CSI REPORTING FOR MULTI-TRP COHERENT JOINT-TRANSMISSION

TECHNICAL FIELD

The present disclosure relates generally to wireless communication systems and, more specifically, the present disclosure relates to channel state information (CSI) reporting for multi-transmit receive point (TRP) coherent joint transmission (CJT) in a wireless communication system.

BACKGROUND

5th generation (5G) or new radio (NR) mobile communications is recently gathering increased momentum with all the worldwide technical activities on the various candidate technologies from industry and academia. The candidate enablers for the 5G/NR mobile communications include massive antenna technologies, from legacy cellular frequency bands up to high frequencies, to provide beamforming gain and support increased capacity, new waveform (e.g., a new radio access technology (RAT)) to flexibly accommodate various services/applications with different requirements, new multiple access schemes to support massive connections, and so on.

SUMMARY

The present disclosure relates to CSI reporting for multi-TRP CJT in a wireless communication system.

In one embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to receive a configuration about a CSI report. The configuration includes information about (i) N_TRPCSI reference signal (CSI-RS) resources, where N_TRP>1, (ii) a parameter codebookType set to type-II-CJT-r18 or type-II-PortSelection-CJT-r18, and (iii) a parameter codebookMode set to model. The UE further includes a processor operably coupled to the transceiver. The processor, based on the configuration, is configured to determine information for the CSI report based on N CSI-RS resources, where N≤N_TRP, partition the CSI report into two parts, a CSI Part 1 and a CSI part 2, and partition the CSI Part 2 into three groups, G0, G1, and G2. The transceiver is further configured to transmit the CSI Part 1 and at least a portion of the CSI Part 2. The group G1 includes an indicator indicating, for each of N−1 CSI-RS resources of the N CSI-RS resources, a frequency-domain (FD) offset d_r∈{0, 1, . . . , N₃O₃−1} relative to a reference CSI-RS resource. Here, r∈{1, . . . , N_TRP}, r≠r*, and r* is an index of the reference CSI-RS resource such that d_r*=0; N₃is a length of each of FD basis vectors; and O₃is an oversampling value.

In another embodiment, a base station (BS) is provided. The BS includes a processor and a transceiver operably coupled to the processor. The transceiver is configured to transmit a configuration about a CSI report. The configuration includes information about (i) N_TRPCSI-RS resources, where N_TRP>1, (ii) a parameter codebookType set to type-II-CJT-r18 or type-II-PortSelection-CJT-r18, and (iii) a parameter codebookMode set to model. The CSI report is based on N CSI-RS resources, where N≤N_TRP. The CSI report includes two parts, a CSI Part 1 and a CSI part 2. The CSI Part 2 includes three groups, G0, G1, and G2. The transceiver is configured to receive the CSI Part 1 and at least a portion of the CSI Part 2. The group G1 includes an indicator indicating, for each of N−1 CSI-RS resources of the N CSI-RS resources, a FD offset d_r∈{0, 1, . . . , N₃O₃−1} relative to a reference CSI-RS resource. Here, r∈{1, . . . , N_TRP}, r≠r*, and r* is an index of the reference CSI-RS resource such that d_r*=0; N₃is a length of each of FD basis vectors; and O₃is an oversampling value.

In yet another embodiment, a method performed by a UE is provided. The method includes receiving a configuration about a CSI report. The configuration includes information about (i) N_TRPCSI-RS resources, where N_TRP>1, (ii) a parameter codebookType set to type-II-CJT-r18 or type-II-PortSelection-CJT-r18, and (iii) a parameter codebookMode set to model. The method further includes, based on the configuration, determining information for the CSI report based on N CSI-RS resources, where N≤N_TRP; partitioning the CSI report into two parts, a CSI Part 1 and a CSI part 2; and partitioning the CSI Part 2 into three groups, G0, G1, and G2. The method further includes transmitting the CSI Part 1 and at least a portion of the CSI Part 2. The group G1 includes an indicator indicating, for each of N−1 CSI-RS resources of the N CSI-RS resources, a frequency-domain (FD) offset d_r∈{0, 1, . . . , N₃O₃− 1} relative to a reference CSI-RS resource. Here, r∈{1, . . . , N_TRP}, r≠r*, and r* is an index of the reference CSI-RS resource such that d_r*=0; N₃is a length of each of FD basis vectors; and O₃is an oversampling value.

Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term “controller” means any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware or a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

FIG. 1 illustrates an example of wireless network according to embodiments of the present disclosure;

FIG. 2 illustrates an example of gNB according to embodiments of the present disclosure;

FIG. 3 illustrates an example of UE according to embodiments of the present disclosure;

FIGS. 4 and 5 illustrate example of wireless transmit and receive paths according to this disclosure;

FIG. 6 illustrates an example of antenna structure according to embodiments of the present disclosure;

FIGS. 7 and 8 illustrate examples of distributed MIMO according to embodiments of the present disclosure;

FIG. 9 illustrates an example of antenna port layout according to embodiments of the present disclosure;

FIG. 10 illustrates an example of 3D grid of DFT vectors according to embodiments of the present disclosure;

FIG. 11 illustrates an example of codebook according to embodiments of the present disclosure;

FIG. 12 illustrates an example of two-part UCI used to multiplex and report CSI according to embodiments of the present disclosure;

FIG. 13 illustrates an example of D-MIMO structure according to embodiments of the present disclosure;

FIG. 14 illustrates an example of channel measurement according to embodiments of the present disclosure;

FIG. 15 illustrates an example of UE moving on a linear trajectory in a DMIMO system according to embodiments of the present disclosure;

FIG. 16 illustrates an example of window-based FD basis vector selection according to embodiments of the present disclosure; and

FIG. 17 illustrates an example method performed by a UE in a wireless communication system according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through 17, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device.

The following documents are hereby incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TS 36.211 v17.2.0, “E-UTRA, Physical channels and modulation”; 3GPP TS 36.212 v17.2.0, “E-UTRA, Multiplexing and Channel coding”; 3GPP TS 36.213 v17.2.0, “E-UTRA, Physical Layer Procedures”; 3GPP TS 36.321 v17.1.0, “E-UTRA, Medium Access Control (MAC) protocol specification”; 3GPP TS 36.331 v17.1.0, “E-UTRA, Radio Resource Control (RRC) Protocol Specification”; 3GPP TS 38.211 v17.2.0, “NR, Physical channels and modulation”; 3GPP TS 38.212 v17.2.0, “NR, Multiplexing and Channel coding”; 3GPP TS 38.213 v17.2.0, “NR, Physical Layer Procedures for Control”; 3GPP TS 38.214 v17.2.0, “NR, Physical Layer Procedures for Data”; 3GPP TS 38.215 v17.1.0, “NR, Physical Layer Measurements”; 3GPP TS 38.321 v17.1.0, “NR, Medium Access Control (MAC) protocol specification”; and 3GPP TS 38.331 v17.1.0, “NR, Radio Resource Control (RRC) Protocol Specification.”

To meet the demand for wireless data traffic having increased since deployment of 4G communication systems and to enable various vertical applications, 5G/NR communication systems have been developed and are currently being deployed. The 5G/NR communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 28 GHz or 60 GHz bands, so as to accomplish higher data rates or in lower frequency bands, such as 6 GHz, to enable robust coverage and mobility support. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G/NR communication systems.

In addition, in 5G/NR communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancelation and the like.

The discussion of 5G systems and frequency bands associated therewith is for reference as certain embodiments of the present disclosure may be implemented in 5G systems. However, the present disclosure is not limited to 5G systems, or the frequency bands associated therewith, and embodiments of the present disclosure may be utilized in connection with any frequency band. For example, aspects of the present disclosure may also be applied to deployment of 5G communication systems, 6G or even later releases which may use terahertz (THz) bands.

FIGS. 1-3 below describe various embodiments implemented in wireless communications systems and with the use of orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques. The descriptions of FIGS. 1-3 are not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably arranged communications system.

FIG. 1 illustrates an example wireless network according to embodiments of the present disclosure. The embodiment of the wireless network shown in FIG. 1 is for illustration only. Other embodiments of the wireless network 100 could be used without departing from the scope of this disclosure.

As shown in FIG. 1, the wireless network includes a gNB 101 (e.g., base station, BS), a gNB 102, and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB 103. The gNB 101 also communicates with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

The gNB 102 provides wireless broadband access to the network 130 for a first plurality of user equipments (UEs) within a coverage area 120 of the gNB 102. The first plurality of UEs includes a UE 111, which may be located in a small business; a UE 112, which may be located in an enterprise; a UE 113, which may be a WiFi hotspot; a UE 114, which may be located in a first residence; a UE 115, which may be located in a second residence; and a UE 116, which may be a mobile device, such as a cell phone, a wireless laptop, a wireless PDA, or the like. The gNB 103 provides wireless broadband access to the network 130 for a second plurality of UEs within a coverage area 125 of the gNB 103. The second plurality of UEs includes the UE 115 and the UE 116. In some embodiments, one or more of the gNBs 101-103 may communicate with each other and with the UEs 111-116 using 5G/NR, long term evolution (LTE), long term evolution-advanced (LTE-A), WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can refer to any component (or collection of components) configured to provide wireless access to a network, such as transmit point (TP), transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a 5G/NR base station (gNB), a macrocell, a femtocell, a WiFi access point (AP), or other wirelessly enabled devices. Base stations may provide wireless access in accordance with one or more wireless communication protocols, e.g., 5G/NR 3^rdgeneration partnership project (3GPP) NR, long term evolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA), Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS” and “TRP” are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, the term “user equipment” or “UE” can refer to any component such as “mobile station,” “subscriber station,” “remote terminal,” “wireless terminal,” “receive point,” or “user device.” For the sake of convenience, the terms “user equipment” and “UE” are used in this patent document to refer to remote wireless equipment that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile telephone or smartphone) or is normally considered a stationary device (such as a desktop computer or vending machine).

Dotted lines show the approximate extents of the coverage areas 120 and 125, which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with gNBs, such as the coverage areas 120 and 125, may have other shapes, including irregular shapes, depending upon the configuration of the gNBs and variations in the radio environment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs 111-116 include circuitry, programing, or a combination thereof, for CSI reporting for multi-TRP CJT. In certain embodiments, and one or more of the gNBs 101-103 includes circuitry, programing, or a combination thereof, to support UCI parameters for CSI reporting for multi-TRP CJT.

Although FIG. 1 illustrates one example of a wireless network, various changes may be made to FIG. 1. For example, the wireless network could include any number of gNBs and any number of UEs in any suitable arrangement. Also, the gNB 101 could communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network 130. Similarly, each gNB 102-103 could communicate directly with the network 130 and provide UEs with direct wireless broadband access to the network 130. Further, the gNBs 101, 102, and/or 103 could provide access to other or additional external networks, such as external telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of the present disclosure. The embodiment of the gNB 102 illustrated in FIG. 2 is for illustration only, and the gNBs 101 and 103 of FIG. 1 could have the same or similar configuration. However, gNBs come in a wide variety of configurations, and FIG. 2 does not limit the scope of this disclosure to any particular implementation of a gNB.

As shown in FIG. 2, the gNB 102 includes multiple antennas 205a-205n, multiple transceivers 210a-210n, a controller/processor 225, a memory 230, and a backhaul or network interface 235.

The transceivers 210a-210n receive, from the antennas 205a-205n, incoming RF signals, such as signals transmitted by UEs in the network 100. The transceivers 210a-210n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in the transceivers 210a-210n and/or controller/processor 225, which generates processed baseband signals by filtering, decoding, and/or digitizing the baseband or IF signals. The controller/processor 225 may further process the baseband signals.

Transmit (TX) processing circuitry in the transceivers 210a-210n and/or controller/processor 225 receives analog or digital data (such as voice data, web data, e-mail, or interactive video game data) from the controller/processor 225. The TX processing circuitry encodes, multiplexes, and/or digitizes the outgoing baseband data to generate processed baseband or IF signals. The transceivers 210a-210n up-converts the baseband or IF signals to RF signals that are transmitted via the antennas 205a-205n.

The controller/processor 225 can include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller/processor 225 could control the reception of UL channel signals and the transmission of DL channel signals by the transceivers 210a-210n in accordance with well-known principles. The controller/processor 225 could support additional functions as well, such as more advanced wireless communication functions. For instance, the controller/processor 225 could support beam forming or directional routing operations in which outgoing/incoming signals from/to multiple antennas 205a-205n are weighted differently to effectively steer the outgoing signals in a desired direction. Any of a wide variety of other functions could be supported in the gNB 102 by the controller/processor 225.

The controller/processor 225 is also capable of executing programs and other processes resident in the memory 230, such as processes to support CSI reporting for multi-TRP CJT. The controller/processor 225 can move data into or out of the memory 230 as required by an executing process.

The controller/processor 225 is also coupled to the backhaul or network interface 235. The backhaul or network interface 235 allows the gNB 102 to communicate with other devices or systems over a backhaul connection or over a network. The interface 235 could support communications over any suitable wired or wireless connection(s). For example, when the gNB 102 is implemented as part of a cellular communication system (such as one supporting 5G/NR, LTE, or LTE-A), the interface 235 could allow the gNB 102 to communicate with other gNBs over a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 235 could allow the gNB 102 to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The interface 235 includes any suitable structure supporting communications over a wired or wireless connection, such as an Ethernet or transceiver.

The memory 230 is coupled to the controller/processor 225. Part of the memory 230 could include a RAM, and another part of the memory 230 could include a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes may be made to FIG. 2. For example, the gNB 102 could include any number of each component shown in FIG. 2. Also, various components in FIG. 2 could be combined, further subdivided, or omitted and additional components could be added according to particular needs.

FIG. 3 illustrates an example UE 116 according to embodiments of the present disclosure. The embodiment of the UE 116 illustrated in FIG. 3 is for illustration only, and the UEs 111-115 of FIG. 1 could have the same or similar configuration. However, UEs come in a wide variety of configurations, and FIG. 3 does not limit the scope of this disclosure to any particular implementation of a UE.

As shown in FIG. 3, the UE 116 includes antenna(s) 305, a transceiver(s) 310, and a microphone 320. The UE 116 also includes a speaker 330, a processor 340, an input/output (I/O) interface (IF) 345, an input 350, a display 355, and a memory 360. The memory 360 includes an operating system (OS) 361 and one or more applications 362.

The transceiver(s) 310 receives, from the antenna 305, an incoming RF signal transmitted by a gNB of the network 100. The transceiver(s) 310 down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by RX processing circuitry in the transceiver(s) 310 and/or processor 340, which generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuitry sends the processed baseband signal to the speaker 330 (such as for voice data) or is processed by the processor 340 (such as for web browsing data).

TX processing circuitry in the transceiver(s) 310 and/or processor 340 receives analog or digital voice data from the microphone 320 or other outgoing baseband data (such as web data, e-mail, or interactive video game data) from the processor 340. The TX processing circuitry encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceiver(s) 310 up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna(s) 305.

The processor 340 can include one or more processors or other processing devices and execute the OS 361 stored in the memory 360 in order to control the overall operation of the UE 116. For example, the processor 340 could control the reception of DL channel signals and the transmission of UL channel signals by the transceiver(s) 310 in accordance with well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes and programs resident in the memory 360, such as processes for CSI reporting for multi-TRP CJT.

The processor 340 can move data into or out of the memory 360 as required by an executing process. In some embodiments, the processor 340 is configured to execute the applications 362 based on the OS 361 or in response to signals received from gNBs or an operator. The processor 340 is also coupled to the I/O interface 345, which provides the UE 116 with the ability to connect to other devices, such as laptop computers and handheld computers. The I/O interface 345 is the communication path between these accessories and the processor 340.

The processor 340 is also coupled to the input 350 and the display 355m which includes for example, a touchscreen, keypad, etc., The operator of the UE 116 can use the input 350 to enter data into the UE 116. The display 355 may be a liquid crystal display, light emitting diode display, or other display capable of rendering text and/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360 could include a random-access memory (RAM), and another part of the memory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes may be made to FIG. 3. For example, various components in FIG. 3 could be combined, further subdivided, or omitted and additional components could be added according to particular needs. As a particular example, the processor 340 could be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In another example, the transceiver(s) 310 may include any number of transceivers and signal processing chains and may be connected to any number of antennas. Also, while FIG. 3 illustrates the UE 116 configured as a mobile telephone or smartphone, UEs could be configured to operate as other types of mobile or stationary devices.

FIG. 4 and FIG. 5 illustrate example wireless transmit and receive paths according to this disclosure. In the following description, a transmit path 400 may be described as being implemented in a gNB (such as the gNB 102), while a receive path 500 may be described as being implemented in a UE (such as a UE 116). However, it may be understood that the receive path 500 can be implemented in a gNB and that the transmit path 400 can be implemented in a UE. In some embodiments, the transmit path 400 is configured to support CSI reporting for multi-TRP CJT.

The transmit path 400 as illustrated in FIG. 4 includes a channel coding and modulation block 405, a serial-to-parallel (S-to-P) block 410, a size N inverse fast Fourier transform (IFFT) block 415, a parallel-to-serial (P-to-S) block 420, an add cyclic prefix block 425, and an up-converter (UC) 430. The receive path 500 as illustrated in FIG. 5 includes a downconverter (DC) 555, a remove cyclic prefix block 560, a serial-to-parallel (S-to-P) block 565, a size N fast Fourier transform (FFT) block 570, a parallel-to-serial (P-to-S) block 575, and a channel decoding and demodulation block 580.

As illustrated in FIG. 4, the channel coding and modulation block 405 receives a set of information bits, applies coding (such as a low-density parity check (LDPC) coding), and modulates the input bits (such as with quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency-domain modulation symbols.

The serial-to-parallel block 410 converts (such as de-multiplexes) the serial modulated symbols to parallel data in order to generate N parallel symbol streams, where N is the IFFT/FFT size used in the gNB 102 and the UE 116. The size N IFFT block 415 performs an IFFT operation on the N parallel symbol streams to generate time-domain output signals. The parallel-to-serial block 420 converts (such as multiplexes) the parallel time-domain output symbols from the size N IFFT block 415 in order to generate a serial time-domain signal. The add cyclic prefix block 425 inserts a cyclic prefix to the time-domain signal. The up-converter 430 modulates (such as up-converts) the output of the add cyclic prefix block 425 to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to the RF frequency.

A transmitted RF signal from the gNB 102 arrives at the UE 116 after passing through the wireless channel, and reverse operations to those at the gNB 102 are performed at the UE 116.

As illustrated in FIG. 5, the downconverter 555 down-converts the received signal to a baseband frequency, and the remove cyclic prefix block 560 removes the cyclic prefix to generate a serial time-domain baseband signal. The serial-to-parallel block 565 converts the time-domain baseband signal to parallel time domain signals. The size N FFT block 570 performs an FFT algorithm to generate N parallel frequency-domain signals. The parallel-to-serial block 575 converts the parallel frequency-domain signals to a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

Each of the gNBs 101-103 may implement a transmit path 400 as illustrated in FIG. 4 that is analogous to transmitting in the downlink to UEs 111-116 and may implement a receive path 500 as illustrated in FIG. 5 that is analogous to receiving in the uplink from UEs 111-116. Similarly, each of UEs 111-116 may implement the transmit path 400 for transmitting in the uplink to the gNBs 101-103 and may implement the receive path 500 for receiving in the downlink from the gNBs 101-103.

Each of the components in FIG. 4 and FIG. 5 can be implemented using only hardware or using a combination of hardware and software/firmware. As a particular example, at least some of the components in FIG. 4 and FIG. 5 may be implemented in software, while other components may be implemented by configurable hardware or a mixture of software and configurable hardware. For instance, the FFT block 570 and the IFFT block 415 may be implemented as configurable software algorithms, where the value of size N may be modified according to the implementation.

Furthermore, although described as using FFT and IFFT, this is by way of illustration only and may not be construed to limit the scope of this disclosure. Other types of transforms, such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions, can be used. It may be appreciated that the value of the variable N may be any integer number (such as 1, 2, 3, 4, or the like) for DFT and IDFT functions, while the value of the variable N may be any integer number that is a power of two (such as 1, 2, 4, 8, 16, or the like) for FFT and IFFT functions.

Although FIG. 4 and FIG. 5 illustrate examples of wireless transmit and receive paths, various changes may be made to FIG. 4 and FIG. 5. For example, various components in FIG. 4 and FIG. 5 can be combined, further subdivided, or omitted and additional components can be added according to particular needs. Also, FIG. 4 and FIG. 5 are meant to illustrate examples of the types of transmit and receive paths that can be used in a wireless network. Any other suitable architectures can be used to support wireless communications in a wireless network.

A unit for DL signaling or for UL signaling on a cell is referred to as a slot and can include one or more symbols. A bandwidth (BW) unit is referred to as a resource block (RB). One RB includes a number of sub-carriers (SCs). For example, a slot can have duration of one millisecond and an RB can have a bandwidth of 180 KHz and include 12 SCs with inter-SC spacing of 15 KHz. A slot can be either full DL slot, or full UL slot, or hybrid slot similar to a special subframe in time division duplex (TDD) systems.

DL signals include data signals conveying information content, control signals conveying DL control information (DCI), and reference signals (RS) that are also known as pilot signals. A gNB transmits data information or DCI through respective physical DL shared channels (PDSCHs) or physical DL control channels (PDCCHs). A PDSCH or a PDCCH can be transmitted over a variable number of slot symbols including one slot symbol. A UE can be indicated a spatial setting for a PDCCH reception based on a configuration of a value for a TCI state of a CORESET where the UE receives the PDCCH. The UE can be indicated a spatial setting for a PDSCH reception based on a configuration by higher layers or based on an indication by a DCI format scheduling the PDSCH reception of a value for a TCI state. The gNB can configure the UE to receive signals on a cell within a DL bandwidth part (BWP) of the cell DL BW.

A gNB transmits one or more of multiple types of RS including channel state information RS (CSI-RS) and demodulation RS (DMRS). A CSI-RS is primarily intended for UEs to perform measurements and provide channel state information (CSI) to a gNB. For channel measurement, non-zero power CSI-RS (NZP CSI-RS) resources are used. For interference measurement reports (IMRs), CSI interference measurement (CSI-IM) resources associated with a zero power CSI-RS (ZP CSI-RS) configuration are used. A CSI process consists of NZP CSI-RS and CSI-IM resources. A UE can determine CSI-RS transmission parameters through DL control signaling or higher layer signaling, such as an RRC signaling from a gNB. Transmission instances of a CSI-RS can be indicated by DL control signaling or configured by higher layer signaling. A DMRS is transmitted only in the BW of a respective PDCCH or PDSCH and a UE can use the DMRS to demodulate data or control information.

UL signals also include data signals conveying information content, control signals conveying UL control information (UCI), DMRS associated with data or UCI demodulation, sounding RS (SRS) enabling a gNB to perform UL channel measurement, and a random access (RA) preamble enabling a UE to perform random access. A UE transmits data information or UCI through a respective physical UL shared channel (PUSCH) or a physical UL control channel (PUCCH). A PUSCH or a PUCCH can be transmitted over a variable number of slot symbols including one slot symbol. The gNB can configure the UE to transmit signals on a cell within an UL BWP of the cell UL BW.

UCI includes hybrid automatic repeat request acknowledgement (HARQ-ACK) information, indicating correct or incorrect detection of data transport blocks (TBs) in a PDSCH, scheduling request (SR) indicating whether a UE has data in the buffer of UE, and CSI reports enabling a gNB to select appropriate parameters for PDSCH or PDCCH transmissions to a UE. HARQ-ACK information can be configured to be with a smaller granularity than per TB and can be per data code block (CB) or per group of data CBs where a data TB includes a number of data CBs.

A CSI report from a UE can include a channel quality indicator (CQI) informing a gNB of a largest modulation and coding scheme (MCS) for the UE to detect a data TB with a predetermined block error rate (BLER), such as a 10% BLER, of a precoding matrix indicator (PMI) informing a gNB how to combine signals from multiple transmitter antennas in accordance with a MIMO transmission principle, and of a rank indicator (RI) indicating a transmission rank for a PDSCH. UL RS includes DMRS and SRS. DMRS is transmitted only in a BW of a respective PUSCH or PUCCH transmission. A gNB can use a DMRS to demodulate information in a respective PUSCH or PUCCH. SRS is transmitted by a UE to provide a gNB with an UL CSI and, for a TDD system, an SRS transmission can also provide a PMI for DL transmission. Additionally, in order to establish synchronization or an initial higher layer connection with a gNB, a UE can transmit a physical random-access channel.

In the present disclosure, a beam is determined by either of: (1) a TCI state, which establishes a quasi-colocation (QCL) relationship between a source reference signal (e.g., synchronization signal/physical broadcasting channel (PBCH) block (SSB) and/or CSI-RS) and a target reference signal; or (2) spatial relation information that establishes an association to a source reference signal, such as SSB or CSI-RS or SRS. In either case, the ID of the source reference signal identifies the beam.

The TCI state and/or the spatial relation reference RS can determine a spatial Rx filter for reception of downlink channels at the UE, or a spatial Tx filter for transmission of uplink channels from the UE.

Rel.14 LTE and Rel.15 NR support up to 32 CSI-RS antenna ports which enable an eNB to be equipped with a large number of antenna elements (such as 64 or128). In this case, a plurality of antenna elements is mapped onto one CSI-RS port. For mmWave bands, although the number of antenna elements can be larger for a given form factor, the number of CSI-RS ports—which can correspond to the number of digitally precoded ports—tends to be limited due to hardware constraints (such as the feasibility to install a large number of ADCs/DACs at mmWave frequencies) as illustrated in FIG. 6.

FIG. 6 illustrates an example antenna structure 600 according to embodiments of the present disclosure. An embodiment of the antenna structure 600 shown in FIG. 6 is for illustration only.

In this case, one CSI-RS port is mapped onto a large number of antenna elements which can be controlled by a bank of analog phase shifters 601. One CSI-RS port can then correspond to one sub-array which produces a narrow analog beam through analog beamforming 605. This analog beam can be configured to sweep across a wider range of angles 620 by varying the phase shifter bank across symbols or subframes. The number of sub-arrays (equal to the number of RF chains) is the same as the number of CSI-RS ports N_CSI-PORT. A digital beamforming unit 610 performs a linear combination across N_CSI-PORTanalog beams to further increase precoding gain. While analog beams are wideband (hence not frequency-selective), digital precoding can be varied across frequency sub-bands or resource blocks. Receiver operation can be conceived analogously.

Since the aforementioned system utilizes multiple analog beams for transmission and reception (wherein one or a small number of analog beams are selected out of a large number, for instance, after a training duration—to be performed from time to time), the term “multi-beam operation” is used to refer to the overall system aspect. This includes, for the purpose of illustration, indicating the assigned DL or UL TX beam (also termed “beam indication”), measuring at least one reference signal for calculating and performing beam reporting (also termed “beam measurement” and “beam reporting,” respectively), and receiving a DL or UL transmission via a selection of a corresponding RX beam.

The aforementioned system is also applicable to higher frequency bands such as >52.6 GHz. In this case, the system can employ only analog beams. Due to the O2 absorption loss around 60 GHz frequency (˜10 dB additional loss @100 m distance), larger number of and sharper analog beams (hence larger number of radiators in the array) may be needed to compensate for the additional path loss.

