Communication method for feeding back precoding matrix, and apparatus

Abstract

A communication method for feeding back a precoding matrix, and an apparatus. The method comprises: a first apparatus receives a first reference signal, and sends at least one piece of information. First information is any one of the at least one piece of information. The first information indicates M1 vectors corresponding to a first stream, and M1 matrices. The M1 vectors belong to M vectors corresponding to the first stream. Each of the M vectors is a coefficient corresponding to one of M sub-bands in a first coefficient matrix, and the first coefficient matrix is a coefficient matrix corresponding to a precoding matrix of the first stream. The precoding matrix of the first stream is determined on the basis of precoding matrices of the M sub-bands, and the precoding matrices of the M sub-bands are obtained on the basis of the first reference signal. The M1 vectors correspond to the M1 matrices, a first vector is any one of the M1 vectors, the first vector corresponds to a first matrix among the M1 matrices, and the first matrix indicates a recursive relationship between at least one of the M vectors and the first vector.

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. 202410940628.3, 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 and transmitting at least one piece of information. The at least one piece of information corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and the first piece of information corresponds to a first stream in the at least one stream. The first information indicates M1 vectors and M1 matrices corresponding to the first stream, where M1 is a positive integer. The M1 vectors belong to M vectors corresponding to the first stream, where M is a positive integer. The M vectors correspond to M subbands, and each of the M vectors is a coefficient in a first coefficient matrix corresponding to one of the M subbands. The first coefficient matrix is ​​a coefficient matrix corresponding to the precoding matrix of the first stream. The precoding matrix of the first stream is determined based on the precoding matrices of the M subbands, which are obtained based on the first reference signal. The M1 vectors correspond to the M1 matrices, and the first vector is any one of the M1 vectors. The first vector corresponds to a first matrix in the M1 matrices, and the first matrix indicates the recursive relationship between at least one of the M vectors and the first vector.

[0011] Using this method, a first device can send at least one piece of information, which corresponds to at least one stream. The first piece of information can be any one of the at least one pieces of information, and it corresponds to a first stream within the at least one stream. The first piece of information can indicate a subset of M vectors (i.e., M1 vectors), and a recursive relationship between each of the M1 vectors and the other vectors in the M vectors. Thus, a second device can accurately determine the M vectors based on the M1 vectors and the recursive relationship, thereby determining the precoding matrix 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.

[0012] 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 matrices of M1 sub-bands, 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 matrices of M1 sub-bands, 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 M1 vectors and / or M1 matrices 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 receiving at least one piece of information. The at least one piece of information corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and the first piece of information corresponds to a first stream in the at least one stream. The first information indicates M1 vectors and M1 matrices corresponding to the first stream, where M1 is a positive integer. The M1 vectors belong to M vectors corresponding to the first stream, where M is a positive integer. The M vectors correspond to M subbands, and each of the M vectors is a coefficient in a first coefficient matrix corresponding to one of the M subbands. The first coefficient matrix is ​​a coefficient matrix corresponding to the precoding matrix of the first stream. The precoding matrix of the first stream is determined based on the precoding matrices of the M subbands, which are obtained based on the first reference signal. The M1 vectors correspond to the M1 matrices, and the first vector is any one of the M1 vectors. The first vector corresponds to a first matrix in the M1 matrices, and the first matrix indicates the recursive relationship between at least one of the M vectors and the first vector.

[0018] Using this method, the second device can receive at least one piece of information, which corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and it corresponds to a first stream in the at least one stream. The first piece of information may indicate a subset of M vectors (i.e., M1 vectors), and a recursive relationship between each of the M1 vectors and the other vectors in the M vectors. Thus, the second device can accurately determine the M vectors based on the M1 vectors and the recursive relationship, thereby determining the precoding matrix 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 matrices of M1 sub-bands, 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 matrices of M1 sub-bands, 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 M1 vectors and / or M1 matrices 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 and sending at least one piece of information. The at least one piece of information corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and corresponds to a first stream in the at least one stream. The first information indicates N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to N vectors corresponding to the first stream, where N is a positive integer. The N vectors correspond to N time units, and each of the N vectors is a coefficient in one of the N coefficient matrices. Each of the N coefficient matrices is a coefficient matrix corresponding to the precoding matrix of one time unit in the N time units of the first stream. The precoding matrix of each time unit in the N time units of the first stream is obtained based on the first reference signal. The N1 vectors correspond to the N1 matrices, and a second vector is any one of the N1 vectors. The second vector corresponds to a third matrix in the N1 matrices, and the third matrix indicates the recursive relationship between one or more of the N vectors and the second vector.

[0025] Using this method, a first device can send at least one piece of information, which corresponds to at least one stream. The first piece of information can be any one of the at least one pieces of information, and it corresponds to a first stream within the at least one stream. The first piece of information can indicate a subset of N vectors (i.e., N1 vectors), and a recursive relationship between each of the N1 vectors and the other vectors in the N vectors. Thus, a second device can accurately determine the N vectors based on the N1 vectors 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.

[0026] 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 of coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. In this method, the first device can transmit only the coefficients corresponding to the precoding matrix of a portion of the N time units (i.e., N1 time units), without transmitting the coefficients corresponding to the precoding matrix of each time unit, thereby significantly reducing the overhead of the feedback precoding matrix.

[0027] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated N1 vectors and / or N1 matrices without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0028] Fourthly, embodiments of this application provide a communication method that can be applied to a second device.

[0029] 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.

[0030] 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.

[0031] The method may include: a second device transmitting a first reference signal and receiving at least one piece of information. The at least one piece of information corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and corresponds to a first stream in the at least one stream. The first information indicates N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to N vectors corresponding to the first stream, where N is a positive integer. The N vectors correspond to N time units, and each of the N vectors is a coefficient in one of the N coefficient matrices. Each of the N coefficient matrices is a coefficient matrix corresponding to the precoding matrix of one time unit in the N time units of the first stream. The precoding matrix of each time unit in the N time units of the first stream is obtained based on the first reference signal. The N1 vectors correspond to the N1 matrices, and a second vector is any one of the N1 vectors. The second vector corresponds to a third matrix in the N1 matrices, and the third matrix indicates the recursive relationship between one or more of the N vectors and the second vector.

[0032] Using this method, the second device can receive at least one piece of information, which corresponds to at least one stream. The first piece of information is any one of the at least one pieces of information, and it corresponds to a first stream in the at least one stream. The first piece of information may indicate a subset of N vectors (i.e., N1 vectors), and a recursive relationship between each of the N1 vectors and the other vectors in the N vectors. Thus, the second device can accurately determine the N vectors based on the N1 vectors 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.

[0033] 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 of coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. In this method, the first device can transmit only the coefficients corresponding to the precoding matrix of a portion of the N time units (i.e., N1 time units), without transmitting the coefficients corresponding to the precoding matrix of each time unit, thereby significantly reducing the overhead of the feedback precoding matrix.

[0034] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated N1 vectors and / or N1 matrices without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0035] Based on the first or second aspect, in one possible design, the method further includes: the second device being able to transmit second information; correspondingly, the first device being able to receive the second information. The second information may indicate at least one of the following:

[0036] 1. M1 sub-bands out of M sub-bands. Each of the M1 vectors is a coefficient in the first coefficient matrix corresponding to one of the M1 sub-bands. Thus, the second device can indicate the M1 sub-bands to the first device, allowing the first device to determine the M1 vectors indicated by the first information, thereby enabling flexible management of the M1 vectors indicated by the first information.

[0037] 2. The transmission period of the first information. In this way, the first device can accurately determine the transmission period of the first information based on the second information. Furthermore, in this design, the second device can flexibly manage the transmission period of the first information.

[0038] Optionally, this design can be used for downlink MIMO.

[0039] Based on the first or second aspect, in one possible design, the method further includes: the first device being capable of transmitting second information; correspondingly, the second device being capable of receiving the second information. The second information may indicate at least one of the following:

[0040] 1. M1 sub-bands out of M sub-bands. Each of the M1 vectors is a coefficient in the first coefficient matrix corresponding to one of the M1 sub-bands. Thus, the first device can indicate the M1 sub-bands to the second device, enabling the second device to accurately determine which sub-bands correspond to the M1 vectors indicated by the first information.

[0041] 2. The transmission period of the first information. In this way, the first device can indicate the transmission period of the first information to the second device, so that the second device can receive the first information according to the transmission period.

[0042] Optionally, this design can be used for uplink MIMO.

[0043] Based on the first or second aspect, in one possible design, the second information indicating the M1 sub-bands may include at least one of the following:

[0044] 1. The second information includes the sequence numbers of M1 sub-bands. In this way, the second information can directly indicate the M1 sub-bands, so the receiving device of the second information does not need to calculate to determine the M1 sub-bands, thereby reducing the computational complexity of the receiving device of the second information.

[0045] 2. When the sequence number difference between adjacent sub-bands in the M1 sub-bands is the same, the second information includes the sequence number of the reference sub-band, the sequence number difference, and M1. In this way, the second information can indicate the M1 sub-bands through the sequence number of the reference sub-band, the first sequence number difference, and M1, without excluding the sequence number of each sub-band in the M1 sub-bands, thereby reducing the overhead of indicating the M1 sub-bands.

[0046] 3. The second information includes a first index, which corresponds to M1 sub-bands. In this way, the second information can indicate the M1 sub-bands through the first index, without excluding the sequence number of each sub-band in the M1 sub-bands, thereby reducing the overhead of indicating the M1 sub-bands.

[0047] Based on the first or second aspect, in one possible design, the value of M1 is negatively correlated with the stability of the first-order flow. Thus, for flows with high stability, the first device can report fewer coefficients corresponding to the precoding matrices of sub-bands, thereby reducing the overhead of the feedback precoding matrix; for flows with low stability, the first device can report more coefficients corresponding to the precoding matrices of sub-bands, thereby improving the accuracy of the feedback precoding matrix.

[0048] Based on any one of the first to fourth aspects, in one possible design, the method further includes: a second device sending first indication information; correspondingly, a first device receiving the first indication information. The first indication information is used to indicate the manner of feedback channel state information (CSI). If the first indication information indicates that the CSI feedback manner is a new manner, the first device may send at least one piece of information; correspondingly, the second device may receive at least one piece of information. Optionally, this design can be used for downlink MIMO. With this design, the first device can send at least one piece of information to the second device according to the indication of the second device. Furthermore, in this design, the second device can indicate the CSI feedback manner to the first device, thus allowing the second device to flexibly manage the CSI feedback manner of the first device.

[0049] Based on any one of the first to fourth aspects, in one possible design, the method further includes: a first device sending first indication information; correspondingly, a second device receiving the first indication information, the first indication information indicating a method for feedback CSI. When the first indication information indicates that the method for feedback CSI is a new method, the first device sends at least one piece of information. With this design, the first device can indicate to the second device that the method for feedback CSI is a new method. Thus, after sending at least one piece of information to the second device, the second device can process the at least one piece of information according to the new method; for example, it can determine M vectors and / or N vectors based on the first information in the at least one piece of information. Furthermore, in this design, the first device can indicate the method for feedback CSI to the second device, thus allowing the first device to flexibly manage the method for feedback CSI.

[0050] Based on the first or second aspect, in one possible design, the first information further indicates N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to the N vectors corresponding to the first stream, where N is a positive integer. The N vectors correspond to N time units. Each of the N vectors is a coefficient in one of the N coefficient matrices, and each of the N coefficient matrices is the coefficient matrix corresponding to the precoding matrix of one time unit in the N time units of the first stream. The precoding matrix of each time unit in the N time units of the first stream is obtained based on the first reference signal. The N1 vectors correspond to the N1 matrices, and the second vector is any one of the N1 vectors. The second vector corresponds to a third matrix in the N1 matrices, which indicates the recursive relationship between one or more of the N vectors and the second vector.

[0051] In this design, the first information can indicate a subset of N vectors (i.e., N1 vectors), and the recursive relationship between each of the N1 vectors and the other vectors in the N vectors. Thus, the second device can accurately determine the N vectors based on the N1 vectors and the recursive relationship, thereby determining the precoding matrix for the N time units. In this design, 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.

[0052] When applied to massive MIMO technology, this design significantly reduces 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. In this design, the first device can transmit only the coefficients corresponding to the precoding matrix of a portion of the N time units (i.e., N1 time units), without transmitting the coefficients corresponding to the precoding matrix of each time unit, thereby significantly reducing the overhead of the feedback precoding matrix.

[0053] Alternatively, since the first device may not send each of the N vectors, this design can improve the accuracy of the indicated N1 vectors and / or N1 matrices without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0054] Based on any one of the first to fourth aspects, in one possible design, the method further includes: the second device being capable of transmitting third information; correspondingly, the first device being capable of receiving the third information. The third information may indicate at least one of the following:

[0055] 1. N1 time units out of N time units. Each of the N1 vectors includes coefficients from one of the N1 coefficient matrices. Each of the N1 coefficient matrices is the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units. Thus, the second device can indicate N1 time units to the first device, allowing the first device to determine the N1 vectors indicated by the first information, thereby enabling flexible management of the N1 vectors indicated by the first information.

[0056] 2. The time range to which the N time units belong. In this way, the second device can indicate the time range to which the N time units belong to the first device, so that the first device can determine the N vectors accordingly, and thus flexibly manage the N vectors.

[0057] 3. The transmission period of the first information. In this way, the first device can accurately determine the transmission period of the first information based on the third information. Furthermore, in this design, the second device can flexibly manage the transmission period of the first information.

[0058] Optionally, this design can be used for downlink MIMO.

[0059] Based on any one of the first to fourth aspects, in one possible design, the method further includes: the first device being capable of transmitting third information; correspondingly, the second device being capable of receiving the third information. The third information may indicate at least one of the following:

[0060] 1. N1 time units out of N time units. Each of the N1 vectors includes coefficients from one of the N1 coefficient matrices. Each of the N1 coefficient matrices is the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units. Thus, the first device can indicate N1 time units to the second device, enabling the second device to accurately determine which time units correspond to the N1 vectors indicated by the first information.

[0061] 2. The time range to which the N time units belong. In this way, the first device can accurately indicate the time range to which the N time units belong to the second device.

[0062] 3. The transmission period of the first information. In this way, the first device can indicate the transmission period of the first information to the second device, so that the second device can receive the first information according to the transmission period.

[0063] Optionally, this design can be used for uplink MIMO.

[0064] Based on any one of the first to fourth aspects, in one possible design, the way in which the third information indicates N1 time units may include at least one of the following:

[0065] 1. The third information includes the sequence numbers of N1 time units. In this way, the third information can directly indicate the N1 time units, and the receiving device of the third device does not need to determine the N1 time units through calculation, thereby reducing the computational complexity of the first device.

[0066] 2. When the sequence number difference between adjacent time units in the N1 time units is the same, the third information includes the sequence number of the reference time unit in the N1 time units, the sequence number difference between adjacent time units in the N1 time units, and N1. In this way, the third information can indicate the N1 time units through the sequence number of the reference time unit, the second sequence number difference, and N1, without excluding the sequence number of each time unit in the N1 time units, thereby reducing the overhead of indicating the N1 time units.

[0067] 3. The third information includes the second index, which corresponds to N1 time units. Thus, the third information can indicate the N1 time units through the second index, eliminating the need for the sequence number of each of the N1 time units, thereby reducing the overhead of indicating the N1 time units.

[0068] Based on any one of the first to fourth aspects, in one possible design, the length of the time range is positively correlated with the stability of the first-order flow. Thus, for a highly stable flow, the first device can predict and report the coefficients corresponding to the precoding matrix of the subband over a longer time range; for a less stable flow, the first device can report the coefficients corresponding to the precoding matrix of the subband over a shorter time range.

[0069] Based on any one of the first to fourth aspects, in one possible design, the value of N1 is negatively correlated with the stability of the first-order flow. Thus, for flows with high stability, the first device can report coefficients corresponding to the precoding matrix of fewer time units, thereby reducing the overhead of the feedback precoding matrix; for flows with low stability, the first device can report coefficients corresponding to the precoding matrix of more time units, thereby improving the accuracy of the feedback precoding matrix.

[0070] Based on any one of the first to fourth aspects, in one possible design, the value of the transmission period is positively correlated with the stability of the first-order flow. Thus, for flows with high stability, the first device can use a longer period for the feedback precoding matrix, thereby reducing the overhead of the feedback precoding matrix; for flows with low stability, the first device can use a shorter period for the feedback precoding matrix, thereby improving the accuracy of the feedback precoding matrix.

[0071] Based on any one of the first to fourth aspects, in one possible design, the first device can transmit first capability information; correspondingly, the second device can receive the first capability information. The first capability 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 first capability information.

[0072] Based on any one of the first to fourth aspects, in one possible design, the second device can transmit second capability information; correspondingly, the first device can receive the second capability information. The second capability 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 second capability information.

[0073] Based on either the first or second aspect, in one possible design, the first vector is the i-th vector among M1 vectors, where i is an integer from 1 to M1. The set of at least one vector and the first vector is M3 vectors, where M3 is a positive integer. The b1-th vector among the M3 vectors is x.a1+b1-1,1 Let a1 be a positive integer, and b1 be any integer from 1 to M3. The first matrix satisfies the following formula: G f,i =Y f,i *pinv(X f,i ),

[0074] Among them, G f,i Let Y be the first matrix. f,i =[x a1+1,1 ,x a1+2,1 ,…,x a1+M3-1,1 ], X f,i =[x a1,1 ,x a1+1,1 ,…,x a1+M3-2,1 ], pinv indicates the pseudo-inverse operation.

[0075] With this design, the first device can accurately determine the first matrix.

[0076] Based on any one of the first to fourth aspects, in one possible design, the second vector is the l-th vector among N1 vectors, where l is an integer from 1 to N1. The set of one or more vectors and the second vector is N3 vectors, where N3 is a positive integer. The b2-th vector among the N3 vectors is x. 1,a2+b2-1 Let a2 be a positive integer, b2 be any integer from 1 to N3, and the third matrix satisfy the following formula: G t,l =Y t,l *pinv(X t,l ),

[0077] Among them, G t,i For the third matrix, Y t,l =[x 1,a2+1 ,x 1,a2+2 ,…,x 1,a2+N3-1 ], X t,l =[x 1,a2 ,x 1,a2+1 ,…,x 1,a2+N3-2 ], pinv indicates the pseudo-inverse operation.

