WO2020164039A1

WO2020164039A1 - Signaling support for differential csi reporting

Info

Publication number: WO2020164039A1
Application number: PCT/CN2019/075042
Authority: WO
Inventors: Yuwei REN; Yu Zhang; Liangming WU; Bo Chen; Renqiu Wang; Ruifeng MA; Hao Xu; Chenxi HAO; Tingfang Ji
Original assignee: Qualcomm Incorporated
Priority date: 2019-02-14
Filing date: 2019-02-14
Publication date: 2020-08-20
Also published as: WO2020164462A1

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, after receiving a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The UE may reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication. Numerous other aspects are provided.

Description

SIGNALING SUPPORT FOR DIFFERENTIAL CSI REPORTING

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication, and more particularly to techniques and apparatuses for signaling support for differential channel state information (CSI) reporting.

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 (for example, bandwidth, transmit power, or the like, or a combination thereof) . 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) .

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments (UEs) 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 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 or SC-FDM (for example, 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.

In some cases, a BS may transmit one or more reference signals to a UE. The UE may perform one or more measurements based at least in part on the one or more reference signals, and may provide a feedback report that is based at least in part on the one or more measurements. In some cases, the one or more reference signals may include a channel state information (CSI) reference signal (CSI-RS) , a demodulation reference signal (DMRS) , or the like, or a combination thereof. The UE may transmit the feedback report, such as a CSI feedback report, based at least in part on receiving an instruction to transmit the feedback report, based at least in part on a feedback reporting schedule, or the like, or a combination thereof.

Some wireless networks (for example, an LTE wireless network, a 5G NR wireless network, etc. ) may support advanced CSI reporting in cases where legacy CSI reporting is insufficient to reflect channel information between a BS and a UE. Legacy CSI reporting, for example, generally assumes that a precoding matrix indicator (PMI) is constructed from a single beam, and thus may be insufficient for reflecting the channel information at larger antenna arrays (for example, for MIMO communications) . Advanced CSI reporting can increase CSI feedback reporting accuracy by combining multiple beams, such as discrete Fourier transform (DFT) beams, in the PMI. However, advanced CSI reporting may also increase feedback overhead and UE processing complexity.

SUMMARY

In some aspects, a method of wireless communication, performed by a user equipment (UE) , may include receiving, after receiving a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The method may include resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.

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 receive, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The memory and the one or more processors may be configured to reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.

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 receive, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.

In some aspects, an apparatus for wireless communication may include means for receiving, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The apparatus may include means for resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.

In some aspects, a method of wireless communication, performed by a base station (BS) , may include transmitting, to a UE, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure transmitting, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and receiving, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.

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, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure transmit, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and receive, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.

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, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure transmit, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and receive, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.

In some aspects, an apparatus for wireless communication may include means for transmitting, to a UE, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure means for transmitting, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and means for receiving, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and 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 in accordance with 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.

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

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

Figure 3A is a block diagram illustrating an example frame structure for use in a wireless network in accordance with various aspects of the present disclosure.

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

Figure 4 is a block diagram illustrating an example slot format in accordance with various aspects of the present disclosure.

Figure 5 illustrates an example logical architecture of a distributed radio access network (RAN) in accordance with various aspects of the present disclosure.

Figure 6 illustrates an example physical architecture of a distributed RAN in accordance with various aspects of the present disclosure.

Figure 7 is a diagram showing an example downlink (DL) -centric slot or communication structure in accordance with various aspects of the present disclosure.

Figure 8 is a diagram showing an example uplink (UL) -centric slot or communication structure in accordance with various aspects of the present disclosure.

Figures 9A-9D are diagrams illustrating an example of signaling support for differential channel state information (CSI) reporting in accordance with various aspects of the present disclosure.

Figures 10A-10C are diagrams illustrating various techniques for resetting a differential CSI feedback reporting procedure in accordance with various aspects of the present disclosure.

Figure 11 is a diagram illustrating an example process performed by a UE in accordance with various aspects of the present disclosure.

Figure 12 is a diagram illustrating an example process performed 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 implemented 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 a person having ordinary skill in the art. Based on the teachings herein, a person having ordinary skill 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 implemented 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, or the like, or a combination thereof (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 is noted that while aspects may be described herein using terminology commonly associated with 3G or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including New Radio (NR) technologies.

As explained above, advanced channel state information (CSI) reporting can increase CSI feedback reporting accuracy but may also increase CSI feedback reporting overhead and user equipment (UE) processing complexity. Some aspects of the present disclosure described herein provide techniques and apparatuses for signaling support for differential CSI reporting. In some aspects, a UE may receive, from a base station (BS) , a first communication that includes a first indication to activate a differential CSI feedback reporting procedure. After receiving the first communication, the UE may receive, from the BS, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The UE may reset the differential CSI feedback reporting procedure based at least in part on receiving the second communication while the differential CSI feedback reporting procedure is already activated. The UE may be configured to determine a slot in which to reset the differential CSI feedback reporting procedure (that is, in which to transmit a new base CSI feedback report) . The UE may be configured to determine the slot based at least in part on the first communication or the second communication.

In this way, the BS may be capable of instructing the UE to reset the differential CSI feedback reporting procedure, and UE may be capable of resetting the differential CSI feedback reporting procedure and determining the slot in which to reset the differential CSI feedback reporting procedure. As a result, the UE may reset the differential CSI feedback reporting procedure in order to correct issues with the differential CSI feedback reporting procedure (such as providing inaccurate CSI feedback based at least in part on fading, multipathing, or other environmental or network phenomena) , in order to modify one or more parameters for the differential CSI feedback reporting procedure, or the like, or a combination thereof, without having to deactivate the differential CSI feedback reporting procedure. This improves the accuracy of the differential CSI feedback reporting procedure, decreases the amount of time that the differential CSI feedback reporting procedure is not active, decreases the amount of signaling required to reset the differential CSI feedback reporting procedure, and the like.

