Method and apparatus for reporting of time-domain channel correlation properties

Methods and apparatuses for reporting of time-domain channel correlation properties are provided. A method includes receiving a configuration about a CSI report. The configuration includes information about (i) M non-zero power (NZP) CSI reference signal (RS) resources for tracking, (ii) a number (K) of time-domain correlation values, and (iii) delay values τk for k=0, 1, . . . , K−1. The method further includes, based on the configuration: measuring the M NZP CSI-RS resources for tracking, determining, based on the measurement, the K time-domain correlation values, wherein a k-th correlation value is between two CSI-RS transmission occasions that are separated by one of the delay values τk, and quantizing a value for an amplitude of each of the K time-domain correlation values. The method further includes transmitting the CSI report including an indicator, for each of the K time-domain correlation values, indicating the quantized value of the amplitude.

TECHNICAL FIELD

The present disclosure relates generally to wireless communication systems and, more specifically, to methods and apparatuses for reporting of time-domain channel correlation properties.

BACKGROUND

SUMMARY

This disclosure relates to reporting of time-domain channel properties.

In one embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to receive a configuration about a channel state information (CSI) report. The configuration includes information about (i) M non-zero power (NZP) CSI reference signal (RS) resources for tracking, where M≥1, (ii) a number (K) of time-domain correlation values, where K≥1, and (iii) delay values τkfor k=0, 1, . . . , K−1. The UE further includes a processor operably coupled to the transceiver. The processor, based on the configuration, is configured to: measure the M NZP CSI-RS resources for tracking, determine, based on the measurement, the K time-domain correlation values, and quantize a value for an amplitude of each of the K time-domain correlation values. A k-th correlation value is between two CSI-RS transmission occasions that are separated by one of the delay values τk. The transceiver is further configured to transmit the CSI report including an indicator, for each of the K time-domain correlation values, indicating the quantized value of the amplitude.

In another embodiment, a base station is provided. The base station includes a transceiver configured to transmit a configuration about a CSI report that includes information about (i) M NZP CSI-RS resources for tracking, where M≥1, (ii) a number (K) of time-domain correlation values, where K≥1, and (iii) delay values τkfor k=0, 1, . . . , K−1; transmit the M NZP CSI-RS resources for tracking; and receive the CSI report including an indicator, for each of the K time-domain correlation values, indicating a quantized value of an amplitude of the respective K time-domain correlation value that is based on the M NZP CSI-RS resources for tracking. A k-th correlation value is between two CSI-RS transmission occasions that are separated by one of the delay values τk.

In yet another embodiment, a method performed by a UE is provided. The method includes receiving a configuration about a CSI report. The configuration includes information about (i) M NZP CSI-RS resources for tracking, where M≥1, (ii) a number (K) of time-domain correlation values, where K≥1, and (iii) delay values τkfor k=0, 1, . . . , K−1. The method further includes, based on the configuration: measuring the M NZP CSI-RS resources for tracking, determining, based on the measurement, the K time-domain correlation values, wherein a k-th correlation value is between two CSI-RS transmission occasions that are separated by one of the delay values τk, and quantizing a value for an amplitude of each of the K time-domain correlation values. The method further includes transmitting the CSI report including an indicator, for each of the K time-domain correlation values, indicating the quantized value of the amplitude.

DETAILED DESCRIPTION

Wireless communication has been one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services exceeded five billion and continues to grow quickly. The demand of wireless data traffic is rapidly increasing due to the growing popularity among consumers and businesses of smart phones and other mobile data devices, such as tablets, “note pad” computers, net books, eBook readers, and machine type of devices. In order to meet the high growth in mobile data traffic and support new applications and deployments, improvements in radio interface efficiency and coverage is of paramount importance.

As described in more detail below, one or more of the UEs111-116include circuitry, programing, or a combination thereof for reporting of time-domain channel correlation properties. In certain embodiments, one or more of the BS s101-103include circuitry, programing, or a combination thereof for providing configuration information for reporting of time-domain channel correlation properties.

FIG.2illustrates an example gNB102according to embodiments of the present disclosure. The embodiment of the gNB102illustrated inFIG.2is for illustration only, and the gNBs101and103ofFIG.1could have the same or similar configuration. However, gNB s come in a wide variety of configurations, andFIG.2does not limit the scope of this disclosure to any particular implementation of a gNB.

As shown inFIG.2, the gNB102includes multiple antennas205a-205n, multiple transceivers210a-240n, a controller/processor225, a memory230, and a backhaul or network interface235.

The transceivers210a-240nreceive, from the antennas205a-205n, incoming RF signals, such as signals transmitted by UEs in the network100. The transceivers210a-240ndown-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in the transceivers210a-240nand/or controller/processor225, which generates processed baseband signals by filtering, decoding, and/or digitizing the baseband or IF signals. The controller/processor225may further process the baseband signals.

The controller/processor225is also capable of executing programs and other processes resident in the memory230, such as processes providing configuration information for reporting of time-domain channel correlation properties as described in embodiments of the present disclosure. The controller/processor225can move data into or out of the memory230as required by an executing process.

The transceiver(s)310receives from the antenna305, an incoming RF signal transmitted by a gNB of the network100. The transceiver(s)310down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by RX processing circuitry in the transceiver(s)310and/or processor340, which generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuitry sends the processed baseband signal to the speaker330(such as for voice data) or is processed by the processor340(such as for web browsing data).

FIG.4andFIG.5illustrate example wireless transmit and receive paths according to this disclosure. In the following description, a transmit path400, ofFIG.4, may be described as being implemented in an gNB or TRP (such as the gNB102or TRP200), while a receive path500, ofFIG.5, may be described as being implemented in a UE (such as a UE116). However, it may be understood that the receive path500can be implemented in a BS or TRP and that the transmit path400can be implemented in a UE. In various embodiments, one or more of the receive path500and/or transmit path400may be implemented in a repeater. In some embodiments, the transmit path400is configured to facilitate reporting of time-domain channel correlation properties as described in embodiments of the present disclosure.

As illustrated inFIG.4, the channel coding and modulation block405receives a set of information bits, applies coding (such as a low-density parity check (LDPC) coding), and modulates the input bits (such as with quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency-domain modulation symbols. The serial-to-parallel block410converts (such as de-multiplexes) the serial modulated symbols to parallel data in order to generate N parallel symbol streams, where N is the IFFT/FFT size used in the gNB102and the UE116. The size N IFFT block415performs an IFFT operation on the N parallel symbol streams to generate time-domain output signals. The parallel-to-serial block420converts (such as multiplexes) the parallel time-domain output symbols from the size N IFFT block415in order to generate a serial time-domain signal. The add cyclic prefix block425inserts a cyclic prefix to the time-domain signal. The up-converter430modulates (such as up-converts) the output of the add cyclic prefix block425to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to the RF frequency.

A transmitted RF signal from the gNB102arrives at the UE116after passing through the wireless channel, and reverse operations to those at the gNB102are performed at the UE116.

A communication system includes a downlink (DL) that conveys signals from transmission points such as base stations (BS s) or NodeBs to user equipments (UEs) and an uplink (UL) that conveys signals from UEs to reception points such as NodeBs. A UE, also commonly referred to as a terminal or a mobile station, may be fixed or mobile and may be a cellular phone, a personal computer device, or an automated device. An eNodeB, which is generally a fixed station, may also be referred to as an access point or other equivalent terminology. For LTE systems, a NodeB is often referred to as an eNodeB.

In a communication system, such as LTE, DL signals can include data signals conveying information content, control signals conveying DL control information (DCI), and reference signals (RS) that are also known as pilot signals. An eNodeB transmits data information through a physical DL Shared channel (PDSCH). An eNodeB transmits DCI through a physical DL control channel (PDCCH) or an enhanced PDCCH (EPDCCH)—see also REF 3. An eNodeB transmits acknowledgement information in response to data transport block (TB) transmission from a UE in a physical hybrid ARQ indicator channel (PHICH). An eNodeB transmits one or more of multiple types of RS including a UE-common RS (CRS), a channel state information RS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DL system bandwidth (BW) and can be used by UEs to obtain a channel estimate to demodulate data or control information or to perform measurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RS with a smaller density in the time and/or frequency domain than a CRS. DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCH and a UE can use the DMRS to demodulate data or control information in a PDSCH or an EPDCCH, respectively. A transmission time interval for DL channels is referred to as a subframe (or slot) and can have, for example, duration of 1 millisecond.

DL signals also include transmission of a logical channel that carries system control information. A BCCH is mapped to either a transport channel referred to as a broadcast channel (BCH) when it conveys a master information block (MIB) or to a DL shared channel (DL-SCH) when it conveys a system information block (SIB)—see also REF 3 and REF 5. Most system information is included in different SIB s that are transmitted using DL-SCH. A presence of system information on a DL-SCH in a subframe (or slot) can be indicated by a transmission of a corresponding PDCCH conveying a codeword with a CRC scrambled with a special system information RNTI (SI-RNTI). Alternatively, scheduling information for a SIB transmission can be provided in an earlier SIB and scheduling information for the first SIB (SIB-1) can be provided by the MIB.

DL resource allocation is performed in a unit of subframe and a group of physical resource blocks (PRBs). A transmission BW includes frequency resource units referred to as resource blocks (RBs). Each RB includes NscRBsub-carriers, or resource elements (REs), such as 12 REs. A unit of one RB over one subframe is referred to as a PRB. A UE can be allocated MPDSCHRBs for a total of MscPDSCH=MPDSCH·NscRBREs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, control signals conveying UL control information (UCI), and UL RS. UL RS includes DMRS and sounding RS (SRS). A UE transmits DMRS only in a BW of a respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate data signals or UCI signals. A UE transmits SRS to provide an eNodeB with an UL CSI. A UE transmits data information or UCI through a respective physical UL shared channel (PUSCH) or a physical UL control channel (PUCCH). If a UE needs to transmit data information and UCI in a same UL subframe, the UE may multiplex both in a PUSCH. UCI includes hybrid automatic repeat request acknowledgement (HARQ-ACK) information, indicating correct (ACK) or incorrect (NACK) detection for a data TB in a PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR) indicating whether a UE has data in the UE's buffer, rank indicator (RI), and channel state information (CSI) enabling an eNodeB to perform link adaptation for PDSCH transmissions to a UE. HARQ-ACK information is also transmitted by a UE in response to a detection of a PDCCH/EPDCCH indicating a release of semi-persistently scheduled PDSCH (see also REF 3).

An UL subframe (or slot) includes two slots. Each slot includes NsymbULsymbols for transmitting data information, UCI, DMRS, or SRS. A frequency resource unit of an UL system BW is an RB. A UE is allocated NRBRBs for a total of NRB·NscRBREs for a transmission BW. For a PUCCH, NRB=1. A last subframe symbol can be used to multiplex SRS transmissions from one or more UEs. A number of subframe symbols that are available for data/UCI/DMRS transmission is Nsymb=2 (NsymbUL−1)−NSRS, where NSRS=1 if a last subframe symbol is used to transmit SRS and NSRS=0 otherwise.

