CSI reporting for multiple CSI-RS resources in wireless communication system

Abstract

The present disclosure relates to a method and apparatus for CSI feedback reporting, a wireless device (500) and a network node (600). A method performed by a wireless device (500) comprises: receiving a CSI report configuration; determining a set of linear merge coefficients for a precoding matrix for the plurality of CSI-RS resources; determining a bitmap for indicating a plurality of non-zero merge coefficients; assigning an order to the bits of the bitmap and assigning the same order to a plurality of non-zero merge coefficients to be reported to a network node together with the bitmap in a CSI report; dividing the plurality of non-zero merge coefficients into two or more CSI groups having an associated priority level; generating a CSI report comprising an indication of the spatial domain component and the frequency domain component, the determined bitmap, and the non-zero merge coefficient, where the CSI report comprises a CSI portion 1 and a CSI portion 2, where the CS I portion 1 has a fixed payload size and comprises information indicating a payload size of the CSI portion 2, and where the CSI portion 2 has a fixed payload size. And wherein the CSI part 2 comprises the non-zero merge coefficients of at least one of two or more CSI groups; and transmitting or reporting uplink control information (UCI) comprising the CSI report to the network node (600) on an uplink, UL, channel.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and more particularly to a method and apparatus for reporting channel state information (CSI) feedback in an uplink control channel (UCI) for distributed multiple-input multiple-output (MIMO) cooperative transmission with codebook-based precoding in wireless communication networks such as advanced 5G networks. Background Art

[0002] Fifth-generation (5G) mobile communication systems, also known as New Radio (NR), offer higher levels of performance than previous generations of mobile communication systems. The driving force behind 5G mobile communications is to provide ubiquitous connectivity for data applications such as automotive communications, remote control with feedback, video downloads, and Internet of Things (IoT) devices and Machine Type Communication (MTC) devices. 5G wireless technology offers several key advantages, such as faster speeds, reduced latency, and enhanced connectivity. The Third Generation Partnership Project (3GPP) has provided complete system specifications for the 5G network architecture, which includes at least the Radio Access Network (RAN), the Core Transport Network (CN), and service functions.

[0003] Figure 1 This diagram illustrates a simplified example of a wireless communication network 100, which includes a core network (CN) 110 and a radio access network (RAN) 120. As shown, RAN 120 comprises multiple network nodes or radio base stations, referred to as gNBs in 5G. The diagram depicts three radio base stations, gNB1, gNB2, and gNB3. The area served by each gNB is called a coverage area or cell. Figure 1 Three cells are shown: cell 121, cell 122, and cell 123. Each cell is served by its corresponding gNB1, gNB2, and gNB3, respectively. It should be noted that network 100 can include any number of cells and gNBs. A wireless base station, or network node, provides services to users within a cell. In 4G or Long Term Evolution (LTE), a wireless base station is called an eNB; in 3G or Universal Mobile Telecommunications System (UMTS), it is called an eNodeB; and in other radio access technologies, it is called a base station (BS). A user or user equipment (UE) can be a wireless or mobile terminal device or a fixed communication device. A mobile terminal device or UE can also be an IoT device, a Mobile Telecommunications (MTC) device, or other device. IoT devices may include wireless sensors, software, actuators, and computing equipment. They can be embedded in mobile devices, vehicles, industrial equipment, environmental sensors, medical equipment, aircraft, and other devices, as well as network connections that enable these devices to collect and exchange data over existing network infrastructure.

[0004] Back to Figure 1, each cell is shown to contain UEs and IoT devices. gNB1 in cell 121 serves UE1 121A, UE2 121B, and IoT device 121C. Similarly, gNB2 in cell 122 serves UE3 122A, UE4 122B, and IoT device 122C, and gNB3 in cell 123 serves UE5 123A, UE6 123B, and IoT device 123C. The network 100 may include any number of UEs, IoT devices, or any other type of device. These devices communicate with their serving gNB via the uplink, and the gNB communicates with these devices via the downlink. Each base station gNB1 to gNB3 may communicate via its own backhaul links 111, 121D, 122D, 123D (in Figure 1 The gNBs are connected to the core network (CN 120, for example, via the S1 interface) (illustrated in the figure by arrows pointing to "Core"). Core network 120 can be connected to one or more external networks, such as the Internet. gNBs can be interconnected via the 5G S1, X2, or XN interfaces (corresponding to their respective interface links 121E, 122E, and 123E, as indicated by arrows pointing to the gNBs in the figure).

[0005] For data transmission, a physical resource grid (PRG) can be used. The PRG can contain a set of resource elements (REs) onto which various physical channels and physical signals are mapped. For example, physical channels can include physical downlink, uplink, and / or sidelink (SL) shared channels (PDSCH, PUSCH, PSSCH), which are used to transmit specific user data, also known as downlink, uplink, or sidelink payload data; physical broadcast channels (PBCH), which carry content such as the master information block (MIB) and system information block (SIB); and physical downlink, uplink, and / or sidelink control channels (PDCCH, PUCCH, PSCCH), which carry content such as downlink control information (DCI), uplink control information (UCI), or sidelink control information (SCI). In the uplink, physical channels can also include a physical random access channel (PRACH or RACH), which can be used to access the network after the UE completes synchronization and obtains the MIB and SIB. Physical signals can include reference signals (RS), synchronization signals (SS), etc. A resource grid may contain a frame or radio frame with a specific duration (e.g., 10 milliseconds) in the time domain and a given bandwidth in the frequency domain. The radio frame may have a certain number of subframes of predefined length, for example, two subframes of 1 millisecond in length. Each subframe may contain two time slots, and the number of orthogonal frequency division multiplexing (OFDM) symbols in a time slot depends on the length of the cyclic prefix (CP). In 5G, each time slot consists of 14 OFDM symbols or 12 OFDM symbols based on normal CP and extended CP, respectively. A frame may also contain a smaller number of OFDM symbols, for example, when a shortened transmission time interval (TTI) or a microslot / non-slotted frame structure containing only a few OFDM symbols is adopted. 5G New Radio (NR) supports time slot aggregation, so data transmission can be scheduled between one or more time slots. The slot format indication informs the UE whether an OFDM symbol is of downlink, uplink, or flexible type.

[0006] The wireless communication network system can be a single-tone or multi-carrier system using frequency division multiplexing, such as an orthogonal frequency division multiplexing (OFDM) system, an orthogonal frequency division multiple access (OFDMA) system, or any other IFFT-based signal with or without CP, such as DFT-OFDM. Other waveforms, such as non-orthogonal waveforms for multiple access, such as filter bank multi-carrier (FBMC), generalized frequency division multiplexing (GFDM), or universal filtered multi-carrier (UFMC), can also be used. The wireless communication system can operate, for example, in accordance with the LTE-Advanced pro standard or the 5G or NR (New Radio) standard.

[0007] Figure 1The wireless communication network system shown can be a heterogeneous network consisting of two different overlapping networks, one of which is a macro cellular network consisting of a macro base station network (such as base stations gNB1 to gNB3), and the other is a small cell base station network ( Figure 1 In addition to the above-mentioned terrestrial wireless networks, there are also non-terrestrial wireless communication networks, including spaceborne transceivers (such as satellites) and / or airborne transceivers (such as drone systems). The operation of the non-terrestrial wireless communication network or system can be similar to that described above. Figure 1 The terrestrial systems described are similar, for example according to the LTE-Advanced pro standard or the 5G or NR standard.

[0008] In such Figure 1 In the schematically depicted wireless communication network system, multi-antenna technology (e.g., as used in LTE, NR, or other communication systems) can be used to improve user data rates, link reliability, cellular coverage, and network capacity. To support multi-stream or multi-layer transmission, the physical layer of the communication system uses linear precoding. Linear precoding is implemented using a precoding matrix that maps data layers to antenna ports. Precoding can be considered an extension of beamforming, a technique that focuses data transmission to the intended receiver through spatial orientation. The precoding matrix used by the gNB to map data to the transmit antenna ports is determined based on channel state information (CSI).

[0009] In wireless communication network systems such as LTE or new wireless (5G), downlink signals carry data signals, control signals including downlink (DL) control information (DCI), and multiple reference signals / symbols (RS) for various purposes. The gNodeB (gNB) or base station transmits data and downlink control information (DCI) via the physical downlink shared channel (PDSCH) and physical downlink control channel (PDCCH) or enhanced PDCCH (ePDCCH), respectively. Furthermore, the gNB's downlink signals may include one or more types of reference signals (RS), including the common RS (CRS) in LTE, channel state information RS (CSI-RS), demodulation RS (DM-RS), and phase tracking RS (PT-RS). CRS are transmitted across the DL system bandwidth and are used by user equipment (UE) to obtain channel estimates for demodulating data or control information. Compared to CRS, CSI-RS are transmitted at a lower density in the time and frequency domains and are used by UEs for channel estimation or obtaining channel state information (CSI). DM-RS is transmitted only on the corresponding PDSCH bandwidth portion for UE data demodulation. For signal precoding at the gNB, multiple CSI-RS reporting mechanisms are used, such as non-precoded CSI-RS and beamformed CSI-RS reporting. For non-precoded CSI-RS, a one-to-one mapping is used between the CSI-RS ports of the antenna array at the gNB and the transceiver unit (TXRU). Therefore, non-precoded CSI-RS provides cell-wide coverage, where different CSI-RS ports have the same beam direction and beamwidth. For beamformed / precoded UE-specific or non-UE-specific CSI-RS, beamforming is applied to a single antenna port or multiple antenna ports to generate multiple narrow beams with high gain in different directions, achieving directional coverage.

[0010] In wireless communication networks using time division duplex (TDD), CSI can be obtained at the gNB due to channel reciprocity. However, in frequency division duplex (FDD), channel reciprocity is lacking, requiring the UE to perform channel estimation and feed the estimation results back to the gNB. Figure 2 The modular model of multiple-input multiple-output (MIMO) downlink transmission with LTE Release 8 codebook precoding is shown. Figure 2 The schematic diagram shows a base station 200 (gNB), a user equipment (UE) 202, and a channel 204, such as the wireless data communication between the base station 200 and the user equipment 202 via the wireless channel. The base station includes an antenna array ANT having multiple antennas or antenna elements. T, and a precoder 206 that receives a data vector 208 and a precoding matrix F from a codebook 210. The channel 204 can be described by a channel tensor / matrix 212. The user equipment 202 is connected to an antenna or antenna array ANT having multiple antennas or antenna elements. R Receive data vector 214. A feedback channel 216 is provided between user equipment 202 and base station 200 for transmitting feedback information. 3GPP Release 15 and earlier versions support UE to use multiple downlink reference symbols (such as CSI-RS) for CSI estimation.

