Patent Application
20250031085
The present disclosure relates generally to wireless communication systems and, more specifically, to channel state information (CSI) reporting.
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.
This disclosure relates to apparatuses and methods for CSI reporting.
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) K>1 non-zero power (NZP) CSI-reference signal (RS) resources and (ii) a codebookType. The codebookType indicates a codebook associated with PCSIRS CSI-RS ports aggregated across the K NZP CSI-RS resources. The UE further includes processor operably coupled to the transceiver. The processor, based on the configuration, is configured to determine, a number of layers (v); and when v>1, determine a vector br for each pair of consecutive layers (2r−1,2r) and determine one of: (A) a coefficient cr for each pair of consecutive layers (2r−1,2r) and (B) a coefficient c for each layer l=1, . . . , v. The transceiver is configured to transmit the CSI report including at least one vector indicator indicating vectors {br} and at least one coefficient indicator indicating coefficients. PCSIRS>32, r=1, . . . , ┌v/2┐, and each vector has a length dependent on PCSIRS.
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) K>1 NZP CSI-RS resources and (ii) a codebookType. The codebookType indicates a codebook associated with PCSIRS CSI-RS ports aggregated across the K NZP CSI-RS resources. The transceiver is further configured to receive the CSI report including at least one vector indicator indicating vectors {br} and at least one coefficient indicator indicating coefficients. When a number of layers (v)>1, a vector br is determined for each pair of consecutive layers (2r−1,2r) and one of: (A) a coefficient cr is determined for each pair of consecutive layers (2r−1,2r) and (B) a coefficient cl is determined for each layer l=1, . . . , v. PCSIRS>32, r=1, . . . , ┌v/2┐, and each vector has a length dependent on PCSIRS.
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) K>1 NZP CSI-RS resources and (ii) a codebookType. The codebookType indicates a codebook associated with PCSIRS CSI-RS ports aggregated across the K NZP CSI-RS resources. The method further includes, based on the configuration, determining, a number of layers (v) and when v>1, determining a vector br for each pair of consecutive layers (2r−1,2r) and determining one of: (A) a coefficient cr for each pair of consecutive layers (2r−1,2r) and (B) a coefficient c for each layer l=1, . . . , v. The method further includes transmitting the CSI report including at least one vector indicator indicating vectors {br} and at least one coefficient indicator indicating coefficients. PCSIRS>32, r=1, . . . , 2%, and each vector has a length dependent on PCSIRS.
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.
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:
The following documents and standards descriptions are hereby incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TS 36.211 v17.3.0, “E-UTRA, Physical channels and modulation (herein “REF 1”);” 3GPP TS 36.212 v17.1.0, “E-UTRA, Multiplexing and Channel coding” (herein “REF 2”); 3GPP TS 36.213 v17.3.0, “E-UTRA, Physical Layer Procedures” (herein “REF 3”); 3GPP TS 36.321 v17.3.0, “E-UTRA, Medium Access Control (MAC) protocol specification” (herein “REF 4”); 3GPP TS 36.331 v17.3.0, “E-UTRA, Radio Resource Control (RRC) Protocol Specification” (herein “REF 5”); 3GPP TR 22.891 v1.2.0 (herein “REF 6”); 3GPP TS 38.212 v17.3.0, “E-UTRA, NR, Multiplexing and Channel coding” (herein “REF 7”); 3GPP TS 38.214 v17.3.0, “E-UTRA, NR, Physical layer procedures for data” (herein “REF 8”); 3GPP TS 38.211 v17.3.0, “E-UTRA, NR, Physical channels and modulation” (herein “REF 9”).
Wireless communication has been one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services exceeded five billion and continues to grow quickly. The demand of wireless data traffic is rapidly increasing due to the growing popularity among consumers and businesses of smart phones and other mobile data devices, such as tablets, “note pad” computers, net books, eBook readers, and machine type of devices. In order to meet the high growth in mobile data traffic and support new applications and deployments, improvements in radio interface efficiency and coverage is of paramount importance.
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 multiple-input multiple-output (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.
In the 5G/NR system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
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.
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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 3rd generation 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. In certain embodiments, one or more of the BSs 101-103 include circuitry, programing, or a combination thereof for facilitating CSI reporting.
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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. As another example, the controller/processor 225 could support methods for facilitating CSI reporting. 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 for facilitating CSI reporting. 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.
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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. 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, which includes for example, a touchscreen, keypad, etc., and the display 355. 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).
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The transmit path 400 as illustrated in
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A transmitted RF signal from the BS 102 arrives at the UE 116 after passing through the wireless channel, and reverse operations to those at the BS 102 are performed at the UE 116.
As illustrated in
Each of the BSs 101-103 may implement a transmit path 400 as illustrated in
Each of the components in
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.
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A communication system includes a downlink (DL) that conveys signals from transmission points such as base stations (BSs) or NodeBs to user equipments (UEs) and an Uplink (UL) that conveys signals from UEs to reception points such as NodeBs. A UE, also commonly referred to as a terminal or a mobile station, may be fixed or mobile and may be a cellular phone, a personal computer device, or an automated device. An eNodeB, which is generally a fixed station, may also be referred to as an access point or other equivalent terminology. For LTE systems, a NodeB is often referred as an eNodeB.
In a communication system, such as LTE, DL signals can include data signals conveying information content, control signals conveying DL control information (DCI), and reference signals (RS) that are also known as pilot signals. An eNodeB transmits data information through a physical DL shared channel (PDSCH). An eNodeB transmits DCI through a physical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH)—see also REF 3. An eNodeB transmits acknowledgement information in response to data transport block (TB) transmission from a UE in a physical hybrid ARQ indicator channel (PHICH). An eNodeB transmits one or more of multiple types of RS including a UE-common RS (CRS), a channel state information RS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DL system bandwidth (BW) and can be used by UEs to obtain a channel estimate to demodulate data or control information or to perform measurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RS with a smaller density in the time and/or frequency domain than a CRS. DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCH and a UE can use the DMRS to demodulate data or control information in a PDSCH or an EPDCCH, respectively. A transmission time interval for DL channels is referred to as a subframe and can have, for example, duration of 1 millisecond.