FIG.6illustrates a transmitter block diagram600for a PDSCH in a slot according to embodiments of the present disclosure. The embodiment of the transmitter block diagram600illustrated inFIG.6is for illustration only. One or more of the components illustrated inFIG.6can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.FIG.6does not limit the scope of this disclosure to any particular implementation of the transmitter block diagram600.

As shown inFIG.6, information bits610are encoded by encoder620, such as a turbo encoder, and modulated by modulator630, for example using quadrature phase shift keying (QPSK) modulation. A serial to parallel (S/P) converter640generates M modulation symbols that are subsequently provided to a mapper650to be mapped to REs selected by a transmission BW selection unit655for an assigned PDSCH transmission BW, unit660applies an Inverse fast Fourier transform (IFFT), the output is then serialized by a parallel to serial (P/S) converter670to create a time domain signal, filtering is applied by filter680, and a signal transmitted690. Additional functionalities, such as data scrambling, cyclic prefix insertion, time windowing, interleaving, and others are well known in the art and are not shown for brevity.

FIG.7illustrates a receiver block diagram700for a PDSCH in a slot according to embodiments of the present disclosure. The embodiment of the diagram700illustrated inFIG.7is for illustration only. One or more of the components illustrated inFIG.7can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.FIG.7does not limit the scope of this disclosure to any particular implementation of the diagram700.

As shown inFIG.7, a received signal710is filtered by filter720, REs730for an assigned reception BW are selected by BW selector735, unit740applies a fast Fourier transform (FFT), and an output is serialized by a parallel-to-serial converter750. Subsequently, a demodulator760coherently demodulates data symbols by applying a channel estimate obtained from a DMRS or a CRS (not shown), and a decoder770, such as a turbo decoder, decodes the demodulated data to provide an estimate of the information data bits780. Additional functionalities such as time-windowing, cyclic prefix removal, de-scrambling, channel estimation, and de-interleaving are not shown for brevity.

FIG.8illustrates a transmitter block diagram800for a PUSCH in a slot according to embodiments of the present disclosure. The embodiment of the block diagram800illustrated inFIG.8is for illustration only. One or more of the components illustrated inFIG.6can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.FIG.8does not limit the scope of this disclosure to any particular implementation of the block diagram800.

As shown inFIG.8, information data bits810are encoded by encoder820, such as a turbo encoder, and modulated by modulator830. A discrete Fourier transform (DFT) unit840applies a DFT on the modulated data bits, REs850corresponding to an assigned PUSCH transmission BW are selected by transmission BW selection unit855, unit860applies an IFFT and, after a cyclic prefix insertion (not shown), filtering is applied by filter870and a signal transmitted880.

FIG.9illustrates a receiver block diagram900for a PUSCH in a subframe according to embodiments of the present disclosure. The embodiment of the block diagram900illustrated inFIG.9is for illustration only. One or more of the components illustrated inFIG.9can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.FIG.9does not limit the scope of this disclosure to any particular implementation of the block diagram900.

As shown inFIG.9, a received signal910is filtered by filter920. Subsequently, after a cyclic prefix is removed (not shown), unit930applies an FFT, REs940corresponding to an assigned PUSCH reception BW are selected by a reception BW selector945, unit950applies an inverse DFT (IDFT), a demodulator960coherently demodulates data symbols by applying a channel estimate obtained from a DMRS (not shown), a decoder970, such as a turbo decoder, decodes the demodulated data to provide an estimate of the information data bits980.

In next generation cellular systems, various use cases are envisioned beyond the capabilities of LTE system. Termed 5G or the fifth-generation cellular system, a system capable of operating at sub-6 GHz and above-6 GHz (for example, in mmWave regime) becomes one of the requirements. In 3GPP TR 22.891, 74 5G use cases have been identified and described; those use cases can be roughly categorized into three different groups. A first group is termed “enhanced mobile broadband (eMBB),” targeted to high data rate services with less stringent latency and reliability requirements. A second group is termed “ultra-reliable and low latency (URLL)” targeted for applications with less stringent data rate requirements, but less tolerant to latency. A third group is termed “massive MTC (mMTC)” targeted for large number of low-power device connections such as 1 million per km2with less stringent the reliability, data rate, and latency requirements.

The 3GPP NR specification supports up to 32 CSI-RS antenna ports which enable a gNB to be equipped with a large number of antenna elements (such as 64 or 128). In this case, a plurality of antenna elements is mapped onto one CSI-RS port. For next generation cellular systems such as 5G, the maximum number of CSI-RS ports can either remain the same or increase.

FIG.10illustrates an example antenna blocks or arrays1000according to embodiments of the present disclosure. For example, in various embodiments, the antenna blocks or arrays1000may be implemented in any of the gNBs101-103, the TRP200, and/or the UEs111-116. The embodiment of the antenna blocks or arrays1000illustrated inFIG.10is for illustration only.FIG.10does not limit the scope of this disclosure to any particular implementation of the antenna blocks or arrays1000.

For mmWave bands, although the number of antenna elements can be larger for a given form factor, the number of CSI-RS ports—which can correspond to the number of digitally precoded ports—tends to be limited due to hardware constraints (such as the feasibility to install a large number of ADCs/DACs at mmWave frequencies) as illustrated inFIG.10. In this case, one CSI-RS port is mapped onto a large number of antenna elements which can be controlled by a bank of analog phase shifters1001. One CSI-RS port can then correspond to one sub-array which produces a narrow analog beam through analog beamforming1005. This analog beam can be configured to sweep across a wider range of angles1020by varying the phase shifter bank across symbols or subframes. The number of sub-arrays (equal to the number of RF chains) is the same as the number of CSI-RS ports NCSI-PORT. A digital beamforming unit1010performs a linear combination across NCSI-PORTanalog beams to further increase precoding gain. While analog beams are wideband (hence not frequency-selective), digital precoding can be varied across frequency sub-bands or resource blocks.

To enable digital precoding, efficient design of CSI-RS is a crucial factor. For this reason, three types of CSI reporting mechanism corresponding to three types of CSI-RS measurement can be considered: 1) ‘CLASS A’ CSI reporting which corresponds to non-precoded CSI-RS, 2) ‘CLASS B’ reporting with K=1 CSI-RS resource which corresponds to UE-specific beamformed CSI-RS, 3) ‘CLASS B’ reporting with K>1 CSI-RS resources which corresponds to cell-specific beamformed CSI-RS. For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping between CSI-RS port and TXRU is utilized. Here, different CSI-RS ports have the same wide beam width and direction and hence generally cell wide coverage. For beamformed CSI-RS, beamforming operation, either cell-specific or UE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (including multiple ports). Here, (at least at a given time/frequency) CSI-RS ports have narrow beam widths and hence not cell wide coverage, and (at least from the eNB (or gNB) perspective) at least some CSI-RS port-resource combinations have different beam directions.

In scenarios where DL long-term channel statistics can be measured through UL signals at a serving eNodeB, UE-specific BF CSI-RS can be readily used. This is typically feasible when UL-DL duplex distance is sufficiently small. When this condition does not hold, however, some UE feedback is necessary for the eNodeB to obtain an estimate of DL long-term channel statistics (or any of its representation thereof). To facilitate such a procedure, a first BF CSI-RS transmitted with periodicity T1 (ms), and a second NP CSI-RS transmitted with periodicity T2 (ms), where T1≤T2. This approach is termed hybrid CSI-RS. The implementation of hybrid CSI-RS is largely dependent on the definition of CSI process and NZP CSI-RS resource.

In a wireless communication system, MIMO is often identified as an essential feature in order to achieve high system throughput requirements. One of the key components of a MIMO transmission scheme is the accurate CSI acquisition at the eNB (or gNB) (or TRP). For MU-MIMO, in particular, the availability of accurate CSI is necessary in order to guarantee high MU performance. For TDD systems, the CSI can be acquired using the SRS transmission relying on the channel reciprocity. For FDD systems, on the other hand, it can be acquired using the CSI-RS transmission from eNB (or gNB), and CSI acquisition and feedback from UE. In legacy FDD systems, the CSI feedback framework is “implicit” in the form of CQI/PMI/RI (also CRI and LI) derived from a codebook assuming SU transmission from eNB (or gNB).

In 5G or NR systems (REF 7, REF 8), the above-mentioned “implicit” CSI reporting paradigm from LTE is also supported and referred to as Type I CSI reporting. In addition, a high-resolution CSI reporting, referred to as Type II CSI reporting, is also supported in Release 15 specification to provide more accurate CSI information to gNB for use cases such as high-order MU-MIMO. However, the overhead of Type II CSI reporting can be an issue in practical UE implementations. One approach to reduce Type II CSI overhead is based on frequency domain (FD) compression. In Rel. 16 NR, DFT-based FD compression of the Type II CSI has been supported (referred to as Rel. 16 enhanced Type II codebook in REF 8). Some of the key components for this feature includes (a) spatial domain (SD) basis W1, (b) FD basis Wf, and (c) coefficients {tilde over (W)}2that linearly combine SD and FD basis. In a non-reciprocal FDD system, a complete CSI (comprising all components) needs to be reported by the UE. However, when reciprocity or partial reciprocity does exist between UL and DL, then some of the CSI components can be obtained based on the UL channel estimated using SRS transmission from the UE. In Rel. 16 NR, the DFT-based FD compression is extended to this partial reciprocity case (referred to as Rel. 16 enhanced Type II port selection codebook in REF 8), wherein the DFT-based SD basis in W1is replaced with SD CSI-RS port selection, i.e., L out of

PCSI-RS2
CSI-RS ports are selected (the selection is common for the two antenna polarizations or two halves of the CSI-RS ports). The CSI-RS ports in this case are beamformed in SD (assuming UL-DL channel reciprocity in angular domain), and the beamforming information can be obtained at the gNB based on UL channel estimated using SRS measurements.

It has been known in the literature that UL-DL channel reciprocity can exist in both angular and delay domains if the UL-DL duplexing distance is small. Since delay in time domain transforms (or closely related to) basis vectors in frequency domain (FD), the Rel. 16 enhanced Type II port selection can be further extended to both angular and delay domains (or SD and FD). In particular, the DFT-based SD basis in W1and DFT-based FD basis in W f can be replaced with SD and FD port selection, i.e., L CSI-RS ports are selected in SD and/or M ports are selected in FD. The CSI-RS ports in this case are beamformed in SD (assuming UL-DL channel reciprocity in angular domain) and/or FD (assuming UL-DL channel reciprocity in delay/frequency domain), and the corresponding SD and/or FD beamforming information can be obtained at the gNB based on UL channel estimated using SRS measurements. In Rel. 17, such a codebook is supported (which is referred to as Rel. 17 further enhanced Type II port selection codebook in REF 8).

