Communication method and apparatus for feeding back precoding matrix

Abstract

A communication method and apparatus for feeding back a precoding matrix, which are applied to the technical field of communications. The method comprises: a terminal sending first information, wherein the first information is used for indicating at least one precoding matrix and / or at least one precoding vector; the at least one precoding matrix comprises a precoding matrix of each of at least one sub-band, the at least one sub-band is a portion of all sub-bands occupied by a reference signal, and the at least one precoding matrix is used for performing interpolation by means of a first interpolation method, so as to obtain precoding matrices respectively corresponding to all the sub-bands; and the at least one precoding vector comprises a precoding vector of each of at least one antenna port, the at least one antenna port is a portion of all antenna ports occupied by the reference signal, and the at least one precoding vector is used for performing interpolation by means of a second interpolation method, so as to obtain precoding vectors respectively corresponding to all the antenna ports. The method can reduce the overheads of feeding back a precoding matrix.

Description

A communication method and apparatus for feedback precoding matrices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510200503.1, filed on February 21, 2025, entitled "A Communication Method and Apparatus for Feedback Precoding Matrix", the entire contents of which are incorporated herein by reference. Technical Field

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

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

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

[0006] This application provides a communication method and apparatus for feedback precoding matrices, which reduces the overhead of feedback precoding matrices.

[0007] Firstly, embodiments of this application provide a communication method that can be applied to a terminal or a device capable of being applied to a terminal. Optionally, the device capable of being applied to a terminal may be a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, also known as a baseband chip, or a system-on-chip (SoC) chip or system-in-package (SIP) chip containing a modem core), chip system, or processor, or may be a logic node, logic module, or software capable of implementing all or part of the terminal's functions. The device capable of being applied to a terminal can exist independently; for example, it can be independently manufactured, sold, or used. For ease of description, the following explanation uses a terminal as an example.

[0008] The method may include: a terminal receiving a reference signal and sending first information, the first information being used to indicate at least one precoding matrix and / or at least one precoding vector. The at least one precoding matrix may be determined based on the reference signal, and the at least one precoding matrix includes the precoding matrix of each subband in at least one subband. The at least one subband may be a portion of all subbands occupied (or corresponding to, or used by) the reference signal. The at least one precoding matrix can be interpolated using a first interpolation method to obtain the precoding matrices corresponding to each of the subbands. Accordingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain the precoding matrices corresponding to each of the subbands. The at least one precoding vector may be determined based on a reference signal. The at least one precoding vector includes a precoding vector for each of at least one antenna port. The at least one antenna port may be a portion of all antenna ports occupied (or corresponding to, or used) by the reference signal. The at least one precoding vector can be interpolated using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. Accordingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to each of the antenna ports.

[0009] For example, the reference signal may be a channel state information reference signal (CSI-RS).

[0010] For example, the first interpolation method is a manifold interpolation method, and / or the second interpolation method is a manifold interpolation method.

[0011] Optionally, all subbands occupied (or corresponding to, or used) by the reference signal can be replaced with all subbands in the downlink resources configured (or scheduled, or indicated, or allocated) by the access network device for the terminal. And / or, all antenna ports occupied (or corresponding to, or used) by the reference signal can be replaced with all antenna ports configured (or scheduled, or indicated, or allocated) by the access network device for the terminal for transmitting downlink data.

[0012] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can include: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands; correspondingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands. And / or, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports, which may include: the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to each of the antenna ports; correspondingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to each of the antenna ports.

[0013] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can be replaced by: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. Accordingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. And / or, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. This can be replaced by: the at least one precoding vector can be used to interpolate using the second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports. Accordingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports.

[0014] In this method, if the first information is used to indicate the precoding matrix of a portion of all subbands occupied (or corresponding to, or used) by the reference signal, the access network device can interpolate the precoding matrix of that portion of the subbands to obtain the precoding matrices corresponding to each of the subbands. In this way, the terminal does not need to feed back the precoding matrix corresponding to each of the subbands, thereby reducing the overhead of feeding back the precoding matrix.

[0015] When applied to massive MIMO (Multi-Match MIMO) technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each sub-band increases with the number of antenna ports. This method can feed back only the precoding matrix for a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. Similarly, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can also feed back only the precoding matrix for a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix.

[0016] Alternatively, since the terminal may not need to feed back the precoding matrix for each subband, this method can improve the accuracy of the fed-back precoding matrix without changing the overhead of the fed-back precoding matrix, thereby improving the accuracy of the precoding matrix recovered by the access network device.

[0017] In this method, if the first information is used to indicate the precoding vectors of a portion of all antenna ports occupied (or corresponding to, or used) by the reference signal, the access network device can interpolate the precoding vectors of that portion of antenna ports to obtain the precoding vectors corresponding to each of the antenna ports. In this way, the terminal does not need to feed back the precoding vector corresponding to each of the antenna ports, thereby reducing the overhead of feeding back the precoding vectors and, consequently, the overhead of feeding back the precoding matrix.

[0018] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each subband increases with the number of antenna ports. This method can feed back only the precoding vectors of a portion of the antenna ports, without feeding back the precoding vectors of every single antenna port, thereby significantly reducing the overhead of feeding back the precoding vectors, and consequently significantly reducing the overhead of the feedback precoding matrix.

[0019] Alternatively, since the terminal may not need to feed back the precoding vector for each antenna port, this method can improve the accuracy of the fed-back precoding vector without changing the overhead of the fed-back precoding vector, thereby improving the accuracy of the precoding vector recovered by the access network equipment.

[0020] Secondly, embodiments of this application provide a communication method that can be applied to an access network device or a device capable of being applied to an access network device. Optionally, the device capable of being applied to an access network device may be a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core, chip system, or processor) that can be used in the access network device, or may be a logical node, logical module, or software capable of implementing all or part of the functions of the access network device. The device capable of being applied to the access network device can exist independently; for example, it can be independently manufactured, sold, or used. For ease of description, the following explanation uses an access network device as an example.

[0021] The method may include: an access network device transmitting a reference signal and receiving first information, the first information being used to indicate at least one precoding matrix and / or at least one precoding vector. The at least one precoding matrix may be determined based on the reference signal, and the at least one precoding matrix includes the precoding matrix of each subband in at least one subband. The at least one subband may be a portion of all subbands occupied (or corresponding to, or used by) the reference signal. The at least one precoding matrix can be interpolated using a first interpolation method to obtain the precoding matrices corresponding to each of the subbands. Accordingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain the precoding matrices corresponding to each of the subbands. The at least one precoding vector may be determined based on a reference signal. The at least one precoding vector includes a precoding vector for each of at least one antenna port. The at least one antenna port may be a portion of all antenna ports occupied (or corresponding to, or used) by the reference signal. The at least one precoding vector can be interpolated using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. Accordingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to each of the antenna ports.

[0022] For example, the reference signal may be CSI-RS.

[0023] For example, the first interpolation method is a manifold interpolation method, and / or the second interpolation method is a manifold interpolation method.

[0024] Optionally, all subbands occupied (or corresponding to, or used) by the reference signal can be replaced with all subbands in the downlink resources configured (or scheduled, or indicated, or allocated) by the access network device for the terminal. And / or, all antenna ports occupied (or corresponding to, or used) by the reference signal can be replaced with all antenna ports configured (or scheduled, or indicated, or allocated) by the access network device for the terminal for transmitting downlink data.

[0025] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can include: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands; correspondingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands. And / or, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports, which may include: the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to each of the antenna ports; correspondingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to each of the antenna ports.

[0026] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can be replaced by: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. Accordingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. And / or, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. This can be replaced by: the at least one precoding vector can be used to interpolate using the second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports. Accordingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports.

[0027] In this method, if the first information is used to indicate the precoding matrix of a portion of all subbands occupied (or corresponding to, or used) by the reference signal, the access network device can interpolate the precoding matrix of that portion of the subbands to obtain the precoding matrices corresponding to each of the subbands. In this way, the terminal does not need to feed back the precoding matrix corresponding to each of the subbands, thereby reducing the overhead of feeding back the precoding matrix.

[0028] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each sub-band increases with the number of antenna ports. This method can feed back only the precoding matrix of a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. Similarly, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can also feed back only the precoding matrix of a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix.

[0029] Alternatively, since the terminal may not need to feed back the precoding matrix for each subband, this method can improve the accuracy of the fed-back precoding matrix without changing the overhead of the fed-back precoding matrix, thereby improving the accuracy of the precoding matrix recovered by the access network device.

[0030] In this method, if the first information is used to indicate the precoding vectors of a portion of all antenna ports occupied (or corresponding to, or used) by the reference signal, the access network device can interpolate the precoding vectors of that portion of antenna ports to obtain the precoding vectors corresponding to each of the antenna ports. In this way, the terminal does not need to feed back the precoding vector corresponding to each of the antenna ports, thereby reducing the overhead of feeding back the precoding vectors and, consequently, the overhead of feeding back the precoding matrix.

[0031] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each subband increases with the number of antenna ports. This method can feed back only the precoding vectors of a portion of the antenna ports, without feeding back the precoding vectors of every single antenna port, thereby significantly reducing the overhead of feeding back the precoding vectors, and consequently significantly reducing the overhead of the feedback precoding matrix.

[0032] Alternatively, since the terminal may not need to feed back the precoding vector for each antenna port, this method can improve the accuracy of the fed-back precoding vector without changing the overhead of the fed-back precoding vector, thereby improving the accuracy of the precoding vector recovered by the access network equipment.

[0033] Based on the first or second aspect, in one possible design, the method further includes: the access network device sending first indication information, and correspondingly, the terminal receiving the first indication information. The first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all subbands, and / or, the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports.

[0034] Optionally, the first indication information can be used to instruct the terminal to feed back precoding matrix indications for a portion of the subbands among all subbands. This can be understood as: the first indication information can be used to instruct the terminal to feed back precoding matrices for a portion of the subbands among all subbands; or, the first indication information can be used to instruct the terminal to send precoding matrix indications for a portion of the subbands among all subbands. And / or, the first indication information can be used to instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports among all antenna ports. This can be understood as: the first indication information can be used to instruct the terminal to feed back precoding vectors for a portion of the antenna ports among all antenna ports; or, the first indication information can be used to instruct the terminal to send precoding matrix indications for a portion of the antenna ports among all antenna ports.

[0035] This design allows the terminal to feed back precoding matrix indications for some sub-bands and / or some antenna ports to the access network device, based on the device's instructions, thus saving the overhead of feeding back the precoding matrix. Furthermore, in this design, the operation of the terminal feeding back precoding matrix indications for some sub-bands and / or some antenna ports to the access network device can be instructed by the access network device itself, thereby improving the flexibility of the access network device in managing the terminal.

[0036] Based on the first or second aspect, in one possible design, the method further includes: the terminal sending first indication information, and correspondingly, the access network device receiving the first indication information. The first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all subbands, and / or, the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports.

[0037] This design allows the terminal to instruct the access network device to provide precoding matrix indications for certain sub-bands and / or antenna ports. This enables the access network device to interpolate the precoding matrices of the sub-bands to obtain the precoding matrices for all sub-bands, and / or interpolate the precoding vectors of the antenna ports to obtain the precoding vectors for all antenna ports. Furthermore, in this design, the operation of the terminal providing precoding matrix indications for the sub-bands and / or antenna ports can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0038] Based on the first or second aspect, in one possible design, if the first condition is met, the terminal sends the first information; accordingly, the access network device receives the first information.

[0039] Optionally, the first condition includes at least one of the following: the number of transmit antennas of the access network device is greater than or equal to a first threshold; the number of receive antennas of the terminal is greater than or equal to a second threshold; the number of subbands in all subbands is greater than or equal to a third threshold; the number of antenna ports in all antenna ports is greater than or equal to a fourth threshold; the number of streams corresponding to downlink data transmission is less than or equal to a fifth threshold; or, the number of streams corresponding to downlink data transmission is greater than or equal to a sixth threshold.

[0040] This design allows the terminal to determine, based on a first condition, the precoding matrix of a portion of the subband and / or the precoding vector of a portion of the antenna ports to be fed back to the access network device. This saves on the overhead of feeding back the precoding vectors, and consequently, the overhead of feeding back the precoding matrix. Furthermore, in this design, the access network device may not instruct the terminal to feed back the precoding matrix of a portion of the subband and / or the precoding vector of a portion of the antenna ports, thereby reducing signaling overhead. Moreover, in this design, the operation of the terminal feeding back the precoding matrix of a portion of the subband and / or the precoding vector of a portion of the antenna ports to the access network device can be determined by the terminal itself, thus improving the flexibility of terminal operation.

[0041] Based on the first or second aspect, in one possible design, where the first information is used to indicate at least one precoding matrix, the method further includes: the access network device sending second information, and correspondingly, the terminal receiving the second information. The second information can be used to indicate at least one of the following: at least one subband, or the number of subbands in at least one subband. For example, the second information can indicate the at least one subband. Alternatively, the second information can indicate: the at least one subband, and the number of subbands in the at least one subband. With this design, the terminal can accurately determine at least one subband and / or the number of subbands in the at least one subband based on the second information. Furthermore, in this design, the at least one subband and / or the number of subbands in the at least one subband can be indicated by the access network device, thereby improving the flexibility of the access network device in managing the terminal.

[0042] Based on the first or second aspect, in one possible design, where the first information is used to indicate at least one precoding matrix, the method further includes: the terminal sending second information, and correspondingly, the access network device receiving the second information. The second information can be used to indicate at least one of the following: at least one subband, or the number of subbands in at least one subband.

[0043] Optionally, when the terminal sends the second information and the access network device receives the second information, the method further includes: the access network device sending third information; correspondingly, the terminal receiving the third information. The third information can be used to indicate candidate subbands, which include the at least one subband. Optionally, the candidate subband including the at least one subband can be understood as: the at least one subband being selected (or determined) from the candidate subbands; correspondingly, the terminal can select (or determine) the at least one subband from the candidate subbands.

[0044] In some implementations, the candidate subband includes one or more subbands, and the at least one subband may include some or all of the subbands in the one or more subbands. For example, the candidate subband includes subband #1, subband #3, subband #5 and subband #7, and the at least one subband may include subband #1, subband #3 and subband #5.

[0045] In other implementations, the candidate subband may include multiple sets of subbands, and the at least one subband may include a subband from one of the multiple sets of subbands. For example, the candidate subband may include subband set #1 and subband set #2, and the at least one subband may include a subband from subband set #1.

[0046] This design allows the terminal to indicate at least one subband and / or the number of subbands within that at least one subband to the access network device, enabling the access network device to interpolate the precoding matrices of a subset of the subbands to obtain the precoding matrices of all the subbands. Furthermore, in this design, the at least one subband and / or the number of subbands within that at least one subband can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0047] Based on the first or second aspect, in one possible design, when the first information is used to indicate at least one precoding matrix, the at least one subband and / or the number of subbands in at least one subband is related to at least one of the following: the number of transmit antennas of the access network device; the number of receive antennas of the terminal; the number of subbands in all subbands; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the frequency domain; or, the degree of change of the channel in the frequency domain. With this design, the terminal can accurately determine the at least one subband and / or the number of subbands in at least one subband. Furthermore, in this design, the access network device may not need to indicate the at least one subband and / or the number of subbands in at least one subband, thereby reducing signaling overhead. Moreover, in this design, the at least one subband and / or the number of subbands in at least one subband can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0048] Based on the first or second aspect, in one possible design, where the first information is used to indicate at least one precoded vector, the method further includes: the access network device sending fourth information, and correspondingly, the terminal receiving the fourth information. The fourth information can be used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports among the at least one antenna port. For example, the fourth information can indicate the at least one antenna port. Also, for example, the fourth information can indicate: the at least one antenna port, and the number of antenna ports among the at least one antenna port. With this design, the terminal can accurately determine the at least one antenna port and / or the number of antenna ports among the at least one antenna port based on the fourth information. Furthermore, in this design, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be indicated by the access network device, thereby improving the flexibility of the access network device in managing the terminal.

[0049] Based on the first or second aspect, in one possible design, where the first information is used to indicate at least one precoded vector, the method further includes: the terminal sending fourth information, and correspondingly, the access network device receiving the fourth information. The fourth information can be used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports among the at least one antenna port.

[0050] Optionally, when the terminal sends fourth information and the access network device receives the fourth information, the method further includes: the access network device sending fifth information; correspondingly, the terminal receiving the fifth information. The fifth information can be used to indicate candidate antenna ports, which include at least one antenna port. Optionally, the inclusion of the at least one antenna port in the candidate antenna ports can be understood as: the at least one antenna port being selected (or determined) from the candidate antenna ports; correspondingly, the terminal can select (or determine) the at least one antenna port from the candidate antenna ports.

[0051] In some implementations, the candidate antenna port includes one or more antenna ports, and the at least one antenna port may include some or all of the one or more antenna ports. For example, the candidate antenna port includes antenna port #1, antenna port #3, antenna port #5, and antenna port #7, and the at least one antenna port may include antenna port #1, antenna port #3, and antenna port #5.

[0052] In other implementations, the candidate antenna port may include multiple sets of antenna ports, and the at least one antenna port may include an antenna port from one of the multiple sets of antenna ports. For example, the candidate antenna port may include antenna port set #1 and antenna port set #2, and the at least one antenna port may include an antenna port from antenna port set #1.

[0053] This design allows the terminal to indicate the at least one antenna port and / or the number of antenna ports among the at least one antenna port to the access network device, enabling the access network device to interpolate the precoding vectors of some antenna ports to obtain the precoding vectors of all antenna ports. Furthermore, in this design, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0054] Based on the first or second aspect, in one possible design, when the first information is used to indicate at least one precoding vector, the at least one antenna port and / or the number of antenna ports among the at least one antenna port is related to at least one of the following: the number of transmit antennas of the access network device; the number of receive antennas of the terminal; the number of antenna ports among all antenna ports; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the spatial domain; or the degree of change of the channel in the spatial domain. With this design, the terminal can accurately determine the at least one antenna port and / or the number of antenna ports among the at least one antenna port. Furthermore, in this design, the access network device may not indicate the at least one antenna port and / or the number of antenna ports among the at least one antenna port, thereby reducing signaling overhead. Moreover, in this design, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0055] Based on the first or second aspect, in one possible design, at least one precoding matrix is ​​used for interpolation using a first interpolation method to obtain precoding matrices corresponding to each subband. This may include: the first and second precoding matrices in the at least one precoding matrix are used to obtain a third precoding matrix using the first interpolation method; correspondingly, the access network device can interpolate the first and second precoding matrices in the at least one precoding matrix using the first interpolation method to obtain the third precoding matrix. Wherein, the first precoding matrix is ​​the precoding matrix of the first subband in the at least one subband, the second precoding matrix is ​​the precoding matrix of the second subband in the at least one subband, and the third precoding matrix is ​​the precoding matrix of the third subband, where the third subband is the subband other than at least one subband among all the subbands. With this design, the access network device can accurately determine the third precoding matrix based on the first and second precoding matrices in the at least one precoding matrix.

[0056] Based on the first or second aspect, in one possible design, the first and second precoding matrices in the at least one precoding matrix are used to obtain a third precoding matrix through a first interpolation method, including: the first and second precoding vectors are used to obtain a third precoding vector through the first interpolation method; correspondingly, the access network device can interpolate the first and second precoding vectors through the first interpolation method to obtain the third precoding vector. Wherein, the first precoding vector is the precoding vector in the first precoding matrix corresponding to the first flow, the second precoding vector is the precoding vector in the second precoding matrix corresponding to the first flow, and the third precoding vector is the precoding vector in the third precoding matrix corresponding to the first flow. Optionally, the first flow can be any flow corresponding to one or more of the first, second, or third precoding matrices. For example, the first flow can be any flow corresponding to the third precoding matrix. Or, for example, the first flow can be any flow corresponding to the first, second, and third precoding matrices. Through this design, the access network device can accurately determine the third precoding vector based on the first and second precoding vectors. When the first flow is any flow in the third precoding matrix, the access network device can obtain the precoding vector corresponding to each flow in the third precoding matrix using this method, thereby accurately determining the third precoding matrix. Furthermore, in this design, the access network device can determine the precoding vector corresponding to each flow in the third precoding matrix flow-by-flow, resulting in lower computational complexity.

[0057] Based on the first or second aspect, in one possible design, the first and second precoding matrices in the at least one precoding matrix are used to obtain a third precoding matrix through a first interpolation method. This includes: the first and second matrices are used to obtain the third matrix through the first interpolation method; correspondingly, the access network device can interpolate the first and second matrices using the first interpolation method to obtain the third matrix. The first matrix includes precoding vectors corresponding to multiple flows in the first precoding matrix, the second matrix includes precoding vectors corresponding to the multiple flows in the second precoding matrix, and the third matrix includes precoding vectors corresponding to the multiple flows in the third precoding matrix. The multiple flows are some or all of the flows corresponding to the third precoding matrix. Through this design, the access network device can accurately determine the third matrix based on the first and second matrices, thereby accurately determining the third precoding matrix. Furthermore, in this design, the access network device can interpolate by combining flows to obtain the third matrix, which reduces the computational load compared to interpolating for each flow individually.

[0058] Based on the first or second aspect, in one possible design, the third sub-band is located between the first and second sub-bands in the frequency domain. With this design, the precoding matrix of the third sub-band is obtained by interpolating the precoding matrices of the two sub-bands located on either side of the third sub-band in the frequency domain, thereby improving the accuracy and precision of the determined precoding matrix of the third sub-band.

[0059] Based on the first or second aspect, in one possible design, the third sub-band is located on the same side of the first and second sub-bands in the frequency domain. With this design, the precoding matrix of the third sub-band is obtained by interpolating the precoding matrices of the two sub-bands located on the same side of the third sub-band in the frequency domain. This allows for accurate determination of the precoding matrix of the third sub-band, and enables the determination of the precoding matrix of the third sub-band even when the first information does not indicate the precoding matrices of the two sub-bands located on either side of the third sub-band.

[0060] Based on the first or second aspect, in one possible design, at least one precoding vector is used for interpolation using a second interpolation method to obtain precoding vectors corresponding to all antenna ports, including: the fourth and fifth precoding vectors in the at least one precoding vector are used for interpolation using the second interpolation method to obtain a sixth precoding vector; correspondingly, the access network device can use the second interpolation method to interpolate the fourth and fifth precoding vectors in the at least one precoding vector to obtain the sixth precoding vector. Wherein, the fourth precoding vector is the precoding vector of the first antenna port in the at least one antenna port, the fifth precoding vector is the precoding vector of the second antenna port in the at least one antenna port, and the sixth precoding vector is the precoding vector of the third antenna port, which is the antenna port other than the at least one antenna port among all antenna ports.

[0061] Optionally, the fourth, fifth, and sixth precoding vectors all correspond to the second stream. The second stream is, for example, any stream in the stream corresponding to downlink data transmission.

[0062] With this design, the access network device can accurately determine the sixth precoding vector based on the fourth and fifth precoding vectors in the at least one precoding vector.

[0063] Based on the first or second aspect, in one possible design, the index of the third antenna port is located between the indices of the first and second antenna ports. With this design, the precoding vector of the third antenna port is obtained by interpolating the precoding vectors of the two antenna ports located on either side of the third antenna port in the spatial domain, thereby improving the accuracy and precision of the determined precoding vector of the third antenna port.

[0064] Based on the first or second aspect, in one possible design, the index of the third antenna port is greater than the index of the first antenna port and the index of the second antenna port; or, the index of the third antenna port is less than the index of the first antenna port and the index of the second antenna port. With this design, the precoding vector of the third antenna port is obtained by interpolating the precoding vectors of the two antenna ports located on the same side of the third antenna port in the spatial domain. This allows for accurate determination of the precoding vector of the third antenna port, and enables the determination of the precoding vector of the third antenna port even when the first information does not indicate the precoding vectors of the two antenna ports located on either side of the third antenna port.

[0065] Thirdly, this application provides a communication device. In some examples, the communication device can be a terminal, or a device applicable to a terminal (e.g., a module, communication module, circuit or chip responsible for communication functions (e.g., a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software capable of implementing all or part of the terminal's functions. The device applicable to the terminal can exist independently; for example, it can be independently manufactured, sold, or used. This communication device has the functionality to achieve the first aspect described above. In other examples, the communication device can be an access network device, or a device applicable to an access network device (e.g., a module, communication module, circuit or chip responsible for communication functions (e.g., a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or a logical node, logical module, or software capable of implementing all or part of the access network device's functions. The device applicable to the access network device can exist independently; for example, it can be independently manufactured, sold, or used. This communication device has the functionality to achieve the second aspect described above.

[0066] In one possible design, the communication device includes modules, units, or means corresponding to the operations involved in any of the first to second aspects described above. These modules, units, or means can be implemented in software, hardware, or a combination of both. For example, the communication device includes an interface unit and a processing unit. The interface unit can be used to transmit and receive signals to enable communication between the communication device and other devices; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the interface unit can correspond to the operations involved in any of the first to second aspects described above.

[0067] In one possible design, the communication device includes a processor. The processor is capable of executing computer programs or instructions, for example, executing computer programs or instructions stored in memory. When the computer program or instructions are executed, the communication device performs the methods in any of the possible designs described in the first to second aspects above.

[0068] Optionally, the processor is coupled to the memory via an interface, which is either a memory built into the communication device or an external memory connected to the communication device.

[0069] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and to perform the methods in any of the possible designs in any of the first to second aspects described above.

