Method performed on terminal device, terminal device, method performed on network device, and network device

Abstract

To provide a method, a device, and a computer-readable medium for reducing channel state information (CSI) feedback overhead.SOLUTION: In an exemplary embodiment, a method performed at a terminal device includes receiving a reference signal and a codebook configuration indicating at least one codebook subset restriction (CBSR) from a network device, determining at least one precoding matrix indicator (PMI) associated with a plurality of beams selected from a beam set between the terminal device and the network device based at least in part on the at least one CBSR on the basis of the reference signal, and transmitting the at least one PMI to the network device.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly, to methods and devices for reducing channel state information (CSI) feedback overhead. [Background technology]

[0002] Communication technologies have been developed with various telecommunication standards to provide common protocols that allow different wireless devices to communicate at municipal, national, regional, and even global levels. An example of a novel telecommunication standard is New Radio (NR) access, e.g., 5G wireless access. Currently, research on NR systems has been approved. NR aims to be a single technology framework that addresses all use cases, requirements, and deployment scenarios defined in TR38.913, including enhanced mobile broadband, large-scale machine-type communication, and ultra-reliable and low-latency communication, and considers frequency ranges up to 100 GHz.

[0003] A multi-antenna scheme for new radio access has been provided focusing on aspects including multi-antenna scheme, beam management, CSI acquisition, reference signal and QCL. Furthermore, a type-II codebook has been agreed upon for NR. However, the type-II codebook has huge computational complexity and feedback overhead. Also, for the type-II codebook, a codebook subset restriction (CBSR) has been agreed upon, which can reduce the computational complexity but does not change the feedback overhead. Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the example embodiments of the present disclosure provide methods and devices for reducing channel state information (CSI) feedback overhead. [Means for solving the problem]

[0005] In a first aspect, a method is provided that is performed in a terminal device, the method including receiving a reference signal and a codebook configuration indicating at least one Codebook Subset Restriction (CBSR) from a network device, determining at least one Precoding Matrix Indicator (PMI) associated with a plurality of beams selected based at least in part on the at least one CBSR from a set of beams between the terminal device and the network device based on the reference signal, and transmitting the at least one PMI to the network device.

[0006] In a second aspect, a method is provided that is performed in a network device, the method including: transmitting a reference signal and a codebook configuration indicating at least one Codebook Subset Restriction (CBSR) to a terminal device, and receiving at least one Precoding Matrix Indicator (PMI) associated with a plurality of beams selected from a set of beams between the terminal device and the network device based at least in part on the at least one CBSR, the at least one PMI being determined by the terminal device based on the reference signal.

[0007] In a third aspect, there is provided a terminal device comprising a processor and a memory coupled to the processor and having instructions stored thereon, the instructions, when executed by the processor, causing the device to perform a method according to the first aspect.

[0008] In a fourth aspect, there is provided a network device comprising a processor and a memory coupled to the processor and having instructions stored thereon, the instructions, when executed by the processor, causing the device to perform a method according to the second aspect.

[0009] In a fifth aspect, there is provided a computer readable medium having stored thereon instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the first aspect.

[0010] In a sixth aspect, there is provided a computer readable medium having stored thereon instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the second aspect.

[0011] Other features of the present disclosure will become readily apparent from the following description. [Brief description of the drawings]

[0012] The above and other objects, features and advantages of the present disclosure will become more apparent through more detailed description of several embodiments of the present disclosure with reference to the accompanying drawings.

[0013] [Figure 1] FIG. 1 is a block diagram of a communication environment in which embodiments of the present disclosure may be implemented.

[0014] [Diagram 2] 2 illustrates a flowchart of an example method 200 for reducing CSI feedback overhead according to some embodiments of the present disclosure.

[0015] [Figure 3A] 1 illustrates examples of some embodiments of the present disclosure. [Figure 3B] 1 illustrates examples of some embodiments of the present disclosure. [Figure 3C] 1 illustrates examples of some embodiments of the present disclosure.

[0016] [Figure 4] 1 illustrates examples of some embodiments of the present disclosure.

[0017] [Diagram 5] 1 illustrates examples of some embodiments of the present disclosure.

[0018] [Figure 6] 2 illustrates a flowchart of an example method 200 for reducing CSI feedback overhead according to some embodiments of the present disclosure.

[0019] [Figure 7] 1 illustrates a flowchart of an example method for reducing CSI feedback overhead in accordance with some embodiments of the present disclosure.

[0020] [Figure 8] FIG. 1 is a simplified block diagram of a device suitable for practicing embodiments of the present disclosure.

[0021] Throughout the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only, and are not intended to imply any limitation on the scope of the present disclosure, but to aid those skilled in the art in understanding and practicing the present disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0023] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0024] As used herein, the term "network device" or "base station" (BS) refers to a device that can provide or host a cell or coverage through which terminal devices can communicate. Examples of network devices include, but are not limited to, Node B (NodeB or NB), Evolved Node B (eNodeB or eNB), Node B in new radio access (gNB), next generation Node B (gNB), Remote Radio Unit (RRU), Radio Head (RH), Remote Radio Head (RRH), and low power nodes such as femto nodes and pico nodes. For purposes of explanation, some embodiments will be described below with an eNB as an example of a network device.

[0025] As used herein, the term "terminal device" refers to any device having wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, User Equipment (UE), personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback devices, or Internet appliances that enable wireless or wired Internet access and browsing, etc.

[0026] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The term "comprises" and variations thereof are read as open terms meaning "including, but not limited to." The term "based on" is read as "based at least in part on." The terms "one embodiment" and "embodiment" are read as "at least one embodiment." The term "another embodiment" is read as "at least one other embodiment." Terms such as "first," "second," and the like may refer to different objects or the same object. Other definitions, both explicit and implicit, are included below.

