Patent ID: 12244384

DETAILED DESCRIPTION

FIG.1throughFIG.17, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device.

The following documents and standards descriptions are hereby incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TS 36.211 v17.0.0, “E-UTRA, Physical channels and modulation” (herein “REF 1”); 3GPP TS 36.212 v17.0.0, “E-UTRA, Multiplexing and Channel coding” (herein “REF 2”); 3GPP TS 36.213 v17.0.0, “E-UTRA, Physical Layer Procedures” (herein “REF 3”); 3GPP TS 36.321 v16.6.0, “E-UTRA, Medium Access Control (MAC) protocol specification” (herein “REF 4”); 3GPP TS 36.331 v16.7.0, “E-UTRA, Radio Resource Control (RRC) protocol specification” (herein “REF 5”); 3GPP TR 22.891 v1.2.0 (herein “REF 6”); 3GPP TS 38.212 v17.0.0, “E-UTRA, NR, Multiplexing and channel coding” (herein “REF 7”); 3GPP TS 38.214 v17.0.0, “E-UTRA, NR, Physical layer procedures for data” (herein “REF 8”); RP-192978, “Measurement results on Doppler spectrum for various UE mobility environments and related CSI enhancements,” Fraunhofer IIS, Fraunhofer HHI, Deutsche Telekom (herein “REF 9”); and 3GPP TS 38.211 v17.0.0, “E-UTRA, NR, Physical channels and modulation (herein “REF 10”).

Aspects, features, and advantages of the disclosure are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the disclosure. The disclosure is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. The disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as the duplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assume orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA), the present disclosure can be extended to other OFDM-based transmission waveforms or multiple access schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a “beyond 4G network” or a “post LTE system.”

The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates or in lower frequency bands, such as below 6 GHz, to enable robust coverage and mobility support. To decrease propagation loss of the radio waves and increase the transmission coverage, the beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques and the like are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul communication, moving network, cooperative communication, coordinated multi-points (CoMP) transmission and reception, interference mitigation and cancelation and the like.

The discussion of 5G systems and frequency bands associated therewith is for reference as certain embodiments of the present disclosure may be implemented in 5G systems. However, the present disclosure is not limited to 5G systems, or the frequency bands associated therewith, and embodiments of the present disclosure may be utilized in connection with any frequency band. For example, aspects of the present disclosure may also be applied to deployment of 5G communication systems, 6G or even later releases which may use terahertz (THz) bands.

FIGS.1-4Bbelow describe various embodiments implemented in wireless communications systems and with the use of orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques. The descriptions ofFIGS.1-3are not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably-arranged communications system. The present disclosure covers several components which can be used in conjunction or in combination with one another or can operate as standalone schemes.

FIG.1illustrates an example wireless network according to embodiments of the present disclosure. The embodiment of the wireless network shown inFIG.1is for illustration only. Other embodiments of the wireless network100could be used without departing from the scope of this disclosure.

As shown inFIG.1, the wireless network includes a gNB101, a gNB102, and a gNB103. The gNB101communicates with the gNB102and the gNB103. The gNB101also communicates with at least one network130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

The gNB102provides wireless broadband access to the network130for a first plurality of user equipments (UEs) within a coverage area120of the gNB102. The first plurality of UEs includes a UE111, which may be located in a small business; a UE112, which may be located in an enterprise (E); a UE113, which may be located in a WiFi hotspot (HS); a UE114, which may be located in a first residence (R); a UE115, which may be located in a second residence (R); and a UE116, which may be a mobile device (M), such as a cell phone, a wireless laptop, a wireless PDA, or the like. The gNB103provides wireless broadband access to the network130for a second plurality of UEs within a coverage area125of the gNB103. The second plurality of UEs includes the UE115and the UE116. In some embodiments, one or more of the gNBs101-103may communicate with each other and with the UEs111-116using 5G, LTE, LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can refer to any component (or collection of components) configured to provide wireless access to a network, such as transmit point (TP), transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point (AP), or other wirelessly enabled devices. Base stations may provide wireless access in accordance with one or more wireless communication protocols, e.g., 5G 3GPP new radio interface/access (NR), long term evolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA), Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS” and “TRP” are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, the term “user equipment” or “UE” can refer to any component such as “mobile station,” “subscriber station,” “remote terminal,” “wireless terminal,” “receive point,” or “user device.” For the sake of convenience, the terms “user equipment” and “UE” are used in this patent document to refer to remote wireless equipment that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile telephone or smartphone) or is normally considered a stationary device (such as a desktop computer or vending machine).

Dotted lines show the approximate extents of the coverage areas120and125, which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with gNBs, such as the coverage areas120and125, may have other shapes, including irregular shapes, depending upon the configuration of the gNBs and variations in the radio environment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs111-116include circuitry, programing, or a combination thereof, for receiving a configuration about a CSI report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length PCSIRS×1 for a SD, a second set of vectors each of length N3×1 for a FD, and a third set of vectors each of length N4×1 for a DD, and (ii) coefficients associated with each basis vector triple (ai, bf, cd), aifrom the first set, bffrom the second set, and cdfrom the third set; determining, based on the configuration, the components; and transmitting the CSI report including: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients, wherein N3and N4are total number of FD and DD units respectively, and wherein PCSIRSis a number of CSI-RS ports configured for the CSI report. One or more of the gNBs101-103includes circuitry, programing, or a combination thereof, for generating a configuration about a CSI report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length PCSIRS×1 for a SD, a second set of vectors each of length N3×1 for a FD, and a third set of vectors each of length N4×1 for a DD, and (ii) coefficients associated with each basis vector triple (ai, bf, cd), aifrom the first set, bffrom the second set, and cdfrom the third set; transmitting the configuration; and receiving the CSI report based on the configuration, wherein the CSI report includes: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients, wherein N3and N4are total number of FD and DD units respectively, and wherein PCSIRSis a number of CSI-RS ports configured for the CSI report.

AlthoughFIG.1illustrates one example of a wireless network, various changes may be made toFIG.1. For example, the wireless network could include any number of gNBs and any number of UEs in any suitable arrangement. Also, the gNB101could communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network130. Similarly, each gNB102-103could communicate directly with the network130and provide UEs with direct wireless broadband access to the network130. Further, the gNBs101,102, and/or103could provide access to other or additional external networks, such as external telephone networks or other types of data networks.

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, gNBs 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 RF transceivers210a-210n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry220. The gNB102also includes a controller/processor225, a memory230, and a backhaul or network interface235.

The RF transceivers210a-210nreceive, from the antennas205a-205n, incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers210a-210ndown-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to the RX processing circuitry220, which generates processed baseband signals by filtering, decoding, and/or digitizing the baseband or IF signals. The RX processing circuitry220transmits the processed baseband signals to the controller/processor225for further processing.

The TX processing circuitry215receives analog or digital data (such as voice data, web data, e-mail, or interactive video game data) from the controller/processor225. The TX processing circuitry215encodes, multiplexes, and/or digitizes the outgoing baseband data to generate processed baseband or IF signals. The RF transceivers210a-210nreceive the outgoing processed baseband or IF signals from the TX processing circuitry215and up-converts the baseband or IF signals to RF signals that are transmitted via the antennas205a-205n.

The controller/processor225can include one or more processors or other processing devices that control the overall operation of the gNB102. For example, the controller/processor225could control the reception of UL channel signals and the transmission of DL channel signals by the RF transceivers210a-210n, the RX processing circuitry220, and the TX processing circuitry215in accordance with well-known principles. The controller/processor225could support additional functions as well, such as more advanced wireless communication functions.

For instance, the controller/processor225could support beam forming or directional routing operations in which outgoing signals from multiple antennas205a-205nare weighted differently to effectively steer the outgoing signals in a desired direction. Any of a wide variety of other functions could be supported in the gNB102by the controller/processor225.

The controller/processor225is also capable of executing programs and other processes resident in the memory230, such as an OS. The controller/processor225can move data into or out of the memory230as required by an executing process.

The controller/processor225is also coupled to the backhaul or network interface235. The backhaul or network interface235allows the gNB102to communicate with other devices or systems over a backhaul connection or over a network. The interface235could support communications over any suitable wired or wireless connection(s). For example, when the gNB102is implemented as part of a cellular communication system (such as one supporting 5G, LTE, or LTE-A), the interface235could allow the gNB102to communicate with other gNBs over a wired or wireless backhaul connection. When the gNB102is implemented as an access point, the interface235could allow the gNB102to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The interface235includes any suitable structure supporting communications over a wired or wireless connection, such as an Ethernet or RF transceiver.

The memory230is coupled to the controller/processor225. Part of the memory230could include a RAM, and another part of the memory230could include a Flash memory or other ROM.

AlthoughFIG.2illustrates one example of gNB102, various changes may be made toFIG.2. For example, the gNB102could include any number of each component shown inFIG.2. As a particular example, an access point could include a number of interfaces235, and the controller/processor225could support routing functions to route data between different network addresses. As another particular example, while shown as including a single instance of TX processing circuitry215and a single instance of RX processing circuitry220, the gNB102could include multiple instances of each (such as one per RF transceiver). Also, various components inFIG.2could be combined, further subdivided, or omitted and additional components could be added according to particular needs.

FIG.3illustrates an example UE116according to embodiments of the present disclosure. The embodiment of the UE116illustrated inFIG.3is for illustration only, and the UEs111-115ofFIG.1could have the same or similar configuration. However, UEs come in a wide variety of configurations, andFIG.3does not limit the scope of this disclosure to any particular implementation of a UE.

As shown inFIG.3, the UE116includes an antenna305, a radio frequency (RF) transceiver310, TX processing circuitry315, a microphone320, and receive (RX) processing circuitry325. The UE116also includes a speaker330, a processor340, an input/output (I/O) interface (IF)345, a touchscreen350, a display355, and a memory360. The memory360includes an operating system (OS)361and one or more applications362.

The RF transceiver310receives, from the antenna305, an incoming RF signal transmitted by a gNB of the network100. The RF transceiver310down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to the RX processing circuitry325, which generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuitry325transmits the processed baseband signal to the speaker330(such as for voice data) or to the processor340for further processing (such as for web browsing data).

The TX processing circuitry315receives analog or digital voice data from the microphone320or other outgoing baseband data (such as web data, e-mail, or interactive video game data) from the processor340. The TX processing circuitry315encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver310receives the outgoing processed baseband or IF signal from the TX processing circuitry315and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna305.