Figure 1 is a block diagram illustrating an example wireless network 100 in accordance with various aspects of the present disclosure. The wireless network 100 may be a Long Term Evolution (LTE) network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a number of base stations (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 (UE (s)) via a downlink and an 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. A BS and may also be referred to as a Node B, an eNodeB, an eNB, a gNB, a NR BS, a 5G node B, an access point (AP) , a transmit receive point (TRP) , or the like, or a combination thereof (these terms are used interchangeably herein) . 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 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, or another type of cell. A macro cell may cover a relatively large geographic area (for example, 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 (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, 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. A BS may support one or multiple (for example, three) cells.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, for example, macro BSs, pico BSs, femto BSs, relay BSs, or the like, or a combination thereof. 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 (for example, 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, 0.1 to 2 Watts) . In the example shown in Figure 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 network controller 130 may couple to the set of

BSs

102a, 102b, 110a and 110b, 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, for example, directly or indirectly via a wireless or wireline backhaul.

In some aspects, a cell may not necessarily be stationary, rather, the geographic area of the cell may move in accordance with the location of a mobile BS. In some aspects, the BSs may be interconnected to one another 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, or the like, or a combination thereof 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 (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, 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 Figure 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, or the like, or a combination thereof.

UEs 120 (for example, 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, or the like, or a combination thereof. A UE may be a cellular phone (for example, 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 (for example, smart ring, smart bracelet) ) , an entertainment device (for example, 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 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, or the like, or a combination thereof, that may communicate with a base station, another device (for example, remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, 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, 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, or the like, or a combination thereof.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies or frequency channels. A frequency may also be referred to as a carrier or the like, or a combination thereof. 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 (for example, shown as UE 120a and UE 120e) may communicate directly with one another using one or more sidelink channels (for example, without using a base station 110 as an intermediary) . For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (for example, which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or the like, or a combination thereof) , a mesh network, or the like, or a combination thereof. In this case, the UE 120 may perform scheduling operations, resource selection operations, or other operations described elsewhere herein as being performed by the base station 110.

Figure 2 is a block diagram 200 illustrating an example base station (BS) in communication with a user equipment (UE) in a wireless network in accordance with various aspects of the present disclosure. 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 (MCSs) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (for example, encode) 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 (for example, for semi-static resource partitioning information (SRPI) or the like, or a combination thereof) and control information (for example, CQI requests, grants, upper layer signaling, or the like, or a combination thereof) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS) ) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD 232 may process a respective output symbol stream (for example, for OFDM or the like, or a combination thereof) to obtain an output sample stream. Each MOD 232 may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from MODs 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. In accordance with 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 or other base stations and may provide received signals to R demodulators (DEMODs) 254a through 254r, respectively. Each DEMOD 254 may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each DEMOD 254 may further process the input samples (for example, for OFDM or the like, or a combination thereof) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R DEMODs 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (for example, 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 a reference signal received power (RSRP) , a received signal strength indicator (RSSI) , a reference signal received quality (RSRQ) , a channel quality indicator (CQI) , or the like, or a combination thereof. 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 as well as control information (for example, for reports including RSRP, RSSI, RSRQ, CQI, or the like, or a combination thereof) 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 MODs 254a through 254r (for example, for discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) , orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) , or the like, or a combination thereof) , 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 DEMODs 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, or any other component (s) of Figure 2 may perform one or more techniques associated with signaling support for differential CSI reporting, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE 120, or any other component (s) of Figure 2 may perform or direct operations of, for example, process 1100 of Figure 11, process 1200 of Figure 12, or other processes as described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink or uplink.

In some aspects, UE 120 may include means for receiving, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure, means for resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication, or the like, or a combination thereof. In some aspects, such means may include one or more components of UE 120 described in connection with Figure 2.

In some aspects, base station 110 may include means for transmitting, to a UE 120, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, means for transmitting, to the UE 120, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure, means for receiving, from the UE 120 based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication, or the like, or a combination thereof. In some aspects, such means may include one or more components of base station 110 described in connection with Figure 2.

Figure 3A is a block diagram illustrating an example frame structure 300 for use in a wireless network in accordance with various aspects of the present disclosure. For example, frame structure 300 may be used for frequency division duplexing (FDD) in a telecommunications system (for example, NR) . The transmission timeline for each of the downlink and uplink directions may be partitioned into units of radio frames (sometimes referred to simply as “frames” ) . Each radio frame may have a predetermined duration (for example, 10 milliseconds (ms) ) and may be partitioned into a set of Z (Z ≥ 1) subframes (for example, with indices of 0 through Z-1) . Each subframe may have a predetermined duration (for example, 1ms) and may include a set of slots (for example, 2 ^m slots per subframe are shown in Figure 3A, where m is numerology used for a transmission, such as 0, 1, 2, 3, 4, or the like, or a combination thereof) . Each slot may include a set of i symbol periods. For example, each slot may include fourteen symbol periods (for example, as shown in Figure 3A) , seven symbol periods, or another number of symbol periods. In a case where the subframe includes two slots (for example, 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, or the like, or a combination thereof.

While some techniques are described herein in connection with frames, subframes, slots, or the like, or a combination thereof, these techniques may equally apply to other types of wireless communication structures, which may be referred to using terms other than “frame, ” “subframe, ” “slot, ” or the like, or a combination thereof 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 or protocol. Additionally or alternatively, different configurations of wireless communication structures than those shown in Figure 3A may be used.

In certain telecommunications (for example, 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) , or the like, or a combination thereof, 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, a base station may transmit a PBCH such that the PBCH occupies the space above and below the SSS. In this case, the SSS and PBCH may form a three-OFDM-symbol rectangular grid.

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

Figure 3B is a block diagram illustrating an example synchronization communication hierarchy for use in a wireless communication network in accordance with various aspects of the present disclosure. The SS hierarchy, which is an example of a synchronization communication hierarchy. As shown in Figure 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_pp-1}) , where b _{max_pp-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 Figure 3B. In some aspects, an SS burst set may have a fixed or dynamic length, shown as Y milliseconds in Figure 3B.