[0078] With this design, the first device can accurately determine the third matrix.

[0079] Based on the first or second aspect, in one possible design, the method further includes: a second device transmitting a first signal; correspondingly, a first device receiving 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, and the M vectors are determined based on M1 vectors and M1 matrices. Through this design, the second device can accurately determine the M vectors based on the M1 vectors and M1 matrices, thereby determining the precoding matrix used for transmitting the signal.

[0080] Based on the first or second aspect, in one possible design, the first vector can be represented as x. k1,1 k1 is a positive integer. Any vector in at least one vector can be represented as x. k2,1 k2 is a positive integer. When k2 is greater than k1, x k2,1 =G f,i k2-k1 *x k1,1 ; and / or, when k2 is less than k1, x k2,1 =inv(G f,i ) |k2-k1| *x k1,1 Among them, G f,i Let G be the first matrix. f,i k2-k1 For G f,i k2-k1, inv(G f,i ) is G f,i The inverse matrix, inv(G) f,i ) |k2-k1| for inv(G f,i The |k2-k1| power of ) is used, where || represents the absolute value operation. Through this design, the second device can accurately determine M vectors.

[0081] Based on any one of the first to fourth aspects, in one possible design, the method further includes: a second device transmitting a first signal; correspondingly, a first device receiving 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, which are determined based on N1 vectors and N1 matrices. Through this design, the second device can accurately determine the N vectors based on the N1 vectors and N1 matrices, thereby determining the precoding matrix used for transmitting the signal.

[0082] Based on any one of the first to fourth aspects, in one possible design, the second vector can be represented as x. 1,q1q1 is a positive integer. Any one of these vectors can be represented as x. 1,q2 Let q2 be a positive integer. When q2 is greater than q1, x 1,q2 =G t,l q2-q1 *x 1,q1 ; and / or, when q2 is less than q1, x 1,q2 =inv(G t,l ) |q2-q1| *x 1,q1 Among them, G t,l G is the third matrix. t,l q2-q1 For G t,l q²-q¹, inv(G) t,l ) is G t,l The inverse matrix, inv(G) t,l ) |q2-q1| for inv(G t,l The expression is a power of |q²-q¹|, where || represents the absolute value operation, and l is an integer greater than or equal to 1 and less than or equal to N¹. Through this design, the second device can accurately determine N vectors.

[0083] 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).

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] In some possible designs, the first device is a terminal and the second device is an access network device.

[0091] In other possible designs, the first device is an access network device and the second device is a terminal.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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

[0096] Figure 1 is an architecture diagram of a communication system provided in an embodiment of this application;

[0097] Figure 2 is a schematic diagram of the relationship between the precoding matrices provided in the embodiments of this application;

[0098] Figure 3 is a flowchart of a communication method provided in an embodiment of this application;

[0099] Figures 4A to 4C are schematic diagrams of a method for determining M vectors provided in an embodiment of this application;

[0100] Figures 5A to 5C are schematic diagrams of a method for determining N vectors provided in an embodiment of this application;

[0101] Figure 6 is a schematic diagram of a method for determining M vectors corresponding to each of N time units according to an embodiment of this application;

[0102] Figures 7 to 9 are flowcharts of several other communication methods provided in the embodiments of this application;

[0103] Figure 10 is a structural diagram of a communication device provided in an embodiment of this application;

[0104] Figure 11 is a structural diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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).

[0115] 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.

[0116] 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.

[0117] 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).

[0118] 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.

[0119] 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.

[0120] The correspondence between network elements and their achievable protocol layer functions in the ORAN system can be found in Table 1 below.

[0121] Table 1

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 1. Reference signal (RS):

[0126] 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.

[0127] 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.

[0128] 2. Precoding matrix:

[0129] 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.

[0130] 3. Precoding Matrix Indicator (PMI):

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] Table 2

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] Optionally, PMI can be used for downlink MIMO.

[0144] 4. Transmitted precoding matrix indicator (TPMI):

[0145] 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.

[0146] 5. Antenna port:

[0147] 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.

[0148] 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).

[0149] 6. Flow:

[0150] 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.

[0151] 7. Flow stability:

[0152] The stability of a stream can be characterized by at least one of the following, or the stability of a stream is related to at least one of the following: the difference in signal quality of the stream in different subbands, the change in the direction of the beam corresponding to the stream, or the correlation of the precoding vectors corresponding to the stream in different subbands.

[0153] For example, the smaller the difference in signal quality across different subbands of a stream, the better the stability of the stream; and / or, the greater the difference in signal quality across different subbands of a stream, the worse the stability of the stream.

[0154] For example, the smaller the change in the direction of the beam corresponding to a flow, the better the stability of the flow; and / or, the greater the change in the direction of the beam corresponding to a flow, the worse the stability of the flow.

[0155] For example, the greater the correlation between the precoding vectors of a stream across different subbands, the better the stability of the stream; and / or, the smaller the correlation between the precoding vectors of a stream across different subbands, the worse the stability of the stream.

[0156] 8. DMD:

[0157] 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.

[0158] 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)

[0159] Where Y3=[y2,y3,…,y s X3 = [y1, y2, ..., y] s-1 ], pinv indicates the pseudo-inverse operation.

[0160] n is any integer from 1 to s-1, y n+1 =Gy n .

[0161] 9. 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.

[0162] 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).

[0163] 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.

[0164] 10. 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.

[0165] 11. 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.

[0166] 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.

[0167] 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.

[0168] 12. 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.

[0169] 13. In this application, the words "exemplarily," "for example," "for instance," and "example" are used to indicate examples, illustrations, or descriptions, 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.

[0170] 14. In this application, any two of the programs, instructions and code may be substituted for one another.

[0171] 15. 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.

[0172] 16. In this application, the recursive relationship may be replaced by at least one of the following: association relationship or correspondence relationship.

[0173] 17. 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 .

[0174] 18. 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.

[0175] 19. 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.

[0176] 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.

[0177] 20. In this application, "obtain" and "determine" are interchangeable.

[0178] 21. In this application, the asterisk (*) in the formula can represent matrix-matrix multiplication, matrix-vector multiplication, vector-matrix multiplication, or vector-vector multiplication.

[0179] 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.

[0180] 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.

[0181] Among some possible approaches, as shown in Figure 2, 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 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 P j (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., in the C. Access network equipment can, according to C j (1) W j (1) and W j (2) Determine P j (2) Therefore, it is possible to determine the relationship between P and P. j (2) Determine P k (1) .

[0182] 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.

[0183] 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.

[0184] Optionally, the method shown in Figure 3 can be used in scenario 1 and / or scenario 2.

[0185] 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.

[0186] Optionally, scenario 1 can be used for downlink MIMO.

[0187] 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.

[0188] Optionally, scenario 2 can be used for uplink MIMO.

[0189] As shown in Figure 3, the method includes:

[0190] S301: The second device sends a first reference signal; correspondingly, the first device receives the first reference signal.

[0191] In some examples, such as Scenario 1 above, the first reference signal may be CSI-RS.

[0192] In other examples, such as scenario 2 above, the first reference signal may be the SRS.

[0193] 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.

[0194] S302: The first device sends at least one piece of information; correspondingly, the second device receives at least one piece of information.

[0195] In some examples, in scenario 1 above, at least one piece of information may be PMI, or at least one piece of information may be CSI including PMI.

[0196] In other examples, in scenario 2 above, at least one piece of information may be TPMI.

[0197] At least one piece of information may correspond to at least one stream; for example, at least one piece of information may correspond one-to-one with at least one stream.

[0198] The first piece of information can be any one of the at least one pieces of information. The following explanation will use the first piece of information as an example to illustrate at least one piece of information.

[0199] The first information corresponds to a first stream in at least one stream. The first information indicates M1 vectors and M1 matrices corresponding to the first stream, where M1 is a positive integer. The M1 vectors belong to the M vectors corresponding to the first stream, where M is a positive integer. Optionally, M can be greater than or equal to 2, or in other words, M can be an integer greater than or equal to 2. The M1 vectors correspond to the M1 matrices, and the first vector is any one of the M1 vectors, corresponding to the first matrix among the M1 matrices. The first matrix is ​​used to indicate: the recursive relationship (or association or correspondence) between at least one of the M vectors and the first vector; or, the first matrix can be used to determine the at least one vector; or, the first matrix and the first vector can be used to determine the at least one vector.

[0200] To make it easier to understand, we will first explain the M vectors.

[0201] 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.

[0202] Each of the M vectors can be a coefficient in the first coefficient matrix corresponding to one of the M subbands, where the first coefficient matrix is ​​the coefficient matrix corresponding to the first-order precoding matrix; 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 first-order precoding matrix is ​​determined based on the precoding matrices of the M subbands, and the determination method can be referred to the explanation of Figure 2 above, which will not be repeated here. The precoding matrices of the M subbands are obtained based on the first reference signal; for example, the precoding matrix of each of the M subbands is obtained 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.

[0203] 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.

[0204] The k-th vector can be the coefficient in the first coefficient matrix corresponding to the precoding matrix of the k-th sub-band (hereinafter referred to as the k-th sub-band) among the M sub-bands. Optionally, k is positively correlated with the frequency of the k-th sub-band; that is, the larger k is, the larger the frequency of the k-th sub-band, and the smaller k is, the smaller the frequency of the k-th sub-band.

[0205] For example (hereinafter referred to as Example 1), the first stream is the j-th stream, and the first coefficient matrix is ​​the precoding matrix P of the j-th stream. j (2) The corresponding coefficient matrix. The k-th vector can be 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 2, 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. The first stream is the j-th stream in stream J. Here, J is the stream number, a positive integer; j is an integer greater than or equal to 1 and less than or equal to J.

[0206] To facilitate understanding, let's first discuss P. j (2) The corresponding coefficient matrix is ​​explained.

[0207] 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, C j (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) .

[0208] 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).

[0209] 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 2), 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.

[0210] It should be understood that 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.

[0211] The following explanation uses M vectors to illustrate M1 vectors and M1 matrices.

[0212] 1. M1 vectors:

[0213] As mentioned earlier, M1 vectors belong to M vectors. Optionally, M1 is less than M; or, the M1 vectors are a subset of the M vectors. The k-th vector among these M vectors can be represented as x. k,1 k can be referred to as the index of the vector and / or the index of the sub-band, and k takes integer values ​​from 1 to M. The indices of the M1 vectors can be uniformly distributed or non-uniformly distributed. For example, if M is 50 and M1 is 5, the M1 vectors may include: x 1,1 x 11,1 x21,1 x 31,1 , and x 41,1 For example, if M is 50 and M1 is 5, the M1 vectors can include: x 10,1 x 20,1 x 30,1 x 40,1 , and x 50,1 For example, if M is 45 and M1 is 5, then the M1 vectors can include: x 5,1 x 14,1 x 23,1 x 32,1 , and x 41,1 For example, if M is 50 and M1 is 5, the M1 vectors can include: x 1,1 x 12,1 x 20,1 x 31,1 , and x 40,1 .

[0214] It should be understood that the above examples are merely illustrative and are not intended to limit the scope of protection of this application. For example, M and M1 may take other values; and / or, the M1 vectors may be other vectors.

[0215] 2. M1 matrices:

[0216] As mentioned earlier, the first vector is any one of the M1 vectors, and the first vector corresponds to the first matrix among the M1 matrices. The first matrix is ​​used to indicate the recursive relationship between at least one of the M vectors and the first vector.

[0217] The following explanation uses the first matrix as an example to illustrate the M1 matrices.

[0218] For example, when the set of at least one vector and the first vector (hereinafter referred to as set #1) is the first to tenth vectors among the M vectors, the first vector in set #1 can be P. j (2) The first column of the corresponding coefficient matrix; the second vector in set #1 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 columns 1 to 10 of the corresponding coefficient matrix can indicate the recursive relationship between at least one vector and the first vector. In the case that set #1 consists of the 11th to 20th vectors among the M vectors, the first vector in set #1 can be P. j (2) The 11th column of the corresponding coefficient matrix; the second vector in set #1 can be P. j(2) The 12th column of the corresponding coefficient matrix, and so on. The first matrix indicates P. j (2) The recursive relationship between columns 11 to 20 of the corresponding coefficient matrix indicates the recursive relationship between at least one vector and the first vector. This pattern continues, without further elaboration.

[0219] In some implementations, the union of the at least one vector and the first vector is designated as union #1. The first matrix can be used to indicate the recursive relationship (or association or correspondence) between vectors in union #1 that correspond to adjacent sub-bands; the first matrix can be used to indicate the recursive relationship (or association or correspondence) between adjacent vectors in union #1; or, the product of the first matrix and the first vector can be used to determine the vector adjacent to the first vector in the at least one vector; or, the product of the first matrix and one of the at least one vectors can be used to determine another vector adjacent to that vector in the at least one vector. Adjacent sub-bands can be sub-bands with adjacent indices. For example, the first sub-band and the second sub-band among M sub-bands are adjacent sub-bands. Adjacent vectors can be vectors with adjacent indices. For example, the first vector and the second vector among M vectors are adjacent vectors.

[0220] 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 vectors that are separated by O indices in set #1, where O is a positive integer.

[0221] Optionally, the first vector is the i-th vector among M1 vectors, where i is an integer from 1 to M1. The set of at least one vector and the first vector is M3 vectors, where M3 is a positive integer. The b1-th vector among the M3 vectors is x. a1+b1-1,1 a1 is a positive integer, and b1 takes integer values ​​from 1 to M3. The first matrix G... f,i The following formula (1) can be satisfied; or, the first device can determine the first matrix G according to the following formula (1). f,i G f,i =Y f,i *pinv(X f,i ), formula (1)

[0222] Among them, Y f,i =[x a1+1,1 ,x a1+2,1 ,…,x a1+M3-1,1 ], X f,i =[x a1,1 ,x a1+1,1 ,…,x a1+M3-2,1 ], pinv indicates the pseudo-inverse operation.

[0223] For example, the first vector is the first vector among M1 vectors; the set of at least one vector and the first vector is the set of vectors from the first to the tenth of the M vectors, which can be represented as x. 1,1 ,x 2,1 ,…,x 10,1 Y f,1 =[x 2,1 ,x 3,1 ,…,x 10,1 ], X f,1 =[x 1,1 ,x 2,1 ,…,x 9,1 ], the first matrix G corresponding to the first vector f,1 =Y f,1 *pinv(X f,1 ).

[0224] For example, the first vector is the second vector among M1 vectors; the set of at least one vector and the first vector is the 11th to 20th vectors among the M vectors, which can be represented as x respectively. 11,1 ,x 12,1 ,…,x 20,1 Y f,2 =[x 12,1 ,x 13,1 ,…,x 20,1 ], X f,2 =[x 11,1 ,x 12,1 ,…,x 19,1 ], the first matrix G corresponding to the first vector f,2 =Y f,2 *pinv(X f,2 ).

[0225] 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, X f,i and / or Y f,i The positions of the column vectors in the array can change. For example, X... f,i and / or Y f,i It may include a smaller number of column vectors. Any variations of formula (1) are within the scope of protection of this application.

[0226] In this way, the first device can accurately determine the first matrix according to formula (1), thereby accurately determining the recursive relationship between the at least one vector and the first vector.

[0227] As previously stated, the first matrix and the first vector can be used to determine at least one vector among the M vectors, thus, M1 vectors and M1 matrices can be used to determine the M vectors. The first vector may correspond to the first sub-band among the M sub-bands. The first vector may be a coefficient corresponding to the precoding matrix of the first sub-band; or, the first vector may be used to determine the precoding matrix of the first sub-band; or, there is a correspondence (or association) between the first vector and the precoding matrix of the first sub-band. The at least one vector may correspond to at least one sub-band, for example, the at least one vector may correspond one-to-one with at least one sub-band. Each of the at least one vectors may be a coefficient corresponding to the precoding matrix of one sub-band among at least one sub-band; or, each of the at least one vectors may be used to determine the precoding matrix of one sub-band among at least one sub-band; or, there is a correspondence (or association) between each of the at least one vectors and the precoding matrix of one sub-band among at least one sub-band.

[0228] The following explanation uses the example of a first matrix and a first vector used to determine at least one vector. There are multiple ways to use the first matrix and the first vector to determine at least one vector, such as method a1, method a2, or method a3.

[0229] Method a1: The first matrix and the first vector are used to determine at least one vector whose index is greater than that of the first vector; or, the first matrix and the first vector are used to determine at least one vector whose index of at least one sub-band is greater than that of the first sub-band corresponding to the first vector.

[0230] Optionally, the first vector can be represented as x k1,1 k1 is a positive integer. Any vector in at least one vector can be represented as x. k2,1 k2 is a positive integer. k2 is greater than k1. k2,1 =G f,i k2-k1 *x k1,1 Among them, G f,i Let G be the first matrix. f,i k2-k1 For G f,i The power of k2-k1, where i is an integer greater than or equal to 1 and less than or equal to M1.

[0231] For example, as shown in Figure 4A, the first vector is the first vector x among the M vectors. 1,1 The at least one vector is the 2nd to 10th vector among the M vectors, which can be represented as x respectively. 2,1 ,x 3,1 ,…,x 10,1 ;x 1,1 The corresponding first matrix is ​​G f,1 The second vector x in the M vectors.2,1 =G f,1 *x 1,1 The third vector x among the M vectors 3,1 =G f,1 2 *x 1,1 And so on, without further explanation.

[0232] For example, as shown in Figure 4A, the first vector is the 11th vector x among the M vectors. 11,1 The at least one vector is the 12th to 20th vector among the M vectors, and can be represented as x. 12,1 ,x 13,1 ,…,x 20,1 ;x 11,1 The corresponding first matrix is ​​G f,2 The 12th vector x in the M vectors. 12,1 =G f,2 *x 11,1 The 13th vector x in the M vectors 13,1 =G f,2 2 *x 11,1 And so on, without further explanation.

[0233] Optionally, in method a1, the at least one vector may be determined based on the first matrix and the first vector in ascending order of the indices of at least one sub-band; or, the at least one vector may be determined based on the first matrix and the first vector in ascending order of the indices of at least one vector; or, the second device may determine the at least one vector based on the first matrix and the first vector in ascending order of the indices of at least one sub-band; or, the second device may determine the at least one vector based on the first matrix and the first vector in ascending order of the indices of at least one vector. For example, the first vector is the first vector x among the M vectors. 1,1 The at least one vector is the 2nd to 10th vector among the M vectors. The second device can be based on x. 1,1 Together with the first matrix, determine the 2nd to 10th vectors from the M vectors in sequence.