The processor340can include one or more processors or other processing devices and execute the OS361stored in the memory360in order to control the overall operation of the UE116. For example, the processor340could control the reception of DL channel signals and the transmission of UL channel signals by the RF transceiver310, the RX processing circuitry325, and the TX processing circuitry315in accordance with well-known principles. In some embodiments, the processor340includes at least one microprocessor or microcontroller.

The processor340is also capable of executing other processes and programs resident in the memory360, such as processes for receiving a configuration about a CSI report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length PCSIRS×1 for a SD, a second set of vectors each of length N3×1 for a FD, and a third set of vectors each of length N4×1 for a DD, and (ii) coefficients associated with each basis vector triple (ai, bf, cd), aifrom the first set, bffrom the second set, and cdfrom the third set; determining, based on the configuration, the components; and transmitting the CSI report including: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients, wherein N3and N4are total number of FD and DD units respectively, and wherein PCSIRSis a number of CSI-RS ports configured for the CSI report. The processor340can move data into or out of the memory360as required by an executing process. In some embodiments, the processor340is configured to execute the applications362based on the OS361or in response to signals received from gNBs or an operator. The processor340is also coupled to the I/O interface345, which provides the UE116with the ability to connect to other devices, such as laptop computers and handheld computers. The I/O interface345is the communication path between these accessories and the processor340.

The processor340is also coupled to the touchscreen350and the display355. The operator of the UE116can use the touchscreen350to enter data into the UE116. The display355may be a liquid crystal display, light emitting diode display, or other display capable of rendering text and/or at least limited graphics, such as from web sites.

The memory360is coupled to the processor340. Part of the memory360could include a random-access memory (RAM), and another part of the memory360could include a Flash memory or other read-only memory (ROM).

AlthoughFIG.3illustrates one example of UE116, various changes may be made toFIG.3. For example, various components inFIG.3could be combined, further subdivided, or omitted and additional components could be added according to particular needs. As a particular example, the processor340could be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). Also, whileFIG.3illustrates the UE116configured as a mobile telephone or smartphone, UEs could be configured to operate as other types of mobile or stationary devices.

FIG.4Ais a high-level diagram of transmit path circuitry. For example, the transmit path circuitry may be used for an orthogonal frequency division multiple access (OFDMA) communication.FIG.4Bis a high-level diagram of receive path circuitry. For example, the receive path circuitry may be used for an orthogonal frequency division multiple access (OFDMA) communication. InFIGS.4A and4B, for downlink communication, the transmit path circuitry may be implemented in a base station (gNB)102or a relay station, and the receive path circuitry may be implemented in a user equipment (e.g., user equipment116ofFIG.1). In other examples, for uplink communication, the receive path circuitry450may be implemented in a base station (e.g., gNB102ofFIG.1) or a relay station, and the transmit path circuitry may be implemented in a user equipment (e.g., user equipment116ofFIG.1).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block410, Size N Inverse Fast Fourier Transform (IFFT) block415, parallel-to-serial (P-to-S) block420, add cyclic prefix block425, and up-converter (UC)430. Receive path circuitry450comprises down-converter (DC)455, remove cyclic prefix block460, serial-to-parallel (S-to-P) block465, Size N Fast Fourier Transform (FFT) block470, parallel-to-serial (P-to-S) block475, and channel decoding and demodulation block480.

At least some of the components inFIGS.4A400and4B450may be implemented in software, while other components may be implemented by configurable hardware or a mixture of software and configurable hardware. In particular, it is noted that the FFT blocks and the IFFT blocks described in this disclosure document may be implemented as configurable software algorithms, where the value of Size N may be modified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment that implements the Fast Fourier Transform and the Inverse Fast Fourier Transform, this is by way of illustration only and may not be construed to limit the scope of the disclosure. It may be appreciated that in an alternate embodiment of the present disclosure, the Fast Fourier Transform functions and the Inverse Fast Fourier Transform functions may easily be replaced by discrete Fourier transform (DFT) functions and inverse discrete Fourier transform (IDFT) functions, respectively. It may be appreciated that for DFT and IDFT functions, the value of the N variable may be any integer number (i.e., 1, 4, 3, 4, etc.), while for FFT and IFFT functions, the value of the N variable may be any integer number that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry400, channel coding and modulation block405receives a set of information bits, applies coding (e.g., LDPC coding) and modulates (e.g., quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) the input bits to produce a sequence of frequency-domain modulation symbols. Serial-to-parallel block410converts (i.e., de-multiplexes) the serial modulated symbols to parallel data to produce N parallel symbol streams where N is the IFFT/FFT size used in BS102and UE116. Size N IFFT block415then performs an IFFT operation on the N parallel symbol streams to produce time-domain output signals. Parallel-to-serial block420converts (i.e., multiplexes) the parallel time-domain output symbols from Size N IFFT block415to produce a serial time-domain signal. Add cyclic prefix block425then inserts a cyclic prefix to the time-domain signal. Finally, up-converter430modulates (i.e., up-converts) the output of add cyclic prefix block425to RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE116after passing through the wireless channel, and reverse operations to those at gNB102are performed. Down-converter455down-converts the received signal to baseband frequency and removes cyclic prefix block460and removes the cyclic prefix to produce the serial time-domain baseband signal. Serial-to-parallel block465converts the time-domain baseband signal to parallel time-domain signals. Size N FFT block470then performs an FFT algorithm to produce N parallel frequency-domain signals. Parallel-to-serial block475converts the parallel frequency-domain signals to a sequence of modulated data symbols. Channel decoding and demodulation block480demodulates and then decodes the modulated symbols to recover the original input data stream.

Each of gNBs101-103may implement a transmit path that is analogous to transmitting in the downlink to user equipment111-116and may implement a receive path that is analogous to receiving in the uplink from user equipment111-116. Similarly, each one of user equipment111-116may implement a transmit path corresponding to the architecture for transmitting in the uplink to gNBs101-103and may implement a receive path corresponding to the architecture for receiving in the downlink from gNBs101-103.

5G communication system use cases have been identified and described. Those use cases can be roughly categorized into three different groups. In one example, enhanced mobile broadband (eMBB) is determined to do with high bits/sec requirement, with less stringent latency and reliability requirements. In another example, ultra-reliable and low latency (URLL) is determined with less stringent bits/sec requirement. In yet another example, massive machine type communication (mMTC) is determined that a number of devices can be as many as 100,000 to 1 million per km2, but the reliability/throughput/latency requirement could be less stringent. This scenario may also involve power efficiency requirement as well, in that the battery consumption may be minimized as possible.

A communication system includes a downlink (DL) that conveys signals from transmission points such as base stations (BSs) 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 as an eNodeB.

In a communication system, such as LTE system, 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).

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 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 the DL signals convey a master information block (MIB) or to a DL shared channel (DL-SCH) when the DL signals convey a System Information Block (SIB). Most system information is included in different SIBs that are transmitted using DL-SCH. A presence of system information on a DL-SCH in a subframe can be indicated by a transmission of a corresponding PDCCH conveying a codeword with a cyclic redundancy check (CRC) scrambled with 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.

An UL subframe 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.5illustrates a transmitter block diagram500for a PDSCH in a subframe according to embodiments of the present disclosure. The embodiment of the transmitter block diagram500illustrated inFIG.5is for illustration only. One or more of the components illustrated inFIG.5can 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.5does not limit the scope of this disclosure to any particular implementation of the transmitter block diagram500.

As shown inFIG.5, information bits510are encoded by encoder520, such as a turbo encoder, and modulated by modulator530, for example using quadrature phase shift keying (QPSK) modulation. A serial to parallel (S/P) converter540generates M modulation symbols that are subsequently provided to a mapper550to be mapped to REs selected by a transmission BW selection unit555for an assigned PDSCH transmission BW, unit560applies an Inverse fast Fourier transform (IFFT), the output is then serialized by a parallel to serial (P/S) converter570to create a time domain signal, filtering is applied by filter580, and a signal transmitted590. 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.6illustrates a receiver block diagram600for a PDSCH in a subframe according to embodiments of the present disclosure. The embodiment of the 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 diagram600.

As shown inFIG.6, a received signal610is filtered by filter620, REs630for an assigned reception BW are selected by BW selector635, unit640applies a fast Fourier transform (FFT), and an output is serialized by a parallel-to-serial converter650. Subsequently, a demodulator660coherently demodulates data symbols by applying a channel estimate obtained from a DMRS or a CRS (not shown), and a decoder670, such as a turbo decoder, decodes the demodulated data to provide an estimate of the information data bits680. Additional functionalities such as time-windowing, cyclic prefix removal, de-scrambling, channel estimation, and de-interleaving are not shown for brevity.

FIG.7illustrates a transmitter block diagram700for a PUSCH in a subframe according to embodiments of the present disclosure. The embodiment of the block diagram700illustrated inFIG.7is for illustration only. One or more of the components illustrated inFIG.5can 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 block diagram700.

As shown inFIG.7, information data bits710are encoded by encoder720, such as a turbo encoder, and modulated by modulator730. A discrete Fourier transform (DFT) unit740applies a DFT on the modulated data bits, REs750corresponding to an assigned PUSCH transmission BW are selected by transmission BW selection unit755, unit760applies an IFFT and, after a cyclic prefix insertion (not shown), filtering is applied by filter770and a signal transmitted780.

FIG.8illustrates a receiver block diagram800for a PUSCH in a subframe 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.8can 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, a received signal810is filtered by filter820. Subsequently, after a cyclic prefix is removed (not shown), unit830applies a FFT, REs840corresponding to an assigned PUSCH reception BW are selected by a reception BW selector845, unit850applies an inverse DFT (IDFT), a demodulator860coherently demodulates data symbols by applying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide an estimate of the information data bits880.

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.9illustrates an example antenna blocks or arrays900according to embodiments of the present disclosure. The embodiment of the antenna blocks or arrays1100illustrated inFIG.9is for illustration only.FIG.9does not limit the scope of this disclosure to any particular implementation of the antenna blocks or arrays900.

