Feedback method of channel state information and communication device

Abstract

The application discloses a channel state information feedback method and a communication device, which are used for enabling a network device to determine N space-frequency joint vectors representing joint space-frequency domain compression, so as to reduce the feedback overhead of a terminal device. In the method, the terminal device receives a precoded reference signal sent by the network device, and the precoded reference signal is obtained by performing precoding processing on a reference signal according to a space domain basis vector matrix. The space domain basis vector matrix comprises at least one space domain basis vector, and one space domain basis vector is associated with one reference signal port. Then, the terminal device determines channel state information (CSI) according to the precoded reference signal, and sends the CSI to the network device. The CSI comprises first indication information used for indicating M reference signal port-frequency domain basis vector pairs and second indication information used for indicating M groups of first combination coefficients, so as to enable the network device to determine N space-frequency joint vectors according to the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, and in particular to a channel state information feedback method and a communication device. BACKGROUND

[0002] Multiple input and multiple output (MIMO) technology is a core technology of long term evolution (LTE) systems and 5th generation (5G) new radio (NR). MIMO technology plays a crucial role in the spectral efficiency of a communication system. Among them, a network device can determine a precoding matrix used for transmitting downlink data according to precoding matrix indicator (PMI) related information sent by a terminal device.

[0003] At present, a double-domain compression codebook scheme is proposed in the 3GPP release 16 (R16) technical specification, that is, a channel matrix (also referred to as a precoding matrix) is compressed and fed back in the spatial domain and the frequency domain respectively. The channel matrix can be represented by a weighted sum of a spatial-frequency component matrix constructed by at least one spatial basis vector and at least one frequency basis vector. Specifically, a network device sends a reference signal to a terminal device. The terminal device obtains downlink channel information through the reference signal. The terminal device selects a spatial basis vector, a frequency basis vector, and determines the corresponding linear combination coefficient based on the downlink channel information. Then, the terminal device determines the index of the spatial basis vector, the index of the frequency basis vector, and the corresponding linear combination coefficient, and reports them to the network device as PMI. The network device determines the spatial-frequency component matrix (i.e., the double-domain compression basis) according to the spatial basis vector and the frequency basis vector selected by the terminal device, and then determines the channel matrix in combination with the corresponding linear combination coefficient. The network device can use the channel matrix to process and send downlink data.

[0004] From the above technical solution, it can be seen that the double-domain compression codebook is compressed in the spatial domain and the frequency domain respectively for the channel matrix. However, how to more efficiently compress and feed back the channel matrix is a problem to be solved in the application of MIMO technology. SUMMARY

[0005] The present application provides a channel state information feedback method and a communication device, which enable a network device to determine a spatial-frequency joint vector representing joint spatial-frequency domain compression, thereby realizing efficient compression and feedback of a channel matrix (also referred to as a precoding matrix) in the joint spatial-frequency domain by a terminal device.

[0006] The first aspect of the present application provides a channel state information feedback method, comprising:

[0007] The terminal device receives a precoded reference signal from the network device, and then determines CSI according to the precoded reference signal. The terminal device sends the CSI to the network device. The precoded reference signal is obtained by precoding a reference signal according to a spatial domain basis vector matrix, the spatial domain basis vector matrix includes at least one spatial domain basis vector, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port, and different spatial domain basis vectors in the spatial domain basis vector matrix are associated with different reference signal ports. The CSI includes first indication information and second indication information, the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients; the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients are used to determine N space-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0008] In the above technical solution, the terminal device feeds back the first indication information and the second indication information to the network device, the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients. Therefore, the network device can determine N space-frequency joint vectors representing joint space-frequency domain compression through the M space-frequency basis vectors and the M groups of first combination coefficients, so as to realize efficient joint space-frequency domain compression feedback of the channel matrix (also known as precoding matrix) by the terminal device.

[0009] In a possible implementation, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one group of first combination coefficients in the M groups of first combination coefficients is associated with one space-frequency basis vector in the M space-frequency basis vectors, and each space-frequency joint vector in the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0010] In this implementation, a specific implementation of the terminal device indicating the N space-frequency joint vectors is provided. Each space-frequency joint vector can be represented by linear combination of the M space-frequency basis vectors and the M groups of first combination coefficients, thereby reducing the overhead of the terminal device feeding back the N space-frequency joint vectors.

[0011] In another possible implementation, each group of first combination coefficients in the M groups of first combination coefficients includes N first combination coefficients, and one first combination coefficient in the N first combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0012] In this implementation, each group of first combination coefficients includes N first combination coefficients, thereby realizing indication of the N space-frequency joint vectors by the terminal device.

