Method and apparatus for CSI reporting

Abstract

The invention relates to a method and apparatus for channel state information (CSI) reporting. An embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver that: receives a codebook configuration for channel state information reference signal (CSI-RS) reports associated with a plurality of CSI-RS resources; and transmitting a CSI report based on the codebook configuration, and a processor coupled with the transceiver.

Description

Technical Field

[0001] The present disclosure relates to wireless communications, and in particular, to methods and apparatus for channel state information (CSI) reporting. Background Art

[0002] The continued evolution of Multiple Input Multiple Output (MIMO) is perhaps the most important part of the physical layer of the 3rd Generation Partnership Project (3GPP). It is important to identify and specify the necessary enhancements for both downlink and uplink MIMO to facilitate the use of large antenna arrays, not only for frequency range 1 (FR1), but also for FR2 to meet the evolving requirements of New Radio (NR) deployments in Rel-18.

[0003] As coherent joint transmission (CJT) improves coverage and average throughput in commercial deployments with high-performance backhaul and synchronization, CSI acquisition enhancements for frequency division duplex (FDD) and time division duplex (TDD) targeting FR1 can help expand the effectiveness of multiple transmit or receive points (TRP) deployments.

[0004] Therefore, it is advantageous to provide a method and apparatus for CSI reporting in a CJT scenario. Summary of the invention

[0005] An embodiment of the present disclosure provides a user equipment (UE), comprising: a transceiver, which: receives a codebook configuration of a CSI report associated with a plurality of channel state information reference signal (CSI-RS) resources; and transmits the CSI report based on the codebook configuration; and a processor, which is coupled to the transceiver.

[0006] In some embodiments, the codebook configuration includes at least one first parameter, and each first parameter indicates a codebook subset restriction of a number pair consisting of: a first number of antenna ports in a first dimension; and a second number of antenna ports in a second dimension; wherein each of the at least one first parameter is associated with one of the multiple CSI-RS resources; or wherein in the case where only one first parameter is included in the codebook configuration, the first parameter is associated with the multiple CSI-RS resources.

[0007] In some embodiments, the restriction values ​​of the first number and the second number included in the codebook subset restriction are determined based on the total number of the plurality of CSI-RS resources, the capability of the UE, or both.

[0008] In some embodiments, the transceiver further transmits the capabilities of the UE to a base station (BS), wherein the capabilities of the UE include one of: the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports per CSI-RS resource; the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports across CSI-RS resources; or the supported maximum number of CSI-RS ports across CSI-RS resources.

[0009] In some embodiments, the supported maximum number of CSI-RS ports across a CSI-RS resource comprises a value selected from a set comprising at least one of 8, 12, 16, 24, 32, or 64.

[0010] In some embodiments, the codebook configuration further indicates a same pair of values ​​for the number pair for each of the plurality of CSI-RS resources.

[0011] In some embodiments, the codebook configuration includes at least one second parameter, and each second parameter indicates a combination of: the number of selected beams L; a factor β; and a frequency compression ratio p v ; wherein each of the at least one second parameter is associated with one of the plurality of CSI-RS resources; or wherein in the case where only one second parameter is included in the codebook configuration, the second parameter is associated with the plurality of CSI-RS resources.

[0012] In some embodiments, the number of selected beams is 2 or 4 when the number of selected beams is configured per CSI-RS resource, or is 4, 5, 6, 7 or 8 when the number of selected beams is configured across the multiple CSI-RS resources.

[0013] In some embodiments, when the multiple CSI-RS resources include more than two CSI-RS resources, the factor is a value less than 1 / 4.

[0014] In some embodiments, the CSI report includes a number of non-zero coefficients, and the processor determines at least one of the following based on the codebook configuration: a maximum number of non-zero coefficients per layer per CSI-RS resource; a maximum number of non-zero coefficients across layers per CSI-RS resource; a maximum number of non-zero coefficients per layer across CSI-RS resources; or a maximum number of non-zero coefficients across layers across CSI-RS resources.

[0015] In some embodiments, in the codebook configuration, the maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be And the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be 2K0.

[0016] In some embodiments, across the CSI-RS resource configuration factor β, the number of selected beams L, and the number of bases M1 in the frequency domain in the codebook configuration, the maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be And the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be 2K0, where N is the total number of the multiple CSI-RS resources.

[0017] In some embodiments, when the factor β, the number of selected beams L, and the number of bases M1 in the frequency domain are configured per CSI-RS resource in the codebook configuration, for each CSI-RS resource, the processor determines a value The maximum number of non-zero coefficients for each layer across CSI-RS resources is determined to be x_k1×K0′, and the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2x_k1×K0, where x_k1 is a predefined coefficient or a configured coefficient, and K0′ is the maximum value or average of all the determined values ​​K0.

[0018] In some embodiments, in the codebook configuration across the CSI-RS resource configuration factor β, the number of selected beams L, and the number of bases M1 in the frequency domain, the maximum number of non-zero coefficients across each layer of CSI-RS resources is determined to be And the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2K0.

[0019] In some embodiments, the codebook configuration further indicates a same rank restriction for each of the plurality of CSI-RS resources.

[0020] Another embodiment of the present disclosure provides a BS, comprising: a transceiver, which: transmits a codebook configuration of a CSI report associated with a plurality of CSI-RS resources; and receives a CSI report based on the codebook configuration; and a processor coupled to the transceiver.

[0021] In some embodiments, the codebook configuration includes at least one first parameter, and each first parameter indicates a codebook subset restriction of a number pair consisting of: a first number of antenna ports in a first dimension; and a second number of antenna ports in a second dimension; wherein each of the at least one first parameter is associated with one of the multiple CSI-RS resources; or wherein in the case where only one first parameter is included in the codebook configuration, the first parameter is associated with the multiple CSI-RS resources.

