Communication method and communication apparatus

Abstract

Provided in the present application are a communication method and a communication apparatus. The method provides a first basis or a channel covariance matrix for determining the first basis, wherein the first basis is a regional channel basis provided by a channel chart, or the channel covariance matrix is a regional channel covariance matrix provided by the channel chart, which can be used as prior information to be sent to a terminal, which is conducive to reducing the overheads of a reference signal. Moreover, after performing channel measurement on the basis of the reference signal, the terminal can only feed back the position index of the first basis without the need to feed back information, such as the index of one or more basis vectors constituting the first basis, and long-period coefficients, which is conducive to reducing the feedback overheads.

Description

A communication method and communication device

[0001] This application claims priority to Chinese Patent Application No. 202311683910.X, filed on December 7, 2023, entitled "A Communication Method and Communication Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a communication method and communication device. Background Technology

[0003] Currently, channel reconfiguration schemes based on reference signals suffer from high overhead in reference signal resources and high feedback overhead in long-period basis architectures. For example, the codebook in 3GPP Release 16 (R16) only utilizes the sparse characteristics of the channel in the angle-delay domain, requiring the reporting of spatial and frequency domain basis architectures and combination coefficients, resulting in significant feedback overhead. As another example, the codebook in 3GPP Release 18 (R18) further considers the sparse characteristics of the channel and takes into account the inconsistent rates of change of different channel characteristics over time, designing a codebook feedback method combining long and short periods to reduce feedback overhead; however, with the increase in antennas, the overhead of the required reference signals increases dramatically, as does the feedback overhead. Summary of the Invention

[0004] This application provides a communication method and device. The method can send a first substrate as prior information to a first device, which helps reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first substrate, which helps reduce feedback overhead.

[0005] In a first aspect, this application provides a communication method executed by a first device. For example, the first device may be a terminal, a component of the terminal (e.g., a processor, chip, or chip system), or a logic module capable of implementing all or part of the terminal's functions. The first device receives indication information of a first substrate, which indicates the projection coefficients of the first substrate onto the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. After receiving the indication information of the first substrate, the first device can determine and record the first substrate. The first device receives a first reference signal and determines a first channel matrix based on the first reference signal. Further, the first device can determine a first superposition coefficient vector based on a second substrate constructed from the corresponding row of the first substrate using the first channel matrix and the position index of the first reference signal in the spatial frequency domain. For example, assuming the dimension of the first channel matrix is ​​MN1*1, the dimension of the second substrate is MN1*L, M is the number of antenna ports receiving the first reference signal, N1 is the number of frequency domain units carrying the first reference signal, the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, M and N1 are positive integers, and L is less than or equal to MN1. The first device can select the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determine the position indices of the K superposition coefficient vectors in the first superposition coefficient vector to form a second basis selection vector. Furthermore, the first device can transmit the second superposition coefficient vector and the second basis selection vector.

[0006] In this method, the first device can receive indication information from a first substrate and a first reference signal. The first reference signal can be a sparse reference signal, which helps reduce the overhead of the reference signal. Furthermore, based on the indication information from the first substrate, the first device can determine the position index of the first reference signal in the spatial frequency domain in the corresponding row of the first substrate. This allows the first device to calculate short-period coefficients (such as a second superposition coefficient vector) by combining the channel estimation results of the sparse reference signal and report them, which helps reduce feedback overhead.

[0007] This application also provides a communication method, which differs from the previous communication method in that the indication information of the first basis indicates the projection coefficients of the channel covariance matrix on the quantization basis and the corresponding indices of the projection coefficients on the quantization basis. Thus, the first device can determine the channel covariance matrix based on the indicated projection coefficients and indices of the channel covariance matrix; perform singular value decomposition or eigenvalue decomposition on the channel covariance matrix to obtain the first basis corresponding to the channel covariance matrix, and then perform subsequent operations in the previous communication method, such as receiving a first reference signal and determining a first channel matrix based on the first reference signal; determining a first superposition coefficient vector based on a second basis constructed from the position indices of the first channel matrix and the first reference signal in the spatial frequency domain in the corresponding rows of the first basis; and transmitting a second superposition coefficient vector and a second basis selection vector, wherein the second superposition coefficient vector includes K superposition coefficients; and the second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector, where K is a positive integer less than or equal to L.

[0008] In this method, the first reference signal in the first device remains a sparse reference signal, which helps reduce the overhead of the reference signal. Furthermore, based on the first basis, the first device can calculate and report the second superposition coefficient vector by combining the channel estimation results of the sparse reference signal, which helps reduce feedback overhead.

[0009] Optionally, the indication information of the first basis may indicate: the top L elements of the diagonal coefficient matrix of the projection coefficient matrix of the channel covariance matrix onto the quantization basis, which have the largest numerical or quantized values. delay Each projection coefficient, and the preceding L delay Each projection coefficient corresponds to an index on the quantization basis. Since the diagonal elements of the projection coefficient matrix are real numbers, indicating the diagonal elements reduces indication overhead. In one possible implementation, the first device multiplies the second superposition coefficient vector and the third basis to obtain a second channel matrix; the third basis is composed of the K position indices from the second basis selected from the corresponding columns of the first basis.

[0010] In this method, the first device can determine the projection of the channel matrix based on the corresponding columns of the first basis using K position indices. The channel matrix can be recovered by combining the projection of the channel matrix with short-period coefficients, which helps to reduce computational overhead.

[0011] In one possible implementation, the first device performs channel estimation based on a second reference signal to obtain a third channel matrix. The second reference signal is a reference signal received prior to the first reference signal, and the second reference signal is of the same type as the first reference signal. The first device determines a fourth basis based on the third channel matrix, and determines the common subspace where the fourth basis intersects with the first basis as a first common subspace, and determines the subspaces in the fourth basis excluding the first common subspace as first non-common subspaces. The first device sends indication information for the first non-common subspace, which indicates the projection coefficients of the first non-common subspace onto the quantization basis of the first non-common subspace and the column index of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L1 column basis vectors, where L1 is a positive integer.

[0012] In this method, the first device can further perform channel estimation on the second reference signal (also known as the historical reference signal) to obtain a third channel matrix (also known as the historical channel matrix), thereby allowing the first device to determine the projection of the historical channel matrix. Furthermore, the first device can determine a first non-common subspace, which is a non-common subspace of the projections of the historical channel matrix and the current channel matrix. This first non-common subspace characterizes the difference between the projections of the historical channel matrix and the current channel matrix, thus facilitating the updating of the first basis based on this difference and improving the accuracy of channel estimation.

[0013] In one possible implementation, the first device receives first indication information, which indicates the frequency domain position for transmitting the third reference signal. The first device transmits the third reference signal based on the first indication information.

[0014] In this method, the first device may also receive first indication information of a third reference signal (such as an uplink reference signal), and then send the third reference signal based on the indication of the first indication information, so that the receiving end of the third reference signal can perform channel estimation and recover channel state information based on the third reference signal.

[0015] Secondly, this application provides a communication method executed by a second device. For example, the second device may be a network device (such as a base station), or a component of the network device (such as a processor, chip, or chip system), or a logic module capable of implementing all or part of the network device's functions. The second device transmits indication information for a first substrate, which indicates the projection coefficients of the first substrate onto the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. The second device transmits a first reference signal, enabling a receiver of the first reference signal to perform channel estimation based on the first reference signal to obtain a first channel matrix. Furthermore, the receiver of the first reference signal can determine a first superposition coefficient vector based on the second substrate constructed from the first channel matrix and the position index of the first reference signal in the spatial frequency domain of the corresponding row of the first substrate. This determines the first superposition coefficient vector, selects the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and the position indices of these K superposition coefficient vectors in the first superposition coefficient vector constitute a second substrate selection vector. The second device receives the second superposition coefficient vector and the second substrate selection vector.

[0016] In this method, the second device can determine a first basis and send indication information of the first basis and a first reference signal. The first reference signal can be a sparse reference signal, which helps reduce the overhead of the reference signal. Furthermore, the second device receives a smaller amount of data for the second superposition coefficient vector and the second basis selection vector, indicating lower feedback overhead. Further, based on these two types of feedback and the first basis, the second device can recover the channel state information.

[0017] In another embodiment, this application also provides a communication method, which differs from the previous communication method in that the indication information of the first basis indicates the projection coefficients of the channel covariance matrix on the quantization basis and the corresponding indices of the projection coefficients on the quantization basis; enabling the first device to first recover the channel covariance matrix based on the indicated projection coefficients and indices of the channel covariance matrix, and then perform singular value decomposition or eigenvalue decomposition on the channel covariance matrix to obtain the first basis corresponding to the channel covariance matrix. Furthermore, the second device sends a first reference signal, which can correspondingly receive a second superposition coefficient vector and a second basis selection vector; the second device can recover channel state information based on the received second superposition coefficient vector and second basis selection vector.

[0018] In this method, the second device sends indication information of the first substrate and a first reference signal. The first reference signal can be a sparse reference signal, which helps to reduce the overhead of the reference signal. Furthermore, the second device receives relatively small amounts of data for the second superposition coefficient vector and the second substrate selection vector, resulting in lower feedback overhead.

[0019] Optionally, the indication information of the first basis may indicate: the top L elements of the diagonal coefficient matrix of the projection coefficient matrix of the channel covariance matrix onto the quantization basis, which have the largest numerical or quantized values. delay Each projection coefficient, and the preceding L delay The index of each projection coefficient on the quantization basis. Since the diagonal elements of the projection coefficient matrix are real numbers, indicating the diagonal elements reduces the indication overhead.

[0020] In one possible implementation, the second device multiplies the second superposition coefficient vector and the third basis to obtain the second channel matrix; the third basis is composed of the K position indices in the second basis selection vector in the corresponding columns of the first basis.

[0021] In this method, the second device can determine the projection of the channel matrix based on the corresponding columns of the first basis using K position indices. The channel matrix can be recovered by combining the projection of the channel matrix with short-period coefficients, which helps to reduce computational overhead.

[0022] In one possible implementation, the second device receives indication information of a first non-common subspace. This indication information indicates the projection coefficients of the first non-common subspace onto the quantization basis of the first non-common subspace, as well as the column index of the quantization basis of the first non-common subspace. The second device performs Schmitt orthogonalization on the first basis and the first non-common subspace to obtain a fifth basis, and then sends indication information for the fifth basis. Specifically, the indication information for the fifth basis indicates the fifth basis, or indicates the projection coefficients of the fifth basis onto the quantization basis of the fifth basis, as well as the column index of the quantization basis of the fifth basis.

[0023] In this method, after the first device determines the non-common subspace of the projection of the historical channel matrix and the projection of the current channel matrix, it can indicate this non-common subspace (i.e., the first non-common subspace) to the second device. Specifically, the indication method includes indicating only the projection coefficients of the first non-common subspace and the column index of the quantization basis, which helps reduce feedback overhead. Furthermore, after determining the first non-common subspace, the second device can update the first basis based on the first non-common subspace to obtain the fifth basis. Subsequently, the fifth basis can be used to quantize the channel matrix, which helps improve the accuracy of recovering channel state information. Optionally, the second device can also send the indication information of the fifth basis to the core network equipment, thereby facilitating the core network equipment to update the basis information and the channel map.

[0024] In one possible implementation, the second device sends first indication information, which indicates the frequency domain position for transmitting the third reference signal. The second device receives the third reference signal.

[0025] In this method, the second device may also send a first indication message, thereby instructing the first device to send a third reference signal, so that the channel state information can be recovered based on the third reference signal.

[0026] In one possible implementation, the second device determines a fourth channel matrix based on a third reference signal, and determines a third superposition coefficient vector based on a sixth basis constructed from the fourth channel matrix and the position indices of the third reference signal in the spatial frequency domain corresponding to the rows of the first basis. The second device determines that the F superposition coefficients with the largest amplitudes in the third superposition coefficient vector constitute a fourth superposition coefficient vector, and determines that the position indices of these F superposition coefficients in the third superposition coefficient vector constitute a fourth basis selection vector. The second device multiplies the fourth superposition coefficient vector by a seventh basis to obtain a fifth channel matrix, where the seventh basis is composed of the K position indices of the fourth basis selection vector corresponding to the columns of the fifth basis.

[0027] In this method, the second device can perform channel estimation and channel state information recovery based on the uplink reference signal (e.g., SRS).

[0028] In one possible implementation, the second device sends a first request message to the core network equipment, requesting access to a channel map or requesting access to the base information corresponding to the first device in the channel map. The second device receives a first response message, which includes the channel map or the base information corresponding to the first device in the channel map. In this method, the second device can request access to the channel map from the core network equipment, thereby obtaining base information (such as a first base) based on the channel map, and can send the base information as prior information to the first device, which helps to reduce the overhead of the reference signal.

[0029] In one possible implementation, the second device sends a first request message to the core network equipment, requesting to obtain a channel map, or requesting to obtain the channel covariance matrix corresponding to the first device in the channel map. The second device receives a first response message, which includes the channel map, or the channel covariance matrix corresponding to the first device in the channel map.

[0030] In this method, the second device can request the channel map from the core network equipment, thereby obtaining the channel covariance matrix corresponding to the first device based on the channel map, and can send the channel covariance matrix as prior information to the first device, which helps to reduce the overhead of the reference signal.

[0031] In one possible implementation, the second device performs channel estimation based on the fourth reference signal to obtain multiple sixth channel matrices. These sixth channel matrices include channel state information in the spatial frequency domain. The fourth reference signal is a reference signal received prior to the third reference signal, and the fourth reference signal is of the same type as the third reference signal. Based on these multiple sixth channel matrices, the second device determines an eighth basis.

[0032] In one possible implementation, the second device determines the common subspace where the eighth substrate and the first substrate intersect as the second common subspace, and determines the subspace in the eighth substrate excluding the second common subspace as the second non-common subspace, which is used to update the fifth substrate.

[0033] In the above method, the second device can generate a corresponding eighth basis based on the information of the historical SRS signal, thereby obtaining the difference information (such as the second non-common subspace) between the information of the first basis and the historical SRS signal, and thus updating the channel basis, which is beneficial to improving the reconstruction accuracy of the channel state information.

[0034] In one possible implementation, the second device performs Schmitt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis. Based on the fourth channel matrix and the corresponding rows of the SRS signal's spatial frequency position in the ninth basis, the second device determines the fifth superposition coefficient vector, and based on the fifth superposition coefficient vector, determines the sixth superposition coefficient vector and the sixth basis selection vector. The second device multiplies the sixth superposition coefficient vector with the tenth basis to obtain the sixth channel matrix, thereby reconstructing the channel state information.

