Communication method and apparatus for feeding back pre-coding matrix

Abstract

A communication method and apparatus for feeding back a pre-coding matrix. The method comprises: a first apparatus receives a first reference signal; and the first apparatus sends first information. The first information indicates a first vector and a first matrix. The first vector belongs to M vectors, wherein M is a positive integer. The first matrix is used for indicating a recurrence relation between different vectors among the M vectors. The M vectors correspond to M sub-bands, each vector among the M vectors is a coefficient corresponding to a pre-coding matrix for one sub-band among the M sub-bands, and a pre-coding matrix for each sub-band among the M sub-bands is obtained on the basis of the first reference signal. In this way, a second apparatus can accurately determine the M vectors on the basis of the first vector and the recurrence relation, thereby determining pre-coding matrices for the M sub-bands. In the method, the first apparatus may not send each vector among the M vectors, thereby reducing the overhead of feeding back pre-coding matrices.

Description

A communication method and apparatus for feedback precoding matrices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410946606.8, filed on July 12, 2024, entitled "A Communication Method and Apparatus for Feedback Precoding Matrix", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method and apparatus for feedback precoding matrices. Background Technology

[0004] Multiple-input multiple-output (MIMO) technology is a key technology in wireless communication, capable of meeting the demands of high-speed transmission. This technology can utilize spatial resources to enable signals to achieve array gain, multiplexing and diversity gain, and interference cancellation gain in space without increasing system bandwidth, thereby improving the capacity and spectral efficiency of the communication system.

[0005] In MIMO technology, the receiving device can feed back a precoding matrix determined by the receiving device to the transmitting device based on the received reference signal. How to reduce the overhead of feeding back the precoding matrix requires further discussion. Summary of the Invention

[0006] This application provides a communication method and apparatus for reducing the overhead of the feedback precoding matrix.

[0007] In a first aspect, embodiments of this application provide a communication method that can be applied to a first device.

[0008] In some examples, the first device may be a terminal, or a device applicable to a terminal (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, also known as a baseband chip, or a system-on-chip (SoC) chip or system-in-package (SIP) chip containing a modem core), a chip system, or a processor), or a logical node, logical module, or software capable of implementing all or part of the terminal's functions. Optionally, this example may be applicable to downlink MIMO.

[0009] In other examples, the first device may be an access network device, or a device that can be applied to an access network device (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the functions of the access network device. Optionally, this example may be applicable to uplink MIMO.

[0010] The method may include: a first device receiving a first reference signal; the first device transmitting first information; wherein the first information indicates a first vector and a first matrix; the first vector belongs to M vectors, where M is a positive integer; the first matrix is ​​used to indicate the recursive relationship between different vectors among the M vectors; the M vectors correspond to M subbands, each vector in the M vectors is a coefficient corresponding to the precoding matrix of one of the M subbands, and the precoding matrix of each of the M subbands is obtained based on the first reference signal.

[0011] Using this method, the first device can send first information, which indicates one of the M vectors (i.e., the first vector) and the recursive relationship between the different vectors in the M vectors. Thus, the second device can accurately determine the M vectors based on the first vector and the recursive relationship, thereby determining the precoding matrices for the M subbands. In this method, the first device may not need to send every single one of the M vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0012] When applied to massive MIMO (Multi-Match MIMO) technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix of each sub-band increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. Similarly, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band. In this way, the overhead of the feedback precoding matrix does not increase with the number of sub-bands, thus significantly reducing the overhead of the feedback precoding matrix.

[0013] Alternatively, since the first device may not send each of the M vectors, the method can improve the accuracy of the indicated first vector and / or the first matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the M vectors recovered by the second device.

[0014] Secondly, embodiments of this application provide a communication method that can be applied to a second device.

[0015] In some examples, the second device may be an access network device, or a device that can be applied to an access network device (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the functions of the access network device. Optionally, this example may be applicable to downlink MIMO.

[0016] In other examples, the second device may be a terminal, or a device that can be applied to a terminal (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the terminal functions. Optionally, this example may be applicable to uplink MIMO.

[0017] The method may include: a second device transmitting a first reference signal; and a second device receiving first information. The first information indicates a first vector and a first matrix. The first vector belongs to M vectors, where M is a positive integer. The first matrix indicates the recursive relationship between different vectors among the M vectors. The M vectors correspond to M subbands. Each of the M vectors is a coefficient corresponding to the precoding matrix of one of the M subbands. The precoding matrix of each of the M subbands is obtained based on the first reference signal.

[0018] Using this method, the second device can receive first information, which indicates one of the M vectors (i.e., the first vector) and the recursive relationship between the different vectors in the M vectors. Thus, the second device can accurately determine the M vectors based on the first vector and the recursive relationship, thereby determining the precoding matrices for the M subbands. In this method, the first device does not need to send every single one of the M vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0019] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix of each sub-band increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. As another example, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band. In this way, the overhead of the feedback precoding matrix does not increase with the number of sub-bands, thus significantly reducing the overhead of the feedback precoding matrix.

[0020] Alternatively, since the first device may not send each of the M vectors, the method can improve the accuracy of the indicated first vector and / or the first matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the M vectors recovered by the second device.

[0021] Thirdly, embodiments of this application provide a communication method that can be applied to a first device.

[0022] In some examples, the first device may be a terminal, or a device that can be applied to a terminal (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the terminal functions. Optionally, this example may be applicable to downlink MIMO.

[0023] In other examples, the first device may be an access network device, or a device that can be applied to an access network device (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the functions of the access network device. Optionally, this example may be applicable to uplink MIMO.

[0024] The method may include: a first device receiving a first reference signal; the first device transmitting first information; wherein the first information indicates a first vector and a second matrix; the first vector belonging to N vectors, where N is a positive integer; and the second matrix indicating the recursive relationship between different vectors among the N vectors; the N vectors corresponding to N time units, each vector being a coefficient of the precoding matrix corresponding to one of the N time units, and the precoding matrix of each of the N time units being obtained based on the first reference signal.

[0025] Optionally, the first reference signal may be a reference signal on one or more time units, and the precoding matrix of each time unit in the N time units is obtained based on the reference signals on one or more time units.

[0026] Using this method, the first device can send first information, which indicates one of N vectors (i.e., the first vector) and the recursive relationship between different vectors among the N vectors. Thus, the second device can accurately determine the N vectors based on the first vector and the recursive relationship, thereby determining the precoding matrix for the N time units. In this method, the first device may not need to send every single one of the N vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0027] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one time unit, instead of transmitting the coefficients corresponding to the precoding matrix of each subsequent time unit, thus significantly reducing the overhead of the feedback precoding matrix.

[0028] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated first vector and / or second matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0029] Fourthly, embodiments of this application provide a communication method that can be applied to a second device.

[0030] In some examples, the second device may be an access network device, or a device that can be applied to an access network device (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the functions of the access network device. Optionally, this example may be applicable to downlink MIMO.

[0031] In other examples, the second device may be a terminal, or a device that can be applied to a terminal (e.g., a module, communication module, circuitry or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that can implement all or part of the terminal functions. Optionally, this example may be applicable to uplink MIMO.

[0032] The method may include: a second device transmitting a first reference signal; and a second device receiving first information. The first information indicates a first vector and a second matrix. The first vector belongs to N vectors, where N is a positive integer. The second matrix indicates the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0033] Optionally, the first reference signal may be a reference signal on one or more time units, and the precoding matrix of each time unit in the N time units is obtained based on the reference signals on one or more time units.

[0034] Using this method, the second device can receive first information, which indicates one of N vectors (i.e., the first vector) and the recursive relationship between different vectors among the N vectors. Thus, the second device can accurately determine the N vectors based on the first vector and the recursive relationship, thereby determining the precoding matrix for the N time units. In this method, the first device does not need to send every single one of the N vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0035] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one time unit, instead of transmitting the coefficients corresponding to the precoding matrix of each subsequent time unit, thus significantly reducing the overhead of the feedback precoding matrix.

[0036] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated first vector and / or second matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0037] Based on any one of the first to fourth aspects, in one possible design, the second device can send first indication information, and correspondingly, the first device can receive the first indication information. The first indication information is used to indicate the method of feedback channel state information (CSI). When the first indication information indicates that the CSI feedback method is a new method, the first device can send first information; correspondingly, the second device can receive the first information. Optionally, this design can be used for downlink MIMO. With this design, the first device can send first information to the second device according to the instruction of the second device. Furthermore, in this design, the second device can indicate the CSI feedback method to the first device, thus allowing the second device to flexibly manage the CSI feedback method of the first device.

[0038] Based on any one of the first to fourth aspects, in one possible design, the first device can send first indication information, and correspondingly, the second device can receive the first indication information. The first indication information is used to indicate the mode of CSI feedback. When the first indication information indicates that the CSI feedback mode is a new mode, the first device can send first information; correspondingly, the second device can receive the first information. Optionally, this design can be used for uplink MIMO. With this design, the first device can indicate to the second device that the CSI feedback mode is a new mode. Thus, after sending the first information to the second device, the second device can process the first information according to the new mode; for example, it can determine M vectors and / or N vectors based on the first information. Furthermore, in this design, the first device can indicate the CSI feedback mode to the second device, allowing the first device to flexibly manage the CSI feedback mode.

[0039] Based on the first or third aspect, in one possible design, the first device can acquire a correspondence between at least one condition and at least one mode, each of the at least one mode being a mode for feedback CSI. When a first condition among the at least one conditions is satisfied and corresponds to a new mode among the at least one modes, the first device can send first information; correspondingly, the second device can receive the first information. With this design, the first device can accurately determine whether to send the first information based on the correspondence. Furthermore, in this design, the second device does not need to indicate the mode for feedback CSI to the first device, thereby reducing signaling overhead.

[0040] Based on the first or third aspect, in one possible design, the first device can send first information when the first condition is met; correspondingly, the second device can receive the first information. With this design, the first device can accurately determine whether to send the first information based on the first condition. Furthermore, in this design, the second device does not need to instruct the first device on the method of feedback CSI, thereby reducing signaling overhead.

[0041] Based on the first or third aspect, in one possible design, the first condition includes at least one of the following: the number of transmitting antennas of the transmitting device is greater than or equal to a first threshold, and the transmitting device is a device that transmits signals according to the first information; the number of receiving antennas of the receiving device is greater than or equal to a second threshold, and the receiving device is a device that receives signals according to the first information; the number of transmitting antenna ports of the transmitting device is greater than or equal to a third threshold; the number of receiving antenna ports of the receiving device is greater than or equal to a fourth threshold; or, M is greater than or equal to a fifth threshold. This design provides multiple possible ways to fulfill the first condition, offering greater flexibility in implementation.

[0042] Based on any one of the first to fourth aspects, in one possible design, the first device can transmit second information; correspondingly, the second device can receive the second information. The second information can indicate whether the first device has the capability to provide feedback on CSI based on dynamic mode decomposition (DMD). Optionally, this design can be used for downlink MIMO. Thus, the second device can accurately determine whether the first device has the capability to provide feedback on CSI based on DMD based on the second information.

[0043] Based on any one of the first to fourth aspects, in one possible design, the second device can transmit third information; correspondingly, the first device can receive the third information. The third information can indicate whether the second device has the capability to provide feedback on CSI based on the DMD. Optionally, this design can be used for uplink MIMO. Thus, the first device can accurately determine whether the second device has the capability to provide feedback on CSI based on the DMD based on the third information.

[0044] Based on the first or second aspect, in one possible design, the first information may include a first vector and a first matrix. In this way, the second device can accurately determine the first vector and the first matrix based on the first information. Furthermore, in this design, the first information can directly indicate the first vector and the first matrix, thus eliminating the need for the second device to calculate and determine them, thereby reducing the computational complexity of the second device. Alternatively, the first information may include information that corresponds to the first vector and / or the first matrix. In this way, the second device can accurately determine the first vector and the first matrix based on the first information.

[0045] Based on the first or second aspect, in one possible design, the first information may include: a first vector, Λ1, and Ψ1. Here, Λ1 is a diagonal matrix; Ψ1 is a matrix obtained by eigenvalue decomposition of the first matrix, and Ψ1 has the same number of rows and columns as the first matrix. The first matrix has the same number of rows and columns. Λ1, Ψ1, and the first matrix can satisfy the following formula: G f =Ψ1*Λ1*Ψ1 H G f Let Ψ1 be the first matrix. H It is the conjugate transpose of Ψ1. Since G f =Ψ1*Λ1*Ψ1 H Therefore, in this design, the second device can accurately determine the first matrix based on Λ1 and Ψ1. Furthermore, in this design, the second device can accurately determine the first matrix based on Λ1, Ψ1, and Ψ1. H It can perform parallel computation of vectors other than the first vector among M vectors, thereby saving computation time and resources and reducing the amount of computation.

[0046] Alternatively, the first information may include: Ψ1 H The product of the first vector, Λ1, and Ψ1. Since Ψ1*Λ1*Ψ1 H Therefore, in this design, the second device can accurately determine the first matrix based on Λ1 and Ψ1. Furthermore, in this design, the second device can accurately determine the first matrix based on Λ1, Ψ1, and Ψ1. H This design allows for parallel computation of all vectors except the first vector among M vectors, thus saving computation time and resources and reducing computational complexity. Furthermore, in this design, the first device determines Ψ1. H *x 1,1 Thus, the second device can directly use Ψ1 H *x 1,1 The calculation results determine the vectors other than the first vector among the M vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0047] Based on the first or second aspect, in one possible design, the first vector is the coefficient corresponding to the precoding matrix of the first subband, and the first subband is the subband with the lowest frequency among the M subbands; the first matrix is ​​the recursive relationship between the vectors corresponding to the adjacent subbands among the M subbands. This design provides a possible example of the first vector and the first matrix, which is easy to implement.

[0048] Based on the first or second aspect, in one possible design, the coefficients corresponding to the precoding matrix of the k-th sub-band among the M sub-bands are x. k,1 Let k be any integer from 1 to M, and let the first matrix satisfy the following formula: G f =Y1*pinv(X1),

[0049] Among them, G f Let Y1 be the first matrix, and Y1 = [x 2,1 ,x 3,1 ,…,x M,1 ], X1 = [x 1,1 ,x 2,1 ,…,x M-1,1 ], pinv indicates the pseudo-inverse operation.

[0050] Through this design, the first device can accurately determine the first matrix, thereby accurately determining the recursive relationship between different vectors among M vectors.

[0051] Based on either the first or second aspect, in one possible design, the first information also indicates a second matrix. The first vector also belongs to N vectors, where N is a positive integer. The second matrix is ​​used to indicate the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0052] Optionally, the first reference signal may be a reference signal on one or more time units, and the precoding matrix of each time unit in the N time units is obtained based on the reference signals on one or more time units.

[0053] Using this method, a first device can transmit first information, which may indicate a portion of N vectors (e.g., a first vector) and a recursive relationship between different vectors among the N vectors. Thus, a second device can accurately determine the N vectors based on the first vector and the recursive relationship, thereby determining the precoding matrix for the N time units. In this method, the first device does not need to transmit N vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0054] Based on any one of the first to fourth aspects, in one possible design, the first information may include a first vector and a second matrix. Thus, the second device can accurately determine the first vector and the second matrix based on the first information. Furthermore, in one embodiment, the first information may directly indicate the first vector and the second matrix, thereby eliminating the need for the second device to calculate and determine them, thus reducing the computational complexity of the second device. Alternatively, the first information may include information corresponding to the first vector and / or the second matrix. In this case, the second device can accurately determine the first vector and the second matrix based on the first information.

[0055] Based on any one of the first to fourth aspects, in one possible design, the first information may include: a first vector, Λ2, and Ψ2. Here, Λ2 is a diagonal matrix; Ψ2 is the matrix obtained by eigenvalue decomposition of the second matrix, and Ψ2 has the same number of rows and columns as the second matrix. The second matrix has the same number of rows and columns. Λ2, Ψ2, and the second matrix satisfy the following formula: G t =Ψ2*Λ2*Ψ2 H G t For the second matrix, Ψ2 H It is the conjugate transpose of Ψ2. Since G t =Ψ2*Λ2*Ψ2 H Therefore, in this design, the second device can accurately determine the second matrix based on Λ2 and Ψ2. Furthermore, in this design, the second device can accurately determine the second matrix based on Λ2, Ψ2, and Ψ2. H It can perform parallel computation of all vectors except the first vector among N vectors, thereby saving computation time and resources and reducing the amount of computation.

[0056] Alternatively, the first information may include: Ψ2 H The product of the first vector, Λ2, and Ψ2. Since G t =Ψ2*Λ2*Ψ2 H Therefore, in this design, the second device can accurately determine the second matrix based on Λ2 and Ψ2. Furthermore, in this design, the second device can accurately determine the second matrix based on Λ2, Ψ2, and Ψ2. H This design allows for parallel computation of all vectors except the first vector among N vectors, thus saving computation time and resources and reducing computational complexity. Furthermore, in this design, the first device determines Ψ2. H *x 1,1 Thus, the second device can directly use Ψ2 H *x 1,1 The calculation results determine the vectors other than the first vector among N vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0057] Based on any one of the first to fourth aspects, in one possible design, the first vector is the coefficient corresponding to the precoding matrix of the first time unit, and the first time unit is the earliest subband among N time units; the second matrix is ​​the recursive relationship between the vectors corresponding to adjacent time units among the N time units. This design provides a possible example of the first vector and the second matrix, which is easy to implement.

[0058] Based on any one of the first to fourth aspects, in one possible design, the coefficients corresponding to the precoding matrix of the q-th time unit out of N time units are x. 1,q Let q take any integer from 1 to N, and let the second matrix satisfy the following formula: G t =Y2*pinv(X2),

[0059] Among them, G t For the second matrix, Y2 = [x 1,2 ,x 1,3 ,…,x 1,N ], X2 = [x 1,1 ,x 1,2 ,…,x 1,N-1 ], pinv indicates the pseudo-inverse operation.

[0060] Through this design, the first device can accurately determine the second matrix, thereby accurately determining the recursive relationship between vectors corresponding to adjacent time units in N time units.

[0061] Based on the first or second aspect, in one possible design, the second device transmits a first signal; correspondingly, the first device receives the first signal. The first signal is transmitted according to a first precoding matrix, which is determined based on the precoding matrices of some or all of the M subbands. The precoding matrices of the M subbands are determined based on M vectors. The first vector among the M vectors is determined based on first information, and the vectors other than the first vector among the M vectors are determined based on the first vector and the first matrix. Through this design, the second device can accurately determine the M vectors based on the first vector and the first matrix, thereby determining the precoding matrix used for transmitting the signal.

[0062] Based on the first or second aspect, in one possible design, the k-th vector among the M vectors is x. k,1 k takes integers from 1 to M, and the first vector is x. 1,1 x k,1 and x 1,1 Satisfies the following formula: x k,1 =G f k-1 *x 1,1 ,

[0063] Among them, G f Let G be the first matrix. f k-1 For G f k-1.

[0064] With this design, the second device can accurately determine M vectors.

[0065] Based on the third or fourth aspect, in one possible design, the second device transmits a first signal; correspondingly, the first device receives the first signal. The first signal is transmitted according to a first precoding matrix, which is determined based on the precoding matrices of some or all of the N time units. The precoding matrices of the N time units are determined based on N vectors, where the first vector is determined based on first information, and the vectors other than the first vector are determined based on the first vector and a second matrix. Through this design, the second device can accurately determine the N vectors based on the first vector and the second matrix, thereby determining the precoding matrix used to transmit the signal.

[0066] Based on the third or fourth aspect, in one possible design, the q-th vector among N vectors is x. 1,q q takes any integer from 1 to N, and the first vector is x. 1,1 x 1,q and x 1,1 Satisfies the following formula: x 1,q =G t q-1 *x 1,1 ,

[0067] Among them, G t G is the second matrix. t q-1 For G t q-1.

[0068] With this design, the second device can accurately determine N vectors.