[0022] In some embodiments, the restriction values ​​of the first number and the second number included in the codebook subset restriction are determined based on the total number of the plurality of CSI-RS resources, the capability of the UE, or both.

[0023] In some embodiments, the transceiver further receives capabilities of the UE from the UE, wherein the capabilities of the UE include one of: the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports per CSI-RS resource; the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports across CSI-RS resources; or the supported maximum number of CSI-RS ports across CSI-RS resources.

[0024] In some embodiments, the supported maximum number of CSI-RS ports across a CSI-RS resource comprises a value selected from a set comprising at least one of 8, 12, 16, 24, 32, or 64.

[0025] In some embodiments, the codebook configuration further indicates a same pair of values ​​for the number pair for each of the plurality of CSI-RS resources.

[0026] In some embodiments, the codebook configuration includes at least one second parameter, and each second parameter indicates a combination of: the number of selected beams L; a factor β; and a frequency compression ratio p v ; wherein each of the at least one second parameter is associated with one of the plurality of CSI-RS resources; or wherein in the case where only one second parameter is included in the codebook configuration, the second parameter is associated with the plurality of CSI-RS resources.

[0027] In some embodiments, the number of selected beams is 2 or 4 when the number of selected beams is configured per CSI-RS resource, or is 4, 5, 6, 7 or 8 when the number of selected beams is configured across the multiple CSI-RS resources.

[0028] In some embodiments, when the multiple CSI-RS resources include more than two CSI-RS resources, the factor is a value less than 1 / 4.

[0029] In some embodiments, the codebook configuration further indicates a same rank restriction for each of the plurality of CSI-RS resources.

[0030] Yet another embodiment of the present disclosure provides a method performed by a UE, comprising: receiving a codebook configuration of a CSI report associated with a plurality of CSI-RS resources; and transmitting the CSI report based on the codebook configuration.

[0031] Yet another embodiment of the present disclosure provides a method performed by a BS, comprising: transmitting a codebook configuration of a CSI report associated with a plurality of CSI-RS resources; and receiving a CSI report based on the codebook configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered to limit its scope.

[0033] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present disclosure.

[0034] Figure 2 A flow chart illustrating an exemplary method for CSI reporting performed by a UE according to some embodiments of the present disclosure.

[0035] Figure 3 A flow chart illustrating an exemplary method for CSI reporting performed by a BS according to some embodiments of the present disclosure.

[0036] Figure 4 A simplified block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0037] The detailed description of the accompanying drawings is intended as a description of the currently preferred embodiments of the present invention and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be accomplished by different embodiments that are intended to be included in the spirit and scope of the present invention.

[0038] Although the operations are depicted in a particular order in the figures, those skilled in the art will readily recognize that such operations need not be performed in the particular order shown or in sequential order or require all of the illustrated operations to be performed in order to achieve the desired result; sometimes, one or more operations may be skipped. In addition, the figures may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous.

[0039] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), 3GPP 4G, 3GPP 5GNR, 3GPP Release 16 and above, etc.). It is considered that with the development of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and in addition, the terms cited in the present disclosure may be changed, which should not affect the principles of the present disclosure.

[0040] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application.

[0041] refer to Figure 1 , the wireless communication system may include BS101, several TRPs (e.g., TRP 103-1, TRP 103-2, ..., TRP 103-N) and UE 105. Although only one BS101, three TRPs and one UE 105 are shown for simplicity, it should be noted that according to some other embodiments of the present application, the wireless communication system may include more or fewer communication devices, apparatuses or nodes.

[0042] The wireless communication system is compatible with any type of network capable of sending and receiving wireless communication signals. For example, the wireless communication system is compatible with wireless communication networks, cellular telephone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3GPP-based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and / or other communication networks.

[0043] BS 101 may also be referred to as an access point, an access terminal, a base, a macro cell, a Node B, an enhanced Node B (eNB), a gNB, a home Node B, a relay node or a device, or described using other terms used in the art. BS 101 is typically part of a radio access network that may include a controller communicatively coupled to BS 101.

[0044] The TRPs may communicate with BS 101 via, for example, a backhaul link. Each of the TRPs may serve one or more UEs. Figure 1 103-1 may serve some mobile stations (including UE 105) within a service area or region (e.g., a cell or cell sector), TRP 103-2 may serve some mobile stations (including UE 105) within a service area or region (e.g., a cell or cell sector), and TRP 103-N may serve some mobile stations (including UE 105) within a service area or region (e.g., a cell or cell sector). In some embodiments, TRP 103-1, TRP 103-2, and TRP 103-N may serve different UEs. The TRPs may be connected to each other via, for example, a backhaul link ( Figure 1 ) communicate with each other.

[0045] UE 105 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a car computer, a network device (e.g., a router, a switch, and a modem), or the like. According to some embodiments of the present disclosure, UE 105 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals on a wireless network. In some embodiments of the present disclosure, UE 105 may include a wearable device, such as a smart watch, a fitness bracelet, an optical head-mounted display, or the like. In addition, UE 105 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terms used in the art.

[0046] In some embodiments of the present application, a TRP (e.g., TRP 103-1, TRP 103-2, ..., TRP 103-N) may perform CJT with UE 105. All TRPs involved in the CJT may have the same antenna configuration but be at different locations. In CJT, each TRP may transmit the same data to UE 105. Each TRP may be configured and transmitted with CSI-RS resources for channel measurement with the same number of antenna ports. In other words, one TRP may correspond to one CSI-RS resource. Therefore, in the present disclosure, the expressions "per TRP" and "per CSI-RS resource" may be used interchangeably, the expressions "across TRPs" and "across CSI-RS resources" may be used interchangeably, and the like.

