WO2021159439A1

WO2021159439A1 - Delay spread scaling

Info

Publication number: WO2021159439A1
Application number: PCT/CN2020/075201
Authority: WO
Inventors: Chenxi HAO; Yu Zhang; Alexandros MANOLAKOS; Liangming WU; Min Huang; Lei Xiao; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2020-02-14
Filing date: 2020-02-14
Publication date: 2021-08-19

Abstract

A UE is configured to receive a CSI request triggering a CSI report, where the CSI request is associated with CSI-RS resources. The UE is configured to determine that the CSI-RS resources are associated with a reference signal for tracking. The UE is configured to receive the reference signal for tracking. The UE is configured to perform CSI measurements of CSI-RS received in the CSI-RS resources based on the measurement of the reference signal for tracking. In another configuration, a UE is configured to receive a CSI-RS report configuration associated with CSI-RS resources, where the configuration includes an indication of QCL information of each of the CSI-RS resources. The UE is configured to receive an indication of a delay spread scaling factor. The UE is configured to perform a CSI measurement of CSI-RS received in the CSI-RS resources based on the QCL information and the delay spread scaling factor.

Description

DELAY SPREAD SCALING

BACKGROUND

Technical Field

The present disclosure relates generally to communication systems, and more particularly, to delay spread scaling in a channel estimation in a 5G New Radio (NR) based communication system.

Introduction

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

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. An example telecommunication standard is 5G NR. 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT) ) , and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB) , massive machine type communications (mMTC) , and ultra-reliable low latency communications (URLLC) . Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at a user equipment (UE) . The device may be a processor and/or modem at the UE or the UE itself. The device is configured to receive a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources. The device is configured to determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking. The device is configured to receive the one or more reference signal for tracking. The device is configured to perform CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.

In another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at the UE. The device may be a processor and/or modem at the UE or the UE itself. The device is configured to receive CSI-RS report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources. The device is configured to receive an indication of a delay spread scaling factor from a base station (BS) . The device is configured to perform a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.

Further, in an aspect of the disclosure a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at a BS. The device may be a processor and/or modem at the BS or the BS itself. The device is configured to transmit, to a UE, a CSI request triggering a CSI report, the CSI request being associated with one or more CSI-RS, wherein the one or more CSI-RS resources are associated with one or more reference signal for tracking. The device is configured to transmit, to the UE, the one or more reference signal for tracking. The device is configured to receive, from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking.

Further, in another aspect of the disclosure a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at the BS. The device may be a processor and/or modem at the BS or the BS itself. The device is configured to transmit, to a UE, a CSI-RS report configuration associated with one or more CSI-RS resources, the configuration includes an indication of QCL information of each of the one or more CSI-RS resources. The device is configured to transmit, to the UE, an indication of a delay spread scaling factor. The device is configured to receive, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, the CSI measurement results being based on the QCL information and the delay spread scaling factor.

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 annexed 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, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network.

FIGs. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a first 5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame, and UL channels within a 5G/NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a BS and a user equipment (UE) in an access network.

FIG. 4 is a call flow diagram illustrating channel estimation with a spatial domain basis precoding of CSI-RS in an access network.

FIG. 5 is a call flow diagram illustrating a port-selection codebook, where a base station uses a precoder to transmit CSI-RS in an access network.

FIG. 6 is a diagram illustrating an example of a precoder set for precoding of CSI-RS in an access network.

FIG. 7 is a diagram illustrating channel estimation using CSI-RS in an access network.

FIG. 8 is a diagram illustrating transmission configuration indicator (TCI) configuration of an aperiodic CSI-RS.

FIG. 9 is a diagram illustrating channel estimation using a frequency-selective precoded CSI-RS in an access network.

FIG. 10 is a diagram illustrating one implementation of triggering an aperiodic tracking reference signal (A-TRS) with a CSI-RS resource (s) .

FIG. 11 is a diagram illustrating different implementations of triggering an A-TRS with configuration of an A-TRS setting in a CSI report configuration.

FIG. 12 is a diagram illustrating channel estimation using delay spread (DS) scaling for a frequency-selective precoded CSI-RS.

FIG. 13 is a diagram illustrating a joint indication of DS scaling and physical resource group (PRG) .

FIG. 14 is a flowchart of a method of wireless communication of a UE.

FIG. 15 is a flowchart of a method of wireless communication of a UE.

FIG. 16 is a flowchart of a method of wireless communication of a BS.

FIG. 17 is a flowchart of a method of wireless communication of a BS.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

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

By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems on a chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network 100. The wireless communications system (also referred to as a wireless wide area network (WWAN) ) includes base stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and another core network 190 (e.g., a 5G Core (5GC) ) . The base stations 102 may include macrocells (high power cellular base station) and/or small cells (low power cellular base station) . The macrocells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through first backhaul links 132 (e.g., S1 interface) . The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN) ) may interface with core network 190 through second backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity) , inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS) , subscriber and equipment trace, RAN information management (RIM) , paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or core network 190) with each other over third backhaul links 134 (e.g., X2 interface) . The third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102' may have a coverage area 110' that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs) , which may provide service to a restricted group known as a closed subscriber group (CSG) . The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations 102 /UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL) . The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell) .

Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , and a physical sidelink control channel (PSCCH) . D2D communication may be through a variety of wireless D2D communications systems, such as for example, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs 152 /AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell 102' may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP 150. The small cell 102', employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station 102, whether a small cell 102' or a large cell (e.g., macro base station) , may include and/or be referred to as an eNB, gNodeB (gNB) , or another type of base station. Some base stations, such as gNB 180 may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW /near mmW radio frequency (RF) band (e.g., 3 GHz –300 GHz) has extremely high path loss and a short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182'. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180 /UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 /UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network 190 may include a Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a Packet Switch (PS) Streaming (PSS) Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a transmit reception point (TRP) , or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA) , a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player) , a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc. ) . The UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again to FIG. 1, in certain aspects, the UE 104 and/or the base station 180 may be configured to include a channel estimation unit 140 and a delay spread scaling unit 142 for channel estimation in a 5G NR access network as described below with reference to FIGs. 4-15. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframe within a 5G/NR frame structure. FIG. 2B is a diagram 230 illustrating an example of DL channels within a 5G/NR subframe. FIG. 2C is a diagram 250 illustrating an example of a second subframe within a 5G/NR frame structure. FIG. 2D is a diagram 280 illustrating an example of UL channels within a 5G/NR subframe. The 5G/NR frame structure may be frequency division duplexed (FDD) in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for either DL or UL, or may be time division duplexed (TDD) in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by FIGs. 2A, 2C, the 5G/NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL) , where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL) . While

subframes

3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI) . Note that the description infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms) . Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission) . The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2 ^μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2 ^μ*15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGs. 2A-2D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

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

As illustrated in FIG. 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as R _x for one particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. For example, CSI-RS may be included in

REs

201, 203 and 205. The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and phase tracking RS (PT-RS) .

FIG. 2B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) , each CCE including nine RE groups (REGs) , each REG including four consecutive REs in an OFDM symbol. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE 104 to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI) . Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH) . The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS) . The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and hybrid automatic repeat request (HARQ) ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR) , a power headroom report (PHR) , and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller/processor 375. The controller/processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs) , RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release) , inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression /decompression, security (ciphering, deciphering, integrity protection, integrity verification) , and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs) , error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs) , re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs) , demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK) , quadrature phase-shift keying (QPSK) , M-phase-shift keying (M-PSK) , M-quadrature amplitude modulation (M-QAM) ) . The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.

The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression /decompression, and security (ciphering, deciphering, integrity protection, integrity verification) ; RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and the controller/processor 359 may be configured to perform aspects in connection with the channel estimation unit 140 and the delay spread scaling unit 142 of FIG. 1.

At least one of the TX processor 316, the RX processor 370, and the controller/processor 375 may be configured to perform aspects in connection with the channel estimation unit 140 and the delay spread scaling unit 142 of FIG. 1.