[0069] Based on any one of the first to fourth aspects, in one possible design, the second device transmits a first signal; correspondingly, the first device receives the first signal. The first signal is transmitted according to a first precoding matrix, which is determined based on the following precoding matrices: precoding matrices for some or all of the M subbands, and precoding matrices for some or all of the N time units. Specifically, the precoding matrices for the M subbands are determined based on M vectors, where the first vector among the M vectors is determined based on first information, and the vectors other than the first vector among the M vectors are determined based on the first vector and the first matrix; the precoding matrices for the N time units are determined based on N vectors, where the first vector among the N vectors is determined based on the first information, and the vectors other than the first vector among the N vectors are determined based on the first vector and the second matrix. Through this design, the second device can accurately determine the M vectors based on the first vector and the first matrix, and accurately determine the N vectors based on the first vector and the second matrix, thereby determining the precoding matrix used for transmitting the signal.

[0070] Based on any one of the first to fourth aspects, in one possible design, the coefficients corresponding to the precoding matrix of the k-th sub-band at the q-th time unit are x. k,q k takes integers from 1 to M, q takes integers from 1 to N, and the first vector is x. 1,1 x k,q and x 1,1 Satisfies the following formula: x k,q =G t q-1 *G f k-1 *x 1,1 ,

[0071] Among them, G t G is the second matrix. t q-1 For G t q-1; G f Let G be the first matrix. f k-1 For G f k-1.

[0072] With this design, the second device can accurately determine the coefficients corresponding to the precoding matrix of the k-th sub-band in the q-th time unit.

[0073] Based on any one of the first to fourth aspects, in one possible design, the first device is a terminal or a device within a terminal, the second device is an access network device or a device within an access network device, and the first reference signal is a channel state information reference signal (CSI-RS); or, the first device is an access network device or a device within an access network device, the second device is a terminal or a device within a terminal, and the first reference signal is a sounding reference signal (SRS).

[0074] Fifthly, this application provides a communication device. This communication device can be a terminal, or a device applicable to a terminal (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software capable of implementing all or part of the terminal's functions; or, the communication device can be an access network device, or a device applicable to an access network device (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software capable of implementing all or part of the access network device's functions. This communication device possesses the functionality to implement any one of the first to fourth aspects described above.

[0075] In one possible design, the communication device includes modules, units, or means that perform the operations involved in any of the first to fourth aspects described above. These modules, units, or means can be implemented in software, hardware, or a combination of both. For example, the communication device includes an interface unit and a processing unit. The interface unit can be used to send and receive signals to enable communication between the communication device and other devices; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the interface unit can correspond to the operations involved in any of the first to fourth aspects described above.

[0076] In one possible design, the communication device includes a processor. The processor is capable of executing computer programs or instructions that, when executed, cause the communication device to implement the methods in any of the possible designs of any of the first to fourth aspects described above.

[0077] In one possible design, the communication device includes a processor and a memory, the memory of which can store necessary computer programs or instructions for implementing the functions involved in any of the first to fourth aspects described above. The processor can execute the computer programs or instructions stored in the memory, and when the computer programs or instructions are executed, cause the communication device to implement the methods in any of the possible designs of any of the first to fourth aspects described above.

[0078] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and to execute the methods in any possible design of any of the first to fourth aspects described above.

[0079] Sixthly, this application provides a communication system that may include a first device and a second device. The first device may execute the communication method provided in the first aspect, and the second device may execute the communication method provided in the second aspect; or, the first device may execute the communication method provided in the third aspect, and the second device may execute the communication method provided in the fourth aspect.

[0080] In some possible designs, the first device is a terminal and the second device is an access network device.

[0081] In other possible designs, the first device is an access network device and the second device is a terminal.

[0082] In a seventh aspect, this application provides a computer-readable storage medium storing a computer program or instructions, wherein when the computer program or instructions are executed, a method in any possible design of any of the first to fourth aspects described above is implemented.

[0083] Eighthly, this application provides a computer program product comprising computer program code, wherein when the computer program code is run, a method in any possible design of any of the first to fourth aspects described above is implemented.

[0084] Ninthly, this application provides a chip for reading a computer program stored in a memory to execute a method in any possible design of any of the first to fourth aspects described above.

[0085] The technical effects that can be achieved by any of the fifth to ninth aspects mentioned above can be described with reference to the technical effects that can be achieved by any possible design in any of the first to fourth aspects mentioned above. Where there is overlap, no further discussion will be given. Attached Figure Description

[0086] Figure 1 is an architecture diagram of a communication system provided in an embodiment of this application;

[0087] Figures 2A to 2C are schematic diagrams illustrating the relationships between several precoding matrices provided in the embodiments of this application;

[0088] Figure 3 is a flowchart of a communication method provided in an embodiment of this application;

[0089] Figures 4A to 4C are schematic diagrams of a method for determining M vectors provided in an embodiment of this application;

[0090] Figures 5A to 5C are schematic diagrams of a method for determining N vectors provided in an embodiment of this application;

[0091] Figure 6 is a schematic diagram of the method for determining M*N vectors provided in an embodiment of this application;

[0092] Figures 7 to 9 are flowcharts of several other communication methods provided in the embodiments of this application;

[0093] Figure 10 is a structural diagram of a communication device provided in an embodiment of this application;

[0094] Figure 11 is a structural diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0095] The technical solutions in the embodiments of this application will be described below with reference to the accompanying drawings. The technical solutions in the embodiments of this application can be applied to various communication systems, such as wireless local area networks (WLANs), wireless fidelity (Wi-Fi or WiFi) systems, fourth-generation (4G) mobile communication systems (such as long-term evolution (LTE) systems), fifth-generation (5G) mobile communication systems (such as new radio (NR) systems), or future communication systems. The methods provided in the embodiments of this application can be applied to terrestrial network communication systems or non-terrestrial network (NTN) communication systems. NTN communication systems can be, for example, satellite communication systems, and may also include unmanned aerial vehicles (UAVs), high-altitude platform stations (HAPS), and other aerial access network equipment; this application does not limit these aspects.

[0096] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches are also possible.

[0097] To facilitate understanding of the embodiments of this application, Figure 1 illustrates a possible, non-limiting system schematic diagram. As shown in Figure 1, the communication system 10 includes a radio access network (RAN) 100 and a core network (CN) 200. Optionally, the communication system 10 may also include the Internet 300.

[0098] RAN 100 includes at least one RAN node (110a and 110b in Figure 1, collectively referred to as 110) and at least one terminal (120a-120j in Figure 1, collectively referred to as 120). RAN 100 may also include other RAN nodes, such as wireless relay equipment and / or wireless backhaul equipment (not shown in Figure 1). Terminal 120 is wirelessly connected to RAN node 110. RAN node 110 is wirelessly or wired connected to core network 200. The core network equipment in core network 200 and RAN node 110 in RAN 100 can be different physical devices, or they can be the same physical device integrating core network logical functions and wireless access network logical functions.

[0099] RAN 100 can be a cellular system related to the 3rd Generation Partnership Project (3GPP), such as 4G, 5G mobile communication systems, or future-oriented evolution systems. RAN 100 can also be an open RAN (O-RAN or ORAN), a cloud radio access network (CRAN), or a WiFi system. RAN 100 can also be a communication system that integrates two or more of the above systems.

[0100] RAN node 110, sometimes referred to as RAN entity or access node, constitutes part of the communication system and assists terminals in achieving wireless access. Multiple RAN nodes 110 in communication system 10 can be of the same type or different types. In some scenarios, the roles of RAN node 110 and terminal 120 are relative. For example, network element 120i in Figure 1 can be a helicopter or drone, which can be configured as a mobile base station. For terminals 120j accessing RAN 100 through network element 120i, network element 120i is a base station; however, for base station 110a, network element 120i is a terminal. RAN node 110 and terminal 120 are sometimes both referred to as communication devices. For example, network elements 110a and 110b in Figure 1 can be understood as communication devices with base station functions, and network elements 120a-120j can be understood as communication devices with terminal functions.

[0101] RAN nodes can also be described in different ways, such as access network equipment. Unless otherwise specified in this application, access network equipment will be used as the term.

[0102] Access network equipment can be devices or modules located on the network side of the aforementioned communication system and possessing corresponding communication functions. Access network equipment typically contains communication modules, circuits, or chips that perform the corresponding communication functions. Access network equipment may also be configured with programs or instructions for performing the corresponding communication functions, as well as the corresponding programs or instructions themselves.

[0103] In one possible scenario, the access network equipment can be a base station (BS), an evolved NodeB (eNodeB or eNB), a transmitting point (TP), an access point (AP), a transmit / receive point (TRP), a mobile switching center, a next-generation NodeB (gNB), a next-generation base station in a future communication system, or an access node in a WiFi system, etc. The access network equipment can be a macro base station (as shown in Figure 1, 110a), a micro base station or indoor station (as shown in Figure 1, 110b), a relay node or donor node, or, in a CRAN scenario, a wireless controller, satellite, drone, balloon, or aircraft, etc. Optionally, the access network equipment can also be a server, wearable device, vehicle, or in-vehicle equipment, etc. For example, the access network equipment in vehicle-to-everything (V2X) technology can be a roadside unit (RSU). All or part of the functions of the access network equipment in this application can also be implemented through software functions running on hardware, or through virtualization functions instantiated on a platform (e.g., a cloud platform). The access network device in this application may also be a logical node, logical module, or software that can implement all or part of the functions of the access network device.

[0104] In another possible scenario, multiple access network devices collaborate to assist the terminal in achieving wireless access, with each device performing a portion of the base station's functions. For example, the access network devices can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU can be separate entities or included in the same network element, such as a baseband unit (BBU). The RU can be included in radio frequency equipment or radio frequency units, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0105] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called an open CU (O-CU), DU can also be called an open DU (O-DU), CU-CP can also be called an open CU-CP (O-CU-CP), CU-UP can also be called an open CU-UP (O-CU-UP), and RU can also be called an open RU (O-RU). Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0106] A terminal is a device or module that connects to the aforementioned communication system and possesses corresponding communication functions. A terminal can also be called a terminal device, user equipment (UE), mobile station, mobile terminal, wireless terminal device, subscriber unit, subscriber station, mobile station, remote station, user terminal, user agent, or user device, etc. A terminal typically contains communication modules, circuits, or chips that perform the corresponding communication functions. The terminal may also be configured with programs or instructions for performing these communication functions.

[0107] Terminals can be widely used in various scenarios, such as device-to-device (D2D), V2X communication, machine-type communications (MTC), the Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. Wearable devices, also known as wearable smart devices or smart wearable devices, are a general term for devices that utilize wearable technology to intelligently design and develop everyday wearables. Terminals used in vehicles are called in-vehicle terminal devices, which include, for example, transportation vehicles with wireless communication capabilities, communication modules, or on-board units (OBUs).

[0108] For example, a terminal may include a mobile phone (or "cellular" phone), a computer with a mobile terminal device, or a portable, pocket-sized, handheld, or computer-embedded mobile device. For instance, a terminal may be a Personal Communication Service (PCS) phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), or other similar devices. A terminal may also include restricted devices, such as devices with limited power consumption, limited storage capacity, or limited computing power. For example, a terminal may be an information sensing device such as a barcode scanner, radio frequency identification (RFID), a sensor, a global positioning system (GPS), or a laser scanner. The embodiments of this application do not limit the device form of the terminal.

[0109] Communication between access network devices and terminals follows a specific protocol layer structure. This protocol layer may include a control plane protocol layer and a user plane protocol layer. The control plane protocol layer may include at least one of the following: radio resource control (RRC) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, medium access control (MAC) layer, or physical (PHY) layer, etc. The user plane protocol layer may include at least one of the following: service data adaptation protocol (SDAP) layer, PDCP layer, RLC layer, MAC layer, or physical layer, etc.

[0110] The correspondence between network elements and their achievable protocol layer functions in the ORAN system can be found in Table 1 below.

[0111] Table 1

[0112] In this application, core network equipment refers to equipment in the core network that provides service support for terminals. For example, if CN200 is the core network of a future communication system, or a 5G core network, or an evolved 5G core network, then some examples of core network equipment include: access and mobility management function (AMF) entities, session management function (SMF) entities, user plane function (UPF) entities, policy control function (PCF) entities, etc., which are not listed here. Among them, the AMF entity can be responsible for terminal access management and mobility management; the SMF entity can be responsible for session management, such as user session establishment; the UPF entity can be a user plane functional entity, mainly responsible for connecting to external networks. For example, if CN200 is a 4G core network, some core network devices include: Mobility Management Entity (MME), Home Subscriber Server (HSS), Serving Gateway (S-GW), Policy and Charging Rules Function (PCRF), Public Data Network Gateway (PDN Gateway, P-GW), etc., which will not be listed here. It should be noted that in this application, entities can also be referred to as network elements or functional entities. For example, an AMF entity can also be called an AMF network element or AMF functional entity, and an SMF entity can also be called an SMF network element or SMF functional entity, etc. The above-mentioned core network devices can work independently or be combined to implement certain control functions. For example, AMF, SMF, and PCF can be combined into a single core network device.

[0113] The communication systems and service scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new service scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0114] The relevant terms used in the embodiments of this application will be explained below. It should be noted that these explanations are for the purpose of making the embodiments of this application easier to understand, and should not be regarded as a limitation on the scope of protection claimed by this application.

[0115] 1. Reference signal (RS):

[0116] The reference signal can also be called a pilot signal. In communication systems, estimating the uplink or downlink channel is crucial for transmitting and receiving data, obtaining system synchronization and feedback channel information. Channel estimation refers to the process of reconstructing or recovering the received signal to compensate for signal distortion caused by channel fading and noise fading. It uses a known reference signal from both the transmitting and receiving devices to track the time and frequency domain variations of the channel. This reference signal can also be called a reference signal. Optionally, the reference signal can be distributed across one or more resource elements (REs) in the time-frequency two-dimensional space within orthogonal frequency division multiplexing (OFDM) symbols, and has known amplitude and phase.

[0117] The reference signal may include an uplink reference signal and a downlink reference signal. The uplink reference signal may include, but is not limited to, at least one of the following: SRS, uplink demodulation reference signal (DMRS), or uplink phase tracking reference signal (PTRS). The downlink reference signal may include, but is not limited to, at least one of the following: CSI-RS, downlink DMRS, or downlink PTRS.

[0118] 2. Precoding matrix:

[0119] Communication systems can increase system capacity and improve throughput through MIMO technology. The mathematical expression can be y = Hx + n, where y is the received signal, H is the MIMO channel, x is the transmitted signal, and n is noise. In communication systems with multiple antennas, signals from multiple transmitting antennas can be superimposed on any one receiving antenna. Therefore, the method by which the transmitting device transmits signals affects system performance, and the process of the receiving device recovering the transmitted signal is also complex. In this context, precoding can be used to reduce system overhead and improve the system capacity of MIMO, and also to reduce the complexity of the receiving device in eliminating inter-channel interference. In this case, the mathematical expression can be y = HPx + n, where P is the precoding matrix (or vector, or precoder). To simplify implementation complexity, P can be selected from a predefined set of matrices (or vectors), called the codebook. The above signal transmission method is also called a codebook-based transmission method. If the transmitting device can obtain all the information of H, then P can be obtained by the transmitting device itself; this signal transmission method is also called a non-codebook (NCB) transmission method.

[0120] 3. Precoding Matrix Indicator (PMI):

[0121] The Precoding Matrix (PMI) can be used to instruct the terminal to determine the precoding matrix for downlink transmission. This precoding matrix can be determined by the terminal based on received reference signals. Optionally, the precoding matrix can be determined by the terminal based on a channel matrix. This channel matrix can be determined by the terminal based on received reference signals (e.g., CSI-RS). For example, the channel matrix can be determined by the terminal through channel estimation or based on channel reciprocity. For instance, the terminal can perform channel estimation based on the received reference signals to determine the channel matrix, and thus determine the precoding matrix.

[0122] It should be understood that the specific methods used by the terminal to determine the precoding matrix are not limited to those described above. Specific implementations can be found in the protocol; for brevity, they are not listed here. For example, the precoding matrix can be obtained by performing singular value decomposition (SVD) on the channel matrix or its covariance matrix, or by performing eigenvalue decomposition (EVD) on the covariance matrix of the channel matrix. It should be understood that the methods for determining the precoding matrix listed above are merely examples and should not constitute any limitation on this application.

[0123] PMI can include wideband PMI and / or subband PMI. Both wideband PMI and subband PMI are related to subband. For ease of understanding, subband will be explained first below.

[0124] Subbands can be divided based on common resource blocks (CRBs), and each CRB can include a physical resource block (PRB). The size of a subband can be determined based on the size of the bandwidth part (BWP) and the configuration of the access network equipment. For example, Table 2 shows one possible correspondence between subband size and BWP size.

[0125] Table 2

[0126] Assuming the BWP size is 76 PRBs (meaning one BWP consists of 76 PRBs), and the subband size configured for the access network device is the first value in Table 2, then the subband size can be 8 PRBs. For example, CRB0 to CRB7 can be one subband, CRB8 to CRB15 can be another subband, and so on.

[0127] Optionally, the boundaries of a BWP and its subbands may not be aligned, thus reducing the actual size of the subbands at the BWP boundaries. For example, within a BWP, the CRBs corresponding to CSI-RS resources are CRB2 to CRB77, and this BWP contains 10 subbands, namely subbands A to J. Subband A includes CRB2 to CRB7, and subband J includes subbands CRB72 to CRB77.

[0128] It should be understood that the above description of subbands is only an example. In practical applications, subbands can also be divided in other ways without limitation.

[0129] The broadband in a broadband PMI can include all subbands configured (or scheduled, indicated, or allocated) by the access network equipment for the terminal. A broadband PMI refers to a PMI reported by the terminal for that broadband. For example, if the subbands configured (or scheduled, indicated, or allocated) by the access network equipment for the terminal include: subband B, subband C, subband D, subband E, subband G, and subband H, then the terminal can receive reference signals (e.g., CSI-RS) on these subbands, obtain a PMI (i.e., broadband PMI), and report the PMI to the access network equipment.

[0130] A subband PMI can refer to each subband configured (or scheduled, indicated, or allocated) by the access network equipment, and the terminal reports one PMI for each subband. For example, if the subbands configured (or scheduled, indicated, or allocated by the access network equipment for the terminal include: subband B, subband C, subband D, subband E, subband G, and subband H, then the terminal determines subband PMI#1 based on the reference signal (e.g., CSI-RS) received on subband B, determines subband PMI#2 based on the reference signal (e.g., CSI-RS) received on subband C, and so on. The terminal determines a subband PMI based on the reference signal (e.g., CSI-RS) received on each of these subbands and reports the determined multiple subband PMIs to the access network equipment.

[0131] Optionally, the access network device can determine the CSI-RS port, the frequency domain discrete Fourier transform (DFT) vector, and the space-frequency vector combining coefficients for constructing the precoding vector based on the PMI from the terminal, thereby determining the precoding matrix. This precoding matrix can be directly used to transmit downlink signals (e.g., downlink data); or it can be processed using one or more beamforming methods, such as zero forcing (ZF), regularized zero-forcing (RZF), minimum mean-squared error (MMSE), and signal-to-leakage-and-noise ratio (SLNR), to obtain the final precoding matrix used for transmitting downlink signals. This application does not limit this.

[0132] It is understandable that the precoding matrix determined by the terminal can be interpreted as the precoding matrix to be fed back. The terminal can indicate the precoding matrix to be fed back through the PMI, so that the access network device can recover the precoding matrix based on the PMI. Optionally, the precoding matrix recovered by the access network device based on the PMI can be the same as or similar to the precoding matrix to be fed back. The higher the similarity between the precoding matrix determined by the access network device based on the PMI and the precoding matrix determined by the terminal, the more well the precoding matrix determined by the access network device for transmitting downlink signals can be adapted to the channel state, and therefore the better the signal reception quality can be improved.

[0133] Optionally, PMI can be used for downlink MIMO.

[0134] 4. Transmitted precoding matrix indicator (TPMI):

[0135] TPMI can be used to instruct access network devices on the precoding matrix used for uplink transmission. For details on TPMI, please refer to the explanation of PMI above, except that the access network devices and terminals are interchanged, CSI-RS is replaced with SRS, and downlink is replaced with uplink.