For a cellular system operation in a sub-1 GHz frequency range (e.g., less than 1 GHz), supporting large number of CSI-RS antenna ports (e.g., 32) at a single location or remote radio head (RRH) or TRP is challenging due to that a larger antenna form factor size is needed at these frequencies than a system operating at a higher frequency such as 2 GHz or4 GHz. At such low frequencies, the maximum number of CSI-RS antenna ports that can be co-located at a single site (or TRP/RRH) can be limited, for example to 8. This limits the spectral efficiency of such systems. In particular, the MU-MIMO spatial multiplexing gains offered due to large number of CSI-RS antenna ports (such as 32) cannot be achieved.

One way to operate a sub-1 GHz system with large number of CSI-RS antenna ports is based on distributing antenna ports at multiple locations (or TRP/RRHs). The multiple sites or TRPs/RRHs can still be connected to a single (common) base unit, hence the signal transmitted/received via multiple distributed TRPs/RRHs can still be processed at a centralized location. This is called distributed MIMO or multi-TRP coherent joint transmission (C-JT).

This disclosure considers two-part CSI or UCI framework for multi-TRP C-JT scenarios and provides method and apparatus for UCI parameters for CSI Part 1 and CSI Part 2 CSI in multi-TRP C-JT scenarios.

The present disclosure relates to electronic devices and methods on CSI reporting for MIMO operations, more particularly, to electronic devices and methods on two-part UCI (or CSI) for distributed MIMO or multi-TRP operations in wireless networks.

CSI enhancement described in Rel-18 MIMO considers Rel-16/17 Type-II CSI codebook refinements to support mTRP coherent joint transmission (C-JT) operations by considering performance-and-overhead trade-off. The Rel-16/17 Type-II CSI codebook has three components W₁, W₂, and W_f, and the Rel-18 Type-II CSI codebook for CJT has been developing based on the Rel-16/17 Type-II CSI codebooks, which is associated with multiple CSI-RS resources (multiple TRPs). Therefore, CSI includes elements associated with multiple TRPs (or CSI-RS resources), and thus the legacy framework of two-part CSI or two-part UCI needs to be enhanced for further efficient CSI reporting to be tailored for Rel-18 Type-II CSI framework.

In this disclosure, a component for UCI or CSI parameters in two-part CSI or two-part UCI is provided for multi-TRP C-JT scenarios.

Although the focus of the present disclosure is on 3GPP 5G NR communication systems, various embodiments may apply in general to UEs operating with other RATs and/or standards, such as different releases/generations of 3GPP standards (including beyond 5G, 6G, and so on), IEEE standards (such as 802.16 WiMAX and 802.11 Wi-Fi), and so on.

At lower frequency bands such as <1 GHz, on the other hand, the number of antenna elements may not be large in a given form factor due to the large wavelength. As an example, for the case of the wavelength size (7) of the center frequency 600 MHz (which is 50 cm), it desires 4 m for uniform-linear-array (ULA) antenna panel of 16 antenna elements with the half-wavelength distance between two adjacent antenna elements. Considering a plurality of antenna elements is mapped to one digital port in practical cases, the desirable size for antenna panel(s) at gNB to support a large number of antenna ports such as 32 CSI-RS ports becomes very large in such low frequency bands, and it leads the difficulty of deploying 2-D antenna element arrays within the size of a conventional form factor. This results in a limited number of CSI-RS ports that can be supported at a single site and limits the spectral efficiency of such systems.

One possible approach to resolving the issue is to form multiple TRPs (multi-TRP) or RRHs with a small number of antenna ports instead of integrating all of the antenna ports in a single panel (or at a single site) and to distribute the multiple panels in multiple locations/sites (or TRPs, RRHs). This approach, concept of distributed MIMO (D-MIMO), is shown in FIG. 7.

FIGS. 7 and 8 illustrate examples of distributed MIMO 700 and 800 according to embodiments of the present disclosure. An embodiment of the distributed MIMO 700 and 800 shown in FIG. 8 are for illustration only.

The multiple TRPs at multiple locations can still be connected to a single base unit, and thus the signal transmitted/received via multiple distributed TRPs can be processed in a centralized manner through the single base unit, as illustrated in FIG. 8.

Note that although low frequency band systems (sub-1 GHz band) are provided as a motivation for distributed MIMO (or mTRP), the distributed MIMO technology is frequency-band-agnostic and can be useful in mid-(sub-6 GHz) and high-band (above-6 GHz) systems in addition to low-band (sub-1 GHz) systems.

The terminology “distributed MIMO” is used as an illustrative purpose, it can be considered under another terminology such as multi-TRP, mTRP, cell-free network, and so on.

All the following components and embodiments are applicable for UL transmission with CP-OFDM (cyclic prefix OFDM) waveform as well as DFT-SOFDM (DFT-spread OFDM) and SC-FDMA (single-carrier FDMA) waveforms. Furthermore, all the following components and embodiments are applicable for UL transmission when the scheduling unit in time is either one subframe (which can consist of one or multiple slots) or one slot.

In the present disclosure, the frequency resolution (reporting granularity) and span (reporting bandwidth) of CSI reporting can be defined in terms of frequency “subbands” and “CSI reporting band” (CRB), respectively.

A subband for CSI reporting is defined as a set of contiguous PRBs which represents the smallest frequency unit for CSI reporting. The number of PRBs in a subband can be fixed for a given value of DL system bandwidth, configured either semi-statically via higher-layer/RRC signaling, or dynamically via L1 DL control signaling or MAC control element (MAC CE). The number of PRBs in a subband can be included in CSI reporting setting.

A “CSI reporting band” is defined as a set/collection of subbands, either contiguous or non-contiguous, wherein CSI reporting is performed. For example, CSI reporting band can include all the subbands within the DL system bandwidth. This can also be termed “full-band.” Alternatively, CSI reporting band can include only a collection of subbands within the DL system bandwidth. This can also be termed “partial band.”

The term “CSI reporting band” is used only as an example for representing a function. Other terms such as “CSI reporting subband set” or “CSI reporting bandwidth” or bandwidth part (BWP) can also be used.

In terms of UE configuration, a UE can be configured with at least one CSI reporting band. This configuration can be semi-static (via higher-layer signaling or RRC) or dynamic (via MAC CE or L1 DL control signaling). When configured with multiple (N) CSI reporting bands (e.g., via RRC signaling), a UE can report CSI associated with n<N CSI reporting bands. For instance, >6 GHz, large system bandwidth may desire multiple CSI reporting bands. The value of n can either be configured semi-statically (via higher-layer signaling or RRC) or dynamically (via MAC CE or L1 DL control signaling). Alternatively, the UE can report a recommended value of n via an UL channel.

Therefore, a CSI parameter frequency granularity can be defined per CSI reporting band as follows. A CSI parameter is configured with “single” reporting for the CSI reporting band with M_nsubbands when one CSI parameter for all the M_nsubbands within the CSI reporting band. A CSI parameter is configured with “subband” for the CSI reporting band with M_nsubbands when one CSI parameter is reported for each of the M_nsubbands within the CSI reporting band.

FIG. 9 illustrates an example of antenna port layout 900 according to embodiments of the present disclosure. An embodiment of the antenna port layout 900 shown in FIG. 9 is for illustration only.

In the following, it may assume that N₁and N₂are the number of antenna ports with the same polarization in the first and second dimensions, respectively. For2D antenna port layouts, there may be N₁>1, N₂>1, and for1D antenna port layouts N₁>1 and N₂=1. So, for a dual-polarized antenna port layout, the total number of antenna ports is 2N₁N₂when each antenna maps to an antenna port. An illustration is shown in FIG. 9 where “X” represents two antenna polarizations. In this disclosure, the term “polarization” refers to a group of antenna ports. For example, antenna ports

$j = X + 0, X + 1, \dots, X + \frac{P_{CSIRS}}{2} - 1$

comprise a first antenna polarization, and antenna ports

$j = X + \frac{P_{CSIRS}}{2}, X + \frac{P_{CSIRS}}{2} + 1, \dots, X + P_{CSIRS} - 1$

comprise a second antenna polarization, where P_CSIRSis a number of CSI-RS antenna ports and X is a starting antenna port number (e.g., X=3000, then antenna ports are 3000, 3001, 3002, . . . ). Let N_gbe a number of antenna panels at the gNB. When there are multiple antenna panels (N_g>1), it may assume that each panel is dual-polarized antenna ports with N₁and N₂ports in two dimensions. This is illustrated in FIG. 9 Note that the antenna port layouts may or may not be the same in different antenna panels.

In one example, the antenna architecture of a D-MIMO or CJT (coherent joint-transmission) system is structured. For example, the antenna structure at each RRH (or TRP) is dual-polarized (single or multi-panel as shown in FIG. 9. The antenna structure at each RRH/TRP can be the same. Or the antenna structure at an RRH/TRP can be different from another RRH/TRP. Likewise, the number of ports at each RRH/TRP can be the same. Or the number of ports at one RRH/TRP can be different from another RRH/TRP. In one example, N_g=N_RRH, a number of RRHs/TRPs in the D-MIMO transmission.

In another example, the antenna architecture of a D-MIMO or CJT system is unstructured. For example, the antenna structure at one RRH/TRP can be different from another RRH/TRP.

It may assume a structured antenna architecture in the rest of the disclosure. For simplicity, it may assume each RRH/TRP is equivalent to a panel (cf. FIG. 9), although, an RRH/TRP can have multiple panels in practice. The disclosure however is not restrictive to a single panel assumption at each RRH/TRP and can easily be extended (covers) the case when an RRH/TRP has multiple antenna panels.

In one embodiment, an RRH constitutes (or corresponds to or is equivalent to or is associated with) at least one of the following examples.

In one example, an RRH corresponds to a TRP.

In one example, an RRH or TRP corresponds to a CSI-RS resource. A UE is configured with K=N_RRH=(N_TRP)>1 non-zero-power (NZP) CSI-RS resources, and a CSI reporting is configured to be across multiple CSI-RS resources. This is similar to Class B, K>1 configuration in Rel. 14 LTE. The K NZP CSI-RS resources can belong to a CSI-RS resource set or multiple CSI-RS resource sets (e.g., K resource sets each comprising one CSI-RS resource). The details are as explained earlier in this disclosure.

In one example, an RRH or TRP corresponds to a CSI-RS resource group, where a group comprises one or multiple NZP CSI-RS resources. A UE is configured with K≥N_RRH>1 non-zero-power (NZP) CSI-RS resources, and a CSI reporting is configured to be across multiple CSI-RS resources from resource groups. This is similar to Class B, K>1 configuration in Rel. 14 LTE. The K NZP CSI-RS resources can belong to a CSI-RS resource set or multiple CSI-RS resource sets (e.g., K resource sets each comprising one CSI-RS resource). The details are as explained earlier in this disclosure. In particular, the K CSI-RS resources can be partitioned into N_RRHresource groups. The information about the resource grouping can be provided together with the CSI-RS resource setting/configuration, or with the CSI reporting setting/configuration, or with the CSI-RS resource configuration.

In one example, an RRH or TRP corresponds to a subset (or a group) of CSI-RS ports. A UE is configured with at least one NZP CSI-RS resource comprising (or associated with) CSI-RS ports that can be grouped (or partitioned) multiple subsets/groups/parts of antenna ports, each corresponding to (or constituting) an RRH/TRP. The information about the subsets of ports or grouping of ports can be provided together with the CSI-RS resource setting/configuration, or with the CSI reporting setting/configuration, or with the CSI-RS resource configuration.

In one example, an RRH or TRP corresponds to examples disclosed in the present disclosure depending on a configuration. For example, this configuration can be explicit via a parameter (e.g., an RRC parameter). Or the configuration can be implicit.

In one example, when implicit, it could be based on the value of K. For example, when K>1 CSI-RS resources, an RRH corresponds to example provided in the present disclosure, and when K=1 CSI-RS resource, an RRH corresponds to example provided in the present disclosure.

In another example, the configuration could be based on the configured codebook. For example, an RRH corresponds to a CSI-RS resource (e.g., example provided in the present disclosure) or resource group (e.g., examples as provided in the present disclosure) when the codebook corresponds to a decoupled codebook (modular or separate codebook for each RRH), and an RRH corresponds to a subset (or a group) of CSI-RS ports (e.g., example as provided in the present disclosure) when codebook corresponds to a coupled (joint or coherent) codebook (one joint codebook across TRPs/RRHs).

In one example, when RRH or TRP maps (or corresponds to) a CSI-RS resource or resource group (e.g., example as provided in the present disclosure), and a UE can select a subset of TRPs/RRHs (resources or resource groups) and report the CSI for the selected TRPs/RRHs (resources or resource groups), the selected TRPs/RRHs can be reported via an indicator. For example, the indicator can be a CRI or a PMI (component) or a new indicator.

In one example, when RRH or TRP maps (or corresponds to) a CSI-RS port group (e.g., example as provided in the present disclosure), and a UE can select a subset of TRPs/RRHs (port groups) and report the CSI for the selected TRPs/RRHs (port groups), the selected TRPs/RRHs can be reported via an indicator. For example, the indicator can be a CRI or a PMI (component) or a new indicator.

In one example, when multiple (K>1) CSI-RS resources are configured for N_RRHTRPs/RRHs (e.g., examples as provided in the present disclosure), a decoupled (modular) codebook is used/configured, and when a single (K=1) CSI-RS resource for N_RRHTRPs/RRHs (e.g., examples as provided in the present disclosure), a joint codebook is used/configured.

As described in U.S. Pat. No. 10,659,118, which is incorporated herein by reference in its entirety, a UE is configured with high-resolution (e.g., Type II) CSI reporting in which the linear combination based Type II CSI reporting framework is extended to include frequency dimension in addition to the 1st and 2nd antenna port dimensions. An illustration of the 3D grid of the oversampled DFT vectors (1st port dim., 2nd port dim., freq. dim.) is shown in FIG. 10 in which: (1) 1st dimension is associated with the 1st port dimension, (2) 2nd dimension is associated with the 2nd port dimension, and (3) 3rd dimension is associated with the frequency dimension.

FIG. 10 illustrates an example of 3D grid of DFT vectors 1000 according to embodiments of the present disclosure. An embodiment of the 3D grid of DFT vectors 1000 shown in FIG. 10 is for illustration only.

The basis sets for1^stand 2^ndport domain representation are oversampled DFT codebooks of length-N₁and length-N₂, respectively, and with oversampling factors O₁and O₂, respectively. Likewise, the basis set for frequency domain representation (i.e., 3rd dimension) is an oversampled DFT codebook of length-N₃and with oversampling factor O₃. In one example, O₁=O₂=O₃=4. In one example, O₁=O₂=4 and 03=1. In another example, the oversampling factors O₁belongs to {2, 4, 8}. In yet another example, at least one of O₁, O₂, and O₃is higher layer configured (via RRC signaling).

As explained in 3GPP standard specification TS38.213, a UE is configured with higher layer parameter codebookType set to “typeII-PortSelection-r16” for an enhanced Type II CSI reporting in which the pre-coders for all SBs and for a given layer l=1, . . . , v, where v is the associated RI value, is given by either:

$\begin{matrix} W^{l} = {AC}_{l} B^{H} = [\begin{matrix} a_{0} & a_{1} & \dots & a_{L - 1} \end{matrix}] [\begin{matrix} c_{l, 0, 0} & c_{l, 0, 1} & \dots & c_{l, 0, M - 1} \\ c_{l, 1, 0} & c_{l, 1, 1} & \dots & c_{l, 1, M - 1} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ c_{l, L - 1, 0} & c_{l, L - 1, 1} & \dots & c_{l, L - 1, M - 1} \end{matrix}] {[\begin{matrix} b_{0} & b_{1} & \dots & b_{M - 1} \end{matrix}]}^{H} ⁠ = Σ_{f = 0}^{M - 1} Σ_{i = 0}^{L - 1} c_{l, i, f} (a_{i} b_{f}^{H}) = Σ_{i = 0}^{L - 1} Σ_{f = 0}^{M - 1} c_{l, i, f} (a_{i} b_{f}^{H}) & (Eq . 1) \end{matrix}$

$or$

$\begin{matrix} W^{l} = [\begin{matrix} A & 0 \\ 0 & A \end{matrix}] C_{l} B^{H} = [⁠ \begin{matrix} \begin{matrix} a_{0} & a_{1} & \dots & a_{L - 1} \end{matrix} & 0 \\ 0 & \begin{matrix} a_{0} & a_{1} & \dots & a_{L - 1} \end{matrix} \end{matrix}] {[⁠ \begin{matrix} c_{l, 0, 0} & c_{l, 0, 1} & \dots & c_{l, 0, M - 1} \\ c_{l, 1, 0} & c_{l, 1, 1} & \dots & c_{l, 1, M - 1} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ c_{l, L - 1, 0} & c_{l, L - 1, 1} & \dots & c_{l, L - 1, M - 1} \end{matrix}] ⁠ [\begin{matrix} b_{0} & b_{1} & \dots & b_{M - 1} \end{matrix}]}^{H} = [⁠ \begin{matrix} Σ_{f = 0}^{M - 1} Σ_{i = 0}^{L - 1} c_{l, i, f} (a_{i} b_{f}^{H}) \\ Σ_{f = 0}^{M - 1} Σ_{i = 0}^{L - 1} c_{l, i + L, f} (a_{i} b_{f}^{H}) \end{matrix}] & (Eq . 2) \end{matrix}$

In such equations: (1) N₁is a number of antenna ports in a first antenna port dimension (having the same antenna polarization), (2) N₂is a number of antenna ports in a second antenna port dimension (having the same antenna polarization, (3) P_CSI-RSis a number of CSI-RS ports configured to the UE, (4) N₃is a number of SBs for PMI reporting or number of FD units or number of FD components (that comprise the CSI reporting band) or a total number of precoding matrices indicated by the PMI (one for each FD unit/component), (5) a_iis a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector, or a_iis a P_CSIRS×1 (Eq. 1) or

$\frac{P_{CSIRS}}{2} \times 1$

port selection column vector, where a port selection vector is a defined as a vector which contains a value of 1 in one element and zeros elsewhere, (6) b_fis a N₃×1 column vector, and (7) c_l,i,fis a complex coefficient.

In a variation, when the UE reports a subset K<2LM coefficients (where K is either fixed, configured by the gNB or reported by the UE), then the coefficient c_l,i,fin precoder equations Eq. 1 or Eq. 2 is replaced with x_l,i,f×c_l,i,f, where: (1) x_l,i,f=1 if the coefficient c_l,i,fis reported by the UE according to some embodiments of the present disclosure, and (2) x_l,i,f=0 otherwise (i.e., c_l,i,fis not reported by the UE).

The indication whether x_l,i,f=1 or0 is according to some embodiments of the present disclosure. For example, the indication can be via a bitmap.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectively generalized to

$\begin{matrix} W^{l} = Σ_{i = 0}^{L - 1} Σ_{f = 0}^{M_{i} - 1} c_{l, i, f} (a_{i} b_{i, f}^{H}) & (Eq . 3) \end{matrix}$

$and$

$\begin{matrix} W^{l} = [\begin{matrix} Σ_{i = 0}^{L - 1} Σ_{f = 0}^{M_{i} - 1} c_{l, i, f} (a_{i} b_{i, f}^{H}) \\ Σ_{i = 0}^{L - 1} Σ_{= 0}^{M_{i} - 1} c_{l, i + L, f} (a_{i} b_{i, f}^{H}) \end{matrix}] & (Eq . 4) \end{matrix}$

where for a given i, the number of basis vectors is M_iand the corresponding basis vectors are {b_i,f}. Note that M_iis the number of coefficients c_l,i,freported by the UE for a given i, where M_i≤M (where {M_i} or ΣM_iis either fixed, configured by the gNB or reported by the UE).

The columns of W^lare normalized to norm one. For rank R or R layers (v=R), the pre-coding matrix is given by

$W^{(R)} = \frac{1}{\sqrt{R}} [\begin{matrix} W^{1} & W^{2} & \dots & W^{R} \end{matrix}] .$

Eq. 2 is assumed in the rest of the disclosure. The embodiments of the disclosure, however, are general and are also application to Eq. 1, Eq. 3, and Eq. 4.

Here

$L \leq \frac{P_{CSI - RS}}{2}$

$and$

$M \leq N_{3} .$

$If$

$L = \frac{P_{CSI - RS}}{2},$

then A is an identity matrix, and hence not reported. Likewise, if M=N₃, then B is an identity matrix, and hence not reported. Assuming M<N₃, in an example, to report columns of B, the oversampled DFT codebook is used. For instance, b_f=w_f, where the quantity w_fis given by

$W_{f} = {[\begin{matrix} 1 & e^{j \frac{2 π n_{3, l}^{(f)}}{O_{3} N_{3}}} e^{j \frac{2 π \cdot 2 n_{3, l}^{(f)}}{O_{3} N_{3}}} & \dots & e^{j \frac{2 π \cdot (N_{3} - 1) n_{3, l}^{(f)}}{O_{3} N_{3}}} \end{matrix}]}^{T} .$

When O₃=1, the FD basis vector for layer l∈{1, . . . , v} (where v is the RI or rank value) is given by w_f=[y_0,l^(f), y_1,l^(f). . . y_N₃_−1,l^(f)]^T, where

$y_{t, l}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}}$

and n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M-1)] where n_3,l^(f)∈{0, 1, . . . , N₃−1}.

In another example, discrete cosine transform DCT basis is used to construct/report basis B for the 3^rddimension. The m-th column of the DCT compression matrix is simply given by

${[W_{f}]}_{n m} = {\begin{matrix} \frac{1}{\sqrt{K}}, n = 0 \\ \sqrt{\frac{2}{K}} \cos \frac{π (2 m + 1) n}{2 K}, n = 1, \dots K - 1 \end{matrix}, and K = N_{3}, and m = 0, \dots, N_{3} - 1.$

Since DCT is applied to real valued coefficients, the DCT is applied to the real and imaginary components (of the channel or channel eigenvectors) separately. Alternatively, the DCT is applied to the magnitude and phase components (of the channel or channel eigenvectors) separately. The use of DFT or DCT basis is for illustration purpose only. The disclosure is applicable to any other basis vectors to construct/report A and B.

On a high level, a precoder W^lcan be described as follows:

$\begin{matrix} W = A_{l} C_{l} B_{l}^{H} = W_{1} {\tilde{W}}_{2} W_{f}^{H}, & (Eq . 5) \end{matrix}$

where A=W₁corresponds to the Rel. 15 W₁in Type II CSI codebook as shown in 3GPP standard specification, and B=W_f.

The C_l={tilde over (W)}₂matrix consists of all the required linear combination coefficients (e.g., amplitude and phase or real or imaginary). Each reported coefficient (c_l,i,f=p_l,i,fϕ_l,i,f) in {tilde over (W)}₂is quantized as amplitude coefficient (p_l,i,f) and phase coefficient (ϕ_l,i,f). In one example, the amplitude coefficient (p_l,i,f) is reported using a A-bit amplitude codebook where A belongs to {2, 3, 4}. If multiple values for A are supported, then one value is configured via higher layer signaling.

In another example, the amplitude coefficient (p_l,i,f) is reported as p_l,i,f=p_l,i,f⁽¹⁾, p_l,i,f⁽²⁾) where: (1) p_l,i,f⁽¹⁾is a reference or first amplitude which is reported using a A1-bit amplitude codebook where A1 belongs to {2, 3, 4}, and (2) pf is a differential or second amplitude which is reported using a A2-bit amplitude codebook where A2<A1 belongs to {2, 3, 4}.

For layer l, let us denote the linear combination (LC) coefficient associated with spatial domain (SD) basis vector (or beam) i∈{0, 1, . . . , 2L−1} and frequency domain (FD) basis vector (or beam) f∈{0, 1, . . . , M−1} as c_l,i,f, and the strongest coefficient as c_l,i*,f. The strongest coefficient is reported out of the K_NZnon-zero (NZ) coefficients that is reported using a bitmap, where K_NZ≤K₀=┌β×2LM┐<2LM and β is higher layer configured. The remaining 2LM−K_NZcoefficients that are not reported by the UE are assumed to be zero.

The following quantization scheme is used to quantize/report the K_NZNZ coefficients.

In one example, a UE reports the following for the quantization of the NZ coefficients in {tilde over (W)}₂: (1) a X-bit indicator for the strongest coefficient index (i*,f*), where X=┌log₂K_NZ┐ or ┌log₂2L┐: (i) strongest coefficient c_l,i*,f*=1 (hence its amplitude/phase are not reported); (2) two antenna polarization-specific reference amplitudes are used: (i) for the polarization associated with the strongest coefficient c_l,i*,f*=1, since the reference amplitude p_l,i,f⁽¹⁾=1, it is not reported; and (ii) for the other polarization, reference amplitude p_l,i,f⁽¹⁾is quantized to 4 bits. In such instance, the 4-bit amplitude alphabet is

${1, {(\frac{1}{2})}^{\frac{1}{4}}, {(\frac{1}{4})}^{\frac{1}{4}}, {(\frac{1}{8})}^{\frac{1}{4}}, \dots, {(\frac{1}{2^{14}})}^{\frac{1}{4}}};$

(3) for {c_l,i,f, (i, f)≠(i*, f*)}: (i) for each polarization, differential amplitudes p_l,i,f⁽²⁾of the coefficients calculated relative to the associated polarization-specific reference amplitude and quantized to 3 bits, in such instance, the 3-bit amplitude alphabet is

${1, \frac{1}{\sqrt{2}}, \frac{1}{2}, \frac{1}{2 \sqrt{2}}, \frac{1}{4}, \frac{1}{4 \sqrt{2}}, \frac{1}{8}, \frac{1}{8 \sqrt{2}}} .$

Note the final quantized amplitude p_l,i,fis given by p_l,i,f⁽¹⁾×p_l,i,f⁽²⁾; and (ii) each phase is quantized to either8PSK (N_ph=8) or16PSK (N_ph=16) (which is configurable).

For the polarization r*∈{0, 1} associated with the strongest coefficient c_l,i*f*, there may be

$r^{*} = ⌊ \frac{i^{*}}{L} ⌋$

and the reference amplitude p_l,i,f⁽¹⁾=p_l,r*⁽¹⁾=1. For the other polarization r∈{0, 1} and r≠r*, there may be

$r = (⌊ \frac{i^{*}}{L} ⌋ + 1) \mod 2$

and the reference amplitude p_l,i,f⁽¹⁾=p_l,r⁽¹⁾quantized (reported) using the 4-bit amplitude codebook mentioned above.