Various embodiments of the present disclosure recognize that when the UE speed is in a moderate or high speed regime, the performance of the Rel. 15/16/17 codebooks starts to deteriorate quickly due to fast channel variations (which in turn is due to UE mobility that contributes to the Doppler component of the channel), and a one-shot nature of CSI-RS measurement and CSI reporting in Rel. 15/16/17. This limits the usefulness of Rel. 15/16/17 codebooks to low mobility or static UEs only. For moderate or high mobility scenarios, an enhancement in CSI-RS measurement and CSI reporting is needed, which is based on the time-domain (TD) variations or Doppler components of the channel. As described in (REF 9), the Doppler components of the channel remain almost constant over a large time duration, referred to as channel stationarity time, which is significantly larger than the channel coherence time. Note that the current (Rel. 15/16/17) CSI reporting is based on the channel coherence time, which is not suitable when the channel has significant Doppler components. The Doppler components of the channel can be calculated based on measuring a reference signal (RS) burst, where the RS can be CSI-RS or SRS. When RS is CSI-RS, the UE measures a CSI-RS burst, and use it to obtain Doppler components of the DL channel, and when RS is SRS, the gNB measures an SRS burst, and use it to obtain Doppler components of the UL channel. The obtained Doppler components can be reported by the UE using a codebook (as part of a CS report). Or the gNB can use the obtained Doppler components of the UL channel to beamform CSI-RS for CSI reporting by the UE.

FIG.11illustrates channel measurement with and without Doppler components1100according to embodiments of the present disclosure. The embodiment of the channel measurement with and without Doppler components1100illustrated inFIG.11is for illustration only.FIG.11does not limit the scope of this disclosure to any particular implementation of the channel measurement with and without Doppler components.

An illustration of channel measurement with and without Doppler components is shown inFIG.11. When the channel is measured with the Doppler components (e.g., based on an RS burst), the measured channel can remain close to the actual varying channel. On the other hand, when the channel is measured without the Doppler components (e.g., based on a one-shot RS), the measured channel can be far from the actual varying channel.

As described, measuring an RS burst is needed in order to obtain the Doppler components of the channel. Various embodiments of the present disclosure provide several example embodiments on measuring an RS burst (measuring time varying channel over a measurement window) and reporting of TD channel properties (such as Doppler components of the channel).

Various embodiments of the present disclosure provide mechanisms for acquisition of time-domain channel properties (TDCP) at gNB. In particular, various embodiments relate to the reporting of TDCP based on a TRS based RS burst measurement. Various embodiments of the present disclosure provide mechanisms for acquiring details of correlation as a TDCP parameter, reporting details, a codebook for TDCP reporting.

All the following components and embodiments are applicable for UL transmission with CP-OFDM (cyclic prefix OFDM) waveform as well as DFT-SOFDM (DFT-spread OFDM) and SC-FDMA (single-carrier FDMA) waveforms. Furthermore, all the following components and embodiments are applicable for UL transmission when the scheduling unit in time is either one subframe (which can include one or multiple slots) or one slot.

In the present disclosure, the frequency resolution (reporting granularity) and span (reporting bandwidth) of CSI reporting can be defined in terms of frequency “subbands” and “CSI reporting band” (CRB), respectively.

A subband for CSI reporting is defined as a set of contiguous PRBs which represents the smallest frequency unit for CSI reporting. The number of PRB s in a subband can be fixed for a given value of DL system bandwidth, configured either semi-statically via higher-layer/RRC signaling, or dynamically via L1 DL control signaling or MAC control element (MAC CE). The number of PRBs in a subband can be included in CSI reporting setting.

“CSI reporting band” is defined as a set/collection of subbands, either contiguous or non-contiguous, wherein CSI reporting is performed. For example, CSI reporting band can include all the subbands within the DL system bandwidth. This can also be termed “full-band”. Alternatively, CSI reporting band can include only a collection of subbands within the DL system bandwidth. This can also be termed “partial band”.

The term “CSI reporting band” is used only as an example for representing a function. Other terms such as “CSI reporting subband set” or “CSI reporting bandwidth” or bandwidth part (BWP) can also be used.

In terms of UE configuration, a UE can be configured with at least one CSI reporting band. This configuration can be semi-static (via higher-layer signaling or RRC) or dynamic (via MAC CE or L1 DL control signaling). When configured with multiple (N) CSI reporting bands (e.g., via RRC signaling), a UE can report CSI associated with n≤N CSI reporting bands. For instance, >6 GHz, large system bandwidth may require multiple CSI reporting bands. The value of n can either be configured semi-statically (via higher-layer signaling or RRC) or dynamically (via MAC CE or L1 DL control signaling). Alternatively, the UE can report a recommended value of n via an UL channel.

Therefore, CSI parameter frequency granularity can be defined per CSI reporting band as follows. A CSI parameter is configured with “single” reporting for the CSI reporting band with Mnsubbands when one CSI parameter for all the Mnsubbands within the CSI reporting band. A CSI parameter is configured with “subband” for the CSI reporting band with Mnsubbands when one CSI parameter is reported for each of the Mnsubbands within the CSI reporting band.

FIG.12illustrates an example antenna port layout1200according to embodiments of the present disclosure. The embodiment of the antenna port layout1200illustrated inFIG.12is for illustration only.FIG.12does not limit the scope of this disclosure to any particular implementation of the antenna port layout.

As illustrated inFIG.12, N1and N2are the number of antenna ports with the same polarization in the first and second dimensions, respectively. For 2D antenna port layouts, N1>1, N2>1, and for 1D antenna port layouts N1>1 and N2=1. Therefore, for a dual-polarized antenna port layout, the total number of antenna ports is 2N1N2when each antenna maps to an antenna port. An illustration is shown inFIG.12where “X” represents two antenna polarizations. In this disclosure, the term “polarization” refers to a group of antenna ports. For example, antenna ports

j=X+0,X+1,…,X+PCSIRS2-1
comprise a first antenna polarization, and antenna ports

j=X+PCSIRS2,X+PCSIRS2+1,…,X+PCSIRS-1
comprise a second antenna polarization, where PCSIRSis a number of CSI-RS antenna ports and X is a starting antenna port number (e.g., X=3000, then antenna ports are 3000, 3001, 3002, . . . ).

As described in U.S. Pat. No. 10,659,118, issued May 19, 2020, and entitled “Method and Apparatus for Explicit CSI Reporting in Advanced Wireless Communication Systems,” which is incorporated herein by reference in its entirety, a UE is configured with high-resolution (e.g., Type II) CSI reporting in which the linear combination-based Type II CSI reporting framework is extended to include a frequency dimension in addition to the first and second antenna port dimensions.

FIG.13illustrates a 3D grid of oversampled DFT beams1300according to embodiments of the present disclosure. The embodiment of the 3D grid of oversampled DFT beams1300illustrated inFIG.13is for illustration only.FIG.13does not limit the scope of this disclosure to any particular implementation of the 3D grid of oversampled DFT beams.

As illustrated,FIG.13shows a 3D grid1300of the oversampled DFT beams (1st port dim., 2nd port dim., freq. dim.) in which:a 1st dimension is associated with the 1st port dimension,a 2nd dimension is associated with the 2nd port dimension, anda 3rd dimension is associated with the frequency dimension.

The basis sets for 1stand 2ndport domain representation are oversampled DFT codebooks of length-N1and length-N2, respectively, and with oversampling factors O1and O2, respectively. Likewise, the basis set for frequency domain representation (i.e., 3rd dimension) is an oversampled DFT codebook of length-N3and with oversampling factor O3. In one example, O1=O2=O3=4. In one example, O1=O2=4 and O3=1. In another example, the oversampling factors Oibelongs to {2, 4, 8}. In yet another example, at least one of O1, O2, and O3is higher layer configured (via RRC signaling).

As explained in Section 5.2.2.2.6 of REF 8, a UE is configured with higher layer parameter codebookType set to ‘typeII-PortSelection-r16’ for an enhanced Type II CSI reporting in which the pre-coders for all SBs and for a given layer l=1, . . . , v, where v is the associated RI value, is given by either:

Wl=A⁢Cl⁢BH=[a0⁢a1⁢…⁢aL-1][cl,0,0cl,0,1…cl,0,M-1cl,1,0cl,1,1…cl,1,M-1⋮⋮⋮⋮cl,L-1,0cl,L-1,1…cl,L-1,M-1][b0⁢b1⁢…⁢bM-1]H=∑f=0M-1⁢∑i=0L-1⁢cl,i,f(ai⁢bfH)=∑i=0L-1⁢∑f=0M-1⁢cl,i,f(ai⁢bfH),(Eq.1)orWl=[A00A]⁢Cl⁢BH=[a0⁢a1⁢…⁢aL-100a0⁢a1⁢…⁢aL-1][cl,0,0cl,0,1…cl,0,M-1cl,1,0cl,1,1…cl,1,M-1⋮⋮⋮⋮cl,L-1,0cl,L-1,1…cl,L-1,M-1]⁢[b0⁢b1⁢…⁢bM-1]H=[∑f=0M-1⁢∑i=0L-1⁢cl,i,f(ai⁢bfH)∑f=0M-1⁢∑i=0L-1⁢cl,i+L,f(ai⁢bfH)],(Eq.2)
where:N1is a number of antenna ports in a first antenna port dimension (having the same antenna polarization),N2is a number of antenna ports in a second antenna port dimension (having the same antenna polarization),PCSI-RSis a number of CSI-RS ports configured to the UE,N3is a number of SB s for PMI reporting or number of FD units or number of FD components (that comprise the CSI reporting band) or a total number of precoding matrices indicated by the PMI (one for each FD unit/component),aiis a 2N1N2×1 (Eq. 1) or N1N2×1 (Eq. 2) column vector, and aiis a N1N2×1 port selection column vector if antenna ports at the gNB are co-polarized, and is a 2N1N2×1 port selection column vector if antenna ports at the gNB are dual-polarized or cross-polarized, where a port selection vector is a defined as a vector which contains a value of 1 in one element and zeros elsewhere,bfis a N3×1 column vector,cl,i,fis a complex coefficient.

In a variation, when the UE reports a subset K<2LM coefficients (where K is either fixed, configured by the gNB or reported by the UE), then the coefficient cl,i,fin precoder equations Eq. 1 or Eq. 2 is replaced with xl,i,f×cl,i,f, where:xl,i,f=1 if the coefficient cl,i,fis reported by the UE according to some embodiments of this disclosure.xl,i,f=0 otherwise (i.e., cl,i,fis not reported by the UE).

The indication whether xl,i,f=1 or 0 is according to some embodiments of this disclosure. For example, it can be via a bitmap.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectively generalized to:

Wl=∑i=0L-1⁢∑f=0Mi-1⁢cl,i,f(ai⁢bi,fH),(Eq.3)andWl=[∑i=0L-1⁢∑f=0Mi-1⁢cl,i,f(ai⁢bi,fH)∑i=0L-1⁢∑=0Mi-1⁢cl,i+L,f(ai⁢bi,fH)],(Eq.4)
where for a given i, the number of basis vectors is Miand the corresponding basis vectors are {bi,f}. Note that Miis the number of coefficients cl,i,freported by the UE for a given i, where Mi≤M (where {Mi} or ΣMiis either fixed, configured by the gNB or reported by the UE).

