RADIO UNIT REMOTE INTERFERENCE MANAGEMENT REFERENCE SIGNAL TRANSMISSION

Abstract

Certain aspects of the present disclosure provide techniques for interference management reference signal (RS) transmission. An example method, performed at a first network entity, generally includes applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence, and outputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.

Description

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for interference management reference signal (RS) transmission.

Description of Related Art

Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, or other similar types of services. These wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available wireless communications system resources with those users.

Although wireless communications systems have made great technological advancements over many years, challenges still exist. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and wireless receivers. Accordingly, there is a continuous desire to improve the technical performance of wireless communications systems, including, for example: improving speed and data carrying capacity of communications, improving efficiency of the use of shared communications mediums, reducing power used by transmitters and receivers while performing communications, improving reliability of wireless communications, avoiding redundant transmissions and/or receptions and related processing, improving the coverage area of wireless communications, increasing the number and types of devices that can access wireless communications systems, increasing the ability for different types of devices to intercommunicate, increasing the number and type of wireless communications mediums available for use, and the like. Consequently, there exists a need for further improvements in wireless communications systems to overcome the aforementioned technical challenges and others.

SUMMARY

One aspect provides a method for wireless communications at a first network entity. The method includes applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; and outputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.

Another aspect provides a method for wireless communications at a second network entity. The method includes obtaining, from a first network entity, frequency domain samples of a first copy of a first reference signal (RS) sequence and frequency domain samples of a second copy of the first RS sequence; applying a frequency domain function to the first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; performing an inverse Fourier transform (IFT) on the modified copy of the first RS sequence to obtain a circularly time-shifted RS signal in the time domain that forms a first part of an interference management RS, and performing the IFT on the second copy of the first RS sequence to obtain a second part of the interference management RS; and outputting the first and second parts of the interference management RS for transmission.

Other aspects provide: an apparatus operable, configured, or otherwise adapted to perform any one or more of the aforementioned methods and/or those described elsewhere herein; a non-transitory, computer-readable media comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform the aforementioned methods as well as those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising code for performing the aforementioned methods as well as those described elsewhere herein; and/or an apparatus comprising means for performing the aforementioned methods as well as those described elsewhere herein. By way of example, an apparatus may comprise a processing system, a device with a processing system, or processing systems cooperating over one or more networks. Means for applying, means for outputting, means for obtaining, and means for performing may comprise one or more processors, such as one or more of the processors described above with reference to FIG. 3 or 13.

The following description and the appended figures set forth certain features for purposes of illustration.

BRIEF DESCRIPTION OF DRAWINGS

The appended figures depict certain features of the various aspects described herein and are not to be considered limiting of the scope of this disclosure.

FIG. 1 depicts an example wireless communications network.

FIG. 2 depicts an example disaggregated base station architecture.

FIG. 3 depicts aspects of an example base station and an example user equipment.

FIGS. 4A, 4B, 4C, and 4D depict various example aspects of data structures for a wireless communications network.

FIG. 5 depicts an example description of lower layer uplink link split between O-RAN Distributed Unit (O-DU) and O-RAN Radio Unit (O-RU).

FIG. 6 depicts an example remote interference management reference signal (RIM-RS) structure.

FIG. 7 is an example call flow diagram, in accordance with aspects of the present disclosure.

FIG. 8 depicts an example RIM-RS structure, in accordance with aspects of the present disclosure.

FIGS. 9A, 9B, and 9C depict generation of an example RIM-RS structure, in accordance with aspects of the present disclosure.

FIGS. 10A and 10B depict example RIM-RS structures with different CP lengths, in accordance with aspects of the present disclosure.

FIG. 11 depicts a method for wireless communications.

FIG. 12 depicts a method for wireless communications.

FIG. 13 depicts aspects of an example communications device.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for interference management reference signal (RS) transmission.

In wireless networks, transmissions from one network entity may interfere with communications involving another network entity. For example, transmissions from a remote base station (BS) or component thereof may interfere with communication involving another base station. In some cases, techniques referred to as Remote Interference Management (RIM) may be used to mitigate the impact of such interference. RIM may involve transmission and measurement of references signals (RS) referred to as RIM-RS.

RIM-RS may be part of 3GPP 5GR NR reference signals that are transmitted and received by a network entity (e.g., a gNB) and used for interference mitigation between gNBs. The RIM-RS structure typically includes a single cyclic prefix (CP) followed by two repetitions of the same sequence or symbol (as depicted in FIG. 6). This time domain signal structure is different from many of the common downlink (DL) signals, such as physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), synchronization signal block (SSB), and channel state information (CSI) RS structures, that have a shorter CP at the start of every symbol.

Deployment of communication systems, such as 5G new radio (NR) systems, may be arranged in multiple manners with various components or constituent parts. In such systems, a network entity, such as a base station (BS), or one or more units (or one or more components) performing base station functionality, may be implemented in a disaggregated architecture. For example, a disaggregated base station may be configured to utilize a protocol stack that is physically or logically distributed among two or more units (such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs)). In some cases, disaggregated base stations may be utilized in an open radio access network (O-RAN (such as the network configuration sponsored by the O-RAN Alliance)).

