WO2022047759A1

WO2022047759A1 - Flexible csi-rs sharing for port selection csi feedback

Info

Publication number: WO2022047759A1
Application number: PCT/CN2020/113642
Authority: WO
Inventors: Chenxi HAO; Yu Zhang; Hao Xu; Liangming WU; Wanshi Chen
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2020-09-05
Filing date: 2020-09-05
Publication date: 2022-03-10
Anticipated expiration: 2023-03-05

Abstract

Certain aspects of the present disclosure provide techniques for channel state information (CSI) reporting. According to certain aspects, a user equipment (UE) receives a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report, receives dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources, performs CSI measurement using the activated subset of CSI-RS ports or resources, and transmits a report based on the CSI measurement.

Description

FLEXIBLE CSI-RS SHARING FOR PORT SELECTION CSI FEEDBACK

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for channel state information (CSI) feedback reporting.

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 DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation NodeB (gNB or gNodeB) , transmission reception point (TRP) , etc. ) . A BS or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a BS or DU to a UE) and uplink channels (e.g., for transmissions from a UE to BS or DU) .

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. NR (e.g., new radio or 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using 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.

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 access points and stations in a wireless network.

Certain aspects of the disclosure relate to a method for wireless communication by a user equipment (UE) . The method generally includes receiving a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report, receiving dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources, performing CSI measurement using the activated subset of CSI-RS ports or resources, and transmitting a report based on the CSI measurement.

Certain aspects of the disclosure relate to a method for wireless communication by a network entity. The method generally includes sending a user equipment (UE) a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report, sending the UE dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources, and receiving a CSI report based on CSI measurements taken by the UE using the activated subset of CSI-RS ports or resources.

Aspects of the present disclosure also provide various apparatuses, means, and computer readable including instructions for performing the operations described herein.

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 showing examples for implementing a communication protocol stack in the example RAN architecture, in accordance with certain aspects of the present disclosure.

FIG. 3 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. 4 illustrates an example of a frame format for a telecommunication system, in accordance with certain aspects of the present disclosure.

FIG. 5 illustrates a conceptual example of precoder matrices, in accordance with certain aspects of the present disclosure.

FIG. 6 is a call flow diagram illustrating a first example of Type II CSI feedback.

FIG. 7 is a call flow diagram illustrating a second example of Type II CSI feedback.

FIGs. 8A and 8B illustrate example ports and layer to port mapping.

FIG. 9 illustrates an example CSI-RS report configuration.

FIG. 10 illustrates example associations between CSI reports and CSI-resources and corresponding impact on port sharing.

FIGs. 11A and 11B illustrate example associations between CSI reports and CSI-resources.

FIG. 12 illustrates example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure.

FIG. 13 illustrates example operations for wireless communication by a network entity, in accordance with certain aspects of the present disclosure.

FIGs. 14A and 14B illustrate an example mechanism for flexible CSI-RS sharing, in accordance with certain aspects of the present disclosure.

FIGs. 15A and 15B illustrate another example mechanism for flexible CSI-RS sharing, in accordance with certain aspects of the present disclosure.

FIGs. 16A and 16B illustrate another example mechanism for flexible CSI-RS sharing, in accordance with certain aspects of the present disclosure.

FIGs. 17A and 17B illustrate another example mechanism for flexible CSI-RS sharing, in accordance with certain 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 relate to wireless communications, and more particularly, to techniques for performing efficient CSI feedback reporting. In some cases, to support flexible CSI-RS ports sharing, a UE is configured with a pool of CSI-RS resources and a network entity (e.g., gNB) may use dynamic signaling to activate a subset of the CSI-RS resource pool.

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-A and 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, a UE 120 in the wireless communication network 100 may include a CSI reporting module configured to perform (or assist the UE 120 in performing) operations 1200 described below with reference to FIG. 12. Similarly, a base station 120 (e.g., a gNB) may be configured to perform (or assist the base station 110 in performing) operations 1300 described below with reference to FIG. 13 to configure and process CSI reports received from a UE (performing operations 1200 of FIG. 12) .

As illustrated in FIG. 1, the wireless communication 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 (UE) . 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 NB 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 or gNodeB) , 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 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 communication 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 communication 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 communication 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 sub-bands. For example, a sub-band may cover 1.08 MHz (i.e., 6 resource blocks) , and there may be 1, 2, 4, 8, or 16 sub-bands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

Communication systems such as NR may utilize OFDM with a cyclic prefix (CP) on the uplink and downlink and include support for half-duplex operation using time division duplex (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 4 streams per UE. Multi-layer transmissions with up to 4 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) 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 a diagram showing examples for implementing a communications protocol stack in a RAN (e.g., such as the RAN 100) , according to aspects of the present disclosure. The illustrated communications protocol stack 200 may be implemented by devices operating in a wireless communication system, such as a 5G NR system (e.g., the wireless communication network 100) . In various examples, the layers of the protocol stack 200 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 or a UE. As shown in FIG. 2, the system may support various services over one or more protocols. One or more protocol layers of the protocol stack 200 may be implemented by the AN and/or the UE.

As shown in FIG. 2, the protocol stack 200 is split in the AN (e.g., BS 110 in FIG. 1) . The RRC layer 205, PDCP layer 210, RLC layer 215, MAC layer 220, PHY layer 225, and RF layer 230 may be implemented by the AN. For example, the CU-CP may implement the RRC layer 205 and the PDCP layer 210. A DU may implement the RLC layer 215 and MAC layer 220. The AU/RRU may implement the PHY layer (s) 225 and the RF layer (s) 230. The PHY layers 225 may include a high PHY layer and a low PHY layer.

The UE may implement the entire protocol stack 200 (e.g., the RRC layer 205, the PDCP layer 210, the RLC layer 215, the MAC layer 220, the PHY layer (s) 225, and the RF layer (s) 230) .

FIG. 3 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 352,

processors

366, 358, 364, and/or controller/processor 380 of the UE 120 may be configured (or used) to perform operations 1200 of FIG. 12 and/or antennas 334,

processors

320, 330, 338, and/or controller/processor 340 of the BS 110 may be configured (or used) to perform operations 1300 described below with reference to FIG. 13.