[0136] 5. Antenna port:

[0137] An antenna port can be simply referred to as a port. Optionally, an antenna port can be understood as a virtual antenna (or antenna group) recognized by the device, or a spatially distinguishable virtual antenna (or antenna group). An antenna port can be pre-configured for each virtual antenna, and each virtual antenna can be a single physical antenna or a weighted combination of multiple physical antennas. One or more antenna ports can correspond to a reference signal. An antenna port can be understood as a transmit / receive interface on the channel through which the reference signal passes; therefore, each antenna port can be called a port for a reference signal, such as a CSI-RS port, DMRS port, SRS port, etc. In this embodiment, an antenna port can also be used to transmit multiple reference signals. For example, multiple reference signals can be transmitted through this antenna port using frequency division or time division.

[0138] In the protocol, antenna ports can be characterized by "antenna port" or "port," or by resources (such as CSI-RS resources, SRS resources, DMRS resources, PTRS resources, synchronization signal block (SSB) resources, etc.) or resource groups. In other words, the identifier for an antenna port can be replaced with the identifiers mentioned above; for example, the identifier for an antenna port can be replaced with the identifier for a resource, pilot resource, or reference signal resource. Optionally, the full name of SSB can also be "synchronization signal and PBCH block" (SS / PBCH block).

[0139] 6. Flow:

[0140] In a spatial multiplexing MIMO system, multiple parallel data streams can be transmitted simultaneously on the same frequency domain resources, and each data stream is called a stream. Streams in MIMO may also have other names, such as layer, spatial layer, transport layer, data layer, or spatial stream, etc., as long as they have the same meaning, they are all within the protection scope of this application.

[0141] 7. DMD:

[0142] Decomposition Method (DMD) is a method for decomposing dynamic systems. Optionally, DMD can be used to process multiple vectors to obtain recursive relationships between different vectors.

[0143] For example, the plurality of vectors includes s vectors, denoted as y1, y2, ..., y s s is a positive integer. The recurrence relation G between adjacent vectors in these multiple vectors can satisfy the following formula: G = Y³ * pinv(X³)

[0144] Where Y3=[y2,y3,…,y s X3 = [y1, y2, ..., y] s-1 ], pinv indicates the pseudo-inverse operation.

[0145] n is any integer from 1 to s-1, y n+1 =Gy n .

[0146] 8. In this application, the signal may include, but is not limited to, at least one of the following: an uplink signal or a downlink signal.

[0147] The uplink signal includes, for example, at least one of the following: SRS, uplink control information (UCI), uplink DMRS, physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), narrowband physical uplink shared channel (NPUSCH), narrowband physical uplink control channel (NPUCCH), or physical random access channel (PRACH).

[0148] Downlink signals may include at least one of the following: CSI-RS, downlink control information (DCI), downlink DMRS, SSB, paging signal, weak up signal (WUS), paging early indication (PEI) or low power weak up signal (LP-WUS), physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), narrowband physical downlink shared channel (NPDSCH), narrowband physical downlink control channel (NPDCCH) or PBCH.

[0149] 9. In this application, a time unit may be a unit of time-domain resources. Exemplarily, a time unit may include at least one of the following: a system frame, a subframe, a slot, or a symbol (e.g., an OFDM symbol). Figures 5A to 6 below illustrate this using a slot as an example.

[0150] 10. In this application, "instruction" or "for instruction" may include explicit instruction (or direct instruction) and implicit instruction (or indirect instruction). When describing information for instructing A, it may include whether the information explicitly instructs A or implicitly instructs A, but does not necessarily mean that the information carries A.

[0151] The indication methods involved in the embodiments of this application should be understood to cover various methods that enable the party to be indicated to obtain the information to be indicated. The information to be indicated can be sent as a whole or divided into multiple sub-information and sent separately. Moreover, the sending period and / or sending time of these sub-information can be the same or different, without limitation.

[0152] In the embodiments of this application, "information" can be an explicit indication, that is, a direct indication through signaling, or obtained by combining other rules or parameters with parameters indicated by signaling, or by deduction. It can also be an implicit indication, that is, obtained based on rules or relationships, or based on other parameters, or by deduction. No limitation is imposed.

[0153] 11. In this application, communication between different devices can refer to direct communication between different devices (i.e., without the need for relaying or forwarding by other devices), or communication between different devices through other devices (i.e., requiring relaying or forwarding by other devices), or communication between a functional unit within a device and other devices through another functional unit. For example, "sending information to…(terminal)" can be understood as the destination of the information being the terminal, and may include sending information directly or indirectly to the terminal. "Receiving information from…(terminal)" can be understood as the source of the information being the terminal, and may include receiving information directly or indirectly from the terminal. Information may undergo necessary processing between the source and destination ends, such as format changes, digital-to-analog conversion, amplification, filtering, etc., but the destination end can understand the valid information from the source end. Similar expressions in this application can be understood in a similar way, and will not be elaborated further here.

[0154] 12. In this application, the words "exemplarily," "for example," "for instance," and "example" are used to indicate examples, illustrations, or explanations, and are not intended to limit the scope of protection of this application. It should be understood that the examples in this application may also be implemented in other ways.

[0155] 13. In this application, any two of the programs, instructions and code may be substituted for one another.

[0156] 14. In this application, “greater than or equal to” and “greater than” are interchangeable; and / or, “less than” and “less than or equal to” are interchangeable.

[0157] 15. In this application, the recursive relationship may be replaced by at least one of the following: association relationship or correspondence relationship.

[0158] 16. In this application, the parameters may have other representations, as long as they have the same meaning, they are all within the scope of protection of this application. For example, the coefficients corresponding to the precoding matrix of each sub-band in M ​​sub-bands can be represented as: x1, x2, ..., x M .

[0159] 17. In this application, some characters are in regular font, such as 'k'; some characters are in italic font, such as 'k'. When the same character is used in different fonts, it has the same meaning.

[0160] 18. In the accompanying drawings of this application, some vectors are represented by solid lines, such as x in Figure 4A. 1,1 Some vectors are represented using dashed lines, such as x in Figure 4A. 2,1 Vectors represented by solid lines are the vectors indicated by the first information, while vectors represented by dashed lines are the vectors determined based on the vectors represented by solid lines.

[0161] In the accompanying drawings of this application, for the sake of simplification, the k-th sub-band is denoted as sub-band k, where k takes any integer from 1 to M, and M is a positive integer.

[0162] 19. In this application, "obtain" and "determine" are interchangeable.

[0163] 20. In this application, the asterisk (*) in the formula can represent matrix multiplication, matrix multiplication, vector multiplication, vector multiplication, or vector multiplication.

[0164] Currently, after receiving a reference signal, the receiving device can determine the precoding matrix for each sub-band based on the reference signal and feed it back to the transmitting device. In this way, the transmitting device can determine the precoding matrix used for transmitting the signal based on the precoding matrix of each sub-band. The following explanation uses downlink MIMO as an example to illustrate how the receiving device feeds back the precoding matrix. It should be understood that uplink MIMO can also use a similar method as downlink MIMO, which will not be elaborated further.

[0165] For example, for downlink MIMO, the downlink resources configured (or scheduled, indicated, or allocated) by the access network device for the terminal include M subbands, where M is a positive integer. The terminal processes the precoding matrix of each of the M subbands to obtain the coefficients corresponding to the precoding matrix of each of the M subbands. The subband PMI sent by the terminal to the access network device may include the coefficients corresponding to the precoding matrix of each of the M subbands.

[0166] In some possible ways, as shown in Figure 2A, the precoding matrix of the k-th subband out of M subbands can be represented as P k (1) P k (1) The number of rows and columns are the number of transmit antenna ports and the number of streams, J, respectively. Here, k takes integer values ​​from 1 to M, and J is a positive integer. The precoding matrix P for the j-th stream... j (2) It can include the j-th column of the precoding matrix for each of the M subbands, for example, P j (2) The k-th column in the array is P k (1) The j-th column in the array. Here, j takes integer values ​​from 1 to J. Optional, P... j (2) It can be represented as: P j (2) =W j (1) *C j (1) *W j (2) W j (1)W can be the first basis vector corresponding to the j-th flow. j (1) The number of rows and P j (2) The number of rows is the same. (C) j (1) It can be P j (2) The corresponding coefficient matrix, C j (1) The number of rows and W j (1) The number of columns is the same. Because P j (2) It can include the j-th column of the precoding matrix for each of the M subbands, therefore, C j (1) C can be the coefficient matrix corresponding to the j-th column of the precoding matrix for each of the M subbands. j (1) China and P k (1) The relevant column can be P k (1) The corresponding coefficient, for example, C j (1) P k (1) The calculated column can be P k (1) The corresponding coefficient. W j (2) W can be the second basis vector. j (2) The number of rows and C j (1) The number of columns is the same, W j (2) The number of columns and P j (2) The number of columns is the same. For example, P j (2) The number of rows and columns are 1024 and 100 respectively; W j (1) The number of rows and columns are 1024 and 4 respectively; C j (1) The number of rows and columns are 4 and 6 respectively; W j (2) The number of rows and columns are 6 and 100, respectively. In this method, the terminal can send an instruction to the access network device for C. j (1) W j (1) and W j (2) Information. Among them, information used to indicate C. j (1) The information can be Pj (2) The corresponding coefficient, due to P j (2) It relates to the precoding matrix of each of the M subbands, therefore, it is used to indicate C. j (1) The information can be referred to as the coefficients corresponding to the precoding matrix of each subband. Used to indicate C j (1) Information such as C may include j (1) Or C j (1) Column vectors, etc. Access network devices can, according to C... j (1) W j (1) and W j (2) Determine P j (2) Therefore, it can be based on P j (2) Determine P k (1) .

[0167] In the above method, the transmitting device needs to send the coefficients corresponding to the precoding matrix for each sub-band, which incurs significant overhead. For example, when this method is applied to massive MIMO technology, the overhead of feeding back the precoding matrix may be substantial. This is because massive MIMO technology may have a large number of antennas. Since P k (1) The number of rows represents the number of transmit antenna ports. Therefore, as the number of antennas increases, the number of antenna ports also increases, according to P. k (1) The obtained C j (1) The number of rows also increases, leading to a greater overhead for the feedback precoding matrix. For example, large-scale MIMO technology has a large bandwidth. As bandwidth increases, the number of subbands also increases, due to C... j (1) The number of columns is related to the number of subbands, therefore, the overhead of the feedback precoding matrix increases. Furthermore, as bandwidth increases, the number of candidate vectors for the second basis vector also increases, and the overhead of feeding back the second basis vector can be positively correlated with the number of candidate vectors, thus leading to an increase in the overhead of feeding back the second basis vector.

[0168] This application provides a communication method. Figure 3 is a flowchart illustrating the communication method provided in this application. Figure 3 uses a first device and a second device as examples of the execution entities in this interaction to illustrate the method.

[0169] Optionally, the method shown in Figure 3 can be used in scenario 1 and / or scenario 2.

[0170] Scenario 1: The first device is a terminal or a device applicable to a terminal (e.g., a module, circuit, chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that implements all or part of the terminal's functions. The second device is an access network device or a device applicable to an access network device (e.g., a module, circuit, chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that implements all or part of the access network device's functions.

[0171] Optionally, scenario 1 can be used for downlink MIMO.

[0172] Scenario 2: The first device is an access network device or a device that can be applied to an access network device (e.g., a module, circuit, chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that implements all or part of the functions of the access network device. The second device is a terminal or a device that can be applied to a terminal (e.g., a module, circuit, chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software that implements all or part of the functions of the terminal.

[0173] Optionally, scenario 2 can be used for uplink MIMO.

[0174] As shown in Figure 3, the method includes:

[0175] S301: The second device sends a first reference signal; correspondingly, the first device receives the first reference signal.

[0176] In some examples, such as Scenario 1 above, the first reference signal may be CSI-RS.

[0177] In other examples, such as scenario 2 above, the first reference signal may be the SRS.

[0178] This application does not limit the specific method by which the second device transmits the first reference signal; for example, it may transmit the signal in a manner specified in the protocol.

[0179] S302: The first device sends the first information; correspondingly, the second device receives the first information.

[0180] In some examples, in scenario 1 above, the first information may be PMI, or the first information may be CSI including PMI.

[0181] In other examples, such as scenario 2 above, the first piece of information could be TPMI.

[0182] In S302, the first information may indicate a first vector and a first matrix. The first vector may belong to M vectors, where M is a positive integer. Optionally, M may be greater than or equal to 2, or in other words, M may be an integer greater than or equal to 2. The first matrix may be used to indicate the recursive relationship (or association or correspondence) between different vectors among the M vectors; or, the first matrix may be used to determine the vectors among the M vectors other than the first vector; or, the first matrix and the first vector may be used to determine the M vectors.

[0183] To make it easier to understand, we will first explain the M vectors.

[0184] M vectors can correspond to M subbands; for example, M vectors can correspond one-to-one with M subbands. Optionally, in scenario 1 above, the M subbands may include some or all of the subbands in the downlink resources configured (or scheduled, indicated, or allocated) by the second device for the first device; or, in scenario 2 above, the M subbands may include some or all of the subbands in the uplink resources configured (or scheduled, indicated, or allocated) by the first device for the second device.

[0185] Each of the M vectors can be a coefficient corresponding to the precoding matrix of one of the M subbands; or, each of the M vectors can be used to determine the precoding matrix of one of the M subbands; or, each of the M vectors has a correspondence (or association) with the precoding matrix of one of the M subbands. The precoding matrix of each of the M subbands is obtained (or determined) based on the first reference signal, for example, the precoding matrix of each of the M subbands is obtained (or determined) based on the first reference signal transmitted on that subband. This application does not limit the specific process of obtaining the precoding matrix of each of the M subbands.

[0186] The following explanation uses the k-th vector (hereinafter referred to as the k-th vector) among the M vectors as an example. Here, k takes any integer from 1 to M.

[0187] The k-th vector can be the coefficient corresponding to the precoding matrix of the k-th subband (hereinafter referred to as the k-th subband) among the M subbands. The k-th vector can have multiple possible forms, such as form a1 or form a2.

[0188] Method a1: The k-th vector can be the precoding matrix P of the j-th stream. j (2) A column in the corresponding coefficient matrix; or, the coefficients corresponding to the precoding matrix of the k-th sub-band are P.j (2) This corresponds to a column in the coefficient matrix. These M vectors may include P. j (2) Each column of the corresponding coefficient matrix; or, each of the M vectors is P. j (2) This corresponds to a column in the coefficient matrix. Where P... j (2) It can include the j-th column of the precoding matrix of each of the M subbands, for example, as shown in Figure 2A, P j (2) The k-th column in the matrix is ​​the precoding matrix P of the k-th subband. k (1) The j-th column in P. j (2) The number of rows and columns are the number of antenna ports and M, respectively. j is an integer greater than or equal to 1 and less than or equal to J; J is the stream number, and J is a positive integer.

[0189] To facilitate understanding, let's first discuss P. j (2) The corresponding coefficient matrix is ​​explained.

[0190] In some implementations (hereinafter referred to as implementation 1), P j (2) The corresponding coefficient matrix is ​​based on P j (2) The first basis vector corresponding to the j-th flow is determined; or, the first device can be determined according to P. j (2) The first basis vector corresponding to the j-th flow determines P. j (2) The corresponding coefficient matrix. For example, P j (2) It can be represented as: P j (2) =W j (1) *C j (2) Among them, W j (1) W can be the first basis vector corresponding to the j-th flow. j (1) The number of rows and P j (2) The number of rows is the same; C j (2) It can be P j (2) The corresponding coefficient matrix, C j (2) The number of rows and W j (1) The number of columns is the same, Cj (2) The number of columns and P j (2) The columns have the same number of columns, i.e., C j (2) The number of columns is M. Thus, the first device can be based on P. j (2) and W j (1) Determine C j (2) .

[0191] The first basis vector corresponding to the j-th flow can be pre-set, for example, as specified by the protocol, or determined based on the Type I codebook or the Type II codebook. The specific contents of the Type I codebook and the Type II codebook can be referred to the protocol. Alternatively, the first basis vector corresponding to the j-th flow can be determined by the first device. Alternatively, the first basis vector corresponding to the j-th flow can be notified to the first device by other devices (e.g., core network equipment or the second device).

[0192] For example, in P j (2) The k-th column in the matrix is ​​the precoding matrix P of the k-th subband. k (1) In the case of the j-th column (as shown in Figure 2A), the k-th vector can be P. j (2) The corresponding k-th column of the coefficient matrix, the M vectors may include P j (2) Each column of the corresponding coefficient matrix. For example, the k-th vector could be C in implementation 1. j (2) The k-th column of the M vectors may include the C vectors in implementation 1. j (2) Each column in the table.

[0193] It should be understood that, in method a1, the k-th vector can also be implemented in other ways. For example, in P j (2) The (k+1)th column in the array is P. k (1) In the case of the j-th column, the k-th vector can be P. j (2) The corresponding (k+1)th column of the coefficient matrix, for example, the kth vector, can be C in implementation 1. j (2) The (k+1)th column.

[0194] Optionally, in this method a1, the first information may indicate at least one pair of vectors and matrices, each pair of vectors and matrices being used to determine the coefficient matrix corresponding to the precoding matrix of a stream. For example, the first information may indicate J pairs of vectors and matrices. The j-th pair of vectors and matrices can be used to determine P j (2) The corresponding coefficient matrix. This application uses a pair of vectors and matrices (i.e., the first vector and the first matrix) as an example for illustration. For the specific details of other pairs of vectors and matrices, please refer to the description of the first vector and the first matrix in this application, which will not be repeated here.

[0195] Method a2: The k-th vector can be a column of the coefficient matrix corresponding to the precoding matrix of stream J; or, the coefficients corresponding to the precoding matrix of the k-th subband are a column of the coefficient matrix corresponding to the precoding matrix of stream J. These M vectors can include each column of the coefficient matrix corresponding to the precoding matrix of stream J; or, each of these M vectors is a column of the coefficient matrix corresponding to the precoding matrix of stream J. Wherein, a column of the precoding matrix of stream J includes a column of the precoding matrices of streams 1 to J, and the precoding matrix P of stream j... j (2) For details, please refer to method a1 regarding P. j (2) The explanation will not be repeated here.

[0196] Optionally, the k-th column of the precoding matrix of stream J may include the k-th column of the precoding matrices of streams 1 through J. For example, as shown in Figure 2B, each precoding matrix of streams 1 through J has U1 rows, where U1 is a positive integer. In the k-th column of the precoding matrix of stream J, the first to U1 elements are the elements of the k-th column of the precoding matrix of stream 1, the U1+1 to 2U1 elements are the elements of the k-th column of the precoding matrix of stream 2, and so on. It should be understood that the k-th column of the precoding matrix of stream J may also be arranged in other ways, without restriction.

[0197] In some implementations, the coefficient matrix corresponding to the precoding matrix of the J-stream is determined based on the precoding matrix of the J-stream and the first basis vector corresponding to the J-stream; alternatively, the first device can determine the coefficient matrix corresponding to the precoding matrix of the J-stream based on the precoding matrix of the J-stream and the first basis vector corresponding to the J-stream, and the method of determination can be referred to in method a1 regarding "the first device can determine the coefficient matrix corresponding to the precoding matrix of the J-stream based on P j (2) The first basis vector corresponding to the j-th flow determines P. j (2) The description of the "corresponding coefficient matrix" simply means that P j (2) The precoding matrix is ​​replaced with the J-stream, and the j-th stream is replaced with the J-stream. This will not be elaborated further.

[0198] In some examples, the k-th column in the precoding matrix of stream J may include the k-th column in the precoding matrices of streams 1 through J, and P j (2) The k-th column in the matrix is ​​the precoding matrix P of the k-th subband. k (1) In the case of the j-th column, the k-th vector can be the k-th column of the coefficient matrix corresponding to the precoding matrix of the J-stream. These M vectors can include each column of the coefficient matrix corresponding to the precoding matrix of the J-stream.

[0199] It should be understood that, in method a2, the k-th vector can also be implemented in other ways. For example, in P j (2) The (k+1)th column in the array is P. k (1) In the case of the j-th column, the k-th vector can be the (k+1)-th column of the coefficient matrix corresponding to the precoding matrix of the J-stream.

