WO2020143022A1

WO2020143022A1 - Channel state information (csi) omission for type-ii csi report

Info

Publication number: WO2020143022A1
Application number: PCT/CN2019/071338
Authority: WO
Inventors: Chenxi HAO; Chao Wei; Liangming WU; Qiaoyu Li; Min Huang; Wanshi Chen; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2019-01-11
Filing date: 2019-01-11
Publication date: 2020-07-16
Also published as: WO2020143737A1

Abstract

Certain aspects of the present disclosure provide techniques for omitting channel state information feedback components. An example method generally includes obtaining an uplink (UL) resource to be used for channel state information (CSI) reporting; receiving a CSI reference signal (CSI-RS); determining a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases; identifying that the UL resource is insufficient to carry a payload for the CSI report; omitting a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and reporting the remaining feedback components after the omission.

Description

CHANNEL STATE INFORMATION (CSI) OMISSION FOR TYPE-II CSI REPORT

INTRODUCTION

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for omitting channel state information (CSI) feedback components for a Type-II CSI report.

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, 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, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system may include a number of base stations (BSs) , which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs) . In an LTE or LTE-Anetwork, a set of one or more base stations may define an eNodeB (eNB) . In other examples (e.g., in a next generation, a new radio (NR) , or 5G network) , a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs) , edge nodes (ENs) , radio heads (RHs) , smart radio heads (SRHs) , transmission reception points (TRPs) , etc. ) in communication with a number of central units (CUs) (e.g., central nodes (CNs) , access node controllers (ANCs) , etc. ) , where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., which may be referred to as a base station, 5G NB, next generation NodeB (gNB or gNodeB) , TRP, etc. ) . A base station or distributed unit may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit) .

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New Radio (NR) (e.g., 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. It 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 OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports 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 NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between network entities and user equipment.

Certain aspects provide a method for wireless communication. The method generally includes obtaining an uplink (UL) resource to be used for channel state information (CSI) reporting; receiving a CSI reference signal (CSI-RS) ; determining a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases; identifying that the UL resource is insufficient to carry a payload for the CSI report; omitting a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and reporting the remaining feedback components after the omission.

Certain aspects provide a method for wireless communication. The method generally includes signaling an uplink (UL) resource to be used for channel state information (CSI) reporting; receiving, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases; determining from a first portion of the CSI report that a second portion of the CSI report has an omitted portion of the feedback components associated with at least one spatial beam and at least one compression basis; and taking one or more actions based on the CSI report.

Aspects of the present disclosure also provide various apparatuses, means, and computer program products corresponding to the methods and operations described above.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which 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 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.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram illustrating an example logical architecture of a distributed radio access network (RAN) , in accordance with certain aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example physical architecture of a distributed RAN, in accordance with certain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE) , in accordance with certain aspects of the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communication protocol stack, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates an example of a frame format for a new radio (NR) system, in accordance with certain aspects of the present disclosure.

FIG. 7A illustrates an example feedback system which reports all the feedback components in the transformed codebook using a beam-common basis, in accordance with certain aspects of the present disclosure.

FIG. 7B illustrates an example feedback system which reports a subset of the feedback components in the transformed codebook using a beam-common basis, in accordance with certain aspects of the present disclosure.

FIG. 7C illustrates illustrates an example feedback system which reports a subset of the feedback components using a beam-specific basis, in accordance with certain aspects of the present disclosure.

FIG. 8 is a flow diagram illustrating example operations for omitting a portion of the CSI feedback components, in accordance with certain aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating example operations for reducing CSI overhead, in accordance with certain aspects of the present disclosure.

FIG. 10 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for omitting a portion of the CSI feedback components under a feedback scheme using a compression basis as further described herein.

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC- FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) .

New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-Aand GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

New radio (NR) access (e.g., 5G technology) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a New Radio (NR) or 5G network. As further described herein, the UE may perform operations for omitting CSI feedback components under a feedback scheme that uses a compression basis, and the BS may identify that feedback components in the CSI feedback are omitted.

As illustrated in FIG. 1, the wireless network 100 may include a number of base stations (BSs) 110 and other network entities. A BS may be a station that communicates with user equipment (UEs) . Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB) , new radio base station (NR BS) , 5G NB, access point (AP) , or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

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. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. 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.

A base station (BS) may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the femto cells 102y and 102z, respectively. A BS may support one or multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110r may communicate with the BS 110a and a UE 120r in order to facilitate communication between the BS 110a and the UE 120r. A relay station may also be referred to as a relay BS, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network 100. For example, macro BS may have a high transmit power level (e.g., 20 Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 Watt) .

Wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.

The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, 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 computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a “resource block” (RB) ) may be 12 subcarriers (or 180 kHz) . Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz) , respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks) , and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a cyclic prefix (CP) on the uplink and downlink and include support for half-duplex operation using TDD. 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.

In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A finely dashed line with double arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates an example logical architecture of a distributed Radio Access Network (RAN) 200, which may be implemented in the wireless communication network 100 illustrated in FIG. 1. A 5G access node 206 may include an access node controller (ANC) 202. ANC 202 may be a central unit (CU) of the distributed RAN 200. The backhaul interface to the Next Generation Core Network (NG-CN) 204 may terminate at ANC 202. The backhaul interface to neighboring next generation access Nodes (NG-ANs) 210 may terminate at ANC 202. ANC 202 may include one or more transmission reception points (TRPs) 208 (e.g., cells, BSs, gNBs, etc. ) .

The TRPs 208 may be a distributed unit (DU) . TRPs 208 may be connected to a single ANC (e.g., ANC 202) or more than one ANC (not illustrated) . For example, for RAN sharing, radio as a service (RaaS) , and service specific AND deployments, TRPs 208 may be connected to more than one ANC. TRPs 208 may each include one or more antenna ports. TRPs 208 may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE.

The logical architecture of distributed RAN 200 may support fronthauling solutions across different deployment types. For example, the logical architecture may be based on transmit network capabilities (e.g., bandwidth, latency, and/or jitter) .

The logical architecture of distributed RAN 200 may share features and/or components with LTE. For example, next generation access node (NG-AN) 210 may support dual connectivity with NR and may share a common fronthaul for LTE and NR.

The logical architecture of distributed RAN 200 may enable cooperation between and among TRPs 208, for example, within a TRP and/or across TRPs via ANC 202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logical architecture of distributed RAN 200. As will be described in more detail with reference to FIG. 5, the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and a Physical (PHY) layers may be adaptably placed at the DU (e.g., TRP 208) or CU (e.g., ANC 202) .

FIG. 3 illustrates an example physical architecture of a distributed Radio Access Network (RAN) 300, according to aspects of the present disclosure. A centralized core network unit (C-CU) 302 may host core network functions. C-CU 302 may be centrally deployed. C-CU 302 functionality may be offloaded (e.g., to advanced wireless services (AWS) ) , in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions. Optionally, the C-RU 304 may host core network functions locally. The C-RU 304 may have distributed deployment. The C-RU 304 may be close to the network edge.

A DU 306 may host one or more TRPs (Edge Node (EN) , an Edge Unit (EU) , a Radio Head (RH) , a Smart Radio Head (SRH) , or the like) . The DU may be located at edges of the network with radio frequency (RF) functionality.

FIG. 4 illustrates example components of BS 110 and UE 120 (as depicted in FIG. 1) , which may be used to implement aspects of the present disclosure. For example, antennas 452,

processors

466, 458, 464, and/or controller/processor 480 of the UE 120 and/or antennas 434,

processors

420, 430, 438, and/or controller/processor 440 of the BS 110 may be used to perform the various techniques and methods described herein, such as illustrated in FIGs. 8 and 9.