[0234] By means of method a1, the second device can accurately determine at least one vector whose index is greater than that of the first vector based on the first matrix and the first vector.

[0235] Optionally, each pair of matrices and vectors in the M1 matrices and M1 vectors can be used to determine a set of vectors according to method a1, thereby determining the M vectors. For example, the M vectors may include: x 1,1 ,x 2,1 ,…,x 50,1 The M1 vectors may include: x 1,1x 11,1 x 21,1 x 31,1 , and x 41,1 The M1 matrices may include: G f,1 G f,2 G f,3 G f,4 and G f,5 x 1,1 and G f,1 It can be used to determine the 2nd to 10th vectors among the M vectors according to method a1; x 11,1 and G f,2 It can be used to determine the 12th to 20th vectors among the M vectors according to method a1; x 21,1 and G f,3 It can be used to determine the 22nd to 30th vectors among the M vectors according to method a1; x 31,1 and G f,4 It can be used to determine the 32nd to 40th vectors among the M vectors according to method a1; x 41,1 and G f,5 This can be used to determine the 42nd to 50th vectors among the M vectors according to method a1. In this way, the second device can accurately determine the M vectors based on M1 matrices and M1 vectors.

[0236] Method a2: The first matrix and the first vector are used to determine at least one vector whose index is less than that of the first vector; or, the first matrix and the first vector are used to determine at least one vector whose index of at least one sub-band is less than that of the first sub-band corresponding to the first vector.

[0237] Optionally, the first vector can be represented as x k1,1 k1 is a positive integer. Any vector in at least one vector can be represented as x. k2,1 k2 is a positive integer. k2 is less than k1. k2,1 =inv(G f,i ) |k2-k1| *x k1,1 Among them, G f,i For the first matrix, inv(G) f,i ) is G f,i The inverse matrix, inv(G) f,i ) |k2-k1| for inv(G f,i The |k2-k1| power of ) is where || represents the absolute value operation, and i is an integer greater than or equal to 1 and less than or equal to M1.

[0238] For example, as shown in Figure 4B, the first vector is the 10th vector x among the M vectors. 10,1The at least one vector is the 1st to 9th vector among the M vectors, which can be represented as x respectively. 1,1 ,x 2,1 ,…,x 9,1 ;x 10,1 The corresponding first matrix is ​​G f,1 The 9th vector x among the M vectors 9,1 =inv(G f,1 )*x 10,1 The 8th vector x in the M vectors 8,1 =inv(G f,1 ) 2 *x 10,1 And so on, without further explanation.

[0239] For example, as shown in Figure 4B, the first vector is the 20th vector x among the M vectors. 20,1 The at least one vector is the 11th to 19th vector among the M vectors, which can be represented as x respectively. 11,1 ,x 12,1 ,…,x 19,1 ;x 20,1 The corresponding first matrix is ​​G f,2 The 19th vector x in the M vectors. 19,1 =inv(G f,2 )*x 20,1 The 18th vector x in the M vectors 18,1 =inv(G f,2 ) 2 *x 20,1 And so on, without further explanation.

[0240] Optionally, in method a2, the at least one vector may be determined based on the first matrix and the first vector in descending order of the indices of at least one sub-band; or, the at least one vector may be determined based on the first matrix and the first vector in descending order of the indices of at least one vector; or, the second device may determine the at least one vector based on the first matrix and the first vector in descending order of the indices of at least one sub-band; or, the second device may determine the at least one vector based on the first matrix and the first vector in descending order of the indices of at least one vector. For example, the first vector is the 10th vector x among the M vectors. 10,1 The at least one vector is the 1st to 9th vector among the M vectors. The second device can be based on x. 10,1 Together with the first matrix, determine the 9th to 1st vectors from the M vectors in sequence.

[0241] By means of method a2, the second device can accurately determine at least one vector whose index is less than that of the first vector based on the first matrix and the first vector.

[0242] Optionally, each pair of matrices and vectors in the M1 matrices and M1 vectors can be used to determine a set of vectors according to method a2, thereby determining the M vectors. For example, the M vectors may include: x 1,1 ,x 2,1 ,…,x 50,1 The M1 vectors may include: x 10,1 x 20,1 x 30,1 x 40,1 , and x 50,1 The M1 matrices may include: G f,1 G f,2 G f,3 G f,4 and G f,5 x 10,1 and G f,1 It can be used to determine the 1st to 9th vectors among the M vectors according to method a2; x 20,1 and G f,2 It can be used to determine the 11th to 19th vectors among the M vectors according to method a2; x 30,1 and G f,3 It can be used to determine the 21st to 29th vectors among the M vectors according to method a2; x 40,1 and G f,4 It can be used to determine the 31st to 39th vectors among the M vectors according to method a2; x 50,1 and G f,5 This can be used to determine the 41st to 49th vectors among the M vectors according to method a2. In this way, the second device can accurately determine the M vectors based on M1 matrices and M1 vectors.

[0243] Method a3: The first matrix and the first vector are used to determine the at least one vector, and the at least one vector includes indices greater than and less than the first vector; or, the first matrix and the first vector are used to determine the at least one vector, and the indices of the at least one sub-band corresponding to the at least one vector include indices greater than and less than the indices of the first sub-band corresponding to the first vector; or, the at least one vector can be determined according to the first matrix and the first vector in a recursive order starting from the indices of the first sub-bands.

[0244] Optionally, the first vector can be represented as x k1,1 k1 is a positive integer. Any vector in at least one vector can be represented as x. k2,1 k2 is a positive integer. When k2 is greater than k1, x k2,1 =G f,i k2-k1 *x k1,1When k2 is less than k1, x k2,1 =inv(G f,i ) |k2-k1| *x k1,1 Among them, G f,i Let G be the first matrix. f,i k2-k1 For G f,i k2-k1, inv(G f,i ) is G f,i The inverse matrix, inv(G) f,i ) |k2-k1| for inv(G f,i The |k2-k1| power of ) is where || represents the absolute value operation, and i is an integer greater than or equal to 1 and less than or equal to M1.

[0245] For example, as shown in Figure 4C, the first vector is the 5th vector x among the M vectors. 5,1 The at least one vector is the 1st to 4th vector and the 6th to 9th vector among the M vectors, which can be represented as x respectively. 1,1 ,x 2,1 ,…,x 4,1 ,x 6,1 ,x 7,1 ,…,x 9,1 ;x 5,1 The corresponding first matrix is ​​G f,1 The 6th vector x in the M vectors. 6,1 =G f,1 *x 5,1 The 7th vector x in the M vectors 7,1 =G f,1 2 x 5,1 And so on, without further explanation. The 4th vector x in these M vectors... 4,1 =inv(G f,1 )*x 5,1 The third vector x among the M vectors 3,1 =inv(G f,1 ) 2 *x 5,1 And so on, without further explanation.

[0246] For example, the first vector is the 14th vector x among the M vectors. 14,1 The at least one vector is the 10th to 13th vector and the 15th to 18th vector among the M vectors, which can be represented as x respectively. 10,1 ,x 11,1 ,…,x 13,1 ,x 15,1 ,x 16,1 ,…,x18,1 ;x 14,1 The corresponding first matrix is ​​G f,2 The 15th vector x in the M vectors. 15,1 =G f,2 *x 14,1 The 16th vector x in the M vectors 16,1 =G f,2 2 *x 14,1 And so on, without further explanation. The 13th vector x in these M vectors... 13,1 =inv(G f,2 )*x 14,1 The 12th vector x in the M vectors 12,1 =inv(G f,2 ) 2 *x 14,1 And so on, without further explanation.

[0247] Using method a3, the second device can accurately determine at least one vector whose index is greater than or less than the first vector based on the first matrix and the first vector. Furthermore, in this method, the second device can recursively deduce at least one vector from the first vector in both directions, i.e., starting from the first vector and deducing at least one vector in both directions, thereby reducing the spread of quantization errors.

[0248] Optionally, each pair of matrices and vectors in the M1 matrices and M1 vectors can be used to determine a set of vectors according to method a3, thereby determining the M vectors. For example, the M vectors may include: x 1,1 ,x 2,1 ,…,x 45,1 The M1 vectors may include: x 5,1 x 14,1 x 23,1 x 32,1 , and x 41,1 The M1 matrices may include: G f,1 G f,2 G f,3 G f,4 and G f,5 x 5,1 and G f,1 It can be used to determine the 1st to 4th vectors and the 6th to 9th vectors among the M vectors according to method a3; x 14,1 and G f,2 This can be used to determine the 10th to 13th vectors and the 15th to 18th vectors among the M vectors according to method a3; x 23,1 and G f,3This can be used to determine the 19th to 22nd vectors and the 24th to 27th vectors among the M vectors according to method a3; x 32,1 and G f,4 This can be used to determine the 28th to 31st vectors and the 33rd to 36th vectors among the M vectors according to method a3; x 41,1 and G f,5 This can be used to determine the 37th to 40th vectors and the 42nd to 45th vectors among the M vectors according to method a3. In this way, the second device can accurately determine the M vectors based on the M1 matrices and M1 vectors.

[0249] In some implementations, in method a3, the first difference can be greater than the second difference. The first difference can be the absolute value of the difference between the index of the second sub-band and the index of the third sub-band, where the second sub-band is any sub-band among at least one sub-band, and the third sub-band is any sub-band among the M1 sub-bands excluding the first sub-band; the second difference is the absolute value of the difference between the index of the second sub-band and the index of the first sub-band. Alternatively, any vector among the M vectors excluding the M1 vectors can be determined based on the vector among the M1 vectors whose index has the smallest absolute value. For example, the M vectors may include: x 1,1 ,x 2,1 ,…,x 45,1 The M1 vectors may include: x 5,1 x 14,1 x 23,1 x 32,1 , and x 41,1 x 8,1 With x in the M1 vectors 5,1 The absolute value of the difference between the indices is the smallest, x 8,1 Based on x 5,1 This is confirmed. Through this implementation, the first and second devices can accurately determine which of the M1 vectors each vector can be used to determine which of the M vectors.

[0250] Optionally, for any vector other than the M1 vectors among the M vectors, if the absolute value of the difference between the index of the vector and multiple vectors among the M1 vectors is the smallest, the vector used to determine the vector can be determined from the multiple vectors according to condition #1; or, the second device can select the vector used to determine the vector from the multiple vectors according to condition #1. Condition #1 may include, but is not limited to, at least one of the following: the vector used to determine the vector is the vector with the smallest index among the multiple vectors; or, the vector used to determine the vector is the vector with the largest index among the multiple vectors. The following explanation uses the example where condition #1 includes: the vector used to determine the vector is the vector with the smallest index among the multiple vectors. For example, the M vectors may include: x 1,1 ,x 2,1,…,x 50,1 The M1 vectors may include: x 5,1 x 15,1 x 25,1 x 35,1 , and x 45,1 x 10,1 With x in the M1 vectors 5,1 and x 15,1 The difference between the serial numbers is the smallest, x 5,1 The sequence number is less than x 15,1 The serial number, x 10,1 Based on x 5,1 Sure.

[0251] In some possible ways, the manner in which the first matrix and the first vector are used to determine at least one vector can be predetermined, such as as specified by a protocol. For example, the manner in which the first matrix and the first vector are used to determine at least one vector can be predetermined as manner a1, manner a2, or manner a3.

[0252] In some other possible ways, the first matrix and the first vector are used to determine at least one vector in a manner that the second device indicates to the first device, as will be described in detail in S309 below, and will not be elaborated here.

[0253] In some other possible ways, the first matrix and the first vector are used to determine at least one vector, which may be indicated by the first device to the second device. The details will be described in S310 below and will not be elaborated here.

[0254] As mentioned earlier, the first information can indicate M1 matrices, and there can be multiple ways of indicating them, such as mode b1, mode b2, or mode b3.

[0255] Method b1: The first information may include M1 matrices.

[0256] For example, the M1 matrices include: G f,1 G f,2 G f,3 G f,4 and G f,5 The first piece of information includes: G f,1 G f,2 G f,3 G f,4 and G f,5 .

[0257] In this way, the second device can accurately determine M1 matrices based on the first information. Furthermore, in this method, the first information can directly indicate the M1 matrices, so the second device does not need to calculate to determine the M1 matrices, thereby reducing the computational complexity of the second device.

[0258] Method b2: The first information includes: the second matrix among the M1 matrices, and the difference between the second matrix and the matrices other than the second matrix among the M1 matrices.

[0259] Optionally, the second matrix can be the first matrix of the M1 matrices, or the last matrix of the M1 matrices, or a matrix located in the middle of the M1 matrices.

[0260] For example, the M1 matrices include: G f,1 G f,2 G f,3 G f,4 and G f,5 The first piece of information may include: G f,1 G f,2 -G f,1 G f,3 -G f,1 G f,4 -G f,1 and G f,5 -G f,1 .

[0261] For example, the M1 matrices include: G f,1 G f,2 G f,3 G f,4 and G f,5 The first piece of information may include: G f,5 G f,1 -G f,5 G f,2 -G f,5 G f,3 -G f,5 and G f,4 -G f,5 .

[0262] For example, the M1 matrices include: G f,1 G f,2 G f,3 G f,4 and G f,5 The first piece of information may include: G f,3 G f,1 -G f,3 G f,2 -G f,3 G f,4 -G f,3 and G f,5 -G f,3 .

[0263] The position of the second matrix among the M1 matrices (or, which of the M1 matrices the second matrix is) can be predetermined, for example, as specified by a protocol; or it can be determined by the first device; or it can be notified to the first device by another device (e.g., core network equipment or the second device). If the first device determines the position of the second matrix among the M1 matrices, the first device can indicate the position of the second matrix among the M1 matrices to the second device, for example, the first device can indicate the sequence number of the second matrix to the second device.

[0264] In this method, the first information may include the second matrix among M1 matrices, and the differences between the second matrix and the other matrices among the M1 matrices. Compared to including M1 matrices, this method can improve the accuracy of the transmitted information, i.e., improve the accuracy of the transmitted M1 matrices, while using the same number of transmitted bits.

[0265] Method b3: The first information may include information that corresponds to the M1 matrices.

[0266] The following explanation uses the first matrix as an example to illustrate that the first information includes information that corresponds to the M1 matrices.

[0267] In some implementations, the first information may include 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,i =Ψ1*Λ1*Ψ1 H Among them, G f,i This is the first matrix; Ψ1 H This is the conjugate transpose of Ψ1. 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 determine the first matrix based on Λ1, Ψ1, and Ψ1. H We compute at least one of M vectors in parallel. For example, if the first vector is x... 1,1 The first matrix is ​​G f,i In this case, the third vector among the M vectors can be x. 1,1 *G f,i 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,i3 =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 at least one vector among the 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 load of the second device. This saves computation time and resources and reduces the computational load.

[0268] 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,i And G f,i =Ψ1*Λ1*Ψ1 H In this case, the first information may include: Ψ1 H *x 1,1 Λ1 and Ψ1. 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 determine the first matrix based on Λ1, Ψ1, and Ψ1. H We compute at least one of M vectors in parallel. For example, if the first vector is x... 1,1 The first matrix is ​​G f,i In this case, the third vector among the M vectors can be x. 1,1 *G f,i 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,i 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 at least one vector among the 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 low, thus reducing the computational load on the second device. This saves computation time and resources and reduces the computational load. In addition, 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 at least one vector among the M vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0269] Optionally, mode b3 can be combined with mode b1 or mode b2. For example, when mode b3 is combined with mode b1, each of the M1 matrices can be indicated by mode b3 in the first information. Also, for example, when mode b2 is combined with mode b1, the second matrix can be indicated by mode b3 in the first information.

[0270] In some possible ways, the way in which the first information indicates the M1 matrices can be preset, for example, as specified by a protocol. For example, the way in which the first information indicates the M1 matrices can be preset as mode b1, mode b2, or mode b3.

[0271] In some other possible ways, the first information indicates M1 matrices, which may be indicated by the second device to the first device. The details will be described in S309 below and will not be elaborated here.

[0272] Among other possible methods, the first information indicating M1 matrices can be indicated by the first device to the second device. The details will be described in S310 below and will not be elaborated here.

[0273] As mentioned earlier, the first information may indicate M1 vectors, which may correspond to M1 subbands. Each of the M1 vectors includes the coefficients corresponding to the precoding matrix of each of the M1 subbands; or, each of the M1 vectors may be a coefficient in the first coefficient matrix corresponding to one of the M1 subbands. There are multiple ways to obtain these M1 subbands, such as one of methods c1 to c5.

[0274] Method c1: M1 sub-bands can be indicated by the second device to the first device. The details will be described in S309 below and will not be elaborated here.

[0275] Method c2: The M1 sub-bands can be determined by the first device. Optionally, in method c2, the first device can indicate the M1 sub-bands to the second device, the details of which will be described in S310 below and will not be elaborated here.

[0276] Method c3: The candidate subband range of M1 subbands is preset, for example, as specified in the protocol. The candidate subband range includes M1 subbands. In this way, the first device can obtain (or select or determine) M1 subbands from the candidate subband range.

[0277] For example, the candidate subband range includes: the 5th subband, the 10th subband, and the 15th subband. The M1 subbands may include: the 5th subband, the 10th subband, and the 15th subband.

[0278] For example, the candidate subband range includes: the 5th subband, the 10th subband, and the 15th subband. The M1 subbands may include: the 5th subband and the 10th subband.

[0279] Using method c3, the first device can accurately determine M1 subbands. Furthermore, in this method, the first device does not need to obtain the candidate subband range from other devices, thereby reducing signaling overhead.

[0280] Method c4: The candidate subband range of M1 subbands can be indicated by the second device to the first device. The details will be described in S309 below and will not be elaborated here. In this way, the first device can obtain (or select or determine) M1 subbands from the candidate subband range. The method of obtaining them can be referred to method c3 and will not be repeated here.

[0281] Method c5: The candidate subband range of M1 subbands can be determined by the first device. In this way, the first device can obtain (or select or determine) M1 subbands from the candidate subband range. The method of obtaining them can be referred to method c3, and will not be repeated here.

[0282] Optionally, in mode c5, the first device may indicate the range of candidate subbands of M1 subbands to the second device. The details will be described in S310 below and will not be elaborated here.