Generation and transmission of RIM-RS may present certain challenges in systems deploying disaggregated base stations. For example, an O-RAN compliant RU (O-RU) may be expected to receive frequency domain samples for all the DL signals from an O-RAN compliant DU (O-DU). Typical RU DL functionality involves mapping the input frequency domain tones, executing an inverse fast Fourier transform (IFFT), and inserting the CP. Unfortunately, the unique time domain signal structure of the RIM-RS might require the RU to use a dedicated processing flow for this signal.

This flow might require the RU to dedicate additional processor resources only for the transmission of this RIM-RS signal. These additional processor resources might include hardware (HW) resources and may result in increased code complexity, increased processing execution latency, and excessive memory usage. This may result from the typical RU transmit (TX) processing of the RIM-RS signal, which may include separation of the RIM-RS signal to a dedicated flow, performing an FFT separately from other DL signals, and inserting an RIM-RS specific (e.g., non-legacy) CP insertion for the first symbol (e.g., with no CP insertion for the second symbol) before combining, in the time domain, the DL signal with the RIM-RS signal.

Aspects of the present disclosure, however, propose techniques that may allow RIM-RS transmission using more traditional downlink signal processing. In some cases, mathematical manipulation (e.g., applying a phase ramp) may be performed on RS sequences to allow an RIM-RS to be transmitted using normal downlink signal processing with normal CP insertion.

As a result, aspects of the present disclosure may help avoid the need for additional processor resources, increased code complexity, increased processing execution latency, and excessive memory usage.

Introduction to Wireless Communications Networks

The techniques and methods described herein may be used for various wireless communications networks. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may likewise be applicable to other communications systems and standards not explicitly mentioned herein.

FIG. 1 depicts an example of a wireless communications network 100, in which aspects described herein may be implemented.

Generally, wireless communications network 100 includes various network entities (alternatively, network elements or network nodes). A network entity is generally a communications device and/or a communications function performed by a communications device (e.g., a user equipment (UE), a base station (BS), a component of a BS, a server, etc.). For example, various functions of a network as well as various devices associated with and interacting with a network may be considered network entities. Further, wireless communications network 100 includes terrestrial aspects, such as ground-based network entities (e.g., BSs 102), and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipments.

In the depicted example, wireless communications network 100 includes BSs 102, UEs 104, and one or more core networks, such as an Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190, which interoperate to provide communications services over various communications links, including wired and wireless links.

FIG. 1 depicts various example UEs 104, which may more generally include: a cellular phone, smart phone, session initiation protocol (SIP) phone, laptop, personal digital assistant (PDA), satellite radio, global positioning system, multimedia device, video device, digital audio player, camera, game console, tablet, smart device, wearable device, vehicle, electric meter, gas pump, large or small kitchen appliance, healthcare device, implant, sensor/actuator, display, internet of things (IoT) devices, always on (AON) devices, edge processing devices, or other similar devices. UEs 104 may also be referred to more generally as a mobile device, a wireless device, a wireless communications device, a station, a mobile station, a subscriber station, a mobile subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a remote device, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, and others.

BSs 102 wirelessly communicate with (e.g., transmit signals to or receive signals from) UEs 104 via communications links 120. The communications links 120 between BSs 102 and UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a BS 102 and/or downlink (DL) (also referred to as forward link) transmissions from a BS 102 to a UE 104. The communications links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.

BSs 102 may generally include: a NodeB, enhanced NodeB (eNB), next generation enhanced NodeB (ng-eNB), next generation NodeB (gNB or gNodeB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, transmission reception point, and/or others. Each of BSs 102 may provide communications coverage for a respective geographic coverage area 110, which may sometimes be referred to as a cell, and which may overlap in some cases (e.g., small cell 102′ may have a coverage area 110′ that overlaps the coverage area 110 of a macro cell). A BS may, for example, provide communications coverage for a macro cell (covering relatively large geographic area), a pico cell (covering relatively smaller geographic area, such as a sports stadium), a femto cell (relatively smaller geographic area (e.g., a home)), and/or other types of cells.

While BSs 102 are depicted in various aspects as unitary communications devices, BSs 102 may be implemented in various configurations. For example, one or more components of a base station may be disaggregated, including a central unit (CU), one or more distributed units (DUs), one or more radio units (RUs), a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC), or a Non-Real Time (Non-RT) RIC, to name a few examples. In another example, various aspects of a base station may be virtualized. More generally, a base station (e.g., BS 102) may include components that are located at a single physical location or components located at various physical locations. In examples in which a base station includes components that are located at various physical locations, the various components may each perform functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. In some aspects, a base station including components that are located at various physical locations may be referred to as a disaggregated radio access network architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture. FIG. 2 depicts and describes an example disaggregated base station architecture.

Different BSs 102 within wireless communications network 100 may also be configured to support different radio access technologies, such as 3G, 4G, and/or 5G. For example, BSs 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through first backhaul links 132 (e.g., an S1 interface). BSs 102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) may interface with 5GC 190 through second backhaul links 184. BSs 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over third backhaul links 134 (e.g., X2 interface), which may be wired or wireless.