[0070] Fourthly, this application provides a communication system that may include a first device and a second device. The first device is capable of executing the communication method provided in the first aspect, and the second device is capable of executing the communication method provided in the second aspect.

[0071] In some possible designs, the first device is a terminal and the second device is an access network device.

[0072] Fifthly, this application provides a computer-readable storage medium storing a computer program or instructions, wherein when the computer program or instructions are executed, the method in any possible design of any of the first to second aspects described above is implemented.

[0073] Sixthly, this application provides a computer program product comprising computer program code, wherein when the computer program code is run, any possible design method of any of the first to second aspects described above is implemented.

[0074] In a seventh aspect, this application provides a chip that may include at least one processor for executing computer programs or instructions in memory to implement the methods in any possible design of any of the first to second aspects described above.

[0075] The technical effects that can be achieved by any of the third to seventh aspects mentioned above can be described with reference to the technical effects that can be achieved by any of the possible designs in the first to second aspects mentioned above. Where there is overlap, no further discussion will be given. Attached Figure Description

[0076] Figure 1 is an architecture diagram of a communication system provided in an embodiment of this application;

[0077] Figure 2 is a schematic diagram of a precoding matrix provided in an embodiment of this application;

[0078] Figure 3 is a flowchart of the first communication method provided in an embodiment of this application;

[0079] Figures 4A and 4B are schematic diagrams of several interpolation methods provided in the embodiments of this application;

[0080] Figure 5 is a flowchart of the second communication method provided in an embodiment of this application;

[0081] Figures 6A and 6B are schematic diagrams of several other interpolation methods provided in the embodiments of this application;

[0082] Figure 7 is a flowchart of the third communication method provided in the embodiments of this application;

[0083] Figure 8 is a schematic diagram of another interpolation method provided in an embodiment of this application;

[0084] Figures 9 to 12 are structural diagrams of several communication devices provided in the embodiments of this application. Detailed Implementation

[0085] The technical solutions in the embodiments of this application will be described below with reference to the accompanying drawings. The technical solutions in the embodiments of this application can be applied to various communication systems, such as wireless local area networks (WLANs), wireless fidelity (Wi-Fi or WiFi) systems, fourth-generation (4G) mobile communication systems (such as long-term evolution (LTE) systems), fifth-generation (5G) mobile communication systems (such as new radio (NR) systems), or future communication systems. The methods provided in the embodiments of this application can be applied to terrestrial network communication systems or non-terrestrial network (NTN) communication systems. NTN communication systems can be, for example, satellite communication systems, and may also include unmanned aerial vehicles (UAVs), high-altitude platform stations (HAPS), and other aerial access network equipment; this application does not limit these aspects.

[0086] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches are also possible.

[0087] Figure 1 illustrates a schematic diagram of a communication system provided in an embodiment of this application. As shown in Figure 1, the communication system 10 includes a radio access network (RAN) 100 and a core network (CN) 200. Optionally, the communication system 10 may also include the Internet 300.

[0088] RAN 100 includes at least one RAN node (110a and 110b in Figure 1, collectively referred to as 110) and at least one terminal (120a-120j in Figure 1, collectively referred to as 120). RAN 100 may also include other RAN nodes, such as wireless relay equipment and / or wireless backhaul equipment (not shown in Figure 1). Terminal 120 is wirelessly connected to RAN node 110. RAN node 110 is wirelessly or wired connected to core network 200. The core network equipment in core network 200 and RAN node 110 in RAN 100 can be different physical devices, or they can be the same physical device integrating core network logical functions and wireless access network logical functions.

[0089] RAN 100 can be a cellular system related to the 3rd Generation Partnership Project (3GPP), such as 4G, 5G mobile communication systems, or future-oriented evolution systems. RAN 100 can also be an open RAN (O-RAN or ORAN), a cloud radio access network (CRAN), or a WiFi system. RAN 100 can also be a communication system that integrates two or more of the above systems.

[0090] RAN node 110, sometimes referred to as RAN entity or access node, constitutes part of the communication system and assists terminals in achieving wireless access. Multiple RAN nodes 110 in communication system 10 can be of the same type or different types. In some scenarios, the roles of RAN node 110 and terminal 120 are relative. For example, network element 120i in Figure 1 can be a helicopter or drone, which can be configured as a mobile base station. For terminals 120j accessing RAN 100 through network element 120i, network element 120i is a base station; however, for base station 110a, network element 120i is a terminal. RAN node 110 and terminal 120 are sometimes both referred to as communication devices. For example, network elements 110a and 110b in Figure 1 can be understood as communication devices with base station functions, and network elements 120a-120j can be understood as communication devices with terminal functions.

[0091] RAN nodes can also be described in different ways, such as access network equipment. Unless otherwise specified in this application, access network equipment will be used as the term.

[0092] Access network equipment can be devices or modules located on the network side of the aforementioned communication system and possessing corresponding communication functions. Access network equipment typically contains communication modules, circuits, or chips that perform the corresponding communication functions. Access network equipment may also be configured with programs or instructions for performing the corresponding communication functions, as well as the corresponding programs or instructions themselves.

[0093] In one possible scenario, access network equipment can be a base station (BS), an evolved NodeB (eNodeB), a transmission point (TP), an access point (AP), a transmission reception point (TRP), a mobile switching center, a next-generation NodeB (gNB), a next-generation base station in a future communication system, or an access node in a WiFi system. Access network equipment can also be a macro base station (as shown in Figure 1, 110a), a micro base station or indoor station (as shown in Figure 1, 110b), a relay node or donor node, a radio controller in a CRAN scenario, a satellite, a drone, a balloon, or an aircraft. Optionally, access network equipment can also be a server, wearable device, vehicle, or in-vehicle equipment. For example, in vehicle-to-everything (V2X) technology, the access network equipment can be a roadside unit (RSU). All or part of the functions of the access network device in this application can also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (e.g., a cloud platform).

[0094] In another possible scenario, multiple access network devices collaborate to assist the terminal in achieving wireless access, with each device performing a portion of the base station's functions. For example, the access network devices can be centralized units (CUs or control units), distributed units (DUs), CU-control plane (CP), CU-user plane (UP), or radio units (RUs), etc. CUs and DUs can be separate entities or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio frequency equipment or radio frequency units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs).

[0095] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called an open CU (O-CU), DU can also be called an open DU (O-DU), CU-CP can also be called an open CU-CP (O-CU-CP), CU-UP can also be called an open CU-UP (O-CU-UP), and RU can also be called an open RU (O-RU). Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0096] A terminal is a device or module that connects to the aforementioned communication system and possesses corresponding communication functions. A terminal can also be called a terminal device, user equipment (UE), mobile station, mobile terminal, wireless terminal device, subscriber unit, subscriber station, mobile station, remote station, user terminal, user agent, or user device, etc. A terminal typically contains communication modules, circuits, or chips that perform the corresponding communication functions. The terminal may also be configured with programs or instructions for performing these communication functions.

[0097] Terminals can be widely used in various scenarios, such as device-to-device (D2D), V2X communication, machine-type communications (MTC), the Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. Wearable devices, also known as wearable smart devices or smart wearable devices, are a general term for devices that utilize wearable technology to intelligently design and develop everyday wearables. Terminals used in vehicles are called in-vehicle terminal devices, which include, for example, transportation vehicles with wireless communication capabilities, communication modules, or on-board units (OBUs).

[0098] For example, a terminal may include a mobile phone (or "cellular" phone), a computer with a mobile terminal device, or a portable, pocket-sized, handheld, or computer-embedded mobile device. For instance, a terminal may be a Personal Communication Service (PCS) phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), or other similar devices. A terminal may also include restricted devices, such as devices with limited power consumption, limited storage capacity, or limited computing power. For example, a terminal may be an information sensing device such as a barcode scanner, radio frequency identification (RFID), a sensor, a global positioning system (GPS), or a laser scanner. The embodiments of this application do not limit the device form of the terminal.

[0099] In this application, core network equipment refers to equipment in the core network that provides service support to terminals. For example, in the case where CN200 is the core network of a future communication system, a 5G core network, or an evolved 5G core network, some examples of core network equipment include: access and mobility management function (AMF) entities, session management function (SMF) entities, user plane function (UPF) entities, policy control function (PCF) entities, etc., which are not listed here. Among them, the AMF entity can be responsible for terminal access management and mobility management; the SMF entity can be responsible for session management, such as user session establishment; the UPF entity can be a user plane functional entity, mainly responsible for connecting to external networks. For example, in the case of CN200 as a 4G core network, some core network devices include: Mobile Management Entity (MME), Home Subscriber Server (HSS), Serving Gateway (S-GW), Policy and Charging Rules Function (PCRF), Public Data Network Gateway (PDN Gateway, P-GW), etc., which will not be listed here. It should be noted that in this application, entities can also be referred to as network elements or functional entities. For example, an AMF entity can also be called an AMF network element or AMF functional entity, and similarly, an SMF entity can also be called an SMF network element or SMF functional entity. The aforementioned core network devices can operate independently or be combined to implement certain control functions. For example, AMF, SMF, and PCF can be combined into a single core network device.

[0100] The communication systems and service scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new service scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0101] The relevant terms used in the embodiments of this application will be explained below. It should be noted that these explanations are for the purpose of making the embodiments of this application easier to understand, and should not be regarded as a limitation on the scope of protection claimed by this application.

[0102] 1. Reference signal (RS):

[0103] Reference signals, also known as pilot signals, are essential in communication systems for transmitting and receiving data, obtaining system synchronization and feedback channel information, and estimating the uplink or downlink channel. Channel estimation refers to the process of reconstructing or recovering the received signal to compensate for signal distortion caused by channel fading and noise fading. It uses known reference signals from both the transmitter and receiver to determine the time and frequency domain variations of the channel. These reference signals, also called reference signals, are distributed across one or more resource elements (REs) in the time-frequency two-dimensional space within orthogonal frequency division multiplexing (OFDM) symbols, and have known amplitude and phase.

[0104] At the physical layer, uplink communication can include the transmission of uplink physical channels and uplink signals. Uplink physical channels include the Physical Random Access Channel (PRACH), Physical Uplink Control Channel (PUCCH), and Physical Uplink Shared Channel (PUSCH), etc. Uplink signals include the Sounding Reference Signal (SRS), the PUCCH Demodulation Reference Signal (PUCCH-DMRS), the PUSCH Demodulation Reference Signal (PUSCH-DMRS), the Demodulation Reference Signal (DMRS), the Phase Tracking Reference Signal (PTRS), and the Positioning Reference Signal (SRS), etc. The Positioning Reference Signal, for example, is the SRS for Positioning or the Positioning SRS.

[0105] At the physical layer, downlink communication can include the transmission of downlink physical channels and downlink signals. Downlink physical channels include the physical broadcast channel (PBCH), physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH), etc. Downlink signals include the primary synchronization signal (PSS) / secondary synchronization signal (SSS), physical downlink control demodulation reference signal (PDCCH-DMRS), physical downlink shared channel demodulation reference signal (PDSCH-DMRS), DMRS, PTRS, CSI-RS, cell reference signal (CRS), tracking reference signal (TRS), positioning reference signal (positioning RS), SSB, etc. The full name of SSB can be synchronization signal block or synchronization signal (SS) / PBCH block.

[0106] It should be understood that the reference signals listed above are merely examples and should not be construed as limiting this application. This application does not preclude the possibility of defining other reference signals in future agreements to achieve the same or similar functions.

[0107] 2. Precoding and codebook:

[0108] In communication systems, the mathematical expression for communication is y = Hx + n, where y is the received signal, H is the MIMO channel, x is the transmitted signal, and n is noise. In communication systems with multiple antennas, signals from multiple transmitting antennas can be superimposed on any one receiving antenna. Therefore, the method of transmitting signals at the transmitting end affects the system performance, and recovering the transmitted signal at the receiving end is often complex. In this context, precoding can reduce system overhead and maximize the system capacity of MIMO, while also reducing the complexity of eliminating inter-channel interference at the receiver. In this case, the mathematical expression is y = HPx + n, where P is the precoding matrix (or vector, or precoder). To simplify implementation complexity, P can be selected from a predefined set of matrices (or vectors), called the codebook. This signal transmission method is also called a codebook-based transmission method. If the transmitting end has all the information of H, then P can be obtained at the transmitting end itself; this signal transmission method is called a non-codebook (NCB) transmission method.

[0109] 3. Precoding Matrix Indicator (PMI):

[0110] The Precoding Matrix (PMI) can be used to instruct the terminal to determine the precoding matrix for downlink transmission. This precoding matrix can be determined by the terminal based on received reference signals. Optionally, the precoding matrix can be determined by the terminal based on a channel matrix. This channel matrix can be determined by the terminal based on received reference signals (e.g., CSI-RS). Exemplarily, the channel matrix can be determined by the terminal through channel estimation or based on channel reciprocity. For example, the terminal can perform channel estimation based on the received reference signals to determine the channel matrix, and thus determine the precoding matrix.

[0111] It should be understood that the specific methods used by the terminal to determine the precoding matrix are not limited to those described above. Specific implementations can be found in the protocol; for brevity, they are not listed here. For example, the precoding matrix can be obtained by performing singular value decomposition (SVD) on the channel matrix or its covariance matrix, or by performing eigenvalue decomposition (EVD) on the covariance matrix of the channel matrix. It should be understood that the methods for determining the precoding matrix listed above are merely examples and should not constitute any limitation on this application.

[0112] PMI can include wideband PMI and / or subband PMI. Both wideband PMI and subband PMI are related to subband. For ease of understanding, subband will be explained first below.

[0113] In some possible approaches, subbands can be divided based on common resource blocks (CRBs), each CRB comprising a physical resource block (PRB). The size of the subband can be determined based on the size of the bandwidth part (BWP) and the configuration of the access network equipment. For example, Table 1 shows one possible correspondence between subband size and BWP size.

[0114] Table 1

[0115] Assuming the BWP size is 76 PRBs (meaning one BWP consists of 76 PRBs), and the subband size configured for the access network device is the first value in Table 1, then the subband size can be 8 PRBs. For example, CRB0 to CRB7 can be one subband, CRB8 to CRB15 can be another subband, and so on.

[0116] Optionally, the boundaries of the BWP and the subbands may not be aligned, thus the actual size of the subbands at the BWP boundaries will be smaller. For example, within a BWP, the CRBs corresponding to the CSI-RS resources are CRB2 to CRB77, and there are a total of 10 subbands within this BWP, namely subbands A to J. Subband A includes CRB2 to CRB7, and subband J includes subbands CRB72 to 77.

[0117] It should be understood that the above description of subbands is merely an example. In practical applications, subbands can be divided in other ways without limitation. For example, a subband can be understood as any of the following: one or more REs, one or more resource blocks (RBs), one or more precoding resource block groups (PRGs), or one or more physical resource block groups (PRGs).

[0118] The broadband in a broadband PMI can include all subbands configured (or scheduled, or indicated, or allocated) by the access network equipment for the terminal. A broadband PMI refers to a PMI reported by the terminal for that broadband. For example, if the subbands configured (or scheduled, or indicated, or allocated) by the access network equipment for the terminal include: subband B, subband C, subband D, subband E, subband G, and subband H, then the terminal can receive reference signals (e.g., CSI-RS) on these subbands, obtain a PMI (i.e., broadband PMI), and report the PMI to the access network equipment.

[0119] Optionally, after receiving the reference signal, the receiving device can determine the precoding matrix for each sub-band based on the reference signal and feed back the PMI corresponding to the precoding matrix of each sub-band to the transmitting device. In this way, the transmitting device can determine the precoding matrix used for transmitting signals based on the precoding matrix of each sub-band. In other words, the sub-band PMI can refer to the PMI reported by the terminal for each sub-band configured (or scheduled, indicated, or allocated) by the access network device.

[0120] For example, the downlink resources configured (or scheduled, or indicated, or allocated) by the access network device for the terminal include M subbands, where M is a positive integer. The terminal processes the precoding matrix of each of the M subbands to obtain the PMI corresponding to the precoding matrix of each of the M subbands. The subband PMI sent by the terminal to the access network device may include: the PMI corresponding to the precoding matrix of each of the M subbands. For example, if the access network equipment configures (or schedules, or instructs, or allocates) subbands for the terminal, including subband B, subband C, subband D, subband E, subband G, and subband H, then the terminal determines subband PMI#1 based on the reference signal (e.g., CSI-RS) received on subband B, determines subband PMI#2 based on the reference signal (e.g., CSI-RS) received on subband C, and so on. The terminal determines a subband PMI based on the reference signal (e.g., CSI-RS) received on each of these subbands and reports the determined multiple subband PMIs to the access network equipment.

[0121] The precoding matrix of each of the M subbands is illustrated below with reference to Figure 2. As shown in Figure 2, the precoding matrix of the k-th subband among the M subbands can be represented as P k (1) P k (1) The number of rows and columns are N (the number of antenna ports) and J (the number of streams), respectively. Here, k takes integer values ​​from 1 to M, and N and J are positive integers. P k (1) The nth row vector in P is the precoding vector corresponding to the nth antenna port; k (1)The j-th column vector in the vector is the precoding vector corresponding to the j-th stream, where n takes integers from 1 to N and j takes integers from 1 to J.

[0122] Optionally, the access network device can determine the precoding matrix based on the PMI from the terminal. For example, the access network device can determine the CSI-RS port, the discrete Fourier transform (DFT) vector, and the space-frequency vector combining coefficients used to construct the precoding vector based on the PMI from the terminal, and thus determine the precoding matrix. This precoding matrix can be directly used to transmit downlink signals (e.g., downlink data); or it can be processed through one or more beamforming methods, such as zero forcing (ZF), regularized zero-forcing (RZF), minimum mean-squared error (MMSE), and maximizing the signal-to-leakage-and-noise ratio (SLNR), to obtain the final precoding matrix used for transmitting downlink signals. This application does not limit this.

[0123] It is understandable that the precoding matrix determined by the terminal can be interpreted as the precoding matrix to be fed back. The terminal can indicate the precoding matrix to be fed back through the PMI, so that the access network device can recover the precoding matrix based on the PMI. Optionally, the precoding matrix recovered by the access network device based on the PMI can be the same as or similar to the precoding matrix to be fed back. The higher the similarity between the precoding matrix determined by the access network device based on the PMI and the precoding matrix determined by the terminal, the more well the precoding matrix determined by the access network device for transmitting downlink signals can be adapted to the channel state, and therefore the better the signal reception quality can be improved.

[0124] Optionally, PMI can be used for downlink MIMO.

[0125] 4. Antenna Port:

[0126] An antenna port, often simply called a port, is a logical concept. It can be understood as a virtual transmitting antenna (or antenna array) identified by the receiver, or a spatially distinguishable virtual transmitting antenna (or antenna array). An antenna port generally corresponds to a physical antenna. Each antenna port represents a channel model, which can be derived from a reference signal on the antenna port. Therefore, an antenna port is usually associated with a reference signal, and its meaning can be understood as a transmit / receive interface on the channel through which the reference signal passes. Because antenna ports can be associated with reference signals, each antenna port can be called a port for a reference signal, such as a CSI-RS port, DMRS port, or SRS port. For low frequencies, an antenna port may correspond to one or more antenna elements that jointly transmit the reference signal; the receiver can treat them as a whole without distinguishing between individual elements. For high-frequency systems, an antenna port may correspond to a beam; similarly, the receiver only needs to treat this beam as an interface without distinguishing between individual elements.

[0127] A set of multiple antenna ports can be called a port set. In one approach, multiple digital ports of an access network device are grouped to form multiple port sets. In another approach (e.g., in a hybrid beamforming (HBF) architecture), a port set can be multiple digital ports corresponding to the same analog beam, also simply called a port set, or a digital-to-analog port set. Alternatively, a port set can be a set of digital ports corresponding to multiple analog beams, also simply called a port set, or a digital-to-analog port set. Or, multiple digital ports corresponding to an analog beam can be divided into multiple subsets, each subset being called a port set, or a digital-to-analog port set.

[0128] In protocols, antenna ports are typically identified by "antenna port" or "port," but they can also be identified by resources (such as CSI-RS resources, SRS resources, DMRS resources, PTRS resources, CRS resources, TRS resources, or SSB resources) or resource groups. In other words, the identifier for an antenna port can be replaced with one of the above-mentioned identifiers; for example, an antenna port can be replaced with an identifier for a resource, a pilot resource, or a reference signal resource.

[0129] A port set may contain one or more antenna ports, typically corresponding to one or more resources. Therefore, a port set can also be replaced with other names, such as resource group, resource set, pilot resource group, pilot resource set, reference signal resource group, reference signal resource set, port group, antenna port group, antenna port set, or antenna port collection, etc., without limitation. In this embodiment, the port set can also be replaced with "port #A to port #B". Here, port #A and port #B can be understood as examples of port indices. The antenna ports indicated by ports #A to #B can be understood as antenna ports indexed from #A to #B, and these antenna port indices are consecutive. In this embodiment, the port set can also be replaced with the index of each antenna port included in the port set. In this case, the antenna ports included in the port set can be consecutive antenna ports or non-consecutive antenna ports.

[0130] 5. Flow:

[0131] In a spatial multiplexing MIMO system, multiple parallel data streams can be transmitted simultaneously on the same frequency domain resources, and each data stream is called a stream. Streams in MIMO may also have other names, such as layer, spatial layer, transport layer, data layer, or spatial stream, etc., as long as they have the same meaning, they are all within the protection scope of this application.

[0132] 6. In this application, "instruction" or "for instruction" may include explicit instruction (or direct instruction) and implicit instruction (or indirect instruction). When describing information for instructing A, it may include whether the information explicitly instructs A or implicitly instructs A, but does not necessarily mean that the information carries A.

[0133] The indication methods involved in the embodiments of this application should be understood to cover various methods that enable the party to be indicated to obtain the information to be indicated. The information to be indicated can be sent as a whole or divided into multiple sub-information and sent separately. Moreover, the sending period and / or sending time of these sub-information can be the same or different, without limitation.

[0134] In the embodiments of this application, "information" can be an explicit indication, that is, a direct indication through signaling, or obtained by combining other rules or parameters with parameters indicated by signaling, or by deduction. It can also be an implicit indication, that is, obtained based on rules or relationships, or based on other parameters, or by deduction. No limitation is imposed.

[0135] 7. In this application, communication between different devices can refer to direct communication between different devices (i.e., without the need for relaying or forwarding by other devices), or communication between different devices through other devices (i.e., requiring relaying or forwarding by other devices), or communication between a functional unit within a device and other devices through another functional unit. For example, "sending information to…(terminal)" can be understood as the destination of the information being the terminal, and may include sending information directly or indirectly to the terminal. "Receiving information from…(terminal)" can be understood as the source of the information being the terminal, and may include receiving information directly or indirectly from the terminal. Information may undergo necessary processing between the source and destination ends, such as format changes, digital-to-analog conversion, amplification, filtering, etc., but the destination end can understand the valid information from the source end. Similar expressions in this application can be understood in a similar way, and will not be elaborated further here.

[0136] 8. In this application, the words "exemplarily," "for example," "for instance," and "example" are used to indicate examples, illustrations, or explanations, and are not intended to limit the scope of protection of this application. It should be understood that the examples in this application may also be implemented in other ways. In this application, "of," "corresponding, relevant," and "corresponding" may sometimes be used interchangeably, and it should be noted that their intended meanings are consistent when their distinction is not emphasized.

[0137] 9. In this application, any two of the programs, instructions, and code may be substituted for one another.

[0138] 10. In this application, "greater than or equal to" and "greater than" are interchangeable. For example, "A is greater than threshold 1" and "A is greater than or equal to threshold 1" are interchangeable. "Less than or equal to" and "less than" are interchangeable. For example, "A is less than threshold 1" and "A is less than or equal to threshold 1" are interchangeable.

[0139] 11. In this application, some characters are in regular font, such as 'k'; some characters are in italic font, such as 'k'. When the same character is used in different fonts, it has the same meaning.

[0140] 12. In this application, the parameters in the formulas can also be represented by other letters, as long as they have the same meaning, they are all within the scope of protection of this application. For example, the first matrix can be represented as follows:

[0141] 13. In this application, "in the case of," "when," "if," and "if," "then" can have the same meaning and can be substituted for each other. Optionally, in this application, "in the case of," "when," "if," and "then" all refer to the corresponding processing that will be carried out under certain objective circumstances, and are not limited to a time, nor do they require a judgment action at the time of implementation, nor do they imply any other limitations.

[0142] 14. In this application, a precoding vector can be understood as at least one of the following: a vector used for precoding, or a vector in a precoding matrix (e.g., a row vector and / or a column vector).

[0143] 15. In this application, the manifold interpolation method can be understood as at least one of the following: a manifold-based interpolation method, a stream-based interpolation method, or a method of interpolation based on the precoding matrix and / or precoding vector corresponding to the stream.

[0144] 16. In this application, the number of streams corresponding to downlink data transmission can be understood as at least one of the following: the number of streams corresponding to (or used) downlink transmission, or the number of streams used for downlink data transmission.

[0145] 17. In this application, the index may be replaced with a sequence number or a number, etc. For example, the subband index may be replaced with the subband sequence number or the subband number. As another example, the antenna port index may be replaced with the antenna port sequence number or the antenna port number.