[0035] Thirdly, this application provides a communication method implemented through interaction between a first device and a second device. For example, the first device may be a terminal, and the second device may be a network device. The communication method includes the following steps: the second device sends indication information of a first substrate, the indication information indicating the projection coefficients of the first substrate on the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate; correspondingly, the first device receives the indication information of the first substrate. The second device sends a first reference signal, correspondingly, the first device receives the first reference signal, and determines a first channel matrix based on the first reference signal. Further, the first device can determine a first superposition coefficient vector based on a second substrate constructed from the first channel matrix and the position index of the first reference signal in the spatial frequency domain of the corresponding row of the first substrate. The first device selects the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determines the position indices of the K superposition coefficient vectors in the first superposition coefficient vector to form a second substrate selection vector. The first device can send the second superposition coefficient vector and the second substrate selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second substrate selection vector.

[0036] In another communication method, a second device sends indication information of a first substrate. This indication information indicates the projection coefficients of the channel covariance matrix onto the quantization substrate and the corresponding indices of these projection coefficients on the quantization substrate. The projection coefficients and indices of the channel covariance matrix are used by the receiving end to recover the channel covariance matrix and determine the first substrate. Correspondingly, the first device receives this indication information. The second device also sends a first reference signal. Correspondingly, the first device receives the first reference signal and determines a first channel matrix based on it. Further, the first device can determine a first superposition coefficient vector based on a second substrate constructed from the first channel matrix and the position indices of the first reference signal in the spatial frequency domain, corresponding to the rows of the first substrate. The first device selects the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determines the position indices of these K superposition coefficient vectors within the first superposition coefficient vector to form a second substrate selection vector. The first device can send the second superposition coefficient vector and the second substrate selection vector; correspondingly, the second device receives both the second superposition coefficient vector and the second substrate selection vector.

[0037] In this method, the first device can receive indication information from a first substrate and a first reference signal. The first reference signal can be a sparse reference signal, which helps reduce the overhead of the reference signal. Furthermore, based on the indication information from the first substrate, the first device can determine the position index of the first reference signal in the spatial frequency domain within the corresponding row of the first substrate. This allows the first device to calculate short-period coefficients (such as a second superposition coefficient vector) and report them, combining the channel estimation results of the sparse reference signal, thus reducing feedback overhead. The second device receives a smaller amount of data for the second superposition coefficient vector and the second substrate selection vector, indicating lower feedback overhead. Further, based on these two types of feedback and the first substrate, the second device can recover the channel state information.

[0038] Optionally, other implementations of this communication method can be found in the corresponding descriptions in the first and second aspects, and will not be repeated here.

[0039] Fourthly, this application provides a communication device. This communication device may be a terminal, a component of a terminal (e.g., a processor, chip, or chip system), or a device compatible with a terminal. In one possible implementation, the communication device may include functional modules, which may be hardware circuits, software, or a combination of hardware circuits and software.

[0040] In one possible implementation, the communication device includes a communication unit and a processing unit. The communication unit receives indication information of a first substrate, which indicates the projection coefficients of the first substrate onto a quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. The processing unit determines and records the first substrate. The communication unit also receives a first reference signal, and the processing unit further determines a first channel matrix based on the first reference signal. The processing unit further determines a first superposition coefficient vector based on a second substrate constructed from the first channel matrix and the position index of the first reference signal in the spatial frequency domain of the corresponding row of the first substrate. The processing unit further selects K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determines the position indices of these K superposition coefficient vectors within the first superposition coefficient vector to form a second substrate selection vector. The communication unit further transmits the second superposition coefficient vector and the second substrate selection vector.

[0041] In one possible implementation, the processing unit is used to multiply the second superposition coefficient vector and the third basis to obtain the second channel matrix; the third basis is composed of the K position indices in the second basis selection vector in the corresponding columns of the first basis.

[0042] In one possible implementation, the processing unit is configured to perform channel estimation based on a second reference signal to obtain a third channel matrix. The second reference signal is a reference signal received prior to the first reference signal, and the second reference signal is of the same type as the first reference signal. The processing unit is configured to determine a fourth basis based on the third channel matrix, and to determine the common subspace where the fourth basis intersects with the first basis as a first common subspace, and to determine the subspace in the fourth basis excluding the first common subspace as a first non-common subspace. The communication unit is configured to transmit indication information for the first non-common subspace, which indicates the projection coefficients of the first non-common subspace onto the quantization basis of the first non-common subspace and the column index of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L1 column basis vectors, where L1 is a positive integer.

[0043] In one possible implementation, the communication unit is configured to receive first indication information, which indicates the frequency domain position for transmitting the third reference signal. The processing unit is configured to transmit the third reference signal through the communication unit based on the first indication information.

[0044] Fifthly, this application provides a communication device. This communication device may be a network device, a component of a network device (e.g., a processor, chip, or chip system), or a device compatible with a network device. In one possible implementation, the communication device may include functional modules, which may be hardware circuits, software, or a combination of hardware circuits and software.

[0045] In one possible implementation, the communication device includes a communication unit and a processing unit. The communication unit is configured to transmit indication information of a first substrate, which indicates the projection coefficients of the first substrate onto the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. The communication unit is further configured to transmit a first reference signal, enabling a receiver of the first reference signal to perform channel estimation based on the first reference signal to obtain a first channel matrix. The receiver of the first reference signal can also determine a first superposition coefficient vector based on the first channel matrix and the position index of the first reference signal in the spatial frequency domain, constructed from the corresponding rows of the first substrate, thereby determining the first superposition coefficient vector. This allows the receiver to select the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and the position indices of these K superposition coefficient vectors within the first superposition coefficient vector to form a second substrate selection vector. The communication unit is also configured to receive the second superposition coefficient vector and the second substrate selection vector.

[0046] In one possible implementation, the processing unit is used to multiply the second superposition coefficient vector and the third basis to obtain the second channel matrix; the third basis is composed of the K position indices in the second basis selection vector in the corresponding columns of the first basis.

[0047] In one possible implementation, the communication unit is configured to receive indication information of a first non-common subspace, which indicates the projection coefficients of the first non-common subspace onto the quantization basis of the first non-common subspace and the column index of the quantization basis of the first non-common subspace. The processing unit is configured to perform Schmitt orthogonalization processing on the first basis and the first non-common subspace to obtain a fifth basis, and the communication unit is configured to transmit indication information of the fifth basis. Specifically, the indication information of the fifth basis indicates the fifth basis, or indicates the projection coefficients of the fifth basis onto the quantization basis of the fifth basis and the column index of the quantization basis of the fifth basis.

[0048] In one possible implementation, the communication unit is configured to transmit first indication information, which indicates the frequency domain position for transmitting the third reference signal. The communication unit is also configured to receive the third reference signal.

[0049] In one possible implementation, the processing unit is configured to determine a fourth channel matrix based on a third reference signal, and to determine a third superposition coefficient vector based on a sixth basis constructed from the fourth channel matrix and the position indices of the third reference signal in the spatial frequency domain corresponding to the rows of the first basis. The processing unit is further configured to determine that the F superposition coefficients with the largest amplitudes in the third superposition coefficient vector constitute a fourth superposition coefficient vector, and to determine that the position indices of these F superposition coefficients in the third superposition coefficient vector constitute a fourth basis selection vector. The processing unit is also configured to multiply the fourth superposition coefficient vector by a seventh basis to obtain a fifth channel matrix, where the seventh basis is composed of the K position indices of the fourth basis selection vector corresponding to the columns of the fifth basis.

[0050] In one possible implementation, the communication unit is configured to send a first request message to the core network equipment, the first request message requesting access to a channel map, or requesting access to base information corresponding to a first device in the channel map. The communication unit is also configured to receive a first response message, the first response message including the channel map, or the base information corresponding to the first device in the channel map.

[0051] In one possible implementation, the processing unit is used to perform channel estimation based on the fourth reference signal to obtain multiple sixth channel matrices. These sixth channel matrices include channel state information in the spatial dimension. The fourth reference signal is a reference signal received prior to the third reference signal, and the fourth reference signal is of the same type as the third reference signal. The processing unit is then used to determine an eighth basis based on the multiple sixth channel matrices.

[0052] In one possible implementation, the processing unit is used to determine the common subspace where the eighth base and the first base intersect as the second common subspace, and to determine the subspace in the eighth base excluding the second common subspace as the second non-common subspace, which is used to update the fifth base.

[0053] In one possible implementation, the processing unit performs Schmitt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis. The processing unit then determines the fifth superposition coefficient vector based on the fourth channel matrix and the corresponding row of the SRS signal's spatial frequency position in the ninth basis, and determines the sixth superposition coefficient vector and the sixth basis selection vector based on the fifth superposition coefficient vector. Finally, the processing unit multiplies the sixth superposition coefficient vector with the tenth basis to obtain the sixth channel matrix, thereby reconstructing the channel state information.

[0054] Regarding the fourth and fifth aspects, as examples, the processing unit can be a processor, and the communication unit can be a transceiver unit, transceiver, or communication interface. It is understood that when the communication device is a communication apparatus (e.g., a terminal or network device), the communication unit can be a transceiver within the communication apparatus (e.g., a transceiver includes a transmitter and a receiver), implemented, for example, through an antenna, feeder, and codec within the communication apparatus. Alternatively, if the communication device is a chip located within a device, the processing unit can be the chip's processing circuitry, logic circuitry, etc., and the communication unit can be the chip's input / output interface, such as input / output circuitry, pins, etc.

[0055] Sixthly, this application provides a communication device, comprising: a processor for executing instructions; optionally, the communication device further comprises a memory for storing the instructions, which, when executed by the processor, cause the communication device to perform at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect. Optionally, the processor and the memory are coupled.

[0056] In a seventh aspect, this application provides a communication system comprising at least one of the means or apparatuses of the fourth to sixth aspects described above, such that the at least one means or apparatus performs at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect.

[0057] Eighthly, this application provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect.

[0058] Ninthly, this application provides a computer program product including instructions that, when executed on a computer, cause the computer to perform at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect.

[0059] In a tenth aspect, this application provides a chip including a processor (or logic circuit). Optionally, the chip may further include a communication interface (or interface) for implementing at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect. In one possible implementation, if the chip is the smallest processing unit in a complete machine, the chip may be a processor, or may include a processor and a memory, or may include a processor, a memory, and a transceiver for implementing at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect.

[0060] Eleventhly, this application provides a chip system. The chip system includes a processor and an interface. Optionally, it may also include memory for implementing at least one of the following: the method of the first aspect and any possible implementation of the first aspect, and the method of the second aspect and any possible implementation of the second aspect. The chip system may be composed of a chip or may include chips and other discrete devices. Attached Figure Description

[0061] Figure 1 is a schematic diagram of a communication system provided in this application;

[0062] Figure 2 is a schematic diagram of a network element structure provided in this application;

[0063] Figure 3 is a schematic diagram of a channel map;

[0064] Figure 4 is a schematic diagram of the process of performing CSI measurement on a network device and terminal;

[0065] Figure 5 is a schematic diagram of an R16 codebook structure;

[0066] Figure 6 is a schematic diagram of a channel matrix H represented by column vectors;

[0067] Figure 7 is a schematic diagram of matrix decomposition of a space-frequency joint channel h;

[0068] Figure 8 is a schematic diagram of a space-frequency joint long and short period combined codebook feedback process;

[0069] Figure 9 is a flowchart illustrating a communication method provided in this application;

[0070] Figure 10 is a schematic diagram of a downlink channel reconstruction process enabled by combining a channel map with CSI-RS according to this application;

[0071] Figure 11 is a schematic diagram of a channel map combined with CSI-RS to enable downlink channel reconstruction and channel basis update process provided in this application;

[0072] Figure 12 is a schematic diagram of a downlink channel reconstruction process enabled by combining a channel map with CSI-RS and SRS, as provided in this application.

[0073] Figure 13 is a schematic diagram of a channel map combined with CSI-RS and SRS to enable downlink channel reconstruction and channel basis update process provided in this application;

[0074] Figure 14 is a schematic diagram of a channel map combined with SRS to enable channel reconstruction and channel basis update process provided in this application;

[0075] Figure 15 is a schematic diagram of a communication device provided in this application;

[0076] Figure 16 is a schematic diagram of another communication device provided in this application. Detailed Implementation

[0077] The communication method provided in this application can be applied to the communication system 1000 shown in Figure 1. For example, the communication system includes a radio access network (RAN) 100, wherein the RAN 100 includes at least one RAN node (110a and 110b in Figure 1, collectively referred to as 110), and may also include at least one terminal (120a-120j in Figure 1, collectively referred to as 120). The RAN 100 may also include other RAN nodes, such as wireless relay devices and / or wireless backhaul devices (not shown in Figure 1). The terminal 120 is wirelessly connected to the RAN node 110. Terminals and RAN nodes can be interconnected via wired or wireless means. The communication system 1000 may also include a core network 200. The RAN node 110 is connected to the core network 200 wirelessly or via wired means. The core network equipment in the core network 200 and the RAN node 110 in the RAN 100 can be independent and different physical devices, or they can be the same physical device integrating the logical functions of the core network equipment and the logical functions of the RAN node. The communication system 1000 may also include the Internet 300.

[0078] RAN100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, or a future radio access system as defined in 3GPP. RAN100 can also include two or more of the above-mentioned different radio access systems. RAN100 can also be an open RAN (O-RAN).

[0079] RAN nodes, also known as radio access network devices, RAN entities, or access nodes, are used to help terminals access communication systems wirelessly. In one application scenario, an RAN node can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a 5G mobile communication system, a next-generation base station in a 6G mobile communication system, or a base station in a future mobile communication system. RAN nodes can be macro base stations (as shown in Figure 1, 110a), micro base stations or indoor stations (as shown in Figure 1, 110b), and can also be relay nodes or donor nodes.

[0080] In another application scenario, multiple RAN nodes can collaborate to help terminals achieve wireless access, with different RAN nodes implementing different functions of the base station. For example, a RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). Here, the CU performs the functions of the base station's Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP), and can also perform the functions of the Service Data Adaptation Protocol (SDAP). The DU performs the functions of the base station's Radio Link Control (RANC) and Medium Access Control (MAC) layers, and can also perform some or all of the physical layer functions. For specific descriptions of these protocol layers, refer to the relevant 3GPP technical specifications. The RU can be used to implement radio frequency signal transmission and reception. The CU and DU can be two independent RAN nodes or integrated into the same RAN node, such as within a baseband unit (BBU). The RU can be included in radio frequency equipment, such as in a remote radio unit (RRU) or an active antenna unit (AAU). The CU can be further divided into two types of RAN nodes: CU-control plane and CU-user plane.