DL signals also include transmission of a logical channel that carries system control information. A BCCH is mapped to either a transport channel referred to as a broadcast channel (BCH) when the DL signals convey a master information block (MIB) or to a DL shared channel (DL-SCH) when the DL signals convey a System Information Block (SIB). Most system information is included in different SIBs that are transmitted using DL-SCH. A presence of system information on a DL-SCH in a subframe can be indicated by a transmission of a corresponding PDCCH conveying a codeword with a cyclic redundancy check (CRC) scrambled with system information RNTI (SI-RNTI). Alternatively, scheduling information for a SIB transmission can be provided in an earlier SIB and scheduling information for the first SIB (SIB-1) can be provided by the MIB.
DL resource allocation is performed in a unit of subframe and a group of physical resource blocks (PRBs). A transmission BW includes frequency resource units referred to as resource blocks (RBs). Each RB includes NscRB sub-carriers, or Resource Elements (REs), such as 12 REs. A unit of one RB over one subframe (or slot) is referred to as a PRB. A UE can be allocated MPDSCH RBs for a total of MPDSCH=MscPDSCH·NscRB REs for the PDSCH transmission BW.
UL signals can include data signals conveying data information, control signals conveying UL control information (UCI), and UL RS. UL RS includes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW of a respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate data signals or UCI signals. A UE transmits SRS to provide an eNodeB with an UL CSI. A UE transmits data information or UCI through a respective physical UL shared channel (PUSCH) or a Physical UL control channel (PUCCH). If a UE needs to transmit data information and UCI in a same UL subframe, the UE may multiplex both in a PUSCH. UCI includes Hybrid Automatic Repeat request acknowledgement (HARQ-ACK) information, indicating correct (ACK) or incorrect (NACK) detection for a data TB in a PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR) indicating whether a UE has data in the UE's buffer, rank indicator (RI), and channel state information (CSI) enabling an eNodeB to perform link adaptation for PDSCH transmissions to a UE. HARQ-ACK information is also transmitted by a UE in response to a detection of a PDCCH/EPDCCH indicating a release of semi-persistently scheduled PDSCH (see also REF 3).
An UL subframe (or slot) includes two slots. Each slot includes NsymbUL symbols for transmitting data information, UCI, DMRS, or SRS. A frequency resource unit of an UL system BW is an RB. A UE is allocated NRB RBs for a total of NRB·NscRB REs for a transmission BW. For a PUCCH, NRB=1. A last subframe (or slot) symbol can be used to multiplex SRS transmissions from one or more UEs. A number of subframe (or slot) symbols that are available for data/UCI/DMRS transmission is Nsymb=2·(NsymbUL−1)−NSRS, where NSRS=1 if a last subframe (or slot) symbol is used to transmit SRS and NSRS=0 otherwise.
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There are two types of frequency range (FR) defined in 3GPP 5G NR specifications. The sub-6 GHz range is called frequency range 1 (FR1) and millimeter wave range is called frequency range 2 (FR2). An example of the frequency range for FR1 and FR2 is shown below.
For MIMO in FR1, up to 32 CSI-RS antenna ports is supported, and in FR2, up to 8 CSI-RS antenna ports is supported. In next generation cellular standards (e.g., 6G), in addition to FR1 and FR2, new carrier frequency bands can be considered, e.g., FR4 (>52.6 GHz), terahertz (>100 GHz) and upper mid-band (10-15 GHz). The number of CSI-RS ports that can be supported for these new bands is likely to be different from FR1 and FR2. In particular, for 10-15 GHz band, the max number of CSI-RS antenna ports is likely to be more than FR1, due to smaller antenna form factors, and feasibility of fully digital beamforming (as in FR1) at these frequencies. For instance, the number of CSI-RS antenna ports can grow up to 128. Besides, the NW deployment/topology at these frequencies is also expected to be denser/distributed, for example, antenna ports distributed at multiple (potentially non-co-located, hence geographically separated) TRPs within a cellular region can be the main scenario of interest, due to which the number of CSI-RS antenna ports for MIMO can be even larger (e.g., up to 256).
A (spatial or digital) precoding/beamforming can be used across these large number of antenna ports in order to achieve MIMO gains. Depending on the carrier frequency, and the feasibility of RF/HW-related components, the (spatial) precoding/beamforming can be fully digital or hybrid analog-digital. In fully digital beamforming, there can be one-to-one mapping between an antenna port and an antenna element, or a ‘static/fixed’ virtualization of multiple antenna elements to one antenna port can be used. Each antenna port can be digitally controlled. Hence, a spatial multiplexing across all antenna ports is possible.
In a hybrid analog-digital beamforming, analog beamforming corresponds to a ‘dynamic/varying’ virtualization of multiple antenna elements to obtain one antenna port (or antenna panel). 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
Embodiments of the present disclosure recognize that 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 time division duplexing (TDD) systems, the CSI can be acquired using the SRS transmission relying on the channel reciprocity. For frequency division duplexing (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 [REF7, REF8], 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 Wf, and (c) coefficients {tilde over (W)}2 that 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 W1 is replaced with SD CSI-RS port selection, i.e., L out of
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.
In Rel. 18 NR MIMO, the following CSI enhancements are further provided targeting two use cases (coherent joint transmission from multiple TRPs, and high/medium velocity UEs):
Although Rel-18 CJT CSI can support up to 128 antenna ports by configuring 4 CSI-RS resources each with 32 antenna ports, there is another interest arising to support up to 128 antenna ports using Type-I CSI, which requires smaller feedback overhead than Rel-18 CJT CSI. Currently, a single CSI-RS resource can support up to 32 antenna ports for Type-I single-panel (SP) and multi-panel (MP) CSI. By using multiple CSI-RS resources for Type-I CSI, it is allowed to configure up to 64 antenna ports according to one of the following two schemes:
However, both of the schemes do not offer CSI feedback associated with the entire channel of 64 antenna ports, but are designed for specific use cases, 1) NCJT from two TRP, and 2) one CSI-RS resource selection and reporting associated with the selected CSI-RS resource, respectively. Hence, Type-I CSI with more than 32 antenna ports is limited in terms of use cases, and needs some enhancement.