The SS burst set shown in Figure 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 Figure 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, or other synchronization signals (for example, a tertiary synchronization signal (TSS) ) or synchronization channels. In some aspects, multiple SS blocks are included in an SS burst, and the PSS, the SSS, 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 (for example, occupying one symbol) , the SSS (for example, occupying one symbol) , or the PBCH (for example, occupying two symbols) .

In some aspects, the symbols of an SS block are consecutive, as shown in Figure 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 (for example, 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 during which the SS blocks of the SS burst are transmitted by the base station in accordance with 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, and the SS bursts of the SS burst set are transmitted by the base station in accordance with 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 C may be configurable for each slot. The base station may transmit traffic data or other data on the PDSCH in the remaining symbol periods of each slot.

Figure 4 is a block diagram 400 conceptually illustrating an example slot format 410 in accordance with various aspects of the present disclosure. The available time frequency resources may be partitioned into resource blocks. Each resource block may cover a set of subcarriers (for example, 12 subcarriers) in one slot and may include a number of resource elements. Each resource element may cover one subcarrier in one symbol period (for example, 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 (for example, 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, or the like, or a combination thereof. Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR) , 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 in accordance with a new air interface (for example, other than Orthogonal Frequency Divisional Multiple Access (OFDMA) -based air interfaces) or fixed transport layer (for example, other than Internet Protocol (IP) ) . In aspects, NR may utilize OFDM with a cyclic prefix (CP) (herein referred to as cyclic prefix OFDM or CP-OFDM) 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) or 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 (for example, 80 megahertz (MHz) and beyond) , millimeter wave (mmW) targeting high carrier frequency (for example, 60 gigahertz (GHz) ) , massive MTC (mMTC) targeting non-backward compatible MTC techniques, 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 (for example, for example, downlink (DL) or uplink (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. 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 central units or distributed units.

Figure 5 illustrates an example logical architecture of a distributed radio access network (RAN) 500, in accordance with various aspects of the present disclosure. A 5G access node 506 may include an access node controller (ANC) 502. The ANC may be a central unit (CU) of the distributed RAN 500. The backhaul interface to the next generation core network (NG-CN) 504 may terminate at the ANC. The backhaul interface to neighboring next generation access nodes (NG-ANs) 510 may terminate at the ANC. The ANC may include one or more TRPs 508 (which may also be referred to as BSs, NR BSs, Node Bs, 5G NBs, APs, gNB, or some other term) . As described above, a TRP may be used interchangeably with “cell. ”

The TRPs 508 may be a distributed unit (DU) . The TRPs may be connected to one ANC (ANC 502) or more than one ANC (not illustrated) . For example, for RAN sharing, radio as a service (RaaS) , and service specific AND deployments, the TRP may be connected to more than one ANC. A TRP may include one or more antenna ports. The TRPs may be configured to individually (for example, dynamic selection) or jointly (for example, joint transmission) serve traffic to a UE.

The local architecture of RAN 500 may be used to support fronthaul definition. The architecture may be defined to support fronthauling solutions across different deployment types. For example, the architecture may be based at least in part on transmit network capabilities (for example, bandwidth, latency, or jitter) .

The architecture may share features or components with LTE. In accordance with aspects, NG-AN 510 may support dual connectivity with NR. NG-AN 510 may share a common fronthaul for LTE and NR.

The architecture may enable cooperation between and among TRPs 508. For example, cooperation may be preset within a TRP or across TRPs via the ANC 502. In accordance with aspects, no inter-TRP interface may be needed/present.

In accordance with aspects, a dynamic configuration of split logical functions may be present within the architecture of RAN 500. The packet data convergence protocol (PDCP) , radio link control (RLC) , and MAC protocol layers may be adaptably placed at the ANC or TRP.

Figure 6 illustrates an example physical architecture of a distributed RAN 600 in accordance with various aspects of the present disclosure. A centralized core network unit (C-CU) 602 may host core network functions. The C-CU may be centrally deployed. C-CU functionality may be offloaded (for example, to advanced wireless services (AWS) ) , in an effort to handle peak capacity. A centralized RAN unit (C-RU) 604 may host one or more ANC functions. Optionally, the C-RU may host core network functions locally. The C-RU may have distributed deployment. The C-RU may be closer to the network edge. A distributed unit (DU) 606 may host one or more TRPs. The DU may be located at edges of the network with radio frequency (RF) functionality.

Figure 7 is a diagram showing an example downlink (DL) -centric slot 700 or communication structure in accordance with various aspects of the present disclosure. The DL-centric slot (or wireless communication structure) may include a control portion 702 during which the scheduling entity (for example, UE or BS) transmits various scheduling information or control information corresponding to various portions of the DL-centric slot to the subordinate entity (for example, UE) . The control portion 702 may exist in the initial or beginning portion of the DL-centric slot. In some configurations, the control portion 702 may be a physical DL control channel PDCCH, as indicated in Figure 7. In some aspects, the control portion 702 may include legacy PDCCH information, shortened PDCCH (sPDCCH) information) , a control format indicator (CFI) value (for example, carried on a physical control format indicator channel (PCFICH) ) , one or more grants (for example, downlink grants, uplink grants, or the like, or a combination thereof) , or the like, or a combination thereof.

The DL-centric slot may also include a DL data portion 704 during which the scheduling entity (for example, UE or BS) transmits DL data to the subordinate entity (for example, UE) using communication resources utilized to communicate DL data. The DL data portion 704 may sometimes be referred to as the payload of the DL-centric slot. In some configurations, the DL data portion 704 may be a PDSCH.