At the BS 110, a transmit processor 320 may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical 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 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 320 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 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 332a through 332t. Each modulator 332 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 332a through 332t may be transmitted via the antennas 334a through 334t, respectively.

At the UE 120, the antennas 352a through 352r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) in transceivers 354a through 354r, respectively. Each demodulator 354 may condition (e.g., filter, amplify, down-convert, 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 356 may obtain received symbols from all the demodulators 354a through 354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 358 may process (e.g., demodulate, de-interleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 360, and provide decoded control information to a controller/processor 380.

In a MIMO system, a transmitter (e.g., BS 120) includes multiple transmit antennas 354a through 354r, and a receiver (e.g., UE 110) includes multiple receive antennas 352a through 352r. Thus, there are a plurality of signal paths 394 from the transmit antennas 354a through 354r to the receive antennas 352a through 352r. Each of the transmitter and the receiver may be implemented, for example, within a UE 110, a BS 120, or any other suitable wireless communication device.

The use of such multiple antenna technology enables the wireless communication system to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data, also referred to as layers, simultaneously on the same time-frequency resource. The data streams may be transmitted to a single UE to increase the data rate or to multiple UEs to increase the overall system capacity, the latter being referred to as multi-user MIMO (MU-MIMO) . This is achieved by spatially precoding each data stream (i.e., multiplying the data streams with different weighting and phase shifting) and then transmitting each spatially precoded stream through multiple transmit antennas on the downlink. The spatially precoded data streams arrive at the UE (s) with different spatial signatures, which enables each of the UE (s) to recover the one or more data streams destined for that UE. On the uplink, each UE transmits a spatially precoded data stream, which enables the base station to identify the source of each spatially precoded data stream.

The number of data streams or layers corresponds to the rank of the transmission. In general, the rank of the MIMO system is limited by the number of transmit or receive antennas, whichever is lower. In addition, the channel conditions at the UE, as well as other considerations, such as the available resources at the base station, may also affect the transmission rank. For example, the rank (and therefore, the number of transmission layers) assigned to a particular UE on the downlink may be determined based on the rank indicator (RI) transmitted from the UE to the base station. The RI may be determined based on the antenna configuration (e.g., the number of transmit and receive antennas) and a measured signal-to-interference-and-noise ratio (SINR) on each of the receive antennas. The RI may indicate, for example, the number of layers that may be supported under the current channel conditions. The base station may use the RI, along with resource information (e.g., the available resources and amount of data to be scheduled for the UE) , to assign a transmission rank to the UE.

On the uplink, at UE 120, a transmit processor 364 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 380. The transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the demodulators in transceivers 354a through 354r (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 334, processed by the modulators 332, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by the UE 120. The receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.

FIG. 4 is a diagram showing an example of a frame format 400 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 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. 4. 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. The SS block can be transmitted up to sixty-four times, for example, with up to sixty-four different beam directions for mmW. The up to sixty-four transmissions of the SS block are referred to as the SS burst set. SS blocks in an SS burst set are transmitted in the same frequency region, while SS blocks in different SS bursts sets can be transmitted at different frequency locations.

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 CSI Report Configuration

Channel state information (CSI) may refer to channel properties of a communication link. The CSI may represent the combined effects of, for example, scattering, fading, and power decay with distance between a transmitter and receiver. Channel estimation using pilots, such as CSI reference signals (CSI-RS) , may be performed to determine these effects on the channel. CSI may be used 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. CSI is typically measured at the receiver, quantized, and fed back to the transmitter.

The time and frequency resources that can be used by the UE to report CSI are controlled by a base station (e.g., gNB) . CSI may include Channel Quality Indicator (CQI) , precoding matrix indicator (PMI) , CSI-RS resource indicator (CRI) , SS/PBCH Block Resource indicator (SSBRI) , layer indicator (LI) , rank indicator (RI) and/or L1-RSRP. However, as described below, additional or other information may be included in the report.

The base station may configure UEs for CSI reporting. For example, the BS configures the UE with a CSI report configuration or with multiple CSI report configurations. The CSI report configuration may be provided to the UE via higher layer signaling, such as radio resource control (RRC) signaling (e.g., CSI-ReportConfig) . The CSI report configuration may be associated with CSI-RS resources for channel measurement (CM) , interference measurement (IM) , or both. The CSI report configuration configures CSI-RS resources for measurement (e.g., CSI-ResourceConfig) . The CSI-RS resources provide the UE with the configuration of CSI-RS ports, or CSI-RS port groups, mapped to time and frequency resources (e.g., resource elements (REs) ) . CSI-RS resources can be zero power (ZP) or non-zero power (NZP) resources. At least one NZP CSI-RS resource may be configured for CM.

For the Type II codebook, the PMI is a linear combination of beams; it has a subset of orthogonal beams to be used for linear combination and has per layer, per polarization, amplitude and phase for each beam. For the PMI of any type, there can be wideband (WB) PMI and/or subband (SB) PMI as configured.

The CSI report configuration may configure the UE for aperiodic, periodic, or semi-persistent CSI reporting. For periodic CSI, the UE may be configured with periodic CSI-RS resources. Periodic CSI on physical uplink control channel (PUCCH) may be triggered via RRC. Semi-persistent CSI reporting on physical uplink control channel (PUCCH) may be activated via a medium access control (MAC) control element (CE) . For aperiodic and semi-persistent CSI on the physical uplink shared channel (PUSCH) , the BS may signal the UE a CSI report trigger indicating for the UE to send a CSI report for one or more CSI-RS resources, or configuring the CSI-RS report trigger state (e.g., CSI-AperiodicTriggerStateList and CSI-SemiPersistentOnPUSCH-TriggerStateList) . The CSI report trigger for aperiodic CSI and semi-persistent CSI on PUSCH may be provided via downlink control information (DCI) .