[0011] In FDD systems (up to Rel. 15), the channel estimated at the UE is implicitly reported to the gNB, where the CSI report transmitted by the UE over the feedback channel includes the rank index (RI), precoding matrix index (PMI) and channel quality indicator (CQI) (and CRI starting from Release 13), so that the precoding matrix, as well as the modulation order and coding scheme (MCS) of the symbols to be transmitted, can be determined at the gNB. The PMI and RI are used to determine the precoding matrix from a set of predefined matrices Ω (also called a codebook). For example, according to LTE, the codebook can be a lookup table with each entry having a matrix, and the UE's PMI and RI determine which row and column of the table to get the precoding matrix to use. Up to Release 15, the precoder and codebook are designed for a UE equipped with N1 dual-polarized antennas (for a total of N t = 2N1 antennas) or a one-dimensional uniform linear array (ULA) at N1N2 locations (a total of N t =2N1N2 antennas) with a two-dimensional uniform planar array (UPA) of dual-polarized antennas. ULA allows steering of radio waves only in the horizontal (azimuth) direction, enabling azimuth-only beamforming at the gNB, while UPA supports transmit beamforming in both the vertical (elevation) and horizontal (azimuth) directions, also known as full-dimensional (FD) MIMO. For example, in the case of massive antenna arrays (such as FD-MIMO), the codebook can be a set of beamforming weights that form spatially separated electromagnetic transmit / receive beams using the array response vectors of the array. The array's beamforming weights (also known as array steering vectors) are the amplitude gain and phase adjustments applied to the signal fed to (or received from) the antenna to transmit (or extract) radiation in a specific direction. The components of the precoding matrix are obtained from the codebook, and the PMI and RI are used to read the codebook and obtain the precoder. When using ULA or UPA for signal transmission, the array steering vectors can be described by column vectors of a two-dimensional discrete Fourier transform (DFT) matrix.

[0012] The precoding matrix used in the Type-I, Type-I multi-panel, and Type-II CSI reporting schemes in 3GPP New Wireless Release 15 is defined in the frequency domain and has a two-level structure (i.e., two component codebooks): F(s) = F1F2(s), s = 0…, S-1, where S represents the number of subbands. The first component, or so-called first-level precoder F1, is used to select multiple beam vectors from a matrix based on the discrete Fourier transform (DFT), also known as a spatial codebook. In addition, the first-level precoder F1 corresponds to a wideband matrix that is independent of the subband index s and contains L spatial beamforming vectors (i.e., the so-called spatial beams). These vectors are selected from the DFT-based codebook matrices for the two polarizations of the antenna array, For the Type-I codebook, L=1, so F1 is simply given by: The spatial codebook consists of an oversampled DFT matrix of dimension N1N2×N1O1N2O2, where O1 and O2 represent the oversampling factors relative to the first and second dimensions of the codebook, respectively. The DFT vectors in the codebook are grouped into subsets (q1, q2), (0≤q1≤O1-1,0≤q2≤O2-1), where each subset contains N1N2 DFT-based vectors, and the parameters q1 and q2 represent the rotation oversampling factors relative to the first and second dimensions of the antenna array, respectively.

[0013] The second component, or so-called second-stage precoder F2(s), is used to combine the selected beam vectors. This means that the second-stage precoder F2(s) corresponds to a selection / combination / co-phasing matrix that is used to select / combine / co-phase the beams defined in F1 for the s-th configured subband. For example, for rank 1 transmission and Type-I CSI reporting, for a dual-polarized antenna array, F2(s) is given by: is the quantized in-phase factor (phase adjustment) between the two orthogonal polarizations of the antenna array. Therefore, for the Type-I codebook, a single DFT beam is selected in each transmission layer of the precoding so that the transmission is directed to the strongest path component of the wireless channel.

[0014] For rank-1 transmission and Type-IICSI reporting, for a dual-polarized antenna array, F2(s) is given by: where p l and are the quantized amplitude and phase beam combining coefficients, respectively. For a rank R transmission, F2(s) contains R vectors, where R represents the transmission rank, and the entries of each vector are selected to combine single or multiple beams within each polarization.

[0015] The selection of matrices F1 and F2(s) is performed by the UE based on knowledge of reference signals (such as CSI-RS) and channel conditions. The selected matrices are indicated in the CSI report in the form of RI (where RI represents the rank of the precoding matrix) and PMI, and are used at the gNB to update the multi-user precoder for the next transmission time interval.

[0016] In addition to the Type-I codebook, the 3GPP Release 15 specification also defines a Type-I multi-panel (multi-antenna array) codebook for the case where the gNB is equipped with multiple (co-located) antenna panels or antenna arrays (which may not be calibrated). The precoder of this codebook is similar to the Type-I codebook, applying a single DFT beam in each transmission layer of the precoding matrix. To account for different spacings between antenna panels and / or possible phase calibration errors between antenna panels (for example, due to different local oscillators), a panel-specific co-phasing factor is applied to each panel. For example, for a rank 1 transmission and a gNB equipped with N g = For a gNB with 2 antenna panels, the Type-I multi-panel CSI report is defined as:

[0017]

[0018] in and is the quantized in-phase factor, is the panel-specific in-phase factor applied to the second panel.

[0019] The current 3GPP NR Type-I and Type-II codebook designs are suitable for deployments where the gNB is equipped with a single panel or antenna array or multiple co-located panels or antenna arrays. However, the current 3GPP specifications do not support CSI reporting for so-called "distributed MIMO coordinated transmission," where multiple panels or antenna arrays connected to the gNB operate as a large distributed multi-panel or multi-antenna array. Therefore, a new codebook and CSI reporting scheme suitable for distributed MIMO deployments is needed. The present invention, according to this disclosure, proposes extensions to the NR Type-II codebook and CSI reporting for distributed MIMO coordinated transmission.

[0020] UCI omission mechanism in CSI reporting

[0021] In 3GPP Release 15, a UCI or CSI omission mechanism was introduced for PUSCH-based resource allocation and CSI reporting. This mechanism allows a wireless device or UE to drop parts of one or more CSI reports when the PUSCH resource allocation is insufficient to carry the entire content of the CSI report. UCI omission can occur when the base station (gNB) does not accurately allocate PUSCH resources when scheduling CSI reports. For example, the base station may allocate resources for a rank 1 (RI=1) CSI report, but the UE actually determines a rank 2 transmission and reports a rank 2 (RI=2) CSI report, the size of which is larger than the allocated PUSCH resource size. If the allocated PUSCH resources are insufficient to carry the complete CSI report, the UE must drop part of the UCI content. In 3GPP Releases 15 and 16, omission is achieved by decomposing the UCI payload associated with the CSI report into smaller parts, so-called priority levels, where priority 0 has the highest priority and represents the total number of CSI reports configured to be carried on the PUSCH. Each priority level corresponds to a part of the CSI report. The UE drops the lower priority CSI parts so that the payload size of the CSI report fits into the PUSCH resource allocation. The CSI report is decomposed into multiple CSI parts. Here, a CSI part (or so-called subband PMI in Release 15) contains the CSI content associated with the even or odd subband of the CSI report. In addition, each subband PMI is associated with a priority level. The motivation behind the subband-based CSI decomposition and omission approach of Release 15 is that if the first subband PMI of CSI report n is omitted, the base station can use the CSI content of the second subband PMI reported by CSI report n to estimate the CSI of the omitted first subband PMI by using an interpolation scheme. In this way, since adjacent subbands are usually highly correlated, this approach can avoid severe performance degradation.

[0022] Therefore, the known solutions as described above have disadvantages, which are addressed by the present invention according to the present disclosure.Therefore, there is a need for new enhanced CSI reporting schemes and rules (eg, CSI or UCI omission) for distributed MIMO cooperative transmission. Summary of the Invention

[0023] The purpose of the embodiments of this document is to provide a method and apparatus for codebook-based precoding CSI feedback reporting in a wireless communication network (such as an advanced 5G network).

[0024] According to one aspect of the embodiments herein, a method performed by a wireless device (or UE) is provided for generating and reporting or transmitting a CSI report, the method comprising:

[0025] o Receive CSI reporting configuration from a network node;

[0026] o determining, based on the received CSI reporting configuration, a set of linear combining coefficients for a precoding matrix for a plurality of CSI reference signal (CSI-RS) resources; wherein the set of linear combining coefficients comprises a plurality of non-zero combining coefficients, and wherein the CSI-RS resources are indicated in the CSI reporting configuration;

[0027] o determining a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by means of bits or by means of bits, and assigning an ordering to the bits of the bitmap and assigning an ordering to the bits to be used in conjunction with the bits in the CSI report Figure 1 Assign the same ranking as the multiple non-zero combining coefficients reported to the network node;

[0028] o dividing the plurality of non-zero combining coefficients into two or more CSI groups having associated priority levels;

[0029] o generating a CSI report, the CSI report comprising indications of the spatial domain components and the frequency domain components, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating a payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients for at least one of the two or more CSI groups; and

[0030] o Transmitting or reporting uplink control information (UCI) including the CSI report to the network node on an uplink (UL) channel.

[0031] According to another aspect of the embodiments herein, a method performed by a network node is provided, the method comprising:

[0032] - transmitting a CSI reporting configuration to the wireless device; for enabling the wireless device to perform:

[0033] - determining, based on the received CSI reporting configuration, a set of linear combining coefficients of a precoding matrix for a plurality of CSI reference signal (CSI-RS) resources; wherein the set of linear combining coefficients comprises a plurality of non-zero combining coefficients, and wherein the CSI-RS resources are indicated in the CSI reporting configuration;

[0034] - determining a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by means of bits or by means of bits;

[0035] - assigning an order to the bits of the bitmap and assigning an order to the bits to be used in the CSI report Figure 1 Assign the same ranking as the multiple non-zero combining coefficients reported to the network node;

[0036] -dividing the plurality of non-zero combining coefficients into two or more CSI groups with associated priority levels;

[0037] - generating a CSI report to be transmitted to the network node, the CSI report comprising an indication of the spatial domain component and the frequency domain component, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients for at least one of the two or more CSI groups; and

[0038] - receiving uplink control information (UCI) including the CSI report on an uplink (UL) channel from the wireless device.

[0039] According to another aspect of the embodiments herein, there is also provided a wireless device or UE, comprising a processor and a memory, wherein the memory contains instructions executable by the processor, whereby the UE is operable or configured to perform any of the embodiments described in the detailed description relating to actions performed by the UE, such as described in method claim 1.

[0040] According to another aspect of the embodiments herein, a network node is also provided, comprising a processor and a memory, wherein the memory contains instructions executable by the processor, whereby the network node is operable or configured to perform any embodiment related to the network node in the detailed description, such as at least method claim 2.

[0041] A computer program is also provided, comprising instructions, which, when executed on at least one processor of a UE, cause the at least one processor to perform the actions or method steps described in this application.

[0042] A computer program is also provided, comprising instructions which, when executed on at least one processor of the network node, cause the at least one processor to perform the method steps described herein.

[0043] A carrier is also provided, comprising the computer program, wherein the carrier is one of a computer-readable storage medium, an electronic signal, an optical signal, or a radio signal.

[0044] The advantages of the embodiments of the present application include significantly reducing the UE feedback overhead and computational complexity in codebook-based CSI reporting for joint transmission from a network node or gNB equipped with multiple RRHs, panels, or antenna arrays to a UE. Another advantage is reduced CSI reporting latency.