Wireless communications network 100 may subdivide the electromagnetic spectrum into various classes, bands, channels, or other features. In some aspects, the subdivision is provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. For example, 3GPP currently defines Frequency Range 1 (FR1) as including 410 MHZ-7125 MHz, which is often referred to (interchangeably) as “Sub-6 GHz”. Similarly, 3GPP currently defines Frequency Range 2 (FR2) as including 24,250 MHz-52,600 MHZ, which is sometimes referred to (interchangeably) as a “millimeter wave” (“mmW” or “mm Wave”). A base station configured to communicate using mmWave/near mmWave radio frequency bands (e.g., a mmWave base station such as BS 180) may utilize beamforming (e.g., 182) with a UE (e.g., 104) to improve path loss and range.

The communications links 120 between BSs 102 and, for example, UEs 104, may be through one or more carriers, which may have different bandwidths (e.g., 5, 10, 15, 20, 100, 400, and/or other MHz), and which may be aggregated in various aspects. Carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL).

Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g., 180 in FIG. 1) may utilize beamforming 182 with a UE 104 to improve path loss and range. For example, BS 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. In some cases, BS 180 may transmit a beamformed signal to UE 104 in one or more transmit directions 182′. UE 104 may receive the beamformed signal from the BS 180 in one or more receive directions 182″. UE 104 may also transmit a beamformed signal to the BS 180 in one or more transmit directions 182″. BS 180 may also receive the beamformed signal from UE 104 in one or more receive directions 182′. BS 180 and UE 104 may then perform beam training to determine the best receive and transmit directions for each of BS 180 and UE 104. Notably, the transmit and receive directions for BS 180 may or may not be the same. Similarly, the transmit and receive directions for UE 104 may or may not be the same.

Wireless communications network 100 further includes a Wi-Fi AP 150 in communication with Wi-Fi stations (STAs) 152 via communications links 154 in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum.

Certain UEs 104 may communicate with each other using device-to-device (D2D) communications link 158. D2D communications link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), and/or a physical sidelink feedback channel (PSFCH).

EPC 160 may include various functional components, including: a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and/or a Packet Data Network (PDN) Gateway 172, such as in the depicted example. MME 162 may be in communication with a Home Subscriber Server (HSS) 174. MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation as well as other functions. PDN Gateway 172 and the BM-SC 170 are connected to IP Services 176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packet Switched (PS) streaming service, and/or other IP services.

BM-SC 170 may provide functions for MBMS user service provisioning and delivery. BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and/or may be used to schedule MBMS transmissions. MBMS Gateway 168 may be used to distribute MBMS traffic to the BSs 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and/or may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

5GC 190 may include various functional components, including: an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. AMF 192 may be in communication with Unified Data Management (UDM) 196.

AMF 192 is a control node that processes signaling between UEs 104 and 5GC 190. AMF 192 provides, for example, quality of service (QOS) flow and session management.

Internet protocol (IP) packets are transferred through UPF 195, which is connected to the IP Services 197, and which provides UE IP address allocation as well as other functions for 5GC 190. IP Services 197 may include, for example, the Internet, an intranet, an IMS, a PS streaming service, and/or other IP services.

In various aspects, a network entity or network node can be implemented as an aggregated base station, as a disaggregated base station, a component of a base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, to name a few examples.

FIG. 2 depicts an example disaggregated base station 200 architecture. The disaggregated base station 200 architecture may include one or more central units (CUs) 210 that can communicate directly with a core network 220 via a backhaul link, or indirectly with the core network 220 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a Non-Real Time (Non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) Framework 205, or both). A CU 210 may communicate with one or more distributed units (DUs) 230 via respective midhaul links, such as an F1 interface. The DUs 230 may communicate with one or more radio units (RUS) 240 via respective fronthaul links. The RUs 240 may communicate with respective UEs 104 via one or more radio frequency (RF) access links. In some implementations, the UE 104 may be simultaneously served by multiple RUs 240.

Each of the units, e.g., the CUS 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communications interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally or alternatively, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver), configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (e.g., Central Unit-User Plane (CU-UP)), control plane functionality (e.g., Central Unit-Control Plane (CU-CP)), or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.

The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3^rd Generation Partnership Project (3GPP). In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.

Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (IFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like), or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU(s) 240 can be implemented to handle over the air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communications with the RU(s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU(s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-cNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a Non-RT RIC 215 configured to support functionality of the SMO Framework 205.

The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the Non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies).

FIG. 3 depicts aspects of an example BS 102 and a UE 104.

Generally, BS 102 includes various processors (e.g., 320, 330, 338, and 340), antennas 334a-t (collectively 334), transceivers 332a-t (collectively 332), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source 312) and wireless reception of data (e.g., data sink 339). For example, BS 102 may send and receive data between BS 102 and UE 104. BS 102 includes controller/processor 340, which may be configured to implement various functions described herein related to wireless communications.

Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380), antennas 352a-r (collectively 352), transceivers 354a-r (collectively 354), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., retrieved from data source 362) and wireless reception of data (e.g., provided to data sink 360). UE 104 includes controller/processor 380, which may be configured to implement various functions described herein related to wireless communications.

In regards to an example downlink transmission, BS 102 includes a transmit processor 320 that may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical HARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), and/or others. The data may be for the physical downlink shared channel (PDSCH), in some examples.

Transmit processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor 320 may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).

Transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t may process a respective output symbol stream to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers 332a-332t may be transmitted via the antennas 334a-334t, respectively.

In order to receive the downlink transmission, UE 104 includes antennas 352a-352r that may receive the downlink signals from the BS 102 and may provide received signals to the demodulators (DEMODs) in transceivers 354a-354r, respectively. Each demodulator in transceivers 354a-354r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples to obtain received symbols.