[0146] 18. In this application, the sub-band occupied by the reference signal can replace the sub-band corresponding to or used by the reference signal. For example, all sub-bands occupied by the reference signal can replace all sub-bands corresponding to or used by the reference signal.

[0147] In this application, the antenna port occupied by the reference signal can be replaced with the antenna port corresponding to or used by the reference signal. For example, all antenna ports occupied by the reference signal can be replaced with all antenna ports corresponding to or used by the reference signal.

[0148] Currently, after receiving a reference signal, the receiving device can determine the precoding matrix for each sub-band based on the reference signal and feed back the PMI corresponding to the precoding matrix of each sub-band to the transmitting device. In this way, the transmitting device can determine the precoding matrix used for transmitting the signal based on the precoding matrix of each sub-band. However, this method requires the transmitting device to send the PMI corresponding to the precoding matrix of each sub-band, resulting in significant overhead.

[0149] In addition, the number of rows in the precoding matrix of the subband is equal to the number of transmit antenna ports. Currently, the receiving device needs to feed back the PMI of the precoding vectors corresponding to all transmit antenna ports, which incurs a large overhead.

[0150] Further research is needed on how to reduce the overhead of the feedback precoding matrix.

[0151] Based on this, embodiments of this application provide a communication method and apparatus for reducing the feedback overhead of precoding matrices. The method and apparatus described in this application are based on the same technical concept. Since the principles by which the method and apparatus solve the problem are similar, the implementations of the apparatus and method can be mutually referred to, and repeated details will not be elaborated further.

[0152] The various communication methods provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings. These methods can be applied to the communication system shown in FIG1, but are not limited thereto. The embodiments of this application take the interaction between a terminal and an access network device as an example for description. The operations implemented by the terminal can be implemented by a device that can be applied to the terminal (e.g., a module, a communication module, a circuit or chip responsible for communication functions (e.g., a modem chip, or a SoC chip or SIP chip containing a modem core), a chip system, or a processor), or by a logical node, logical module, or software that can implement all or part of the terminal's functions. The operations implemented by the access network device can be implemented by a device that can be applied to the access network device (e.g., a module, a communication module, a circuit or chip responsible for communication functions (e.g., a modem chip, or a SoC chip or SIP chip containing a modem core), a chip system, or a processor), or by a logical node, logical module, or software that can implement all or part of the access network device's functions. The device that can be applied to the terminal can exist independently, for example, it can be independently manufactured, sold, or used; the device that can be applied to the access network device can exist independently, for example, it can be independently manufactured, sold, or used.

[0153] It is understood that in the embodiments of this application, the terminal and / or access network device may perform some or all of the steps in the embodiments of this application. These steps or operations are merely examples, and the embodiments of this application may also perform other operations or variations thereof. Furthermore, the steps may be performed in different orders as presented in the embodiments of this application, and it is not necessarily necessary to perform all the operations in the embodiments of this application.

[0154] Figure 3 is a flowchart illustrating a communication method provided in an embodiment of this application. In the method shown in Figure 3, the terminal can feed back the precoding matrix of a portion of the sub-bands occupied by the reference signal, and the access network device can interpolate the precoding matrix of that portion of the sub-bands to obtain the precoding matrix of all sub-bands occupied by the reference signal. As shown in Figure 3, the method may include:

[0155] S301: The access network device sends a reference signal; correspondingly, the terminal receives the reference signal.

[0156] The number of reference signals can be one or more.

[0157] Optionally, the reference signal may be a traditional reference signal, such as CSI-RS. In the subsequent standard evolution process, the name of the traditional reference signal may change or remain the same, all of which are within the protection scope of this application; or, the reference signal may be an evolution of the traditional reference signal. The name of the evolved reference signal may change or remain the same, all of which are within the protection scope of this application; or, the reference signal may be a new reference signal or a reference signal defined in the future.

[0158] This application does not restrict the way in which access network equipment transmits reference signals, for example, it may transmit them in a manner specified by the protocol; this application does not restrict the way in which terminals receive reference signals, for example, they may receive them in a manner specified by the protocol.

[0159] S302: The terminal sends the first information; correspondingly, the access network device receives the first information.

[0160] The first information can be used to indicate at least one precoding matrix. This application does not limit the manner in which the first information indicates the at least one precoding matrix; for example, it can be indicated in a manner specified by a protocol. The at least one precoding matrix can be determined based on the reference signal. Accordingly, the terminal can determine the at least one precoding matrix based on the reference signal. This application does not limit the manner in which the terminal can determine the at least one precoding matrix based on the reference signal; for example, it can be determined in a manner specified by a protocol.

[0161] The following describes at least one precoding matrix.

[0162] 1. The at least one precoding matrix may include the precoding matrix of each subband in at least one subband, and the at least one subband may be a portion of all subbands occupied by the reference signal. Optionally, the at least one subband may be continuous or discontinuous in the frequency domain.

[0163] For example, the reference signal occupies subbands #1 to #6; the at least one subband may include subband #1, subband #3 and subband #5, and correspondingly, the first information may indicate: the precoding matrix of subband #1, the precoding matrix of subband #3 and the precoding matrix of subband #5.

[0164] Optionally, the at least one subband can be understood as a subband in the first subband set; or, the at least one subband can be replaced by the first subband set. The first subband set may include a portion of the subbands occupied by the reference signal. For example, the reference signal occupies subbands #1 to #6; the first subband set may include subband #1, subband #3, and subband #5, and correspondingly, the first information may indicate: the precoding matrix of subband #1, the precoding matrix of subband #3, and the precoding matrix of subband #5.

[0165] Optionally, all subbands occupied by the reference signal can be replaced with all subbands in the downlink resources configured (or scheduled, or indicated, or allocated) by the access network device for the terminal. For example, the downlink resources configured (or scheduled, or indicated, or allocated) by the access network device for the terminal include subbands #1 to #6; the at least one subband may include subband #1, subband #3, and subband #5, and correspondingly, the first information may indicate the precoding matrix of subband #1, the precoding matrix of subband #3, and the precoding matrix of subband #5.

[0166] In some implementations, the at least one precoding matrix may correspond to the at least one subband; for example, the at least one precoding matrix may correspond one-to-one with the at least one subband.

[0167] Optionally, the at least one precoding matrix may be at least two precoding matrices, and the at least one subband may be at least two subbands.

[0168] 2. The at least one precoding matrix can be interpolated using a first interpolation method to obtain precoding matrices corresponding to each of the subbands; correspondingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices corresponding to each of the subbands. Optionally, the first interpolation method is a manifold interpolation method.

[0169] The specific contents of all sub-bands can be found in the description of all sub-bands above, and will not be repeated here.

[0170] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can include: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands; correspondingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices for all subbands except the at least one subband, thereby obtaining precoding matrices corresponding to each of the subbands.

[0171] For example (hereinafter referred to as Example 1), all subbands include subbands #1 to #6; the first information may indicate: the precoding matrix of subband #1, the precoding matrix of subband #3, and the precoding matrix of subband #5. The precoding matrices of subband #1, subband #3, and subband #5 can be interpolated using a first interpolation method to obtain the precoding matrices of subband #2, subband #4, and subband #6, thereby obtaining the precoding matrices corresponding to each of the subbands; correspondingly, the access network device can interpolate the precoding matrices of subband #1, subband #3, and subband #5 using the first interpolation method to obtain the precoding matrices of subband #2, subband #4, and subband #6, thereby obtaining the precoding matrices corresponding to each of the subbands.

[0172] Optionally, the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each of the subbands. This can be understood as: the at least one precoding matrix can be used to interpolate using a first interpolation method to obtain the precoding matrix corresponding to each subband among all the subbands.

[0173] Optionally, the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices corresponding to each of the subbands. This can be replaced by: the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. Accordingly, the access network device can interpolate the at least one precoding matrix using the first interpolation method to obtain precoding matrices corresponding to some or all of the subbands. The following explanation uses the example of "the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain precoding matrices corresponding to each of the subbands" for illustration.

[0174] Optionally, for the terminal side, "the at least one precoding matrix can be used to interpolate using the first interpolation method to obtain the precoding matrices corresponding to each of the subbands" is optional.

[0175] The following is an exemplary description of the implementation of "the at least one precoding matrix can be used to interpolate by the first interpolation method to obtain the precoding matrices corresponding to all the subbands respectively".

[0176] In some possible approaches, the first and second precoding matrices in the at least one precoding matrix can be used to obtain a third precoding matrix through a first interpolation method; correspondingly, the access network device can interpolate the first and second precoding matrices in the at least one precoding matrix using the first interpolation method to obtain the third precoding matrix. Wherein, the first precoding matrix is ​​the precoding matrix of the first subband in the at least one subband, the second precoding matrix is ​​the precoding matrix of the second subband in the at least one subband, and the third precoding matrix is ​​the precoding matrix of the third subband, where the third subband is any subband other than the at least one subband.

[0177] Optionally, the first and second precoding matrices in the at least one precoding matrix can be used to obtain a third precoding matrix by a first interpolation method, which can be understood as at least one of the following: the first and second precoding matrices in the at least one precoding matrix can be used to interpolate by the first interpolation method to obtain a third precoding matrix; the third precoding matrix is ​​obtained by interpolating the first and second precoding matrices in the at least one precoding matrix; or, the third precoding matrix is ​​obtained by interpolating the first and second precoding matrices in the at least one precoding matrix by the first interpolation method.

[0178] It should be understood that this method is illustrated by taking "the first precoding matrix and the second precoding matrix can be used to obtain the third precoding matrix through the first interpolation method" as an example. The precoding matrix of any subband except for at least one subband can be obtained by interpolating the two precoding matrices in the at least one precoding matrix, thereby obtaining the precoding matrices corresponding to each of the subbands.

[0179] The following example illustrates, based on the relationship between the first subband, the second subband, and the third subband, that "the first and second precoding matrices in the at least one precoding matrix can be used to obtain the third precoding matrix through the first interpolation method".

[0180] In some implementations, the third sub-band may lie between the first and second sub-bands in the frequency domain. Optionally, if the indices of the sub-bands in the at least one sub-band are arranged in descending order of their corresponding frequencies, or if the indices of the sub-bands in the at least one sub-band are arranged in ascending order of their corresponding frequencies, then "the third sub-band may lie between the first and second sub-bands in the frequency domain" can be replaced with: the index of the third sub-band lies between the indices of the first and second sub-bands. Optionally, the first and second sub-bands may be the two sub-bands that are closest to the third sub-band in the frequency domain among the at least one sub-bands. In the example below, assume that all sub-bands include sub-bands #1 to #6, whose corresponding frequencies in ascending order are sub-band #1, sub-band #2, sub-band #3, sub-band #4, sub-band #5, and sub-band #6.

[0181] For example, in Example 1, the first subband can be subband #1, and the first precoding matrix is ​​the precoding matrix of subband #1; the second subband can be subband #3, and the second precoding matrix is ​​the precoding matrix of subband #3; the third subband is subband #2, and the third precoding matrix is ​​the precoding matrix of subband #2. Subband #2 is located between subband #1 and subband #3 in the frequency domain. The precoding matrices of subband #1 and subband #3 can be interpolated using the first interpolation method to obtain the precoding matrix of subband #2; correspondingly, the access network device can interpolate the precoding matrices of subband #1 and subband #3 using the first interpolation method to obtain the precoding matrix of subband #2.

[0182] For example, in Example 1, the first subband can be subband #3, and the first precoding matrix is ​​the precoding matrix of subband #3; the second subband can be subband #5, and the second precoding matrix is ​​the precoding matrix of subband #5; the third subband is subband #4, and the third precoding matrix is ​​the precoding matrix of subband #4. Subband #4 is located between subband #3 and subband #5 in the frequency domain. The precoding matrices of subband #3 and subband #5 can be interpolated using the first interpolation method to obtain the precoding matrix of subband #4; correspondingly, the access network device can interpolate the precoding matrices of subband #3 and subband #5 using the first interpolation method to obtain the precoding matrix of subband #4.

[0183] This implementation allows the precoding matrix of the third sub-band to be obtained by interpolating the precoding matrices of the two sub-bands located on either side of the third sub-band in the frequency domain, thereby improving the accuracy and precision of the determined precoding matrix of the third sub-band.

[0184] In other implementations, the third sub-band may be located on the same side of the first and second sub-bands in the frequency domain. Optionally, if the indices of the sub-bands in the at least one sub-band are arranged in descending order of their corresponding frequencies, or if the indices of the sub-bands in the at least one sub-band are arranged in ascending order of their corresponding frequencies, then "the third sub-band may be located on the same side of the first and second sub-bands in the frequency domain" can be replaced with: the index of the third sub-band is greater than the index of the first sub-band and the index of the second sub-band, or the index of the third sub-band is less than the index of the first sub-band and the index of the second sub-band. In the example below, assume that all the sub-bands include sub-bands #1 to #6, whose corresponding frequencies in ascending order are sub-band #1, sub-band #2, sub-band #3, sub-band #4, sub-band #5, and sub-band #6.

[0185] For example, in Example 1, the first subband can be subband #1, and the first precoding matrix is ​​the precoding matrix of subband #1; the second subband can be subband #5, and the second precoding matrix is ​​the precoding matrix of subband #5; the third subband is subband #6, and the third precoding matrix is ​​the precoding matrix of subband #6. Subband #6 is located on the same side of subband #1 and subband #5 in the frequency domain. The precoding matrices of subband #1 and subband #5 can be interpolated using the first interpolation method to obtain the precoding matrix of subband #6; correspondingly, the access network device can interpolate the precoding matrices of subband #1 and subband #5 using the first interpolation method to obtain the precoding matrix of subband #6.

[0186] Optionally, when the third sub-band is located on the same side of the first and second sub-bands in the frequency domain, the first and second sub-bands can be the two sub-bands that are closest to the third sub-band in the frequency domain among the at least one sub-band.

[0187] For example, in Example 1, the first sub-band can be sub-band #3, and the first precoding matrix is ​​the precoding matrix of sub-band #3; the second sub-band can be sub-band #5, and the second precoding matrix is ​​the precoding matrix of sub-band #5; the third sub-band is sub-band #6, and the third precoding matrix is ​​the precoding matrix of sub-band #6. Sub-band #6 is located on the same side of sub-band #3 and sub-band #5 in the frequency domain. The precoding matrices of sub-band #3 and sub-band #5 can be interpolated using the first interpolation method to obtain the precoding matrix of sub-band #6; correspondingly, the access network device can interpolate the precoding matrices of sub-band #3 and sub-band #5 using the first interpolation method to obtain the precoding matrix of sub-band #6.

[0188] Through this implementation, the precoding matrix of the third sub-band is obtained by interpolating the precoding matrices of the two sub-bands located on the same side of the third sub-band in the frequency domain. This allows for accurate determination of the precoding matrix of the third sub-band, and it can be determined even when the first information does not indicate the precoding matrices of the two sub-bands located on both sides of the third sub-band.

[0189] As mentioned above, the first and second precoding matrices in at least one precoding matrix can be used to obtain a third precoding matrix through a first interpolation method. There are multiple ways to implement this, such as method a1 and / or method a2.

[0190] Method a1: The first precoding vector and the second precoding vector are used to obtain the third precoding vector through the first interpolation method; correspondingly, the access network device can interpolate the first precoding vector and the second precoding vector through the first interpolation method to obtain the third precoding vector.

[0191] Wherein, the first precoding vector may be the precoding vector corresponding to the first stream in the first precoding matrix, the second precoding vector may be the precoding vector corresponding to the first stream in the second precoding matrix, and the third precoding vector may be the precoding vector corresponding to the first stream in the third precoding matrix. Optionally, the first stream may be a stream corresponding to one or more precoding matrices among the first, second, or third precoding matrices. For example, the first stream may be any stream corresponding to one or more precoding matrices among the first, second, or third precoding matrices. For instance, the first stream may be any stream corresponding to the third precoding matrix. Also, for example, the first stream may be any stream corresponding to the first, second, and third precoding matrices.

[0192] For example (hereinafter referred to as Example 2), the first stream is the first stream in the stream corresponding to downlink data transmission. As shown in Figure 4A, the first precoding vector V 11 V is the precoding vector corresponding to the first stream in the precoding matrix of subband #1, i.e., the first precoding vector V. 11 V is the first column vector in the precoding matrix of subband #1; the second precoding vector is V. 31 V is the precoding vector corresponding to the first stream in the precoding matrix of subband #3, i.e., the second precoding vector. 31 V is the first column vector in the precoding matrix of subband #3; the third precoding vector is V. 21 V is the precoding vector corresponding to the first stream in the precoding matrix of subband #2, i.e., the third precoding vector. 21 V is the first column vector in the precoding matrix of subband #2. 11 and V 31 It can be used to interpolate using the first interpolation method to obtain V.21 .

[0193] It should be understood that this example uses the first stream in the stream corresponding to downlink data transmission as an example for illustration. The first stream can also be any other stream in the stream corresponding to downlink data transmission, without restriction.

[0194] Optionally, the first precoding vector and the second precoding vector are used to obtain the third precoding vector through the first interpolation method, which can be understood as at least one of the following: the first precoding vector and the second precoding vector are used to interpolate through the first interpolation method to obtain the third precoding vector; the third precoding vector is obtained by interpolating the first precoding vector and the second precoding vector; or, the third precoding vector is obtained by interpolating the first precoding vector and the second precoding vector through the first interpolation method.

[0195] It should be understood that this method is illustrated by taking "the first precoding vector and the second precoding vector as examples to obtain the third precoding vector through the first interpolation method". The precoding vector corresponding to each stream in the third precoding matrix can be obtained by interpolating the precoding vector corresponding to the stream in the first precoding matrix and the precoding vector corresponding to the stream in the second precoding matrix, thereby obtaining the third precoding matrix.

[0196] In some possible ways, the first precoding vector, the second precoding vector, and the third precoding vector can satisfy the following formulas (1) to (3):

[0197] in, This is the first precoding vector. V is the second precoding vector. t Here, k is the index of the first sub-band, k1 is the index of the second sub-band, t is the index of the third sub-band, cos() is the cosine function, sin() is the sine function, and acos() is the inverse cosine function. for The conjugate transpose of , || represents taking the absolute value, atan() is the arctangent function, Im() represents taking the imaginary part of the complex number, and Re() represents taking the real part of the complex number.

[0198] For example, in Example 2, For V 11 , For V 31 V t For V 21 k0 is the index of subband #1, k1 is the index of subband #3, and t is the index of subband #2. The access network device can determine the index based on V. 11 V 31 And θ is determined by formula (2), and V is used to determine θ.11 V 31 And φ is determined by formula (3), so V can be determined according to formula (1). 21 .

[0199] Alternatively, formulas (2) and (3) can be replaced with the following formulas:

[0200] Using method a1, the access network device can accurately determine the third precoding vector based on the first and second precoding vectors. When the first flow is any flow in the third precoding matrix, the access network device can obtain the precoding vector corresponding to each flow in the third precoding matrix using this method, thereby accurately determining the third precoding matrix. Furthermore, in this method, the access network device can determine the precoding vector corresponding to each flow in the third precoding matrix flow-by-flow, resulting in lower computational complexity.

[0201] Method a2: The first matrix and the second matrix can be used to obtain the third matrix through the first interpolation method; correspondingly, the access network device can interpolate the first matrix and the second matrix through the first interpolation method to obtain the third matrix.

[0202] The first matrix may include precoding vectors corresponding to multiple streams in the first precoding matrix, the second matrix may include precoding vectors corresponding to the multiple streams in the second precoding matrix, and the third matrix may include precoding vectors corresponding to the multiple streams in the third precoding matrix. The multiple streams may be some or all of the streams corresponding to the third precoding matrix.

[0203] For example (hereinafter referred to as Example 3), these multiple streams include the first and second streams in the stream corresponding to downlink data transmission. As shown in Figure 4B, the first matrix V 12 This includes: the precoding vector corresponding to the first stream in the precoding matrix of subband #1, and the precoding vector corresponding to the second stream in the precoding matrix of subband #1, i.e., the first matrix V. 12 Includes the first and second column vectors in the precoding matrix of subband #1; the second matrix V 32 This includes: the precoding vector corresponding to the first stream in the precoding matrix of subband #3, and the precoding vector corresponding to the second stream in the precoding matrix of subband #3, i.e., the second matrix V. 32 Includes the first and second column vectors in the precoding matrix of subband #3; the third matrix V 22 This includes: the precoding vector corresponding to the first stream in the precoding matrix of subband #2, and the precoding vector corresponding to the second stream in the precoding matrix of subband #2, i.e., the third matrix V. 22 This includes the first and second column vectors in the precoding matrix of subband #2. 12 and V32 It can be used to interpolate using the first interpolation method to obtain V. 22 .

[0204] It should be understood that this example is illustrated using the first and second streams in the streams corresponding to downlink data transmission as an example. The multiple streams may also include other streams in the streams corresponding to downlink data transmission, without limitation.

[0205] Optionally, the first matrix and the second matrix are used to obtain the third matrix through the first interpolation method, which can be understood as at least one of the following: the first matrix and the second matrix are used to interpolate through the first interpolation method to obtain the third matrix; the third matrix is ​​obtained by interpolating the first matrix and the second matrix; or, the third matrix is ​​obtained by interpolating the first matrix and the second matrix through the first interpolation method.

[0206] It should be understood that this method is illustrated by the example of "the first matrix and the second matrix are used to obtain the third matrix through the first interpolation method". The third precoding matrix may include multiple matrices, each of which corresponds to multiple streams. Each of these multiple matrices can be obtained by interpolating the matrices in the first precoding matrix and the matrices in the second precoding matrix, thereby obtaining the third precoding matrix.

[0207] In some possible ways, the third matrix V t1 It can satisfy the following formula (4):

[0208] in, and Formula (5) can be satisfied:

[0209] Yes For example, obtained by performing SVD. Satisfies formula (6):

[0210] Formula (7) can be satisfied:

[0211] Γ(x), Ω(x), and F(x) satisfy formulas (8) to (10) respectively: Γ(x)= diag(cos(xθ1),cos(xθ2),…,cos (xθ) p )); (8) Ω(x)= diag(sin(xθ1),sin(xθ2),…,sin (xθ p)) ; (9)

[0212] Wherein, B satisfies formula (11): B=A*logm(D)*inv(A); (11)

[0213] Among them, matrices A and D are based on the matrix The eigenvalue decomposition yields, for example, matrices A and D satisfying formula (12):

[0214] In the above formula, For the first matrix, V is the second matrix. t1 Let be the third matrix, k0 be the index of the first sub-band, k1 be the index of the second sub-band, t be the index of the third sub-band, p be the number of the multiple streams, cos() be the cosine function, sin() be the sine function, and (). H Let be the conjugate transpose of the matrix, ...

[0215] For example, in Example 3, For V 12 , For V 32 V t1 For V 22 k0 is the index of subband #1, k1 is the index of subband #3, and t is the index of subband #2. Access network devices can use formula V... 12 V 32 Determined by formula (6) and Then, the access network equipment can, according to V 12 V 32 Determined by formula (5) and according to Formulas (7) to (9) determine Γ(x) and Ω(x), according to Formulas (10) to (12) determine F(x), thus allowing us to determine F(x) based on... Γ(x), Ω(x), F(x) and formula (4) determine V 22 .

[0216] Using method a2, the access network device can accurately determine the third matrix based on the first and second matrices, thereby accurately determining the third precoding matrix. Furthermore, in this method, the access network device can interpolate by stream combination to obtain the third matrix, which reduces the computational load compared to interpolating for each stream.

[0217] It should be understood that methods a1 and a2 can be independent or combined. For example, the third precoding matrix includes the precoding vectors corresponding to streams #1 to #4. The precoding vectors corresponding to streams #1 to #4 in the third precoding matrix can be determined according to method a1. Another example: the third precoding matrix includes the precoding vectors corresponding to streams #1 to #4. Matrix #1 includes the precoding vectors corresponding to streams #1 to #2 in the third precoding matrix, and matrix #2 includes the precoding vectors corresponding to streams #3 to #4 in the third precoding matrix. Matrix #1 and matrix #2 can be determined according to method a2. Yet another example: the third precoding matrix includes the precoding vectors corresponding to streams #1 to #4. The precoding vector corresponding to stream #1 in the third precoding matrix can be determined according to method a1; matrix #3 includes the precoding vectors corresponding to streams #2 to #4 in the third precoding matrix, and matrix #3 can be determined according to method a2.

[0218] In S302, the first information can be carried in a traditional message or in a new message, without restriction.

[0219] Optionally, the first information may be PMI, or the first information may be channel state information (CSI) including PMI.

[0220] Using the method shown in Figure 3, the terminal can send first information, which can be used to indicate the precoding matrix of a portion of the subbands occupied by the reference signal. In this way, the access network device can interpolate the precoding matrix of that portion of the subbands to obtain the precoding matrices corresponding to each of the subbands. In this method, the terminal does not need to feed back the precoding matrix corresponding to each subband, thereby reducing the overhead of feeding back the precoding matrix.

[0221] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each sub-band increases with the number of antenna ports. This method can feed back only the precoding matrix of a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix. Similarly, massive MIMO technology may have a large bandwidth, resulting in a large number of sub-bands. This method can also feed back only the precoding matrix of a portion of the sub-bands, without feeding back the precoding matrix for each sub-band, thus significantly reducing the overhead of the feedback precoding matrix.