[0045] Additional advantages of embodiments of the present application are provided in the detailed description of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0047] Figure 1 shows a schematic diagram of a wireless communication system;

[0048] Figure 2 shows a block-based model for MIMO DL transmission using codebook-based precoding according to LTE Release 8;

[0049] Figure 3 is a schematic diagram of a wireless communication system for communicating information between a transmitter and multiple receivers, in which embodiments of the present application may be applied;

[0050] Figure 4 A flowchart illustrating a method performed by a wireless device (or UE) according to some embodiments of the present application is provided;

[0051] Figure 5 A flowchart illustrating a method performed by a network node according to some embodiments of the present application;

[0052] Figure 6 is a block diagram depicting a wireless device according to some embodiments of the present application;

[0053] Figure 7 is a block diagram depicting a network node according to some embodiments of the present application; DETAILED DESCRIPTION

[0054] The exemplary embodiments are described in detail below with reference to the accompanying drawings, through various scenarios to facilitate understanding of the solutions described herein.

[0055] For the two-stage Type-IICSI report of 3GPP Release 15, the second-stage precoder F2(s) is calculated based on the subband, so that for the rth transmission layer, The number of columns depends on the number of configured CQI subbands S. Here, a subband refers to a group of adjacent physical resource blocks (PRBs). One disadvantage of Type-IICSI feedback is that the feedback overhead is large when reporting the combining coefficients on a subband basis. The feedback overhead increases approximately linearly with the number of subbands, and when the number of subbands is large, the feedback overhead becomes quite large. In order to overcome the high feedback overhead problem of the Type-IICSI reporting scheme of Release 15, 3GPP RAN#81 decided to study feedback compression schemes for the second-level precoder F2. Some research results have shown that when F2 is transformed into a transform domain called the delay domain using a small number of DFT-based basis vectors, the number of beam combining coefficients in F2 can be greatly reduced. The corresponding three-level precoder relies on three levels (i.e., three components) Codebook. The first component is represented by the matrix F1, which is the same as the NR component of Release 15, is independent of the transmission layer (r), and contains multiple spatial domain (SD) basis vectors selected from the spatial codebook. The second component is represented by the matrix It is layer-dependent and is used to select multiple delay domain (DD) basis vectors from a matrix based on discrete Fourier transform (DFT), also known as delay codebook. The third component is represented by the matrix It represents a plurality of combining coefficients for combining the SD basis vectors and the DD basis vectors selected from the spatial codebook and the delay codebook, respectively.

[0056] Assuming a rank R transmission, for the configured 2N1N2 antennas / CSI-RS ports and the configured S subbands, for the first polarization of the antenna port and the rth transmission layer, the three-component precoding matrix or CSI matrix is ​​expressed as:

[0057]

[0058] For the second polarization of the antenna port and the rth transmission layer, the three-component precoding matrix or CSI matrix is ​​expressed as:

[0059]

[0060] where b u (l=0,…,L-1) represents the u-th SD basis vector selected from the spatial codebook, is the d-th FD basis vector associated with the r-th layer and selected from the delayed codebook, is the complex delay domain combining coefficient associated with the u-th SD basis vector, the d-th FD basis vector, and the p-th polarization, D represents the number of configured D basis vectors, and α (r) is a normalized scalar.

[0061] The advantage of the three-component CSI reporting scheme in the above equation is that the feedback overhead of the precoding matrix or CSI matrix combining coefficients no longer depends on the number of configured CQI subbands (i.e., it is independent of the system bandwidth). Therefore, the above three-component codebook has recently been adopted by the two-stage Type-II CSI reporting specification of 3GPP Rel.16.

[0062] As previously mentioned, the current 3GPP NR Type-I and Type-II codebooks only support deployments where the network node (e.g., gNB) is equipped with a single panel or multiple co-located panels or antenna arrays. For coordinated transmission scenarios where multiple panels or antenna arrays are connected to the same network node (e.g., gNB) to form a large distributed multi-panel or multi-antenna array, CSI reporting for distributed MIMO coordinated transmission is not supported.

[0063] Therefore, the present invention proposes a novel codebook and CSI reporting scheme for distributed MIMO deployments. According to this embodiment, the present invention addresses the previously described shortcomings. Specifically, it proposes a method to significantly reduce the feedback overhead and computational complexity of codebook-based CSI reporting at user equipment for distributed MIMO deployments.

[0064] Precoder structure and CSI reporting

[0065] It should be noted that the term "precoding" and "precoder" have the same meaning. Therefore, in this disclosure, precoding and precoder can be used interchangeably.

[0066] The term "beam" is used to denote the precoding / filtering of signals at the antenna port of a device (UE or gNB) using a specific set of coefficients to achieve spatially selective / directional transmission of outgoing signals or spatially selective / directional reception of incoming signals. The terms precoding, precoder, or filtering can refer to signal processing performed in either the analog or digital domain. The set of coefficients used for spatially directional transmission / reception in a specific direction can vary depending on the direction. The term "Tx beam" denotes spatially selective / directional transmission, and the term "Rx beam" denotes spatially selective / directional reception. The set of coefficients used for precoding / filtering transmission or reception is referred to as the "spatial filter." In this document, the terms "spatial filter" and "beam direction" are used interchangeably, as the spatial filter coefficients determine the spatial direction of transmission / reception.

[0067] Exemplary embodiments of the present invention may be employed in Figure 1 or Figure 2 The depicted wireless communication system or network is implemented, including a transmitter or transceiver (such as a base station) and a communication device (receiver) or user (such as a mobile or fixed terminal or IoT device or UE), as described in the background technology part of the present disclosure.

[0068] refer to Figure 3 , which depicts a method for transmitting data between a transmitter 200 (such as a base station or gNB) and a plurality of wireless devices 2021 to 202 n Schematic diagram of a wireless communication system for communicating information between UEs (e.g., served by a network node, such as a base station 200). The network node 200 and the UE 202 may communicate via a wireless communication link or channel 204 (e.g., a wireless link). The network node 200 includes one or more antennas ANT T or an antenna array having multiple antenna elements, and a signal processor 200a. UE 202 includes one or more antennas ANT R or an antenna array having multiple antennas, a signal processor 202a1, 202a n , and transceivers 202b1, 202b n Base station 200 and each UE 202 may operate in accordance with the inventive teachings described herein.

[0069] According to an embodiment of the present invention, a wireless device is configured to generate a CSI report about a radio channel between the wireless device and a network node (e.g., a gNB in ​​a wireless communication system). The radio channel may be a MIMO channel.

[0070] The wireless device may include one or more of the following: a UE, a mobile terminal, a fixed terminal, a cellular IoT-UE, a vehicle-mounted UE, a vehicle group leader (GL) UE, an IoT, a narrowband IoT (NB-IoT) device, a WiFi non-access point station (non-AP STA) (e.g., 802.11ax or 802.11be), a ground vehicle, an aircraft, a drone, a mobile base station, a roadside unit, a building, or any other item or device (e.g., a sensor or actuator) equipped with a network connection to enable communication using the wireless communication network, or a macro cell base station, a small cell base station, a central unit of a base station, a distributed unit of a base station, a repeater, a remote radio head, an AMF, an SMF, a core network entity, a mobile edge computing entity, a network slice in the context of NR or 5G core, or any transmission / reception point (TRP) that enables an item or device to communicate using the wireless communication network, wherein the item or device is equipped with a network connection to enable communication using the wireless communication network. The receiver may be a network node, a gNB, or a base station. Conversely, the transmitter can be considered as a wireless base station or network node or gNB, while the receiver can be a UE.

[0071] In general, and according to some non-limiting exemplary effects achieved by embodiments herein, a UE receives a CSI reporting configuration from a network node or gNB indicating one or more CSI-RS resources. Each CSI-RS resource includes a number of CSI-RS ports and is associated with a panel or remote radio head or antenna array of the network node or gNB. In some examples, the CSI reporting configuration includes at least a parameter P CSI-RS , or N1, and N2, where P CSI-RS The value of indicates the number of antenna ports for CSI-RS or CSI-RS resources of one polarization of the antenna port of the panel or remote radio head (RRH), and N1 and N2 represent the number of antenna ports of the first dimension and the second dimension of one polarization of the panel or antenna array of the RRH, respectively.

[0072] Precoder Description

[0073] In certain embodiments, the wireless device determines a precoder or precoder vector or matrix for each of the RI transmission layers and indicates the precoder or precoder vector or matrix in a CSI report. Each of the plurality of precoder vectors or matrices is represented as a linear combination of a spatial domain component and a frequency domain component, and a set of combining / combining coefficients (as described herein) for combining the spatial domain component and the frequency domain component. The plurality of precoder vectors or matrices may be represented by indicating the spatial domain component, the frequency domain component, and the set of linear combination coefficients in the CSI report.

[0074] The terms "combining coefficient" and "merging coefficient" are used interchangeably in this disclosure.

[0075] The precoder vector or matrix can be defined across multiple subbands N3. The bandwidth of the DL channel can be divided into multiple subbands, where each precoder vector or matrix is ​​associated with a subband. In some embodiments, the number of precoder subbands is an integer multiple (or a real multiple less than 1) of the number of CQI subbands configured for the wireless device. The number of CQI subbands can be indicated to the wireless device via the CSI report configuration.

[0076] The precoder vector or matrix is ​​determined by the wireless device based on measurements of a received reference signal (e.g., CSI-RS), where the reference signal is provided by another wireless device or a network node. The reference signal is configured to the wireless device via a CSI reporting configuration. The wireless device is configured to perform CSI measurements on one or more configured CSI-RSs, determine precoder vectors or matrices based on the CSI measurements, and indicate these precoder vectors or matrices in a CSI report.

[0077] The spatial domain component of the precoder

[0078] In some embodiments, the wireless device is configured to determine one or more spatial domain components SD of a set of linear combination coefficients of a precoder. Each spatial domain component corresponds to a basis vector. A set of spatial domain components may correspond to a first set of basis vectors. To determine the precoder vector or matrix, the wireless device is configured to select one or more spatial domain components from the first set of basis vectors. A basis vector from the first set of basis vectors is associated with a set of antenna ports or CSI-RS ports of an antenna port group. A set of antenna ports or CSI-RS ports may be associated with first and second polarizations. The first set of antennas or CSI-RS ports may be associated with the first polarization, and the second set of antennas or CSI-RS ports may be associated with the second polarization. The selection of one or more basis vectors (one or more spatial domain components) from the first set of basis vectors may be polarization-common or polarization-specific. In the case of polarization-common selection, the basis vectors selected from the first set of basis vectors are common to both polarizations of the antennas or CSI-RS ports configured for the wireless device. In the case of polarization-specific selection, the wireless device independently selects the basis vectors selected from the first set for both polarizations of the antennas or CSI-RS ports configured for the wireless device. In an exemplary embodiment, the wireless device selects L basis vectors of a precoder vector or matrix from a first set of basis vectors and indicates the selected L basis vectors in a CSI report. In some examples, the selected L basis vectors are polarization-common, so the L basis vectors selected for the first and second groups of antennas or CSI-RS ports are the same. In some examples, the selected L basis vectors are polarization-dependent, so the L basis vectors selected for the first or second group of antennas or CSI-RS ports may be different. In some examples, the selected L basis vectors are layer-dependent and are different for a subset of transmission layers of the precoder or for each transmission layer. In this case, each layer subset or each layer of the precoder selects a basis vector independently. In some other examples, the selected L basis vectors are layer-independent and are the same for all layers of the precoder.