[0283] Optionally, in the method shown in Figure 3, the first information also indicates the M1 sub-bands corresponding to the M1 vectors. In this way, the second device can accurately determine which sub-bands correspond to the M1 vectors.

[0284] Optionally, in S302, the value of M1 is negatively correlated with the stability of the first-order flow; or, at least one flow includes flow #1 and flow #2, where the stability of flow #1 is higher than that of flow #2, and the value of M1 corresponding to flow #1 can be less than or equal to the value of M1 corresponding to flow #2. For example, at least one flow includes flow #1 and flow #2. Flow #1 corresponds to information #1 in at least one piece of information; flow #2 corresponds to information #2 in at least one piece of information. The stability of flow #1 is higher than that of flow #2. The M1 vectors and M1 matrices indicated by information #1 may include: 5 vectors and 5 matrices; the M1 vectors and M1 matrices indicated by information #2 may include: 10 vectors and 10 matrices. Thus, for a flow with high stability, the first device can report fewer coefficients corresponding to the precoding matrices of sub-bands, thereby reducing the overhead of the feedback precoding matrix; for a flow with low stability, the first device can report more coefficients corresponding to the precoding matrices of sub-bands, thereby improving the accuracy of the feedback precoding matrix.

[0285] In some implementations, the transmission period of the first information is positively correlated with the stability of the first-order flow. Alternatively, at least one flow includes flow #1 and flow #2, where flow #1 corresponds to information #1 in at least one information, and flow #2 corresponds to information #2 in at least one information. The stability of flow #1 is higher than that of flow #2. The transmission period of information #1 can be greater than or equal to the transmission period of information #2. For example, the transmission period of information #1 can be 10 time slots, and the transmission period of information #2 can be 5 time slots. Thus, for flows with high stability, the first device can use a longer period to feed back the precoding matrix, thereby reducing the overhead of the feedback precoding matrix; for flows with low stability, the first device can use a shorter period to feed back the precoding matrix, thereby improving the accuracy of the feedback precoding matrix.

[0286] Optionally, in S302, at least one piece of information may include J pieces of information, which correspond to J streams. Each of the J pieces of information may indicate a set of vectors and matrices, and each set of vectors and matrices may be used to determine the coefficient matrix corresponding to the precoding matrix of a stream. This application uses one piece of information (i.e., the first piece of information) as an example for illustration. The specific content of the other pieces of information in the at least one piece of information can be referred to the description of the first piece of information in this application, and will not be repeated here.

[0287] Using the method shown in Figure 3, the first device can send at least one piece of information, which corresponds to at least one stream. The first information can be any one of the at least one pieces of information, and it corresponds to a first stream within the at least one stream. The first information can indicate a subset of M vectors (i.e., M1 vectors), and a recursive relationship between each of the M1 vectors and the other vectors in the M vectors. Thus, the second device can accurately determine the M vectors based on the M1 vectors and the recursive relationship, thereby determining the precoding matrix 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.

[0288] 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 matrices of M1 sub-bands, 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 matrices of M1 sub-bands, 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.

[0289] Alternatively, since the first device may not send each of the M vectors, the method can improve the accuracy of the indicated M1 vectors and / or M1 matrices without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the M vectors recovered by the second device.

[0290] 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.

[0291] Among some possible approaches, the method shown in Figure 3 also includes:

[0292] S303: The second device sends a first signal; correspondingly, the first device receives the first signal.

[0293] In some examples, such as Scenario 1 above, the first signal may be a downlink signal.

[0294] In other examples, such as scenario 2 above, the first information may be an uplink signal.

[0295] 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.

[0296] The precoding matrices for the M subbands can be determined based on M vectors; or, the second device can determine the precoding matrices for the M subbands based on M vectors; or, the M vectors can be used to determine the precoding matrices for the M subbands. Specifically, the M vectors are determined based on M1 vectors and M1 matrices indicated by the first information. The method of determination can be found in the explanation in S302 regarding "M1 vectors and M1 matrices can be used to determine the M vectors," and will not be repeated here.

[0297] The following example, based on the description of the M vectors in S302, illustrates the statement that "the precoding matrix of the M subbands can be determined based on the M vectors".

[0298] According to the description of the M vectors in S302, these 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.

[0299] Optionally, the second device may determine the precoding matrix for the M subbands through steps A1 to A2:

[0300] Step A1: 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) .

[0301] 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) .

[0302] 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).

[0303] The second device can perform step A1 for each of the first to J streams to obtain the precoding matrix for each of the first to J streams. Optionally, the first basis vectors corresponding to different streams among the first to J streams can be different (or independent).

[0304] Step A2: 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.

[0305] According to the description of the M vectors in S302, 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 2), 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.

[0306] Optionally, after obtaining the precoding matrix of each stream from the 1st to the Jth stream, the second device can orthogonalize the precoding matrices of the 1st to the Jth streams to obtain orthogonalized precoding matrices of each stream from the 1st to the Jth streams, and determine the precoding matrix of each of the M subbands based on the orthogonalized precoding matrices of each stream from the 1st to the Jth streams. This application does not limit the orthogonalization process. The specific content of the precoding matrix of each of the M subbands determined by the second device based on the orthogonalized precoding matrices of each stream from the 1st to the Jth streams can be described in step A2 as follows: "The second device determines the precoding matrix of each of the M subbands based on the precoding matrices of each stream from the 1st to the Jth streams," except that "precoding matrix of each stream from the 1st to the Jth streams" is replaced with "orthogonalized precoding matrix of each stream from the 1st to the Jth streams," and will not be repeated here.

[0307] Among some possible approaches, the method shown in Figure 3 also includes:

[0308] S304: The second device sends the first instruction information; correspondingly, the first device receives the first instruction information.

[0309] Optionally, S304 can be used in scenario 1 above.

[0310] 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.

[0311] 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 M1 vectors and M1 matrices; or, when the CSI feedback method is the new method, the precoding matrix can be indicated by a subset of the M vectors and the recursive relationship between different vectors in 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 may differ from methods 1 and 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.

[0312] 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 d1, method d2, or method d3:

[0313] Method d1: 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.

[0314] 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.

[0315] 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.

[0316] 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.

[0317] Through method d1, 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.

[0318] Method d2: The second device may 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.

[0319] 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.

[0320] 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).

[0321] 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.

[0322] 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.

[0323] 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.

[0324] 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.

[0325] 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.

[0326] 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.

[0327] 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.

[0328] 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.

[0329] 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.

[0330] 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.

[0331] 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.

[0332] 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] 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.

[0341] For example, Table 3 shows one possible example of the correspondence between at least one condition and at least one manner.

[0342] Table 3

[0343] 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.

[0344] Table 4

[0345] Method d3: The second device can determine the first instruction information on its own.

[0346] 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 d1, 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.

[0347] It should be understood that modes d1 to d3 can be independent or combined with each other. For example, modes d1 and d3 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.

[0348] 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.

[0349] Optionally, S304 can precede S302. This application does not restrict the execution order of S304 and S301.

[0350] 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 e1, mode e2, or mode e3.

[0351] Mode e1: When the first indication information indicates that the method for feeding back channel status information is a new method, the first device sends at least one piece of information; correspondingly, the second device receives at least one piece of 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.

[0352] Optionally, if the first indication information indicates that the method for feeding back channel state information is a new method, and the first device has a first capability, the first device sends at least one piece of information; correspondingly, the second device receives at least one piece of information. The specific content of the first capability can be referred to the description of the first capability in method d1 above, and will not be repeated here. Optionally, this method can be combined with any of methods d1 to d3 above.

[0353] In this manner, the first device can send at least one piece of 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.

[0354] Method e2: When the first indication information indicates that the method for feeding back channel state information is Method 1, the first device sends the 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.

[0355] Mode e3: When the first indication information indicates that the mode for feeding back channel state information is mode 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.

[0356] Optionally, the method shown in Figure 3 further includes S305:

[0357] S305: The first device sends first capability information; correspondingly, the second device receives the first capability information.

[0358] Optionally, S305 can be used in scenario 1 above.

[0359] The first capability information indicates whether the first device possesses a first capability. The specific details of the first capability can be found in the explanation of the first capability in method d1 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 first capability information.

[0360] In some implementations, S305 may precede S304. Optionally, in this implementation, mode d1 may be replaced by: the second device determining the first instruction information based on the first capability information; or, the first instruction information may be determined based on the first capability information.

[0361] In other implementations, S305 may follow S304. For example, after receiving the first instruction information, the first device may send first capability 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 at least one piece of information and execute S303 based on the at least one piece of information; if the first device does not have the first capability, the second device may receive a PMI determined according to a Type 1 codebook or a Type 2 codebook, determine a second precoding matrix accordingly, and send a downlink signal to the first device based on the second precoding matrix.

[0362] This application does not limit the specific manner in which the first device transmits the first capability information. For example, the first device may transmit the first capability information periodically or aperiodically. As another example, the first device may transmit the first capability information independently, or the first device may transmit the first capability information based on a request (or instruction) from the second device. The above examples may be independent or combined with each other.

[0363] Furthermore, the first capability information can be carried in a traditional message or in a new message, without restriction. For example, the first capability information can be carried in a UCI or RRC message.

[0364] Among other possible approaches, the method shown in Figure 3 also includes S306:

[0365] 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.

[0366] Optionally, S306 can be used in either scenario 1 or scenario 2 above.

[0367] The specific details of the first correspondence can be found in the explanation of the first correspondence in method d2 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 second device).

[0368] 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 f1 or mode f2.

[0369] Method f1: 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 at least one piece of information; correspondingly, the second device receives at least one piece of 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 may execute S302.

[0370] For details on the first condition, please refer to the explanation of the first condition in method d2; repeated points will not be elaborated upon. The differences between scenario 1 and scenario 2 will be explained below.

[0371] For scenario 1:

[0372] For example, the first condition includes condition a1 in method d2. 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 d2. 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. As yet another example, the first condition includes condition a3 in method d2. 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. As yet another example, the first condition includes condition a4 in method d2. 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. As yet another example, the first condition includes condition a5 in method d2. 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.

[0373] 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.

[0374] 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.

[0375] For scenario 2:

[0376] For example, the first condition includes condition a1 in method d2. 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 d2. 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 d2. 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 d2. 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 d2. 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.

[0377] 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 satisfied, and the first device can transmit at least one piece of information.

[0378] 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 satisfied, and the first device can transmit at least one piece of information.

[0379] For details on the new method, please refer to the description of the new method in S304, which will not be repeated here.

[0380] In mode f1, the first device can accurately determine whether to send at least one piece of information based on the first correspondence. In this mode, the second device may not instruct the first device on how to provide feedback CSI, thereby reducing signaling overhead.

[0381] Method f2: 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.

[0382] For details regarding the second condition, please refer to the explanation of the second condition in method d2; repeated points will not be elaborated upon. The differences between scenario 1 and scenario 2 will be explained below.

[0383] For scenario 1:

[0384] For example, the second condition includes condition b1 in method d2. 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 d2. 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 d2. 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 d2. 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 d2. 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 b5 is satisfied. The above examples can be independent or combined with each other.

[0385] For scenario 2:

[0386] For example, the second condition includes condition b1 in method d2. 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 d2. 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. Yet another example, the second condition includes condition b3 in method d2. 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. Yet another example, the second condition includes condition b4 in method d2. 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. Yet another example, the second condition includes condition b5 in method d2. 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.

[0387] 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.

[0388] S306 can precede S302. This application does not restrict the execution order of S306 and S301.

[0389] In some other possible embodiments, S302 may include: if the first condition is met, the first device may send at least one piece of information; correspondingly, the second device may receive at least one piece of information. The specific content of the first condition can be found in the description of the first condition in embodiment d2, and will not be repeated here.

[0390] Among some possible approaches, the method shown in Figure 3 may also include S307:

[0391] 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).

[0392] Optionally, S307 can be used in scenario 2 above.

[0393] 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.

[0394] 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 g1, method g2, or method g3:

[0395] Method g1: 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.

[0396] The details of method g1 can be found in method d1, except that the first device and the second device are interchanged, and will not be repeated here.

[0397] Method g2: 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.

[0398] For details on the first correspondence, please refer to the explanation of the first correspondence in method d2, which will not be repeated here.

[0399] 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 d1, and will not be repeated here.

[0400] 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.

[0401] 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.

[0402] 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 d2, and will not be repeated here.

[0403] 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.

[0404] 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.

[0405] Method g3: The first device can determine the first instruction information on its own.

[0406] For details of method g3, please refer to method d3, except that the second device is replaced by the first device, which will not be repeated here.

[0407] It should be understood that modes g1 to g3 can be independent or combined with each other. For example, modes g1 and g3 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.

[0408] 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.

[0409] The order of S307 with S301 to S302 is not limited. Optionally, S307 may precede S301 and / or S302.

[0410] Optionally, if the first indication information indicates that the method of CSI feedback is a new method, the first device may send at least one piece of information; correspondingly, the second device may receive at least one piece of information. In other words, if the first indication information indicates that the method of CSI feedback is a new method, the first device may execute S302. In this way, the first device may indicate to the second device that the method of CSI feedback is a new method. Thus, after sending at least one piece of information to the second device, the second device may process at least one piece of information according to the new method, for example, it may determine M vectors based on at least one piece of information. Furthermore, in this method, the first device may indicate the method of CSI feedback to the second device, thus allowing the first device to flexibly manage the method of CSI feedback.

[0411] 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 h1 or mode h2.

[0412] Mode h1: 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.

[0413] 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.

[0414] Mode h2: 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.

[0415] Optionally, the method shown in Figure 3 may also include S308:

[0416] S308: The second device can send second capability information; correspondingly, the first device can receive the second capability information.

[0417] Optionally, S308 can be used in scenario 2 above.

[0418] The second capability information indicates whether the second device possesses the first capability. The specific content of the first capability can be found in the description of the first capability in method d1 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 second capability information.

[0419] In some implementations, S308 may precede S307. Optionally, in this implementation, mode g1 may be replaced by: the first device determining the first instruction information based on the second capability information; or, the first instruction information may be determined based on the second capability information.

[0420] In other implementations, S308 may follow S307. For example, after receiving the first indication information, the second device may send second capability 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 at least one piece of information, and correspondingly, the second device may receive at least one piece of information and execute S303 based on the at least one piece of 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 based on the second precoding matrix.

[0421] Among some possible approaches, the method shown in Figure 3 may also include S309:

[0422] S309: The second device can send the second information; correspondingly, the first device can receive the second information.

[0423] Optionally, S309 can be used in scenario 1 above.

[0424] The second information may indicate parameters for some or all of the flows in at least one flow. In some examples, the second information may indicate parameters for each flow in that part or all of the flow, individually. For example, if at least one flow includes flow #1 and flow #2, the second information may indicate parameters for flow #1 and flow #2, respectively. Optionally, where the second information indicates parameters for each flow in that part or all of the flow, the parameters for different flows may be independent. In other examples, the second information may indicate one or more sets of parameters. Each set of parameters in this set or sets may be parameters for one or more flows in that part or all of the flow. For example, if at least one flow includes flows #1 to #3, the second information may indicate: a first set of parameters and a second set of parameters. The first set of parameters may be parameters for flow #1, and the second set of parameters may be parameters for flows #2 and #3.

[0425] Optionally, the streams may include stream #1 and stream #2, and the parameters of stream #1 and stream #2 may be different. In this way, the second device can configure different parameters for the first device for different streams, thereby enabling flexible management of the feedback of the precoding matrix for different streams.

[0426] As mentioned earlier, the first flow is any one of at least one flows. The following explanation uses the second information indicating the parameters of the first flow as an example.

[0427] The second information may indicate at least one of the following: the manner in which the first matrix and the first vector are used to determine at least one vector; the manner in which the first information indicates M1 matrices; M2 sub-bands out of M sub-bands; M1 sub-bands out of M sub-bands; or, the transmission period of the first information. These are described below.

[0428] 1. The way the first matrix and the first vector are used to determine at least one vector:

[0429] Optionally, the second information may indicate that the first matrix and the first vector are used to determine at least one vector in a manner of mode a1, mode a2, or mode a3. The specific details of mode a1, mode a2, and mode a3 can be found in the descriptions of mode a1, mode a2, and mode a3 in S302 above, and will not be repeated here.

[0430] 2. The first information indicates the M1 matrices in the following way:

[0431] Optionally, the second information may indicate that the first information indicates the M1 matrices in mode b1, mode b2, or mode b3. The specific details of mode b1, mode b2, and mode b3 can be found in the descriptions of mode b1, mode b2, and mode b3 in S302 above, and will not be repeated here.

[0432] 3. M2 sub-bands out of M sub-bands:

[0433] Where M2 is a positive integer less than M and greater than or equal to M1. The M2 subbands include the M1 subbands; or, the M2 subbands may be the range of candidate subbands in method d2 above, which includes the M1 subbands. The first device may obtain (or select or determine) the M1 subbands from the M2 subbands.

[0434] M2 can be 1, or M2 can be greater than 1. When M2 is greater than 1, the M2 subbands can be consecutive, consecutively spaced, or non-consecutive. For example, the M2 subbands may include the 5th, 10th, and 15th subbands. The M1 subbands may include the 5th, 10th, and 15th subbands. Alternatively, the M2 subbands may include the 5th, 10th, and 15th subbands. The M1 subbands may include the 5th and 10th subbands.

[0435] Optionally, the second information may indicate M1 groups of subbands, where each group of subbands in the M1 groups includes one or more subbands from M subbands, and the collection of the M1 groups of subbands is M2 subbands. The fourth subband is any one of the M1 subbands, and the fourth subband is one of the subbands in the group of subbands corresponding to the fourth subband in the M1 groups. For example, the second information may indicate 2 groups of subbands, where the first group of subbands includes subbands 5 to 8, and the second group of subbands includes subbands 13 to 15. The M1 subbands may include one subband from the first group and one subband from the second group; for example, the M1 subbands may include the 7th subband and the 14th subband.

[0436] 4. M1 sub-bands out of M sub-bands: For details on the M1 sub-bands, please refer to the description of the M1 sub-bands in S302, which will not be repeated here.

[0437] The second information can indicate the M1 sub-bands in several ways, such as mode i1, mode i2, or mode i3.

[0438] Method i1: The second information includes the sequence numbers of M1 sub-bands.