The DL-centric slot may also include an UL short burst portion 706 during which the subordinate entity (for example, UE) transmits reference signals or feedback to the scheduling entity (for example, UE or BS) using communication resources utilized to communicate UL data. The UL short burst portion 706 may sometimes be referred to as an UL burst, an UL burst portion, a common UL burst, a short burst, an UL short burst, a common UL short burst, a common UL short burst portion, or various other suitable terms. In some aspects, the UL short burst portion 706 may include one or more reference signals. Additionally or alternatively, the UL short burst portion 706 may include feedback information corresponding to various other portions of the DL-centric slot. For example, the UL short burst portion 706 may include feedback information corresponding to the control portion 702 or the data portion 704. Non-limiting examples of information that may be included in the UL short burst portion 706 include an acknowledgement (ACK) signal (for example, a physical uplink control channel (PUCCH) ACK, a physical uplink shared channel (PUSCH) ACK, or an immediate ACK) , a negative acknowledgement (NACK) signal (for example, a PUCCH NACK, a PUSCH NACK, or an immediate NACK) , a scheduling request (SR) , a buffer status report (BSR) , a hybrid automatic repeat request (HARQ) indicator, a channel state indication (CSI) , a channel quality indicator (CQI) , a sounding reference signal (SRS) , a demodulation reference signal (DMRS) , PUSCH data, or various other suitable types of information. The UL short burst portion 706 may include additional or alternative information, such as information pertaining to RACH procedures, scheduling requests, and various other suitable types of information.

As illustrated in Figure 7, the end of the DL data portion 704 may be separated in time from the beginning of the UL short burst portion 706. This time separation may sometimes be referred to as a gap, a guard period, a guard interval, or various other suitable terms. This separation provides time for the switch-over from DL communication (for example, reception operation by the subordinate entity (for example, BS or UE) ) to UL communication (for example, transmission by the subordinate entity (for example, UE) ) . The foregoing provides some examples of a DL-centric wireless communication structure, but alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

Figure 8 is a diagram showing an example uplink (UL) -centric slot 800 or communication structure in accordance with various aspects of the present disclosure. The UL-centric slot (or wireless communication structure) may include a control portion 802. The control portion 802 may exist in the initial or beginning portion of the UL-centric slot. The control portion 802 in Figure 8 may be similar to the control portion 702 described above with reference to Figure 7. The UL-centric slot may also include an UL long burst portion 804. The UL long burst portion 804 may sometimes be referred to as the payload of the UL-centric slot. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (for example, UE) to the scheduling entity (for example, UE or BS) . In some configurations, the control portion 802 may be a physical DL control channel PDCCH.

As illustrated in Figure 8, the end of the control portion 802 may be separated in time from the beginning of the UL long burst portion 804. This time separation may sometimes be referred to as a gap, guard period, guard interval, or various other suitable terms. This separation provides time for the switch-over from DL communication (for example, reception operation by the scheduling entity) to UL communication (for example, transmission operation by the scheduling entity) .

The UL-centric slot may also include an UL short burst portion 806. The UL short burst portion 806 in Figure 8 may be similar to the UL short burst portion 706 described above with reference to Figure 7, and may include any of the information described above in connection with Figure 7. The foregoing is merely one example of an UL-centric wireless communication structure, and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

In some circumstances, two or more subordinate entities (for example, UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, V2V communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (for example, UE1) to another subordinate entity (for example, UE2) without relaying that communication through the scheduling entity (for example, UE or BS) , even though the scheduling entity may be utilized for scheduling or control purposes. In some aspects, the sidelink signals may be communicated using a licensed spectrum band; in other aspects, the sidelink signals may be communicated using an unlicensed spectrum band.

In one example, a wireless communication structure, such as a frame, may include both UL-centric slots and DL-centric slots. In this example, the ratio of UL-centric slots to DL-centric slots in a frame may be dynamically adjusted based at least in part on the amount of UL data and the amount of DL data that are transmitted. For example, if there is more UL data, then the ratio of UL-centric slots to DL-centric slots may be increased. Conversely, if there is more DL data, then the ratio of UL-centric slots to DL-centric slots may be decreased.

As explained above, advanced CSI reporting can increase CSI feedback reporting accuracy but may also increase CSI feedback reporting overhead and UE processing complexity. Some aspects of the present disclosure described herein provide techniques and apparatuses for differential CSI feedback reporting, which can provide high-resolution CSI feedback while reducing per-feedback report overhead associated with advanced CSI reporting. For example, using techniques presented herein, a UE may receive respective reference signals (such as a CSI reference signal (CSI-RS) or another type of reference signal) , from a BS, on a plurality of beams (such as discreet Fourier transform (DFT) beams) . The UE may select a subset of beams based at least in part on the respective reference signals and may generate a base CSI feedback report based at least in part on subset of beams. The base CSI feedback report may be an initial or low-resolution CSI feedback report. The UE may transmit the base CSI feedback report to the BS in a first slot. The UE may then generate one or more differential (or incremental) CSI feedback reports based at least in part on the respective reference signals transmitted using the subset of beams, and may transmit the one or more differential CSI feedback reports to the BS in one or more subsequent slots. To reduce CSI feedback reporting overhead, the one or more differential CSI feedback reports may indicate changes to the complete CSI feedback that was indicated in the base CSI feedback report instead of including complete CSI feedback. In this way, the differential CSI feedback reports may be used to fine-tune and increase the resolution of the base CSI feedback report.

In this way, the UE may be capable of providing a base CSI feedback report, which includes complete CSI feedback (for example, a rank indicator (RI) , a precoding matrix indicator (PMI) , an indication of a selection of one or more beams transmitted by the BS, phase information associated with the one or more beams, amplitude information associated with the one or more beams, etc. ) , and one or more differential CSI feedback reports, which fine tune the complete CSI feedback indicated in the base CSI feedback report. Since the one or more differential CSI feedback reports do not include complete CSI feedback and, instead, indicate changes to the complete CSI feedback indicated in the base CSI feedback report, the one or more differential CSI feedback reports may be relatively smaller than the base CSI feedback report, and may therefore reduce CSI feedback reporting overhead while providing increased CSI feedback resolution.