[0079] In some embodiments, the first group of basis vectors is an orthogonal basis vector group, that is, the basis vector group includes multiple orthogonal basis vectors. For example, the first group of basis vectors is a basis vector group based on DFT or DCT. In some embodiments, the first group of basis vectors is defined by a DFT or IDFT basis vector group, or by an oversampled DFT or IDFT basis vector group. In some embodiments, the first group of basis vectors includes a group of vectors based on discrete cosine transform (DCT). When the first group of basis vectors is defined by a DFT (DFT or IDFT) based basis vector group, the first group of basis vectors is represented by a DFT or IDFT matrix. In some embodiments, the first group of basis vectors is defined by a rotated DFT-based basis vector, where the index of the DFT-based vector is i1=O1i 11 +q1,i11 =0,…,N1-1,i2=O2i 22 +q2,i 22 =0,…,N2-1, where q1=0,…,O1-1 and q2=0,…,O2-1 are the rotation factors of the rotated DFT-based basis vectors, N1 and N2 represent the number of antenna ports in the first and second dimensions, respectively, and O1 and O2 represent the oversampling factors in the first and second dimensions, respectively. In this case, the rotated DFT-based basis vectors are selected from an oversampled DFT-based basis vector set consisting of O1, O2, N1, and N2 DFT-based vectors. The rotation factors may be selected by the wireless device, configured for the wireless device, or reported by the wireless device as part of the CSI report. The oversampling factors may be fixed in the 3GPP specification and thus known to the wireless device. Parameters N1 and N2 may depend on the CSI-RS resource and may be different for different CSI-RS resources indicated in the CSI reporting configuration.

[0080] In some embodiments, the first set of basis vectors is an orthogonal basis vector set, that is, the basis vector set includes a plurality of orthogonal basis vectors, including an identity matrix. CSI-RS or P CSI-RS Each vector of / 2 is associated with a CSI-RS port and contains P CSI-RS -1 or zeros and one 1, where P CSI-RS or P CSI-RS / 2 (e.g., per antenna port polarization) is the number of antenna ports in one or more antenna port groups. In some examples, P CSI-RS It may depend on the CSI-RS resource and may be different for different CSI-RS resources.

[0081] In some embodiments, there are multiple first groups of basis vectors, where each first group of basis vectors is associated with a CSI-RS resource. The dimensions of each basis vector group may be based on N1, N2, and / or P. CSI-RS These parameters may be the same or different for different CSI-RS resources. The value of parameter L may vary with the CSI-RS resource. TRP When N CSI-RS resources are selected from the configured CSI-RS resources, there are L n , n=0,…,N-1 parameters, where L n represents the number of SD components selected by the wireless device from the first set of basis vectors associated with the nth CSI resource.

[0082] Frequency domain components of the precoder

[0083] In some embodiments, the wireless device is configured to determine one or more frequency domain FD components of a set of linear combination coefficients of a precoder. Each frequency domain FD component of the precoder corresponds to a basis vector. A set of frequency domain components corresponds to a second set of basis vectors. To determine the precoder vector or matrix, the wireless device is configured to select one or more frequency domain components (i.e., basis vectors) from the second set of basis vectors. A basis vector in the second set of basis vectors is associated with a plurality of subbands N3 of the DL channel bandwidth. A subband can contain multiple physical resource blocks (PRBs). In some embodiments, the number of subbands N3 depends on the number of CQI subbands, or on the CQI subband size configured for the wireless device.

[0084] In some embodiments, the second set of basis vectors is defined by a set of orthogonal basis vectors, i.e., the set of basis vectors includes multiple orthogonal vectors. For example, the second set of basis vectors is a DFT- or DCT-based basis vector. In some embodiments, the second set of basis vectors is defined by a DFT- or IDFT-based basis vector, or by an oversampled DFT- or IDFT-based basis vector. In some embodiments, the second set of basis vectors includes a set of discrete cosine transform (DCT)-based vectors. When the second set of basis vectors is defined by a DFT-based (DFT or IDFT)-based basis vector, the second set of basis vectors can be represented by a DFT or IDFT matrix. In some embodiments, the second set of basis vectors is defined by rotated DFT-based basis vectors, where the index of the DFT-based vector is defined by d3=03i3+q3, i3=0,…,N3-1, where q3=0,…,03-1 is the rotation factor of the rotated DFT-based basis vector. In this case, the rotated DFT-based basis vectors are selected from the oversampled DFT-based basis vectors including O3N3 DFT-based vectors. This means that the set of basis vectors corresponding to the frequency domain components is an oversampled DFT- or DCT-based matrix containing O3 orthogonal DFT- or DCT-based matrices. The rotation factors may be selected by the wireless device, configured to the wireless device, or reported by the wireless device as part of the CSI report. In some embodiments, the number of frequency domain subbands defines the length (N3) of the basis vectors of the second set of basis vectors. The number of frequency domain subbands may be indicated to the wireless device, for example, via higher layers, or may be fixed in the NR specification and known to the wireless device, or may be selected by the wireless device and indicated in the CSI report.

[0085] In some embodiments, a set of frequency domain components is a basis vector group represented by a DFT-based or DCT-based matrix or an oversampled DFT-based or DCT-based matrix, and the basis vector group contains multiple basis vectors representing the frequency domain components, and each basis vector is a DFT-based or DCT-based vector.

[0086] In some embodiments, the basis vector group of the frequency domain components is an oversampled DFT or DCT-based matrix, which includes O3 DFT or DCT-based orthogonal matrices.

[0087] In some embodiments, the wireless device is configured to select M frequency domain components from a second set of basis vectors in a precoding matrix or vector for N selected CSI-RS resources.

[0088] In some embodiments, the wireless device selects M frequency domain components from a second set of basis vectors for a precoding matrix or vector for each of the N selected CSI-RS resources.

[0089] In some embodiments, the parameter M is configured to the wireless device, is selected and reported from the wireless device to the network node, is derived from another parameter such as N3, or it is fixed in the 3GPP NR specification and is therefore known to the wireless device.

[0090] Precoding matrix structure

[0091] According to one embodiment, the precoding matrix or vector indicated in the CSI report may be TRP The precoding matrix comprises N precoding matrices or vectors, each of which is associated with one CSI-RS resource.

[0092] The precoder vector or matrix W for the lth transmission layer l In multiple frequency domain units / PRBs or frequency domain precoding units (N3) and spatial units (2N1N2 or P CSI-RS ) is defined for N selected CSI-RS resources. In an exemplary embodiment, the precoder vector or matrix W for the lth transmission layer and the gth CSI-RS resource is l Defined as:

[0093] or

[0094] or

[0095]

[0096] in:

[0097] W 1,g,l is L selected from the first set of basis vectors v The matrix of basis vectors,

[0098] W 2,g,l is the coefficient matrix,

[0099] To include M v A matrix of basis vectors, where each vector is associated with an N3 frequency domain element of the precoding matrix,

[0100] b g,l,m are the N1N2×1 or P×1 basis vectors associated with the antenna ports of the CSI-RS port group of the g-th antenna or precoding matrix,

[0101] a g,l,m,i are the N3×1 basis vectors associated with the N3 frequency domain elements of the precoding matrix,

[0102] c g,l,m,i is the complex precoder coefficient or combining coefficient,

[0103] α is the normalization factor.

[0104] According to one embodiment, the precoding matrix may include a plurality of precoding matrices, wherein each precoding matrix is ​​associated with an antenna port group or a CSI-RS port group.

[0105] In some embodiments, the matrix containing the selected FD components is independent of the CSI-RS resources, i.e. This means that there is only a single matrix In the CSI report, there is only one FD indicator for the selected FD component per layer, subset of layers, or all layers of the precoding matrix.

[0106] Number of frequency domain units / subbands:

[0107] According to one embodiment, the wireless device is configured to determine the number of CQI subbands based on the parameter Q and the number of CQI subbands N. CQI To determine the dimension N3 of the second set of basis vectors The parameter Q may be determined by: being configured by a higher layer to the wireless device, being autonomously selected by the wireless device, or being a fixed value known to the wireless device (e.g., predefined in the 3GPP NR specification).

[0108] Selection of basis vectors and indication in CSI reports

[0109] In some embodiments, the wireless device determines a set of combining coefficients for combining the selected SD component and the FD component to form a precoder. The wireless device generates and transmits a CSI report to a network node or other wireless device, the report including an indication of the selected one or more SD components, an indication of the selected one or more FD components, and an indication of combining coefficients for a precoder vector or matrix.

[0110] According to an embodiment, the UE is configured to select L from a first set of basis vectors for a plurality of antennas or CSI-RS port groups of a precoding matrix n basis vectors. Parameter L n The CSI-RS resources for the multiple N selections may be different. In some examples, the parameter L n The precoding matrix can be the same for all v transmission layers. n It can be determined in any of the following ways: configured by the network to the UE, reported by the UE, or fixed as a predefined value in the NR specification and known to the UE.

[0111] According to an embodiment, the UE is configured to indicate one or more basis vectors selected from a first set of basis vectors or multiple first sets of basis vectors in the CSI report. In some examples, the UE reports one for each CSI-RS resource. A bit indicator to indicate the selected L n basis vectors.

[0112] According to an embodiment, the UE indicates in the CSI report, for each selected CSI-RS resource or for all N selected CSI-RS resources, a basis vector selected from the second set of basis vectors by one or more indicators per transmission layer or subset of transmission layers of the precoding matrix. For example, such an indicator may be or Combined bit indicator, where N3 and M v The parameter M represents the total number of the second set of basis vectors used by the precoding matrix layer v and the number of basis vectors selected from them for the selected CSI-RS resource or in all N CSI-RS resources. v The N CSI-RS resources associated with the precoding matrix may be the same or different.

[0113] In the following, it is assumed that the number of basis vectors M selected from the second set of basis vectors is v Configured via higher layers (e.g. RRC), or fixed in the NR specification and known to the UE, or reported by the UE.

[0114] UCI omission mechanism

[0115] Uplink control information (UCI) omission occurs when the uplink resources allocated by the base station or network node to the wireless device (user equipment, UE) are insufficient to carry the entire content of one or more CSI reports. The UE can control the CSI payload size of the CSI report by adjusting the number of precoder coefficients to be reported. In the case of UCI or CSI omission, the UE can directly reduce the number of precoder coefficients to be reported in one or more CSI reports based on the available uplink resources (such as available PUSCH resources). However, such a reduction in the number of precoder combining coefficients will require recalculation of the precoder coefficients and all basis vectors associated with the precoder vectors or matrices of one or more CSI reports, occupying additional UE resources. These additional UE resources may not be available on the UE side. Therefore, the UCI omission scheme should not require recalculation of the precoder vectors or matrices of one or more CSI reports.