[0027] In some instances, a value, procedure, or device may be referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to indicate that a selection may be made from among many functional options available, and that such selection is not necessarily better, smaller, higher, or more preferred than other options.

[0028] FIG. 1 illustrates an exemplary communication network 100 in which embodiments of the present disclosure may be implemented. The network 100 includes a network device 110 and a terminal device 120 that is serviced by the network device 110. The service area of ​​the network device 110 is referred to as a cell 102. It should be understood that the number of network devices and terminal devices is for illustrative purposes only, without implying any limitation. The network 100 may include any suitable number of network devices and terminal devices suitable for implementing embodiments of the present disclosure. Although not illustrated, it should be understood that one or more terminal devices may be located within the cell 102 and serviced by the network device 110.

[0029] In the communication network 100, the network devices 110 may communicate data and control information to the terminal devices 120. The link from the network devices 110 to the terminal devices 120 is called the downlink (DL) or forward link, and the link from the terminal devices 120 to the network devices 110 is called the uplink (UL) or reverse link.

[0030] Depending on the communication technology, the network 100 may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Access (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency-Division Multiple Access (OFDMA) network, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) network, or any other. Communications contemplated by network 100 may conform to any suitable standard, including, but not limited to, New Radio Access (NR), Long Term Evolution (LTE), LTE Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, Global System for Mobile Communication (GSM), and the like. Furthermore, communications may be performed according to any currently known or future developed generation of communications protocols. Examples of communications protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communications protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the technology are described below in terms of LTE, and LTE terminology is used in much of the description below.

[0031] In communication, the terminal device 120 is configured to estimate and report channel state information (CSI) of a communication channel between the terminal device 120 and the network device 110. The terminal device 120 can determine the CSI using a downlink reference signal transmitted by the network device 110.

[0032] In general, LTE utilizes an implicit rank indicator / precoding matrix indicator / resource partitioning information / channel quality indicator (RI / PMI / RPI / CQI) feedback framework for CSI feedback, where the CSI feedback framework is "implicit" in the form of codebook-derived CQI / PMI / RI (and CRI in the LTE specification).

[0033] As described above, RI (Rank Indicator) is information on the channel rank and indicates the number of streams / layers that can be received via the same time-frequency resource. RI is determined by long-term fading of the channel, so it may generally be fed back at a longer period than PMI (Precoding Matrix Indicator) or CQI (Channel Quality Indicator). PMI is a value indicating the spatial characteristics of the channel and indicates the index of the precoding matrix of the network device desired by the terminal device. RPI (Relative Power Indicator) corresponds to the allocation of resources in the power domain between different beams / layers or between different ports indicated by PMI. ACI (Amplitude Coefficient Indicator) is an amplitude parameter of the beam / layer, and the amplitude coefficient indicator may be wideband or subband. PCI (Phase Coefficient Indicator) is an amplitude parameter of the beam / layer, and the phase coefficient indicator may be wideband or subband. CQI is information indicating the strength of the channel and indicates the received SINR obtained when the network device uses PMI.

[0034] The CSI feedback reflects the average channel condition over the entire or a portion of the configured bandwidth (e.g., wideband). For example, the configured bandwidth may be the bandwidth of the CSI-RS (Channel State Information-Reference Signal). In another example, the configured bandwidth may be the bandwidth configured for reporting. Some metrics such as RI, PMI, ACI, PCI, RPI, etc. may be calculated to reflect the average channel condition over the entire configured bandwidth (e.g., wideband RI / PMI / ACI). The wideband PMI may indicate the index of the beam over the entire configured bandwidth, and the wideband ACI may indicate the gain of the beam over the entire configured bandwidth. Some metrics such as PMI and CQI may be calculated per subband (e.g., a portion of the entire configured bandwidth). The PMI of a subband may indicate the gain of a beam in the subband, the ACI of a subband may indicate the amplitude coefficient of a beam in the subband, and the PCI of a subband may indicate the phase coefficient of a beam in the subband.

[0035] If the terminal device 120 reports CSI for multiple beams (e.g., L beams), information about the beams is needed to determine a codeword from a codebook. The codebook may be supported in Layer 1 and Layer 2. The codeword in this case may be defined by the terminal device 120 according to the information of different beams, for example, as follows: For Layer 1:

number

number

number

number

number

number

number

number

number

number

[0036] To enable the network device 110 to determine the codeword, the terminal device 120 needs to report the parameters described above for each of the L beams, which would increase the overhead of CSI feedback.

[0037] As mentioned above, several metrics such as RI, PMI, ACI, PCI, RPI, etc. may be calculated to reflect the average channel conditions. Table 1 below shows the PMI for Type II codebooks. [Table 1]

[0038] As can be seen from Table 1, PMI refers to wideband PMI and subband PMI. For example, i 1,1 can be considered as an indication for feedback of one beam group from O1*O2 beam groups, where O1 and O2 are values ​​configured for oversampling the spatial direction. 1,2 is a beam group (e.g., i 1,1The beam group (beam group denoted by i) can be regarded as a feedback instruction for L beams from N1*N2 beams. 1,4,1 can be considered as an indication for the broadband amplitude coefficient of each of the L beams. 2,1,1 can be taken as an indication of the phase coefficient of a beam whose broadband amplitude parameter has a non-zero value. 2,2,1 may be taken as an indication of the subband amplitude coefficients of beams whose broadband amplitude parameter has a non-zero value.