In next generation MIMO systems, the number of antenna ports is expected to increase further (e.g., up to 256), for example, for carrier frequencies in upper mid-band (10-15 GHz); the NW deployments are likely to be denser/more distributed (when compared with 5G NR); and the system is expected to work seamlessly even in challenging scenarios such as medium-high (e.g., 120 kmph) speed UEs, ‘higher-order) multi-user MIMO.
Various embodiments of the present disclosure recognize that similar to legacy (Rel.15/18 NR) both low-resolution (aka Type I) and high-resolution (aka Type II) CSI reporting for the above-mentioned distributed systems are needed and beneficial depending on use cases and scenarios. Unlike legacy, however, it is preferable to have a common framework or components between the two CSI reporting settings, in order to have a simple, future-proof, and scalable solution, thereby making it more feasible in real deployments.
Various embodiments of the present disclosure propose a framework for such CSI reporting that is based on Rel.16 enhanced Type II and Rel.18 Type II CJT codebooks. In particular, based on the proposed framework, several examples are provided to facilitate the low-resolution (aka Type I) CJT CSI reporting across multiple antenna port groups or NZP CSI-RS resources.
The present disclosure relates to a CSI reporting framework in next generation MIMO systems. In particular, it relates to the CSI reporting based on a low-resolution (or Type I) codebook comprising spatial, frequency, and time (Doppler) domain components for a mTRP CJT with distributed antenna structure (DMIMO).
Various embodiments of the present disclosure propose the following: W1: based on Rel.16 eType II and Rel.18 Type II CJT codebooks; W2: based on Rel. 15 Type I (selection and co-phasing); independent vs joint encoding of layers; and relative amp/power across CSI-RS resources, FD/DD compression.
Aspects, features, and advantages of the present disclosure are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the disclosure. The present disclosure is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.
In the following, for brevity, both FDD and TDD are provided as the duplex method for both DL and UL signaling.
Although exemplary descriptions and embodiments to follow assume orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA), this disclosure can be extended to other OFDM-based transmission waveforms or multiple access schemes such as filtered OFDM (F-OFDM).
This present disclosure covers several components which can be used in conjunction or in combination with one another, or can operate as standalone schemes.
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” (CRAB), 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.
“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” 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 require 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, 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 Mn subbands when one CSI parameter for all the Mn subbands within the CSI reporting band. A CSI parameter is configured with “subband” for the CSI reporting band with Mn subbands when one CSI parameter is reported for each of the M, subbands within the CSI reporting band.
As illustrated in
comprise a first antenna polarization, and antenna ports
. . . , X+PCSIRS−1 comprise a second antenna polarization, where PCSIRS is 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, . . . ). Dual-polarized antenna payouts are assumed in this disclosure. The embodiments (and examples) in this disclosure however are general and are applicable to single-polarized antenna layouts as well.
Let Ng be a number of antenna groups (AGs). When there are multiple antenna groups (Ng>1), we assume that each group (g∈{1, . . . , Ng}) comprises dual-polarized antenna ports with N1,g and N2,g ports in two dimensions. This is illustrated in
In one example, an antenna group corresponds to an antenna panel. In one example, an antenna group corresponds to a TRP. In one example, an antenna group corresponds to an RRH. In one example, an antenna group corresponds to CSI-RS antenna ports of a NZP CSI-RS resource. In one example, an antenna group corresponds to a subset of CSI-RS antenna ports of a NZP CSI-RS resource (comprising multiple antenna groups). In one example, an antenna group corresponds to CSI-RS antenna ports of multiple NZP CSI-RS resources (e.g., comprising a CSI-RS resource set).
In one example, an antenna group corresponds to a reconfigurable intelligent surface (RIS) in which the antenna group can be (re-) configured more dynamically (e.g., via MAC CE and/or DCI). For example, the number of antenna ports associated with the antenna group can be changed dynamically.
In one example scenario, multiple AGs can be co-located or distributed, and can serve static (non-mobile) or moving UEs. An illustration of AGs serving a moving UE is shown in
In one example, the antenna architecture of the MIMO system is structured. For example, the antenna structure at each AG is dual-polarized (single or multi-panel as shown in
In another example, the antenna architecture of the MIMO system is unstructured. For example, the antenna structure at one AG can be different from another AG.
We assume a structured antenna architecture in the rest of the disclosure. For simplicity, we assume each AG is equivalent to a panel (cf.
In one embodiment, an AG constitutes (or corresponds to or is equivalent to) at least one of the following:
In one example, when an AG maps (or corresponds to) a CSI-RS resource or resource group, and a UE can select a subset of AGs (resources or resource groups) and report the CSI for the selected AGs (resources or resource groups), the selected AGs 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 an AG maps (or corresponds to) a CSI-RS port group, and a UE can select a subset of AGs (port groups) and report the CSI for the selected AGs (port groups), the selected AGs 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 Ng AGs, a decoupled (modular) codebook is used/configured, and when a single (K=1) CSI-RS resource for Ng AGs, a joint codebook is used/configured.
In one embodiment, as shown in
The UE receives the CSI-RS burst, estimates the B instances of the DL channel measurements, and uses the channel estimates to obtain the Doppler component(s) of the DL channel. The CSI-RS burst can be linked to (or associated with) a single CSI reporting setting (e.g., via higher layer parameter CSI-ReportConfig), wherein the corresponding CSI report includes an information about the Doppler component(s) of the DL channel.
Let ht be the DL channel estimate based on the CSI-RS resource(s) received in time slot t∈{0, 1, . . . , B−1}. When the DL channel estimate in slot t is a matrix Gt of size NRx×NTx×NSc, then ht=vec(Gt), where NRx, NTx, and NSc are number of receive (Rx) antennae at the UE, number of CSI-RS ports measured by the UE, and number of subcarriers in frequency band of the CSI-RS burst, respectively. The notation vec (X) is used to denote the vectorization operation wherein the matrix X is transformed into a vector by concatenating the elements of the matrix in an order, for example, 1→2→3→ and so on, implying that the concatenation starts from the first dimension, then moves second dimension, and continues until the last dimension. Let HB=[h0 h1 . . . hB-1] be a concatenated DL channel. The Doppler component(s) of the DL channel can be obtained based on H B. For example, HB can be represented as CΦH=ΣS=0N-1csΦsH where Φ=[ϕ0 ϕ1 . . . ϕN-1] is a Doppler domain (DD) basis matrix whose columns comprise basis vectors, C=[c0 c1 . . . cN-1] is a coefficient matrix whose columns comprise coefficient vectors, and N<B is the number of DD basis vectors. Since the columns of HB are likely to be correlated, a DD compression can be achieved when the value of N is small (compared to the value of B). In this example, the Doppler component(s) of the channel is represented by the DD basis matrix Φ and the coefficient matrix C.