[0116] According to an embodiment, uplink resources or uplink control information (UCI) may include one or more reduced-size CSI reports, where the UCI may include UCI or CSI part 1 and UCI or CSI part 2. In some examples, the UCI or CSI part 1 may include an indication of the number of precoding (amplitude and / or phase) combining coefficients of a precoder vector or matrix for each layer or for all layers in the one or more CSI reports. In some examples, the UCI or CSI part 1 may include one or more rank indications or rank indices (RIs) for indicating the number of layers of the precoder vector or matrix in the CSI report for one or more CSI reports.

[0117] According to an embodiment, a UE is configured to receive an uplink resource allocation from a base station for uplink transmission of one or more CSI reports. The UE may determine that the resource allocation size is insufficient to carry the entire content of the CSI report. In this case, the UE may perform a CSI or UCI omission procedure to determine one or more reduced-size CSI reports that fit within the uplink resource allocation. The one or more reduced-size CSI reports may be transmitted to a network node (e.g., a base station, gNB) via an uplink channel.

[0118] In one embodiment, the CSI omission process is based on discarding some of the amplitude and phase coefficients of the precoder or combining coefficients of one or more CSI reports. This means that the UE is configured to omit parts of one or more CSI reports, thereby generating a reduced CSI report for transmission to a network node, such as a base station (e.g., a gNB), via an uplink channel.

[0119] According to an embodiment, for each CSI report, a set of combining coefficients is divided into two or more CSI groups to support UCI or CSI omission, wherein a specific ordering is applied to the combining coefficients and the combining coefficients are split or divided into two or more CSI groups. In addition, each CSI report and each CSI group can be associated with a priority level.

[0120] In one embodiment, the CSI or UCI omission process is based on omitting the associated phase and amplitude of the precoder vector or matrix of the associated CSI report by dropping one or more CSI groups according to a priority rule. Therefore, when CSI or UCI omission occurs, some amplitude and / or phase coefficients of the precoder vector or matrix indicated in the CSI report are omitted.

[0121] According to an embodiment, the UE may discard low-priority CSI groups when UCI or CSI is omitted until the CSI report payload size adapts to the resources allocated by the network node, such as the base station (e.g., gNB). When a CSI group of a specific priority level is omitted, the UE may discard all CSI content at that priority level.

[0122] The following embodiments propose a scheme for ordering the bits in the bitmap and, therefore, determining the ordering of the combining coefficients. It is assumed that the ordering of the combining coefficients in at least two CSI groups follows the ordering of the bits in the bitmap. The purpose of this combining coefficient ordering is to reduce performance degradation when UCI or CSI is omitted, i.e., when one or more CSI groups are dropped from the CSI report.

[0123] Selection and indication of non-zero combining coefficients in CSI reports

[0124] In some embodiments, the wireless device is configured to select M FD components for a precoding matrix and indicate the selected M FD components for N selected CSI-RS resources in a CSI report.

[0125] In some embodiments, the wireless device is configured to select L for the precoding matrix n SD components and indicates the selected L associated with the nth CSI-RS resource in the CSI report n SD components.

[0126] Note that the SD component is the same for both polarizations of the antenna port associated with a TRP or panel or RRH or CSI-RS resource. Therefore, the precoding matrix is ​​the same as SD components are associated, where L n The SD components are the same for both polarizations for all n=0,…,N-1.

[0127] In some embodiments, the wireless device selects Merging coefficients, where Ln is the number of spatial domain (SD) components associated with the nth selected CSI-RS resource, and M is the number of frequency domain (FD) components. The number of SD and FD components is selected and reported by the wireless device, or configured by higher layers (e.g., via RRC) to the UE, or is fixed in the specification and known to the wireless device.

[0128] To reduce feedback overhead, wireless devices can be configured to K or fewer non-zero combining coefficients are determined from the K combining coefficients. The K non-zero combining coefficients are reported by the wireless device to the network node (e.g., gNB) as part of the CSI report. The value of K is configured for the wireless device, fixed in the 3GPP specification and thus known to the wireless device, or selected by the wireless device and reported to the network node.

[0129] In some embodiments, the wireless device determines the size of A bitmap is used to indicate the locations of selected non-zero combining coefficients. The bitmap contains both 1s and 0s. A '1' is associated with a selected non-zero combining coefficient, a '0' is associated with a zero or unselected combining coefficient, and vice versa. In some examples, the bitmap is selected per layer of the precoding matrix. The bitmap is part of the CSI report.

[0130] In some embodiments, the wireless device is configured to use A bit indicator indicates the position of the selected non-zero coefficient.

[0131] In some embodiments, the UE is configured to TRP N TRPs or CSI-RS resources are selected from the configured TRPs or CSI-RS resources. The precoding matrix indicated in the CSI report is defined for the N selected CSI-RS resources or TRPs.

[0132] In some embodiments, the maximum number of non-zero combining coefficients for each layer across all N selected CSI-RS resources or TRPs is bounded by K0. In some embodiments, for RI>1, the maximum value of the sum of the non-zero combining coefficients for all layers and all N selected CSI-RS resources or TRPs is 2K0.

[0133] In some embodiments, the wireless device reports (in a CSI report) a bitmap containing bit field, where each bit is associated with the TRP index (n), SD component index (l n ), FD component index (m n ) and rank index (r n ) is associated, where l n =0,…,2L n -1;m n=0,…,M n -1; r n =0,…,R n -1, and L n 、M n and R n They respectively represent the number of CSI-RS resource-specific SD components, the number of CSI-RS resource-specific FD components, and the rank value or number of layers specifically supported by the CSI-RS resource for the nth CSI-RS resource.

[0134] The following embodiments assume that each bit is associated with a combining coefficient, where '0' indicates that the associated combining coefficient is not reported, and '1' indicates that the associated combining coefficient is reported.

[0135] In some embodiments, the ordering of the amplitude and phase information of the combining coefficients follows the ordering of the bits or bit fields of the bitmap in the CSI report.

[0136] In some embodiments, the non-zero combining coefficients of the precoding matrix associated with the strongest TRP or CSI-RS resource are included in CSI Group 1, where the combining coefficients of the strongest TRP or CSI-RS resource include the strongest coefficient indicated by the strongest coefficient indicator. Note that the magnitude and / or phase of the strongest coefficient are not reported. In some embodiments, the strongest coefficient indicator is the strongest coefficient indicator associated with the first layer of the precoding matrix.

[0137] In some embodiments, the non-zero combining coefficients of the precoding matrix associated with the strongest TRP or CSI-RS resource are included in CSI group 1, where the reference magnitude of the non-zero combining coefficients associated with the strongest TRP or CSI-RS resource is value '1' and is not reported.

[0138] Bitmap sorting scheme

[0139] Grouping scheme 1:

[0140] In some embodiments, The bit fields are grouped into N groups, where N is the number of selected TRP or CSI-RS resources. Each of the N groups is associated with a TRP or CSI-RS resource index and contains 2L n M n R n In some embodiments, each group contains 2L n M n R n The N groups of bits are sorted in ascending order from left to right by TRP or CSI-RS resource index or remapped TRP or CSI-RS resource index.

[0141] Option 1a + Option 1b

[0142] In some embodiments, 2L in each group n M n R n bits are further grouped into R n subgroups, each containing 2L n M n bits, where r n subgroups are associated with one layer of the precoding matrix. In option 1a, the 2L n M n bits are further grouped into M n subgroups, each containing 2L n bits, and the mth n All bits of a subgroup are associated with the same FD component index. n Each of the bits is associated with a different SD index. In option 1b, 2L n M n bits are further grouped into 2L n subgroups, each containing M n bits, and the first n All bits of a subgroup are associated with the same SD component index. n Each of the 10 bits is associated with a different FD component index.

[0143] In some embodiments, each comprising 2L n M n bits of R n The subgroups are sorted in ascending order from left to right. In option 1a, each contains 2L n M bits n The subgroups are sorted in ascending order from left to right according to the FD index or remapped FD index. The 2L in each subgroup n bits are sorted in ascending order from left to right according to the SD index or remapped SD index. In option 1b, each containing M n 2L of bits n The subgroups are sorted in ascending order from left to right according to the SD index or remapped SD index. n The bits are sorted in ascending order from left to right according to the FD index or remapped FD index.

[0144] Option 1c + Option 1d

[0145] In some embodiments, 2L in each group n M n R n bits are further grouped into M n subgroups, each containing 2L nR n bits, where the mth n subgroups are associated with the FD components of the precoding matrix. In option 1c, 2L n R n bits are further grouped into R n subgroups, each containing 2L n bits, and the rth n All bits of a subgroup are associated with the same layer index. n Each bit is associated with a different SD component index. In option 1d, 2L n R n bits are further grouped into 2L n subgroups, each containing R n bits, and the first n All bits of a subgroup are associated with the same SD component index. n Each of the bits is associated with a different layer index.

[0146] In some embodiments, each comprising 2L n R n M bits n The subgroups are sorted in ascending order from left to right by FD index or remapped FD index. In option 1c, each contains 2L n bits of R n The subgroups are sorted in ascending order from left to right. The 2L in each subgroup n bits are sorted in ascending order from left to right according to the SD index or remapped SD index. In option 1d, each containing R n 2L of bits n The subgroups are sorted in ascending order from left to right according to the SD index or remapped SD index. n The bits are sorted in ascending order from left to right.

[0147] Option 1e + Option 1f

[0148] In some embodiments, 2L in each group n M n R n bits are further grouped into 2L n subgroups, each containing M n R n bits, where the first n The subgroups are associated with the SD components of the precoding matrix. In option 1e, M n R n bits are further grouped into M n subgroups, each containing R nbits, and all bits of the m n th subgroup are associated with the same FD component index. R n Each of the bits is associated with a layer index. In option 1e, M n R n bits are further grouped into R n subgroups, each subgroup containing M n bits, and all bits of the r n th subgroup are associated with the same layer index. M n Each of the bits is associated with an FD component index.

[0149] In some embodiments, each of the 2L n Rsubgroups containing M n bits is sorted in ascending order from left to right according to the SD index or the remapped SD index. In option 1e, each of the R n subgroups containing 2L n bits is sorted in ascending order from left to right. The 2L n bits in each subgroup are sorted in ascending order from left to right according to the SD index or the remapped SD index. In option 1e, each of the M n subgroups containing R n bits is sorted in ascending order from left to right according to the FD index or the remapped FD index. The R n bits in each subgroup are sorted in ascending order from left to right. In option 1f, each of the R n subgroups containing M n bits is sorted in ascending order from left to right. The M n n bits in each subgroup are sorted in ascending order from left to right according to the FD index or the remapped FD index.

[0150] Grouping scheme 2:

[0151] In some embodiments, bit fields are grouped into R groups, where R is the maximum rank value supported among the selected N TRPs or CSI-RS resources. Each group is associated with the rth layer index and includes at most bits. When R n < R, the 2L n M n R n bits associated with the nth TRP or CSI-RS resource index only appear in the first R n groups. The R groups are sorted in ascending order from left to right.