In Rel. 16 enhanced Type II and Type II port selection codebooks, a UE can be configured to report M FD basis vectors. In one example,

$M = ⌈ p \times \frac{N_{3}}{R} ⌉,$

where R is higher-layer configured from {1, 2} and p is higher-layer configured from {¼, ½}. In one example, the p value is higher-layer configured for rank 1-2 CSI reporting. For rank>2 (e.g., rank 3-4), the p value (denoted by v₀) can be different. In one example, for rank 1-4, (p, v₀) is jointly configured from

${(\frac{1}{2}, \frac{1}{4}), (\frac{1}{4}, \frac{1}{4}), (\frac{1}{4}, \frac{1}{8})},$

i.e.,

$M = ⌈ p \times \frac{N_{3}}{R} ⌉$

for rank 1-2 and

$M = ⌈ v_{0} \times \frac{N_{3}}{R} ⌉$

for rank 3-4. In one example, N₃=N_SB×R where N_SBis the number of SBs for CQI reporting. In one example, M is replaced with M_vto show its dependence on the rank valuev, hence p is replaced with p_v, v∈{1, 2} and v₀is replaced with p_v, v∈{3, 4}.

A UE can be configured to report M_vFD basis vectors in one-step from N₃basis vectors freely (independently) for each layer l∈{1, . . . , v} of a rank v CSI reporting. Alternatively, a UE can be configured to report M_vFD basis vectors in two-step as follows: (1) in step 1, an intermediate set (InS) comprising N₃′<N₃basis vectors is selected/reported, wherein the InS is common for all layers; and (2) in step 2, for each layer l∈{1, . . . , v} of a rank v CSI reporting, M_vFD basis vectors are selected/reported freely (independently) from N₃′ basis vectors in the InS.

In one example, one-step method is used when N₃≤19 and two-step method is used when N₃>19. In one example, N₃′=┌αM_v┐ where α>1 is either fixed (to 2 for example) or configurable.

The codebook parameters used in the DFT based frequency domain compression (eq. 5) are (L,p_vfor v∈{1, 2},p_vfor v∈{3, 4}, β, α, N_ph). The set of values for these codebook parameters are as follows: (1) L: the set of values is {2, 4} in general, except L∈{2, 4, 6} for rank 1-2, 32 CSI-RS antenna ports, and R=1; (2) (p_vfor v∈{1, 2}1, p for v∈{3, 4})∈

$\begin{matrix} {(\frac{1}{2}, \frac{1}{4}), (\frac{1}{4}, \frac{1}{4}), (\frac{1}{4}, \frac{1}{8})}; \\ β \in {\frac{1}{4}, \frac{1}{2}, \frac{3}{4}}; & (3) \\ α = 2; & (4) \end{matrix}$

and (5) N_ph=16.

The set of values for these codebook parameters are as in TABLE 1.

TABLE 1

Values for the codebook parameters

p_ν

paramCombination-r16
L
ν ∈ {1, 2}
ν ∈ {3, 4}
β

1
2
¼
⅛
¼

2
2
¼
⅛
½

3
4
¼
⅛
¼

4
4
¼
⅛
½

5
4
¼
¼
¾

6
4
½
¼
½

7
6
¼
—
½

8
6
¼
—
¾

In Rel. 17 (further enhanced Type II port selecting codebook),

$M \in {1, 2}, L = \frac{K_{1}}{2}$

where K₁=α×P_CSIRS, and codebook parameters (M, α, β) are configured from TABLE 2.

TABLE 2

Values for the codebook parameters

paramCombination-r17
M
α
β

1
1
¾
½

2
1
1
½

3
1
1
¾

4
1
1
1

5
2
½
½

6
2
¾
½

7
2
1
½

8
2
1
¾

The above-mentioned framework (e.g., Eq. 5) represents the precoding-matrices for multiple (N₃) FD units using a linear combination (double sum) over2L (or K₁) SD beams/ports and M_vFD beams. This framework can also be used to represent the precoding-matrices in time domain (TD) by replacing the FD basis matrix W_fwith a TD basis matrix W_t, wherein the columns of W_tcomprises M_vTD beams that represent some form of delays or channel tap locations. Hence, a precoder W^lcan be described as follows:

$\begin{matrix} W = A_{l} C_{l} B_{l}^{H} = W_{1} {\tilde{W}}_{2} W_{t}^{H}, & (5 A) \end{matrix}$

In one example, the M_vTD beams (representing delays or channel tap locations) are selected from a set of N₃TD beams, i.e., N₃corresponds to the maximum number of TD units, where each TD unit corresponds to a delay or channel tap location. In one example, a TD beam corresponds to a single delay or channel tap location. In another example, a TD beam corresponds to multiple delays or channel tap locations. In another example, a TD beam corresponds to a combination of multiple delays or channel tap locations.

In one example, the codebook for the CSI report is according to at least one of the following examples.

In one example, the codebook can be a Rel. 15 Type I single-panel codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 15 Type I multi-panel codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 15 Type II codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 15 port selection Type II codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 16 enhanced Type II codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 16 enhanced port selection Type II codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook can be a Rel. 17 further enhanced port selection Type II codebook (e.g., as illustrated in TS 38.214).

In one example, the codebook is a new codebook for C-JT CSI reporting.

In one example, the new codebook is a decoupled codebook comprising the following components: (called “CB1” hereafter): (1) intra-TRP: per TRP Rel. 16/17 Type II codebook components, i.e., SD basis vectors (W1), FD basis vectors (W_f), W2 components (e.g., SCI, indices of NZ coefficients, and amplitude/phase of NZ coefficients) and (2) inter-TRP: co-amplitude and co-phase for each TRP.

In one example, the new codebook is a joint codebook (called “CB2” hereafter) comprising following components: (1) per TRP SD basis vectors (W1); (2) single joint FD basis vectors (W_f); and (3) single joint W2 components (e.g., SCI, indices of NZ coefficients, and amplitude/phase of NZ coefficients).

Two new codebooks are illustrated in FIG. 11.

FIG. 11 illustrates an example of codebook 1100 according to embodiments of the present disclosure. An embodiment of the codebook 1100 shown in FIG. 11 is for illustration only.

In one example, when the codebook is a legacy codebook (e.g., one of Rel. 15/16/17 NR codebooks, according to one of the examples above), then the CSI reporting is based on a CSI resource set comprising one or multiple NZP CSI-RS resource(s), where each NZP CSI-RS resource comprises CSI-RS antenna ports for all TRPs/RRHs, i.e., P=Σ_r=1^NP_r, where P is the total number of antenna ports, and P_ris the number of antenna ports associated with r-th TRP. In this case, a TRP corresponds to (or maps to or is associated with) a group of antenna ports.

In one example, when the codebook is a new codebook (e.g., one of the two new codebooks above), then the CSIreporting is based on a CSI resource set comprising one or multiple NZP CSI-RS resource(s).

In one example, each NZP CSI-RS resource comprises CSI-RS antenna ports for all TRPs/RRHs. i.e., P=Σ_r=1^NP_r, where P is the total number of antenna ports, and P_ris the number of antenna ports associated with r-th TRP. In this case, a TRP corresponds to (or maps to or is associated with) a group of antenna ports.

In one example, each NZP CSI-RS resource corresponds to (or maps to or is associated with) a TRP/RRH (a TRP-group).

In the present disclosure, it may use N, N_TRP, N_RRHinterchangeably for a number of TRPs/RRHs.

In one embodiment, a UE is configured with a CSI reporting based on an mTRP (or D-MIMO or C-JT) codebook, via e.g., higher layer parameter codebookType set to “typeII-r18-cjt” or “typeII-PortSelection-r18-cjt,” where the codebook is one of the following two modes: In one example, one of the two modes is configured, e.g., via higher layer (e.g., via parameter codebookMode).

In one example of Mode 1, per-TRP/TRP-group (or per-CSI-RS resource) SD/FD basis selection. Example formulation (N_TRP=number of TRPs or TRP groups): The UE reports (i) SD basis vectors for each TRP, (ii) FD basis vectors for each TRP, and (iii) either a joint W2 across all TRPs or one W2 for each TRP:

$[\begin{matrix} W_{1, 1} {\tilde{W}}_{2, 1} W_{f, 1}^{H} \\ ⋮ \\ W_{1, N} {\tilde{W}}_{2, N} W_{f, N}^{H} \end{matrix}] .$

In one example of Mode 2, per-TRP/TRP group (port-group or resource) SD basis selection and joint (across N_TRPTRPs) FD basis selection. Example formulation (N_TRP=number of TRPs or TRP groups): The UE reports (i) SD basis vectors for each TRP, (ii) one common/joint FD basis vectors across all TRPs, and (iii) either a joint W2 across all TRPs or one W2 for each TRP:

$[\begin{matrix} \begin{matrix} W_{1, 1} & 0 \\ 0 & ⋱ \end{matrix} & \begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} \\ \begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} & W_{1, N} \end{matrix}] {\tilde{W}}_{2} W_{f}^{H} or [\begin{matrix} W_{1, 1} {\tilde{W}}_{2, 1} W_{f, 1}^{H} \\ ⋮ \\ W_{1, N} {\tilde{W}}_{2, N} W_{f, N}^{H} \end{matrix}]$

where it may use N and N_TRPinterchangeably.

In one example, Mode 1 and Mode 2 can be the codebooks described in U.S. patent application Ser. No. 18/310,396, as incorporated herein by reference in its entirety.

In one example, the two modes can share similar detailed designs such as parameter combinations, basis selection, TRP (group) selection, reference amplitude, {tilde over (W)}₂quantization schemes.

In one example, parameter combinations can be a tuple of parameters such as L, p_v, β for regular Type-II CJT codebook or a tuple of parameters such as M, α, β for portselection Type-II CJT codebook.

In one example, basis selection scheme can be SD basis selection and/or FD basis selection schemes described in embodiments as described in U.S. patent application Ser. No. 18/310,396.

In one example, a TRP selection can be one component/example described in U.S. as described in U.S. patent application Ser. No. 18/295,219, as incorporated herein by reference in its entirety.

In one example, a reference amplitude scheme can be one component/example described in as described in U.S. patent application Ser. No. 18/305,241, as incorporated herein by reference in its entirety.

In one example, a W₂quantization scheme can include strongest coefficient indicator, upper bound of non-zero coefficients, reference amplitudes, a scheme that each coefficient is decomposed into phase and amplitude and they are selected respective codebooks, and a codebook subset restriction.

The bitwidth for PMI of codebookType=typeII-r16 is provided in TABLE 3, where the values of (N₁, N₂), (O₁, O₂), L, K^NZ, N₃, and {M_l}_{l=1, . . . , v}are shown in 3GPP standard specification TS 38.214.

TABLE 3

PMI of codebookType= typeII-r16

Information fields X₁

i_1,1
i_1,2
i_1,8,1
i_1,8,2
i_1,8,3
i_1,8,4

Rank = 1 N₃≤ 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂K^NZ┐
N/A
N/A
N/A

Rank = 2 N₃≤ 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂(2L)┐
N/A
N/A

Rank = 3 N₃≤ 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂(2L)┐
┌log₂(2L)┐
N/A

Rank = 4 N₃≤ 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂(2L)┐
┌log₂(2L)┐
┌log₂(2L)┐

Rank = 1 N₃> 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂K^NZ┐
N/A
N/A
N/A

Rank = 2 N₃> 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂┐
N/A
N/A

Rank = 3 N₃> 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂(2L)┐
┌log₂(2L)┐
N/A

Rank = 4 N₃> 19
┌log₂(O₁O₂)┐

⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L \end{matrix}) ⌉

┌log₂(2L)┐
┌log₂(2L)┐
┌log₂(2L)┐
┌log2(2L)┐

Information fields X₂

i_2,3,1
i_2,3,2
i_2,3,3
i_2,3,4
i_1,5
i_1,6,1

Rank = 1 N₃≤ 19
4
N/A
N/A
N/A
N/A

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{1} - 1 \end{matrix}) ⌉

Rank = 2 N₃≤ 19
4
4
N/A
N/A
N/A

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{2} - 1 \end{matrix}) ⌉

Rank = 3 N₃≤ 19
4
4
4
N/A
N/A

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

Rank = 4 N₃≤19
4
4
4
4
N/A

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

Rank = 1 N₃> 19
4
N/A
N/A
N/A
┌log₂(2M₁)┐

⌈ \log_{2} (\begin{matrix} 2 M_{1} - 1 \\ M_{1} - 1 \end{matrix}) ⌉

Rank = 2 N3 > 19
4
4
N/A
N/A
┌log₂(2M₂)┐

⌈ \log_{2} (\begin{matrix} 2 M_{2} - 1 \\ M_{2} - 1 \end{matrix}) ⌉

Rank = 3 N3 > 19
4
4
4
N/A
┌log₂(2M₃)┐

⌈ \log_{2} (\begin{matrix} 2 M_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

Rank = 4 N3 >19
4
4
4
4
┌log₂(2M₄)┐

⌈ \log_{2} (\begin{matrix} 2 M_{4} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

Information fields X₂

i_1,6,2
i_1,6,3
i_1,6,4
{i_2,4,l}_l=1,...υ
{i_2,5,l}_l=1,...υ
{i_1,7,l}_l=1,...υ

Rank = 1 N₃≤ 19
N/A
N/A
N/A
3(K^NZ− 1)
4(K^NZ− 1)
2LM₁

Rank = 2 N₃≤ 19

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{2} - 1 \end{matrix}) ⌉

N/A
N/A
3(K^NZ− 2)
4(K^NZ− 2)
4LM₂

Rank = 3 N₃≤ 19

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

N/A
3(K^NZ− 3)
4(K^NZ− 3)
6LM₃

Rank = 4 N₃≤19

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

3(K^NZ− 4)
4(K^NZ− 4)
8LM₄

Rank = 1 N₃> 19
N/A
N/A
N/A
3(K^NZ− 1)
4(K^NZ− 1)
2LM₁

Rank = 2 N3 > 19

⌈ \log_{2} (\begin{matrix} 2 M_{2} - 1 \\ M_{2} - 1 \end{matrix}) ⌉

N/A
N/A
3(K^NZ− 2)
4(K^NZ− 2)
4LM₂

Rank = 3 N3 > 19

⌈ \log_{2} (\begin{matrix} 2 M_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} 2 M_{3} - 1 \\ M_{3} - 1 \end{matrix}) ⌉

N/A
3(K^NZ− 3)
4(K^NZ− 3)
6LM₃

Rank = 4 N3 >19

⌈ \log_{2} (\begin{matrix} 2 M_{4} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} 2 M_{4} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

⌈ \log_{2} (\begin{matrix} 2 M_{4} - 1 \\ M_{4} - 1 \end{matrix}) ⌉

3(K^NZ− 4)
4(K^NZ− 4)
8LM₄

Note: the bitwidth for {i_1,7,l}_{l=1, . . . , v}and {i_2,5,l}_{l=1, . . . , v}shown in 3 is the total bitwidth of {i_1,7,l}, {i_2,4,l} and {i_2,5,l} up to Rank=v, respectively, and the corresponding per layer bitwidths are 2LM_v, 3(K_l^NZ−1), and 4(K_l^NZ−1), (i.e., 1, 3, and 4 bits for each respective indicator elements k_l,i,f⁽³⁾, k_l,i,f⁽²⁾, and c_l,i,f, respectively), where K_l^NZas defined in 3GPP standard specification TS 38.214 is the number of nonzero coefficients for layer l such that K^NZ=Σ_l=1^vK_l^NZ.

The bitwidth for PMI of codebookType=typeII-PortSelection-r17 is provided in TABLE 4, where the values of P_CSI-RS, K₁, K^NZ, N₃, N and M are given by 3GPP standard specification TS 38.214.

TABLE 4

PMI of codebookType= typeII-PortSelection-r17

Information fields X₁

i_1,2
i_1,6
i_1,8,1
i_1,8,2
i_1,8,3
i_1,8,4

Rank = 1

⌈ \log_{2} (\begin{matrix} P_{CSI - RS} / 2 \\ K_{1} / 2 \end{matrix})

┌log 2 (N − 1)┐ if N >
┌log₂(K₁M)┐
N/A
N/A
N/A

M = 2, N/A

otherwise

Rank = 2

⌈ \log_{2} (\begin{matrix} P_{CSI ‐ RS} / 2 \\ K_{1} / 2 \end{matrix}) ⌉

┌log 2 (N − 1)┐ if N >
┌log₂(K₁M)┐
┌log₂(K₁M)┐
N/A
N/A

M = 2, N/A

otherwise

Rank = 3

⌈ \log_{2} (\begin{matrix} P_{CSI ‐ RS} / 2 \\ K_{1} / 2 \end{matrix}) ⌉

┌log 2 (N − 1)┐ if N >
┌log₂(K₁M)┐
┌log₂(K₁M)┐
┌log₂(K₁M)┐
N/A

M = 2, N/A

otherwise

Rank = 4

⌈ \log_{2} (\begin{matrix} P_{CSI ‐ RS} / 2 \\ K_{1} / 2 \end{matrix}) ⌉

┌log2 (N − 1)┐ if N >
┌log₂(K₁M)┐
┌log₂(K₁M)┐
┌log₂(K₁M)┐
┌log₂(K₁M)┐

M = 2, N/A

otherwise

Information fields X₂

i_2,3,1
i_2,3,2
i_2,3,3
i_2,3,4
{i_2,4,l}_l=1,_{... ,υ}
{i_2,5,l}_l=1,...,υ
{i_1,7,l}_l=1,...,υ

Rank = 1
4
N/A
N/A
N/A
3(K^NZ− 1)
4(K^NZ− 1)
N/A if K^NZ=

K₁M;

K₁M otherwise

Rank = 2
4
4
N/A
N/A
3(K^NZ− 2)
4(K^NZ− 2)
N/A if K^NZ=

2K₁M;

2K₁M otherwise

Rank = 3
4
4
4
N/A
3(K^NZ− 3)
4(K^NZ− 3)
3K₁M

Rank = 4
4
4
4
4
3(K^NZ− 4)
4(K^NZ− 4)
4K₁M

Note: the bitwidth for {i_1,7,l}_{l=1, . . . , v}, {i_2,4,l}_{l=1, . . . , v}and {i_2,5,l}_{l=1, . . . , v}shown in TABLE 5 is the total bitwidth of {i_1,7,l}, {i_2,4,l} and {i_2,5,l} up to Rank v, respectively, and the corresponding per layer bitwidths are K₁M, 3(K_l^NZ−1), and 4(K_l^NZ−1), (i.e., 1, 3, and 4 bits for each respective indicator elements k_l,i,f⁽³⁾, k_l,i,f⁽²⁾and c_l,i,f, respectively), where K_l^NZas defined in 3GPP standard specification TS 38.214 is the number of nonzero coefficients for layer l such that K_l^NZ=Σ_l=1^vK_l^NZ.

In Rel-16/17 Type-Id CSI reporting, the mapping order of CSI fields of one CSI report, CSI part 1, is shown in 3GPP TS 38.212, which is as follows.

TABLE 5

Mapping order of CSI fields of one CSI report, CSI part 1

CSI report

number
CSI fields

CSI report #n
CRI as in Tables 6.3.1.1.2-3/4/6 of 3GPP TS 38.212, if reported

CSI part 1
Rank Indicator as in Tables 6.3.1.1.2-3/4/5 or 6.3.2.1.2-8/9 of 3GPP TS

38.212, if reported

Wideband CQI for the first TB as in Tables 6.3.1.1.2-3/4/5 or 6.3.2.1.2-

8/9 of 3GPP TS 38.212, if reported

Subband differential CQI for the first TB with increasing order of

subband number as in Tables 6.3.1.1.2-3/4/5 or 6.3.2.1.2-8/9 of 3GPP

TS 38.212, if reported

Indicator of the number of non-zero wideband amplitude coefficients M₀

for layer 0 as in Table 6.3.1.1.2-5 of 3GPP TS 38.212, if reported

Indicator of the number of non-zero wideband amplitude coefficients M₁

for layer 1 as in Table 6.3.1.1.2-5 of 3GPP TS 38.212 (if the rank

according to the reported RI is equal to one, this field is set to all zeros),

if 2-layer PMI reporting is allowed according to the rank restriction in

Clauses 5.2.2.2.3 and 5.2.2.2.4 of 3GPP TS 38.214 and if reported

Indicator of the total number of non-zero coefficients summed across all

layers K^NZas in Table 6.3.2.1.2-8/9 of 3GPP TS 38.212, if reported

Note:

Subbands for given CSI report n indicated by the higher layer parameter csi-ReportingBand are numbered continuously in the increasing order with the lowest subband of csi-ReportingBand as subband 0.

In Rel-16 Type-II CSI reporting, the mapping order of CSI fields of one CSI report, CSI part 2, is shown in 3GPP TS38.212, which is as follows:

TABLE 6

Mapping order of CSI fields of one CSI report, CSI part 2 of codebookType=typeII-

r16 or typeII-PortSelection-r16

CSI report

number
CSI fields

CSI report #n
PMI fields X₁, from left to right as in Tables 6.3.2.1.2-1A/2A, if

CSI part 2,
reported

group 0

CSI report #n
The following PMI fields X₂, from left to right, as in Tables 6.3.2.1.2-

CSI part 2, group 1

1 A / 2 A : {i_{2, 3, l} : l = 1, \dots, υ}, i_{1, 5}, {i_{1, 6, l} : l = 1, \dots, υ} and \max (0, ⌈ \frac{K^{N Z}}{2} ⌉ - υ) \times 3

highest priority bits of

{i_{2, 4, l} : l = 1, \dots, υ}, \max (0, ⌈ \frac{K^{N Z}}{2} ⌉ - υ) \times 4 highest priority bits of

{i_2,5,l: l = 1, ... , υ} and v * 2LM_υ − └K^NZ/2┘ highest priority bits

of{i_1,7,l: l = 1, ... , υ}, in decreasing order of priority based on the

corresponding function Pri(l, i, f) defined in clause 5.2.3 of TS38.214,

if reported

CSI report #n
The following PMI fields X₂, from left to right, as in Tables 6.3.2.1.2-

CSI part 2, group 2

1 A / 2 A : \min (K^{N Z} - v, ⌊ \frac{K^{N Z}}{2} ⌋) \times 3 lowest priority bits of {i_{2, 4, l} : l =

1, \dots, υ}, \min (K^{N Z} - υ, ⌊ \frac{K^{N Z}}{2} ⌋) \times 4 lowest priority bits of {i_{2, 5, l} : l =

1, ... , υ}and └K^NZ/2┘ lowest priority bits of {i_1,7,l: l = 1, ... , υ}, in

decreasing order of priority based on the corresponding function

Pri(l, i, f) defined in clause 5.2.3 of TS38.214, if reported

In Rel-16 Type-II CSI reporting, the mapping order of CSI fields of one CSI report, CSI part 2, is given by 3GPP TS 38.212, which is as follows:

TABLE 7

Mapping order of CSI fields of one CSI report, CSI part 2 of codebookType=typeII-

PortSelection-r17

CSI report

number
CSI fields

CSI report #n
PMI fields X₁, from left to right as in Tables 6.3.2.1.2-2B, if reported

CSI part 2, group 0

CSI report #n
The following PMI fields X₂, from left to right, as in Tables

CSI part 2, group 1

6.3 .2 .1 .2 - 2 B : {i_{2, 3, l} : l = 1, \dots, υ} \max (0, ⌈ \frac{K^{N Z}}{2} ⌉ - υ)) \times 3 highest

priority bits of

{i_{2, 4, l} : l = 1, \dots, υ}, (\max (0, ⌈ \frac{K^{N Z}}{2} ⌉ - υ)) \times 4 highest priority bits of

{i_2,5,l: l = 1, ... , υ} and v * K₁M − └K^NZ/2┘ highest priority bits

of{i_1,7,l: l = 1, ... , υ}, in decreasing order of priority based on the

corresponding function Pri(l, i, f) defined in clause 5.2.3 of

TS38.214, if reported

CSI report #n
The following PMI fields X₂, from left to right, as in Tables

CSI part 2, group 2

6.3 .2 .1 .2 - 2 B : (\min (K^{N Z} - υ, ⌊ \frac{K^{N Z}}{2} ⌋)) \times 3 lowest priority bits of

{i_{2, 4, l} : l = 1, \dots, υ}, (\min (K^{N Z} - υ, ⌊ \frac{K^{N Z}}{2} ⌋)) \times 4 lowest priority bits of

{i_2,5,l: l = 1, ... , υ} and └K^NZ/2┘ lowest priority bits of

{i_1,7,l: l = 1, ... , υ}, in decreasing order of priority based on the

corresponding function Pri(l, i, f) defined in clause 5.2.3 of

TS38.214, if reported

FIG. 12 illustrates an example of two-part UCI used to multiplex and report CSI 1200 according to embodiments of the present disclosure. An embodiment of the UCI used to multiplex and report CSI 1200 shown in FIG. 12 is for illustration only.

In one embodiment, the two-part UCI (or two-part CSI) (FIG. 12) is used to multiplex and report CSI comprising CSI part 1 and CSI part 2 according to the above-mentioned framework, e.g., Mode1/Mode 2 codebooks for Rel-18 (or beyond) CJT Type-II CSI.

In one embodiment, on Rel-16-Type-II-CSI-based refinement for Rel-18 Type-II CSI.

In one embodiment, when either Mode 1 or Mode 2 is configured by higher-layer signaling (i.e., RRC), CSI part 1 includes at least one of the following parameters: (1) (I1) N_TRP-bit bitmap indicator to indicate a set of selected TRPs (CSI-RS resources); (2) (I2) An indicator of ┌log₂N_L┐-bit to indicate one combination of values for (L₁, ⋅ ⋅ ⋅ L_N_TRP), where N_L≥1; (3) (I3) A reference TRP (CSI-RS) indicator (for FD basis reporting); and (4) Legacy parameters: RI, CQI(s) (subband differential CQIs), an indicator of the number of non-zero coefficients, K^NZ(total number of NZC across all layers).

In one example, the N_TRP-bit bitmap indicator can be absent (not reported) if a restriction where the number of selected (cooperating) TRPs N is the same as N_TRP(e.g., N=N_TRP, all TRP selection) is configured by higher-layer signaling, i.e., the N_TRP-bit bitmap is reported if N≤N_TRPis allowed (e.g., by configuration). In one example, the CRI can be reused as the N_TRP-bit bitmap indicator.

In one example, the indicator of ┌log₂N_L┐-bit can be absent (not reported) if N_L=1 (i.e., one combination of values for (L₁, ⋅ ⋅ ⋅ , L_N_TRP)) is configured by higher-layer signaling, i.e., the indicator of ┌log₂N_L┐-bit is reported if N_L>1.

In one example, the reference TRP (CSI-RS) indicator has ┌log₂N_TRP┐-bit length.

In one example, the CRI can be reused for the reference TRP (CSI-RS) indicator for Rel-18 Type-II CSI. In this case, no new reference TRP (CSI-RS) indicator is specified. In one example, the reference TRP (CSI-RS) indicator can be included in CSI part 2 (not in CSI part 1).

In one embodiment, when either Mode 1 or Mode 2 is configured by higher-layer signaling (i.e., RRC), CSI part 2 includes at least one of the following parameters.

In one example, CSI part 2 includes an indicator of ┌log₂O₁O₂┐-bit to indicate SD basis oversampling group for each CSI-RS (TRP) resource, i_1,1,r, where r is a CSI-RS (TRP) index.

In one example, CSI part 2 includes an indicator of

$⌈ \log_{2} (\begin{matrix} N_{1} N_{2} \\ L_{r} \end{matrix}) ⌉$

bit to indicate L_rSD basis vector selection for each CSI-RS (TRP) resource, i_1,2,r, where r is a CSI-RS (TRP) index.