The columns of Wlare normalized to norm one. For rank R or R layers (v=R), the pre-coding matrix is given by

W(R)=1R[W1W2…WR].
Eq. 2 is assumed in the rest of the disclosure. The embodiments of the disclosure, however, are general and are also application to Eq. 1, Eq. 3, and Eq. 4.

L≤PCSI-RS2
and M<N3. If

L=PCSI-RS2,
then A is an identity matrix, and hence not reported. Likewise, if M=N3, then B is an identity matrix, and hence not reported. Assuming M<N3, in an example, to report columns of B, the oversampled DFT codebook is used. For instance, bf=wf, where the quantity wfis given by:

When O3=1, the FD basis vector for layer l∈{1, . . . , v} (where v is the RI or rank value) is given by:
wf=[y0,l(f)y1,l(f). . . yN3−1,l(f)]T,
where

In another example, discrete cosine transform DCT basis is used to construct/report basis B for the 3rddimension. The m-th column of the DCT compression matrix is simply given by:

Since DCT is applied to real valued coefficients, the DCT is applied to the real and imaginary components (of the channel or channel eigenvectors) separately. Alternatively, the DCT is applied to the magnitude and phase components (of the channel or channel eigenvectors) separately. The use of DFT or DCT basis is for illustration purpose only. The disclosure is applicable to any other basis vectors to construct/report A and B.

On a high level, a precoder Wlcan be described as follows:
W=AlClBlH=W1{tilde over (W)}2WfH,  (Eq. 5)
where A=W1corresponds to the Rel. 15 W1in Type II CSI codebook (REF 8), and B=Wf.

The Cl={tilde over (W)}2matrix includes all the required linear combination coefficients (e.g., amplitude and phase or real or imaginary). Each reported coefficient (cl,i,f=pl,i,fϕl,i,f) in {tilde over (W)}2is quantized as amplitude coefficient (pl,i,f) and phase coefficient (ϕl,i,f). In one example, the amplitude coefficient (pl,i,f) is reported using a A-bit amplitude codebook where A belongs to {2, 3, 4}. If multiple values for A are supported, then one value is configured via higher layer signalling. In another example, the amplitude coefficient (pl,i,f) is reported as pl,i,f=pl,i,f(1)pl,i,f(2)where:pl,i,f(1)is a reference or first amplitude which is reported using a A1-bit amplitude codebook where A1 belongs to {2, 3, 4}, andpl,i,f(2)is a differential or second amplitude which is reported using a A2-bit amplitude codebook where A2≤A1 belongs to {2, 3, 4}.

For layer 1, let us denote the linear combination (LC) coefficient associated with spatial domain (SD) basis vector (or beam) i∈{0, 1, . . . , 2L−1} and frequency domain (FD) basis vector (or beam) f∈{0, 1, . . . , M−1} as cl,i,f, and the strongest coefficient as cl,i*,f*. The strongest coefficient is reported out of the KNZnon-zero (NZ) coefficients that is reported using a bitmap, where KNZ≤K0=┌β×2LM┐<2LM and β is higher layer configured. The remaining 2LM−KNZcoefficients that are not reported by the UE are assumed to be zero. The following quantization scheme is used to quantize/report the KNZNZ coefficients:UE reports the following for the quantization of the NZ coefficients in {tilde over (W)}2:An X-bit indicator for the strongest coefficient index (i*, f*), where X=┌log2KNZ┐ or ┌log22L┐.Strongest coefficient cl,i*,f*=1 (hence its amplitude/phase are not reported).Two antenna polarization-specific reference amplitudes are used.For the polarization associated with the strongest coefficient cl,i*,f*=1 since the reference amplitude pl,i,f(1)=1, it is not reported.For the other polarization, reference amplitude pl,i,f(1)is quantized to 4 bits:The 4-bit amplitude alphabet is

{1,(12)14,(14)14,(18)14,…,(121⁢4)14}.For {cl,i,f, (i,f)≠(i*, f*)}:For each polarization, differential amplitudes pl,i,f(2)of the coefficients calculated relative to the associated polarization-specific reference amplitude and quantized to 3 bits:The 3-bit amplitude alphabet is

{1,12,12,12⁢2,14,14⁢2,18,18⁢2}.Note: The final quantized amplitude pl,i,fis given by pl,i,f(1)×pl,i,f(2).Each phase is quantized to either 8 PSK (Nph=8) or 16 PSK (Nph=16) (which is configurable).

For the polarization r*∈{0,1} associated with the strongest coefficient cl,i*,f*, we have

r*=⌊i*L⌋
and the reference amplitude pl,i,f(1)=pl,r*(1)=1. For the other polarization r⊂{0,1} and r≠r*, we have

r=(⌊i*L⌋+1)
mod 2 and the reference amplitude pl,i,f(1)=pl,r(1)is quantized (reported) using the 4-bit amplitude codebook mentioned above.

A UE can be configured to report M FD basis vectors. In one example,

M=⌈p×N3R⌉,
where R is higher-layer configured from {1,2} and p is higher-layer configured from {¼, ½}. In one example, the p value is higher-layer configured for rank 1-2 CSI reporting. For rank >2 (e.g., rank 3-4), the p value (denoted by v0) can be different. In one example, for rank 1-4, (p, v0) is jointly configure from {½, ¼, ¼, ¼, ¼, ⅛}, i.e.,

M=⌈p×N3R⌉
for rank 1-2 and

M=⌈v0×N3R⌉
for rank 3-4. In one example, N3=NSB×R where NSBis the number of SBs for CQI reporting. In the rest of the disclosure, M is replaced with Mvto show its dependence on the rank value v, hence p is replaced with pv, v∈{1,2} and v0is replaced with pv, v∈{3,4}.

A UE can be configured to report MvFD basis vectors in one-step from N3basis vectors freely (independently) for each layer l∈{1, . . . , v} of a rank v CSI reporting. Alternatively, a UE can be configured to report MvFD basis vectors in two-step as follows:In step 1, an intermediate set (InS) comprising N′3<N3basis vectors is selected/reported, wherein the InS is common for all layers.In step 2, for each layer l∈{1, . . . , v} of a rank v CSI reporting, MvFD basis vectors are selected/reported freely (independently) from N′3basis vectors in the InS.

In one example, one-step method is used when N3≤19 and two-step method is used when N3>19. In one example, N′3=┌αMv┐ where α>1 is either fixed (to 2 for example) or configurable.

The codebook parameters used in the DFT based frequency domain compression (eq. 5) are (L, pvfor v∈{1,2}, pvfor v∈{3,4}, β, α, Nph). In one example, the set of values for these codebook parameters are as follows:L: the set of values is {2,4} in general, except L∈{2,4,6} for rank 1-2, 32 CSI-RS antenna ports, and R=1.(pvfor v∈{1,2}, pvfor v∈{3,4})∈{(½, ¼), (¼, ¼), (¼, ⅛)}.β∈{¼, ½,¾}.α=2Nph=16.

The set of values for these codebook parameters are as in Table 1.

In Rel. 17 (further enhanced Type II port selecting codebook),

TABLE 2paramCombination-r17Mαβ11¾½211½311¾411152½½62¾½721½821¾
where K1=α×PCSIRS, and codebook parameters (M, α, β) are configured from Table 2.

The above-mentioned framework (Eq. 5) represents the precoding-matrices for multiple (N3) FD units using a linear combination (double sum) over 2 L SD beams and M, FD beams. This framework can also be used to represent the precoding-matrices in time domain (TD) by replacing the FD basis matrix Wfwith a TD basis matrix Wt, wherein the columns of Wtcomprises MvTD beams that represent some form of delays or channel tap locations. Hence, a precoder Wlcan be described as follows:
W=AlClBlH=W1{tilde over (W)}2WtH,  (Eq. 5A)

In one example, the MvTD beams (representing delays or channel tap locations) are selected from a set of N3TD beams, i.e., N3corresponds to the maximum number of TD units, where each TD unit corresponds to a delay or channel tap location. In one example, a TD beam corresponds to a single delay or channel tap location. In another example, a TD beam corresponds to multiple delays or channel tap locations. In another example, a TD beam corresponds to a combination of multiple delays or channel tap locations.

Various embodiments of the present disclosure are applicable to both space-frequency (Eq. 5) and space-time (Eq. 5A) frameworks.

The present disclosure focuses on a measuring a CS-RS burst that can be used to obtain time-domain (TD) or Doppler-domain (DD) component(s)/properties of the channel. The measured channel can be used to report TDCP or DD components, either alone (separate) or together with the other CSI components (e.g., based on space-frequency compression).

FIG.14illustrates an example of a UE configured to receive a burst of non-zero power (NZP) CSI-RS resource(s)1400according to embodiments of the present disclosure. The embodiment of the example of a UE configured to receive a burst of non-zero power (NZP) CSI-RS resource(s)1400illustrated inFIG.14is for illustration only.FIG.14does not limit the scope of this disclosure to any particular implementation of the example of a UE configured to receive a burst of non-zero power (NZP) CSI-RS resource(s).

In one embodiment, as shown inFIG.14, a UE is configured to receive a burst of non-zero power (NZP) CSI-RS resource(s), referred to as CSI-RS burst for brevity, within B time slots comprising a measurement window, where B¢1. The B time slots can be accordingly to at least one of the following examples:In one example, the B time slots are evenly/uniformly spaced with an inter-slot spacing d.In one example, the B time slots can be non-uniformly spaced with inter-slot spacing e1=d1, e2=d2−d1, e3=d3−d2, . . . , so on, where ei≠ejfor at least one pair (i,j) with i≠j.

The UE receives the CSI-RS burst, estimates the B instances of the DL channel measurements, and uses the channel estimates to obtain the Doppler component(s) of the DL channel. The CSI-RS burst can be linked to (or associated with) a single CSI reporting setting (e.g., via higher layer parameter CSI-ReportConfig), wherein the corresponding CSI report includes an information about the Doppler component(s) of the DL channel.

Let it htbe the DL channel estimate based on the CSI-RS resource(s) received in time slot t∈{0, 1, . . . , B−1}. When the DL channel estimate in slot t is a matrix Gtof size NRx×NTx×NSc, then it ht=vec(Gt), where NRx, NTx, and NScare number of receive (Rx) antennae at the UE, number of CSI-RS ports measured by the UE, and number of subcarriers in frequency band of the CSI-RS burst, respectively. The notation vec(X) is used to denote the vectorization operation wherein the matrix X is transformed into a vector by concatenating the elements of the matrix in an order, for example, 1→2→3→ and so on, implying that the concatenation starts from the first dimension, then moves second dimension, and continues until the last dimension. Let HB=[h0h1. . . hB-1] be a concatenated DL channel. The Doppler component(s) of the DL channel can be obtained based on HB. For example, HBcan be represented as CΦH=Σs=0N-1csϕsHwhere Φ=[ϕ0ϕ1. . . ϕN−1] is a Doppler domain (DD) basis matrix whose columns comprise basis vectors, C=[c0c1. . . cN−1] is a coefficient matrix whose columns comprise coefficient vectors, and N<B is the number of DD basis vectors. Since the columns of HBare likely to be correlated, a DD compression can be achieved when the value of N is small (compared to the value of B). In this example, the Doppler component(s) of the channel is represented by the DD basis matrix Φ and the coefficient matrix C.