At the BS 110, a transmit processor 420 may receive data from a data source 412 and control information from a controller/processor 440. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. The processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols, e.g., for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , and cell-specific reference signal (CRS) . A transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.

At the UE 120, the antennas 452a through 452r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) in transceivers 454a through 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 456 may obtain received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 460, and provide decoded control information to a controller/processor 480.

On the uplink, at UE 120, a transmit processor 464 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 462 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 480. The transmit processor 464 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators in transceivers 454a through 454r (e.g., for SC-FDM, etc. ) , and transmitted to the base station 110. At the BS 110, the uplink signals from the UE 120 may be received by the antennas 434, processed by the modulators 432, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by the UE 120. The receive processor 438 may provide the decoded data to a data sink 439 and the decoded control information to the controller/processor 440.

The controllers/

processors

440 and 480 may direct the operation at the base station 110 and the UE 120, respectively. The processor 440 and/or other processors and modules at the BS 110 may perform or direct the execution of processes for the techniques described herein. The

memories

442 and 482 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 444 may schedule UEs for data transmission on the downlink and/or uplink.

FIG. 5 illustrates a diagram 500 showing examples for implementing a communications protocol stack, according to aspects of the present disclosure. The illustrated communications protocol stacks may be implemented by devices operating in a wireless communication system, such as a 5G system (e.g., a system that supports uplink-based mobility) . Diagram 500 illustrates a communications protocol stack including a Radio Resource Control (RRC) layer 510, a Packet Data Convergence Protocol (PDCP) layer 515, a Radio Link Control (RLC) layer 520, a Medium Access Control (MAC) layer 525, and a Physical (PHY) layer 530. In various examples, the layers of a protocol stack may be implemented as separate modules of software, portions of a processor or ASIC, portions of non-collocated devices connected by a communications link, or various combinations thereof. Collocated and non-collocated implementations may be used, for example, in a protocol stack for a network access device (e.g., ANs, CUs, and/or DUs) or a UE.

A first option 505-ashows a split implementation of a protocol stack, in which implementation of the protocol stack is split between a centralized network access device (e.g., an ANC 202 in FIG. 2) and distributed network access device (e.g., DU 208 in FIG. 2) . In the first option 505-a, an RRC layer 510 and a PDCP layer 515 may be implemented by the central unit, and an RLC layer 520, a MAC layer 525, and a PHY layer 530 may be implemented by the DU. In various examples the CU and the DU may be collocated or non-collocated. The first option 505-a may be useful in a macro cell, micro cell, or pico cell deployment.

A second option 505-b shows a unified implementation of a protocol stack, in which the protocol stack is implemented in a single network access device. In the second option, RRC layer 510, PDCP layer 515, RLC layer 520, MAC layer 525, and PHY layer 530 may each be implemented by the AN. The second option 505-b may be useful in, for example, a femto cell deployment.

Regardless of whether a network access device implements part or all of a protocol stack, a UE may implement an entire protocol stack as shown in 505-c (e.g., the RRC layer 510, the PDCP layer 515, the RLC layer 520, the MAC layer 525, and the PHY layer 530) .

In LTE, the basic transmission time interval (TTI) or packet duration is the 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (e.g., 1, 2, 4, 8, 16, …slots) depending on the subcarrier spacing. The NR RB is 12 consecutive frequency subcarriers. NR may support a base subcarrier spacing of 15 KHz and other subcarrier spacing may be defined with respect to the base subcarrier spacing, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7, 12, or 14 symbols) depending on the subcarrier spacing. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols) .

Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.

In NR, a synchronization signal (SS) block is transmitted. The SS block includes a PSS, a SSS, and a two symbol PBCH. The SS block can be transmitted in a fixed slot location, such as the symbols 0-3 as shown in FIG. 6. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS blocks may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI) , system information blocks (SIBs) , other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes.

In some circumstances, two or more subordinate entities (e.g., 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, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, and/or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying that communication through the scheduling entity (e.g., UE or BS) , even though the scheduling entity may be utilized for scheduling and/or control purposes. In some examples, the sidelink signals may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum) .

A UE may operate in various radio resource configurations, including a configuration associated with transmitting pilots using a dedicated set of resources (e.g., a radio resource control (RRC) dedicated state, etc. ) or a configuration associated with transmitting pilots using a common set of resources (e.g., an RRC common state, etc. ) . When operating in the RRC dedicated state, the UE may select a dedicated set of resources for transmitting a pilot signal to a network. When operating in the RRC common state, the UE may select a common set of resources for transmitting a pilot signal to the network. In either case, a pilot signal transmitted by the UE may be received by one or more network access devices, such as an AN, or a DU, or portions thereof. Each receiving network access device may be configured to receive and measure pilot signals transmitted on the common set of resources, and also receive and measure pilot signals transmitted on dedicated sets of resources allocated to the UEs for which the network access device is a member of a monitoring set of network access devices for the UE. One or more of the receiving network access devices, or a CU to which receiving network access device (s) transmit the measurements of the pilot signals, may use the measurements to identify serving cells for the UEs, or to initiate a change of serving cell for one or more of the UEs.

Example Channel State Information (CSI) Feedback

As channel conditions between a user equipment (UE) and a base station (BS) change, the UE may periodically or aperiodically report certain channel properties (e.g., a CSI-reference signal channel indicator (CRI) , a channel quality indicator (CQI) , a precoding matrix index (PMI) , and/or a rank indicator (RI) ) to the BS. In certain aspects, the UE transmits a channel state information (CSI) report to the BS to indicate channel conditions to the BS. The CSI may be an explicit report of channel or an implicit report of the precoder. The explicit CSI represents the channel itself, which is a result of the combined effects of, for example, scattering, fading, and power decay with distance between a transmitter and receiver. The implicit report comprises a precoder that is preferred by the UE for downlink data transmission. Channel estimation may be performed to determine these effects on the channel or the precoder. The CSI report may be used by the BS to adapt transmissions based on the current channel conditions, which is useful for achieving reliable communication, in particular, with high data rates in multi-antenna systems (e.g., 5G/NR wireless communication networks) .

In certain aspects, such as under NR/5G wireless communication networks, implicit CSI reporting is widely used. It may support multiple types of spatial information (e.g., CSI) feedback. For instance, Type I CSI feedback may provide a CSI feedback scheme that is also used by wireless communications devices comporting to other wireless communication standards such LTE standards. Type I CSI feedback may include codebook-based PMI feedback with normal spatial resolution and is designed based on beam selection. As another example, Type II CSI feedback may provide an enhanced feedback scheme, enabling codebook-based feedback with higher spatial resolution. Type I CSI feedback corresponds to a lower resolution and smaller payload, while Type II CSI corresponds to a higher resolution and larger payload. Type II CSI feedback may include information regarding linear combination of different beams identified from a codebook, such as amplitude, phase, etc. of transmit antennas associated with different widebands and subbands.

Type II CSI feedback relates to reporting a precoder feedback based on a linear combination of dual-stage codebooks. In certain aspects, a linear combination of the dual-stage codebooks supports up to four beam combinations with a certain precoder structure. For example, the PMI codebook may assume the following precoder structure:

In Release 15 of the 5G/NR 3GPP standards, for rank 1:

where W is normalized to 1. W ₁ and W ₂ indicate precoding weights for rank 1 (or transmission layer 1) . For rank 2:

where columns of W are normalized to

Based on such a precoder structure, the UE may feed the following information back to the BS:

(weighted combination of L beams) , where

In this formula, r stands for polarization and l stands for transmission layer. In addition, up to L wideband orthogonal beams are selected. In addition, as shown, the UE reports the wideband amplitude

as well as the subband differential amplitude

and subband phase θ _r, l, i. Also, a number or quantity of bits (e.g., 2 or 3 bits) are used to report the subband phase with amplitude dependent quantization.