[0152] Option 2a + Option 2b

[0153] In some embodiments, each group bits are further grouped into N subgroups, each containing 2L n M n bits, where the nth subgroup is associated with a TRP or CSI-RS resource index. In option 2a, 2L n M n bits are further grouped into 2L n subgroups, each containing M n bits, and the first n All bits of a subgroup are associated with the same SD component index. n Each of the bits is associated with an FD component index. In option 2b, 2L n M n bits are further grouped into M n subgroups, each containing 2L n bits, and the mth n All bits of a subgroup are associated with the same FD component index. n Each of the bits is associated with a different SD component index.

[0154] In some embodiments, each comprising 2L n M n The N subgroups of M bits are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. n 2L of bits n The subgroups are sorted in ascending order from left to right according to the SD index or remapped SD index. n bits are sorted in ascending order from left to right according to the FD index or remapped FD index. In option 2b, each contains 2L n M bits n The subgroups are sorted in ascending order from left to right according to the FD index or remapped FD index. The 2L in each subgroup n The bits are sorted in ascending order from left to right according to the SD index or remapped SD index.

[0155] Option 2c + Option 2d

[0156] In some embodiments, each group The bits are further grouped into 2L subgroups, where L is the maximum number of SD components selected in the N selected TRPs or CSI-RS resources. The lth subgroup is associated with the SD component and contains bits. When L nWhen L, the M bits associated with the nth TRP or CSI-RS resource index only appear in the first 2L n groups. In Option 2c, the n bits in each subgroup are further grouped into N subgroups, each subgroup containing M bits, where all bits in the nth subgroup are associated with the same TRP or CSI-RS resource index. Each of the M n bits is associated with a different FD component index. In Option 2d, the n bits in each subgroup are further grouped into M subgroups, where M is the maximum number of FD components selected among N selected TRP or CSI-RS resources. When M < M, the bits associated with the nth TRP or CSI-RS resource index only appear in the first M n groups. All bits in the mth subgroup are associated with the same FD component index. Each bit in the mth subgroup is associated with a different TRP or CSI-RS resource index. n

[0157] In some embodiments, the 2L subgroups are sorted in ascending order from left to right according to the SD index or the remapped SD index. In Option 2c, each of the N subgroups containing M n bits is sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. The M n bits in each subgroup are sorted in ascending order from left to right according to the FD index or the remapped FD index. In Option 2d, the M n [[ID=]25] subgroups are sorted in ascending order from left to right according to the FD index or the remapped FD index. The bits in each subgroup are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index.

[0158] Option 2e + Option 2f

[0159] In some embodiments, the bits in each group are further grouped into M subgroups, where M is the maximum number of FD components selected among N selected TRP or CSI-RS resources. The mth subgroup is associated with an FD component and contains bits. When M n < M, the 2L n bits associated with the nth TRP or CSI-RS resource index only appear in the first M n groups. In Option 2e, the bits in each subgroup are further grouped into N subgroups, each subgroup containing 2L nbits, where all bits in the nth subgroup are associated with the same TRP or CSI-RS resource index. 2L n Each of the bits is associated with an SD component index. In option 2f, the n bits in each subgroup are further grouped into 2L subgroups, where L is the maximum number of SD components selected among the N selected TRPs or CSI-RS resources. When L n < L, the bits associated with the nth TRP or CSI-RS resource index only appear in the first 2L

[0160] groups. All bits in the lth subgroup are associated with the same SD component index. Each bit in the lth subgroup is associated with a TRP or CSI-RS resource index. n In some embodiments, the M subgroups are sorted in ascending order from left to right according to the FD index or the remapped FD index. In option 2e, the N subgroups are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. 2L

[0161] Grouping scheme 3:

[0162] In some embodiments, a bit field is grouped into M groups, where M is the maximum number of FD components selected among the N selected TRPs or CSI-RS resources. Each group is associated with the mth FD index and includes bits. When M n < M, the 2L n R n bits associated with the nth TRP or CSI-RS resource index only appear in the first M n groups. In some embodiments, the M groups are sorted in ascending order from left to right according to the FD index or the remapped FD index.

[0163] Option 3a + Option 3b <00007​​​​​​​​​n The bits are further grouped into 2L n sub - groups, each sub - group containing R n bits, and all the bits of the l n th sub - group are associated with the same SD component index. Each of the R n bits is associated with a layer index. In option 3b, the 2L n R n bits are further grouped into R n sub - groups, each sub - group containing 2L n bits, and all the bits of the r n th sub - group are associated with the same layer index. Each of the 2L n bits is associated with an SD component index.

[0165] In some embodiments, the M groups are sorted in ascending order from left to right according to the FD index or the remapped FD index. Each of the N sub - groups containing 2L n R n bits is sorted in ascending order from left to right according to the TRP or CSI - RS resource index or the remapped TRP or CSI - RS resource index. In option 3a, each of the R n bits in the 2L n sub - groups is sorted in ascending order from left to right according to the SD index or the remapped SD index. The R n bits in each sub - group are sorted in ascending order from left to right. In option 3b, each of the R n sub - groups containing 2L n bits is sorted in ascending order from left to right. The 2L n bits in each sub - group are sorted in ascending order from left to right according to the SD index or the remapped SD index.

[0166] Option 3c + Option 3d

[0167] In some embodiments, the bits in each group are further grouped into 2L sub - groups, where L is the maximum number of SD components selected among the N selected TRP or CSI - RS resources. The lth sub - group is associated with an SD component and contains bits. When L n < L, the R n bits associated with the nth TRP or CSI - RS resource index only appear in the first 2L n groups. In option 3c, the bits in each sub - group are further grouped into N sub - groups, each sub - group containing R n bits, where all the bits of the nth sub - group are associated with the same TRP or CSI - RS resource index. Rn Each bit in a number of bits is associated with a layer index. In Option 3d, the number of bits in each subgroup is further grouped into R subgroups, where R is the maximum supported rank value of N selected TRP or CSI-RS resources. When R n < R, the bits associated with the nth TRP or CSI-RS resource index only appear in the first R n groups. All bits in the rth subgroup are associated with the same layer index. Each bit in the rth subgroup is associated with a TRP or CSI-RS resource index.

[0168] In some embodiments, the 2L subgroups are sorted in ascending order from left to right according to the SD index or the remapped SD index. In Option 3c, each of the N subgroups containing R n bits is sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. The R n bits are sorted in ascending order from left to right. In Option 3d, the R subgroups are sorted in ascending order from left to right. The bits in the rth subgroup are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index.

[0169] Option 3e + Option 3f

[0170] In some embodiments, the number of bits in each group is further grouped into R subgroups, where R is the maximum supported rank value of N selected TRP or CSI-RS resources. The rth subgroup is associated with a layer index and contains number of bits. When R n < R, the 2L n bits associated with the nth TRP or CSI-RS resource index only appear in the first R n groups. In Option 3e, the number of bits in each subgroup is further grouped into N subgroups, each subgroup containing 2L n bits, where all bits in the nth subgroup are associated with the same TRP or CSI-RS resource index. Each of the 2L n bits is associated with an SD component index. In Option 3f, the number of bits in each subgroup is further grouped into 2L subgroups, where L is the maximum number of SD components selected from N selected TRP or CSI-RS resources. When L n < L, the bits associated with the nth TRP or CSI-RS resource index only appear in the first 2L nIn a group. All bits in the l-th subgroup are associated with the same SD component index. Each bit in the l-th subgroup is associated with a TRP or CSI-RS resource index.

[0171] In some embodiments, the R subgroups are sorted in ascending order from left to right. In option 3e, each of the N subgroups containing n are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. The 2L

[0172] Grouping scheme 4:

[0173] In some embodiments, a bit field is grouped into 2L groups, where L is the maximum number of SD components selected from among N selected TRP or CSI-RS resources. Each group is associated with the l-th SD index and includes bits. When L n < L, the M n R n bits associated with the n-th TRP or CSI-RS resource index only appear in the first 2L n [[ID=z5]]groups.

[0174] [[ID=za]]In some embodiments, the 2L groups are sorted in ascending order from left to right according to the SD index or the remapped SD index.

[0175] Option 4a + Option 4b

[0176] In some embodiments, the bits in each group are further grouped into N subgroups, each subgroup containing M n R n bits, where the n-th subgroup is associated with the TRP or CSI-RS resource index. In option 4a, the M n R n bits are further grouped into M [[ID=aa]] n subgroups, each subgroup containing R n bits, and all bits in the m n -th subgroup are associated with the same FD component index. Each of the R n bits is associated with a layer index. In option 4b, the M n R n bits are further grouped into Rn a subgroup, each subgroup containing M n bits, and all bits of the r n -th subgroup are associated with the same layer index. Each of the M n bits is associated with an FD component index.

[0177] In some embodiments, each of the N subgroups containing M n R n bits is sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. In option 4a, each of the M n subgroups containing R n bits is sorted in ascending order from left to right according to the FD index or the remapped FD index. The R n bits in each subgroup are sorted in ascending order from left to right. In option 4b, each of the R n subgroups containing M n bits is sorted in ascending order from left to right. The M n bits in each subgroup are sorted in ascending order from left to right according to the FD index or the remapped FD index.

[0178] Option 4c + Option 4d

[0179] In some embodiments, the bits in each group are further grouped into M subgroups, where M is the maximum number of FD components selected among the N selected TRP or CSI-RS resources. The m-th subgroup is associated with an FD component and contains bits. When M n < M, the R n bits associated with the n-th TRP or CSI-RS resource index only appear in the first M n groups. In option 4c, the bits in each subgroup are further grouped into N subgroups, each subgroup containing R n bits, and all bits of the n-th subgroup are associated with the same TRP or CSI-RS resource index. Each of the R n bits is associated with a layer index. In option 4d, the bits in each subgroup are further grouped into R subgroups, where R is the maximum supported rank value among the N selected TRP or CSI-RS resources. When R n < R, the bits associated with the n-th TRP or CSI-RS resource index only appear in the first R n groups. All bits in the r-th subgroup are associated with the same layer index. Each bit in the r-th subgroup is associated with a TRP or CSI-RS resource index.

[0180] In some embodiments, the M subgroups are sorted in ascending order from left to right according to the FD index or the remapped FD index. In option 4c, each of the N subgroups containing R n bits is sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. The R n bits are sorted in ascending order from left to right. In option 4d, the R subgroups are sorted in ascending order from left to right. The bits in the r-th subgroup are sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index.

[0181] Option 4e + Option 4f

[0182] In some embodiments, the bits in each group are further grouped into R subgroups, where R is the maximum supported rank value among the N selected TRP or CSI-RS resources. The r-th subgroup is associated with a layer index and contains bits. When R n < R, the M n bits associated with the n-th TRP or CSI-RS resource index only appear in the first R n groups. In option 4e, the bits in each subgroup are further grouped into N subgroups, each subgroup containing M n bits, where all the bits in the n-th subgroup are associated with the same TRP or CSI-RS resource index. Each of the M n bits is associated with an FD component index. In option 4f, the bits in each subgroup are further grouped into M subgroups, where M is the maximum number of FD components selected among the N selected TRP or CSI-RS resources. When M [[ID=3i]] n < M, the bits associated with the n-th TRP or CSI-RS resource index only appear in the first M n groups. All the bits in the m-th subgroup are associated with the same FD component index. Each bit in the m-th subgroup is associated with a TRP or CSI-RS resource index.