[0081] In different systems, RAN nodes may have different names. For example, in an O-RAN system, a CU can be called an open CU (O-CU), a DU can be called an open DU (O-DU), and an RU can be called an open RU (O-RU). The RAN nodes in the embodiments of this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules. For example, a RAN node can be a server loaded with the corresponding software modules. The embodiments of this application do not limit the specific technology or device form used in the RAN nodes. For ease of description, a base station is used as an example of a RAN node in the following description.

[0082] A terminal is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from a base station. Terminals can also be called terminal equipment, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, airplanes, ships, robots, robotic arms, smart home devices, etc. The embodiments of this application do not limit the specific technology or device form used in the terminal.

[0083] Base stations and terminals can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the base stations and terminals.

[0084] The roles of base stations and terminals can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile base station. For terminals 120j that access the wireless access network 100 through 120i, terminal 120i is a base station; however, for base station 110a, 120i is a terminal, meaning that 110a and 120i communicate via a wireless air interface protocol. Of course, 110a and 120i can also communicate via a base station-to-base station interface protocol. In this case, relative to 110a, 120i is also a base station. Therefore, both base stations and terminals can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be called communication devices with base station functions, and 120a-120j in Figure 1 can be called communication devices with terminal functions.

[0085] Communication between base stations and terminals, between base stations, and between terminals can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can be conducted using spectrum below 6 GHz, spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0086] In the embodiments of this application, the functions of the base station can be executed by modules (such as chips) within the base station, or by a control subsystem that includes base station functions. This control subsystem, including base station functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal can be executed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions.

[0087] In this application, the base station sends downlink signals or downlink information to the terminal, with the downlink information carried on the downlink channel; the terminal sends uplink signals or uplink information to the base station, with the uplink information carried on the uplink channel. To communicate with the base station, the terminal needs to establish a radio connection on a cell controlled by the base station. The cell with which the terminal has established a radio connection is called the terminal's serving cell. When the terminal communicates with this serving cell, it is also susceptible to interference from signals from neighboring cells.

[0088] The core network may include, but is not limited to, one or more of the following devices or network elements: Access and Mobility Management Function (AMF), Location Management Function (LMF), Map Management Function (MMF), etc. The AMF is primarily responsible for mobility management in the mobile network, such as user location updates, user network registration, and user handover. The LMF is primarily responsible for acquiring location information such as user location. The MMF is primarily responsible for storing channel characteristics based on location information and generating channel maps, etc.

[0089] Optionally, the network element structure involved in this application is shown in Figure 2, and mainly includes the following network elements and modules:

[0090] (1) Radio Resource Control (RRC) Signaling Interaction Module: The module used by the base station and the terminal to send and receive RRC signaling.

[0091] (2) MAC signaling interaction module: The module used by the base station and terminal to send and receive signaling from the Media Access Control-Control Element (MAC-CE).

[0092] (3) Physical layer (PHY) signaling and data interaction module: The module used by the base station and terminal to send and receive uplink / downlink control signaling (e.g., physical downlink control channel (PDCCH), physical uplink control channel (PUCCH)) and uplink / downlink data (e.g., data transmitted on physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH)).

[0093] (4) The base station communicates with the AMF through the NG-C interface. The AMF is equivalent to a router for communication between the base station and the LMF / MMF. The LMF realizes the location estimation of the UE. The map construction process is completed in the LMF / MMF. The AMF communicates with the LMF / MMF through the NLs interface.

[0094] It is understood that in this application, PDSCH, PDCCH, PUSCH and PUCCH are just examples of downlink data channel, downlink control channel, uplink data channel and uplink control channel, respectively. In different systems and different scenarios, data channels and control channels may have different names, and this application does not limit them.

[0095] It should be noted that:

[0096] In the embodiments of this application, "send" and "receive" indicate the direction of signal transmission. For example, "sending information to a terminal" can be understood as the destination of the information being the terminal device, which may include sending directly via the air interface or sending indirectly via the air interface from other units or modules. "Receiving information from a network device" can be understood as the source of the information being the network device, which may include receiving directly from the network device via the air interface or receiving indirectly from the network device via the air interface from other units or modules. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface.

[0097] In other words, sending and receiving can occur between devices, such as between network devices and terminal devices, or within a device, such as between components, modules, chips, software modules, or hardware modules within the device via buses, wiring, or interfaces.

[0098] It is understandable that information may undergo processing, such as encoding and modulation, between the source and destination, but the destination can still understand the valid information from the source. Similar statements in this application can be interpreted in a similar way and will not be elaborated further.

[0099] In the embodiments of this application, "instruction" can include direct and indirect instructions, as well as explicit and implicit instructions. The information indicated by a certain piece of information (hereinafter referred to as instruction information) is called the information to be instructed. In specific implementation, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index. It can also indirectly indicate the information to be instructed by indicating other information, where there is an association between the other information and the information to be instructed; or it can indicate only a part of the information to be instructed, while the other parts are known or pre-agreed upon. For example, the instruction can be implemented by using a pre-agreed (e.g., protocol predefined) arrangement of various information, thereby reducing the instruction overhead to a certain extent. This application does not limit the specific method of instruction. It is understood that for the sender of the instruction information, the instruction information can be used to indicate the information to be instructed; for the receiver of the instruction information, the instruction information can be used to determine the information to be instructed.

[0100] For ease of understanding, the definitions of relevant terms used in this application are provided below:

[0101] 1. Channel map:

[0102] A channel map can be understood as a database used to store channel features based on location information; these channel features include, but are not limited to, channel statistical covariance matrix, angle spectrum, delay spectrum, and path loss. For example, Figure 3 shows a schematic diagram of a channel map. In this channel map, physical cells are divided into two-dimensional grid-level sections (each square in Figure 3 is called a grid point), and each grid point stores several channel features (such as channel statistical covariance matrix, angle spectrum, delay spectrum, and path loss) in the form of a matrix, vector, or scalar.

[0103] One common method for constructing channel maps is to build a database based on historical measurement data and establish a mapping relationship between location information and channel characteristics. However, historical measurement data has limitations. For example, it is usually based on channel characteristics at known locations, and interpolation methods are used to complete the channel characteristics at unknown locations to obtain the channel map for the entire cell. With the development of digital twin technology, channel maps can be obtained through channel twin technology. For example, computers can combine prior environmental maps (including measured environmental information) and use electromagnetic simulation to calculate and simulate the reflection, diffraction, and scattering characteristics of communication multipath, thereby obtaining deterministic channels for constructing channel maps.

[0104] 2. Channel map-assisted communication technology:

[0105] With the increasing system bandwidth, the proliferation of terminal antennas, the heavier network load, the surge in wireless channel dimensions (such as spatial, spatial-frequency, and frequency domains), and the limited pilot measurement resources, high-precision wireless channel measurement faces significant challenges. Accurate wireless channel measurement is the cornerstone of mobile communication network research and is crucial for the design, analysis, and optimization of wireless communication networks. However, traditional wireless channel measurement methods based on reference signals (such as pilot symbols) are insufficient to meet the demands of technologies with large bandwidth and multiple antennas. To address the limited reference signal measurement resources in wireless communication systems, channel maps can be used to achieve low pilot overhead channel measurement; for example, the channel covariance matrix at a specific location can be provided through the channel map, and this covariance matrix can be used to help reduce the sounding reference signal (SRS) overhead.

[0106] 3. Downlink channel reconstruction technology:

[0107] In 5G communication systems, employing massively multi-input multiple-output (MIMO) technology is beneficial for improving system spectral efficiency. When using MIMO technology, network devices need to perform signal precoding based on channel state information (CSI) when sending data to terminal devices.

[0108] In time-division duplex (TDD) systems, downlink channel identity (CSI) can be obtained based on channel reciprocity, for example, by estimating the downlink channel through uplink SRS data transmission. However, as the number of users increases and the load intensifies, SRS round-robin transmission in high-bandwidth scenarios may lead to insufficient SRS resources and severe channel aging.

[0109] In frequency division duplex (FDD) systems, due to the significant frequency spacing between uplink and downlink channels, the uplink and downlink channels do not satisfy a direct reciprocal relationship, making it impossible to use uplink channel information for accurate downlink precoding. In FDD systems, users need to feed back downlink channel CSI to the base station.

[0110] For example, Figure 4 is a schematic diagram of a process for network devices and terminals to perform CSI measurements, which may include the following steps:

[0111] Step 1: The network device sends channel measurement configuration information to the terminal. This channel measurement configuration information is used to configure channel measurements, such as instructing the terminal on the time for channel measurements.

[0112] Step 2: The network device sends a Channel State Information Reference Signal (CSI RS) to the terminal. This pilot signal is used for channel measurement. For example, the terminal receives the CSI-RS and performs measurements based on it to obtain CSI feedback information. Optionally, the CSI-RS can also be called a CSI-RS pilot.

[0113] Step 3: The terminal sends channel state information to the network device. For example, the terminal sends channel state information such as channel rank indicator (RI), channel quality indicator (CQI), and precoding matrix indicator (PMI) to the network device.

[0114] Step 4: The network device sends data to the terminal based on the CSI. Specifically, the network device determines the precoding information for the service data to be sent, etc., based on the CSI returned by the terminal, and then transmits the service data.

[0115] Optionally, Channel State Information (CSI) includes information reported by the receiving device to the transmitting device in a wireless communication system to describe the channel attributes of the communication link. CSI may include, but is not limited to, Precoding Matrix Indicator (PMI), Rank Indicator (RI), Channel Quality Indicator (CQI), CSI-RS Resource Indicator (CRI), and Layer Indicator (LI). It should be understood that the specific contents of CSI listed above are merely illustrative and should not constitute any limitation on this application. CSI may include one or more of the information listed above, or other information used to characterize CSI besides those listed above; this application does not impose any limitations.

[0116] 4. Scheme for channel reconstruction based on reference signal using R16 codebook:

[0117] For example, the R16 codebook is a dual-domain compressed codebook in both the spatial and frequency domains. In the frequency domain, it compresses the channels of all sub-bands, and the codebook structure satisfies formula (1):

[0118] in, It is a spatial compression matrix. This is the combination coefficient matrix. The frequency domain compression matrix is ​​defined by N1 and N2, representing the number of horizontal and vertical antenna ports of the base station, respectively. L represents the number of spatial basis vectors, and M represents the number of frequency basis vectors. For example, Figure 5 shows a schematic diagram of an R16 codebook structure, illustrating each matrix and its dimensions. Optionally, spatial-frequency dual-domain compression utilizes the sparsity of the channel in the spatial and frequency domains for quantization, reducing the number of weighting coefficients required for reporting, thereby compressing the channel matrix.

[0119] However, the R16 codebook only utilizes the sparsity of the channel in the angle-delay domain, i.e., the correlation characteristics of spatial information across different subbands, for feedback and compression. This requires feedback of the spatial and frequency domain basis and combination coefficients, resulting in significant feedback overhead. Furthermore, because the basis needs to be reported, the protocol specifies that both the spatial and frequency domain basis are Discrete Fourier Transform (DFT) codebooks, limiting the sparsity of the combination coefficient matrix W2. Additionally, in real-world channels, especially in scenarios where the channel propagation environment changes slowly, the basis changes very slowly, allowing for long-period feedback. R16, however, does not support reporting the basis and combination coefficients at different periods.

[0120] 5. Scheme for channel reconstruction based on reference signal using R18 codebook:

[0121] To sparsely represent the channel in the space-frequency domain, fully exploit its sparsity characteristics, and consider the inconsistent rates of change of different channel features over time—such as the slow transformation of path angle-delay information (space-frequency joint basis) and the rapid change of path superposition coefficients (superposition coefficients corresponding to the basis)—a codebook scheme combining long and short periods is designed for channel reconstruction based on a reference signal. This approach helps reduce feedback overhead. For example, the following descriptions address two cases: joint space-frequency compression and feedback, and independent space-frequency compression and feedback.

[0122] Scenario 1: Space-Frequency Joint Compression and Feedback:

[0123] Taking the downlink channel as an example, assuming the terminal has a single antenna, the channel matrix of the terminal satisfies formula (2):

[0124] in, It is a spatial compression matrix. For frequency domain compression matrix, The matrix is ​​a combination coefficient matrix (which is a diagonal matrix), where M is the number of base station antennas, L is the number of channel multipaths, and N is the number of frequency elements (e.g., a frequency element is a subcarrier, a resource element (RE), a resource block (RB), an RB group (RBG), or a sub-band). For example, Figure 6 is a schematic diagram of a channel matrix H represented by column vectors. It can be seen that the spatial-frequency domain representation of channels H1, H2, ..., H in Figure 6 is a matrix representation of the channels. t The column vectors h1, h2, ..., h in the spatial frequency domain can be used. t Equivalent representation. The equivalent column vector satisfies formula (3):

[0125] Where diag(C) represents the column vector formed by the diagonal elements of matrix C. ⊙ represents the Khatri-Rao product. For example, a l It is the l-th column of A. It is the Kronecker product, b l It is the l-th column of B, where l is an integer greater than 0. Matrix F * The l-th (i = 1, ..., N) column of S satisfies formula (4):

[0126] in, Let represent the Kronecker product, where [:,l] denotes the l-th column of the matrix. The above operation allows a channel represented as a matrix in the spatial-frequency domain to be represented as a spatial-frequency domain column vector.

[0127] For the channel h represented by the column vector, its statistical covariance matrix satisfies formula (5):

[0128] in, This represents the expectation of a random number / matrix, where U is the covariance matrix R. h The matrix formed by the eigenvectors of U, where the i-th column of U is R h The i-th eigenvector has the corresponding eigenvalue as the i-th element on the diagonal of the diagonal matrix Λ. The eigenvalues ​​of each column of U are the elements on the diagonal of the diagonal matrix Λ, and the elements on the diagonal of Λ are arranged in descending order. The average covariance matrix between polarizations satisfies formula (6):

[0129] Among them, h + For the channel corresponding to positive polarization, h - For the channel corresponding to negative polarization, The average covariance matrix The matrix formed by the eigenvectors of , The i-th column is The i-th eigenvector has a corresponding eigenvalue matrix. The i-th element on the diagonal, Each column corresponds to a diagonal matrix of eigenvalues. The elements on the diagonal, and If the elements on the diagonal are arranged from largest to smallest, then the instantaneous channel satisfies formula (7):

[0130] Among them, U p The matrix is ​​formed by the first P columns of the basis U. The channel exhibits sparse properties in the angular delay domain (i.e., (Only some elements are non-zero or have large values), and the angle time delay changes slowly (i.e., at different times h1, h2...h... t U can be considered to remain essentially unchanged or change slowly, while (Then it changes over time). Additionally, using Karhunen-Loeve decomposition (KL decomposition), when based on matrix R... h The eigenvectors corresponding to the P largest eigenvalues ​​of U (i.e., the first P columns of U) p When expanding h using ), its truncation statistical mean square error is minimized. Considering that the statistical covariance matrix can be approximated by the statistical covariance matrix after polarization averaging, the instantaneous channel h satisfies formula (8):

[0131] in, for The former A matrix composed of columns, This represents the Kronecker product. When designing a CSI feedback scheme, a longer period can be used for... Quantitative feedback is provided, using short-term or non-periodic methods. Provide quantitative feedback.