[0222] Alternatively, since the terminal may not feed back the precoding matrix for each subband, this method can improve the accuracy of the fed-back precoding matrix without changing the overhead of the fed-back precoding matrix, thereby improving the accuracy of the precoding matrix recovered by the access network device.

[0223] Among some possible approaches, the method shown in Figure 3 also includes S303:

[0224] S303: The access network device sends a first signal; correspondingly, the terminal receives the first signal.

[0225] The first signal is transmitted according to precoding matrix #1; or, the access network device may transmit the first signal according to precoding matrix #1. Precoding matrix #1 may be determined based on the precoding matrices of some or all of the subbands; correspondingly, the access network device may determine precoding matrix #1 based on the precoding matrices of some or all of the subbands. For example, if the first signal is transmitted through some of the subbands, precoding matrix #1 may be determined based on those subbands. Or, for example, if the first signal is transmitted through all of the subbands, precoding matrix #1 may be determined based on all of the subbands. Furthermore, the granularity of precoding performed by the access network device may be the same as or different from the granularity of the subbands, without limitation.

[0226] Optionally, the first signal may be a downlink signal, for example, the first signal may be PDSCH.

[0227] Among some possible approaches, the method shown in Figure 3 also includes S304:

[0228] S304: The access network device sends a first instruction message; correspondingly, the terminal receives the first instruction message.

[0229] The first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all the subbands.

[0230] Optionally, the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all the subbands. This can be understood as: the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all the subbands; or, the first indication information can be used to instruct the terminal to send precoding matrix indications for a portion of the subbands among all the subbands.

[0231] In some implementations, the first indication information may explicitly instruct the terminal to provide precoding matrix indications for a portion of the subbands among all subbands. For example, when the value of the first indication information is #1 (e.g., 0 or 1), the first indication information may instruct the terminal to provide precoding matrix indications for a portion of the subbands among all subbands.

[0232] In other implementations, the first indication information may implicitly instruct the terminal to feed back precoding matrix indications for a portion of the subbands among all subbands. Optionally, the first indication information may be used to indicate the method of feeding back CSI. If the first indication information indicates that the method of feeding back CSI is a first feedback method, then the first indication information may be used to instruct the terminal to feed back precoding matrix indications for a portion of the subbands among all subbands; in other words, if the first indication information indicates that the method of feeding back CSI is a first feedback method, then the terminal may feed back precoding matrix indications for a portion of the subbands among all subbands. For example, the terminal may execute S302.

[0233] Optionally, the method of feeding back CSI can be replaced by at least one of the following: feeding back a precoding matrix, feeding back a PMI, compressing CSI, compressing a precoding matrix, or compressing a PMI.

[0234] Optionally, the CSI feedback method includes, but is not limited to, at least one of the following: Method 1 (or Type 1), Method 2 (or Type 2), or a first feedback method (or a new method, first feedback type, or new type). Wherein, when the CSI feedback method is Method 1, the precoding matrix is ​​a precoding matrix based on the Type 1 codebook; details can be found in the protocol's description of the Type 1 codebook. When the CSI feedback method is Method 2, the precoding matrix is ​​a precoding matrix based on the Type 2 codebook; details can be found in the protocol's description of the Type 2 codebook.

[0235] When the CSI feedback method is the first feedback method, the terminal can feedback the precoding matrix of a portion of all subbands. The access network device can interpolate the precoding matrix of this portion of subbands according to the first interpolation method to obtain the precoding matrix corresponding to each of all subbands. Alternatively, when the CSI feedback method is the first feedback method, the precoding matrix (or CSI or PMI) can be compressed and / or fed back based on the manifold. Optionally, the first feedback method may include one or more of feedback method #1, feedback method #2, or feedback method #3.

[0236] When the CSI feedback method is feedback method #1, the precoding matrix (or CSI or PMI) can be compressed and / or fed back based on the manifold. In other words, the first indication information can indicate the method of interpolation for each subband, or the first indication information can indicate interpolation for each subband. Accordingly, the access network device can interpolate the precoding matrix of this part of the subband for each subband to obtain the precoding matrix corresponding to each subband. For example, the access network device can interpolate the precoding matrix of this part of the subband according to the above method a1 to obtain the precoding matrix corresponding to each subband.

[0237] When the CSI feedback method is feedback method #2, the precoding matrix (or CSI or PMI) can be compressed and / or fed back based on the manifold for flow combination. In other words, the first indication information can indicate the method of flow combination interpolation, or the first indication information can indicate flow combination interpolation. Accordingly, the access network device can interpolate the precoding matrix of this part of the subband according to the flow combination to obtain the precoding matrix corresponding to each of the subbands. For example, the access network device can interpolate the precoding matrix of this part of the subband according to the above method a2 to obtain the precoding matrix corresponding to each of the subbands.

[0238] When the CSI feedback method is feedback method #3, the precoding matrix (or CSI or PMI) can be compressed and / or fed back based on the manifold for all flows. In other words, the first indication information can indicate a method of interpolation based on all flows, or the first indication information can indicate interpolation based on all flows. Accordingly, the access network device can interpolate the precoding matrix of this sub-band according to all flows to obtain the precoding matrices corresponding to each sub-band. For example, the access network device can interpolate the precoding matrix of this sub-band according to method a2 above to obtain the precoding matrices corresponding to each sub-band. The first matrix can be a first precoding matrix, the second matrix can be a second precoding matrix, and the third matrix can be a third precoding matrix. Optionally, the method of interpolation based on all flows can be a possible example of a flow-by-flow combined interpolation method; correspondingly, feedback method #3 can be a possible example of feedback method #2.

[0239] The specific content of all sub-bands can be found in the description of all sub-bands in S302 above, and will not be repeated here. Optionally, the first feedback method is different from methods 1 and 2. The first feedback method may also have other names, such as method 3 or type 3, as long as it has the same function, it is within the protection scope of this application.

[0240] In some implementations, upon the fulfillment of the first condition, the access network device may send first indication information; correspondingly, the terminal receives the first indication information. Exemplarily, the first condition may include at least one of conditions a1 to a6 below. Any one of the first to sixth thresholds below may be predefined, such as those specified in a protocol; or it may be determined by the access network device; or it may be notified to the access network device by other means (e.g., core network device or terminal). Any one of the first to sixth thresholds may also have other names, as long as they have the same function, they are all within the scope of protection of this application. The first condition is described in detail below.

[0241] Condition a1: The number of transmit antennas of the access network device is greater than or equal to the first threshold. For example, if the first threshold is 256 and the number of transmit antennas of the access network device is greater than or equal to 256, then condition a1 is satisfied.

[0242] Condition a2: The number of receiving antennas of the terminal is greater than or equal to the second threshold. For example, if the second threshold is 8 and the number of transmitting antennas of the terminal is greater than or equal to 8, then condition a2 is satisfied. Optionally, the access network device may receive information from the terminal indicating the number of receiving antennas of the terminal, thereby determining the number of receiving antennas of the terminal, and thus determining whether condition a2 is satisfied.

[0243] Condition a3: The number of sub-bands in all sub-bands is greater than or equal to the third threshold. For example, if the third threshold is 13, and the number of sub-bands in all sub-bands is greater than or equal to 13, then condition a3 is satisfied. For details regarding all sub-bands, please refer to the explanation of all sub-bands in S302, which will not be repeated here.

[0244] Condition a4: The number of antenna ports occupied by the reference signal is greater than or equal to the fourth threshold. For example, if the fourth threshold is 256, and the number of antenna ports occupied by the reference signal is greater than or equal to 256, then condition a4 is satisfied.

[0245] Condition a5: The number of streams corresponding to downlink data transmission is less than or equal to the fifth threshold. For example, if the fifth threshold is 4, and the number of streams corresponding to downlink data transmission is less than or equal to 4, then condition a5 is satisfied.

[0246] Condition a6: The number of streams corresponding to downlink data transmission is greater than or equal to the sixth threshold. For example, if the sixth threshold is 8, and the number of streams corresponding to downlink data transmission is greater than or equal to 8, then condition a6 is satisfied.

[0247] In some examples, the first condition may include: condition a1, condition a2, and condition a3. For example, the first condition includes: the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than or equal to 8, and the number of subbands in all subbands is greater than or equal to 13. If the number of transmit antennas of the access network device is 512, the number of receive antennas of the terminal is 16, and the number of subbands in all subbands is 16, then the first condition is met, and the first indication information may indicate that the CSI feedback method is the first feedback method.

[0248] In other examples, the first condition may include: condition a1, condition a2, condition a3, and condition a5. For example, the first condition includes: the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than or equal to 8, the number of subbands in all subbands is greater than or equal to 13, and the number of streams corresponding to downlink data transmission is less than or equal to 4. If the number of transmit antennas of the access network device is 512, the number of receive antennas of the terminal is 16, the number of subbands in all subbands is 16, and the number of streams corresponding to downlink data transmission is 4, then the first condition is met, and the first indication information may indicate that the CSI feedback method is the first feedback method. For example, the first indication information may indicate that the CSI feedback method is feedback method #1.

[0249] In some examples, the first condition may include: condition a1, condition a2, condition a3, and condition a6. For example, the first condition includes: the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than or equal to 8, the number of subbands in all subbands is greater than or equal to 13, and the number of streams corresponding to downlink data transmission is greater than or equal to 4. If the number of transmit antennas of the access network device is 512, the number of receive antennas of the terminal is 16, the number of subbands in all subbands is 16, and the number of streams corresponding to downlink data transmission is 8, then the first condition is met, and the first indication information may indicate that the CSI feedback method is the first feedback method. For example, the first indication information may indicate that the CSI feedback method is feedback method #2.

[0250] It should be understood that the numbers in the first condition above are merely examples and are not intended to limit the scope of protection of this application. For example, other values ​​may also be used for the numbers in the first condition.

[0251] Optionally, before sending the first indication information, the access network device may obtain a correspondence between at least one condition and at least one method (hereinafter referred to as the first correspondence). The at least one condition may include a first condition, and the at least one method may include a first feedback method corresponding to the first condition. Thus, the access network device may send the first indication information when the first condition is met, and the first indication information may indicate that the method of feedback CSI is the first feedback method.

[0252] Each of the at least one methods may be a method for providing CSI feedback. For example, at least one method may include at least one of the following: Method 1, Method 2, or a first feedback method. The specific details of Method 1, Method 2, and the first feedback method can be found in the descriptions of Method 1, Method 2, and the first feedback method above, and will not be repeated here.

[0253] Optionally, the at least one condition may also include a second condition, and the at least one method may include a conventional feedback method corresponding to the second condition, such as method 1 or method 2.

[0254] The first correspondence can be pre-defined, such as as specified in the protocol; or it can be determined by the access network device; or it can be notified to the access network device by other devices (e.g., core network device or terminal).

[0255] For example, Table 2 shows one possible example of the correspondence between at least one condition and at least one manner.

[0256] Table 2

[0257] It should be understood that Table 2 is merely an example and is not intended to limit the scope of protection of this application. In practical applications, Table 2 may also be modified in other ways, such as including more or fewer rows and / or columns, without limitation.

[0258] In S304, the first indication information can be carried in a conventional message or in a new message. For example, the first indication information can be carried in downlink control information (DCI), medium access control (or media access control, MAC) control element (MAC CE), or radio resource control (RRC) messages.

[0259] The first indication information may have other names, such as CSI feedback method indication information or PMI feedback method indication information, and there are no restrictions.

[0260] Optionally, S304 can precede S302; this application does not restrict the execution order of S304 and S301.

[0261] In this method, the terminal can feed back a precoding matrix indication of a partial subband to the access network device according to the device's instructions, thereby saving the overhead of feeding back the precoding matrix. Furthermore, in this method, the operation of the terminal feeding back the precoding matrix indication of a partial subband to the access network device can be instructed by the access network device itself, thus improving the flexibility of the access network device in managing the terminal.

[0262] Among other possible approaches, the method shown in Figure 3 also includes S305:

[0263] S305: The terminal sends the first instruction information; correspondingly, the access network device receives the first instruction information.

[0264] The first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the subbands among all subbands. For details regarding the first indication information, please refer to the description of the first indication information in S304, which will not be repeated here.

[0265] In some implementations, if the first condition is met, the terminal may send a first indication message; correspondingly, the access network device receives the first indication message. For details of the first condition, please refer to the description of the first condition in S304; repeated details will not be elaborated upon here.

[0266] Optionally, when the first condition includes condition a1 (i.e., the number of transmit antennas of the access network device is greater than or equal to a first threshold), the terminal can receive information from the access network device indicating the number of transmit antennas of the access network device, thereby determining the number of transmit antennas of the access network device, and thus determining whether condition a1 is satisfied. When the first condition includes condition a3 (i.e., the number of subbands in all subbands is greater than or equal to a third threshold), the terminal can receive information from the access network device to determine the number of subbands in all subbands, thereby determining the number of subbands in all subbands, and thus determining whether condition a3 is satisfied. When the first condition includes condition a4 (i.e., the number of antenna ports in all antenna ports occupied by the reference signal is greater than or equal to a fourth threshold), the terminal can receive information from the access network device to determine the number of antenna ports in all antenna ports, thereby determining the number of antenna ports in all antenna ports, and thus determining whether condition a4 is satisfied. When the first condition includes condition a5 (i.e., the number of streams corresponding to the downlink data transmission is less than or equal to the fifth threshold), the terminal can receive information from the access network device to determine the number of streams corresponding to the downlink data transmission, thereby determining the number of streams corresponding to the downlink data transmission, and thus determining whether condition a5 is satisfied. When the first condition includes condition a6 (i.e., the number of streams corresponding to the downlink data transmission is greater than or equal to the sixth threshold), the terminal can receive information from the access network device to determine the number of streams corresponding to the downlink data transmission, thereby determining the number of streams corresponding to the downlink data transmission, and thus determining whether condition a6 is satisfied.

[0267] Optionally, before sending the first indication information, the terminal may obtain a correspondence between at least one condition and at least one method (hereinafter referred to as the first correspondence). The at least one condition may include a first condition, and the at least one method may include a first feedback method corresponding to the first condition. Thus, the terminal may send the first indication information when the first condition is met, and the first indication information may indicate that the method of feedback CSI is the first feedback method.

[0268] The specific details of the at least one method can be found in the description of the at least one method in S304, and will not be repeated here.

[0269] The first correspondence can be pre-set, such as as specified by a protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., core network equipment or access network equipment).

[0270] In S305, the first indication information can be carried in a conventional message or in a new message. For example, the first indication information can be carried in uplink control information (UCI), MAC CE, or RRC messages.

[0271] The first indication information may have other names, such as CSI feedback method indication information or PMI feedback method indication information, and there are no restrictions.

[0272] Optionally, the order of steps S305 and any of S301 to S302 is not limited; S305 may precede S303; the first instruction information and the first information may be carried in the same message, or they may be carried in different messages.

[0273] In this method, the terminal can indicate to the access network device that it is feeding back a precoding matrix indication for a portion of the sub-bands. This allows the access network device to interpolate the precoding matrix of the portion of the sub-bands to obtain the precoding matrix for all sub-bands. Furthermore, in this method, the operation of the terminal feeding back the precoding matrix indication for the portion of the sub-bands to the access network device can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0274] Optionally, S304 and S305 can be understood as different ways of instructing the terminal to provide feedback on the precoding matrix indication of some subbands among all subbands. For example, S304 can be understood as indication method #a1, and S305 can be understood as indication method #a2.

[0275] In some other possible ways, S302 may include: if the first condition is met, the terminal sends first information; accordingly, the access network device receives the first information.

[0276] For example, the first condition may include at least one of conditions a1 to a6. The specific contents of the first condition and conditions a1 to a6 can be found in the descriptions of the first condition and conditions a1 to a6 in S304 and S305, respectively, and will not be repeated here.

[0277] In this method, the terminal can determine the precoding matrix of a portion of the subband to be fed back to the access network device based on a first condition, thereby saving the overhead of feeding back the precoding matrix. Furthermore, in this method, the access network device may not instruct the terminal to feed back the precoding matrix of a portion of the subband to the access network device, thereby reducing signaling overhead. Moreover, in this method, the operation of the terminal feeding back the precoding matrix of a portion of the subband to the access network device can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0278] Among some possible approaches, the method shown in Figure 3 further includes step A1:

[0279] Step A1: The access network device sends the second indication information; correspondingly, the terminal receives the second indication information.

[0280] The second indication information can be used to indicate that the CSI feedback method is a traditional feedback method, such as method 1 or method 2. The specific details of the CSI feedback method, method 1, and method 2 can be found in the descriptions of the CSI feedback method, method 1, and method 2 in S304, and will not be repeated here. This traditional feedback method may also have other names, such as second feedback method, second feedback type, etc., without limitation.

[0281] In some implementations, upon the fulfillment of the second condition, the access network device may send second indication information; correspondingly, the terminal receives the second indication information. Exemplarily, the second condition may include at least one of conditions b1 to b6 below. Any one of the seventh to twelfth thresholds below may be predefined, such as those specified in a protocol; or it may be determined by the access network device; or it may be notified to the access network device by other means (e.g., core network device or terminal). Any one of the seventh to twelfth thresholds may also have other names, as long as they have the same function, they are all within the scope of protection of this application. The second condition is described in detail below.

[0282] Condition b1: The number of transmit antennas of the access network device is less than or equal to the seventh threshold. For example, if the seventh threshold is 32 and the number of transmit antennas of the access network device is less than or equal to 32, then condition b1 is satisfied.

[0283] Condition b2: The number of receiving antennas of the terminal is less than or equal to the eighth threshold. For example, if the eighth threshold is 8 and the number of transmitting antennas of the terminal is less than or equal to 8, then condition b2 is satisfied. Optionally, the access network device may receive information from the terminal indicating the number of receiving antennas of the terminal, thereby determining the number of receiving antennas of the terminal, and thus determining whether condition b2 is satisfied.

[0284] Condition b3: The number of sub-bands in all sub-bands is less than or equal to the ninth threshold. For example, if the ninth threshold is 13, and the number of sub-bands in all sub-bands is less than or equal to 13, then condition b3 is satisfied. For details regarding all sub-bands, please refer to the explanation of all sub-bands in S302; it will not be repeated here.

[0285] Condition b4: The number of antenna ports occupied by the reference signal is less than or equal to the tenth threshold. For example, if the tenth threshold is 32 and the number of antenna ports occupied by the reference signal is less than or equal to 32, then condition b4 is satisfied.

[0286] Condition b5: The number of streams corresponding to downlink data transmission is greater than or equal to the eleventh threshold. For example, if the eleventh threshold is 8, and the number of streams corresponding to downlink data transmission is greater than or equal to 8, then condition b5 is satisfied.

[0287] Condition b6: The number of streams corresponding to downlink data transmission is less than or equal to the twelfth threshold. For example, if the twelfth threshold is 4, and the number of streams corresponding to downlink data transmission is less than or equal to 4, then condition b6 is satisfied.

[0288] In some examples, the second condition may include: condition b1, condition b2, and condition b3. For example, the second condition includes: the number of transmit antennas of the access network device is less than or equal to 32, the number of receive antennas of the terminal is less than or equal to 8, and the number of subbands in all subbands is less than or equal to 13. If the number of transmit antennas of the access network device is 16, the number of receive antennas of the terminal is 4, and the number of subbands in all subbands is 10, then the second condition is met, and the second indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0289] In some examples, the second condition may include: condition b1, condition b2, condition b3, and condition b6. For example, the second condition includes: the number of transmit antennas of the access network device is less than or equal to 32, the number of receive antennas of the terminal is less than or equal to 8, the number of subbands in all subbands is less than or equal to 13, and the number of streams corresponding to downlink data transmission is less than or equal to 4. If the number of transmit antennas of the access network device is 16, the number of receive antennas of the terminal is 4, the number of subbands in all subbands is 10, and the number of streams corresponding to downlink data transmission is 4, then the second condition is met, and the second indication information may indicate that the CSI feedback method is mode 1 or mode 2.

[0290] It should be understood that the numbers in the second condition above are merely examples and are not intended to limit the scope of protection of this application. For example, other values ​​may also be used for the numbers in the second condition.

[0291] Optionally, before sending the second indication information, the access network device may obtain the correspondence between at least one condition and at least one method. For details, please refer to the description of "the access network device can obtain the correspondence between at least one condition and at least one method" in S304; repeated descriptions will not be repeated here. The at least one condition may include a second condition, and the at least one method may include a conventional feedback method corresponding to the second condition. Thus, the access network device may send the second indication information when the second condition is met.

[0292] In step A1, the second indication information can be carried in a conventional message or in a new message. For example, the second indication information can be carried in a DCI, MAC CE, or RRC message.

[0293] The second instruction information may have other names, such as CSI feedback method instruction information or PMI feedback method instruction information, etc., without restriction.

[0294] In some other possible approaches, the method shown in Figure 3 further includes step B1:

[0295] Step B1: The terminal sends the second instruction information; correspondingly, the access network device receives the second instruction information.

[0296] The second indication information can be used to indicate that the CSI feedback method is the traditional feedback method. For details on the content of the second indication information, please refer to the explanation of the second indication information in step A1, which will not be repeated here.

[0297] In some implementations, if the second condition is met, the terminal can send the second indication information; correspondingly, the access network device receives the second indication information. The specific content of the second condition can be found in the description of the second condition in step A1; repeated details will not be elaborated upon here.

[0298] Optionally, when the second condition includes condition b1 (i.e., the number of transmit antennas of the access network device is less than or equal to the seventh threshold), the terminal can receive information from the access network device indicating the number of transmit antennas of the access network device, thereby determining the number of transmit antennas of the access network device, and thus determining whether condition b1 is satisfied. When the second condition includes condition b3 (i.e., the number of subbands in all subbands is less than or equal to the ninth threshold), the terminal can receive information from the access network device to determine the number of subbands in all subbands, thereby determining the number of subbands in all subbands, and thus determining whether condition b3 is satisfied. When the second condition includes condition b4 (i.e., the number of antenna ports in all antenna ports occupied by the reference signal is less than or equal to the tenth threshold), the terminal can receive information from the access network device to determine the number of antenna ports in all antenna ports, thereby determining the number of antenna ports in all antenna ports, and thus determining whether condition b4 is satisfied. When the second condition includes condition b5 (i.e., the number of streams corresponding to the downlink data transmission is greater than or equal to the eleventh threshold), the terminal can receive information from the access network device to determine the number of streams corresponding to the downlink data transmission, thereby determining the number of streams corresponding to the downlink data transmission, and thus determining whether condition b5 is satisfied. When the second condition includes condition b6 (i.e., the number of streams corresponding to the downlink data transmission is less than or equal to the twelfth threshold), the terminal can receive information from the access network device to determine the number of streams corresponding to the downlink data transmission, thereby determining the number of streams corresponding to the downlink data transmission, and thus determining whether condition b6 is satisfied.

[0299] Optionally, before sending the second instruction information, the terminal may obtain the correspondence between at least one condition and at least one method. For details, please refer to the description of "the terminal may obtain the correspondence between at least one condition and at least one method" in S305; repeated descriptions will not be repeated here. The at least one condition may include a second condition, and the at least one method may include a conventional feedback method corresponding to the second condition. Thus, the terminal may send the second instruction information when the second condition is met.

[0300] In step B1, the second indication information can be carried in a conventional message or in a new message. For example, the second indication information can be carried in a UCI, MAC CE, or RRC message.

[0301] The second instruction information may have other names, such as CSI feedback method instruction information or PMI feedback method instruction information, etc., without restriction.

[0302] In some implementations, when the second indication information indicates that the CSI feedback method is mode 1, the terminal sends a PMI determined according to the type 1 codebook; correspondingly, the access network device receives the PMI determined according to the type 1 codebook. This application does not limit the method of determining the PMI according to the type 1 codebook; for example, the method specified in the protocol can be used.

[0303] In other implementations, when the second indication information indicates that the CSI feedback method is mode 2, the terminal sends the PMI determined according to the type 2 codebook; correspondingly, the access network device receives the PMI determined according to the type 2 codebook. This application does not limit the method of determining the PMI according to the type 2 codebook; for example, the method specified in the protocol can be used.

[0304] Among other possible approaches, the method shown in Figure 3 further includes step C1:

[0305] Step C1: If the second condition is met, the terminal sends a PMI determined according to the Type 1 codebook; correspondingly, the access network device receives the PMI determined according to the Type 1 codebook. Alternatively, if the second condition is met, the terminal sends a PMI determined according to the Type 2 codebook; correspondingly, the access network device receives the PMI determined according to the Type 2 codebook.

[0306] The specific details of the second condition can be found in the explanation of the second condition in step B1, and will not be repeated here.

[0307] This application does not restrict the method of determining PMI based on the Type 1 codebook; for example, it can be determined using the method specified in the protocol. This application does not restrict the method of determining PMI based on the Type 2 codebook; for example, it can be determined using the method specified in the protocol.

[0308] Among some possible approaches, the method shown in Figure 3 also includes S306:

[0309] S306: The access network device sends the second information; correspondingly, the terminal receives the second information.

[0310] The second information may be used to indicate at least one of the following: the at least one sub-band, or the number of sub-bands in the at least one sub-band. For example, the second information may indicate the at least one sub-band. Alternatively, the second information may indicate the at least one sub-band and the number of sub-bands in the at least one sub-band. This application does not limit the manner in which the second information is indicated; for example, it may be explicitly indicated or implicitly indicated.