[0183] In some embodiments, the R subgroups are sorted in ascending order from left to right. In option 4e, each of the N subgroups containing is sorted in ascending order from left to right according to the TRP or CSI-RS resource index or the remapped TRP or CSI-RS resource index. M nThe bits are sorted in ascending order from left to right by FD index or remapped FD index. In option 4f, the M subgroups are sorted in ascending order from left to right by FD index or remapped FD index. The bits in each subgroup are sorted in ascending order from left to right by TRP or CSI-RS resource index or remapped TRP or CSI-RS resource index.

[0184] SD index mapping

[0185] In some embodiments, the L SD components are sorted in ascending order from left to right and mapped to SD indices l=0, ..., L n -1 and l = L n ,…,2L n -1, l=0,…,L n -1 and l = L n ,…,2L n -1 is associated with the first polarization and the second polarization of the antenna port, respectively. In some examples, the selected L=4 SD components are {2, 5, 7, 11}, SD component 2 is mapped to SD indices 0 and 4, SD component 5 is mapped to SD indices 1 and 5, SD component 7 is mapped to SD indices 2 and 6, and SD component 11 is mapped to SD indices 3 and 7.

[0186] In some embodiments, the combining coefficients associated with bits in the bitmap (the bits are associated with the strongest SD components) are placed in CSI group 1. The strongest SD component is the SD component associated with the strongest coefficient.

[0187] In some embodiments, the SD index is l′ n =mod(l n -l SCI ,2L n ) or mod(l SCI -l,2L n ), where l′ n is the remapped SD index, and l SCI is the SD index associated with the strongest coefficient of the precoding matrix for the nth selected TRP or CSI-RS resource index.

[0188] In some embodiments, the SD index l′ n =0,…,2L n -1 is sorted in ascending order from left to right by the nth selected TRP or CSI-RS resource index. In some examples, when L=2, SD component 2 is mapped to SD indices 0 and 2, and SD component 5 is mapped to SD indices 1 and 3, and the strongest coefficient is associated with SD component 2 of the second polarization, i.e., l SCI= 2. After remapping, the new order of SD indices is l′0 = {2, 3, 0, 1}, where remapping index 0 is associated with the strongest coefficient (ie, SD component 2 of the second polarization).

[0189] In some examples, when L=2, SD component 2 is mapped to SD indices 0 and 2, and SD component 5 is mapped to SD indices 1 and 3, and the strongest coefficient is associated with SD component 2 of the second polarization, i.e., l SCI = 2. After remapping, the new order is l′0 = {2, 1, 0, 3}, where the remapped SD index 0 is associated with the strongest coefficient (ie, SD component 2 of the second polarization).

[0190] In some embodiments, SD Index 1 n =l SCI and l n = l0 is remapped so that the remapped SD indices are l′ n = 0 and l′ n = 10, and the remaining SD indices are sorted in natural order.

[0191] In some examples, when L=2, SD component 2 is mapped to SD indices 0 and 2, and SD component 5 is mapped to SD indices 1 and 3, and the strongest coefficient is associated with SD component 2 of the second polarization, i.e., l SCI = 2. Remap SD index l n =2 and l n =0, the remapping order is {2,1,0,3}, where remapping SD index 0 is associated with the strongest coefficient (i.e., SD component 2 of the second polarization), and remapping index 2 is associated with SD component 2 of the first polarization of the antenna or CSI-RS port.

[0192] In some embodiments, the permutation is performed only on a subset of layers, or a subset of TRPs, or a subset of CSI-RS resources. In some examples, permutation of SD and / or FD indexes: the permutation is performed per layer and per TRP. In some examples, the permutation of SD and / or FD indexes is performed only on the first layer and per TRP. In some examples, the permutation of SD and / or FD indexes is performed only on the first layer and the strongest TRP, where the strongest TRP is the associated TRP with the largest coefficient. In some examples, the permutation of SD and / or FD indexes is performed only on all layers and the strongest TRP, where the strongest TRP is the associated TRP with the largest coefficient.

[0193] In some embodiments, the M FD components are sorted in ascending order from left to right and mapped to FD index m n =0,…,M nIn some examples, the selected M=4 SD components are {2, 3, 6, 7}, and FD component 2 is mapped to FD index 0, FD component 3 is mapped to FD index 1, FD component 6 is mapped to FD index 2, and FD component 7 is mapped to FD index 3.

[0194] FD index mapping

[0195] In some embodiments, the combining coefficients associated with bits in the bitmap (the bits are associated with the strongest FD components) are placed in CSI Group 1. The strongest FD component is the FD component associated with the strongest coefficient.

[0196] In some embodiments, the FD index is m′ n =mod(m n -m SCI ,M n ) or mod(m SCI -m,M n ), where m′ n is the remap FD index, and m SCI is the FD index associated with the strongest coefficient of the precoding matrix for the nth selected TRP or CSI-RS resource index.

[0197] In some embodiments, the FD index m′ n =0,…,M n -1 is sorted in ascending order from left to right by the nth selected TRP or CSI-RS resource index. In some examples, when M=2, FD component 2 is mapped to FD indexes 0 and 2, and FD component 2 is mapped to FD index 1, and the strongest coefficient is associated with FD component 3, that is, m SCI = 1. After remapping, the new order of FD indices is m′0 = {1, 0}, where remap index 0 is associated with the strongest coefficient (ie, FD component 3).

[0198] In some examples, when M=2, FD component 2 is mapped to FD index 0, and FD component 3 is mapped to FD index 1, and the strongest coefficient is associated with FD component 3, i.e., m SCI = 1. After remapping, the new order is m′0 = {1, 0}, where remapped FD index 0 is associated with the strongest coefficient (ie, FD component 3).

[0199] In some embodiments, the FD index m n =m SCI and m n =m0 is remapped so that the permuted FD indices are m′ n = 0 and m′ n =m0, and the remaining FD indices are sorted in natural order.

[0200] TRP or CSI-RS resource index mapping

[0201] In some embodiments, the N selected TRPs or CSI-RS resources are sorted in ascending order from left to right and mapped to TRPs or CSI-RS resources n = 0, ..., N - 1. In some examples, for N = 4 TRPs or CSI-RS resources, TRP 0 is mapped to TRP or CSI resource index 0, TRP 1 is mapped to TRP or CSI resource 1, TRP 2 is mapped to TRP or CSI resource index 2, and TRP 3 is mapped to TRP or CSI resource index 3.

[0202] In some examples, the numbering of the TRPs is based on the numbering of the configured N TRPs or CSI-RS resources.

[0203] In some examples, the numbering of the TRPs is based on the numbering of the configured N TRPs or CSI-RS resources indicated in the CSI reporting configuration.

[0204] In some embodiments, the TRP or CSI-RS resource index is n′=mod(nn SCI ,N) or mod(n SCI -n,N), where n′ is the remapped SD index, and n SCI is the TRP index associated with the strongest coefficient of the precoding matrix for the nth selected TRP or CSI-RS resource index.

[0205] In some embodiments, the TRP index n′=0,…,N-1 is sorted in ascending order from left to right by the nth selected TRP or CSI-RS resource index. In some examples, when N=2, TRP or CSI resource 0 is mapped to TRP or CSI resource 0, and TRP or CSI resource 1 is mapped to TRP or CSI resource 1, and the strongest coefficient is associated with TRP or CSI resource 1, i.e., n SCI = 1. After remapping, the new order of TRP or CSI resources is n′={1,0}, where remapping index 0 is associated with the strongest TRP or CSI resource (i.e., TRP or CSI resource 1).

[0206] In some embodiments, TRP or CSI resource index n=n SCI and n=0 are remapped so that the remapped TRP or CSI resource indices are n′=0 and n′=n SCI .

[0207] In some embodiments, the N selected TRPs are mapped one-to-one to a TRP index n, where n={0, ..., N TRP -1}, where TRPs are sorted from left to right according to the total power constraints of non-zero combining coefficients from large to small.

[0208] In some examples, when N=4, the order of TRPs in descending power is {1, 3, 0, 2}, TRP 1 maps to TRP index 0, TRP 3 maps to TRP index 1, TRP 0 maps to TRP index 2, and TRP 2 maps to TRP index 3.

[0209] In some embodiments, the N selected TRPs are mapped one-to-one to TRP index n, n={0,…,N-1}, where the TRP associated with the strongest coefficient corresponds to TRP index 0.

[0210] In some embodiments, the wireless device is configured to report the ranking of N selected TRPs or CSI-RS resources in a CSI report, wherein the ranking of the TRPs is based on ascending or descending power.

[0211] Bit segmentation of the bitmap in the CSI report

[0212] In some embodiments, the bits of the bitmap are divided into two segments, where the first segment contains the first bits and are assigned to CSI group 1, and the second segment contains the remaining bits and is allocated to CSI group 2. Here, K represents the number of non-zero combining coefficients of the precoding matrix.

[0213] Splitting of non-zero coefficients in CSI reports

[0214] In some embodiments, in a CSI report, the amplitude values ​​or differential amplitude values ​​of K or fewer non-zero combined coefficients are quantized using A bits of common amplitude and B bits of differential amplitude. For example, in this case, each amplitude coefficient of the non-zero coefficient is represented by the product of a reference or common amplitude coefficient and a differential amplitude coefficient.

[0215] In some embodiments, the total number of bits associated with the phase and amplitude (or differential amplitude values) of K or fewer non-zero combining coefficients is divided into two segments, where the first segment is allocated to CSI group 1 and the second segment is allocated to CSI group 2.

[0216] In some embodiments, in a CSI report, the phase values ​​of K or fewer non-zero combining coefficients are quantized using C bits.

[0217] In some embodiments, the total number of bits used to quantize the differential magnitudes of K or fewer non-zero combining coefficients is divided into two or more segments and allocated to two or more CSI groups.

[0218] In some embodiments, the total number of bits associated with the differential magnitudes of K or fewer non-zero combining coefficients is divided into two segments, where the first segment includes at most bits and are assigned to CSI group 1, and the second segment includes at most bits and are allocated to CSI group 2.

[0219] In some embodiments, the total number of bits associated with a phase having K or fewer non-zero combining coefficients is divided into two segments, where the first segment includes at most bits and are assigned to CSI group 1, and the second segment includes at most bits and are allocated to CSI group 2.

[0220] In some embodiments, the total number of bits associated with the differential magnitudes of K or fewer non-zero combining coefficients is divided into two segments, where the first segment includes at most bits and are assigned to CSI group 1, and the second segment includes at most bits and are allocated to CSI group 2.

[0221] In some embodiments, the total number of bits associated with a phase having K or fewer non-zero combining coefficients is segmented into two segments, where the first segment includes at most bits and are assigned to CSI group 1, and the second segment includes at most bits and are allocated to CSI group 2.