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.9. 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 shifters901. One CSI-RS port can then correspond to one sub-array which produces a narrow analog beam through analog beamforming905. This analog beam can be configured to sweep across a wider range of angles (920) by 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 unit910performs 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 mechanisms corresponding to three types of CSI-RS measurement behavior are supported, for example, “CLASS A” CSI reporting which corresponds to non-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource which corresponds to UE-specific beamformed CSI-RS, and “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. 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 (e.g., comprising multiple ports). 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 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 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 the 3GPP LTE specification, MIMO has been identified as an essential feature in order to achieve high system throughput requirements and it will continue to be the same in NR. One of the key components of a MIMO transmission scheme is the accurate CSI acquisition at the eNB (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, the CSI can be acquired using the CSI-RS transmission from the eNB, and CSI acquisition and feedback from the UE. In legacy FDD systems, the CSI feedback framework is ‘implicit’ in the form of CQI/PMI/RI derived from a codebook assuming SU transmission from the eNB. Because of the inherent SU assumption while deriving CSI, this implicit CSI feedback is inadequate for MU transmission. Since future (e.g., NR) systems are likely to be more MU-centric, this SU-MU CSI mismatch will be a bottleneck in achieving high MU performance gains. Another issue with implicit feedback is the scalability with larger number of antenna ports at the eNB. For large number of antenna ports, the codebook design for implicit feedback is quite complicated, and the designed codebook is not guaranteed to bring justifiable performance benefits in practical deployment scenarios (for example, only a small percentage gain can be shown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTE is also supported and referred to as Type I CSI reporting. In addition to Type I, a high-resolution CSI reporting, referred to as Type II CSI reporting, is also supported to provide more accurate CSI information to gNB for use cases such as high-order MU-MIMO. 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 REF8). 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 REF8), 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 exists 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/or DFT-based FD basis in Wfcan 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 NR, such a codebook will be supported.

FIG.10illustrates channel measurement with and without Doppler components1000according to embodiments of the present disclosure. The embodiment of the channel measurement with and without Doppler components1000illustrated inFIG.10is for illustration only.FIG.10does not limit the scope of this disclosure to any particular implementation of the channel measurement with and without Doppler components1000.

Now, 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 Doppler components of the channel. As described in [REF9], 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 the 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. An illustration of channel measurement with and without Doppler components is shown inFIG.10. 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. This disclosure provides several example embodiments on obtaining the Doppler domain components or units that determine the length of the basis vectors that are used for the Doppler compression. The disclosure also describes example embodiments on signaling related to the CSI reporting format.

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 consist of 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 PRBs 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” 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.11illustrates an example antenna port layout1100according to embodiments of the present disclosure. The embodiment of the antenna port layout1100illustrated inFIG.11is for illustration only.FIG.11does not limit the scope of this disclosure to any particular implementation of the antenna port layout1100.

As illustrated inFIG.11, 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 2N1N2.

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.12illustrates a 3D grid1300of the oversampled DFT beams (1st port dim., 2nd port dim., freq. dim.) in which1st dimension is associated with the 1st port dimension,2nd dimension is associated with the 2nd port dimension, and3rd 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 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 REF8, 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, . . . , ν, where ν 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-1cl,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)
whereN1is 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 SBs 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 or

PCSIRS2×1
port selection column vector if antenna ports at the gNB are co-polarized, and is a 2N1N2×1 or PCSIRS×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, and PCSIRSis the number of CSI-RS ports configured for CSI reporting,bfis a N3×1 column vector,cl,i,fis a complex coefficient associate with vectors aiand bf.

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, wherexl,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=[∑f=0M-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 (ν=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.

Here

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

wf=[1ej⁢2⁢π⁢n3,l(f)O3⁢N3ej⁢2⁢π·2⁢n3,l(f)O3⁢N3…ej⁢2⁢π·(N3-1)⁢n3,l(f)O3⁢N3]T.

When O3=1, the FD basis vector for layer l∈{1, . . . , ν} (where ν is the RI or rank value) is given by

wf=[y0,l(f)y1,l(f)…yN3-1,l(f)]T,where⁢yt,l(f)=ej⁢2⁢π⁢t⁢n3,l(f)N3⁢andn3,l=[n3,l(0),…,n3,l(M-1)]where⁢n3,l(f)∈{0,1,…,N3-1}.

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

[Wf]n⁢m={1K,n=02K⁢cos⁢π⁡(2⁢m+1)⁢n2⁢K,n=1,…⁢K-1,and⁢K=N3,and⁢m=0,…,N3-1.

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 [REF8], and B=Wf.

The Cl={tilde over (W)}2matrix consists of 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 signaling. In another example, the amplitude coefficient (pl,i,f) is reported as pl,i,f=pl,i,f(1)pl,i,f(2)wherepl,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 l, 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.

The UE reports the following for the quantization of the NZ coefficients in {tilde over (W)}2A 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 reportedFor the other polarization, reference amplitude pl,i,f(1)is quantized to 4 bitsThe 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 bitsThe 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 8PSK (Nph=8) or 16PSK (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,i,f(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,i,f(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 ν0) can be different. In one example, for rank 1-4, (p, ν0) is jointly configured 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 Mνto show its dependence on the rank value ν, hence p is replaced with pν, ν∈{1, 2} and ν0is replaced with pν, ν∈{3, 4}.

A UE can be configured to report MνFD basis vectors in one-step from N3basis vectors freely (independently) for each layer l∈{0, 1, . . . , ν−1} of a rank ν CSI reporting. Alternatively, a UE can be configured to report MνFD basis vectors in two-step as follows.In step 1, an intermediate set (InS) comprising N3′<N3basis vectors is selected/reported, wherein the InS is common for all layers.In step 2, for each layer l∈{0, 1, . . . , ν−1} of a rank ν CSI reporting, M FD basis vectors are selected/reported freely (independently) from N3′ basis 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, N3′=┌αM┐ 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, pνfor ν∈{1, 2}, pνfor ν∈{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.(pνfor ν∈{1, 2}, pνfor ν∈{3, 4})∈{(½, ¼), (¼, ¼), (¼, ⅛)}.β∈{¼, ½, ¾}.α∈{1.5, 2, 2.5, 3}Nph∈{8, 16}.

In another example, the set of values for these codebook parameters are as follows: α=2, Nph=16, and as in Table 1, where the values of L, β and pνare determined by the higher layer parameter paramCombination-r17. In one example, the UE is not expected to be configured with paramCombination-r17 equal to3, 4, 5, 6, 7, or 8 when PCSI-RS=4,7 or 8 when number of CSI-RS ports PCSI-RS<32,7 or 8 when higher layer parameter typeII-RI-Restriction-r17 is configured with ri=1 for any i>1,7 or 8 when R=2.

The bitmap parameter typeII-RI-Restriction-r17 forms the bit sequence r3, r2, r1, r0where r0is the LSB and r3is the MSB. When riis zero, i∈{0, 1, . . . , 3}, PMI and RI reporting are not allowed to correspond to any precoder associated with ν=i+1 layers. The parameter R is configured with the higher-layer parameter numberOfPMISubbandsPerCQISubband-r17. This parameter controls the total number of precoding matrices N3indicated by the PMI as a function of the number of subbands in csi-ReportingBand, the subband size configured by the higher-level parameter subbandSize and of the total number of PRBs in the bandwidth part.

TABLE 1param-pvCombination-vvr17Lϵ {1,2}ϵ {3,4}β12¼⅛¼22¼⅛½34¼⅛¼44¼⅛½54¼¼¾64½¼½76¼—½86¼—¾

The above-mentioned framework (equation 5) represents the precoding-matrices for multiple (N3) FD units using a linear combination (double sum) over 2L SD beams and MνFD 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 MνTD 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,  (Equation 5A)

In one example, the MνTD 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.

The abovementioned framework for CSI reporting based on space-frequency compression (equation 5) or space-time compression (equation 5A) frameworks can be extended to Doppler domain (e.g., for moderate to high mobility UEs). This disclosure focuses on a CS-RS burst that can be used to obtain Doppler component(s) of the channel, which can be used to perform Doppler domain (DD) or time domain (TD) compression. In particular, the disclosure provides embodiments regarding the granularity or unit of the components across which the TD/DD compression is performed, where each component corresponds to one or multiple time instances within a CSI-RS burst or across multiple CSI-RS bursts.

This disclosure focuses on a reference signal burst that can be used to obtain Doppler component(s) of the channel, which can be used to perform Doppler domain compression.

FIG.13illustrates an example of a UE configured to receive a burst of non-zero power (NZP) CSI-RS resource(s)1300according to embodiments of the present disclosure. The embodiment of the UE configured to receive the burst of NZP CSI-RS resource(s)1300illustrated inFIG.13is for illustration only.FIG.13does not limit the scope of this disclosure to any particular implementation of the UE configured to receive a burst of NZP CSI-RS resource(s)1300.

In one embodiment, as shown inFIG.13, a UE is configured to receive a burst (or occasions) of non-zero power (NZP) CSI-RS resource(s), referred to as CSI-RS burst (or occasions) for brevity, in B time slots, 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 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 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) or TD 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 or TD basis vectors. Since the columns of HBare likely to be correlated, a DD or TD 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 or TD basis matrix Φ and the coefficient matrix C.

FIG.14illustrates an example of a UE configured to determine a value of N4based on the value B in a CSI-RS burst and a sub-time unit size NST1400according to embodiments of the present disclosure. The embodiment of the UE configured to determine a value of N4based on the value B in a CSI-RS burst and a sub-time unit size NST1400illustrated inFIG.14is for illustration only.FIG.14does not limit the scope of this disclosure to any particular implementation of the UE configured to determine a value of N4based on the value B in a CSI-RS burst and a sub-time unit size NST1400.

Let N4be the length of the basis vectors {ϕs}, e.g., each basis vector is a length N4×1 column vector.

In one embodiment, a UE is configured to determine a value of N4based on the value B (number of CSI-RS instances) in a CSI-RS burst and components across which the DD or TD compression is performed, where each component corresponds to one or multiple time instances within the CSI-RS burst. In one example, N4is fixed (e.g., N4=B) or configured (e.g., via RRC or MAC CE or DCI) or reported by the UE (as part of the CSI report). In one example, the B CSI-RS instances can be partitioned into sub-time (ST) units (instances), where each ST unit is defined as (up to) NSTcontiguous time instances in the CSI-RS burst. In this example, a component for the DD or TD compression corresponds to a ST unit. Three examples of the ST units are shown inFIG.14. In the first example, each ST unit comprises NST=1 time instance in the CSI-RS burst. In the second example, each ST unit comprises NST=2 contiguous time instances in the CSI-RS burst. In the third example, each ST unit comprises NST=4 contiguous time instances in the CSI-RS burst.