[0039] From the above, it can be seen that the overhead of PMI feedback is large. Furthermore, when the system bandwidth is wide, feedback is transmitted for each of multiple subbands in the system bandwidth, and as the number of subbands increases, the overhead further increases.

[0040] Currently, codebook subset restriction (CBSR) is introduced for type-II codebooks to reduce the computational complexity due to channel conditions, but the feedback overhead remains unchanged.

[0041] According to an embodiment of the present disclosure, a solution for reducing the overhead of CSI feedback is provided. In this solution, PMI associated with only some specific beams is reported to a network device to reduce the overhead of CSI feedback. Further details of the embodiment of the present disclosure will be described with reference to Figures 2 to 8.

[0042] 2 illustrates a flowchart of an example method 200 for reducing channel state information (CSI) feedback overhead according to some embodiments of the present disclosure. Method 200 may be implemented in terminal device 120 illustrated in FIG. It is understood that method 200 may include additional blocks not illustrated and / or omit some blocks illustrated, and the scope of the present disclosure is not limited in this respect. For purposes of explanation, method 200 will be described from the perspective of terminal device 120 with reference to FIG. 1.

[0043] In block 210, the terminal device 120 receives a codebook configuration and a reference signal from the network device 110, where the codebook configuration indicates at least one codebook subset restriction (CBSR).

[0044] In some embodiments, the terminal device 120 receives Radio Resource Control (RRC) signaling from the network device 110 and determines, based on the RRC signaling, a number of antenna ports in a first dimension and a second dimension of the antenna array of the network device 110 and an oversampling factor corresponding to the number of antenna ports in the first dimension and the second dimension of the antenna array of the network device 110. The terminal device 120 receives a reference signal based on at least the number of antenna ports in the first dimension and the second dimension of the antenna array of the network device 110 and the corresponding oversampling factor. Furthermore, the terminal device 120 obtains channel state information based on the reference signal.

[0045] As described above, the number of antenna ports in the first and second dimensions of the antenna array of the network device may be represented by the type II codebook, i.e., N1 and N2, as shown in Equation (3). Specifically, N1 and N2 may be understood as the number of antenna ports corresponding to the first and second dimensions (e.g., horizontal and vertical directions) of the network device 120. Furthermore, in some cases, the oversampling factors corresponding to the number of the first and second dimensions of the antenna array of the network device 120 may be represented by O1 and O2, which are configured to oversample the spatial direction, as described above.

[0046] In general, the values ​​of the oversampling factors O1,O2 correspond to the number N1,N2 of the first and second dimensions of the antenna array. Table 2 below shows supported configurations of (N1,N2) and (O1,O2). [Table 2]

[0047] In some embodiments, the network device 110 configures the number of dimensions N1, N2 of the antenna array and informs the terminal device 110 of the configuration of the number of dimensions N1, N2 of the antenna array via RRC signaling. Thus, the number of oversampling factors O1, O2 may also be obtained by the terminal device 110.

[0048] In block 220, the terminal device 120 determines at least one precoding matrix indicator (PMI) based on the reference signal, the at least one PMI being associated with a plurality of beams selected from a set of beams between the terminal device and the network device based at least in part on the at least one CBSR.

[0049] In some cases, the terminal device 120 may determine the total number of beam groups (O1*O2) and the total number of beams (N1*N2*O1*O2) between the terminal device 120 and the network device 110 in different spatial directions based on the number of first and second dimensions N1, N2 of the antenna array and the corresponding oversampling factors O1, O2. For example, N1=4, N2=4, the corresponding oversampling factors O1=4, O2=4. Thus, for a two-dimensional antenna array defined by N1, N2 and O1, O2, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=256. There are N1*N2, i.e., 16 beams, in each beam group.

[0050] It can be understood that if the terminal device 120 reports the PMI associated with each beam group or each beam in the two-dimensional antenna array to the network device 120, the overhead of CSI feedback is very large. Therefore, it is considered to limit the number of beams to be reported.

[0051] In some embodiments, the terminal device 120 obtains a first CBSR of the at least one CBSR from RRC signaling received from the network device 110. The first CBSR indicates a third number of first beam groups selected from a beam set between the terminal device and the network device and a fourth number of beams selected from the beam set.

[0052] As mentioned above, in the type-II codebook, the codebook subset restriction (CBSR) is introduced to reduce the channel state calculation complexity. In other words, some designated beams are selected from the whole set of beams. To reduce the overhead of CSI feedback, the CBSR mechanism can be introduced to determine the PMI.

[0053] In some embodiments, the first CBSR indicates a third number of beam groups (e.g., denoted as P) collectively having a fourth number of beams (e.g., denoted as H) from a total number of selected (N1*N2*O1*O2) beam sets.

[0054] In some embodiments, terminal device 120 may determine one or more PMIs based on the first CBSR, a number of antenna ports in a first dimension and a second dimension of an antenna array of the network device, and an oversampling factor corresponding to the number of antenna ports in the first dimension and the second dimension of the antenna array of the network device. For example, terminal device 120 may determine at least one of the first PMI and the second PMI.

[0055] In some embodiments, the first PMI (shown in Table 1) 1,1 ) and / or the second PMI (indicated by i in Table 1 1,2 In some embodiments, the first PMI refers to a beam group (e.g., denoted as G) of a second number of beams (e.g., denoted as F) selected from a fourth number of beams H. In some embodiments, the second PMI refers to a first number of beams (e.g., denoted as L, where L is an integer and may be 2, 3, 4, 5, or 6) selected from a beam group G of the second number of beams.

[0056] The process of determining the first PMI and the second PMI will be described in detail below with reference to FIGS. 3A-3C and 4, respectively.