[0047] For Rel.16 enhanced type II codebook, the codebook configuration and CSI reporting scheme associated with a TRP are specified in the 3GPP document, such as TS38.214.

[0048] Specifically, the codebook configuration may include a parameter (e.g., n1-n2-codebookSubsetRestriction-r16) indicating a codebook subset restriction of a number of pairs consisting of N1 and N2. The supported configurations of (N1, N2) and the corresponding values ​​of (O1, O2) for a given number of CSI-RS ports are described in Table 5.2.2.2.1-2 in TS38.214, and the number of CSI-RS ports P CSI-RS It is 2N1N2. Table 5.2.2.2.1-2 in TS38.214 is reproduced below.

[0049] Table 5.2.2.2.1-2: Supported configurations for (N1, N2) and (O1, O2)

[0050]

[0051] The codebook configuration may also include the number of beams selected by TRP (denoted as L), the factor (denoted as β), and the frequency compression ratio (denoted as p v ) (e.g., paramCombination-r16). The values ​​of the parameters are described in Table 5.2.2.2.5-1 in TS38.214, which is reproduced below.

[0052] Table 5.2.2.2.5-1: L, β and p υ Codebook parameter configuration

[0053]

[0054] In the above table, the parameter v may indicate a rank indication (RI) value. The UE may report the RI value v according to the configured higher layer parameter typeII-RI-Restriction-r16. In the case of v>4, the UE may not report the RI value.

[0055] The UE may determine the CSI report based on the above parameters (eg, n1-n2-codebookSubsetRestriction-r16 and paramCombination-r16).

[0056] In addition, the CSI report may include the number of non-zero coefficients. For one TRP, the value K0 may be used to define the maximum non-zero coefficient per layer, and 2K0 may be used to define the maximum total number of non-zero coefficients across the layers of the TRP.

[0057] The value K0 can be calculated as follows:

[0058]

[0059] where β and L are defined as described above, and M1 is the number of bases in the frequency domain.

[0060] Its non-zero position indicates the amplitude coefficient index i 2,4,l And the phase coefficient index i 2,5,l Which coefficients are reported in the bitmap is determined by i 1,7,l Instructions are as follows:

[0061]

[0062] For l = 1, ..., υ, such that is the number of non-zero coefficients of layer l=1,…,v, and is the total number of nonzero coefficients.

[0063] Detailed bitmap information about non-zero coefficients is described in a 3GPP profile, such as TS 38.214, and the details are omitted here.

[0064] In view of the above, for the Rel.16e-Type-II codebook, the codebook configuration and the maximum number of non-zero coefficients are designed based on single TRP (S-TRP) transmission.

[0065] Currently, it is agreed to specify enhancements for CSI acquisition for CJT targeting FR1 and up to 4 TRPs, assuming ideal backhaul and synchronization and the same number of antenna ports across TRPs. Some agreements are presented below:

[0066] - Rel-16 / 17 Type-II codebook refinement for CJT multi-TRP (mTRP) targeting FDD and its associated CSI reporting, taking into account the throughput-overhead trade-off;

[0067] - SSR enhancement for managing the interference across SRS between TRPs targeting TDD CJT via SRS capacity enhancement and / or interference randomization, with the constraints that: 1) no additional resources for SRS are consumed; 2) existing SRS comb structure is reused; 3) no new SRS root sequence;

[0068] - Note: The maximum number of CSI-RS ports per resource remains the same as in Rel-17, i.e. 32;

[0069] -For N TRP Rel-18 Type-II codebook refinement for CJT mTRP of >1TRP or TRP group, supporting N with equal priority TRP ={1,2,3,4};

[0070] - For Rel-18 Type-II codebook of CJT mTRP, RI={1,2,3,4} is supported;

[0071] -For N TRP Rel-18 Type-II codebook refinement for CJT mTRP of >1TRP / TRP group supports the following:

[0072] Channel measurement resources (CMRs) include K>1 NZP CSI-RS resources, where one resource corresponds to one TRP / TRP group (i.e., K=N TRP )

[0073] Each of the CSI-RS resources has the same number of CSI-RS ports;

[0074] -For the Rel-18 Type-II codebook of CJT mTRP, the following two modes are supported:

[0075] • Mode 1: SD / FD basis selection per TRP / TRP group, which allows independent FD basis selection across N TRPs / TRP groups. Examples The formula (N=number of TRPs or TRP groups) may be as follows:

[0076]

[0077] • Mode 2: SD basis selection per TRP / TRP group (port group or resource) and joint / common (across N TRPs) FD basis selection. Examples The formula (N=number of TRPs or TRP groups) may be as follows:

[0078]

[0079] • Efforts were made to make both modes share commonalities in the detailed design of eg parameter combination, basis selection, TRP (group) selection, reference amplitude, W2 quantization scheme.

[0080] In view of the above, in Rel. 18, CJT may be further studied, where the same information may be coherently transmitted from multiple TRPs. However, there is no codebook configuration for CJT multiple TRPs, and thus a codebook configuration for CJT multiple TRPs is desired. In addition, the total number of parameter combinations and non-zero coefficients should be further considered as a balance between CSI overhead and system performance, especially in the case of a large number of TRPs (e.g., 4 TRPs) and a maximum RI value (e.g., 4).

[0081] For CJT, an enhanced codebook is designed for CSI reports containing multiple TRPs. Rel.18 agrees to support two codebook structures, which are presented as follows:

[0082] -Mode 1: Using independent selection scheme on a per-TRP or TRP group spatial and frequency domain basis across N TRPs or TRP groups, where N can be an integer equal to or greater than 2.

[0083] -Mode 2: Using per-TRP or TRP group spatial selection and joint or common frequency domain basis selection across N TRPs, where N can be an integer equal to or greater than 2.

[0084] Therefore, the codebook configuration and restrictions should be consistent with these two agreed codebook structures.