In a 5G NR access network, frequency-selective precoding for CSI-RS may be used. For example, a BS (e.g., the BS 180 as described above with reference to FIG. 1) may precode a CSI reference signal (RS) (CSI-RS) using a spatial domain basis and specific frequency domain basis (further described in FIGs. 4-6 below) which may facilitate overhead reduction, as a UE (e.g., the UE 104 as described above with reference to FIG. 1) may not need to report a frequency domain basis matrix to the BS.Further, such implementation may provide flexibility in port emulation (e.g., through use of different frequency domain (FD) basis as described below with reference to FIG. 6) and finer frequency domain granularity in precoding (e.g., granularity at RB level) . However, when the UE performs a channel estimation using wide-band channel estimation (WB-CE) for a frequency-selective precoded CSI, the channel estimation may be poor resulting in a low channel impulse response (CIR) (as described below with reference to FIG. 9) .

To improve the channel estimation, in one implementation, one or more CSI-RS resources may be associated with one or more reference signal for tracking. For example, an A-TRS may be transmitted with same FD-basis as the frequency-selective precoded CSI-RS (as described below with reference to FIGs. 10 and 11) . Further, in another implementation, to improve the channel estimation, the BS may configure the UE to utilize a DS scaling factor for channel estimation (as described below with reference to FIG. 12) . Further, in another implementation, the BS may transmit a joint indication the DS scaling factor and a size of a PRG to the UE (as described below with reference to FIG. 13) .

In one implementation (e.g., Rel-16 regular Type II CSI) a BS may transmit a non-precoded CSI-RS with P ports to a UE. The UE may report a CSI comprising a precoding matrix indicator (PMI) , a rank indicator (RI) and a channel quality indicator (CQI) , representing the precoder, the rank and the spectral efficiency, respectively. For each layer, the precoder across N ₃ subbands (e.g., a subband may include several RBs) is represented by a P*N ₃ matrix formed by

wherein b _i is a spatial domain basis, size P×1, f _m is a frequency domain basis of size N ₃×1, N ₃ is the number of FD units (e.g., subbands/RBs) , and c _i, m is the linear combination coefficient to combine them. For each layer, the UE may be configured to select and report L SD basis, M FD basis, and up to K ₀ non-zero coefficients (total number of coefficients is 2L*M, K ₀ <= 2LM. With L SD basis and 2 polarizations, and same L SD basis being applied to each polarization, multiplication factor is 2L not L) , with L, M and K ₀ being configured by the network (i.e., the network including the UE and the BS) . Among different layers, same L SD basis are applied, but layer-specific FD basis are reported, so are the coefficients.

FIG. 4 is a call flow diagram 400 illustrating a port-selection codebook, where a base station determines a precoder b _i using SRS and use the precoder to transmit CSI-RS. FIG. 4 includes a UE 402 and a BS 404. The UE 402 transmits an SRS 405 to the BS 404. The BS 404 may utilize the SRS 405 for determining a matrix b _i (as described below) . In another implementation (e.g., Rel-16 port-selection Type II CSI) , the network (i.e., the network including the UE 402 and the BS 404) may determine SD basis (e.g., b _i) based on the SRS 405, assuming there is reciprocity between UL and DL channels, and use the determined SD basis to transmit the precoded CSI-RS 406. If the network formulates P ports using P different SD basis, then there are P CSI-RS ports. The UE 402 may select a port and report FD basis and coefficients. For each layer, the PMI across N ₃ subbands may be given by

where v _i= [0, …, 0, 1, 0, …, 0] ^T is of size P×1 with a “1”in the i-th entry meaning that the i-th port is selected. The UE 402 may be configured to select and report L ports, M FD basis, and up to K ₀ non-zero coefficients. L, M and K ₀ may be configured by the network. Among different layers, same L ports may be applied, but layer-specific FD basis may be reported, so may be the coefficients.

FIG. 5 is a call flow diagram 500 illustrating a port-selection codebook, where a base station uses a precoder to transmit CSI-RS in an access network. FIG. 5 includes a UE 502 (e.g., the UE 104 as described above with reference to FIG. 1) and a BS 504 (e.g., the BS 180 as described above with reference to FIG. 1) . The UE 502 transmits an SRS 505 to the BS 504. The BS 504 may utilize the SRS 505 for determining a b _i and an

(as described above with reference to FIG. 4) . In one implementation (e.g., potential Rel-17 port selection Type II CSI) , the network (e.g., the network including the BS 502 and the UE 504) , may determine SD basis and FD basis based on the SRS 505 assuming reciprocity, and use the determined basis to transmit a CSI-RS 506. The network may transmit on P ports, with each CSI-RS for port being transmitted using a specific pair of SD basis and FD basis. The precoder for each subband of the N ₃ subband may be

where v _i= [0, …, 0, 1, 0, …, 0] ^T is of size P×1 with a “1” in the i-th entry meaning that the i-th port is selected. the UE 502 may report up to K ₀ ports and the corresponding coefficients. The port selection and coefficients may be reported layer-specific. The BS 504 may precode the CSI-RS 506 via b _i and

The UE 502 may transmit, to the BS 504, a CSI report 508 with a port selection (v _i and c _i) , where v _iis as described above with reference to FIG. 4, andc _i represents coeffecients (e.g., a coefficient corresponding to short term fading) . A typical use case of this CSI framework may be the scenario where the SRS transmission band and CSI-RS transmission band are mismatched, e.g., FDD system where UL and DL band are different. In this case, only the long-term channel statistics are reciprocal between UL and DL, such as angle spread and delay spread. The network may emulate CSI-RS ports using the SD and FD basis determined by exploiting the angle and delay reciprocity. The UE may only need to report some selected ports (i.e., a specific pair of SD and FD basis) and the coefficients that combine them. The benefits may include 1) overhead reduction as UE does not need to report SD and FD basis, 2) more flexibility in SD and FD basis selection (e.g., in Rel-16 regular Type II CSI, only DFT basis may be supported for SD and FD basis, but in this framework the gNB may use other basis, such as DCT, slepian basis and SVD basis, where the Slepian basis are obtained via the frequency correlation of the channel and SVD is obtained via the SVD of the frequency response of the channel) .

FIG. 6 is a diagram illustrating an example of a precoder set 600 for precoding of CSI-RS in an access network. The rows of the precoder set 600 may represent ports (e.g., Port 0, Port 1, Port 2 and Port 3 as shown in FIG. 6) . The columns of the precoder set 600 may represent FD units (e.g., FD unit 0, FD unit 1, and so on up to FD unit N ₃-1, where N ₃ is the number of FD units (or sub-bands/RBs) . ACSI-RS port on N ₃ FD units (RB or subband) is frequency selective precoded with a specific spatial domain basis and a specific FD basis, and each entry of the precoder set 600 may correspond to a specific port and a specific FD unit. For example, the first entry 602 in the first row corresponding to the precoder of port 0 applied on FD unit 0 may be

where b ₀ corresponds to spatial domain basis and

corresponds to the first entry of FD basis

Similarly, a last entry 612 in the precoder set 600 may be

where b ₁ corresponds to spatial domain basis and

corresponds to FD basis. The size of the precoder set 600 may be N _t x1, where N _t may represent a number of antennas at a base station (e.g., the BS 504 as described above with reference to FIG. 5) . There could be P ports (e.g., P=4 in the example of FIG. 6) . The BS 504 may emulate P ports, and the UE 502 (as described above with reference to FIG. 5) may select K ₀ ports out of the P ports. The UE 502 may report the associated K ₀ coefficients of the selected ports.