[0057] In some embodiments, multiple beams between the terminal device 120 and the network device 110 in different spatial directions may be represented by a two-dimensional antenna array defined by N1, N2, and O1, O2. The first CBSR may indicate a third number of beam groups (e.g., denoted as P) collectively having a fourth number of beams (e.g., denoted as H) selected from the entire set of (N1*N2*O1*O2) beams. For different values ​​of N1 and N2, when the CBSR is configured, the total number of beams M available for the second PMI is different depending on the first CBSR.

[0058] In some embodiments, the number of bits of the second PMI feedback is based on the number of available beams (e.g., denoted as M), which in turn is based on a fourth number of beams H indicated by the CBSR. In some embodiments, the value of M is different for different values ​​of N1 and / or N2 and / or different configurations of the CBSR.

[0059] In some embodiments, in the codebook subset restriction configuration, the total number of beam groups is O1*O2 and the total number of beams is N1*N2*O1*O2. Each beam group has N1*N2 beams. The index of the beam groups in the antenna array is denoted by {r1(i),r2(i)}, where r1(i)=0,1,···,O1-1, r2(i)=0,1,···,O2-1, i=0,1,···,P-1. In each beam group, the beams are (r1(i)*N1+x1,r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, a third number of beam groups (denoted P, e.g., P is an integer and may be 1, 2, 3, 4, 5, or 6) are selected from the entire O1*O2 beam groups. In some embodiments, P is 4 and O1*O2 is 4. In this case, it may not be necessary to select the third number of beam groups P from the entire O1*O2 beam groups. Alternatively, the third number of beam groups P is the entire O1*O2 beam groups.

[0060] As an example, FIG. 3A shows an antenna array 3000 defined with N1=4 and N2=4, O1=4 and O2=4. In the antenna array 3000, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=256. There are 16 beams in each beam group. The index of the beam groups in the antenna array is represented as {r1(i), r2(i)}, where r1=0,1,···,O1-1, r2=0,1,···,O2-1, i=0,1,···,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1.

[0061] In Table 1, i 1,2 teeth,

number

Number

Number

[0062] In some embodiments, P (for example, P may be 2, 3, 4, 5 or 6) beam groups are selected. The indexes {r1(i), r2(i)} of the selected beam groups may be represented as any P combinations from {r1(i), r2(i)}, where r1(i)=0, 1,..., O1-1, r2(i)=0, 1,..., O2-1, and i=0, 1,..., P-1. In some embodiments, no matter which P beam groups are selected, the N1*N2 beams within one beam group are not orthogonal. For example, for i 1,2 with respect to, the first number of beams (L orthogonal beams) should be selected with the same x1, x2 from P beam groups, and for i 1,2 the number of bits is

Number

[0063] According to the first CBSR, as shown in FIG. 3A, four beam groups, 3100 to 3103, can be selected in the antenna array 3000. The indices {r1(i), r2(i)} of the selected beam groups are expressed as {0,0}, {0,2}, {1,2}, {2,3}, respectively. In this case, no matter which of the four beam groups is selected, the N1*N2 beams in one beam group are not orthogonal. 1,2 For each, select L orthogonal beams from the four beam groups with the same x1, x2 values, and 1,2 The number of bits in

number

number

[0064] In some embodiments, P beam groups are selected (e.g., P may be 2, 3, 4, 5, or 6). The indices {r1(i), r2(i)} of the selected beam groups may be represented as any P combinations from {r1(i), r2(i)}, where r1(i)=0,1,...,O1-1, r2(i)=0,1,...,O2-1, i=0,1,...,P-1. In some embodiments, no matter which P beam groups are selected, i 1,2 The number of bits in

number

[0065] In some embodiments, P (e.g., P may be 2, 3, 4, 5, or 6) beam groups are selected. The indices {r1(i), r2(i)} of the selected beam groups may be represented as any P combinations from {r1(i), r2(i)}, where r1(i)=0, 1, ..., O1-1, r2(i)=0, 1, ..., O2-1, i=0, 1, ..., P-1. In some embodiments, no matter which P beam groups are selected, i 1,2 The number of bits in

number

[0066] In some embodiments, P beam groups are selected (e.g., P may be 2, 3, 4, 5, or 6). The indices {r1(i), r2(i)} of the selected beam groups may be represented as any P combinations from {r1(i), r2(i)}, where r1(i)=0, 1, ..., O1-1, r2(i)=0, 1, ..., O2-1, i=0, 1, ..., P-1. In some embodiments, no matter which P beam groups are selected, i 1,2 The number of bits in

number

[0067] In some embodiments, when N1=4 and N2=2, i 1,2 The total number of beams available for depends on the group selected in the first CBSR. According to Table 2, if N1=4 and N2=2, then O1=4 and O2=4.

[0068] In this case, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=128. Each beam group has 8 beams. Of the total N1*N2*O1*O2=128 beams, each beam group contains N1*N2=8 orthogonal beams. In this case, the index of the beam group selected based on the first CBSR is i 1,2 This may result in a different number of orthogonal beams available.

[0069] As another example, FIG. 3B shows an antenna array 3001 defined by N1=4 and N2=2, O1=4 and O2=4. In the antenna array 3001, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=128. There are 8 beams in each beam group for CBSR. Similar to the antenna array 3000 shown in FIG. 3A, the index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,···,O1-1, r2=0,1,···,O2-1, i=0,1,···,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1.