Moreover, in some aspects, the UE may receive, from a BS, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure. After receiving the first communication, the UE may receive, from the BS, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure. The UE may reset the differential CSI feedback reporting procedure based at least in part on receiving the second communication while the differential CSI feedback reporting procedure is already activated. The UE may be configured to determine a slot in which to reset the differential CSI feedback reporting procedure (that is, in which to transmit a new base CSI feedback report) . The UE may be configured to determine the slot based at least in part on the first communication or the second communication.

Figures 9A-9D are diagrams 900 illustrating an example of signaling support for differential CSI reporting in accordance with various aspects of the present disclosure. As shown in Figures 9A-9D, the example may include communications between a user equipment (for example, UE 120) and a base station (for example, BS 110) . In some aspects, BS 110 and UE 120 may be included in a wireless network (for example, wireless network 100) .

In some aspects, BS 110 may communicate with UE 120 on a downlink of a wireless communication link between BS 110 and UE 120. In some aspects, UE 120 may perform one or more measurements of the downlink and may provide a feedback report, such as a CSI feedback report, to BS 110 based at least in part on the one or more measurements. UE 120 may perform the one or more measurements based on a reference signal transmitted from BS 110. The reference signal may include, for example, a CSI-RS, a DMRS, or the like, or a combination thereof. BS 110 may use the information included in the CSI feedback report to perform beam selection, to adjust phasing of the selected beams, to adjust amplitudes of the selected beams, or the like, or a combination thereof.

In some aspects, UE 120 may transmit a plurality of CSI feedback reports based at least in part on a differential CSI feedback reporting procedure. The differential CSI feedback reporting procedure may configure UE 120 to transmit a base CSI feedback report and one or more differential CSI reports in a particular reporting period and at a particular reporting interval. The reporting period may indicate the quantity of differential CSI feedback reports that are to be transmitted during the reporting period. The reporting interval may indicate a spacing (for example, in slots, in symbols, or the like, or a combination thereof) between CSI feedback reports in a reporting period.

UE 120 may be configured to generate and transmit the base CSI feedback report in a slot at the beginning of the reporting period. UE 120 may include, in the base CSI feedback report, complete CSI feedback based at least in part on the one or more measurements that are performed based at least in part on the reference signal transmitted from BS 110. The complete CSI feedback may include an indication of a selection of one or more beams transmitted from BS 110, an RI, a PMI, one or more coefficients corresponding to a phase shift associated with the one or more beams, one or more coefficients corresponding to an amplitude associated with the one or more beams, or the like, or a combination thereof. In some aspects, the base CSI feedback report may be a wideband base CSI feedback report in that the base CSI feedback report includes feedback for an entire bandwidth of the downlink. In some aspects, the base CSI feedback report may be a sub-band base CSI feedback report for a sub-band of a plurality of sub-bands of the downlink. In this case, UE 120 may generate and transmit respective sub-band base CSI feedback reports for each sub-band of the downlink.

UE 120 may be configured to generate and transmit the one or more differential CSI feedback reports in subsequent slots in the reporting period and at the particular reporting interval. For example, UE 120 may transmit a first differential CSI feedback report in a slot that is one or more slots after the slot in which the base CSI feedback report was transmitted, may transmit a second differential CSI feedback report in a slot that is one or more slots after the slot in which the first differential CSI feedback report was transmitted, and so on. Each differential CSI feedback report may include differential or incremental CSI feedback based at least in part on the complete CSI feedback indicated in the base CSI feedback report.

To generate the differential CSI feedback, UE 120 may perform one or more additional measurements of the reference signal, and may indicate, in the differential CSI feedback report, any changes to the complete CSI feedback. The differential CSI feedback may indicate, for example, a change in amplitude of the one or more selected beams, a change in phase shift of the one or more selected beams, or the like, or a combination thereof. In some aspects, differential CSI feedback, included in a differential CSI feedback report, may be indicated relative to the complete CSI feedback included in the base CSI feedback report. In some aspects, differential CSI feedback, included in a differential CSI feedback report, may be indicated relative to differential CSI feedback indicated in a previous differential CSI feedback report.

As shown in Figure 9A, in a first operation 902, BS 110 may activate a differential CSI feedback reporting procedure at UE 120 by transmitting a first communication to UE 120. The first communication may include a radio resource control (RRC) communication, a downlink control information (DCI) communication, or the like. BS 110 may transmit the first communication on a PDSCH, a PBCH or another type of physical channel.

In some aspects, the first communication may include an indication that UE 120 is to activate the differential CSI feedback reporting procedure. The indication may include, for example, a flag, a value included in one or more fields, or the like, or a combination thereof, included in the first communication.

As shown in Figure 9B, in a second operation 904, UE 120 may activate the differential CSI feedback reporting procedure based at least in part on receiving the first communication. For example, UE 120 may generate and transmit a base CSI feedback report ( “B” ) in slot 1, may generate and transmit one or more differential CSI feedback reports ( “D” ) in subsequent slots (for example, slot 3 and slot 5) , and so on. UE 120 may transmit CSI feedback reports in subsequent reporting periods in a similar manner.

As further shown in Figure 9B, UE 120 may transmit a base CSI feedback report and two differential CSI feedback reports in a reporting period. The reporting interval between CSI feedback reports in a reporting period may be one slot. Further, UE 120 may transmit sub-band CSI feedback across a plurality of sub-bands. It is to be noted that the differential CSI feedback reporting procedure configuration illustrated in Figure 9B is an example only, and different reporting periods, reporting intervals, or the like, or a combination thereof may be configured.

In some aspects, UE 120 may transmit the first base CSI feedback report in a slot that is determined based at least in part on a slot in which the first communication was received. For example, UE 120 may transmit the first base CSI feedback report after a timing gap starting from the slot in which the first communication was received. The timing gap may include a timing gap of one or more slots, one or more symbols, or the like, or a combination thereof, that UE 120 is to wait before transmitting the first base CSI feedback report. In some aspects, the timing gap may be specified in the first communication (for example, in a field included in the first communication) . In some aspects, the timing gap may be specified in another communication, such as an RRC communication, a DCI communication, or the like, that is received from BS 110. In some aspects, the timing gap may be configured at UE 120 based at least in part on a capability of UE 120, such as a processing capability (for example, which may determine how quickly UE 120 can generate and transmit the base CSI feedback report after receiving the first communication) .