[0132] For example, a specific CSI compressed reporting scheme includes the following steps:

[0133] S1: The UE performs spatial-frequency joint covariance matrix statistics on the downlink channel and performs inter-polarity averaging to obtain... right Perform singular value decomposition (SVD) or eigenvalue decomposition to obtain the matrix composed of eigenvectors. UE for matrix Cut off the section and select the one with the highest energy. The corresponding eigenvalues Columns form a matrix It contains most of the channel's energy (the choice of P can be determined by the UE itself, or the gNB can specify an optional range for the UE to choose from).

[0134] S2: The matrix constructed by the UE using the DFT codebook on statistical eigenvectors To make an approximation, that is, to find W f W s C1 makes or Among them W f With W s C1 is a submatrix formed by a subset of columns of the oversampled DFT matrix, representing the beam / basis vectors in the frequency and spatial domains, respectively; Projecting W1 onto the quantization matrix can correct W1 into a statistical characteristic matrix. W calculated in this step f W s C1 is reported to the base station with a long period (optional; "long period" is used to distinguish it from "short period" in the following text, and does not necessarily mean that the reporting periods of these matrices are the same, because the time scale of each matrix may be different. For example, the rate of change of C1 over time is likely to be greater than that of W). f W s It's faster, so there can be different feedback cycle granularities.

[0135] S3: The UE calculates the codebook C2 that needs to be fed back based on the instantaneous channel h and W1C1 obtained in S2. C2 can be the projection of the instantaneous channel h onto W1C1, that is, C2 = (W1C1). H h; or C2 can be calculated in other forms (e.g., when the columns of W1C1 are not orthogonal, W1C1 needs to be orthogonalized). The UE feeds back C2 to the base station using short-period or aperiodic methods to reconstruct the downlink channel.

[0136] The above CSI compression reporting scheme, when mapped to the codebook format, satisfies formula (9):

[0137] Where ⊙ represents the KR (Khatri-Rao) product. For example, Figure 7 is a schematic diagram of matrix decomposition of a space-frequency joint channel h, where h is the space-frequency joint channel, M is the number of base station antennas (dual-polarized array), and N is the number of frequency units (subcarrier granularity, RB granularity, RBG granularity, or sub-band granularity). Since W f W s C1 is used to quantize approximations. Therefore, 2K≥P is satisfied, where K is a matrix W. s The number of columns. The DFT basis for quantizing the space-frequency joint basis.

[0138] Scenario 2: Independent space frequency compression and feedback:

[0139] Taking the downlink channel as an example, assuming the terminal has a single antenna, the channel matrix of the terminal satisfies formula (10): H≈S′C1C2C3F′ H (10)

[0140] in, It is a spatial basis, and is a matrix composed of B spatial vectors; It is a matrix consisting of F frequency domain vectors, which serves as the frequency domain basis. Let be the first superposition coefficient matrix, representing a coefficient matrix composed of multiple sets of spatial vector coefficients; The second superposition coefficient matrix represents the coefficient matrix consisting of the weighted coefficients corresponding to a set of space-frequency vectors formed by each of the B spatial vectors and each of the F frequency vectors. This is the third superposition coefficient matrix, representing a matrix composed of multiple sets of frequency domain vector coefficients. B represents the number of spatial vectors determined by the network device or terminal; K s D represents the number of weighting coefficients corresponding to each spatial vector; F represents the number of weighting coefficients corresponding to each frequency vector; and F represents the number of frequency vectors determined by the network device or terminal.

[0141] Optionally, the spatial domain vector, also known as the beam vector, spatial beam basis vector, or spatial basis vector, can have a length of M equal to the number of transmit antenna ports M along a polarization direction. M is a positive integer greater than 1. For example, if the spatial domain vector is a column vector or row vector of length M, then the M column vectors or row vectors correspond to M transmit antenna ports, which is not limited in this application. Each element in the spatial domain vector can represent the weight of each antenna port. Based on the weights of each antenna port represented by the elements in the spatial domain vector, the signals from each antenna port are linearly superimposed, which can form a region with a strong signal in one or more directions in space. Optionally, the spatial domain vector can be determined based on a DFT vector. In other words, the spatial domain vector can be a DFT vector. This spatial domain vector can, for example, be a DFT vector defined in the Type II codebook of 3GPP technical specification TS 38.214, release 15 (R15).

[0142] Optionally, a frequency domain vector, also known as a frequency domain basis vector, is used to represent the variation pattern of the channel in the frequency domain. A frequency domain vector can represent one variation pattern. Since a signal can travel from the transmitting antenna to the receiving antenna via multiple paths during wireless channel transmission, multipath delay leads to frequency-selective fading, which is a variation of the frequency domain channel. Therefore, different frequency domain vectors can be used to represent the variation pattern of the channel in the frequency domain caused by delays on different transmission paths. The length of the frequency domain vector can be determined by the number of frequency domain units to be reported configured on the network side in the reporting bandwidth, or it can be a predefined value in the protocol. This application does not limit the length of the frequency domain vector. The reporting bandwidth, for example, can refer to the CSI reporting bandwidth carried in the CSI reporting configuration in higher-layer signaling (such as RRC messages). The length of the frequency domain vector can be denoted as N, where N is a positive integer greater than 1. The frequency domain vector can be, for example, a column vector or row vector with a length including N. This application does not impose any limitations.

[0143] Optionally, the space-frequency joint basis can characterize the common features of the spatial and frequency domains; for example, the space-frequency joint basis is a matrix constructed from one or more space-frequency domain basis vectors. The space-frequency domain basis vectors can represent the channel's variation in the frequency domain and the signal characteristics in one or more spatial directions, as can be seen in the preceding descriptions of the characteristics of spatial and frequency domain vectors, which will not be repeated here.

[0144] Corresponding to the channel decomposition method shown in formula (10), the codebook form satisfies formula (11):

[0145] in, It is the spatial basis of the downlink channel determined by network devices or terminals. It is the frequency domain basis of the downlink channel determined by network devices or terminals. s The calculation method satisfies formulas (12) and (13): U s =W S C1 (13)

[0146] in, Let H be the spatial statistical covariance matrix. For R S The matrix formed by the eigenvectors of U S Each column corresponds to a diagonal matrix of eigenvalues. The elements on the diagonal, and Λ S The elements on the diagonal are arranged from largest to smallest. This represents the expectation of a random number / matrix. W fThe calculation method satisfies formulas (14) and (15):

[0147] in, Let H be the frequency domain statistical covariance matrix. For R F The matrix formed by the eigenvectors of U F Each column corresponds to a diagonal matrix of eigenvalues. The elements on the diagonal, and Λ F The elements on the diagonal are arranged from largest to smallest.

[0148] For example, Figure 8 is a schematic diagram of a space-frequency joint long-short period codebook feedback process. For example, assume the base station configuration includes a 64T dual-polarized antenna, 50RB, and uses 64 DFT column vectors for approximation. The number of columns is 13. Long-period feedback W1C1, with a period of T L Short-cycle feedback C2, with a period of T s In each long-period base feedback, ignoring the feedback amount required for W1, 64 × 13 = 832 coefficients constituting C1 need to be fed back. It can be seen that the combined space-frequency long and short-period codebook feedback has a large overhead. Furthermore, the base station also needs to configure a 32-port CSI-RS for measuring channel information, resulting in significant pilot overhead. This pilot overhead increases dramatically with the number of antennas and the frequency band.

[0149] Therefore, this application provides a communication method in which the base station uses the regional-level channel basis provided by the channel map as prior information (which may be a space-frequency joint basis U, a spatial basis U). S Frequency domain basis U F It can also be a spatial compression matrix W. s Frequency domain compression matrix W f (This application does not impose any limitations), and then the space-frequency joint basis U is sent to the UE with a long period, and the sparse CSI-RS is sent with a short period. After receiving the sparse CSI-RS, the UE calculates the superposition coefficient C2 and feeds it back with a short period, while updating and feeding back the column index value of the space-frequency joint basis, which helps to reduce feedback overhead.

[0150] To reduce the overhead and feedback overhead of the reference signal, this application provides a communication method that effectively reduces the overhead and feedback overhead of the reference signal by transmitting channel basis information based on the channel map, thereby improving the channel reconstruction accuracy.

[0151] For example, Figure 9 is a flowchart illustrating a communication method provided in this application. This method can be implemented through interaction between a first device and a second device. The first device in this application can be a terminal or a module applied to a terminal, and the second device can be a network device or a module applied to a network device. The method includes the following steps:

[0152] S101, the second device sends indication information of the first substrate; correspondingly, the first device receives the indication information of the first substrate.

[0153] For example, based on the R16 and R18 codebook schemes for channel reconstruction based on reference signals described earlier, the channel matrix of the terminal can be represented by an equivalent column vector in the spatial frequency domain. The terminal determines the channel based on CSI-RS, and the base station recovers the channel based on the quantization basis and coefficients fed back by the terminal. Therefore, in this embodiment, the second device is designed to directly send indication information of the first basis (used to indicate the first basis to the first device), thereby enabling the first device to directly obtain the basis information. Furthermore, unlike the R16 and R18 codebook schemes (where the channel basis is calculated on the terminal side and then quantized and fed back to the base station side, resulting in accuracy loss in the basis obtained by the base station side), in this embodiment, the first basis is a regional-level channel basis (a priori information) provided by the channel map. The second device can obtain a channel basis without quantization loss based on the channel map, which is beneficial for improving the accuracy of CSI reconstruction.

[0154] In one optional implementation, the indication information of the first substrate indicates the projection coefficients of the first substrate on the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate; the second device can determine the first substrate based on the projection coefficients and column index of the first substrate.

[0155] In another optional implementation, the indication information of the first basis indicates the projection coefficients of the channel covariance matrix on the quantization basis and the corresponding indices of the projection coefficients on the quantization basis; the second device can recover the channel covariance matrix based on the projection coefficients and indices of the channel covariance matrix, and then determine the first basis based on the channel covariance matrix.

[0156] The first basis consists of L columns of basis vectors, where L is a positive integer. For example, the quantization basis of the first basis can be any one of the following: a DFT codebook, a Fast Fourier Transform (FFT) codebook, an oversampled DFT codebook, an oversampled FFT codebook, or a codebook determined based on a preset rule; this application does not impose any limitation. The basis vectors are determined based on the quantization basis. For example, the basis vectors can be any one of the following: DFT basis vectors (vectors determined based on the DFT codebook), FFT basis vectors (vectors determined based on the FFT codebook), oversampled DFT basis vectors (vectors determined based on the oversampled DFT codebook), oversampled FFT basis vectors (vectors determined based on the oversampled FFT codebook), or vectors determined based on a preset rule. Assuming one or more basis vectors are one or more DFT basis vectors, the first basis is a matrix composed of L columns of DFT basis vectors selected from these one or more DFT basis vectors (that is, the elements in the first basis satisfy the preset rule and have relevant characteristics).

[0157] The column index of the quantization basis of the first basis includes the indices of the basis vectors constituting the first basis. For example, suppose the first basis is obtained by quantizing and projecting the quantization basis of the first basis. For instance, the quantization basis of the first basis could be a DFT codebook, in which case the first basis is obtained by quantizing and projecting the DFT codebook. However, the DFT codebook may have multiple DFT basis vectors arranged sequentially. Suppose the 1st, 3rd, and 5th DFT basis vectors are selected to construct the first basis, then the column index of the quantization basis of the first basis is {1, 3, 5}.

[0158] Optionally, the first basis can be a space-frequency joint basis, or a spatial basis and a frequency basis. For example, assuming the first basis is a space-frequency joint basis U, and the quantization basis of the first basis is a DFT codebook, then the indication information of the first basis indicates the projection coefficients of the space-frequency joint basis U onto the DFT codebook and the column index of the DFT codebook. It should be noted that the basis in this application can also be called a codebook; for example, the first basis can also be called the first codebook, the second basis can also be called the second codebook, and so on. This application does not impose any limitation.

[0159] Optionally, the specific implementation of the indication information of the first base includes the following:

[0160] (1) Scenario 1: The indication information of the first base includes the first base. That is, the second device directly sends the first base to the first device. For example, assuming the first base is a space-frequency joint base U, the second device uses PDCCH / PDSCH to send the space-frequency joint base corresponding to the first device to the first device. M represents the number of antennas in the second device, L represents the number of paths, and N represents the number of frequency elements (e.g., a frequency element is a subcarrier, RB, RBG, or subband). It should be noted that the values ​​in the first substrate can be in complex form, in which case amplitude and phase quantization processing needs to be performed on the complex values. The second device can then obtain and transmit the first substrate after amplitude and phase quantization.

[0161] (2) Case 2: The indication information of the first substrate includes the projection coefficients of the first substrate onto the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. That is, the second device indirectly indicates the first substrate to the first device. For example, assuming the first substrate is a space-frequency joint substrate U, the second device can use the quantization substrate B of the first substrate constructed by one or more basis vectors to quantize the space-frequency joint substrate U, and the quantization process satisfies formula (16): U=B×C 13 (16)

[0162] Where B represents the quantization basis of the first basis, C 13 C represents the projection coefficient of the first substrate onto the quantized substrate of the first substrate. 13 Its function is similar to that of the coefficient W1C1 mentioned earlier. Therefore, the indication information of the first basis includes the column index of the quantization basis of the first basis (indicating the basis vector used for quantizing the space-frequency joint basis U) and C 13 For example, suppose the first basis is the spatial basis U. S and frequency domain basis U F In this case, you can refer to the description of the independent compression and feedback process of space frequency described in Part 1 above, such as the spatial basis U. S Satisfying formula (13), using W S Quantization processing is performed; frequency domain basis U F Satisfying formula (15), using W f Quantification is performed.