[0070] In response to the first CBSR, four beam groups, groups 3200-3203, may be selected in the antenna array 3001 as shown in FIG. 3B. The indices {r1(i), r2(i)} of the selected beam groups may be represented as {0,0}, {0,2}, {1,2}, {2,3}, respectively. It should be understood that the indices {r1(i), r2(i)} of the selected beam groups are for illustrative purposes only, without implying any limitation. To implement an embodiment of the present disclosure, the indexes {r1(i), r2(i)} of the selected beam groups may be any P combinations from the set ({0,0}, {0,1}, {0,2}, {0,3}, {1,0}, {1,1}, {1,2}, {1,3}, {2,0}, {2,1}, {2,2}, {2,3}, {3,0}, {3,1}, {3,2}, {3,3}). The beams at corresponding positions in the four beam groups may be represented as (a1,b1), (a2,b2), (a3,b3), and (a4,b4). If the indexes associated with the corresponding positions of the beams satisfy the following equation (4) or (5), the beams will be orthogonal to each other.

number

[0071] In this way, among the four beams 3210 to 3213 shown in FIG. 3B, beam 3210 and beam 3211 are not orthogonal. Therefore, among beams 3210 to 3213 of beam groups 3200 to 3203, when beam 3210 of beam group 3200 is selected, beam 3212 of beam group 3202 will be selected. Similarly, when beam 3211 of beam group 3201 is selected, beam 3213 of beam group 3203 will be selected. Therefore, in the case shown in FIG. 3B, i 1,2 The number of beams available for i is M=2, so 1,2 About

number

number

number

[0072] FIG. 3C shows a further example of an antenna array similarly defined by N1=4 and N2=2, O1=4 and O2=4. In the antenna array 3002, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=128. There are 8 beams in each beam group. Similar to the antenna array 3000 shown in FIG. 3A and FIG. 3B, the index of the beam group may be expressed as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1.

[0073] In response to the first CBSR, four beam groups, groups 3300-3303, may be selected in the antenna array 3002 as shown in FIG. 3B. The indices {r1(i), r2(i)} of the selected beam groups may be represented as {0,0}, {0,1}, {0,3}, {3,3}, respectively. It should be understood that the indices {r1(i), r2(i)} of the selected beam groups are for illustrative purposes only, without implying any limitation. The indexes of the selected beam groups {r1(i), r2(i)} may be any P combinations from the set of ({0,0}, {0,1}, {0,2}, {0,3}, {1,0}, {1,1}, {1,2}, {1,3}, {2,0}, {2,1}, {2,2}, {2,3}, {3,0}, {3,1}, {3,2}, {3,3}) to implement the embodiments of the present disclosure. The beams at corresponding positions in the four beam groups may be represented as (a1,b1), (a2,b2), (a3,b3), and (a4,b4). As described above, if the indexes associated with the corresponding positions of the beams satisfy equation (4) or (5), the beams will be orthogonal to each other.

[0074] 3C, beam 3310, beam 3312 and beam 3213 are orthogonal to each other. Therefore, among beams 3310-3313 of beam groups 3300-3303, when beam 3310 of beam group 3300 is selected, beam 3312 of beam group 3302 and beam 3213 of beam group 3302 are selected. When beam 3311 of beam group 3301 is selected, there are no beams in the other three beam groups that are orthogonal to beam 3311.

[0075] As a result, in the case shown in Figure 3C, i 1,2 The number of beams available for i is M=3, so 1,2 About

number

number

number

[0076] In some embodiments, when N1=4 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=128. There are 8 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,2 The number of beams available for i is M, 1,2 The number of bits in

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[0077] In some embodiments, when N1=3 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=96. There are 6 beams in each beam group for CBSR. Here, the index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,2 The number of beams available for i is M, 1,2 The number of bits in

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[0078] In some embodiments, when N1=6 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=192. There are 12 beams in each beam group for CBSR. Here, the index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,2 The number of beams available for i is M, 1,2 The number of bits in

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[0079] In some embodiments, when N1=8 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=256. There are 16 beams in each beam group for CBSR. Here, the beam group index may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,2 The number of beams available for i is M, 1,2 The number of bits in

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[0080] In some embodiments, when N1=2, N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=64. There are four beams in each beam group for CBSR. Here, the index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,2 The number of beams available for i is M, 1,2 The number of bits in

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[0081] In some embodiments, for other configurations of N1 and N2 shown in Table 2, 1,2 It is possible to determine the maximum number of beams available for

[0082] In some embodiments, for example, when N2=1, N1=4, the corresponding oversampling factors are O1=4, O2=1. In this case, the total number of beam groups is O1*O2=4, and the total number of beams is N1*N2*O1*O2=16. Each beam group has four beams. Since the antenna array in this case is divided into only four groups, it is necessary to select L orthogonal beams with the same x1, x2 values ​​from the four groups. That is, i 1,2 The number of beams available for is M = 4. In this case, M = N1 * N2. Therefore, when N2 = 1 and N1 = 4, i 1,2 There is no reduction in overhead for

[0083] In some embodiments, as another example, when N2=2 and N1=2, the corresponding oversampling factors are O1=4 and O2=4. Similar to the example shown in FIGS. 3B and 3C, i 1,2The total number of beams available for depends on the group selected. If r2(i)={0,2} or {1,3} and r1(i)={0,2} or {1,3}, then M=4. If r2(i)={0,1} or {2,3} or {1,2} and r1(i)={0,2} or {1,3}, then M=2. If r1(i)={0,1} or {2,3} or {1,2} and r2(i)={0,2} or {1,3}, then M=2. If r1(i)={0,1} or {2,3} or {1,2} and r2(i)={0,1} or {2,3} or {1,2}, then M=1. i 1,2 The maximum number of beams available for is M=4.