The value of NSTcan be fixed (e.g., NST=1 or 2 or 4) or indicated to the UE (e.g., via higher layer RRC or MAC CE or DCI based signaling) or reported by the UE (e.g., as part of the CSI report). The value of NST(fixed or indicated or reported) can be subject to a UE capability reporting. The value of NSTcan also be dependent on the value of B (e.g., one value for a range of values for B and another value for another range of values for B).

FIG.15illustrates an example of a UE configured to determine a value of a frequency-domain unit and a value of time/Doppler domain unit based on J≥1 CSI-RS bursts that occupy a frequency band and a time span1500according to embodiments of the present disclosure. The embodiment of the UE configured to determine a value of a frequency-domain unit and a value of time/Doppler domain unit based on J≥1 CSI-RS bursts that occupy a frequency band and a time span1500illustrated inFIG.15is for illustration only.FIG.15does not limit the scope of this disclosure to any particular implementation of the UE configured to determine a value of a frequency-domain unit and a value of time/Doppler domain unit based on J≥1 CSI-RS bursts that occupy a frequency band and a time span1500.

In one embodiment, a UE is configured with J≥1 CSI-RS bursts (as illustrated earlier in the disclosure) that occupy a frequency band and a time span (duration), wherein the frequency band comprises A RBs, and the time span comprises B time instances (of CSI-RS resource(s)) or C or B+C time instances, as described above. When J>1, the A RBs and/or Y time instances (where Y=B or C or B+C) can be aggregated across j CSI-RS bursts. In one example, the frequency band equals the CSI reporting band, and the time span equals the number of CSI-RS resource instances (across J CSI-RS bursts) or the time span/window during which the CSI report is expected to be valid, both can be configured to the UE for a CSI reporting, which can be based on the DD or TD compression.

The UE is further configured to partition (divide) the A RBs into subbands (SBs) and/or the Y time instances into sub-times (STs). The partition of A RBs can be based on a SB size value NSB, which can be configured to the UE (cf. Table 5.2.1.4-2 of REF8). The partition of Y time instances can be based either on an ST size value NSTor on an r value, as described in this disclosure. An example is illustrated inFIG.15for Y=B, where RB0, RB1, . . . , RBA-1comprise A RBs, T0, T1, . . . , TB−1comprise B time instances, the SB size NSB=4, and the ST size NST=2.

The CSI reporting is based on channel measurements (based on CSI-RS bursts) in three-dimensions (3D): the first dimension corresponds to SD comprising 2N1N2or PCSIRSCSI-RS antenna ports, the second dimension corresponds to FD comprising N3FD units (e.g., SB), and the third dimension corresponds to DD or TD comprising N4DD or TD units (e.g., ST). The 3D channel measurements can be compressed using basis vectors (or matrices) similar to the Rel. 16 enhanced Type II codebook. Let W1, Wf, and Wdrespectively denote basis matrices whose columns comprise basis vectors for SD, FD, and DD or TD.

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) three separate basis matrices W1, Wf, and Wdfor SD, FD, and DD or TD compression, respectively, and (B) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by
Wl=AlClBlH=W1{tilde over (W)}2Wf,dH
Here Wlis a PCSIRS×N3N4matrix whose columns are precoding vectors for N3N4pairs of (FD, DD/TD) units, W1is a PCSIRS×2L or PCSIRS×L SD basis matrix (similar to Rel. 16 enhanced Type II codebook), {tilde over (W)}2is a 2L×MνN coefficients matrix, and Wf,dis a N3N4×MνN basis matrix for (FD, DD/TD) pairs. The columns of Wf, comprises vectors νf,d,lthat are Kronecker products (KPs) of vectors gf,land hd,l, columns of Wfand Wd, respectively. Wfis a N3×MνFD basis matrix (similar to Rel. 16 enhanced Type II codebook) and Wdis a N4×N DD basis matrix.

In one example, νf,d,l[=gf,lϕ0,l(d)gf,lϕ1,l(d). . . gf,lϕN4−1,l(d)]T=[ϕ0,l(d)gf,lϕ1,l(d)gf,l. . . ϕN−4−1,l(d)gf,l]T, the KP of hd,land gf,l.

In one example νf,d,l=[hd,ly0,l(f)hd,ly1,l(f). . . hd,lyN3−1,l(f)]T=[y0,l(f)hd,ly1,l(f)hd,l. . . yN3−1,l(f)hd,l]T, the KP of gf,land hd,l.

Here, gf,l=[y0,l(f)y1,l(f). . . yN3−1,l(f)] and hd,l=[ϕ0,l(d)ϕ0,l(d). . . ϕN4−1,l(d)].

At least one of the following examples is used/configured regarding the reporting of the three bases.In one example, all three bases are reported by the UE, e.g., via a component or more than one component of the PMI.In one example, 2 out of 3 bases are reported, and the 3rdbasis is either fixed, or configured (e.g., via RRC, MAC CE, or DCI).In one example, the 2 reported bases correspond to SD and FD bases, and the 3rdbasis corresponds to the DD/TD basis.In one example, the 2 reported bases correspond to SD and DD/TD bases, and the 3rdbasis corresponds to the FD basis.In one example, the 2 reported bases correspond to FD and DD/TD bases, and the 3rdbasis corresponds to the SD basis.In one example, 1 out of 3 bases is reported, and one or both of the other two bases is either fixed, or configured (e.g., via RRC, MAC CE, or DCI).In one example, the 1 reported basis corresponds to the SD basis, and the other two bases correspond to the FD and DD/TD bases.In one example, the 1 reported basis corresponds to the FD basis, and the other two bases correspond to the SD and DD/TD bases.In one example, the 1 reported basis corresponds to the DD/TD basis, and the other two bases correspond to the SD and FD bases.

At least one of the following examples is used/configured regarding the three basis matrices.

In one, when W1is a PCSIRS×2L, the L SD basis vectors are determined the same way as in Rel. 15/16 Type II codebooks (cf. 5.2.2.2.3, REF 8), i.e., the SD basis vectors νm1(i)m2(i), i=0, 1, . . . , L−1, are identified by the indices q1, q2, n1, n2, can be indicated by PMI components i1, 1, i1, 2, and are obtained as in 5.2.2.2.3 of [REF 8].

The MνFD basis vectors, gf,l=[y0,l(f)y1,l(f). . . yN3−1,l(f)], f=0, 1, . . . , Mν−1, are identified by n3,l(l=1, . . . , ν) where
n3,l=[n3,l(0), . . . ,n3,l(Mν−1)]
n3,l(f)∈{0,1, . . . ,N3−1}

The vector yt,l=[yt,l(0)yt,l(0). . . yt,l(Mν−1)] comprises entries of FD basis vectors with FD index t={0, 1, . . . , N3−1}, which is an (FD) index associated with the precoding matrix.

The N DD/TD basis vectors, hd,l=[ϕ0,l(d)ϕ1,l(d). . . ϕN4−1,l(d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}
The vector ϕu,l=[ϕu,l(0)ϕu,l(1). . . ϕu,l(N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix.

In one example, the FD basis vectors are orthogonal DFT vectors, and

yt,l(f)=ej⁢2⁢π⁢t⁢n3,l(f)N3.
In one example, the DD/TD basis vectors are orthogonal DFT vectors, and

ϕu,l(d)=ej⁢2⁢π⁢u⁢n4,l(d)N4.
In one example, the FD basis vectors are oversampled (or rotated) orthogonal DFT vectors with the oversampling (rotation) factor O3, and

yt,l(f)=ej⁢2⁢π⁢t⁢n3,l(f)O3⁢N3,
and the MνFD basis vectors are also identified by the rotation index q3,l∈{0, 1, . . . , O3−1}. In one example, the DD/TD basis vectors are oversampled (or rotated) orthogonal DFT vectors with the oversampling (rotation) factor O4, and

ϕu,l(d)=ej⁢2⁢π⁢u⁢n4,l(d)O4⁢N4
and the N DD/TD basis vectors are also identified by the rotation index q4,l∈{0, 1, . . . , O4−1}. In one example, O3is fixed (e.g., 4), or configured (e.g., via RRC), or reported by the UE. In one example, O4is fixed (e.g., 4), or configured (e.g., via RRC), or reported by the UE. In one example, the rotation factor is layer-common (one value for all layers), i.e., q3,l=q3or q4,l=q4.

The precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vmi(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(d)⁢xl,i,f,d∑i=0L-1vmi(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(d)⁢xl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=02⁢l-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2. In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8). Then,

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vmi(i),m2(i)⁢pl,0(1)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(d)⁢pl,i,f,d(2)⁢φl,i,f,d∑i=0L-1vmi(i),m2(i)⁢pl,1(1)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(d)⁢pl,i+L,f,d(2)⁢φl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1⁢(pl,⌊iL⌋(1))2⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(d)⁢pl,i,f,d(2)⁢φl,i,f,d❘"\[RightBracketingBar]"2,
and the quantities φl,i,f,dand pl,1(1), pl,i,f,d(2), correspond to φl,i,fand pl,0(1), pl,1(1), pl,i,f(2)respectively, as described in 5.2.2.2.5 of [REF 8].

In a variation, when W1is a PCSIRS×L, and is not common for two antenna polarizations, the precoders for ν layers are then given b

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(d)⁢xl,i,f,d],l=1,…,υ,γt,u,l=∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
Where νm1(i)m2(i)is a PCSIRS×1 or 2N1N2×1 FD basis vector.

In one example, when W1is a PCSIRS×2L, the L SD basis vectors are determined as in example I.1.1. The MνN basis vectors νk,l=νf,d,l=[y0,l(k)y1,l(k). . . yN3N4−1,l(k)], k=0, 1, . . . , MνN−1, are determined based on the MνFD basis vectors, gf,l=[y0,l(f)y1,l(f). . . yN3−1,l(f)], f=0, 1, . . . , Mν−1, and DD/TD basis vectors, hd,l=[ϕ0,l(d)ϕ1,l(d). . . ϕN4−1,l(d)], d=0, 1, . . . , N−1. The index k determines (f, d) as explained in example I.1.1. The details of gf,land hd,lare as in example I.1.1.

