WO2020258132A1

WO2020258132A1 - Csi reporting for partial reciprocity

Info

Publication number: WO2020258132A1
Application number: PCT/CN2019/093194
Authority: WO
Inventors: Liangming WU; Chao Wei; Chenxi HAO; Qiaoyu Li; Yu Zhang; Joseph Binamira Soriaga; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2019-06-27
Filing date: 2019-06-27
Publication date: 2020-12-30

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS). The UE may transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS. Numerous other aspects are provided.

Description

CSI REPORTING FOR PARTIAL RECIPROCITY

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for channel state information (CSI) reporting for partial reciprocity.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and/or the like) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) . A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New Radio (NR) , which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP) . NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a user equipment (UE) , may include transmitting, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) ; and transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.

In some aspects, a UE for wireless communication may include memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to transmit, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI-RS; and transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.

In some aspects, a method of wireless communication, performed by a base station (BS) , may include transmitting, to a UE, an indication of a CSI configuration; transmitting, to the UE, a CSI-RS; and receiving, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to transmit, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI-RS; and transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.

In some aspects, an apparatus for wireless communication may include means for transmitting, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI-RS; and means for transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.

In some aspects, a BS for wireless communication may include memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to transmit, to a UE, an indication of a CSI configuration; transmit, to the UE, a CSI-RS; and receive, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a BS, may cause the one or more processors to: transmit, to a UE, an indication of a CSI configuration; transmit, to the UE, a CSI-RS; and receive, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.

In some aspects, an apparatus for wireless communication may include means for transmitting, to a UE, an indication of a CSI configuration; means for transmitting, to the UE, a CSI-RS; and means for receiving, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 2 is a block diagram conceptually illustrating an example of a base station (BS) in communication with a user equipment (UE) in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 3A is a block diagram conceptually illustrating an example of a frame structure in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 3B is a block diagram conceptually illustrating an example synchronization communication hierarchy in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 4 is a block diagram conceptually illustrating an example slot format with a normal cyclic prefix, in accordance with various aspects of the present disclosure.

Figs. 5A-5G are diagrams illustrating one or more examples of channel state information (CSI) reporting for partial reciprocity, in accordance with various aspects of the present disclosure.

Fig. 6 is a diagram illustrating an example process performed, for example, by a UE, in accordance with various aspects of the present disclosure.

Fig. 7 is a diagram illustrating an example process performed, for example, by a BS, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. 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 which 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.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Fig. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in Fig. 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some aspects, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Fig. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 Watts) .

A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like. A UE may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and/or the like, that may communicate with a base station, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE) . UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a base station 110 as an intermediary to communicate with one another) . For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like) , a mesh network, and/or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the base station 110.

As indicated above, Fig. 1 is provided as an example. Other examples may differ from what is described with regard to Fig. 1.

Fig. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

At base station 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS (s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , reference signal received quality (RSRQ) , channel quality indicator (CQI) , and/or the like. In some aspects, one or more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110. At base station 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240. Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with channel state information (CSI) reporting for partial reciprocity, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 600 of Fig. 6, process 700 of Fig. 7, and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. In some aspects, memory 242 and/or memory 282 may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors of the base station 110 and/or the UE 120, may perform or direction operations of, for example, process 600 of Fig. 6, process 700 of Fig. 7, and/or other processes as described herein. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for transmitting, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) , means for transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS, and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2, such as controller/processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and/or the like.

In some aspects, base station 110 may include means for transmitting, to a UE 120, an indication of a CSI configuration, means for transmitting, to the UE 120, a CSI-RS, means for receiving, from the UE 120, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration, and/or the like. In some aspects, such means may include one or more components of base station 110 described in connection with Fig. 2, such as antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller/processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, antenna 234, and/or the like.

As indicated above, Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.

Fig. 3A shows an example frame structure 300 for frequency division duplexing (FDD) in a telecommunications system (e.g., NR) . The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames (sometimes referred to as frames) . Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms) ) and may be partitioned into a set of Z (Z ≥ 1) subframes (e.g., with indices of 0 through Z-1) . Each subframe may have a predetermined duration (e.g., 1 ms) and may include a set of slots (e.g., 2 ^m slots per subframe are shown in Fig. 3A, where m is a numerology used for a transmission, such as 0, 1, 2, 3, 4, and/or the like) . Each slot may include a set of L symbol periods. For example, each slot may include fourteen symbol periods (e.g., as shown in Fig. 3A) , seven symbol periods, or another number of symbol periods. In a case where the subframe includes two slots (e.g., when m = 1) , the subframe may include 2L symbol periods, where the 2L symbol periods in each subframe may be assigned indices of 0 through 2L–1. In some aspects, a scheduling unit for the FDD may be frame-based, subframe-based, slot-based, symbol-based, and/or the like.

While some techniques are described herein in connection with frames, subframes, slots, and/or the like, these techniques may equally apply to other types of wireless communication structures, which may be referred to using terms other than “frame, ” “subframe, ” “slot, ” and/or the like in 5G NR. In some aspects, a wireless communication structure may refer to a periodic time-bounded communication unit defined by a wireless communication standard and/or protocol. Additionally, or alternatively, different configurations of wireless communication structures than those shown in Fig. 3A may be used.

In certain telecommunications (e.g., NR) , a base station may transmit synchronization signals. For example, a base station may transmit a primary synchronization signal (PSS) , a secondary synchronization signal (SSS) , and/or the like, on the downlink for each cell supported by the base station. The PSS and SSS may be used by UEs for cell search and acquisition. For example, the PSS may be used by UEs to determine symbol timing, and the SSS may be used by UEs to determine a physical cell identifier, associated with the base station, and frame timing. The base station may also transmit a physical broadcast channel (PBCH) . The PBCH may carry some system information, such as system information that supports initial access by UEs.

In some aspects, the base station may transmit the PSS, the SSS, and/or the PBCH in accordance with a synchronization communication hierarchy (e.g., a synchronization signal (SS) hierarchy) including multiple synchronization communications (e.g., SS blocks) , as described below in connection with Fig. 3B.

Fig. 3B is a block diagram conceptually illustrating an example SS hierarchy, which is an example of a synchronization communication hierarchy. As shown in Fig. 3B, the SS hierarchy may include an SS burst set, which may include a plurality of SS bursts (identified as SS burst 0 through SS burst B-1, where B is a maximum number of repetitions of the SS burst that may be transmitted by the base station) . As further shown, each SS burst may include one or more SS blocks (identified as SS block 0 through SS block (b _{max_SS}-1) , where b _{max_SS}-1 is a maximum number of SS blocks that can be carried by an SS burst) . In some aspects, different SS blocks may be beam-formed differently. An SS burst set may be periodically transmitted by a wireless node, such as every X milliseconds, as shown in Fig. 3B. In some aspects, an SS burst set may have a fixed or dynamic length, shown as Y milliseconds in Fig. 3B.