[0163] Optionally, the second device can use PDCCH / PDSCH to send the projection coefficients of the first substrate onto the quantized substrate of the first substrate and the column index of the quantized substrate of the first substrate to the first device; correspondingly, the first device receives the projection coefficients of the first substrate onto the quantized substrate of the first substrate and the column index of the quantized substrate of the first substrate, thereby combining the quantized substrate B of the first substrate to reconstruct the space-frequency joint substrate U. Optionally, the quantized substrate B of the first substrate is known and the same for both the first and second devices. Optionally, the indication overhead of the second case is lower than that of the first case, but both the first and second devices need to preset (e.g., pre-store) the quantized substrate B of the first substrate.

[0164] (3) Case 3: The indication information of the first basis includes the projection coefficients of the channel covariance matrix onto the quantization basis and the corresponding indices (or position indices) of the projection coefficients onto the quantization basis. That is, the second device indirectly indicates the first basis to the first device. The first device can determine the channel covariance matrix based on the indicated projection coefficients and indices of the channel covariance matrix, and perform singular value decomposition or eigenvalue decomposition on the channel covariance matrix to obtain the first basis corresponding to the channel covariance matrix.

[0165] For example, the frequency domain statistical covariance matrix R shown in formula (14) F For example, the first device calculates R using the following formula (17). F In the frequency domain compression matrix W f Projection is performed on the surface, and the projection coefficient matrix S delay :

[0166] The second device can be derived from the projection coefficient matrix S. delay Select the K' projection coefficients with the largest quantization values ​​and distribute them, and then distribute these K' projection coefficients in the frequency domain compression matrix W. f The corresponding row and column indices.

[0167] Optionally, for the projection coefficient matrix of the channel covariance matrix on the quantization basis, the second device may only send the diagonal elements of the projection coefficient matrix. Since the diagonal elements are real numbers (the coefficients are real numbers), the indication overhead can be reduced.

[0168] For example, the projection coefficient matrix S delay The diagonal elements are:

[0169] Among them, S delay The diagonal elements are real numbers, and the projection coefficients are also real numbers. The second device can send this S. delay The top L with the largest median or quantized value delay Each projection coefficient and the preceding L delay The index ID corresponding to each projection coefficient on the quantization basis d,part Since the row index and column index of the diagonal elements are equal, row indexes and / or column indexes can be used.

[0170] Optionally, prior to S101, the following steps are also included:

[0171] The second device sends a first request message to the core network equipment, requesting to obtain the channel map, thereby acquiring the base information corresponding to the first device. For example, as shown in Figure 3, when the first device moves to any grid in the channel map, the second device can trigger the first request message to request the base information corresponding to that first device. The base information is determined based on the channel map; for example, the second device can determine the space-frequency joint base as the first base based on the path angle-delay information of the channel map. Optionally, if the core network equipment is, for example, an AMF (Advanced Management Function), the second device sends the first request message to the AMF. The AMF acts as a router for communication between the second device and the LMF / MMF (Local Management Function), so the second device requests the channel map from the LMF / MMF through the AMF. Correspondingly, the LMF / MMF can send the channel map to the second device through the AMF. Therefore, after acquiring the channel map, the second device can determine the first base based on the channel map.

[0172] S102, the second device sends the first reference signal; correspondingly, the first device receives the first reference signal.

[0173] The first reference signal is used to measure channel information, and may specifically be a downlink reference signal. This downlink reference signal may include CSI-RS, synchronization signal / physical broadcast channel block (SSB), or demodulation reference signal (DMRS), etc.

[0174] Optionally, the density of the first reference signal is positively correlated with the number of columns of the first substrate. Specifically, the density ρ of the first reference signal is proportional to the number of columns L of the first substrate; for example, the smaller L is, the smaller ρ is. It can be understood that a smaller number of columns L of the first substrate indicates fewer channel multipath propagation paths, resulting in fewer channel measurement values ​​and correspondingly fewer reference signals to be transmitted; therefore, the density ρ of the first reference signal is proportional to the number of columns L of the first substrate. For example, assuming the first substrate is a space-frequency joint substrate U, and the space-frequency joint substrate corresponding to the first device is known... Where M is the number of antennas in the second device, L is the number of channel multipaths, and N is the number of frequency units; the second device sets the density ρ of the first reference signal based on the number of columns L of the space-frequency joint substrate U, which can reduce the frequency domain granularity from N to N1, thereby reducing the overhead of the reference signal.

[0175] S103, the first device determines the first channel matrix based on the first reference signal.

[0176] S104, the first device determines the first superposition coefficient vector based on the second basis constructed by the first channel matrix and the position index of the first reference signal in the spatial frequency domain in the corresponding row of the first basis.

[0177] The first device performs channel estimation based on the first reference signal, obtaining a first channel matrix that represents the channel state information of the first reference signal in the corresponding spatial-frequency domain dimension. For example, assuming the first reference signal is a CSI-RS signal, the first device performs channel estimation on this CSI-RS signal to obtain a first channel matrix h in the spatial-frequency domain dimension. s The first channel matrix has a dimension of MN1×1, for example, h s satisfy M is the spatial granularity of the first reference signal (e.g., the number of antennas), and N1 is the frequency granularity of the first reference signal (e.g., the number of subcarriers, RBs, RBGs, or subbands).

[0178] Wherein, the position index of the first reference signal in the spatial frequency domain is represented by the second basis constructed from the corresponding row of the first basis as U. s The second basis has a dimension of MN1×L, for example, U s satisfy For example, the first device receives a first reference signal and can determine the position index of the first reference signal in the spatial frequency domain; based on the position index (M and N1) of the first reference signal in the spatial frequency domain, it obtains the row corresponding to the position index from the first substrate to form the second substrate U. s .

[0179] The first superposition coefficient vector is determined by a second basis constructed based on the position index of the first channel matrix and the first reference signal in the spatial frequency domain in the corresponding row of the first basis, satisfying formula (19): c = pinv(U s )×h s (19)

[0180] Where c is the first superposition coefficient vector, h s U is the first channel matrix. s Let pinv(A) be the second basis, and denote the pseudo-inverse of matrix A. Optionally, equation (19) is only one example; the first superposition coefficient vector can also satisfy a transformation based on equation (19), or satisfy a transformation based on h. s and U s Other generation methods are not limited in this application. The first superposition coefficient vector includes L superposition coefficients, and the dimension of the first superposition coefficient vector is L*1, where L is a positive integer; for example, c satisfies... Optionally, the superposition coefficient vector represents the projection coefficients of the channel matrix onto the basis.

[0181] S105, the first device transmits a second superposition coefficient vector and a second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0182] Among them, the second superposition coefficient vector includes K superposition coefficients, and the K superposition coefficients are the K elements with the largest amplitudes in the first superposition coefficient vector. K is a positive integer less than or equal to L. For example, it is known that the first superposition coefficient vector includes L superposition coefficients. Assuming that the K elements with the largest amplitudes among the L superposition coefficients form the second superposition coefficient vector c′, then c′ satisfies K satisfies 0 < K ≤ L. It can be understood that the K elements with the largest amplitudes among the L superposition coefficients satisfy that the K coefficients are greater than the L - K superposition coefficients other than the K coefficients among the L superposition coefficients; for example, assuming that the L superposition coefficients are 1, 3, 4, 6, 2, 5, then L = 6; assuming K = 3, then the K elements with the largest amplitudes among all the elements of the L superposition coefficients include 4, 5, 6, that is, the second superposition coefficient vector includes three elements, namely 4, 5, 6.

[0183] Among them, the second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector. For example, assuming that the L superposition coefficients are 1, 3, 4, 6, 2, 5, then L = 6; assuming K = 3, then the second superposition coefficient vector includes three superposition coefficients, namely 4, 5, 6. The position indices of these three superposition coefficients in the first superposition coefficient vector are 3, 6, 4 respectively, that is, the second basis selection vector includes three elements, namely 3, 4, 6.

[0184] Optionally, the first device transmits the second superposition coefficient vector and the second basis selection vector. For example, it can be that the first device uses PUCCH / PUSCH to transmit the second superposition coefficient vector and the second basis selection vector to the second device. Optionally, the first device can report the second superposition coefficient vector in a short period, and the first device can report the second basis selection vector in a short period or a long period. This application does not make a limit.

[0185] It can be seen that the first device only needs to feedback K superposition coefficients (similar to the short-period superposition coefficients shown in FIG. 8), and the position indices of the K superposition coefficients in the first superposition coefficient vector (indicating the position indices in the first basis), which is beneficial to reducing the feedback overhead. For example, since the second device knows the channel map and the first basis, the first device only needs to feedback the position indices in the first basis, rather than the indices of one or more basis vectors constituting the first basis and the long-period coefficients (such as the long-period superposition coefficients shown in FIG. 8), thereby reducing the feedback overhead.

[0186] In this embodiment, the first substrate is a regional-level channel substrate provided by the channel map. The second device sends the first substrate as prior information to the first device, which helps reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first substrate, which helps reduce feedback overhead.

[0187] I. Channel basis update method provided in this application:

[0188] Specifically, the first device can multiply the second superposition coefficient vector and the third basis to obtain the second channel matrix, which is to recover the CSI information. Furthermore, the first device can determine the historical channel basis associated with the historical CSI information based on the recovered CSI information and historical CSI information, and update the channel basis based on the historical channel basis (such as updating the first basis).

[0189] For example, the channel basis update method provided in this application includes the following steps:

[0190] (1) The first device multiplies the second superposition coefficient vector and the third basis to obtain the second channel matrix. The third basis is formed by selecting K position indices from the second basis vector and placing them in the corresponding columns of the first basis. For example, the second channel matrix satisfies formula (20): h=U′×c′ (20)

[0191] Where h is the second channel matrix, U′ is the third basis, and c′ is the second superposition coefficient vector. For example, the second device selects K position indices from the second basis selection vector, obtains the corresponding columns of these K position indices in the first basis, and constructs the third basis U′ using these corresponding columns. The dimension of the third basis is MN×K. For example, U′ satisfies... Optionally, the second channel matrix may also satisfy a transformation of formula (20), or satisfy other implementation methods for generating the second channel matrix based on the second superposition coefficient vector and the third basis, which are not limited in this application.

[0192] (2) The first device determines the fourth basis based on multiple third channel matrices. The third channel matrix is ​​the channel state information in the spatial-frequency domain obtained by channel estimation based on the second reference signal. The second reference signal is a reference signal received before the first reference signal, and the second reference signal and the first reference signal are of the same type. For example, the second reference signal is a reference signal received before the first reference signal, that is, the second reference signal is a historical reference signal; the second reference signal can be a reference signal received at the moment before the first device received the first reference signal, or it can be multiple reference signals received at several moments before receiving the second reference signal, which is not limited in this application. Furthermore, the second reference signal and the first reference signal are of the same type (for example, if the first reference signal is CSI-RS, then the second reference signal is also CSI-RS). The first device performs channel estimation based on the second reference signal to obtain the third channel matrix in the spatial-frequency domain. Since the statistical covariance matrix of the channel h represented by the column vector satisfies formula (5), the statistical covariance matrix of the third channel matrix satisfies formula (21):

[0193] Among them, R h U is the statistical covariance matrix of the third channel matrix. h The covariance matrix R h The matrix formed by the eigenvectors (i.e., the fourth basis).

[0194] (3) The first device determines the subspace where the fourth base and the first base intersect as the first common subspace. The subspace where the fourth base and the first base intersect is also called the common subspace of the fourth base and the first base. For example, the fourth base U... h The common subspace of the first basis U is denoted as V (that is, the first common subspace is V), and any vector v in V satisfies formula (22):

[0195] Among them, P U =U(U H U) -1 U H Let U be the projection matrix of U. For U h The projection matrix.

[0196] (4) The first device determines a first non-common subspace, which includes the subspace in the fourth basis excluding the first common subspace. The subspace in the fourth basis excluding the first common subspace is also called a non-common subspace, or a subspace in the fourth basis orthogonal to the first common subspace. For example, the fourth basis U... hThe non-common subspace D, excluding the first common subspace V, satisfies formula (23):

[0197] Where D is the first non-public subspace, This represents the direct sum of a subspace.

[0198] (5) The first device sends indication information of the first non-public subspace; correspondingly, the second device receives the indication information of the first non-public subspace. The indication information of the first non-public subspace indicates the projection coefficients of the first non-public subspace onto the quantization basis of the first non-public subspace and the column index of the quantization basis of the first non-public subspace. The first non-public subspace is composed of L1 column vectors. For example, the quantization basis of the first non-public subspace is any one of a DFT codebook, an FFT codebook, an oversampled DFT codebook, an oversampled FFT codebook, or a codebook determined based on a preset rule, and the column vectors of the first non-public subspace are determined based on the aforementioned codebooks.

[0199] Optionally, the implementation of the indication information of the first non-public subspace and the indication information of the first basis are similar; for example, the indication information of the first non-public subspace includes the first non-public subspace itself. That is, the first device directly sends the first non-public subspace D to the second device. Another example is that the indication information of the first non-public subspace includes the projection coefficients of the first non-public subspace onto the quantization basis of the first non-public subspace and the column index of the quantization basis of the first non-public subspace. That is, the first device indirectly indicates the first non-public subspace to the second device. Assume that the first non-public subspace D can use an oversampled DFT basis W. d Perform projection quantization (i.e., the quantization basis of the first non-common subspace is the oversampled DFT basis W). d If the first non-common subspace D satisfies formula (24): D = W d C d (twenty four)

[0200] Among them, C d This represents the projection coefficients of D on the oversampled DFT basis. Based on equation (24), the indication information of the first non-common subspace may include these projection coefficients C. d And the column index of the quantization basis of the first non-common subspace. Optional, the oversampled DFT basis W d Both the first and second devices are known and identical.

[0201] (6) The second device performs Schmitt orthogonalization on the first basis and the first non-common subspace to obtain the fifth basis. For example, the second device receives indication information of the first non-common subspace, which includes projection coefficients C. dThe second device can reconstruct the first non-common subspace D=W, and the column index of the quantization basis of the first non-common subspace. d C d And determine that the fifth basis satisfies formula (25): U p =oth{[UW d C d ]} (25)

[0202] Among them, U p This represents the fifth basis, with dimensions MN×(K+L1), for example, U p satisfy oth{A} represents the Schmitt orthogonalization of each column of matrix A. This orthogonalization is necessary because quantization may destroy the orthogonality between the columns of the basis.