The vector yt,u,l=[yt,u,l(0)yt,u,l(1). . . yt,u,l(MνN−1)] comprises entries of FD basis vectors with FD index t={0, 1, . . . , N3−1} and entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, and (t, u) is an (FD, DD/TD) index pair associated with the precoding matrix.

The precoders for ν layers are given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,u,l(k)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,u,l(k)⁢xl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,u,l(k)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.
In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
as in Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8). Then,

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢pl,0(1)⁢∑f=0Mυ-1∑d=0N-1yt,u,l(k)⁢pl,i,f,d(2)⁢φl,i,f,d∑i=0L-1vm1(i),m2(i)⁢pl,1(1)⁢∑f=0Mυ-1∑d=0N-1yt,u,l(k)⁢pl,i+L,f,d(2)⁢φl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1⁢(pl,⌊iL⌋(1))2⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,u,l(k)⁢pl,i,f,d(2)⁢φl,i,f,d❘"\[RightBracketingBar]"2.
and the quantities φl,i,f,dand pl,0(1), pl,1(1), pl,i,f,d(2)correspond to φl,i,fand pl,0(1), pl,1(1), pl,i,f(2)respectively, as described in in 5.2.2.2.5 of [REF 8].

In a variation, when W1is a PCSIRS×L, and is not common for two antenna polarizations, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,u,l(k)⁢xl,i,f,d],l=1,…,υ,γt,u,l=∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,u,l(k)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
Where νm1(i)m2(i)is a PCSIRS×1 or 2N1N2×1 FD basis vector.

In one example, the same as examples described above except that the SD basis is replaced with a port selection (PS) basis, i.e., the 2L antenna ports vectors are selected from the PCSIRSCSIRS ports. The rest of the details are the same as in the examples described above.

In one example, whether there is any selection in SD or not depends on the value of L. If

L=PCSI-RS2,
there is no need for any selection in SD (since all ports are selected), and when

L<PCSI-RS2,
the SD ports are selected (hence reported), where this selection is according to at least one example described above.

In one example, the SD basis is analogous to the W1component in Rel.15/16 Type II port selection codebook (cf. 5.2.2.2.3/5.2.2.2.5, REF 8), wherein the Llantenna ports or column vectors of Alare selected by the index

q1∈{0,1,…,⌈PCSI-RS2⁢d⌉-1}
(this require

⌈log2⁢⌈PCSI-RS2⁢d⌉⌉⁢bits),
where

d≤min⁡(PCSI-RS2⁢d,Ll).
In one example, d∈{1, 2, 3, 4}. To select columns of Al, the port selection vectors are used, For instance, ai=νm, where the quantity νmis a PCSI-RS/2-element column vector containing a value of 1 in element m mod PCSI-RS/2 and zeros elsewhere (where the first element is element 0). The port selection matrix is then given by

W1=Al=[X00X]⁢where⁢X=[vq1⁢d⁢vq1⁢d+1⁢…⁢vq1⁢d+Ll-1].

The SD basis is selected either common (the same) for the two antenna polarizations or independently for each of the two antenna polarizations.

In one example, the SD basis selects Llantenna ports freely, i.e., the Llantenna ports per polarization or column vectors of Alare selected freely by the index

q1∈{0,1,…,(PCSI-RS2Ll)-1}⁢(this⁢requires⁢⌈log2(PCSI-RS2Ll)⌉⁢bits).
To select columns of Al, the port selection vectors are used, For instance, ai=νm, where the quantity νmis a PCSI-RS/2-element column vector containing a value of 1 in element (m mod PCSI-RS/2) and zeros elsewhere (where the first element is element 0). Let {x0, x1, . . . , xLl−1} be indices of selection vectors selected by the index q1. The port selection matrix is then given by

W1=Al=[X00X]⁢where⁢X=[vx0⁢vx1⁢…⁢vxL1-1].

The SD basis is selected either common (the same) for the two antenna polarizations or independently for each of the two antenna polarizations.

In one example, the SD basis selects Llantenna ports freely from PCSI-RSports, i.e., the Llantenna ports or column vectors of Alare selected freely by the index

q1∈{0,1,…,(PCSI-RSLl)-1}
(this requires

⌈log2(PCSI-RSLl)⌉⁢bits).
To select columns of Al, the port selection vectors are used, For instance, ai=νm, where the quantity νmis a PCSI-RS-element column vector containing a value of 1 in element (m mod PCSI-RS) and zeros elsewhere (where the first element is element 0). Let {x0, x1, . . . , xLl−1} be indices of selection vectors selected by the index q1. The port selection matrix is then given by

W1=Ai=[X00X]⁢where⁢X=[vx0⁢vx1⁢…⁢vxLl-1].

In one example, the SD basis selects 2Llantenna ports freely from PCSI-RSports, i.e., the 2Llantenna ports or column vectors of Alare selected freely by the index

q1∈{0,1,…,(PCSI-RS2⁢Ll)-1}
(this requires

⌈log2(PCSI-RSLl)⌉⁢bits).
To select columns of Al, the port selection vectors are used, For instance, ai=νm, where the quantity νmis a PCSI-RS-element column vector containing a value of 1 in element (m mod PCSI-RS) and zeros elsewhere (where the first element is element 0). Let {x0, x1, . . . x2Ll−1} be indices of selection vectors selected by the index q1. The port selection matrix is then given by

W1=Al=[X00X]⁢where⁢X=[vx0⁢vx1⁢…⁢vx2⁢Ll-1].

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) two separate basis matrices W1, Wf, for SD, FD compression, (B) for each (SD, FD) basis vector pairs with indices (i, f), an independent/separate TD/DD basis matrix Wd(i,f)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In articular, the recoder for layer l is given by

Wl[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i,f,d(gf,l⊗hd,l(i,f))H∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i+L,f,d(gf,l⊗hd,l(i,f))H]
Where gf,l⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,land hd,l(i,f). Here, the set of TD/DD basis vectors {hd,l(i,f)} for each (SD, FD) basis vector pairs (νm1(i)m2(i), gf,l) is polarization-common, i.e., the same/common set of TD/DD basis vectors are determined/reported for the two antenna polarizations, a first polarization and second polarization. In one example, the first polarization comprises a first group CSI-RS antenna ports

{x,x+1,…⁢x+PCSIRS2-1},
and the second polarization comprises a second group CSI-RS antenna ports

{x+PCSIRS2,x+PCSIRS2+1,…⁢x+PCSIRS-1}
and x is the index of the first CSI-RS antenna port. So, the number of sets of TD/DD basis vectors is LMν(when the sets are the same for all layers) or LMνν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i,f)=[ϕ0,l(i,f,d)ϕ1,l(i,f,d). . . ϕN4−1,l(i,f,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i,f):i=0, . . . ,L−1,f=0, . . . ,Mν−1}
n4,l(i,f)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i,f)=[ϕu,l(i,f,0)ϕu,l(i,f,1). . . ϕu,l(i,f,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l⁢ϕu,l(i,f,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l⁢ϕu,l(i,f,d)⁢xl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,f,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2+∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,f,d)⁢xl,i+L,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMv,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) two separate basis matrices W1, Wf, for SD, FD compression, (B) for each (SD, FD) basis vector pairs with indices (i, f), an independent/separate TD/DD basis matrix Wd(i,f)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by

Wl=[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i,f,d(gf,l⊗hd,l(i,f))H∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i+L,f,d(gf,l⊗hd,l(i+L,f))H]
where gf,l⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,land hd,l(i,f). Here, the set of TD/DD basis vectors {hd,l(i,f)} for each (SD, FD) basis vector pairs (νm1(i)m2(i), gf,l) is polarization-specific or polarization-independent, i.e., the set of TD/DD basis vectors are determined/reported for each polarizations. So, the number of sets of TD/DD basis vectors is 2LM (when the sets are the same for all layers) or 2LMνν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i,f)=[ϕ0,l(i,f,d)ϕ1,l(i,f,d). . . ϕN4−1,l(i,f,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i,f):i=0, . . . ,2L−1,f=0, . . . ,Mν−1}
n4,l(i,f)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i,f)=[ϕu,l(i,f,0)ϕu,l(i,f,1). . . ϕu,l(i,f,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(i,f,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(i,f,d)⁢xl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,f,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) two separate basis matrices W1, Wf, for SD, FD compression, (B) for each SD basis vector with index i, an independent/separate TD/DD basis matrix Wd(i)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by

Wl[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i,f,d(gf,l⊗hd,l(i))H∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i+L,f,d(gf,l⊗hd,l(i))H]
Where gf,l⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,land hd,l(i). Here, the set of TD/DD basis vectors {hd,l(i)} for each SD basis vector νm1(i)m2(i)is polarization-common, i.e., the same/common set of TD/DD basis vectors are determined/reported for the two antenna polarizations, a first polarization and second polarization. In one example, the first polarization comprises a first group CSI-RS antenna ports

{x,x+1,…⁢x+PCSIRS2-1},
and the second polarization comprises a second group CSI-RS antenna ports

{x+PCSIRS2,x+PCSIRS2+1,…⁢x+PCSIRS-1}
and x is the index of the first CSI-RS antenna port. So, the number of sets of TD/DD basis vectors is L (when the sets are the same for all layers) or Lν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i)=[ϕ0,l(i,d)ϕ1,l(i,d). . . ϕN4−1,l(i,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i):i=0, . . . ,L−1}
n4,l(i)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i)=[ϕu,l(i,0)ϕu,l(i,1). . . ϕu,l(i,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1xt,l(f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(i,d)⁢xl,i,f,d],l=1,…,υ,γt,u,l=∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2+∑i=0L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,d)⁢xl,i+L,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) two separate basis matrices W1, Wf, for SD, FD compression, (B) for each SD basis vector with index i, an independent/separate TD/DD basis matrix Wd(i)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by

Wl=[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i,f,d(gf,l⊗hd,l(i))H∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1cl,i+L,f,d(gf,l⊗hd,l(i))H]
where gf,l⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,land hd,l(i). Here, the set of TD/DD basis vectors {hd,l(i)} for each SD basis vector νm1(i)m2(i)is polarization-specific or polarization-independent, i.e., the set of TD/DD basis vectors are determined/reported for each polarizations. So, the number of sets of TD/DD basis vectors is 2L (when the sets are the same for all layers) or 2Lν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i)=[ϕ0,l(i,d)ϕ1,l(i,d). . . ϕN4−1,l(i,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i):i=0, . . . ,L−1}
n4,l(i)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i)=[ϕu,l(i,0)ϕu,l(i,1). . . ϕu,l(i,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(f)⁢ϕu,l(i+L,d)⁢xl,i,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1⁢❘"\[LeftBracketingBar]"∑f=0Mυ-1⁢∑d=0N-1⁢yt,l(f)⁢ϕu,l(i,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) one SD basis matrix W1for SD compression, (B) for each SD basis vector with index i, an independent/separate Wffor FD compression and an independent/separate TD/DD basis matrix Wd(i)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by