In one embodiment, a UE is configured to determine/report a CSI report, where the CSI report includes TDCP or Doppler component(s) of the channel. Such a configuration can be via higher layer CSI-ReportConfig including reportQuantity or reportQuantity-r18 set to ‘new quantity’ or ‘TDCP’ or ‘DD’, where ‘new quantity’ corresponds to at least one of the following.

In one example, ‘new quantity’ or ‘TDCP’ or ‘DD’ is (or is based on or corresponds to) Doppler spread.

In one example, ‘new quantity’ or ‘TDCP’ or ‘DD’ is (or is based on or corresponds to) Doppler shift.

In one example, ‘new quantity’ or ‘TDCP’ or ‘DD’ is (or is based on or corresponds to) UE speed.

In one example, ‘new quantity’ or ‘TDCP’ or ‘DD’ is (or is based on or corresponds to) time-domain correlation.In one example, a linear prediction model is assumed to predict channel coefficient(s) (amplitude/phase) variations over time.In one example, the linear prediction model corresponds to ct=p1×ct-1, where ctis a predicted channel coefficient at time slot t, and p1is a predictor coefficient. When t=1 (reference time), c0is a reference predictor coefficient, which can correspond to a reference (e.g., CSI reference resource) or a latest (Typell) CSI reported in an earlier slot.In one example, the linear prediction model corresponds to ct=p1×ct-1+p2×ct-2, where ctis a predicted channel coefficient at time slot t, and pifor i=1,2 is a predictor coefficient. When t=1 (reference time), c0is a reference predictor coefficient, which can correspond to a reference (e.g., CSI reference resource) or a latest (Typell) CSI reported in an earlier slot.In one example, the linear prediction model corresponds to ct=Σi=1ppict-i, where p is a number (length) of predictor coefficients, ctis a predicted channel coefficient at time slot t, and pifor i=1,2 is a predictor coefficient. When t=1 (reference time), c0is a reference predictor coefficient, which can correspond to a reference (e.g., CSI reference resource) or a latest (Type II) CSI reported in an earlier slot.In one example, a time-domain or DD compression is used to report time domain correlation. For example, a CSI-RS burst (e.g., based on a TRS) measured within a measurement window, details as described in this disclosure, can be used to obtain time-domain channel measurements within the measurement window and a Type II (linear combination of basis vectors) like framework is used to report compressed time-domain or DD channel components. In one example, the reported content includes a set of N basis vectors (e.g., TD or DD basis vectors) Φ=[ϕ0ϕ1. . . ϕN−1] (e.g., DFT) and corresponding coefficients {c0, . . . cN−1}. In one example, vectors ϕ0ϕ1. . . ϕN-1can be length-N orthogonal DFT vectors. In one example, each coefficient is represented as cn=anϕn, where anand ϕnrespectively are amplitude (or power) and phase values. In one example, amplitude/phase of all N coefficients are reported. In one example, amplitude/phase of N−1 coefficients are reported, and amplitude/phase of the one remaining coefficient cn*is not reported. The amplitude/phase of the coefficient cn*can be fixed (e.g., to 1). The index n* of the coefficient cn*can be fixed (e.g., to 1), or reported (e.g., as part of the reporting as the strongest/reference coefficient index), or is configured to the UE (e.g., via higher layer, or MAC CE, or DCI).In one example, the time domain correlation reporting corresponds to K≥1 (normalized) time domain correlation(s) calculated lag(s) or delay(s) or tap(s) τkwhere k=0, 1, . . . , K−1. The details of such reporting are provided in the following embodiment herein.

In one embodiment, a UE is configured with a CSI reporting (e.g., via higher layer) associated with at least one CSI-RS resource for tracking (i.e., at least one TRS resource), where the CSI report includes a quantized version of time domain correlation(s) associated with K≥1 delays or lags or taps, which can be calculated based on a correlation (or auto-correlation) profile of the measured DL channel.

When the K tap/lag values are fixed or configured to the UE, the CSI report includes the K correlation or auto-correlation values corresponding to the K lags/taps.

When the K tap/lag values are also reported by the UE, the CSI report includes both (A) K tap/lag values, and (B) the K correlation or auto-correlation values corresponding to the K lags/taps.

The UE determines/calculates the correlation (or auto-correlation) profile of the measured DL channel, which corresponds to N time domain correlation values associated with N delays/taps/lags, and selects K (out of N) “strongest” delays/lags/taps whose time domain correlation (or auto-correlation) values are “strong”, e.g., the absolute value of the correlation (or auto-correlation) is the highest/largest.

In one example, the unit of the lag/delay/tap values is in terms of number of time slots.

In one example, the unit of the lag/delay/tap values is in terms of number of OFDM symbols.

In one example, at least one of the following examples is used/configured regarding the calculation of time domain correlation(s).

In one example, the time domain correlation for a delay/lag/tap r can be calculated in the frequency domain as

c⁡(τ)=1γ⁢∑s=1S⁢∑f=0F-1⁢(Q),
where Q=Xt2(s),fX*t1(s),for Xt1(s),fX*2z(s),for X*t1(s),fXt2(s),for X*t2(s),fXt1(s),f, γ or Yf(t1(s)+τ)Y*f(ts(s)) (assuming t2(s)−t1(s)=τ, we have Xt2(s),f=Yf(t1(s)+τ) and Xt1(s),f=Yf(t1(s)) is a normalization factor, S is the number of symbol pairs such that their (relative) tap/lag is τ, i.e., t2(s)−t1(s)=τ, F is the number of subcarriers carrying the TRS resource(s) for measurement, and Xt,fis the TRS resource measured at a time-frequency RE location (t, f). In one example, γ=SF. In one example,

γ=12⁢∑s=1S⁢∑f=0F-1⁢(Xt1(s),f⁢Xt1(s),f*+Xt2(s),f⁢Xt2(s),f*).
In one example, γ=√{square root over (Σs=1SΣf=0F-1|Xt1(s),f|2)}√{square root over (Σs=1SΣf=0F-1|Xt2(s),f|2)}.

If S=1, then

c⁡(τ)=1γ⁢∑s=1S⁢∑f=0F-1⁢(Xt2(s),f⁢Xt1(s),f*).
In one example, γ=√{square root over (SF)}. In one example,

γ=12⁢∑s=1S⁢∑f=0F-1(Xt1(s),f⁢Xt1(s),f*+Xt2(s),f⁢Xt2(s),f*).
In one example, γ2=√{square root over (Σs=1SΣf=0F-1|Xt1(s),f|2)}√{square root over (Σs=1SΣf=0F-1|Xt2(s),f|2)}.

In one example, the time domain correlation for a delay/lag/tap γ can be calculated in the frequency domain as d(τ)=|c(τ)|sign(c τ)), where c(τ) is according to one examples in example I.1A.1.1, and sign(x) is the sign of a number x, i.e., sign(x)=+1 when x≥0 and sign(x)=−1 when x<0.

In one example, the time domain correlation for a delay/lag/tap r can be calculated in the time domain as

c⁡(τ)=1γ⁢∑s=1S⁢∑d=0D-1⁢(Yt2(s),d⁢Yt1(s),d*),
where Yt,d=ifft(Xt,f), γ is a normalization factor, S is the number of symbol pairs such that their (relative) tap/lag is τ, i.e., t2(s)=t1(s)=τ, T is the number of time delays associated with the TRS resource(s) for measurement, and Yt,dis the TRS resource associated with a time-delay pair (t, d). In one example, γ=SF. In one example,

c⁡(τ)=1γ⁢∑s=1S⁢∑f=0F-1⁢(Yt2(s),d⁢Yt1(s),d*).
In one example, γ=√{square root over (SF)}. In one example,

In one example, the time domain correlation for a delay/lag/tap r can be calculated in the time domain as d(τ)=|c(τ)|sign(c τ)), where c(τ) is according to one of the examples herein.

In one example, at least one of the following examples is used/configured regarding the number of TRS resource(s) configured for reporting/calculation of time domain correlation(s).

In one example, the UE is configured with such CSI reporting based on a M=1 TRS resource (i.e., intra TRS reporting). Let p be the periodicity of the TRS resource, then the set of candidate lag values include τ=0, p, 2p, . . . , i.e., τ∈{n×p: n=0, 1, 2 . . . }. In one example, p can be configured via higher layer parameter periodicityAndOffset in IE NZP-CSI-RS-Resource that configures the TRS resource.In one example, the maximum value of n is fixed (e.g., n=1 or 2).In one example, the maximum value of n is configured (e.g., via RRC).In one example, the maximum value of n is determined based on a threshold on the correlation (auto-correlation value), e.g., the value of n is such that the corresponding correlation c(n*) is c(n*)≥thr×c(0), where thr is a threshold value (fixed, configured, or reported by the UE).In one example, the set of values of n for the candidate lag values for the CSI reporting is fixed (e.g., n=0, 1, 2).In one example, the set of values of n for the candidate lag values for the CSI reporting is configured (e.g., via RRC).In one example, the set of values of n for the candidate lag values for the CSI reporting is determined based on a threshold on the correlation (auto-correlation value).

In one example, the UE is configured with such CSI reporting based on M>1 TRS resources (i.e., inter TRS reporting). The multiple TRS resources can be configured via a TRS resource set (e.g., multiple TRS resources in the same TRS resource set) or multiple TRS resource sets (e.g., 2 sets).

In one example, M=2. Let p1and p2be the periodicities of the two TRS resources and o1and o2be the offsets of the two TRS resources. In one example, p1and o1can be configured via higher layer parameter periodicityAndOffset in IE NZP-CSI-RS-Resource corresponding to the i-th TRS resource.

In one example, only one value corresponding to M>1 is allowed/supported (e.g., 2 or 4).

In one example, M=4 for frequency range 1 (FR1). In one example, M=2 for FR2.

In one example, when M=4, an NZP-CSI-RS-ResourceSet includes four periodic NZP CSI-RS resources in two consecutive slots with two periodic NZP CSI-RS resources in each slot.

In one example, when M=2, an NZP-CSI-RS-ResourceSet includes two periodic CSI-RS resources in one slot.

In one example, the UE is configured with such CSI reporting based on a M=1 TRS resource or M>1 TRS resources, where the value of M is configured. When M=1, the details are according to examples herein, and when M>1, the details are according to examples herein.