[0203] Optionally, the second device sends indication information for the fifth base station. The implementation of the indication information for the fifth base station is similar to that for the first base station; for example, if the indication information for the fifth base station includes the fifth base station, then the second device sends the fifth base station U to the core network equipment. p Correspondingly, the core network equipment receives the fifth base station U... p For example, the indication information of the fifth basis includes the projection coefficients of the fifth basis onto the quantization basis of the fifth basis and the column index of the quantization basis of the fifth basis. Optionally, the second device may send indication information of the first non-common subspace (e.g., direct indication D or indication W). d and C d If the first base U is known to the core network device, then after receiving the indication information from the first non-common subspace, the core network device can also determine the fifth base. That is, the second device indirectly indicates the fifth base to the core network device. Optionally, the core network device may be, for example, an AMF, which acts as a router for communication between the second device and the LMF / MMF. In this case, the second device sends the fifth base U to the LMF / MMF through the AMF. p Optionally, the LMF / MMF can be based on a fifth substrate U. p Update the channel map; for example, based on the path angle-delay information corresponding to the fifth basis, update the path angle-delay information of the corresponding grid in the channel map.

[0204] Optionally, the first, second, third, fourth, or fifth basis described in Parts II and III above are basis of the same type, namely: a space-frequency joint basis, or a spatial basis and a frequency basis. The space-frequency joint basis is a matrix constructed from one or more space-frequency basis vectors; the spatial basis is a matrix constructed from one or more spatial basis vectors; and the frequency basis is a matrix constructed from one or more frequency basis vectors. For example, assuming the first basis is a space-frequency joint basis, then the first basis is a matrix constructed from one or more space-frequency basis vectors, which can characterize the common characteristics of the spatial and frequency domains; or, for example, assuming the first basis is a spatial basis and a frequency basis, then the first basis includes a matrix constructed from one or more spatial basis vectors and a matrix constructed from one or more frequency basis vectors (e.g., a set of matrices), respectively characterizing the characteristics of the spatial and frequency domains.

[0205] In this embodiment, the first device can determine the historical channel base associated with the historical CSI information based on the recovered CSI information and the historical CSI information, and update and report the channel base based on the historical channel base, so that the second device and the core network equipment can obtain the updated channel base information, which is beneficial to improving the accuracy of channel estimation.

[0206] II. The interaction process between the first and second devices when using different reference signals and when the channel base is updated:

[0207] Example 1: Assuming the first reference signal is CSI-RS, and a scheme that does not update the channel basis:

[0208] In this example, the second device uses the regional channel basis provided by the channel map as prior information (for example, the first basis could be the space-frequency joint basis U, the spatial basis U). S Frequency domain basis U F It can also be a spatial compression matrix W. s Frequency domain compression matrix W f (Example 1 uses the space-frequency joint base U as an example) and sends out the regional channel base and the first reference signal; correspondingly, the first device calculates the short-period coefficients based on the regional channel base and the first reference signal and reports the short-period coefficients and the position index on the first base. The second device recovers the full-dimensional CSI based on the full-dimensional channel base, short-period coefficients and the position index on the first base provided by the map.

[0209] For example, Figure 10 is a schematic diagram of a downlink channel reconstruction process enabled by combining channel map with CSI-RS according to this application. This process is implemented through interaction between a first device, a second device, and core network equipment. The core network equipment in this application can be an AMF / LMF / MMF. The process includes the following steps:

[0210] S201, the second device sends a first request message to the core network equipment, which requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map; correspondingly, the core network equipment receives the first request message.

[0211] S202, the core network device sends a first response message to the second device, the first response message including a channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0212] For example, as shown in Figure 3, when the first device moves to any grid in the channel map, the second device can trigger a first request message to request the acquisition of the entire channel map, or to request the acquisition of the base information corresponding to the first device in the channel map. The base information is determined based on the channel map. For example, the space-frequency joint base can be determined based on the path angle-delay information of the channel map; therefore, the space-frequency joint base corresponding to the first device is determined based on the path angle-delay information of the grid where the first device is located. Optionally, the core network equipment includes, for example, AMF / LMF / MMF. The interaction between the second device and the core network equipment can be referred to the corresponding description in S101, which will not be repeated here.

[0213] S203, the second device sends indication information of the first substrate; correspondingly, the first device receives the indication information of the first substrate.

[0214] The specific implementation of S202 can be referred to the corresponding description in S101. For example, assuming the first substrate is a space-frequency joint substrate U, the second device uses PDCCH / PDSCH to send the space-frequency joint substrate corresponding to the first device to the first device. Or send the column index of the first substrate on the first substrate's quantization substrate and C to the first device. 13 This will not be elaborated upon here.

[0215] Optionally, when the first basis is a spatial basis U s Frequency domain basis U F It can also be a spatial compression matrix W. s Frequency domain compression matrix W f At the same time, the processing procedure is similar to that described in S101. For example, assume that the first basis includes the spatial basis U. S and frequency domain basis U F The second device sends the corresponding spatial base U to the first device. S and frequency domain basis U F Or send a spatial base U to the first device S and frequency domain basis U FThe projection coefficients of the quantization basis B of the first basis, and the column index of the first quantization basis.

[0216] S204, the second device sends a CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0217] The specific implementation of S203 can be referred to the corresponding description in S102. For example, the second device sends a CSI-RS signal to the first device for downlink channel measurement. Optionally, the density ρ of the CSI-RS signal is proportional to the number of columns L of the first substrate. For example, the second device can reduce the density of the CSI-RS signal, thereby reducing the overhead of the CSI-RS signal.

[0218] S205, the first device determines the first channel matrix based on the CSI-RS signal.

[0219] S206, the first device determines the first superposition coefficient vector based on the second basis constructed by the first channel matrix and the position index of the CSI-RS signal in the spatial frequency domain in the corresponding row of the first basis.

[0220] The specific implementation of S205 and S206 can be referred to the corresponding descriptions in S103 and S104. For example, the first device estimates the corresponding first channel matrix based on the received CSI-RS signal. The corresponding row of the first substrate is found based on the spatial frequency domain position index of the CSI-RS signal to form the second substrate. Thus, the first superposition coefficient vector c is determined.

[0221] S207, the first device determines the second superposition coefficient vector and the second basis selection vector based on the first superposition coefficient vector.

[0222] S208, the first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0223] The specific implementation of S207 and S208 can be referred to the corresponding description in S105. For example, the first device selects the K superposition coefficients with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determines the K position indices of the K superposition coefficients in the first superposition coefficient vector to form a second basis selection vector. The first device sends the second superposition coefficient vector (including the K superposition coefficients) and the second basis selection vector (including the K index values) to the second device.

[0224] S209, the second device multiplies the second superposition coefficient vector and the second basis to obtain the second channel matrix.

[0225] The specific implementation of S209 can be found in the description of the second channel matrix in Part III, and will not be repeated here. Therefore, the second device realizes the recovery of CSI information.

[0226] Optionally, when the first reference signal is another downlink reference signal (such as SSB / DMRS) and the channel map is not updated, the specific implementation process is similar to that in Example 1. For example, the first reference signal can be replaced by another downlink reference signal instead of CSI-RS, while the other processes remain unchanged. This will not be elaborated here.

[0227] In this example, the first basis is a regional channel basis provided by the channel map. The second device sends the first basis as prior information to the first device, which helps to reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first basis, which reduces feedback overhead compared to feeding back the entire channel basis.

[0228] Example 2: Assuming the first reference signal is CSI-RS, and a scheme for updating the channel map:

[0229] Example 2 is based on Example 1, and adds a process in which the first device calculates the statistical channel base based on the historical CSI reconstruction results, updates and reports the newly added channel base information, thereby realizing the updating of channel base information and improving the accuracy of channel reconstruction.

[0230] For example, Figure 11 is a schematic diagram of a channel map combined with CSI-RS enabling downlink channel reconstruction and channel basis update process provided in this application. This process is implemented through interaction between a first device, a second device, and core network equipment. The process includes the following steps:

[0231] S301, the second device sends a first request message to the core network equipment, which requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map; correspondingly, the core network equipment receives the first request message.

[0232] S302, the core network device sends a first response message to the second device, the first response message including a channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0233] S303, the second device sends indication information of the first substrate; correspondingly, the first device receives the indication information of the first substrate.

[0234] S304, the second device sends a CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0235] S305, the first device determines the first channel state information based on the CSI-RS signal.

[0236] S306, the first device determines the first superposition coefficient vector based on the first channel state information corresponding to the CSI-RS signal and the second basis constructed by the corresponding row of the first basis in the spatial frequency domain position index of the CSI-RS signal.

[0237] S307, the first device determines the second superposition coefficient vector and the second basis selection vector based on the first superposition coefficient vector.

[0238] S308, the first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0239] S309, the second device multiplies the second superposition coefficient vector and the third basis to obtain the second channel matrix.

[0240] The specific implementation methods of S301-S309 can be referred to the corresponding descriptions in S101-S105 and S201-S209, and will not be repeated here.

[0241] S310, the first device determines the fourth basis based on the third channel matrix.

[0242] The specific implementation of this step can be found in the description of the fourth basis and the third channel matrix in Part III. For example, the third channel matrix is ​​the channel state information in the spatial frequency domain obtained by channel estimation based on the second reference signal; the second reference signal is a reference signal received before the first reference signal, that is, the second reference signal is a historical reference signal; the second reference signal and the first reference signal are reference signals of the same type (for example, if the first reference signal is CSI-RS, then the second reference signal is also CSI-RS); the fourth basis satisfies formula (21), and other related descriptions, which will not be repeated here.

[0243] S311, the first device determines the common subspace where the fourth base and the first base intersect as the first common subspace.

[0244] S312, the first device determines a first non-public subspace, the first non-public subspace including the subspace in the fourth base excluding the first public subspace.

[0245] The specific implementations of S311 and S312 can be found in the description of the first non-common subspace, the first common subspace, and the common subspace where the fourth basis intersects with the first basis in Part III. For example, the first non-common subspace D satisfies formula (23), and the first common subspace V is the fourth basis U. h The common subspace of V with the first basis U, any vector v in V satisfies formula (22), and other related descriptions, which will not be repeated here.

[0246] S313, the first device sends the indication information of the first non-public subspace; correspondingly, the second device receives the indication information of the first non-public subspace.

[0247] The specific implementation of S313 can be found in the description of the indication information of the first non-public subspace in Part III. For example, the first device may directly send the first non-public subspace D to the second device, or send the projection coefficients of the quantization basis of the first non-public subspace and the column index of the quantization basis of the first non-public subspace, as well as other related descriptions, to the second device, which will not be repeated here.

[0248] S314, the second device performs Schmitt orthogonalization on the first substrate and the first non-common subspace to obtain the fifth substrate.

[0249] S315, the second device sends the instruction information of the fifth base station to the core network equipment.

[0250] For specific implementation details of S314 and S315, please refer to the description of the fifth base and its indication information in Part III. For example, the fifth base U p It satisfies formula (25), and other related descriptions, which will not be repeated here.

[0251] Optionally, when the first reference signal is another downlink reference signal (such as SSB / DMRS) and the channel map is not updated, the specific implementation process is similar to that in Example 2. For example, the first reference signal can be replaced by another downlink reference signal instead of CSI-RS, while the other processes remain unchanged. This will not be elaborated here.

[0252] In Example 2, the first base is a regional-level channel base provided by the channel map. The second device sends the first base as prior information to the first device, which helps reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first base, reducing feedback overhead compared to feeding back the entire channel base. Moreover, the first device can update and report the channel base based on historical CSI information and recovered CSI information, which facilitates further updating of the channel map and improves its accuracy.

[0253] Example 3: Assuming the first reference signal is CSI-RS, and the first device transmits a third reference signal, a scheme for the second device to perform channel estimation based on the first and third reference signals is proposed:

[0254] Example 3 is based on Example 1, but adds the function of the first device sending a third reference signal (such as an uplink reference signal SRS) so that the second device can perform channel estimation based on the third reference signal and recover the CSI process, which is beneficial to improving the CSI reconstruction accuracy.

[0255] For example, Figure 12 is a schematic diagram of a downlink channel reconfiguration process enabled by combining channel map data with CSI-RS and SRS, as provided in this application. This process is implemented through interaction between a first device, a second device, and core network equipment. The process includes the following steps:

[0256] S401, the second device sends a first request message to the core network equipment, which requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map; correspondingly, the core network equipment receives the first request message.

[0257] S402, the core network device sends a first response message to the second device, the first response message including a channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0258] S403, the second device sends indication information of the first substrate; correspondingly, the first device receives the indication information of the first substrate.

[0259] S404, the second device sends a CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0260] S405, the first device determines the first channel matrix based on the CSI-RS signal.

[0261] S406, the first device determines the first superposition coefficient vector based on the second basis constructed by the first channel matrix and the position index of the CSI-RS signal in the spatial frequency domain in the corresponding row of the first basis.

[0262] S407, the first device determines the second superposition coefficient vector and the second basis selection vector based on the first superposition coefficient vector.

[0263] S408, the first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0264] The specific implementation methods of S401-S408 can be found in the corresponding descriptions in S101-S105 and S201-S208, and will not be repeated here.

[0265] S409, the second device sends the first instruction information; correspondingly, the first device receives the first instruction information.

[0266] S410, the first device sends a third reference signal based on the first instruction information; correspondingly, the second device receives the third reference signal.

[0267] The third reference signal is used to measure channel information, and may specifically be an uplink reference signal. For example, the uplink reference signal may include SRS, etc., and this application does not limit it.

[0268] The first indication information indicates the frequency domain location of the third reference signal. For example, assuming the third reference signal is an SRS, the first indication information indicates the frequency domain location of the SRS, such as indicating the frequency domain unit carrying the SRS (e.g., RE / RB).

[0269] Optionally, the first indication information may also indicate the resource pattern of the third reference signal. For example, assuming the third reference signal is SRS, the second device may indicate the resource pattern (e.g., SRS pattern) of the uplink reference signal to the first device through the first indication information.

[0270] Optionally, the first indication information indicates the density of the third reference signal; the density of the third reference signal is positively correlated with the length of the second superposition coefficient vector. Specifically, the density of the third reference signal is proportional to the length of the second superposition coefficient vector. For example, the smaller the length of the second superposition coefficient vector, the fewer the number of channel multipaths, and the fewer channel measurements are required; correspondingly, the fewer reference signals need to be transmitted, and the smaller the density of the third reference signal. Optionally, the second device can set the density of the third reference signal based on the length of the second superposition coefficient vector, for example, reducing the spatial granularity of the third reference signal from M to M², and the frequency granularity from N to N², thereby reducing the overhead of the reference signal.

[0271] S411, the second device determines the fourth channel matrix based on the third reference signal.