MIMO detector 356 may obtain received symbols from all the demodulators in transceivers 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to a data sink 360, and provide decoded control information to a controller/processor 380.

In regards to an example uplink transmission, UE 104 further includes a transmit processor 364 that may receive and process data (e.g., for the PUSCH) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH)) from the controller/processor 380. Transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the modulators in transceivers 354a-354r (e.g., for SC-FDM), and transmitted to BS 102.

At BS 102, the uplink signals from UE 104 may be received by antennas 334a-t, processed by the demodulators in transceivers 332a-332t, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by UE 104. Receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.

Memories 342 and 382 may store data and program codes for BS 102 and UE 104, respectively.

Scheduler 344 may schedule UEs for data transmission on the downlink and/or uplink.

In various aspects, BS 102 may be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 312, scheduler 344, memory 342, transmit processor 320, controller/processor 340, TX MIMO processor 330, transceivers 332a-t, antenna 334a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 334a-t, transceivers 332a-t, RX MIMO detector 336, controller/processor 340, receive processor 338, scheduler 344, memory 342, and/or other aspects described herein.

In various aspects, UE 104 may likewise be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 362, memory 382, transmit processor 364, controller/processor 380, TX MIMO processor 366, transceivers 354a-t, antenna 352a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 352a-t, transceivers 354a-t, RX MIMO detector 356, controller/processor 380, receive processor 358, memory 382, and/or other aspects described herein.

In some aspects, a processor may be configured to perform various operations, such as those associated with the methods described herein, and transmit (output) to or receive (obtain) data from another interface that is configured to transmit or receive, respectively, the data.

FIGS. 4A, 4B, 4C, and 4D depict aspects of data structures for a wireless communications network, such as wireless communications network 100 of FIG. 1.

In particular, FIG. 4A is a diagram 400 illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure, FIG. 4B is a diagram 430 illustrating an example of DL channels within a 5G subframe, FIG. 4C is a diagram 450 illustrating an example of a second subframe within a 5G frame structure, and FIG. 4D is a diagram 480 illustrating an example of UL channels within a 5G subframe.

Wireless communications systems may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. Such systems may also support half-duplex operation using time division duplexing (TDD). OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth (e.g., as depicted in FIGS. 4B and 4D) into multiple orthogonal subcarriers. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and/or in the time domain with SC-FDM.

A wireless communications frame structure may be frequency division duplex (FDD), in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either DL or UL. Wireless communications frame structures may also be time division duplex (TDD), in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.

In FIGS. 4A and 4C, the wireless communications frame structure is TDD where Dis DL, U is UL, and X is flexible for use between DL/UL. UEs may be configured with a slot format through a received slot format indicator (SFI) (dynamically through DL control information (DCI), or semi-statically/statically through radio resource control (RRC) signaling). In the depicted examples, a 10 ms frame is divided into 10 equally sized 1 ms subframes. Each subframe may include one or more time slots. In some examples, each slot may include 7 or 14 symbols, depending on the slot format. Subframes may also include mini-slots, which generally have fewer symbols than an entire slot. Other wireless communications technologies may have a different frame structure and/or different channels.

In certain aspects, the number of slots within a subframe is based on a slot configuration and a numerology. For example, for slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology u, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2^μ×15 kHz, where u is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGS. 4A, 4B, 4C, and 4D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

As depicted in FIGS. 4A, 4B, 4C, and 4D, a resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry reference (pilot) signals (RS) for a UE (e.g., UE 104 of FIGS. 1 and 3). The RS may include demodulation RS (DMRS) and/or channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and/or phase tracking RS (PT-RS).

FIG. 4B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including, for example, nine RE groups (REGs), each REG including, for example, four consecutive REs in an OFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., 104 of FIGS. 1 and 3) to determine subframe/symbol timing and a physical layer identity.

A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DMRS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and/or paging messages.

As illustrated in FIG. 4C, some of the REs carry DMRS (indicated as R for one particular configuration, but other DMRS configurations are possible) for channel estimation at the base station. The UE may transmit DMRS for the PUCCH and DMRS for the PUSCH. The PUSCH DMRS may be transmitted, for example, in the first one or two symbols of the PUSCH. The PUCCH DMRS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. UE 104 may transmit sounding reference signals (SRS). The SRS may be transmitted, for example, in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 4D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

As noted above, O-RAN specifies control plane, user plane and synchronization plane protocols used over the fronthaul interface linking the O-DU (O-RAN Distributed Unit) with the O-RU (O-RAN Radio Unit) with a Lower Layer Functional Split based architecture. FIG. 5 illustrates an example of an O-RAN architecture 500 implementing such a split for uplink transmissions, sent from an O-RU to an O-DU via a fronthaul (FH) interface.

Aspects Related to RU RIM-RS Transmission

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for interference management reference signal (RS) transmission.

As illustrated in FIG. 6, the structure for an RIM-RS 602 typically includes a single cyclic prefix (CP) followed by two repetitions of the same sequence or symbol (e.g., sym_M). As shown by comparison, this time domain signal structure is different from the structure of many of the common DL signals, such as a PDSCH 604, that have a shorter CP at the start of every symbol (e.g., sym_N and sym_N+1).