[0084] In some embodiments, as a further example, if N2=3 and N1=4, the corresponding oversampling factors are O1=4 and O2=4. Similar to the examples shown in FIGS. 3B and 3C, i 1,2 The total number of beams available for depends on the group selected. If r1(i) for i=0,1,2,3 is the same, then M=3, otherwise M=4. 1,2 The maximum number of beams available for is M=4.

[0085] In some embodiments, as another example, when N2=6 and N1=2, the corresponding oversampling factors are O1=4 and O2=4. In this case, if r2(i) for i=0,1,2,3 is the same, M=6. If r1(i) for i=0,1,2,3 is the same, M=2. If r1(i) has three values ​​and r2(i) has two values, M=7. If r1(i) has two values ​​and r2(i)={0,2} or {1,3}, M=8. i 1,2 The maximum number of beams available for is M=8.

[0086] In some embodiments, as another example, when N2=8 and N1=2, the corresponding oversampling factors are O1=4 and O2=4. In this case, if r2(i) for i=0, 1, 2, 3 is the same, M=8. If r1(i) for i=0, 1, 2, 3 is the same, M=2. Also, if i 1,2The maximum number of beams available for is M=8.

[0087] In each case of the N1, N2 configuration shown in Table 2, it can be understood that it is not necessary to determine the value of M for each N1, N2 configuration situation. Conversely, if the maximum value M for one N1, N2 configuration is determined and the determined M is smaller than the value of N1*N2, i 1,2 The feedback overhead can be reduced for

[0088] In some embodiments, for different values ​​of N1 and N2, when CBSR is configured, the number K of beam groups available to the first PMI according to the first CBSR is not greater than O1*O2. For example, 1,1 The number of bits in

number

[0089] As an example, FIG. 4 shows an antenna array 4000 defined with N1=4 and N2=2, O1=4 and O2=4. In the antenna array 4000, the total number of beam groups is O1*O2=16, and the total number of beams is N1*N2*O1*O2=128. There are 8 beams in each beam group. The index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,···,O1-1, r2=0,1,···,O2-1, i=0,1,···,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1.

[0090] According to the first CBSR, four beam groups, groups 4100-4103, can be selected in the antenna array 4000 as shown in FIG. 4. The indices {r1(i), r2(i)} of the selected beam groups are represented as {0,0}, {0,1}, {0,2}, {0,3}, respectively. In other words, r2(i) for i=0,1,2,3 is the same. As mentioned above, if the indices associated with the corresponding positions of the beams satisfy equation (4) or (5), the beams will be orthogonal to each other. For example, in this case, if a beam, for example beam 4110, is selected from beam group 4100, then of the 15 beam groups, only seven other beam groups, namely beam groups 4102, 4104-4106, and 4107-4109, contain beams that are orthogonal to beam group 4110. Thus, i 1,1 The number of beam groups available for i is 8, which is less than the value of O1*O2. 1,1 The feedback overhead for may be reduced.

[0091] Continuing with the case of N1=4 and N2=2, O1=4 and O2=4, similarly, if r1(i) for i=0,1,2,3 is the same, then K=8. If r1(i) has two values ​​and r2(i)={0,2} or {1,3}, then K=8. Otherwise, K=16.

[0092] In some embodiments, as another example, when N2=2, N1=2, the corresponding oversampling factors are O1=4, O2=4. In this case, if r2(i) for i=0,1,2,3 is the same, then K=8. If r1(i) for i=0,1,2,3 is the same, then K=8. If r2(i) has two values ​​and r1(i) has two values, then K=4 unless r2(i)={0,2} or {1,3} and r1(i)={0,2} or {1,3}. Otherwise, K=8.

[0093] In some embodiments, as another example, if N2=3, N1=4, the corresponding oversampling factors are O1=4, O2=4. In this case, if r2(i) for i=0,1,2,3 is the same, then K=12. Otherwise, K=16.

[0094] As another example, in some embodiments, if N2=2, N1=3, the corresponding oversampling factors are O1=4, O2=4. In this case, if r2(i) for i=0,1,2,3 is the same, then K=8. If r1(i) for i=0,1,2,3 is the same, then K=12. If r1(i) has two values ​​and r2(i)={0,2} or {1,3}, then K=12. Otherwise, K=16.

[0095] In some embodiments, the terminal device 120 also obtains a second CBSR from the RRC signaling received from the network device 110, the second CBSR indicating a fifth number of second beam groups selected from the beam set and a sixth number of beams selected from the beam set. In some embodiments, the second CBSR may refer to a limit on the amplitude value of one beam.

[0096] In some embodiments, when N1=4 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=128. There are 8 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i),r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1,r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively.1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0097] In some embodiments, when N1=3 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=96. There are 6 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i),r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1,r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0098] In some embodiments, when N1=6 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=192. There are 12 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0099] In some embodiments, when N1=8 and N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=256. There are 16 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0100] In some embodiments, when N1=2, N2=2, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=64. There are four beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i),r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1,r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0101] In some embodiments, when N1=4 and N2=3, the total number of beam groups is O1*O2=16 and the total number of beams is N1*N2*O1*O2=192. There are 12 beams in each beam group for CBSR. The index of the beam group may be represented as {r1(i), r2(i)}, where r1=0,1,...,O1-1, r2=0,1,...,O2-1, i=0,1,...,P-1. In each beam group, the beams are (r1(i)*N1+x1, r2(i)*N2+x2), where x1=0,1,...,N1-1, x2=0,1,...,N2-1. In some embodiments, when P=4, the indices {r1(i), r2(i)} of the four selected beam groups are represented as {r1(0), r2(0)}, {r1(1), r2(1)}, {r1(2), r2(2)}, and {r1(3), r2(3)}, respectively. 1,1 The number of beam groups available for i is K, 1,1 The number of bits in

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[0102] In some embodiments, the terminal device may determine a third PMI based on the first PMI, the second PMI, and the second CBSR. The third PMI indicates at least one wideband amplitude coefficient of a seventh number of beams determined based on the first PMI, the second PMI, and the second CBSR.