[0085] The present disclosure proposes some solutions related to codebook configuration and restriction. Specifically, the present disclosure proposes solutions related to rank restriction (e.g., typeII-RI-Restriction-r18), values ​​of N1 and N2, codebook subset restriction (e.g., n1-n2-codebookSubsetRestriction-r18), and codebook configuration per TRP and / or joint parameter combination (paramCombination-r18) (including the number of selected beams L, factor β, and frequency compression ratio p v ) and restrictions on the maximum number of non-zero coefficients per TRP and the maximum number of non-zero coefficients of TRPs spanning CJTs.

[0086] The aforementioned two modes (i.e., codebook structures) may be configured in radio resource control (RRC) signaling, which may be denoted as codebookConfig-r18. For both mode 1 and mode 2, some parameters may be configured with one value or a common value and used for all TRPs of the CJT, since the same information may be transmitted from all cooperating TRPs. In other words, the same parameters may be applied to all TRPs. These parameters may include:

[0087] - rank restriction, which may be referred to as typeII-RI-Restriction-r18;

[0088] - the number of precoding matrix indicator (PMI) subbands per channel quality indication (CQI) subband, which may be referred to as numberOfPMI-SubbandsPerCQI-Subband-r18; and

[0089] - The number of antenna ports in the first dimension and the number of antenna ports in the second dimension, which may be referred to as: N1 and N2, respectively.

[0090] Solution 1:

[0091] The values ​​of N1 and N2 can be configured in the codebook subset restriction of each TRP, such as n1-n2-codebookSubsetRestriction-r18. The number of CSI-RS ports per TRP P CSI-RS It can be: 2N1N2. The value of N1 is associated with O1, and the value of N2 is associated with O2. The values ​​of N1, N2, O1 and O2 and P CSI-RS CJT is facilitated by an agreement that each of the CSI-RS resources in the channel measurement resources (CMRs) has the same number of CSI-RS ports among multiple TRPs.

[0092] In some embodiments, the values ​​of the N1 and N2 pairs corresponding to the total CSI-RS antenna ports among all cooperative TRPs may be associated with the UE capabilities.

[0093] The UE may report its capabilities to the BS. The UE's capabilities may include one of the following:

[0094] - the maximum supported number of TRPs (i.e., CSI-RS resources as channel measurement resources) and the maximum supported number of CSI-RS ports per TRP (i.e., per CSI-RS resource); or

[0095] - Maximum number of supported TRPs (i.e., CSI-RS resources as channel measurement resources) and spanning TRPs (i.e.,

[0096] the supported maximum number of CSI-RS ports across the CSI-RS resource); or

[0097] - The supported maximum number of CSI-RS ports across a TRP (ie, across CSI-RS resources).

[0098] The supported maximum number of CSI-RS ports for a TRP spanning a CJT may include one of the following: 8, 12, 16, 24, 32, 64, etc. In some embodiments of the present disclosure, other numbers of CSI-RS ports may also be applied. Different UEs may support different maximum numbers of CSI-RS ports for CJT. In some embodiments, a set of supported numbers of CSI-RS ports for a CJT may be predefined in the specification, and each UE may report a value from this set as the maximum number of CSI-RS ports for the CJT. In some embodiments, the BS may configure a set of supported maximum numbers of CSI-RS ports for the UE, and each UE may report a value from this set. For example, the predefined or configured set may include at least one of 8, 12, 16, 24, 32, 64, etc.

[0099] The supported configurations of (N1, N2) and (O1, O2) of CJT are shown in Table 1 based on UE capabilities, assuming that the UE can support a maximum number of 32 CSI-RS antenna ports across TRPs and a maximum number of 4 TRPs.

[0100] Table 1: Supported configurations of CJT (N1, N2) and (O1, O2)

[0101]

[0102] In the case where the number of CSI-RS antenna ports per TRP is 4 or 8, the supported number of TRPs for CJT may be 2, 3, or 4. In the case where the number of CSI-RS antenna ports per TRP is 12 or 16, the supported number of TRPs for CJT may be 2. In some embodiments, for example, more than 4 TRPs may be supported for CJT, and in the case where the number of CSI-RS antenna ports per TRP is 4, the supported number of TRPs for CJT may be 8.

[0103] It should be noted that Table 1 is merely an example for illustration and not limitation; other configurations among the supported configurations of (N1, N2) and (O1, O2) of CJTs may also be applied.

[0104] In addition to the above parameters that can be configured to have one value (or a common value) across TRPs, some other parameters can be configured to have values ​​for each TRP (i.e., every TRP) of codebook structure mode 1 and across TRPs (i.e., for 2 TRPs, 3 TRPs, 4 TRPs, etc.) of codebook structure mode 2.

[0105] For example, codebook subset restrictions (e.g., n1-n2-codebookSubsetRestriction-r18) may be configured per TRP for codebook structure mode 1 and across TRPs for codebook structure 2. Codebook subset restrictions are defined per beam selected from one TRP and are thus naturally configured independently between TRPs as required by the BS. For codebook structure mode 1, codebook subset restrictions may be configured independently for each TRP. For codebook structure mode 2, codebook subset restrictions may be configured for beam combinations from multiple cooperating TRPs. From a signaling perspective, both may be implemented with multiple n1-n2-codebookSubsetRestriction-r18 restriction bit strings, where one n1-n2-codebookSubsetRestriction-r18 corresponds to one cooperating TRP of the CJT.

[0106] Solution 2:

[0107] Solution 2 involves parameter combinations included in the codebook configuration (e.g. paramCombination-r18). The parameter combination may consist of the following parameters:

[0108] - the number of selected beams, which may be referred to as L;

[0109] - a factor, which may be referred to as β; and

[0110] - the frequency compression ratio, which may be referred to as p v .