As noted above, generation and transmission of RIM-RS may present certain challenges in systems deploying disaggregated base stations. For example, an O-RU may be expected to receive (e.g., via the FH interface) frequency domain samples for all the DL signals from an O-DU. Typical RU DL functionality involves mapping the input frequency domain tones, performing an IFFT, and inserting the CP. Unfortunately, the unique time domain signal structure of the RIM-RS might require the RU to use a dedicated processing flow for this RIM-RS signal.

This flow might require the RU to dedicate additional processor resources only for the transmission of this RIM-RS signal. These additional processor resources might include hardware (HW) resources and may result in increased code complexity, increased processing execution latency, and excessive memory usage.

Aspects of the present disclosure, however, propose techniques that may allow RIM-RS transmission using more traditional downlink signal processing. In some cases, mathematical manipulation may be performed at a network entity on RS sequences to allow an RIM-RS to be transmitted using normal downlink signal processing with normal CP insertion.

For example, a phase ramp may be applied to a copy of the RS sequence before an IFFT is performed. The phase ramp may be designed such that performing the IFFT results in a circularly time-shifted RS signal in the time domain. In this context, a phase ramp generally refers to a mathematical operation, where the complex samples of the original signal are multiplied with additional complex coefficients, where the additional complex coefficients have a linearly increasing phase. According to certain aspects, a step size of the linear increase may be directly related to the desired circular shift in the time domain.

In some cases, the DU may transfer unmodified copies of the RS sequence and the RU may apply the phase ramp before performing the IFFT. In other cases, the DU may apply a phase ramp before transferring the corresponding frequency domain samples to the RU. One advantage of introducing the phase ramp at the DU side is that such an approach may allow full transparency at the RU. In other words, the RU may not even need to know it is transmitting RIM-RS. Rather, normal processing (e.g., IFFT and CP insertion) results in a compliant RIM-RS with the appropriate structure.

An example of a DU applying a phase ramp is depicted in the call flow diagram 700 of FIG. 7. The O-DU and O-RU depicted in FIG. 7 may be examples of a DU and RU shown and described above with reference to FIG. 2.

As shown at 702, the DU may apply a phase ramp to a first copy of an RS sequence before sending the (e.g., modified) first copy of the RS sequence to the RU. As shown at 704, the DU may send a second copy of the RS sequence to the RU without applying the phase ramp.

As shown at 706, utilizing the resulting structure of the RIM-RS, the techniques proposed herein will allow the RU processing of this signal to be the same as that used for other DL signals. For example, as will be described in greater detail below, the RS sequence and phase ramp may be designed such that the resulting signal, after performing the IFFT and CP insertion for the modified and unmodified copies of the RS sequence, results in an RIM-RS structure with a CP followed by two copies of the same RS sequence.

As illustrated in FIG. 8, in some cases, the RIM-RS structure 802 may have a CP size that is twice the size of a first CP, followed by two identical symbols (e.g., or sequences). The first CP may be a normal CP used in normal DL processing, as shown at 804. As will be described in greater detail below, in other cases, an RIM-RS structure may have different size CPs (e.g., greater than or less than twice the size of a normal CP).

FIGS. 9A-9C illustrate how applying the phase ramp to the first copy of the RS sequence (e.g., symbol 0), but not the second copy, results in an RIM-RS structure with a CP followed by identical RS sequences.

As illustrated in FIG. 9A, when the phase ramp is applied in the frequency domain before the IFFT, the IFFT output will result in a circularly time-shifted signal 904, rather than the conventional time domain signal 902 that results from the IFFT for the unmodified copy of the RS sequence. In other words, an end portion of the signal 902 is shifted to the start of the signal 904. Performing normal CP insertion to signal 904 results in a first part of the RIM-RS 906.

As illustrated in FIG. 9B, performing normal CP insertion to the signal 902 (obtained after performing the IFFT for the unmodified copy of the RS sequence) results in a second part of the RIM-RS 908.

FIG. 9C illustrates how a combination of the circularly time-shifted signal 906 and the signal 909 form an RIM-RS 910. As illustrated, the CP of the RIM-RS 910 is formed by the CP from the circularly time shifted signal 906 and the time-shifted portion (e.g., that would have been at the end of the original sequence 902). The identical sequences are labelled Sequence 0 and Sequence 1, with Sequence 0 formed by the portion of signal 906 after the after the RIM-RS CP, plus the CP of signal 908. Sequence 1 is identical, formed by the portion of signal 908 after the CP of signal 908.

As illustrated in the above example, the circular shift (achieved by the phase ramp) may be a normal CP size. This CP size may correspond to a second PDSCH symbol, and could be shorter or longer, depending on slot and symbol. For example, FIG. 10A illustrates an example 1000 where the circular shift (CP-1) added to the first symbol of the RIM-RS is shorter than a normal CP (CP-0). On the other hand, FIG. 10B illustrates an example 1050 where the circular shift (CP-1) added to the first symbol of the RIM-RS is longer than a normal CP (CP-0).