In one example, CSI part 2 includes an indicator i_1,8,lto indicate a strongest coefficient across all CSI-RS resources for each layer1.

In one example, CSI part 2 includes an indicator i_2,3,lto indicate either (ex 1) a reference amplitude or (ex 2) 2N−1 reference amplitudes: (1) in one example, i_2,3,lfor each layer l, where each i_2,3,lhas n-bit length. In one example, n=4; and (2) in one example, i_2,3,lfor each layer l, where each i_2,3,lhas n×(2N−1)-bit length, and N is the number of selected (cooperating) TRPs (which can be inferred from N_TRP-bit bitmap indicator in CSI part 1). In one example, n=4.

In one example, CSI part 2 includes an indicator i_1.5to indicate for M_initial(i.e., window offset) when N₃>19: (1) in one example, i_1.5is common across all CSI-RS (TRP) resources, i.e., one for all CSI-RS resources, where the size of i_1.5is ┌log₂2M_v┐ bit and v is rank (i.e., the number of layers); (2) in one example, i_1.5is independent for each CSI-RS (TRP) resource, i.e., one for each CSI-RS resource: (i) in one instance, it can be denoted by i_1.5r*, where r is a CSI-RS (TRP) index and the size of i_1.5,ris ┌log₂2M_v┐ bit and v is rank (i.e., the number of layers); and (ii) in one instance, for one CSI-RS resource, the size of i_1.5,r*is ┌log₂2M_v┐ bits and for other N−1 CSI-RS resources, the size of i_1.5,ris ┌log₂N₃┐ bits for r≠r*. For example, r* is the CSI-RS resource index associated with (or including) the SCI.

In one example, CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource for each CSI-RS resource, either N₃>19 or/and N₃≤19 L: (1) in one example, the indicator for each of N−1 CSI-RS resources (excluding the reference CSI-RS resource) has ┌log₂N₃┐ (or ┌log₂(N₃−1)┐) bits across all layers 1=1, ⋅ ⋅ ⋅ , v; (2) in one example, the indicator for each of N−1 CSI-RS resources (excluding the reference CSI-RS resource) has ┌log₂N₃┐ (or ┌log₂(N₃−1)┐) bits for each layer l; (3) in one example, the indicator for each of N CSI-RS resources has ┌log₂N₃┐ (or ┌log₂(N₃−1)┐) bits across all layers 1=1, ⋅ ⋅ ⋅ , v; and (4) in one example, the indicator for each of N CSI-RS resources has ┌log₂N₃┐ (or ┌log₂(N₃−1)┐) bits for each layer l.

In one example, CSI part 2 includes an indicator i_1,6,lto indicate FD basis vector selection for each layer l: (1) in one example, the indicator is common for all CSI-RS (TRP) resources, i.e., one for all CSI-RS resources, where the size of i_1,6,lis

$⌈ \log_{2} (\begin{matrix} 2 M_{v} - 1 \\ M_{v} - 1 \end{matrix}) ⌉$

bits for N₃>19 or

$⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix}) ⌉$

bits for N₃≤19; (2) in one example, the indicator is independent for each CSI-RS resource, i.e., one for each CSI-RS resource: (i) in one instance, it can be denoted by i_1,6,l,r, where r is a CSI-RS (TRP) index and where the size of i_1,6,l,ris

$⌈ \log_{2} (\begin{matrix} 2 M_{υ} - 1 \\ M_{υ} - 1 \end{matrix}) ⌉$

bits for N₃≥19 or

$⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix}) ⌉$

bits for N₃≤19; and (ii) in one instance, for one CSI-RS resource, the size of i_1,6,l,r*is

$⌈ \log_{2} (\begin{matrix} 2 M_{υ} - 1 \\ M_{υ} - 1 \end{matrix}) ⌉$

bits for N₃>19 and for other N−1 CSI-RS resources, the size of i_1,6,l,r*is

$⌈ \log_{2} (\begin{matrix} 2 M_{υ} \\ M_{υ} \end{matrix}) ⌉$

bits for N>19 for r≠r*. Or, for one CSI-RS resource, the size of i_1,6,l,r*is

$⌈ \log_{2} (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix}) ⌉$

bits for N₃<19 and for other N−1 CSI-RS resources, the size of i_1,6,l,r*is

$⌈ \log_{2} (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) ⌉$

bits for N₃≤19 for r≠r*. For example, r* is the CSI-RS resource index associated with (or including) the SCI.

In one example, CSI part 2 includes an indicator {i_2,4,l}_{l=1, . . . , v}to indicate amplitude coefficients across all CSI-RS (TRP) resources, where the size of the indicator is n_α(K^NZ−v) bits, n_αis the number of bits for amplitude coefficient, and K^NZis the total number of non-zero coefficients across all CSI-RS (TRP) resources. In one example, n_α=3.

In one example, CSI part 2 includes an indicator {i_2,5,l}_{l=1, . . . v}to indicate phase coefficients across all CSI-RS (TRP) resources, where the size of the indicator is n_p(K^NZ−v) bits, n_pis the number of bits for phase coefficient, and K^NZis the total number of non-zero coefficients across all CSI-RS (TRP) resources. In one example, n_p=4.

In one example, CSI part 2 includes an indicator {i_7,1,l}_{l=1, ⋅ ⋅ ⋅ v}to indicate locations of non-zero coefficients across all CSI-RS (TRP) resources, where the size of the indicator is v2M_vΣ_rL_rand r is a CSI-RS (TRP) index.

In one example, CSI part 2 includes (I3) An indicator to indicate a reference CSI-RS (TRP) resource, where the size of the indicator is ┌log₂N┐ bits and N is the number of selected (cooperating) TRPs (which can be inferred from N_TRP-bit bitmap indicator in CSI part 1).

In this disclosure, legacy parameters/indicators refer to the indicators excluding (I1), (I2), (I3), and (I4) described in the mentioned embodiments.

In one embodiment, CSI part 1 and CSI part 2 include (whole or a subset of) legacy parameters/indicators described in embodiments disclosed in the present disclosure (similar to Rel-16 CSI) and new indicators (I1), (I2), (I3), and (I4) for CJT according to at least one of the following examples.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit, and (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (2) group 0 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit, and (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (2) group 1 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit, and (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (2) group 2 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 0 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting), and (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 0 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (3) group 1 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 0 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (3) group 2 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 0 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource; and (3) group 1 of CSI Part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 1 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting), and (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 1 of CSI Part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting); and (3) group 2 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 0 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource; and (3) group 2 of CSI Part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; (2) group 1 of CSI part 2 includes (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource; and (3) group 2 of CSI Part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 2 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting), and (I4) an indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one embodiment, CSI part 1 and CSI part 2 include legacy parameters/indicators (similar to Rel-16 CSI) and new indicators (I1), (I2), and (I3) for CJT according to at least one of the following examples.

In one example, CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit, and (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 0 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 1 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 2 of CSI part 2 includes (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In embodiment, CSI part 1 and CSI part 2 include legacy parameters/indicators (similar to Rel-16 CSI) and new indicators (I1), (I2), and (I4) for CJT according to at least one of the following examples.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 0 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 1 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In one example: (1) CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit; and (2) group 2 of CSI part 2 includes (I4) an (new) indicator to indicate FD basis selection offset relative to a reference CSI-RS (TRP) resource.

In embodiment, CSI part 1 and CSI part 2 include legacy parameters/indicators (similar to Rel-16 CSI) and new indicators (I1) and (I2) for CJT according to at least one of the following examples.

In one example, CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit.

In one embodiment, a reference CSI-RS can be implicitly derived, hence there can be no reference CSI-RS indicator (i.e., (I3)) in CSI part 1 or/and CSI part 2. For example, a CSI-RS resource associated with SCI can be regarded as a reference CSI-RS resource.

In one embodiment/example, any embodiment/example described under embodiment as disclosed in the present disclosure excluding one example can be another embodiment/example.

In one embodiment/example, any embodiment/example described under embodiment as disclosed in the present disclosure excluding one example and including a reference CSI-RS resource=CSI-RS resource associated with SCI can be another embodiment/example.

In one embodiment, Rel-17-Type-II-CSI-based refinement for Rel-18 Type-II CSI is provided.

In one embodiment, when either Mode 1 or Mode 2 is configured by higher-layer signaling (i.e., RRC), CSI part 1 includes at least one of the following parameters: (1) (I1) N_TRP-bit bitmap indicator to indicate a set of selected TRPs (CSI-RS resources); (2) (I2) An indicator of ┌log₂N_L┐-bit to indicate one combination of values for (L₁, ⋅ ⋅ ⋅ , L_N_TRP), where N_L≥1; (3) (I3) A reference TRP (CSI-RS) indicator (for FD basis reporting); and (4) legacy parameters: RI, CQI(s) (subband differential CQIs), an indicator of the number of non-zero coefficients, K^NZ(total number of NZC across all layers).

In one example, the reference TRP (CSI-RS) indicator has ┌log₂N_TRP┐-bit length.

In one example, the CRI can be reused for the reference TRP (CSI-RS) indicator for Rel-18 Type-II CSI. In this case, no new reference TRP (CSI-RS) indicator is specified.

In one example, the reference TRP (CSI-RS) indicator can be included in CSI part 2 (not in CSI part 1).

In one embodiment, when either Mode 1 or Mode 2 is configured by higher-layer signaling (i.e., RRC), CSI part 2 includes at least one of the following parameters.

In one example, CSI part 2 includes an indicator of

$⌈ \log_{2} (\begin{matrix} P_{CSI ‐ RS} / 2 \\ L_{r} \end{matrix}) ⌉$

-bit to indicate L_rSD basis vector selection for each CSI-RS (TRP) resource, i_1,2,r, where r is a CSI-RS (TRP) index, P_CSI-RS=2N₁N₂, and L_r=α_rP_CSI-RS/2, and K_1,r=α_rP_CSI-RS.

In one example, CSI part 2 includes an indicator i_1,8,lto indicate a strongest coefficient across all CSI-RS resources for each layer l.

In one example, CSI part 2 includes an indicator i_1,6to indicate FD basis vector selection: (1) in one example, the indicator is common for all CSI-RS (TRP) resources, i.e., one for all CSI-RS resources, where the size of i_1,6is ┌log₂(N_R17−1)┐ if N_R17>M=2, N/A otherwise, where N_R17is a value configured by higher-layer parameter (e.g., valueOfN); and (2) in one example, the indicator is independent for each CSI-RS resource, i.e., one for each CSI-RS resource. For example, it can be denoted by i_1,6,r, where r is a CSI-RS (TRP) index and where the size of i_1,6,ris ┌log₂(N_R17−1)┐ if N_R17>M=2, N/A otherwise, where N_R17is a value configured by higher-layer parameter (e.g., valueOfN).

In one example, CSI part 2 includes an indicator {i_2,4,l}_{l=1, . . . v}, to indicate amplitude coefficients across all CSI-RS (TRP) resources, where the size of the indicator is n_α(K^NZ−v) bits, n_α is the number of bits for amplitude coefficient, and K^NZis the total number of non-zero coefficients across all CSI-RS (TRP) resources. In one example, n_α=3.

In one example, CSI part 2 includes an indicator {i_2,5,l}_{l=1, . . . , v}to indicate phase coefficients across all CSI-RS (TRP) resources, where the size of the indicator is n_p(K^NZ−v) bits, n_pis the number of bits for phase coefficient, and K^NZis the total number of non-zero coefficients across all CSI-RS (TRP) resources. In one example, n_p=4.

In one example, CSI part 2 includes an indicator {i_1,7,l}_{l=1, . . . , v}to indicate locations of non-zero coefficients across all CSI-RS (TRP) resources, where the size of the indicator is vM Σ_rK_1,rand r is a CSI-RS (TRP) index.

In one example, CSI part 2 includes (I3) an indicator to indicate a reference CSI-RS (TRP) resource, where the size of the indicator is ┌log₂N┐ bits and N is the number of selected (cooperating) TRPs (which can be inferred from N_TRP-bit bitmap indicator in CSI part 1).

In the present disclosure, legacy parameters/indicators refer to the indicators excluding (I1), (I2), and (I3) described in the mentioned embodiments.

In one embodiment, CSI part 1 and CSI part 2 include legacy parameters/indicators (similar to Rel-17 CSI) and new indicators (I1), (I2), and (I3) for CJT according to at least one of the following examples.

In one example, CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, (I2) an indicator of ┌log₂N_L┐-bit, and (I3) a reference CSI-RS (TRP) indicator (for FD basis reporting).

In one embodiment, CSI part 1 and CSI part 2 include legacy parameters/indicators (similar to Rel-17 CSI) and new indicators (I1) and (I2) for CJT according to at least one of the following examples.

In one example, CSI part 1 includes (I1) a N_TRP-bit bitmap indicator, and (I2) an indicator of ┌log₂N_L┐-bit.

In one embodiment/example, any embodiment/example described under embodiment as disclosed in the present disclosure excluding one example can be another embodiment/example.

Any of the above variation embodiments can be utilized independently or in combination with at least one other variation embodiment.

The present disclosure provides multi-TRP C-JT scenarios and provides method and apparatus for CSI reporting in multi-TRP scenarios.

The present disclosure provides electronic devices and methods on CSI codebook and reporting for MIMO operations, more particularly, to electronic devices and methods on CSI codebook and reporting for distributed MIMO or multi-TRP operations in wireless networks.

In the present disclosure, components to indicate reference values/relative offsets and reporting for W1/W2/W_fare provided for multi-TRP C-JT scenarios.

In one embodiment, a UE is configured with an mTRP (or D-MIMO or C-JT) codebook, via e.g., higher layer parameter codebookType set to “typeII-r18-cjt,” which is designed based on Rel-16/17 Type-II codebook. For example, The mTRP codebook has a triple-stage structure which can be represented as W=W₁W₂W_f^H, where the component W₁is used to report/indicate a spatial-domain (SD) basis matrix comprising SD basis vectors, the component W_fis used to report/indicate a frequency-domain (FD) basis matrix comprising FD basis vectors, and the component W₂is used to report/indicate coefficients corresponding to SD and FD basis vectors.

In one embodiment, for the mTRP codebook, W_fbasis vectors (or indices of FD basis vectors) and W₂FD indices (columns of W₂) or FD indices of coefficients are shifted (or rotated or remapping) based on or with respect to the FD beam index f*, which can be reference FD beam index.

In Rel-16 Type-II codebook, the remapping procedure is illustrated in 3GPP standard specification: let f_l*∈{0, 1, . . . , M_v−1} be the index of i_2,4,land i_l*∈{0, 1, . . . , 2L−1} be the index of k_l,f_l_*⁽²⁾which identify the strongest coefficient of layer l, i.e., the element k_l,i,_l_*,f_l_*⁽²⁾of i_2,4,l, for l=1, . . . , v. The codebook indices of n_3,lare remapped with respect to n_3,l^(f^l^*)as n_3,l^(f)=(n_3,l^(f)−n_3,l^(f*)) mod N₃, such that n_3,l^(f^l^*), after remapping. The index f is remapped with respect to f_l* as f=(f−f_l*)mod M_v, such that the index of the strongest coefficient is f_l*=0 (l=1, . . . , v), after remapping. The indices of i_2,4,l, i_2,5,land i_1,7,lindicate amplitude coefficients, phase coefficients and bitmap after remapping.

In one example, the strongest coefficient of layer l is identified by i_1,8,l∈{0, 1, . . . , 2L−1}, which is obtained as follows:

$i_{1, 8, l} = {\begin{matrix} \sum_{i = 0}^{i_{1}^{*}} k_{1, i, 0}^{(3)} - 1 & υ = 1 \\ i_{l}^{*} & 1 < υ \leq 4 \end{matrix} for l = 1, \dots, υ .$

In one example, the strongest coefficient of layer l is identified by i_1,8,l∈{0, 1, . . . , 2L−1}, which is obtained as follows i_1,8,l=i_l* for all rank v∈{1, . . . , 4} and for l=1, . . . , v.

In example, the reference FD beam index f* is the FD beam index f of the SCI (of the strongest TRP). The SCI hence the index f* is layer-common, i.e., the same for all layers.

In one example, the reference FD beam index f* is the FD beam index f of the SCI of a reference TRP. The SCI hence the index f* is layer-common, i.e., the same for all layers.

In one example, a reference TRP can be configured via RRC, MAC-CE, or DCI. In one example, a reference TRP can be fixed or determined in a pre-defined rule. In one example, a reference TRP can be determined by UE and reported as a part of CSI. In one example, a strongest TRP can be a reference TRP.

In one example, the reference FD beam index f* is fixed (e.g., the lowest index among the FD basis vectors). The fixed index f* is layer-common, i.e., the same for all layers.

In one example, the reference FD beam index f* is a configured, via, DCI, MAC-CE, or RRC by NW (layer-common). The configured index can be one of indices of FD basis vectors. Or the configured index can be different from indices of FD basis vectors. The configured index f* is layer-common, i.e., the same for all layers.

In one example, W_fbasis vectors and W₂FD indices (columns of W₂) associated with the strongest TRP (or a reference TRP) are shifted (or rotate or remapping FD indices) based on the FD beam index f*, where f* is according to one of the examples disclosed in the present disclosure. For the rest of the TRPs, the shift or rotation or remapping may not be performed. The index f* is layer-common, i.e., the same for all layers.

In one example, W_fbasis vectors and W₂FD indices (columns of W₂) associated with all TRPs are shifted (or rotated or remapping FD indices) based on the FD beam index f*, where f* is according to one of the examples disclosed in the present disclosure.

In one example, the reference FD beam index f_l* is the FD beam index f_lof the SCI (of the strongest TRP, or a reference TRP) for each layer l. The SCI hence the index f_l* is layer-specific, i.e., one SCI for each layer.

In one example, the reference FD beam index f_l* is fixed (e.g., the lowest index among the FD basis vectors) for each layer l. The fixed index f_l* is layer-specific, i.e., one SCI for each layer.

In one example, the reference FD beam index f_l* is a configured, via, DCI, MAC-CE, or RRC by NW (layer-specific). The configured index can be one of indices of FD basis vectors. Or the configured index can be different from indices of FD basis vectors. The configured index f_l* is layer-specific, i.e., one for each layer.

In one example, for each layer l=1, . . . , v, W_fbasis vectors and W₂FD indices (columns of W₂) associated with the strongest TRP (or a reference TRP) are shifted (or rotate or remapping FD indices) based on the FD beam index f_l*, where f_l* is according to one of the examples disclosed in the present disclosures. The index f_l* is layer-specific, i.e., one for each layer.

In one example, for each layer l=1, . . . , v, W_fbasis vectors and W₂FD indices (columns of W₂) associated with all TRPs are shifted (or rotated or remapping FD indices) based on the FD beam index f_l*, where f_l* is according to one of the examples disclosed in the present disclosures.

In one embodiment, a UE is configured to report a (relative) offset in FD with respect to a reference FD index (f*), where the reference FD index is according to one of the examples disclosed in the present disclosures. In one example, the one (relative) offset in FD is defined as δ_f=f−f*.

For N_TRP>1 TRPs, the one (relative) offset in FD for a TRP r∈{0, 1 . . . , N_TRP−1} is defined as δ_r,f=f_r−f_r*, where f_ris the FD index (of FD basis vectors or W₂coefficient matrix), and f_ris the reference FD index. When the reference FD index is the same for all TRPs (i.e., there is only one reference FD index), f_r=f*, and hence δ_r,f=f_r−f*.

In one example, the one (relative) offset is reported regardless of the value of N≤N_TRP. where N is the number of TRPs selected from N_TRPTRPs by the UE for CSI reporting. In one example, the one (relative) offset is reported only when N>1, and not reported when N=1.

In one example, the one (relative) offset is reported for each TRP (including the strongest TRP which includes the strongest coefficient with the reference FD index f*). So, the total number of (relative) offset reported is N.

In one example, the one (relative) offset is reported for each TRP except the strongest TRP (which includes the strongest coefficient with the reference FD index f*). So, the total number of (relative) offset reported is N−1. The (relative) offset for the strongest TRP is fixed to 0.

In one example, the one (relative) offset is reported for each TRP except a reference TRP (which can be configured, fixed, or determined by the UE and reported). So, the total number of (relative) offset reported is N−1. The (relative) offset for the strongest TRP is fixed to 0.

In one example, the one (relative) offset is reported only when N=2, and two (relative) offsets are reported when N∈{3, 4}, and no reported when N=1.

In one example, the one (relative) offset is reported only when N∈{2, 3}, and two (relative) offsets are reported when N=4, and no reported when N=1.

In one example, the (relative) offset is reported from a window of FD indices. In one example, the window is {0, 1, . . . , X−1}. In one example, the window is {M_init,M_init+1, . . . , M_init+X−1} mod N₃. The size (X) or/and the starting index (M_init) can be fixed or configured (e.g., via RRC) or reported by the UE.

For N≥1 or/and v≥1, the (relative) offset is reported according to at least one of the following examples.

In one example, the (relative) offset is reported in layer common manner, i.e., one (relative) offset is reported that is common across all layers l=1, . . . , v.

In one example, the (relative) offset is reported in layer specific manner, i.e., one (relative) offset is reported for each layer l=1, . . . , v.

In one example, the (relative) offset is reported in TRP common manner, i.e., one (relative) offset is reported that is common across all TRPs.

In one example, the (relative) offset is reported in TRP specific manner, i.e., one (relative) offset is reported for each TRP.

In one example, the (relative) offset is reported in TRP-group specific manner, i.e., one (relative) offset is reported for each TRP group, and the same offset is assumed for each TRP within a TRP group.

In one example, the (relative) offset is reported in layer common manner and TRP common manner, i.e., one (relative) offset is reported that is common across all layers and all TRPs.

In one example, the (relative) offset is reported in layer common manner and TRP specific manner, i.e., for each TRP, one (relative) offset is reported that is common across all layers.

In one example, the (relative) offset is reported in layer common manner and TRP-group specific manner, i.e., for each TRP-group, one (relative) offset is reported that is common across all layers.

In one example, the (relative) offset is reported in layer specific manner and TRP common manner, i.e., for each layer, one (relative) offset is reported that is common across all TRPs.

In one example, the (relative) offset is reported in layer specific manner and TRP specific manner, i.e., for each layer and for each TRP, one (relative) offset is reported.

In one embodiment, a UE is configured to report a (relative) delay offset δ_τ with respect to a reference delay τ*, where the reference delay is according to at least one of the following examples.

In one example, the reference delay τ* is 0, hence not reported.

In one example, the reference delay τ* is in an index set of {0, 1, 2, . . . , T_ref}, where T_refis fixed or configured via RRC, MAC-CE, or DCI. In one example, T_ref=4, 8, 16, 32.

In one example, the reference delay τ* is in [0, τ_max], where τ_maxis fixed or configured via RRC, MAC-CE, or DCI. In one example, τ* is selected/reported using an x-bit codebook including equidistance points in [0, τ_max].

In one example, the delay offset δ_τ is defined as δ_τ=τ−τ*. The delay offset δ_τ is according to at least one of the following examples.

In one example, the delay offset δ_τ is in an index set of {0, 1, 2, . . . , T_rel}, where T_relis fixed or configured via RRC, MAC-CE, or DCI. In one example, T_ref=T_rel. In one example, T_rel=4, 8,16, 32.

In one example, the delay offset δ_τ is in [0, τ_max,rel], where τ_max,relis fixed or configured via RRC, MAC-CE, or DCI. In one example, δ_τ is selected/reported using an y-bit codebook including equidistance points in [0, τ_max,rel]. In one example, τ_max=τ_max,rel.

In one example, delay offset δ_τ is represented in a phase form, e.g., [0,2π]. In this case, for example, instead of “delay offset,” it can be referred as “phase offset,” “phase ramp/slope,” “phase offset of delay difference between TRPs,” etc.

In one example, when delay offset δ_τ is represented in a phase form, 2ⁿ^bit-PSK can be used to quantize [0, 2π] for reporting. For example, n_bit=2, 3, 4, . . . and so on.

In one example, n_bitcan be fixed to 3 or4 or5 . . . .

In another example, n_bitcan be configured by NW via DCI, MAC-CE, or RRC.

In one example, n_bitcan be determined by a pre-defined rule. For example, n_bit=a+n_p, where a is fixed (e.g., 0, 1 or2) and n_pis the number of bits configured for phase component in W₂.

In one example, delay offset δ_τ can be reported using a DFT codebook. For example, the phase offset associated with the delay offset can be selected/reported from a DFT codebook with size N₅and oversampling factor O₅, which can be expressed as

$z_{n} = [1 e^{j \frac{2 π n}{O_{5} N_{5}}} \dots e^{j \frac{2 π n (N_{5} - 1)}{O_{5} N_{5}}}],$

where n=0, 1, ⋅ ⋅ ⋅ , N₅−1, i.e., the index of n is reported for delay offset δ_τ. The payload size for this can be given by ┌log₂O₅N₅┐ bits.

In one example, N₅is determined in a pre-defined rule.

In one example, N₅is fixed.

In one example, N₅is configured by NW via DCI, MAC-CE, or RRC.

In one example, O₅is determined in a pre-defined rule.

In one example, O₅is fixed, e.g., O₅=1 or O₅=2.

In one example, O₅is configured by NW via DCI, MAC-CE or RRC.

In one example, any combination of the above examples can be applied.

For examples, N₅is the same number of N₃(i.e., frequency-domain compression unit). In this case, additional configuration may not be needed.

In another example, N₅is defined based on N₃and the density of (associated) CSI-RS (DL RS) resources.

In another example, N₅is defined based on the number of configured SBs n_SBfor (associated) CSI-RS (DL RS) resource/reporting/measurement bandwidth.

In another example, N₅is defined based on the number of configured SBs n_SBand CSI-RS density for (associated) CSI-RS (DL RS) resource/reporting/measurement bandwidth.

In another example, N₅is defined based on the number of configured RBs n_RBfor (associated) CSI-RS (DL RS) resource/reporting/measurement bandwidth.

In another example, N₅is defined based on the number of configured RBs n_RBand CSI-RS density for (associated) CSI-RS (DL RS) resource/reporting/measurement bandwidth.

In one example, O₅can be denoted by another notation such as O₃or other.

In one example, O₅is the same as O₃.

The delay offset can be called under another name such as FD basis selection offset, phase offset, and so on.

The quantization method (e.g., 2ⁿ^bit-PSK or DFT codebook z_n) described in each example above can be applied for δ_r,τdescribed in examples below.

For N_TRP>1 TRPs, the one (relative) delay offset for a TRP r∈{0, 1 . . . , N_TRP−1} is defined as or δ_r,τ=τ_r−τ_r*, where τ_ris the delay value for TRP r, and τ_r* it is the reference delay value. When the reference delay value is the same for all TRPs (i.e., there is only one reference delay), τ_r*=τ* and hence δ_r,τ=τ_r−τ*.

In one example, the one (relative) delay offset is reported regardless of the value of N≤N_TRP. where N is the number of TRPs selected from N_TRPTRPs by the UE for CSI reporting. In one example, the one (relative) delay offset is reported only when N>1, and not reported when N=1.