As Type II CSI reporting provides a higher resolution (more granular channel information over a number or quantity of subbands, transmission layers, and/or beams etc. ) , the overhead associated with Type II CSI reporting is large even if the reporting is performed for only two transmission layers (e.g., up to rank 2) . For example, the total PMI bits may be more than, for example, 900 bits in worst case for Type-II CSI in 3GPP Release 15. Also, trivial extension to a higher rank may result in even larger payload bits. In addition, payload (or overhead) increases linearly as the number or quantity of beams and/or ranks increases.

To reduce the overhead under Type-II CSI feedback, feedback systems may transform subband coefficients into another domain (e.g., a discrete Fourier transform (DFT) basis domain or a discrete cosine transform (DCT) domain) . For a certain layer, the precoder across the frequency domain w _r, may be given by the following expression:

where b _l is a vector of spatial beams (e.g., DFT beams) ,

and

are coefficients associated with beam b _l for the first and second polarization, respectively, and

and

are a frequency domain compression matrix and may also be referred to herein as a transformed basis or a compression basis (e.g., DFT basis or DCT basis) that is applied to beam b _l for the first and second polarization. In certain aspects, c _i, which represents the linear combination coefficients across subbands for beam index i in R15, may be transformed into different matrices under a second feedback system including

with dimensions 1×M _i and

with dimensions M _i×N ₃, where M≤N ₃, N ₃ may be the quantity of subbands N _SB, and M _i is the quantity of coefficients. The coefficients and compression basis may have different sizes according to beam indices (i) . The coefficients and the compression basis may be represented according to polarities as provided by the following expressions:

having dimensions M _1, l×N ₃

having dimensions M _2, l×N ₃

and

Representing the basis and coefficients applied to beam l for the first and second polarization. For instance, the overall quantity of identified beams from the Type-II codebook may be B=2L, where the number 2 is due to the consideration of antenna polarization (e.g.,

may correspond to + 45° polarization, and

may correspond to -45° polarization) . For the coefficients in the transferred domain associated with the bth beam, the quantity of coefficients in the transferred domain associated with this beam to feedback is denoted by M _band thus

In current feedback systems, coefficient feedback is feedback of amplitude and phase values of the entries in matrix c. For the bth beam (i.e., for the bth row in matrix c) , a beam-specific amplitude, such as a wideband amplitude value, is reported using A _b bits. For each coefficient in different subbands for the bth beam (i.e., for the entries in the bth row in matrix c) , a differential amplitude value based on the beam-specific amplitude value (e.g., measured over a wideband rather than per-subband) is reported using

bits, and a phase value based on the wideband phase value is reported using

bits.

In some feedback systems, coefficients in current feedback systems can be transferred into a transfer domain. Provided the number of non-zero coefficients in the transfer domain is sparse, by reporting the dominant coefficients in the transfer domain instead of in the original domain, overhead of reporting can be reduced. Particularly, coefficient feedback is feedback of the amplitude and phase values of the entries (or a subset of the entries) in matrix

For the bth beam (e.g., for the bth row in matrix

) , a beam-specific amplitude, such as a wideband amplitude value, is reported using A _b bits, and a beam-specific phase, such as a wideband phase value, is reported using P _b bits. For each selected coefficients associated with the bth beam (e.g., for the entries in the bth row in matrix

) , a differential amplitude value based on the beam-specific amplitude value may be reported using

bits, and a differential phase value based on the beam-specific phase value may be reported using

bits.

FIG. 7A illustrates an example feedback system which reports beam-common basis, and reports all the feedback components associated with the beam-common basis, in accordance with certain aspects of the present disclosure. As shown, ,

is a row vector representing the coefficients associated with the first beam (e.g., b _i) , where M _i = M, for all i=0, 1, ..., 2L and F _i = F, for all i = 0, 1, ..., 2L-1.

FIG. 7B illustrates an example feedback system which reports a subset of the feedback components in the transformed codebook using a beam-common basis, in accordance with certain aspects of the present disclosure. As shown, the UE reports a subset of the coefficients

702B using a common basis

704B. The subset of beam coefficients may be given by the following expression:

K ₀＜K=2L×M _i

where K ₀ represents the number of beam coefficients included in the CSI report, and K represents the total number of beam coefficients. K ₀ may be signaled to the BS by the UE or configured by a higher layer parameter (e.g., RRC signaling from the BS, downlink control signaling, or medium access control signaling) .

In certain aspects, a beam-specific basis may be used to feedback the CSI report. For example, FIG. 7C illustrates an example feedback system which reports a subset of the feedback components using a beam-specific basis, in accordance with certain aspects of the present disclosure. As shown, each row vector of coefficients

702C is beam specific using a beam specific compression basis

704C. Each row of the coefficient matrix

corresponds to the coefficients for a particular beam (b _i) . For instance, the number of reported coefficients for beam b ₁ is M ₁ and the associated basis for beam b ₁ is denoted by F ₁, having a size of M ₁×N ₃.

In some cases, the payload size of CRI, RI and CQI are fixed, while the PMI (especially the subband PMI) payload size may vary depending on the reported RI. From this aspect, the CSI reporting may be divided into two or three parts, where a first portion of the CSI feedback contains CRI/RI/CQI having a fixed payload size, while the second and third portions of the CSI feedback contain PMI having a variable payload size. Table 1, below, illustrates example scenarios of when CSI feedback may be partitioned into two or three portions and the information carried in each portion.

Table 1

Under Release 15, a coefficient of beam i in a subband k may be given by the following expression:

where

has a wideband amplitude, and

has a subband differential amplitude and a phase. The UE may identify that an uplink channel is insufficient to report all of the subband coefficients and reduce the size of the coefficient payload. In some cases, the UE may omit the odd subband coefficients, for example, omitting

In other cases, the UE may omit the even subband coefficients, for example omitting

Because subband information is integrated in a compression basis, omitting subband feedback components cannot be applied to a feedback scheme without eliminating the entire compression basis, which is not a feasible CSI payload reduction technique. The present disclosure provides various omission techniques for reducing the payload of feedback using a compression basis.

Example CSI Omission for Type-II CSI Report

Certain aspects of the present disclosure relate to reducing the payload of the variable size CSI portion of the feedback components under a compression basis reporting scheme. For example, in some cases, the configured UL resource for CSI reproting may be insufficient to carry the CSI payload. Under such a condition, the UE may omit certain feedback components in order to fit within the UL resource. For example, the UE may omit a portion of the feedback components associated with a spatial beam and a compression basis. In certain aspects, the UE may report a smaller subset of compression basis components or coefficients than the CSI configuration. In other aspects, the UE may reduce the quantization resolution of the feedback components. In aspects, the UE may omit feedback components based on a layer priority associated with the CSI portion. For other aspects, the UE may omit a spatial beam, compression basis, or coefficient report based on the CSI processing time assigned to the UE. In aspects, the UE may down-sample the compression basis according to a down-sampling factor as further described herein.

FIG. 8 is a flow diagram illustrating example operations 800 that may be performed, for example, by a user equipment (e.g., UE 120) , for omitting a portion of the CSI feedback components, in accordance with certain aspects of the present disclosure.

The operations 800 may begin, at block 802, where the UE may obtain an uplink (UL) resource to be used for channel state information (CSI) reporting. At block 804, the UE may receive a CSI reference signal (CSI-RS) . At block 806, the UE may determine a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases. At block 808, the UE may identify that the UL resource is insufficient to carry a payload for the CSI report. At block 810, the UE may omit a portion of the feedback components associated with at least one spatial beam and at least one compression basis. At block 812, the UE may report the remaining feedback components after the omission.