There are various potential benefits to the techniques provided herein. For example, as noted above, applying a phase ramp at the DU may allow the RU to be completely agnostic to RIM-RS transmission. This may help DUs achieve RIM-RS transmission, even with RUs that were not specifically designed to accommodate RIM-RS processing flows. Alternatively, if the phase ramp is applied at the RU, it still allows the IFFT flow to be agnostic to RIM-RS. The techniques proposed herein may allow for O-RU RIM-RS transmission without a dedicated RIM-RS DL flow and/or dedicated ORAN signaling. The techniques proposed herein may help avoid the addition of dedicated HW resources, and may help minimize processing complexity, latency, and (ORAN) signaling overhead. Thus, the techniques proposed herein may save processing resources, and may enable the RU to support RIM-RS transmission transparently.

Example Operations

FIG. 11 shows an example of a method 1100 of wireless communications at a first network entity, such as a BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

Method 1100 begins at step 1105 with applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence. In some cases, the operations of this step refer to, or may be performed by, circuitry for applying and/or code for applying as described with reference to FIG. 13.

Method 1100 then proceeds to step 1110 with outputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence. In some cases, the operations of this step refer to, or may be performed by, circuitry for outputting and/or code for outputting as described with reference to FIG. 13.

In some aspects, the frequency domain function is designed to achieve a circularly time-shifted RS signal in the time domain after an inverse Fourier transform (IFT) is performed on the modified first copy of the first RS sequence.

In some aspects, the first network entity comprises a distributed unit (DU); and the second network entity comprises a radio unit (RU).

In some aspects, the frequency domain function comprises a phase ramp.

In some aspects, the circularly time-shifted RS signal has a time circular shift length that is based on a length of cyclic prefix (CP) of an interference management RS.

In some aspects, the length of the CP of the interference management RS is a sum of a reference CP length and a length of another CP.

In some aspects, the reference CP length is equal to the length of the other CP.

In some aspects, the CP of the interference management RS comprises: a first CP portion corresponding to the other CP; and a second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

In some aspects, the interference management RS comprises: the CP of the interference management RS and two copies of the first RS sequence.

In one aspect, method 1100, or any aspect related to it, may be performed by an apparatus, such as communications device 1300 of FIG. 13, which includes various components operable, configured, or adapted to perform the method 1100. Communications device 1300 is described below in further detail.

Note that FIG. 11 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

FIG. 12 shows an example of a method 1200 of wireless communications at a second network entity, such as a BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

Method 1200 begins at step 1205 with obtaining, from a first network entity, frequency domain samples of a first copy of a first reference signal (RS) sequence and frequency domain samples of a second copy of the first RS sequence. In some cases, the operations of this step refer to, or may be performed by, circuitry for obtaining and/or code for obtaining as described with reference to FIG. 13.

Method 1200 then proceeds to step 1210 with applying a frequency domain function to the first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence. In some cases, the operations of this step refer to, or may be performed by, circuitry for applying and/or code for applying as described with reference to FIG. 13.

Method 1200 then proceeds to step 1215 with performing an inverse Fourier transform (IFT) on the modified copy of the first RS sequence to obtain a circularly time-shifted RS signal in the time domain that forms a first part of an interference management RS, and performing the IFT on the second copy of the first RS sequence to obtain a second part of the interference management RS. In some cases, the operations of this step refer to, or may be performed by, circuitry for performing and/or code for performing as described with reference to FIG. 13.

Method 1200 then proceeds to step 1220 with outputting the first and second parts of the interference management RS for transmission. In some cases, the operations of this step refer to, or may be performed by, circuitry for outputting and/or code for outputting as described with reference to FIG. 13.

In some aspects, the first network entity comprises a distributed unit (DU); and the second network entity comprises a radio unit (RU).

In some aspects, the function comprises a phase ramp.

In some aspects, the circularly time-shifted RS signal has a time circular shift length determined based on a length of cyclic prefix (CP) of the interference management RS.

In some aspects, the length of the CP of the interference management RS is a sum of a reference CP length and a length of a CP inserted at the second network entity.

In some aspects, the reference CP length is equal to the length of the CP inserted at the second network entity.

In some aspects, the CP of the interference management RS comprises: a first CP portion corresponding to the CP inserted at the second network entity; and a second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

In some aspects, the interference management RS comprises: the CP of the interference management RS, followed by two copies of the first RS sequence.

In one aspect, method 1200, or any aspect related to it, may be performed by an apparatus, such as communications device 1300 of FIG. 13, which includes various components operable, configured, or adapted to perform the method 1200. Communications device 1300 is described below in further detail.

Note that FIG. 12 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Communications Device(s)

FIG. 13 depicts aspects of an example communications device 1300. In some aspects, communications device 1300 is a network entity, such as BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

The communications device 1300 includes a processing system 1305 coupled to the transceiver 1365 (e.g., a transmitter and/or a receiver) and/or a network interface 1375. The transceiver 1365 is configured to transmit and receive signals for the communications device 1300 via the antenna 1370, such as the various signals as described herein. The network interface 1375 is configured to obtain and send signals for the communications device 1300 via communication link(s), such as a backhaul link, midhaul link, and/or fronthaul link as described herein, such as with respect to FIG. 2. The processing system 1305 may be configured to perform processing functions for the communications device 1300, including processing signals received and/or to be transmitted by the communications device 1300.