As shown in Figure 9C, in a third operation 906, BS 110 may transmit a second communication to UE 120. The second communication may include another indication to activate the differential CSI feedback reporting procedure. The second communication may include another RRC communication, another DCI communication, or the like, transmitted on a PDSCH, a PBCH, or another type of physical channel, that includes an indication to activate the differential CSI feedback reporting procedure. The indication may include, for example, a flag, a value included in one or more fields, or the like, or a combination thereof, included in the second communication.

BS 110 may transmit the second communication for various purposes. For example, BS 110 may determine that the differential CSI feedback reporting procedure is deactivated at UE 120 and accordingly may transmit the second communication to reactivate the differential CSI feedback reporting procedure. As another example, BS 110 may determine that the differential CSI feedback reporting procedure is already activated at UE 120, but that a DCI issue has occurred (for example, BS 110 transmitted an erroneous DCI communication to UE 120, UE 120 could not decode or read a DCI communication transmitted from BS 110, etc. ) . As another example, BS 110 may determine that the differential CSI feedback reporting procedure is already activated at UE 120, but that downlink channel performance does not satisfy one or more channel performance thresholds (e.g., a noise threshold, a throughput threshold, a channel quality threshold, or the like, or a combination thereof) . This may occur, for example, when BS 110 determines that a large amount of fading occurs in a relatively short period of time, when BS 110 determines that the reporting period for the differential CSI feedback reporting procedure is too long (which may cause the CSI feedback to become stale or inaccurate before the reporting period ends) , when BS 110 determines that BS 110 does not receive an expected CSI feedback report, or the like.

As shown in Figure 9D, in a fourth operation 908, if the differential CSI feedback reporting procedure is already activated at UE 120, UE 120 may determine to reset the differential CSI feedback reporting procedure. In some aspects, UE 120 may determine to reset the differential CSI feedback reporting procedure based at least in part on being configured to reset the differential CSI feedback reporting procedure if UE 120 receives an indication to activate the differential CSI feedback reporting procedure when the differential CSI feedback reporting procedure is already activated at UE 120. In some aspects, UE 120 may determine to reset the differential CSI feedback reporting procedure based at least in part on identifying an indication in the second communication to reset the differential CSI feedback reporting procedure.

In some aspects, the second communication may include information for resetting the differential CSI feedback reporting procedure. For example, the second communication may indicate that UE 120 is to use a different reporting period (that is, UE 120 is to transmit a greater or fewer quantity of differential CSI feedback reports in the reporting period) , may indicate that UE 120 is to use a different reporting interval (that is, UE 120 is to wait a greater or fewer quantity of slots or symbols between transmit CSI feedback reports in the reporting period) , or the like, or a combination thereof.

Figures 10A-10C are diagrams illustrating various techniques for resetting the differential CSI feedback reporting procedure. As shown in Figure 10A, UE 120 may reset the differential CSI feedback reporting procedure based at least in part on a time duration. The time duration may be determined based at least in part on a slot in which the second communication was received. The time duration may be indicated by the second communication, may be indicated by another communication (for example, another RRC communication, another DCI communication, or another type of communication) , may be configured at UE 120, or the like, or a combination thereof.

In some aspects, the time duration may specify a quantity of slots, symbols, or the like, or a combination thereof, between the slot in which the second communication was received and a slot in which UE 120 is to reset the differential CSI reporting procedure by initiating a new reporting period. That is, UE 120 is to initiate the new reporting period in the next slot or symbol after the slot or symbol in which the time duration expires. In this case, UE 120 may establish a new cadence for subsequent reporting periods after receiving the second communication. That is, UE 120 may initiate the new reporting period in a slot that was not previously scheduled in the differential CSI feedback reporting procedure, and the time interval between CSI feedback reports in the differential CSI feedback reporting procedure may be based at least in part on the slot in which the base CSI feedback report is to be transmitted in the new reporting period.

As an example of the above, and as illustrated in Figure 10A, UE 120 may receive the second communication in slot 2, and the time duration may include one slot. In this case the time duration may expire in slot 3, and UE 120 may reset the differential CSI feedback reporting procedure by transmitting a base CSI feedback report in a new reporting period in the next slot (that is, slot 4) adjacent to the slot in which the time duration expired. UE 120 may continue to transmit CSI feedback reports using the newly establish cadence (that is, in even-numbered slots as opposed to odd-numbered slots before the second communication was received) .

In some aspects, UE 120 may be configured to refrain from transmitting any CSI feedback reports that were scheduled to occur during the time duration (for example, UE 120 may be configured to refrain from transmitting the differential CSI feedback report that was to occur in slot 3, as illustrated in Figure 10A) . In this way, UE 120 conserves processing, memory, and radio resources that would have otherwise been used to transmit the CSI feedback reports. In some aspects, UE 120 may be configured to transmit the CSI feedback reports that were scheduled to be transmitted during the time duration, and BS 110 may be configured to ignore or discard the CSI feedback reports.

As shown in Figures 10B and 10C, UE 120 may reset the differential CSI feedback reporting procedure based at least in part on a timing gap. The timing gap may be determined based at least in part on a slot in which the second communication was received. The time duration may be indicated by the second communication, may be indicated by another communication (for example, another RRC communication, another DCI communication, or another type of communication) , may be configured at UE 120, may be the timing gap indicated in the first communication, or the like, or a combination thereof.

In some aspects, the timing gap may specify a quantity of slots, symbols, or the like, or a combination thereof, after the slot in which the second communication was received, that UE 120 is to wait to initiate a new reporting period in a slot that was previously scheduled for transmitting another CSI feedback report. That is, UE 120 is to initiate the new reporting period according to the feedback reporting cadence of the differential CSI feedback reporting procedure.