In one example, the one (relative) delay offset is reported for each TRP (including the strongest TRP which includes the strongest coefficient). So, the total number of (relative) delay offset reported is N.

In one example, the one (relative) delay offset is reported for each TRP except the strongest TRP (which includes the strongest coefficient). So, the total number of (relative) offset reported is N−1. The (relative) delay offset for the strongest TRP is fixed to 0.

In one example, the one (relative) delay offset is reported for each TRP except a reference TRP (which can be configured, fixed, or determined by the UE and reported). So, the total number of (relative) offset reported is N−1. The (relative) delay offset for the strongest TRP is fixed to 0.

In one example, the one (relative) delay offset is reported only when N=2, and two (relative) delay offsets are reported when N∈{3, 4}, and no reported when N=1.

In one example, the one (relative) delay offset is reported only when N∈{2, 3}, and two (relative) delay offsets are reported when N=4, and no reported when N=1.

For N≥1 or/and v≥1, the (relative) delay offset (above mentioned, e.g., δ_τ (δ_{r, τ})) is reported according to at least one of the following examples.

In one example, the (relative) delay offset is reported in layer common manner, i.e., one (relative) delay offset is reported that is common across all layers l=1, . . . , v.

In one example, the (relative) delay offset is reported in layer specific manner, i.e., one (relative) delay offset is reported for each layer l=1, . . . , v.

In one example, the (relative) delay offset is reported in TRP common manner, i.e., one (relative) delay offset is reported that is common across all TRPs.

In one example, the (relative) delay offset is reported in TRP specific manner, i.e., one (relative) delay offset is reported for each TRP.

In one example, the (relative) delay offset is reported in TRP-group specific manner, i.e., one (relative) delay offset is reported for each TRP group, and the same delay offset is assumed for each TRP within a TRP group.

In one example, the (relative) delay offset is reported in layer common manner and TRP common manner, i.e., one (relative) delay offset is reported that is common across all layers and all TRPs.

In one example, the (relative) delay offset is reported in layer common manner and TRP specific manner, i.e., for each TRP, one (relative) delay offset is reported that is common across all layers.

In one example, the (relative) delay offset is reported in layer common manner and TRP-group specific manner, i.e., for each TRP-group, one (relative) delay offset is reported that is common across all layers.

In one example, the (relative) delay offset is reported in layer specific manner and TRP common manner, i.e., for each layer, one (relative) delay offset is reported that is common across all TRPs.

In one example, the (relative) delay offset is reported in layer specific manner and TRP specific manner, i.e., for each layer and for each TRP, one (relative) delay offset is reported.

In one embodiment, a UE is configured to report a (relative) frequency offset δ_gwith respect to a reference frequency g*, where the reference frequency is according to at least one of the following examples.

In one example, the reference frequency g* is 0, hence not reported.

In one example, the reference frequency g* is in an index set of {0, 1, 2, . . . , F_ref}, where F_refis fixed or configured via RRC, MAC-CE, or DCI. In one example, F_ref=4, 8,16, 32.

In one example, the reference frequency g* is in [0, g_max], where g_maxis fixed or configured via RRC, MAC-CE, or DCI. In one example, g* is selected/reported using an x-bit codebook including equidistance points in [0, g_max].

In one example, the frequency offset δ_gis defined as δ_g=g−g*. The frequency offset δ_gis according to at least one of the following examples.

In one example, the frequency offset δ_gis in an index set of {0, 1, 2, . . . , F_rel}, where F_relis fixed or configured via RRC, MAC-CE, or DCI. In one example, F_ref=F_rel. In one example, F_rel=4, 8, 16, 32.

In one example, the frequency offset δ_gis in [0, g_max,rel], where g_max,relis fixed or configured via RRC, MAC-CE, or DCI. In one example, δ_gis selected/reported using an y-bit codebook including equidistance points in [0, g_max,rel]. In one example, g_max=g_max,rel.

For N_TRP>1 TRPs, the one (relative) frequency offset for a TRP r∈{0, 1 . . . , N_TRP−1} is defined as or δ_r,g=g_r−g*, where g_ris the frequency value for TRP r, and τ_r* is the reference frequency value. When the reference frequency value is the same for all TRPs (i.e., there is only one reference frequency), g_r*=g* and hence δ_r,g=g_r−g*.

In one example, the one (relative) frequency offset is reported regardless of the value of N≤N_TRP. where N is the number of TRPs selected from N_TRPTRPs by the UE for CSI reporting. In one example, the one (relative) frequency offset is reported only when N>1, and not reported when N=1.

In one example, the one (relative) frequency offset is reported for each TRP (including the strongest TRP which includes the strongest coefficient). So, the total number of (relative) frequency offset reported is N.

In one example, the one (relative) frequency offset is reported for each TRP except the strongest TRP (which includes the strongest coefficient). So, the total number of (relative) frequency reported is N−1. The (relative) frequency offset for the strongest TRP is fixed to 0.

In one example, the one (relative) frequency offset is reported for each TRP except a reference TRP (which can be configured, fixed, or determined by the UE and reported). So, the total number of (relative) offset reported is N−1. The (relative) delay offset for the strongest TRP is fixed to 0.

In one example, the one (relative) frequency offset is reported only when N=2, and two (relative) frequency offsets are reported when N∈{3, 4}, and no reported when N=1.

In one example, the one (relative) frequency offset is reported only when N∈{2, 3}, and two (relative) frequency offsets are reported when N=4, and no reported when N=1.

For N≥1 or/and v≥1, the (relative) frequency offset is reported according to at least one of the following examples.

In one example, the (relative) frequency offset is reported in layer common manner, i.e., one (relative) frequency offset is reported that is common across all layers l=1, . . . , v.

In one example, the (relative) frequency offset is reported in layer specific manner, i.e., one (relative) frequency offset is reported for each layer l=1, . . . , v.

In one example, the (relative) frequency offset is reported in TRP common manner, i.e., one (relative) frequency offset is reported that is common across all TRPs.

In one example, the (relative) frequency offset is reported in TRP specific manner, i.e., one (relative) frequency offset is reported for each TRP.

In one example, the (relative) frequency offset is reported in TRP-group specific manner, i.e., one (relative) frequency offset is reported for each TRP group, and the same frequency offset is assumed for each TRP within a TRP group.

In one example, the (relative) frequency offset is reported in layer common manner and TRP common manner, i.e., one (relative) frequency offset is reported that is common across all layers and all TRPs.

In one example, the (relative) frequency offset is reported in layer common manner and TRP specific manner, i.e., for each TRP, one (relative) frequency offset is reported that is common across all layers.

In one example, the (relative) frequency offset is reported in layer common manner and TRP-group specific manner, i.e., for each TRP-group, one (relative) frequency offset is reported that is common across all layers.

In one example, the (relative) frequency offset is reported in layer specific manner and TRP common manner, i.e., for each layer, one (relative) frequency offset is reported that is common across all TRPs.

In one example, the (relative) frequency offset is reported in layer specific manner and TRP specific manner, i.e., for each layer and for each TRP, one (relative) frequency offset is reported.

In one embodiment, the reporting of the relative offset, for each of the examples disclosed in the present disclosures, can be turned ON/OFF (or enabled). For instance, the UE can be configured with the information regarding whether the relative offset(s) is/are reported by the UE. If turned ON, the UE reported the relative offset(s); else it does not. The information can be provided via e.g., RRC, MAC-CE, or DCI.

In one embodiment, a UE is configured to report one of the relative offset types in embodiment disclosed in the present disclosures (e.g., offset in FD index, delay offset, and frequency offset).

In one example, the UE can be configured to report the relative offset(s) in FD index f*.

In one example, the UE can be configured to report the relative delay offset(s) with respect to τ*.

In one example, the UE can be configured to report the relative frequency offset(s) with respect to g*.

In one embodiment, a UE is configured to report two of the relative offset types in embodiment disclosed in the present disclosures (e.g., offset in FD index, delay offset, and frequency offset).

In one example, the UE can be configured to report the relative offset(s) in FD index f* and the relative delay offset(s) with respect to τ*.

In one example, the UE can be configured to report the relative offset(s) in FD index f* and the relative frequency offset(s) with respect to g*.

In one example, the UE can be configured to report the relative delay offset(s) with respect to τ* and the relative frequency offset(s) with respect to g*.

In one embodiment, a UE is configured to report all of the relative offset types in embodiment disclosed in the present disclosures (e.g., offset in FD index, delay offset, and frequency offset).

In one example, the UE can be configured to report the relative offset(s) in FD index f* and the relative delay offset(s) with respect to τ* and the relative frequency offset(s) with respect to g*.

In one example of Mode 1, per-TRP/TRP-group SD/FD basis selection and example formulation (N_TRP=number of TRPs or TRP groups), the UE reports (i) SD basis vectors for each TRP, (ii) FD basis vectors for each TRP, and (iii) either a joint W2 across all TRPs or one W2 for

$[\begin{matrix} W_{1, 1} {\tilde{W}}_{2, 1} W_{f, 1}^{H} \\ ⋮ \\ W_{1, N} {\tilde{W}}_{2, N} W_{f, N}^{H} \end{matrix}] .$

In one embodiment of Mode 2, per-TRP/TRP group (port-group or resource) SD basis selection and joint (across N_TRPTRPs) FD basis selection, and example formulation (N_TRP-number of TRPs or TRP groups), the UE reports (i) SD basis vectors for each TRP, (ii) one common/joint FD basis vectors across all TRPs, and (iii) either a joint W2 across all TRPs or one W2 for each TRP:

$[\begin{matrix} W_{1, 1} & 0 & 0 & 0 \\ 0 & ⋱ & 0 & 0 \\ 0 & 0 & W_{1, N} \\ 0 & 0 \end{matrix}] {\tilde{W}}_{2} W_{f}^{H} or [\begin{matrix} W_{1, 1} {\tilde{W}}_{2, 1} W_{f}^{H} \\ ⋮ \\ W_{1, N} {\tilde{W}}_{2, N} W_{f}^{H} \end{matrix}] .$

In one example, Mode 1 and Mode 2 can be the codebook described in embodiments disclosed in the U.S. patent application Ser. No. 18/310,396.

In one example, the two modes can share similar detailed designs such as parameter combinations, basis selection, TRP (group) selection, reference amplitude, {tilde over (W)}₂quantization schemes.

In one example, a TRP selection can be one component/example described in the U.S. patent application Ser. No. 18/295,219.

In one example, a reference amplitude scheme can be one component/example described in the U.S. patent application Ser. No. 18/305,241.

In one example, a {tilde over (W)}₂quantization scheme can include strongest coefficient indicator, upper bound of non-zero coefficients, reference amplitudes, a scheme that each coefficient is decomposed into phase and amplitude, and they are selected respective codebooks, and a codebook subset restriction.

In one embodiment, a UE reports a (relative) offset in FD (e.g., δ_f) or/and a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) only when Mode 1 codebook is configured (i.e., relative FD offset is not reported when Mode 2 codebook is configured). In one example, a UE reports a (or more) relative offset in FD. In one example, a UE reports a (or more) relative delay offset. In one example, a UE reports a (or more) (relative) frequency offset. In one example, a UE reports any combination of the threes.

In one example, δ_fis according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

Alternatively, the UE is expected to report the relative FD offset when mode 1 codebook is configured, and the UE is not expected to report the relative FD offset when mode 2 codebook is configured.

In one embodiment, a UE reports a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) only when Mode 2 codebook is configured (i.e., relative FD offset is not reported when Mode 2 codebook is configured). In one example, a UE reports a (or more) relative offset in FD. In one example, a UE reports a (or more) relative delay offset. In one example, a UE reports a (or more) (relative) frequency offset. In one example, a UE reports any combination of the threes.

In one example, of is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

Alternatively, the UE is expected to report the relative FD offset when mode 2 codebook is configured, and the UE is not expected to report the relative FD offset when mode 1 codebook is configured.

In one embodiment, a UE reports a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) both for Mode 1 and Mode 2. In one example, a UE reports a (or more) relative offset in FD. In one example, a UE reports a (or more) relative delay offset. In one example, a UE reports a (or more) (relative) frequency offset. In one example, a UE reports any combination of the threes.

In one example, δ_fis according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

Alternatively, the UE is expected to report the relative FD offset for both codebook modes.

In one embodiment, a UE is configured (e.g., via higher layer) to report a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) when mTRP codebook (with N>1 TRPs or NZP CSI-RS resources) is configured. In one example, a UE reports a (or more) relative offset in FD. In one example, a UE reports a (or more) relative delay offset. In one example, a UE reports a (or more) (relative) frequency offset. In one example, a UE is configured to report any combination of the threes.

In one example, δ_fis according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

In one embodiment, a UE is configured (e.g., via higher layer) to report a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) for Mode 1 only or for Mode 2 only or either Mode 1 or Mode 2, using a new higher-layer parameter. For example, a parameter relativeOffsetEnabledModelorMode2 is used to indicate which Mode is configured to report relative offset. In one example, relativeOffsetEnabledModelorMode2 can have two integer values, e.g., 1 and 2. In one example, a UE is configured to report a (or more) relative offset in FD. In one example, a UE is configured to report a (or more) relative delay offset. In one example, a UE is configured to report a (or more) (relative) frequency offset. In one example, a UE is configured to report any combination of the threes.

In one example, δ_fis according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

In one embodiment, a UE decides whether to report a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g) or not via a parameter in UCI part 1. In one example, a UE decides whether to report a (or more) relative offset in FD or not. In one example, a UE decides whether to report a (or more) relative delay offset or not. In one example, a UE decides whether to report a (or more) (relative) frequency offset or not. In one example, a UE decides whether to report any combination of the threes or not.

In one example, δ_fis according to at least one of the examples disclosed in the present disclosure.

In one example, δ_τ is according to at least one of the examples disclosed in the present disclosure.

In one example, δ_gis according to at least one of the examples disclosed in the present disclosure.

In one embodiment, a UE reports UE capability on reporting a (relative) offset in FD (e.g., δ_f), a (relative) delay offset (e.g., δ_τ), and/or a (relative) frequency offset (e.g., δ_g).

In one example, a UE reports its capability on reporting a (relative) offset in FD as UE capability. If NW receives this UE capability, the NW needs to follow the UE capability and can configure based on the UE capability.

In one example, a UE reports its capability on reporting a (relative) delay offset as UE capability. If NW receives this UE capability, the NW needs to follow the UE capability and can configure based on the UE capability.

In one example, a UE reports its capability on reporting a (relative) frequency offset as UE capability. If NW receives this UE capability, the NW needs to follow the UE capability and can configure based on the UE capability.

In one example, a UE reports its capability on reporting any combination of the above three offset components as UE capability. If NW receives this UE capability, the NW needs to follow the UE capability and can configure based on the UE capability.

In one embodiment, a UE reports UE capability on possible mode operations among the two modes.

In one example, a UE reports Mode 1-only as UE capability. If NW receives this UE capability, the NW can configure Mode 1 only to the UE.

In one example, a UE reports Mode 2-only as UE capability. If NW receives this UE capability, the NW can configure Mode 2 only to the UE.

In one example, a UE reports Modes 1 and 2 as UE capability. If NW receives this UE capability, the NW can configure either Mode 1 or Mode 2 to the UE.

In one embodiment, the two modes support a same set of rank candidates custom-character , i.e., any rank in can be configured for either mode 1 or mode 2.

In one example, custom-character ={1, 2}.

In one example, custom-character ={1, 2, 3}.

In another example custom-character =?{1, 2, 3, 4}.

In one embodiment, each mode i support a different set of rank candidates custom-character _i.

In one example, low ranks, e.g., custom-character ₁={1, 2}, can be configured for Mode 1, and high ranks, e.g., ₂={3, 4}, can be configured for Mode 2.

In one example, low ranks, e.g., custom-character ₂={1, 2}, are for Mode 2, and high ranks, e.g., ₁={3, 4}, are for Mode 1.

In one example, low ranks, e.g., custom-character ₁={1, 2}, are for Mode 1, and any rank, e.g., ₂={1, 2, 3, 4}, is for Mode 2.

In one example, low ranks, e.g., custom-character ₂={1, 2}, are for Mode 2, and any rank, e.g., ₁={1, 2, 3, 4}, is for Mode 2.

In one embodiment, there are common codebook parameters for Mode 1 and Mode 2, and mode-specific codebook parameters.

In one example, L (or L_sumor L_r) value(s) is a common parameter for both Mode 1 and Mode 2, i.e., same value(s) can be configured for both Mode 1 and Mode 2.

In one example, L (or L_sumor L_r) value(s) is a mode-specific parameter, i.e., independent L value(s) can be configured for each mode.

In one example M_v(or M_v,sum=Σ_r=1^N^TRPM_v,ror M_v,r) value(s) is a common parameter for both Mode 1 and Mode 2, i.e., same value(s) of M_v(or M_v,sum=Σ_r=1^N^TRPM_v,ror M_v,r) can be configured for both Mode 1 and Mode 2.

In one example, M_v(or M_v,sumor M_v,r) value(s) is a mode-specific parameter, i.e., independent M_v(or M_v,sumor M_v,r) value(s) can be configured for each mode.

In one embodiment, a UE is configured with a CSI report for N≥1 TRPs (where TRP corresponds to a NZP CSI-RS resource or a subset of CSI-RS antenna ports within a NZP CSI-RS resource) based on a mTRP CJT codebook, where the codebook is configured according to (at least) one of the examples disclosed in the present disclosure.

In one embodiment, FD basis vectors and relative offsets in FD for N≥1 TRPs are reported as part of CSI report according to (at least) one of the following examples.

In one example (Alt 1), a relative offset(s) in FD (e.g., δ_for δ_f,r) for each of N TRPs (or each of N−1 TRPs, e.g., excluding a reference TRP) is reported and a common set of M_vFD basis vectors for all TRP are reported, as part of CSI report. So, the UE reports {δ_f,r: r=1, . . . , N−1} (or {δ_f,r: r=1, . . . , N}) and a set of M_vFD basis vectors via respective indicators.

In one example, a reference TRP can be configured by RRC, MAC-CE, or DCI.

In one example, a reference TRP can be determined by UE and reported. In one example, a reference TRP can be a strongest TRP.

In one example, a reference TRP can be fixed using a pre-defined rule. (e.g., the TRP that includes the SCI)

In one example (Alt 2), a relative offset(s) in FD (e.g., δ_for δ_f,r) for each of N TRPs (or each of N−1 TRPs, e.g., excluding a reference TRP) is reported and M_v(or M_v,r) FD basis vectors for each TRP r are reported, as part of CSI report. So, the UE reports {δ_f,r: r=1, . . . , N−1} (or {δ_f,r: r=1, . . . , N}) and N sets of M_v,rFD basis vectors via respective indicators.

In one example, a reference TRP can be configured by RRC, MAC-CE, or DCI.

In one example, a reference TRP can be determined by UE and reported. In one example, a reference TRP can be a strongest TRP.

In one example, a reference TRP can be fixed using a pre-defined rule. (e.g., the TRP that includes the SCI)

In one example (Alt 3), a common set of M_vFD basis vectors for all TRPs (across TRPs) are reported, as part of CSI report, and there is no reporting of relative offsets.

In one example (Alt 4), M_v(or M_v,r) FD basis vectors for each TRP r are reported, as part of CSI report, and there is no reporting of relative offsets.

In one example, Alt 1 and Alt 2 are associated with Mode 1 and Mode 2, respectively, where Mode 1 and Mode 2 are described in embodiment disclosed in the present disclosure, Alt1 is used for FD basis vector reporting when Mode 1 is configured and Alt2 is used for FD basis vector reporting when Mode 2 is configured.

Any example of relative offset(s) disclosed in the present disclosure can be an example for the relative offsets described in this embodiment.

In one example, Alt 1 and Alt 3 are associated with Mode 1 and Mode 2, respectively, where Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, Alt1 is used for FD basis vector reporting when Mode 1 is configured and Alt3 is used for FD basis vector reporting when Mode 2 is configured.

In one example, Alt 1 and Alt 4 are associated with Mode 1 and Mode 2, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, Alt1 is used for FD basis vector reporting when Mode 1 is configured and Alt4 is used for FD basis vector reporting when Mode 2 is configured.

In one example, Alt 2 and Alt 3 are associated with Mode 1 and Mode 2, respectively, where the Mode 1 and Mode 2 are described in embodiment disclosed in the present disclosure, i.e., Alt2 is used for FD basis vector reporting when Mode 1 is configured and Alt3 is used for FD basis vector reporting when Mode 2 is configured.

In one example, Alt 2 and Alt 4 are associated with Mode 1 and Mode 2, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt2 is used for FD basis vector reporting when Mode 1 is configured and Alt4 is used for FD basis vector reporting when Mode 2 is configured.

In one example, Alt 3 and Alt 4 are associated with Mode 1 and Mode 2, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt3 is used for FD basis vector reporting when Mode 1 is configured and Alt4 is used for FD basis vector reporting when Mode 2 is configured.

In one example, Alt 1 and Alt 2 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, Alt1 is used for FD basis vector reporting when Mode 2 is configured and Alt2 is used for FD basis vector reporting when Mode 1 is configured.

In one example, Alt 1 and Alt 3 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt1 is used for FD basis vector reporting when Mode 2 is configured and Alt3 is used for FD basis vector reporting when Mode 1 is configured.

In one example, Alt 1 and Alt 4 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt1 is used for FD basis vector reporting when Mode 2 is configured and Alt4 is used for FD basis vector reporting when Mode 1 is configured.

In one example, Alt 2 and Alt 3 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt2 is used for FD basis vector reporting when Mode 2 is configured and Alt3 is used for FD basis vector reporting when Mode 1 is configured.

In one example, Alt 2 and Alt 4 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt2 is used for FD basis vector reporting when Mode 2 is configured and Alt4 is used for FD basis vector reporting when Mode 1 is configured.

In one example, Alt 3 and Alt 4 are associated with Mode 2 and Mode 1, respectively, where the Mode 1 and Mode 2 are described in embodiments disclosed in the present disclosure, i.e., Alt3 is used for FD basis vector reporting when Mode 2 is configured and Alt4 is used for FD basis vector reporting when Mode 1 is configured.

In one embodiment, one of the examples (or some examples) in embodiments disclosed in the present disclosure can be configured by RRC, MAC-CE, or DCI signaling.

In one example, one of the examples disclosed in the present disclosure can be configured by RRC, MAC-CE or DCI signaling.

In one example, one of any combination of the examples disclosed in the present disclosure can be configured by RRC, MAC-CE or DCI signaling.

In one embodiment, Mode 1 can be associated with a fixed Alt x from Alt1-Alt4 in embodiments disclosed in the present disclosure, and one of the Alts in embodiments disclosed in the present disclosure can be configured for Mode 2 via RRC, MAC-CE or DCI signaling.

In one example, Mode 1 can be associated with fixed Alt 1 and one of the Alts (from Alt1-Alt4) can be configured for Mode 2 via RRC, MAC-CE or DCI signaling.

In one example, Mode 1 can be associated with fixed Alt 2 and one of the Alts (from Alt1-Alt4) can be configured for Mode 2 via RRC, MAC-CE or DCI signaling.

In one example, Mode 1 can be associated with fixed Alt 3 and one of the Alts (from Alt1-Alt4) can be configured for Mode 2 via RRC, MAC-CE or DCI signaling.

In one example, Mode 1 can be associated with fixed Alt 4 and one of the Alts (from Alt1-Alt4) can be configured for Mode 2 via RRC, MAC-CE or DCI signaling.

In one embodiment, Mode 2 can be associated with a fixed Alt x from Alt1-Alt4 in embodiments disclosed in the present disclosure and one of the Alts in embodiments disclosed in the present disclosure can be configured for Mode 1 via RRC, MAC-CE or DCI signaling.

In one example, Mode 2 can be associated with fixed Alt 1 and one of the Alts (from Alt1-Alt4) can be configured for Mode 1 via RRC, MAC-CE or DCI signaling.

In one example, Mode 2 can be associated with fixed Alt 2 and one of the Alts (from Alt1-Alt4) can be configured for Mode 1 via RRC, MAC-CE or DCI signaling.

In one example, Mode 2 can be associated with fixed Alt 3 and one of the Alts (from Alt1-Alt4) can be configured for Mode 1 via RRC, MAC-CE or DCI signaling.

In one example, Mode 2 can be associated with fixed Alt 4 and one of the Alts (from Alt1-Alt4) can be configured for Mode 1 via RRC, MAC-CE or DCI signaling.

In one embodiment, one of the Alts in embodiments disclosed in the present disclosure can be configured for either Mode 1 or Mode 2 via RRC, MAC-CE or DCI signaling.

In one example, one of the Alts (from Alt1-Alt4) can be configured for Mode 1 via RRC, MAC-CE, or DCI signaling.

In one example, one of the Alts (from Alt1-Alt4) can be configured for Mode 2 via RRC, MAC-CE, or DCI signaling.

In one embodiment, one of the Alts in embodiments disclosed in the present disclosure can be fixed for either Mode 1 or Mode 2.

In one example, one of the Alts (from Alt1-Alt4) can be fixed for Mode 1.

In one example, one of the Alts (from Alt1-Alt4) can be fixed for Mode 2.

In one embodiment, a UE is configured to report relative offsets for N_TRP(≥1) CSI-RS resources (or CSI-RS port groups, or TRPs, etc.), where the relative offsets are one of the relative offsets described in embodiments disclosed in the present disclosure. The CSI-RS resources and TRPs may be used interchangeably.

In one embodiment, a UE is configured to report relative offsets for a subset of N_TRPTRPs (or CSI-RS resources or CSI-RS port groups). In this case, the UE reports relative offsets only for the subset of N_TRPTRPs.

In one example, the subset of N_TRPTRPs (i.e., which TRPs for the relative offsets can be configured) can be configured via higher-layer signaling (e.g., RRC), or MAC-CE, or DCI. In one example, a bit-map indicator can be used to configure a subset of N_TRPTRPs.

In one example, a UE reports relative offsets for each of the subset of N_TRPTRPs.

In one example, a UE reports relative offsets for each of the subset of N_TRPTRPs, except a reference TRP. In one example, a reference TRP can be configured, fixed, determined by the UE and reported. In another example, the reference TRP can be a (the) strongest TRP.

In one embodiment, a UE (dynamically) decides which TRPs' relative offsets to be reported (being reported). The (dynamic) selection of TRPs for reporting corresponding relative offsets can be indicated via CSI Part 1.

In one example, the N_TRP-bit bitmap indicator for the TRP selection (the indicator for the dynamic TRP selection) can also be used for the TRP selection purpose of relative offsets, and the indicator is reported via CSI part 1.

In one example, a separate N_TRP-bit bitmap indicator for TRP selection for purpose of relative offsets can be used and this is reported via CSI part 1.

In one example, a separate combinatorial indicator for TRP selection for purpose of relative offsets can be used and this is reported via CSI part 1.

In another example, a N-bit bitmap indicator for TRP selection for purpose of relative offsets can be used and this is reported via CSI part 2, where N≤N_TRP. In one example, N is the selected number of TRPs in CSI part 1, inferred from the N_TRP-bit bitmap indicator.

In another example, a combinatorial indicator for TRP selection for purpose of relative offsets can be used and this is reported via CSI part 2.