[0200] It should be understood that methods a1 and a2 are merely illustrative and are not intended to limit the scope of protection of this application. In practical applications, the k-th vector may also have other implementations. For example, as shown in Figure 2C, the number of columns in each precoding matrix of the first to J-th streams is M. The first to M columns of the precoding matrix of the J-th stream are the first to M columns of the precoding matrix of the first stream, the (M+1) to 2M columns of the precoding matrix of the J-th stream are the first to M columns of the precoding matrix of the second stream, and so on. In this case, the number of columns in the coefficient matrix corresponding to the precoding matrix of the J-th stream is M*J. The M vectors may include the (j-1)M+1 to jM columns of the coefficient matrix corresponding to the precoding matrix of the J-th stream, and the k-th vector may be the (j-1)M+k column of the coefficient matrix corresponding to the precoding matrix of the J-th stream. j is an integer greater than or equal to 1 and less than or equal to J.

[0201] The first vector and the first matrix will be explained below based on M vectors.

[0202] 1. First vector:

[0203] As mentioned earlier, the first vector belongs to the M vectors. Optionally, the first vector is one of the M vectors. For example (hereinafter referred to as Example 1), the M vectors include: x 1,1 ,x 2,1 ,…,x M,1 In other words, the coefficients corresponding to the precoding matrices of these M subbands include: x 1,1 ,x 2,1 ,…,x M,1 Among them, x k,1 Let x be the k-th vector among the M vectors; in other words, xk,1 These are the coefficients corresponding to the precoding matrix of the k-th subband out of M subbands. k can be referred to as the vector index and / or the subband index, and k takes integer values ​​from 1 to M. The first vector can be x. 1,1 ,x 2,1 ,…,x M,1 One of them. For example, the first vector could be x. 1,1 , or x 2,1 , or x 3,1 , or x M,1 It should be understood that the first vector can also be any of the M vectors excluding x. 1,1 ,x 2,1 ,x 3,1 and x M,1 Other vectors besides these are not listed one by one.

[0204] Optionally, the first vector can be the coefficients corresponding to the precoding matrix of the first sub-band, and the first sub-band can be the sub-band with the smallest frequency among the M sub-bands. For example (hereinafter referred to as Example 2), the M vectors are as shown in Example 1. The value of k is positively correlated with the frequency of the k-th sub-band; in other words, the smaller the value of k, the smaller the frequency of the k-th sub-band, and the larger the value of k, the larger the frequency of the k-th sub-band. In this case, the first sub-band can be the 1st sub-band among the M sub-bands, and the first vector can be x 1,1 .

[0205] To simplify the description, the specific details of the M vectors in the examples below can be found in Example 1 or Example 2, and will not be repeated here.

[0206] 2. First matrix:

[0207] As mentioned earlier, the first matrix can be used to indicate the recursive relationship between different vectors among the M vectors.

[0208] In some examples, the k-th vector among the M vectors is a vector from mode a1. The 1-th vector among the M vectors can be the precoding matrix P of the j-th stream. j (2) The first column of the corresponding coefficient matrix; the second vector among the M vectors can be P. j (2) The second column of the corresponding coefficient matrix, and so on. The first matrix indicates P. j (2) The recursive relationship between different columns in the corresponding coefficient matrix.

[0209] In other examples, the k-th vector among the M vectors is the vector in mode a2. The first vector among the M vectors can be the first column of the coefficient matrix corresponding to the precoding matrix of the J-stream; the second vector among the M vectors can be the second column of the coefficient matrix corresponding to the precoding matrix of the J-stream, and so on. The first matrix can indicate the recursive relationship between different columns in the coefficient matrix corresponding to the precoding matrix of the J-stream.

[0210] Optionally, the first matrix can be used to indicate the recursive relationship (or association or correspondence) between vectors corresponding to adjacent sub-bands in the M sub-bands; or, the first matrix can be used to indicate the recursive relationship (or association or correspondence) between adjacent vectors in the M vectors; or, the product of the first matrix and the first vector can be used to determine the vector adjacent to the first vector among the M vectors; or, the product of the first matrix and one of the vectors in the M vectors can be used to determine another vector adjacent to that vector among the M vectors. Adjacent sub-bands can be sub-bands with adjacent indices. For example, the first sub-band and the second sub-band in the M sub-bands are adjacent sub-bands. Adjacent vectors can be vectors with adjacent indices. For example, the first vector and the second vector in the M vectors are adjacent vectors.

[0211] It should be understood that the first matrix may also have other forms, all of which are within the scope of protection of this application. For example, the first matrix may indicate the recursive relationship between the vectors corresponding to the sub-bands that are separated by O sub-bands among the M vectors, where O is a positive integer.

[0212] Optional, the first matrix G f The following formula (1) can be satisfied; or, the first device can determine the first matrix G according to the following formula (1). f G f =Y1*pinv(X1) Formula (1)

[0213] Where, Y1=[x 2,1 ,x 3,1 ,…,x M,1 ], X1 = [x 1,1 ,x 2,1 ,…,x M-1,1 ], pinv indicates the pseudo-inverse operation. x k,1 For details, please refer to Example 1 or Example 2 above regarding x. k,1 The explanation is that k takes on all integers greater than 1 to M, which will not be elaborated further.

[0214] It should be understood that formula (1) is merely an example and is not intended to limit the scope of protection of this application. In practical applications, formula (1) can also be modified. For example, the positions of the column vectors in X1 and / or Y1 can be changed. Also, for example, X1 and / or Y1 may include fewer column vectors. All modifications to formula (1) are within the scope of protection of this application.

[0215] In this way, the first device can accurately determine the first matrix according to formula (1), thereby accurately determining the recursive relationship between different vectors among the M vectors.

[0216] The following example illustrates how the first matrix and the first vector can be used to determine the M vectors, using the first matrix indicating the recursive relationship between the vectors in the M vectors and the vectors in the adjacent sub-bands of the M sub-bands.

[0217] In some implementations, as shown in Figure 4A, the first vector is x 1,1 The first matrix is ​​G f In the case of the k-th vector x among the M vectors k,1 =G f k-1 *x 1,1 Where k takes any integer from 1 to M, and G f k-1 For G f The (k-1)th power. For example, x 2,1 =G f *x 1,1 For example, x 3,1 =G f 2 *x 1,1 For example, x M,1 =G f M-1 *x 1,1 Thus, after receiving the first information indicating the first matrix and the first vector, the second device can accurately determine the vector with an index greater than the first vector among the M vectors, thereby accurately determining the M vectors.

[0218] In other implementations, as shown in Figure 4B, the first vector is x M,1 The first matrix is ​​G f In the case of the k-th vector x among the M vectors k,1 =inv(G f ) M-k *x M,1 Where k takes integer values ​​from 1 to M, inv(G f ) M-k for inv(G f ) to the power of Mk, inv(G f ) is Gf The inverse matrix. For example, x M-1,1 =inv(G f )*x M,1 For example, x M-2,1 =inv(G f ) 2 *x M,1 For example, x 1,1 =inv(G f ) M-1 *x M,1 Thus, after receiving the first information indicating the first matrix and the first vector, the second device can accurately determine the vectors among the M vectors whose index is less than that of the first vector, thereby accurately determining the M vectors.

[0219] In some implementations, the first vector can be represented as x k1,1 k1 is a positive integer; the first matrix is ​​G. f When k is greater than k1, x k,1 =G f k-k1 *x k1,1 When k is less than k1, x k,1 =inv(G f ) k1-k *x k1,1 Where k takes any integer from 1 to M, and G f k-k1 For G f k-k1, inv(G f ) k1-k for inv(G f ) to the power of k1-k, inv(G f ) is G f The inverse matrix. For example, as shown in Figure 4C, the first vector is x. 3,1 The first matrix is ​​G f When k is greater than 3, the k-th vector x among the M vectors... k,1 =G f k-3 *x 3,1 When k is less than 3, the k-th vector x among the M vectors k,1 =inv(G f ) 3-k *x 3,1 For example, x 4,1 =G f *x 3,1 For example, x 5,1 =G f 2 *x 3,1 For example, x 1,1=inv(G f ) 2 *x 3,1 For example, x 2,1 =inv(G f )*x 3,1 Thus, after receiving the first information indicating the first matrix and the first vector, the second device can accurately determine the vectors other than the first vector among the M vectors, thereby accurately determining the M vectors. Optionally, in this implementation, the first vector can be the vector with the middle index among the M vectors. In this way, the difference between the first vector and the vectors other than the first vector among the M vectors is relatively small, thereby determining the M vectors more accurately.

[0220] As mentioned earlier, the first information can indicate the first vector and the first matrix, and there can be multiple ways of indicating them, such as mode b1 or mode b2.

[0221] Method b1: The first information includes the first vector and the first matrix.

[0222] For example, in the first vector x 1,1 The first matrix is ​​G f In this case, the first piece of information may include: x 1,1 and G f .

[0223] For example, when the first vector is x M,1 The first matrix is ​​G f In this case, the first piece of information may include: x M,1 and G f .

[0224] In this manner, the second device can accurately determine the first vector and the first matrix based on the first information. Furthermore, in this method, the first information can directly indicate the first vector and the first matrix, thus eliminating the need for the second device to calculate and determine the first vector and the first matrix, thereby reducing the computational complexity of the second device.

[0225] Method b2: The first information includes information that corresponds to the first vector and / or the first matrix.

[0226] In some implementations, the first information may include: a first vector, Λ1, and Ψ1. Here, Λ1 is a diagonal matrix; Ψ1 is the matrix obtained by eigenvalue decomposition of the first matrix, and Ψ1 has the same number of rows and columns as the first matrix. The first matrix has the same number of rows and columns; in other words, the first matrix is ​​a square matrix. Λ1, Ψ1, and the first matrix can satisfy the following formula: G f =Ψ1*Λ1*Ψ1 H Among them, G f This is the first matrix; Ψ1H This is the conjugate transpose of Ψ1. For example, when the first vector is x... 1,1 The first matrix is ​​G f And G f =Ψ1*Λ1*Ψ1 H In this case, the first piece of information may include: x 1,1 Λ1 and Ψ1.

[0227] In this implementation, the second device can accurately determine the first matrix based on Λ1 and Ψ1. Furthermore, in this implementation, the second device can accurately determine the first matrix based on Λ1, Ψ1, and Ψ1. H This involves parallel computation of M vectors, excluding the first vector. For example, if the first vector is x... 1,1 The first matrix is ​​G f In this case, the third vector among the M vectors can be x. 1,1 *G f 2 =x 1,1 *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H =x 1,1 *Ψ1*Λ1 2 *Ψ1 H The fourth vector among these M vectors can be x. 1,1 *G f 3 =x 1,1 *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H =x 1,1 *Ψ1*Λ1 3 *Ψ1 H In this way, the second device can compute all vectors except the first vector in M ​​vectors in parallel, thereby saving computation time and resources. Furthermore, in this implementation, the second device can compute the k-th vector among the M vectors based on Λ1 raised to the power of k-1. Since Λ1 is a diagonal matrix, the computational cost of Λ1 raised to the power of k-1 is relatively low, thus reducing the computational cost of the second device.

[0228] In other implementations, the first information may include: Ψ1 H The product of the first vector, Λ1, and Ψ1. Where Λ1, Ψ1, and Ψ1... H For details, please refer to the sections on Λ1, Ψ1, and Ψ1 above. H The explanation will not be repeated here. For example, when the first vector is x 1,1 The first matrix is ​​G f And G f =Ψ1*Λ1*Ψ1 HIn this case, the first information may include: Ψ1 H *x 1,1 Λ1 and Ψ1.

[0229] In this implementation, the second device can accurately determine the first matrix based on Λ1 and Ψ1. Furthermore, in this implementation, the second device can accurately determine the first matrix based on Λ1, Ψ1, and Ψ1. H This involves parallel computation of M vectors, excluding the first vector. For example, if the first vector is x... 1,1 The first matrix is ​​G f In this case, the third vector among the M vectors can be x. 1,1 *G f 2 =x 1,1 *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H =x 1,1 *Ψ1*Λ1 2 *Ψ1 H The fourth vector among these M vectors can be x. 1,1 *G f 3 =x 1,1 *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H *Ψ1*Λ1*Ψ1 H =x 1,1 *Ψ1*Λ1 3 *Ψ1 H In this way, the second device can compute all vectors except the first vector out of the M vectors in parallel, thereby saving computation time and resources. Furthermore, in this implementation, the second device can compute the k-th vector out of the M vectors based on Λ1 raised to the power of k-1. Since Λ1 is a diagonal matrix, the computational cost of Λ1 raised to the power of k-1 is low, thus reducing the computational load on the second device. Additionally, in this implementation, the first device can determine Ψ1... H *x 1,1 Thus, the second device can directly use Ψ1 H *x 1,1 The calculation results determine the vectors other than the first vector among the M vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0230] This application does not limit the specific method by which the first device sends the first information; for example, it may use the method specified in the protocol.

[0231] Using the method shown in Figure 3, the first device can send first information, which indicates one of the M vectors (i.e., the first vector) and the recursive relationship between the different vectors in the M vectors. Thus, the second device can accurately determine the M vectors based on the first vector and the recursive relationship, thereby determining the precoding matrices for the M subbands. In this method, the first device does not need to send every single one of the M vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0232] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix of each sub-band increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. As another example, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can transmit only the coefficients corresponding to the precoding matrix of one sub-band, without transmitting the coefficients corresponding to the precoding matrix of each sub-band. In this way, the overhead of the feedback precoding matrix does not increase with the number of sub-bands, thus significantly reducing the overhead of the feedback precoding matrix.

[0233] Alternatively, since the first device may not send each of the M vectors, the method can improve the accuracy of the indicated first vector and / or the first matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the M vectors recovered by the second device.

[0234] In addition, in this method, the coefficient matrix corresponding to the precoding matrix can be determined based on the precoding matrix and the first basis vector. The first device may not need to indicate the second basis vector to the second device, thereby reducing the overhead of feeding back the second basis vector.

[0235] Among some possible approaches, the method shown in Figure 3 also includes:

[0236] S303: The second device sends a first signal; correspondingly, the first device receives the first signal.

[0237] In some examples, such as Scenario 1 above, the first signal may be a downlink signal.

[0238] In other examples, such as scenario 2 above, the first information may be an uplink signal.

[0239] In S303, the first signal is transmitted based on the first precoding matrix; or, the second device may transmit the first signal based on the first precoding matrix. The first precoding matrix may be determined based on the precoding matrices of some or all of the M subbands; or, the second device may determine the first precoding matrix based on the precoding matrices of some or all of the M subbands. For example, if the first signal is transmitted through some of the M subbands, the first precoding matrix may be determined based on those some subbands. As another example, if the first signal is transmitted through all of the M subbands, the first precoding matrix may be determined based on all of the M subbands. Furthermore, the granularity of precoding performed by the second device may be the same as or different from the granularity of the subbands, without limitation.

[0240] The precoding matrices for the M subbands can be determined based on M vectors; alternatively, the second device can determine the precoding matrices for the M subbands based on the M vectors; or, the M vectors can be used to determine the precoding matrices for the M subbands. For ease of understanding, the method for determining the M vectors will be explained below.

[0241] The first vector among the M vectors is determined based on the first information; or, the second device can determine the first vector based on the first information. In some examples, when the first information includes the first vector, the second device can accurately determine the first vector based on the first information. In other examples, when the first information includes information that corresponds to the first vector, the second device can determine the first vector based on the information that corresponds to the first vector. For example, when the first information includes: Ψ1 H In the case of the product of the first vector, Λ1, and Ψ1, the second device can be based on Ψ1. H The first vector is determined by the product of the first vector and Ψ1.

[0242] The vectors other than the first vector among the M vectors are determined based on the first vector and the first matrix; or, the first vector and the first matrix can be used to determine the vectors other than the first vector among the M vectors; or, the second device can determine the vectors other than the first vector among the M vectors based on the first vector and the first matrix. For details, please refer to the explanation of "the first matrix and the first vector can be used to determine the M vectors" in S302, which will not be repeated here.

[0243] As mentioned earlier, the precoding matrix for the M subbands can be determined based on M vectors. The following example, using methods a1 and a2 from the previous text, illustrates this.

[0244] For method a1:

[0245] In mode a1, the M vectors may include the precoding matrix P of the j-th stream.j (2) Each column of the corresponding coefficient matrix; or, each of the M vectors is P. j (2) A column in the corresponding coefficient matrix. j is an integer greater than or equal to 1 and less than or equal to J; J is the stream number. In this case, the precoding matrix of the M subbands can be determined based on the coefficient matrix corresponding to the precoding matrix of each stream from the 1st to the Jth stream; or, the second device can determine the precoding matrix of the M subbands based on the coefficient matrix corresponding to the precoding matrix of each stream from the 1st to the Jth stream.

[0246] Optionally, the second device may determine the precoding matrix of the M subbands through steps A1 to A3:

[0247] Step A1: The first information may indicate J pairs of vectors and matrices. The second device may determine P based on the j-th pair of vectors and matrices. j (2) The corresponding coefficient matrix; or, the j-th pair of vectors and matrices can be used to determine P. j (2) The corresponding coefficient matrix; or, the second device can determine the j-th group of vectors based on the j-th pair of vectors and matrices, the j-th group of vectors comprising M vectors, each of which is P. j (2) A column in the corresponding coefficient matrix; or, the j-th pair of vectors and the matrix can be used for the j-th group of vectors.

[0248] "The j-th pair of vectors and matrices can be used to determine P" j (2) For details regarding the "corresponding coefficient matrix", please refer to the explanation in S302 that "the first matrix and the first vector can be used to determine the M vectors", which will not be repeated here.

[0249] Step A2: The second device can be based on P j (2) The corresponding coefficient matrix determines P. j (2) Or, P j (2) The corresponding coefficient matrix can be used to determine P. j (2) .

[0250] For example, as shown in Implementation 1 of S302, P j (2) =W j (1) *C j (2) W j (1) C can be the first basis vector corresponding to the j-th flow.j (2) It can be P j (2) The corresponding coefficient matrix. Thus, the second device can be based on W. j (1) and C j (2) Determine P j (2) .

[0251] The first basis vector corresponding to the j-th flow can be pre-set, for example, as specified by the protocol, or determined based on the Type I codebook or the Type II codebook. The specific contents of the Type I codebook and the Type II codebook can be referred to the protocol. Alternatively, the first basis vector corresponding to the j-th flow can be determined by the second device. Or, the first basis vector corresponding to the j-th flow can be notified to the second device by other devices (e.g., core network equipment or the first device).

[0252] The second device can perform steps A1 to A2 for each of the first to J streams to obtain the precoding matrix for each of the first to J streams.

[0253] Step A3: The second device determines the precoding matrix of each of the M subbands based on the precoding matrix of each of the streams from the first to the Jth; or, the precoding matrix of each of the streams from the first to the Jth can be used to determine the precoding matrix of each of the M subbands.

[0254] As described in method a1 above, P j (2) This can include the j-th column of the precoding matrix for each of the M subbands; therefore, the precoding matrix for each stream from the 1st to the Jth stream can be used to determine the precoding matrix for the M subbands. For example, in P j (2) The k-th column in the matrix is ​​the precoding matrix P of the k-th subband. k (1) In the case of the j-th column (as shown in Figure 2A), the precoding matrix P of the k-th subband k (1) This may include the k-th column of the precoding matrix of each of the streams 1 through J. Thus, the second device can determine the precoding matrix of each of the M subbands based on the precoding matrix of each of the streams 1 through J.

[0255] For method a2:

[0256] In mode a2, the M vectors may include each column of the coefficient matrix corresponding to the precoding matrix of the J-stream; or, each of the M vectors may be a column of the coefficient matrix corresponding to the precoding matrix of the J-stream. In this case, the precoding matrices of the M sub-bands may be determined based on the coefficient matrix corresponding to the precoding matrix of the J-stream; or, the second device may determine the precoding matrices of the M sub-bands based on the coefficient matrix corresponding to the precoding matrix of the J-stream.

[0257] Optionally, the second device may determine the precoding matrix of the M subbands through steps B1 to B4:

[0258] Step B1: The first information may indicate a first vector and a first matrix. The second device may determine the coefficient matrix corresponding to the precoding matrix of the J-stream based on the first vector and the first matrix; or, the first vector and the first matrix may be used to determine the coefficient matrix corresponding to the precoding matrix of the J-stream; or, the second device may determine M vectors based on the first vector and the first matrix, each of the M vectors being a column of the coefficient matrix corresponding to the precoding matrix of the J-stream; or, the first vector and the first matrix may be used for the M vectors.