The SS burst set shown in Fig. 3B is an example of a synchronization communication set, and other synchronization communication sets may be used in connection with the techniques described herein. Furthermore, the SS block shown in Fig. 3B is an example of a synchronization communication, and other synchronization communications may be used in connection with the techniques described herein.

In some aspects, an SS block includes resources that carry the PSS, the SSS, the PBCH, and/or other synchronization signals (e.g., a tertiary synchronization signal (TSS) ) and/or synchronization channels. In some aspects, multiple SS blocks are included in an SS burst, and the PSS, the SSS, and/or the PBCH may be the same across each SS block of the SS burst. In some aspects, a single SS block may be included in an SS burst. In some aspects, the SS block may be at least four symbol periods in length, where each symbol carries one or more of the PSS (e.g., occupying one symbol) , the SSS (e.g., occupying one symbol) , and/or the PBCH (e.g., occupying two symbols) .

In some aspects, the symbols of an SS block are consecutive, as shown in Fig. 3B. In some aspects, the symbols of an SS block are non-consecutive. Similarly, in some aspects, one or more SS blocks of the SS burst may be transmitted in consecutive radio resources (e.g., consecutive symbol periods) during one or more slots. Additionally, or alternatively, one or more SS blocks of the SS burst may be transmitted in non-consecutive radio resources.

In some aspects, the SS bursts may have a burst period, whereby the SS blocks of the SS burst are transmitted by the base station according to the burst period. In other words, the SS blocks may be repeated during each SS burst. In some aspects, the SS burst set may have a burst set periodicity, whereby the SS bursts of the SS burst set are transmitted by the base station according to the fixed burst set periodicity. In other words, the SS bursts may be repeated during each SS burst set.

The base station may transmit system information, such as system information blocks (SIBs) on a physical downlink shared channel (PDSCH) in certain slots. The base station may transmit control information/data on a physical downlink control channel (PDCCH) in C symbol periods of a slot, where B may be configurable for each slot. The base station may transmit traffic data and/or other data on the PDSCH in the remaining symbol periods of each slot.

As indicated above, Figs. 3A and 3B are provided as examples. Other examples may differ from what is described with regard to Figs. 3A and 3B.

Fig. 4 shows an example slot format 410 with a normal cyclic prefix. The available time frequency resources may be partitioned into resource blocks. Each resource block may cover a set of subcarriers (e.g., 12 subcarriers) in one slot and may include a number of resource elements. Each resource element may cover one subcarrier in one symbol period (e.g., in time) and may be used to send one modulation symbol, which may be a real or complex value.

An interlace structure may be used for each of the downlink and uplink for FDD in certain telecommunications systems (e.g., NR) . For example, Q interlaces with indices of 0 through Q –1 may be defined, where Q may be equal to 4, 6, 8, 10, or some other value. Each interlace may include slots that are spaced apart by Q frames. In particular, interlace q may include slots q, q + Q, q + 2Q, etc., where q ∈ {0, …, Q –1} .

A UE may be located within the coverage of multiple BSs. One of these BSs may be selected to serve the UE. The serving BS may be selected based at least in part on various criteria such as received signal strength, received signal quality, path loss, and/or the like. Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SNIR) , or a reference signal received quality (RSRQ) , or some other metric. The UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering BSs.

While aspects of the examples described herein may be associated with NR or 5G technologies, aspects of the present disclosure may be applicable with other wireless communication systems. New Radio (NR) may refer to radios configured to operate according to a new air interface (e.g., other than Orthogonal Frequency Divisional Multiple Access (OFDMA) -based air interfaces) or fixed transport layer (e.g., other than Internet Protocol (IP) ) . In aspects, NR may utilize OFDM with a CP (herein referred to as cyclic prefix OFDM or CP-OFDM) and/or SC-FDM on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using time division duplexing (TDD) . In aspects, NR may, for example, utilize OFDM with a CP (herein referred to as CP-OFDM) and/or discrete Fourier transform spread orthogonal frequency-division multiplexing (DFT-s-OFDM) on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using TDD. NR may include Enhanced Mobile Broadband (eMBB) service targeting wide bandwidth (e.g., 80 megahertz (MHz) and beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 60 gigahertz (GHz) ) , massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra reliable low latency communications (URLLC) service.

In some aspects, a single component carrier bandwidth of 100 MHz may be supported. NR resource blocks may span 12 sub-carriers with a sub-carrier bandwidth of 60 or 120 kilohertz (kHz) over a 0.1 millisecond (ms) duration. Each radio frame may include 40 slots and may have a length of 10 ms. Consequently, each slot may have a length of 0.25 ms. Each slot may indicate a link direction (e.g., DL or UL) for data transmission and the link direction for each slot may be dynamically switched. Each slot may include DL/UL data as well as DL/UL control data.

Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells. Alternatively, NR may support a different air interface, other than an OFDM-based interface. NR networks may include entities such as central units or distributed units.

As indicated above, Fig. 4 is provided as an example. Other examples may differ from what is described with regard to Fig. 4.

A UE and a BS may perform wireless communication in a wireless network. To facilitate bandwidth selection and parameters for the wireless communication link between the UE and the BS, a UE may transmit an SRS to the BS. The BS may perform one or more measurements of the SRS (which may be referred to as a channel estimation) and may select the bandwidth and/or other parameters for the wireless communication link based at least in part on the results of the one or more measurements. In some cases, a UE may support full reciprocity, in which case the UE is configured and/or equipped with an equal quantity of transmit elements (e.g., antennas, antenna arrays, antenna panels, and/or the like) and receive elements. In this case, the BS may use the result of an uplink channel estimation for downlink channel estimation due to the equality between the transmit elements and receive elements of the UE. However, if a UE is configured and/or equipped with an unequal quantity of transmit elements and receive elements (which may be referred to as partial reciprocity) , the BS may be unable to estimate the downlink based at least in part on full reciprocity with the uplink.

Some techniques and apparatuses described herein provide CSI reporting for partial reciprocity. In some aspects, a BS may transmit a CSI configuration to a UE that may not support full reciprocity (e.g., a UE that is configured and/or equipped with a greater quantity of receive elements relative to a quantity of transmit elements) . The CSI configuration may include information and/or one or more parameters for generating and transmitting an uplink reference signal and a partial reciprocity explicit CSI report to the BS. The BS may transmit a CSI-RS to the UE, and the UE may transmit, to the BS, an uplink reference signal and a partial reciprocity explicit CSI report for the CSI-RS. The SRS and the partial reciprocity explicit CSI report may be based at least in part on the CSI configuration. In this way, the BS may perform a downlink channel estimation of a downlink between the UE and the BS based at least in part on a combination of the uplink reference signal and the partial reciprocity explicit CSI report, which increases the accuracy of the downlink channel estimation and improves downlink channel quality for partial reciprocity.