When there are multiple TRPs/RRHs (NTRP>1), the UE can be configured to measure the CSI-RS burst(s) according to at least one of the following examples.
In one example, the UE is configured to measure NTRP CSI-RS bursts, one from each TRP/RRH. The NTRP CSI-RS bursts can be overlapping in time (i.e., measured in same time slots). Or, they can be staggered in time (i.e., measured in different time slots). Whether overlapping or staggered can be determined based on configuration. It can also depend on the total number of CSI-RS ports across RRHs/TRPs. When the total number of ports is small (e.g., <=32), they can overlap, otherwise (>32), they are staggered. The number of time instances B can be the same for all of the NTRP bursts. Or the number B can be the same or different across bursts (or TRPs/RRHs).
In one example, the UE is configured to measure K≥NTRP CSI-RS bursts, where K=>NTRP K, and Kr is a number of CSI-RS bursts associated with RRH/TRP r, where r∈{1, . . . , NTRP}. Each CSI-RS burst is according to at least one of the examples in example A.1.1. When Kr>1, multiple CSI-RS bursts are linked to (or associated with) a CSI reporting setting, i.e., the UE receives the Nr CSI-RS bursts, estimates the DL channels, and obtains the Doppler component(s) of the channel using all of the Nr CSI-RS bursts.
In one example, the UE is configured to measure one CSI-RS burst across all of NTRP TRPs/RRHs. Let P be a number of CSI-RS ports associated with the NZP CSI-RS resource measured via the CSI-RS burst. The CSI-RS burst is according to at least one of the examples in described herein. The total of P ports can be divided into NTRP groups/subsets of ports and one NTRP P, and group/subset of ports is associated with (or corresponds to) a TRP/RRH. Then, P=Σr=1N
is configured to measure one half of the port groups, and the second half of the time instances (e.g., B/2, . . . B−1) is configured to measure the remaining half of the port groups.
In one example, the UE is configured to measure multiple CSI-RS bursts, where each burst is according to at least one of the examples described herein. Multiple CSI-RS bursts are linked to (or associated with) a CSI reporting setting, i.e., the UE receives multiple CSI-RS bursts, estimates the DL channels, and obtains the Doppler component(s) of the channel using all of multiple CSI-RS bursts.
Let N4 be the length of the DD basis vectors {ϕs}, e.g., each basis vector is a length N4×1 column vector.
In one embodiment, a UE is configured to determine a value of N4 based on the value B (number of CSI-RS instances) in a CSI-RS burst and components across which the DD compression is performed, where each component corresponds to one or multiple time instances within the CSI-RS burst. In one example, N4 is fixed (e.g., N4=B) or configured (e.g., via RRC or MAC CE or DCI) or reported by the UE (as part of the CSI report). In one example, the B CSI-RS instances can be partitioned into sub-time (ST) units (instances), where each ST unit is defined as (up to) NST contiguous time instances in the CSI-RS burst. In this example, a component for the DD compression corresponds to a ST unit. Three examples of the ST units are shown in
The value of NST can be fixed (e.g., NST=1 or 2 or 4) or indicated to the UE (e.g., via higher layer RRC or MAC CE or DCI based signaling) or reported by the UE (e.g., as part of the CSI report). The value of NST (fixed or indicated or reported) can be subject to a UE capability reporting. The value of NST can also be dependent on the value of B (e.g., one value for a range of values for B and another value for another range of values for B).
When there are multiple TRPs/RRHs (NTRP>1), the UE can be configured to determine a value of N4 according to at least one of the following examples.
In one example, a value of N4 is the same for all TRPs/RRHs.
In one example, a value of N4 can be the same or different across TRPs/RRHs.
In one embodiment, a UE is configured with J≥1 CSI-RS bursts (as illustrated earlier in the disclosure) that occupy a frequency band and a time span (duration), wherein the frequency band comprises A RBs, and the time span comprises B time instances (of CSI-RS resource(s)). When J>1, the A RBs and/or B time instances can be aggregated across J CSI-RS bursts. In one example, the frequency band equals the CSI reporting band and the time span equals the number of CSI-RS resource instances (across) CSI-RS bursts), both can be configured to the UE for a CSI reporting, which can be based on the DD compression.
The UE is further configured to partition (divide) the A RBs into subbands (SBs) and/or the B time instances into sub-times (STs). The partition of A RBs can be based on a SB size value NSB, which can be configured to the UE (cf. Table 5.2.1.4-2 of REF8). The partition of B time instances can be based either a ST size value NST or an r value, as described in this disclosure. An example is illustrated in
When there are multiple TRPs/RRHs (NTRP>1), the UE can be configured to determine subbands (SBs) and/or sub-times (STs) according to at least one of the following examples.
For illustration, both subbands (SBs) and/or sub-times (STs) being the same for all TRPs/RRHs is assumed in the rest of this disclosure.
The CSI reporting is based on channel measurements (based on CSI-RS bursts) in three-dimensions (3D): the first dimension corresponds to SD comprising PCSIRS CSI-RS antenna ports (in total across all of NTRP RRHs/TRPs), the second dimension corresponds to FD comprising N3 FD units (e.g., SB), and the third dimension corresponds to DD comprising N4 DD units (e.g., ST). The 3D channel measurements can be compressed using basis vectors (or matrices) similar to the Rel. 16 enhanced Type II codebook. Let W1, Wf, and Wd respectively denote basis matrices whose columns comprise basis vectors for SD, FD, and DD.
In one embodiment, the DD compression (or DD component or Wd basis) can be turned OFF/ON from the codebook. When turned OFF, Wd can be fixed (hence not reported), e.g., Wd=1 (scalar 1) or Wd=[1, . . . , 1] (all-one vector) or
(all-one vector) or
(identity matrix), where n is a scaling factor (e.g., n=N4) or
where d* is an index of a fixed DD basis vector hd*. In one example, d*=0. In one example, when the DD basis vectors comprise an orthogonal DFT basis set, hat is a DD basis vector which corresponds to the DC component. When turned ON, Wd (DD basis vectors) is reported.