Wl[∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1cl,i,f,d(gf,l(i)⊗hd,l(i))H∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1cl,i+L,f,d(gf,l(i)⊗hd,l(i))H]
Where gf,l(i)⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,l(i)and hd,l(i). Here, the set of FD basis vectors {gf,l(i)} and TD/DD basis vectors {hd,l(i)} for each SD basis vector νm1(i)m2(i)is polarization-common, i.e., the same/common set of FD basis vectors and TD/DD basis vectors are determined/reported for the two antenna polarizations, a first polarization and second polarization. In one example, the first polarization comprises a first group CSI-RS antenna ports

{x,x+1,…⁢x+PCSIRS2-1},
and the second polarization comprises a second group CSI-RS antenna ports

{x+PCSIRS2,x+PCSIRS2+1,…⁢x+PCSIRS-1}
and x is the index of the first CSI-RS antenna port. So, the number of sets of FD basis vectors is L (when the sets are the same for all layers) or Lν (when the sets can be different for ν layers). Likewise, the number of sets of TD/DD basis vectors is L (when the sets are the same for all layers) or Lν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i)=[ϕ0,l(i,d)ϕ1,l(i,d). . . ϕN4−1,l(i,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i):i=0, . . . ,L−1}
n4,l(i)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i)=[ϕu,l(i,0)ϕu,l(i,1). . . ϕu,l(i,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i+L,f,d],l=1,…,υ,γt,u,l=∑i=0L-1❘"\[LeftBracketingBar]"∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2+∑i=0L-1❘"\[LeftBracketingBar]"∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, which is an extension of an embodiment described above, wherein the UE is configured to report a CSI determined based on a codebook comprising components: (A) one SD basis matrix W1for SD compression, (B) for each SD basis vector with index i, an independent/separate Wffor FD compression and an independent/separate TD/DD basis matrix Wd(i)for DD or TD compression, and (C) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by

Wl[∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑N⁢‐⁢1d=0cl,i,f,d(gf,l(i)⊗hd,l(i))H∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1cl,i+L,f,d(gf,l(i+L)⊗hd,l(i+L))H]
Where gf,l(i)⊗hd,l(i)is Kronecker product (KP) of FD and TD/DD basis vectors gf,l(i)and hd,l(i). Here, the set of FD basis vectors {gf,l(i)} and TD/DD basis vectors {hd,l(i)} for each SD basis vector νm1(i)m2(i)is polarization-specific or polarization-independent, i.e., the set of TD/DD basis vectors are determined/reported for each polarizations. So, the number of sets of FD basis vectors is 2L (when the sets are the same for all layers) or 2Lν (when the sets can be different for ν layers). Likewise, the number of sets of TD/DD basis vectors is 2L (when the sets are the same for all layers) or 2Lν (when the sets can be different for ν layers).

The N DD/TD basis vectors, hd,l(i)=[ϕ0,l(i,d)ϕ1,l(i,d). . . ϕN4−1,l(i,d)], d=0, 1, . . . , N−1, are identified by n4,l(l=1, . . . , ν) where
n4,l={n4,l(i):i=0, . . . ,L−1}
n4,l(i)=[n4,l(0), . . . ,n4,l(N−1)]
n4,l(d)∈{0,1, . . . ,N4−1}

The vector ϕu,l(i)=[ϕu,l(i,0)ϕu,l(i,1). . . ϕu,l(i,N−1)] comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . . , N4−1}, which is an (DD/TD) index associated with the precoding matrix. The rest of the details can be the same as embodiment I.1. In particular, the precoders for ν layers are then given by

W…,t,ul=1N1⁢N2⁢γt,u,l[∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L⁢‐⁢1vm1(i),m2(i)⁢∑f=0Mυ⁢‐⁢1∑d=0N⁢‐⁢1yt,l(i+L,f)⁢ϕu,l(i+L,d)⁢xl,i,f,d],l=1,…,υ,γt,u,l=∑i=02⁢L-1❘"\[LeftBracketingBar]"∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d❘"\[RightBracketingBar]"2,
where xl,i,f,dis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, f, d), where i is a row index of {tilde over (W)}2and (f, d) determine the column index k of {tilde over (W)}2.

In one example, f=k mod Mνand

d=k-fMυ,
where k∈{0, 1, . . . , MνN} is a column index of {tilde over (W)}2. Here, k=Mνd+f.

In one example, d=k mod N and

f=k-dN.
Here, k=Nf+d.

In one example,

xl,i,f,d=pl,⌊iL⌋(1)⁢pl,i,f,d(2)⁢φl,i,f,d
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).

In one embodiment, the same as one or more embodiments described above except that the SD basis vectors νm1(i)m2(i)are replaced with port selection (PS) vectors νm(i), i.e., the 2L antenna ports vectors are selected from the PCSIRSCSIRS ports, e.g., as in Rel. 16 or 17 Type II port selection codebooks [cf. 5.2.2.2.6 and 5.2.2.2.7 of REF 8]. The rest of the details are the same as in embodiment I.1A through I.1D. The details of the port selection vectors are according to at least one of the examples described above.

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) two basis matrices, basis W1for SD, and a joint basis Wjointfor joint FD and DD/TD compression, and (B) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by
Wl=AlClBlH=W1{tilde over (W)}2WjointH
Here Wlis a PCSIRS×N3N4matrix whose columns are precoding vectors for a total of N3N4units, N3FD units and N4DD/TD units, W1is a PCSIRS×2L or PCSIRS×L SD basis matrix (similar to Rel. 16 enhanced Type II codebook), {tilde over (W)}2is a 2L×Mνcoefficients matrix, and Wjointis a N3N4×Mνbasis matrix comprising Mνjoint (FD, DD/TD) basis vectors. The k-th column of Wjointis a vector νk,lthat is a KP of two vectors gk,land hk,l, where (gk,l, hk,l) is the k-th joint (FD, DD/TD) basis vectors, and k=0, 1, . . . , Mν−1.

In one example, νk,l=[gk,lϕ0,l(k)gk,lϕ1,l(k). . . gk,lϕN4−1,l(k)]T, the KP of gk,land hk,l.

In one example νk,l=[hk,ly0,l(k)hk,ly0,l(k). . . hk,lyN3−1,l(k)]T, the KP of gk,land hk,l. Here, gk,l=[y0,l(k)y1,l(k). . . yN3−1,l(k)] and hk,l=[ϕ0,l(k)ϕ1,l(k). . . ϕN4−1,l(k)].

At least one of the following examples is used/configured regarding the reporting of the two bases.In one example, both bases are reported by the UE, e.g., via a component or more than one component of the PMI.In one example, one of the two bases is reported, and the other basis is either fixed, or configured (e.g., via RRC, MAC CE, or DCI).In one example, the reported basis corresponds to the SD basis, and the other basis corresponds to the joint (FD, DD/TD) basis.In one example, the reported basis corresponds to the joint (FD, DD/TD) basis, and the other basis corresponds to the SD basis.

At least one of the following examples is used/configured regarding the three basis matrices.

In one example, the SD basis W1is as described in one or more examples described above. The Mνjoint (FD, DD/TD) basis vectors νk,l=[y0,l(k)y1,l(k). . . yN3N4−1,l(k)], k=0, 1, . . . , Mν−1, are determined based on the Mν(FD, DD/TD) basis vector pairs, (gf,l(k), hd,l(k)), and are identified by njoint,l(l=1, . . . , ν) where
njoint,l=[njoint,l(0), . . . ,njoint,l(Mν−1)]
njoint,l(k)∈{0,1, . . . ,N3N4−1}

In one example, the Mνjoint (FD, DD/TD) vectors are reported jointly, similar to L basis reporting for W1(cf. Section 5.2.2.2.3, REF 8). For instance, the Mνvectors can be identified by the indices ijoint,1and ijoint,2, where
ijoint,1=[q3q4]
q3∈{0,1, . . . ,O3−1}
q4∈{0,1, . . . ,O4−1}

ijoint,2∈{0,1,…,(N3⁢N4Mυ)-1}
if all Mνvectors are selected, or,

ijoint,2∈{0,1,…,(N3⁢N4-1Mυ-1)-1}
if Mν−1 vectors are selected (e.g., njoint,l(k)∈{1, . . . , N3N4−1}) and one vector is fixed (e.g., njoint,l(k)=0).

Let njoint,l(k)corresponds (maps) to (n3,l(k), n4,l(k)).

n3,l=[n3,l(0),…,n3,l(Mυ-1)]n4,l=[n4,l(0),…,n4,l(Mυ-1)]n3,l(k)∈{0,1,…,N3-1}n4,l(k)∈{0,1,…,N4-1}andC⁡(x,y)={(xy)x≥y0x<y.
where the values of C(x, y) are given in Table 5.2.2.2.3-1 (REF 8).

Then the elements of n3,land n4,lare found from ijoint,2using the algorithm:

s−1= 0for k = 0, . . . , Mv− 1Find the largest x* ∈ {Mv− 1 − k, . . . , N3N4− 1 − k} in Table5.2.2.2.3-1 (REF 8) such that ijoint,2− sk−1≥ C(x*, Mv− k)ek= C(x*, Mv− k)sk= sk−1+ ekn(k)= N3N4− 1 − x*n3(k)= n(k)mod N3n4(k)=(n(k)-n3(k))N3

When n3,land n4,lare known, ijoint,2is found using:njoint,l(k)=N3n4(k)+n3(k)where the indices k=0, 1, . . . , Mν−1 are assigned such that njoint,l(k)increases as k increasesijoint,2=Σk=0Mν−1C(N3N4−1−njoint,l(k), Mν−k), where C(x, y) is given in Table 5.2.2.2.3-1 (REF 8).

The vector yt,l=[yt,l(0)yt,l(1). . . yt,l(Mν−1)] comprises entries of joint (FD, DD/TD) basis vectors with index t={0, 1, . . . , N3N4−1}, which is a joint (FD, DD/TD) index associated with the precoding matrix.