Fig. 5A-5G are diagrams illustrating one or more examples 500 of channel state information (CSI) reporting for partial reciprocity, in accordance with various aspects of the present disclosure. As shown in Figs. 5A-5G, examples 500 may include communication between a BS (e.g., BS 110) and a UE (e.g., UE 120) . In some aspects, the BS and the UE may be included in a wireless network (e.g., wireless network 100) . In some aspects, the BS and the UE may communicate using a frame structure (e.g., frame structure 300 illustrated in Fig. 3A and/or another frame structure) , a slot format (e.g., slot format 410 illustrated in Fig. 4 and/or another slot format) , and/or the like.

In some aspects, the UE may be configured and/or equipped with an unequal quantity of transmit elements and receive elements (e.g., a greater quantity of receive elements relative to the quantity of transmit elements) . In this case, the BS may be unable to estimate the downlink of the wireless communication link using full reciprocity channel estimation techniques.

As shown in Fig. 5A, and by reference number 502, in order to assist the BS in fully estimating the downlink, the BS may transmit a CSI configuration to the UE. The CSI configuration may include information and/or one or more parameters for generating and transmitting an SRS and a partial reciprocity explicit CSI report to the BS. The UE may use the information and/or the one or more parameters to generate and transmit an uplink reference signal and a partial reciprocity explicit CSI report that are associated with a CSI-RS transmitted by the BS. The uplink reference signal may include an SRS, a demodulation reference signal (DMRS) , and/or the like. The partial reciprocity explicit CSI report may be a CSI report that includes explicit reporting information, such as an estimated covariance matrix associated with the downlink, one or more eigenvectors or eigenvalues of the covariance matrix, and/or the like. The BS may use the uplink reference and the partial reciprocity explicit CSI report to fully estimate the downlink.

In some aspects, the BS may transmit an indication of the CSI configuration in one or more communications, such as one or more radio resource control (RRC) communications, one or more medium access control (MAC) control element (MAC-CE) communications, one or more downlink control information (DCI) communications, and/or the like. In some aspects, the BS may transmit the indication of the CSI configuration to the UE during a random access channel (RACH) procedure, after the UE is communicatively connected and/or RRC configured for the BS, and/or the like. In some aspects, the BS may transmit the indication of the CSI configuration based at least in part on receiving an indication that the UE does not support full reciprocity or that the UE supports partial reciprocity. The indication that the UE does not support full reciprocity or that the UE supports partial reciprocity may be indicated in an uplink reference signal transmitted by the UE, may be indicated in other communications with the BS, such as during a RACH procedure, UE uplink signaling, and/or the like.

In some aspects, the CSI configuration may identify a CSI-RS resource set for a CSI-RS to be transmitted by the BS. The CSI-RS resource set may include time-domain resources (e.g., one or more symbols, one or more slots, one or more subframes, one or more radio frames and/or the like) and/or frequency-domain resources (e.g., one or more subcarriers, one or more resource blocks, and/or the like) in which the BS may transmit the CSI-RS. The UE may perform one or more measurements associated with the CSI-RS and may report the measurement results to the BS as the measurements results for the CSI-RS resource set by transmitting a partial reciprocity explicit CSI report for the CSI-RS resource set for the CSI-RS.

In some aspects, the CSI configuration may identify a plurality of CSI-RS resource sets. In this case, the BS may transmit the CSI-RS for each CSI-RS resource set. In some aspects, the CSI configuration may configure the UE to report the measurement results for each CSI-RS resource set. In this case, the UE may transmit a partial reciprocity explicit CSI report for the plurality of the CSI-RS resource sets for the CSI-RS. In some aspects, the CSI configuration may configure the UE to select a CSI-RS resource set and to report the measurement results for the selected CSI-RS resource set to the BS. In this case, the UE may transmit a partial reciprocity explicit CSI report for a CSI-RS resource set of the plurality of the CSI-RS resource sets for the CSI-RS, and the selected CSI-RS resource set may be indicated (e.g., in the partial reciprocity explicit CSI report) by a CSI-RS resource indicator (CRI) in the partial reciprocity explicit CSI report.

In some aspects, the CSI configuration may identify one or more antenna ports. Each antenna port may correspond to a respective transmit element or antenna of the UE. The CSI configuration may identify one or more antenna ports, associated with the UE, for transmitting the uplink reference signal and/or the partial reciprocity explicit CSI report to the BS. In this case, the UE may transmit the uplink reference signal and/or the partial reciprocity explicit CSI report via each identified antenna port, may transmit respective uplink reference signals and/or the partial reciprocity explicit CSI reports via each identified antenna port, and/or the like.

In some aspects, the CSI configuration may identify the uplink reference signal type for the uplink reference signal to be transmitted by the UE. For example, the uplink reference signal may include an SRS, a DMRS, and/or the like. In some aspects, if the uplink reference signal is an SRS, the CSI configuration may identify an SRS resource and/or SRS resource set for transmitting the SRS (e.g., a time-domain and/or frequency domain resource, a plurality of time-domain and/or frequency domain resources, and/or the like) , may identify a sequence for the SRS (e.g., a Zadoff-Chu sequence, a Gold code sequence, and/or the like) , an antenna switching parameter for transmitting the SRS, and/or the like. Additionally and/or alternatively, an SRS configuration, separate from the CSI configuration, may indicate and/or specify the sequence for the SRS and/or the antenna switching parameter. The antenna switching parameter may indicate that the UE is to determine the antenna port via which the UE is to transmit the SRS and/or the partial reciprocity explicit CSI report. In this case, the UE may identify the antenna port based at least in part on the CSI-RS (e.g., by performing one or more measurements of the CSI-RS and selecting the antenna port associated with the best reception, quality, and/or power for the CSI-RS, and/or the like) and may transmit the SRS and/or the partial reciprocity explicit CSI report via the antenna port.

In some aspects, if the uplink reference signal is a DMRS, the CSI configuration may identify an uplink channel on which to transmit the DMRS and/or the partial reciprocity explicit CSI report. For example, the CSI configuration may indicate that the UE is to transmit the DMRS and/or the partial reciprocity explicit CSI report on a physical uplink shared channel (PUSCH) , on a physical uplink control channel (PUCCH) , and/or the like.

In some aspects, the CSI configuration may identify a bandwidth of the CSI-RS for the partial reciprocity explicit CSI report. The bandwidth of the CSI-RS, for the partial reciprocity explicit CSI report, may include the full or entire bandwidth of the CSI-RS (e.g., in which case the partial reciprocity explicit CSI report may be transmitted using the full bandwidth of the CSI-RS) or may include a subset (or subsets) of the full or entire bandwidth of the CSI-RS (e.g., in which case the partial reciprocity explicit CSI report may be transmitted using the subset bandwidth of the full or entire bandwidth of the CSI-RS) .