[0439] For example, the second information includes serial numbers 5, 10, and 15, indicating that the M1 subbands include the 5th, 10th, and 15th subbands among the M subbands.

[0440] In this way, the first device can accurately determine M1 sub-bands based on the second information. Furthermore, in this method, the second information can directly indicate the M1 sub-bands, so the first device does not need to determine the M1 sub-bands through calculation, thereby reducing the computational complexity of the first device.

[0441] Method i2: When the sequence number difference between adjacent sub-bands in M1 sub-bands is the same, the second information includes the sequence number of the reference sub-band in M1 sub-bands, the sequence number difference between adjacent sub-bands in M1 sub-bands (hereinafter referred to as the first sequence number difference) and M1.

[0442] Optionally, the reference sub-band can be the first sub-band among M1 sub-bands, or it can be the last sub-band among M1 sub-bands.

[0443] For example, the reference sub-band is the first sub-band out of M1 sub-bands. In the second information, the reference sub-band's index is 5, the first index difference is 5, and M1 is 5. In this case, the M1 sub-bands include the 5th, 10th, 15th, 20th, and 25th sub-bands out of the M sub-bands.

[0444] For example, the reference sub-band is the last sub-band among M1 sub-bands. In the second information, the reference sub-band number is 25, the first number difference is 5, and M1 is 5. In this case, the M1 sub-bands include the 5th, 10th, 15th, 20th, and 25th sub-bands among the M sub-bands.

[0445] In this manner, the first device can accurately determine M1 sub-bands based on the second information. Furthermore, in this manner, the second information may include the reference sub-band number, the first number difference, and M1, but may not include the number of each of the M1 sub-bands, thereby reducing the overhead of indicating the M1 sub-bands.

[0446] Method i3: The second information includes the first index, and there is a correspondence between the first index and M1 sub-bands.

[0447] Optionally, at least one index and at least one set of subbands have a corresponding relationship (hereinafter referred to as the second correspondence). The first index belongs to at least one index, and the M1 subbands can be subbands in the subband set corresponding to the first index from at least one set of subbands.

[0448] The second correspondence can be pre-set, such as as specified in an agreement; 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).

[0449] For example, Table 5 shows one possible example of the second correspondence. When the second information includes index 1, the M1 subbands may include the 1st, 11th, 21st, 31st, and 41st subbands out of the M subbands. When the second information includes index 2, the M1 subbands may include the 10th, 20th, 30th, 40th, and 50th subbands out of the M subbands.

[0450] Table 5

[0451] It should be understood that Table 5 is merely an example and is not intended to limit the scope of protection of this application. In practical applications, Table 5 may also have other variations; for example, each subband set may include more or fewer subbands.

[0452] In this manner, the first device can accurately determine the M1 sub-bands based on the second information. Furthermore, in this manner, the second information may include the first index but may not include the sequence number of each of the M1 sub-bands, thereby reducing the overhead of indicating the M1 sub-bands.

[0453] 5. The sending cycle of the first message. For details, please refer to the description of the sending cycle of the first message in S302. It will not be repeated here.

[0454] S309 may precede S302. The order of S309 with at least one of the following steps is not limited: S301, S304, or S305.

[0455] In some implementations, the second information in S309 can be used to implicitly instruct the first device to send at least one piece of information.

[0456] In other implementations, S309 and S304 may be combined. The first instruction information may instruct the first device to send at least one piece of information based on the second information.

[0457] Among some possible approaches, the method shown in Figure 3 may also include S310:

[0458] S310: The first device can send the second information; correspondingly, the second device can receive the second information.

[0459] Optionally, S310 can be used in scenario 2 above.

[0460] The second information may indicate at least one of the following: the manner in which the first matrix and the first vector are used to determine at least one vector; the manner in which the first information indicates M1 matrices; M2 sub-bands out of M sub-bands; M1 sub-bands out of M sub-bands; or, the transmission period of the first information. For details regarding the second information, please refer to the description of the second information in S309, which will not be repeated here.

[0461] S310 may precede S302. The order of S310 with at least one of the following steps is not limited: S301, S307, or S308.

[0462] In some implementations, the second information in S310 can be used to implicitly instruct the first device to send at least one piece of information.

[0463] In other implementations, S310 and S307 may be combined. The first instruction information may instruct the first device to send at least one piece of information based on the second information.

[0464] Optionally, if the second information in S309 or S310 indicates M2 sub-bands out of M sub-bands, the first information may indicate M1 sub-bands out of M sub-bands. The method of indication can refer to the description of "the second information indicates M1 sub-bands out of M sub-bands" in S309, except that the second information is replaced with the first information, and will not be repeated here.

[0465] In some possible ways, the first information also indicates N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to the N vectors corresponding to the first stream, where N is a positive integer. The N1 vectors correspond to the N1 matrices, and the second vector is any one of the N1 vectors, corresponding to a third matrix among the N1 matrices. The third matrix is ​​used to indicate: a recursive relationship (or association or correspondence) between one or more of the N vectors and the second vector; or, the third matrix can be used to determine the one or more vectors; or, the third matrix and the second vector can be used to determine the one or more vectors.

[0466] To make it easier to understand, we will first explain the N vectors.

[0467] N vectors correspond to N time units; for example, N vectors can correspond one-to-one with N time units. Each of the N vectors is a coefficient in one of the N coefficient matrices; or, each of the N vectors has a correspondence (or association) with one of the N coefficient matrices. Each of the N coefficient matrices is the coefficient matrix corresponding to the precoding matrix of one time unit in the first stream of the N time units. The precoding matrix of each time unit in the first stream of the N time units is obtained 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 time unit in 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 time unit in the N time units.

[0468] 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.

[0469] The q-th vector can be the coefficient of the precoding matrix of the first stream in the q-th time unit (hereinafter referred to as the q-th time unit) out of the N time units. Optionally, the larger the value of q, the later the time corresponding to the q-th time unit; the smaller the value of q, the earlier the time corresponding to the q-th time unit.

[0470] For example, the first stream is the j-th stream, and the N coefficient matrices are the coefficient matrices corresponding to the precoding matrix of the j-th stream in the q-th time unit out of N time units. The q-th vector can be a column in 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. For details of this example, please refer to the explanation of Example 1 in S302, except that M is replaced with N, sub-bands are replaced with time units, and k is replaced with q, which will not be repeated here.

[0471] The following explanation uses N vectors to illustrate N1 vectors and N1 matrices.

[0472] 1. N1 vectors:

[0473] As mentioned earlier, N1 vectors belong to N vectors. Optionally, N1 is less than N; or, the N1 vectors are a subset of the N vectors. The q-th vector among these N vectors can be represented as x. 1,q q can be referred to as the index of the vector and / or the index of the time unit, and q takes integer values ​​from 1 to N. The indices of the N1 vectors can be uniformly distributed or non-uniformly distributed. For example, if N is 50 and N1 is 5, the N1 vectors may include: x 1,1 x 1,11 x 1,21 x 1,31 , and x 1,41 For example, if N is 50 and N1 is 5, the N1 vectors can include: x 1,10 x 1,20 x 1,30 x 1,40 , and x 1,50 For example, if N is 45 and N1 is 5, these N1 vectors can include: x 1,5 x 1,14 x 1,23 x 1,32 , and x 1,41 For example, if N is 50 and N1 is 5, these N1 vectors can include: x 1,1 x 1,12 x 1,20 x 1,31 x 1,40 .

[0474] It should be understood that the above examples are merely illustrative and are not intended to limit the scope of protection of this application. For example, N and N1 can take other values; and / or, the N1 vectors can be other vectors.

[0475] 2. N1 matrices:

[0476] As mentioned earlier, the second vector is any one of the N1 vectors, and the second vector corresponds to the third matrix among the N1 matrices. The third matrix is ​​used to indicate the recursive relationship between one or more of the N vectors and the second vector.

[0477] The following explanation uses the third matrix as an example to illustrate the N1 matrices.

[0478] For example, the q-th vector among the N vectors is a column in the coefficient matrix corresponding to the precoding matrix of the j-th stream at the q-th time unit. When the set of the one or more vectors and the second vector (hereinafter referred to as set #2) consists of the 1st to 10th vectors among the N vectors, the 1st vector in set #2 can be the 1st column in the coefficient matrix corresponding to the precoding matrix of the 1-th stream at the 1st time unit; the 2nd vector in set #2 can be the 1st column in the coefficient matrix corresponding to the precoding matrix of the 1-th stream at the 2nd time unit, and so on. The third matrix can indicate the recursive relationship between the 1st to 10th vectors among the N vectors, thereby indicating the recursive relationship between the one or more vectors and the second vector. When set #2 consists of the 11th to 20th vectors out of the N vectors, the first vector in set #2 can be the first column of the coefficient matrix corresponding to the precoding matrix of the first stream in the 11th time unit; the second vector in set #2 can be the first column of the coefficient matrix corresponding to the precoding matrix of the first stream in the 12th time unit, and so on. The third matrix can indicate the recursive relationship between the 11th to 20th vectors out of the N vectors, thereby indicating the recursive relationship between the one or more vectors and the second vector. And so on, without further elaboration.

[0479] In some implementations, the union of the one or more vectors and the first vector is union #2. The third matrix can be used to indicate the recursive relationship (or association or correspondence) between vectors in union #2 corresponding to adjacent time units; the third matrix can be used to indicate the recursive relationship (or association or correspondence) between adjacent vectors in union #2; or, the product of the third matrix and the first vector can be used to determine the vector adjacent to the first vector among the one or more vectors; or, the product of the third matrix and one of the one or more vectors can be used to determine another vector adjacent to that vector among the one or more vectors. Adjacent time units can be time units with adjacent indexes. For example, the first time unit out of N time units and the second time unit out of N time units are adjacent time units. Adjacent vectors can be vectors with adjacent indexes. For example, the first vector out of N vectors and the second vector out of N vectors are adjacent vectors.

[0480] It should be understood that the third matrix may also take other forms, all of which are within the scope of protection of this application. For example, the third matrix may indicate the recursive relationship between vectors in set #2 that are separated by O indices, where O is a positive integer.

[0481] Optionally, the second vector is the l-th vector among N1 vectors, where l is an integer from 1 to N1. The set of one or more vectors and the second vector is N3 vectors, where N3 is a positive integer. The b2-th vector among the N3 vectors is x. 1,a2+b2-1 a2 is a positive integer, and b2 takes integer values ​​from 1 to N3. The third matrix G t,l The following formula (2) can be satisfied; or, the first device can determine the third matrix G according to the following formula (2). t,l G t,l =Y t,l *pinv(X t,l ), formula (2)

[0482] Among them, Y t,l =[x 1,a2+1 ,x 1,a2+2 ,…,x 1,a2+N3-1 ], X t,l =[x 1,a2 ,x 1,a2+1 ,…,x 1,a2+N3-2 ], pinv indicates the pseudo-inverse operation.

[0483] For example, the second vector is the first vector among N1 vectors; the set of one or more vectors and the second vector is the first to tenth vectors among the N vectors, which can be represented as x. 1,1 ,x 1,2 ,…,x 1,10 Y t,1 =[x 1,2 ,x 1,3 ,…,x 1,10 ], X t,1 =[x 1,1 ,x 1,2 ,…,x 1,9 The third matrix G corresponding to the second vector. t,1 =Y t,1 *pinv(X t,1 ).

[0484] For example, the second vector is the second vector out of N1 vectors; the set of one or more vectors and the second vector is the 11th to 20th vectors out of the N vectors, which can be represented as x. 1,11 ,x 1,12 ,…,x 1,20 Yt,2 =[x 1,12 ,x 1,13 ,…,x 1,20 ], X t,2 =[x 1,11 ,x 1,12 ,…,x 1,19 The third matrix G corresponding to the second vector. t,2 =Y t,2 *pinv(X t,2 ).

[0485] 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, X t,l and / or Y t,l The positions of the column vectors in the array can change. For example, X... t,l and / or Y t,l It may include a smaller number of column vectors. Any variations of formula (2) are within the scope of protection of this application.

[0486] In this way, the first device can accurately determine the third matrix according to formula (2), thereby accurately determining the recursive relationship between the one or more vectors and the second vector.

[0487] As previously mentioned, the third matrix and the second vector can be used to determine one or more vectors among the N vectors, thus N1 vectors and N1 matrices can be used to determine the N vectors. The second vector may correspond to a first time unit among the N time units. The second vector may be a coefficient corresponding to the precoding matrix of the first stream in the first time unit; or, the second vector may be used to determine the precoding matrix of the first stream in the first time unit; or, the second vector has a correspondence (or association) with the precoding matrix of the first stream in the first time unit. The one or more vectors may correspond to one or more time units, for example, the one or more vectors may correspond one-to-one with one or more time units. Each of the one or more vectors may be a coefficient corresponding to the precoding matrix of the first stream in one time unit among the one or more time units; or, each of the one or more vectors may be used to determine the precoding matrix of the first stream in one time unit among the one or more time units; or, each of the one or more vectors has a correspondence (or association) with the precoding matrix of the first stream in one time unit among the one or more time units.

[0488] The following example illustrates how a third matrix and a second vector can be used to determine one or more vectors. There are several ways to use a third matrix and a second vector to determine one or more vectors, such as method j1, method j2, or method j3.

[0489] Method j1: The third matrix and the second vector are used to determine one or more vectors whose index is greater than that of the second vector; or, the third matrix and the second vector are used to determine one or more vectors whose index of one or more time units is greater than that of the first time unit corresponding to the second vector.

[0490] Optionally, the second vector can be represented as x 1,q1 q1 is a positive integer. Any one of these vectors can be represented as x. 1,q2 q2 is a positive integer. q2 is greater than q1. 1,q2 =G t,l q2-q1 *x 1,q1 Among them, G t,l G is the third matrix. t,l q2-q1 For G t,l The power of q²-q¹, where l is an integer greater than or equal to 1 and less than or equal to N¹.

[0491] For example, as shown in Figure 5A, the second vector is the first vector x among the N vectors. 1,1 The one or more vectors are the 2nd to 10th vectors among the N vectors, and can be represented as x respectively. 1,2 ,x 1,3 ,…,x 1,10 ;x 1,1 The corresponding third matrix is ​​G t,1 The second vector x among these N vectors. 1,2 =G t,1 *x 1,1 The third vector x among the N vectors 1,3 =G t,1 2 *x 1,1 And so on, without further explanation.

[0492] For example, as shown in Figure 5A, the second vector is the 11th vector x among the N vectors. 1,11 The one or more vectors are the 12th to 20th vectors among the N vectors, and can be represented as x. 1,12 ,x 1,13 ,…,x 1,20 ;x 1,11 The corresponding third matrix is ​​G t,2 The 12th vector x in these N vectors 1,12 =G t,2 *x 1,11 The 13th vector x in these N vectors 1,13 =G t,2 2 *x1,11 And so on, without further explanation.

[0493] Optionally, in method j1, the one or more vectors can be determined according to the third matrix and the second vector in ascending order of the sequence numbers of one or more time units; or, the one or more vectors can be determined according to the third matrix and the second vector in ascending order of the sequence numbers of one or more vectors; or, the second device can determine the one or more vectors according to the third matrix and the second vector in ascending order of the sequence numbers of one or more time units; or, the second device can determine the one or more vectors according to the third matrix and the second vector in ascending order of the sequence numbers of one or more vectors. For example, the second vector is the first vector x among the N vectors. 1,1 The one or more vectors are the 2nd to 10th vectors among the N vectors. The second device can be based on x 1,1 Together with the third matrix, we determine the 2nd to 10th vectors from the N vectors in sequence.

[0494] By means of j1, the second device can accurately determine one or more vectors whose index is greater than that of the second vector based on the third matrix and the second vector.

[0495] Optionally, each pair of matrices and vectors in the N1 matrices and N1 vectors can be used to determine a set of vectors according to method j1, thereby determining N vectors. For example, the N vectors may include: x 1,1 ,x 1,2 ,…,x 1,50 The N1 vectors may include: x 1,1 x 1,11 x 1,21 x 1,31 , and x 1,41 The N1 matrices may include: G t,1 G t,2 G t,3 G t,4 and G t,5 x 1,1 and G t,1 It can be used to determine the 2nd to 10th vectors among the N vectors according to method j1; x 1,11 and G t,2 It can be used to determine the 12th to 20th vectors among the N vectors according to method j1; x 1,21 and G t,3 It can be used to determine the 22nd to 30th vectors among the N vectors according to method j1; x 1,31 and G t,4 It can be used to determine the 32nd to 40th vectors among the N vectors according to method j1; x 1,41 and G t,5This can be used to determine the 42nd to 50th vectors among the N vectors according to method j1. In this way, the second device can accurately determine the N vectors based on the N1 matrices and N1 vectors.

[0496] Method j2: The third matrix and the second vector are used to determine one or more vectors whose index is less than that of the second vector; or, the third matrix and the second vector are used to determine one or more vectors whose index of one or more time units is less than that of the first time unit corresponding to the second vector.

[0497] Optionally, the second vector can be represented as x 1,q1 q1 is a positive integer. Any one of these vectors can be represented as x. 1,q2 q2 is a positive integer. q2 is less than q1. 1,q2 =inv(G t,l ) |q2-q1| *x 1,q1 Among them, G t,l For the third matrix, inv(G) t,l ) is G t,l The inverse matrix, inv(G) t,l ) |q2-q1| for inv(G t,l The |q2-q1| power of ) is where || represents the absolute value operation, and l is an integer greater than or equal to 1 and less than or equal to N1.

[0498] For example, as shown in Figure 5B, the second vector is the 10th vector x among the N vectors. 1,10 The one or more vectors are the 1st to 9th vectors among the N vectors, and can be represented as x respectively. 1,1 ,x 1,2 ,…,x 1,9 ;x 1,10 The corresponding third matrix is ​​G t,1 The 9th vector x in these N vectors 1,9 =inv(G t,1 )*x 1,10 The 8th vector x in these N vectors 1,8 =inv(G t,1 ) 2 *x 1,10 And so on, without further explanation.

[0499] For example, as shown in Figure 5B, the second vector is the 20th vector x among the N vectors. 1,20 The one or more vectors are the 11th to 19th vectors among the N vectors, and can be represented as x respectively. 1,11 ,x 1,12 ,…,x 1,19 ;x1,20 The corresponding third matrix is ​​G t,2 The 19th vector x in these N vectors 1,19 =inv(G t,2 )*x 1,20 The 18th vector x in these N vectors 1,18 =inv(G t,2 ) 2 *x 1,20 And so on, without further explanation.