[0111] Some parameters in the codebook parameter combination may be configured per TRP because the RSRP and signal strength of a TRP may have the following differences and thus the corresponding feedback overhead may be different.

[0112] The present disclosure proposes some solutions for configuring codebook parameter combinations. Hereinafter, the codebook parameter combination may be referred to as "paramCombination-r18", but is not limited thereto.

[0113] Solution 2-1

[0114] In this solution, the parameter combination (L, β, p) can be configured separately for each TRP (i.e., per TRP paramCombination-r18). υ ), that is, each TRP can be configured with a parameter combination (L, β, p based on codebook structure mode 1 v ).

[0115] The RRC signaling of the codebook configuration (e.g., codebookConfig-r18) may include multiple parameter combinations paramCombination-r18, where each paramCombination-r18 may correspond to one TRP. There is an implicit one-to-one mapping between one NZP CSI-RS resource (i.e., resourcesForChannelMeasurement) and one parameter combination (i.e., paramCombination-r18). In other words, each parameter combination may correspond to one NZP CSI-RS resource, i.e., each parameter combination may correspond to one TRP.

[0116] In some embodiments, when codebook structure mode 1 is configured in RRC signaling and only one parameter combination paramCombination-r18 is included in the RRC signaling, the same parameter combination configuration paramCombination-r18 may be applied to each TRP of the CJT, that is, each TRP may be associated with the same paramCombination-r18.

[0117] In some embodiments of the present disclosure, it is proposed that for each TRP, the number of selected beams, i.e., L, may be less than 6, because in the case of a large number of TRPs, a relatively large number of L may result in a relatively large number of reporting overheads, but due to the limited number of total CSI-RS ports, it may not bring significant performance gains.

[0118] For factor β, it is proposed that in the case of a relatively large number of TRPs (e.g., 3 TRPs or 4 TRPs, etc.) and a higher rank value (e.g., 3 or 4), a smaller value (e.g., less than 1 / 4, such as 1 / 8, 1 / 16, etc.) can be configured to reduce CSI overhead.

[0119] In some embodiments of the present disclosure, it is proposed that the CSI reporting overhead in the case of 3 or 4 TRPs does not exceed the maximum overhead in the case of 2 TRPs.

[0120] Table 2a depicts an example of a separate codebook parameter configuration paramCombination-r18 (ie, per TRP) for CJT.

[0121] Table 2a: L, β and p of CJT v Separate codebook parameter configuration for

[0122]

[0123] In Table 2a, the number of selected beams, i.e., L, is less than 6. In the case of more than 2 TRPs, a factor β having a smaller value is configured. For example, in the case where the value of paramCombination-r18 is 7, in the case where there are more than 2 TRPs (e.g., 3 TRPs or 4 TRPs), the value of the factor β is 1 / 8, and the value of L is 2. In the case where the value of paramCombination-r18 is 8, in the case where there are more than 2 TRPs (e.g., 3 TRPs or 4 TRPs), the value of β is 1 / 8, and the value of L is 4.

[0124] It should be noted that Table 2a is an example for illustration only and not limitation; other configurations of parameter combinations may also be applied.

[0125] Solution 2-2

[0126] In this solution, a parameter combination (L, β, p) can be configured for all TRPs based on codebook structure mode 2. υ ). That is, the joint paramCombination-r18 is configured based on codebook structure mode 2.

[0127] The frequency compression ratio, i.e., p υ Can be common to all TRPs.

[0128] The total number of selected beams L across the TRPs can be configured in the joint paramCombination-r18. It is proposed that there are N TRPs and the number of selected beams n of a TRP is L n ,So In the case of 3 TRPs, 4 TRPs or more, the configurable To support 2 selected beams per TRP, for example, L can be 6, 8, or even larger. In addition, smaller values ​​of L (e.g., 2) may not be as useful because there are at least two TRPs for CJT.

[0129] For β, in the case where there are 3 TRPs, 4 TRPs or even more TRPs and in the case where the rank value may be 3, 4 or even higher, a smaller value (e.g., less than 1 / 4, such as 1 / 8, 1 / 16, etc.) may be configured to reduce the CSI overhead.

[0130] In some embodiments, the CSI reporting overhead in the presence of 3 or 4 TRPs may not exceed the maximum overhead associated with two TRPs. Table 2b illustrates an example of a joint paramCombination-r18 for CJT.

[0131] Table 2b: L, β and p of CJT υ Joint codebook parameter configuration

[0132]

[0133] As explained above, for the joint codebook parameter configuration, the value of the selected number of beams, i.e., L, may be other than 2. In the case where the value of paramCombination-r18 is 5, 6, or 10 (which corresponds to the value of L being 6), 3 TRP CJTs may be supported, where the number of selected beams for each TRP is 2. In the case where the value of paramCombination-r18 is 7, 8, or 11 (which corresponds to the value of L being 8), 4 TRP CJTs may be supported, where the number of selected beams for each TRP is 2. In some other embodiments, the number of selected beams across TRPs may include 4, 5, 6, 7, 8, 9, etc.

[0134] When the value of paramCombination-r18 is 9, 10, or 11, the value of factor β may be 1 / 8, which is smaller than other values ​​of β, and smaller values ​​of β may be used for higher ranks and / or larger numbers of TRPs for CJTs.

[0135] It should be noted that Table 2b is an example for illustration only and not limitation; other configurations of parameter combinations may also be applied.

[0136] For this solution, the parameter combination (L,β,p v ) can be defined from the perspective of multiple TRPs. If for each TRP we restrict v The proposed configuration can also be defined from the perspective of each TRP. For example, β,p v The same value of may be used for configurations defined across TRPs and for configurations defined per TRP. The value of the selected beam across a TRP (which may be represented as L′) may be equal to the product of the total number of TRPs of the CJT (which may be represented as N) and the value of L defined per TRP, i.e., L′=N×L.