[0222] refer to Figure 4 , a method performed by a wireless device according to some of the aforementioned embodiments is described. The method is performed by a wireless device (or UE) to generate and report or transmit a CSI report, wherein the CSI report includes a precoding matrix, wherein the precoding matrix is ​​represented as a linear combination of spatial domain components and frequency domain components, and the method includes:

[0223] - receiving (400) a CSI reporting configuration from a network node;

[0224] - based on the received CSI reporting configuration, determining (401) a set of linear combining coefficients of a precoding matrix for a plurality of CSI-RS resources; wherein the set of linear combining coefficients comprises a plurality of non-zero combining coefficients, and wherein the CSI-RS resources are indicated in the CSI reporting configuration;

[0225] - determining (402) a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by means of bits or by means of bits, and assigning an ordering to the bits of the bitmap and assigning an ordering to be associated with the bits in the CSI report Figure 1 Assign the same ranking as the multiple non-zero combining coefficients reported to the network node;

[0226] - dividing (403) the plurality of non-zero combining coefficients into two or more CSI groups having associated priority levels;

[0227] - generating (404) a CSI report, the CSI report comprising an indication of the spatial domain component and the frequency domain component, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating a payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients of at least one of the two or more CSI groups; and

[0228] - transmitting (405) or reporting uplink control information (UCI) including said CSI report to said network node on an uplink UL channel.

[0229] In order to perform the aforementioned procedures or method steps performed by a wireless device or UE, a wireless device is also provided. Figure 6 A simplified block diagram depicting a wireless device or UE 500 is illustrated. Wireless device 500 includes a processor 510 or processing circuitry or processing module or processor component 510; receiver circuitry or receiver module 540; transmitter circuitry or transmitter module 550; a memory module 520; and transceiver circuitry or transceiver module 530, which may include transmitter circuitry 550 and receiver circuitry 540. Wireless device 500 also includes an antenna system 560, which includes antenna circuitry for transmitting and receiving signals to and from at least a network node or other wireless device. The antenna system employs the beamforming techniques described above.

[0230] The wireless device 500 may be of any radio access technology that supports beamforming technology, including 4G or LTE, LTE-A, 5G, Advanced 5G, or a combination thereof. The wireless device includes a processor and a memory, wherein the memory contains instructions executable by the processor, so that the wireless device 500 is operable or configured to perform any of the aforementioned embodiments related to wireless devices.

[0231] The processing module / circuitry 510 includes a processor, a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc., and the processing module / circuitry 510 may be referred to as a "processor." The processor 510 controls the operation of the wireless device and its components. The memory (circuitry or module) 520 includes random access memory (RAM), read-only memory (ROM), and / or other types of memory to store data and instructions that may be used by the processor 510. In general, it will be understood that in one or more embodiments, the wireless device 500 includes fixed or programmable circuitry configured to perform the operations of any of the embodiments disclosed herein.

[0232] In at least one such example, the processor 510 comprises a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry configured to execute computer program instructions from a computer program stored on a non-transitory computer-readable medium located within or accessible to the processing circuitry. Here, "non-transitory" does not necessarily imply permanent or unchanging storage and can include storage in working or volatile memory, but the term does imply storage with at least some persistence. Execution of the program instructions specifically adapts or configures the processing circuitry to perform the operations described herein in connection with the wireless device. Furthermore, it will be appreciated that the wireless device 500 may include other components.

[0233] The wireless device 500 executes instructions contained in the memory 520 via the processor 510, enabling the wireless device to perform any of the embodiments described above with respect to actions performed by the wireless device, some of which appear in the appended claims.

[0234] A computer program is also provided, comprising instructions which, when executed by the processor 510 of a wireless device, cause the processor 510 to perform a method according to any one of the above-described embodiments.

[0235] refer to Figure 5 , illustrates a method performed by a network node 600 according to some of the aforementioned embodiments. The method performed by the network device 600 is used to receive a CSI report from a wireless device 500, wherein the CSI report indication is represented as a linear combination of a spatial domain SD component and a frequency domain FD component and a set of linear combination coefficients for combining the spatial component and the frequency domain component. Figure 5 The main method steps are described, which include:

[0236] - transmitting (501) a CSI reporting configuration to the wireless device, so as to enable the wireless device to:

[0237] - determining, based on the received CSI reporting configuration, a set of linear combining coefficients of a precoding matrix for a plurality of CSI reference signal (CSI-RS) resources, wherein the set of linear combining coefficients comprises a plurality of non-zero combining coefficients, and the CSI-RS resources are indicated in the CSI reporting configuration;

[0238] - determining a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by means of bits or by means of bits;

[0239] - assigning an order to the bits of the bitmap and assigning an order to the bits to be used in the CSI report Figure 1 Assign the same ranking as the multiple non-zero combining coefficients reported to the network node;

[0240] -dividing the plurality of non-zero combining coefficients into two or more CSI groups with associated priority levels;

[0241] - generating a CSI report to be transmitted to the network node, the CSI report comprising an indication of the spatial domain component and the frequency domain component, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients for at least one of the two or more CSI groups; and

[0242] - receiving (502) uplink control information (UCI) including the CSI report on an uplink (UL) channel from the wireless device.

[0243] In order to perform the above-mentioned process or method steps performed by the network node, a network node is also provided. Figure 7 A block diagram depicting a network node 600 is illustrated. Network node 600 includes a processor 610 or processing circuitry or processing module or processor element 610; receiver circuitry or receiver module 640; transmitter circuitry or transmitter module 650; a memory module 620; and transceiver circuitry or transceiver module 630, which may include transmitter circuitry 650 and receiver circuitry 640. Network node 600 also includes an antenna system 660, which includes antenna circuitry for transmitting signals to and receiving signals from at least a wireless device. The antenna system employs the beamforming techniques described above.

[0244] The network node 600 may be of any radio access technology that supports beamforming technology, including 4G or LTE, LTE-A, 5G, Advanced 5G, or a combination thereof. The network device includes a processor and a memory, wherein the memory contains instructions executable by the processor, so that the network node 600 is operable or configured to perform any of the embodiments related to the network node 600 as described above.

[0245] The processing module / circuit 610 includes a processor, a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc., and the processing module / circuit 610 may be referred to as a "processor". The processor 610 controls the operation of the network node and its components. The memory (circuit or module) 620 includes a random access memory (RAM), a read-only memory (ROM), and / or other types of memory to store data and instructions that may be used by the processor 610. In general, it will be understood that in one or more embodiments, the network node includes fixed or programmable circuits that are configured to perform the operations of any embodiment disclosed herein.

[0246] In at least one such example, the processor 610 includes a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry configured to execute computer program instructions from a computer program stored in a non-transitory computer-readable medium that is within or accessible to the processing circuitry. Here, "non-transitory" does not necessarily mean permanent or unchanging storage and can include storage in working or volatile memory, but the term does mean storage that has at least some persistence. The execution of the program instructions specifically adapts the processing circuitry or configures the processing circuitry to perform the operations associated with the network node of the present disclosure. In addition, it will be understood that the network node 600 may include other components. The network node 600 may also be considered a transmitter and receiver point (TRP).

[0247] The network node 600 executes instructions contained in the memory 620 via the processor 610, so that the network node 600 is able to perform any of the embodiments described above in relation to actions performed by the network node, some of which appear in the appended claim 2.

[0248] A computer program is also provided, comprising instructions which, when executed by a processor 610 of a network node, cause the processor 610 to perform a method according to any one of the embodiments of claim 2.

[0249] As previously mentioned, the embodiments described in this disclosure achieve several advantages, including significantly reducing the feedback overhead and computational complexity of wireless devices in codebook-based CSI reporting. Another advantage is reduced latency in CSI reporting.

[0250] Throughout this specification, references to "one example" or "exemplary" mean that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in one example" or "exemplary" throughout this specification are not necessarily all referring to the same embodiment.

[0251] In this disclosure, the terms "including" or "comprising" are used in a non-limiting sense, meaning "consisting at least of..." Although specific terms may be used herein, they are used in a generic and descriptive sense only and not for purposes of limitation. The embodiments herein may be applied to any wireless system, including LTE or 4G, LTE-A (or LTE-Advanced), 5G, Advanced 5G, WiMAX, WiFi, satellite communications, television broadcasting, etc.

Claims

1. A method performed by a wireless device (500) for generating and reporting or transmitting a channel state information (CSI) report in a wireless communication system, wherein the CSI report includes a precoding matrix, wherein the precoding matrix is ​​represented as a linear combination of a spatial domain component and a frequency domain component, the method comprising: o receiving (400) a CSI reporting configuration from a network node; o determining (401) a set of linear combining coefficients of a precoding matrix for a plurality of CSI reference signal CSI-RS resources based on the received CSI reporting configuration; wherein the set of linear combining coefficients includes a plurality of non-zero combining coefficients, and wherein the CSI-RS resource is indicated in the CSI reporting configuration; o determining (402) a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by or with the aid of bits, assigning an order to the bits of the bitmap, and assigning the same order to the plurality of non-zero combining coefficients to be reported to the network node together with the bitmap in a CSI report; o dividing (403) the plurality of non-zero combining coefficients into two or more CSI groups having associated priority levels; o generating (404) a CSI report, the CSI report comprising indications of spatial domain components and frequency domain components, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating a payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients for at least one of the two or more CSI groups; as well as o transmitting (405) or reporting uplink control information UCI including the CSI report to the network node (600) on an uplink UL channel.

2. A method performed by a network node (600) for receiving a channel state information (CSI) report from a wireless device (500) in a wireless communication system, the CSI report indicating a precoding matrix, the precoding matrix being represented as a linear combination of a spatial domain component and a frequency domain component, the method comprising: A CSI reporting configuration is transmitted (501) to the wireless device (500) to enable the wireless device (500) to: - determining a set of linear combining coefficients of a precoding matrix for a plurality of CSI reference signal (CSI-RS) resources based on the received CSI reporting configuration; wherein the set of linear combining coefficients includes a plurality of non-zero combining coefficients, and the CSI-RS resource is indicated in the CSI reporting configuration; - determining a bitmap for indicating the plurality of non-zero combining coefficients in the set of linear combining coefficients by means of bits or by means of bits; - assigning an order to the bits of the bitmap and assigning the same order to a plurality of non-zero combining coefficients to be reported to the network node together with the bitmap in a CSI report; -dividing the plurality of non-zero combining coefficients into two or more CSI groups having associated priority levels; - generating a CSI report to be transmitted to the network node (600), the CSI report comprising indications of spatial domain components and frequency domain components, the determined bitmap, and the non-zero combining coefficients, wherein the CSI report comprises a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the payload size of the CSI part 2, and wherein the CSI part 2 comprises the non-zero combining coefficients of at least one of the two or more CSI groups; as well as Uplink control information (UCI) including the CSI report is received (502) from the wireless device (500) on an uplink (UL) channel.

3. A network node (600) comprising a processor (610) and a memory (620), the memory (620) containing instructions executable by the processor (610), whereby the network node (600) is capable of performing the method of claim 2.

4. A wireless device (500) comprising a processor (510) and a memory (520), the memory (520) containing instructions executable by the processor (510), whereby the wireless device (500) is capable of performing the method of claim 1.

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