[0259] For details on step B1, please refer to the explanation in S302 that "the first matrix and the first vector can be used to determine the M vectors", which will not be repeated here.

[0260] Step B2: The second device can determine the precoding matrix of the J stream based on the coefficient matrix corresponding to the precoding matrix of the J stream; or, the coefficient matrix corresponding to the precoding matrix of the J stream can be used to determine the precoding matrix of the J stream.

[0261] The details of step B2 can be found in step A2, except that P... j (2) The precoding matrix is ​​replaced with the J-stream, and the j-th stream is replaced with the J-stream. This will not be elaborated further.

[0262] Step B3: The second device can determine the precoding matrix of each of the first to the J streams based on the precoding matrix of the J stream; or, the precoding matrix of the J stream can be used to determine the precoding matrix of each of the first to the J streams.

[0263] For example, as shown in Figure 2B, in the k-th column of the precoding matrix of stream J, the elements from 1 to U1 are the elements of the k-th column of the precoding matrix of stream 1, the elements from U1+1 to 2U1 are the elements of the k-th column of the precoding matrix of stream 2, and so on. Thus, based on the coefficient matrix corresponding to the precoding matrix of stream J, the second device can determine the precoding matrix of each stream from stream 1 to stream J.

[0264] Step B4: The second device determines the precoding matrix of each of the M subbands based on the precoding matrix of each of the streams from the first to the Jth; or, the precoding matrix of each of the streams from the first to the Jth can be used to determine the precoding matrix of each of the M subbands.

[0265] The details of step B4 can be found in step A3, and will not be repeated here.

[0266] Among some possible approaches, the method shown in Figure 3 also includes:

[0267] S304: The second device sends the first instruction information; correspondingly, the first device receives the first instruction information.

[0268] Optionally, S304 can be used in scenario 1 above.

[0269] The first indication information can be used to indicate the method of CSI feedback. CSI may include PMI. Optionally, in this application, the method of CSI feedback can be replaced by at least one of the following: a method of feeding back a precoding matrix, a method of feeding back PMI, a method of feeding back TPMI, a method of compressing CSI, a method of compressing a precoding matrix, a method of compressing PMI, or a method of compressing TPMI.

[0270] Optionally, the CSI feedback method includes, but is not limited to, at least one of the following: Method 1 (or Type 1), Method 2 (or Type 2), or a new method (or new type). Wherein, when the CSI feedback method is Method 1, the precoding matrix is ​​a precoding matrix based on the Type 1 codebook; details can be found in the protocol's description of the Type 1 codebook. When the CSI feedback method is Method 2, the precoding matrix is ​​a precoding matrix based on the Type 2 codebook; details can be found in the protocol's description of the Type 2 codebook. When the CSI feedback method is the new method, the precoding matrix can be indicated by a first vector and a first matrix; or, when the CSI feedback method is the new method, the precoding matrix can be indicated by a subset of M vectors and the recursive relationship between different vectors among the M vectors; or, when the CSI feedback method is the new method, the precoding matrix (or CSI, PMI, or TPMI) can be compressed and / or fed back based on DMD. The details of the M vectors can be found in the description of the M vectors in S302 above, and will not be repeated here. Optionally, the new method differs from Method 1 and Method 2. The new method may also have other names, such as method 3 or type 3, as long as it has the same function, it is within the scope of protection of this application.

[0271] The second device may determine the first indication information in multiple ways, or there may be multiple ways to determine the first indication information, such as method c1, method c2, or method c3:

[0272] Method c1: The second device may determine the first instruction information based on whether the first device has the first capability; or, the first instruction information is determined based on whether the first device has the first capability.

[0273] The first capability may be the ability to provide feedback and / or compress CSI based on DMD; or, the first capability may be the ability to process information (or data) based on DMD; or, the first capability may be the ability to provide feedback and / or compress precoding matrices based on DMD; or, the first capability may be the ability to determine multiple vectors based on recursive relationships between multiple vectors; or, the first capability may be the ability to calculate (or determine or derive) recursive relationships between multiple vectors; or, the first capability may include: the ability to determine multiple vectors based on recursive relationships between multiple vectors, and the ability to calculate (or determine or derive) recursive relationships between multiple vectors.

[0274] Optionally, if the first device has the first capability, the first indication information may indicate that the method of CSI feedback is a new method; and / or, if the first device does not have the first capability, the first indication information may indicate that the method of CSI feedback is method 1 or method 2.

[0275] The method by which the second device determines whether the first device has the first capability will be described in S305 below, and will not be elaborated here.

[0276] Through method c1, the second device can instruct the first device on the method of feedback CSI according to whether the first device has the first capability, thereby determining the method of feedback CSI that is appropriate to the first device’s capability and improving the second device’s management capability over the first device.

[0277] Method c2: The second device can determine the first indication information based on the correspondence between at least one condition and at least one method (hereinafter referred to as the first correspondence); or, the first indication information is determined based on the first correspondence.

[0278] Each of the at least one methods can be a method for feedback CSI. For example, at least one method may include at least one of the following: Method 1, Method 2, or a new method. The specific details of Method 1, Method 2, and the new method can be found in the description of Method 1, Method 2, and the new method in S304, and will not be repeated here.

[0279] The first correspondence can be pre-set, such as as specified in an agreement; or it can be determined by the second device; or it can be notified to the second device by other devices (e.g., core network equipment or the first device).

[0280] In some implementations, if a first condition in at least one condition is met and the first condition corresponds to a new method in at least one method, the first indication information may indicate that the method of feedback CSI is the new method.

[0281] For example, the first condition may include at least one of conditions a1 to a5 below. In conditions a1 and a3, the transmitting device is a device that transmits a signal according to the first information; for example, the transmitting device may be a second device (e.g., an access network device). In conditions a2 and a4, the receiving device is a device that receives a signal according to the first information; for example, the receiving device may be a first device (e.g., a terminal). Any one of the first to fifth thresholds below may be predefined, such as as specified by a protocol; or it may be determined by the second device; or it may be notified to the second device by another device (e.g., a core network device). Any one of the first to fifth thresholds may also have other names, as long as they have the same function, they are all within the scope of protection of this application. The first condition is described in detail below.

[0282] Condition a1: The number of transmitting antennas of the transmitting device is greater than or equal to a first threshold. For example, the number of transmitting antennas of the transmitting device is greater than or equal to 256. Optionally, the second device may be the transmitting device or located within the transmitting device. The second device can know the number of transmitting antennas of the transmitting device, thereby determining whether condition a1 is satisfied.

[0283] Condition a2: The number of receiving antennas of the receiving device is greater than or equal to a second threshold. For example, the number of receiving antennas of the receiving device is greater than or equal to 8. Optionally, the second device may receive information from the first device indicating the number of receiving antennas of the receiving device, thereby determining the number of receiving antennas of the receiving device, and thus determining whether condition a2 is satisfied.

[0284] Condition a3: The number of transmit antenna ports of the transmitting device is greater than or equal to the third threshold. For example, the number of transmit antenna ports of the transmitting device is greater than or equal to 256. Optionally, the second device may be the transmitting device or located within the transmitting device. The second device can know the number of transmit antenna ports of the transmitting device, thereby determining whether condition a3 is satisfied.

[0285] Condition a4: The number of receiving antenna ports of the receiving device is greater than or equal to a fourth threshold. For example, the number of receiving antenna ports of the receiving device is greater than or equal to 8. Optionally, the second device may receive information from the first device indicating the number of receiving antenna ports of the receiving device, thereby determining the number of receiving antenna ports of the receiving device, and further determining whether condition a4 is satisfied.

[0286] Condition a5: M is greater than or equal to the fifth threshold. For example, M is greater than or equal to 13. Optionally, the second device may configure (or schedule, indicate, or allocate) resources for the first device, thereby obtaining the number of sub-bands M in the resources, and thus determining whether condition a5 is satisfied.

[0287] In some examples, the first condition may include: condition a1, condition a2, and condition a5. For example, the first condition includes: the number of transmitting antennas of the transmitting device is greater than or equal to 256, the number of receiving antennas of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antennas of the second device is 512, the number of receiving antennas of the first device is 16, and M is 16, then the first condition is met, and the first indication information may indicate that the method of CSI feedback is a new method.

[0288] In other examples, the first condition may include: condition a3, condition a4, and condition a5. For example, the first condition includes: the number of transmit antenna ports of the transmitting device is greater than or equal to 256, the number of receive antenna ports of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmit antenna ports of the second device is 512, the number of receive antenna ports of the first device is 16, and M is 16, then the first condition is met, and the first indication information may indicate that the method of CSI feedback is a new method.

[0289] It should be understood that the numbers in the first condition above are merely examples and are not intended to limit the scope of protection of this application. For example, other values ​​may also be used for the numbers in the first condition.

[0290] In other implementations, if a second condition in at least one condition is met, and the second condition corresponds to mode 1 or mode 2 in at least one mode, the first indication information may indicate that the mode of feedback CSI is mode 1 or mode 2.

[0291] For example, the second condition may include at least one of conditions b1 to b5 below. In conditions b1 and b3, the transmitting device is a device that transmits a signal according to the first information; for example, the transmitting device may be a second device (e.g., an access network device). In conditions b2 and b4, the receiving device is a device that receives a signal according to the first information; for example, the receiving device may be a first device (e.g., a terminal). Any one of the sixth to tenth thresholds below may be predefined, such as as specified in a protocol; or may be determined by the second device; or may be notified to the second device by another device (e.g., a core network device). Any one of the sixth to tenth thresholds may also have other names, as long as they have the same function, they are all within the scope of protection of this application. The second condition is described in detail below.

[0292] Condition b1: The number of transmitting antennas of the transmitting device is less than the sixth threshold. For example, the number of transmitting antennas of the transmitting device is less than 32. Optionally, the sixth threshold may be less than or equal to the first threshold. Optionally, the second device may be the transmitting device or located within the transmitting device, and the second device may know the number of transmitting antennas of the transmitting device, thereby determining whether condition b1 is satisfied.

[0293] Condition b2: The number of receiving antennas of the receiving device is less than the seventh threshold. For example, the number of receiving antennas of the receiving device is less than 8. Optionally, the seventh threshold may be less than or equal to the second threshold. Optionally, the second device may receive information from the first device indicating the number of receiving antennas of the receiving device, thereby determining the number of receiving antennas of the receiving device, and thus determining whether condition b2 is satisfied.

[0294] Condition b3: The number of transmit antenna ports of the transmitting device is less than the eighth threshold. For example, the number of transmit antenna ports of the transmitting device is less than or equal to 8. Optionally, the eighth threshold may be less than or equal to the third threshold. Optionally, the second device may know the number of transmit antenna ports of the transmitting device, thereby determining whether condition b3 is satisfied.

[0295] Condition b4: The number of receiving antenna ports of the receiving device is less than the ninth threshold. For example, the number of receiving antenna ports of the receiving device is less than 8. Optionally, the ninth threshold may be less than or equal to the fourth threshold. Optionally, the second device may receive information from the first device indicating the number of receiving antenna ports of the receiving device, thereby determining the number of receiving antenna ports of the receiving device, and thus determining whether condition b4 is satisfied.

[0296] Condition b5: M is less than the tenth threshold. For example, M is less than 13. Optionally, the tenth threshold may be less than or equal to the fifth threshold. Optionally, the second device may configure (or schedule, indicate, or allocate) resources for the first device, thereby obtaining the number of sub-bands M in the resources, and thus determining whether condition b5 is satisfied.

[0297] In some examples, the second condition may include: condition b1, condition b2, and condition b5. For example, the second condition includes: the number of transmitting antennas of the transmitting device is less than 32, the number of receiving antennas of the receiving device is less than 8, and M is less than 13. If the number of transmitting antennas of the transmitting device is 16, the number of receiving antennas of the receiving device is 4, and M is 10, then the second condition is met, and the first indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0298] In some other examples, the second condition may include: condition b3, condition b4, and condition b5. For example, the second condition includes: the number of transmit antenna ports of the transmitting device is less than 32, the number of receive antenna ports of the receiving device is less than 8, and M is less than 13. If the number of transmit antenna ports of the transmitting device is 16, the number of receive antenna ports of the receiving device is 8, and M is 10, then the second condition is met, and the first indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0299] It should be understood that the numbers in the second condition above are merely examples and are not intended to limit the scope of protection of this application. For example, other values ​​may also be used for the numbers in the second condition.

[0300] For example, Table 3 shows one possible example of the correspondence between at least one condition and at least one manner.

[0301] Table 3

[0302] It should be understood that Table 3 is merely an example and is not intended to limit the scope of protection of this application. In practical applications, Table 3 may also be modified in other ways; for example, Table 3 may be modified into Table 4.

[0303] Table 4

[0304] Method c3: The second device can determine the first instruction information on its own.

[0305] Optionally, the second device may determine the first indication information based on whether the second device has the first capability; or, the first indication information may be determined based on whether the second device has the first capability. The specific content of the first capability can be found in the description of the first capability in method c1, and will not be repeated here. For example, if the second device has the first capability, the first indication information may indicate that the method of CSI feedback is a new method; and / or, if the second device does not have the first capability, the first indication information may indicate that the method of CSI feedback is method 1 or method 2.

[0306] It should be understood that modes c1 to c3 can be independent or combined with each other. For example, modes c1 and c3 can be combined, where the first device and the second device both have the first capability, the first indication information can indicate that the mode of CSI feedback is a new mode; and / or, where the first device and / or the second device do not have the first capability, the first indication information can indicate that the mode of CSI feedback is mode 1 or mode 2.

[0307] In S304, the first indication information can be carried in a conventional message or in a new message. For example, the first indication information can be carried in a DCI, MAC control element (MAC CE) or RRC message.

[0308] Optionally, S304 can precede S302. This application does not restrict the execution order of S304 and S301.

[0309] After receiving the first instruction information, the first device can feed back a precoding matrix based on the first instruction information. There can be multiple ways to feed back the matrix, such as mode d1, mode d2, or mode d3.

[0310] Mode d1: When the first indication information indicates that the method for feeding back channel status information is a new method, the first device sends the first information; correspondingly, the second device receives the first information. In other words, when the first indication information indicates that the method for feeding back channel status information is a new method, the first device can execute S302. The specific details of the new method can be found in the description of the new method in S304, and will not be repeated here.

[0311] Optionally, if the first indication information indicates that the method for feeding back channel status information is a new method, and the first device has a first capability, the first device sends the first information; correspondingly, the second device receives the first information. The specific content of the first capability can be referred to the description of the first capability in method c1 above, and will not be repeated here. Optionally, this method can be combined with any of methods c1 to c3 above.

[0312] In this manner, the first device can send first information to the second device according to the instructions of the second device. Furthermore, in this manner, the second device can instruct the first device on the method of CSI feedback, thus allowing the second device to flexibly manage the method of CSI feedback from the first device.

[0313] Mode d2: When the first indication information indicates that the mode for feeding back channel state information is mode 1, the first device sends a PMI determined according to the type 1 codebook; correspondingly, the second device receives the PMI determined according to the type 1 codebook. This application does not limit the method of determining the PMI according to the type 1 codebook; for example, the method specified in the protocol can be used.

[0314] Method d3: When the first indication information indicates that the method for feeding back channel state information is Method 2, the first device sends the PMI determined according to the Type 2 codebook; correspondingly, the second device receives the PMI determined according to the Type 2 codebook. This application does not limit the method of determining the PMI according to the Type 2 codebook; for example, the method specified in the protocol can be used.

[0315] Optionally, the method shown in Figure 3 further includes S305:

[0316] S305: The first device sends the second information; correspondingly, the second device receives the second information.

[0317] Optionally, S305 can be used in scenario 1 above.

[0318] The second information indicates whether the first device possesses the first capability. The specific details of the first capability can be found in the description of the first capability in method c1 above, and will not be repeated here. Thus, the second device can accurately determine whether the first device possesses the first capability based on the second information.

[0319] In some implementations, S305 may precede S304. Optionally, in this implementation, mode c1 may be replaced by: the second device determining the first indication information based on the second information; or, the first indication information may be determined based on the second information.

[0320] In other implementations, S305 may follow S304. For example, after receiving the first instruction information, the first device may send second information so that the second device can determine whether the first device has the first capability. If the first device has the first capability, the second device may receive the first information and execute S303 according to the first information; if the first device does not have the first capability, the second device may receive the PMI determined according to a Type 1 codebook or a Type 2 codebook, determine the second precoding matrix accordingly, and send a downlink signal to the first device according to the second precoding matrix.

[0321] This application does not limit the specific manner in which the first device transmits the second information. For example, the first device may transmit the second information periodically or aperiodically. As another example, the first device may transmit the second information independently, or the first device may transmit the second information based on a request (or instruction) from the second device. The above examples may be independent or combined with each other.

[0322] Furthermore, the second information can be carried within a traditional message or a new message, without restriction. For example, the second information can be carried within a UCI or RRC message.

[0323] Among other possible approaches, the method shown in Figure 3 also includes S306:

[0324] S306: The first device can acquire a correspondence between at least one condition and at least one mode (hereinafter referred to as the first correspondence). Each of the at least one mode is a mode for feedback CSI.

[0325] Optionally, S306 can be used in either scenario 1 or scenario 2 above.

[0326] The specific details of the first correspondence can be found in the explanation of the first correspondence in method c2 above, and will not be repeated here. The first correspondence can be pre-set, such as as specified by the protocol; or it can be determined by the first device; or it can be notified to the first device by other devices (e.g., core network equipment or the second device).

[0327] After obtaining the first correspondence, the first device can feed back the precoding matrix based on the first correspondence. There can be multiple ways to feed back the matrix, such as mode e1 or mode e2.

[0328] Method e1: If a first condition in at least one of the conditions is met, and the first condition corresponds to a new method in at least one of the methods, the first device sends first information; correspondingly, the second device receives the first information. In other words, if a first condition in at least one of the conditions is met, and the first condition corresponds to a new method in at least one of the methods, the first device can execute S302.

[0329] For details on the first condition, please refer to the explanation of the first condition in method c2; repeated points will not be repeated. The differences between scenario 1 and scenario 2 will be explained below.

[0330] For scenario 1:

[0331] For example, the first condition includes condition a1 in method c2. The first device can receive information from the second device indicating the number of transmit antennas of the transmitting device, thereby determining the number of transmit antennas of the transmitting device, and thus determining whether condition a1 is satisfied. As another example, the first condition includes condition a2 in method c2. The first device can be a receiving device or located within a receiving device, and the first device can know the number of receive antennas of the receiving device, thereby determining whether condition a2 is satisfied. Yet another example, the first condition includes condition a3 in method c2. The first device can receive information from the second device indicating the number of transmit antenna ports of the transmitting device, thereby determining the number of transmit antenna ports of the transmitting device, and thus determining whether condition a3 is satisfied. Yet another example, the first condition includes condition a4 in method c2. The first device can be a receiving device or located within a receiving device, and the first device can know the number of receive antenna ports of the receiving device, thereby determining whether condition a4 is satisfied. Yet another example, the first condition includes condition a5 in method c2. The first device can receive information from the second device indicating the configuration (or scheduling, instruction, or allocation) of resources for the first device, thereby determining the number M of sub-bands in the resource, and thus determining whether condition a5 is satisfied. The above examples can be independent or combined.

[0332] In some examples, the first condition may include: condition a1, condition a2, and condition a5. For example, the first condition includes: the number of transmitting antennas of the transmitting device is greater than or equal to 256, the number of receiving antennas of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antennas of the second device is 512, the number of receiving antennas of the first device is 16, and M is 16, then the first condition is met, and the first device can transmit the first information.

[0333] In other examples, the first condition may include: condition a3, condition a4, and condition a5. For example, the first condition includes: the number of transmitting antenna ports of the transmitting device is greater than or equal to 256, the number of receiving antenna ports of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antenna ports of the second device is 512, the number of receiving antenna ports of the first device is 16, and M is 16, then the first condition is met, and the first device can transmit the first information.