In some aspects, the CSI configuration may identify respective bandwidths of the CSI-RS for the partial reciprocity explicit CSI report for a plurality of antenna ports associated with the UE. For example, the CSI configuration may identify a first bandwidth of the CSI-RS (e.g., full or entire bandwidth, or subset of the full or entire bandwidth) for the partial reciprocity explicit CSI report via a first antenna port, may identify a second bandwidth of the CSI-RS (e.g., full or entire bandwidth, or subset of the full or entire bandwidth) for the partial reciprocity explicit CSI report via a second antenna port, and so on. In this case, the respective bandwidths may be the same bandwidth or different bandwidths.

Figs. 5B-5D illustrate various bandwidth examples that may be configured by the CSI configuration. Other examples of the CSI-RS for the partial reciprocity explicit CSI report may be configured. As shown by bandwidth example 1 in Fig. 5B, if the CSI configuration indicates and/or specifies that the UE is to transmit an SRS via a first antenna port (e.g., Port 1) , the CSI configuration may indicate and/or specify that the UE is to transmit, via the first antenna port, a first transmission of the partial reciprocity explicit CSI report using a subset of the full bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the SRS. In some aspects, the CSI configuration may indicate and/or specify that the UE is to transmit other transmissions of the partial reciprocity explicit CSI report on other antenna ports. For example, the CSI configuration may indicate and/or specify that the UE is to transmit, via a second antenna port (e.g., Port 2) , a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS.

As shown by bandwidth example 2 in Fig. 5C, if the CSI configuration indicates and/or specifies that the UE is to transmit an SRS via a first antenna port (e.g., Port 1) , the CSI configuration may indicate and/or specify that the UE is to transmit, via the first antenna port, a first transmission of the partial reciprocity explicit CSI report using the full or entire bandwidth of the CSI-RS. In this case, if a subset of the full or entire bandwidth of the CSI-RS is non-overlapping with the bandwidth for transmitting the SRS, the CSI configuration may indicate and/or specify that the UE is to transmit a first portion of the partial reciprocity explicit CSI report using the subset of the full or entire bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the SRS.

If another subset of the full or entire bandwidth of the CSI-RS is overlapping with the bandwidth for transmitting the SRS, the CSI configuration may indicate and/or specify that the UE is to transmit a second portion of the partial reciprocity explicit CSI report using the subset of the full or entire bandwidth of the CSI-RS that is overlapping with the bandwidth for transmitting the SRS. In this case, the BS may combine the feedback included in the second portion of the partial reciprocity explicit CSI report with measurement results from one or more measurements (e.g., performed by the BS) associated with the SRS. Moreover, the CSI configuration may indicate and/or specify that the UE is to transmit the second portion of the partial reciprocity explicit CSI report with reduced granularity (e.g., lower frequency granularity, lower quantization granularity, and/or the like) relative to the first portion of the partial reciprocity explicit CSI report. For example, the CSI configuration may include a frequency-domain compression parameter for the partial reciprocity explicit CSI report that specifies a frequency-domain sampling rate and/or a quantization parameter for the partial reciprocity explicit CSI report that specifies a time-domain sampling rate to be used for the first portion. The CSI configuration may further include an explicit indication of a lower frequency-domain compression and/or quantization parameter for the second portion relative to the first portion, or may include an implicit indication implicit (e.g., ratio, a percentage, and/or the like) relative to the frequency-domain compression and/or the quantization parameter for the first portion.

In some aspects, the CSI configuration may indicate and/or specify that the UE is to transmit other transmissions of the partial reciprocity explicit CSI report on other antenna ports. For example, the CSI configuration may indicate and/or specify that the UE is to transmit, via a second antenna port (e.g., Port 2) , a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS.

As shown by bandwidth example 3 in Fig. 5D, if the CSI configuration indicates and/or specifies that the UE is to transmit a DMRS, the CSI configuration may indicate and/or specify that the UE is to transmit the partial reciprocity explicit CSI report using the same bandwidth as the bandwidth configured for transmitting the DMRS. The bandwidth for transmitting the DMRS and the partial reciprocity explicit CSI report may include the full bandwidth or a subset of the full bandwidth of the CSI-RS.

In some aspects, the CSI configuration may include one or more transmission timing parameters for transmitting the partial reciprocity explicit CSI report and the uplink reference signal. The one or more transmission timing parameters may indicate and/or specify a transmission timing association between the transmission of the CSI-RS, the transmission of the partial reciprocity explicit CSI report, the transmission of the uplink reference signal, and/or the transmission of other uplink reference signals.

Figs. 5E and 5F illustrate various transmission timing examples that may be configured by the CSI configuration. Other examples of transmission timing may be configured. As shown by transmission timing example 1 in Fig. 5E, the one or more transmission timing parameters may indicate and/or specify that the partial reciprocity explicit CSI report is to be transmitted after transmission of a most recent transmission of the uplink reference signal. For example, the UE may be configured to transmit the partial reciprocity explicit CSI report via a second antenna port (e.g., Port 2) after the transmission of an SRS via a first antenna port (e.g., Port 1) . In this case, the transmission of the partial reciprocity explicit CSI report via a second antenna port may be associated with the transmission of the SRS on the first antenna port. As another example, the UE may be configured to transmit another partial reciprocity explicit CSI report on the first antenna port (e.g., Port 1) after the transmission of another SRS via the second antenna port (e.g., Port 2) . In this case, the transmission of the other partial reciprocity explicit CSI report via a first antenna port may be associated with the transmission of the other SRS via the second antenna port.

As shown by transmission timing example 2 in Fig. 5E, the one or more transmission timing parameters may indicate and/or specify that the partial reciprocity explicit CSI report is to be transmitted prior to the transmission of a most recent transmission of the uplink reference signal. For example, the UE may be configured to transmit the partial reciprocity explicit CSI report via a second antenna port (e.g., Port 2) prior to the transmission of an SRS via a first antenna port (e.g., Port 1) . In this case, the transmission of the partial reciprocity explicit CSI report via a second antenna port may be associated with the transmission of the SRS via the first antenna port. As another example, the UE may be configured to transmit another partial reciprocity explicit CSI report via the first antenna port (e.g., Port 1) prior to the transmission of another SRS via the second antenna port (e.g., Port 2) . In this case, the transmission of the other partial reciprocity explicit CSI report via a first antenna port may be associated with the transmission of the other SRS via the second antenna port.

As shown by transmission timing example 3 in Fig. 5E, the one or more transmission timing parameters may explicitly indicate which partial reciprocity explicit CSI report is to be associated with which uplink reference signal. In this case, the CSI configuration may explicitly indicate that the transmission of the partial reciprocity explicit CSI report via a first antenna port (e.g., Port 1) may be associated with the transmission of an SRS via the first antenna port, may explicitly indicate that the transmission of the partial reciprocity explicit CSI report via a second antenna port (e.g., Port 2) may be associated with the transmission of an SRS via the second antenna port, and/or the like.