In one example, at least one of the following examples is used/configured regarding the value of K for reporting/calculation of time domain correlation(s).

In one example, the value of K can be fixed, e.g., K=4.

In one example, the value of K can be configured, e.g., via higher layer RRC signaling, or/and indicated via MAC CE or/and DCI (e.g., as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report).

In one example, the value of K can be determined based on a threshold. The threshold can be relative to the τ(0).

In one example, the value of K can be reported by the UE, e.g., via UCI part 1 of a two-part UCI comprising UCI part 1 and UCI part 2.

In one example, the max value of K or the set of supported values of K can be reported by the UE via UE capability reporting. If the UE reports the support for multiple K values, one of them can be configured, e.g., via higher layer, or MAC CE or DCI (e.g., as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report).

In one example, the max value of K (say Kmax) is configured (e.g., via RRC) or indicated via MAC CE or/and DCI (e.g., as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report), and the UE can report k≤Kmaxcorrelation(s) or auto-correlation value(s). In this case, a value of k or, optionally, an indicator related to or usable to infer a payload size (or the number of correlation values k) of the report, can be reported via UCI part 1 of a two-part UCI comprising UCI part 1 and UCI part 2 (which can be transmitted on PUCCH or PUSCH). Or, a value of k or, optionally, an indicator related to or usable to infer a payload size (or the number of correlation values k) of the report, can be reported via a (one part) UCI (which can be transmitted on PUCCH). In case of PUCCH, in order to ensure a fixed payload size (number of bits) for this reporting, a number of zero-padding bits can be appended with the CSI reported.

In one example, the value of K can also be a function of the period or/and offset of TRS resource(s).

In one example, the value of K (or the value of k≤K) is signaled to the UE as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report including the correlation or auto-correlation value(s), or indicator(s) indicating the correlation or auto-correlation value(s).

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is also reported by the UE. For instance, the CSI report can also include an indicator indicating the value of the threshold either in UCI part 1 or in UCI part 2.

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is also reported by the UE together with the value K. For instance, the CSI report can also include a joint indicator or two separate indicators indicating the values of θ and K. When a joint indicator is used, it can be reported via either in UCI part 1 or in UCI part 2. When two separate indicators are used, they can be reported together via either UCI part 1 or UCI part, or separately, one via UCI part 1 and another via UCI part 2.

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is also reported by the UE together with the value k≤K. For instance, the CSI report can also include a joint indicator or two separate indicators indicating the values of θ and k. When a joint indicator is used, it can be reported via either in UCI part 1 or in UCI part 2. When two separate indicators are used, they can be reported together via either UCI part 1 or UCI part, or separately, one via UCI part 1 and another via UCI part 2.

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is signaled to the UE as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report including the correlation or auto-correlation value(s), or indicator(s) indicating the correlation or auto-correlation value(s).

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is signaled to the UE together with the value K as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report including the correlation or auto-correlation value(s), or indicator(s) indicating the correlation or auto-correlation value(s). For instance, the CSI request field can indicate a triggering state that includes either a joint indicator//parameter or two separate indicators/parameters indicating the values of θ and K.

In one example, the value of the threshold (θ) on the correlation (auto-correlation) value(s) is signaled to the UE together with the value k≤K as a part of the triggering state of the CSI request field in the DCI that triggers an aperiodic reporting of the CSI report including the correlation or auto-correlation value(s), or indicator(s) indicating the correlation or auto-correlation value(s). For instance, the CSI request field can indicate a triggering state that includes either a joint indicator/parameter or two separate indicators/parameters indicating the values of θ and k.

In one example, at least one of the following examples is used/configured regarding the reporting/calculation of K correlation value(s).

In one example, the reporting is absolute, i.e., each of K values are determined/reported independently from other values.

In one example, the reporting is differential (relative) w.r.t. a reference. In one example, the reference is r=0, the lag/tap 0. That is, the correlation value corresponding to a tap/lag r=k is reported/determined w.r.t. to the same corresponding to r=0.

In one example, the differential/relative correlation is determined as c′(k)=c(k)−c(0).

The UE reports correlation c(0) for r=0, and c′(k) for r=k≠0

In one example, the differential/relative correlation is determined as

c′(k)=c⁡(k)c⁡(0).
The UE reports correlation c(0) for r=0, and c′(k) for r=k≠0.

In one example, at least one of the following examples is used/configured regarding the frequency domain granularity of the reporting/calculation of K correlation value(s).

In one example, the reporting/calculation of K correlation value(s) is in a wideband (WB) manner, i.e., K correlation values are reported common for the entire CSI reporting band.

In one example, the reporting/calculation of K correlation value(s) is in a subband (SB) manner, i.e., K correlation values are reported for each SB in the CSI reporting band.

In one example, at least one of the following examples is used/configured regarding the indicator(s) indicating the K correlation value(s).

In one example, the CSI report includes an (one joint) indicator which indicates K correlation or auto-correlation values jointly.

In one example, the CSI report includes a separate indicator for each of the K correlation or auto-correlation values.

In one example, when indices of the K lags/taps are also reported, the CSI report also includes one (joint) indicator which indicates the indices of the K taps/labs, or K separate indicators, one for each of the K taps/lags. The CSI report also induces one joint indicator (see examples herein) or separate indicators (see examples herein) indicating the corresponding K correlation values.

In one example, at least one of the following examples is used/configured regarding the codebook to indicate the amplitude or/and phase of the K correlation value(s).

In one example, amplitude of each of the K values are reported using b bits.In one example, b=2. The 4 values are uniform in a dB scale, [x, x−y, x−2y, x−3y] or, [x−y, x−2y, x−3y, x−4y]. In one example, x=0. In one example, y=3. In one example, y= 3/2=1.5. In one example, y=1.In one example, b=2. The 4 values are uniform in a dB scale, [x, x−y, x−2y, x−3y] or, [x−y, x−2y, x−3y, x−4y]. In one example, x=0 or x=−ay, where a>0 (e.g., a=7 or 8 or 9 or 3 or 4 or 5). In one example, y=3. In one example, y= 3/2=1.5. In one example, y=1.In one example, x is fixed, (e.g., x=0 or x=−ay, where a>0), and y is also fixed (e.g., y=3, 3/2=1.5, or 1).In one example, x is fixed, (e.g., x=0 or x=−ay, where a>0), and y is configured (e.g., y=3, 3/2=1.5, or 1 based on RRC signaling).In one example, x is configured, (e.g., x=0 or x=−ay, where a>0 based on RRC signaling), and y is configured (e.g., y=3, 3/2=1.5, or 1 based on RRC signaling).In one example, x is configured, (e.g., x=0 or x=÷ay, where a>0 based on RRC signaling), y is fixed (e.g., y=3, 3/2=1.5, or 1).In one example, b=2. The 4 values are uniform in a linear scale,

[x,xy,(xy)2,(xy)3]⁢or[x,xy,xy,(xy)32].
In one example, x=1. In one example, y=2.In one example, b=2 and 4 values are 1−v, where v is one of the first four values (Indicator 0-3) of Table 3, i.e.,

{18⁢2,18,14⁢2,14}.In one example, b=2 and 4 values are 1−v2where v is one of the first four values (Indicator 0-3) of Table 3, i.e.,

{18⁢2,18,14⁢2,14}.
Equivalently, 4 values are 1−u, where u is one of the values { 1/128, 1/64, 1/32, 1/16}.In one example, b=2 and 4 values are 1−v, where v is one of the first four values (Indicator 0-3) of Table 4, i.e.,

{(13⁢2⁢7⁢6⁢8)1/4,1128,(18⁢1⁢9⁢2)1/4,18}.
Or equivalently, 4 values are {0.9257 0.9116 0.8949 0.87501}.In one example, b=2 and 4 values are 1−v2where v is one of the first four values (Indicator 0-3) of Table 4, i.e.,

{(132768)1/4,1128,(18192)1/4,18}.
Equivalently, 4 values are 1−u, where u is one of the values

{(121⁢5)1/n,(121⁢4)1/n,(121⁢3)1/n,(121⁢2)1/n},
where n is fixed or configured from e.g., 2, or 2.5 (5/2), 3, or 3.5 (7/2) or 4 or 4.5 (9/2) or 5.In one example, b=2 and 4 values are 1−v, where v is one of the 4 values

{(12B)1/n,(12B-1)1/n,(12B-2)1/n,(12B-3)1/n},
where n is fixed or configured from e.g., 2, or 2.5 (5/2), 3, or 3.5 (7/2) or 4 or 4.5 (9/2) or 5, and B is fixed or configured from {20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10}.In one example, b=2 and 4 values are 1−v, where v is one of the 4 values

{(12C+7)1/n,(12C+6)1/n,(12C+5)1/n,(12C+4)1/n},
where n is fixed or configured from e.g., 2, or 2.5 (5/2), 3, or 3.5 (7/2) or 4 or 4.5 (9/2) or 5, and C is fixed or configured from {12,11,10,9,8,7,6}.In one example, b=3. The 8 values are uniform in a dB scale, [x, x−y, x−2y, . . . , x−7y], In one example, x=0. In one example, y=3. In one example, y= 3/2=1.5.In one example, b=3. The 8 values are uniform in a linear scale,

[x,xy,(xy)2,…,(xy)7]⁢or[x,xy,xy,…,(xy)72].
In one example, x=1. In one example, y=2. In one example, the 8 values are as shown in Table 3.In one example, b=3 and 8 values are 1−v, where v is one of the first 8 values (Indicator 0-7) of Table 3, i.e.,

{18⁢2,18,14⁢2,14,12⁢2,12,12,1}.In one example, b=3 and 8 values are 1−v2 where v is one of the first 8 values (Indicator 0-7) of Table 3, i.e.,

{18⁢2,18,14⁢2,14,12⁢2,12,12,1}.
Equivalently, 8 values are 1−u, where u is one of the values { 1/128, 1/64, 1/32, 1/16⅛, ¼, ½, 1}.In one example, b=3 and 8 values are 1−v, where v is one of the first 8 values (Indicator 0-7) of Table 4, i.e.,

{(132768)1/4,1128,(18192)1/4,18,(12048)1/4,12⁢8,(1512)1/4,14}.
Equivalently, 8 values are 1−u, where u is one of the values

{(121⁢5)1/n,(121⁢4)1/n,(121⁢3)1/n,(121⁢2)1/n,(121⁢1)1/n,(121⁢0)1/n,(129)1/n,(128)1/n},
where n is fixed or configured from e.g., 2, or 2.5 (5/2), 3, or 3.5 (7/2) or 4 or 4.5 (9/2) or 5.In one example, b=3 and 8 values are 1−v, where v is one of the 8 values

{(12B)1/n,(12B-1)1/n,(12B-2)1/n,(12B-3)1/n,(12B-4)1/n,(12B-5)1/n,(12B-6)1/n,(12B-7)1/n},
where n is fixed or configured from e.g., 2, or 2.5 (5/2), 3, or 3.5 (7/2) or 4 or 4.5 (9/2) or 5, and B is fixed or configured from {20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10}.In one example, b=3 and 8 values are 1−v, where v is one of the 8 values

In one example, b is configured via higher layer signaling, e.g., from {3,4}.