The UE may report the CSI feedback based on the CSI report configuration and the CSI report trigger. For example, the UE may measure the channel on which the triggered CSI-RS resources (associated with the CSI report configuration) is conveyed. Based on the measurements, the UE may select a preferred CSI-RS resource. The UE reports the CSI feedback for the selected CSI-RS resource. LI may be calculated conditioned on the reported CQI, PMI, RI and CRI; CQI may be calculated conditioned on the reported PMI, RI and CRI; PMI may be calculated conditioned on the reported RI and CRI; and RI may be calculated conditioned on the reported CRI.

Each CSI report configuration may be associated with a single downlink bandwidth part (BWP) . The CSI report setting configuration may define a CSI reporting band as a subset of subbands of the BWP. The associated DL BWP may indicated by a higher layer parameter (e.g., bwp-Id) in the CSI report configuration for channel measurement and contains parameter (s) for one CSI reporting band, such as codebook configuration, time-domain behavior, frequency granularity for CSI, measurement restriction configurations, and the CSI-related quantities to be reported by the UE. Each CSI resource setting may be located in the DL BWP identified by the higher layer parameter, and all CSI resource settings may be linked to a CSI report setting have the same DL BWP.

In certain systems, the UE can be configured via higher layer signaling (e.g., in the CSI report configuration) with one out of two possible subband sizes (e.g., reportFreqConfiguration contained in a CSI-ReportConfig) which indicates a frequency granularity of the CSI report, where a subband may be defined as

contiguous physical resource blocks (PRBs) and depends on the total number of PRBs in the bandwidth part. The UE may further receive an indication of the subbands for which the CSI feedback is requested. In some examples, a subband mask is configured for the requested subbands for CSI reporting. The UE computes precoders for each requested subband and finds the PMI that matches the computed precoder on each of the subbands.

Compressed CSI Feedback Coefficient Reporting

As discussed above, a user equipment (UE) may be configured for channel state information (CSI) reporting, for example, by receiving a CSI configuration message from the base station. In certain systems (e.g., 3GPP Release 15 5G NR) , the UE may be configured to report at least a Type II precoder across configured frequency domain (FD) units. For example, the precoder matrix W _r for layer r includes the W ₁ matrix, reporting a subest of selected beams using spatial compression and the W _2, r matrix, reporting (for cross-polarization) the linear combination coefficients for the selected beams (2L) across the configured FD units:

where

where b _i is the selected beam, c _i is the set of linear combination coefficients (i.e., entries of W _2, r matrix) , L is the number of selected spatial beams, and N ₃ corresponds to the number of frequency units (e.g., subbands, resource blocks (RBs) , etc. ) . In certain configurations, L is RRC configured. The precoder is based on a linear combination of DFT beams. The Type II codebook may improve MU-MIMO performance. In some configurations considering there are two polarizations, the W _2, r matrix has size 2L X N ₃.

In certain systems (e.g., Rel-16 5G NR) , the UE may be configured to report FD compressed precoder feedback to reduce overhead of the CSI report. As shown in FIG. 5, the precoder matrix (W _2, i) for layer i with i=0, 1 may use an FD compression

matrix to compress the precoder matrix into

matrix size to 2L X M (where M is network configured and communicated in the CSI configuration message via RRC or DCI, and M < N ₃) given as:

Where the precoder matrix W _i (not shown) has P = 2N ₁N ₂ rows (spatial domain, number of ports) and N ₃ columns (frequency-domain compression unit containing RBs or reporting sub-bands) , and where M bases are selected for each of layer 0 and layer 1 independently. The

matrix 520 consists of the linear combination coefficients (amplitude and co-phasing) , where each element represents the coefficient of a tap for a beam. The

matrix 520 as shown is defined by size 2L X M, where one row corresponds to one spatial beam in W ₁ (not shown) of size P X 2L (where L is network configured via RRC) , and one entry therein represents the coefficient of one tap for this spatial beam. The UE may be configured to report (e.g., CSI report) a subset K ₀ < 2LM of the linear combination coefficients of the

matrix 520. For example, the UE may report K _NZ, i < K ₀ coefficients (where K _NZ, i corresponds to a maximum number of non-zero coefficients for layer-i with i=0 or 1, and K ₀ is network configured via RRC) illustrated as shaded squares (unreported coefficients are set to zero) . In some configurations, an entry in the

matrix 520 corresponds to a row of

matrix 530. In the example shown, both the

matrix 520 at layer 0 and the

matrix 550 at layer 1 are 2L X M.

The

matrix 530 is composed of the basis vectors (each row is a basis vector) used to perform compression in frequency domain. In the example shown, both the

matrix 530 at layer 0 and the

matrix 560 at layer 1 include M=4 FD basis (illustrated as shaded rows) from N ₃ candidate DFT basis. In some configurations, the UE may report a subset of selected basis of the

matrix via CSI report. The M bases specifically selected at layer 0 and layer 1. That is, the M bases selected at layer 0 can be same/partially-overlapped/non-overlapped with the M bases selected at layer 1.

Example Decoupled Port Selection and Coefficients Reporting

Some deployments (e.g., NR Release 16 and 17 systems) support enhancements to CSI based feedback that are designed to exploit directional (angle) and delay reciprocity (meaning the same or similar conditions may be assumed to be observed on the uplink and downlink) . FIGs. 6 and 7 illustrate examples of such CSI based feedback where a gNB obtains the following terms based on a combination of SRS measurements taken at the gNB and feedback from the UE:

b _i: spatial domain basis;

frequency domain basis; and

c _i, m: linear combination coefficients.

FIG. 6 is a call flow diagram illustrating an example of Type II port-selection CSI feedback (according to Release 16) . The UE transmits SRS that the gNB measures to determine a spatial domain basis (b _i) . Assuming spatial reciprocity, the gNB precodes CSI-RS via the spatial domain basis (b _i) , wherein each CSI-RS port may be precoded via a particular spatial domain basis. Based on measurements of the precoded CSI-RS, the UE determines preferred CSI-RS ports and reports them and also reports other terms (c _i, m and

) used to combine the preferred CSI-RS ports.