In one embodiment, a UE identifies a need for UE-initiated/triggered reporting on relative offsets for a subset of N_TRPTRPs.

In one example, the UE requests to the NW to send reference signal resources (CSI-RS).

In one example, the UE initiates CSI reporting or relative offset reporting.

In one example, the UE performs UE-initiated/UE-triggered reporting or CSI reporting for relative offset reporting.

In a wireless communication system, MIMO is often identified as an essential feature in order to achieve high system throughput requirements. One of the key components of a MIMO transmission scheme is the accurate CSI acquisition at the eNB (or gNB) (or TRP). For MU-MIMO, in particular, the availability of accurate CSI is necessary in order to guarantee high MU performance. For TDD systems, the CSI can be acquired using the SRS transmission relying on the channel reciprocity. For FDD systems, on the other hand, it can be acquired using the CSI-RS transmission from eNB (or gNB), and CSI acquisition and feedback from UE. In legacy FDD systems, the CSI feedback framework is “implicit” in the form of CQI/PMI/RI (also CRI and LI) derived from a codebook assuming SU transmission from eNB (or gNB).

In 5G or NR systems, the above-mentioned “implicit” CSI reporting paradigm from LTE is also supported and referred to as Type I CSI reporting. In addition, a high-resolution CSI reporting, referred to as Type II CSI reporting, is also supported in Release 15 specification to provide more accurate CSI information to gNB for use cases such as high-order MU-MIMO. However, the overhead of Type II CSI reporting can be an issue in practical UE implementations. One approach to reduce Type II CSI overhead is based on frequency domain (FD) compression. In Rel. 16 NR, DFT-based FD compression of the Type II CSI has been supported (referred to as Rel. 16 enhanced Type II codebook in REF8). Some of the key components for this feature includes (a) spatial domain (SD) basis W₁, (b) FD basis W_f, and (c) coefficients {tilde over (W)}₂that linearly combine SD and FD basis. In a non-reciprocal FDD system, a complete CSI (comprising all components) needs to be reported by the UE.

However, when reciprocity or partial reciprocity does exist between UL and DL, then some of the CSI components can be obtained based on the UL channel estimated using SRS transmission from the UE. In Rel. 16 NR, the DFT-based FD compression is extended to this partial reciprocity case (referred to as Rel. 16 enhanced Type II port selection codebook in REF8), wherein the DFT-based SD basis in W₁is replaced with SD CSI-RS port selection, i.e., L out of

$\frac{P_{CSI - RS}}{2}$

CSI-RS ports are selected (the selection is common for the two antenna polarizations or two halves of the CSI-RS ports). The CSI-RS ports in this case are beamformed in SD (assuming UL-DL channel reciprocity in angular domain), and the beamforming information can be obtained at the gNB based on UL channel estimated using SRS measurements.

In Rel. 17 NR, CSI reporting has been enhanced to support the following examples.

In one example of enhanced Type II port selection codebook, it has been known in the literature that UL-DL channel reciprocity can exist in both angular and delay domains if the UL-DL duplexing distance is small. Since delay in time domain transforms (or closely related to) basis vectors in frequency domain (FD), the Rel. 16 enhanced Type II port selection can be further extended to both angular and delay domains (or SD and FD). In particular, the DFT-based SD basis in W₁and DFT-based FD basis in W_fcan be replaced with SD and FD port selection, i.e., L CSI-RS ports are selected in SD or/and M ports are selected in FD. The CSI-RS ports in this case are beamformed in SD (assuming UL-DL channel reciprocity in angular domain) or/and FD (assuming UL-DL channel reciprocity in delay/frequency domain), and the corresponding SD or/and FD beamforming information can be obtained at the gNB based on UL channel estimated using SRS measurements. In Rel. 17, such a codebook is supported (which is referred to as Rel. 17 further enhanced Type II port selection codebook in 3GPP standard specification).

In one example of NCJT CSI reporting, when the UE can communicate with multiple TRPs that are distributed at different locations in space (e.g., within a cell), the CSI reporting can correspond to a single TRP hypothesis (i.e., CSI reporting for one of the multiple TRPs), or multi-TRP hypothesis (i.e., CSI reporting for at least two of the multiple TRPs). The CSI reporting for both single TRP and multi-TRP hypotheses are supported in Rel. 17. However, the multi-TRP CSI reporting assume a non-coherent joint transmission (NCJT), i.e., a layer (and precoder) of the transmission is restricted to be transmitted from only one TRP.

In Rel. 18 MIMO WID includes the following objectives on CSI enhancements: (1) study, and if justified, specify enhancements of CSI acquisition for Coherent-JT targeting FR1 and up to 4 TRPs, assuming ideal backhaul and synchronization as well as the same number of antenna ports across TRPs, as follows: (i) Rel-16/17 Type-II codebook refinement for CJT mTRP targeting FDD and its associated CSI reporting, taking into account throughput-overhead trade-off; and (2) study, and if justified, specify CSI reporting enhancement for high/medium UE velocities by exploiting time-domain correlation/Doppler-domain information to assist DL precoding, targeting FR1, as follows: (i) Rel-16/17 Type-II codebook refinement, without modification to the spatial and frequency domain basis and (ii) a UE reporting of time-domain channel properties measured via CSI-RS for tracking.

The first objective extends the Rel.17 NCJT CSI to coherent JT (CJT), and the second extends FD compression in the Rel.16/17 codebook to include time (Doppler) domain compression. Both extensions are based on the same legacy codebook, i.e., Rel. 16/17 codebook. In the present disclosure, a unified codebook design considering both extensions has been provided.

The main use case or scenario of interest for CJT/DMIMO is as follows. Although NR supports up to 32 CSI-RS antenna ports, for a cellular system operating in a sub-1 GHz frequency range (e.g., less than 1 GHz), supporting large number of CSI-RS antenna ports (e.g., 32) at one site or remote radio head (RRH) or TRP is challenging due to larger antenna form factors at these frequencies (when compared with a system operating at a higher frequency such as 2 GHz or4 GHz. At such low frequencies, the maximum number of CSI-RS antenna ports that can be co-located at a site (or RRH or TRP) can be limited, for example to 8. This limits the spectral efficiency of such systems. In particular, the MU-MIMO spatial multiplexing gains offered due to large number of CSI-RS antenna ports (such as 32) cannot be achieved. One way to operate a sub-1 GHz system with large number of CSI-RS antenna ports is based on distributing antenna ports at multiple sites (or RRHs).

The multiple sites or RRHs can still be connected to a single (common) baseband unit, hence the signal transmitted/received via multiple distributed RRHs can still be processed at a centralized location. For example, 32 CSI-RS ports can be distributed across 4 RRHs, each with 8 antenna ports. Such a MIMO system can be referred to as a distributed MIMO (D-MIMO) or a CJT system. An example is illustrated in FIG. 13.

FIG. 13 illustrates an example of D-MIMO structure 1300 according to embodiments of the present disclosure. An embodiment of the D-MIMO structure 1300 shown in FIG. 13 are for illustration only.

The multiple RRHs in a D-MIMO setup can be utilized for spatial multiplexing gain (based on CSI reporting). Since RRHs are geographically separated, they (RRHs) tend to contribute differently in a CSI reporting. This motivates a dynamic RRH selection followed by CSI reporting condition on the RRH selection. This disclosure provides example embodiments on how channel and interference signal can be measure under different RRH selection hypotheses. Additionally, the signaling details of such a CSI reporting and CSI-RS measurement are also provided.

The main use case or scenario of interest for time-/Doppler-domain compression is moderate to high mobility scenarios. When the UE speed is in a moderate or high-speed regime, the performance of the Rel. 15/16/17 codebooks starts to deteriorate quickly due to fast channel variations (which in turn is due to UE mobility that contributes to the Doppler component of the channel), and a one-shot nature of CSI-RS measurement and CSI reporting in Rel. 15/16/17. This limits the usefulness of Rel. 15/16/17 codebooks to low mobility or static UEs only. For moderate or high mobility scenarios, an enhancement in CSI-RS measurement and CSI reporting is needed, which is based on the Doppler components of the channel. As described in 3GPP standard specification, the Doppler components of the channel remain almost constant over a large time duration, referred to as channel stationarity time, which is significantly larger than the channel coherence time. Note that the current (Rel. 15/16/17) CSI reporting is based on the channel coherence time, which is not suitable when the channel has significant Doppler components.

The Doppler components of the channel can be calculated based on measuring a reference signal (RS) burst, where the RS can be CSI-RS or SRS. When RS is CSI-RS, the UE measures a CSI-RS burst, and use it to obtain Doppler components of the DL channel, and when RS is SRS, the gNB measures an SRS burst, and use it to obtain Doppler components of the UL channel. The obtained Doppler components can be reported by the UE using a codebook (as part of a CS report). Or the gNB can use the obtained Doppler components of the UL channel to beamform CSI-RS for CSI reporting by the UE. An illustration of channel measurement with and without Doppler components is shown in FIG. 14. When the channel is measured with the Doppler components (e.g., based on an RS burst), the measured channel can remain close to the actual varying channel. On the other hand, when the channel is measured without the Doppler components (e.g., based on a one-shot RS), the measured channel can be far from the actual varying channel.

FIG. 14 illustrates an example of channel measurement 1400 according to embodiments of the present disclosure. An embodiment of the channel measurement 1400 shown in FIG. 14 are for illustration only.

The present disclosure relates to CSI acquisition at gNB. In particular, it relates to the CSI reporting based on a high-resolution (or Type II) codebook comprising spatial-, frequency- or/and time- (Doppler-) domain components for a distributed antenna structure (DMIMO). The 3 most novel aspects are as follows: (1) a joint or separate indicator of FD offset value and oversampled value for FD offset value per TRP or all TRPs, or per-layer, all layers; (2) details of window(s): initial index (Minit) and length W; (3) signaling: configured window, reported window; and (4) for multiple windows: a reference window+a relative offset per TRP with respect to the reference window.

The present disclosure is applicable to both space-frequency (equation 5) and space-time (equation 5A) frameworks.

In the present disclosure, the abovementioned framework for CSI reporting based on space-frequency compression (equation 5) or space-time compression (equation 5A) frameworks can be extended in two directions: (1) time or Doppler domain compression (e.g., for moderate to high mobility UEs) and (2) joint transmission across multiple RRHs/TRP (e.g., for a DMIMO or multiple TRP systems).

FIG. 15 illustrates an example of UE moving on a linear trajectory in a DMIMO system 1500 according to embodiments of the present disclosure. An embodiment of the UE moving on a linear trajectory in a DMIMO system 1500 shown in FIG. 15 are for illustration only.

An illustration of a UE moving on a trajectory located in a DMIMO system is shown in FIG. 15. While the UE moves from a location A to another location B at high speed (e.g., 60 kmph), the UE measures the channel and the interference (e.g., via NZP CSI-RS resources and CSI-IM resources, respectively), uses them to determine/report CSI considering CJT from multiple RRHs. The reported CSI can be based on a codebook, which includes components considering both multiple RRHs, and time-/Doppler-domain channel compression.

In one embodiment I, a UE is configured with a CSI report for Z≥1 TRPs (across or associated with Z NZP CSI-RS resources) based on a codebook that includes components, SD and FD bases (for compression), similar to Rel.16 enhanced Type II codebook (as shown in 3GPP standard specification 38.214) or rel. 17 further enhanced Type II port selection codebook (as shown in 3GPP standard specification 38.214). The value of Z can be equal to N_TRP, the number of TRPs or NZP CSI-RS resources configured for the CSI report. Or the value of Z≤N_TRP, where Z can be reported by the UE (e.g., via the CSI report) or signaled to the UE (e.g., via MACE CE or/and DCI). In one example, N_TRP∈{1, 2, 3, 4}. At least one of the following embodiments is used/configured. In this disclosure, notation N can be used for notation Z, i.e., Z and N are used interchangeably.

In one embodiment, the UE is configured to report a CSI for N>1 TRPs/RRHs (where TRP corresponds to a NZP CSI-RS resource or a subset of CSI-RS antenna ports within a NZP CSI-RS resource), the CSI determined based on a codebook comprising components: (A) two separate basis matrices W₁, W_ffor SD and FD compression, respectively, and (B) coefficients {tilde over (W)}₂. In one example, the codebook can be configured via one higher layer parameter codebookType set to “typeII-cjt-mode2-r18,” or via two higher layer parameters codebookType set to “typeII-cjt-r18” and codebookMode set to “Mode2.”

In particular, the precoder for layer l is given by:

$W_{l} = A_{l} C_{l} B_{l}^{H} = \frac{1}{γ} W_{1} {\tilde{W}}_{2} W_{f}^{H}$

where: (1) W_lis a P_CSIRS×N₃matrix whose columns are precoding vectors for N₃FD units, (2) W₁is a block diagonal matrix

$[\begin{matrix} W_{1, 1} & 0 & 0 & 0 \\ 0 & ⋱ & 0 & 0 \\ 0 & 0 & W_{1, 2 N} \\ 0 & 0 \end{matrix}]$

comprising 2N blocks, where (2(r−1)+1,2r)-th blocks are associated with two antenna polarizations (two halves or groups of CSI-RS antenna ports) of TRP r and each of two blocks is a

$\frac{P_{CSIRS, r}}{2} \times L_{r} SD$

basis or port selection matrix (similar to Rel. 16 enhanced Type II codebook or Rel. 17 enhanced Type II codebook) or (3){tilde over (W)}₂is a 2L×M_vcoefficients matrix, where L=Σ_r=1^NL_r, and (4) W_fis a N₃×M_vbasis matrix for FD basis matrix (similar to Rel. 16 enhanced Type II codebook). The columns of W_fcomprises vectors g_f,l=[y_0,l^(f), y_1,l^(f)⋅ ⋅ ⋅ y_N₃_−1,l^(f)], and (5) γ is a normalization factor.

In one example, for each r=1, . . . , N,

$[\begin{matrix} W_{1, 2 (r - 1) + 1} & 0 \\ 0 & W_{1, 2 r} \end{matrix}] = [\begin{matrix} B_{r} & 0 \\ 0 & B_{r} \end{matrix}]$

is a P_CSIRS,r×²L_rSD basis matrix, where the L_rSD basis vectors comprising columns of B_rare determined the same way as in Rel. 15/16 Type II codebooks (as shown in 3GPP standard specification).

In one example, the M_vFD basis vectors, g_f,l=[y_0,l^(f), y_1,l^(f)⋅ ⋅ ⋅ y_N₃_−1,l^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾] and n_3,l^(f)∈{0, 1, . . . , N₃−1}.

The vector y_t,l=[y_t,l⁽⁰⁾, y_t,l⁽¹⁾. . . y_t,l^(M^v⁻¹⁾] comprises entries of FD basis vectors with FD index t={0, 1, . . . , N₃−1}, which is an (FD) index associated with the precoding matrix.

In one example, the FD basis vectors are orthogonal DFT vectors, and

$y_{t, l}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} .$

In one example, the FD basis vectors are oversampled (or rotated) orthogonal DFT vectors with the oversampling (rotation) factor O₃, and

$y_{t, l}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{O_{3} N_{3}}},$

and the M_vFD basis vectors are also identified by the rotation index q_3,l∈{0, 1, . . . , O₃−1}. In one example, O₃is fixed (e.g., 1 or4), or configured (e.g., via RRC), or reported by the UE. In one example, the rotation factor is layer-common (one value for all layers), i.e., q_3,l=q₃.

In one example, each coefficient x_l,r,i,fcorresponding to row i, column f of the W_2,l,rfor layer l and TRP (or CSI-RS resource) r can be expressed as

$x_{l, r, i, f} = p_{l, r, ⌊ \frac{i}{L} ⌋}^{(1)} p_{l, r, i, f}^{(2)} φ_{l, r, i, f}$

similar to Rel. 16 enhanced Type II codebook (as shown in 3GPP standard specification).

In one embodiment, the UE is configured to report a CSI for N>1 TRPs/RRHs (where TRP corresponds to a NZP CSI-RS resource or a subset of CSI-RS antenna ports within a NZP CSI-RS resource), the CSI determined based on a codebook comprising components: (A) two separate basis matrices W₁, W_ffor SD and FD compression, respectively, and (B) coefficients {tilde over (W)}₂. In one example, the codebook can be configured via one higher layer parameter codebookType set to “typeII-cjt-model-r18,” or via two higher layer parameters codebookType set to “typeII-cjt-r18” and codebookMode set to “Model.”

In particular, the precoder for layer l is given by

$W_{l} = A_{l} C_{l} B_{l}^{H} = \frac{1}{γ} W_{1} {\tilde{W}}_{2} W_{f}^{H} = \frac{1}{γ} [\begin{matrix} W_{1, 1} & {\tilde{W}}_{2, 1} & W_{f, 1}^{H} \\ ⋮ \\ W_{1, N} & {\tilde{W}}_{2, N} & W_{f, N}^{H} \end{matrix}]$

where: (1) W_lis a P_CSIRS×N₃matrix whose columns are precoding vectors for N₃FD units, (2) W_l,ris a block diagonal matrix

$[\begin{matrix} B_{r} & 0 \\ 0 & B_{r} \end{matrix}]$

comprising 2 blocks that are associated with two antenna polarizations (two halves or groups of CSI-RS antenna ports) of TRP r and each of two blocks is a

$\frac{P_{CSIRS, r}}{2} \times L_{r} SD$

basis or port selection matrix (similar to Rel. 16 enhanced Type II codebook or Rel. 17 enhanced Type II codebook), or (3) {tilde over (W)}_2,ris a 2L_r×M_v,rcoefficients matrix, and (4) W_f,ris a N₃×M_v,rbasis matrix for FD basis matrix (similar to Rel. 16 enhanced Type II codebook). The columns of W_f,rcomprises vectors g_r,f,l=[y_0,l^(r,f)y_1,l^(r,f)⋅ ⋅ ⋅ y_N₃_−1,l^(rf)] or g_f_r_,l=[y_0,l^(fr)y_1,l^(fr)⋅ ⋅ ⋅ y_N₃_−1,l^(fr)] and (5) γ is a normalization factor.

In one example, for each

$r = 1, \dots, N, W_{1, r} = [\begin{matrix} B_{r} & 0 \\ 0 & B_{r} \end{matrix}]$

is a P_CSIRS,r×2L_rSD basis matrix, where the L_rSD basis vectors comprising columns of B_rare determined the same way as in Rel. 15/16 Type II codebooks (as shown in 3GPP standard specification)

In one example, the M_v,rFD basis vectors, g_r,f,l=[y_0,l^(r,f)y_1,l^(rf)⋅ ⋅ ⋅ y_N₃_−1,l^(r,f)]^T, f=0, 1, . . . , M_v,r−1, are identified by n_3,l,r(l=1, . . . , v) where n_3,l,r=[n_3,l,r⁽⁰⁾, . . . , n_3,l,r^(M^v,r⁻¹⁾] and n_3,l,r^(f)∈{0, 1, . . . , N₃−1}.

The vector y_t,l,r=[y_t,l,r⁽⁰⁾y_t,l,r⁽¹⁾⋅ ⋅ ⋅ y_t,l,r^(M^v,r⁻¹⁾] comprises entries of FD basis vectors with FD index t={0, 1, . . . , N₃−1}, which is an (FD) index associated with the precoding matrix.

In one example, the FD basis vectors are orthogonal DFT vectors, and

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3}}} .$

In one example, the FD basis vectors are oversampled (or rotated) orthogonal DFT vectors with the oversampling (rotation) factor O₃, and

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{O_{3} N_{3}}},$

and the M_v,rFD basis vectors are also identified by the rotation index q_3,l,r∈{0, 1, . . . , O₃−1}. In one example, O₃is fixed (e.g., 1 or4), or configured (e.g., via RRC), or reported by the UE. In one example, the rotation factor is layer-common (one value for all layers), i.e., q_3,l,r=q_3,r.

In one example, corresponding to row i, column f of the W_2,l,rfor layer l and TRP (or CSI-RS resource)

$r x_{l, r, i, f} = p_{l, r, ⌊ \frac{i}{L} ⌋}^{(1)} p_{l, r, i, f}^{(2)} φ_{l, r, i, f}$

similar to Rel. 16 enhanced Type II codebook (as shown in 3GPP standard specification).

In one embodiment, a UE is configured with a CSI reporting based on a codebook which is one of the two codebooks described in embodiments of the present disclosure. In one example, this configuration can be via a higher layer parameter CodebookMode.

In one embodiment, where in the SD basis selection matrix is replaced with a SD port selection matrix. In one example, the codebook in this case can be configured via one higher layer parameter codebookType set to “typeII-PortSelection-cjt-mode2-r18,” or via two higher layer parameters codebookType set to “typeII-PortSelection-cjt-r18” and codebookMode set to “Mode2.”

In one example,

$v_{m_{1}^{(r, i)}, m_{2}^{(r, i)}}$

is replaced with v_i_1,1r_d+i(cf. Rel.16 Type II codebook). For TRP r, the antenna ports per polarization are selected by the index i_1,1=[i_1,1,1. . . i_1,1,N], where

$i_{1, 1, r} \in {0, 1, \dots, ⌈ \frac{P_{CSI - RS, r}}{2 d} ⌉} .$

In one example, v_m₁_(r,i)_,m₂_(r,i)is replaced with v_i_1,1,r_d+i(cf. Rel.17 Type II codebook). For TRP r, K_1,r=2L_rports are selected from P_CSI-RS, r ports based on L_rvectors, v_m_(r,i), i=0, 1, . . . , L_r−1, which are identified by m=[m⁽¹⁾. . . m^(N)] m^(r)=[m^(r,0). . . m^(r,L−1)] and

$m^{(r, i)} \in {0, 1, \dots, \frac{P_{CSI - RS}}{2} - 1}$

which are indicated by the index i_1,2=[i_1,2,l. . . i_1,2,N], where

$i_{1, 2, r} \in {0, 1, \dots, (\begin{matrix} \frac{P_{CSI - RS, r}}{2} \\ L_{r} \end{matrix}) - 1} .$

In one embodiment, where in the SD basis selection matrix is replaced with a SD port selection matrix. In one example, the codebook in this case can be configured via one higher layer parameter codebookType set to “typeII-PortSelection-cjt-model-r18,” or via two higher layer parameters codebookType set to “typeII-PortSelection-cjt-r18” and codebookMode set to “Mode1.”

In one example,

$v_{m_{1}^{(r, i)}, m_{2}^{(r, i)}}$

is replaced with v_i_1,1,r_d+i(cf. Rel.16 Type II codebook). For TRP r, the antenna ports per polarization are selected by the index i_1,1=[i_1,1,1. . . i_1,1,N], where

$i_{1, 1, r} \in {0, 1, \dots, ⌈ \frac{P_{CSI - RS, r}}{2 d} ⌉} .$

In one example

$v_{m_{1}^{(r, i)}, m_{2}^{(r, i)}}$

is replaced with v_m_(r,i)(cf. Rel.17 Type II codebook). For TRP r, K_1,r=2L_rports are selected from P_CSI-RS, r ports based on L_rvectors, v_m_(r,i), i=0, 1, . . . , L_r−1, which are identified by: m=[m⁽¹⁾⋅ ⋅⋅ m^(N)] m^(r)=[m^(r,0)⋅ ⋅ ⋅ m^(r,L-1)] and

$m^{(r, i)} \in {0, 1, \dots, \frac{P_{CSI - RS}}{2} - 1}$

which are indicated by the index i_1,2=[i_1,2,l. . . i_1,2,N], where

$i_{1, 2, r} \in {0, 1, \dots, (\begin{matrix} \frac{P_{CSI - RS, r}}{2} \\ L_{r} \end{matrix}) - 1} .$

In one embodiment, where in the SD basis selection matrix is replaced with a SD port selection matrix.

In one example,

$v_{m_{1}^{(r, i)}, m_{2}^{(r, i)}}$

is replaced with v_i_1,1,r_d+i(cf. Rel.16 Type II codebook). For TRP r the antenna ports per polarization are selected by the index i_1,1=[i_1,1,1. . . i_1,1,N], where

$i_{1, 1, r} \in {0, 1, \dots, ⌈ \frac{P_{CSI - RS, r}}{2 d} ⌉} .$

In one example,

$v_{m_{1}^{(r, i)}, m_{2}^{(r, i)}}$

$m^{(r, i)} \in {0, 1, \dots, \frac{P_{CSI - RS}}{2} - 1}$

which are indicated by the index i_1,2=[i_1,2,l. . . i_1,2,N], where

$i_{1, 2, r} \in {0, 1, \dots, (\begin{matrix} \frac{P_{CSI - RS, r}}{2} \\ L_{r} \end{matrix}) - 1} .$

In one embodiment, a UE is configured with a CSI report for Z≥1 TRPs or CSI-RS resources (from a total of N_TRPNZP CSI-RS resources) based on a codebook, where the codebook is configured according to embodiments of the present disclosure. In addition, the FD basis vectors comprising columns of W_fcan be configured (e.g., via higher layer parameter) to be determined/reported according to at least one of the following embodiments/examples.

In one example, the FD basis vectors comprising columns of W_f,rfor CSI-RS resource r are determined/derived from TRP-common (CSI-RS resource common) M_vFD basis vectors and TRP-specific (CSI-RS resource specific) FD offset values φ_r. In other words, the UE determines/reports M_vFD basis vectors common for all CSI-RS resources and FD offset value(s) φ_rfor each CSI-RS resource r, where φ_r∈{0, 1, . . . , N₃−1} (or φ_r∈{1, . . . , N₃}). For example, W_f,rcan be derived from W_fincluding the TRP-common M_vFD basis vectors and TRP-specific FD offset value φ_r, e.g.,

$W_{f, r} = diag ([1 e^{j \frac{2 π}{N_{3}} φ_{r}} \dots \cdot e^{j \frac{2 π}{N_{3}} (N_{3} - 1) φ_{r}}]) W_{f},$

where diag([x₁, . . . , x_n]) is an n×n diagonal matrix including x₁, . . . , x_nas diagonal entries.

In one example, in addition to FD offset value(s) or index φ_r, an oversampled (rotated) value or index q_3,rfor FD offset value can be used to determine/derive W_f,r, where q_3,r∈{0, 1, . . . , O₃−1} (or q_3,r∈{1, . . . , O₃}). For example, W_f,rcan be expressed as

$W_{f, r} = e^{j \frac{2 π q_{3, r}}{N_{3} O_{3}}} \cdot diag ([1 e^{j \frac{2 π}{N_{3}} φ_{r}} \dots \cdot e^{j \frac{2 π}{N_{3}} (N_{3} - 1) φ_{r}}]) W_{f} = diag ([e^{j \frac{2 π q_{3, r}}{N_{3} O_{3}}} e^{j \frac{2 π (q_{3, r} + O_{3} φ_{r})}{N_{3} O_{3}}} \dots \cdot e^{j \frac{2 π (q_{3, r} + (N_{3} - 1) O_{3} φ_{r})}{N_{3} O_{3}}}]) W_{f} .$

In one example, O₃is fixed (e.g., 4 or8). In one example, O₃is configured (e.g., via higher layer from {1, 4}.