[0272] S412, the second device determines the third superposition coefficient vector based on the sixth basis constructed by the fourth channel matrix and the position index of the third reference signal in the spatial frequency domain in the corresponding row of the first basis.

[0273] The second device can perform channel estimation based on the third reference signal, obtaining a fourth channel matrix that represents the channel state information of the third reference signal in the spatial-frequency domain. For example, assuming the third reference signal is an SRS signal, the first device performs channel estimation on this SRS signal, obtaining a fourth channel matrix in the spatial-frequency domain. The fourth channel matrix has a dimension of M²N²×1, for example, satisfy M2 is the spatial granularity of the third reference signal, and N2 is the frequency granularity of the third reference signal.

[0274] Wherein, the position index of the third reference signal in the spatial frequency domain is used to construct the sixth basis corresponding to the row of the first basis. The sixth basis has a dimension of M²N²×L, for example, satisfy For example, the second device receives the third reference signal and can determine the position index of the third reference signal in the spatial frequency domain; based on the position index (M2 and N2) of the third reference signal in the spatial frequency domain, it obtains the row corresponding to the position index from the first substrate to form the sixth substrate. The sixth basis has the same number of columns as the first basis.

[0275] The third superposition coefficient vector is determined by the sixth basis constructed based on the fourth channel matrix and the position index of the third reference signal in the spatial frequency domain in the corresponding row of the first basis, satisfying formula (26):

[0276] Among them, c srs This is the third superposition coefficient vector. This is the fourth channel matrix. Let pinv(A) be the sixth basis, and denote the pseudo-inverse of matrix A. Optionally, formula (26) is only one example; the third superposition coefficient vector can also satisfy a transformation based on formula (26), or satisfy a transformation based on... and Other generation methods are not limited in this application. The third superposition coefficient vector includes E superposition coefficients, and the dimension of the third superposition coefficient vector is E*1, where E is a positive integer; for example, c srs satisfy

[0277] S413, the second device determines the fourth superposition coefficient vector and the fourth basis selection vector.

[0278] The fourth superposition coefficient vector includes F superposition coefficients, which are the F elements with the largest amplitudes in the third superposition coefficient vector. F is a positive integer less than or equal to E. The fourth basis selection vector includes the position indices of the F superposition coefficients in the third superposition coefficient vector (i.e., including F index values). It is understandable that the specific implementation of the fourth superposition coefficient vector and the fourth basis selection vector is similar to that of the second superposition coefficient vector and the second basis selection vector; please refer to the corresponding descriptions above, which will not be repeated here.

[0279] S414, the second device multiplies the fourth superposition coefficient vector and the seventh basis to obtain the fifth channel matrix.

[0280] The seventh basis is formed by selecting F positions from the fourth basis vector and finding their corresponding columns in the fifth basis. For example, similar to formula (20), the fifth channel matrix satisfies formula (27): h srs =U′ p×c′ srs (27)

[0281] Among them, h srs The fifth channel matrix, U′ p For the seventh basis, c′ srs This is the fourth superposition coefficient vector. For example, the second device selects F position indices from the fourth basis selection vector, obtains the corresponding columns of these F position indices in the fifth basis, and constructs the seventh basis U′ from these corresponding columns. p The seventh basis has dimensions MN×F, for example, U′ p satisfy Optionally, the fifth channel matrix can also satisfy the transformation of formula (27), or satisfy other implementation methods for generating the fifth channel matrix based on the fourth superposition coefficient vector and the seventh basis, which are not limited in this application.

[0282] In Example 3, the first base is a regional-level channel base provided by the channel map. The second device sends the first base as prior information to the first device, which helps reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first base, which reduces feedback overhead compared to feeding back the entire channel base. Additionally, the first device can also send an uplink reference signal, enabling the second device to recover the CSI based on the uplink and downlink reference signals, thus improving CSI reconstruction accuracy.

[0283] Example 4: Assuming the first reference signal is CSI-RS, and the first device transmits a third reference signal, a scheme for the second device to perform channel estimation and channel basis update based on the first and third reference signals:

[0284] Example 4 is based on Example 3, and adds a process for the second device to calculate the statistical channel base based on the historical CSI reconstruction results, update and report the newly added channel base information, thereby realizing the updating of channel base information and improving the accuracy of channel reconstruction.

[0285] For example, Figure 13 is a schematic diagram of a channel map combined with CSI-RS and SRS to enable downlink channel reconstruction and channel basis update process provided in this application. This process is implemented through interaction between a first device, a second device, and core network equipment. The process includes the following steps:

[0286] S501, the second device sends a first request message to the core network equipment, which requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map; correspondingly, the core network equipment receives the first request message.

[0287] S502, the core network device sends a first response message to the second device, the first response message including a channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0288] S503, the second device sends indication information of the first substrate; correspondingly, the first device receives the indication information of the first substrate.

[0289] S504, the second device sends a CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0290] S505, the first device determines the first channel matrix based on the CSI-RS signal.

[0291] S506, the first device determines the first superposition coefficient vector based on the second basis constructed by the first channel matrix and the position index of the CSI-RS signal in the spatial frequency domain in the corresponding row of the first basis.

[0292] S507, the first device determines the second superposition coefficient vector and the second basis selection vector based on the first superposition coefficient vector.

[0293] S508 The first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0294] S509, the second device sends the first instruction information; correspondingly, the first device receives the first instruction information.

[0295] S510, the first device sends a third reference signal based on the first instruction information; correspondingly, the second device receives the third reference signal.

[0296] The specific implementation methods of S501-S510 can be found in the corresponding descriptions in S101-S105 and S401-S410, and will not be repeated here.

[0297] S511, the second device determines the fourth channel matrix based on the third reference signal.

[0298] For example, assuming the third reference signal is an SRS signal, the first device performs channel estimation on this SRS signal to obtain a fourth channel matrix in the spatial frequency domain. The fourth channel matrix has a dimension of M²N²×1, for example, satisfy M2 is the spatial granularity of the third reference signal, and N2 is the frequency granularity of the third reference signal.

[0299] S512, the second device determines the eighth basis based on multiple sixth channel matrices.

[0300] The sixth channel matrix is ​​the channel state information in the spatial-frequency domain obtained by channel estimation based on the fourth reference signal. The fourth reference signal is a reference signal received before the third reference signal, and the fourth reference signal and the third reference signal are reference signals of the same type. For example, the fourth reference signal is a reference signal received before the third reference signal, that is, the fourth reference signal is a historical reference signal; the fourth reference signal can be a reference signal received at the moment before the second device receives the third reference signal, or it can be multiple reference signals received at several moments before the third reference signal, which is not limited in this application. Furthermore, the fourth reference signal and the third reference signal are reference signals of the same type (for example, if the third reference signal is SRS, then the fourth reference signal is also SRS). The second device performs channel estimation based on the fourth reference signal to obtain the sixth channel matrix in the spatial-frequency domain. Since the statistical covariance matrix of the channel h represented by the column vector satisfies formula (5), the statistical covariance matrix of the sixth channel matrix also satisfies formula (21).

[0301] S513, the second device determines the common subspace where the eighth base and the first base intersect as the second common subspace.

[0302] S514, the first device determines the second non-public subspace, which includes the subspace in the eighth base excluding the second public subspace.

[0303] The common subspace where the eighth basis and the first basis intersect is also called the second common subspace. For example, any vector v in the second common subspace also satisfies formula (22). The subspace in the eighth basis excluding the second common subspace is also called the second non-common subspace, or the subspace in the eighth basis that is orthogonal to the second common subspace. For example, the second non-common subspace in the eighth basis excluding the second common subspace also satisfies formula (23).

[0304] S515, the second device performs Schmitt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis.

[0305] S516, the second device sends the indication information of the ninth base station; correspondingly, the core network equipment receives the indication information of the ninth base station.

[0306] For example, similar to formula (25), the second device determines that the ninth basis satisfies formula (28): U p′ =oth{[U p D′]} (28)

[0307] Among them, U p′This represents the ninth basis, whose dimensions are MN×(K+L1+L2), for example, U p′ satisfy U p Let D denote the fifth basis, and D′ denote the second non-common subspace.

[0308] Optionally, the second device sends indication information for the ninth base station. The implementation of the indication information for the ninth base station is similar to that of the indication information for the first base station; for example, if the indication information for the ninth base station includes the ninth base station, then the second device sends the ninth base station U to the core network equipment. p′ Correspondingly, the core network equipment receives the ninth base station U p′ For example, the indication information of the ninth basis includes the projection coefficients of the ninth basis onto the quantization basis of the ninth basis and the column index of the quantization basis of the ninth basis. Optionally, the second device may send indication information of the second non-common subspace (e.g., directly indicating D′ or indicating the column index of the quantization basis of the second non-common subspace and the projection coefficients of the second non-common subspace), and the fifth basis U p If the core network equipment already knows the ninth base, it can also determine the ninth base after receiving the indication information from the second non-common subspace. That is, the second device indirectly indicates the ninth base to the core network equipment. Optionally, the core network equipment may be, for example, an AMF (Advanced Management Function), which acts as a router for communication between the second device and the LMF / MMF. In this case, the second device sends the ninth base to the LMF / MMF through the AMF. Optionally, the LMF / MMF can update the channel map based on the ninth base; for example, it can update the path angle-delay information of the corresponding grid in the channel map based on the path angle-delay information corresponding to the ninth base.

[0309] S517, the second device determines the fifth superposition coefficient vector based on the fourth channel matrix and the corresponding row of the SRS signal's spatial frequency position in the ninth basis.

[0310] The fifth superposition coefficient vector includes P superposition coefficients, where P is a positive integer. The specific implementation of this step can be found in the corresponding description in S104. For example, the second device searches for the corresponding row of the ninth basis based on the position index of the SRS signal in the spatial frequency domain to determine that the fifth superposition coefficient vector satisfies formula (29):

[0311] Among them, c srs ′ is the fifth superposition coefficient vector, This is the fourth channel matrix. It is formed by the position index of the third reference signal in the spatial frequency domain corresponding to the row of the ninth basis.

[0312] S518, the second device determines the sixth superposition coefficient vector and the sixth basis selection vector.

[0313] The sixth superposition coefficient vector includes Q superposition coefficients, which are the Q elements with the largest magnitudes in the fifth superposition coefficient vector. The sixth basis selection vector includes the position indices of the Q superposition coefficients in the fifth superposition coefficient vector, where Q is a positive integer less than or equal to P.

[0314] The specific implementation of this step can be found in the description in S104. For example, the sixth superposition coefficient vector is c′. srs Similar to the implementation of the second superposition coefficient vector, the implementation of the sixth basis selection vector is similar to that of the second basis selection vector.

[0315] S519, the second device multiplies the sixth superposition coefficient vector and the tenth basis to obtain the sixth channel matrix.

[0316] The tenth basis is formed by selecting Q positions from the sixth basis vector and finding their corresponding columns in the ninth basis. For example, the specific implementation of this step can be found in the implementation of the second channel matrix described in Part III, similar to formula (20), where the sixth channel matrix satisfies formula (30): h′ srs =U′ p′ ×c′ srs (30)

[0317] Where, h′ srs The sixth channel matrix, c′ srs U′ is the sixth superposition coefficient vector. p′ This forms the tenth basis. For example, the second device selects Q position indices from the vector chosen from the sixth basis, obtains the corresponding columns of these Q position indices in the ninth basis, and constructs the tenth basis U′ from these corresponding columns. p′ The tenth basis has dimensions MN×Q, for example, U′ p′ satisfy Optionally, the sixth channel matrix can also satisfy the transformation of formula (30), or satisfy other implementation methods for generating the sixth channel matrix based on the sixth superposition coefficient vector and the tenth basis, which are not limited in this application.

[0318] In Example 4, the first base is a regional-level channel base provided by the channel map. The second device sends the first base as prior information to the first device, which helps reduce reference signal overhead. Furthermore, the first device only feeds back the position index and short-period superposition coefficients of the first base, further reducing feedback overhead. Additionally, the first device can send uplink reference signals so that the second device can recover the CSI based on the uplink and downlink reference signals, improving CSI reconstruction accuracy. Moreover, the first device can update and report the channel base based on historical CSI information and the recovered CSI information, facilitating further updates to the channel map and improving its accuracy.

[0319] Example 5: Scheme for a second device to perform channel estimation and channel basis update based on a third reference signal, assuming the first device transmits a third reference signal:

[0320] The channel estimation scheme provided in Example 5 can be a scheme in which the second device directly performs channel estimation and channel basis update based on SRS (not based on CSI-RS), which can improve the accuracy of channel reconstruction.

[0321] For example, Figure 14 is a schematic diagram of a channel map combined with SRS-enabled channel reconfiguration and channel basis update process provided in this application. This process is implemented through interaction between a first device, a second device, and core network equipment. The process includes the following steps:

[0322] S601, the second device sends a first request message to the core network equipment, which requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map; correspondingly, the core network equipment receives the first request message.

[0323] S602, the core network device sends a first response message to the second device, the first response message including a channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0324] The specific implementation methods of S601 and S602 can be found in the corresponding descriptions in S101 and S102 and S201 and S202, which will not be repeated here.

[0325] S603, the second device sends the first instruction information; correspondingly, the first device receives the first instruction information.

[0326] S604, the first device sends an SRS signal based on the first instruction information; correspondingly, the second device receives the SRS signal.

[0327] S605, the second device determines the fourth channel matrix based on the SRS signal.

[0328] S606, the second device determines the eighth basis based on multiple sixth channel matrices.

[0329] S607, the second device determines the common subspace where the eighth base and the first base intersect as the second common subspace.

[0330] S608, the first device determines the second non-public subspace, the second non-public subspace including the subspace in the eighth base excluding the second public subspace.

[0331] S609, the second device performs Schmitt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis.

[0332] S610, the second device sends the indication information of the ninth base station; correspondingly, the core network equipment receives the indication information of the ninth base station.

[0333] S611, the second device determines the fifth superposition coefficient vector based on the fourth channel matrix and the corresponding row of the SRS signal's spatial frequency position in the ninth basis.

[0334] S612, the second device determines the sixth superposition coefficient vector and the sixth basis selection vector.

[0335] S613, the second device multiplies the sixth superposition coefficient vector and the tenth basis to obtain the sixth channel matrix.

[0336] The specific implementation methods of S603-S613 can be found in the corresponding descriptions in S509-S519, and will not be repeated here.

[0337] In Example 5, the first basis is a regional-level channel basis provided by the channel map. The second device sends the first basis as prior information to the first device, which helps reduce reference signal overhead. Furthermore, without considering the downlink reference signal, the first device can send an uplink reference signal, enabling the second device to perform channel reconstruction based on the uplink reference signal SRS. Moreover, the first device can update the channel basis based on information from historical and current SRS signals, which facilitates further updating of the channel map and improves its accuracy.