The term CSI-RS port refers to an antenna port used for CSI-RS transmission. An antenna port is a logical concept related to physical layer (L1) , rather than an actual physical RF antenna. According to the 3GPP specification definition, an antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. In other words, each individual downlink transmission is carried out from a specific antenna port, the identity of which is known to the UE and the UE can assume that two transmitted signals have experienced the same radio channel if and only if they are transmitted from the same antenna port. The mapping of antenna ports to physical antennas is generally controlled by beam forming as a certain beam needs to transmits the signal on certain antenna ports to form a desired beam. As such, it is possible that two antenna ports may be mapped to one physical antenna port or that a single antenna port may be mapped to multiple physical antenna ports.

FIG. 7 is a call flow diagram illustrating another example of Type II CSI feedback (according to Release 17) . In this case, the gNB determines both (b _i) and

based on SRS measurements. Assuming both spatial and delay reciprocity, the gNB precodes CSI-RS via the spatial domain basis (b _i) and the frequency domain basis

wherein each CSI-RS port maybe precoded via a particular pair of a spatial domain basis and a frequency domain basis. Based on measurements of the precoded CSI-RS, the UE determines preferred CSI-RS ports and reports them and also reports c _i, m used to combine the preferred CSI-RS ports.

In scenarios where there is an ideal spatial and delay reciprocity in the uplink and downlink frequency band, such as time division duplexing (TDD) scenarios, the CSI reporting of FIG. 7 may have certain benefits. Examples of such benefits include lower reporting overhead, lower UE complexity, and higher performance due to finer resolution of frequency domain basis and higher performance due to better spatial and frequency bases (gNB can use bases other than DFT bases, e.g., SVD bases, to gain more performance benefit) .

For the frequency selective precoding shown in FIG. 7, on an FD unit (RB or subband) , the precoder of a CSI-RS port is formed by a pair of an SD basis (or spatial domain transmission filter) b _i and an FD basis (frequency domain transmission filter/weight) f _m. When generating a wideband (WB) CSI report, for a given port p, the UE observes:

on FD unit n;

based on which the UE calculates CSI. In this equation, H is the wireless channel between UE and gNB without precoding, where i (p) and m (p) denote the indices of the spatial and frequency bases applied on port p, respectively.

For each layer, the UE selects a subset of total ports, and reports a single coefficient per port across the frequency band. The PMI for a certain layer on any of the N ₃ FD units is given as:

where

is of size P×1 with only one “1” in row i _k, P is the total number of CSI-RS ports. The UE reports

and

or a subset of

wherein the unreported coefficients are set to 0, K ₀ is the maximum number of ports allowed to be selected for linear combination.

As illustrated in FIG. 8A, in current standards, the CSI-RS port index in each resource starts from 3000. As shown in FIG. 8B, the UE calculates CQI assuming a virtual PDSCH:

and the actual precoder of the virtual PDSCH is given as:

CSI-RS port precoding may be less than ideal for various reasons. In certain conditions, such as frequency division duplexing, the UL and DL band are mismatched so that UL/DL reciprocity may be poor which may impact the accuracy of precoding. For example, the gNB may determine the SD/FD combination used to precode each CSI-RS port. However, the UL/DL reciprocity may be poor considering UL/DL band mismatch and Rx/Tx calibration errors and/or practical sounding errors.

Example Flexible CSI-RS resource set, CSI-RS resource, or CSI-RS port activation

FIG. 9 illustrates an example CSI-RS report configuration. As illustrated, the configuration may indicate, for a CSI report/resource setting, one non zero-power CSI-RS (NZP-CSI-RS) resource setting for channel measurement and zero or more (e.g., 0-2) resources for interference measurement (IM) . If one IM resource (IMR) is configured, the IMR can be configured as either CSI-IM (zero-power) setting or NZP-CSI-RS setting. If two IMRs, these resources may be configured as CSI-IM setting plus NZP CSI-RS settings. For NZP-CSI-RS IMR, any single port in the activated resources may be assumed as an interference layer, in which case, a UE may be configured to aggregate all the interference layers in CSI calculation. As indicated in FIG. 9, there may be a resource-wise association between CMR and CSI-IM resources.

In some cases, aperiodic CSI reporting may be triggered, for example, via a mechanism involving radio resource control (RRC) , medium access control (MAC) control element (CE) , and downlink control information (DCI) . For example, RRC signaling may be used to configure up to 128 trigger states per serving cell, where each trigger state comprises one or more CSI report configurations. In each trigger state, RRC signaling may also be used to activate one resource set from the multiple resource sets of each CSI report configurations. In some cases, a MAC CE may be used to downselect 64 trigger states from the 128 states, while a DCI may be used to trigger one trigger state from the (downselected) 64 states (e.g., via a 6-bit CSI-request in UL-related DCI, such as DCI format 0_1) .

The conventional mechanism of CSI-RS report configuration with fixed association between CSI report and CSI-RS resource may be less than optimal in certain scenarios. For example, the fixed association may not be sufficiently flexible for the sharing of CSI-RS resources (resource/resource sets and CSI-RS ports) among UEs, particularly when the CSI-RS transmissions are beamformed.

For example, FIG. 10 shows an illustration of candidate frequency domain basis index and spatial domain basis index. The gNB may select some spatial domain-frequency domain (SD-FD) pairs to transmit CSI-RS intended to UE0 and some other pairs to transmit CSI-RS intended to UE1. When channel conditions change, the precoders used (for CSI-RS ports) may change, which can impact the level of port-sharing. For example, with the set of precoders selected for UE0 CSI-RS and UE1 CSI-RS shown in the first diagram 1000, 16 ports can be shared by UE0 and UE1. When the precoders change as shown in the second diagram 1050, on the other hand, only 8 ports can be shared by UE0 and UE1.