The frequency selective precoding of CSI-RS using the precoder set 600 may provide several advantages such as overhead reduction and lower complexity of operations at the UE 502, since the UE 502 may not need to report the FD basis (e.g.,

as described above with reference to FIGs. 4 and 5) to the BS 504. The UE 502 may only need to determine ports and coefficients (c _i) associated with each port. Further, the frequency selective precoding of CSI-RS using the precoder set 600 may provide flexibility in port emulation (e.g., through use of different FD basis such as Discrete Fourier Transform (DFT) , Discrete Cosine Transform (DCT) , Single Vector Decomposition (SVD) and Slepian basis (e.g., SVD of an FD covariance matrix) ) . Since, the UE 502 does not have to report the FD basis, the BS 504 may use an FD basis independently. Also, finer frequency domain granularity in precoding (e.g., granularity at RB level) may be achieved using the frequency selective precoding of CSI-RS using the precoder set 600.

The UE 502 may perform wideband (WB) channel estimation (CE) (WB-CE) (e.g., using FFD approach) . The UE 502 may use pilot tones at REs where a CSI-RS is transmitted for the measurement. After depatterning (e.g., descrambling, depatterning the cover code) , the UE may transform the signal to time domain and use a window to filter-out the interference and noise.

FIG. 7 is a diagram 700 illustrating a channel estimation using CSI-RS in an access network. The diagram 700 includes a two-dimensional graph with an y-axis 701 representing Amplitude and a x-axis 703 representing Taps (e.g., a time instance in delay domain) . The diagram 700 also includes a curve representing CIR 702 and a curve representing a window 704 over which channel estimation is performed. The diagram 700 represents a measurement of a downlink channel by the UE 502 (as described above with reference to FIG. 5) based on CSI-RS.

The UE 502 may derive the shape and the length of the window 704 using QCL-A (e.g., QCL -Type A that includes Doppler shift, Doppler spread, average delay and delay spread) in a TCI state of the CSI-RS. The TCI state with QCL-A may indicate the delay spread or an average delay spread. Further, the CSI-RS may have the same delay spread and average delay as a tracking reference signal (TRS, i.e., CSI-RS for tracking) or a synchronization signal block (SSB) . In one implementation, the TCI state may indicate to the UE the spatial parameters e.g., Doppler shift, Doppler spread, average delay, delay spread, and a spatial receiver (Rx) parameter.

FIG. 8 is a diagram 800 illustrating a TCI configuration of an aperiodic CSI-RS. The diagram 800 represents a computer program code, and a section 802 of the computer program code represents the TCI configuration of the aperiodic CSI-RS. For example, the TCI is configured in an associated report information of a trigger state. The TCI may include QCL Type A, B, C and D, and a reference signal of the QCL. For example, QCL-TypeA may include Doppler shift, Doppler spread, average delay and delay spread. QCL-TypeB may include Doppler shift and Doppler spread. QCL-TypeC may include Doppler shift and average delay. QCL-TypeD may include a spatial receiver (Rx) parameter e.g., a spatial receiving beam associated with CSI-RS. A corresponding channel (e.g., CSI-RS) may be QCLed (e.g., have the same spatial properties) with the QCL reference signal with the provided QCL type.

FIG. 9 is a diagram 900 illustrating channel estimation using a frequency-selective precoded CSI-RS in an access network. The diagram 900 includes a two-dimensional graph with an y-axis 901 representing Amplitude and a x-axis 903 representing Taps (e.g., a time instance in delay domain) . The diagram 900 also includes a curve representing CIR 902 (or a CSI-RS port without precoding via FD basis) , a curve representing a window 904 over which channel estimation is performed. Further, the diagram includes curves representing candidate FD basis DCT 906, Slepian 908 and DFT 910 for the frequency selective precoded CSI-RS. The curves representing FD basis, i.e., the DCT 906, the Slepian 908 and the DFT 910 may be based on a selection of the FD basis by a BS (e.g., the BS 504 as described above with reference to FIG. 5) .

For example, the candidate FD basis DFT 910 may shift the original CIR 902 as shown in diagram 900. Similarly, the candidate FD basis DCT 906 or Slepian 908 may change the shape of the CIR 902 (e.g., by convolution of CIR of channel and CIR of basis) . Similarly, using FD basis SVD for frequency selective precoding of CSI-RS may change the shape of the CIR 902, although a curve corresponding to SVD basis is not shown in FIG. 9 for the purpose of simplification.

On reusing WB-CE using a window (e.g., the window 904) based on the provided TCI-state, the channel estimation performance may be poor, as the significant path of the curves corresponding to the DCT 906, the Slepian 908, and the DFT 910 may be outside the window 904 as shown in FIG. 9.

FIG. 10 is a diagram 1000 illustrating one implementation of improving channel estimation performance by bundling a frequency-selective precoded CSI-RS with an A-TRS. In one example, an A-TRS may be triggered with a CSI-RS resource (s) . For example, triggering the A-TRS with the CSI-RS resource (s) may allow the UE 502 (as described above with reference to FIG. 5) to improve channel estimation. The A-TRS and the CSI-RS resource (e.g., non-zero power (NZP) channel measurement resource (CMR) (NZP-CMR) ) may be indicated in a report configuration. For example, when triggering a CSI request in DCI, the triggering may also trigger an A-TRS which may be transmitted with a same FD-basis as the frequency selective precoded CSI-RS. The UE 502 may obtain an average delay-spread or a max delay spread based on the A-TRS. The UE 502 may further perform channel estimation for the NZP-CMR using the window based on the average delay-spread or max delay spread measured from the A-TRS.

In one implementation, the A-TRS and the NZP-CMR may be bundled together by indicating TCI state for the NZP-CMR. For example, indicating the A-TRS as a QCL reference signal for the NZP-CMR as shown in a section 1002 and a section 1004 of a computer program code in the diagram 1000. Once the CSI report with which the CSI-RS is associated is triggered, the associated A-TRS may also be simultaneously triggered.

FIG. 11 is a diagram 1100 illustrating different implementations of triggering an A-TRS with configuration of an A-TRS setting in a CSI report configuration. Once the CSI report with which the CSI-RS is associated is triggered, the associated A-TRS may also be simultaneously triggered. The diagram 1100 includes a computer program code section 1110 representing a first implementation and a computer program code section 1150 representing a second implementation.

In the first implementation, an A-TRS setting may be configured in a CSI report configuration such that the CSI report configuration may have two CMR resource settings. For example, a first CMR resource setting for channel measurement (e.g., the NZP-CMR) , and a second CMR resource setting for delay spread measurement (e.g., the A-TRS) , as illustrated in the computer program code section 1110.

In the second implementation, an A-TRS resource set may be configured in the trigger state. For example, the trigger state may be an additional field about NZP CSI-RS resource set for delay spread measurement as shown in a computer program code sub-section 1152 and the computer program code section 1150 in FIG. 11.

Further, in another implementation, the A-TRS and NZP-CMR may be bundled by an explicit trigger of the A-TRS in the same DCI that triggers the CSI request (not shown in FIG. 11 for the purpose of simplification) .

In one or more implementations described above, the UE 502 may measure a delay spread of NZP-CMR associated with CSI request based on measurement of A-TRS.

FIG. 12 is a diagram illustrating channel estimation using DS scaling for a frequency-selective precoded CSI-RS. FIG. 12 includes a two-dimensional graph 1200 with an y-axis 1201 representing Amplitude and a x-axis 1203 representing Taps (e.g., a time instance in delay domain) . The graph 1200 also includes a curve representing CIR 1202. The graph 1200 also includes a curve representing a window without extension 1204 (similar to the window 904 as described above with reference to FIG. 9) and a window with extension 1205 over which channel estimation may be performed. The graph 1200 also includes curves representing candidate FD basis DCT 1206, Slepian 1208 and DFT 1210 for the frequency selective precoded CSI-RS. The curves representing FD basis, i.e., the DCT 1206, the Slepian 1208 and the DFT 1210 may be based on a selection of the FD basis by a BS (e.g., the BS 504 as described above with reference to FIG. 5) .