[0137] Solution 3

[0138] Solution 3 involves restrictions on the maximum number of non-zero coefficients per TRP and the maximum number of non-zero coefficients across TRPs.

[0139] The CSI report may include the number of non-zero coefficients. The number of non-zero coefficients may be limited by the following two parameters:

[0140] i. The maximum number of non-zero coefficients per layer, and

[0141] ii. The maximum number of non-zero coefficients across layers (ie, the maximum total number of non-zero coefficients).

[0142] That is, the number of non-zero coefficients of each layer may not exceed the first parameter, i.e., the maximum number of non-zero coefficients per layer; and the total number of non-zero coefficients may not exceed the second parameter, i.e., the maximum number of non-zero coefficients across layers.

[0143] For codebook structure mode 1, for each TRP, parameter K0 is used to define the maximum number of non-zero coefficients per layer, and 2K0 is used to define the maximum number of non-zero coefficients across layers. Parameter K0 is calculated as follows:

[0144]

[0145] Where β is a factor, L is the number of selected beams, M1 is the number of bases in the frequency domain, and these parameters are configured per TRP in the codebook configuration.

[0146] With the above restrictions, i.e., K0 as the maximum number of non-zero coefficients per layer and 2K0 as the maximum number of non-zero coefficients across layers of one TRP, it avoids too many non-zero coefficients for one TRP, for example, one TRP has a larger RSRP value compared to other TRPs.

[0147] Regarding the total number of non-zero coefficients across TRPs, in order to balance between CSI reporting overhead and system performance, for high rank (e.g., rank may be 3, 4, or even higher) transmission, the CSI reporting overhead may be the same as that of rank 2. That is, in the case where the same value of K0 is determined for each TRP, the maximum number of non-zero coefficients per layer across TRPs (e.g., 3 TRPs, 4 TRPs, or even more TRPs) is 2K0, and the maximum number of non-zero coefficients across layers across TRPs (e.g., 3 TRPs, 4 TRPs, or even more TRPs) is 4K0.

[0148] In some embodiments, the coefficient x_k1 may be configured by the BS or predefined in the specification. In the case where the same value of K0 is determined for each TRP, the maximum number of non-zero coefficients per layer across a TRP may be defined as x_k1×K0, and the maximum number of non-zero coefficients across layers across a TRP may be defined as x_k1×2k0. The value of x_k1 may include 2, 3, or other numbers.

[0149] In some other embodiments, different TRPs may have different k0 values. For example, the parameters (i.e., β, L, or M1) may be configured to have different values ​​for different TRPs. In this case, K0′ may be determined based on all K0 values ​​of the TRP. For example, K0′ may be the maximum, average, or minimum of all K0 values, a randomly selected value of K0 among the TRPs, etc. Then, the maximum number of non-zero coefficients across each layer of the TRP may be determined to be x_k1×K0′, and the maximum number of non-zero coefficients across layers across the TRP may be determined to be 2x_k1×K0′.

[0150] In this way, the CSI reporting overhead does not increase linearly with the number of TRPs.For some TRPs with the smallest RSRP values, a smaller number of non-zero coefficients may be reported.

[0151] For codebook structure mode 2 for CJT, parameters β, L, and M1 may be defined for a joint codebook spanning multiple TRPs. For example, Where L is the number of selected beams of all TRPs, L n is the selected beam number of a TRP (ie, TRP n), and N is the total number of TRPs.

[0152] It is proposed that the number of selected beams for each TRP is the same. Therefore, for each TRP, the number of selected beams can be L / N. Then, the maximum number of non-zero coefficients per layer per TRP can be defined as And the maximum number of non-zero coefficients across layers per TRP can be defined as 2k0.

[0153] Similarly, the maximum number of non-zero coefficients across each layer of the TRP can be defined as And the maximum number of non-zero coefficients across layers across TRP can be defined as 2K0.

[0154] It should be noted that the parameter β in Solution 3 can use the value defined in Solution 2, for example, for more than 2 TRPs, 1 / 8 can be used.

[0155] Figure 2 Flowchart illustrating an exemplary method for CSI reporting performed by a UE according to some embodiments of the present disclosure. It is contemplated that the method may be performed by other devices having similar functionality.

[0156] In operation 201, the UE may receive a codebook configuration for a CSI report associated with a plurality of CSI-RS resources. In operation 202, the UE may transmit a CSI report based on the codebook configuration. The per-TRP and cross-TRP codebook configurations and restrictions on the maximum number of non-zero coefficients described in any of the above embodiments may apply.

[0157] Figure 3 Flowchart illustrating an exemplary method for CSI reporting performed by a BS according to some embodiments of the present disclosure. It is contemplated that the method may be performed by other devices having similar functionality.

[0158] In operation 301, the BS may transmit a codebook configuration for a CSI report associated with a plurality of CSI-RS resources. In operation 302, the BS may receive a CSI report based on the codebook configuration. The per-TRP and cross-TRP codebook configurations and the restrictions on the maximum number of non-zero coefficients described in any of the above embodiments may apply.

[0159] In some embodiments, the codebook configuration includes at least one first parameter (e.g., n1-n2-codebookSubsetRestriction-r18), and each first parameter indicates a codebook subset restriction of a number pair (e.g., N1 and N2) consisting of: a first number of antenna ports in a first dimension (e.g., N1); and a second number of antenna ports in a second dimension (e.g., N2); wherein each of the at least one first parameter is associated with one of a plurality of CSI-RS resources; or wherein in the case where the codebook configuration includes only one first parameter, the first parameter is associated with a plurality of CSI-RS resources.

[0160] In some embodiments, the restriction values ​​of the first number and the second number included in the codebook subset restriction are determined based on the total number of the plurality of CSI-RS resources, the capability of the UE, or both.