In one example, phase of each of the K values are reported using e bits.In one example, e=1. The 2 values correspond to BPSK [1, −1].In one example, e=2. The 4 values correspond to QPSK [1, j, −1, −j].In one example, e=3. The 8 values correspond to 8 PSK

{ej⁢2⁢π⁢k1⁢6:k=0,1,…,15}.In one example, e is configured via higher layer signaling, e.g., from {3, 4}.

In one embodiment, the reporting, as described in embodiments herein, can be configured based on (or linked to) X≥1 NZP CSI-RS resources (which can be included in a CSI-RS resource set). In one example, such NZP CSI-RS resources correspond to TRS (CSI-RS for tracking). When X>1, at least one of the following examples is used/configured for reporting.

In one example, one TDCP or DD components of the channel is reported per CSI-RS resource. So, there are X separate reports (one for each CSI-RS resource) or X components (one for each CSI-RS resource) in the (single) reported CSI report. In this case, the UE determine the multiple reports/components using the respective CSI-RS resource.

In one example, one (joint) TDCP or DD components of the channel is reported across all CSI-RS resources (regardless of the value of X). In this case, the UE can combine/aggregate all CSI-RS measurements across all resources, and then determine the report using the aggregated measurements.

In one example, a subset of Z CSI-RS resources can be selected, and the TDCP or DD components of the channel can be reported only using (for) the selected CSI-RS resources. The information (e.g., Z value or/and the indices of the selected resources) about the selection can be provided/reported by the UE, e.g., as part of the report. A two-part UCI is used when Z is reported by the UE. Or, the value of Z can be fixed, or configured, and the information (e.g., the indices of the selected resources) about the selection can be provided/reported by the UE, e.g., as part of the report. For the selected resources, the report can be separate (see examples herein) or one (joint) (see examples herein).

The information about the selection can be reported via an indicator. In one example, a new indicator (separate from existing indicators) is used. In one example, an existing indicator is used. For example, CRI (or PMI or PMI component) is used.In one example, one (single) joint indicator (new indicator, or CRI, or PMI, or PMI component) is used to indicate Z selected CSI-RS resource(s).In one example, multiple separate indicator(s) is/are used, i.e., one indicator (new indicator, or CRI, or PMI, or PMI component) is used to indicate each of the Z selected CSI-RS resource(s).

In one embodiment, for TDCP or Doppler component reporting (or a CSI reporting that includes TDCP or Doppler components), a UE is configured to receive a CSI reporting setting (e.g., via higher layer CSI-ReportConfig) that is linked to a CSI resource setting (e.g., via higher layer CSI-ResourceConfig), and includes the higher layer parameter reportQuantity set to other than ‘none’, where the CSI resource setting includes NZP CSI-RS resource set(s) for tracking. That is, the CSI-Resource setting contains (reference) ID(s) of S≥1 NZP CSI-RS resource set(s), and each NZP CSI-RS resource set is configured via higher layer NZP-CSI-RS-ResourceSet configured with higher layer parameter trs-Info. Each NZP-CSI-RS-ResourceSet includes:either four periodic NZP CSI-RS resources in two consecutive slots with two periodic NZP CSI-RS resources in each slot, ortwo periodic NZP CSI-RS resources in one slot.
Such a NZP CSI-RS resource is referred to as tracking RS (TRS) later in this disclosure.

Also, NZP-CSI-RS-ResourceSet(s) may have the CSI-RS resources configured as:Periodic, with the CSI-RS resources in the NZP-CSI-RS-ResourceSet configured with same periodicity, bandwidth and subcarrier location.Periodic CSI-RS resources in one set and aperiodic CSI-RS resources in a second set, with the aperiodic CSI-RS and periodic CSI-RS resources having the same bandwidth (with same RB location) and the aperiodic CSI-RS being configured with qcl-Type set to ‘typeA’ and ‘typeD’, where applicable, with the periodic CSI-RS resources.
Each CSI-RS resource is configured by the higher layer parameter NZP-CSI-RS-Resource with some restrictions. For example, each resource is a single port CSI-RS resource with density ρ=3.

The rest of the details about NZP CSI-RS resources for tracking (TRS) can be as described in Section 5.1.6.1.1 of REF 8.

When TRS is configured for CSI (or TDCP or Doppler component) reporting with reportQuantity set to other than ‘none’, a value of S can be according to at least one of the following examples.In one example, a value of S is fixed (e.g., to S=1) when TRS is configured for CSI reporting with reportQuantity set to other than ‘none’.In one example, a value of S can be 1 or more than 1 (e.g., S=2) based on the configuration. The value S>1 can be subject to UE capability reporting (i.e., only when the UE supports, it can be configured).

Also, when TRS is configured for CSI (or TDCP or Doppler component) reporting with reportQuantity set to other than ‘none’, there can be at least one restriction on such a TRS. A few examples of the restriction are as follows.In one example, TRS can only be a periodic NZP CSI-RS resource.In one example, the periodicity and slot offset for periodic NZP CSI-RS resources, as given by the higher layer parameter periodicityAndOffset configured by NZP-CSI-RS-Resource, is 2μXpslots, where Xpis fixed (e.g., 10) and where μ is defined in Clause 4.3 of (REF 10).

Note that when TRS is a periodic NZP CSI-RS resource, it can be used/configured to measure a CSI-RS burst for TDCP or Doppler component reporting. This can be achieved by associating a measurement window (comprising B>1 time slots) from the TRS measurement instances/occasions to the reporting. In one example, the measurement window is defined/configured based on a CSI reference resource (cf. 5.2.2.5, REF 8). In one example, the measurement window can be fixed, or configured, or reported by the UE. In one example, the measurement window can be identified based on a starting (first or reference) time slot (T0) and a number of time slots B (starting from the first time slot).In one example, both T0and B are fixed.In one example, both T0and B are configured.In one example, both T0and B are reported by the UE.In one example, T0is fixed and B is configured.In one example, T0is fixed and B is reported.In one example, T0is configured and B is fixed.In one example, T0is configured and B is reported.In one example, T0is reported and B is configured.In one example, T0is reported and B is fixed.
When configured, the measurement window is configured via RRC (e.g., as a parameter in CSI-ReportConfig). Or it is indicated via MAC CE or DCI. When reported, the measurement window is reported via CSI (e.g., as a CSI parameter).

When TRS is configured for CSI (or TDCP or Doppler component) reporting with reportQuantity set to other than ‘none’, the higher layer parameter timeRestrictionForChannelMeasurements in CSI-ReportConfig can be determined/configured according to at least one of the following examples.In one example, timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to ‘notConfigured’. The UE is expected to be configured with timeRestrictionForChannelMeasurements=‘notConfigured’. Or the UE is not expected to be configured with timeRestrictionForChannelMeasurements=‘configured’.In one example, timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to ‘configured’. The UE is expected to be configured with timeRestrictionForChannelMeasurements=‘configured’. Or the UE is not expected to be configured with timeRestrictionForChannelMeasurements=‘notConfigured’.

If the higher layer parameter timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to ‘notConfigured’, the UE shall derive the channel measurements for CSI (or TDCP or Doppler component) reporting in uplink slot n based on only the NZP CSI-RS, no later than the CSI reference resource, (defined in REF 10) associated with the CSI resource setting.

If the higher layer parameter timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to ‘configured’, the UE shall derive the channel measurements for CSI (or TDCP or Doppler component) reporting in uplink slot n based on only the most recent, no later than the CSI reference resource, occasion of NZP CSI-RS (defined in REF 10) associated with the CSI resource setting.

Depending on the value of the reportQuantity (for example, when CQI is included in the CSI reporting), at least one interference measurement resource (IMR) can also be configured via CSI-ReportConfig. The IMR can be a CSI-IM resource, or a NZP CSI-RS configured for interference measurement.

Examples of reportQuanity set to other than ‘none’ are provided herein.

The content of the CSI report (including TDCP or Doppler components reporting) configured via reportQuantity or reportQuantity-r18 set to other than ‘none’, as described above, is configured according to at least one of the following embodiments.

In one embodiment related to separate reporting, reportQuantity or reportQuantity-r18 set to other than ‘none’ corresponds to a separate report.

In one example, reportQuantity=‘new quantity’ or ‘TDCP’ or ‘DD’, where the new quantity is according to (corresponds to) at least one of the examples in the embodiments herein.

In one example, reportQuantity=an existing indicator ‘I’, which indicates one of the TDCP or Doppler components as described in examples herein.In one example, ‘I’=‘PMI’ or ‘PMI component’.In one example, ‘I’=‘CRI’.

The time-domain behavior for such reporting can be configured according to at least one of the following examples.In one example, the TD behavior is fixed to periodic (P).In one example, the TD behavior is fixed to semi-persistent on PUCCH (SPonPUCCH).In one example, the TD behavior is fixed to semi-persistent on PUSCH (SPonPUSCH).In one example, the TD behavior is fixed to aperiodic (AP).In one example, the TD behavior is configured from {P, SPonPUCCH}.In one example, the TD behavior is configured from {P, SPonPUSCH}.In one example, the TD behavior is configured from {P, AP}.In one example, the TD behavior is configured from {AP, SPonPUCCH}.In one example, the TD behavior is configured from {AP, SPonPUSCH}.In one example, the TD behavior is configured from {SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {P, SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {AP, SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {P, AP, SPonPUCCH}.In one example, the TD behavior is configured from {P, AP, SPonPUSCH}.In one example, the TD behavior is configured from {P, SPonPUCCH, SPonPUCCH, SP}.

When configured, the TD behavior of the CSI-ReportConfig is indicated by the higher layer parameter reportConfigType.

In one embodiment related to joint reporting, reportQuantity or reportQuannty-r18 set to other than ‘none’ corresponds to a joint report, wherein the joint report comprises (A) the TDCP or Doppler component of the channel and (B) the other CSI parameters from {CRI, LI, PMI, CQI, RI}.