The processing system 1305 includes one or more processors 1310. In various aspects, one or more processors 1310 may be representative of one or more of receive processor 338, transmit processor 320, TX MIMO processor 330, and/or controller/processor 340, as described with respect to FIG. 3. The one or more processors 1310 are coupled to a computer-readable medium/memory 1335 via a bus 1360. In certain aspects, the computer-readable medium/memory 1335 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1310, cause the one or more processors 1310 to perform the method 1100 described with respect to FIG. 11, or any aspect related to it; and the method 1200 described with respect to FIG. 12, or any aspect related to it. Note that reference to a processor of communications device 1300 performing a function may include one or more processors 1310 of communications device 1300 performing that function.

In the depicted example, the computer-readable medium/memory 1335 stores code (e.g., executable instructions), such as code for applying 1340, code for outputting 1345, code for obtaining 1350, and code for performing 1355. Processing of the code for applying 1340, code for outputting 1345, code for obtaining 1350, and code for performing 1355 may cause the communications device 1300 to perform the method 1100 described with respect to FIG. 11, or any aspect related to it; and the method 1200 described with respect to FIG. 12, or any aspect related to it.

The one or more processors 1310 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1335, including circuitry such as circuitry for applying 1315, circuitry for outputting 1320, circuitry for obtaining 1325, and circuitry for performing 1330. Processing with circuitry for applying 1315, circuitry for outputting 1320, circuitry for obtaining 1325, and circuitry for performing 1330 may cause the communications device 1300 to perform the method 1100 described with respect to FIG. 11, or any aspect related to it; and the method 1200 described with respect to FIG. 12, or any aspect related to it.

Various components of the communications device 1300 may provide means for performing the method 1100 described with respect to FIG. 11, or any aspect related to it; and the method 1200 described with respect to FIG. 12, or any aspect related to it. Means for transmitting, sending or outputting for transmission may include transceivers 332 and/or antenna(s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1365 and the antenna 1370 of the communications device 1300 in FIG. 13. Means for receiving or obtaining may include transceivers 332 and/or antenna(s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1365 and the antenna 1370 of the communications device 1300 in FIG. 13.

EXAMPLE CLAUSES

Implementation examples are described in the following numbered clauses:

Clause 1: A method for wireless communications at a first network entity, comprising: applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; and outputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.

Clause 2: The method of Clause 1, wherein the frequency domain function is designed to achieve a circularly time-shifted RS signal in the time domain after an inverse Fourier transform (IFT) is performed on the modified first copy of the first RS sequence.

Clause 3: The method of any one of Clauses 1-2, wherein: the first network entity comprises a distributed unit (DU); and the second network entity comprises a radio unit (RU).

Clause 4: The method of any one of Clauses 1-3, wherein the frequency domain function comprises a phase ramp.

Clause 5: The method of any one of Clauses 1-4, wherein the circularly time-shifted RS signal has a time circular shift length that is based on a length of cyclic prefix (CP) of an interference management RS.

Clause 6: The method of Clause 5, wherein the length of the CP of the interference management RS is a based on (e.g., a sum of) a reference CP length and a length of another CP.

Clause 7: The method of Clause 6, wherein the reference CP length is equal to the length of the other CP.

Clause 8: The method of Clause 6, wherein the CP of the interference management RS comprises: a first CP portion corresponding to the other CP; and a second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

Clause 9: The method of Clause 8, wherein the interference management RS comprises: the CP of the interference management RS and two copies of the first RS sequence.

Clause 10: A method for wireless communications at a second network entity, comprising: obtaining, from a first network entity, frequency domain samples of a first copy of a first reference signal (RS) sequence and frequency domain samples of a second copy of the first RS sequence; applying a frequency domain function to the first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; performing an inverse Fourier transform (IFT) on the modified copy of the first RS sequence to obtain a circularly time-shifted RS signal in the time domain that forms a first part of an interference management RS, and performing the IFT on the second copy of the first RS sequence to obtain a second part of the interference management RS; and outputting the first and second parts of the interference management RS for transmission.

Clause 11: The method of Clause 10, wherein: the first network entity comprises a distributed unit (DU); and the second network entity comprises a radio unit (RU).

Clause 12: The method of any one of Clauses 10-11, wherein the function comprises a phase ramp.

Clause 13: The method of any one of Clauses 10-12, wherein the circularly time-shifted RS signal has a time circular shift length determined based on a length of cyclic prefix (CP) of the interference management RS.

Clause 14: The method of Clause 13, wherein the length of the CP of the interference management RS is based on (e.g., a sum of) a reference CP length and a length of a CP inserted at the second network entity.

Clause 15: The method of Clause 14, wherein the reference CP length is equal to the length of the CP inserted at the second network entity.

Clause 16: The method of Clause 14, wherein the CP of the interference management RS comprises: a first CP portion corresponding to the CP inserted at the second network entity; and a second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

Clause 17: The method of Clause 16, wherein the interference management RS comprises: the CP of the interference management RS, followed by two copies of the first RS sequence.

Clause 18: An apparatus, comprising: a memory comprising executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform a method in accordance with any one of Clauses 1-17.

Clause 19: An apparatus, comprising means for performing a method in accordance with any one of Clauses 1-17.

Clause 20: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of an apparatus, cause the apparatus to perform a method in accordance with any one of Clauses 1-17.

Clause 21: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-17.

Clause 22: A first network entity comprising: at least one transceiver, at least one memory comprising executable instructions; and at least one processor configured to execute the executable instructions and cause the first network entity to perform a method in accordance with any one of Clauses 1-9, wherein the at least one transceiver is configured to transmit the frequency domain samples.