In one embodiment, a UE is configured (e.g., via a higher layer CSI configuration information) with a CSI report, where the CSI report is based on a channel measurement (and interference measurement) and a codebook. When the CSI report is configured to be aperiodic, it is reported when triggered via a DCI field (e.g., a CSI request field) in a DCI.
The channel measurement can be based on K≥1 channel measurement resources (CMRs) that are transmitted from a plurality of spatial-domain (SD) units (e.g., a SD unit=a CSI-RS antenna port), and are measured via a plurality of frequency-domain (FD) units (e.g., a FD unit=one or more PRBs/SBs) and via either a time-domain (TD) unit or a plurality of TD units (e.g., a TD unit=one or more time slots). In one example, a CMR can be a NZP-CSI-RS resource.
The CSI report can be associated with the plurality of FD units and the plurality of TD units associated with the channel measurement. Alternatively, the CSI report can be associated with a second set of FD units (different from the plurality of FD units associated with the channel measurement) and/or a second set of TD units (different from the plurality of TD units associated with the channel measurement). In this later case, the UE, based on the channel measurement, can perform prediction (interpolation or extrapolation) in the second set of FD units and/or the second set of TD units associated with the CSI report.
An illustration of the SD units (in 1st and 2nd antenna dimensions), FD units, and, and TD units is shown in
The plurality of SD units can be associated with antenna ports (e.g., co-located at one site or distributed across multiple sites) comprising one or multiple antenna groups (i.e., Ng≥1), and dimensionalizes the spatial-domain profile of the channel measurement.
When K=1, there is one CMR comprising PCSIRS CSI-RS antenna ports.
When K>1, there are multiple CMRs, and the CSI report is based on the channel measurement across the multiple CMRs. In one example, a CMR corresponds to an AG (one-to-one mapping). In one example, multiple CMRs can correspond to an AG (many-to-one mapping). In one example, when all of the PCSIRS antenna ports are co-located at one site, Ng=1. In one example, when all of the PCSIRS antenna ports are distributed (non-co-located) across multiple sites, Ng>1.
In one example, when all of the PCSIRS antenna ports are co-located at one site and within a single antenna panel, Ng=1. In one example, when all of the PCSIRS antenna ports are distributed across multiple antenna panels (can be co-located or non-co-located), Ng>1.
The value of Ng can be configured, e.g., via higher layer RRC parameter. Or it can be indicated via a MAC CE. Or it can be provided via a DCI field.
Likewise, the value of K can be configured, e.g., via higher layer RRC parameter. Or it can be indicated via a MAC CE. Or it can be provided via a DCI field.
In one example, K=Ng=X. The value of X can be configured, e.g., via higher layer RRC parameter. Or it can be indicated via a MAC CE. Or it can be provided via a DCI field.
In one example, the value of K is determined based on the value of Ng. In one example, the value of Ng is determined based on the value of K.
The plurality of FD units can be associated with a frequency domain allocation of resources (e.g., one or multiple CSI reporting bands, each comprising multiple PRBs) and dimensionalizes the frequency (or delay)-domain profile of the channel measurement.
The plurality of TD units can be associated with a time domain allocation of resources (e.g., one or multiple CSI reporting windows, each comprising multiple time slots) and dimensionalizes the time (or Doppler)-domain profile of the channel measurement.
The CSI report includes an information about a precoding matrix (e.g., the information is an indicator such as PMI). The information about the precoding matrix comprises/includes at least two components (W1 and W2). The first component (W1) includes a basis which corresponds to a set of basis entities. The second component (W2) includes
The first component W1 is codebook-based. When the basis needs reporting (or configured to be reported), the codebook configured for the CSI report includes at least one component for reporting the basis W1. This component is similar to legacy (e.g., Type I and II codebooks in 5G NR) codebooks. However, since W1 is decoupled from W2, the framework allows more options and parameterization for the W1 basis as future upgrades when newer antenna types become available. The basis can be dictated by (or associated with) at least one of the spatial-domain profile, frequency (or delay)-domain profile, or time (Doppler)-domain profile of the channel measurement. Even though the number of CSI-RS antenna ports can be large (e.g., 256), the antenna ports are expected to have some antenna structure (e.g., similar to 2D active antenna array), hence the SD channel profile can be represented using SD basis entities, where the SD basis entities have dimension depending on the number of SD units (PCSIRS or PCSIRS/2 or 2N1N2 or N1N2). Likewise, the FD channel profile is likely to be correlated across FD units, and the DD/TD channel profile is also expected to have some correlation across DD/TD units (e.g., for low-medium speed UEs). Hence, FD and DD/TD channel profiles can be represented using FD and DD/TD basis entities, respectively, where their dimensions depend on the number of FD units (N3) and the number of DD/TD units (N4), respectively.
The second component (W2) is also codebook-based and is derived based on the channel measurement and W1. For instance, the channel measurement can be projected on to the basis W1 and projected channel can be used to derive the W2 components (coefficients), e.g., based on Type I or Type II codebooks in 5G NR.
In one example, the number of antenna ports across K CSI-RS resources is the same. For example, each of the K CSI-RS resources can be associated with 2N1N2 antenna ports. In this case, the total number of antenna ports is PCSIRS,tot=2N1N2.
In one example, the number of antenna ports across K CSI-RS resources can be the same or different. For example, each of the K CSI-RS resources can be associated with 2N1,rN2,r antenna ports. In this case, the total number of antenna ports is PCSIRS,tot=Σr=1K2N1,rN2,r.
In port numbering scheme 1, the CSI-RS ports are numbered according to the order of (polarization p, NZP CSI-RS resource r) as CSI-RS ports of (p=0,r=1) followed by CSI-RS ports of (p=1,r=1), followed by CSI-RS ports of (p=0,r=2), followed by CSI-RS ports of (p=1,r=2), . . . , followed by CSI-RS ports of (p=0,r=N) followed by CSI-RS ports of (p=1,r=N).