In one example, the joint (FD, DD/TD) basis vectors are orthogonal DFT vectors, and νt,l(k)=yt,l(k)ϕ2,l(k)where

yt1,l(k)=ej⁢2⁢π⁢t1⁢n3,l(k)N3⁢and⁢⁢ϕt2,l(k)=ej⁢2⁢π⁢t2⁢n4,l(k)N4,
(t1, t2) is determined based on t and vice versa as:In one example, t1=t mod N3and

t2=t-t1N3,where t∈{0, 1, . . . , N3N4}. Here, t=N3t2+t1.In one example, t2=t mod N4and

t1=t-t2N4.Here, t=N4t1+t2.

In one example, the joint (FD, DD/TD) basis vectors are oversampled (or rotated) orthogonal DFT vectors with the oversampling (rotation) factor O3and O4, and

yt1,l(k)=ej⁢2⁢π⁢t1⁢n3,l(k)O3⁢N3andϕt2,l(k)=ej⁢2⁢π⁢t2⁢n4,l(k)O4⁢N4,
and the Mνjoint (FD, DD/TD) basis vectors are also identified by the rotation indices q3,l∈{0, 1, . . . , O3−1} and q4,l∈{0, 1, . . . , O4−1}. In one example, O3is fixed (e.g., 4), or configured (e.g., via RRC), or reported by the UE. In one example, O4is fixed (e.g., 4), or configured (e.g., via RRC), or reported by the UE. In one example, the rotation factor is layer-common (one value for all layers), i.e., q3,l=q3or q4,l=q4.

The precoders for ν layers are then given by

W…,tl=1N1⁢N2⁢γt,l[∑i=0L-1vm1(i),m2(i)⁢∑k=0Mυ-1yt,l(f)⁢xl,i,k∑i=0L-1vm1(i),m2(i)⁢∑k=0Mυ-1yt,l(f)⁢xl,i+L,k],l=1,…,υ,γt,l=∑i=02⁢L-1⁢❘"\[LeftBracketingBar]"∑k=0Mυ-1⁢yt,l(k)⁢xl,i,k❘"\[RightBracketingBar]"2,
where xl,i,kis the coefficient (an element of {tilde over (W)}2) associated with codebook indices (l, i, k), where i is a row index of {tilde over (W)}2and k is the column index of {tilde over (W)}2.

In one example,

xl,i,k=pl,⌊1L⌋(1)⁢pl,i,k(2)⁢φl,i,k
similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8). Then,

W…,tl=1N1⁢N2⁢γt,l[∑i=0L-1vm1(i),m2(i)⁢pl,0(1)⁢∑k=0Mυ-1yt,l(k)⁢pl,i,k(2)⁢φl,i,k∑i=0L-1vm1(i),m2(i)⁢pl,1(1)⁢∑k=0Mυ-1yt,l(f)⁢pl,i+L,k(2)⁢φl,i+L,k],l=1,…,υ,γt,l=∑i=02⁢L-1⁢(pl,⌊iL⌋(1))2⁢❘"\[LeftBracketingBar]"∑k=0Mυ-1⁢yt,l(k)⁢pl,i,k(2)⁢φl,i,k❘"\[RightBracketingBar]"2,
and the quantities φl,i,kand pl,0(1), pl,1(1), pl,i,k(2)correspond to φl,i,fand pl,0(1), pl,1(1), pl,i,f(2), respectively, as described in 5.2.2.2.5 of [REF 8].

In a variation, when W1is a PCSIRS×L, and is not common for two antenna polarizations, the precoders for ν layers are then given by

W…,tl=1N1⁢N2⁢γt,l[∑i=0L-1vm1(i),m2(i)⁢∑k=0Mυ-1yt,l(k)⁢xl,i,k],l=1,…,υ,γt,l=∑i=0L-1⁢❘"\[LeftBracketingBar]"∑k=0Mυ-1⁢yt,l(k)⁢xl,i,k❘"\[RightBracketingBar]"2,
Where νm1(i)m2(i)is a PCSIRS×1 or 2N1N2×1 FD basis vector.

In one example, the same as one or more examples described above except that the SD basis is replaced with a port selection (PS) basis, i.e., the 2L antenna ports vectors are selected from the PCSIRSCSIRS ports. The rest of the details about the PS are the same as in one or more examples described above.

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) two basis matrices, basis W1for SD, and a joint basis Wjointfor joint FD and DD/TD compression, and (B) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by
Wl=AlClBlH=W1{tilde over (W)}2WjointH

Here Wlis a PCSIRS×N3N4matrix whose columns are precoding vectors for a total of N3N4units, N3FD units and N4DD/TD units, W1is a PCSIRS×2L or PCSIRS×L SD basis matrix (similar to Rel. 16 enhanced Type II codebook), {tilde over (W)}2is a 2L×Mνcoefficients matrix, and Wjointis a N3N4×Mνbasis matrix comprising Mνjoint (FD, DD/TD) basis vectors. The k-th column of Wjointis a vector νk,lwhose length is N3N4, and which is the k-th joint (FD, DD/TD) basis vectors, and k=0, 1, . . . , Mν−1.

In one example, νk,l=[m0,l, m1,l, . . . mN3N4,l]T.

In one example, νk,lis the k-th DFT vector on length N3N4, i.e.,

vk,l=[1,ej⁢2⁢π⁢k·1N3⁢N4,ej⁢2⁢π⁢k·2N3⁢N4,…,ej⁢2⁢π⁢k·(N3⁢N4-1)N3⁢N4]⁢and⁢mx,l=ej⁢2⁢π⁢k·xN3⁢N4.

In one example, νk,lis the k-th oversampled DFT vector on length N3N4, i.e.,

vk,l=[1,ej⁢2⁢π⁢k·1ON3⁢N4,ej⁢2⁢π⁢k·2ON3⁢N4,…,ej⁢2⁢π⁢k·(N3⁢N4-1)ON3⁢N4]⁢and⁢mx,l=ej⁢2⁢π⁢k·xN3⁢N4.
Here, O is the oversampling factor. In one example, O is fixed (e.g., 4). In one example, O is configured (e.g., via RRC).

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) two basis matrices, basis Wd,1or W1,dfor joint SD and DD/TD compression, and a basis Wffor FD compression, and (B) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by
Wl=AlClBlH=Wd,1{tilde over (W)}2WfHorW1,d{tilde over (W)}2WfH

Here Wlis a PCSIRSN4×N3matrix whose each column (f) comprises precoding vectors for N4DD/TD units and a given FD unit f, W1is a PCSIRS×2L or PCSIRS×L SD basis matrix (similar to Rel. 16 enhanced Type II codebook), Wfis a N3×MνFD basis matrix (similar to Rel. 16 enhanced Type II codebook) and Wdis a N4×N DD/TD basis matrix. The columns of Wd,1comprises vectors νd,1,lthat are Kronecker products (KPs) of vectors e1,land hd,l, columns of W1and Wd, respectively, i.e., Wd,1=kron(Wd, W1), is (PCSIRSN4)×(2LN). The columns of W1,dcomprises vectors ν1,d,lthat are Kronecker products (KPs) of vectors hd,land e1,l, columns of Wdand W1, respectively, i.e., W1,d=kron(W1, Wd), is (PCSIRSN4)×(2LN). The {tilde over (W)}2is (2LN)×(Mν) coefficient matrix.

For FD unit n3∈{1, . . . , N3} and DD/TD unit n4∈{1, . . . , N4}, the precoder for layer l is given byWl(I, n3) when Wl=Wd,1{tilde over (W)}2WfH, where I={(n4−1)*PCSIRS+i:i=1, . . . , PCSIRS} orWl(J, n3) when Wl=W1,d{tilde over (W)}2WfH, where J={n4+i×PCSIRS:i=1, . . . PCSIRS}.

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) two basis matrices, basis Wf,1or W1,ffor joint SD and FD compression, and a basis Wdfor DD/TD compression, and (B) coefficients {tilde over (W)}2. In particular, the precoder for layer l is given by
Wl=AlClBlH=Wf,1{tilde over (W)}2WdHorW1,f{tilde over (W)}2WdH

Here Wlis a PCSIRSN3×N4matrix whose each column (d) comprises precoding vectors for N3FD units and a given DD/TD unit d, W1is a PCSIRS×2L or PCSIRS×L SD basis matrix (similar to Rel. 16 enhanced Type II codebook), Wfis a N3×MνFD basis matrix (similar to Rel. 16 enhanced Type II codebook) and Wdis a N4×N DD/TD basis matrix. The columns of Wf,1comprises vectors νf,1,lthat are Kronecker products (KPs) of vectors e1,land gf,l, columns of W1and Wf, respectively, i.e., Wf,1=kron(Wf, W1), is (PCSIRSN3)×(2LMν). The columns of W1,fcomprises vectors ν1,f,l, that are Kronecker products (KPs) of vectors gf,land e1,l, columns of Wfand W1, respectively, i.e., W1,f=kron(W1, Wf), is (PCSIRSN3)×(2LMν). The {tilde over (W)}2is (2LMν)×(N) coefficient matrix.

For FD unit n3∈{1, . . . , N3} and DD/TD unit n4∈{1, . . . , N4}, the precoder for layer l is given byWl(I:, n4) when Wl=Wf,1{tilde over (W)}2WdH, where I={(n3−1)*PCSIRS+i:i=1, . . . , PCSIRS} orWl(J, n4) when Wl=W1,f{tilde over (W)}2WdH, where J={n3+i×PCSIRS: i=1, . . . , PCSIRS}.

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) three separate basis matrices W1, Wf, and Wdfor SD, FD, and DD/TD compression, respectively, and (B) coefficients {tilde over (W)}2. The details of the components are as explained in embodiment I.1 except that only 2 out of the 3 basis matrices are used for dimension reduction or compression, and the third basis is either fixed (e.g., 1 or identity matrix) or turned OFF (e.g., via explicit or implicit higher layer or MAC CE or DCI based signalling).

For all the components associated with the 3rddimension, the CSI (or PMI) reporting can correspond to only one value (similar to WB PMI reporting format) or multiple values (similar to SB PMI reporting format). In one example, this reporting is fixed (e.g., to one value) or configurable (e.g., via RRC) or reported by the UE (e.g., as part of UE capability or CSI reporting).