Figure 10B illustrates an example of initiating a new reporting period based at least in part on the timing gap. As shown in Figure 10B, UE 120 may receive the second communication in slot 1, and the timing gap may include a two-slot timing gap. Since no CSI feedback report was scheduled in slot 4 (that is, the next slot after expiration of the timing gap) in the differential CSI feedback reporting procedure, UE 120 may reset the differential CSI feedback reporting procedure by initiating the new reporting period in the next slot, after slot 4, in which a CSI feedback report is scheduled in the differential CSI feedback reporting procedure. In this case, UE 120 may reset the differential CSI feedback reporting procedure by converting slot 5 from a differential CSI feedback report slot to a base CSI feedback report slot, since the next CSI feedback report in the differential CSI feedback reporting procedure occurs in slot 5. UE 120 may further convert slot 7 from a base CSI feedback reporting slot to a differential CSI feedback reporting slot, and so on.

Figure 10C illustrates another example of initiating a new reporting period based at least in part on the timing gap. As shown in Figure 10C, UE 120 may receive the second communication in slot 3, and the timing gap may include a one-slot timing gap. Since a differential CSI feedback report was scheduled in slot 5 in the differential CSI feedback reporting procedure, UE 120 may reset the differential CSI feedback reporting procedure by transmitting a base CSI feedback report in the new reporting period. In this case, UE 120 may reset the differential CSI feedback reporting procedure by converting slot 5 from a differential CSI feedback report slot to a base CSI feedback report slot, by converting slot 7 from a base CSI feedback reporting slot to a differential CSI feedback reporting slot, and so on.

In some aspects, UE 120 may be configured to refrain from transmitting any CSI feedback reports that were scheduled to occur during the timing gap (for example, UE 120 may be configured to refrain from transmitting the differential CSI feedback report that was to occur in slot 3, as illustrated in Figure 10B) . In this way, UE 120 conserves processing, memory, and radio resources that would have otherwise been used to transmit the CSI feedback reports. In some aspects, UE 120 may be configured to transmit the CSI feedback reports that were scheduled to be transmitted during the timing gap, and BS 110 may be configured to ignore or discard the CSI feedback reports.

In this way, UE 120 may be capable of providing a base CSI feedback report, which includes complete CSI feedback (that is, CSI feedback indicating a selection of one or more beams transmitted by BS 110, phase information associated with the one or more beams, amplitude information associated with the one or more beams, etc. ) , and one or more differential CSI feedback reports, which fine tune the complete CSI feedback indicated in the base CSI feedback report. Since the one or more differential CSI feedback reports do not include complete CSI feedback and, instead, indicate changes to the complete CSI feedback indicated in the base CSI feedback report, the one or more differential CSI feedback reports may be relatively smaller than the base CSI feedback report, and may therefore reduce CSI feedback reporting overhead while providing increased CSI feedback resolution.

Figure 11 is a diagram illustrating an example process 1100 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 1100 is an example where a UE (e.g., UE 120) performs operations associated with signaling support for differential CSI reporting.

As shown in Figure 11, in some aspects, process 1100 may include receiving, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure (block 1110) . For example, the UE (using receive processor 258, transmit processor 264, controller/processor 280, memory 282, or the like, or a combination thereof) may receive, after receiving a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure, as described above.

As further shown in Figure 11, in some aspects, process 1100 may include resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication (block 1120) . For example, the UE (using receive processor 258, transmit processor 264, controller/processor 280, memory 282, or the like, or a combination thereof) may reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication, as described above.

Process 1100 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In some aspects, the first communication includes a first DCI communication and the second communication comprises a second DCI communication. In some aspects, receiving the second communication includes receiving the second communication on a PDCCH. In some aspects, the slot is determined based at least in part on the second communication, and process 1100 includes determining the slot based at least in part on a time duration, associated with the second communication, relative to a time at which the second communication was received.

In some aspects, the time duration is determined based at least in part on at least one of an indication of the time duration by the second communication, an indication of the time duration by a third communication, or a capability of the UE. In some aspects, the slot occurs adjacent to another slot at an end of the time duration. In some aspects, resetting the differential CSI feedback reporting procedure includes transmitting a base CSI feedback report in the slot.

In some aspects, the slot is determined based at least in part on the first communication, and process 1100 includes determining the slot based at least in part on a timing gap, associated with the first communication, relative to a time at which the second communication was received. In some aspects, the timing gap is determined based at least in part on at least one of an indication of the time duration by the first communication, an indication of the time duration by a third communication, or a capability of the UE.

In some aspects, the slot includes a reporting slot, after the timing gap, that was initially scheduled for transmission of a differential CSI feedback report in the differential CSI feedback reporting procedure, and resetting the differential CSI feedback reporting procedure includes transmitting a base CSI feedback report in the slot. In some aspects, process 1100 includes refraining from transmitting another CSI feedback report in another reporting slot, during the timing gap, that was initially scheduled for transmission of the other CSI feedback report in the differential CSI feedback reporting procedure. In some aspects, the other indication to activate the differential CSI feedback reporting procedure includes at least one of, a field included in the second communication, a value included in the second communication, or a flag included in the second communication.

Figure 12 is a diagram illustrating an example process 1200 performed, for example, by a BS, in accordance with various aspects of the present disclosure. Example process 1200 is an example where a BS (e.g., BS 110) performs operations associated with signaling support for differential CSI reporting.

As shown in Figure 12, in some aspects, process 1200 may include transmitting, to a UE, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure (block 1210) . For example, the BS (using transmit processor 220, receive processor 238, controller/processor 240, memory 242, or the like, or a combination thereof) may transmit, to a UE, a first communication that includes a first indication to activate a differential CSI feedback reporting procedure, as described above.

As further shown in Figure 12, in some aspects, process 1200 may include transmitting, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure (block 1220) . For example, the BS (using transmit processor 220, receive processor 238, controller/processor 240, memory 242, or the like, or a combination thereof) may transmit, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure, as described above.