[0338] It is understood that, in order to achieve the functions in the above embodiments, the base station and terminal include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0339] Figures 15 and 16 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of terminals or base stations in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device can be the terminal 120 shown in Figure 1, the base station 110 shown in Figure 1, or a module (such as a chip) applied to a terminal or base station.

[0340] As shown in Figure 15, the communication device 1500 includes a processing unit 1510 and a transceiver unit 1520. The communication device 1500 is used to implement the functions of a terminal or base station in the method embodiments shown in Figures 9 to 14. Optionally, the transceiver unit 1520 can also be referred to as a communication unit. Optionally, the transceiver unit includes a transmitting unit and a receiving unit, wherein the transmitting unit is used to transmit signals and the receiving unit is used to receive signals.

[0341] For example, when the communication device 1500 is used to implement the terminal function in the method embodiment shown in FIG9: the transceiver unit 1520 is used to receive indication information of a first substrate, the indication information of which indicates the projection coefficients of the first substrate on the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. The processing unit 1510 is used to determine and record the first substrate. The transceiver unit 1520 is also used to receive a first reference signal, and the processing unit 1510 is also used to determine a first channel matrix based on the first reference signal. The processing unit 1510 is also used to determine a first superposition coefficient vector based on a second substrate constructed from the first channel matrix and the position index of the first reference signal in the spatial frequency domain in the corresponding row of the first substrate. The processing unit 1510 is also used to select the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and to determine the position indexes of the K superposition coefficient vectors in the first superposition coefficient vector to form a second substrate selection vector. The transceiver unit 1520 is also used to transmit the second superposition coefficient vector and the second substrate selection vector.

[0342] For example, when the communication device 1500 is used to implement the function of the network device in the method embodiment shown in FIG9: the transceiver unit 1520 is used to send indication information of the first substrate, the indication information of the first substrate indicating the projection coefficients of the first substrate on the quantization substrate of the first substrate and the column index of the quantization substrate of the first substrate. The transceiver unit 1520 is also used to send a first reference signal, so that the receiver of the first reference signal can perform channel estimation based on the first reference signal to obtain a first channel matrix, and the receiver of the first reference signal can determine a first superposition coefficient vector based on the second substrate constructed by the first channel matrix and the position index of the first reference signal in the spatial frequency domain in the corresponding row of the first substrate, thereby determining the K superposition coefficient vectors with the largest amplitude selected from the first superposition coefficient vector to form a second superposition coefficient vector, and the position index of the K superposition coefficient vectors in the first superposition coefficient vector to form a second substrate selection vector. The transceiver unit 1520 is also used to receive the second superposition coefficient vector and the second substrate selection vector. The processing unit 1510 is used to process the data received by the transceiver unit 1520.

[0343] For a more detailed description of the processing unit 1510 and the transceiver unit 1520, please refer to the relevant description in the method embodiment shown in FIG9.

[0344] Optionally, when the communication device 1500 is used to implement the functions of a terminal or base station in the method embodiments of Figures 10 to 14, a more detailed description of the processing unit 1510 and the transceiver unit 1520 can be found in the relevant descriptions in the method embodiments shown in Figures 10 to 14, and will not be repeated here.

[0345] As shown in Figure 16, the communication device 1600 includes a processor 1610 and an interface circuit 1620. The processor 1610 and the interface circuit 1620 are coupled to each other. It is understood that the interface circuit 1620 can be a transceiver or an input / output interface. Optionally, the communication device 1600 may also include a memory 1630 for storing instructions executed by the processor 1610, or storing input data required by the processor 1610 to execute instructions, or storing data generated after the processor 1610 executes instructions. Sometimes, the interface circuit 1620 can also be understood as part of the processor 1610, in which case the communication device 1600 includes the processor 1610.

[0346] When the communication device 1600 is used to implement the method shown in FIG9, the processor 1610 is used to implement the functions of the processing unit 1510, and the interface circuit 1620 is used to implement the functions of the transceiver unit 1520. Optionally, when the communication device 1600 is used to implement the methods shown in FIG10 to FIG14, the implementation methods of the processor 1610 and the interface circuit 1620 are as described in the corresponding descriptions in the method embodiments, and will not be repeated here.

[0347] When the aforementioned communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from the base station, which can be understood as the information being first received by other modules in the terminal (such as an RF module or antenna), and then sent to the terminal chip by these modules. The terminal chip sends information to the base station, which can be understood as the information being first sent to other modules in the terminal (such as an RF module or antenna), and then sent to the base station by these modules.

[0348] When the aforementioned communication device is a chip applied to a base station, the base station chip implements the functions of the base station in the above method embodiments. The base station chip receives information from the terminal, which can be understood as the information being first received by other modules in the base station (such as an RF module or antenna), and then sent to the base station chip by these modules. The base station chip sends information to the terminal, which can be understood as the information being sent down to other modules in the base station (such as an RF module or antenna), and then sent to the terminal by these modules.

[0349] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be RAN nodes or terminals, or modules within RAN nodes or terminals. Information transmission and reception can be between RAN nodes and terminals, such as between a base station and a terminal; between two RAN nodes, such as between a CU and a DU; or between different modules within a single device, such as between a terminal chip and other modules of the terminal, or between a base station chip and other modules of the base station.

[0350] It is understood that the processor in the embodiments of this application may 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), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor.

[0351] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a base station or terminal. The processor and storage medium can also exist as discrete components in a base station or terminal.

[0352] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0353] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0354] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0355] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects. "Including at least one of A, B, and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

Claims

1. A communication method, characterized in that, The method includes: The system receives indication information of a first basis, which indicates the projection coefficients of the first basis onto the quantization basis of the first basis and the column index of the quantization basis of the first basis; the first basis is composed of L column basis vectors, where L is a positive integer. Receive a first reference signal and determine a first channel matrix based on the first reference signal; Based on the first channel matrix and the second basis constructed from the corresponding rows of the first basis in the spatial frequency domain position index of the first reference signal, a first superposition coefficient vector is determined, wherein the dimension of the first channel matrix is ​​MN1*1, the dimension of the second basis is MN1*L, M is the number of antenna ports receiving the first reference signal, and N1 is the number of frequency domain units carrying the first reference signal; the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, M and N1 are positive integers, and L is less than or equal to MN1; Send a second superposition coefficient vector and a second basis selection vector. The second superposition coefficient vector includes K superposition coefficients, which are the K elements with the largest amplitudes in the first superposition coefficient vector. The second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector, where K is a positive integer less than or equal to L.

2. A communication method, characterized in that, The method includes: Receive indication information of a first basis, wherein the indication information of the first basis indicates the projection coefficients of the channel covariance matrix on the quantization basis and the index of the projection coefficients on the quantization basis; Based on the projection coefficients and indices of the indicated channel covariance matrix, the channel covariance matrix is ​​determined; singular value decomposition or eigenvalue decomposition is performed on the channel covariance matrix to obtain the first basis corresponding to the channel covariance matrix; the first basis is composed of L column basis vectors, where L is a positive integer; Receive a first reference signal and determine a first channel matrix based on the first reference signal; Based on the first channel matrix and the second basis constructed from the corresponding rows of the first basis in the spatial frequency domain position index of the first reference signal, a first superposition coefficient vector is determined, wherein the dimension of the first channel matrix is ​​MN1*1, the dimension of the second basis is MN1*L, M is the number of antenna ports receiving the first reference signal, and N1 is the number of frequency domain units carrying the first reference signal; the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, M and N1 are positive integers, and L is less than or equal to MN1; Send a second superposition coefficient vector and a second basis selection vector. The second superposition coefficient vector includes K superposition coefficients, which are the K elements with the largest amplitudes in the first superposition coefficient vector. The second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector, where K is a positive integer less than or equal to L.

3. The method according to claim 1 or 2, characterized in that, The method further includes: The second channel matrix is ​​obtained by multiplying the second superposition coefficient vector and the third basis; the third basis is composed of K position indices in the second basis selection vector in the corresponding columns of the first basis.

4. The method according to claim 1 or 2, characterized in that, The method further includes: The fourth basis is determined based on the third channel matrix, which is the channel state information in the spatial frequency domain obtained by channel estimation based on the second reference signal. The second reference signal is a reference signal received before the first reference signal, and the second reference signal and the first reference signal are reference signals of the same type. A first non-public subspace is determined, which includes the subspaces in the fourth base excluding the first public subspace, and the first public subspace is the public subspace where the fourth base and the first base intersect. Send indication information for the first non-public subspace, which indicates the projection coefficients of the first non-public subspace on the quantization basis of the first non-public subspace and the column index of the quantization basis of the first non-public subspace; the first non-public subspace is composed of L1 column basis vectors, where L1 is a positive integer.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Receive first indication information, which indicates the frequency domain position for transmitting the third reference signal; The third reference signal is sent based on the first indication information.

6. The method according to any one of claims 1 to 4, characterized in that, The first substrate, the second substrate, the third substrate, the fourth substrate, or the fifth substrate are substrates of the same type, wherein the substrates of the same type are: a space-frequency joint substrate, or a spatial domain substrate and a frequency domain substrate; Wherein, the space-frequency joint basis is a matrix constructed by one or more space-frequency domain basis vectors; the space-domain basis is a matrix constructed by one or more space-domain basis vectors, and the frequency-domain basis is a matrix constructed by one or more frequency-domain basis vectors.

7. The method according to any one of claims 1 to 4, characterized in that, The basis vector is any one of the following: Discrete Fourier Transform (DFT) basis vector, Fast Fourier Transform (FFT) basis vector, Oversampled DFT basis vector, Oversampled FFT basis vector, or a vector determined based on a preset rule.

8. A communication method, characterized in that, The method includes: Send indication information for the first basis, which indicates the projection coefficients of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis; the first basis is composed of L column basis vectors, where L is a positive integer; Send the first reference signal; The system receives a second superposition coefficient vector and a second basis selection vector. The second superposition coefficient vector includes K superposition coefficients, which are the K elements with the largest amplitudes in the first superposition coefficient vector. The second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector. The first superposition coefficient vector is obtained by constructing a second basis based on the first channel matrix and the corresponding rows of the position indices of the first reference signal in the spatial frequency domain in the first basis. The first channel matrix is ​​determined based on the first reference signal. The dimension of the first channel matrix is ​​MN1*1, the dimension of the second basis is MN1*L, M is the number of antenna ports transmitting the first reference signal, and N1 is the number of frequency domain units carrying the first reference signal. The first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, M and N1 are positive integers, L is less than or equal to MN1, and K is a positive integer less than or equal to L.

9. A communication method, characterized in that, The method includes: The first basis indication information is transmitted, which indicates the projection coefficients of the channel covariance matrix on the quantization basis and the corresponding indices of the projection coefficients on the quantization basis. The projection coefficients and indices of the channel covariance matrix are used by the receiving end to recover the channel covariance matrix and determine the first basis. The first basis is composed of L column basis vectors, where L is a positive integer. Send the first reference signal; The system receives a second superposition coefficient vector and a second basis selection vector. The second superposition coefficient vector includes K superposition coefficients, which are the K elements with the largest amplitudes in the first superposition coefficient vector. The second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector. The first superposition coefficient vector is obtained by constructing a second basis based on the first channel matrix and the corresponding rows of the position indices of the first reference signal in the spatial frequency domain in the first basis. The first channel matrix is ​​determined based on the first reference signal. The dimension of the first channel matrix is ​​MN1*1, the dimension of the second basis is MN1*L, M is the number of antenna ports transmitting the first reference signal, and N1 is the number of frequency domain units carrying the first reference signal. The first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, M and N1 are positive integers, L is less than or equal to MN1, and K is a positive integer less than or equal to L.

10. The method according to claim 8 or 9, characterized in that, The method further includes: The second channel matrix is ​​obtained by multiplying the second superposition coefficient vector and the third basis; the third basis is composed of K position indices in the second basis selection vector in the corresponding columns of the first basis.

11. The method according to claim 8 or 9, characterized in that, The method further includes: Receive indication information of the first non-public subspace, the indication information of the first non-public subspace indicating the projection coefficients of the first non-public subspace on the quantization basis of the first non-public subspace and the column index of the quantization basis of the first non-public subspace; the first non-public subspace is composed of L1 column basis vectors, where L1 is a positive integer; The fifth basis is obtained by performing Schmidt orthogonalization on the first basis and the first non-common subspace. Send indication information of the fifth basis, which indicates the fifth basis, or indicates the projection coefficient of the fifth basis on the quantization basis of the fifth basis and the column index of the quantization basis of the fifth basis; the fifth basis is composed of (L+L1) column vectors.

12. The method according to any one of claims 8 to 11, characterized in that, The method further includes: Send a first indication message, which indicates the frequency domain position for sending the third reference signal; Receive the third reference signal.

13. The method according to any one of claims 8 to 11, characterized in that, The first basis, the second basis, the third basis, the fourth basis, or the fifth basis are basis of the same type, wherein the basis of the same type is: a space-frequency joint basis, or a spatial basis and a frequency basis; the space-frequency joint basis is a matrix constructed by one or more space-frequency basis vectors; the spatial basis is a matrix constructed by one or more spatial basis vectors, and the frequency basis is a matrix constructed by one or more frequency basis vectors.

14. The method according to any one of claims 8 to 11, characterized in that, The basis vector is any one of the following: Discrete Fourier Transform (DFT) basis vector, Fast Fourier Transform (FFT) basis vector, Oversampled DFT basis vector, Oversampled FFT basis vector, or a vector determined based on a preset rule.

15. A communication device, characterized in that, It includes a communication unit and a processing unit, the communication unit and the processing unit being used to perform the method as described in any one of claims 1 to 7 or 8 to 14.

16. A communication device, characterized in that, The device includes a processor and an interface circuit, the interface circuit being used to receive signals from other communication devices and transmit them to the processor or to send signals from the processor to other communication devices, the processor being used to implement the method as described in any one of claims 1 to 7 or 8 to 14 via logic circuits or executing code instructions.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 7 or 8 to 14.

18. A chip system, characterized in that, The chip system includes a processor and an interface, the processor being configured to execute a computer program that enables the chip system to implement the method as described in any one of claims 1 to 7 or 8 to 14.

19. A computer program product, characterized in that, Includes instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 1 to 7 or 8 to 14.

20. A communication system, characterized in that, The communication system includes means for performing the method according to any one of claims 1 to 7, and means for performing the method according to any one of claims 8 to 14.

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