[0500] Optionally, in method j2, the one or more vectors may be determined according to the third matrix and the second vector in descending order of the sequence numbers of one or more time units; or, the one or more vectors may be determined according to the third matrix and the second vector in descending order of the sequence numbers of one or more vectors; or, the second device may determine the one or more vectors according to the third matrix and the second vector in descending order of the sequence numbers of one or more time units; or, the second device may determine the one or more vectors according to the third matrix and the second vector in descending order of the sequence numbers of one or more vectors. For example, the second vector is the 10th vector x among the N vectors. 1,10 The one or more vectors are the 1st to 9th vectors among the N vectors. The second device can be based on x 1,10 Together with the third matrix, we determine the 9th to 1st vectors from the N vectors in sequence.

[0501] By means of j2, the second device can accurately determine one or more vectors whose index is less than that of the second vector based on the third matrix and the second vector.

[0502] Optionally, each pair of matrices and vectors in the N1 matrices and N1 vectors can be used to determine a set of vectors according to method j2, thereby determining N vectors. For example, the N vectors may include: x 1,1 ,x 1,2 ,…,x 1,50 The N1 vectors may include: x 1,10 x 1,20 x 1,30 x 1,40 , and x 1,50 The N1 matrices may include: G t,1 G t,2 G t,3 G t,4 and G t,5 x 1,10 and G t,1 It can be used to determine the 1st to 9th vectors among the N vectors according to method j2; x 1,20 and G t,2It can be used to determine the 11th to 19th vectors among the N vectors according to method j2; x 1,30 and G t,3 It can be used to determine the 21st to 29th vectors among the N vectors according to method j2; x 1,40 and G t,4 It can be used to determine the 31st to 39th vectors among the N vectors according to method j2; x 1,50 and G t,5 This can be used to determine the 41st to 49th vectors among the N vectors according to method j2. In this way, the second device can accurately determine the N vectors based on the N1 matrices and N1 vectors.

[0503] Method j3: The third matrix and the second vector are used to determine the one or more vectors, wherein the indices of the one or more vectors include indices greater than and less than the second vector; or, the third matrix and the second vector are used to determine the one or more vectors, wherein the indices of the one or more time units corresponding to the one or more vectors include indices greater than and less than the indices of the first time units corresponding to the second vector; or, the one or more vectors may be determined according to the third matrix and the second vector in a recursive order starting from the indices of the first time units.

[0504] Optionally, the second vector can be represented as x 1,q1 q1 is a positive integer. Any one of these vectors can be represented as x. 1,q2 Let q2 be a positive integer. q2 is greater than q1. Given that q2 is greater than q1, x... 1,q2 =G t,l q2-q1 *x 1,q1 When q2 is less than q1, x 1,q2 =inv(G t,l ) |q2-q1| *x 1,q1 Among them, G t,l For the third matrix, inv(G) t,l ) is G t,l The inverse matrix, inv(G) t,l ) |q2-q1| for inv(G t,l The |q2-q1| power of ) is where || represents the absolute value operation, and l is an integer greater than or equal to 1 and less than or equal to N1.

[0505] For example, as shown in Figure 5C, the second vector is the 5th vector x among the N vectors. 1,5 The one or more vectors are the 1st to 4th vectors and the 6th to 9th vectors in the N vectors, which can be represented as x respectively. 1,1 ,x1,2 ,…,x 1,4 ,x 1,6 ,x 1,7 ,…,x 1,9 ;x 1,5 The corresponding third matrix is ​​G t,1 The 6th vector x in these N vectors 1,6 =G t,1 *x 1,5 The 7th vector x in these N vectors 1,7 =G t,1 2 *x 1,5 And so on, without further explanation. The 4th vector x in these N vectors... 1,4 =inv(G t,1 )*x 1,5 The third vector x among the N vectors 1,3 =inv(G t,1 ) 2 *x 1,5 And so on, without further explanation.

[0506] For example, the second vector is the 14th vector x out of these N vectors. 1,14 The one or more vectors are the 10th to 13th vectors and the 15th to 18th vectors in the N vectors, which can be represented as x respectively. 1,10 ,x 1,11 ,…,x 1,13 ,x 1,15 ,x 1,16 ,…,x 1,18 ;x 1,14 The corresponding third matrix is ​​G t,2 The 15th vector x among the N vectors. 1,15 =G t,2 *x 1,14 The 16th vector x in these N vectors 1,16 =G t,2 2 *x 1,14 And so on, without further explanation. The 13th vector x in these N vectors... 1,13 =inv(G t,2 )*x 1,14 The 12th vector x in these N vectors 1,12 =inv(G t,2 ) 2 *x 1,14 And so on, without further explanation.

[0507] Through method j3, the second device can accurately determine one or more vectors with indices greater than and less than the second vector based on the third matrix and the second vector. Furthermore, in this design, the second device can recursively deduce one or more vectors from the second vector in the directions with indices greater than and less than the second vector; that is, the second device can recursively deduce one or more vectors from the first vector in both directions, thereby reducing the spread of quantization errors.

[0508] Optionally, each pair of matrices and vectors in the N1 matrices and N1 vectors can be used to determine a set of vectors according to method j3, thereby determining N vectors. For example, the N vectors may include: x 1,1 ,x 1,2 ,…,x 1,45 The N1 vectors may include: x 1,5 x 1,14 x 1,23 x 1,32 , and x 1,41 The N1 matrices may include: G t,1 G t,2 G t,3 G t,4 and G t,5 x 1,5 and G t,1 This can be used to determine the 1st to 4th vectors and the 6th to 9th vectors among the N vectors according to method j3; x 1,14 and G t,2 This can be used to determine the 10th to 13th vectors and the 15th to 18th vectors among the N vectors according to method j3; x 1,23 and G t,3 This can be used to determine the 19th to 22nd vectors and the 24th to 27th vectors among the N vectors according to method j3; x 1,32 and G t,4 This can be used to determine the 28th to 31st vectors and the 33rd to 36th vectors among the N vectors according to method j3; x 1,41 and G t,5 This can be used to determine the 37th to 40th vectors and the 42nd to 45th vectors among the N vectors according to method j3. In this way, the second device can accurately determine the N vectors based on the N1 matrices and N1 vectors.

[0509] In some implementations, in method j3, the third difference can be greater than the fourth difference. The third difference can be the absolute value of the difference between the index of the second time unit and the index of the third time unit. The second time unit is any one of the one or more time units, and the third time unit is any one of the N1 time units excluding the first time unit. The fourth difference is the absolute value of the difference between the index of the second time unit and the index of the first time unit. Alternatively, any vector other than the N1 vectors can be determined based on the vector with the smallest absolute difference between its index and the N1 vectors. For example, the N vectors may include: x 1,1 ,x 1,2 ,…,x 1,45 The N1 vectors may include: x 1,5 x 1,14 x 1,23 x 1,32 , and x 1,41 x 1,8 With x in the N1 vectors 1,5 The absolute value of the difference between the indices is the smallest, x 1,8 Based on x 1,5 This is confirmed. Through this implementation, the first and second devices can accurately determine which of the N1 vectors each vector can be used to determine which of the N vectors.

[0510] Optionally, for any vector other than the N1 vectors among the N vectors, if the absolute value of the difference between the index of the vector and multiple vectors among the N1 vectors is the smallest, the vector used to determine the vector can be determined from the multiple vectors according to condition #2; or, the second device can select the vector used to determine the vector from the multiple vectors according to condition #2. Condition #2 may include, but is not limited to, at least one of the following: the vector used to determine the vector is the vector with the smallest index among the multiple vectors; or, the vector used to determine the vector is the vector with the largest index among the multiple vectors. The following explanation uses the example where condition #2 includes: the vector used to determine the vector is the vector with the smallest index among the multiple vectors. For example, the N vectors may include: x 1,1 ,x 1,2 ,…,x 1,50 The N1 vectors may include: x 1,5 x 1,14 x 1,23 x 1,32 , and x 1,41 x 1,10 With x in the N1 vectors 1,5 and x 1,15 The difference between the serial numbers is the smallest, x 1,5 The sequence number is less than x 1,15 The serial number, x1,10 Based on x 1,5 Sure.

[0511] In some possible ways, the way the third matrix and the second vector are used to determine one or more vectors can be predefined, such as by a protocol. For example, the way the third matrix and the second vector are used to determine one or more vectors can be predefined as mode j1, mode j2, or mode j3.

[0512] In some other possible ways, the third matrix and the second vector are used to determine one or more vectors in a manner that can be indicated by the second device to the first device, as will be described in detail in S311 below, and will not be elaborated here.

[0513] In some other possible ways, the third matrix and the second vector are used to determine one or more vectors, which may be indicated by the first device to the second device. The details will be described in S312 below and will not be elaborated here.

[0514] Optionally, M1 vectors, M1 matrices, N1 vectors, and N1 matrices 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 in the q-th time unit based on M1 vectors, M1 matrices, N1 vectors, and N1 matrices. 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.

[0515] In some examples, as shown in Figure 6, the first vector in M1 vectors and the second vector in N1 vectors are both x. 1,1 x k,q and x 1,1 The formula can be satisfied: x k,q =G t,l q-1 *G f,i k-1 *x 1,1 Among them, G t,l G is the third matrix in a set of N1 matrices. t,l q-1 For G t,l q-1; G f,i G is the first matrix among M1 matrices. f,i k-1 For G f,i The (k-1)th power. For example, x3,3 =G t,l 2 *G f,i 2 *x 1,1 .

[0516] In other examples, the first vector in M1 vectors and the second vector in N1 vectors are both x. M,N x k,q and x M,N The formula can be satisfied: x k,q =inv(G t,l ) N-q *inv(G f,i ) M-k *x M,N Among them, inv(G t,l ) N-q for inv(G t,l ) to the power of Nq, inv(G t,l ) is G t,l inverse matrix; inv(G f,i ) M-k for inv(G f,i ) to the power of Mk, inv(G f,i ) is G f,i The inverse matrix.

[0517] 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 M1 vectors, M1 matrices, N1 vectors, and N1 matrices.

[0518] 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.

[0519] As mentioned earlier, the first information can indicate N1 matrices, and there can be multiple ways of indicating them, such as method k1, method k2, or method k3.

[0520] Method k1: The first information may include N1 matrices.

[0521] For example, the N1 matrices include: G t,1 G t,2 G t,3 G t,4 and G t,5 The first piece of information includes: G t,1 Gt,2 G t,3 G t,4 and G t,5 .

[0522] In this way, the second device can accurately determine N1 matrices based on the first information. Furthermore, in this method, the first information can directly indicate the N1 matrices, so the second device does not need to calculate to determine the N1 matrices, thereby reducing the computational complexity of the second device.

[0523] Method k2: The first information may include the fourth matrix among N1 matrices, and the differences between the fourth matrix and the matrices other than the fourth matrix among the N1 matrices.

[0524] Optionally, the fourth matrix can be the first matrix of the N1 matrices, or the last matrix of the N1 matrices, or the matrix located in the middle of the N1 matrices.

[0525] For example, the N1 matrices include: G t,1 G t,2 G t,3 G t,4 and G t,5 The first piece of information may include: G t,1 G t,2 -G t,1 G t,3 -G t,1 G t,4 -G t,1 and G t,5 -G t,1 .

[0526] For example, the N1 matrices include: G t,1 G t,2 G t,3 G t,4 and G t,5 The first piece of information may include: G t,5 G t,1 -G t,5 G t,2 -G t,5 G t,3 -G t,5 and G t,4 -G t,5 .

[0527] For example, the N1 matrices include: G t,1 G t,2 G t,3 G t,4 and G t,5 The first piece of information may include: G t,3 Gt,1 -G t,3 G t,2 -G t,3 G t,4 -G t,3 and G t,5 -G t,3 .

[0528] The position of the fourth matrix among the N1 matrices (or, which of the N1 matrices the fourth matrix is) can be predetermined, for example, as specified by a protocol; or it can be determined by the first device; or it can be notified to the first device by another device (e.g., core network equipment or the second device). If the first device determines the position of the fourth matrix among the N1 matrices, the first device can indicate the position of the fourth matrix among the N1 matrices to the second device, for example, the first device can indicate the sequence number of the fourth matrix to the second device.

[0529] In this method, the first information may include the fourth matrix out of N1 matrices, and the differences between the fourth matrix and the other matrices in the N1 matrices. Compared to including N1 matrices, this method can improve the accuracy of the transmitted information, i.e., improve the accuracy of the transmitted N1 matrices, while using the same number of transmitted bits.

[0530] Method k3: The first information may include information that corresponds to the N1 matrices.

[0531] The following explanation uses the third matrix as an example to illustrate the information in the first information, which includes information that corresponds to N1 matrices.

[0532] In some implementations, the first information may include Λ2 and Ψ2. Here, Λ2 is a diagonal matrix; Ψ2 is the matrix obtained by eigenvalue decomposition of the third matrix, and Ψ2 has the same number of rows and columns as the third matrix. The third matrix has the same number of rows and columns. Λ2, Ψ2, and the third matrix satisfy the following formula: G t,l =Ψ2*Λ2*Ψ2 H G t,l This is the third matrix. Ψ2 H It can be the conjugate transpose of Ψ2. In this implementation, the second device can accurately determine the third matrix based on Λ2 and Ψ2. Furthermore, in this implementation, the second device can determine the third matrix based on Λ2, Ψ2, and Ψ2. H It computes one or more vectors out of N vectors in parallel. For example, in the second vector x... 1,1 The third matrix is ​​G t,l In this case, the third vector among the N vectors can be x. 1,1 *G t,l 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,l 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 one or more vectors 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 cost of the second device.

[0533] In other implementations, the first information may include: Ψ2 H And the product of the second 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, in the second vector x 1,1 The third matrix is ​​G t,l And G t,l =Ψ2*Λ2*Ψ2 H In this case, the first information may include: Ψ2 H *x 1,1 Λ2 and Ψ2. In this implementation, the second device can accurately determine the third matrix based on Λ2 and Ψ2. Furthermore, in this implementation, the second device can determine the third matrix based on Λ2, Ψ2, and Ψ2. H It computes one or more vectors out of N vectors in parallel. For example, in the second vector x... 1,1 The third matrix is ​​G t,l In this case, the third vector among the N vectors can be x. 1,1 *G t,l 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,l 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 one or more vectors 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 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 one or more vectors from N vectors, thereby further saving computation time and resources and reducing the amount of computation.

[0534] Optionally, method k3 can be combined with method k1 or method k2. For example, when method k3 is combined with method k1, each of the N1 matrices can be indicated by method k3 in the first information. Also, for example, when method k2 is combined with method k1, the fourth matrix can be indicated by method k3 in the first information.

[0535] In some possible ways, the way in which the first information indicates N1 matrices can be pre-defined, such as as specified by a protocol. For example, the way in which the first information indicates N1 matrices can be pre-defined is mode k1, mode k2, or mode k3.

[0536] In some other possible ways, the first information indicates N1 matrices, which may be indicated by the second device to the first device. The details will be described in S311 below and will not be elaborated here.

[0537] Among other possible methods, the first information indicating N1 matrices can be indicated by the first device to the second device. The details will be described in S312 below and will not be elaborated here.

[0538] As previously mentioned, the first information may indicate N1 vectors, which correspond to N1 time units. These N1 vectors include the coefficients of the precoding matrix corresponding to each of the N1 time units in the first stream. There are multiple ways to obtain these N1 time units, such as one of methods l1 to l5.

[0539] Method l1: N1 time units can be indicated by the second device to the first device. The details will be described in S311 below and will not be elaborated here.

[0540] Method l2: The N1 time units can be determined by the first device. Optionally, in method c2, the first device can indicate the N1 time units to the second device, the details of which will be described in S312 below and will not be elaborated here.

[0541] Method 13: The range of candidate time units for N1 time units is preset, for example, as specified in the protocol. The range of candidate time units includes N1 time units. In this way, the first device can obtain (or select or determine) N1 time units from the range of candidate time units.

[0542] For example, the candidate time unit range includes: the 5th time unit, the 10th time unit, and the 15th time unit. The N1 time units may include: the 5th time unit, the 10th time unit, and the 15th time unit.

[0543] For example, the candidate time unit range includes: the 5th time unit, the 10th time unit, and the 15th time unit. The N1 time units may include: the 5th time unit and the 10th time unit.

[0544] Using method l3, the first device can accurately determine N1 time units. Furthermore, in this method, the first device does not need to obtain the candidate time unit range from other devices, thereby reducing signaling overhead.

[0545] Method 14: The range of candidate time units for N1 time units can be indicated by the second device to the first device. The specific details will be described in S311 below and will not be elaborated here. In this way, the first device can obtain (or select or determine) N1 time units from the range of candidate time units. The method of obtaining them can be referred to Method 13 and will not be repeated here.

[0546] Method 15: The range of candidate time units for N1 time units can be determined by the first device. In this way, the first device can obtain (or select or determine) N1 time units from the range of candidate time units. The method of obtaining them can be referred to Method 13, and will not be repeated here.

[0547] Optionally, in mode 15, the first device may indicate to the second device a range of candidate time units of N1 time units, the details of which will be described in S312 below and will not be elaborated here.

[0548] Optionally, in the method shown in Figure 3, the first information also indicates the N1 time units corresponding to the N1 vectors. In this way, the second device can accurately determine which time units correspond to the N1 vectors.

[0549] Optionally, the value of N1 is negatively correlated with the stability of the first-order flow; or, at least one flow includes flow #1 and flow #2, where the stability of flow #1 is higher than that of flow #2, and the value of N1 corresponding to flow #1 can be less than or equal to the value of N1 corresponding to flow #2. For example, at least one flow includes flow #1 and flow #2. Flow #1 corresponds to information #1 in at least one piece of information; flow #2 corresponds to information #2 in at least one piece of information. The stability of flow #1 is higher than that of flow #2. The N1 vectors and N1 matrices indicated by information #1 may include: 5 vectors and 5 matrices; the N1 vectors and N1 matrices indicated by information #2 may include: 10 vectors and 10 matrices. In this way, for a flow with high stability, the first device can report the coefficients corresponding to the precoding matrix of a smaller number of time units, thereby reducing the overhead of the feedback precoding matrix; for a flow with low stability, the first device can report the coefficients corresponding to the precoding matrix of a larger number of time units, thereby improving the accuracy of the feedback precoding matrix.