One approach to achieve more optimal CSI-RS resource association is shown in FIG. 11A. In this example, the gNB may configure a CSI report setting 0 for UE0 wherein the CSI report 0 is associated a CSI-RS resource 0 with precoders selected for UE0. At the same time, the gNB may configure a CSI report setting 0 for UE1 wherein the CSI report 0 is associated a CSI-RS resource 0 with precoders selected for UE1. When the proper precoders for UE0 and UE1 change, the gNB may send RRC reconfiguration change the CSI-RS resources or ports associated with a CSI-RS report. Unfortunately, this approach results in large overhead and high latency.

Another approach to achieve more optimal CSI-RS resource association is shown in FIG. 11B. In this example, the gNB may configure two CSI report settings to UE0, wherein CSI report 0 is associated with a first set of CSI-RS resources or ports transmitted using a first set of SD-FD pairs as precoders and CSI report 1 is associated with a second set of CSI-RS resources or ports transmitted using a second set of SD-FD pairs as precoders. Similarly, the gNB may configure two CSI report settings to UE1, each with a particular CSI-RS resources. When channel changes, the gNB may selectively send a CSI request to trigger CSI report 0 or CSI report 1. This approach consumes a large number of CSI report configurations.

Aspects of the present disclosure, however, provide a mechanism to allow port-sharing more dynamically. In some cases, to support flexible CSI-RS ports sharing, a UE is configured with a pool of CSI-RS resources and a network entity (e.g., gNB) may use dynamic signaling to activate a subset of the CSI-RS resource pool.

FIG. 12 illustrates example operations 1200 for wireless communication by a UE. For example, operations 1200 may be performed by a UE 120 (of FIG. 1 or FIG. 3) for CSI reporting, in accordance with certain aspects of the present disclosure.

Operations 1200 begin, at 1202, by the UE receiving a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report. At 1204, the UE receives dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources. As described in greater detail below, the configuration may be via RRC signaling, while the dynamic signaling activating the subset of CSI-RS ports or resources may be via a MAC CE or DCI signaling.

At 1206, the UE performs CSI measurement using the activated subset of CSI-RS ports or resources. At 1208, the UE transmits a report based on the CSI measurement. The exact resources used to calculate the CSI measurements may depend on the configuration and activation scheme. For example, for one scheme, the UE may calculate CSI using the activated ports or port-groups, for another scheme, the UE may calculate CSI using all ports within the activate resources and not report a CSI resource indicator (CRI) .

FIG. 13 illustrates example operations 1300 that may be considered complementary to operations 1200 of FIG. 12. For example, operations 1300 may be performed by a network entity (e.g., a base station, such as an eNB or gNB) , to configure and receive CSI reports from a UE (performing operations 1200 of FIG. 12) .

Operations 1300 begin, at 1302, by the network entity sending to the user equipment (UE) a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report. At 1304, the network entity sends to the UE dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources. At 1306, the network entity receives a CSI report based on CSI measurements taken by the UE using the activated subset of CSI-RS ports or resources.

FIGs. 14-17 illustrate examples of the flexible CSI-RS resource and/or port activation that may be achieved using operations of FIGs. 12 and 13. Each of the examples illustrate a type of CSI-RS configuration and how a network entity may dynamically signal a change in CSI-RS resources/ports, for example, via DCI and/or MAC CE signaling.

In some cases, the UE may further receive an indication of CSI-RS port-grouping or CSI-RS resource-grouping. Such grouping may be signaled dynamically (e.g., via RRC or MAC-CE) or the grouping may be fixed or based on a CSI-RS resource mapping or code division multiplexing (CDM) group. For example, the CSI-RS ports transmitted in the same CDM group may be said to be in the same group. In another example, the CSI-RS ports transmitted in the same OFDM symbol may be said to be in the same group. In either case, the UE may receive a MAC CE/DCI to activate a subset of the CSI-RS port/resource groups.

As an alternative (or in addition) , a UE may further receive an indication of CSI-RS port-patterns or resource-patterns via RRC or MAC CE; the UE receives a MAC CE/DCI to activate one of the port pattern or resource-pattern. The size of grouping or patterns may represent a trade-off between flexibility and configuration overhead. For example, considering a total N ports, and M groups, there would be O=N/M ports per resource. The sharing of ports should be multiple of O, while the configuration overhead is a function of M (e.g., using a size-M bitmap) .

In some cases, the plurality of CSI-RS ports may correspond to CSI-RS ports within a CSI-RS resource.

FIGs. 14A and 14B illustrate an example of CSI-RS port grouping where a UE is configured (e.g., via RRC signaling) such that every 4 ports are grouped, for a total of 16 groups, with MAC CE or DCI activating a subset of the 16 groups.

In the example shown in FIG. 14A, at a first time, the UE0 receives a MAC CE (MAC CE1) or DCI1 that activates groups 0-3 (such at ports 0-15 are activated) , while UE1 receives a MAC CE1 or DCI1 that activates groups 2-5 (such that ports 8-23 are activated) . Thus, there are 8 shared (overlapping) ports in this example.

In the example shown in FIG. 14B, at a later time, the UE0 receives a MAC CE (MAC CE2) or DCI2 that activates groups 1-6 (such at ports 4-27 are activated) , while UE1 receives a MAC CE2 or DCI2 that activates groups 2-7 (such that ports 8-31 are activated) . Thus, there are 16 overlapping ports in this example. Herein, the MAC CE1 received by UE0 and UE1 may not be the same MAC CE signaling because MAC CE is unicast (i.e., UE-specific) . The DCI received by UE0 and UE1 can be different if the DCI is UE-specific. The DCI received by UE0 and UE1 can be same if the DCI is a group common DCI.

In such cases as shown in FIGs. 14A and 14B, RRC may be used to configure trigger state containing an A-CSI report and also to select a CSI-RS resource set from the resource setting associated to the A-CSI report. All the resources within the set are selected and will be used for CSI measurement. There may be only 1 resource in the selected set. As noted above, the UE may receive a MAC CE or DCI to activate a subset of the plurality of the CSI-RS ports within each of the selected set.

In some case, the UE may determine a port-grouping or a port-pattern based on a RRC configuration or based on the CDM type (e.g., ports within same CDM group belong to the same group) or resource mapping (e.g., ports transmitted on the same OFDM symbol belong to the same group) . In such a case, the UE may receive a MAC CE or DCI indicating the activated ports/port groups or indicating a selected port-pattern. In such cases, the UE calculates CSI using the activated ports or port-groups.