[0103] As described above, i 1,2 Assume that the number M of available values for i 1,1 and the number K of available values for i 1,1 and i 1,2 have been determined. According to the second CBSR, four beam groups can be selected in the antenna array. The index of the beam group selected in the antenna array may be represented as {N1*r_1i + x, N2*r_2i + y}, where i = 0, 1, 2, 3, x = 0, 1, 2,..., N1 - 1, and y = 0, 1, 2,..., N2 - 1. When the values of x and y are constant and i = 0, 1, 2, 3, the number of non-zero amplitude beams in the selected beam group is called W. If W < L, sufficient beams cannot be selected. In other words, the beams with the values of x and y cannot be used and will not be selected. i 1,1 For the determined number of beams given by i 1,2 and i 1,1 let Z be the number of (x, y) pairs in the beam group selected based on the second CBSR, and when W < L is satisfied, i 1,2 the number of available values for i

[0104] Usually, the interval between the selected beams for one terminal device should not be too large. Therefore, in some embodiments, the range of the interval between orthogonal beams in the antenna array is determined, starting from N1*N2, i 1,2FIG. 5 shows an antenna array 500.

[0105] As can be seen from FIG. 5, there are 16 beam groups in the antenna array 500. In different beam groups, the beams spaced apart from each other by O1 are orthogonal to each other. For example, if N1=4, N2=4, O1=4, O2=4, the beams in the beam group 5100 are orthogonal to the corresponding beams in other beam groups of the antenna array 500. In a normal situation, the number of available beams L is 16. If the spacing between the mutually orthogonal beams is limited, for example, the spacing d=2O1, the number of available beams L is limited to 9. 1,2 About

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[0106] In some embodiments, the terminal device 120 may further determine a fourth PMI, the fourth PMI indicating at least one subband amplitude coefficient of the seventh number of beams.

[0107] Refer to Table 1. 1,4,1 may be considered as a broadband indication of the amplitude coefficient of each beam in the L beams, and i 2,2,1 may be considered as a subband indication of the beam phase coefficients from the 2L-1 beams in the subbands with non-zero broadband amplitude values. 2,2,1 About M l represents the number of beams that have a non-zero broadband amplitude coefficient.

[0108] The CSI report may include a first CSI portion and a second CSI portion. In general, the number of non-zero wideband amplitude coefficients M l Considering the overhead of reporting, in the first CSI part, l In some embodiments, the wideband amplitude coefficient (i.e., i 1,4,1 ) is reported to the network device in the first CSI part. Therefore, the number of beams with non-zero broadband amplitude coefficients (i.e., M l ) does not need to be reported.

[0109] The mapping order of the CSI fields for the first CSI part is shown in Table 3 below. [Table 3]

[0110] As mentioned above, for the subband amplitude coefficients, the overhead depends on the number of non-zero wideband amplitude coefficients. However, even if some wideband amplitude coefficients are non-zero, these wideband amplitude coefficients are not large enough. Therefore, for these wideband amplitude coefficients, there is no need to adjust the subband amplitude coefficients.

[0111] In some embodiments, a threshold may be further set on the number of non-zero wideband amplitude coefficients. In some embodiments, the threshold is:

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[0112] 2, in block 230, the terminal device 120 transmits at least one PMI to the network device 120. For example, the at least one PMI is transmitted to the network device 120 via a physical uplink control channel (PUCCH).

[0113] As can be seen from the above, the embodiments of the present disclosure provide a solution for reducing the overhead of CSI feedback by introducing CBSR into the feedback. 1,2 , i 1,1 , i 1,4,1 and i 2,1,1 The feedback overhead is significantly reduced for PMIs associated with

[0114] 6 illustrates a flowchart of an example method 600 for reducing channel state information (CSI) feedback overhead in accordance with some embodiments of the present disclosure. The method 600 may be implemented in the network device 110 illustrated in FIG. 1. For purposes of explanation, the method 600 is described from the perspective of the network device 110 with reference to FIG. 1.

[0115] At block 610, the network device 110 transmits a codebook configuration and a reference signal to the terminal device, where the codebook configuration indicates at least one codebook subset restriction (CBSR).

[0116] In block 620, the network device 110 receives at least one precoding matrix indicator (PMI) associated with a plurality of beams selected from a set of beams between the terminal device and the network device based at least in part on at least one CBSR, the at least one PMI being determined by the terminal device based on a reference signal.

[0117] Further, in some embodiments, the network device 110 determines a target beam from the at least one PMI and transmits a signal to the terminal device via the target beam.

[0118] Finally, the principles and implementations of the present disclosure are described in detail below with reference to Fig. 7. Fig. 7 shows a process 700 for UCI transmission according to an embodiment of the present disclosure. For illustrative purposes, the process 700 is described with reference to Fig. 1. The process 700 involves the network device 110 and the terminal device 120 of Fig. 1.

[0119] The network device 110 transmits (705) a codebook configuration and a reference signal to the terminal device 120. The codebook configuration indicates at least one codebook subset restriction (CBSR). Various parameters associated with the channel configuration may be obtained by the terminal device 120.