[0550] Optionally, the first information in "the first information also indicates the N1 vectors and N1 matrices corresponding to the first stream" 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 sending order of the fourth information and the first information is not limited.

[0551] Optionally, the first reference signal in "the precoding matrix of each time unit in the first stream is obtained 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.

[0552] Among some possible approaches, the method shown in Figure 3 may also include S311:

[0553] S311: The second device can send third information; correspondingly, the first device can receive the third information.

[0554] Optionally, S311 can be used in scenario 1 above.

[0555] The third information may indicate parameters for some or all of the flows in at least one flow. In some examples, the third information may indicate parameters for each flow in that part or all of the flow, respectively. Optionally, where the third information may indicate parameters for each flow in that part or all of the flow, the parameters of the different flows may be independent. For example, if at least one flow includes flow #1 and flow #2, the third information may indicate parameters for flow #1 and flow #2, respectively. In other examples, the third information may indicate one or more sets of parameters. Each set of parameters in this set or sets may be parameters for one or more flows in that part or all of the flow. For example, if at least one flow includes flows #1 to #3, the third information may indicate: a third set of parameters and a fourth set of parameters. The third set of parameters may be parameters for flow #1, and the fourth set of parameters may be parameters for flows #2 and #3.

[0556] Optionally, the streams may include stream #1 and stream #2, and the parameters of stream #1 and stream #2 may be different. In this way, the second device can configure different parameters for the first device for different streams, thereby enabling flexible management of the feedback of the precoding matrix for different streams.

[0557] As mentioned earlier, the first flow is any one of at least one flows. The following explanation uses the example of the third information indicating the parameters of the first flow to illustrate this.

[0558] The third information indicates at least one of the following: the way the third matrix and the second vector are used to determine one or more vectors; the way the first information indicates the N1 matrices; the N2 time units out of the N time units; the N1 time units out of the N time units; the transmission period of the first information; or, the time range to which the N time units belong. These are described below.

[0559] 1. The way the third matrix and the second vector are used to determine one or more vectors:

[0560] Optionally, the third information may indicate that the third matrix and the second vector are used to determine one or more vectors in a manner of j1, j2, or j3. The specific details of j1, j2, and j3 can be found in the descriptions of j1, j2, and j3 in section S302 above, and will not be repeated here.

[0561] 2. The method of indicating N1 matrices with the first information:

[0562] Optionally, the third information indicates the first information indicating N1 matrices in a manner that is either method k1, method k2, or method k3. The specific details of method k1, method k2, and method k3 can be found in the descriptions of method k1, method k2, and method k3 in S302 above, and will not be repeated here.

[0563] 3. N² time units out of N time units:

[0564] Wherein, N2 is a positive integer less than N and greater than or equal to N1. The N2 time units include the N1 time units; or, the N2 time units may be the range of candidate time units in the above method m2, the range of candidate time units including the N1 time units. The first device may obtain (or select or determine) the N1 time units from the N2 time units.

[0565] N2 can be 1, or N2 can be greater than 1. When N2 is greater than 1, the N2 time units can be consecutive, consecutively spaced, or non-consecutive. For example, the N2 time units may include the 5th time unit, the 10th time unit, and the 15th time unit. The N1 time units may include the 5th time unit, the 10th time unit, and the 15th time unit. Alternatively, the N2 time units may include the 5th time unit, the 10th time unit, and the 15th time unit. The N1 time units may include the 5th time unit and the 10th time unit.

[0566] Optionally, the third information may indicate N1 groups of time units, each group comprising one or more time units from N time units, and the collection of N1 groups of time units is N2 time units. The fourth time unit is any one of the N1 time units, and the fourth time unit is a time unit within the group of time units corresponding to the fourth time unit in the N1 groups. For example, the third information may indicate two groups of time units: the first group includes time units 5 to 8, and the second group includes time units 13 to 15. The N1 time units may include one time unit from the first group and one time unit from the second group; for example, the N1 time units may include the 7th time unit and the 14th time unit.

[0567] 4. N1 time units out of N time units:

[0568] As previously mentioned, the first information may indicate N1 vectors, which may correspond to N1 time units. The N1 vectors include the coefficients of the precoding matrix corresponding to each time unit of the first stream in the N1 time units.

[0569] The second information can indicate N1 time units in several ways, such as mode m1, mode m2, or mode m3.

[0570] Method m1: The third information includes the sequence numbers of N1 time units.

[0571] For example, the third information includes: sequence numbers 5, 10, and 15, indicating that the N1 time units include: the 5th, 10th, and 15th time units out of the N time units.

[0572] In this way, the first device can accurately determine N1 time units based on the third information. Furthermore, in this method, the third information can directly indicate the N1 time units, so the first device does not need to calculate to determine the N1 time units, thereby reducing the computational complexity of the first device.

[0573] Method m2: When the sequence number difference between adjacent time units in N1 time units is the same, the third information includes the sequence number of the reference time unit in N1 time units, the sequence number difference between adjacent time units in N1 time units (hereinafter referred to as the second sequence number difference), and N1.

[0574] The reference time unit can be the first time unit among N1 time units, or it can be the last time unit among N1 time units.

[0575] For example, the reference time unit is the first time unit out of N1 time units. In the third information, the reference time unit number is 5, the second number difference is 5, and N1 is 5. In this case, the N1 time units include the 5th, 10th, 15th, 20th, and 25th time units out of the N time units.

[0576] For example, the reference time unit is the last time unit out of N1 time units. In the third information, the reference time unit number is 25, the second number difference is 5, and N1 is 5. In this case, the N1 time units include the 5th, 10th, 15th, 20th, and 25th time units out of the N time units.

[0577] In this manner, the first device can accurately determine N1 time units based on the third information. Furthermore, in this manner, the third information may include the sequence number of the reference time unit, the second sequence number difference, and N1, but may not include the sequence number of each of the N1 time units, thereby reducing the overhead of indicating the N1 time units.

[0578] Method m3: The third information includes the second index, which has a correspondence with N1 time units.

[0579] Optionally, one or more indices and one or more time unit sets have a corresponding relationship (hereinafter referred to as the third correspondence). The second index belongs to the one or more indices, and the N1 time units can be time units in the time unit set corresponding to the second index from the one or more time unit sets.

[0580] The third correspondence can be pre-set, such as as specified in an agreement; 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).

[0581] For example, Table 6 shows one possible example of the third correspondence. When the third information includes index 1, the N1 time units may include the 1st, 11th, 21st, 31st, and 41st time units out of the N time units. When the third information includes index 2, the N1 time units may include the 10th, 20th, 30th, 40th, and 50th time units out of the N time units.

[0582] Table 6

[0583] It should be understood that Table 6 is merely an example and is not intended to limit the scope of protection of this application. In practical applications, Table 6 may also have other variations; for example, each set of time units may include more or fewer time units.

[0584] In this manner, the first device can accurately determine N1 time units based on the third information. Furthermore, in this method, the third information may include a second index but may not include the sequence number of each of the N1 time units, thereby reducing the overhead of indicating the N1 time units.

[0585] 5. The sending cycle of the first message. For details, please refer to the description of the sending cycle of the first message in S302. It will not be repeated here.

[0586] 6. Time range to which N time units belong: Optional, the time range to which N time units belong can be replaced with one of the following: N time units, the duration of N time units, or a value of N.

[0587] Optionally, the length of the time range to which the N time units belong is positively correlated with the stability of the first-order flow, or at least one flow includes flow #1 and flow #2. Flow #1 corresponds to information #1 in at least one piece of information; flow #2 corresponds to information #2 in at least one piece of information. The stability of flow #1 is higher than that of flow #2. The length of the time range to which the N time units corresponding to information #1 belong can be greater than or equal to the length of the time range to which the N time units corresponding to information #2 belong. For example, the length of the time range to which the N time units corresponding to information #1 belong is 50 time slots; the length of the time range to which the N time units corresponding to information #2 belong is 20 time slots. Thus, for a flow with high stability, the first device can predict and report the coefficients corresponding to the precoding matrix of the subband over a longer time range; for a flow with low stability, the first device can report the coefficients corresponding to the precoding matrix of the subband over a shorter time range.

[0588] S311 can precede S302. The order of S311 and S301 is not limited in this application. The order of S311 and S309 is not limited in this application. The second and third information can be carried in the same message or in different messages.

[0589] In some implementations, the third information in S311 can be used to implicitly instruct the first device to send at least one piece of information.

[0590] In other implementations, S311 and S304 may be combined. The first instruction information may instruct the first device to send at least one piece of information based on the third information.

[0591] Among some possible approaches, the method shown in Figure 3 may also include S312:

[0592] S312: The first device can send the third information; correspondingly, the second device can receive the third information.

[0593] Optionally, S312 can be used in scenario 2 above.

[0594] The third information indicates at least one of the following: the way the third matrix and the second vector are used to determine one or more vectors; the way the first information indicates the N1 matrices; N2 time units out of N time units; N1 time units out of N time units; the transmission period of the first information; or, the time range to which the N time units belong. For details on the third information, please refer to the description of the third information in S311, which will not be repeated here.

[0595] S312 may precede S302. The order of S312 and S301 is not limited in this application. The order of S312 and S310 is not limited in this application. The second and third information may be carried in the same message or in different messages.

[0596] In some implementations, the third information in S312 can be used to implicitly instruct the first device to send at least one piece of information.

[0597] In other implementations, S312 and S307 may be combined. The first instruction information may instruct the first device to send at least one piece of information based on the third information.

[0598] Optionally, if the third information in S311 or S312 indicates N2 time units out of N time units, the first information may indicate N1 time units out of N time units. The method of indication can refer to the description of "the third information indicates N1 time units out of N time units" in S311, except that the third information is replaced with the first information, and will not be repeated here.

[0599] 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.

[0600] As shown in Figure 7, the method includes:

[0601] S701: The second device sends a first reference signal; correspondingly, the first device receives the first reference signal.

[0602] For details on S701, please refer to S301; further details will not be provided here.

[0603] S702: The first device sends at least one piece of information; correspondingly, the second device receives at least one piece of information.

[0604] In some examples, in scenario 1 above, at least one piece of information may be PMI, or at least one piece of information may be CSI including PMI.

[0605] In other examples, in scenario 2 above, at least one piece of information may be TPMI.

[0606] At least one piece of information may correspond to at least one stream; for example, at least one piece of information may correspond one-to-one with at least one stream.

[0607] The first piece of information can be any one of the at least one pieces of information. The following explanation will use the first piece of information as an example to illustrate at least one piece of information.

[0608] The first information corresponds to a first stream in at least one stream. The first information may indicate N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to the N vectors corresponding to the first stream, where N is a positive integer. The N1 vectors correspond to the N1 matrices, and the second vector is any one of the N1 vectors. The second vector corresponds to a third matrix among the N1 matrices. The third matrix is ​​used to indicate: a recursive relationship (or association or correspondence) between one or more of the N vectors and the second vector; or, the third matrix can be used to determine the one or more vectors; or, the third matrix and the second vector can be used to determine the one or more vectors.

[0609] The specific contents of the N1 vectors and N1 matrices can be found in the explanation of the N1 vectors and N1 matrices in the method shown in Figure 3, and will not be repeated here. The first information can indicate the specific contents of the N1 vectors and N1 matrices, and can be found in the explanation of "the first information also indicates the N1 vectors and N1 matrices" in the method shown in Figure 3, and will not be repeated here.

[0610] Using this method, a first device can send at least one piece of information, which corresponds to at least one stream. The first piece of information can be any one of the at least one pieces of information, and it corresponds to a first stream within the at least one stream. The first piece of information can indicate a subset of N vectors (i.e., N1 vectors), and a recursive relationship between each of the N1 vectors and the other vectors in the N vectors. Thus, a second device can accurately determine the N vectors based on the N1 vectors 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.

[0611] 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 of coefficients corresponding to the precoding matrix in each time unit increases with the number of antenna ports. In this method, the first device can transmit only the coefficients corresponding to the precoding matrix of a portion of the N time units (i.e., N1 time units), without transmitting the coefficients corresponding to the precoding matrix of each time unit, thereby significantly reducing the overhead of the feedback precoding matrix.

[0612] Alternatively, since the first device may not send each of the N vectors, the method can improve the accuracy of the indicated N1 vectors and / or N1 matrices without changing the overhead of the feedback precoding matrix, thereby improving the accuracy of the N vectors recovered by the second device.

[0613] Among some possible approaches, the method shown in Figure 7 also includes:

[0614] S703: The second device sends a first signal; correspondingly, the first device receives the first signal.

[0615] In some examples, such as Scenario 1 above, the first signal may be a downlink signal.

[0616] In other examples, such as scenario 2 above, the first information may be an uplink signal.

[0617] The first signal is transmitted based on a 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 N time units; or, the second device may determine the first precoding matrix based on the precoding matrices of some or all of the N time units.

[0618] 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.

[0619] Among some possible approaches, the method shown in Figure 7 also includes:

[0620] 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.

[0621] For details on S704, please refer to S304; further details will not be provided here.

[0622] 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.

[0623] In some implementations, the first indication information in S704 can be replaced with second indication information. The second 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 with at least one of the following: a method of precoding matrix feedback, a method of PMI feedback, a method of TPMI feedback, a method of compressed CSI, a method of compressed precoding matrix, a method of compressed PMI, or a method of compressed TPMI.

[0624] 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 Method 4 (or Type 4). The specific details of Method 1 and Method 2 can be found in the descriptions of Method 1 and Method 2 in S304, and will not be repeated here. When the CSI feedback method is Method 4, the precoding matrix can be indicated by N1 vectors and N1 matrices; or, when the CSI feedback method is Method 4, the precoding matrix can be indicated by a subset of the N vectors and the recursive relationship between different vectors in the N vectors; or, when the CSI feedback method is Method 4, the precoding matrix (or CSI, PMI, or TPMI) can be predicted based on DMD. Optionally, Method 4 differs from Method 1 and Method 2. Method 4 may also have other names, as long as they have the same function, they are all within the scope of protection of this application.

[0625] The method for determining the second instruction information can be found in the description of the method for determining the first instruction information in S304, and will not be repeated here.

[0626] After receiving the second instruction information, the first device can feed back a precoding matrix according to the second instruction information. For details, please refer to the description 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. The only difference is that the first instruction information is replaced with the second instruction information, and the new method is replaced with method 4. It will not be described again.

[0627] Optionally, the method shown in Figure 7 further includes S705:

[0628] S705: The first device sends first capability information; correspondingly, the second device receives the first capability information. The first capability information indicates whether the first device possesses a first capability.

[0629] For details on S705, please refer to S305; further details will not be provided here.

[0630] In some other possible embodiments, the method shown in Figure 7 may also include S706:

[0631] 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.

[0632] For details on S706, please refer to S306; further details will not be provided here.

[0633] 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.

[0634] Among some possible approaches, the method shown in Figure 7 may also include S707:

[0635] 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.

[0636] For details on S707, please refer to S307; further details will not be provided here.

[0637] 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 can 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 can process the first information according to the new method; for example, it can determine M vectors based on the first information. Furthermore, in this manner, the first device can indicate the CSI feedback method to the second device, allowing the first device to flexibly manage the CSI feedback method.

[0638] 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.

[0639] In some implementations, the first instruction information in S707 can be replaced with the second instruction information. The specific content of the second instruction information can be found in the description of the second instruction information in S704, and will not be repeated here.

[0640] After receiving the second instruction information, the second device can send a signal according to the first instruction information. For details, please refer to the description of "after receiving the first instruction information, the second device can send a signal according to the first instruction information" in the method shown in Figure 3. The only difference is that the first instruction information is replaced with the second instruction information, and the new method is replaced with method 4. It will not be described again.

[0641] Optionally, the method shown in Figure 7 may also include S708:

[0642] S708: The second device can send second capability information; correspondingly, the first device can receive the second capability information. The second capability information can indicate whether the second device has the first capability.

[0643] For details on S708, please refer to S308; further details will not be provided here.

[0644] Among some possible approaches, the method shown in Figure 7 may also include S709:

[0645] S709: The second device can send third information; correspondingly, the first device can receive the third information.

[0646] The third information indicates at least one of the following: the way the third matrix and the second vector are used to determine one or more vectors; the way the first information indicates the N1 matrices; the N1 time units in the N time units; the transmission period of the first information; or, the time range to which the N time units belong.

[0647] For details on S709, please refer to S311; further details will not be provided here.

[0648] Among some possible approaches, the method shown in Figure 7 may also include S712:

[0649] S710: The first device can send the third information; correspondingly, the second device can receive the third information.

[0650] For details on S710, please refer to S312, which will not be repeated here.

[0651] 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.

[0652] As shown in Figure 8, the method includes:

[0653] S801: The terminal sends first capability information to the access network device. The first capability information can indicate whether the terminal has a first capability.

[0654] For details on S801, please refer to S305 or S705, and will not be repeated here.

[0655] 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.

[0656] For details on S802, please refer to S304 or S704, and will not be repeated here.

[0657] Steps S801 to S802 are optional. The order of S801 and S802 is not limited.

[0658] S803: The access network device sends the second information to the terminal.

[0659] The second information may indicate at least one of the following: the manner in which the first matrix and the first vector are used to determine at least one vector; the manner in which the first information indicates M1 matrices; M1 subbands out of M subbands; or, the transmission period of the first information.

[0660] For details on S803, please refer to S309, which will not be repeated here.

[0661] S804: Access network equipment sends third-party information to the terminal.

[0662] The third information indicates at least one of the following: the way the third matrix and the second vector are used to determine one or more vectors; the way the first information indicates the N1 matrices; the N1 time units in the N time units; the transmission period of the first information; or, the time range to which the N time units belong.

[0663] For details on S804, please refer to S311 or S709; further details will not be provided here.

[0664] Steps S803 to S804 are optional. The order of S803 and S804 is not limited. The order of S803 to S804 and S801 to S802 is not limited. The order of S803 to S804 and S805 is not limited.

[0665] The second and third pieces of information can be carried in the same message or in different messages.

[0666] S805: Access network equipment sends CSI-RS to the terminal.

[0667] For details on S805, please refer to S301 or S701, and will not be repeated here.

[0668] S806: The terminal sends at least one piece of information to the access network device.

[0669] Optionally, at least one piece of information may be PMI, or at least one piece of information may be CSI including PMI.