FIG. 9 is a flow diagram illustrating example operations 900 that may be performed, for example, by a network entity (e.g., BS 110) , for reducing CSI overhead, in accordance with certain aspects of the present disclosure.

The operations 900 may begin, at block 902, where the network entity may signal an uplink (UL) resource to be used for channel state information (CSI) reporting. At block 904, the network entity may receive, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases. At block 906, the network entity may determine, from a first part of the CSI report, a payload of a second part of the CSI report. At block 908, the network entity may determine that the allocated UL resource is insufficient to carry the payload of the second part of the CSI report. At block 910, the network entity may determine that a portion of the second part of the CSI report is omitted based on the allocated UL resource being insufficient to carry the payload of the second part of the CSI report. At 912, the network entity may take one or more actions based on the CSI report, such as determining a precoding to use for multiple input multiple output (MIMO) communications based on the CSI report.

In certain aspects, omitting a portion of the feedback components may include omitting a first portion of the feedback components, identifying that the UL resource is insufficient to carry a payload for the CSI report after omitting the first portion, omitting a second portion of the feedback components, and reporting the remaining feedback components after omitting the first and second portions of the feedback components.

In certain aspects, omitting a portion of the feedback components may include omitting one or more compression bases and/or one or more coefficients associated with one or more spatial beams. For instance, the UE may receive a CSI configuration from the BS to report M basis and K ₀ coefficients associated with the M basis. The UE may determine to report M′＜M basis and/or K′ ₀＜K ₀ coefficients, based at least in part on the UL resource allocation (e.g., at block 808 where the UE identifies that the UL resource is insufficient to carry a payload for the CSI report) .

In certain aspects, omitting the first and second portions of the feedback components may include omitting one or more compression bases associated with one or more spatial beams. For example, the UE may omit M-m ₁ from the compression basis and report m ₁ compression bases; omit M-m ₂ from the compression basis and report m ₂ compression bases; or omit M and not report the compression basis and the coefficients. In some cases, m ₁ may be less than m ₂ (m ₁＜m ₂) , for example, m ₁= M/2 and m ₂=M-1. The values of m ₁ and/or m ₂ may be fixed values (e.g., a default value stored on the UE) or configured by the BS.

In certain aspects, omitting one or more compression bases may include omitting the one or more compression bases according to an order corresponding to the one or more compression bases. For example, the UE may sort the compression bases according to compression basis indices or in descending order based on compression basis amplitudes (e.g., the amplitude of the compression basis (i.e., tap) k may be

) . In aspects, omitting the first portion may include omitting the compression basis with the lowest order, and omitting the second portion may include omitting the compression basis with the second lowest order. In other aspects, omitting the feedback components may include omitting the compression bases starting from the compression basis with the lowest order until the UL resource is sufficient to report the CSI feedback.

In certain aspects, omitting the portion of the feedback components may include omitting the one or more coefficients associated with the one or more spatial beams and the one or more compression bases. For example, the UE may omit K ₀-k ₁ from the coefficients and report k ₁ coefficients; omit K ₀-k ₂ from the coefficients and report k ₂ coefficients; or omit all the M basis and not report the compression basis and the coefficients. In some cases, k ₁ may be less than k ₂ (k ₁＜k ₂) , for example, k ₁=2LM′/2 and k ₂=K ₀-2L. If there is no bases omission then M′=M as configured by BS; if there is basis omission then M′=m ₁ or m ₂ determined in the basis omission procedure. The values of k ₁ and/or k ₂ may be configured by the BS or fixed values (e.g., a default value stored on the UE) .

In certain aspects, omitting the one or more coefficients comprises omitting the one or more coefficients according to an order of the one or more coefficients. For example, the UE may sort the coefficients according to coefficient indices or in descending order based on coefficient amplitudes. In some cases, omitting the first portion may include omitting the one or more coefficients with the lowest order, and omitting the second portion may include omitting the coefficients with the second lowest order. The number of coefficients omitted in the first and second portions may be configured by the BS or a fixed value. In aspects, omitting the feedback components may include omitting the coefficients starting from the coefficient with the lowest order until the UL resource is sufficient to report the CSI feedback.

In certain aspects, omitting the portion of the feedback components may include omitting one or more compression bases associated one or more spatial beams, and omitting one or more coefficients associated with the one or more spatial beams and the one or more remaining compression bases after the compression basis omission. In aspects, the one or more compression bases and coefficients may be omitted according to an order of the one or more compression bases and coefficients. In some cases, omitting the first portion may include omitting the one or more compression bases and the one or more coefficients with the lowest order, and omitting the second portion may include omitting the one or more compression bases and the one or more coefficients with the second lowest order. The number of coefficients and number of compression bases omitted in the first and second portions may be configured by the BS or fixed values (e.g., stored on the UE) .

In certain aspects, the BS may determine that CSI omission has been performed based on the CSI payload and resource allocation in the UL channel. As the first part of the CSI report may have a fixed size, the BS may determine the payload of the second part of the CSI from the first part of the CSI report. The BS may compare the payload of the second part of the CSI with the UL resource and determine whether the UE performed feedback component omissions. For example, if M basis and/or K ₀ coefficients are reported, the BS determines that the UL resource is sufficient and no feedback components were omitted. If M′ basis and/or K′ ₀ coefficients are reported, the BS determines the UL resource is insufficient and omission was performed by the UE. The BS may also determine the feedback components omitted as described herein, including basis omissions, coefficient omissions, quantization reductions, and/or down-sampling.

In aspects, omitting the first and second portions of the feedback components may include reducing a quantization resolution for at least one of the coefficients. Reducing the quantization resolution may include reducing the quantization resolution for at least one of an amplitude quantization or a phase quantization of the coefficients. Omitting the first portion of the feedback component may include reducing a quantization resolution for an amplitude of the coefficients, and omitting the second portion of the feedback component may include reducing the quantization resolution for a phase of the coefficients. In certain aspects, the quantization of each of the coefficients may include determining a wideband part and a differential part, and omitting the portion of the feedback components may include reducing a quantization resolution for at least one of the wideband part and the differential part of the coefficients. The resolution of the reduced quantization is configured by a base station or a fixed value.

After identifying that the UL resource is insufficient to carry a payload for the CSI report at block 808, the UE may reduce the quantization resolution for the amplitude and phase data equally. Suppose the UE is configured to use 3-bits to quantize the amplitude and 3-bits to quantize the phase, the UE may reduce the quantization resolution for amplitude to 2-bits and the quantization resolution for the phase to 2-bits.

In other cases, the UE may reduce the quantization resolution for the amplitude and phase unequally. For instance, for a first part of coefficients with higher amplitude, the UE may employ a reduced quantization for the amplitude and phase, and for a second part of coefficients with lower amplitude, the UE may employ a quantization resolution as that used for no omission case.

In certain aspects, the UE may reduce the quantization by performing differential quantization for amplitude and phase coefficients. For example, the UE may reduce the quantization by determining a quantization for the amplitude and phase coefficients relative to a reference value, such as an average, maximum, or minimum value.