[0334] For scenario 2:

[0335] For example, the first condition includes condition a1 in method c2. The first device may be a transmitting device or located within a transmitting device. The first device can know the number of transmitting antennas of the transmitting device, thereby determining whether condition a1 is satisfied. As another example, the first condition includes condition a2 in method c2. The first device can receive information from the second device indicating the number of receiving antennas of the receiving device, thereby determining the number of receiving antennas of the receiving device, and thus determining whether condition a2 is satisfied. Yet another example, the first condition includes condition a3 in method c2. The first device may be a transmitting device or located within a transmitting device. The first device can know the number of transmitting antenna ports of the transmitting device, thereby determining whether condition a3 is satisfied. Yet another example, the first condition includes condition a4 in method c2. The first device can receive information from the second device indicating the number of receiving antenna ports of the receiving device, thereby determining the number of receiving antenna ports of the receiving device, and thus determining whether condition a4 is satisfied. Yet another example, the first condition includes condition a5 in method c2. The first device can configure (or schedule, instruct, or allocate) resources for the second device, thereby determining the number M of sub-bands in those resources, and thus determining whether condition a5 is satisfied. The above examples can be independent or combined.

[0336] In some examples, the first condition may include: condition a1, condition a2, and condition a5. For example, the first condition includes: the number of transmitting antennas of the transmitting device is greater than or equal to 256, the number of receiving antennas of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antennas of the first device is 512, the number of receiving antennas of the second device is 16, and M is 16, then the first condition is met, and the first device can transmit the first information.

[0337] In other examples, the first condition may include: condition a3, condition a4, and condition a5. For example, the first condition includes: the number of transmitting antenna ports of the transmitting device is greater than or equal to 256, the number of receiving antenna ports of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antenna ports of the first device is 512, the number of receiving antenna ports of the second device is 16, and M is 16, then the first condition is met, and the first device can transmit the first information.

[0338] For details on the new method, please refer to the description of the new method in S304, which will not be repeated here.

[0339] In mode e1, the first device can accurately determine whether to send the first information based on the first correspondence. In this mode, the second device may not need to indicate the method of feedback CSI to the first device, thereby reducing signaling overhead.

[0340] Method e2: When the second condition in at least one condition is met, and the second condition corresponds to Method 1 or Method 2 in at least one method, the first device sends a PMI determined according to the method corresponding to the second condition (e.g., Method 1 or Method 2); accordingly, the second device receives the PMI determined according to the method corresponding to the second condition.

[0341] For details regarding the second condition, please refer to the explanation of the second condition in method c2; repeated points will not be elaborated upon. The differences between scenario 1 and scenario 2 will be explained below.

[0342] For scenario 1:

[0343] For example, the second condition includes condition b1 in method c2. The first device can receive information from the second device indicating the number of transmit antennas of the transmitting device, thereby determining the number of transmit antennas of the transmitting device, and thus determining whether condition b1 is satisfied. As another example, the second condition includes condition b2 in method c2. The first device can be a receiving device or located within a receiving device, and the first device can know the number of receive antennas of the receiving device, thereby determining whether condition b2 is satisfied. As yet another example, the second condition includes condition b3 in method c2. The first device can receive information from the second device indicating the number of transmit antenna ports of the transmitting device, thereby determining the number of transmit antenna ports of the transmitting device, and thus determining whether condition b3 is satisfied. As yet another example, the second condition includes condition b4 in method c2. The first device can be a receiving device or located within a receiving device, and the first device can know the number of receive antenna ports of the receiving device, thereby determining whether condition b4 is satisfied. As yet another example, the second condition includes condition b5 in method c2. The first device can receive information from the second device indicating the configuration (or scheduling, instruction, or allocation) of resources for the first device, thereby determining the number of sub-bands M in the resource, and thus determining whether condition b5 is satisfied. The above examples can be independent or combined with each other.

[0344] For scenario 2:

[0345] For example, the second condition includes condition b1 in method c2. The first device may be a transmitting device or located within a transmitting device. The first device can know the number of transmitting antennas of the transmitting device, thereby determining whether condition b1 is satisfied. As another example, the second condition includes condition b2 in method c2. The first device can receive information from the second device indicating the number of receiving antennas of the receiving device, thereby determining the number of receiving antennas of the receiving device, and thus determining whether condition b2 is satisfied. As yet another example, the second condition includes condition b3 in method c2. The first device may be a transmitting device or located within a transmitting device. The first device can know the number of transmitting antenna ports of the transmitting device, thereby determining whether condition b3 is satisfied. As yet another example, the second condition includes condition b4 in method c2. The first device can receive information from the second device indicating the number of receiving antenna ports of the receiving device, thereby determining the number of receiving antenna ports of the receiving device, and thus determining whether condition b4 is satisfied. As yet another example, the second condition includes condition b5 in method c2. The first device can configure (or schedule, instruct, or allocate) resources for the second device, thereby determining the number M of sub-bands in those resources, and thus determining whether condition b5 is satisfied. The above examples can be independent or combined.

[0346] This application does not limit the specific content of PMI determined according to method 1 or method 2. For example, it can be determined using the method specified in the agreement.

[0347] S306 can precede S302. This application does not restrict the execution order of S306 and S301.

[0348] In other possible embodiments, S302 may include: if the first condition is met, the first device may send the first information; correspondingly, the second device may receive the first information. The specific content of the first condition can be found in the description of the first condition in embodiment c2, and will not be repeated here.

[0349] Among some possible approaches, the method shown in Figure 3 may also include S307:

[0350] S307: The first device sends a first instruction message; correspondingly, the second device receives the first instruction message. The first instruction message can be used to indicate the method of feedback control system (CSI).

[0351] Optionally, S307 can be used in scenario 2 above.

[0352] For details regarding the first instruction information, please refer to the description of the first instruction information in S304, which will not be repeated here.

[0353] The first device may determine the first instruction information in multiple ways, or there may be multiple ways to determine the first instruction information, such as method f1, method f2, or method f3:

[0354] Method f1: The first device may determine the first instruction information based on whether the second device has the first capability; or, the first instruction information is determined based on whether the first device has the first capability.

[0355] The specific details of method f1 can be found in method c1, except that the first device and the second device are interchanged, and will not be repeated here.

[0356] Method f2: The first device can determine the first indication information based on the correspondence between at least one condition and at least one method (hereinafter referred to as the first correspondence); or, the first indication information is determined based on the first correspondence.

[0357] For details on the first correspondence, please refer to the explanation of the first correspondence in method c2, which will not be repeated here.

[0358] In some implementations, if the first condition in at least one of the conditions is met, and the first condition corresponds to a new method in at least one of the methods, the first indication information may indicate that the method of feedback CSI is the new method. The specific content of the first condition can be found in the explanation of the first condition for scenario 2 in method e1, and will not be repeated here.

[0359] In some examples, the first condition may include: condition a1, condition a2, and condition a5. For example, the first condition includes: the number of transmitting antennas of the transmitting device is greater than or equal to 256, the number of receiving antennas of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmitting antennas of the second device is 512, the number of receiving antennas of the first device is 16, and M is 16, then the first condition is met, and the first indication information may indicate that the method of CSI feedback is a new method.

[0360] In other examples, the first condition may include: condition a3, condition a4, and condition a5. For example, the first condition includes: the number of transmit antenna ports of the transmitting device is greater than or equal to 256, the number of receive antenna ports of the receiving device is greater than or equal to 8, and M is greater than or equal to 13. If the number of transmit antenna ports of the second device is 512, the number of receive antenna ports of the first device is 16, and M is 16, then the first condition is met, and the first indication information may indicate that the method of CSI feedback is a new method.

[0361] In other implementations, if the second condition in at least one of the conditions is met, and the second condition corresponds to method 1 or method 2 in at least one of the methods, the first indication information may indicate that the method for feedback CSI is method 1 or method 2. The specific content of the second condition can be found in the explanation of the second condition for scenario 2 in method e2, and will not be repeated here.

[0362] In some examples, the second condition may include: condition b1, condition b2, and condition b5. For example, the second condition includes: the number of transmitting antennas of the transmitting device is less than 32, the number of receiving antennas of the receiving device is less than 8, and M is less than 13. If the number of transmitting antennas of the transmitting device is 16, the number of receiving antennas of the receiving device is 4, and M is 10, then the second condition is met, and the first indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0363] In some other examples, the second condition may include: condition b3, condition b4, and condition b5. For example, the second condition includes: the number of transmit antenna ports of the transmitting device is less than 32, the number of receive antenna ports of the receiving device is less than 8, and M is less than 13. If the number of transmit antenna ports of the transmitting device is 16, the number of receive antenna ports of the receiving device is 8, and M is 10, then the second condition is met, and the first indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0364] Method f3: The first device can determine the first instruction information on its own.

[0365] The details of method f3 can be found in method c3, except that the second device is replaced by the first device, and will not be repeated here.

[0366] It should be understood that modes f1 to f3 can be independent or combined with each other. For example, modes f1 and f3 can be combined, where the first device and the second device both have the first capability, the first indication information can indicate that the mode of CSI feedback is a new mode; and / or, where the first device and / or the second device do not have the first capability, the first indication information can indicate that the mode of CSI feedback is mode 1 or mode 2.

[0367] In S307, the first indication information can be carried in a conventional message or in a new message. For example, the first indication information can be carried in a DCI, MAC CE, or RRC message.

[0368] The order of S307 with S301 to S302 is not limited. Optionally, S307 may precede S301 and / or S302.

[0369] Optionally, if the first indication information indicates that the CSI feedback method is a new method, the first device may send the first information; correspondingly, the second device may receive the first information. In other words, if the first indication information indicates that the CSI feedback method is a new method, the first device may execute S302. In this manner, the first device may indicate to the second device that the CSI feedback method is a new method. Thus, after sending the first information to the second device, the second device may process the first information according to the new method; for example, it may determine M vectors based on the first information. Furthermore, in this manner, the first device may indicate the CSI feedback method to the second device, allowing the first device to flexibly manage the CSI feedback method.

[0370] Optionally, after receiving the first instruction information, the second device may send a signal according to the first instruction information. There may be multiple ways to send the signal, such as mode g1 or mode g2.

[0371] Method g1: When the first indication information indicates that the CSI feedback method is a new method, the second device may send a first signal; correspondingly, the first device receives the first signal. The first signal is sent according to the first precoding matrix. In other words, when the first indication information indicates that the CSI feedback method is a new method, the second device may execute S303.

[0372] In this manner, the second device can send a first signal to the second device according to the instructions of the first device. Furthermore, in this manner, the first device can instruct the second device on the method of CSI feedback, thus allowing the first device to flexibly manage the method of CSI feedback from the second device.

[0373] Mode g2: When the first indication information indicates that the CSI feedback mode is Mode 1 or Mode 2, the second device may send a second signal; correspondingly, the first device receives the second signal. The second signal is sent according to a second precoding matrix. The second precoding matrix is ​​determined according to a Type 1 codebook or a Type 2 codebook. This application does not limit the method of determining the second precoding matrix according to a Type 1 codebook or a Type 2 codebook; for example, it may be determined using a method specified in the protocol.

[0374] Optionally, the method shown in Figure 3 may also include S308:

[0375] S308: The second device can send third information; correspondingly, the first device can receive the third information.

[0376] Optionally, S308 can be used in scenario 2 above.

[0377] The third information can indicate whether the second device possesses the first capability. The specific details of the first capability can be found in the description of the first capability in method c1 above, and will not be repeated here. In this way, the first device can accurately determine whether the second device possesses the first capability based on the third information.

[0378] In some implementations, S308 may precede S307. Optionally, in this implementation, mode f1 may be replaced by: the first device determining the first indication information based on the third information; or, the first indication information may be determined based on the third information.

[0379] In other implementations, S308 may follow S307. For example, after receiving the first indication information, the second device may send third information so that the first device can determine whether the second device has the first capability. If the second device has the first capability, the first device may send the first information, and correspondingly, the second device may receive the first information and execute S303 according to the first information; if the second device does not have the first capability, the first device may send a TPMI determined according to a Type 1 codebook or a Type 2 codebook, and the second device may receive the TPMI determined according to a Type 1 codebook or a Type 2 codebook, determine a second precoding matrix accordingly, and send an uplink signal to the first device according to the second precoding matrix.

[0380] In some possible ways, the first information may also indicate a second matrix; or, the first information may indicate a first vector and a second matrix. The first vector may belong to N vectors, where N is a positive integer. The second matrix may be used to indicate the recursive relationship (or association or correspondence) between different vectors among the N vectors; or, the second matrix may be used to determine the vectors among the N vectors other than the first vector; or, the second matrix and the first vector may be used to determine the N vectors.

[0381] To make it easier to understand, we will first explain the N vectors.

[0382] N vectors can correspond to N time units, for example, N vectors can be one-to-one with N time units. Each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units; or, each of the N vectors has a correspondence (or association) with the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained (or determined) based on a first reference signal. For example, the first reference signal in S301 can be a reference signal on one or more time units, and the precoding matrix of each of the N time units is obtained (or determined) based on the reference signals on the one or more time units. Some or all of the one or more time units can be before the N time units; or, the one or more time units can be the N time units. This application does not limit the specific details of obtaining the precoding matrix of each of the N time units.

[0383] The following explanation uses the q-th vector (hereinafter referred to as the q-th vector) among these N vectors as an example. Here, q takes integer values ​​from 1 to N.

[0384] The q-th vector can be the coefficient corresponding to the precoding matrix of the q-th time unit (hereinafter referred to as the q-th time unit) in the N time units. The q-th vector can have multiple possible forms, such as form h1 or form h2.

[0385] Method h1: The q-th vector can be a column of the coefficient matrix corresponding to the precoding matrix of the j-th stream in the q-th time unit; or, the coefficients corresponding to the precoding matrix of the q-th time unit can be a column of the coefficient matrix corresponding to the precoding matrix of the j-th stream in the q-th time unit. j is an integer greater than or equal to 1 and less than or equal to J; J is the stream number, and J is a positive integer.

[0386] Method h2: The q-th vector can be a column of the coefficient matrix corresponding to the precoding matrix of the J-stream in the q-th time unit; or, the coefficients corresponding to the precoding matrix of the q-th time unit can be a column of the coefficient matrix corresponding to the precoding matrix of the J-stream in the q-th time unit.

[0387] For details on methods h1 and h2, please refer to methods a1 and a2 respectively, except that M is replaced with N, sub-band is replaced with time unit, and k is replaced with q, which will not be elaborated further.

[0388] The first vector and the second matrix will be explained below based on N vectors.

[0389] 1. First vector:

[0390] As mentioned earlier, the first vector belongs to the N vectors. Optionally, the first vector is one of the N vectors. For example (hereinafter referred to as Example 3), the N vectors include: x 1,1 ,x 1,2 ,…,x 1,N In other words, the coefficients corresponding to the precoding matrix for these N time units include: x 1,1 ,x 1,2 ,…,x 1,N Among them, x 1,q Let x be the q-th vector among these N vectors; in other words, x 1,q Let x be the coefficients corresponding to the precoding matrix of the q-th time unit out of N time units. q can be referred to as the vector index and / or the time unit index, and q takes integer values ​​from 1 to N. The first vector can be x. 1,1 ,x 1,2 ,…,x 1,N One of them. For example, the first vector could be x. 1,1 , or x 1,2 , or x 1,3 , or x 1,N It should be understood that the first vector can also be any N vectors excluding x. 1,1 ,x 1,2 ,x 1,3 and x 1,N Other vectors besides these are not listed one by one.

[0391] Optionally, the first vector can be the coefficients corresponding to the precoding matrix of the first time unit, and the first time unit can be the earliest time unit among the N time units. For example (hereinafter referred to as Example 4), the N vectors are as shown in Example 3. The smaller the value of q, the earlier the time corresponding to the q-th time unit; the larger the value of q, the later the time corresponding to the q-th time unit. In this case, the first time unit can be the 1st time unit among the N time units, and the first vector can be x. 1,1 .

[0392] To simplify the description, the specific details of the N vectors in the examples below can be found in Example 3 or Example 4, and will not be repeated here.

[0393] 2. Second matrix:

[0394] As mentioned earlier, the second matrix can be used to indicate the recursive relationships between different vectors in N vectors.

[0395] In some examples, where the q-th vector among the N vectors is a vector from mode h1, and the column indices of the coefficient matrices corresponding to different vectors among the N vectors are the same, the second matrix can indicate the recursive relationship between the j-th column vectors in the coefficient matrices corresponding to the precoding matrices of the j-th stream in different time units across the N time units. For example, the first vector among the N vectors can be the first column vector in the coefficient matrix corresponding to the precoding matrix of the first stream in the first time unit across the N time units; the second vector among the N vectors can be the first column vector in the coefficient matrix corresponding to the precoding matrix of the first stream in the second time unit across the N time units, and so on. In this case, the second matrix can indicate the recursive relationship between the first column vectors in the coefficient matrices corresponding to the precoding matrices of the N time units across the N time units.

[0396] In other examples, where the q-th vector among the N vectors is a vector from mode h2, the second matrix can indicate the recursive relationship between columns of the coefficient matrices corresponding to the precoding matrices of the J-stream in different time units across the N time units. For example, the first vector among the N vectors can be the first column vector in the coefficient matrix corresponding to the precoding matrix of the J-stream in the first time unit across the N time units; the second vector among the N vectors can be the first column vector in the coefficient matrix corresponding to the precoding matrix of the J-stream in the second time unit across the N time units, and so on. In this case, the second matrix can indicate the recursive relationship between the first column vectors of the coefficient matrices corresponding to the precoding matrices of the J-stream in different time units across the N time units.

[0397] Optionally, the second matrix can be used to indicate the recursive relationship (or association or correspondence) between the N vectors and the vectors corresponding to adjacent time units in the N time units; or, the product of the second matrix and the first vector can be used to determine the vector adjacent to the first vector among the N vectors; or, the product of the second matrix and one of the N vectors can be used to determine another vector adjacent to that vector among the N vectors. Adjacent time units can be time units with adjacent serial numbers. For example, the first time unit and the second time unit in the N time units are adjacent time units. Adjacent vectors can be vectors with adjacent serial numbers. For example, the first vector and the second vector in the N vectors are adjacent vectors.

[0398] It should be understood that the second matrix may also have other forms, all of which are within the scope of protection of this application. For example, the second matrix is ​​a recursive relationship between N vectors and vectors corresponding to time units that are separated by O time units in the N time units, where O is a positive integer.

[0399] Optional, the second matrix G tThe following formula (2) can be satisfied; or, the first device can determine the second matrix G according to the following formula (2). t G t =Y2*pinv(X2), formula (2)

[0400] Where, Y2=[x 1,2 ,x 1,3 ,…,x 1,N ], X2 = [x 1,1 ,x 1,2 ,…,x 1,N-1 ], pinv indicates the pseudo-inverse operation. x 1,q For details, please refer to Example 3 or Example 4 above regarding x. 1,q The explanation is that q takes on all integers greater than 1 to N, which will not be elaborated further.

[0401] It should be understood that formula (2) is merely an example and is not intended to limit the scope of protection of this application. In practical applications, formula (2) can also be modified; for example, the positions of the column vectors in X2 and / or Y2 can be changed. Also, for example, X2 and / or Y2 may include fewer column vectors. And yet another example, x 1,q Let x be a matrix. 1,q The positions of the column vectors can change in X2 and / or Y2. Any modifications to formula (2) are within the scope of protection of this application.

[0402] In this way, the first device can accurately determine the second matrix according to formula (2), thereby accurately determining the recursive relationship between different vectors among N vectors.

[0403] The following example illustrates how the second matrix and the first vector can be used to determine the N vectors, using the recursive relationship between the second matrix and the vectors corresponding to adjacent time units in the N time units as an example.

[0404] In some implementations, as shown in Figure 5A, the first vector is x 1,1 The second matrix is ​​G t In the case of the N vectors, the q-th vector x 1,q =G t q-1 *x 1,1 Where q takes any integer from 1 to N, and G... t q-1 For G t x raised to the power of q-1. For example, x 1,2 =G t *x 1,1 For example, x 1,3=G t 2 *x 1,1 For example, x 1,N =G t N-1 *x 1,1 Thus, after receiving the first information indicating the second matrix and the first vector, the second device can accurately determine the vector with an index greater than the first vector among the N vectors, thereby accurately determining the N vectors.