In port numbering scheme 2, the CSI-RS ports are numbered according to the order of (polarization p, NZP CSI-RS resource r) as
In one embodiment, a UE is configured with a CSI report associated with (or across) N≥1 NZP CSI-RS resources (or N≥1 subsets of CSI-RS antenna ports or antenna port groups within a NZP CSI-RS resource), the CSI report is determined based on a codebook comprising components corresponding to W1 and W2. In particular, the precoder for layer l is given by
SD basis or port selection matrix (similar to Rel. 16/18 Type II or Type II CJT codebook or Rel. 17/18 Type II port selection (PS) or CJT PS codebook)
In one example, N≤K and K is a number of NZP CSI-RS resources (e.g., in a CSI resource set) configured for channel measurements. In one example, K is fixed (e.g., 2 or 3 or 4) or configured (e.g., via higher layer from {2,3,4} or {1,2,3,4}), or reported by the UE (e.g., as part of UE capability). In one example, the value of N can be ≥1. In one example, the value of N can be ≥2. In one example, the value of N is configured (e.g., via higher layer). In one example, the value of N is reported by the UE (e.g., as part of the CSI report). In one example, the UE is configured with N=K (i.e., no selection of NZP CSI-RS resources) or N≤K (i.e., dynamic selection of NZP CSI-RS resources by the UE). When the UE performs dynamic selection, the selected N NZP CSI-RS resources can be reported via part 1 of the two part CSI (or UCI). The reporting can be via a bitmap indicator of size K bits.
As shown in
In one example, for port numbering scheme 1, W1 is a block diagonal matrix
comprising 2N blocks, (2(r−1)+1,2r)-th blocks, W1,2(r-1)+1 and W1,2r, are associated with two antenna polarizations (two halves or groups of CSI-RS antenna ports) of the NZP CSI-RS resource r, and W2 is a block matrix
is a Lr-element column (selection) vector containing a value of 1 in element jr or (jr mod Lr) and zeros elsewhere, and cr is a coefficient. Note that when Lr=1,
hence ej
In one example, for port numbering scheme 2, W1 is a block diagonal matrix
comprising 2N blocks, where (r,r+N)-th blocks, W1,r and W1,r+N, are associated with two antenna polarizations (two halves or groups of CSI-RS antenna ports) of the NZP CSI-RS resource r, and W2 is a block matrix
is a Lr-element column (selection) vector containing a value of 1 in element jr or (jr mod Lr) and zeros elsewhere, and cr is a coefficient. Note that when Lr=1,
hence ej
For each CSI-RS resource r=1, . . . , N,
is a PCSIRS,r×2Lr SD basis matrix, where the Lr SD basis vectors comprising columns of Br are determined the same way as in Rel. 15/16 Type II codebooks (cf. 5.2.2.2.3, REF 8), i.e., the SD basis vectors vm
where the values of C (x,y) are given in Table 5.2.2.2.3-1 [REF8].
In one example,
i
1,1
=[q
1
q
2]
q
1
=[q
1,1
. . . q
1,N]
q
2
=[q
2,1
. . . q
2,N]
The quantities m1(r,i),m2(r,i) are given by
and correspond to the DFT beam (vector) indices in the oversampled DFT codebook.
The L, DFT beams or DFT vectors are selected or identified by the components i1,1 and i1,2 of the codebook index i1, where (q1, q2) indicates the orthogonal basis set comprising of N1N2 DFT beams, an example of which is shown in
For the Lr out N1N2 beam selection, the N1N2 beams in the orthogonal basis set, indicated by (q1, q2), are sorted or numbered according to at least one of the following schemes:
The sorted beam indices n(i)∈{0, 1, . . . , N1N2−1}. An illustration of the two beam sorting (numbering) schemes are shown in
For a given antenna port layout (N1, N2) and oversampling factors (O1,O2) for two dimensions, a DFT vector vim can be expressed as follows.
where l∈{0, 1, . . . , O1N1−1} and m∈{0, 1, . . . , O2N2−1}. Here, (O1, O2) can be fixed, e.g., (1,1), (2,2), (2,1), (2,2), (4,1), or (4,4), or configured. (O1, O2) can be different across resources. (O1, O2) can depend on (N1, N2). For example, OiNi=v or ≤v where v can be fixed, e.g., 64, 128 or configured.
Let PCSIRS,r=2N1,rN2,r be number of CSI-RS ports associated with CSI-RS resource r. Let K=M1M2 be a total number of resources or port groups, where Mi is a number of resources in i-th dimension, and i=1,2. In one example, the UE is configured with one of the following:
In one example, the UE is configured with one of the above parameters from a set of supported combinations of values, which can be all of or a subset of the combinations shown in Table 1.
indicates data missing or illegible when filed
In one example, the UE is configured with one of the above parameters from a set of supported combinations of values, which can be all of or a subset of the combinations shown in Table 2.
In one example,
where ϕr∈{0, 1, . . . , NPSK−1}, and NPSK=4 (for QPSK), 8 (for 8PSK), or 16 (for 16PSK). In one example, NPSK is fixed, e.g., NPSK=4. In one example, NPSK is configured via higher layer, e.g., from {4,8}.
The selection vector ej
i
2
=[i
2,1
, i
2,2]
i
2,1
=[i
2,1,1
. . . i
2,1,N]
i
2,2
=[i
2,2,1
. . . i
2,2,N]
i
2,1,r
=j
r
i
2,2,r=ϕr
In one example,
where pr is an amplitude or power level. The selection vector ej
i
2
=[i
2,1
, i
2,2
, i
2,3]
The selection vector indicator i2,1=[i2,1,1 . . . i2,1,N] where i2,1,r=jr.
The phase coefficient indicators i2,2=[i2,2,1 . . . i2,2,N] where i2,2,r=ϕr.
The amplitude coefficient indicators i2,3=[i2,3,1 . . . i2,3,N] where i2,3,r=pr.
In one example, the mapping from kr to the amplitude coefficient pr is given one of the examples in Table 3.