In absence of frequency-selective precoding, a UE (e.g., the UE 402 as described above with reference to FIG. 4) may be configured such that a CSI-RS is QCLed with a TRS/SSB with QCL-TypeA. To achieve channel estimation improvement with frequency-selective precoding, a UE (e.g., the UE 502 as described above with reference to FIG. 5) may be configured such that a DS may be extended by a scaling factor. For example, the BS 504 may configure the UE 502 with a DS scaling factor. The DS scaling factor may be provided to the UE 502 via RRC, or a media access control (MAC) control element (CE) (MAC-CE) , or DCI. The UE 502 may update the window without extension 1204 to the window with extension 1205 based on the DS scaling factor. In one example, the UE 502 may update the window without extension 1204 to the window with extension 1205 based on indicated TCI states.

The window with extension 1205 allows for improved channel estimation as significant path of the curves corresponding to the DCT 1206, the Slepian 1208, and the DFT 1210 are inside the window with extension 1205 as shown in FIG. 12.

FIG. 12 also includes a table 1250 to illustrate improvement in channel estimation. The table 1250 illustrates result for a signal with signal-to-noise ratio (SNR) of 4 decibel (dB) for different FD basis (DFT, DCT, and Slepian) . For example, as illustrated in table 1250, for a window without extension (e.g., the window without extension 1204) , MSE (mean square error) values for the DFT, the DCT, and the Slepian FD basis are -2 dB, -3.8 dB, and -2.1 dB, respectively. However, for a window with extension (e.g., the window with extension 1205) , the MSE values for the DFT, the DCT, and the Slepian FD basis are -17.4 dB, -17.9 dB, and -17.5 dB, respectively, which indicate an improvement in channel estimation as compared to the values for the window without extension 1204.

FIG. 13 is a diagram 1300 illustrating a joint indication of DS scaling and PRG. A PRG may be a consecutive group of RBs, e.g., 2 RBs, 4RBs, or wideband (WB) . PRGs may typically be used for downlink demodulation reference signal (DL DMRS) , and a UE (e.g., the UE 402 as described above with reference to FIG. 4) , may assume that a same precoder is applied to all RBs in the same PRG. However, with frequency-selective precoding, UE precoders applied to RBs in different PRG may be different, and WB channel estimation may not be possible if PRG configuration is 2 RBs or 4 RBs, and the UE may only can be able to do narrow-band CE.

Applying the PRG to CSI-RS may solve the frequency-selective precoded CSI-RS to an extent. However, such implementation may lead to an additional impact on the UE, as the UE may have to implement 2 different CE techniques (one being WB and the other being is NB) .

A joint indication of DS scaling and PRG can improve CE for a UE (e.g., the UE 502 as described above with reference to FIG. 5) . For example, a larger PRG may need higher DS-scaling (e.g., a BS using a large PRG may utilize a finer precoder, e.g., RB level precoding and such case may need larger DS scaling) . Also, a smaller PRG may need lower DS-scaling or no scaling (e.g., a channel may be relatively flat in frequency within a PRG, so less DS-scaling may be needed if PRG is small) . The joint indication of DS scaling and PRG may be implemented using an indication (e.g., a codepoint value) to indicate a pair of PRG and DS-scaling.

In one implementation, a reuse of the PRG field in DCI with extension of codepoints, may be utilized for the joint indication of DS scaling and PRG.

Diagram 1300 includes a table illustrating joint implementation of DS scaling and PRG. For example, the table includes codepoint values, PRG and DS scaling as the columns and the values of each of the codepoint values, the PRG and the DS scaling as the rows. For example, for a DS scaling of 1, and

PRGs

2, 4 and WB, the codepoint values 0, 1 and 2, respectively may be used for the joint indication. Similarly, for a DS scaling of 2, and PRGs 4 and WB, the codepoint values 3 and 4, respectively may be used for the joint indication. Further, for a DS scaling of 3, and PRG being WB, a codepoint value of 5 may be used.

In one implementation, an independent indication of DS scaling may be used. In another implementation, a joint indication of the DS scaling and the PRG size may be used. Either of the independent indication or the joint indication may be utilized for the implementations described below.

For example, in one implementation, an indication of DS scaling may be configured via RRC in the CSI report configuration.

Further, in one implementation, an indication of DS scaling may be configured via RRC and configured per resource set. For example, the active set may be activated by the configuration of trigger state.

Further, in one implementation, an indication of DS scaling may be configured via RRC and configured per resource. For example, each resource set may have multiple resources and the UE 502 may report one resource from the set.

Further, in one implementation, an indication of DS scaling may be configured via RRC and configured per port or port-group. For example, the DS scaling or (DS scaling and PRG) may apply to part of total ports of a resource, or different port-group may have different DS scaling or (DS scaling and PRG) .

Further, in one implementation, a MAC-CE or DCI may semi-statically or dynamically configure the DS scaling or (DS scaling and PRG) . This implementation can work together with any of the above described implementations overriding the RRC configuration. When implemented with a configuration per resource set implementation (as described above) , or a configuration per resource (as described above) , this implementation may override the DS scaling or (DS scaling and PRG) for an activated resource set based on the implementation corresponding to per resource set, or the implementation corresponding to per resource (s) . Alternatively, in this implementation, an activated resource set or resource may be changed, e.g., by first deactivating the currently active set of resource, and second by activating another set or resources.

FIG. 14 is a flowchart 1400 of a method of wireless communication of a UE. At 1402, the UE receives a CSI request triggering a CSI report. The CSI request is associated with one or more CSI-RS resources. For example, the UE 502 (as described above with reference to FIGs. 5-13) may receive the CSI request triggering the CSI report.

At 1404, the UE determines that the one or more CSI-RS resources are associated with one or more reference signal for tracking. For example, the UE 502 may determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking.

At 1406, the UE receives the one or more reference signal for tracking. For example, the UE 502 may receive the one or more reference signal for tracking.

At 1408, the UE performs CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking. For example, the UE 502 may perform CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.

In one configuration, the one or more reference signal for tracking may be an aperiodic CSI-RS for tracking. The aperiodic CSI-RS for tracking may be received in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking may be received based on the configuration.

Further, in one configuration, the UE 502 may perform the CSI measurement of the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking by performing the CSI measurement based on determining the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.

Further, in one configuration, the UE 502 may determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on a received transmission configuration indicator (TCI) state of the one or more CSI-RS resources, and the TCI state indicates that one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.

Further, in one configuration, the one or more reference signal for tracking is received from a base station (e.g., the BS 504 as described above with reference to FIG. 5) , and the one or more reference signal for tracking is one or more A-TRS, the A-TRS having a same transmission filter as the received CSI-RS.

Further, in one configuration, the UE 502 may determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking by receiving a configuration for the CSI report. The configuration may include a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking. The UE 502 may determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on the configuration.

Further, in one configuration, the UE 502 may determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking by receiving a configuration for a CSI trigger state. The CSI trigger state may include an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking. The UE 502 may determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the configuration and the CSI request, the CSI request being associated with the CSI trigger state.

Further, in one configuration, the UE 502 may determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking by receiving a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request. The UE 502 may determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the received triggering.

Although, the above description mentions the UE 502 performing the operations in the flowchart 1400, however one or more components of the UE 502 (e.g., the channel estimation unit 140 and/or the delay spread scaling unit 142) may perform the above mentioned operations in the flowchart 1400.

FIG. 15 is a flowchart 1500 of a method of wireless communication of a UE. At 1502, the UE receives a CSI-RS report configuration associated with one or more CSI-RS resources. The configuration includes an indication of QCL information of each of the one or more CSI-RS resources. For example, the UE 502 (as described above with reference to FIGs. 5-13) may receive the CSI-RS report configuration associated with the one or more CSI-RS resources.

At 1504, the UE receives an indication of a delay spread scaling factor from a base station (e.g., the BS 504 as described above with reference to FIG. 5) . For example, the UE 502 may receive the indication of a delay spread scaling factor from the BS 504 (as described above with reference to FIG. 5) .

At 1506, the UE performs a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor. For example, the UE 502 may perform a CSI measurement of the CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.