In some cases, the plurality of CSI-RS ports may correspond to CSI-RS ports across all CSI-RS resource within a resource set. FIGs. 15A and 15B illustrate an example of CSI-RS resource grouping where a UE is configured (e.g., via RRC signaling) such that 4 resources are grouped, for a total of 16 groups, again with MAC CE or DCI activating a subset of the 16 groups.

In the example shown in FIG. 15A, at a first time, the UE0 receives a MAC CE (MAC CE1) of DCI1 that activates

resource groups

0, 1, 3, 4, 6, 8, 9, and 10, while UE1 receives a MAC CE1 or DCI1 that activates

groups

6, 7, 8, 10, 11, 12, 14, 15.

In the example shown in FIG. 15B, at a later time, the UE0 receives a MAC CE (MAC CE2) or DCI2 that activates resource groups 1-4 and 6-9, while UE1 receives a MAC CE2 or DCI2 that activates groups 4-8 and 10-12. Herein, the MAC CE1 received by UE0 and UE1 may not be the same MAC CE signaling because MAC CE is unicast (i.e., UE-specific) . The DCI received by UE0 and UE1 can be different if the DCI is UE-specific. The DCI received by UE0 and UE1 can be same if the DCI is a group common DCI.

In this case, too, RRC signaling may be used to configure trigger state containing an A-CSI report, also select a CSI-RS resource set from the resource setting associated to the A-CSI report. All the resources within the set may be selected and used for CSI measurement. In some cases, there may be only one resource in a selected set.

The UE may receive MAC CE or DCI to activate a subset of plurality of resources within the selected set. The UE may determine a resource-grouping or resource-pattern based on a RRC configuration (e.g., the UE may receive a MAC CE indicating the activated resource groups or resource-pattern) . As an alternative, the UE may determine resource-grouping or a resource pattern based on CSI-RS resource mapping (e.g., the grouping/pattern may be determined based on CSI-RS resources transmitted on the same OFDM symbol belong to the same resource group) .

In such cases, the UE may calculate CSI using all ports within the activate resources and the UE may send CRI reporting. Each resource may contain a single port or multiple ports.

As noted above, the grouping of ports can be configured via RRC or MACCE or determined based on CDM group or resource mapping. In some cases, there may be no resource grouping needed.

FIG. 16A illustrates an example with 16 CSI-RS resources in the resource set, where each resource has 4 ports and there is no grouping.

16 CSI-RS resources are configured. In the illustrated example, UE 0 receives a UE-specific MACCE 1 for UE 0 indicating 4-

port resources

0, 1, 3, 4, 6, 8, 9, and 10 are activated, while UE1 sees 4-

port resources

6, 7, 8, 10, 11, 12, 14, and 15 are activated.

As illustrated in FIG. 16B, upon receiving a UE-specific MAC CE 2, UE 0 sees 4-port resources 1-4 and 6-9 are activated, while UE 1 sees 4-port resources 4-8 and 10-12 are activated. Herein, the MAC CE1 received by UE0 and UE1 may not be the same MAC CE signaling because MAC CE is unicast (i.e., UE-specific) . The DCI received by UE0 and UE1 can be different if the DCI is UE-specific. The DCI received by UE0 and UE1 can be same if the DCI is a group common DCI.

FIG. 17A illustrates an example with 64 CSI-RS resources in the resource set, where each resource has a single port and 1 resource is in a group.

As illustrated in FIG. 17A, upon receiving UE-specific MAC CE 1, UE 0 sees single-

port resources

0, 3, 5, 9, 12, 13, 15-18, 20-22, 45-25, 28-29, 31, 33, 35-36, 38, 42, 45, 49 are activated, while UE 1 sees single-port resources 24, 27, 30-31, 33-34, 36, 38, 40-43, 45-47, 49-51, 54-58, 61-63 are activated.

As illustrated in FIG. 17B, at a later time, upon receiving UE-specific MAC CE 2, UE 0 sees single-

port resources

4, 8, 11-12, 15-18, 20-26, 28-35 are activated while UE 1 sees single-port resources 15, 18, 21-27, 29-35, 37-39, 41-42, 45, 48, 52 are activated. Herein, the MACCE1 received by UE0 and UE1 may not be the same MACCE signaling because MACCE is unicast (i.e., UE-specific) . The DCI received by UE0 and UE1 can be different if the DCI is UE-specific. The DCI received by UE0 and UE1 can be same if the DCI is a group common DCI.

In some cases, the plurality of CSI-RS ports may correspond to CSI-RS ports across all CSI-RS resources in the CSI-RS resource set in the CSI-RS resource setting. In this case, RRC may be used to configure trigger state containing an A-CSI report, where a resource set from the resource setting is selected to be associated to the A-CSI report. All the resources within the set may be selected and will be used for CSI measurement.

In some cases, to activate CSI-RS resources (groups/patterns) , a UE may receive a group common DCI (UE-group specific DCI, e.g., DCI 2_0 ～ DCI 2_6) to activate a subset of ports/port-groups/resource/resource groups or change the activated resource set. In such cases, the group common DCI may include B blocks (e.g., block number 1, block number 2, …, block number B) . Each UE may be configured with 1 block by RRC signaling –RRC to configure UE a starting bit position for reading the group common DCI.

In each block, there may be various options for activation commands. For example, according to one option, an attach activation command may be used and sent with report or resource configuration. A first field of the block may include a CSI report-ID or CSI resource ID. If this block includes a report ID, then the serving cell of the corresponding report is the cell of receiving the group DCI. If the UE has a resource ID, the serving cell of the corresponding resource and CSI measurement is performed.

A second field, may include an activation command to activate a subset of ports/port-groups/resource/resource groups or change the activated resource set associated with the CSI report ID or resource ID.