[0161] In some embodiments, the transceiver further transmits the capabilities of the UE to the BS, wherein the capabilities of the UE include one of: the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports per CSI-RS resource; the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports across CSI-RS resources; or the supported maximum number of CSI-RS ports across CSI-RS resources.

[0162] In some embodiments, the supported maximum number of CSI-RS ports across a CSI-RS resource comprises a value selected from a set comprising at least one of 8, 12, 16, 24, 32, or 64. In some embodiments, the set may comprise other numbers.

[0163] In some embodiments, the codebook configuration further indicates a same pair of values ​​for the number pair for each of the plurality of CSI-RS resources.

[0164] In some embodiments, the codebook configuration includes at least one second parameter, and each second parameter indicates a combination of: the number of selected beams L; the factor β; and the frequency compression ratio p v ; wherein each of the at least one second parameter is associated with one of the plurality of CSI-RS resources; or wherein in the case where only one second parameter is included in the codebook configuration, the second parameter is associated with the plurality of CSI-RS resources.

[0165] In some embodiments, when the number of selected beams is configured per CSI-RS resource, the number of selected beams is 2 or 4 (for example, in Table 2a, the number of selected beams, i.e., L is 2 or 4), or when the number of selected beams is configured across multiple CSI-RS resources, it is 4, 5, 6, 7 or 8 (for example, in Table 2b, the number of selected beams, i.e., L is 4, 6 or 8).

[0166] In some embodiments, in the case where more than two CSI-RS resources are included in the plurality of CSI-RS resources, the factor is a value less than 1 / 4 (eg, in Table 2b, the factor may have a value of 1 / 8).

[0167] In some embodiments, the CSI report includes the number of non-zero coefficients, and the UE determines at least one of the following based on the codebook configuration: the maximum number of non-zero coefficients per layer per CSI-RS resource; the maximum number of non-zero coefficients across layers per CSI-RS resource; the maximum number of non-zero coefficients per layer across CSI-RS resources; or the maximum number of non-zero coefficients across layers across CSI-RS resources.

[0168] In some embodiments, when the factor β, the number of selected beams L, and the number of bases M1 in the frequency domain are configured per CSI-RS resource in the codebook configuration (e.g., for codebook structure mode 1), the maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be And the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be 2K0.

[0169] In some embodiments, the maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be (e.g., for codebook structure mode 2) across the CSI-RS resource configuration factor β, the number of selected beams L, and the number of bases M1 in the frequency domain in the codebook configuration. And the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be 2K0, where N is the total number of multiple CSI-RS resources.

[0170] In some embodiments, when the factor β, the number of selected beams L, and the number of base stations M1 in the frequency domain are configured per CSI-RS resource in the codebook configuration (e.g., for codebook structure mode 1), for each CSI-RS resource, the UE determines the value The maximum number of non-zero coefficients per layer across CSI-RS resources is determined to be x_k1×K0′, and the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2x_k1×K0′, where x_k1 is a predefined coefficient or a configured coefficient, and K0′ is the maximum value or average of all determined values ​​K0.

[0171] In some embodiments, in the case of (e.g., for codebook structure mode 2) across CSI-RS resource configuration factor β, the number of selected beams L, and the number of bases M1 in the frequency domain in the codebook configuration, the maximum number of non-zero coefficients across each layer of CSI-RS resources is determined to be And the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2K0.

[0172] In some embodiments, the codebook configuration further indicates the same rank restriction for each of the plurality of CSI-RS resources.

[0173] Figure 4 A simplified block diagram illustrating an exemplary apparatus 400 in accordance with some embodiments of the present disclosure.

[0174] like Figure 4 4 , the apparatus 400 may include at least one processor 404 and at least one transceiver 402 coupled to the processor 404. The apparatus 400 may be a UE, a BS, or any other device having similar functionality.

[0175] Although in this figure, elements are described in singular form, such as at least one transceiver 402 and processor 404, plural form is contemplated unless limitation to the singular form is explicitly stated. In some embodiments of the present disclosure, transceiver 402 may be divided into two devices, such as a receiving circuit system and a transmitting circuit system. In some embodiments of the present disclosure, device 400 may further include an input device, a memory and / or other components.

[0176] In some embodiments of the present disclosure, the device 400 may be a UE. The transceiver 402 and the processor 404 may interact with each other to perform Figures 1 to 3. For example, the transceiver 402 may receive a codebook configuration for a CSI report associated with a plurality of CSI-RS resources and transmit the CSI report based on the codebook configuration. As another example, the processor 404 may determine, based on the codebook configuration, at least one of: a maximum number of non-zero coefficients per layer per CSI-RS resource; a maximum number of non-zero coefficients across layers per CSI-RS resource; a maximum number of non-zero coefficients per layer across CSI-RS resources; or a maximum number of non-zero coefficients across layers across CSI-RS resources.

[0177] In some embodiments of the present disclosure, the device 400 may be a BS. The transceiver 402 and the processor 404 may interact with each other to perform Figures 1 to 3 For example, the transceiver 402 may transmit a codebook configuration of a CSI report associated with a plurality of CSI-RS resources and receive a CSI report based on the codebook configuration.

[0178] In some embodiments of the present disclosure, the apparatus 400 may further include at least one non-transitory computer-readable medium.

[0179] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may store computer-executable instructions to enable the processor 404 to implement the method described above regarding the UE. For example, when the computer-executable instructions are executed, the processor 404 may interact with the transceiver 402 to perform the method described above regarding the UE. Figures 1 to 3 Operation of the UE described in any one of the foregoing.

[0180] In some embodiments of the present disclosure, a non-transitory computer-readable medium may store computer-executable instructions to enable the processor 404 to implement the method described above regarding the BS. For example, when the computer-executable instructions are executed, the processor 404 may interact with the transceiver 402 to perform the method regarding the BS. Figures 1 to 3 The operation of the BS described by any one of .