Clause 23: A second network entity comprising: at least one transceiver, at least one memory comprising executable instructions; and at least one processor configured to execute the executable instructions and cause the first network entity to perform a method in accordance with any one of Clauses 10-17, wherein the at least one transceiver is configured to receive the frequency domain samples and transmit the first and second parts of the interference management RS.

Additional Considerations

The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various actions may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC), or any other such configuration.

Means for applying, means for outputting, means for obtaining, and means for performing may comprise one or more processors, such as one or more of the processors described above with reference to FIG. 13.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term wireless node may refer to, for example, a network entity or a user equipment (UE). In this context, a network entity may be a base station (e.g., a gNB) or a module (e.g., a CU, DU, and/or RU) of a disaggregated base station.

While the present disclosure may describe certain operations as being performed by one type of wireless node, the same or similar operations may also be performed by another type of wireless node. For example, operations performed by a network entity may also (or instead) be performed by a UE. Similarly, operations performed by a UE may also (or instead) be performed by a network entity.

Further, while the present disclosure may describe certain types of communications between different types of wireless nodes (e.g., between a network entity and a UE), the same or similar types of communications may occur between same types of wireless nodes (e.g., between network entities or between UEs, in a peer-to-peer scenario). Further, communications may occur in reverse direction relative to what is described (e.g., a UE could transmit a request to a network entity and the network entity transmits a response; OR a network entity could transmit the request to a UE and the UE transmits the response).

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The methods disclosed herein comprise one or more actions for achieving the methods. The method actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor.

As used herein, “a processor,” “at least one processor” or “one or more processors” generally refers to a single processor configured to perform one or multiple operations or multiple processors configured to collectively perform one or more operations. In the case of multiple processors, performance the one or more operations could be divided amongst different processors, though one processor may perform multiple operations, and multiple processors could collectively perform a single operation. Similarly, “a memory,” “at least one memory” or “one or more memories” generally refers to a single memory configured to store data and/or instructions, multiple memories configured to collectively store data and/or instructions.

The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. § 112 (f) unless the element is expressly recited using the phrase “means for”. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

1. An apparatus for wireless communications, comprising: at least one memory comprising computer-executable instructions; andone or more processors configured to execute the computer-executable instructions and cause the apparatus to: apply a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; andoutput frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.

2. The apparatus of claim 1, wherein: the frequency domain samples are output to a radio unit (RU).

3. The apparatus of claim 1, wherein the frequency domain function comprises a phase ramp.

4. The apparatus of claim 1, wherein the frequency domain function is designed to achieve a circularly time-shifted RS signal in the time domain after an inverse Fourier transform (IFT) is performed on the modified first copy of the first RS sequence.

5. The apparatus of claim 4, wherein the circularly time-shifted RS signal has a time circular shift length that is based on a length of cyclic prefix (CP) of an interference management RS.

6. The apparatus of claim 5, wherein the length of the CP of the interference management RS is based on a reference CP length and a length of another CP.

7. The apparatus of claim 6, wherein the reference CP length is equal to the length of the other CP.

8. The apparatus of claim 5, wherein the CP of the interference management RS comprises: a first CP portion corresponding to the other CP; anda second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

9. The apparatus of claim 6, wherein the interference management RS comprises: the CP of the interference management RS and two copies of the first RS sequence.

10. The apparatus of claim 1, further comprising at least one transceiver configured to transmit the frequency domain samples, wherein the apparatus is configured to operate as a distributed unit (DU).

11. An apparatus for wireless communications, comprising: at least one memory comprising computer-executable instructions; andone or more processors configured to execute the computer-executable instructions and cause the apparatus to: obtain frequency domain samples of a first copy of a first reference signal (RS) sequence and frequency domain samples of a second copy of the first RS sequence;apply a frequency domain function to the first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence;perform an inverse Fourier transform (IFT) on the modified first copy of the first RS sequence to obtain a circularly time-shifted RS signal in the time domain that forms a first part of an interference management RS;perform the IFT on the second copy of the first RS sequence to obtain a second part of the interference management RS; andoutput the first and second parts of the interference management RS for transmission.

12. The apparatus of claim 11, wherein: the frequency domain samples are obtained from a distributed unit (DU).

13. The apparatus of claim 11, wherein the frequency domain function comprises a phase ramp.

14. The apparatus of claim 11, wherein the circularly time-shifted RS signal has a time circular shift length that is based on a length of cyclic prefix (CP) of the interference management RS.

15. The apparatus of claim 14, wherein the length of the CP of the interference management RS is based on a reference CP length and a length of another CP.

16. The apparatus of claim 15, wherein the reference CP length is equal to the length of the other CP.

17. The apparatus of claim 14, wherein the CP of the interference management RS comprises: a first CP portion corresponding to the other CP; anda second CP portion corresponding to a circularly shifted portion of the first copy of the first RS sequence.

18. The apparatus of claim 14, wherein the interference management RS comprises: the CP of the interference management RS and two copies of the first RS sequence.

19. The apparatus of claim 11, further comprising at least one transceiver configured to receive the frequency domain samples and transmit first and second parts of the interference management RS, wherein the apparatus is configured to operate as a radio unit (RU).

20. A method for wireless communications at a first network entity, comprising: applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence; andoutputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.