[0311] In some implementations, for each stream corresponding to downlink data transmission, the second information may indicate at least one of the following: at least one subband, or the number of subbands in at least one subband. For example, the streams corresponding to downlink data transmission include streams #1 to #3. For stream #1, the second information may indicate subband #1, subband #3, and subband #5; correspondingly, the terminal may feed back the precoding vector corresponding to stream #1 in the precoding matrix of subband #1, the precoding vector corresponding to stream #1 in the precoding matrix of subband #3, and the precoding vector corresponding to stream #1 in the precoding matrix of subband #5 through the first information. For stream #2, the second information may indicate subband #1 and subband #5; correspondingly, the terminal may feed back the precoding vector corresponding to stream #2 in the precoding matrix of subband #1, and the precoding vector corresponding to stream #2 in the precoding matrix of subband #5 through the first information. For stream #3, the second information can indicate subband #1, subband #3 and subband #5; correspondingly, the terminal can feed back the precoding vector corresponding to stream #3 in the precoding matrix of subband #1 through the first information, feed back the precoding vector corresponding to stream #3 in the precoding matrix of subband #3 through the first information, and feed back the precoding vector corresponding to stream #3 in the precoding matrix of subband #5 through the first information.

[0312] In other implementations, for each stream combination corresponding to downlink data transmission, the second information may indicate at least one of the following for each stream combination: at least one subband, or the number of subbands in at least one subband. For example, the streams corresponding to downlink data transmission include streams #1 to #3. For a stream combination including streams #1 and #2, the second information may indicate subband #1, subband #3, and subband #5; correspondingly, the terminal may feed back the precoding vectors corresponding to streams #1 and #2 in the precoding matrix of subband #1, the precoding vectors corresponding to streams #1 and #2 in the precoding matrix of subband #3, and the precoding vectors corresponding to streams #1 and #2 in the precoding matrix of subband #5 through the first information. For stream #3, the second information may indicate subbands #1 and #5; correspondingly, the terminal may feed back the precoding vectors corresponding to stream #3 in the precoding matrix of subband #1 and the precoding vectors corresponding to stream #3 in the precoding matrix of subband #5 through the first information.

[0313] In some implementations, for all streams corresponding to downlink data transmission, the second information may indicate at least one of the following: at least one subband, or the number of subbands in at least one subband. For example, the streams corresponding to downlink data transmission include streams #1 to #3. If the second information indicates subband #1, subband #3, and subband #5, the terminal can feed back the precoding vectors corresponding to streams #1 to #3 in the precoding matrix of subband #1 through the first information, the precoding vectors corresponding to streams #1 to #3 in the precoding matrix of subband #3 through the first information, and the precoding vectors corresponding to streams #1 to #3 in the precoding matrix of subband #5 through the first information.

[0314] In S306, the second information can be carried in a traditional message or in a new message. For example, the second information can be carried in a DCI, MAC CE, or RRC message.

[0315] The second information may have other names, such as sub-band indication information, etc., without restriction.

[0316] Optionally, S306 may precede S302; this application does not limit the execution order of any of the steps S306, S301, and S304; the second information and the first instruction information may be carried in the same message or in different messages, without limitation.

[0317] In this manner, the terminal can accurately determine the at least one sub-band and / or the number of sub-bands within the at least one sub-band based on the second information. Furthermore, in this method, the at least one sub-band and / or the number of sub-bands within the at least one sub-band can be indicated by the access network device, thereby improving the flexibility of the access network device in managing the terminal.

[0318] Among other possible approaches, the method shown in Figure 3 also includes S307:

[0319] S307: The terminal sends the second information; correspondingly, the access network device receives the second information.

[0320] The second information may be used to indicate at least one of the following: the at least one sub-band, or the number of sub-bands in the at least one sub-band. For details regarding the content of the second information, please refer to the description of the second information in S306, which will not be repeated here.

[0321] In S307, the second information can be carried in a traditional message or in a new message. For example, the second information can be carried in a UCI, MAC CE, or RRC message.

[0322] The second information may have other names, such as sub-band indication information, etc., without restriction.

[0323] Optionally, this application does not limit the execution order of any of the steps S307, S302, and S305; S307 may precede S303; any two of the first information, second information, and first instruction information may be carried in the same message or in different messages, without restriction.

[0324] In this manner, the terminal can indicate the at least one subband and / or the number of subbands within the at least one subband to the access network device, thereby enabling the access network device to interpolate the precoding matrix of a portion of the subbands to obtain the precoding matrix of all the subbands. Furthermore, in this manner, the at least one subband and / or the number of subbands within the at least one subband can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0325] Optionally, the method shown in Figure 3 further includes S308:

[0326] S308: The access network device sends third information; correspondingly, the terminal receives the third information.

[0327] The third information is used to indicate candidate subbands, which include the at least one subband. This application does not limit the manner in which the third information is indicated; for example, it can be explicitly indicated or implicitly indicated.

[0328] In some implementations, the candidate subband includes one or more subbands, and the at least one subband may include some or all of the subbands in the one or more subbands. For example, the candidate subband includes subband #1, subband #3, subband #5 and subband #7, and the at least one subband may include subband #1, subband #3 and subband #5.

[0329] In other implementations, the candidate subband may include multiple sets of subbands, and the at least one subband may include a subband from one of the multiple sets of subbands. For example, the candidate subband may include subband set #1 and subband set #2, and the at least one subband may include a subband from subband set #1.

[0330] In some possible approaches, the at least one subband can be determined (or selected) based on the similarity between different subbands occupied by the reference signal; correspondingly, the terminal can determine (or select) the at least one subband from the candidate subbands based on the similarity between different subbands occupied by the reference signal. Optionally, the higher the similarity between different subbands, the fewer the number of subbands in the at least one subband, and the sparser the distribution of the at least one subband in the frequency domain (or, the larger the interval between adjacent subbands in the frequency domain); the lower the similarity between different subbands, the more the number of subbands in the at least one subband, and the denser the distribution of the at least one subband in the frequency domain (or, the smaller the interval between adjacent subbands in the frequency domain). In this way, the terminal can balance the similarity between different subbands and the number of subbands corresponding to the feedback precoding matrix, thereby minimizing the number of subbands corresponding to the feedback precoding matrix and reducing the overhead of the feedback precoding matrix while ensuring the accuracy and precision of interpolation.

[0331] For example, the candidate subbands include subband #1, subband #3, subband #5, subband #7, and subband #10. If the similarity between the different subbands is greater than or equal to a first similarity threshold, then the at least one subband may include subband #1, subband #5, and subband #10. If the similarity between the different subbands is less than the first similarity threshold, then the at least one subband may include subband #1, subband #3, subband #5, subband #7, and subband #10.

[0332] For example, the candidate subbands include subband set #1 and subband set #2. Subband set #1 includes subband #1, subband #3, subband #5, subband #7, and subband #10. Subband set #2 includes subband #1, subband #5, and subband #10. If the similarity between the different subbands is greater than or equal to a first similarity threshold, then the at least one subband may include subbands from subband set #2, that is, the at least one subband includes subband #1, subband #5, and subband #10. If the similarity between the different subbands is less than the first similarity threshold, then the at least one subband may include subbands from subband set #1, that is, the at least one subband includes subband #1, subband #3, subband #5, subband #7, and subband #10.

[0333] The first similarity threshold can be preset, such as as specified in the protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., access network equipment or core network equipment).

[0334] Optionally, the similarity between different sub-bands occupied by the reference signal can be understood as at least one of the following: the similarity between different channels corresponding to different sub-bands occupied by the reference signal; or, the similarity between different channels corresponding to adjacent sub-bands occupied by the reference signal.

[0335] In some implementations, the similarity between different sub-bands occupied by the reference signal may be related to at least one of the following: the degree of channel variation in the frequency domain (e.g., the degree of channel variation in the frequency domain resources occupied by the reference signal); or, the rate of channel variation in the frequency domain (e.g., the rate of channel variation in the frequency domain resources occupied by the reference signal). Optionally, the faster the channel changes in the frequency domain, for example, the faster the channel changes in the frequency domain resources occupied by the reference signal, the lower the similarity between different sub-bands occupied by the reference signal; the slower the channel changes in the frequency domain, for example, the slower the channel changes in the frequency domain resources occupied by the reference signal, the higher the similarity between different sub-bands occupied by the reference signal. Optionally, the greater the degree of channel variation in the frequency domain, for example, the greater the degree of channel variation in the frequency domain resources occupied by the reference signal, the lower the similarity between different sub-bands occupied by the reference signal; the smaller the degree of channel variation in the frequency domain, for example, the smaller the degree of channel variation in the frequency domain resources occupied by the reference signal, the higher the similarity between different sub-bands occupied by the reference signal.

[0336] Optionally, the similarity between different sub-bands occupied by the reference signal can be determined based on the cosine similarity and / or normalized mean squared error (NMSE) between different channels corresponding to different sub-bands; correspondingly, the at least one sub-band, which can be determined (or selected) based on the similarity between different sub-bands occupied by the reference signal, can be replaced by: the at least one sub-band can be determined based on the cosine similarity and / or NMSE between different channels corresponding to different sub-bands occupied by the reference signal. Optionally, the cosine similarity and / or NMSE between different channels corresponding to different sub-bands can be replaced by: the cosine similarity and / or NMSE between the right singular vectors of different channels corresponding to different sub-bands.

[0337] For example, if the cosine similarity between different channels corresponding to the different sub-bands is greater than or equal to threshold #1, then the similarity between the different sub-bands is greater than or equal to the first similarity threshold; if the cosine similarity between different channels corresponding to the different sub-bands is less than threshold #1, then the similarity between the different sub-bands is less than the first similarity threshold.

[0338] For example, if the NMSE between different channels corresponding to the different sub-bands is greater than threshold #2, then the similarity between the different sub-bands is less than the first similarity threshold; if the NMSE between different channels corresponding to the different sub-bands is less than or equal to threshold #2, then the similarity between the different sub-bands is greater than or equal to the first similarity threshold.

[0339] For example, if the cosine similarity between different channels corresponding to different sub-bands is greater than or equal to threshold #1, and the NMSE between different channels corresponding to different sub-bands is less than or equal to threshold #2, then the similarity between different sub-bands is greater than or equal to the first similarity threshold; if the cosine similarity between different channels corresponding to different sub-bands is less than threshold #1, and the NMSE between different channels corresponding to different sub-bands is greater than threshold #2, then the similarity between different sub-bands is less than the first similarity threshold.

[0340] Among them, any one of the thresholds #1 to #2 can be preset, such as those specified by the protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., core network equipment or access network equipment).

[0341] In S308, third-party information can be carried in traditional messages or in new messages. For example, third-party information can be carried in DCI, MAC CE, or RRC messages.

[0342] The third information may have other names, such as candidate sub-band indication information, etc., without restriction.

[0343] Optionally, S308 can precede S307 and S302; the execution order of S308 and any of the following steps is not limited in this application: the execution order of S301, S304 or S305 is not limited; the third information and the first instruction information can be carried in the same message or in different messages, without limitation.

[0344] Optionally, S306 and S307 can be understood as different ways of indicating the number of sub-bands in the at least one sub-band and / or the number of sub-bands in the at least one sub-band. For example, S306 can be understood as indicating mode #b1, and S307 can be understood as indicating mode #b2. Optionally, indicating mode #b2 may also include S308.

[0345] In some possible embodiments, the at least one subband and / or the number of subbands in at least one subband may be related to at least one of the following; in other words, the at least one subband and / or the number of subbands in at least one subband may correspond to at least one of the following (hereinafter referred to as the second correspondence): the number of transmit antennas of the access network device; the number of receive antennas of the terminal; the number of subbands in all the subbands; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the frequency domain; or, the degree of change of the channel in the frequency domain. For example, the at least one subband and / or the number of subbands in at least one subband may be related to the number of subbands in all the subbands and the number of streams corresponding to downlink data transmission. For another example, the at least one subband and / or the number of subbands in at least one subband may be related to the number of subbands in all the subbands, the number of streams corresponding to downlink data transmission, and the rate of change of the channel in the frequency domain. Yet another example, the at least one subband and / or the number of subbands in at least one subband may be related to the number of subbands in all the subbands, the number of streams corresponding to downlink data transmission, and the degree of change of the channel in the frequency domain. For example, the number of sub-bands in the at least one sub-band and / or the number of sub-bands in the at least one sub-band may be related to the rate of change of the channel in the frequency domain. Alternatively, the number of sub-bands in the at least one sub-band and / or the number of sub-bands in the at least one sub-band may be related to the degree of change of the channel in the frequency domain. Thus, the terminal can determine the number of sub-bands in the at least one sub-band and / or the number of sub-bands in the at least one sub-band according to the second correspondence.

[0346] 1. The number of subbands in at least one subband:

[0347] Optionally, the number of subbands in the at least one subband may be positively correlated with the number of subbands in all subbands. For example, the larger the number of subbands in all subbands, the larger the number of subbands in the at least one subband; and / or, the smaller the number of subbands in all subbands, the smaller the number of subbands in the at least one subband.

[0348] Optionally, for streams with later indices (or sequence numbers, or serial numbers), the number of streams corresponding to downlink data transmission can be positively correlated with the number of subbands in the at least one subband corresponding to that stream. For example, the larger the number of streams corresponding to downlink data transmission, the larger the number of subbands in the at least one subband corresponding to a stream with later indices (or sequence numbers, or serial numbers); and / or, the smaller the number of streams corresponding to downlink data transmission, the smaller the number of subbands in the at least one subband corresponding to a stream with later indices (or sequence numbers, or serial numbers).

[0349] Optionally, the number of sub-bands in the at least one sub-band may be positively correlated with the rate of change of the channel in the frequency domain. For example, the faster the channel changes in the frequency domain, the larger the number of sub-bands in the at least one sub-band; and / or, the slower the channel changes in the frequency domain, the smaller the number of sub-bands in the at least one sub-band.

[0350] Optionally, the number of sub-bands in the at least one sub-band may be positively correlated with the degree of channel variation in the frequency domain. For example, the greater the degree of channel variation in the frequency domain, the greater the number of sub-bands in the at least one sub-band; and / or, the smaller the degree of channel variation in the frequency domain, the smaller the number of sub-bands in the at least one sub-band.

[0351] 2. For at least one sub-band:

[0352] Optionally, the sub-bands in the at least one sub-band may be related to the rate of change of the channel in the frequency domain. For example, the faster the rate of change of the channel in the frequency domain, the denser the distribution of the at least one sub-band in the frequency domain (or, the smaller the spacing between adjacent sub-bands in the frequency domain); and / or, the slower the rate of change of the channel in the frequency domain, the sparser the distribution of the at least one sub-band in the frequency domain (or, the larger the spacing between adjacent sub-bands in the frequency domain).

[0353] Optionally, the sub-bands in the at least one sub-band may be related to the degree of variation of the channel in the frequency domain. For example, the greater the degree of variation of the channel in the frequency domain, the denser the distribution of the at least one sub-band in the frequency domain (or, the smaller the interval between adjacent sub-bands in the frequency domain); and / or, the smaller the degree of variation of the channel in the frequency domain, the sparser the distribution of the at least one sub-band in the frequency domain (or, the larger the interval between adjacent sub-bands in the frequency domain).

[0354] The rate of change and / or degree of change of the channel in the frequency domain are related to the similarity between different sub-bands. The faster the channel changes in the frequency domain, and / or the greater the degree of change, the lower the similarity between different sub-bands (e.g., between adjacent sub-bands); conversely, the slower the channel changes in the frequency domain, and / or the smaller the degree of change, the higher the similarity between different sub-bands (e.g., between adjacent sub-bands). In this way, the terminal can balance the similarity between different sub-bands with the number of sub-bands corresponding to the feedback precoding matrix, thereby minimizing the number of sub-bands corresponding to the feedback precoding matrix and reducing the overhead of the feedback precoding matrix while ensuring the accuracy and precision of interpolation.

[0355] In some implementations, the at least one subband may be selected from all the subbands based on the number of subbands in the at least one subband.

[0356] In some examples, the i-th sub-band among at least one sub-band can be the i-th sub-band among all sub-bands. i is a positive integer. This indicates rounding down. For example, if all subbands include 8 subbands, and the number of subbands in the at least one subband is 3, then the at least one subband includes the first, fourth, and seventh subbands of all subbands.

[0357] In other examples, if the number of subbands in the at least one subband is 2, then the at least one subband can be the first and last subbands among all the subbands.

[0358] In some examples, if the number of subbands in the at least one subband is greater than 2, then the at least one subband may include the first and last subbands of all subbands. The fourth subband is any subband in the at least one subband other than the first and last subbands of all subbands; the fourth subband is the *a*-th subband in the at least one subband, where *a* is a positive integer. The fourth subband can be the *a*-th subband among all subbands. Subband. For example, if all subbands include 8 subbands, and the number of subbands in the at least one subband is 3, then the at least one subband includes the first, fourth, and eighth subbands of all subbands.

[0359] The following provides examples of the at least one subband and / or the number of at least one subband.

[0360] In some examples, if the number of transmitting antennas of the access network device is greater than or equal to 256, the number of receiving antennas of the terminal is greater than 8, the number of subbands in all subbands is less than or equal to 13, and the number of streams corresponding to downlink data transmission is less than or equal to 4, then the number of subbands in the at least one subband is 2, and / or the at least one subband can be the first and last subbands in all subbands.

[0361] In other examples, if the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than 8, the number of subbands in all subbands is greater than 13 and less than or equal to 26, and the number of streams corresponding to downlink data transmission is less than or equal to 4, then the number of subbands in the at least one subband is 3, and / or the at least one subband can be the first subband, the second subband, or the third subband in all subbands. The first sub-band and the last sub-band.

[0362] In other examples, if the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than 8, the number of subbands in all subbands is greater than 26, and the number of streams corresponding to downlink data transmission is less than or equal to 4, then the number of subbands in the at least one subband is 4, and / or the at least one subband can be the first subband, the second subband, or the third subband in all subbands. Individual belt, first The first sub-band and the last sub-band.

[0363] It should be understood that the above examples can be independent or combined with each other.

[0364] The second correspondence can be pre-set, such as as specified in the protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., core network equipment or access network equipment).

[0365] In this method, the terminal can accurately determine the at least one sub-band and / or the number of sub-bands within the at least one sub-band based on the second correspondence. Furthermore, in this method, the access network device may not need to indicate the at least one sub-band and / or the number of sub-bands within the at least one sub-band, thereby reducing signaling overhead. Moreover, in this method, the at least one sub-band and / or the number of sub-bands within the at least one sub-band can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0366] Figure 5 is a flowchart illustrating another communication method provided in an embodiment of this application. In the method shown in Figure 5, the terminal can feed back the precoding vectors of a portion of the antenna ports occupied by the reference signal, and the access network device can interpolate the precoding vectors of that portion of the antenna ports to obtain the precoding vectors of all antenna ports occupied by the reference signal. As shown in Figure 5, the method may include:

[0367] S501: The access network device sends a reference signal; correspondingly, the terminal receives the reference signal.

[0368] For details on S501, please refer to S301; further details will not be provided here.

[0369] S502: The terminal sends the first information; correspondingly, the access network device receives the first information.

[0370] The first information can be used to indicate at least one precoding vector. This application does not limit the manner in which the first information indicates the at least one precoding vector; for example, it can be indicated in a manner specified by a protocol. The at least one precoding vector is determined based on a reference signal; correspondingly, the terminal can determine the at least one precoding vector based on the reference signal. This application does not limit the manner in which "the terminal can determine the at least one precoding vector based on the reference signal"; for example, it can be determined in a manner specified by a protocol.

[0371] The following describes at least one precoded vector.

[0372] 1. The at least one precoded vector includes a precoded vector for each of at least one antenna port, wherein the at least one antenna port may be a subset of all antenna ports occupied by the reference signal. Optionally, the at least one antenna port may be continuous or discontinuous in the spatial domain.

[0373] For example, as shown in FIG6A, the reference signal occupies antenna ports #1 to #11; the at least one antenna port may include antenna port #1, antenna port #7 and antenna port #11, and correspondingly, the first information may indicate: the precoding vector V1 of antenna port #1, the precoding vector V2 of antenna port #7 and the precoding vector V3 of antenna port #11.

[0374] Optionally, the at least one antenna port can be understood as an antenna port in the first set of antenna ports; or, the at least one antenna port can be replaced by the first set of antenna ports. The first set of antenna ports may include a portion of all antenna ports occupied by the reference signal. For example, the reference signal occupies antenna ports #1 to #6; the first set of antenna ports may include antenna port #1, antenna port #3, and antenna port #5, and correspondingly, the first information may indicate: the precoding vector of antenna port #1, the precoding vector of antenna port #3, and the precoding vector of antenna port #5.

[0375] Optionally, all antenna ports occupied by the reference signal can be replaced with all antenna ports configured (or scheduled, or indicated, or allocated) by the access network device for the terminal for transmitting downlink data. For example, the antenna ports configured (or scheduled, or indicated, or allocated) by the access network device for the terminal for transmitting downlink data include antenna ports #1 to #6; the at least one antenna port may include antenna port #1, antenna port #3, and antenna port #5, and correspondingly, the first information may indicate: the precoding vector of antenna port #1, the precoding vector of antenna port #3, and the precoding vector of antenna port #5.

[0376] In some implementations, the at least one precoding vector may correspond to the at least one antenna port; for example, the at least one precoding vector may correspond one-to-one with the at least one antenna port.

[0377] Optionally, the at least one precoding vector may be at least two precoding vectors, and the at least one antenna port may be at least two antenna ports.

[0378] 2. The at least one precoding vector can be interpolated using the second interpolation method to obtain precoding vectors corresponding to each of the antenna ports; correspondingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. Optionally, the second interpolation method is a manifold interpolation method.

[0379] For details regarding the specifics of all antenna ports, please refer to the description of all antenna ports above; further details will not be repeated here.

[0380] Optionally, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to all antenna ports respectively. This can include: the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to all antenna ports respectively; correspondingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors for all antenna ports other than the at least one antenna port, thereby obtaining precoding vectors corresponding to all antenna ports respectively.

[0381] For example (hereinafter referred to as Example 4), all antenna ports include antenna ports #1 to #6; the first information may indicate: the precoding vector of antenna port #1, the precoding vector of antenna port #3, and the precoding vector of antenna port #5. The precoding vectors of antenna port #1, antenna port #3, and antenna port #5 can be interpolated using a second interpolation method to obtain the precoding vectors of antenna port #2, antenna port #4, and antenna port #6, thereby obtaining the precoding vectors corresponding to all antenna ports respectively; correspondingly, the access network device can interpolate the precoding vectors of antenna port #1, antenna port #3, and antenna port #5 using the second interpolation method to obtain the precoding vectors of antenna port #2, antenna port #4, and antenna port #6, thereby obtaining the precoding vectors corresponding to all antenna ports respectively.

[0382] Optionally, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to all antenna ports respectively. This can be understood as: the at least one precoding vector can be used to interpolate using a second interpolation method to obtain the precoding vector corresponding to each antenna port among all antenna ports.

[0383] Optionally, the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports. This can be replaced by: the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports. Accordingly, the access network device can interpolate the at least one precoding vector using the second interpolation method to obtain precoding vectors corresponding to some or all of the antenna ports. The following explanation uses the example of "the at least one precoding vector can be used to interpolate using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports" for illustration.

[0384] Optionally, for the terminal side, "the at least one precoding vector can be used for interpolation using a second interpolation method to obtain the precoding vectors corresponding to all antenna ports respectively" is optional.

[0385] The following is an exemplary description of the implementation of "the at least one precoding vector can be used to interpolate through a second interpolation method to obtain the precoding vectors corresponding to all antenna ports respectively".

[0386] In some possible approaches, the fourth and fifth precoding vectors of the at least one precoding vector can be used to obtain a sixth precoding vector through a second interpolation method; correspondingly, the access network device can interpolate the fourth and fifth precoding vectors of the at least one precoding vector using the second interpolation method to obtain the sixth precoding vector. Wherein, the fourth precoding vector is the precoding vector of the first antenna port among the at least one antenna ports, the fifth precoding vector is the precoding vector of the second antenna port among the at least one antenna ports, and the sixth precoding vector is the precoding vector of the third antenna port, which is any antenna port other than the at least one antenna port among all antenna ports. Optionally, the fourth, fifth, and sixth precoding vectors all correspond to a second flow. Optionally, the second flow can be any flow among the number of flows corresponding to downlink data transmission.

[0387] Optionally, the fourth and fifth precoding vectors in at least one precoding vector can be used to obtain a sixth precoding vector through a second interpolation method, which can be understood as at least one of the following: the fourth and fifth precoding vectors in the at least one precoding vector can be used to interpolate through the second interpolation method to obtain a sixth precoding vector; the sixth precoding vector is obtained by interpolating the fourth and fifth precoding vectors in the at least one precoding vector; or, the sixth precoding vector is obtained by interpolating the fourth and fifth precoding vectors in the at least one precoding vector through the second interpolation method.

[0388] For example (hereinafter referred to as Example 5), the second stream is the first stream in the stream corresponding to the downlink data transmission. As shown in Figure 6B, the fourth precoding vector V 13 Includes: elements in the precoding matrices of subbands #1 to #6 that correspond to the second stream and the first antenna port; the fifth precoding vector V 33 Includes: elements in the precoding matrices of subbands #1 to #6 that correspond to the second stream and the second antenna port; the sixth precoding vector V 23 This includes the elements in the precoding matrices from subband #1 to subband #6 that correspond to the second stream and the third antenna port. V 13 and V 33It can be used to interpolate using the second interpolation method to obtain V. 23 .