In some aspects, the one or more transmission timing parameters may indicate and/or specify that the transmission of an uplink reference signal, a partial reciprocity explicit CSI report, and associated CSI-RS are to occur in the same time-domain resource or are to occur in different time-domain resources, are to occur in the same time-domain resource across a plurality of time-domain resources, and/or the like. As shown by transmission timing example 4 in Fig. 5F, for example, the one or more transmission timing parameters may indicate and/or specify that the transmission of an SRS, a partial reciprocity explicit CSI report, and associated CSI-RS are to occur in the same slot. Moreover, the one or more transmission timing parameters may indicate and/or specify that the transmission of an SRS, a partial reciprocity explicit CSI report, and associated CSI-RS are to occur in the same slot for a plurality of slots (e.g., Slot 1 through Slot n) .

In some aspects, the one or more transmission timing parameters may indicate and/or specify that a CSI-RS, associated with a particular transmission of an uplink reference signal, is to be precoded or non-precoded for purposes of beamforming the CSI-RS, which may reduce the overhead of the CSI-RS. For example, the one or more transmission timing parameters may indicate and/or specify that a CSI-RS is to be precoded based at least in part on a transmission of an SRS prior to the transmission of the precoded CSI-RS. Moreover, the one or more transmission timing parameters may indicate a time location of the transmission of the SRS (e.g., in the most recent slot relative to a slot in which the transmission of the precoded CSI-RS is to occur, in a slot that occurred a quantity of slots prior to a slot in which the transmission of the precoded CSI-RS is to occur, and/or the like) .

As shown in Fig. 5G, and by reference number 504, the BS may transmit a CSI-RS to the UE. In some aspects, the BS may transmit a plurality of CSI-RSs to the UE, may transmit CSI-RSs in a periodic transmission interval, and/or the like. In some aspects, the BS may transmit the CSI-RS according to the CSI configuration. For example, the BS may transmit the CSI-RS in the associated CSI-RS resource set indicated in the CSI configuration, the plurality of CSI-RS resource sets indicated in the CSI configuration, and/or the like.

As further shown in Fig. 5G, and by reference number 506, the UE may transmit, to the BS, an uplink reference signal and a partial reciprocity explicit CSI report for the CSI-RS. In some aspects, the UE may generate the partial reciprocity explicit CSI report by performing one or more measurements of the CSI-RS, estimating a covariance matrix associated with the downlink based at least in part on the measurement results, estimating one or more eigenvectors or eigenvalues of the covariance matrix based at least in part on the measurement results, and/or the like. In some aspects, the UE may generate and transmit the uplink reference signal and/or the partial reciprocity explicit CSI report based at least in part on the CSI configuration.

For example, the UE may generate and transmit a partial reciprocity explicit CSI report for each CSI-RS resource set indicated in the CSI configuration, for a CSI-RS resource set of a plurality of CSI-RS resource sets indicated in the CSI configuration and/or the like. As another example, the UE may generate and transmit the uplink reference signal using the SRS resource indicated in the CSI configuration, using the SRS resource set indicated in the CSI configuration, using the sequence indicated in the CSI configuration, and/or the like.

As another example, the UE may transmit the uplink reference signal and the partial reciprocity explicit CSI report via the one or more antenna ports indicated in the CSI configuration, via one or more antenna ports determined by the UE based at least in part on the antenna switching parameter indicated in the CSI configuration, and/or the like. As a further example, the UE may transmit the partial reciprocity explicit CSI report using the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report indicated in the CSI configuration, based at least in part on the frequency-domain compression parameter indicated in the CSI configuration, based at least in part on the quantization parameter indicated in the CSI configuration, and/or the like. Moreover, as an example, the UE may transmit the uplink reference signal and/or the partial reciprocity explicit CSI report based at least in part on the one or more transmission timing parameters indicated in the CSI configuration.

In this way, the BS may transmit a CSI configuration to the UE (e.g., a UE that may not support full reciprocity) . The CSI configuration may include information and/or one or more parameters for generating and transmitting an uplink reference signal and a partial reciprocity explicit CSI report to the BS. The BS may transmit a CSI-RS to the UE, and the UE may transmit, to the BS, an uplink reference signal and a partial reciprocity explicit CSI report for the CSI-RS. The SRS and the partial reciprocity explicit CSI report may be based at least in part on the CSI configuration. In this way, the BS may perform a downlink channel estimation of a downlink between the UE and the BS based at least in part on a combination of the uplink reference signal and the partial reciprocity explicit CSI report, which increases the accuracy of the downlink channel estimation and improves downlink channel quality for partial reciprocity. For example, the BS may select beams, layers, streams, bandwidth allocation, transport block size, and/or other parameters for the downlink and/or the uplink of the wireless communication link between the BS and the UE based at least in part on the information indicated in the partial reciprocity explicit CSI report, based at least in part on performing one or more measurements of the SRS, and/or the like.

As indicated above, Figs. 5A-5G are provided as one or more examples. Other examples may differ from what is described with respect to Figs. 5A-5G.

Fig. 6 is a diagram illustrating an example process 600 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 600 is an example where a UE (e.g., UE 120) performs operations associated with CSI reporting for partial reciprocity.

As shown in Fig. 6, in some aspects, process 600 may include transmitting, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI-RS (block 610) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may transmit, based at least in part on a CSI configuration, an uplink reference signal associated with a CSI-RS, as described above.

As further shown in Fig. 6, in some aspects, process 600 may include transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS (block 620) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS, as described above.