In certain aspects, omitting the portion of the feedback components may include omitting at least one of the feedback components based on a layer priority. The layer priority may be determined based on at least one of a layer indicator or indices of each layer. A layer indicator may indicate which column of the precoder matrix of the reported PMI corresponds to the strong layer of the codeword corresponding to the largest reported wideband CQI. The layer indicated by the layer indicator may have the highest or lowest priority, and the layer priorities of the remaining layers may be ordered by respective indices. If there is no layer indication, the layers may be sorted according to indices associated with the layers. For example, a higher layer index may correspond to a lower priority or vice versa. In certain aspects, the UE may omit the layer with the weakest priority. The numbers of the compression bases and coefficients in a first portion of a first layer may be the same as or different from a first portion of a second layer. The numbers of the first portion and second portion of the compression bases or the coefficients associated with each layer may be fixed values (e.g., stored on the UE) or configured by a BS.

In certain aspects, the UE may omit the compression bases and coefficient within the weakest layer and then across the remaining layers. In some cases, the UE may omit the compression bases according to the layer priority as follows:

Pri (1…m _1, 1) > Pri (m _1, 1+1...m _1, 2) > Pri (m _1, 2+1...M) > Pri (1...m _2, 1) > Pri (m _2, 1+1...m _2, 2) > Pri (m _2, 2+1...M) >…

where m _r, j refers to the omission threshold j for layer r.

In other cases, the UE may omit the coefficients according to the layer priority as follows:

Pri (1…k _1, 1) > Pri (k _1, 1+1...k _1, 2) > Pri (k _1, 2+1...K ₀) > Pri (1...k _2, 1) > Pri (k _2, 1+1...k _2, 2) > Pri (k _2, 2+1...K ₀) >…

where k _r, j refers to the omission threshold j for layer r. In aspects, the UE may omit compression bases and coefficients according to the layer priority as follows:

Pri (1…k _1, 1) > Pri (k _1, 1+1...k _1, 2) > Pri (k _1, 2+1...min {2LM′ (1) , K ₀} ) > Pri (1...k _2, 1) > Pri (k _2, 1+1...k _2, 2) > Pri (k2 _, 2+1...min {2LM′ (2) , K ₀} ) >…

where k _r, j refers to the omission threshold j for layer r, and M′ (r) corresponds to the number of bases after omission for layer r. m _r, j and k _r, j may have different values across layers. Different layers may different threshold values for determining the omissions. Each layer may be ordered according to respective indices or amplitude values.

As an example, the UE may determine that a first layer has a higher priority than a second layer. The UE may also determine that a first portion of at least one of the compression bases or the coefficients associated with a first layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the first layer, the second portion of at least one of the compression bases or the coefficients of the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, and the first portion of at least one of the compression bases or coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer. The UE may omit the feedback components starting from omitting at least one of the compression bases or the coefficients associated with the layer having the lowest priority according to the layer priority determinations.

In certain aspects, the UE may omit the compression bases and coefficients across layers and then within the weakest layers. In some cases, the UE may omit the compression bases according to the layer priority as follows:

Pri (1…m _1, 1) > Pri (1...m _2, 1) > Pri (m _1, 1+1...m _1, 2) > Pri (m _2, 1+1...m _2, 2) > Pri (m _1, 2+1...M) > Pri (m _2, 2+1...M)

where m _r, j refers to the omission threshold j for layer r. In other cases, the UE may omit the coefficients according to the layer priority as follows:

Pri (1…k _1, 1) > Pri (1...k _2, 1) > Pri (k _1, 1+1...k _1, 2) > Pri (k _2, 1+1...k _2, 2) > Pri (k _1, 2+1...K ₀) > Pri (k _2, 2+1...K ₀)

Pri (1…k _1, 1) > Pri (1...k _2, 1) > Pri (k _1, 1+1...k _1, 2) > Pri (k _2, 1+1...k _2, 2) > Pri (k _1, 2+1...min {2LM′ (1) , K ₀} ) > Pri (k _2, 2+1...min {2LM′ (2) , K ₀} )

where k _r, j refers to the omission threshold j for layer r, and M′ (r) corresponds to the number of bases after omission for layer r. m _r, j and k _r, j may have different values across layers.

As an example, the UE may determine that a first portion of at least one of the compression bases or the coefficients associated with the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, a second portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than the second portion of at least one of the compression bases or the coefficients of the first layer, and the first portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer. The UE may omit the feedback components starting from omitting at least one of the compression bases or the coefficients associated with the layer having the lowest priority according to the layer priority determinations.

In certain aspects, the UE may reduce a quantization resolution for at least one of the feedback components according to a layer priority. In some cases, the UE may reduce the quantization resolution for the coefficients in the weakest layer. In other cases, the UE may reduce the quantization resolution for coefficients within the weakest layer and then across the remaining layers. In aspects, the UE may reduce the quantization resolution for coefficients across the layers and then within the weakest layer. The reduced quantization resolution may be layer-specific and/or coefficient specific. For instance, the first layer may employ a higher quantization resolution than the second layer. As another example, the leading coefficients (e.g., the first part) may use a higher quantization resolution than the next coefficients (e.g., the second part) .

As an example, the UE may determine that a first portion of at least one of the compression bases or the coefficients associated with a first layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the first layer, the second portion of at least one of the compression bases or the coefficients of the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, and the first portion of at least one of the compression bases or coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer. The UE may reduce the quantization resolution starting from reducing the quantization resolution for at least one of the compression bases or the coefficients associated with the layer having the lowest priority according to the layer priority determinations.

As another example, the UE may determine a first portion of at least one of the compression bases or the coefficients associated with the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, a second portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than the second portion of at least one of the compression bases or the coefficients of the first layer, and the first portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than a second portion of basis or coefficient associated with the second layer. The UE may reduce the quantization resolution starting from the quantization resolution for at least one of the compression bases or the coefficients associated with the layer having the lowest priority according to the layer priority determinations.

In certain aspects, the UE may omit all of the compression bases and/or the coefficients associated with all the layers. The UE may be configured with timing thresholds to determine whether to omit CSI feedback components. For instance, if a CSI report starts earlier than Z″ _ref symbols after the respective reference resource, but no earlier than Z′ _ref symbols after the respective reference resource, and no earlier than Z _ref symbols after the latest symbol of PDCCH triggering the aperiodic-CSI report, the UE may determine to drop the entire second part of a CSI report. In other cases, if a CSI report starts no earlier than Z″ _ref symbols after its reference resource, and no earlier than Z _ref symbols after the latest symbol of PDCCH triggering the aperiodic-CSI report, the UE may perform the CSI feedback component omission as described herein (e.g., at block 810) .

As an example, the UE may determine that a first time period between the CSI-RS resource and the UL resource to carry the CSI report is smaller than a first timing threshold and determine that a second time period between a CSI report trigger and the UL resource to carry the CSI report is greater than or equal to a second timing threshold. The UE may omit the compression bases and/or the coefficients associated with all layers based on the timing determinations. The first timing threshold may be a fixed value, configured by a BS, or derived based on a predefined rule or UE processing capability.

As another example, the UE may determine that a first time period between the CSI-RS resource and the UL resource to carry the CSI report is greater than or equal to a first timing threshold (e.g., Z″ _ref) and determine that a second time period between the CSI report trigger and the UL resource to carry the CSI report is greater than or equal to a second timing threshold (e.g., Z _ref) . The UE may omit a portion of the feedback components according to the timing determinations.

In certain aspects, the UE may generate one or more down-sampled compression bases according to a down-sampling factor. For instance, the BS may configure the UE to report a N ₃-point DFT-based compression basis. For CSI omission, the UE may generate a down-sampled

-point DFT-based compression basis. The down-sampling factor may be a fixed value (e.g., R = 2) or configured by the BS (e.g., R > 1) .