In one example, the amplitude/power for one (denoted as r*) of the N CSI-RS resources can be fixed (e.g., pr*=1), hence corresponding kr* is not reported. The index r* can be fixed (e.g., r*=1) or configured (e.g., via higher layer) or reported by the UE (e.g., as part of the CSI parameter or a UCI parameter). When rank>1, the r* can be layer-common, i.e., the same for all layers, or it can be layer-specific, i.e., for each layer l, an index ri* can be fixed or configured, or reported. Or, When rank>1, the r* can be layer-pair-common, i.e., the same for consecutive layer pairs (l, l+1), where l=1, 3, . . . , i.e., a first r1* common/same for layer pairs (1,2), a second r2* common/same for layer pairs (3,4), and so on.
For the port numbering scheme 1, the rank-1 (1-layer) precoder is then given by
For the port numbering scheme 2, the rank-1 (1-layer) precoder is then given by
In a variation of a previous example, for r=1, . . . , N,
is equal to
where dr is an inter-CSIRS-resource coefficient associated with CSI-RS resource r.
In another variation of a previous example, for r=1, . . . , N,
is equal to
where cr,0 and cr,1 are coefficients associated with two antenna polarizations (0 and 1) of the CSI-RS resource r.
In another variation of a previous example, for r=1, . . . , N,
is equal to
where jr,0 and jr,1 are selected basis vectors associated with two antenna polarizations (0 and 1) of the CSI-RS resource r.
In another variation of a previous example, for r=1, . . . , N,
is equal to
In another variation of a previous example, for r=1, . . . , N,
is equal to
In one example,
for r=1, . . . , N and p=0,1, where ϕr,p∈{0, 1, . . . , NPSK−1}, and NPSK=4 (for QPSK), 8 (for 8PSK), or 16 (for 16PSK). In one example, NPSK is fixed, e.g., NPSK=4. In one example, NPSK is configured via higher layer, e.g., from {4,8}.
In one example,
for r=1, . . . , N and p=0,1, where pr,p is an amplitude or power level. In one example, the mapping from kr,p to the amplitude coefficient Pr,p is according to one of the examples in Table 3.
In one example, the inter-CSIRS-resource coefficient of the 1st CSI-RS resource is fixed, e.g., d1=1, or configured, or reported by the UE. The inter-CSIRS-resource coefficients of the remaining CSI-RS resources can be reported either independently or relative (differentially) w.r.t. to d1.
In one example, the coefficient of the 1st polarization of the 1st CSI-RS resource is fixed, e.g., c1,0=1, or configured, or reported by the UE. The coefficients of the remaining polarizations and CSI-RS resources can be reported either independently or relative (differentially) w.r.t. to c1,0.
In general, the selection vector ej
i
2
=[i
2,1
,i
2,2
,i
2,3]
i
2,1
=[i
2,1,1
. . . i
2,1,N]
i
2,2
=[i
2,2,1
. . . i
2,2,N]
i
2,3
=[i
2,3,1
. . . i
2,3,N]
i
2,1,r=[ϕr,0 ϕr,1]
i
2,2,r
=[k
r,0
k
r,1]
i
2,3,r
=[k
r,0
k
r,1]
Or,
i
2,1
=[i
2,1,1
. . . i
2,1,2N]
i
2,2
=[i
2,2,1
. . . i
2,2,2N]
i
2,3
=[i
2,3,1
. . . i
2,3,2N]
[i2,1,2(r−1)+1 i2,1,2r]=[jr,0 jr,1]
[i2,2,2(r−1)+1+i2,2,2r]=[ϕr,0 ϕr,1]
[i2,3,2(r−1)+1 i2,3,2r]=[kr,0 kr,1]
Or,
i
2,1
=[i
2,1,1
. . . i
2,1,N]
i
2,2
=[i
2,2,1
. . . i
2,2,N]
i
2,3
=[i
2,3,1
. . . i
2,3,N]
i
2,1,r
=[i
2,1,r,0
i
2,1,r,1]
i
2,2,r
=[i
2,2,r,0
i
2,2,r,1]
i
2,3,r
=[i
2,3,r,0
i
2,3,r,1]
i
2,1,r,p
=j
r,p
i
2,2,r,p=ϕr,p
i
2,3,r,p
=k
r,p
In general, for the port numbering scheme 1, the rank-1 (1-layer) precoder is then given by
Where depending on the above-mentioned variations, either
For the port numbering scheme 2, the rank-1 (1-layer) precoder is then given by
In one example, the W1 has the following structure, i.e., SD basis vectors can be different for two polarizations of a NZP CSI-RS resource.
where W1,r,p=[br,p,0, br,p,1, . . . , br,p,L
In one example, L, SD basis vectors are the same for all p but can be different for r=1, . . . , N.
In another example, L, SD basis vectors are the same for all r but can be different for p=0,1,
In another example, L, SD basis vectors are the same for all r and p,
In one example, Lr=L for all r. In one example, Lr is fixed (e.g., 1 or 4). In one example, Lr is configured (e.g., from {1,2,4}, {2,4,6}, {2,4}, {1,4}, or {1,2,4,6}). In one example, {Lr} is configured via higher layer from a list of supported combinations of {Lr}. An example of the list is shown in Table 4. In one example, the UE is configured with NL≥1 combinations of {Lr} values, and when NL>1, the UE reports selects one of the NL combinations and report the selected combination as part of the CSI report (e.g., via a CSI/UCI parameter in part 1 of a two-part CSI/UCI).
In one example, Lr depends on the rank value (v). For example, Lr=v or v/2 or └v/2┘ or ┌v/2┐ or v/s or └v/s┘ or ┌v/s┐, where s>1.
In one embodiment for rank value (v)>1, at least one of the following example is used/configured. Let W1(v) and W2(v) denote that W1 and W2 components for v layers.
In one example, all components of W1 and W2, as described above, are determined/reported independently for each layer l=1, . . . , v.
In one example, Lr=1 for each r and for each rank v≥1.
In one example, Lr∈{1,x} for rank 1 and Lr=1 for each r and for each rank v>1.
In one example, Lr∈{1,x} for rank 1,2 and Lr=1 for each r and for each rank v>2.
In one example, the rotation factor (q1, q2) or {(q1,r, q2,r)} are determined/reported common for all layers, and {Lr} SD basis vectors and all components of W2, as described above, are determined/reported independently for each layer l=1, . . . , v, and W2 is determined/reported for each layer l=1, . . . , v.
In one example, all components of W1, as described above, are determined/reported common for all layers, and all components of W2, as described above, are determined/reported independently for each layer l=1, . . . , v, and W2 is determined/reported for each layer l=1, . . . , v.