[0181] The methods of the present disclosure may be implemented on a programmed processor. However, the controller, flow charts, and modules may also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, a hardware electronic or logic circuit (e.g., a discrete component circuit), a programmable logic device, or the like. In general, any device having a finite state machine capable of implementing the flow charts shown in the figures may be used to implement the processing functions of the present disclosure.

[0182] Although the present disclosure has been described using specific embodiments of the present disclosure, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, the various components of the embodiments may be interchangeable, added, or substituted in other embodiments. Moreover, all of the elements shown in each figure are not necessary for the operation of the disclosed embodiments. For example, a person skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0183] In the present disclosure, for example, the relational terms of "first", "second" and the like can be used alone to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The term "comprises, comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements but also may include other elements that are not explicitly listed or inherent to this process, method, article or equipment. The elements starting with "a, an" or the like do not exclude the presence of additional identical elements in the process, method, article or equipment including the elements without more constraints. Moreover, the term "another" is defined as at least the second or more. As used herein, the terms "include", "have" and the like are defined as "include".

Claims

1. A user equipment UE, comprising: A transceiver that: receiving a codebook configuration of a channel state information (CSI) report associated with a plurality of channel state information reference signal (CSI-RS) resources; and Transmitting a CSI report based on the codebook configuration; and A processor is coupled to the transceiver.

2. The UE according to claim 1, wherein the codebook configuration comprises at least one first parameter, and each first parameter indicates a codebook subset restriction of a number of pairs consisting of: a first number of antenna ports in a first dimension; and a second number of antenna ports in a second dimension; wherein each of the at least one first parameter is associated with one of the plurality of CSI-RS resources; or wherein in a case where only one first parameter is included in the codebook configuration, the first parameter is associated with the plurality of CSI-RS resources.

3. The UE according to claim 2, wherein restriction values ​​of the first number and the second number included in the codebook subset restriction are determined based on a total number of the plurality of CSI-RS resources, a capability of the UE, or both.

4. The UE according to claim 1, wherein the transceiver further transmits capabilities of the UE to a base station BS, wherein the capabilities of the UE include one of the following: The supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports per CSI-RS resource; the supported maximum number of CSI-RS resources as channel measurement resources and the supported maximum number of CSI-RS ports across CSI-RS resources; or The supported maximum number of CSI-RS ports across a CSI-RS resource.

5. The UE of claim 4, wherein the supported maximum number of CSI-RS ports across a CSI-RS resource comprises a value selected from a set comprising at least one of 8, 12, 16, 24, 32, or 64. 6 . The UE of claim 2 , wherein the codebook configuration further indicates a same pair of values ​​of the number pair for each of the plurality of CSI-RS resources.

7. The UE according to claim 1, wherein the codebook configuration comprises at least one second parameter, and each second parameter indicates a combination consisting of: The number of selected beams L; Factor β; and Frequency compression ratio p v ; wherein each of the at least one second parameter is associated with one of the plurality of CSI-RS resources; or wherein in a case where only one second parameter is included in the codebook configuration, the second parameter is associated with the plurality of CSI-RS resources.

8. The UE according to claim 7, wherein when the number of selected beams is configured per CSI-RS resource, the number of selected beams is 2 or 4, or when the number of selected beams is configured across the multiple CSI-RS resources, it is 4, 5, 6, 7 or 8. 9 . The UE according to claim 7 , wherein in a case where more than two CSI-RS resources are included in the plurality of CSI-RS resources, the factor is a value smaller than 1 / 4.

10. The UE of claim 1, wherein the CSI report comprises a number of non-zero coefficients, and the processor determines at least one of the following based on the codebook configuration: The maximum number of non-zero coefficients per layer per CSI-RS resource; The maximum number of non-zero coefficients across layers per CSI-RS resource; The maximum number of non-zero coefficients per layer across the CSI-RS resource; or Maximum number of non-zero coefficients across layers across CSI-RS resources.

11. The UE according to claim 10, wherein in the case where the factor β, the number of selected beams L, and the number of base stations M1 in the frequency domain are configured per CSI-RS resource in the codebook configuration, The maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be and the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be and / or For each CSI-RS resource, the processor determines a value The maximum number of non-zero coefficients for each layer across CSI-RS resources is determined to be x_k1×K′0, and the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2x_k1×K′0, where x_k1 is a predefined coefficient or a configured coefficient, and K′0 is the maximum value or average of all the determined values ​​K0.

12. The UE according to claim 10, wherein in the case of crossing a CSI-RS resource configuration factor β, a number of selected beams L, and a number of base stations M1 in the frequency domain in the codebook configuration, The maximum number of non-zero coefficients per layer per CSI-RS resource is determined to be and the maximum number of non-zero coefficients across layers per CSI-RS resource is determined to be Wherein N is the total number of the plurality of CSI-RS resources; and / or The maximum number of non-zero coefficients across each layer of the CSI-RS resource is determined to be And the maximum number of non-zero coefficients across layers across CSI-RS resources is determined to be 2K0.

13. The UE of claim 1, wherein the codebook configuration further indicates a same rank restriction for each of the plurality of CSI-RS resources.

14. A base station BS, comprising: A transceiver that: transmitting a codebook configuration of a channel state information (CSI) report associated with a plurality of channel state information reference signal (CSI-RS) resources; and receiving a CSI report based on the codebook configuration; and A processor is coupled to the transceiver.

15. A method performed by a user equipment UE, comprising: receiving a codebook configuration of a channel state information (CSI) report associated with a plurality of channel state information reference signal (CSI-RS) resources; and A CSI report is transmitted based on the codebook configuration.

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