[0389] It should be understood that this example is illustrated using the second stream as the first stream in the stream corresponding to downlink data transmission. The second stream can also be any other stream in the stream corresponding to downlink data transmission, without restriction.

[0390] It should be understood that this method is illustrated by taking "the fourth and fifth precoding vectors can be used to obtain the sixth precoding vector through the second interpolation method" as an example. The precoding vector of any antenna port other than the at least one antenna port can be obtained by interpolating two precoding vectors in the at least one precoding vector, thereby obtaining the precoding vectors corresponding to each of the antenna ports.

[0391] In some possible ways, the fourth, fifth, and sixth precoding vectors can satisfy the following formulas (13) to (15):

[0392] in, This is the fourth precoding vector. V is the fifth precoding vector. t2 t2 is the sixth precoding vector, k2 is the index of the first antenna port, k3 is the index of the second antenna port, t2 is the index of the third antenna port, cos() is the cosine function, sin() is the sine function, and acos() is the inverse cosine function. for The conjugate transpose of , || represents taking the absolute value, atan() is the arctangent function, Im() represents taking the imaginary part of the complex number, and Re() represents taking the real part of the complex number.

[0393] For example, in Example 5, For V 13 , For V 33 V t2 For V 23 Access network equipment can be configured according to V 13 V 33 And θ is determined by formula (14), and V is used to determine θ. 13 V 33 And φ is determined by formula (15), so V can be determined according to formula (13). 23 .

[0394] Alternatively, formulas (14) and (15) can be replaced with the following formulas:

[0395] In this method, the access network device can accurately determine the sixth precoding vector based on the fourth and fifth precoding vectors. When the second stream is any stream in the precoding matrix, the access network device can obtain the element corresponding to the third antenna port in each stream of the precoding matrix using this method, thereby accurately determining the precoding matrix. Furthermore, in this method, the access network device can determine the elements in the precoding matrix stream-by-stream, resulting in lower computational complexity.

[0396] The following example illustrates how "the fourth and fifth precoding vectors in the at least one precoding vector can be used to obtain the sixth precoding vector through the second interpolation method," based on the relationship between the first antenna port, the second antenna port, and the third antenna port.

[0397] In some implementations, the third antenna port may be located in the spatial domain between the first and second antenna ports. Optionally, if the indices of the antenna ports in the at least one antenna port are arranged in order in the spatial domain, then "the third antenna port may be located in the spatial domain between the first and second antenna ports" can be replaced with: the index of the third antenna port is located between the index of the first antenna port and the index of the second antenna port. Optionally, the first and second antenna ports may be the two antenna ports that are spatially closest to the third antenna port among the at least one antenna port. In the example below, assume that all antenna ports include antenna ports #1 to #6, and their spatial order is antenna port #1, antenna port #2, antenna port #3, antenna port #4, antenna port #5, and antenna port #6.

[0398] For example, in Example 4, the first antenna port can be antenna port #1, and the fourth precoding vector is the precoding vector of antenna port #1; the second antenna port can be antenna port #3, and the fifth precoding vector is the precoding vector of antenna port #3; the third antenna port is antenna port #2, and the sixth precoding vector is the precoding vector of antenna port #2. Antenna port #2 is located in the spatial domain between antenna port #1 and antenna port #3. The precoding vectors of antenna port #1 and antenna port #3 can be interpolated using the second interpolation method to obtain the precoding vector of antenna port #2; correspondingly, the access network device can interpolate the precoding vectors of antenna port #1 and antenna port #3 using the second interpolation method to obtain the precoding vector of antenna port #2.

[0399] For example, in Example 4, the first antenna port can be antenna port #3, and the fourth precoding vector is the precoding vector of antenna port #3; the second antenna port can be antenna port #5, and the fifth precoding vector is the precoding vector of antenna port #5; the third antenna port is antenna port #4, and the sixth precoding vector is the precoding vector of antenna port #4. Antenna port #4 is located in the spatial domain between antenna port #3 and antenna port #5. The precoding vectors of antenna port #3 and antenna port #5 can be interpolated using the second interpolation method to obtain the precoding vector of antenna port #4; correspondingly, the access network device can interpolate the precoding vectors of antenna port #3 and antenna port #5 using the second interpolation method to obtain the precoding vector of antenna port #4.

[0400] This implementation allows the precoding vector of the third antenna port to be obtained by interpolating the precoding vectors of the two antenna ports located on either side of the third antenna port in the spatial domain, thereby improving the accuracy and precision of the determined precoding vector of the third antenna port.

[0401] In other implementations, the third antenna port may be located on the same side of the first and second antenna ports in the spatial domain. Optionally, if the indices of the antenna ports in the at least one antenna port are arranged in spatial order, then "the third antenna port may be located on the same side of the first and second antenna ports in the spatial domain" can be replaced with: the index of the third antenna port is greater than the index of the first antenna port and the index of the second antenna port, or the index of the third antenna port is less than the index of the first antenna port and the index of the second antenna port. In the example below, assume that all antenna ports include antenna ports #1 to #6, and their spatial order is antenna port #1, antenna port #2, antenna port #3, antenna port #4, antenna port #5, and antenna port #6.

[0402] For example, in Example 4, the first antenna port can be antenna port #1, and the fourth precoding vector is the precoding vector of antenna port #1; the second antenna port can be antenna port #5, and the fifth precoding vector is the precoding vector of antenna port #5; the third antenna port is antenna port #6, and the sixth precoding vector is the precoding vector of antenna port #6. Antenna port #6 is located on the same side of antenna port #1 and antenna port #5 in the spatial domain. The precoding vectors of antenna port #1 and antenna port #5 can be interpolated using the second interpolation method to obtain the precoding vector of antenna port #6; correspondingly, the access network device can interpolate the precoding vectors of antenna port #1 and antenna port #5 using the second interpolation method to obtain the precoding vector of antenna port #6.

[0403] Optionally, when the third antenna port is located on the same side of the first antenna port and the second antenna port in the airspace, the first antenna port and the second antenna port can be the two antenna ports that are closest to the third antenna port in the airspace among the at least one antenna port.

[0404] For example, in Example 4, the first antenna port can be antenna port #3, and the fourth precoding vector is the precoding vector of antenna port #3; the second antenna port can be antenna port #5, and the fifth precoding vector is the precoding vector of antenna port #5; the third antenna port is antenna port #6, and the sixth precoding vector is the precoding vector of antenna port #6. Antenna port #6 is located on the same side of antenna ports #3 and #5 in the spatial domain. The precoding vectors of antenna port #3 and #5 can be interpolated using the second interpolation method to obtain the precoding vector of antenna port #6; correspondingly, the access network device can interpolate the precoding vectors of antenna port #3 and #5 using the second interpolation method to obtain the precoding vector of antenna port #6.

[0405] Through this implementation, the precoding vector of the third antenna port is obtained by interpolating the precoding vectors of the two antenna ports located on the same side of the third antenna port in the spatial domain. This allows for accurate determination of the precoding vector of the third antenna port, and enables the determination of the precoding vector of the third antenna port even when the first information does not indicate the precoding vectors of the two antenna ports located on both sides of the third antenna port.

[0406] In S502, the first information can be carried in a traditional message or in a new message, without restriction.

[0407] Optionally, the first information may be PMI, or the first information may be CSI including PMI.

[0408] Using the method shown in Figure 5, the terminal can send first information, which can be used to indicate the precoding vectors of a portion of the antenna ports occupied by the reference signal. The access network device can then interpolate the precoding vectors of this portion of antenna ports to obtain the precoding vectors corresponding to each of the antenna ports. In this method, the terminal does not need to feed back the precoding vector corresponding to each of the antenna ports, thereby reducing the overhead of feeding back the precoding vectors and, consequently, the overhead of feeding back the precoding matrix.

[0409] When applied to massive MIMO technology, this method can significantly reduce the overhead of the feedback precoding matrix. For example, massive MIMO technology may have a large number of antennas, resulting in a large number of antenna ports. Since the number of rows in the precoding matrix equals the number of transmit antenna ports, the feedback overhead of the precoding matrix for each subband increases with the number of antenna ports. This method can feed back only the precoding vectors of a portion of the antenna ports, without feeding back the precoding vectors of every single antenna port, thereby significantly reducing the overhead of feeding back the precoding vectors, and consequently significantly reducing the overhead of the feedback precoding matrix.

[0410] Alternatively, since the terminal may not need to feed back the precoding vector for each antenna port, this method can improve the accuracy of the fed-back precoding vector without changing the overhead of the fed-back precoding vector, thereby improving the accuracy of the precoding vector recovered by the access network equipment.

[0411] Among some possible approaches, the method shown in Figure 5 also includes S503:

[0412] S503: The access network device sends a first signal; correspondingly, the terminal receives the first signal.

[0413] The first signal is transmitted according to precoding matrix #2; or, the access network device may transmit the first signal according to precoding matrix #2. Precoding matrix #2 may be determined based on the precoding vectors of some or all of the antenna ports; or, the access network device may determine precoding matrix #2 based on the precoding vectors of some or all of the antenna ports. For example, if the first signal is transmitted through some of the antenna ports, precoding matrix #2 may be determined based on some of the antenna ports. Or, for example, if the first signal is transmitted through all of the antenna ports, precoding matrix #2 may be determined based on all of the antenna ports.

[0414] Optionally, the first signal may be a downlink signal, for example, the first signal may be PDSCH.

[0415] Among some possible approaches, the method shown in Figure 5 also includes S504:

[0416] S504: The access network device sends a first instruction message; correspondingly, the terminal receives the first instruction message.

[0417] The first indication information can be used to instruct the terminal to provide a precoding matrix indication for a portion of the antenna ports among all the antenna ports.

[0418] Optionally, the first indication information can be used to instruct the terminal to feed back the precoding matrix indication of a portion of the antenna ports among all the antenna ports. This can be understood as: the first indication information can be used to instruct the terminal to feed back the precoding vector of a portion of the antenna ports among all the antenna ports; or, the first indication information can be used to instruct the terminal to send the precoding matrix indication of a portion of the antenna ports among all the antenna ports.

[0419] In some implementations, the first indication information may explicitly instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports. For example, when the value of the first indication information is #2 (e.g., 0 or 1), the first indication information may instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports.

[0420] In other implementations, the first indication information may implicitly instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports among all antenna ports. Optionally, the first indication information may be used to indicate the method of feeding back CSI. If the first indication information indicates that the method of feeding back CSI is a first feedback method, then the first indication information may instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports among all antenna ports; in other words, if the first indication information indicates that the method of feeding back CSI is a first feedback method, then the terminal may feed back precoding matrix indications for a portion of the antenna ports among all antenna ports. For example, the terminal may execute S502. The specific content of the method of feeding back CSI can be found in the description of "method of feeding back CSI" in S304, and will not be repeated here.

[0421] In some implementations, when the first condition is met, the access network device may send the first indication information; accordingly, the terminal receives the first indication information. For details, please refer to the explanation in S304 that "in some implementations, when the first condition is met, the access network device may send the first indication information; accordingly, the terminal receives the first indication information", which will not be repeated here.

[0422] Optionally, before sending the first indication information, the access network device may obtain a correspondence between at least one condition and at least one method (hereinafter referred to as the first correspondence). The at least one condition may include a first condition, and the at least one method may include a first feedback method corresponding to the first condition. Thus, the access network device may send the first indication information when the first condition is met, and the first indication information may indicate that the method for feeding back CSI is the first feedback method. The specific content of the first correspondence can be found in the description of the first correspondence in S304, and will not be repeated here.

[0423] In S504, the first indication information can be carried in a conventional message or in a new message. For example, the first indication information can be carried in a DCI, MAC CE, or RRC message.

[0424] The first indication information may have other names, such as CSI feedback method indication information or PMI feedback method indication information, and there are no restrictions.

[0425] Optionally, S504 can precede S502. This application does not restrict the execution order of S504 and S501.

[0426] In this method, the terminal can feed back precoding matrix indications for some antenna ports to the access network device according to the instructions of the access network device, thereby saving the overhead of feeding back the precoding matrix. Furthermore, in this method, the operation of the terminal feeding back precoding matrix indications for some antenna ports to the access network device can be instructed by the access network device itself, thereby improving the flexibility of the access network device in managing the terminal.

[0427] Among other possible approaches, the method shown in Figure 5 also includes S505:

[0428] S505: The terminal sends the first instruction information; correspondingly, the access network device receives the first instruction information.

[0429] The first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports. The specific content of the first indication information can be found in the description of the first indication information in S504, and will not be repeated here.

[0430] In some implementations, if the first condition is met, the terminal may send a first indication message; correspondingly, the access network device receives the first indication message. The specific content of the first condition can be found in the descriptions of the first condition in S305 and S504, and will not be repeated here.

[0431] Optionally, before sending the first indication information, the terminal may obtain a correspondence between at least one condition and at least one method. The at least one condition may include a first condition, and the at least one method may include a first feedback method corresponding to the first condition. Thus, the terminal may send the first indication information when the first condition is met, and the first indication information may indicate that the method for providing CSI feedback is the first feedback method. The specific content of the first correspondence can be found in the description of the first correspondence in S305, and will not be repeated here.

[0432] In S505, the first indication information can be carried in a traditional message or in a new message. For example, the first indication information can be carried in a UCI, MAC CE, or RRC message.

[0433] The first indication information may have other names, such as CSI feedback method indication information or PMI feedback method indication information, and there are no restrictions.

[0434] Optionally, the order of steps S505 and any of S501 to S502 is not limited; S505 may precede S503; the first instruction information and the first information may be carried in the same message, or they may be carried in different messages.

[0435] In this method, the terminal can instruct the access network device to provide a precoding matrix indication for a portion of the antenna ports. This allows the access network device to interpolate the precoding vectors of the selected antenna ports to obtain the precoding vectors for all antenna ports. Furthermore, the operation of the terminal providing the precoding matrix indication for the selected antenna ports can be determined by the terminal itself, thereby improving the flexibility of terminal operation.

[0436] Optionally, S504 and S505 can be understood as different ways of instructing the terminal to provide feedback on the precoding matrix indication of a portion of the antenna ports among all antenna ports. For example, S504 can be understood as indication method #c1, and S505 can be understood as indication method #c2.

[0437] In some other possible ways, S502 may include: when the first condition is met, the terminal sends the first information; accordingly, the access network device receives the first information. For details, please refer to the description of "when the first condition is met, the terminal sends the first information; accordingly, the access network device receives the first information" in the method shown in Figure 3, which will not be repeated here.

[0438] In this method, the terminal can determine the precoding vectors for feeding back a portion of the antenna ports to the access network device based on a first condition, thereby saving the overhead of feeding back the precoding vectors and, consequently, the overhead of the feeding back the precoding matrix. Furthermore, in this method, the access network device may not instruct the terminal to feed back the precoding vectors for a portion of the antenna ports to the access network device, thus reducing signaling overhead. Moreover, in this method, the operation of feeding back the precoding vectors for a portion of the antenna ports to the access network device can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0439] Among some possible approaches, the method shown in Figure 5 further includes step D1:

[0440] Step D1: The access network device sends the second indication information; correspondingly, the terminal receives the second indication information.

[0441] The second indication information can be used to indicate that the CSI feedback method is a traditional feedback method, such as method 1 or method 2.

[0442] The details of step D1 can be found in step A1 of the method shown in Figure 3, and will not be repeated here.

[0443] In some other possible approaches, the method shown in Figure 5 further includes step E1:

[0444] Step E1: The terminal sends the second instruction information; correspondingly, the access network device receives the second instruction information.

[0445] The second indication information can be used to indicate that the CSI feedback method is the traditional feedback method.

[0446] The details of step E1 can be found in step B1 of the method shown in Figure 3, and will not be repeated here.

[0447] Among other possible approaches, the method shown in Figure 5 further includes step F1:

[0448] Step F1: If the second condition is met, the terminal sends a PMI determined according to the Type 1 codebook; correspondingly, the access network device receives the PMI determined according to the Type 1 codebook. Alternatively, if the second condition is met, the terminal sends a PMI determined according to the Type 2 codebook; correspondingly, the access network device receives the PMI determined according to the Type 2 codebook.

[0449] The details of step F1 can be found in step C1 of the method shown in Figure 3, and will not be repeated here.

[0450] Among some possible approaches, the method shown in Figure 5 also includes S506:

[0451] S506: The access network device sends the fourth information; correspondingly, the terminal receives the fourth information.

[0452] The fourth information is used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports among the at least one antenna port. For example, the fourth information may indicate the at least one antenna port. Alternatively, the fourth information may indicate the at least one antenna port and the number of antenna ports among the at least one antenna port. This application does not limit the manner in which the fourth information is indicated; for example, it may be explicitly indicated or implicitly indicated.

[0453] In some implementations, for each stream corresponding to downlink data transmission, the fourth information may indicate at least one of the following for that stream: at least one antenna port, or the number of antenna ports among at least one antenna port. For example, the streams corresponding to downlink data transmission include streams #1 to #3. For stream #1, the fourth information may indicate antenna port #1, antenna port #3, and antenna port #5; correspondingly, the precoding vectors of antenna ports #1, #3, and #5 indicated by the first information all include elements corresponding to stream #1. For stream #2, the fourth information may indicate antenna ports #1 and #5; correspondingly, the precoding vectors of antenna ports #1 and #5 indicated by the first information all include elements corresponding to stream #2. For stream #3, the fourth information may indicate antenna ports #1, #3, and #5; correspondingly, the precoding vectors of antenna ports #1, #3, and #5 indicated by the first information all include elements corresponding to stream #3.

[0454] In other implementations, for each stream combination corresponding to downlink data transmission, the fourth information may indicate at least one of the following for each stream combination: at least one antenna port, or the number of antenna ports in at least one antenna port. For example, the streams corresponding to downlink data transmission include streams #1 to #3. For a stream combination including streams #1 and #2, the fourth information may indicate antenna port #1, antenna port #3, and antenna port #5; correspondingly, the precoding vectors of antenna ports #1, #3, and #5 indicated by the first information all include elements corresponding to streams #1 and #2. For stream #3, the fourth information may indicate antenna ports #1 and #5; correspondingly, the precoding vectors of antenna ports #1 and #5 indicated by the first information all include elements corresponding to stream #3.

[0455] In other implementations, for all streams corresponding to downlink data transmission, the fourth information may indicate at least one of the following: at least one antenna port, or the number of antenna ports among at least one antenna port. For example, the streams corresponding to downlink data transmission include streams #1 to #3. If the fourth information can indicate antenna port #1, antenna port #3, and antenna port #5, then the precoding vectors of antenna ports #1, #3, and #5 indicated by the first information all include the elements corresponding to streams #1 to #3.

[0456] In S506, the fourth message can be carried in a traditional message or in a new message. For example, the fourth message can be carried in a DCI, MAC CE, or RRC message.

[0457] The fourth piece of information may have other names, such as antenna port indication information, and there are no restrictions.

[0458] Optionally, S506 may precede S502; this application does not limit the execution order of any of the steps in S506, S501, and S504; the fourth information and the first instruction information may be carried in the same message or in different messages, without limitation.

[0459] In this manner, the terminal can accurately determine the at least one antenna port and / or the number of antenna ports among the at least one antenna port based on the fourth information. Furthermore, in this method, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be indicated by the access network device, thereby improving the flexibility of the access network device in managing the terminal.

[0460] Among other possible approaches, the method shown in Figure 5 also includes S507:

[0461] S507: The terminal sends the fourth information; correspondingly, the access network device receives the fourth information.

[0462] The fourth information is used to indicate at least one of the following: at least one antenna port, or the number of antenna ports among at least one antenna port. For details on the fourth information, please refer to the description of the fourth information in S506, which will not be repeated here.

[0463] In S507, the fourth message can be carried in a traditional message or in a new message. For example, the fourth message can be carried in a UCI, MAC CE, or RRC message.

[0464] The fourth piece of information may have other names, such as antenna port indication information, and there are no restrictions.

[0465] Optionally, this application does not limit the execution order of any of the steps S507, S502, and S505; S507 may precede S503; any two of the first information, fourth information, and first instruction information may be carried in the same message or in different messages, without restriction.

[0466] In this manner, the terminal can indicate the at least one antenna port and / or the number of antenna ports among the at least one antenna port to the access network device, thereby enabling the access network device to interpolate the precoding vectors of some antenna ports to obtain the precoding vectors of all antenna ports. Furthermore, in this manner, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0467] Optionally, the method shown in Figure 5 further includes S508:

[0468] S508: The access network device sends the fifth information; correspondingly, the terminal receives the fifth information.

[0469] The fifth piece of information is used to indicate a candidate antenna port, which includes the at least one antenna port. This application does not limit the manner in which the fifth piece of information is indicated; for example, it can be explicitly indicated or implicitly indicated.

[0470] In some implementations, the candidate antenna port includes one or more antenna ports, and the at least one antenna port may include some or all of the one or more antenna ports. For example, the candidate antenna port includes antenna port #1, antenna port #3, antenna port #5, and antenna port #7, and the at least one antenna port may include antenna port #1, antenna port #3, and antenna port #5.

[0471] In other implementations, the candidate antenna port may include multiple sets of antenna ports, and the at least one antenna port may include an antenna port from one of the multiple sets of antenna ports. For example, the candidate antenna port may include antenna port set #1 and antenna port set #2, and the at least one antenna port may include an antenna port from antenna port set #1.

[0472] In some possible approaches, the at least one antenna port can be determined (or selected) based on the similarity between different antenna ports occupied by the reference signal; correspondingly, the terminal can determine (or select) the at least one antenna port from the candidate antenna ports based on the similarity between different antenna ports occupied by the reference signal. Optionally, the higher the similarity between the different antenna ports, the fewer the number of antenna ports in the at least one antenna port, and the sparser the spatial distribution of the at least one antenna port (or, the larger the spatial interval between adjacent antenna ports in the at least one antenna port); the lower the similarity between the different antenna ports, the more the number of antenna ports in the at least one antenna port, and the denser the spatial distribution of the at least one antenna port (or, the smaller the spatial interval between adjacent antenna ports in the at least one antenna port). In this way, the terminal can balance the similarity between antenna ports and the number of antenna ports corresponding to the feedback precoding vector, thereby minimizing the number of antenna ports corresponding to the feedback precoding vector and reducing the overhead of the feedback precoding matrix while ensuring the accuracy and precision of interpolation.

[0473] For example, the candidate antenna ports include antenna port #1, antenna port #3, antenna port #5, antenna port #7, and antenna port #10. If the similarity between the different antenna ports is greater than or equal to a second similarity threshold, then the at least one antenna port may include antenna port #1, antenna port #5, and antenna port #10. If the similarity between the different antenna ports is less than the second similarity threshold, then the at least one antenna port may include antenna port #1, antenna port #3, antenna port #5, antenna port #7, and antenna port #10.

[0474] For example, the candidate antenna ports include antenna port set #1 and antenna port set #2. Antenna port set #1 includes antenna port #1, antenna port #3, antenna port #5, antenna port #7, and antenna port #10. Antenna port set #2 includes antenna port #1, antenna port #5, and antenna port #10. If the similarity between the different antenna ports is greater than or equal to a second similarity threshold, then the at least one antenna port may include antenna ports from antenna port set #2, that is, the at least one antenna port includes antenna port #1, antenna port #5, and antenna port #10. If the similarity between the different antenna ports is less than the second similarity threshold, then the at least one antenna port may include antenna ports from antenna port set #1, that is, the at least one antenna port includes antenna port #1, antenna port #3, antenna port #5, antenna port #7, and antenna port #10.

[0475] The second similarity threshold can be preset, such as as specified in the protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., access network equipment or core network equipment).

[0476] Optionally, the similarity between different antenna ports occupied by the reference signal can be understood as at least one of the following: the similarity between different channels corresponding to different antenna ports occupied by the reference signal; or, the similarity between different channels corresponding to adjacent antenna ports occupied by the reference signal.

[0477] In some implementations, the similarity between different antenna ports occupied by the reference signal may be related to at least one of the following: the degree of channel variation in the spatial domain (e.g., the degree of channel variation in the spatial resources occupied by the reference signal); or the speed of channel variation in the spatial domain (e.g., the speed of channel variation in the spatial resources occupied by the reference signal). Optionally, the faster the channel changes in the spatial domain, for example, the faster the channel changes in the spatial resources occupied by the reference signal, the lower the similarity between different antenna ports occupied by the reference signal; the slower the channel changes in the spatial domain, for example, the slower the channel changes in the spatial resources occupied by the reference signal, the higher the similarity between different antenna ports occupied by the reference signal. Optionally, the greater the degree of channel variation in the spatial domain, for example, the greater the degree of channel variation in the spatial resources occupied by the reference signal, the lower the similarity between different antenna ports occupied by the reference signal; the smaller the degree of channel variation in the spatial domain, for example, the smaller the degree of channel variation in the spatial resources occupied by the reference signal, the higher the similarity between different antenna ports occupied by the reference signal.