[0405] In other implementations, as shown in Figure 5B, the first vector is x 1,N The second matrix is ​​G t In the case of the N vectors, the q-th vector x 1,q =inv(G t ) N-q *x 1,N Where q takes integer values ​​from 1 to N, inv(G t ) N-q for inv(G t ) to the power of Nq, inv(G t ) is G t The inverse matrix. For example, x 1,N-1 =inv(G t )*x 1,N For example, x 1,N-2 =inv(G t ) 2 *x 1,N For example, x 1,1 =inv(G t ) N-1 *x 1,N Thus, after receiving the first information indicating the second matrix and the first vector, the second device can accurately determine the vector with an index less than the first vector among the N vectors, thereby accurately determining the N vectors.

[0406] In some implementations, the first vector can be represented as x 1,q1 q1 is a positive integer; the second matrix is ​​G. t When q is greater than q1, x 1,q =G t q-q1 *x 1,q1 When q is less than q1, x 1,q =inv(G t ) q1-q *x 1,q1 Where q takes any integer from 1 to N, and G... t q-q1 For G t q-q1, inv(G t) q1-q for inv(G t ) to the power of q1-q, inv(G t ) is G t The inverse matrix. For example, as shown in Figure 5C, the first vector is x. 1,3 The second matrix is ​​G t When q is greater than 3, the q-th vector x among the N vectors... 1,q =G t q-3 *x 1,3 When q is less than 3, the q-th vector x among the N vectors 1,q =inv(G t ) 3-q *x 1,3 For example, x 1,4 =G t *x 1,3 For example, x 1,5 =G t 2 *x 1,3 For example, x 1,1 =inv(G t ) 2 *x 1,3 For example, x 1,2 =inv(G t )*x 1,3 Thus, after receiving the first information indicating the second matrix and the first vector, the second device can accurately determine the N vectors excluding the first vector, thereby accurately determining the N vectors. Optionally, in this implementation, the first vector can be the vector with the middle index among the N vectors. In this way, the difference between the first vector and the vectors other than the first vector among the N vectors is relatively small, thereby allowing for a more accurate determination of the N vectors.

[0407] Optionally, the first vector, the first matrix, and the second matrix can be used to determine the coefficients x corresponding to the precoding matrix of the k-th subband at the q-th time unit. k,q Alternatively, the second device can determine the coefficient x corresponding to the precoding matrix of the k-th sub-band at the q-th time unit based on the first vector, the first matrix, and the second matrix. k,q x k,q This can be used to determine the precoding matrix of the k-th subband at the q-th time unit. The determination method can be found in the explanation of "M vectors can be used to determine the precoding matrix of the M subbands" in S303, which will not be repeated here. Here, q takes integers from 1 to N, and k takes integers from 1 to M.

[0408] In some examples, as shown in Figure 6, the first vector is x. 1,1 xk,q and x 1,1 The formula can be satisfied: x k,q =G t q-1 *G f k-1 *x 1,1 Among them, G t G is the second matrix. t q-1 For G t q-1; G f Let G be the first matrix. f k-1 For G f The (k-1)th power. For example, x 3,3 =G t 2 *G f 2 *x 1,1 For example, x M,N =G t N-1 *G f M-1 *x 1,1 .

[0409] In other examples, the first vector is x M,N x k,q and x M,N The formula can be satisfied: x k,q =inv(G t ) N-q *inv(G f ) M-k *x M,N Among them, inv(G t ) N-q for inv(G t ) to the power of Nq, inv(G t ) is G t inverse matrix; inv(G f ) M-k for inv(G f ) to the power of Mk, inv(G f ) is G f The inverse matrix.

[0410] Using this method, the second device can accurately determine the coefficients corresponding to the precoding matrix of the k-th sub-band in the q-th time unit based on the first vector, the first matrix, and the second matrix, thereby determining M*N vectors based on the first vector, the first matrix, and the second matrix.

[0411] Accordingly, in S303, the first precoding matrix is ​​determined based on the following precoding matrices: the precoding matrices of some or all of the M subbands, and the precoding matrices of some or all of the N time units. The method of determination can be found in the explanation in S303 that "the first precoding matrix can be determined based on the precoding matrices of some or all of the M subbands", and will not be repeated here.

[0412] As mentioned earlier, the first information can indicate the first vector and the second matrix, and there can be multiple ways of indicating it, such as mode i1 or mode i2.

[0413] Method i1: The first information may include a first vector and a second matrix.

[0414] For example, in the first vector x 1,1 The second matrix is ​​G t In this case, the first piece of information may include: x 1,1 and G t .

[0415] For example, when the first vector is x 1,N The second matrix is ​​G t In this case, the first piece of information may include: x 1,N and G t .

[0416] In this manner, the second device can accurately determine the first vector and the second matrix based on the first information. Furthermore, in this method, the first information can directly indicate the first vector and the second matrix, thus eliminating the need for the second device to calculate and determine the first vector and the second matrix, thereby reducing the computational complexity of the second device.

[0417] Method i2: The first information may include information that corresponds to the first vector and / or the second matrix.

[0418] In some implementations, the first information may include: a first vector, Λ2, and Ψ2. Here, Λ2 is a diagonal matrix; Ψ2 is the matrix obtained by eigenvalue decomposition of the second matrix, and Ψ2 has the same number of rows and columns as the second matrix. The second matrix has the same number of rows and columns. Λ2, Ψ2, and the second matrix satisfy the following formula: G t =Ψ2*Λ2*Ψ2 H G t This is the second matrix. Ψ2 H It can be the conjugate transpose of Ψ². For example, in the first vector x... 1,1 The second matrix is ​​G t And G t =Ψ2*Λ2*Ψ2 H In this case, the first piece of information may include: x 1,1Λ2 and Ψ2.

[0419] In this implementation, the second device can accurately determine the second matrix based on Λ2 and Ψ2. Furthermore, in this implementation, the second device can accurately determine the second matrix based on Λ2, Ψ2, and Ψ2. H This involves parallel computation of all vectors except the first vector out of N vectors. For example, if the first vector is x... 1,1 The second matrix is ​​G t In this case, the third vector among the N vectors can be x. 1,1 *G t 2 =x 1,1 *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H =x 1,1 *Ψ2*Λ2 2 *Ψ2 H The 4th vector among these N vectors can be x. 1,1 *G t 3 =x 1,1 *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H =x 1,1 *Ψ2*Λ2 3 *Ψ2 H In this way, the second device can compute all vectors except the first vector in N vectors in parallel, thereby saving computation time and resources. Furthermore, in this implementation, the second device can compute the q-th vector among the N vectors based on Λ2 raised to the power of q-1. Since Λ2 is a diagonal matrix, the computational cost of Λ2 raised to the power of q-1 is relatively low, thus reducing the computational cost of the second device.

[0420] In other implementations, the first information may include: Ψ2 H The product of the first vector, Λ2, and Ψ2. Where Λ2, Ψ2, and Ψ2... H For details, please refer to the sections on Λ2, Ψ2, and Ψ2 above. H The explanation will not be repeated here. For example, when the first vector is x 1,1 The second matrix is ​​G t And G t =Ψ2*Λ2*Ψ2 H In this case, the first information may include: Ψ2 H *x 1,1 Λ2 and Ψ2.

[0421] In this implementation, the second device can accurately determine the second matrix based on Λ2 and Ψ2. Furthermore, in this implementation, the second device can accurately determine the second matrix based on Λ2, Ψ2, and Ψ2.H This involves parallel computation of all vectors except the first vector out of N vectors. For example, if the first vector is x... 1,1 The second matrix is ​​G t In this case, the third vector among the N vectors can be x. 1,1 *G t 2 =x 1,1 *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H =x 1,1 *Ψ2*Λ2 2 *Ψ2 H The 4th vector among these N vectors can be x. 1,1 *G t 3 =x 1,1 *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H *Ψ2*Λ2*Ψ2 H =x 1,1 *Ψ2*Λ2 3 *Ψ2 H In this way, the second device can compute all vectors except the first vector out of N vectors in parallel, thereby saving computation time and resources. Furthermore, in this implementation, the second device can compute the q-th vector out of N vectors based on Λ2 raised to the power of q-1. Since Λ2 is a diagonal matrix, the computational cost of Λ2 raised to the power of q-1 is relatively low, thus reducing the computational load on the second device. Additionally, in this implementation, the first device determines Ψ2... H *x 1,1 Thus, the second device can directly use Ψ2 H *x 1,1 The calculation results determine the vectors other than the first vector among N vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0422] Optionally, the first information in "the first information may also indicate the second matrix" can be replaced with the fourth information. The specific content of the fourth information can be found in the above description of the first information, and will not be repeated here. The fourth information can be sent from the first device to the second device. The fourth information and the first information in S302 can be carried in the same message or in different messages. The order in which the fourth information and the first information are sent is not limited.

[0423] Optionally, the first reference signal in "the precoding matrix of each of the N time units is obtained (or determined) based on the first reference signal" can be replaced with a second reference signal. The specific content of the second reference signal can be found in the above description of the first reference signal, and will not be repeated here. The second reference signal can be sent from the second device to the first device. The second reference signal and the first reference signal in S301 can be carried in the same message or in different messages. The transmission order of the second reference signal and the first reference signal is not limited.

[0424] This application provides another communication method. Figure 7 is a flowchart illustrating the communication method provided in this application. Figure 7 uses the first device and the second device as examples of the execution entities in this interaction to illustrate the method. Optionally, the method shown in Figure 7 can be applied to scenario 1 and / or scenario 2. The specific details of scenario 1 and scenario 2 can be found in the descriptions of scenario 1 and scenario 2 in the method shown in Figure 3, and will not be repeated here.

[0425] As shown in Figure 7, the method includes:

[0426] S701: The second device sends a first reference signal; correspondingly, the first device receives the first reference signal.

[0427] For details on S701, please refer to S301; further details will not be provided here.

[0428] S702: The first device sends the first information; correspondingly, the second device receives the first information.

[0429] In some examples, in scenario 1 above, the first information may be PMI, or the first information may be CSI including PMI.

[0430] In other examples, such as scenario 2 above, the first piece of information could be TPMI.

[0431] In S702, the first information may indicate a first vector and a second matrix. The first vector may belong to N vectors, where N is a positive integer. The second matrix may be used to indicate the recursive relationship (or association or correspondence) between different vectors among the N vectors; or, the second matrix may be used to determine the vectors among the N vectors other than the first vector; or, the second matrix and the first vector may be used to determine the N vectors.

[0432] The specific contents of the first vector and the second matrix can be found in the explanation of the first vector and the second matrix in the method shown in Figure 3, and will not be repeated here. The first information can indicate the specific contents of the first vector and the second matrix, and can be found in the explanation of "the first information can indicate the first vector and the second matrix" in the method shown in Figure 3, and will not be repeated here.

[0433] Using this method, the first device can send first information, which indicates one of N vectors (i.e., the first vector) and the recursive relationship between the different vectors among the N vectors. Thus, the second device can accurately determine the N vectors based on the first vector and the recursive relationship, thereby determining the precoding matrix for the N time units. In this method, the first device does not need to send every single one of the N vectors, thereby reducing the overhead of feeding back the precoding matrix.

[0434] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the number of rows for the coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. This method can transmit only the coefficients corresponding to the precoding matrix of one time unit, instead of transmitting the coefficients corresponding to the precoding matrix of each subsequent time unit, thus significantly reducing the overhead of the feedback precoding matrix.

[0435] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated first vector and / or second matrix without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0436] Among some possible approaches, the method shown in Figure 7 also includes:

[0437] S703: The second device sends a first signal; correspondingly, the first device receives the first signal.

[0438] In some examples, such as Scenario 1 above, the first signal may be a downlink signal.

[0439] In other examples, such as scenario 2 above, the first information may be an uplink signal.

[0440] The first signal is transmitted based on a first precoding matrix; or, the second device can transmit the first signal based on the first precoding matrix. The first precoding matrix can be determined based on the precoding matrices of some or all of the N time units; or, the second device can determine the first precoding matrix based on the precoding matrices of some or all of the N time units.

[0441] For details on S703, please refer to S303, except that M is replaced with N, sub-band is replaced with time unit, and k is replaced with q. Further details will not be repeated here.

[0442] Among some possible approaches, the method shown in Figure 7 also includes:

[0443] S704: The second device sends the first instruction information; correspondingly, the first device receives the first instruction information. The first instruction information can be used to indicate the method of feedback CSI.

[0444] For details on S704, please refer to S304; further details will not be provided here.

[0445] After receiving the first instruction information, the first device can feed back a precoding matrix according to the first instruction information. For details, please refer to the explanation of "after receiving the first instruction information, the first device can feed back a precoding matrix according to the first instruction information" in the method shown in Figure 3, which will not be repeated here.

[0446] Optionally, the method shown in Figure 7 also includes S705:

[0447] S705: The first device sends second information; correspondingly, the second device receives the second information. The second information may indicate whether the first device possesses a first capability.

[0448] For details on S705, please refer to S305; further details will not be provided here.

[0449] In some other possible embodiments, the method shown in Figure 7 may also include S706:

[0450] S706: The first device can acquire a correspondence between at least one condition and at least one mode (hereinafter referred to as the first correspondence). Each of the at least one mode is a mode for feedback CSI.

[0451] For details on S706, please refer to S306; further details will not be provided here.

[0452] After obtaining the first correspondence, the first device can feed back the precoding matrix according to the first correspondence. For details, please refer to the explanation of "after obtaining the first correspondence, the first device can feed back the precoding matrix according to the first correspondence" in the method shown in Figure 3, which will not be repeated here.

[0453] Among some possible approaches, the method shown in Figure 7 may also include S707:

[0454] S707: The first device sends first indication information; correspondingly, the second device receives the first indication information. The first indication information can be used to indicate the method of CSI feedback.

[0455] For details on S707, please refer to S307; further details will not be provided here.

[0456] Optionally, if the first indication information indicates that the CSI feedback method is a new method, the first device may send the first information; correspondingly, the second device may receive the second information. In other words, if the first indication information indicates that the CSI feedback method is a new method, the first device may execute S702. In this manner, the first device may indicate to the second device that the CSI feedback method is a new method. Thus, after sending the first information to the second device, the second device may process the first information according to the new method; for example, it may determine M vectors based on the first information. Furthermore, in this manner, the first device may indicate the CSI feedback method to the second device, allowing the first device to flexibly manage the CSI feedback method.

[0457] Optionally, after receiving the first instruction information, the second device may send a signal according to the first instruction information. For details, please refer to the explanation of "after receiving the first instruction information, the second device may send a signal according to the first instruction information" in the method shown in Figure 3, which will not be repeated here.

[0458] Optionally, the method shown in Figure 7 may also include S708:

[0459] S708: The second device can send third information; correspondingly, the first device can receive the third information. The third information can indicate whether the second device has the first capability.

[0460] For details on S708, please refer to S308; further details will not be provided here.

[0461] The following examples, with reference to Figures 8 and 9, illustrate possible examples of the methods shown in Figures 3 and 7. The method shown in Figure 8 is illustrated using the example of the first device as the terminal and the second device as the access network equipment; the method shown in Figure 8 can be used in scenario 1 above. The method shown in Figure 9 is illustrated using the example of the first device as the access network equipment and the second device as the terminal; the method shown in Figure 9 can be used in scenario 2 above.

[0462] As shown in Figure 8, the method includes:

[0463] S801: The terminal sends second information to the access network device, which can indicate whether the terminal has the first capability.

[0464] For details on S801, please refer to S305 or S705, and will not be repeated here.

[0465] S802: The access network device sends a first indication information to the terminal. The first indication information can be used to indicate the method of feedback CSI.

[0466] For details on S802, please refer to S304 or S704, and will not be repeated here.

[0467] Steps S801 to S802 are optional. The order of S801 and S802 is not limited.

[0468] S803: Access network equipment sends CSI-RS to the terminal.

[0469] For details on S803, please refer to S301 or S701, and will not be repeated here.

[0470] S804: The terminal sends the first information to the access network device.

[0471] Optionally, the first information may be PMI, or the first information may be CSI including PMI.

[0472] S805: The access network device sends the first signal to the terminal.

[0473] In some possible approaches, the first information may indicate a first vector and a first matrix. The specific details of S804 to S805 can be found in S302 to S303, and will not be repeated here. Optionally, in this approach, the first information may also indicate a second matrix. The specific details can be found in the explanation of "the first information may also indicate a second matrix" in the method shown in Figure 3, and will not be repeated here.

[0474] In some other possible ways, the first information may indicate the first vector and the second matrix. For details of S804 to S805, please refer to S702 to S703, which will not be repeated here.

[0475] In some implementations, in S804, the first information may also indicate the first basis vector. In some examples, when the k-th vector is a vector in mode a1 of S302, the first information may indicate the first basis vector corresponding to each of the first to J-th flows. In other examples, when the k-th vector is a vector in mode a2 of S302, the first information may indicate the first basis vector corresponding to the J-th flow.

[0476] Optionally, in S805, the first signal can be a downlink signal, for example, the first signal can be PDSCH.

[0477] Optionally, S805 is an optional step.

[0478] The method shown in Figure 8 can achieve the same effect as the methods shown in Figure 3 or Figure 7, and will not be elaborated further. Furthermore, in the method shown in Figure 8, the information in the feedback precoding matrix can be PMI. Since PMI can be included in CSI, this method can reduce the overhead of feedback CSI.

[0479] As shown in Figure 9, the method includes:

[0480] S901: The terminal sends third information to the access network device, which can indicate whether the terminal has the first capability.

[0481] For details on S901, please refer to S308 or S708, and will not be repeated here.

[0482] S902: The access network device sends a first indication information to the terminal. The first indication information can be used to indicate the method of feedback CSI.

[0483] For details on S902, please refer to S307 or S707, and will not be repeated here.

[0484] Steps S901 to S902 are optional. The order of S901 and S902 is not limited.

[0485] S903: The terminal sends SRS to the access network equipment.

[0486] For details on S903, please refer to S301 or S701; further details will not be provided here.

[0487] S904: The access network device sends the first information to the terminal.

[0488] Optionally, the first information can be TPMI.

[0489] S905: The terminal sends the first signal to the access network equipment.

[0490] In some possible approaches, the first information may indicate a first vector and a first matrix. The specific details of S904 to S905 can be found in S302 to S303, and will not be repeated here. Optionally, in this approach, the first information may also indicate a second matrix. The specific details can be found in the explanation of "the first information may also indicate a second matrix" in the method shown in Figure 3, and will not be repeated here.

[0491] In some other possible ways, the first information may indicate the first vector and the second matrix. For details of S904 to S905, please refer to S702 to S703, which will not be repeated here.

[0492] In some implementations, in S904, the first information may also indicate the first basis vector. In some examples, when the k-th vector is a vector in mode a1 of S302, the first information may indicate the first basis vector corresponding to each of the first to J-th flows. In other examples, when the k-th vector is a vector in mode a2 of S302, the first information may indicate the first basis vector corresponding to the J-th flow.

[0493] Optionally, in S905, the first signal can be an uplink signal, for example, the first signal can be PUSCH.

[0494] Optionally, S905 is an optional step.

[0495] The method shown in Figure 9 can achieve the same effect as the methods shown in Figure 3 or Figure 7, and will not be elaborated further. Additionally, in the method shown in Figure 9, the information in the feedback precoding matrix can be TPMI, thereby reducing the overhead of the feedback TPMI.

[0496] Based on the same technical concept as the above-described method embodiments, this application provides a corresponding communication device that can be used to perform the functions of the relevant steps in the above-described method embodiments. This function can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. The communication device can be a terminal or access network device, or it can be a device that can be applied to a terminal or access network device (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or it can be a logical node, logical module, or software that can implement all or part of the functions of the terminal or access network device.

[0497] In one possible implementation, the communication device provided in this application embodiment has the structure shown in FIG10, including a processing unit 1002. Optionally, the communication device further includes an interface unit 1001. The functions of each unit in the communication device 1000 are described below.

[0498] Interface unit 1001 is used for inputting and / or outputting information. Input information can be replaced by received information, and output information can be replaced by transmitted information. When outputting information, interface unit 1001 can output information to other devices outside of communication device 1000, or to other units within communication device 1000. In some embodiments, interface unit 1001 can be implemented using at least one of a physical interface, a communication module, a communication interface, and an input / output interface. In other embodiments, interface unit 1001 can be implemented using an interface circuit, such as a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, a low-noise amplifier (LNA), etc. Interface unit 1001 is used to perform the receiving and transmitting operations in the above method embodiments.