[0120] The terminal device 120 determines at least one precoding matrix indicator (PMI) associated with a plurality of beams selected from a set of beams between the terminal device and the network device based at least in part on the at least one CBSR (710). To determine at least one PMI associated with a certain beam or beam group, the terminal device 120 obtains the number of antenna ports in the first and second dimensions of the antenna array of the network device 110 and an oversampling factor corresponding to the number of antenna ports in the first and second dimensions of the antenna array of the network device 110 based on the RRC signaling received from the network device. Furthermore, the terminal device 120 obtains the first CBSR and the second CBSR.

[0121] The terminal device 120 transmits (715) the at least one PMI to the network device 110. The network device 110 determines (720) a target beam from the at least one PMI and transmits (725) a signal to the terminal device 120 via the target beam.

[0122] It can be seen that the embodiments of the present disclosure provide a solution for reducing the overhead of CSI feedback by introducing CBSR in the feedback. 1,2 , i 1,1 , i 1,4,1 and i 2,1,1 The feedback overhead is significantly reduced for PMIs associated with

[0123] 8 is a simplified block diagram of a device 800 suitable for implementing embodiments of the present disclosure. The device 800 can be considered as a further exemplary implementation of the network device 110 or the terminal device 120 shown in FIG. 1. Thus, the device 800 can be implemented in the network device 110 or the terminal device 120, or as at least a part of the network device 110 or the terminal device 120.

[0124] As shown, the device 800 comprises a processor 810, a memory 820 connected to the processor 810, a suitable transmitter (TX) and receiver (RX) 840 connected to the processor 810, and a communication interface connected to the TX / RX 840. The memory 810 stores at least a portion of a program 830. The TX / RX 840 is for bidirectional communication. The TX / RX 840 has at least one antenna to facilitate communication, although in practice, the access node referred to in this application may have several. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a Relay Node (RN), or an Uu interface for communication between an eNB and a terminal device.

[0125] The program 830 is envisioned to include program instructions that, when executed by an associated processor 810, enable the device 800 to operate according to embodiments of the present disclosure, as described herein with reference to Figures 2-7. The embodiments of the present disclosure may be implemented by computer software executable by the processor 810 of the device 800, or by hardware, or by a combination of software and hardware. The processor 810 may be configured to perform various embodiments of the present disclosure. Furthermore, the combination of the processor 810 and the memory 820 may form a processing means 850 suitable for performing various embodiments of the present disclosure.

[0126] The memory 820 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as, by way of non-limiting example, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Although only one memory 820 is shown in the device 800, there may be several physically separate memory modules. The processor 810 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 800 may have multiple processors, such as application specific integrated circuit chips time-slaved to a clock that synchronizes the main processor.

[0127] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described using block diagrams, flow charts, or some other graphical representations, it is understood that these blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting examples, hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controller or other computing device, or combinations thereof.

[0128] The present disclosure further provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions that execute on a target real or virtual processor device, such as those included in a program module, to perform a process or method described above with reference to any of Figures 2-11. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for a program module may be executed on a local device or a distributed device. In a distributed device, the program modules may be located in both local and remote storage media.

[0129] The program codes for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes are provided to a processor or controller of a general purpose computer, a special purpose computer, or other programmable data processing apparatus, such that when the program codes are executed by the processor or controller, the functions / operations defined in the flowcharts and / or block diagrams are realized. The program codes may be executed entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine, or entirely on a remote machine or server.

[0130] The program code may be embodied on a machine-readable medium, which may be any tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium includes, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include an electrical connection by one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0131] Furthermore, although operations are depicted in the figures in a particular order, this should not be understood as requiring that such operations be performed in the particular order or sequential order depicted, or that all of the depicted operations be performed, to achieve desired results. In certain situations, multitasking and parallel processing may be advantageous. Similarly, although the above description includes some specific implementation details, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features specific to certain embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0132] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined by the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. 1. A method performed on a terminal device, comprising: receiving a codebook configuration from a network device indicating a first codebook subset restriction (CBSR) and a second CBSR; receiving a reference signal from the network device; transmitting a first precoding matrix indicator (PMI) and a second PMI to the network device based on the reference signal; Equipped with the first CBSR indicates a first beam group, the second CBSR indicates a second beam group, the first PMI is further determined based on the first CBSR, and the second PMI is further determined based on the second CBSR. method.

2. receiving the codebook configuration from an RRC signaling. The method of claim 1.

3. determining a number of antenna ports in a first dimension (N1), a number of antenna ports in a second dimension (N2), an oversampling factor (O1) corresponding to the number of antenna ports in the first dimension, and an oversampling factor (O2) corresponding to the number of antenna ports in the second dimension; Further preparation, The number of beams in the beam set is the product of N1, N2, O1, and O2. The method of claim 1.

4. 1. A method performed on a network device, comprising: transmitting a codebook configuration to a terminal device, the codebook configuration indicating a first codebook subset restriction (CBSR) and a second CBSR; transmitting a reference signal to the terminal device; receiving a first precoding matrix indicator (PMI) and a second PMI from the terminal device based on the reference signal; Equipped with the first CBSR indicates a first beam group, the second CBSR indicates a second beam group, the first PMI is further determined based on the first CBSR, and the second PMI is further determined based on the second CBSR. method.

5. transmitting the codebook configuration via RRC signaling. The method according to claim 4.

6. determining a number of antenna ports in a first dimension (N1), a number of antenna ports in a second dimension (N2), an oversampling factor (O1) corresponding to the number of antenna ports in the first dimension, and an oversampling factor (O2) corresponding to the number of antenna ports in the second dimension; Further preparation, The number of beams in the beam set is the product of N1, N2, O1, and O2. The method according to claim 4.

7. A terminal device comprising a processor configured to carry out the method according to any one of claims 1 to 3.

8. A network device comprising a processor configured to carry out the method of any one of claims 4 to 6.

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