As further shown in Figure 12, in some aspects, process 1200 may include receiving, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication (block 1230) . For example, the BS (using transmit processor 220, receive processor 238, controller/processor 240, memory 242, or the like, or a combination thereof) may receive, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication, as described above.

Process 1200 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In some aspects, transmitting the second communication includes transmitting the second communication based at least in part on at least one of determining that the differential CSI feedback reporting procedure is deactivated, determining that the BS transmitted an erroneous DCI communication, determining that the UE could not decode the DCI communication, or determining that channel performance, on a downlink between the UE and the BS, does not satisfy a threshold channel performance.

In some aspects, the first communication includes a first DCI communication and the second communication comprises a second DCI communication. In some aspects, transmitting the second communication includes transmitting the second communication on a PDCCH. In some aspects, the slot is determined based at least in part on the second communication, and process 1200 includes determining the slot based at least in part on a time duration relative to a time at which the second communication was received.

In some aspects, the other indication to activate the differential CSI feedback reporting procedure includes at least one of a field included in the second communication, a value included in the second communication, or a flag included in the second communication. In some aspects, the slot comprises a reporting slot after a time duration or a timing gap. In some aspects, process 1200 includes discarding another CSI feedback report, in the differential CSI feedback reporting procedure, that was received during the time duration or the timing gap.

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

Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may 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, or the like, or a combination thereof.

It will be apparent that systems or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems or methods is not limiting of the aspects. Thus, the operation and behavior of the systems 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 or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims 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 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 (for example, 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 (for example, related items, unrelated items, a combination of related and unrelated items, or the like, or a combination thereof) , 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, ” or the like, or a combination thereof 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:

receiving, after receiving a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure; and

resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.
The method of claim 1, wherein the first communication comprises a first downlink control information (DCI) communication, and wherein the second communication comprises a second DCI communication.
The method of claim 1, wherein receiving the second communication comprises receiving the second communication on a physical downlink control channel (PDCCH) .
The method of claim 1, wherein the slot is determined based at least in part on the second communication, and wherein the method further comprises determining the slot based at least in part on a time duration, associated with the second communication, relative to a time at which the second communication was received.
The method of claim 4, wherein the time duration is determined based at least in part on at least one of:

an indication of the time duration by the second communication,

an indication of the time duration by a third communication, or

a capability of the UE.
The method of claim 4, wherein the slot occurs adjacent to another slot at an end of the time duration.
The method of claim 4, wherein resetting the differential CSI feedback reporting procedure comprises transmitting a base CSI feedback report in the slot.
The method of claim 1, wherein the slot is determined based at least in part on the first communication, and wherein the method further comprises determining the slot based at least in part on a timing gap, associated with the first communication, relative to a time at which the second communication was received.
The method of claim 8, wherein the timing gap is determined based at least in part on at least one of:

an indication of the timing gap by the first communication,

an indication of the timing gap by a third communication, or

a capability of the UE.
The method of claim 8, wherein:

the slot comprises a reporting slot, after the timing gap, that was initially scheduled for transmission of a differential CSI feedback report in the differential CSI feedback reporting procedure; and

resetting the differential CSI feedback reporting procedure comprises transmitting a base CSI feedback report in the slot.
The method of claim 10, further comprising refraining from transmitting another CSI feedback report in another reporting slot, during the timing gap, that was initially scheduled for transmission of the other CSI feedback report in the differential CSI feedback reporting procedure.
The method of claim 1, wherein the other indication to activate the differential CSI feedback reporting procedure comprises at least one of:

a field included in the second communication,

a value included in the second communication, or

a flag included in the second communication.
A method of wireless communication performed by a base station (BS) , comprising:

transmitting, to a user equipment (UE) , a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure;

transmitting, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and

receiving, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.
The method of claim 13, wherein transmitting the second communication comprises transmitting the second communication based at least in part on at least one of:

determining that the differential CSI feedback reporting procedure is deactivated,

determining that the BS transmitted an erroneous downlink control information (DCI) communication,

determining that the UE could not decode the DCI communication, or

determining that channel performance, on a downlink between the UE and the BS, does not satisfy a threshold channel performance.
The method of claim 13, wherein the first communication comprises a first downlink control information (DCI) communication, and wherein the second communication comprises a second DCI communication.
The method of claim 13, wherein transmitting the second communication comprises transmitting the second communication on a physical downlink control channel (PDCCH) .
The method of claim 13, wherein the slot is determined based at least in part on the second communication, and wherein the method further comprises determining the slot based at least in part on a time duration relative to a time at which the second communication was received.
The method of claim 13, wherein the other indication to activate the differential CSI feedback reporting procedure comprises at least one of:

a field included in the second communication,

a value included in the second communication, or

a flag included in the second communication.
The method of claim 13, wherein the slot comprises a reporting slot after a time duration or a timing gap; and

wherein the method further comprises discarding another CSI feedback report, in the differential CSI feedback reporting procedure, that was received during the time duration or the timing gap.
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:

receive, after receiving a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure; and

reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.
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:

receive, after receiving a first communication that includes an indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes another indication to activate the differential CSI feedback reporting procedure; and

reset, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.
An apparatus for wireless communication, comprising:

means for receiving, after receiving a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure, a second communication that includes a second indication to activate the differential CSI feedback reporting procedure; and

means for resetting, based at least in part on receiving the second communication, the differential CSI feedback reporting procedure in a slot that is determined based at least in part on the first communication or the second communication.
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) , a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure

transmit, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and

receive, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.
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) , a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure

transmit, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and

receive, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.
An apparatus for wireless communication, comprising:

means for transmitting, to a user equipment (UE) , a first communication that includes a first indication to activate a differential channel state information (CSI) feedback reporting procedure

means for transmitting, to the UE, a second communication that includes a second indication to activate a differential CSI feedback reporting procedure; and

means for receiving, from the UE based at least in part on transmitting the second communication, a base CSI feedback report in a slot that is determined based at least in part on the first communication or the second communication.