[0670] S807: The access network device sends the first signal to the terminal.

[0671] In some possible approaches, the first information can be any of at least one piece of information. The first information may indicate M1 vectors and M1 matrices corresponding to the first stream. The specific content of S806 to S807 can be found in S302 to S303, and will not be repeated here. Optionally, in this approach, the first information may also indicate N1 vectors and N1 matrices corresponding to the first stream. The specific content can be found in the explanation of "the first information also indicates N1 vectors and N1 matrices corresponding to the first stream" in the method shown in Figure 3, and will not be repeated here.

[0672] In some other possible ways, the first information is any one of at least one pieces of information. The first information may indicate the N1 vectors and N1 matrices corresponding to the first stream. The specific contents of S806 to S807 can be found in S702 to S703, and will not be repeated here.

[0673] In some implementations, in S806, the first information may also indicate a first basis vector. For example, the first information may indicate the first basis vector corresponding to each of the first to J streams.

[0674] Optionally, in S807, the first signal can be a downlink signal, for example, the first signal can be PDSCH.

[0675] Optionally, S807 is an optional step.

[0676] 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.

[0677] As shown in Figure 9, the method includes:

[0678] S901: The terminal sends second capability information to the access network device. The second capability information can indicate whether the terminal has the first capability.

[0679] For details on S901, please refer to S308 or S708, and will not be repeated here.

[0680] 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.

[0681] For details on S902, please refer to S307 or S707, and will not be repeated here.

[0682] Steps S901 to S902 are optional. The order of S901 and S902 is not limited.

[0683] S903: The access network device sends the second information to the terminal.

[0684] The second information may indicate at least one of the following: the manner in which the first matrix and the first vector are used to determine at least one vector; the manner in which the first information indicates M1 matrices; M1 subbands out of M subbands; or, the transmission period of the first information.

[0685] For details on S903, please refer to S310; further details will not be provided here.

[0686] S904: Access network equipment sends third-party information to the terminal.

[0687] The third information indicates at least one of the following: the way the third matrix and the second vector are used to determine one or more vectors; the way the first information indicates the N1 matrices; the N1 time units in the N time units; the transmission period of the first information; or, the time range to which the N time units belong.

[0688] For details on S904, please refer to S312 or S710, and will not be repeated here.

[0689] Steps S903 to S904 are optional. The order of S903 and S904 is not limited. The order of S903 to S904 and S901 to S902 is not limited. The order of S903 to S904 and S905 is not limited.

[0690] The second and third pieces of information can be carried in the same message or in different messages.

[0691] S905: The terminal sends SRS to the access network equipment.

[0692] For details on S905, please refer to S301 or S701, and will not be repeated here.

[0693] S906: The access network device sends at least one piece of information to the terminal.

[0694] Optionally, at least one piece of information may be TPMI.

[0695] S907: The terminal sends the first signal to the access network equipment.

[0696] In some possible approaches, the first information can be any of at least one piece of information. The first information may indicate M1 vectors and M1 matrices corresponding to the first stream. The specific content of S906 to S907 can be found in S302 to S303, and will not be repeated here. Optionally, in this approach, the first information may also indicate N1 vectors and N1 matrices corresponding to the first stream. The specific content can be found in the explanation of "the first information also indicates N1 vectors and N1 matrices corresponding to the first stream" in the method shown in Figure 3, and will not be repeated here.

[0697] In some other possible ways, the first information is any one of at least one pieces of information. The first information may indicate the N1 vectors and N1 matrices corresponding to the first stream. For details of S906 to S907, please refer to S702 to S703, which will not be repeated here.

[0698] In some implementations, in S906, the first information may also indicate a first basis vector. For example, the first information may indicate the first basis vector corresponding to each of the first to J streams.

[0699] Optionally, in S907, the first signal can be an uplink signal, for example, the first signal can be PUSCH.

[0700] Optionally, S907 is an optional step.

[0701] 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.

[0702] 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.

[0703] 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.

[0704] 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.

[0705] 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.

[0706] 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.

[0707] 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.

[0708] Processing unit 1002 is configured to: receive a first reference signal through interface unit 1001; and send at least one piece of information through interface unit 1001; wherein the at least one piece of information corresponds to at least one stream, the first piece of information is any one of the at least one pieces of information, the first piece of information corresponds to the first stream in the at least one stream, the first piece of information indicates M1 vectors and M1 matrices corresponding to the first stream, M1 is a positive integer, the M1 vectors belong to M vectors corresponding to the first stream, M is a positive integer, the M vectors correspond to M subbands, each of the M vectors is a coefficient in the first coefficient matrix corresponding to one of the subbands in the M subbands, the first coefficient matrix is ​​a coefficient matrix corresponding to the precoding matrix of the first stream, the first stream precoding matrix is ​​determined based on the precoding matrices of the M subbands, the precoding matrices of the M subbands are obtained based on the first reference signal, the M1 vectors correspond to M1 matrices, the first vector is any one of the M1 vectors, the first vector corresponds to the first matrix in the M1 matrices, and the first matrix is ​​used to indicate the recursive relationship between at least one vector in the M vectors and the first vector.

[0709] In some possible ways, the processing unit 1002 is also configured to: receive or send second information through the interface unit 1001, the second information indicating at least one of the following: M1 subbands out of M subbands; wherein each of the M1 vectors is a coefficient in the first coefficient matrix corresponding to one of the M1 subbands; or, the transmission period of the first information.

[0710] Optionally, the processing unit 1002 is further configured to: receive first indication information through the interface unit 1001, the first indication information indicating 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, send at least one piece of information through the interface unit 1001.

[0711] In some possible ways, the processing unit 1002 is further configured to: receive or send third information through the interface unit 1001, the third information indicating at least one of the following: N1 time units out of N time units, wherein each of the N1 vectors includes a coefficient in one of the N1 coefficient matrices, and each of the N1 coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units; or, the time range to which the N time units belong.

[0712] Optionally, the processing unit 1002 is further configured to: send first capability information through the interface unit 1001, the first capability information indicating whether the first device has the capability to provide feedback on channel state information according to the DMD; or, receive second capability information through the interface unit 1001, the second capability information indicating whether the second device has the capability to provide feedback on channel state information according to the DMD.

[0713] 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.

[0714] Processing unit 1002 is configured to: send a first reference signal through interface unit 1001; receive first information through interface unit 1001; wherein at least one piece of information corresponds to at least one stream, the first information is any one of the at least one pieces of information, the first information corresponds to the first stream in the at least one stream, the first information indicates M1 vectors and M1 matrices corresponding to the first stream, M1 is a positive integer, the M1 vectors belong to M vectors corresponding to the first stream, M is a positive integer, the M vectors correspond to M subbands, each of the M vectors is a coefficient in the first coefficient matrix corresponding to one of the subbands, the first coefficient matrix is ​​the coefficient matrix corresponding to the precoding matrix of the first stream, the first stream precoding matrix is ​​determined based on the precoding matrices of the M subbands, the precoding matrices of the M subbands are obtained based on the first reference signal, the M1 vectors correspond to M1 matrices, the first vector is any one of the M1 vectors, the first vector corresponds to the first matrix in the M1 matrices, and the first matrix is ​​used to indicate the recursive relationship between at least one vector in the M vectors and the first vector.

[0715] In some possible ways, the processing unit 1002 is also used 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, and the M vectors being determined according to M1 vectors and M1 matrices.

[0716] In some possible ways, the processing unit 1002 is also configured to: send or receive second information through the interface unit 1001, the second information indicating at least one of the following: M1 subbands out of M subbands; wherein each of the M1 vectors is a coefficient in the first coefficient matrix corresponding to one of the M1 subbands; or, the transmission period of the first information.

[0717] Optionally, the processing unit 1002 is further configured to: send a first indication information through the interface unit 1001, the first indication information indicating the method of feeding back channel status information; and receive at least one piece of information through the interface unit 1001 when the first indication information indicates that the method of feeding back channel status information is a new method.

[0718] In some possible ways, the processing unit 1002 is also configured to: send or receive third information through the interface unit 1001, the third information indicating at least one of the following: N1 time units out of N time units, wherein each of the N1 vectors includes a coefficient in one of the N1 coefficient matrices, and each of the N1 coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units; or, the time range to which the N time units belong.

[0719] Optionally, the processing unit 1002 is further configured to: receive first capability information through the interface unit 1001, the first capability information indicating whether the first device has the capability to provide feedback on channel state information according to the DMD; or, send second capability information through the interface unit 1001, the second capability information indicating whether the second device has the capability to provide feedback on channel state information according to the DMD.

[0720] 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.

[0721] Processing unit 1002 is configured to: receive a first reference signal through interface unit 1001; and send at least one piece of information through interface unit 1001; wherein the at least one piece of information corresponds to at least one stream, the first piece of information is any one of the at least one pieces of information, the first piece of information corresponds to the first stream in the at least one stream, the first piece of information indicates N1 vectors and N1 matrices corresponding to the first stream, N1 is a positive integer, the N1 vectors belong to N vectors corresponding to the first stream, N is a positive integer, the N vectors correspond to N time units, each of the N vectors is a coefficient in one of the N coefficient matrices, each of the N coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of one time unit in the N time units of the first stream, the precoding matrix of each time unit in the N time units of the first stream is obtained according to the first reference signal, the N1 vectors correspond to N1 matrices, the second vector is any one of the N1 vectors, the second vector corresponds to a third matrix in the N1 matrices, and the third matrix is ​​used to indicate: the recursive relationship between one or more of the N vectors and the second vector.

[0722] Optionally, the processing unit 1002 is further configured to: receive first indication information through the interface unit 1001, the first indication information indicating 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, send at least one piece of information through the interface unit 1001.

[0723] In some possible ways, the processing unit 1002 is further configured to: receive or send third information through the interface unit 1001, the third information indicating at least one of the following: N1 time units out of N time units, wherein each of the N1 vectors includes a coefficient in one of the N1 coefficient matrices, and each of the N1 coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units; or, the time range to which the N time units belong.

[0724] Optionally, the processing unit 1002 is further configured to: send first capability information through the interface unit 1001, the first capability information indicating whether the first device has the capability to provide feedback on channel state information according to the DMD; or, receive second capability information through the interface unit 1001, the second capability information indicating whether the second device has the capability to provide feedback on channel state information according to the DMD.

[0725] 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.

[0726] Processing unit 1002 is configured to: send a first reference signal through interface unit 1001; receive first information through interface unit 1001; wherein at least one piece of information corresponds to at least one stream, the first information is any one of the at least one pieces of information, the first information corresponds to the first stream in the at least one stream, the first information indicates N1 vectors and N1 matrices corresponding to the first stream, N1 is a positive integer, the N1 vectors belong to N vectors corresponding to the first stream, N is a positive integer, the N vectors correspond to N time units, each of the N vectors is a coefficient in one of the N coefficient matrices, each of the N coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of one time unit in the N time units of the first stream, the precoding matrix of each time unit in the N time units of the first stream is obtained according to the first reference signal, the N1 vectors correspond to N1 matrices, the second vector is any one of the N1 vectors, the second vector corresponds to a third matrix in the N1 matrices, and the third matrix is ​​used to indicate: the recursive relationship between one or more of the N vectors and the second vector.

[0727] Optionally, the processing unit 1002 is further configured to: send a first indication information through the interface unit 1001, the first indication information indicating the method of feeding back channel status information; and receive at least one piece of information through the interface unit 1001 when the first indication information indicates that the method of feeding back channel status information is a new method.

[0728] In some possible ways, the processing unit 1002 is also configured to: send or receive third information through the interface unit 1001, the third information indicating at least one of the following: N1 time units out of N time units, wherein each of the N1 vectors includes a coefficient in one of the N1 coefficient matrices, and each of the N1 coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units; or, the time range to which the N time units belong.

[0729] Optionally, the processing unit 1002 is further configured to: receive first capability information through the interface unit 1001, the first capability information indicating whether the first device has the capability to provide feedback on channel state information according to the DMD; or, send second capability information through the interface unit 1001, the second capability information indicating whether the second device has the capability to provide feedback on channel state information according to the DMD.

[0730] 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.

[0731] 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 1001 can be implemented by the interface circuit or data transceiver circuit on the aforementioned chip.

[0732] The communication device can be a terminal or an access network device.

[0733] 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, 4A-4C, 5A-5C, and 6 to 9, and will not be repeated here.

[0734] 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.

[0735] 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.

[0736] 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.

[0737] 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.

[0738] 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.

[0739] 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.

[0740] 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 i...

Claims

1. A communication method, characterized in that, Applied to a first device, the method includes: Receive the first reference signal; Send at least one message; Wherein, the at least one piece of information corresponds to at least one stream, the first piece of information is any one of the at least one pieces of information, the first piece of information corresponds to the first stream in the at least one stream, the first piece of information indicates M1 vectors and M1 matrices corresponding to the first stream, M1 is a positive integer, the M1 vectors belong to M vectors corresponding to the first stream, M is a positive integer, the M vectors correspond to M subbands, each of the M vectors is a coefficient in the first coefficient matrix corresponding to one of the subbands in the M subbands, the first coefficient matrix is ​​the coefficient matrix corresponding to the precoding matrix of the first stream, the precoding matrix of the first stream is determined based on the precoding matrix of the M subbands, the precoding matrix of the M subbands is obtained based on the first reference signal, the M1 vectors correspond to the M1 matrices, the first vector is any one of the M1 vectors, the first vector corresponds to the first matrix in the M1 matrices, and the first matrix is ​​used to indicate the recursive relationship between at least one of the M vectors and the first vector.

2. The method as described in claim 1, characterized in that, Also includes: Receive first indication information, the first indication information indicating the method of feedback channel status information; Send at least one message, including: When the first indication information indicates that the method of feedback channel status information is a new method, the at least one piece of information is sent.

3. The method as described in claim 1 or 2, characterized in that, Also includes: Send first capability information, which indicates whether the first device has the ability to provide feedback on channel state information based on Dynamic Mode Decomposition (DMD). or The second capability information is received, which indicates whether the second device has the ability to provide feedback on channel state information based on the DMD.

4. A communication method, characterized in that, Applied to a second device, comprising: Send the first reference signal; Receive the first message; Wherein, the at least one piece of information corresponds to at least one stream, the first piece of information is any one of the at least one pieces of information, the first piece of information corresponds to the first stream in the at least one stream, the first piece of information indicates M1 vectors and M1 matrices corresponding to the first stream, M1 is a positive integer, the M1 vectors belong to M vectors corresponding to the first stream, M is a positive integer, the M vectors correspond to M subbands, each of the M vectors is a coefficient in the first coefficient matrix corresponding to one of the subbands in the M subbands, the first coefficient matrix is ​​the coefficient matrix corresponding to the precoding matrix of the first stream, the precoding matrix of the first stream is determined based on the precoding matrix of the M subbands, the precoding matrix of the M subbands is obtained based on the first reference signal, the M1 vectors correspond to the M1 matrices, the first vector is any one of the M1 vectors, the first vector corresponds to the first matrix in the M1 matrices, and the first matrix is ​​used to indicate the recursive relationship between at least one of the M vectors and the first vector.

5. The method as described in claim 4, 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, which are determined based on the M1 vectors and the M1 matrices.

6. The method as described in claim 4 or 5, characterized in that, Also includes: Send a first indication message, the first indication message indicating the method of feeding back channel status information; Receive at least one piece of information, including: If the first indication information indicates that the method of feedback channel status information is a new method, then the at least one piece of information is received.

7. The method according to any one of claims 4 to 6, characterized in that, Also includes: Receive first capability information, the first capability information indicating whether the first device has the ability to feed back channel state information based on dynamic mode decomposition (DMD); or Send second capability information, which indicates whether the second device has the ability to provide feedback on channel state information based on the DMD.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: Sending or receiving a second message, the second message indicating at least one of the following: M1 sub-bands out of the M sub-bands; wherein each of the M1 vectors is a coefficient in the first coefficient matrix corresponding to one of the M1 sub-bands; or The sending period of the first information.

9. The method as described in claim 8, characterized in that, The second information indicates the M1 sub-bands, including at least one of the following: The second information includes the sequence numbers of the M1 sub-bands; If the sequence number difference between adjacent sub-bands in the M1 sub-bands is the same, the second information includes the sequence number of the reference sub-band in the M1 sub-bands, the sequence number difference, and M1; or The second information includes a first index, which corresponds to the M1 sub-bands.

10. The method as described in claim 8 or 9, characterized in that, The value of the transmission period is positively correlated with the stability of the first stream.

11. The method according to any one of claims 1 to 10, characterized in that, The value of M1 is negatively correlated with the stability of the first flow.

12. The method according to any one of claims 1 to 11, characterized in that, The first information also indicates N1 vectors and N1 matrices corresponding to the first stream, where N1 is a positive integer. The N1 vectors belong to the N vectors corresponding to the first stream, where N is a positive integer. The N vectors correspond to N time units. Each of the N vectors is a coefficient in one of the N coefficient matrices. Each of the N coefficient matrices is the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N time units. The precoding matrix of the first stream in each of the N time units is obtained based on the first reference signal. The N1 vectors correspond to the N1 matrices. The second vector is any one of the N1 vectors. The second vector corresponds to a third matrix in the N1 matrices. The third matrix is ​​used to indicate the recursive relationship between one or more of the N vectors and the second vector.

13. The method according to any one of claims 1 to 12, characterized in that, The method further includes: Receive or send a third message, the third message indicating at least one of the following: The N1 time units out of the N time units; wherein each of the N1 vectors includes a coefficient from one of the N1 coefficient matrices, and each of the N1 coefficient matrices is: the coefficient matrix corresponding to the precoding matrix of the first stream in one of the N1 time units; or The time range to which the N time units belong.

14. The method as described in claim 13, characterized in that, The third information indicates the N1 time units, including at least one of the following: The third information includes the sequence numbers of the N1 time units; If the sequence number difference between adjacent time units in the N1 time units is the same, the third information includes the sequence number of the reference time unit in the N1 time units, the sequence number difference between adjacent time units in the N1 time units, and N1; or The third information includes a second index, which has a corresponding relationship with the N1 time units.

15. The method as described in claim 13 or 14, characterized in that, The length of the time range is positively correlated with the stability of the first stream.

16. The method according to any one of claims 13 to 15, characterized in that, The value of N1 is negatively correlated with the stability of the first flow.

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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