In one configuration, the UE 502 may perform the CSI measurement of the one or more CSI-RS resources based on QCL information and the delay spread scaling factor by determining a first average delay, a first delay spread, or a first maximum delay based on the QCL information. The UE 502 may determine a second average delay, a second delay spread, or a second maximum delay by scaling the first average delay, the first delay spread, or the first maximum delay by the delay spread scaling factor. The CSI measurement of the one or more CSI-RS resources may be performed based on the second average delay, the second delay spread, or the second maximum delay.

Further, in one configuration, the information indicating the delay spread scaling factor may be received through one of an RRC message, a MAC-CE, or a DCI.

Further, in one configuration, the UE 502 may receive the indication of the delay spread scaling factor from the BS 504 by receiving a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is received.

Further, in one configuration, the UE 502 may receive the indication of the delay spread scaling factor from the BS 504 by receiving the indication via a first signaling indicating the CSI report configuration, and the indicated delay spread scaling factor is applied to all CSI-RS resources and ports associated with the CSI report.

Further, in one configuration, the UE 502 may receive the indication of the delay spread scaling factor from the BS 504 by determining one or more CSI-RS resource set included in the CSI report configuration. The UE 502 may receive first signaling indicating a resource-set specific delay spread scaling factor. The indicated delay spread scaling factor may be applied to all the CSI-RS resources and ports comprised in the corresponding CSI-RS resource set.

Further, in one configuration, the UE 502 may receive the indication of the delay spread scaling factor from the base station by determining the one or more CSI-RS resources included in the CSI report configuration. The UE 502 may receive first signaling indicating a resource specific delay spread scaling factor. The indicated delay spread scaling factor is applied to all ports comprised in the corresponding CSI-RS resource.

Further, in one configuration, the UE 502 may receive the indication of the delay spread scaling factor from the BS 504 by determining one or more CSI-RS port groups within one resource comprised in the CSI report configuration. The UE 502 may receive first signaling indicating port-group specific delay spread scaling factor. The indicated delay spread scaling factor is applied to all the ports comprised in the corresponding CSI-RS port group.

Further, in one configuration, the delay spread scaling factor is received in a first signaling, and the UE 502 may determine an active CSI-RS resource set or one or more active CSI-RS resources based on a configuration. The UE 502 may receive a second signaling indicating a second delay spread scaling factor. The UE 502 may determine the delay spread scaling factor of the active CSI-RS resource set or one or more active CSI-RS resources based on the second delay spread scaling factor.

Further, in one configuration, the second signaling may be received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .

Further, in one configuration, the delay spread scaling factor is received in a first signaling, and the UE 502 may determine a first active CSI-RS resource set or a first one or more active CSI-RS resources based on a configuration. The UE 502 may receive a second signaling deactivating the first active CSI-RS resource set or the first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources. The UE 502 may determine the delay spread scaling factor of the second CSI-RS resource set or the second one or more CSI-RS resources based on the deactivation and activation.

Further, in one configuration, the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .

Although, the above description mentions the UE 502 performing the operations in the flowchart 1500, however one or more components of the UE 502 (e.g., the channel estimation unit 140 and/or the delay spread scaling unit 142) may perform the above mentioned operations in the flowchart 1500.

FIG. 16 is a flowchart 1600 of a method of wireless communication of a BS. At 1602, the BS transmits, to a UE, a CSI request triggering a CSI report, the CSI request being associated with one or more CSI-RS resources. The one or more CSI-RS resources may be associated with one or more reference signal for tracking. For example, the BS 504 (as described above with reference to FIG. 1) may transmit, to the UE 502 (as described above with reference to FIG. 1) , the CSI request triggering the CSI report, the CSI request being associated with one or more CSI-RS resources.

At 1604, the BS transmits, to the UE, the one or more reference signal for tracking. For example, the BS 504 may transmit, to the UE 502, the one or more reference signal for tracking.

At 1606, the BS receives from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking. For example, the BS 504 may receive from the UE 502, the CSI report, the CSI report including information indicating CSI measurement results of the CSI-RS transmitted in the one or more CSI-RS resources and the CSI measurement results being based on the one or more reference signal for tracking. Further, in one configuration, the BS 504 may

In one configuration, the one or more reference signal for tracking may include an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is transmitted in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is transmitted based on the configuration.

Further, in one configuration, the BS 504 may transmit an indication to the UE 502 that the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a max delay.

Further, in one configuration, the indication is a TCI state indicating that the one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.

Further, in one configuration, the one or more reference signal for tracking is one or more A-TRS, the A-TRS having a same transmission filter as the transmitted CSI-RS.

Further, in one configuration, the BS 504 may transmit a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking. The received CSI report may be based on the transmitted configuration.

Further, in one configuration, the BS 504 may transmit a configuration for a CSI trigger state associated with the CSI request, wherein the CSI trigger state may include an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.

Further, in one configuration, the BS 504 may transmit a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request. The received CSI report may be based on the transmitted triggering.

Although, the above description mentions the BS 504 performing the operations in the flowchart 1600, however one or more components of the BS 504 (e.g., the channel estimation unit 140 and/or the delay spread scaling unit 142) may perform the above mentioned operations in the flowchart 1600.

FIG. 17 is a flowchart of a method 1700 of wireless communication of a BS. At 1702, the BS transmits, to a UE, a CSI-RS report configuration associated with one or more CSI-RS resources. The configuration includes an indication of QCL information of each of the one or more CSI-RS resources. For example, the BS 504 (as described above with reference to FIG. 5) , may transmit, to the UE 502 (as described above with reference to FIG. 5) , the CSI-RS report configuration associated with one or more CSI-RS resources.

At 1704, the BS transmits, to the UE, an indication of a delay spread scaling factor. For example, the BS 504 may transmit, to the UE 502, the indication of the delay spread scaling factor.

At 1706, the BS receives, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, and the CSI measurement results being based on the QCL information and the delay spread scaling factor. For example, the BS 504 may receive, from the UE 502, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, and the CSI measurement results based on the QCL information and the delay spread scaling factor.

In one configuration, the information indicating the delay spread scaling factor is transmitted through one of an RRC message, a MAC-CE, or DCI.

Further, in one configuration, the BS 504 may the transmit the indication of the delay spread scaling factor by transmitting a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is transmitted. The CSI report may be based on the transmitted joint indication.

Further, in one configuration, the BS 504 may transmit the indication of the delay spread scaling factor by transmitting the indication via a first signaling indicating the CSI report configuration. The CSI report may be based on the transmitted first signaling.

Further, in one configuration, the one or more CSI-RS resource set may be included in the CSI report configuration, and the BS 504 may transmit the indication of the delay spread scaling factor by transmitting first signaling indicating a resource-set specific delay spread scaling factor. The CSI report may be based on the transmitted first signaling.

Further, in one configuration, the one or more CSI-RS resources included in the CSI report configuration, and the BS 504 may transmit the indication of the delay spread scaling factor by transmitting first signaling indicating a resource specific delay spread scaling factor. The CSI report may be based on the transmitted first signaling.

Further, in one configuration, one or more CSI-RS port groups within one resource may be included in the CSI report configuration, and the BS 504 may transmit the indication of the delay spread scaling factor by transmitting first signaling indicating port-group specific delay spread scaling factor, wherein the CSI report is based on the transmitted first signaling.

Further, in one configuration, the delay spread scaling factor is transmitted in a first signaling, and the BS 504 may transmit a second signaling indicating a second delay spread scaling factor. The CSI report may be based on the transmitted second signaling.

Further, in one configuration, the second signaling may be transmitted through one of an RRC message, a MAC-CE, or DCI.

Further, in one configuration, the delay spread scaling factor may be transmitted in a first signaling, and the BS 504 may transmit a second signaling deactivating a first active CSI-RS resource set or a first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources, wherein the CSI report is based on the transmitted second signaling.

Although, the above description mentions the BS 504 performing the operations in the flowchart 1700, however one or more components of the BS 504 (e.g., the channel estimation unit 140 and/or the delay spread scaling unit 142) may perform the above mentioned operations in the flowchart 1700.