In one example, FD offset value φ_rand oversampled (rotated) value q_3,rfor the FD offset value can be combined into one value, denoted by φ_r, where φ_r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1} or φ_r∈{1, ⋅ ⋅ ⋅ , N₃O₃}. In this case, for example, φ_ris determined/reported by the UE, and the reported φ_rcan be decomposed into two values q_3,rand φ_rusing mod operation or operation to find remainder/quotient. For example, based on the two decomposed values, NW can identify W_f,rusing the above expression. In one example, φ_r=q_3,r+O₃φ_rwhen φ_r∈{0, 1, . . . , N₃−1}, q_3,r=φ_rmod O₃and

$φ_{r} = \frac{φ_{r} - q_{3, r}}{O_{3}} .$

In one example, φ_r=q_3,r+φ_rwhen φ_r∈{0, 1, . . . , O₃N₃−1}, q_3,r=φ_rmod N₃O₃and φ_r=φ_r−q_3,r.

In another example, a combined value φ_rof FD offset value(s) or index φ_rand an oversampled (rotated) value or index q_3,rfor FD offset value can be used to determine/derive W_f,r, where

$ϕ_{r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}} .$

In one example, when

$O_{3} = 4, ϕ_{r} \in {0, \frac{1}{4}, \frac{1}{2}, \frac{3}{4}, 1, \frac{5}{4}, \dots, N_{3} - \frac{1}{4}} .$

For example, W_f,rcan be expressed as

$W_{f, r} = diag ([1 e^{j \frac{2 {πϕ}_{r}}{N_{3}}} \dots \cdot e^{j \frac{2 π (N_{3} - 1) ϕ_{r}}{N_{3}}}]) W_{f} .$

In another example, a combined value φ_rof FD offset value(s) or index φ_rand an oversampled (rotated) value or index q_3,rfor FD offset value can be used to determine/derive W_f,r, where φ_r∈{0, 1, . . . , N₃O₃−1}. In one example, when O₃=4, φ_r∈{0, 1, . . . , 4₃−1}. For example, W_f,rcan be expressed as

$W_{f, r} = diag ([1 e^{j \frac{2 π ϕ_{r}}{N_{3} O_{3}}} \dots \cdot e^{j \frac{2 π (N_{3} - 1) ϕ_{r}}{N_{3} O_{3}}}]) W_{f} .$

In one example, FD offset value φ_ris layer-common, i.e., one value is associated with all layers l=1, ⋅ ⋅ ⋅ , v.

In one example, FD offset value φ_ris layer-specific, i.e., one value is associated with each layer l=1, ⋅ ⋅ ⋅ , v, and in this case, the notation for the FD offset value for example can be given by φ_r,l. The Z values are reported by the UE. Or Z−1 values are reported by the UE when one of the Z TRPs is reported by the UE as a reference (whose φ_rcan be fixed to 0).

In one example, an oversampled (rotated) value q_3,rfor FD offset value is layer-common, i.e., one value is associated with all layers l=1, ⋅ ⋅ ⋅ , v.

In one example, an oversampled (rotated) value q_3,rfor FD offset value is layer-specific, i.e., one value is associated with each layer l=1, ⋅ ⋅ ⋅ , v, and in this case, for example, the notation for the oversampled value can be given by q_3,r,l. The Z values are reported by the UE. Or Z−1 values are reported by the UE when one of the Z TRPs is reported by the UE as a reference (whose q_3,rcan be fixed to 0).

In one example, a combined value of q_3,rand φ_r, i.e., Or is layer-common, i.e., one values is associated with all layers l=1, ⋅ ⋅ ⋅ , v.

In one example, a combined value of q_3,rand φ_r, i.e., φ_ris layer-specific, i.e., one value is associated with each layer l=1, ⋅ ⋅ ⋅ , v. The Z values are reported by the UE. Or Z−1 values are reported by the UE when one of the Z TRPs is reported by the UE as a reference (whose φ_rcan be fixed to 0).

In one example, FD offset value φ_r,lis layer-specific, and an oversampled (rotated) value q_3,ris layer-common.

In one example, FD offset value φ_ris layer-common, and an oversampled (rotated) value q_3,r,lis layer-common.

In one example, the oversampling factor O₃is configured by NW via higher-layer signaling, i.e., RRC.

In one example, the oversampling factor O₃is fixed e.g., O₃=2, or O₃=4, or O₃=8.

In one example, the oversampling factor O₃is determined/reported by the UE.

In one example, a reference CSI-RS resource r* is layer-common, i.e., one reference is associated with all layers.

In one example, a reference CSI-RS resource r* is configured by NW. For example, r*=0 or the CSI resource with the lowest resource ID or a first of the N_TRPCSI-RS resources. In another example, the NW explicitly configures the reference CSI-RS resource r*.

In one example, a reference CSI-RS resource r* is implicitly determined. For example, r* is determined by strongest coefficient indicator (SCI) for layer l=1, i.e., r* is the CSI-RS resource index associated with the SCI of layer l=1.

In one example, a reference CSI-RS resource r* is determined and reported by the UE via CSI part 1.

In one example, a reference CSI-RS resource r_l* is layer-specific, i.e., one reference is associated with each layer.

In one example, a reference CSI-RS resource r_l* is configured by NW. For example, r_l*=0 for all layers or the CSI resource with the lowest resource ID or a first of the N_TRPCSI-RS resources for all layers. In another example, the NW explicitly configures the reference CSI-RS resource r_l* for each layer l.

In one example, a reference CSI-RS resource r_l* is implicitly determined. For example, r_l* is determined by strongest coefficient indicator (SCI) for each layer l, i.e., r_l* is the CSI-RS resource index associated with the SCI of each layer l.

In one example, a reference CSI-RS resource r_l* is determined for each layer l and reported by the UE via CSI part 1.

In this embodiment, φ_rand {tilde over (φ)}_rcan be used interchangeably.

In one embodiment, a UE can be configured to report M_vFD basis vectors from a total of N₃basis vectors separately (independently) for each layer l∈{1, . . . , v} of a rank v CSI reporting. The M_vFD basis vectors for each layer are common across CSI-RS resources (TRPs).

In one example, the M_vFD basis vectors, g_f,l=[y_0,l^(f)y_1,l^(f)⋅ ⋅ ⋅ y_N₃_−1,l^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾] and n_3,l^(f)∈{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), where i_1,6,l∈ {0, 1, . . . , X−1}. The UE reports i_1,6,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits.

In one example, the UE can be further configured to report FD offset value ϕ_r,lseparately (independently) for each layer l∈{1, . . . , v}.

In one example, ϕ_r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) and φ_r,l(l=1, . . . , v) where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and ϕ_r,l∈{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1) and i_offset,r,l, where i_1,6,l∈ {0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π φ_{r, l}}{N_{3}}} .$

In one example, ϕ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, ϕ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, ϕ_r,lis indicated using an existing indicator, for example, i_1,5,r,l, i.e., i_offset,r,l=i_1,5,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_1,5,r,lis ┌log₂N₃┐ bits.

In one example, the UE can be further configured to report FD offset value ϕ_r,lseparately (independently) for each layer l∈{1, . . . , v} and to report an oversampled (rotated) value q_3,r,lseparately (independently) for each layer l∈{1, . . . , v}.

In one example, ϕ_r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, q_3,r,lis indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v), φ_r,l(l=1, . . . , v), and q_3,r,l(l=1, . . . , v), where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, ϕ_r,l∈{0, 1, . . . , N₃−1}, and q_3,r,l∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), i_offset,r,l, and i_OS,r,lwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r,l{0, 1, . . . , O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(=1, . . . , v) and i_OS,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π t n_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r, l} O_{3} + q_{3, r, l})}{N_{3} O_{3}}} .$

In one example, ϕ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, ϕ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, q_3,r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, q_3,r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, a combined value {tilde over (φ)}_r,lof φ_r,land q_3,r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃O₃┐ bits.

In one example, a combined value {tilde over (φ)}_r,lof φ_r,land q_3,r,lis indicated using an indicator, e.g., i_offset,r,l, where

$i_{offset, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_offset,r,lis ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) and {tilde over (φ)}_r,l(l=1, . . . , v), where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and {tilde over (φ)}_r,l∈{0, 1, . . . , N₃O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,r,lwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π t n_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π {\tilde{φ}}_{r, l}}{N_{3} O_{3}}} .$

In one example, {tilde over (φ)}_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, {tilde over (φ)}_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, {tilde over (φ)}_r,lis indicated using an existing indicator, for example, i_1,5,r,l, i.e., i_offset,r,l=i_1,5,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}, hence the payload of i_1,5,r,lis ┌log₂N₃O₃┐ bits.

In one example, {tilde over (φ)}_r,lis indicated using an existing indicator, for example, i_1,5,r,l, i.e.,

$i_{offset, r, l} = i_{1, 5, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_1,5,r,lis ┌log₂N₃O₃┐ bits.

$n_{3, l, r} = [n_{3, l, r}^{(0)}, \dots, n_{3, l, r}^{(M_{υ} - 1)}], n_{3, l, r}^{(f)} \in {0, 1, \dots, N_{3} O_{3} - 1},$

and n_3,l,r^(f)=n_3,lO₃+{tilde over (φ)}_r,lor (n_3,lO₃+{tilde over (φ)}_r,l)mod N₃O₃which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,r,lwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits.

In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π t n_{3, l, r}^{(f)}}{N_{3} O_{3}}} .$

$n_{3, l, r} = [n_{3, l, r}^{(0)}, \dots, n_{3, l, r}^{(M_{v} - 1)}], n_{3, l, r}^{(f)} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

and n_3,l,r^(f)=n_3,l+{tilde over (φ)}_r,lor (n_3,l+{tilde over (φ)}_r,l)mod N₃which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,r,lwhere i_1,6,l∈{0, 1, . . . , X−1} and

$i_{offset, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}} .$

The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π t n_{3, l, r}^{(f)}}{N_{3}}} .$

In one example, the UE can be further configured to report FD offset value φ_r,lseparately (independently) for each layer l∈{1, . . . , v} and to report an oversampled value q_3,rcommon for all layers l∈{1, . . . , v}.

In one example, φ_r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, q_3,ris indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v), φ_r,l(l=1, . . . , v), and q_3,r, where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r,l∈{0, 1, . . . , N₃−1}, and q_3,r∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), i_offset,r,l, and i_OS,rwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r,l∈{0, 1, . . . , O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r,l(=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits.

In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r, l} O_{3} + q_{3, r})}{N_{3} O_{3}}} .$

In one example, φ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, φ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, q_3,r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, the UE can be further configured to report FD offset value φ_rcommon for all layers l∈{1, . . . , v}.

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) and φ_r(l=1, . . . , v) where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{, 1, . . . , N₃−1}, and φ_r∈{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1) and i_offset,r, where i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, . . . , N₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits.

In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 {πφ}_{r}}{N_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, φ_ris indicated using an existing indicator, for example, i_1,5,r, i.e., i_offset,r=i_1,5,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_1,5,ris ┌log₂N₃┐ bits.

In one example, the UE can be further configured to report FD offset value φ_rcommon for all layers l∈{1, . . . , v} and to report an oversampled (rotated) value q_3,r,lseparately (independently) for each layer l∈{1, . . . , v}.

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, q_3,r,lis indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v), φ_r, and q_3,r,l(l=1, . . . , v), where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r∈{0, 1, . . . , N₃−1} and q_3,r,l∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), i_offset,r, and i_OS,r,lwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r,l∈{0, 1, . . . , O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r(l=1, . . . , v) and i_OS,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits.

In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r} O_{3} + q_{3, r, l})}{N_{3} O_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, q_3,r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, q_3,r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, the UE can be further configured to report FD offset value φ_rcommon for all layers l∈{1, . . . , v} and to report an oversampled value q_3,rcommon for all layers l∈{1, . . . , v}.

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, q_3,ris indicated using an indicator, e.g., i_OS,r, where i_OS,r∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,ris ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v), φ_r, and q_3,r, where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r∈{0, 1, . . . , N₃−1}, and q_3,r∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), i_offset,r, and i_OS,rwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r∈{0, 1, . . . , O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,rand i_OS,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r} O_{3} + q_{3, r})}{N_{3} O_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, q_3,r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, a combined value {tilde over (φ)}_rof φ_rand q_3,ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}, hence the payload of i_offset,ris ┌log₂N₃O₃┐ bits.

In one example, a combined value Or of φ_rand q_3,ris indicated using an indicator, e.g., i_offset,r, where

$i_{offset, r} \in {0, \frac{1}{O_{3}}, ..., \frac{O_{3} - 1}{O_{3}}, 1, ..., N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_offset,ris ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l(l=1, . . . , v) and <p, where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and {tilde over (φ)}_r∈{0, 1, . . . , N₃O₃−1} which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,rwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π t n_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π t {\tilde{φ}}_{r}}{N_{3} O_{3}}} .$

In one example, {tilde over (φ)}_r*=0 for reference CSI-RS resource r* (hence no report is needed). Hence, i_offset[i_offset,2, . . . , i_offset,N], where N≤N_TRPis the number of selected CSI-RS resources (reported by UE and inferred from N_TRP-bit bitmap in CSI part 1). In this case, the payload of i_offsetis (N−1)┌log₂O₃N₃┐.

For example, codebook for precoder equation can be written as follows:

$W_{q_{1}, q_{2}, n_{1}, n_{2}, n_{3, l,} p_{l}^{(1)}, p_{l}^{(2)}, φ_{l, t}}^{l} = \frac{1}{\sqrt{N_{1} N_{2} γ_{t, l}}}$

$[\begin{matrix} \sum_{i = 0}^{L_{σ_{1} - 1}} v_{m_{1, 1}^{(i)}, m_{2, 1}^{(i)}} p_{l, 0}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, 1}^{(f)} p_{l, i, f, 1}^{(2)} φ_{l, i, f, 1} \\ \sum_{i = 0}^{L_{σ_{1} - 1}} v_{m_{1, 1}^{(i)}, m_{2, 1}^{(i)}} p_{l, 1}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, 1}^{(f)} p_{l, i, + L_{σ_{1}} f, 1}^{(2)} φ_{l, i + L_{σ_{1}}, f, 1} \\ \sum_{i = 0}^{L_{σ_{2} - 1}} v_{m_{1, 2}^{(i)}, m_{2, 2}^{(i)}} p_{l, 0}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, 2}^{(f)} p_{l, i, f, 2}^{(2)} φ_{l, i, f, 2} \\ \sum_{i = 0}^{L_{σ_{2} - 1}} v_{m_{1, 2}^{(i)}, m_{2, 2}^{(i)}} p_{l, 1}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, 2}^{(f)} p_{l, i + L_{σ_{2}}, f, 2}^{(2)} φ_{l, i + L_{σ_{2}}, f, 2} \\ ⋮ \\ \sum_{i = 0}^{L_{σ_{N} - 1}} v_{m_{1, N}^{(i)}, m_{2, N}^{(i)}} p_{l, 0}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, N}^{(f)} p_{l, i, f, N}^{(2)} φ_{l, i +, f, N} \\ \sum_{i = 0}^{L_{σ_{N} - 1}} v_{m_{1, N}^{(i)}, m_{2, N}^{(i)}} p_{l, 1}^{(1)} & \sum_{f = 0}^{M_{υ} - 1} y_{t, l, N}^{(f)} p_{l, i + L_{σ_{N}}, f, N}^{(2)} φ_{l, i + L_{σ_{N}}, f, N} \end{matrix}]$

In one example, {tilde over (φ)}_ris indicated using an existing indicator, for example, i_1,5,r, i.e., i_offset,r=i_1,5,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}, hence the payload of i_1,5,ris ┌log₂N₃O₃┐ bits.

In one example, {tilde over (φ)}_ris indicated using an existing indicator, for example, i_1,5,r, i.e.,

$i_{offset, r} = i_{1, 5, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_1,5,ris ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors for CSI-RS resource r, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by n_3,l,r(l=1, . . . , v and r=1, . . . , Z) and {tilde over (φ)}_r, where n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃O₃−1}, and n_3,l,r^(f)=n_3,lO₃+{tilde over (φ)}_ror (n_3,lO₃+{tilde over (φ)}_r)mod N₃O₃which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,rwhere i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3} O_{3}}} .$

$n_{3, l, r} = [n_{3, l}^{(0)}, \dots, n_{3, l}^{(M_{υ} - 1)}], n_{3, l, r}^{(f)} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

and n_3,l,r^(f)=n_3,l+{tilde over (φ)}_ror (n_3,l+{tilde over (φ)}_r)mod N₃which are indicated by means of the indices i_1,6,l(for M_v>1), and i_offset,rwhere i_1,6,l∈{0, 1, . . . , X−1} and

$i_{offset, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}} .$

The UE reports i_1,6,l(l=1, . . . , v) and i_offset,r(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} N_{3} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l=0.

In one example,

$X = (\begin{matrix} N_{3} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3}}} .$

FIG. 16 illustrates an example of window-based FD basis vector selection 1600 according to embodiments of the present disclosure. An embodiment of the window-based FD basis vector selection 1600 shown in FIG. 16 are for illustration only.

In one embodiment, a UE can be configured to report M_vFD basis vectors from a set/window of N FD basis vectors, where the M_vFD basis vectors are selected freely (independently) for each layer l∈{1, . . . , v} of a rank v CSI reporting, and the set/window is a subset of a total of N₃basis vectors. In one example, N≤N₃. In one example, N≤N₃. The M_vFD basis vectors for each layer are common across CSI-RS resources (TRPs).

The indices of the FD basis vectors in the set/window are given by mod(M_init+n, N₃), n=0, 1, . . . , N−1, which comprises N adjacent FD basis indices with modulo-shift by N₃, where M_initis the starting index of the window. An example is shown in FIG. 11. Note that the window-based basis set/matrix W_fis completely parameterized by M_initand N. At least one of the following examples can be used/configured to determine W_f.

In one example, both M_initand N are fixed.

In one example, both M_initand N are configured to the UE (via RRC or/and MAC CE or/and DCI).

In one example, both M_initand N are reported by the UE.

In one example, M_initis fixed and N is configured to the UE (via RRC or/and MAC CE or/and DCI).

In one example, M_initis fixed and N is reported by the UE.

In one example, M_initis configured to the UE (via RRC or/and MAC CE or/and DCI) and N is fixed.

In one example, M_initis configured to the UE (via RRC or/and MAC CE or/and DCI) and N is reported by the UE.

In one example, M_initis reported by the UE and N is fixed.

In one example, M_initis reported by the UE and N is configured to the UE (via RRC or/and MAC CE or/and DCI).

For Z>1 TRPs (CSI-RS resources), M_initcan be fixed to (or configured with or reported) as the same/common value for all TRPs, or M_initcan be fixed to (or configured with or reported) same or different values across TRPs. Likewise, for Z>1 TRPs (CSI-RS resources), N can be fixed to (or configured with or reported) the same/common value for all TRPs, or N can be fixed to (or configured with or reported) same or different values across TRPs.

In one example, the window for FD basis vector reporting is independent/separate across TRPs (CSI-RS resources), i.e., one window for each TRP, and M_initis reported. When M_init,ris reported per TRP r, it can be reported via an indicator i_init,ror i_1,5,r, which can be given

$by i_{1, 5, r} = {\begin{matrix} M_{init, r} & M_{init, r} = 0 \\ M_{init, r} + W_{r} & M_{init, r} < 0 \end{matrix} .$

In one example, W_r=N_r=aM_vwhere a can be fixed, e.g., a=2. In one example, N_ris configured. In one example, W_r=min(N_r, N₃). In one example, W_r*=aM_vfor one (a reference) CSI-RS resource r*, and W_r=bN₃for r≠r*, e.g., a=2, b=1. The M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_init,rand n_3,l(l=1, . . . v) where M_init,r∈{−W_r+1, −W_r+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], and n_3,l^(f)∈{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,5,rand i_1,6,l(for M_v>1), where i_1,5,r∈{0, 1, . . . , W_r−1} and i_1,6,l∈{0, 1, . . . , X−1}. The UE reports i_1,5,rand i_1,6,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W_{r} - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W_{r} \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5,rreporting is ┌log₂W_r┐ bits.

In one example, M_init,r=M_initwhen the same (one) value for M_initis reported for all TRPs, and in this case, it can be reported via an indicator i_initor i_1,5. Note W_rcan be the same or different for r=1, . . . , Z.

In one example, M_init,rcan be the same or different across TRPs, and in this case, W_rcan be the same or different for r=1, . . . , Z.

In one example, the window for FD basis vector reporting is independent/separate across TRPs (CSI-RS resources), i.e., one window for one TRP (e.g., a reference TRP r*), and M_initis reported. When M_initis reported for the TRP, it can be reported via an indicator i_initor i_1,5, which can be given by

$i_{1, 5} = {\begin{matrix} M_{init} & M_{init} = 0 \\ M_{init} + W & M_{init} < 0 \end{matrix} .$

In one example, W=N=aM_vwhere a can be fixed, e.g., a=2. In one example, N is configured. In one example, W=min(N, N₃). The M_vFD basis vectors, g_f,l=[y_0,l^(f)y_1,l^(f)⋅ ⋅ ⋅ y_N₃_−1,l^(f)]^T, f=0, 1, . . . , M_v−1 are identified by M_initand n_3,l(l=1, . . . , v) where M_init{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], and n_3,l^(f)∈ {0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1), where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits.

In one example, the UE can be further configured to report FD offset value φ_r,lseparately (independently) for each layer l∈{1, . . . , v}.

In one example, φ_r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and φ_r,l(l=1, . . . , v) where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and φ_r,l∈{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π φ_{r, l}}{N_{3}}} .$

In one example, φ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, φ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, φ_r, is indicated using an existing indicator, for example, i_1,5,r,l, i.e., i_offset,r,l=i_1,5,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_1,5,r,lis ┌log₂N₃┐ bits.

In one example, the UE can be further configured to report FD offset value φ_r,lseparately (independently) for each layer l∈{1, . . . , v} and to report an oversampled (rotated) value q_3,r,lseparately (independently) for each layer l∈{1, . . . , v}.

In one example, φ_r, is indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, q_3,r,lis indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and φ_r,l(l=1, . . . , v), and q_3,r,l(l=1, . . . , v) where M_init∈{−W+1, −W+2, . . . , 0}, [n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r,l∈{0, 1, . . . , N₃−1}, and q_3,r,l∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, and i_OS,r,lwhere i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r,l∈ {0, 1, . . . , O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r,l(=1, . . . , v) and i_OS,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n=0. In one example,

$X = (\begin{matrix} W \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r, l} O_{3} + q_{3, r, l})}{N_{3} O_{3}}} .$

In one example, φ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, φ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, q_3,r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, q_3,r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, a combined value φ_r,lof φ_r,land q_3,r,lis indicated using an indicator, e.g., i_offset,r,l, where

$i_{offset, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_offset,r,lis ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and {tilde over (φ)}_r,l(l=1, . . . , v) where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and {tilde over (φ)}_r,l∈{0, 1, . . . , N₃O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{\frac{2 ω {\tilde{φ}}_{r, l}}{N_{3} O_{3}}} .$

In one example, {tilde over (φ)}_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, {tilde over (φ)}_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, {tilde over (φ)}_r,lis indicated using an existing indicator, for example, i_1,5,r,l, i.e.,

$i_{offset, r, l} = i_{1, 5, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_1,5,r,lis ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l,r(l=1, . . . , v and r=1, . . . , Z) and {tilde over (φ)}_r,l(l=1, . . . , v) where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l,r^(f)=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃O₃−1}, and n_3,l,r^(f)=n_3,lO₃+{tilde over (φ)}_r,lor (n_3,lO₃+{tilde over (φ)}_r,l)mod N₃O₃which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{v} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{v} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3} O_{3}}} .$

$M_{init} \in {- W + 1, - W + 2, \dots, 0}, n_{3, l, r} = [n_{3, l, r}^{(0)}, \dots, n_{3, l, r}^{(M_{υ} - 1)}], n_{3, l, r}^{(f)} \in {0, \frac{1}{o_{3}}, \dots, \frac{o_{3} - 1}{o_{3}}, 1, \dots, N_{3} - \frac{1}{o_{3}}},$

and n_3,l,r=n_3,l+{tilde over (φ)}_r,lor (n_3,l+{tilde over (φ)}_r,l)mod N₃which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and

$i_{offset, r, l} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}} .$

The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0.

In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3}}} .$

In one example, φ_r,lis indicated using an indicator, e.g., i_offset,r,l, where i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,r,lis ┌log₂N₃┐ bits.

In one example, q_3,ris indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and φ_r,l(l=1, . . . , v), and q_3,rwhere M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r,l∈{0, 1, . . . , N₃−1}, and q_3,r∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r,l, and i_OS,rwhere i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r,l∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r∈{0, 1, . . . , O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,r, (l=1, . . . , v) and i_OS,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r, l} O_{3} + q_{3, r})}{N_{3} O_{3}}} .$

In one example, φ_r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, φ_r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, q_3,r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, the UE can be further configured to report FD offset value φ_rcommon for all layers l∈{1, . . . , v}.

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and φ_rwhere M_int∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and φ_r{0, 1, . . . , N₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 {π tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 {πφ}_{r}}{N_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, φ_ris indicated using an existing indicator, for example, i_1,5,r, i.e., i_offset,r=i_1,5,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_1,5,ris ┌log₂N₃┐ bits (e.g., for r≠r*).

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, q_3,r,lis indicated using an indicator, e.g., i_OS,r,l, where i_OS,r,l∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,r,lis ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n₃, (l=1, . . . , v) and φ_rand q_3,r,l(l=1, . . . , v), where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, φ_r∈{0, 1, . . . , N₃−1}, and q_3,r,l∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, and i_OS,r,lwhere i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈ {0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r,l∈{0, 1, . . . , O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rand i_OS,r,l(l=1, . . . , v) via the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r} O_{3} + q_{3, r, l})}{N_{3} O_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, q_3,r*,l=0 for reference CSI-RS resource r* for all layers l (hence no report is needed).

In one example, q_3,r_l_*,l=0 for reference CSI-RS resource r_l* for each layer l (hence no report is needed).

In one example, φ_ris indicated using an indicator, e.g., i_offset,r, where i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1}, hence the payload of i_offset,ris ┌log₂N₃┐ bits.

In one example, q_3,ris indicated using an indicator, e.g., i_OS,r, where i_OS,r∈{0, 1, ⋅ ⋅ ⋅ , O₃−1}, hence the payload of i_OS,ris ┌log₂O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l(l=1, . . . , v) and φ_rand q_3,r, where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, <φ_rF {0, 1, . . . , N₃−1}, and q_3,r∈{0, 1, . . . , O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, and i_OS,rwhere i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃−1} and i_OS,r∈{0, 1, . . . , O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rand i_OS,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π (φ_{r} O_{3} + q_{3, r})}{N_{3} O_{3}}} .$

In one example, φ_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, q_3,r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, a combined value Or of φ_rand q_3,ris indicated using an indicator, e.g., i_offset,r, where

$i_{offset, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_offset,ris ┌log₂N₃O₃┐ bits.

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n₃₁(l=1, . . . , v) and Or, where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l=[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃−1}, and φ_r∈{0, 1, . . . , N₃O₃−1} which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ ,N₃O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π {\tilde{φ}}_{r}}{N_{3} O_{3}}} .$

In one example, {tilde over (φ)}_r*=0 for reference CSI-RS resource r* (hence no report is needed).