Process 600 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the UE is configured with a quantity of receive elements that is greater relative to a quantity of transmit elements with which the UE is configured. In a second aspect, alone or in combination with the first aspect, the CSI configuration identifies a CSI-RS resource set for the CSI-RS, and transmitting the partial reciprocity explicit CSI report comprises transmitting the partial reciprocity explicit CSI report for the CSI-RS resource set for the CSI-RS. In a third aspect, alone or in combination with one or more of the first and second aspects, the CSI configuration identifies a plurality of CSI-RS resource sets for the CSI-RS, and transmitting the partial reciprocity explicit CSI report comprises transmitting the partial reciprocity explicit CSI report for the plurality of the CSI-RS resource sets for the CSI-RS.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the CSI configuration identifies a plurality of CSI-RS resource sets for the CSI-RS, and transmitting the partial reciprocity explicit CSI report comprises transmitting the partial reciprocity explicit CSI report for a CSI-RS resource set of the plurality of the CSI-RS resource sets for the CSI-RS, wherein the CSI-RS resource set is indicated in the partial reciprocity explicit CSI report by a CSI-RS resource indicator. In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the CSI configuration identifies a CSI-RS resource set for the CSI-RS, and transmitting the partial reciprocity explicit CSI report comprises transmitting the partial reciprocity explicit CSI report based at least in part on the CSI-RS resource set for a CSI-RS.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the CSI configuration identifies at least one of one or more antenna ports for transmitting the partial reciprocity explicit CSI report, a frequency-domain compression parameter for the partial reciprocity explicit CSI report, a bandwidth of the CSI-RS for the partial reciprocity explicit CSI report, a transmission timing parameter for the partial reciprocity explicit CSI report, or a quantization parameter for the partial reciprocity explicit CSI report. In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the one or more antenna ports are to be used for transmitting the uplink reference signal, and the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises a subset, of a full bandwidth of the CSI-RS, that is non-overlapping with a bandwidth for transmitting the uplink reference signal.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, transmitting the partial reciprocity explicit CSI report comprises transmitting, via the first antenna port of the one or more antenna ports, a first transmission of the partial reciprocity explicit CSI report using the subset of the full bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the uplink reference signal; and transmitting, via a second antenna port of the one or more antenna ports, a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS. In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, a first antenna port, of the one or more antenna ports, is to be used for transmitting the uplink reference signal, and the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises a full bandwidth of the CSI-RS.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, a first subset of the full bandwidth of the CSI-RS is non-overlapping with a bandwidth for transmitting the uplink reference signal, a second subset of the full bandwidth of the CSI-RS is overlapping with a bandwidth for transmitting the uplink reference signal, and transmitting the partial reciprocity explicit CSI report comprises transmitting a first portion of the partial reciprocity explicit CSI report using the first subset and transmitting a second portion of the partial reciprocity explicit CSI report, using the second subset, with lower frequency granularity or quantization granularity relative to the first portion. In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted after transmission of the uplink reference signal, and the uplink reference signal is a most recent uplink reference signal that is transmitted prior to transmission of the partial reciprocity explicit CSI report.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted prior to transmission of the uplink reference signal, and the uplink reference signal is a most recent uplink reference signal that is transmitted after transmission of the partial reciprocity explicit CSI report. In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the transmission timing parameter for the partial reciprocity explicit CSI report specifies that the uplink reference signal is to be associated with the partial reciprocity explicit CSI report.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report and the uplink reference signal are to be transmitted in a same slot as the CSI-RS, and the CSI-RS is transmitted prior to the partial reciprocity explicit CSI report and the uplink reference signal in the same slot. In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the CSI-RS is a non-precoded CSI-RS. In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the CSI-RS is a precoded CSI-RS that is precoded based at least in part on another uplink reference signal that was transmitted by the UE prior to transmission of the precoded CSI-RS.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the uplink reference signal comprises an SRS, and the CSI configuration identifies at least one of one or more antenna ports for transmitting the SRS, an SRS resource for transmitting the SRS, or an SRS resource set for transmitting the SRS. In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, an antenna switching parameter of the CSI configuration indicates the UE is to determine an antenna port for transmitting the SRS, and transmitting the SRS comprises identifying the antenna port based at least in part on the CSI-RS transmitting the SRS via the antenna port. In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, transmitting the partial reciprocity explicit CSI report comprises transmitting the partial reciprocity explicit CSI report via the antenna port.

In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, the uplink reference signal comprises a DMRS, and transmitting the uplink reference signal comprises transmitting the partial reciprocity explicit CSI report. In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, process 600 further comprises receiving an indication of the CSI configuration in at least one of an RRC communication, a MAC-CE communication, or a DCI communication.

Although Fig. 6 shows example blocks of process 600, in some aspects, process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 6. Additionally, or alternatively, two or more of the blocks of process 600 may be performed in parallel.

Fig. 7 is a diagram illustrating an example process 700 performed, for example, by a BS, in accordance with various aspects of the present disclosure. Example process 700 is an example where a BS (e.g., BS 110) performs operations associated with CSI reporting for partial reciprocity.

As shown in Fig. 7, in some aspects, process 700 may include transmitting, to a UE, an indication of a CSI configuration (block 710) . For example, the BS (e.g., using transmit processor 220, receive processor 238, controller/processor 240, memory 242, and/or the like) may transmit, to a UE, an indication of a CSI configuration, as described above.

As further shown in Fig. 7, in some aspects, process 700 may include transmitting, to the UE, a CSI-RS (block 720) . For example, the BS (e.g., using transmit processor 220, receive processor 238, controller/processor 240, memory 242, and/or the like) may transmit, to the UE, a CSI-RS, as described above.

As further shown in Fig. 7, in some aspects, process 700 may include receiving, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration (block 730) . For example, the BS (e.g., using transmit processor 220, receive processor 238, controller/processor 240, memory 242, and/or the like) may receive, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS, as described above. In some aspects, the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.

Process 700 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the UE is configured with a quantity of receive elements that is greater relative to a quantity of transmit elements with which the UE is configured. In a second aspect, alone or in combination with the first aspect, the CSI configuration identifies a CSI-RS resource set for the CSI-RS, and receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report for the CSI-RS resource set for the CSI-RS. In a third aspect, alone or in combination with one or more of the first and second aspects, the CSI configuration identifies a plurality of CSI-RS resource sets for the CSI-RS, and receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report for the plurality of the CSI-RS resource sets for the CSI-RS.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the CSI configuration identifies a plurality of CSI-RS resource sets for the CSI-RS, and receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report for a CSI-RS resource set of the plurality of the CSI-RS resource sets for the CSI-RS, wherein the CSI-RS resource set is indicated in the partial reciprocity explicit CSI report by a CSI-RS resource indicator. In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the CSI configuration identifies a CSI-RS resource set for the CSI-RS, and receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report based at least in part on the CSI-RS resource set for a CSI-RS.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the CSI configuration identifies at least one of one or more antenna ports for transmitting the partial reciprocity explicit CSI report, a frequency-domain compression parameter for the partial reciprocity explicit CSI report, a bandwidth of the CSI-RS for the partial reciprocity explicit CSI report, a transmission timing parameter for the partial reciprocity explicit CSI report, or a quantization parameter for the partial reciprocity explicit CSI report. In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the one or more antenna ports, is to be used for transmitting the uplink reference signal, and the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises a subset, of a full bandwidth of the CSI-RS, that is non-overlapping with a bandwidth for transmitting the uplink reference signal.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, receiving the partial reciprocity explicit CSI report comprises receiving, via the first antenna port of the one or more antenna ports, a first transmission of the partial reciprocity explicit CSI report using the subset of the full bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the uplink reference signal and receiving, via a second antenna port of the one or more antenna ports, a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS. In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, a first antenna port, of the one or more antenna ports, is to be used for transmitting the uplink reference signal, and the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises a full bandwidth of the CSI-RS.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, a first subset of the full bandwidth of the CSI-RS is non-overlapping with a bandwidth for transmitting the uplink reference signal, a second subset of the full bandwidth of the CSI-RS is overlapping with a bandwidth for transmitting the uplink reference signal, and receiving the partial reciprocity explicit CSI report comprises receiving a first portion of the partial reciprocity explicit CSI report using the first subset and receiving a second portion of the partial reciprocity explicit CSI report, using the second subset, with lower frequency granularity or quantization granularity relative to the first portion. In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted after transmission of the uplink reference signal, and the uplink reference signal is a most recent uplink reference signal that is transmitted prior to transmission of the partial reciprocity explicit CSI report.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report and the uplink reference signal are to be transmitted in a same slot as the CSI-RS, and the CSI-RS is transmitted prior to the partial reciprocity explicit CSI report and the uplink reference signal in the same slot. In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the CSI-RS is a non-precoded CSI-RS. In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, process 700 further comprises precoding the CSI-RS based at least in part on another uplink reference signal that was transmitted by the UE prior to transmission of the CSI-RS.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the uplink reference signal comprises an SRS, and the CSI configuration identifies at least one of one or more antenna ports for transmitting the SRS, an SRS resource for transmitting the SRS, or an SRS resource set for transmitting the SRS. In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, an antenna switching parameter of the CSI configuration indicates the UE is to determine an antenna port for transmitting the SRS, and receiving the SRS comprises receiving the SRS via the antenna port.