[0478] Optionally, the similarity between different antenna ports occupied by the reference signal can be determined based on the cosine similarity and / or NMSE between different channels corresponding to different antenna ports; correspondingly, the at least one antenna port, which can be determined (or selected) based on the similarity between different antenna ports occupied by the reference signal, can be replaced by: the at least one antenna port can be determined based on the cosine similarity and / or NMSE between different channels corresponding to different antenna ports occupied by the reference signal. Optionally, the cosine similarity and / or NMSE between different channels corresponding to different antenna ports can be replaced by: the cosine similarity and / or NMSE between the right singular vectors of different channels corresponding to different antenna ports.

[0479] For example, if the cosine similarity between different channels corresponding to different antenna ports is greater than or equal to threshold #3, then the similarity between different antenna ports is greater than or equal to the second similarity threshold; if the cosine similarity between different channels corresponding to different antenna ports is less than threshold #3, then the similarity between different antenna ports is less than the second similarity threshold.

[0480] For example, if the NMSE between different channels corresponding to different antenna ports is greater than threshold #4, then the similarity between different antenna ports is less than the second similarity threshold; if the NMSE between different channels corresponding to different antenna ports is less than or equal to threshold #4, then the similarity between different antenna ports is greater than or equal to the second similarity threshold.

[0481] For example, if the cosine similarity between different channels corresponding to different antenna ports is greater than or equal to threshold #3, and the NMSE between different channels corresponding to different antenna ports is less than or equal to threshold #4, then the similarity between different antenna ports is greater than or equal to the second similarity threshold; if the cosine similarity between different channels corresponding to different antenna ports is less than threshold #3, and the NMSE between different channels corresponding to different antenna ports is greater than threshold #4, then the similarity between different antenna ports is less than the second similarity threshold.

[0482] Among them, any of the thresholds #3 to #4 can be preset, such as those specified by the protocol; or can be determined by the terminal; or can be notified to the terminal by other devices (e.g., core network equipment or access network equipment).

[0483] In S508, the fifth message can be carried in a traditional message or in a new message. For example, the fifth message can be carried in a DCI, MAC CE, or RRC message.

[0484] The fifth piece of information may have other names, such as candidate antenna port indication information, and there are no restrictions.

[0485] Optionally, S508 can precede S507 and S502; the execution order of S508 and any of the following steps is not limited in this application: the execution order of S501, S504 or S505 is not limited; the fifth information and the first instruction information can be carried in the same message or in different messages, without limitation.

[0486] Optionally, S506 and S507 can be understood as different ways of indicating the at least one antenna port and / or the number of antenna ports in the at least one antenna port. For example, S506 can be understood as indication method #d1, and S507 can be understood as indication method #d2. Optionally, indication method #d2 may also include S508.

[0487] In some possible ways, the at least one antenna port and / or the number of antenna ports in at least one antenna port are related to at least one of the following; in other words, the at least one antenna port and / or the number of antenna ports in at least one antenna port correspond to at least one of the following (hereinafter referred to as the third correspondence): the number of transmitting antennas of the access network device; the number of receiving antennas of the terminal; the number of antenna ports in all antenna ports; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the spatial domain; or the degree of change of the channel in the spatial domain. For example, the at least one antenna port and / or the number of antenna ports in at least one antenna port may be related to the number of antenna ports in all antenna ports and the number of streams corresponding to downlink data transmission. For another example, the at least one antenna port and / or the number of antenna ports in at least one antenna port may be related to the number of antenna ports in all antenna ports, the number of streams corresponding to downlink data transmission, and the rate of change of the channel in the spatial domain. Yet another example, the at least one antenna port and / or the number of antenna ports in at least one antenna port may be related to the number of antenna ports in all antenna ports, the number of streams corresponding to downlink data transmission, and the degree of change of the channel in the spatial domain. For example, the at least one antenna port and / or the number of antenna ports in the at least one antenna port may be related to the rate of change of the channel in the spatial domain. For example, the at least one antenna port and / or the number of antenna ports in the at least one antenna port may be related to the degree of change of the channel in the spatial domain. Thus, the terminal can determine the at least one antenna port and / or the number of antenna ports in the at least one antenna port based on the third correspondence.

[0488] 1. The number of antenna ports in the at least one antenna port:

[0489] Optionally, the number of antenna ports in the at least one antenna port may be positively correlated with the number of antenna ports in all antenna ports. For example, the larger the number of antenna ports in all antenna ports, the larger the number of antenna ports in the at least one antenna port; and / or, the smaller the number of antenna ports in all antenna ports, the smaller the number of antenna ports in the at least one antenna port.

[0490] Optionally, for streams with later indices (or sequence numbers, or serial numbers), the number of streams corresponding to downlink data transmission can be positively correlated with the number of antenna ports in the at least one antenna port corresponding to that stream. For example, the larger the number of streams corresponding to downlink data transmission, the larger the number of antenna ports in the at least one antenna port corresponding to the stream with later indices (or sequence numbers, or serial numbers); and / or, the smaller the number of streams corresponding to downlink data transmission, the smaller the number of antenna ports in the at least one antenna port corresponding to the stream with later indices (or sequence numbers, or serial numbers).

[0491] Optionally, the number of antenna ports in the at least one antenna port may be positively correlated with the rate of change of the channel in the spatial domain. For example, the faster the rate of change of the channel in the spatial domain, the larger the number of antenna ports in the at least one antenna port; and / or, the slower the rate of change of the channel in the spatial domain, the smaller the number of antenna ports in the at least one antenna port.

[0492] Optionally, the number of antenna ports in the at least one antenna port may be positively correlated with the degree of variation of the channel in the spatial domain. For example, the greater the degree of variation of the channel in the spatial domain, the greater the number of antenna ports in the at least one antenna port; and / or, the smaller the degree of variation of the channel in the spatial domain, the smaller the number of antenna ports in the at least one antenna port.

[0493] 2. For at least one antenna port:

[0494] Optionally, the antenna ports of the at least one antenna port may be related to the rate of change of the channel in the spatial domain. For example, the faster the rate of change of the channel in the spatial domain, the denser the distribution of the at least one antenna port in the spatial domain (or, the smaller the spatial spacing between adjacent antenna ports in the at least one antenna port); and / or, the slower the rate of change of the channel in the spatial domain, the sparser the distribution of the at least one antenna port in the spatial domain (or, the larger the spatial spacing between adjacent antenna ports in the at least one antenna port).

[0495] Optionally, the antenna ports of the at least one antenna port may be related to the degree of variation of the channel in the spatial domain. For example, the greater the degree of variation of the channel in the spatial domain, the denser the distribution of the at least one antenna port in the spatial domain (or, the smaller the spatial spacing between adjacent antenna ports in the at least one antenna port); and / or, the smaller the degree of variation of the channel in the spatial domain, the sparser the distribution of the at least one antenna port in the spatial domain (or, the larger the spatial spacing between adjacent antenna ports in the at least one antenna port).

[0496] The rate and / or extent of channel change in the spatial domain are related to the similarity between different antenna ports. The faster the channel changes in the spatial domain, and / or the greater the extent of channel change, the lower the similarity between different antenna ports (e.g., between adjacent antenna ports); conversely, the slower the channel changes in the spatial domain, and / or the smaller the extent of channel change, the higher the similarity between different antenna ports (e.g., between adjacent antenna ports). In this way, the terminal can balance the similarity between different antenna ports with the number of antenna ports corresponding to the feedback precoding vector, thereby minimizing the number of antenna ports corresponding to the feedback precoding vector and reducing the overhead of the feedback precoding matrix while ensuring the accuracy and precision of interpolation.

[0497] In some implementations, the at least one antenna port may be selected from all antenna ports based on the number of antenna ports in the at least one antenna port.

[0498] In some examples, the i-th antenna port among the at least one antenna port can be the i-th antenna port among all the antenna ports. i is a positive integer. For example, if all antenna ports include 8 antenna ports, and the number of antenna ports in the at least one antenna port is 3, then the at least one antenna port includes the first antenna port, the fourth antenna port, and the seventh antenna port in all antenna ports.

[0499] In other examples, if the number of antenna ports in the at least one antenna port is 2, then the at least one antenna port can be the first antenna port and the last antenna port among all the antenna ports.

[0500] In some examples, if the number of antenna ports in the at least one antenna port is greater than 2, then the at least one antenna port may include the first and last antenna ports among all antenna ports. The fourth antenna port is any antenna port among the at least one antenna ports other than the first and last antenna ports among all antenna ports; the fourth antenna port is the *a*-th antenna port among the at least one antenna ports, where *a* is a positive integer. The fourth antenna port may be the *a*-th antenna port among all antenna ports. There are 8 antenna ports. For example, if all antenna ports include 8 antenna ports, and the number of antenna ports in the at least one antenna port is 3, then the at least one antenna port includes the first antenna port, the fourth antenna port, and the eighth antenna port in all antenna ports.

[0501] The following provides examples of the at least one antenna port and / or the number of at least one antenna ports.

[0502] In some examples, if the number of transmitting antennas of the access network device is greater than or equal to 256, the number of receiving antennas of the terminal is less than or equal to 8, and the number of subbands in all subbands is less than or equal to 13, then the number of antenna ports in the at least one antenna port is 2, and / or the at least one antenna port can be the first antenna port and the last subband in all antenna ports.

[0503] In other examples, if the number of transmit antennas of the access network device is greater than or equal to 256, the number of receive antennas of the terminal is greater than 8, and the number of subbands in all subbands is greater than 13, then the number of antenna ports in the at least one antenna port is 4, and / or the at least one antenna port can be the first antenna port, the second antenna port, or the third antenna port among all antenna ports. The antenna port, the first One antenna port and the last sub-band.

[0504] It should be understood that the above examples can be independent or combined with each other.

[0505] The third correspondence can be pre-set, such as as specified in the protocol; or it can be determined by the terminal; or it can be notified to the terminal by other devices (e.g., core network equipment or access network equipment).

[0506] In this method, the terminal can accurately determine the at least one antenna port and / or the number of antenna ports among the at least one antenna port based on the third correspondence. Furthermore, in this method, the access network device may not indicate the at least one antenna port and / or the number of antenna ports among the at least one antenna port, thereby reducing signaling overhead. Moreover, in this method, the at least one antenna port and / or the number of antenna ports among the at least one antenna port can be determined by the terminal, thereby improving the flexibility of terminal operation.

[0507] Figure 7 is a flowchart illustrating a communication method provided in an embodiment of this application. In the method shown in Figure 7, the terminal can feed back the precoding matrix of a portion of the sub-bands occupied by the reference signal, and the access network device can interpolate the precoding matrix of that portion of the sub-bands to obtain the precoding matrix of all sub-bands occupied by the reference signal. The terminal can also feed back the precoding vector of a portion of the antenna ports occupied by the reference signal, and the access network device can interpolate the precoding vector of that portion of the antenna ports to obtain the precoding vector of all antenna ports occupied by the reference signal. As shown in Figure 7, the method may include:

[0508] S701: The access network device sends a reference signal; correspondingly, the terminal receives the reference signal.

[0509] For details on S701, please refer to S301; further details will not be provided here.

[0510] S702: The terminal sends the first information; correspondingly, the access network device receives the first information.

[0511] The first information can be used to indicate at least one precoding matrix and at least one precoding vector. The at least one precoding matrix can be determined based on the reference signal; the at least one precoding matrix can include the precoding matrix of each sub-band in at least one sub-band, and the at least one sub-band can be a portion of all sub-bands occupied by the reference signal; the at least one precoding matrix can be interpolated using a first interpolation method to obtain the precoding matrices corresponding to each of the sub-bands. The at least one precoding vector can be determined based on the reference signal; the at least one precoding vector can include the precoding vector of each antenna port in at least one antenna port, and the at least one antenna port can be a portion of all antenna ports occupied by the reference signal; the at least one precoding vector can be interpolated using a second interpolation method to obtain the precoding vectors corresponding to each of the antenna ports.

[0512] For details of S702, please refer to S302 and S502; repeated parts will not be repeated. For example, the specific content of the first information indicating at least one precoding matrix can be found in the explanation in S302 that "the first information can be used to indicate at least one precoding matrix"; the specific content of the first information indicating at least one precoding vector can be found in the explanation in S502 that "the first information can be used to indicate at least one precoding vector".

[0513] As described in S502, the fourth and fifth precoding vectors in at least one precoding vector can be used to obtain a sixth precoding vector through a second interpolation method; correspondingly, the access network device can interpolate the fourth and fifth precoding vectors in at least one precoding vector using the second interpolation method to obtain the sixth precoding vector. Wherein, the fourth precoding vector is the precoding vector of the first antenna port among the at least one antenna ports, the fifth precoding vector is the precoding vector of the second antenna port among the at least one antenna ports, and the sixth precoding vector is the precoding vector of the third antenna port, which is any antenna port other than the at least one antenna port among all antenna ports. Optionally, the fourth, fifth, and sixth precoding vectors all correspond to the second flow.

[0514] For example, the second stream is the first stream in the stream corresponding to downlink data transmission. As shown in Figure 8, the at least one subband includes subband #1, subband #3, and subband #5; the fourth precoding vector V 13 Includes: elements in the precoding matrices of subband #1, subband #3, and subband #5 that correspond to the second stream and the first antenna port; the fifth precoding vector V 33 Includes: elements in the precoding matrices of subbands #1, #3, and #5 that correspond to the second stream and the second antenna port; the sixth precoding vector V 23 This includes the elements in the precoding matrices of subband #1, subband #3, and subband #5 that correspond to the second stream and the third antenna port. V 13 and V 33 It can be used to interpolate using the second interpolation method to obtain V. 23 .

[0515] It should be understood that this example is illustrated using the second stream as the first stream in the stream corresponding to downlink data transmission. The second stream can also be any other stream in the stream corresponding to downlink data transmission, without restriction.

[0516] Among some possible approaches, the method shown in Figure 7 also includes S703:

[0517] S703: The access network device sends a first signal; correspondingly, the terminal receives the first signal.

[0518] For details on S703, please refer to S303 and S503, which will not be repeated here.

[0519] Among some possible approaches, the method shown in Figure 7 also includes S704:

[0520] S704: The access network device sends a first instruction message; correspondingly, the terminal receives the first instruction message.

[0521] Specifically, the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands; and the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports. For the specific content of the first indication information instructing the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands, please refer to the explanation in S304 regarding "the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands"; for the specific content of the first indication information instructing the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports, please refer to the explanation in S504 regarding "the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports," and will not be repeated here.

[0522] Optionally, S704 can precede S702; this application does not restrict the execution order of S704 and S701.

[0523] Among other possible approaches, the method shown in Figure 7 also includes S705:

[0524] S705: The terminal sends the first instruction information; correspondingly, the access network device receives the first instruction information.

[0525] Specifically, the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands; and the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports. For the specific content of the first indication information instructing the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands, please refer to the explanation in S305 regarding "the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the sub-bands among all sub-bands"; for the specific content of the first indication information instructing the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports, please refer to the explanation in S505 regarding "the first indication information can be used to instruct the terminal to provide precoding matrix indications for a portion of the antenna ports among all antenna ports," and will not be repeated here.

[0526] Optionally, the order of steps S705 and any of S701 to S702 is not limited; S705 may precede S703; the first instruction information and the first information may be carried in the same message, or they may be carried in different messages.

[0527] Optionally, S704 and S705 can be understood as different ways of indicating the following: the terminal feeds back the precoding matrix indication of a portion of the subbands among all the subbands, and the terminal feeds back the precoding matrix indication of a portion of the antenna ports among all the antenna ports. For example, S704 can be understood as indication mode #e1, and S705 can be understood as indication mode #e2.

[0528] In some other possible ways, S702 may include: when the first condition is met, the terminal sends the first information; accordingly, the access network device receives the first information. For details, please refer to the description of "when the first condition is met, the terminal sends the first information; accordingly, the access network device receives the first information" in the method shown in Figure 3, which will not be repeated here.

[0529] Among some possible approaches, the method shown in Figure 7 further includes step G1:

[0530] Step G1: The access network device sends the second indication information; correspondingly, the terminal receives the second indication information.

[0531] The second indication information can be used to indicate that the CSI feedback method is a traditional feedback method, such as method 1 or method 2.

[0532] The details of step G1 can be found in step A1 of the method shown in Figure 3, and will not be repeated here.

[0533] In some other possible approaches, the method shown in Figure 7 further includes step H1:

[0534] Step H1: The terminal sends the second indication information; correspondingly, the access network device receives the second indication information.

[0535] The second indication information can be used to indicate that the CSI feedback method is the traditional feedback method.

[0536] The details of step H1 can be found in step B1 of the method shown in Figure 3, and will not be repeated here.

[0537] Among other possible approaches, the method shown in Figure 7 further includes step I1:

[0538] Step I1: If the second condition is met, the terminal sends a PMI determined according to the Type 1 codebook; correspondingly, the access network device receives the PMI determined according to the Type 1 codebook. Alternatively, if the second condition is met, the terminal sends a PMI determined according to the Type 2 codebook; correspondingly, the access network device receives the PMI determined according to the Type 2 codebook.

[0539] The details of step I1 can be found in step C1 of the method shown in Figure 3, and will not be repeated here.

[0540] Among some possible approaches, the method shown in Figure 7 also includes S706:

[0541] S706: The access network device sends the second information; correspondingly, the terminal receives the second information.

[0542] The second information may be used to indicate at least one of the following: the at least one sub-band, or the number of sub-bands in the at least one sub-band. For example, the second information may indicate the at least one sub-band.

[0543] For details on S706, please refer to S306; further details will not be provided here.

[0544] Optionally, S706 may precede S702; this application does not limit the execution order of any of the steps S706, S701, and S704; the second information and the first instruction information may be carried in the same message or in different messages, without limitation.

[0545] Among other possible approaches, the method shown in Figure 7 also includes S707:

[0546] S707: The terminal sends the second information; correspondingly, the access network device receives the second information.

[0547] The second information may be used to indicate at least one of the following: the at least one sub-band, or the number of sub-bands in the at least one sub-band.

[0548] For details on S707, please refer to S307; further details will not be provided here.

[0549] Optionally, this application does not limit the execution order of any of the steps in S707, S702, and S705; any two of the first information, the second information, and the first instruction information can be carried in the same message or in different messages, without restriction.

[0550] Optionally, the method shown in Figure 7 further includes S708:

[0551] S708: The access network device sends third information; correspondingly, the terminal receives the third information.

[0552] The third piece of information is used to indicate candidate subbands, which include the at least one subband.

[0553] For details on S708, please refer to S308; further details will not be provided here.

[0554] Optionally, S708 may precede S707 and S702; the execution order of S708 and any of the following steps is not limited in this application: the execution order of S701, S704 or S705 is not limited; the third information and the first instruction information may be carried in the same message or in different messages, without limitation.

[0555] Optionally, S706 and S707 can be understood as different ways of indicating the at least one sub-band and / or the number of sub-bands in the at least one sub-band. For example, S706 can be understood as indication method #b1, and S707 can be understood as indication method #b2. Optionally, indication method #b2 may also include S708.

[0556] In some possible approaches, the at least one subband and / or the number of subbands in at least one subband may be related to at least one of the following; in other words, the at least one subband and / or the number of subbands in at least one subband may correspond to at least one of the following: the number of transmit antennas of the access network device; the number of receive antennas of the terminal; the number of subbands in all subbands; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the frequency domain; or, the degree of change of the channel in the frequency domain. For details, please refer to the description in the method shown in Figure 3, which will not be repeated here.

[0557] Among some possible approaches, the method shown in Figure 7 also includes S709:

[0558] S709: The access network device sends the fourth information; correspondingly, the terminal receives the fourth information.

[0559] The fourth piece of information is used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports in the at least one antenna port.

[0560] For details on S709, please refer to S506; further details will not be provided here.

[0561] Optionally, S709 may precede S702; the execution order of S709 and any of the following steps is not limited in this application: S701, S704 or S706; any two messages in the fourth information, the second information and the first instruction information may be carried in the same message or in different messages, without limitation.

[0562] Among other possible approaches, the method shown in Figure 7 also includes S710:

[0563] S710: The terminal sends the fourth information; correspondingly, the access network device receives the fourth information.

[0564] The fourth piece of information is used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports in at least one antenna port.

[0565] For details on S710, please refer to S507, which will not be repeated here.

[0566] Optionally, this application does not limit the execution order of S710 with any of the following steps: S702, S705 and S707; S710 may precede S703; any two of the first information, second information, fourth information and first instruction information may be carried in the same message or in different messages, without restriction.

[0567] Optionally, the method shown in Figure 7 further includes S711:

[0568] S711: The access network device sends the fifth information; correspondingly, the terminal receives the fifth information.

[0569] The fifth piece of information is used to indicate candidate antenna ports, which include at least one antenna port.

[0570] For details on S711, please refer to S508, which will not be repeated here.

[0571] Optionally, S711 may precede S710 and S702; the execution order of S711 and any of the following steps is not limited in this application: the execution order of S701, S704, S705 or S707 is not limited; any two of the fifth information, the third information or the first instruction information may be carried in the same message or in different messages, without restriction.

[0572] Optionally, S709 and S710 can be understood as different ways of indicating the at least one antenna port and / or the number of antenna ports in the at least one antenna port. For example, S709 can be understood as indication method #d1, and S710 can be understood as indication method #d2. Optionally, indication method #d2 also includes S711.

[0573] In some possible approaches, the at least one antenna port and / or the number of antenna ports in at least one antenna port are related to at least one of the following; in other words, the at least one antenna port and / or the number of antenna ports in at least one antenna port correspond to at least one of the following (hereinafter referred to as the third correspondence): the number of transmitting antennas of the access network device; the number of receiving antennas of the terminal; the number of antenna ports in all antenna ports; the number of streams corresponding to downlink data transmission; the rate of change of the channel in the spatial domain; or, the degree of change of the channel in the spatial domain. For details, please refer to the description in the method shown in Figure 5, which will not be repeated here.

[0574] The effect of the method shown in Figure 7 can be referred to the explanation of the effects of the methods shown in Figure 3 and Figure 5, and will not be repeated here.

[0575] Based on the same technical concept as the above-described method embodiments, this application provides a corresponding communication device that can be used to perform the functions of the relevant steps in the above-described method embodiments. This function can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. The communication device can be a terminal or access network device, or it can be a device that can be applied to a terminal or access network device (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or it can be a logical node, logical module, or software that can implement all or part of the functions of a terminal or access network device. The device that can be applied to a terminal or access network device can exist independently; for example, it can be independently manufactured, sold, or used.

[0576] In one possible implementation, the communication device provided in this application embodiment has the structure shown in FIG9, including a processing unit 902. Optionally, the communication device further includes an interface unit 901. The functions of each unit in the communication device 900 are described below.

[0577] Interface unit 901 is used for inputting and / or outputting information. Input information can be replaced by received information, and output information can be replaced by transmitted information. When outputting information, interface unit 901 can output information to other devices outside of communication device 900, or to other units within communication device 900. In some embodiments, interface unit 901 can be implemented through at least one of a physical interface, a communication module, a communication interface, and an input / output interface. In other embodiments, interface unit 901 can be implemented through interface circuitry, such as a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, a low-noise amplifier (LNA), etc. Interface unit 901 is used to perform the receiving and transmitting operations in the above method embodiments.

[0578] In this application, the interface unit 901 may also have other names, such as a transceiver unit or a communication unit. Optionally, the interface unit 901 may include a receiving unit and / or a sending unit, used for inputting information and outputting information, respectively. The receiving unit is used to perform the receiving operation in the above method embodiments. The sending unit is used to perform the sending operation in the above method embodiments.

[0579] The processing unit 902 can be used to support the communication device 900 in performing the processing actions in the above method embodiments. The processing unit 902 can be implemented by one or more processors. For example, the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microprocessors (MCUs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor. The processing unit 902 is used to perform processing-related operations in the above method embodiments, for example, to instruct operations other than receiving and transmitting operations in the above method embodiments.

[0580] In one embodiment, the communication device 900 is applied to the terminal shown in FIG3, FIG5 or FIG7 of the present application embodiment. The specific functions of the processing unit 902 in this embodiment are described below.

[0581] Processing unit 902 is configured to: receive a reference signal through interface unit 901; and send first information through interface unit 901, the first information being used to indicate at least one precoding matrix and / or at least one precoding vector; wherein, at least one precoding matrix is ​​determined based on the reference signal, the at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, the at least one sub-band being a portion of all sub-bands occupied by the reference signal, the at least one precoding matrix being used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each sub-band; and at least one precoding vector is determined based on the reference signal, the at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port, the at least one antenna port being a portion of all antenna ports occupied by the reference signal, the at least one precoding vector being used to interpolate using a second interpolation method to obtain the precoding vectors corresponding to each antenna port.

[0582] In some possible ways, the processing unit 902 is also used to: send or receive first indication information through the interface unit 901, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the subbands in all subbands, and / or, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports in all antenna ports.

[0583] In some other possible ways, the processing unit 902 is specifically used to: send first information through the interface unit 901 when the first condition is met.

[0584] In some possible ways, the processing unit 902 is also configured to: receive or send second information through the interface unit 901 when the first information is used to indicate at least one precoding matrix, the second information being used to indicate at least one of the following: at least one subband, or the number of subbands in at least one subband.

[0585] Optionally, the processing unit 902 is further configured to: receive third information through the interface unit 901 when sending second information, the third information being used to indicate candidate subbands, the candidate subbands including at least one subband.

[0586] In some possible ways, the processing unit 902 is also configured to: receive or send fourth information through the interface unit 901 when the first information is used to indicate at least one precoded vector, the fourth information being used to indicate at least one of the following: at least one antenna port, or the number of antenna ports in at least one antenna port.