Also, the component W1can correspond to regular (e.g., DFT based similar to Rel. enhanced Type II codebook) or port selection (e.g., similar to Rel. 16 enhanced port selection Type II codebook).

In one example, the 2 bases used for dimension reduction or compression correspond to SD and FD bases, and the 3rdbasis corresponds to the DD/TD basis. The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2Wf,dH(with Wd) where Wdis fixed (e.g., to 1 or an identity matrix). Alternatively, Wl=W1{tilde over (W)}2WfH(without Wd).

In one example, the 2 bases used for dimension reduction or compression correspond to SD and DD/TD bases, and the 3rdbasis corresponds to the FD basis. The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2WdH(with Wf) where Wfis fixed (e.g., to 1 or an identity matrix). Alternatively, Wl=W1{tilde over (W)}2WdH(without Wf).

In one example, the 2 bases used for dimension reduction or compression correspond to FD and DD/TD bases, and the 3rdbasis corresponds to the SD basis. The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2Wf,dH(with W1) where W1is fixed (e.g., to 1 or an identity matrix). Alternatively, W1={tilde over (W)}2WfH(without W1).

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) two basis matrices, basis W1for SD, and a joint basis Wjointfor joint FD and DD/TD compression, and (B) coefficients {tilde over (W)}2. The details of the components are as explained above except that only Wjointis used for dimension reduction or compression, and the W1basis is either fixed (e.g., 1 or identity matrix) or turned OFF (e.g., via explicit or implicit higher layer or MAC CE or DCI based signalling).

The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2WjointH(with W1) where Wdis fixed (e.g., to 1 or an identity matrix). Alternatively, W1={tilde over (W)}2WjointH(without W1).

In one embodiment, the UE is configured to report a CSI determined based on a codebook comprising components: (A) three separate basis matrices W1, Wf, and Wdfor SD, FD, and DD/TD compression, respectively, and (B) coefficients {tilde over (W)}2. The details of the components are as explained in embodiment I.1 except that only 1 out of the 3 basis matrices is used for dimension reduction or compression, and one or both of the other two bases is either fixed (e.g., 1 or identity matrix) or turned OFF (e.g., via explicit or implicit higher layer or MAC CE or DCI based signalling).

For all the components associated with the other two dimensions, the CSI (or PMI) reporting can correspond to only one value (similar to WB PMI reporting format) or multiple values (similar to SB PMI reporting format). In one example, this reporting is fixed (e.g., to one value) or configurable (e.g., via RRC) or reported by the UE (e.g., as part of UE capability or CSI reporting).

Also, the component W1can correspond to regular (e.g., DFT based similar to Rel. enhanced Type II codebook) or port selection (e.g., similar to Rel. 16 enhanced port selection Type II codebook).

In one example, the one basis used for dimension reduction or compression corresponds to SD, and the other two bases correspond to the FD and DD/TD basis. The precoder for layer1is given by Wl=AlClBlH=W1{tilde over (W)}2Wf,dH(with Wfand Wd) where Wfand Wdare fixed (e.g., to 1 or an identity matrix). Alternatively, Wl=W1{tilde over (W)}2(without Wfand Wd).

In one example, the one basis used for dimension reduction or compression corresponds to FD, and the other two bases correspond to the SD and DD/TD basis. The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2Wf,dH(with W1and Wd) where W1and Wdare fixed (e.g., to 1 or an identity matrix). Alternatively, Wl={tilde over (W)}2WfH(without W1and Wd).

In one example, the one basis used for dimension reduction or compression corresponds to DD/TD, and the other two bases correspond to the SD and FD basis. The precoder for layer l is given by Wl=AlClBlH=W1{tilde over (W)}2Wf,dH(with W1and Wf) where W1and Wfare fixed (e.g., to 1 or an identity matrix). Alternatively, Wl={tilde over (W)}2WdH(without W1and Wd).

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

FIG.16illustrates a flow chart of a method1600for operating a UE, as may be performed by a UE such as UE116, according to embodiments of the present disclosure. The embodiment of the method1600illustrated inFIG.16is for illustration only.FIG.16does not limit the scope of this disclosure to any particular implementation.

As illustrated inFIG.16, the method1600begins at step1602. In step1602, the UE (e.g.,111-116as illustrated inFIG.1) receives a configuration about a CSI report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length PCSIRS×1 for a SD, a second set of vectors each of length N3×1 for a FD, and a third set of vectors each of length N4×1 for a DD, and (ii) coefficients associated with each basis vector triple (ai, bf, cd), aifrom the first set, bffrom the second set, and cdfrom the third set.

In step1604, the UE determines, based on the configuration, the components.

In step1606, the UE transmits the CSI report including: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients, wherein N3and N4are total number of FD and DD units respectively, and wherein PCSIRSis a number of CSI-RS ports configured for the CSI report.

In one embodiment, for each FD unit among the total of N3FD units and for each DD unit among the total of N4DD units, a precoding vector of length PCSIRS×1 for a layer l∈{1, . . . , ν} is based on: a first sum over the first set of SD basis vectors, a second sum over the second set of FD vectors, and a third sum over the third set DD vectors, where the precoding vector is given by:

Wl=1γ[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i+L,f,d],
wherein:L is a number of basis vectors in the first set,Mνis a number of basis vectors in the second set,N is a number of basis vectors in the third set,νm1(i)m2(i)is a vector of length

PCSIRS2×1⁢and[vmi(i),m2(i)vmi(i),m2(i)]is an i-th SD basis vector in the first set,yt,l(i,f)is a t-th element of an f-th FD basis vector of length N3×1 in the second set,ϕu,l(i,d)is a u-th element of a d-th DD basis vector of length N4×1 in the third set,γ is a normalization factor, andν is a number of layers.

In one embodiment, the first and the second sets of basis vectors for SD and FD respectively are independent, and the third set of basis vectors comprises a set of DD basis vectors {cd(i,f)} for each (SD, FD) basis vector pair (ai, bf).

In one embodiment, the first and the second sets of basis vectors for SD and FD respectively are independent, and the third set of basis vectors comprises a set of DD basis vectors {cd(i)} for each SD basis vector ai.

In one embodiment, the first set of basis vectors for SD is independent, the second set of basis vectors comprises a set of FD basis vectors {bf(i)} for each SD basis vector ai, and the third set of basis vectors comprises a set of DD basis vectors {cd(i)} for each SD basis vector ai.

In one embodiment, the first set of basis vectors for SD is independent, and the second and the third sets of basis vectors comprise sets {bf(i)} and {cd(i)} for each SD basis vector ai, where {bf(i)} and {cd(i)} are vectors from a joint set of FD and DD basis vector pairs {bf(i), cd(i))}.

In one embodiment, one of the sets of basis vectors is set to an identity matrix.

In one embodiment, the first set of SD basis vectors comprises either DFT vectors or port selection vectors, the second set of FD basis vectors comprises DFT vectors, and the third set of DD basis vectors comprises DFT vectors.

FIG.17illustrates a flow chart of another method1700, as may be performed by a base station (BS) such as BS102, according to embodiments of the present disclosure. The embodiment of the method1700illustrated inFIG.17is for illustration only.FIG.17does not limit the scope of this disclosure to any particular implementation.

As illustrated inFIG.17, the method1700begins at step1702. In step1702, the BS (e.g.,101-103as illustrated inFIG.1), generates a configuration about a channel state information (CSI) report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length PCSIRS×1 for a SD, a second set of vectors each of length N3×1 for a FD, and a third set of vectors each of length N4×1 for a DD, and (ii) coefficients associated with each basis vector triple (ai, bf, cd), aifrom the first set, bffrom the second set, and cdfrom the third set.

In step1704, the BS transmits the configuration.

In step1706, the BS receives the CSI report based on the configuration, wherein the CSI report includes: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients, wherein N3and N4are total number of FD and DD units respectively, and wherein PCSIRSis a number of CSI-RS ports configured for the CSI report.

In one embodiment, for each FD unit among the total of N3FD units and for each DD unit among the total of N4DD units, a precoding vector of length PCSIRS×1 for a layer l∈{1, . . . , ν} is based on: a first sum over the first set of SD basis vectors, a second sum over the second set of FD vectors, and a third sum over the third set DD vectors, where the precoding vector is given by:

Wl=1γ[∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i,f,d∑i=0L-1vm1(i),m2(i)⁢∑f=0Mυ-1∑d=0N-1yt,l(i,f)⁢ϕu,l(i,d)⁢xl,i+L,f,d],
wherein:L is a number of basis vectors in the first set,Mνis a number of basis vectors in the second set,N is a number of basis vectors in the third set,νm1(i)m2(i)is a vector of length

1⁢PCSIRS2×1⁢and[vmi(i),m2(i)vmi(i),m2(i)]is an i-th SD basis vector in the first set,yt,l(i,f)is a t-th element of an f-th FD basis vector of length N3×1 in the second set,ϕu,l(i,d)is a u-th element of a d-th DD basis vector of length N4×1 in the third set,γ is a normalization factor, andν is a number of layers.

In one embodiment, the first and the second sets of basis vectors for SD and FD respectively are independent, and the third set of basis vectors comprises a set of DD basis vectors {cd(i,f)} for each (SD, FD) basis vector pair (ai, bf).

In one embodiment, the first and the second sets of basis vectors for SD and FD respectively are independent, and the third set of basis vectors comprises a set of DD basis vectors {cd(i)} for each SD basis vector ai.

In one embodiment, the first set of basis vectors for SD is independent, the second set of basis vectors comprises a set of FD basis vectors {bf(i)} for each SD basis vector ai, and the third set of basis vectors comprises a set of DD basis vectors {cd(i)} for each SD basis vector ai.

In one embodiment, the first set of basis vectors for SD is independent, and the second and the third sets of basis vectors comprise sets {bf(i)} and {cd(i)} for each SD basis vector ai, where {bf(i)} and {cd(i)} are vectors from a joint set of FD and DD basis vector pairs {(bf(i), cd(i))}.

In one embodiment, one of the sets of basis vectors is set to an identity matrix.

In one embodiment, the first set of SD basis vectors comprises either DFT vectors or port selection vectors, the second set of FD basis vectors comprises DFT vectors, and the third set of DD basis vectors comprises DFT vectors.

The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure and various changes could be made to the methods illustrated in the flowcharts herein. For example, while shown as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps.

Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read as implying that any particular element, step, or function is an essential element that must be included in the claims scope. The scope of patented subject matter is defined by the claims.