In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report via the antenna port. In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, the uplink reference signal comprises a DMRS, receiving the uplink reference signal comprises receiving the DMRS on a PUSCH, and receiving the partial reciprocity explicit CSI report comprises receiving the partial reciprocity explicit CSI report on the PUSCH. In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, transmitting the indication of the CSI configuration comprises transmitting the indication of the CSI configuration in at least one of an RRC communication, a MAC-CE communication, or a DCI communication.

Although Fig. 7 shows example blocks of process 700, in some aspects, process 700 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 7. Additionally, or alternatively, two or more of the blocks of process 700 may be performed in parallel.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. 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) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication performed by a user equipment (UE) , comprising:

transmitting, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) ; and

transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.
The method of claim 1, wherein the UE is configured with a quantity of receive elements that is greater relative to a quantity of transmit elements with which the UE is configured.
The method of claim 1, wherein the CSI configuration identifies:

a CSI-RS resource set for the CSI-RS; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report for the CSI-RS resource set for the CSI-RS.
The method of claim 1, wherein the CSI configuration identifies:

a plurality of CSI-RS resource sets for the CSI-RS; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report for the plurality of the CSI-RS resource sets for the CSI-RS.
The method of claim 1, wherein the CSI configuration identifies:

a plurality of CSI-RS resource sets for the CSI-RS; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report for a CSI-RS resource set of the plurality of the CSI-RS resource sets for the CSI-RS,

wherein the CSI-RS resource set is indicated in the partial reciprocity explicit CSI report by a CSI-RS resource indicator.
The method of claim 1, wherein the CSI configuration identifies:

a CSI-RS resource set for the CSI-RS; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report based at least in part on the CSI-RS resource set for a CSI-RS.
The method of claim 1, wherein the CSI configuration identifies at least one of:

one or more antenna ports for transmitting the partial reciprocity explicit CSI report,

a frequency-domain compression parameter for the partial reciprocity explicit CSI report,

a bandwidth of the CSI-RS for the partial reciprocity explicit CSI report,

a transmission timing parameter for the partial reciprocity explicit CSI report, or

a quantization parameter for the partial reciprocity explicit CSI report.
The method of claim 7, wherein the one or more antenna ports are to be used for transmitting the uplink reference signal; and

wherein the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises:

a subset, of a full bandwidth of the CSI-RS, that is non-overlapping with a bandwidth for transmitting the uplink reference signal.
The method of claim 8, wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting, via a first antenna port of the one or more antenna ports, a first transmission of the partial reciprocity explicit CSI report using the subset of the full bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the uplink reference signal; and

transmitting, via a second antenna port of the one or more antenna ports, a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS.
The method of claim 7, wherein a first antenna port, of the one or more antenna ports, is to be used for transmitting the uplink reference signal; and

wherein the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises:

a full bandwidth of the CSI-RS.
The method of claim 10, wherein a first subset of the full bandwidth of the CSI-RS is non-overlapping with a bandwidth for transmitting the uplink reference signal;

wherein a second subset of the full bandwidth of the CSI-RS is overlapping with a bandwidth for transmitting the uplink reference signal; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting a first portion of the partial reciprocity explicit CSI report using the first subset; and

transmitting a second portion of the partial reciprocity explicit CSI report, using the second subset, with lower frequency granularity or quantization granularity relative to the first portion.
The method of claim 7, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted after transmission of the uplink reference signal,

wherein the uplink reference signal is a most recent uplink reference signal that is transmitted prior to transmission of the partial reciprocity explicit CSI report.
The method of claim 7, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted prior to transmission of the uplink reference signal,

wherein the uplink reference signal is a most recent uplink reference signal that is transmitted after transmission of the partial reciprocity explicit CSI report.
The method of claim 7, wherein the transmission timing parameter for the partial reciprocity explicit CSI report specifies that the uplink reference signal is to be associated with the partial reciprocity explicit CSI report.
The method of claim 7, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report and the uplink reference signal are to be transmitted in a same slot as the CSI-RS,

wherein the CSI-RS is transmitted prior to the partial reciprocity explicit CSI report and the uplink reference signal in the same slot.
The method of claim 15, wherein the CSI-RS is a non-precoded CSI-RS.
The method of claim 15, wherein the CSI-RS is a precoded CSI-RS that is precoded based at least in part on another uplink reference signal that was transmitted by the UE prior to transmission of the precoded CSI-RS.
The method of claim 1, wherein the uplink reference signal comprises:

a sounding reference signal (SRS) ; and

wherein the CSI configuration identifies at least one of:

one or more antenna ports for transmitting the SRS,

an SRS resource for transmitting the SRS, or

an SRS resource set for transmitting the SRS.
The method of claim 18, wherein an antenna switching parameter of the CSI configuration indicates the UE is to determine an antenna port for transmitting the SRS; and

wherein transmitting the SRS comprises:

identifying the antenna port based at least in part on the CSI-RS; and

transmitting the SRS via the antenna port.
The method of claim 19, wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report via the antenna port.
The method of claim 1, wherein the uplink reference signal comprises:

a demodulation reference signal (DMRS) ;

wherein transmitting the uplink reference signal comprises:

transmitting the DMRS on a physical uplink shared channel (PUSCH) ; and

wherein transmitting the partial reciprocity explicit CSI report comprises:

transmitting the partial reciprocity explicit CSI report on the PUSCH.
The method of claim 1, further comprising:

receiving an indication of the CSI configuration in at least one of:

a radio resource control communication,

a medium access control control element communication, or

a downlink control information communication.
A method of wireless communication performed by a base station (BS) , comprising:

transmitting, to a user equipment (UE) , an indication of a channel state information (CSI) configuration;

transmitting, to the UE, a CSI reference signal (CSI-RS) ; and

receiving, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS,

wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.
The method of claim 23, wherein the UE is configured with a quantity of receive elements that is greater relative to a quantity of transmit elements with which the UE is configured.
The method of claim 23, wherein the CSI configuration identifies:

a CSI-RS resource set for the CSI-RS; and

wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report for the CSI-RS resource set for the CSI-RS.
The method of claim 23, wherein the CSI configuration identifies:

a plurality of CSI-RS resource sets for the CSI-RS; and

wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report for the plurality of the CSI-RS resource sets for the CSI-RS.
The method of claim 23, wherein the CSI configuration identifies:

a plurality of CSI-RS resource sets for the CSI-RS; and

wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report for a CSI-RS resource set of the plurality of the CSI-RS resource sets for the CSI-RS,

wherein the CSI-RS resource set is indicated in the partial reciprocity explicit CSI report by a CSI-RS resource indicator.
The method of claim 23, wherein the CSI configuration identifies:

a CSI-RS resource set for the CSI-RS; and

wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report based at least in part on the CSI-RS resource set for a CSI-RS.
The method of claim 23, wherein the CSI configuration identifies at least one of:

one or more antenna ports for transmitting the partial reciprocity explicit CSI report,

a frequency-domain compression parameter for the partial reciprocity explicit CSI report,

a bandwidth of the CSI-RS for the partial reciprocity explicit CSI report,

a transmission timing parameter for the partial reciprocity explicit CSI report, or

a quantization parameter for the partial reciprocity explicit CSI report.
The method of claim 29, wherein the one or more antenna ports are to be used for transmitting the uplink reference signal; and

wherein the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises:

a subset, of a full bandwidth of the CSI-RS, that is non-overlapping with a bandwidth for transmitting the uplink reference signal.
The method of claim 30, wherein receiving the partial reciprocity explicit CSI report comprises:

receiving, via the first antenna port of the one or more antenna ports, a first transmission of the partial reciprocity explicit CSI report using the subset of the full bandwidth of the CSI-RS that is non-overlapping with the bandwidth for transmitting the uplink reference signal; and

receiving, via a second antenna port of the one or more antenna ports, a second transmission of the partial reciprocity explicit CSI report using the full bandwidth of the CSI-RS.
The method of claim 29, wherein a first antenna port, of the one or more antenna ports, is to be used for transmitting the uplink reference signal; and

wherein the bandwidth of the CSI-RS for the partial reciprocity explicit CSI report comprises:

a full bandwidth of the CSI-RS.
The method of claim 32, wherein a first subset of the full bandwidth of the CSI-RS is non-overlapping with a bandwidth for transmitting the uplink reference signal;

wherein a second subset of the full bandwidth of the CSI-RS is overlapping with a bandwidth for transmitting the uplink reference signal; and

wherein receiving the partial reciprocity explicit CSI report comprises:

receiving a first portion of the partial reciprocity explicit CSI report using the first subset; and

receiving a second portion of the partial reciprocity explicit CSI report, using the second subset, with lower frequency granularity or quantization granularity relative to the first portion.
The method of claim 29, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted after transmission of the uplink reference signal,

wherein the uplink reference signal is a most recent uplink reference signal that is transmitted prior to transmission of the partial reciprocity explicit CSI report.
The method of claim 29, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report is to be transmitted prior to transmission of the uplink reference signal,

wherein the uplink reference signal is a most recent uplink reference signal that is transmitted after transmission of the partial reciprocity explicit CSI report.
The method of claim 29, wherein the transmission timing parameter for the partial reciprocity explicit CSI report specifies that the uplink reference signal is to be associated with the partial reciprocity explicit CSI report.
The method of claim 29, wherein the transmission timing parameter for the partial reciprocity explicit CSI report indicates that the partial reciprocity explicit CSI report and the uplink reference signal are to be transmitted in a same slot as the CSI-RS,

wherein the CSI-RS is transmitted prior to the partial reciprocity explicit CSI report and the uplink reference signal in the same slot.
The method of claim 37, wherein the CSI-RS is a non-precoded CSI-RS.
The method of claim 37, further comprising:

precoding the CSI-RS based at least in part on another uplink reference signal that was transmitted by the UE prior to transmission of the CSI-RS.
The method of claim 23, wherein the uplink reference signal comprises:

a sounding reference signal (SRS) ; and

wherein the CSI configuration identifies at least one of:

one or more antenna ports for transmitting the SRS,

an SRS resource for transmitting the SRS, or

an SRS resource set for transmitting the SRS.
The method of claim 40, wherein an antenna switching parameter of the CSI configuration indicates the UE is to determine an antenna port for transmitting the SRS; and

wherein receiving the SRS comprises:

receiving the SRS via the antenna port.
The method of claim 41, wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report via the antenna port.
The method of claim 23, wherein the uplink reference signal comprises:

a demodulation reference signal (DMRS) ;

wherein receiving the uplink reference signal comprises:

receiving the DMRS on a physical uplink shared channel (PUSCH) ; and wherein receiving the partial reciprocity explicit CSI report comprises:

receiving the partial reciprocity explicit CSI report on the PUSCH.
The method of claim 23, wherein transmitting the indication of the CSI configuration comprises:

transmitting the indication of the CSI configuration in at least one of:

a radio resource control communication,

a medium access control control element communication, or

a downlink control information communication.
A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

transmit, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) ; and

transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.
A base station (BS) for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

transmit, to a user equipment (UE) , an indication of a channel state information (CSI) configuration;

transmit, to the UE, a CSI reference signal (CSI-RS) ; and

receive, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS,

wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment (UE) , cause the one or more processors to:

transmit, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) ; and

transmit, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a base station (BS) , cause the one or more processors to:

transmit, to a user equipment (UE) , an indication of a channel state information (CSI) configuration;

transmit, to the UE, a CSI reference signal (CSI-RS) ; and

receive, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS,

wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.
An apparatus for wireless communication, comprising:

means for transmitting, based at least in part on a channel state information (CSI) configuration, an uplink reference signal associated with a CSI reference signal (CSI-RS) ; and

means for transmitting, based at least in part on the CSI configuration, a partial reciprocity explicit CSI report associated with the CSI-RS.
An apparatus for wireless communication, comprising:

means for transmitting, to a user equipment (UE) , an indication of a channel state information (CSI) configuration;

means for transmitting, to the UE, a CSI reference signal (CSI-RS) ; and

means for receiving, from the UE, an uplink reference signal and a partial reciprocity explicit CSI report that are associated with the CSI-RS,

wherein the uplink reference signal and the partial reciprocity explicit CSI report are based at least in part on the CSI configuration.