According to another option, each attach activation command may be sent with A-CSI request (i.e., aperiodic CSI trigger state) . In such cases, the first field may trigger a A-CSI trigger state comprising N A-CSI reports, and the serving cell of the trigger state is the cell of receiving the group-common DCI. A second field may be used to carry N activation commands, where each activation command applies to a respective CSI report in the trigger state.

For the second option, the UE may report the N A-CSIs triggered by the A-CSI request using a predefined PUSCH/PUCCH resource. For either the first or second options, the bitwidth of the activation command may be determined based on the granularity of ports/resources (e.g., based on the number of port-groups, port patterns, resource-groups or resource patterns) .

According to current standards, in any slot, the UE is not expected to have more active CSI-RS ports or active CSI-RS resources in active BWPs than reported as capability. An NZP CSI-RS resource is typically active for a duration of time defined (e.g., depending on whether it is periodic, aperiodic, or semi-persistent) as follows. For aperiodic CSI-RS, the active duration starts from the end of the PDCCH containing the request and ends at the end of the PUSCH containing the report associated with this aperiodic CSI-RS. For semi-persistent CSI-RS, the active duration starts from the end of when the activation command is applied, and ends at the end of when the deactivation command is applied. For periodic CSI-RS, the active duration starts when the periodic CSI-RS is configured by higher layer signaling, and ends when the periodic CSI-RS configuration is released.

According to aspects of the present disclosure, the UE may not expect to activate more than X ports (e.g., for a CSI report, X=32) . In some cases, the X value is reported as UE capability. For “active CSI-RS ports” , for all of the cases described herein, the number of active ports may only be counted as the ports activated by the port/port-group/resource/resource-group/resource set activation command discussed herein. For “active CSI-RS resources” , where all ports across the resources are used CSI calculation, the active resource may be counted as a single port.

As described herein, aspects of the present disclosure may help provide efficient CSI reporting, in terms of CSI-RS report configuration/re-configuration overhead, as well as reduced latency.

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. For example, the various processor shown in FIG. 3 may be configured to perform

operations

1200 and 1300 of FIGs. 12 and 13.

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 terminal 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 (e.g., instructions for performing the operations described herein and illustrated in FIGs. 12 and 13) .

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 for wireless communications by a user equipment (UE) , comprising:

receiving a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of channel state information reference signal (CSI-RS) ports or resources associated with a CSI report;

receiving dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources;

performing CSI measurement using the activated subset of CSI-RS ports or resources; and

transmitting a report based on the CSI measurement.
The method of claim 1, wherein the dynamic signaling comprises at least one of a medium access control (MAC) control element (CE) or downlink control information (DCI) signaling.
The method of claim 1, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource; and

the dynamic signaling activates a plurality of CSI-RS ports within a same CSI-RS resource.
The method of claim 3, further comprising:

determining a grouping of CSI-RS ports or a pattern of CSI-RS ports, wherein the dynamic signaling activates a subset of CSI-RS port groups or patterns within the same CSI-RS resource.
The method of claim 4, wherein the grouping or pattern is indicated via at least one of a medium access control (MAC) control element (CE) or radio resource control (RRC) signaling or determined via code division multiplexing (CDM) groups or determined by CSI-RS resource mapping.
The method of claim 4, wherein the UE calculates CSI using the activated CSI-RS ports, CSI-RS port groups, or CSI-RS port patterns.
The method of claim 1, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource;

the plurality of CSI-RS ports comprise CSI-RS ports across CSI-RS resources within a selected CSI-RS resource set; and

the dynamic signaling activates a subset of CSI-RS resources within the selected set.
The method of claim 7, further comprising:

determining a grouping of CSI-RS resources or pattern of CSI-RS resources, wherein the dynamic signaling activates a subset of CSI-RS resource groups or patterns within the selected CSI-RS resource set.
The method of claim 8, wherein the grouping or pattern is indicated via at least one of a medium access control (MAC) control element (CE) or radio resource control (RRC) signaling or determined by CSI-RS resource mapping.
The method of claim 7, wherein the UE calculates CSI using all CSI-RS ports within the activated CSI-RS resources.
The method of claim 7, wherein each resource may contain a single or multiple CSI-RS port.
The method of claim 1, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource;

the plurality of CSI-RS ports comprise CSI-RS ports across the CSI-RS resources sets; and

the dynamic signaling activates at least one of the CSI-RS resource sets.
The method of claim 12, wherein the UE calculates CSI using all CSI-RS resources and CSI-RS ports within the activated CSI-RS resource set.
The method of claim 1, wherein:

the dynamic signaling comprises a group common downlink control information (DCI) including a plurality of blocks and each block activates a particular subset of the plurality of the CSI-RS ports or resources or resource set; and

the UE is assigned a starting bit position for one of the blocks.
The method of claim 14, wherein a block for a UE has an activation command with a report or resource configuration.
The method of claim 15, wherein the block for the UE comprises at least:

a first field with a CSI report ID or CSI resource ID; and

a second field with an activation command to activate or change a subset of the plurality of the CSI-RS ports or resources or resource set associated with the CSI report ID or CSI resource ID.
The method of claim 16, wherein:

if the first field has a CSI report ID, the serving cell of the corresponding report is the cell of the group receiving the group DCI; or

if the first field has a resource ID, the serving cell of the corresponding resource is the cell where CSI measurement is performed.
The method of claim 14, wherein a block for a UE has an activation command with an aperiodic CSI (A-CSI) request.
The method of claim 18, wherein the block for the UE comprises at least:

a first field with the A-CSI request to trigger an A-CSI trigger state comprising one or more A-CSI CSI reports and a serving cell of the trigger state is the cell of receiving the group-common DCI; and

a second field with one or more activation commands, each applicable to a respective A-CSI report in the A-CSI trigger state activating or changing a subset of the plurality of the CSI-RS ports or resources or resource set associated with the respective CSI report.
The method of claim 18, further comprising reporting the A-CSIs triggered by the A-CSI request using predefined a predefined physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH) resource.
The method of any of claims 15-20, wherein a bitwidth of an activation command is determined based on a granularity of activated CSI-RS ports or CSI-RS resources.
The method of claim 1, wherein:

the UE only expects to have no more than a number of activated ports for a CSI report, wherein the number of activated ports is reported as UE capability, or configured by network, or combination thereof.
The method of claim 1, further comprising at least one of:

determining the number of active ports based on the number of ports in the activated subset of the plurality of ports or resources; or

if the dynamic signaling activates CSI-RS resources where all CSI-RS ports across the activated CSI-RS resources are used for CSI-RS calculation, the UE only counts only one resource as active resources.
A method for wireless communications by a network entity, comprising:

sending a user equipment (UE) a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of channel state information reference signal (CSI-RS) ports or resources associated with a CSI report;

sending the UE dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources; and

receiving a CSI report based on CSI measurements taken by the UE using the activated subset of CSI-RS ports or resources.
The method of claim 24, wherein the dynamic signaling comprises at least one of a medium access control (MAC) control element (CE) or downlink control information (DCI) signaling.
The method of claim 24, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource; and

the dynamic signaling activates a plurality of CSI-RS ports within a same CSI-RS resource.
The method of claim 26, further comprising:

configuring the UE with a grouping of CSI-RS ports or a pattern of CSI-RS ports, wherein the dynamic signaling activates a subset of CSI-RS port groups or patterns within the same CSI-RS resource.
The method of claim 27, wherein the grouping or pattern is indicated via at least one of a medium access control (MAC) control element (CE) or radio resource control (RRC) signaling or determined via code division multiplexing (CDM) groups or determined by CSI-RS resource mapping.
The method of claim 24, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource;

the plurality of CSI-RS ports comprise CSI-RS ports across CSI-RS resources within a selected CSI-RS resource set; and

the dynamic signaling activates a subset of CSI-RS resources within the selected set.
The method of claim 29, further comprising:

configuring the UE with a grouping of CSI-RS resources or pattern of CSI-RS resources, wherein the dynamic signaling activates a subset of CSI-RS resource groups or patterns within the selected CSI-RS resource set.
The method of claim 30, wherein the grouping or pattern is indicated via at least one of a medium access control (MAC) control element (CE) or radio resource control (RRC) signaling or determined by CSI-RS resource mapping.
The method of claim 29, wherein each resource may contain a single or multiple CSI-RS port.
The method of claim 24, wherein:

the configuration indicates one or more CSI-RS resource sets, each CSI-RS set having one or more CSI-RS resource;

the plurality of CSI-RS ports comprise CSI-RS ports across the CSI-RS resources sets; and

the dynamic signaling activates at least one of the CSI-RS resource sets.
The method of claim 24, wherein:

the dynamic signaling comprises a group common downlink control information (DCI) including a plurality of blocks and each block activates a particular subset of the plurality of the CSI-RS ports or resources or resource set; and

the UE is assigned a starting bit position for one of the blocks.
The method of claim 34, wherein a block for a UE has an activation command with a report or resource configuration.
The method of claim 35, wherein the block for the UE comprises at least:

a first field with a CSI report ID or CSI resource ID; and

a second field with an activation command to activate or change a subset of the plurality of the CSI-RS ports or resources or resource set associated with the CSI report ID or CSI resource ID.
The method of claim 36, wherein:

if the first field has a CSI report ID, the serving cell of the corresponding report is the cell of the group receiving the group DCI; or

if the first field has a resource ID, the serving cell of the corresponding resource is the cell where CSI measurement is performed.
The method of claim 34, wherein a block for a UE has an activation command with an aperiodic CSI (A-CSI) request.
The method of claim 38, wherein the block for the UE comprises at least:

a first field with the A-CSI request to trigger an A-CSI trigger state comprising one or more A-CSI CSI reports and a serving cell of the trigger state is the cell of receiving the group-common DCI; and

a second field with one or more activation commands, each applicable to a respective A-CSI report in the A-CSI trigger state activating or changing a subset of the plurality of the CSI-RS ports or resources or resource set associated with the respective CSI report.
The method of claim 38, further comprising receiving the A-CSIs triggered by the A-CSI request using predefined a predefined physical uplink control channel

(PUCCH) or physical uplink shared channel (PUSCH) resource.
The method of any of claims 35-40, wherein a bitwidth of an activation command is determined based on a granularity of activated CSI-RS ports or CSI-RS resources.
The method of claim 24, further comprising:

determining a maximum number of activated ports the UE expects for a CSI report, wherein the maximum number of activated ports is reported as UE capability, or configured by network, or combination thereof.
The method of claim 24, further comprising at least one of:

determining the maximum number of active ports based on the number of ports in the activated subset of the plurality of ports or resources; or

if the dynamic signaling activates CSI-RS resources where all CSI-RS ports across the activated CSI-RS resources are used for CSI-RS calculation, determining that the UE only counts only one resource as active resources.
An apparatus for wireless communications by a user equipment (UE) , comprising:

means for receiving a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report;

means for receiving dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources;

means for performing CSI measurement using the activated subset of CSI-RS ports or resources; and

means for transmitting a report based on the CSI measurement.
An apparatus for wireless communications by a network entity, comprising:

means for sending a user equipment (UE) a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report;

means for sending the UE dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources; and

means for receiving a CSI report based on CSI measurements taken by the UE using the activated subset of CSI-RS ports or resources.
An apparatus for wireless communications by a user equipment (UE) , comprising:

at least one processor and a memory coupled with the processor, the processor and memory configured to

receive a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report;

receive dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources;

perform CSI measurement using the activated subset of CSI-RS ports or resources; and

transmit a report based on the CSI measurement.
An apparatus for wireless communications by a network entity, comprising:

at least one processor and a memory coupled with the processor, the processor and memory configured to

send a user equipment (UE) a configuration for channel state information (CSI) reporting, the configuration indicating a plurality of CSI-RS ports or resources associated with a CSI report;

send the UE dynamic signaling to activate a subset of the plurality of the CSI-RS ports or resources; and

receive a CSI report based on CSI measurements taken by the UE using the activated subset of CSI-RS ports or resources.