[0587] Optionally, the processing unit 902 is further configured to: receive fifth information through the interface unit 901 when the fourth information is sent, the fifth information being used to indicate candidate antenna ports, the candidate antenna ports including at least one antenna port.

[0588] In another embodiment, the communication device 900 is applied to the access network device in the embodiment of this application shown in FIG3, FIG5 or FIG7. The specific functions of the processing unit 902 in this embodiment will be described below.

[0589] Processing unit 902 is configured to: transmit a reference signal through interface unit 901; receive first information through interface unit 901, the first information indicating at least one precoding matrix and / or at least one precoding vector; wherein, at least one precoding matrix is ​​determined based on the reference signal, at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, at least one sub-band is a portion of all sub-bands occupied by the reference signal, at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain the precoding matrix corresponding to each sub-band; at least one precoding vector is determined based on the reference signal, at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port, at least one antenna port is a portion of all antenna ports occupied by the reference signal, at least one precoding vector is used to interpolate using a second interpolation method to obtain the precoding vector corresponding to each antenna port.

[0590] In some possible ways, the processing unit 902 is also used to: send or receive first indication information through the interface unit 901, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the subbands in all subbands, and / or, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports in all antenna ports.

[0591] In some other possible ways, the processing unit 902 is specifically used to: receive first information through the interface unit 901 when the first condition is met.

[0592] In some possible ways, the processing unit 902 is also configured to: receive or send second information through the interface unit 901 when the first information is used to indicate at least one precoding matrix, the second information being used to indicate at least one of the following: at least one subband, or the number of subbands in at least one subband.

[0593] Optionally, the processing unit 902 is further configured to: upon receiving the second information, send third information through the interface unit 901, the third information being used to indicate candidate subbands, the candidate subbands including at least one subband.

[0594] In some possible ways, the processing unit 902 is also configured to: receive or send fourth information through the interface unit 901 when the first information is used to indicate at least one precoded vector, the fourth information being used to indicate at least one of the following: at least one antenna port, or the number of antenna ports in at least one antenna port.

[0595] Optionally, the processing unit 902 is further configured to: upon receiving the fourth information, send the fifth information through the interface unit 901, the fifth information being used to indicate candidate antenna ports, the candidate antenna ports including at least one antenna port.

[0596] In some possible ways, the processing unit 902 is specifically used to: interpolate the first precoding matrix and the second precoding matrix in at least one precoding matrix using a first interpolation method to obtain a third precoding matrix; wherein the first precoding matrix is ​​the precoding matrix of the first subband in at least one subband, the second precoding matrix is ​​the precoding matrix of the second subband in at least one subband, and the third precoding matrix is ​​the precoding matrix of the third subband, and the third subband is the subband other than at least one subband among all subbands.

[0597] In some implementations, the processing unit 902 is specifically used to: interpolate the first precoding vector and the second precoding vector using a first interpolation method to obtain a third precoding vector; wherein the first precoding vector is the precoding vector in the first precoding matrix corresponding to the first stream, the second precoding vector is the precoding vector in the second precoding matrix corresponding to the first stream, and the third precoding vector is the precoding vector in the third precoding matrix corresponding to the first stream, and the first stream is any stream corresponding to the third precoding matrix.

[0598] In other implementations, the processing unit 902 is specifically used to: interpolate the first matrix and the second matrix using a first interpolation method to obtain a third matrix; wherein the first matrix includes precoding vectors corresponding to multiple streams in the first precoding matrix, the second matrix includes precoding vectors corresponding to multiple streams in the second precoding matrix, and the third matrix includes precoding vectors corresponding to multiple streams in the third precoding matrix, wherein the multiple streams are some or all of the streams corresponding to the third precoding matrix.

[0599] In some possible ways, the processing unit 902 is specifically used to: interpolate the fourth precoding vector and the fifth precoding vector in at least one precoding vector using a second interpolation method to obtain a sixth precoding vector; wherein the fourth precoding vector is the precoding vector of the first antenna port in at least one antenna port, the fifth precoding vector is the precoding vector of the second antenna port in at least one antenna port, and the sixth precoding vector is the precoding vector of the third antenna port, which is the antenna port other than at least one antenna port among all antenna ports.

[0600] In one possible design, when the communication device 900 is a communication equipment or a communication module within a communication equipment, the functionality of the processing unit 902 can be implemented by one or more processors. For example, the processor may include a modem chip, or a system-on-a-chip (SoC) or SIP chip containing a modem core. The functionality of the interface unit 901 can be implemented by transceiver circuitry.

[0601] In one possible design, when the communication device 900 is a circuit or chip responsible for communication functions in a communication device, such as a modem chip or a system-on-a-chip (SoC) or SIP chip containing a modem core, the function of the processing unit 902 can be implemented by a circuit system in the aforementioned chip that includes one or more processors or processor cores. The function of the interface unit 901 can be implemented by the interface circuit or data transceiver circuit on the aforementioned chip.

[0602] The communication device can be a terminal or an access network device.

[0603] A more detailed description of the processing unit 902 and the interface unit 901 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 3 to 8, and will not be repeated here.

[0604] It should be noted that the module division in the above embodiments of this application is illustrative and only represents a logical functional division. In actual implementation, there may be other division methods. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, exist as separate physical units, or have two or more units integrated into one unit. The integrated units can be implemented in hardware, as software functional units, or in a combination of hardware and software. Whether a function is executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0605] For example, the functional unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, such as one or more ASICs, one or more CPUs, one or more MCUs, one or more DSPs, or one or more FPGAs, or a combination of at least two of these integrated circuit forms.

[0606] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0607] In one possible implementation, the communication device provided in this application embodiment is shown in FIG10. The communication device 1000 includes a processor 1002. Optionally, the communication device 1000 further includes an interface circuit 1001 and a memory 1003. The interface circuit 1001, the processor 1002, and the memory 1003 are coupled to each other.

[0608] Optionally, the interface circuit 1001, processor 1002, and memory 1003 are coupled to each other via bus 1004. Bus 1004 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. Buses can be divided into address buses, data buses, control buses, etc. For ease of illustration, only one thick line is used in Figure 10, but this does not mean that there is only one bus or one type of bus.

[0609] Interface circuit 1001 is used for inputting and / or outputting information. Input information can be replaced with received information, and output information can be replaced with transmitted information. When outputting information, interface circuit 1001 can output information to other devices outside of communication device 1000, or to other units within communication device 1000. For example, interface circuit 1001 can be implemented through at least one of a physical interface, a communication module, a communication interface, an input / output interface, and a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, an LNA, etc. Interface circuit 1001 is used to perform the receiving and transmitting operations in the above method embodiments.

[0610] The interface circuit 1001 may be one of the following: a transceiver, a transceiver circuit, a communication circuit, an interface, a communication interface, or an input / output interface (e.g., a chip's input / output interface). The interface circuit 1001 may include an input interface circuit and an output interface circuit, used for inputting information and outputting information, respectively. The input interface circuit is used to perform the receiving operation in the above method embodiments. The output interface circuit is used to perform the transmitting operation in the above method embodiments.

[0611] The transceiver can be used for communication with other communication devices. For example, if communication device 1000 is a terminal, the transceiver can be used to communicate with access network equipment or with another terminal. As another example, if communication device 1000 is an access network device, the transceiver can be used to communicate with a terminal or with another access network device.

[0612] Optionally, the transceiver may include a receiver and / or a transmitter. The receiver is used to perform the receiving operation in the above method embodiments. The transmitter is used to perform the sending operation in the above method embodiments.

[0613] Optionally, the transceiver can be integrated with the processor 1002 or exist independently and be coupled to the processor 1002 through the interface circuit of the communication device 1000. This application embodiment does not specifically limit this.

[0614] Processor 1002 can be used to support communication device 1000 in performing the processing actions in the above method embodiments. When communication device 1000 is used to implement the above method embodiments, processor 1002 can also be used to implement the functions of processing unit 902. Processor 1002 can be a CPU, or other general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. General-purpose processors can be microprocessors or any conventional processor. Processor 1002 is used to perform processing-related operations in the above method embodiments, for example, to instruct operations other than receiving and sending operations in the above method embodiments.

[0615] In one embodiment, the communication device 1000 is applied to the terminal shown in Figures 3, 5, or 7 of this application. The specific functions of the processor 1002 in this embodiment are described below.

[0616] Processor 1002 is configured to: receive a reference signal via interface circuit 1001; and transmit first information via interface circuit 1001, the first information being used to indicate at least one precoding matrix and / or at least one precoding vector; wherein the at least one precoding matrix is ​​determined based on the reference signal, the at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, the at least one sub-band being a portion of all sub-bands occupied by the reference signal, and the at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each sub-band; and at least one precoding vector is determined based on the reference signal, the at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port, the at least one antenna port being a portion of all antenna ports occupied by the reference signal, and the at least one precoding vector is used to interpolate using a second interpolation method to obtain the precoding vectors corresponding to each antenna port.

[0617] In another embodiment, the communication device 1000 is applied to the access network device in the embodiment of this application shown in FIG3, FIG5 or FIG7. The specific functions of the processor 1002 in this embodiment are described below.

[0618] The processor 1002 is configured to: transmit a reference signal through an interface circuit 1001; receive first information through the interface circuit 1001, the first information indicating at least one precoding matrix and / or at least one precoding vector; wherein the at least one precoding matrix is ​​determined based on the reference signal, the at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, the at least one sub-band is a portion of all sub-bands occupied by the reference signal, the at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each sub-band; the at least one precoding vector is determined based on the reference signal, the at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port, the at least one antenna port is a portion of all antenna ports occupied by the reference signal, the at least one precoding vector is used to interpolate using a second interpolation method to obtain the precoding vectors corresponding to each antenna port.

[0619] The specific functions of processor 1002 can be found in the description of the communication methods provided in the above embodiments and examples of this application, as well as the specific functional description of communication device 900 in the embodiment of this application shown in FIG9, which will not be repeated here.

[0620] Memory 1003 is used to store program instructions and / or data. Specifically, program instructions may include program code, which includes computer operation instructions. Memory 1003 may include RAM and may also include non-volatile memory, such as at least one disk storage device. Processor 1002 executes the program instructions stored in memory 1003 and uses the data stored in memory 1003 to implement the above-mentioned functions, thereby realizing the communication method provided in the embodiments of this application. Memory 1003 may be integrated with processor 1002 or may be a memory outside the communication device.

[0621] It is understood that the memory 1003 in Figure 10 of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be RAM, which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0622] This application also provides a communication device 1100, which can be a terminal, a processor in the terminal, or a chip. The communication device 1100 can be used to perform the operations performed by the first device in the above method embodiments.

[0623] When the communication device 1100 is a terminal, Figure 11 shows a schematic diagram of the terminal structure. As shown in Figure 11, the terminal includes a processor, a memory, and a transceiver. The memory can store computer program code, and the transceiver includes a transmitter 1131, a receiver 1132, radio frequency circuitry (not shown in the figure), an antenna 1133, and input / output devices (not shown in the figure).

[0624] The processor is mainly used to process communication protocols and communication data; control terminals; execute software programs; and process data from software programs.

[0625] Memory is mainly used to store software programs and data.

[0626] Radio frequency (RF) circuits are mainly used for the conversion between baseband signals and RF signals, as well as for the processing of RF signals.

[0627] Antennas are primarily used for transmitting and receiving radio frequency signals in the form of electromagnetic waves.

[0628] Input / output devices can include touchscreens, displays, or keyboards. They are primarily used to receive user input and output data to the user. It should be noted that some types of terminals may not have input / output devices.

[0629] When data needs to be transmitted, the processor performs baseband processing on the data to be transmitted and outputs a baseband signal to the radio frequency (RF) circuit. The RF circuit then processes the baseband signal and transmits it outwards as electromagnetic waves via an antenna. When data is sent to the terminal, the RF circuit receives the RF signal through the antenna. The RF circuit converts the RF signal back into a baseband signal and outputs it to the processor. The processor converts the baseband signal back into data and processes that data.

[0630] For ease of explanation, Figure 11 shows only one memory, processor, and transceiver. In actual terminal products, there may be one or more processors and one or more memories. Memory may also be called storage medium or storage device, etc. Memory may be set up independently of the processor or integrated with the processor; this application embodiment does not impose any limitations on this.

[0631] In the embodiments of this application, the antenna and radio frequency circuit with transceiver functions can be regarded as the interface unit of the terminal, and the processor with processing functions can be regarded as the processing unit of the terminal.

[0632] As shown in Figure 11, the terminal includes a processor 1110, a memory 1120, and a transceiver 1130. The processor 1110 may also be referred to as a processing board, processing module, or processing device. The transceiver 1130 may also be referred to as an interface circuit, transceiver, or transceiver device. The processor 1110 is used to execute the processing operations on the first device side in the above method embodiments. The transceiver 1130 is used to execute the transmit and receive operations on the first device side in the above method embodiments.

[0633] Optionally, the device in transceiver 1130 used for receiving functions can be considered a receiver, and the device in transceiver 1130 used for transmitting functions can be considered a transmitter; that is, transceiver 1130 includes a receiver 1132 and a transmitter 1131. A receiver may also be called a receiver module or receiving circuit, etc. A transmitter may also be called a transmitter, transmitting module, or transmitting circuit, etc. The receiver is used to perform the receiving operation on the first device side in the above method embodiments. The transmitter is used to perform the transmitting operation on the first device side in the above method embodiments.

[0634] It should be understood that Figure 11 is merely an example and not a limitation, and the terminal may not depend on the structure shown in Figure 11.

[0635] When the communication device 1100 is a chip, the chip includes a processor and a transceiver. The transceiver can be an input / output circuit or a communication interface. The processor can be a processing module integrated on the chip, a microprocessor, or an integrated circuit. In the above method embodiments, the transmitting operation of the first device can be understood as the output of the chip, and the receiving operation of the first device in the above method embodiments can be understood as the input of the chip.

[0636] The communication device 1100 may also include a memory, which may be a memory built into the chip or an external memory.

[0637] This application also provides a communication device 1200, which can be an access network device or a chip. The communication device 1200 can be used to perform the operations performed by the second device in the above method embodiments.

[0638] When the communication device 1200 is an access network device, such as a base station, Figure 12 shows a schematic diagram of the structure of an access network device. The access network device includes parts 1210, 1220, and 1230.

[0639] The 1210 section is mainly used for baseband processing and controlling access network equipment; the 1210 section is usually the control center of the base station, which can be called a processor, and is used to control the access network equipment to perform the processing operations on the second device side in the above method embodiment.

[0640] Section 1220 is primarily used to store computer program code and data.

[0641] Section 1230 is primarily used for transmitting and receiving radio frequency (RF) signals, as well as converting RF signals to baseband signals. Section 1230 is commonly referred to as a transceiver module, transceiver, transceiver circuit, interface circuit, or transceiver unit. Section 1230 may include antenna 1233 and RF circuitry (not shown in the figure), where the RF circuitry is mainly used for RF processing. Section 1230 can be used to perform the transmit and receive operations on the second device side in the above method embodiments.

[0642] Optionally, the device used to implement the receiving function in part 1230 can be regarded as a receiver, and the device used to implement the transmitting function can be regarded as a transmitter. That is, part 1230 includes receiver 1232 and transmitter 1231. The receiver can also be called a receiving module, receiver circuit, etc., and the transmitter can be called a transmitting module, transmitter, or transmitting circuit, etc. The receiver is used to perform the receiving operation on the second device side in the above method embodiments. The transmitter is used to perform the transmitting operation on the second device side in the above method embodiments.

[0643] Sections 1210 and 1220 may include one or more single boards, each single board may include one or more processors and one or more memories. The processor is used to read and execute programs in the memory to implement baseband processing functions and control access network devices. If multiple single boards exist, they can be interconnected to enhance processing capabilities. As an optional implementation, multiple single boards may share one or more processors, multiple single boards may share one or more memories, or multiple single boards may simultaneously share one or more processors.

[0644] It should be understood that Figure 12 is merely an example and not a limitation, and access network devices may not depend on the structure shown in Figure 12.

[0645] When the communication device 1200 is a chip, the chip includes a transceiver and a processor. The transceiver can be an input / output circuit or a communication interface; the processor can be a processor integrated on the chip, a microprocessor, or an integrated circuit. In the above method embodiments, the transmitting operation of the second device can be understood as the chip's output, and the receiving operation of the second device in the above method embodiments can be understood as the chip's input.

[0646] The communication device 1200 may also include a memory, which may be a memory built into the chip or an external memory.

[0647] Based on the above embodiments, this application also provides a computer program product including computer-executable instructions, which, when run, causes the methods provided in the above embodiments to be executed.

[0648] Based on the above embodiments, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a computer, causes the computer to perform the methods provided in the above embodiments.

[0649] The storage medium can be any available medium that a computer can access. For example, but not limited to, a computer-readable medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0650] Based on the above embodiments, this application also provides a chip for reading a computer program stored in a memory to implement the method provided in the above embodiments.

[0651] Based on the above embodiments, this application provides a chip system including a processor for supporting a computer device in implementing the functions involved in the devices in the above embodiments. In one possible design, the chip system further includes a memory for storing necessary programs and data of the computer device. The chip system may be composed of chips or may include chips and other discrete components.

[0652] 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.

[0653] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0654] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the comput...

Claims

A communication method, characterized in that, Devices used in or in a terminal, including: Receive reference signal; Send a first message, the first message being used to indicate at least one precoding matrix and / or at least one precoding vector; Wherein, the at least one precoding matrix is ​​determined based on the reference signal, the at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, the at least one sub-band is a portion of all sub-bands occupied by the reference signal, and the at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each of the sub-bands respectively; The at least one precoding vector is determined based on the reference signal. The at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port. The at least one antenna port is a portion of all antenna ports occupied by the reference signal. The at least one precoding vector is used to interpolate using a second interpolation method to obtain the precoding vectors corresponding to each of the antenna ports. The method as described in claim 1, characterized in that, When the first information is used to indicate the at least one precoding matrix, the method further includes: Receive or send a second message, the second message being used to indicate at least one of the following: the at least one subband, or the number of subbands in the at least one subband. The method as described in claim 2, characterized in that, In the case of sending a second message, the method further includes: Receive third information, the third information being used to indicate candidate subbands, the candidate subbands including the at least one subband. The method as described in any one of claims 1 to 3, characterized in that, When the first information is used to indicate the at least one precoded vector, the method further includes: Receive or transmit fourth information, the fourth information being used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports among the at least one antenna port. The method as described in claim 4, characterized in that, In the case of sending a fourth message, the method further includes: Receive fifth information, the fifth information being used to indicate candidate antenna ports, the candidate antenna ports including the at least one antenna port. The method as described in any one of claims 1 to 5, characterized in that, Send the first message, including: If the first condition is met, send the first information. A communication method, characterized in that, A device used in or within an access network device, including: Send a reference signal; Receive first information, the first information being used to indicate at least one precoding matrix and / or at least one precoding vector; Wherein, the at least one precoding matrix is ​​determined based on the reference signal, the at least one precoding matrix includes the precoding matrix of each sub-band in at least one sub-band, the at least one sub-band is a portion of all sub-bands occupied by the reference signal, and the at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain the precoding matrices corresponding to each of the sub-bands respectively; The at least one precoding vector is determined based on the reference signal. The at least one precoding vector includes the precoding vector of each antenna port in at least one antenna port. The at least one antenna port is a portion of all antenna ports occupied by the reference signal. The at least one precoding vector is used to interpolate using a second interpolation method to obtain the precoding vectors corresponding to each of the antenna ports. The method as described in any one of claims 1 to 7, characterized in that, When the first information is used to indicate the at least one precoding matrix, the method further includes: Receive or send a second message, the second message being used to indicate at least one of the following: the at least one subband, or the number of subbands in the at least one subband. The method as described in claim 8, characterized in that, Upon receiving the second information, the method further includes: Send a third message, the third message being used to indicate candidate subbands, the candidate subbands including the at least one subband. The method according to any one of claims 1 to 9, characterized in that, When the first information is used to indicate the at least one precoded vector, the method further includes: Receive or transmit fourth information, the fourth information being used to indicate at least one of the following: the at least one antenna port, or the number of antenna ports among the at least one antenna port. The method as described in claim 10, characterized in that, In the case of receiving a fourth piece of information, the method further includes: A fifth message is sent, which indicates a candidate antenna port, including the at least one antenna port. The method as described in any one of claims 7 to 11, characterized in that, Receive the first message, including: If the first condition is met, the first information is received. The method as described in any one of claims 1 to 5, 7 to 11, is characterized in that, Also includes: Sending or receiving first indication information, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the subbands among all the subbands, and / or, the first indication information being used to instruct the terminal to feed back precoding matrix indications for a portion of the antenna ports among all the antenna ports. The method as described in claim 6 or 12, characterized in that, The first condition includes at least one of the following: The number of transmit antennas of the access network device is greater than or equal to the first threshold. The number of receiving antennas of the terminal is greater than or equal to the second threshold. The number of sub-bands in all sub-bands is greater than or equal to the third threshold; The number of antenna ports in all antenna ports is greater than or equal to the fourth threshold; The number of streams corresponding to downlink data transmission is less than or equal to the fifth threshold; or The number of streams corresponding to downlink data transmission is greater than or equal to the sixth threshold. The method as described in any one of claims 1 to 14, characterized in that, When the first information is used to indicate the at least one precoding matrix, the at least one subband and / or the number of subbands in the at least one subband are related to at least one of the following: The number of transmit antennas of the access network equipment; The number of receiving antennas of the terminal; The number of sub-bands in all sub-bands; or The number of streams corresponding to downlink data transmission. The method as described in any one of claims 1 to 15, characterized in that, When the first information is used to indicate the at least one precoded vector, the at least one antenna port and / or the number of antenna ports among the at least one antenna port is related to at least one of the following: The number of transmit antennas of the access network equipment; The number of receiving antennas of the terminal; The number of antenna ports in all antenna ports; or The number of streams corresponding to downlink data transmission. The method as described in any one of claims 1 to 16, characterized in that, The at least one precoding matrix is ​​used to interpolate using a first interpolation method to obtain precoding matrices corresponding to each of the subbands, including: The first and second precoding matrices in the at least one precoding matrix are used to obtain the third precoding matrix through the first interpolation method; Wherein, the first precoding matrix is ​​the precoding matrix of the first sub-band among the at least one sub-band, the second precoding matrix is ​​the precoding matrix of the second sub-band among the at least one sub-band, the third precoding matrix is ​​the precoding matrix of the third sub-band, and the third sub-band is the sub-band other than the at least one sub-band among all the sub-bands. The method as described in claim 17, characterized in that, The first and second precoding matrices in the at least one precoding matrix are used to obtain a third precoding matrix through the first interpolation method, including: The first and second precoding vectors are used to obtain the third precoding vector through the first interpolation method; wherein, the first precoding vector is the precoding vector in the first precoding matrix corresponding to the first stream, the second precoding vector is the precoding vector in the second precoding matrix corresponding to the first stream, and the third precoding vector is the precoding vector in the third precoding matrix corresponding to the first stream, where the first stream is any stream corresponding to the third precoding matrix; or... The first matrix and the second matrix are used to obtain the third matrix through the first interpolation method; wherein, the first matrix includes precoding vectors corresponding to multiple streams in the first precoding matrix, the second matrix includes precoding vectors corresponding to the multiple streams in the second precoding matrix, and the third matrix includes precoding vectors corresponding to the multiple streams in the third precoding matrix, wherein the multiple streams are some or all of the streams corresponding to the third precoding matrix. The method as described in claim 17 or 18, characterized in that, The third sub-band is located between the first sub-band and the second sub-band in the frequency domain; or, the third sub-band is located on the same side of the first sub-band and the second sub-band in the frequency domain. The method as described in any one of claims 1 to 19, characterized in that, The at least one precoding vector is used for interpolation using a second interpolation method to obtain precoding vectors corresponding to each of the antenna ports, including: The fourth and fifth precoding vectors in the at least one precoding vector are used to obtain the sixth precoding vector through the second interpolation method; Wherein, the fourth precoding vector is the precoding vector of the first antenna port among the at least one antenna port, the fifth precoding vector is the precoding vector of the second antenna port among the at least one antenna port, the sixth precoding vector is the precoding vector of the third antenna port, and the third antenna port is the antenna port other than the at least one antenna port among all the antenna ports. The method as described in claim 20, characterized in that, The fourth, fifth, and sixth precoding vectors all correspond to the second stream. The method as described in claim 20 or 21, characterized in that, The index of the third antenna port is located between the index of the first antenna port and the index of the second antenna port; or, The index of the third antenna port is greater than the index of the first antenna port and the index of the second antenna port; or, The index of the third antenna port is less than the index of the first antenna port and the index of the second antenna port. The method as described in any one of claims 1 to 22, characterized in that, The first interpolation method is a manifold interpolation method, and / or the second interpolation method is a manifold interpolation method. A communication device, characterized in that, Includes a unit for performing the method as described in any one of claims 1-23. A communication device, characterized in that, Includes a processor for executing computer programs or instructions that cause the apparatus to perform the method as described in any one of claims 1-23. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions, which, when executed, implement the method as described in any one of claims 1-23. A computer program product, characterized in that, The computer program product includes: computer program code, wherein when the computer program code is run, the method as described in any one of claims 1-23 is implemented.

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