[0499] In this application, the interface unit 1001 may also have other names, such as a transceiver unit or a communication unit. Optionally, the interface unit 1001 may include a receiving unit and a sending unit, used for inputting information and outputting information, respectively. The receiving unit is used to perform the receiving operation in the above method embodiments. The sending unit is used to perform the sending operation in the above method embodiments.

[0500] The processing unit 1002 can be used to support the communication device 1000 in performing the processing actions in the above method embodiments. The processing unit 1002 can be implemented by one or more processors. For example, the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microprocessors (MCUs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor. The processing unit 1002 is used to perform processing-related operations in the above method embodiments, for example, to instruct operations other than receiving and sending operations in the above method embodiments.

[0501] In one embodiment, the communication device 1000 is applied to the first device in the embodiment of this application shown in FIG3. The specific functions of the processing unit 1002 in this embodiment will be described below.

[0502] Processing unit 1002 is configured to: receive a first reference signal through interface unit 1001; and send first information through interface unit 1001; wherein the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors in the M vectors, the M vectors correspond to M subbands, each vector in the M vectors is a coefficient corresponding to the precoding matrix of a subband in the M subbands, and the precoding matrix of each subband in the M subbands is obtained based on the first reference signal.

[0503] In some possible ways, the processing unit 1002 is also used to: send or receive first indication information through the interface unit 1001, the first indication information being used to indicate the method of feeding back channel status information; and when the first indication information indicates that the method of feeding back channel status information is a new method, send first information through the interface unit 1001.

[0504] In some other possible ways, the processing unit 1002 is also configured to: obtain the correspondence between at least one condition and at least one mode, each of the at least one mode being a mode for feeding back channel state information; and send first information through the interface unit 1001 when a first condition in at least one condition is satisfied and the first condition corresponds to a new mode in at least one mode.

[0505] Optionally, the processing unit 1002 is further configured to: send second information through the interface unit 1001, the second information indicating whether the first device has the ability to provide feedback on channel state information according to the DMD; or, receive third information through the interface unit 1001, the third information indicating whether the second device has the ability to provide feedback on channel state information according to the DMD.

[0506] In another embodiment, the communication device 1000 is applied to the second device in the embodiment of this application shown in FIG3. The specific functions of the processing unit 1002 in this embodiment will be described below.

[0507] Processing unit 1002 is configured to: send a first reference signal through interface unit 1001; receive first information through interface unit 1001; wherein the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors in the M vectors, the M vectors correspond to M subbands, each vector in the M vectors is the coefficient corresponding to the precoding matrix of a subband in the M subbands, and the precoding matrix of each subband in the M subbands is obtained according to the first reference signal.

[0508] Optionally, the processing unit 1002 is further configured to: send a first signal through the interface unit 1001, the first signal being sent according to a first precoding matrix, the first precoding matrix being determined according to the precoding matrices of some or all of the M subbands, the precoding matrices of the M subbands being determined according to M vectors, the first vector among the M vectors being determined according to first information, and the vectors among the M vectors other than the first vector being determined according to the first vector and the first matrix.

[0509] In some possible configurations, the processing unit 1002 is further configured to: receive or send first indication information through the interface unit 1001, the first indication information being used to indicate the manner of feedback channel status information; and, if the first indication information indicates that the manner of feedback channel status information is a new manner, receive first information through the interface unit 1001.

[0510] Optionally, the processing unit 1002 is further configured to: receive second information through the interface unit 1001, the second information indicating whether the first device has the ability to provide feedback on channel state information according to the DMD; or, send third information through the interface unit 1001, the third information indicating whether the second device has the ability to provide feedback on channel state information according to the DMD.

[0511] In another embodiment, the communication device 1000 is applied to the first device in the embodiment of this application shown in FIG7. The specific functions of the processing unit 1002 in this embodiment will be described below.

[0512] Processing unit 1002 is configured to: receive a first reference signal through interface unit 1001; and send first information through interface unit 1001; wherein the first information indicates a first vector and a second matrix. The first vector belongs to N vectors, where N is a positive integer. The second matrix is ​​used to indicate the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0513] In some possible ways, the processing unit 1002 is also used to: send or receive first indication information through the interface unit 1001, the first indication information being used to indicate the method of feeding back channel status information; and when the first indication information indicates that the method of feeding back channel status information is a new method, send first information through the interface unit 1001.

[0514] In some other possible ways, the processing unit 1002 is also configured to: obtain the correspondence between at least one condition and at least one mode, each of the at least one mode being a mode for feeding back channel state information; and send first information through the interface unit 1001 when a first condition in at least one condition is satisfied and the first condition corresponds to a new mode in at least one mode.

[0515] Optionally, the processing unit 1002 is further configured to: send second information through the interface unit 1001, the second information indicating whether the first device has the ability to provide feedback on channel state information according to the DMD; or, receive third information through the interface unit 1001, the third information indicating whether the second device has the ability to provide feedback on channel state information according to the DMD.

[0516] In another embodiment, the communication device 1000 is applied to the second device in the embodiment of this application shown in FIG7. The specific functions of the processing unit 1002 in this embodiment will be described below.

[0517] Processing unit 1002 is configured to: send a first reference signal through interface unit 1001; and receive first information through interface unit 1001; wherein the first information indicates a first vector and a second matrix. The first vector belongs to N vectors, where N is a positive integer. The second matrix is ​​used to indicate the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0518] Optionally, the processing unit 1002 is further configured to: send a first signal through the interface unit 1001, the first signal being sent according to a first precoding matrix, the first precoding matrix being determined according to the precoding matrices of some or all of the N time units, the precoding matrices of the N time units being determined according to N vectors, the first vector among the N vectors being determined according to first information, and the vectors among the N vectors other than the first vector being determined according to the first vector and the second matrix.

[0519] In some possible configurations, the processing unit 1002 is further configured to: receive or send first indication information through the interface unit 1001, the first indication information being used to indicate the manner of feedback channel status information; and, if the first indication information indicates that the manner of feedback channel status information is a new manner, receive first information through the interface unit 1001.

[0520] Optionally, the processing unit 1002 is further configured to: receive second information through the interface unit 1001, the second information indicating whether the first device has the ability to provide feedback on channel state information according to the DMD; or, send third information through the interface unit 1001, the third information indicating whether the second device has the ability to provide feedback on channel state information according to the DMD.

[0521] In one possible design, when the communication device 1000 is a communication equipment or a communication module within a communication equipment, the functionality of the processing unit 1002 can be implemented by one or more processors. For example, the processor may include a modem chip, or a system-on-a-chip (SoC) or SIP chip containing a modem core. The functionality of the interface unit 1001 can be implemented by transceiver circuitry.

[0522] In one possible design, when the communication device 1000 is a circuit or chip responsible for communication functions in a communication device, such as a modem chip or a system-on-a-chip (SoC) or SIP chip containing a modem core, the function of the processing unit 1002 can be implemented by a circuit system in the aforementioned chip that includes one or more processors or processor cores. The function of the interface unit 1003 can be implemented by the interface circuit or data transceiver circuit on the aforementioned chip.

[0523] The communication device can be a terminal or an access network device.

[0524] A more detailed description of the processing unit 1002 and the interface unit 1001 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 3 to 9, and will not be repeated here.

[0525] It should be noted that the module division in the above embodiments of this application is illustrative and only represents a logical functional division. In actual implementation, there may be other division methods. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, exist as separate physical units, or have two or more units integrated into one unit. The integrated units can be implemented in hardware, as software functional units, or in a combination of hardware and software. Whether a function is executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0526] For example, the functional unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, such as one or more ASICs, one or more CPUs, one or more MCUs, one or more DSPs, or one or more FPGAs, or a combination of at least two of these integrated circuit forms.

[0527] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0528] In one possible implementation, the communication device provided in this application embodiment is shown in FIG11. The communication device 1100 includes a processor 1102. Optionally, the communication device 1100 further includes an interface circuit 1101 and a memory 1103. The interface circuit 1101, the processor 1102, and the memory 1103 are coupled to each other.

[0529] Optionally, the interface circuit 1101, processor 1102, and memory 1103 are coupled to each other via bus 1104. Bus 1104 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. Buses can be divided into address buses, data buses, control buses, etc. For ease of illustration, only one thick line is used in Figure 11, but this does not mean that there is only one bus or one type of bus.

[0530] Interface circuit 1101 is used for inputting and / or outputting information. Input information can be replaced with received information, and output information can be replaced with transmitted information. When outputting information, interface circuit 1101 can output information to other devices outside of communication device 1100, or to other units within communication device 1100. For example, interface circuit 1101 can be implemented through at least one of a physical interface, a communication module, a communication interface, an input / output interface, and a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, an LNA, etc. Interface circuit 1101 is used to perform the receiving and transmitting operations in the above method embodiments.

[0531] Interface circuit 1101 may be one of the following: a transceiver, a transceiver circuit, a communication circuit, an interface, a communication interface, or an input / output interface (e.g., a chip's input / output interface). Interface circuit 1101 may include an input interface circuit and an output interface circuit, used for inputting information and outputting information, respectively. The input interface circuit is used to perform the receiving operation in the above method embodiments. The output interface circuit is used to perform the transmitting operation in the above method embodiments.

[0532] The transceiver can be used for communication with other communication devices. For example, if communication device 1100 is a terminal, the transceiver can be used to communicate with an access network device or with another terminal. As another example, if communication device 1100 is an access network device, the transceiver can be used to communicate with a terminal or with another access network device.

[0533] Optionally, the transceiver may include a receiver and a transmitter. The receiver is used to perform the receiving operation in the above method embodiments. The transmitter is used to perform the sending operation in the above method embodiments.

[0534] Optionally, the transceiver can be integrated with the processor 1102 or exist independently and be coupled to the processor 1102 through the interface circuit of the communication device 1100. This application embodiment does not specifically limit this.

[0535] Processor 1102 can be used to support communication device 1100 in performing the processing actions in the above method embodiments. When communication device 1100 is used to implement the above method embodiments, processor 1102 can also be used to implement the functions of processing unit 1002. Processor 1102 can be a CPU, or other general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. General-purpose processors can be microprocessors or any conventional processor. Processor 1102 is used to perform processing-related operations in the above method embodiments, for example, to instruct operations other than receiving and sending operations in the above method embodiments.

[0536] In one embodiment, the communication device 1100 is applied to the first device in the embodiment of this application shown in FIG3. The specific functions of the processor 1102 in this embodiment will be described below.

[0537] Processor 1102 is configured to: receive a first reference signal through interface circuit 1101; and send first information through interface circuit 1101; wherein the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors in the M vectors, the M vectors correspond to M subbands, each vector in the M vectors is a coefficient corresponding to the precoding matrix of a subband in the M subbands, and the precoding matrix of each subband in the M subbands is obtained based on the first reference signal.

[0538] In another embodiment, the communication device 1100 is applied to the second device in the embodiment of this application shown in FIG3. The specific functions of the processor 1102 in this embodiment will be described below.

[0539] Processor 1102 is configured to: send a first reference signal through interface circuit 1101; receive first information through interface circuit 1101; wherein the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors in the M vectors, the M vectors correspond to M subbands, each vector in the M vectors is the coefficient corresponding to the precoding matrix of a subband in the M subbands, and the precoding matrix of each subband in the M subbands is obtained according to the first reference signal.

[0540] In another embodiment, the communication device 1100 is applied to the first device in the embodiment of this application shown in FIG7. The specific functions of the processor 1102 in this embodiment are described below.

[0541] Processor 1102 is configured to: receive a first reference signal through interface circuit 1101; and send first information through interface circuit 1101; wherein the first information indicates a first vector and a second matrix. The first vector belongs to N vectors, where N is a positive integer. The second matrix is ​​used to indicate the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0542] In another embodiment, the communication device 1100 is applied to the second device in the embodiment of this application shown in FIG7. The specific functions of the processor 1102 in this embodiment are described below.

[0543] Processor 1102 is configured to: transmit a first reference signal through interface circuit 1101; and receive first information through interface circuit 1101; wherein the first information indicates a first vector and a second matrix. The first vector belongs to N vectors, where N is a positive integer. The second matrix is ​​used to indicate the recursive relationship between different vectors among the N vectors. The N vectors correspond to N time units, and each of the N vectors is a coefficient corresponding to the precoding matrix of one of the N time units. The precoding matrix of each of the N time units is obtained based on the first reference signal.

[0544] The specific functions of processor 1102 can be found in the description of the communication methods provided in the above embodiments and examples of this application, as well as the specific functional description of communication device 1000 in the embodiment of this application shown in FIG10, which will not be repeated here.

[0545] Memory 1103 is used to store program instructions and / or data. Specifically, program instructions may include program code, which includes computer operation instructions. Memory 1103 may include RAM and may also include non-volatile memory, such as at least one disk storage device. Processor 1102 executes the program instructions stored in memory 1103 and uses the data stored in memory 1103 to implement the above-mentioned functions, thereby realizing the communication method provided in the embodiments of this application. Memory 1103 may be integrated with processor 1102 or may be a memory outside the communication device.

[0546] It is understood that the memory 1103 in Figure 11 of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be RAM, which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0547] Based on the above embodiments, this application also provides a computer program product including computer-executable instructions, which, when run, causes the methods provided in the above embodiments to be executed.

[0548] Based on the above embodiments, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a computer, causes the computer to perform the methods provided in the above embodiments.

[0549] The storage medium can be any available medium that a computer can access. For example, but not limited to, a computer-readable medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0550] Based on the above embodiments, this application also provides a chip for reading a computer program stored in a memory and implementing the method provided in the above embodiments.

[0551] Based on the above embodiments, this application provides a chip system including a processor for supporting a computer device in implementing the functions involved in the devices in the above embodiments. In one possible design, the chip system further includes a memory for storing necessary programs and data of the computer device. The chip system may be composed of chips or may include chips and other discrete components.

[0552] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0553] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0554] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0555] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0556] In this application, the terms "system" and "network" are used interchangeably. "At least one item" refers to one or more items, and "more than one item" refers to two or more items. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0557] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0558] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A communication method, characterized in that, Applied to a first device, the method includes: Receive the first reference signal; Send the first message; Wherein, the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, where M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors among the M vectors, the M vectors correspond to M subbands, each of the M vectors is a coefficient corresponding to the precoding matrix of a subband among the M subbands, and the precoding matrix of each subband among the M subbands is obtained based on the first reference signal.

2. The method as described in claim 1, characterized in that, Also includes: Sending or receiving first indication information, wherein the first indication information is used to indicate the manner of feeding back channel status information; Send the first message, including: If the first indication information indicates that the method of feeding back channel status information is a new method, then the first information is sent.

3. The method as described in claim 1 or 2, characterized in that, Also includes: Obtain the correspondence between at least one condition and at least one method, where each of the at least one method is a method for feeding back channel state information; Sending the first information includes: sending the first information when a first condition in the at least one condition is met and the first condition corresponds to a new method in the at least one method; or Sending the first message includes: sending the first message when the first condition is met.

4. The method as described in claim 3, characterized in that, The first condition includes at least one of the following: The number of transmitting antennas of the transmitting device is greater than or equal to a first threshold, and the transmitting device is a device that transmits signals according to the first information; The number of receiving antennas of the receiving device is greater than or equal to the second threshold, and the receiving device is a device that receives signals based on the first information; The number of transmit antenna ports of the transmitting device is greater than or equal to the third threshold; The number of receiving antenna ports of the receiving device is greater than or equal to the fourth threshold. or M is greater than or equal to the fifth threshold.

5. The method according to any one of claims 1 to 4, characterized in that, Also includes: Send a second message, the second message indicating whether the first device has the ability to provide feedback on channel state information based on the dynamic pattern decomposition DMD; or The third information is received, which indicates whether the second device has the ability to provide feedback on channel state information based on the DMD.

6. A communication method, characterized in that, Applied to a second device, comprising: Send the first reference signal; Receive the first message; Wherein, the first information indicates a first vector and a first matrix, the first vector belongs to M vectors, where M is a positive integer, the first matrix is ​​used to indicate the recursive relationship between different vectors among the M vectors, the M vectors correspond to M subbands, each of the M vectors is a coefficient corresponding to the precoding matrix of a subband among the M subbands, and the precoding matrix of each subband among the M subbands is obtained based on the first reference signal.

7. The method as described in claim 6, characterized in that, Also includes: A first signal is transmitted based on a first precoding matrix, which is determined based on the precoding matrices of some or all of the M subbands. The precoding matrices of the M subbands are determined based on the M vectors. The first vector among the M vectors is determined based on the first information, and the vectors among the M vectors other than the first vector are determined based on the first vector and the first matrix.

8. The method as described in claim 7, characterized in that, The k-th vector among the M vectors is x. k,1 k takes integers from 1 to M, and the first vector is x. 1,1 x k,1 and x 1,1 Satisfies the following formula: x k,1 =G f k-1 *x 1,1 , Among them, G f Let G be the first matrix. f k-1 For G f k-1.

9. The method according to any one of claims 6 to 8, characterized in that, Also includes: Receive or send first indication information, the first indication information being used to indicate the method of feedback channel status information; Receive the first message, including: If the first indication information indicates that the method of feeding back channel status information is a new method, then the first information is received.

10. The method according to any one of claims 6 to 9, characterized in that, Also includes: Receive second information, the second information indicating whether the first device has the ability to feed back channel state information based on dynamic pattern decomposition (DMD); or A third message is sent, indicating whether the second device has the ability to provide feedback on channel state information based on the DMD.

11. The method according to any one of claims 1 to 10, characterized in that, The first information indicates a first vector and a first matrix, including at least one of the following: The first information includes the first vector and the first matrix; or The first information includes information that corresponds to the first vector and / or the first matrix.

12. The method as described in claim 11, characterized in that, The first information includes information that corresponds to the first vector and / or the first matrix, including at least one of the following: The first information includes: the first vector, Λ1, and Ψ1; or The first information includes: Ψ1 H The product of the first vector, Λ1, and Ψ1; Where Λ1 is a diagonal matrix, Ψ1 is the matrix obtained by eigenvalue decomposition of the first matrix, and Ψ1 has the same number of rows and columns as the first matrix. The first matrix has the same number of rows and columns. Λ1, Ψ1, and the first matrix satisfy the following formula: G f =Ψ1*Λ1*Ψ1 H G f Let Ψ1 be the first matrix. H It is the conjugate transpose of Ψ1.

13. The method according to any one of claims 1 to 12, characterized in that, The first vector is the coefficient corresponding to the precoding matrix of the first sub-band, and the first sub-band is the sub-band with the smallest frequency among the M sub-bands; the first matrix is ​​the recursive relationship between the vectors corresponding to adjacent sub-bands among the M sub-bands.

14. The method according to any one of claims 1 to 13, characterized in that, The coefficients corresponding to the precoding matrix of the k-th sub-band among the M sub-bands are x. k Let k be any integer from 1 to M, and let the first matrix satisfy the following formula: G f =Y1*pinv(X1), Among them, G f For the first matrix, Y1 = [x 2,1 ,x 3,1 ,…,x M,1 ], X1 = [x 1,1 ,x 2,1 ,…,x M-1,1 ], pinv indicates the pseudo-inverse operation.

15. The method according to any one of claims 1 to 14, characterized in that, The first information also indicates a second matrix, the first vector also belongs to N vectors, where N is a positive integer, the second matrix is ​​used to indicate the recursive relationship between different vectors in the N vectors, the N vectors correspond to N time units, each of the N vectors is a coefficient corresponding to the precoding matrix of a time unit in the N time units, and the precoding matrix of each time unit in the N time units is obtained based on the first reference signal.

16. The method according to any one of claims 1 to 15, characterized in that, The first device is a terminal or a device within a terminal, the second device is an access network device or a device within an access network device, and the first reference signal is a Channel State Information Reference Signal (CSI-RS); or The first device is an access network device or a device within an access network device, the second device is a terminal or a device within a terminal, and the first reference signal is a detection reference signal (SRS).

17. A communication device, characterized in that, Includes a unit for performing the method as described in any one of claims 1-16.

18. A communication device, characterized in that, Includes a processor for executing computer programs or instructions that cause the apparatus to perform the method as described in any one of claims 1-16.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions, which, when executed, implement the method as described in any one of claims 1-16.

20. A computer program product, characterized in that, The computer program product includes: computer program code, which, when the computer program code is run, implements the method as described in any one of claims 1-16.

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