It is understood that the specific order or hierarchy of blocks in the processes /flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

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 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. ” 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. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. 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. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

Claims

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

receiving a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources;

determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking;

receiving the one or more reference signal for tracking; and

performing CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.
The method of claim 1, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is received in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is received based on the configuration.
The method of claim 1, wherein the performing the CSI measurement of the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking further comprises:

performing the CSI measurement based on determining the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The method of claim 3, further comprising:

determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on a received transmission configuration indicator (TCI) state of the one or more CSI-RS resources, wherein the TCI state indicates that one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The method of claim 1, wherein the one or more reference signal for tracking is received from a base station and the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the received CSI-RS.
The method of claim 1, wherein determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking further comprises:

receiving a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking; and

determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on the configuration.
The method of claim 1, wherein the determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking further comprises:

receiving a configuration for a CSI trigger state, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking; and

determining that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the configuration and the CSI request, the CSI request being associated with the CSI trigger state.
The method of claim 1, wherein determining that the one or more CSI-RS resources are associated with the one or more reference signal for tracking further comprises:

receiving a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request; and

determining that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the received triggering.
A method of wireless communication of a user equipment (UE) , comprising

receiving a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

receiving an indication of a delay spread scaling factor from a base station; and

performing a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.
The method of claim 9, wherein the performing the CSI measurement of the one or more CSI-RS resources based on QCL information and the delay spread scaling factor further comprises:

determining a first average delay, a first delay spread, or a first maximum delay based on the QCL information; and

determining a second average delay, a second delay spread, or a second maximum delay by scaling the first average delay, the first delay spread, or the first maximum delay by the delay spread scaling factor,

wherein the CSI measurement of the one or more CSI-RS resources is performed based on the second average delay, the second delay spread, or the second maximum delay.
The method of claim 9, wherein the information indicating the delay spread scaling factor is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The method of claim 9, wherein the receiving the indication of the delay spread scaling factor from the base station further comprises receiving a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is received.
The method of claim 9, wherein the receiving the indication of the delay spread scaling factor from the base station further comprises receiving the indication via a first signaling indicating the CSI report configuration, and the indicated delay spread scaling factor is applied to all CSI-RS resources and ports associated with the CSI report.
The method of claim 9, wherein the receiving the indication of the delay spread scaling factor from the base station further comprises:

determining one or more CSI-RS resource set included in the CSI report configuration; and

receiving first signaling indicating a resource-set specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the CSI-RS resources and ports comprised in the corresponding CSI-RS resource set.
The method of claim 9, wherein the receiving the indication of the delay spread scaling factor from the base station further comprises:

determining the one or more CSI-RS resources included in the CSI report configuration; and

receiving first signaling indicating a resource specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all ports comprised in the corresponding CSI-RS resource.
The method of claim 9, wherein the receiving the indication of the delay spread scaling factor from the base station further comprises:

determining one or more CSI-RS port groups within one resource comprised in the CSI report configuration; and

receiving first signaling indicating port-group specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the ports comprised in the corresponding CSI-RS port group.
The method of claim 9, wherein the delay spread scaling factor is received in a first signaling, the method further comprising:

determining an active CSI-RS resource set or one or more active CSI-RS resources based on a configuration;

receiving a second signaling indicating a second delay spread scaling factor; and

determining the delay spread scaling factor of the active CSI-RS resource set or one or more active CSI-RS resources based on the second delay spread scaling factor.
The method of claim 17, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The method of claim 9, wherein the delay spread scaling factor is received in a first signaling, the method further comprising:

determining a first active CSI-RS resource set or a first one or more active CSI-RS resources based on a configuration;

receiving a second signaling deactivating the first active CSI-RS resource set or the first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources; and

determining the delay spread scaling factor of the second CSI-RS resource set or the second one or more CSI-RS resources based on the deactivation and activation.
The method of claim 19, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
A method of wireless communication of a base station (BS) , comprising:

transmitting, to a user equipment (UE) , a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources, wherein the one or more CSI-RS resources are associated with one or more reference signal for tracking;

transmitting, to the UE, the one or more reference signal for tracking; and

receiving, from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking.
The method of claim 21, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is transmitted in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is transmitted based on the configuration.
The method of claim 21, further comprising transmitting an indication to the UE that the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The method of claim 23, wherein the indication is a transmission configuration indicator (TCI) state indicating that the one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The method of claim 21, wherein the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the transmitted CSI-RS.
The method of claim 21, further comprising transmitting a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The method of claim 21, further comprising transmitting a configuration for a CSI trigger state associated with the CSI request, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The method of claim 21, further comprising transmitting a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request, wherein the received CSI report is based on the transmitted triggering.
A method of wireless communication of a base station (BS) , comprising

transmitting, to a user equipment (UE) , a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

transmitting, to the UE, an indication of a delay spread scaling factor; and

receiving, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, the CSI measurement results being based on the QCL information and the delay spread scaling factor.
The method of claim 29, wherein the information indicating the delay spread scaling factor is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The method of claim 29, wherein the transmitting the indication of the delay spread scaling factor further comprises transmitting a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is transmitted, wherein the CSI report is based on the transmitted joint indication.
The method of claim 29, wherein the transmitting the indication of the delay spread scaling factor further comprises transmitting the indication via a first signaling indicating the CSI report configuration, the CSI report being based on the transmitted first signaling.
The method of claim 29, wherein one or more CSI-RS resource set is included in the CSI report configuration, and the transmitting the indication of the delay spread scaling factor further comprises transmitting first signaling indicating a resource-set specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The method of claim 29, wherein the one or more CSI-RS resources included in the CSI report configuration, and the transmitting the indication of the delay spread scaling factor further comprises transmitting first signaling indicating a resource specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The method of claim 29, wherein one or more CSI-RS port groups within one resource comprised in the CSI report configuration, and the transmitting the indication of the delay spread scaling factor further comprises transmitting first signaling indicating port-group specific delay spread scaling factor, wherein the CSI report is based on the transmitted first signaling.
The method of claim 29, wherein the delay spread scaling factor is transmitted in a first signaling, the method further comprising transmitting a second signaling indicating a second delay spread scaling factor, wherein the CSI report is based on the transmitted second signaling.
The method of claim 36, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The method of claim 29, wherein the delay spread scaling factor is transmitted in a first signaling, the method further comprising transmitting a second signaling deactivating a first active CSI-RS resource set or a first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources, wherein the CSI report is based on the transmitted second signaling.
The method of claim 38, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
An apparatus for wireless communication, the apparatus being a user equipment (UE) , comprising:

a memory; and

at least one processor coupled to the memory and configured to:

receive a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources;

determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking;

receive the one or more reference signal for tracking; and

perform CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.
The apparatus of claim 40, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is received in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is received based on the configuration.
The apparatus of claim 40, wherein to perform the CSI measurement of the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking, the at least one processor is configured to:

perform the CSI measurement based on determining the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The apparatus of claim 42, wherein the processor is further configured to:

determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on a received transmission configuration indicator (TCI) state of the one or more CSI-RS resources, wherein the TCI state indicates that one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The apparatus of claim 40, wherein the one or more reference signal for tracking is received from a base station and the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the received CSI-RS.
The apparatus of claim 40, wherein to determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking, the at least one processor is configured to:

receive a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking; and

determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on the configuration.
The apparatus of claim 40, wherein to determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking, the at least one processor is configured to:

receive a configuration for a CSI trigger state, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking; and

determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the configuration and the CSI request, the CSI request being associated with the CSI trigger state.
The apparatus of claim 40, wherein to determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking, the at least one processor is configured to:

receive a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request; and

determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the received triggering.
An apparatus for wireless communication, the apparatus being a user equipment (UE) , comprising:

a memory; and

at least one processor coupled to the memory and configured to:

receive a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

receive an indication of a delay spread scaling factor from a base station; and

perform a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.
The apparatus of claim 48, wherein the perform the CSI measurement of the one or more CSI-RS resources based on QCL information and the delay spread scaling factor comprises the processor further configured to:

determine a first average delay, a first delay spread, or a first maximum delay based on the QCL information; and

determine a second average delay, a second delay spread, or a second maximum delay by scaling the first average delay, the first delay spread, or the first maximum delay by the delay spread scaling factor,

wherein the CSI measurement of the one or more CSI-RS resources is performed based on the second average delay, the second delay spread, or the second maximum delay.
The apparatus of claim 48, wherein the information indicating the delay spread scaling factor is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 48, wherein to receive the indication of the delay spread scaling factor from the base station, the at least one processor is configured to receive a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is received.
The apparatus of claim 48, wherein to receive the indication of the delay spread scaling factor from the base station, the at least one processor is configured to receive the indication via a first signaling indicating the CSI report configuration, and the indicated delay spread scaling factor is applied to all CSI-RS resources and ports associated with the CSI report.
The apparatus of claim 48, wherein to receive the indication of the delay spread scaling factor from the base station, the at least one processor is configured to:

determine one or more CSI-RS resource set included in the CSI report configuration; and

receive first signaling indicating a resource-set specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the CSI-RS resources and ports comprised in the corresponding CSI-RS resource set.
The apparatus of claim 48, wherein to receive the indication of the delay spread scaling factor from the base station comprises the processor further configured to:

determine the one or more CSI-RS resources included in the CSI report configuration; and

receive first signaling indicating a resource specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all ports comprised in the corresponding CSI-RS resource.
The apparatus of claim 48, wherein to receive the indication of the delay spread scaling factor from the base station comprises the processor further configured to:

determining one or more CSI-RS port groups within one resource comprised in the CSI report configuration; and

receive first signaling indicating port-group specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the ports comprised in the corresponding CSI-RS port group.
The apparatus of claim 48, wherein the delay spread scaling factor is received in a first signaling, and the processor is further configured to:

determine an active CSI-RS resource set or one or more active CSI-RS resources based on a configuration;

receive a second signaling indicating a second delay spread scaling factor; and

determine the delay spread scaling factor of the active CSI-RS resource set or one or more active CSI-RS resources based on the second delay spread scaling factor.
The apparatus of claim 56, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 48, wherein the delay spread scaling factor is received in a first signaling, and the processor is further configured to:

determine a first active CSI-RS resource set or a first one or more active CSI-RS resources based on a configuration;

receive a second signaling deactivating the first active CSI-RS resource set or the first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources; and

determine the delay spread scaling factor of the second CSI-RS resource set or the second one or more CSI-RS resources based on the deactivation and activation.
The apparatus of claim 58, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
An apparatus for wireless communication, the apparatus being a base station (BS) , comprising:

a memory; and

at least one processor coupled to the memory and configured to:

transmit, to a user equipment (UE) , a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources, wherein the one or more CSI-RS resources are associated with one or more reference signal for tracking;

transmit, to the UE, the one or more reference signal for tracking; and

receive, from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking.
The apparatus of claim 60, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is transmitted in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is transmitted based on the configuration.
The apparatus of claim 60, further comprising the processor configured to transmit an indication to the UE that the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The apparatus of claim 62, wherein the indication is a transmission configuration indicator (TCI) state indicating that the one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The apparatus of claim 60, wherein the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the transmitted CSI-RS.
The apparatus of claim 60, further comprising the processor configured to transmit a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The apparatus of claim 60, further comprising the processor configured to transmit a configuration for a CSI trigger state associated with the CSI request, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The apparatus of claim 60, further comprising the processor configured to transmit a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request, wherein the received CSI report is based on the transmitted triggering.
An apparatus for wireless communication, the apparatus being a base station (BS) , comprising:

a memory; and

at least one processor coupled to the memory and configured to:

transmit, to a user equipment (UE) , a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

transmit, to the UE, an indication of a delay spread scaling factor; and

receive, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, the CSI measurement results being based on the QCL information and the delay spread scaling factor.
The apparatus of claim 68, wherein the information indicating the delay spread scaling factor is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 68, wherein to transmit the indication of the delay spread scaling factor comprises the processor further configured to transmit a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is transmitted, wherein the CSI report is based on the transmitted joint indication.
The apparatus of claim 68, wherein to transmit the indication of the delay spread scaling factor comprises the processor further configured to transmit the indication via a first signaling indicating the CSI report configuration, the CSI report being based on the transmitted first signaling.
The apparatus of claim 68, wherein one or more CSI-RS resource set is included in the CSI report configuration, and to transmit the indication of the delay spread scaling factor comprises the processor further configured to transmit first signaling indicating a resource-set specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The apparatus of claim 68, wherein the one or more CSI-RS resources included in the CSI report configuration, and to transmit the indication of the delay spread scaling factor comprises the processor further configured to transmit first signaling indicating a resource specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The apparatus of claim 68, wherein one or more CSI-RS port groups within one resource comprised in the CSI report configuration, and to transmit the indication of the delay spread scaling factor comprises the processor further configured to transmit first signaling indicating port-group specific delay spread scaling factor, wherein the CSI report is based on the transmitted first signaling.
The apparatus of claim 68, wherein the delay spread scaling factor is transmitted in a first signaling, and the processor is further configured to transmit a second signaling indicating a second delay spread scaling factor, wherein the CSI report is based on the transmitted second signaling.
The apparatus of claim 75, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 68, wherein the delay spread scaling factor is transmitted in a first signaling, and the processor is further configured to transmit a second signaling deactivating a first active CSI-RS resource set or a first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources, wherein the CSI report is based on the transmitted second signaling.
The apparatus of claim 77, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
An apparatus for wireless communication, the apparatus being a user equipment (UE) , comprising:

means for receiving a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources;

means for determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking;

means for receiving the one or more reference signal for tracking; and

means for performing CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.
The apparatus of claim 79, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is received in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is received based on the configuration.
The apparatus of claim 79, wherein the means for performing the CSI measurement of the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking is configured to:

perform the CSI measurement based on determining the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The apparatus of claim 81, further comprising means for determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on a received transmission configuration indicator (TCI) state of the one or more CSI-RS resources, wherein the TCI state indicates that one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The apparatus of claim 79, wherein the one or more reference signal for tracking is received from a base station and the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the received CSI-RS.
The apparatus of claim 79, wherein the means for determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking is further configured to:

receive a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking; and

determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking based on the configuration.
The apparatus of claim 79, wherein the means for determining that the one or more CSI-RS resources are associated with one or more reference signal for tracking is further configured to:

receive a configuration for a CSI trigger state, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking; and

determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the configuration and the CSI request, the CSI request being associated with the CSI trigger state.
The apparatus of claim 79, wherein the means for determining that the one or more CSI-RS resources are associated with the one or more reference signal for tracking is further configured to:

receive a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request; and

determine that the one or more CSI-RS resources are associated with the one or more reference signal for tracking based on the received triggering.
An apparatus for wireless communication, the apparatus being a user equipment (UE) , comprising:

means for receiving a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

means for receiving an indication of a delay spread scaling factor from a base station; and

means for performing a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.
The apparatus of claim 87, wherein the means for performing the CSI measurement of the one or more CSI-RS resources based on QCL information and the delay spread scaling factor is further configured to:

determine a first average delay, a first delay spread, or a first maximum delay based on the QCL information; and

determine a second average delay, a second delay spread, or a second maximum delay by scaling the first average delay, the first delay spread, or the first maximum delay by the delay spread scaling factor,

wherein the CSI measurement of the one or more CSI-RS resources is performed based on the second average delay, the second delay spread, or the second maximum delay.
The apparatus of claim 87, wherein the information indicating the delay spread scaling factor is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 87, wherein the means for receiving the indication of the delay spread scaling factor from the base station is further configured to receive a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is received.
The apparatus of claim 87, wherein the means for receiving the indication of the delay spread scaling factor from the base station is further configured to receive the indication via a first signaling indicating the CSI report configuration, and the indicated delay spread scaling factor is applied to all CSI-RS resources and ports associated with the CSI report.
The apparatus of claim 87, wherein the means for receiving the indication of the delay spread scaling factor from the base station is further configured to:

determine one or more CSI-RS resource set included in the CSI report configuration; and

receive first signaling indicating a resource-set specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the CSI-RS resources and ports comprised in the corresponding CSI-RS resource set.
The apparatus of claim 87, wherein the means for receiving the indication of the delay spread scaling factor from the base station is further configured to:

determine the one or more CSI-RS resources included in the CSI report configuration; and

receive first signaling indicating a resource specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all ports comprised in the corresponding CSI-RS resource.
The apparatus of claim 87, wherein the means for receiving the indication of the delay spread scaling factor from the base station is further configured to:

determine one or more CSI-RS port groups within one resource comprised in the CSI report configuration; and

receive first signaling indicating port-group specific delay spread scaling factor,

wherein the indicated delay spread scaling factor is applied to all the ports comprised in the corresponding CSI-RS port group.
The apparatus of claim 87, wherein the delay spread scaling factor is received in a first signaling, and the apparatus further comprising:

means for determining an active CSI-RS resource set or one or more active CSI-RS resources based on a configuration;

means for receiving a second signaling indicating a second delay spread scaling factor; and

means for determining the delay spread scaling factor of the active CSI-RS resource set or one or more active CSI-RS resources based on the second delay spread scaling factor.
The apparatus of claim 95, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 87, wherein the delay spread scaling factor is received in a first signaling, and the apparatus further comprising:

means for determining a first active CSI-RS resource set or a first one or more active CSI-RS resources based on a configuration;

means for receiving a second signaling deactivating the first active CSI-RS resource set or the first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources; and

means for determining the delay spread scaling factor of the second CSI-RS resource set or the second one or more CSI-RS resources based on the deactivation and activation.
The apparatus of claim 97, wherein the second signaling is received through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
An apparatus for wireless communication, the apparatus being a base station (BS) , comprising:

means for transmitting, to a user equipment (UE) , a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources, wherein the one or more CSI-RS resources are associated with one or more reference signal for tracking;

means for transmitting, to the UE, the one or more reference signal for tracking; and

means for receiving, from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking.
The apparatus of claim 99, wherein the one or more reference signal for tracking comprises an aperiodic CSI-RS for tracking, the aperiodic CSI-RS for tracking is transmitted in a frequency and time resource based on a configuration, and the aperiodic CSI-RS for tracking is transmitted based on the configuration.
The apparatus of claim 99, further comprising means for transmitting an indication to the UE that the one or more CSI-RS resources is quasi-co located (QCLed) with the one or more reference signal for tracking through one of an average delay or a delay spread or a maximum delay.
The apparatus of claim 101, wherein the indication is a transmission configuration indicator (TCI) state indicating that the one or more CSI-RS resource is QCLed with the one or more reference signal for tracking.
The apparatus of claim 99, wherein the one or more reference signal for tracking is one or more aperiodic tracking reference signals (A-TRS) , the A-TRS having a same transmission filter as the transmitted CSI-RS.
The apparatus of claim 99, further comprising means for transmitting a configuration for the CSI report, the configuration including a first CSI-RS configuration for channel or interference measurement and a second CSI-RS configuration for the reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The apparatus of claim 99, further comprising means for transmitting a configuration for a CSI trigger state associated with the CSI request, wherein the CSI trigger state comprises an association between the one or more CSI-RS resources included in the CSI report and the one or more reference signal for tracking, wherein the received CSI report is based on the transmitted configuration.
The apparatus of claim 99, further comprising means for transmitting a triggering of the one or more reference signal for tracking in a same downlink signaling that carries the CSI request, wherein the received CSI report is based on the transmitted triggering.
An apparatus for wireless communication, the apparatus being a base station (BS) , comprising:

means for transmitting, to a user equipment (UE) , a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

means for transmitting, to the UE, an indication of a delay spread scaling factor; and

means for receiving, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, the CSI measurement results being based on the QCL information and the delay spread scaling factor.
The apparatus of claim 107, wherein the information indicating the delay spread scaling factor is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 107, wherein the means for transmitting the indication of the delay spread scaling factor is further configured to transmit a joint indication of the delay spread scaling factor and a size of a physical resource group (PRG) in which the CSI-RS is transmitted, wherein the CSI report is based on the transmitted joint indication.
The apparatus of claim 107, wherein the means for transmitting the indication of the delay spread scaling factor is further configured to transmit the indication via a first signaling indicating the CSI report configuration, the CSI report being based on the transmitted first signaling.
The apparatus of claim 107, wherein one or more CSI-RS resource set is included in the CSI report configuration, and the means for transmitting the indication of the delay spread scaling factor is further configured to transmit first signaling indicating a resource-set specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The apparatus of claim 107, wherein the one or more CSI-RS resources included in the CSI report configuration, and the means for transmitting the indication of the delay spread scaling factor is further configured to transmit the first signaling indicating a resource specific delay spread scaling factor, the CSI report being based on the transmitted first signaling.
The apparatus of claim 107, wherein one or more CSI-RS port groups within one resource comprised in the CSI report configuration, and the means for transmitting the indication of the delay spread scaling factor is further configured to transmit first signaling indicating port-group specific delay spread scaling factor, wherein the CSI report is based on the transmitted first signaling.
The apparatus of claim 107, wherein the delay spread scaling factor is transmitted in a first signaling, and the apparatus further comprising means for transmitting a second signaling indicating a second delay spread scaling factor, wherein the CSI report is based on the transmitted second signaling.
The apparatus of claim 114, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
The apparatus of claim 107, wherein the delay spread scaling factor is transmitted in a first signaling, and the apparatus further comprising means for transmitting a second signaling deactivating a first active CSI-RS resource set or a first one or more active CSI-RS resources and activating a second CSI-RS resource set or a second one or more CSI-RS resources, wherein the CSI report is based on the transmitted second signaling.
The apparatus of claim 116, wherein the second signaling is transmitted through one of a radio resource control (RRC) message, a media access control (MAC) control element (CE) , or downlink control information (DCI) .
A computer-readable medium storing computer executable code, the code when executed by a processor cause the processor to:

receive a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources;

determine that the one or more CSI-RS resources are associated with one or more reference signal for tracking;

receive the one or more reference signal for tracking; and

perform CSI measurements of CSI-RS received in the one or more CSI-RS resources based on the measurement of the one or more reference signal for tracking.
A computer-readable medium storing computer executable code, the code when executed by a processor cause the processor to:

receive a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

receive an indication of a delay spread scaling factor from a base station; and

perform a CSI measurement of CSI-RS received in the one or more CSI-RS resources based on the QCL information and the delay spread scaling factor.
A computer-readable medium storing computer executable code, the code when executed by a processor cause the processor to:

transmit, to a user equipment (UE) , a channel state information (CSI) request triggering a CSI report, the CSI request being associated with one or more CSI reference signal (RS) (CSI-RS) resources, wherein the one or more CSI-RS resources are associated with one or more reference signal for tracking;

transmit, to the UE, the one or more reference signal for tracking; and

receive, from the UE, the CSI report, the CSI report including information indicating CSI measurement results of CSI-RS transmitted in the one or more CSI-RS resources, the CSI measurement results being based on the one or more reference signal for tracking.
A computer-readable medium storing computer executable code, the code when executed by a processor cause the processor to:

transmit, to a user equipment (UE) , a channel state information (CSI) reference signal (RS) (CSI-RS) report configuration associated with one or more CSI-RS resources, the configuration includes an indication of quasi-co location (QCL) information of each of the one or more CSI-RS resources;

transmit, to the UE, an indication of a delay spread scaling factor; and

receive, from the UE, the CSI report, the CSI report including CSI measurement results of CSI-RS transmitting in the one or more CSI-RS resources, the CSI measurement results being based on the QCL information and the delay spread scaling factor.