Suppose the UE is configured to use a beam-common basis as depicted in FIG. 7A. Assuming the BS configures the UE to report CSI feedback components having dimensions M = 4 basis and L = 4 beams, the UE may report the first part of the CSI report including RI = 2, the CQI, and the number of non-zero amplitude beams. The second part of the CSI report may be reduced by performing the CSI omission for the compression bases and/or coefficients associated with spatial beams. For instance, the UE may omit weakest two bases, providing M’=2 basis common to all four beams resulting in 16 coefficients. If the UE determines that the UL resource is still insufficient to report the CSI, the UE may omit the weakest 3 bases, reporting M’=1 bases common to all four beams resulting in 8 coefficients.

As another example, the UE may omit weakest 2 bases for layer-2 resulting in 32 coefficients for layer-1 and 16 for layer-2. If the UE determines that the UL resource is still insufficient to report the CSI, the UE may omit the weakest 3 basis for layer-2, providing only 1 basis for layer-2 yielding in 32 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 and 3 bases for layer-1 and layer-2, respectively, resulting in 16 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 3 bases for layer-1 and layer-2, respectively, leaving 8 coefficients for layer-1 and 8 for layer-2.

In certain cases, the UE may omit weakest 2 basis for layer-2 resulting in 32 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases for layer-1 and layer-2, respectively, resulting in 16 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 and 3 bases for layer-1 and layer-2, respectively, resulting in 16 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit weakest 3 bases for layer-1 and layer-2, respectively, yielding 8 coefficients for layer-1 and 8 for layer-2.

In certain aspects, the UE may omit weakest 2 bases, providing M’=2 basis common to all 4 beams and 2 polarizations resulting in 16 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit all four bases.

As an example, the UE may omit weakest 2 basis for layer-2 providing 32 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit all 4 bases for layer-2 providing 32 coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 and all 4 bases for layer-1 and layer-2, respectively, resulting in 16 coefficients for layer-1 and zero for layer-2. If the UL resource is still insufficient, the UE may omit all 4 bases for both layer-1 and layer-2 providing no coefficients for layer-1 and layer-2.

In certain cases, the UE may omit weakest 2 bases for layer-2 providing 32 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases for layer-1 and layer-2, respectively, yielding 16 coefficients for layer-1 and 16 for layer-2. If the UL resource is still insufficient, the UE may omit weakest 2 and all 4 bases for layer-1 and layer-2, respectively, providing 16 coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit all 4 bases for both layer-1 and layer-2 resulting in reporting no coefficients for layer-1 and layer-2.

Suppose the UE is configured to use a beam-common basis, for example, as depicted in FIG. 7B. Assuming the BS configures the UE to report CSI feedback components having dimensions M=4 basis, L=4 beams, K ₀=24 out of 32 coefficients. The UE may omit the weakest 12 coefficients, resulting in 12 coefficients. If the UL resource is still insufficient, the UE may omit the weakest 16 coefficients, yielding 8 coefficients.

As an example of omitting coefficients, the UE may omit the weakest 12 coefficients for layer-2 resulting in 24 coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 16 coefficients for layer-2, yielding 24 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 and 16 coefficients for layer-1 and layer-2, respectively, resulting in 12 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 coefficients for layer-1 and layer-2, respectively, reporting 8 coefficients for layer-1 and 8 for layer-2.

As an example of omitting coefficients and compression bases, the UE may omit the weakest 12 coefficients for layer-2 resulting in 24 coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 coefficients for layer-1 and layer-2, respectively, yielding 12 coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 and 16 bases for layer-1 and layer-2, respectively, providing 8 coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and layer-2, respectively, reporting 8 coefficients for layer-1 and 8 for layer-2.

In certain cases, the UE may omit the weakest 12 coefficients, resulting in 12 coefficients. If the UL resource is still insufficient, the UE may omit all coefficients and report no coefficients.

In other cases, the UE may omit the weakest 12 coefficients for layer-2, resulting in 24 coefficients for layer-1 and 12 for layer-2.. If the UL resource is still insufficient, the UE may omit all coefficients for layer-2, yielding 24 coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 coefficients for layer-1 and all coefficients for layer-2, providing 12 coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit all coefficients for layer-1 and layer-2, and thus, reporting no coefficients.

In certain examples, the UE may omit the weakest 12 coefficients for layer-2, resulting in 24 coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 coefficients for layer-1 and layer-2, respectively, providing 12 coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 coefficients for layer-1 and all coefficients for layer-2, yielding 8 coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit all coefficients for layer-1 and layer-2, reporting no coefficients.

As an example of omitting bases and coefficients, the UE may omit 2 bases and 12 coefficients, providing 2 bases with 12 coefficients. If the UL resource is still insufficient, the UE may omit 2 bases and 16 coefficients, reporting 2 bases with 8 coefficients.

In other cases, the UE may omit 2 bases and 12 coefficients for layer-2 resulting in 4 bases with 24 coefficients for layer-1 and 2 bases with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 16 coefficients for layer-2, providing 4 bases with 24 coefficients for layer-1 and 2 bases with 8 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit weakest 2 bases and 12 coefficients for layer-1 and 2 bases with 16 coefficients for layer-2, yielding 2 basis with 12 coefficients for layer-1 and 2 bases with 8 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 12 coefficients for both layer-1 and layer-2, reporting 2 bases with 8 coefficients for both layer-1 and layer-2.

In some cases, the UE may omit 2 bases and omit 12 coefficients for layer-2, providing 4 bases with 24 coefficients for layer-1 and 2 bases with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit weakest 2 bases and 12 coefficients for both layer-1 and layer-2 resulting in 2 bases with 12 coefficients for layer-1 and 2 basis with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 12 coefficients for layer-1 and 2 basis with 16 coefficients for layer-2 yielding 2 bases with 12 coefficients for layer-1 and 2 bases with 8 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 12 coefficients for both layer-1 and layer-2, reporting 2 bases with 8 coefficients for both layer-1 and layer-2.

In other cases, the UE may omit 2 bases and 12 coefficients, providing 2 bases with 12 coefficients. If the UL resource is still insufficient, the UE may omit all bases and all coefficients, reporting no bases and coefficients.

In aspects, the UE may omit 2 bases and 12 coefficients for layer-2, providing 4 bases with 24 coefficients for layer-1 and 2 bases with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit all basis and coefficients for layer-2 resulting in 4 bases with 24 coefficients for layer-1 and no basis and coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 12 coefficients for layer-1, and all bases and all coefficients for layer-2, yielding 2 bases with 12 coefficients for layer-1 and no basis and coefficients for layer-2. If the UL resource is still insufficient, the UE may omit all basis and coefficients for both layer-1 and layer-2, providing no basis and coefficients for both layer-1 and layer-2.

In some aspects, the UE may omit 2 bases and 12 coefficients for layer-2, providing 4 bases with 24 coefficients for layer-1 and 2 bases with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 bases and 12 coefficients for both layer-1 and layer-2, yielding 2 bases with 12 coefficients for layer-1 and 2 bases with 12 coefficients for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 2 basis and 12 coeffs for layer-1, and all basis and all coefficients for layer-2, providing 2 bases with 12 coefficients for layer-1 and no basis and coefficients for layer-2. If the UL resource is still insufficient, the UE may omit all basis and all coefficients both layer-1 and layer-2, reporting no basis and coefficients for both layer-1 and layer-2.

Suppose the UE is configured to use a beam-specific basis, for example, as depicted in FIG. 7C. Assuming the BS configures the UE to report L=4 beams,

basis and all coefficients, the UE may omit the weakest 12 bases providing 12 bases with 12 coefficients. If the UL resource is still insufficient, the UE may omit the weakest 16 bases, reporting 8 bases with 8 coefficients.