In one example, all components of W1, as described above, are determined/reported independently for each layer l=1, . . . , v, and one joint W2 across u layers are determined/reported, where the columns of W2 correspond to W2 for u layers.
In one example, the rotation factor (q1, q2) or {(q1,r, q2,r)} are determined/reported common for all layers, {Lr} SD basis vectors, as described above, are determined/reported independently for each layer l=1, . . . , v, and one joint W2 across v layers are determined/reported, where the columns of W2 correspond to W2 for v layers.
In one example, all components of W1, as described above, are determined/reported common for all layers, and one joint W2 across v layers are determined/reported, where the columns of W2 correspond to W2 for v layers.
In one embodiment, when the number of layers (rank) v=2, the rank-2 (2-layer) precoding matrix is given by
At least one of the following examples is used/configured regarding Ur(2), i.e., the portion of the precoding matrix associated with the r-th resource.
In one example,
where by br=vm
In one example,
where br=vm
In one example,
where by brl=vm
In one example,
where brl and crl are as described above. Hence, the indicator (i1,1, i1,2) indicates two sets of {brl}, one for each layer, and i2 indicates two sets of {crl}, one for each layer.
In one example, when the indicator (i1,1, i1,2) indicates two sets of {brl}, then
In one example, when the indicator i2 indicates two sets of {crl}, then
In general, for the port numbering scheme 1, the rank-2 (2-layer) precoding matrix is given by
Likewise, for the port numbering scheme 2, the rank-2 (2-layer) precoding matrix is given by
In one example, when the DFT vector and/or the corresponding co-phase can be different (hence independently reported) for each antenna polarization and for each resource, for the port numbering scheme 1, the rank-2 (2-layer) precoding matrix is given by
where
l is a DFT vector, and cr,pl, l=1,2 is a co-phase for layer l and antenna group (polarization) p, respectively.
Likewise, for the port numbering scheme 2, the rank-2 (2-layer) precoding matrix is given by
In one example,
where ϕr,pl∈{0, 1, . . . , NPSK−1}, and NPSK=4 (for QPSK), 8 (for 8PSK), or 16 (for 16PSK). In one example, NPSK is fixed, e.g., NPSK=4. In one example, NPSK is configured via higher layer, e.g., from {4,8}.
In one example,
where pr,pl is an amplitude or power level. The details of the amplitude and power level are as described above.
Let us denote
In one embodiment, when the number of layers (rank) v=3,4, the precoding matrix is given by one of the following examples.
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
The rank 3,4 precoding matrix includes components: (i) up to four sets of {brl} and (ii) up to four sets of {crl}.
In one embodiment, when the number of layers (rank) v=5,6, the precoding matrix is given by one of the following examples.
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
The corresponding rank 5,6 precoding matrix includes components: (i) up to six sets of {brl} and (ii) up to six sets of {crl}.
In one embodiment, when the number of layers (rank) v=5-8, the rank 5-6 precoding matrix is as described above, and the rank 7-8 precoding matrix is given by one of the following examples.
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
In one example, for the port numbering scheme 1, the precoding matrix is given by
In one example, for the port numbering scheme 2, the precoding matrix is given by
The corresponding rank 5-8 precoding matrix includes components: (i) up to eight sets of {brl} and (ii) up to eight sets of {crl}.
In one embodiment, a variation of previous embodiments, wherein the SD basis selection matrix is replaced with a SD port selection matrix.
In one example, vm
In one example, vm
For CSI-RS resource r, K1,r=2Lr ports are selected from PCSIRS,r ports based on Lr vectors, vm
which are indicated by the index i1,2=[i1,2,1 . . . i1,2,N], where
The method 2000 begins with the UE receiving a configuration about a CSI report (2010). For example, in 2010, the configuration includes information about K>1 NZP CSI-RS resources and a codebookType and the codebookType indicates a codebook associated with PCSIRS CSI-RS ports aggregated across the K NZP CSI-RS resources.
The UE then determines a number of layers (v) (2020). For example, in 2020, the number of layers may be determined based on the configuration. The UE then determines a vector br for each pair of consecutive layers (2r−1,2r) (2030). For example, in 2030, the determination is made when v>1. The UE then determines (A) a coefficient cr for each pair of consecutive layers (2r−1,2r) or (B) a coefficient cr for each layer l=1, . . . , v (2040). For example, in 2040, the configuration includes information indicating the one of (A) and (B) and the UE determines the one of (A) and (B) based on the information.
The UE then transmits the CSI report including at least one vector indicator indicating vectors {br} and at least one coefficient indicator indicating coefficients (2050). For example, in 2050, PCSIRS>32, r=1, . . . , ┌v/2┐, and each vector has a length dependent on PCSIRS.
In various embodiments, K∈{2,3,4}, PCSIRS∈S, a set of values including {64,96,128}, the vectors {br} are orthogonal DFT vectors, PCSIRS=ΣrPCSIRS,r, PCSIRS,r=2N1,rN2,r, and (N1,r, N2,r) is a number of ports in a first and second dimensions of a two-dimensional port layout, and each coefficient c includes at least a phase value from {1, j, −1, −j}. In various embodiments, the K NZP CSI-RS resources have an equal number of CSI-RS ports, (N1,r, N2,r)=(N1,N2), and at least one first vector indicator includes a 4-bit indicator indicating a value of (q1, q2) associated with N1N2 orthogonal DFT vectors, where qi∈{0,1,2,3}, and for each layer, a
indicator indicating one vector associated with a layer.
Any of the above variation embodiments can be utilized independently or in combination with at least one other variation embodiment. The above flowchart(s) 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 figures illustrate different examples of user equipment, various changes may be made to the figures. For example, the user equipment can include any number of each component in any suitable arrangement. In general, the figures do not limit the scope of this disclosure to any particular configuration(s). Moreover, while figures illustrate operational environments in which various user equipment features disclosed in this patent document can be used, these features can be used in any other suitable system.
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.
This application claims priority under 35 U.S.C. § 119 (e) to U.S. Provisional Patent Application No. 63/526,899 filed on Jul. 14, 2023, which provisional patent application is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63526899 | Jul 2023 | US |