In one example, {tilde over (φ)}_ris indicated using an existing indicator, for example, i_1,5,r, i.e.,

$i_{offset, r} = i_{1, 5, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

hence the payload of i_1,5,ris ┌log₂N₃O₃┐ bits (e.g., for r≠r*).

In one example, the M_vFD basis vectors, g_f,l,r=[y_0,l,r^(f)y_1,l,r^(f)⋅ ⋅ ⋅ y_N₃_−1,l,r^(f)]^T, f=0, 1, . . . , M_v−1, are identified by M_initand n_3,l,r(l=1, . . . , v and r=1, . . . , Z) and Or where M_init∈{−W+1, −W+2, . . . , 0}, n_3,l,r[n_3,l⁽⁰⁾, . . . , n_3,l^(M^v⁻¹⁾], n_3,l^(f)∈{0, 1, . . . , N₃O₃−1}, and n_3,l,r^(f)=n_3,lO₃+φ_ror (n_3,lO₃+{tilde over (φ)}_r)mod N₃O₃which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3} O_{3}}} .$

and n_3,l,r^(f)=n_3,l+{tilde over (φ)}_ror (n_3,lO₃+{tilde over (φ)}_r)mod N₃which are indicated by means of the indices i_1,5and i_1,6,l(for M_v>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and

$i_{offset, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

The UE reports i_1,5and i_1,6,l(l=1, . . . , v) and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M_{υ} - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n_3,l⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M_{υ} \end{matrix}) .$

The payload for i_1,6,lreporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l, r}^{(f)}}{N_{3}}} .$

In one embodiment, for each example in each embodiment, the M_vFD basis vectors are layer-common, i.e., one set of M_vFD basis vectors is associated with all layers. In this case, M_v=M, and n_3,l=n₃. The other details can be directly extended from each example in each embodiment.

For example, (e.g., joint indicator disclosed in the present disclosure) the M FD basis vectors, g_f,r=[y_0,r^(f)y_1,r^(f)⋅ ⋅ ⋅ y_N₃_−1,r^(f)]^T, f=0, 1, . . . , M−1, are identified by M_initand n₃where M_init∈{−W+1, −W+2, . . . , 0}, n₃=[n₃⁽⁰⁾, . . . , n₃^(M-1)], n₃^(f)∈{0, 1, . . . , W−1}, and {tilde over (φ)}_r∈{0, 1, . . . , N₃O₃−1} which are indicated by means of the indices i_1,5and i_1,6(for M>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,5and i_1,6and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n₃⁽⁰⁾=0. In one example,

$X = (\begin{matrix} W \\ M \end{matrix}) .$

The payload for i_1,6reporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example

$y_{t, r}^{(f)} = e^{j \frac{2 π {tn}_{3}^{(f)}}{N_{3}}} e^{\frac{2 π {\tilde{φ}}_{r}}{N_{3} O_{3}}} .$

In one example, M_initis fixed.

In one example, the M_vFD basis vectors, g_f,r=[y_0,r^(f)y_1,r^(f)⋅ ⋅ ⋅ y_N₃_−1,r^(f)]^T, f=0, 1, . . . , M−1, are identified by M_initand n_3,r(r=1, . . . , Z) and {tilde over (φ)}_rwhere M_init{−W+1, −W+2, . . . , 0}, n_3,r=[n_3,r⁽⁰⁾, . . . , n_3,r^(M-1)], n_3,r^(f)∈{0, 1, . . . , N₃O₃−1}, and n_3,r^(f)=n₃O₃+{tilde over (φ)}_ror (n₃O₃+{tilde over (φ)}_r)mod N₃O₃which are indicated by means of the indices i_1,5and i_1,6(for M>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈{0, 1, ⋅ ⋅ ⋅ , N₃O₃−1}. The UE reports i_1,5and i_1,6and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n₃⁽⁰⁾=0. In one example

$X = (\begin{matrix} W \\ M \end{matrix}) .$

The payload for i_1,6reporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, r}^{(f)} = e^{j \frac{2 π {tn}_{3, r}^{(f)}}{N_{3} O_{3}}} .$

$M_{init} \in {- W + 1, - W + 2, \dots, 0}, n_{3, r} = [n_{3, r}^{(0)}, \dots, n_{3, r}^{(M - 1)}], n_{3, r}^{(f)} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}},$

and n_3,r^(f)=n₃+{tilde over (φ)}_ror (n₃+{tilde over (φ)}_r)mod N₃which are indicated by means of the indices i_1,5and i_1,6(for M>1) and i_offset,r, where i_1,5∈{0, 1, . . . , W−1} and i_1,6,l∈{0, 1, . . . , X−1} and i_offset,r∈

${0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}} .$

The UE reports i_1,5and i_1,6and i_offset,rvia the PMI included in the CSI report. In one example,

$X = (\begin{matrix} W - 1 \\ M - 1 \end{matrix})$

when one of the FD basis vectors is fixed, e.g., n₃⁽⁰⁾=0. In one example

$X = (\begin{matrix} W \\ M \end{matrix}) .$

The payload for i_1,6reporting is ┌log₂X┐ bits. The payload for i_1,5reporting is ┌log₂W┐ bits. In one example,

$y_{t, r}^{(f)} = e^{j \frac{2 π {tn}_{3, r}^{(f)}}{N_{3}}} .$

In one example, when M∈A, N=2, e.g., A={1}. In one example, this embodiment is applied for N=4 when M=2.

In one example, this embodiment is applied for N=2 and M=2.

In one embodiment, the UE is configured to report (M or) M_vFD basis vectors according to embodiments (window-based) or embodiment (free selection) based on a condition, as disclosed in the present disclosure. The condition is according to at least one of the following examples.

In one example, the reporting is according to embodiment, as disclosed in the present disclosure, (window-based) when N₃>t and is according to embodiment (free selection) when N₃≤t, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N₃≥t and is according to embodiment (free selection) when N₃<t, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N₃<t and is according to embodiment (free selection) when N₃≥t, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N₃≤t and is according to embodiment (free selection) when N₃>t, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N_TRPor Z>k and is according to embodiment (free selection) when N_TRPor Z≤k, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N_TRPor Z₃≥k and is according to embodiment (free selection) when N_TRPor Z<k, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N_TRPor Z<k and is according to embodiment (free selection) when N_TRPor Z≥k, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when N_TRPor Z≤k and is according to embodiment (free selection) when N_TRPor Z>k, as disclosed in the present disclosure.

In one example, the reporting is according to embodiment (window-based) when corresponding both conditions in examples, as disclosed in the present disclosure, respectively, are satisfied, and is according to embodiment (free selection) when corresponding both conditions in examples, as disclosed in the present disclosure, respectively, are satisfied. Here, (A, B) belong to {(1, 5), (1, 6), (1, 7), (1, 8), (2, 5), (2, 6), (2, 7), (2, 8), (3, 5), (3, 6), (3, 7), (3, 8), (4, 5), (4, 6), (4, 7), (4, 8)}.

Here, t is a threshold that can be fixed (e.g., t=19) or configured or reported by the UE. Here, k is a threshold that can be fixed (e.g., k=2) or configured or reported by the UE.

In one embodiment, the UE can be configured to report M, FD basis vectors (free selection and/or window-based selection) for a first group of CSI-RS resources and further report FD offset value(s) φ_rand/or oversampled value(s) q_3,lfor FD offset value(s) for a second group of CSI-RS resources.

In on example, each example in embodiments, as disclosed in the present disclosure, can be an example of embodiment as disclosed in the present disclosure when a first group of CSI-RS resources corresponds to (or includes) a reference CSI-RS resource r* and a second group of CSI-RS resources corresponds to (or includes) CSI-RS resources r≠r*.

In on example, FD offset value(s) φ_ris TRP-common for the second group of CSI-RS resources, i.e., one value is associated for the CSI-RS resources of the second group.

In on example, FD offset value(s) φ_ris TRP-specific for the second group of CSI-RS resources, i.e., one value is associated for each CSI-RS resource in the second group.

In on example, oversampled value(s) q_3,ris TRP-common for the second group of CSI-RS resources, i.e., one value is associated for the CSI-RS resources of the second group.

In on example, oversampled value(s) q_3,ris TRP-specific for the second group of CSI-RS resources, i.e., one value is associated for each CSI-RS resource in the second group.

In one example, any combination of at least two examples above can be this example.

In on example, a combined value of φ_rand q_3,r, e.g., {tilde over (φ)}_ris TRP-common for the second group of CSI-RS resources, i.e., one value is associated for the CSI-RS resources of the second group.

In on example, a combined value of φ_rand q_3,r, e.g., {tilde over (φ)}_ris TRP-specific for the second group of CSI-RS resources, i.e., one value is associated for each CSI-RS resource in the second group.

Similar to each example under embodiment as disclosed in the present disclosure, the above example can be extended using separate indicator or joint indicator.

In one embodiment, at least one of the examples in/under embodiments, as disclosed in the present disclosure, is/are an optional feature, i.e., UE-optional, wherein the UE reports its capability whether to support the UE optional feature or not. The NW can configure the UE-optional feature only when the UE reports that it is supported.

In one example, examples as disclosed in the present disclosure are a UE-optional.

In one example, examples as disclosed in the present disclosure are a basic feature and examples as disclosed in the present disclosure are UE-optional.

In one example, examples as disclosed in the present disclosure are basic features and UE-optional.

In one example, examples as disclosed in the present disclosure are UE-optional, where X and Y are in {1, 2, 3, 4, 5, 6}.

Each of the examples in this embodiment is also directly extended to the case of embodiments as disclosed in the present disclosure.

In one example, reporting q_3,r(q_3,r,l) is a UE-optional feature where q_3,ris described in (any relevant) one of the examples as disclosed in the present disclosure.

In one example, reporting i_offset,r(i_offset,r,l) is a UE-optional feature where i_offset,ris described in (any relevant) one of the examples as disclosed in the present disclosure.

In one example, reporting i_offset,r(i_offset,r,l) for

$i_{offset, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}}$

is a UE-optional feature where i_offset,ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one example, reporting i_offset,r(i_offset,r,l) for i_offset,r∈{0, 1, . . . , N₃O₃−1} is a UE-optional feature where i_offset,ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one example, reporting i_1,5,r(i_1,5,r,l) for

$i_{1, 5, r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}}$

is a UE-optional feature where i_offset,ris described in (any relevant) one of the examples as disclosed in the present disclosure.

In one example, reporting i_1,5,r(i_1,5,r,l) for i_1,5,r∈{0, 1, . . . , N₃O₃−1} is a UE-optional feature where i_offset,ris described in (any relevant) one of the examples in embodiments as disclosed in the present disclosure.

In one example, reporting i_OS,r(i_OS,r,l) is a UE-optional feature where i_OS,ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one example, reporting {tilde over (φ)}_r({tilde over (φ)}_r,l) (a combined value of φ_rand q_3,r) is a UE-optional feature where {tilde over (φ)}_ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one example, reporting {tilde over (φ)}_r({tilde over (φ)}_r,l) (a combined value of φ_rand q_3,r) for

${\tilde{φ}}_{r} \in {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}}$

is a UE-optional feature where {tilde over (φ)}_ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one example, reporting {tilde over (φ)}_r({tilde over (φ)}_r,l) (a combined value of φ_rand q_3,r) for {tilde over (φ)}_r∈{0, 1, . . . , N₃O₃−1} is a UE-optional feature where {tilde over (φ)}_ris described in (any relevant) one of the examples in embodiment as disclosed in the present disclosure.

In one embodiment, at least one of the examples in/under embodiments, as disclosed in the present disclosure, is/are an optional feature based on the number of CSI-RS resources Z.

In one example, examples as disclosed in the present disclosure are UE-optional only when Z≥t.

In one example, examples as disclosed in the present disclosure are UE-optional only when Z>t.

In one example, example as disclosed in the present disclosure are not UE-optional only when Z<t.

In one example, examples as disclosed in the present disclosure are not UE-optional only when Z≤t.

In one example, t=1. In one example, t=2. In one example, t=3. In one example, t=4.

In one embodiment, a UE can be configured to select/determine FD basis offset values φ_rfrom a set/window W_φ, of an index set Φ described in embodiments as disclosed in the present disclosure. In one example, Φ={0, 1, ⋅ ⋅ ⋅ , N₃O₃−1} for O₃>1. In one example,

$Φ = {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{3} - \frac{1}{O_{3}}}$

for O₃>1. In one example, Φ={0, 1, ⋅ ⋅ ⋅ , N₃−1}.

In one example, a set/window of an index set (for φ_r) can be given by W_φ={0, 1, ⋅ ⋅ ⋅ , N O₃−1}, where N, <N₃.

In one example, a set/window of an index set (for φ_r) can be given by

$W_{φ} = {0, \frac{1}{O_{3}}, \dots, \frac{O_{3} - 1}{O_{3}}, 1, \dots, N_{φ} - \frac{1}{O_{3}}},$

where N≤N₃.

In one example, a set/window of an index set (for φ_r) can be given by W_φ={0, 1, ⋅ ⋅ ⋅ , N_φ−1}, where N_φ<N₃.

In one example, the indices of the FD offsets φ_rin a set/window of an index set can be given by mod(M_init,φ+n, N₃), n=0, 1, . . . , N_φ−1, where M_init,φ, is the starting index of the window.

In one example, the indices of the FD offsets φ_rin a set/window of an index set can be given by mod(M_init,φ+n, N₃O₃), n=0, 1, . . . , N_φO₃−1, where M_init,φ, is the starting index of the window.

In one example, the indices of the FD offsets φ_rin a set/window of an index set can be given by mod(M_init,φ+n, N₃O₃), n=0, 1, . . . , N_φ−1, where M_init,φ, is the starting index of the window.

In one example, the indices of the FD offsets φ_rin a set/window of an index set can be given by mod

$(M_{init, φ} + n, N_{3}), n = 0, \frac{1}{O_{3}}, ..., \frac{O_{3} - 1}{O_{3}}, 1, ..., N_{φ} - \frac{1}{O_{3}},$

where M_init,φ, is the starting index of the window.

In one example, at least one of the following examples can be used/configured to determine FD offset values.

In one example, both M_init,φ and N_φ are fixed.

In one example, both M_init,φ and N_φ are configured to the UE (via RRC or/and MAC CE or/and DCI).

In one example, both M_init,φ and N_φ are reported by the UE.

In one example, M_init,φ is fixed and N_φ is configured to the UE (via RRC or/and MAC CE or/and DCI).

In one example, M_init,φ is fixed and N_φ is reported by the UE.

In one example, M_init,φ is configured to the UE (via RRC or/and MAC CE or/and DCI) and N_φ is fixed.

In one example, M_init,φ is configured to the UE (via RRC or/and MAC CE or/and DCI) and N_φ is reported by the UE.

In one example, M_init,φ is reported by the UE and N_φ is fixed.

In one example, M_init,φ is reported by the UE and N_φ is configured to the UE (via RRC or/and MAC CE or/and DCI).

For Z>1 TRPs (CSI-RS resources), M_init,φ can be fixed to (or configured with or reported) as the same/common value for all TRPs, or M_init,φ can be fixed to (or configured with or reported) same or different values across TRPs. Likewise, for Z>1 TRPs (CSI-RS resources), N, can be fixed to (or configured with or reported) the same/common value for all TRPs, or N can be fixed to (or configured with or reported) same or different values across TRPs.

In one example, any example for the window set for φ_rdescribed in embodiment as disclosed in the present disclosure can be applied for the index set of φ_r(φ_rand/or q₃) in example as disclosed in the present disclosure.

In one example, the window set for φ_ris based on the window set (or the whole range set) for W_f(i.e., FD basis vector selection).

In one example, M_init=M_init,φ and N=N, for O₃=1.

In one example, O₃M_init=M_init,φ and O₃N=N, for O₃>1.

In one example, M_init=M_init,φ and N=N, for O₃>1.

In one example, N_φ can be according to at least one of the following examples.

In one example, N_φ is fixed to 4.

In one example, N_φ is fixed to 5.

In one example, N_φ is fixed to 6.

In one example, N_φ is fixed to 7.

In one example, N_φ is fixed to 8.

In one example, N_φ can be given by min(N_φ, N₃).

In one example, N_φ can be given by min(N_φ, N₃O₃) for O₃>1 (e.g., O₃=4).

In one example, N_φ, t_upper, e.g., t_upper=5, 6, 7, 8. In one example, t_upper=cN₃, where c<1.

In one example, Nq, O₃t_upper, e.g., t_upper=5, 6, 7, 8 for O₃>1 (e.g., O₃=4). In one example, t_upper=cN₃, where c<1.

In one example, N_φ<t_upper, e.g., t_upper=5, 6, 7, 8, 9. In one example, t_upper=cN₃, where c<1.

In one example, N_φ<O₃t_upper, e.g., t_upper=5, 6, 7, 8, 9 for O₃>1 (e.g., O₃=4).

In one example, t_upper=cN₃, where c<1.

In one example, N_φ≥t_lower, e.g., t_lower=1, 2, 3, 4.

In one example, N_φ≥O₃t_lower, e.g., t_lower=1, 2, 3, 4.

In one example, N_φ>t_lower, e.g., t_lower=1, 2, 3, 4.

In one example, N_φ>O₃t_lower, e.g., t_lower=1, 2, 3, 4.

In one example, t_lower<N, <t_upper, e.g., t_upper=5, 6, 7, 8, e.g., t_lower=1, 2, 3, 4. In one example, t_upper=cN₃, where c<1.

In one example, t_lower<Nq, <t_upper, e.g., t_upper=5, 6, 7, 8, e.g., t_lower=1, 2, 3, 4. In one example, t_upper=cN₃, where c<1.

In one example, t_lower<N, <t_upper, e.g., t_upper=5, 6, 7, 8, e.g., t_lower=1, 2, 3, 4. In one example, t_upper=cN₃, where c<1.

In one example, t_lower<Nq, <O₃t_upper, e.g., t_upper=5, 6, 7, 8, e.g., t_lower=1, 2, 3, 4 for O₃>1 (e.g., O₃=4). In one example, t_upper=cN₃, where c<1.

In one example, t_lower<N, <O₃t_upper, e.g., t_upper=5, 6, 7, 8, e.g., t_lower=1, 2, 3, 4 for O₃>1 (e.g., O₃=4). In one example, t_upper=cN₃, where c<1.

In one example, M_init,φ can be according to at least one of the following examples.

In one example,

$M_{init, φ} = - \frac{N_{φ}}{2} + 1.$

In one example,

$M_{init, φ} = - ⌈ \frac{N_{φ}}{2} ⌉ + 1.$

In one example,

$M_{init, φ} = - ⌊ \frac{N_{φ}}{2} ⌋ + 1.$

In one example,

$M_{init, φ} = - \frac{N_{φ} O_{3}}{2} + 1.$

In one example,

$M_{init, φ} = - ⌈ \frac{N_{φ} O_{3}}{2} ⌉ + 1.$

In one example,

$M_{init, φ} = - ⌊ \frac{N_{φ} O_{3}}{2} ⌋ + 1.$

In one example,

$M_{init, φ} = - \frac{N_{φ}}{2} .$

In one example,

$M_{init, φ} = - ⌈ \frac{N_{φ}}{2} ⌉ .$

In one example,

$M_{init, φ} = - ⌊ \frac{N_{φ}}{2} ⌋ .$

In one example,

$M_{init, φ} = - \frac{N_{φ} O_{3}}{2} .$

In one example,

$M_{init, φ} = - ⌈ \frac{N_{φ} O_{3}}{2} ⌉ .$

In one example,

$M_{init, φ} = - ⌊ \frac{N_{φ} O_{3}}{2} ⌋ .$

In one example, M_init,φ=−N_φ+1.

In one example, M_init,φ=−N_φO₃+1.

In one example, M_init,φ=−N_φ.

In one example, M_init,φ=−N_φO₃.

In one example, M_init,φ=−2N_φ+1.

In one example, M_init,φ=−2N_φO₃+1.

In one example, M_init,φ=c₁, where c₁is a fixed value, e.g., c₁=0.

In one example,

$M_{init, φ} \in {- \frac{N_{φ}}{2} + 1, - \frac{N_{φ}}{2} + 2, \dots, \frac{N_{φ}}{2}} .$

(In another example, similar variants using

$- ⌈ \frac{N_{φ}}{2} ⌉ + 1 or - ⌊ \frac{N_{φ}}{2} ⌋ + 1) .$

In one example,

$M_{init, φ} \in {- \frac{N_{φ}}{2} + 1, - \frac{N_{φ}}{2} + 2, \dots, 0} .$

(In another example, similar variants using

$- ⌈ \frac{N_{φ}}{2} ⌉ + 1 or - ⌊ \frac{N_{φ}}{2} ⌋ + 1) .$

In one example,

$M_{init, φ} \in {- \frac{N_{φ} O_{3}}{2} + 1, - \frac{N_{φ} O_{3}}{2} + 2, \dots, \frac{N_{φ} O_{3}}{2}} .$

(In another example, similar variants using

$- ⌈ \frac{N_{φ} O_{3}}{2} ⌉ + 1 or - ⌊ \frac{N_{φ} O_{3}}{2} ⌋ + 1) .$

In one example,

$M_{init, φ} \in {- \frac{N_{φ} O_{3}}{2} + 1, - \frac{N_{φ} O_{3}}{2} + 2, \dots, 0} .$

(In another example, similar variants using

$- ⌈ \frac{N_{φ} O_{3}}{2} ⌉ + 1 or - ⌊ \frac{N_{φ} O_{3}}{2} ⌋ + 1) .$

In one example, M_init,φ∈{−N_φ+1, −N_φ+2, ⋅ ⋅ ⋅ , N_φ}.

In one example, M_init,φ∈{−N_φ+1, −N_φ+2, ⋅ ⋅ ⋅ , 0}.

In one example, M_init,φ∈{−N_φO₃+1, −N_φO₃+2, ⋅ ⋅ ⋅ , 0}.

In one example, M_init,φ∈{−N_φO₃+1, −N_φO₃+2⋅ ⋅ ⋅ , N_φO₃}.

In one example, M_init,φ∈{−N_φ+1, −N_φ+2, ⋅ ⋅ ⋅ , 2N_φ}.

In one example, M_init,φ∈{−N_φ+1, −N_φ+2, ⋅ ⋅ ⋅ , 0}.

In one example, M_init,φ∈{−N_φO₃+1, −N_φO₃+2, ⋅ ⋅ ⋅ , 0}.

In one example, M_init,φ∈{−N_φO₃+1, −−N_φO₃+2, ⋅ ⋅ ⋅ , 0}.

FIG. 17 illustrates an example method 1700 performed by a UE in a wireless communication system according to embodiments of the present disclosure. The method 1700 of FIG. 17 can be performed by any of the UEs 111-116 of FIG. 1, such as the UE 116 of FIG. 3, and a corresponding method can be performed by any of the BSs 101-103 of FIG. 1, such as BS 102 of FIG. 2. The method 1700 is for illustration only and other embodiments can be used without departing from the scope of the present disclosure.

The method 1700 begins with the UE receiving a configuration about a CSI report (1710). For example, in 1710, the configuration includes information about (i) N_TRPCSI-RS resources, where N_TRP>1, (ii) a parameter codebookType set to type-II-CJT-r18 or type-II-PortSelection-CJT-r18, and (iii) a parameter codebookMode set to model.

The UE then determines information for the CSI report based on N CSI-RS resources (1720). For example, in 1720, the information for the CSI report is determined based on the configuration and N≤N_TRP. The UE then partitions the CSI report CSI Part 1 and CSI part 2 (1730).

The UE then partitions the CSI Part 2 G0, G1, and G2 (1740). For example, in 1740, the group G1 includes an indicator indicating, for each of N−1 CSI-RS resources of the N CSI-RS resources, a frequency-domain (FD) offset d_r∈{0, 1, . . . , N₃O₃−1} relative to a reference CSI-RS resource. Here, r∈{1, . . . , N_TRP}, r≠r*, and r* is an index of the reference CSI-RS resource such that d_r*=0; N₃is a length of each of FD basis vectors; and O₃is an oversampling value.

In various embodiments, the FD offset d_ris common for all of v layers and a value of O₃is configured by a RRC parameter. Here, O₃∈{1, 4} and a payload of the indicator is (N−1)┌log₂(N₃O₃)┐ bits.

In various embodiments, the index r* of the reference CSI-RS resource is fixed to be a smallest index among indices of the N CSI-RS resources.

In various embodiments, the UE determines a value of N from among N∈{1,2, . . . , N_TRP} and the group G1 includes the indicator when the value of N≥2. For example if N<2 G1 may not include the indicator.

In various embodiments, when codebookMode=type-II-CJT-r18, the UE determines an indicator i_1,6,lindicating M_vFD basis vectors for each layer l=1, . . . , v, where the indicator i_1,6,lis included in the group G1. Here, elements of the M_vFD basis vectors shifted by the FD offset d_rare given by

$y_{t, l, r}^{(f)} = e^{j \frac{2 π {tn}_{3, l}^{(f)}}{N_{3}}} e^{j \frac{2 π {td}_{r}}{N_{3} O_{3}}}$

for t=0, 1, . . . , N₃−1, f=0, 1, . . . , M_v−1, and l=1, ⋅ ⋅ ⋅ , v, where n₃∈{0, 1, . . . , N₃−1} is identified based on i_1,6,l.

In various embodiments, when codebookMode=type-II-PortSelection-CJT-r18, the UE determines an indicator i_1,6indicating M FD basis vectors common for all layers l=1, . . . , v, where the indicator i_1,6is included in the group G0. Here, elements of the M FD basis vectors shifted by the FD offset d_rare given by

$y_{t, r}^{(f)} = e^{j \frac{2 π {tn}_{3}^{(f)}}{N_{3}}} e^{j \frac{2 π {td}_{r}}{N_{3} O_{3}}}$

for t=0, 1, . . . , N₃−1, and f=0, 1, . . . , M−1, where

$n_{3}^{(f)} \in {\begin{matrix} {0} & M = 1 \\ {0, 1, \dots, \min (N_{M}, N_{3}) - 1} & M = 2 \end{matrix}$

is identified by i_1,6and N_Mis a value in {2,4}.

The UE then transmits the CSI Part 1 and at least a portion of the CSI Part 2 (1750). In various embodiments, the portion of the CSI Part 2 is G0, (G0, G1), or (G0, G1, G2).

In various embodiments, the UE may also transmit UE capability information indicating that the UE is capable of supporting codebookMode=model.

Any of the above variation embodiments can be utilized independently or in combination with at least one other variation embodiment.

The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure and various changes could be made to the methods illustrated in the flowcharts herein. For example, while shown as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps.

Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read as implying that any particular element, step, or function is an essential element that must be included in the claims scope. The scope of patented subject matter is defined by the claims.

Number	Date	Country
63440294	Jan 2023	US
63444844	Feb 2023	US
63456346	Mar 2023	US
63456754	Apr 2023	US
63458029	Apr 2023	US
63472161	Jun 2023	US

CSI REPORTING FOR MULTI-TRP COHERENT JOINT-TRANSMISSION

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CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

Provisional Applications (6)