In certain cases, the UE may omit the weakest 12 bases for layer-2, resulting in 24 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 16 bases for layer-2, providing 24 bases and coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 and 16 bases for layer-1 and layer-2, respectively, yielding 12 bases and coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and layer-2 and report 8 bases and coefficients for layer-1 and 8 for layer-2.

As an example, the UE may omit the weakest 12 bases for layer-2, providing 24 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and layer-2, respectively, resulting in 12 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 and 16 bases for layer-1 and layer-2, respectively, reporting 12 bases and coefficients for layer-1 and 8 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and layer-2, respectively, reporting 8 bases and coefficients for layer-1 and 8 for layer-2.

As another example, the UE may omit the weakest 12 bases, reporting 12 bases with 12 coefficients. If the UL resource is still insufficient, the UE may omit all bases and report no bases and coefficients.

In some cases, the UE may omit the weakest 12 bases for layer-2 reporting 24 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit all bases for layer-2 reporting 24 bases and coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and all bases for layer-2, reporting 12 bases and coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit all bases for layer-1 and layer-2 and thus report none.

In other cases, the UE may omit the weakest 12 bases for layer-2 providing 24 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and layer-2, respectively, providing 12 bases and coefficients for layer-1 and 12 for layer-2. If the UL resource is still insufficient, the UE may omit the weakest 12 bases for layer-1 and all bases layer-2, yielding 12 bases and coefficients for layer-1 and none for layer-2. If the UL resource is still insufficient, the UE may omit all bases for layer-1 and layer-2, reporting no bases and coefficients for layer-1 and layer-2.

FIG. 10 illustrates a communications device 1000 (e.g., UE 120 or BS 110) that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIGs. 8 and 9. The communications device 1000 includes a processing system 1002 coupled to a transceiver 1008. The transceiver 1008 is configured to transmit and receive signals for the communications device 1000 via an antenna 1010, such as the various signal described herein. The processing system 1002 may be configured to perform processing functions for the communications device 1000, including processing signals received and/or to be transmitted by the communications device 1000.

The processing system 1002 includes a processor 1004 coupled to a computer-readable medium/memory 1012 via a bus 1006. In certain aspects, the computer-readable medium/memory 1012 is configured to store instructions that when executed by processor 1004, cause the processor 1004 to perform the operations illustrated in FIGs. 8 and 9, or other operations for performing the various techniques discussed herein.

In certain aspects, the processing system 1002 may further include an obtaining component 1014 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include a receiving component 1016 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include a determining component 1018 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include an identifying component 1020 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include an omitting component 1022 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include a reporting component 1024 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include a signaling component 1026 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein. Additionally, the processing system 1002 may include a taking action component 1028 for performing the operations illustrated in FIGs. 8 and 9, or other aspects of the operations described herein.

The obtaining component 1014, receiving component 1016, determining component 1018, identifying component 1020, omitting component 1022, reporting component 1024, signaling component 1026, and/or taking action component 1028 may be coupled to the processor 1004 via bus 1006. In certain aspects, the obtaining component 1014, receiving component 1016, determining component 1018, identifying component 1020, omitting component 1022, reporting component 1024, signaling component 1026, and/or taking action component 1028 may be hardware circuits. In certain aspects, the obtaining component 1014, receiving component 1016, determining component 1018, identifying component 1020, omitting component 1022, reporting component 1024, signaling component 1026, and/or taking action component 1028 may be software components that are executed and run on processor 1004.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

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

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

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

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

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user equipment 120 (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, for example, instructions for performing the operations described herein and illustrated in FIGs. 8 and 9.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

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

obtaining an uplink (UL) resource to be used for channel state information (CSI) reporting;

receiving a CSI reference signal (CSI-RS) ;

determining a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

identifying that the UL resource is insufficient to carry a payload for the CSI report;

omitting a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and

reporting the remaining feedback components after the omission.
The method of claim 1, wherein omitting a portion of the feedback components comprises:

omitting a first portion of the feedback components;

identifying that the UL resource is insufficient to carry a payload for the CSI report after omitting the first portion;

omitting a second portion of the feedback components; and

reporting the remaining feedback components after omitting the first and second portions of the feedback components.
The method of claim 2, wherein omitting the first and second portion of the feedback components comprises omitting one or more compression bases associated with one or more spatial beams.
The method of claim 3, wherein omitting one or more compression bases comprises omitting the one or more compression bases according to an order corresponding to the one or more compression bases.
The method of claim 4, wherein:

the order is based on at least one of the indices of the compression bases or amplitudes of the coefficients associated with each of the one or more compression bases;

omitting the first portion comprises omitting the one or more compression bases with the lowest order; and

omitting the second portion comprises omitting the one or more compression bases with the second lowest order.
The method of claim 4, wherein a number of compression bases omitted in the first and second portions is configured by a base station or a fixed value.
The method of claim 2, wherein omitting the portion of the feedback components comprises omitting the one or more coefficients associated with the one or more spatial beams and the one or more compression bases.
The method of claim 7, wherein omitting the one or more coefficients comprises omitting the one or more coefficients according to an order of the one or more coefficients.
The method of claim 7, wherein:

the order is based on at least one of indices of the one or more coefficients or based on amplitudes of the one or more coefficients;

omitting the first portion comprises omitting the one or more coefficients with the lowest order; and

omitting the second portion comprises omitting the one or more coefficients with the second lowest order.
The method of claim 7, wherein a number of coefficients omitted in the first and second portions is configured by a base station or a fixed value.
The method of claim 2, wherein omitting the portion of the feedback components comprises omitting one or more compression bases associated with one or more spatial beams, and omitting one or more coefficients associated with the one or more spatial beams and the one or more remaining compression bases after the compression basis omission.
The method of claim 11, wherein omitting the one or more basis and coefficients comprises omitting the one or more compression bases and coefficients according to an order of the one or more compression bases and coefficients.
The method of claim 12, wherein:

the order is based on the indices of the compression basis and coefficients or amplitudes of coefficients;

omitting the first portion comprises omitting the one or more compression bases and the one or more coefficients with the lowest order; and

omitting the second portion comprises omitting the one or more compression bases and the one or more coefficients with the second lowest order.
The method of claim 11, wherein a number of coefficients and a number of compression bases omitted in the first and second portions are configured by the base station or fixed values.
The method of claim 2, wherein omitting the first and second portions of the feedback components comprises reducing a quantization resolution for at least one of the coefficients.
The method of claim 15, further comprising determining that the quantization of each of the coefficients comprises a wideband part and a differential part, and wherein omitting the portion of the feedback components comprises reducing a quantization resolution for at least one of the wideband part and the differential part of the coefficients.
The method of claim 15, wherein reducing the quantization resolution further comprises reducing the quantization resolution for at least one of an amplitude quantization or a phase quantization of the coefficients.
The method of claim 15, wherein omitting the first portion of the feedback component comprises reducing a quantization resolution for an amplitude of the coefficients, and omitting the second portion of the feedback component comprises reducing the quantization resolution for a phase of the coefficients.
The method of claim 15, wherein the resolution of the reduced quantization is configured by a base station or a fixed value.
The method of claim 2, wherein omitting the portion of the feedback components comprises omitting at least one of the feedback components based on a layer priority.
The method of claim 20, wherein:

the layer priority is determined based on at least one of a layer indicator or indices of each layer;

the layer indicated by the layer indicator has the highest or lowest priority, the layer priorities of the remaining layers are ordered by respective indices; and

omitting at least one of the feedback components based on the layer priority comprises omitting at least one of the feedback components associated with the layer of the lowest priority.
The method of claim 20, further comprising:

determining that a first layer has a higher priority than a second layer;

determining that:

a first portion of at least one of the compression bases or the coefficients associated with a first layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the first layer,

the second portion of at least one of the compression bases or the coefficients of the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, and

the first portion of at least one of the compression bases or coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer; and

omitting the feedback components starting from omitting at least one of the compression bases or the coefficients associated with the layer having the lowest priority.
The method of claim 9, further comprising:

determining a first layer having a higher priority than a second layer;

determining that:

a first portion of at least one of the compression bases or the coefficients associated with the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer,

a second portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than the second portion of at least one of the compression bases or the coefficients of the first layer, and

the first portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer; and

omitting the feedback components starting from omitting the compression bases or the coefficients associated with the layer having the lowest priority.
The method of claim 20, wherein:

numbers of the compression bases and coefficients in the first portion of the first layer is same as or different from the first portion of the second layer; and

numbers of the first portion and second portion of the compression bases or the coefficients associated with each layer is configured by a base station or fixed values.
The method of claim 1, wherein omitting the portion of the feedback components comprises reducing a quantization resolution for at least one of the feedback components according to a layer priority.
The method of claim 25, further comprising:

determining that a first layer has a higher priority than a second layer;

determining that:

a first portion of at least one of the compression bases or the coefficients associated with a first layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the first layer,

the second portion of at least one of the compression bases or the coefficients of the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer, and

the first portion of at least one of the compression bases or coefficients associated with the second layer has a higher priority than a second portion of at least one of the compression bases or the coefficients associated with the second layer; and

reducing the quantization resolution starting from reducing the quantization resolution for at least one of the compression bases or the coefficients associated with the layer having the lowest priority.
The method of claim 25, further comprising:

determining a first layer having a higher priority than a second layer;

determining that:

a first portion of at least one of the compression bases or the coefficients associated with the first layer has a higher priority than a first portion of at least one of the compression bases or the coefficients associated with the second layer,

a second portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than the second portion of at least one of the compression bases or the coefficients of the first layer, and

the first portion of at least one of the compression bases or the coefficients associated with the second layer has a higher priority than a second portion of basis or coefficient associated with the second layer; and

reducing the quantization resolution starting from the quantization resolution for at least one of the compression bases or the coefficients associated with the layer having the lowest priority.
The method of claim 1, further comprising omitting at least one of the compression bases or the coefficients associated with all layers.
The method of claim 28, further comprising:

determining a first time period between the CSI-RS resource and the UL resource to carry the CSI report is smaller than a first timing threshold;

determining that a second time period between a CSI report trigger and the UL resource to carry the CSI report is greater than or equal to a second timing threshold; and

omitting at least one of the compression bases or the coefficients associated with all layers based on the timing determinations.
The method of claim 28, further comprising:

determining that a first time period between the CSI-RS resource and the UL resource to carry the CSI report is greater than or equal to a first timing threshold;

determining that a second time period between the CSI report trigger and the UL resource to carry the CSI report is greater than or equal to a second timing threshold; and

omitting a portion of the feedback components according to the timing determinations.
The method according to claims 29 or 30, wherein the first timing threshold is configured by a base station, a fixed value, or derived based on a predefined rule or UE processing capability.
The method of claim 1, wherein omitting the portion of the feedback components comprises generating one or more down-sampled compression bases according to a down-sampling factor.
The method of claim 32, wherein the down-sampling factor is configured by a base station or a fixed value.
A method of wireless communication by a network entity, comprising:

signaling an uplink (UL) resource to be used for channel state information (CSI) reporting;

receiving, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

determining, from a first part of the CSI report, a payload of a second part of the CSI report;

determining that the allocated UL resource is insufficient to carry the payload of the second part of the CSI report;

determining that a portion of the second part of the CSI report is omitted based on the allocated UL resource being insufficient to carry the payload of the second part of the CSI report; and

taking one or more actions based on the CSI report.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that one or more compression bases associated with one or more spatial beams is the omitted portion.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that the one or more coefficients associated with the one or more spatial beams and the one or more compression bases is the omitted portion.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that a reduced quantization resolution for at least one of the coefficients is the omitted portion.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that at least one of the feedback components is omitted according to a layer priority.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that at least one of the compression bases or the coefficients associated with all layers is the omitted portion.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises determining that a down-sampled compression basis is the omitted portion.
The method of claim 34, wherein determining that the portion of the second part of the CSI report is omitted comprises:

determining a first time period between the CSI-RS resource and the UL resource to carry the CSI report is smaller than a first timing threshold;

determining that a second time period between a CSI report trigger and the UL resource to carry the CSI report is greater than or equal to a second timing threshold; and

determining the omitted portion according to the timing determinations.
The method of claim 34, wherein taking one or more actions comprises determining a precoding to use for multiple input multiple output (MIMO) communications based on the CSI report.
An apparatus for wireless communication, comprising:

a receiver configured to receive an uplink (UL) resource to be used for channel state information (CSI) reporting and a CSI reference signal (CSI-RS) ;

a processing system configured to:

determine a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases,

identify that the UL resource is insufficient to carry a payload for the CSI report, and

omit a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and

a transmitter configured to transmit the remaining feedback components after the omission.
An apparatus for wireless communication, comprising:

a transmitter configured to transmit an uplink (UL) resource to be used for channel state information (CSI) reporting;

a receiver configured to receive, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases; and

a processing system configured to:

determine, from a first part of the CSI report, a payload of a second part of the CSI report,

determine that the allocated UL resource is insufficient to carry the payload of the second part of the CSI report,

determine that a portion of the second part of the CSI report is omitted based on the allocated UL resource being insufficient to carry the payload of the second part of the CSI report, and

take one or more actions based on the CSI report.
An apparatus for wireless communication, comprising:

means for obtaining an uplink (UL) resource to be used for channel state information (CSI) reporting;

means for receiving a CSI reference signal (CSI-RS) ;

means for determining a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

means for identifying that the UL resource is insufficient to carry a payload for the CSI report;

means for omitting a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and

means for reporting the remaining feedback components after the omission.
An apparatus for wireless communication, comprising:

means for signaling an uplink (UL) resource to be used for channel state information (CSI) reporting;

means for receiving, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

means for determining, from a first part of the CSI report, a payload of a second part of the CSI report;

means for determining that the allocated UL resource is insufficient to carry the payload of the second part of the CSI report;

means for determining that a portion of the second part of the CSI report is omitted based on the allocated UL resource being insufficient to carry the payload of the second part of the CSI report; and

means for taking one or more actions based on the CSI report.
A computer readable medium having instructions stored thereon for:

obtaining an uplink (UL) resource to be used for channel state information (CSI) reporting;

receiving a CSI reference signal (CSI-RS) ;

determining a plurality of feedback components based on the CSI-RS, wherein at least one of the feedback components comprises one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

identifying that the UL resource is insufficient to carry a payload for the CSI report;

omitting a portion of the feedback components associated with at least one spatial beam and at least one compression basis; and

reporting the remaining feedback components after the omission.
A computer readable medium having instructions stored thereon for:

signaling an uplink (UL) resource to be used for channel state information (CSI) reporting;

receiving, from a user equipment (UE) , a CSI report including a plurality of feedback components, wherein at least one of the feedback components comprises at least one or more spatial beams, one or more compression bases associated with the one or more spatial beams, and one or more coefficients associated with the one or more spatial beams and one or more compression bases;

determining, from a first part of the CSI report, a payload of a second part of the CSI report;

determining that the allocated UL resource is insufficient to carry the payload of the second part of the CSI report;

determining that a portion of the second part of the CSI report is omitted based on the allocated UL resource being insufficient to carry the payload of the second part of the CSI report; and

taking one or more actions based on the CSI report.