At least one of the following examples is used/configured regarding the report Quantity.In one example, reportQuantity set to cri-RI-LI-PMI-CQI-X′, where cri-RI-LI-PMI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘RI-LI-PMI-CQI-X’, where RI-LI-PMI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘cri-RI-PMI-CQI-X’, where cri-RI-PMI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘RI-PMI-CQI-X’, where RI-PMI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘cri-RI-CQI-X’, where cri-RI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘RI-CQI-X’, where RI-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘cri-CQI-X’, where cri-CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘CQI-X’, where CQI corresponds to (B), and X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A).In one example, reportQuantity set to ‘cri-RI-LI-PMI-CQI’, where (A) is reported jointly (together with) one of indicators from {CRI, LI, RI, PMI, CQI} for (B).For example, PMI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the PMI components.In one example, reportQuantity set to ‘RI-LI-PMI-CQI’, where (A) is reported jointly (together with) one of indicators from {LI, RI, PMI, CQI} for (B).For example, PMI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the PMI components.In one example, reportQuantity set to ‘cri-RI-PMI-CQI’, where (A) is reported jointly (together with) one of indicators from {CRI, RI, PMI, CQI} for (B).For example, PMI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the PMI components.In one example, reportQuantity set to ‘RI-PMI-CQI’, where (A) is reported jointly (together with) one of indicators from {RI, PMI, CQI} for (B).For example, PMI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the PMI components.In one example, reportQuantity set to ‘cri-RI-CQI’, where (A) is reported jointly (together with) one of indicators from {CRI, RI, CQI} for (B).For example, RI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the RI component.In one example, reportQuantity set to ‘RI-CQI’, where (A) is reported jointly (together with) one of indicators from {RI, CQI} for (B).For example, RI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the RI component.In one example, reportQuantity set to ‘cri-CQI’, where (A) is reported jointly (together with) one of indicators from {CRI, CQI} for (B).For example, CQI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the CQI component.In one example, reportQuantity set to ‘CQI’, where (A) is reported jointly (together with) CQI for (B).For example, CQI={X, Y}, where X corresponds to ‘new quantity’ or ‘TDCP’ or ‘DD’ for (A), and Y corresponds to the CQI component.

The CQI reporting can help/assist NW implementations such as scaling for MU precoding. Also, the CQI reporting can provide accurate interference information to the NW.

At least one of the following examples is used/configured regarding the NZP CSI-RS resource(s) or/and resource set(s).

In one example, the NZP CSI-RS resource(s) are configured common for both (A) and (B). That is, the CSI-ResourceConfig includes CSI-RS resource set(s) that are used common for both (A) and (B). In one example, the number of resource sets is fixed to 1.

In one example, two types of resource sets linked to (configured within) a CSI reporting.SetType1: CSI-RS resource set(s) configured with trs-Info, i.e., sets comprising TRS(s).SetType2: CSI-RS resource set(s) configured without trs-Info, i.e., sets comprising NZP CSI-RS resources for normal CSI.
A set with SetTypel is configured for reporting of (A), and a set with SetType2 is configured for reporting of (B).

Let S1 be a number of sets with SetTypel, and S2 be a number of sets with SetType2.In one example, (S1, S2) is fixed, e.g., (1, 1) or (2, 1).In one example, (S1, S2)=(z, 1), and a value of z depends on the configuration. In one example, z can take a value from {1, 2}.In one example, (S1, S2) depends on the configuration.

Let R1 be a number of resources in each of the S1 sets with SetType1, and R2 be a number of resources in each of the S2 sets with SetType2.In one example, (R1, R2) is fixed, e.g., (4, 1) or (2, 1).In one example, (R1, R2)=(2,1) or (4, 1) based on a condition.In one example, the condition is based on the FR type. For instance, (R1, R2)=(2,1) for FR2, and (R1, R2)=(4,1) for FR1. Or. For instance, (R1, R2)=(2, 1) for FR2, and (R1, R2)=(2,1) or (4,1) for FR1.In one example, (R1, R2)=(2, b) or (4, b), where b>1. For example, b=2.In one example, (R1, R2)=(2, b) or (4, b), where b>=1. For example, b takes a value from {1, 2}.

In one example, a CSI-RS resource set in a CSI reporting is partitioned into two subsets/groups of resources.Group1: CSI-RS resource(s) configured with trs-Info, i.e., resources comprising TRS(s).Group2: CSI-RS resource(s) configured without trs-Info, i.e., resources comprising NZP

CSI-RS resources for normal CSI.

A resource in Group1 is configured for reporting of (A), and a resource Group2 is configured for reporting of (B).

The time-domain behavior for such reporting can be configured according to at least one of the following examples.In one example, the TD behavior is fixed to periodic (P).In one example, the TD behavior is fixed to semi-persistent on PUCCH (SPonPUCCH).In one example, the TD behavior is fixed to semi-persistent on PUSCH (SPonPUSCH).In one example, the TD behavior is fixed to aperiodic (AP).In one example, the TD behavior is configured from {P, SPonPUCCH}.In one example, the TD behavior is configured from {P, SPonPUSCH}.In one example, the TD behavior is configured from {P, AP}.In one example, the TD behavior is configured from {AP, SPonPUCCH}.In one example, the TD behavior is configured from {AP, SPonPUSCH}.In one example, the TD behavior is configured from {SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {P, SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {AP, SPonPUCCH, SPonPUCCH}.In one example, the TD behavior is configured from {P, AP, SPonPUCCH}.In one example, the TD behavior is configured from {P, AP, SPonPUSCH}.In one example, the TD behavior is configured from {P, SPonPUCCH, SPonPUCCH, SP}.

FIG.15illustrates an example1500of a UE moving on a trajectory located in a multiple RRHs/TRPs or distributed MIMO system according to embodiments of the present disclosure. The embodiment of the example1500of a UE moving on a trajectory located in a multiple RRHs/TRPs or distributed MIMO system illustrated inFIG.15is for illustration only.FIG.15does not limit the scope of this disclosure to any particular implementation of the example1500of a UE moving on a trajectory located in a multiple RRHs/TRPs or distributed MIMO system.

Aforementioned embodiments on the TDCP or Doppler component reporting can be extended to the case of multiple RRHs/TRPs or distributed MIMO system, as illustrated inFIG.15, wherein CSI-RS resource(s) are transmitted from multiple locations (RRHs/TRPs) within a cell. While the UE moves from a location A to another location B at high speed (e.g., 60 kmph), the UE measures the channel and the interference (e.g., via NZP CSI-RS resources and CSI-IM resources, respectively), uses them to determine/report CSI considering joint transmission from multiple RRHs. The reported CSI can be based on a codebook, which includes components considering both multiple RRHs, and time-/Doppler-domain channel compression. An RRH/TRP can be associated with (or correspond to) a NZP CSI-RS resource, or a group/subset of ports within a resource.

In one embodiment, a UE is configured to measure TRS resources transmitted from multiple (NRRH>1) TRPs/RRHs, and use them to report TDCP or Doppler components of the measured channels from multiple RRHs/TRPs.

In one example, the TRS or NZP CSI-RS resource(s) with trs-Info configured for such a reporting is according to at least one of the following examples.In one example, the number of NZP CSI-RS resources (M) in a CSI-RS resource set is NRRH, i.e., one resource for each TRP/RRH.In one example, the number of NZP CSI-RS resources (M) in a CSI-RS resource set is ≥NRRH, at least one for each TRP/RRH. The M resources can be partitioned into NRRHsubsets, each including at least one resource for an RRH.In one example, the number of NZP CSI-RS resource sets (S) configured via CSI-ResourceConfig is NRRH, one set for each TRP/RRH.In one example, the number of NZP CSI-RS resource sets (S) configured via CSI-ResourceConfig is ≥NRRH, at least one set for each TRP/RRH. The S resource sets can be partitioned into NRRHsubsets, each including at least one resource set for an RRH.

In one example, the TDCP or Doppler component reporting is according to at least one of the following examples.In one example, the TDCP or Doppler component reporting is separate for each of NRRHTRPs/RRHs. So, there are NRRHreports in total. The indicator for this reporting can be a joint indicator. Or a separate indicator is reported for each TRP. There can be only one CSI-ReportConfig configured for all reports with a reportQuantity that can set to a value other than ‘none’, details as described earlier. Or there can be multiple CSI-ReportConfigs (e.g., one for each report) for these reports. The TD behavior of these multiple reports are expected to be configured the same.In one example, the TDCP or Doppler component reporting is joint for all of NRRHTRPs/RRHs. So, there is only report that is joint for all TRPs.In one example, the TDCP or Doppler component reporting is only for one of the NRRHTRPs/RRHs. The index of the one TRP is fixed (e.g., 1), or configured (e.g., RRC, MAC CE, or DCI), or reported by the UE (e.g., as part of the CSI report).In one example, the TDCP or Doppler component reporting is a subset comprising Z out of the NRRHTRPs/RRHs. The value of Z or/and indices of the Z TRPs can be fixed (e.g., 1), or configured (e.g., RRC, MAC CE, or DCI), or reported by the UE (e.g., as part of the CSI report). The details can be according to embodiment 1.2. When Z>1, the reporting for the Z TRPs can be separate (cf. the first example above) or joint (cf. the second example above).

FIG.16illustrates an example method1600performed by a UE in a wireless communication system according to embodiments of the present disclosure. The method1600ofFIG.16can be performed by any of the UEs111-116ofFIG.1, such as the UE116ofFIG.3, and a corresponding method can be performed by any of the B Ss101-103ofFIG.1, such as BS102ofFIG.2. The method1600is for illustration only and other embodiments can be used without departing from the scope of the present disclosure.

The method1600begins with the UE receiving a configuration about a CSI report (1605). For example, in1605, the configuration including information about (i) M NZP CSI RS resources for tracking, where M≥1, (ii) K of time-domain correlation values, where K≥1, and (iii) delay values τkfor k=0, 1, . . . , K−1. In various embodiments, a unit of the delay values 11 is in terms of number of slots or number of OFDM symbols. In various embodiments, the K NZP CSI-RS resources are included in S≥1 CSI-RS resource sets for tracking. In various embodiments, a value of S belongs to a set of values including {1,2}, and a number of NZP CSI-RS resources in each of the CSI-RS resource sets belongs to a set of values including {1,2,4}.

The UE then measures the M NZP CSI-RS resources for tracking (1610). For example, in1610, the UE measures the M NZP CSI-RS resources based on the configuration. The UE then determines, based on the measurement, the K time-domain correlation values (1615). For example, in1615, the UE determines the K time-domain correlation values based on the configuration and based on the measurement. Here, a k-th correlation value is between two CSI-RS transmission occasions that are separated by one of the delay values τk. In various embodiments, a frequency granularity of the K time-domain correlation values is wideband and is based on the measurement in an entire reporting band configured for the CSI report. In various embodiments, the K time-domain correlation values are normalized by a correlation value associated with a delay value 0.

The UE then quantizes a value for an amplitude of each of the K time-domain correlation values, (1620). For example, in1620, the UE may quantize based on the configuration for the CSI report. In various embodiments, the amplitude values are quantized as 1−v, where v belongs to a codebook of amplitude values including

{18⁢2,18,14⁢2,14,12⁢2,12,12}.
In various embodiments, the UE may also quantize a value for a phase of each of the K time-domain correlation values using a codebook of phase values

{ej⁢2⁢π⁢k1⁢6:k=0,1,…,15}.
In this case, the CSI report further includes 4-bit indicators that indicate the quantized values of the phases of the K time-domain correlation values, respectively. The UE then transmits the CSI report including indicators indicating the quantized values of the amplitudes of the K time-domain correlation values.

Any of the above variation embodiments can be utilized independently or in combination with at least one other variation embodiment.