[0013] In another possible implementation manner, the CSI further includes third indication information, the third indication information being used for indicating N groups of second combination coefficients associated with the N spatial-frequency joint vectors, the N spatial-frequency joint vectors and the N groups of second combination coefficients being used for determining the precoding matrix.

[0014] In the implementation manner, the terminal device takes full advantage of the sparsity of the channel in the angle-delay domain (joint spatial domain and frequency domain) to realize linear combination representation of the channel by using N spatial-frequency joint vectors. Since the channel is more sparse in the joint spatial-frequency domain, the number of spatial-frequency joint vectors required for representing the channel is less than the number of spatial-frequency component matrices determined in the dual-domain compression scheme. Therefore, it is beneficial to reduce the overhead of the second combination coefficients reported by the terminal device for representing the channel. In other words, in the case of the same feedback overhead, the feedback accuracy of the PMI is improved. Further, the network device determines the precoding matrix by using the first indication information, the second indication information and the third indication information fed back by the terminal device, and processes and transmits the downlink data by using the precoding matrix, which is beneficial to improve the communication transmission performance.

[0015] In another possible implementation manner, the sending period of the first indication information and the second indication information is a first period, the sending period of the third indication information is a second period, and the length of the first period is greater than the length of the second period.

[0016] In the implementation manner, since the spatial-frequency joint vector can represent the statistical variation rule of the channel in the joint spatial-frequency domain and is a slowly-varying quantity, the first indication information and the second indication information can be reported in a longer period compared with other CSI reporting quantities, thereby reducing the overhead of the terminal device for feeding back the PMI. Since some channel characteristics of the channel are instantaneously changed, the terminal device can report the N groups of second combination coefficients in a short period. The above technical solution adopts a mode of feeding back the N spatial-frequency joint vectors in a long period and feeding back the N groups of second combination coefficients in a short period. From the overall scheme, compared with the dual-domain compression scheme, the terminal device has smaller overhead for feeding back the PMI, or in the case of the same feedback overhead, the feedback accuracy of the PMI in the technical solution is higher.

[0017] In another possible implementation manner, the length of the first period is 100 milliseconds (ms), 200 ms or 300 ms, and the length of the second period is 5 ms, 10 ms or 20 ms. As can be seen, the length of the first period is much greater than the length of the second period, thereby being beneficial to reduce the feedback overhead.

[0018] In another possible implementation, the network device configures the terminal device with the time length of the first period and the time length of the second period through a radio resource control (RRC) message, a media access control control element (MAC CE), or downlink control information (DCI).

[0019] In another possible implementation, one of the N groups of second combination coefficients is associated with one of the N spatial-frequency joint vectors.

[0020] In this implementation, a specific implementation of the terminal device indicating the precoding matrix is provided. The precoding matrix can be represented by linear combination of the N spatial-frequency joint vectors, which takes full advantage of the sparsity of the channel in the joint spatial-frequency domain, thereby reducing the overhead of the terminal device feeding back the PMI.

[0021] In another possible implementation, each of the N groups of second combination coefficients includes R or 2×R second combination coefficients; where R is equal to the number N r of receive antenna ports of the terminal device; or R is equal to the value N RANK of the rank corresponding to the precoding matrix. N RANK is an integer greater than or equal to 1 and less than or equal to N r .

[0022] In the above technical solution, each group of second combination coefficients includes N r or 2×N r second combination coefficients, thereby realizing the feedback of the terminal device to the channel information corresponding to each receive antenna port. Alternatively, each group of second combination coefficients includes N RANK or 2×N RANK second combination coefficients, thereby realizing the feedback of the terminal device to the precoding vector corresponding to each data stream.

[0023] In another possible implementation, the terminal device determines the CSI according to the precoding reference signal, including:

[0024] The terminal device determines the equivalent channel between the terminal device and the network device according to the precoding reference signal.

[0025] The terminal device determines N reference signal port-frequency domain joint vectors according to the equivalent channel; where the N reference signal port-frequency domain joint vectors are projections of the N spatial-frequency joint vectors on a spatial domain basis vector matrix, and N is an integer greater than or equal to 1.

[0026] The terminal device determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients from the P reference signal port-frequency domain basis vector pairs according to N reference signal port-frequency domain joint vectors, P is equal to the number N of frequency domain basis vectors fbasis multiplied by the number K of reference signal ports, N fbasis less than or equal to the number K of frequency domain units, K is less than or equal to the number of transmission antenna ports of the network device.

[0027] In this implementation, the specific implementation of the terminal device determining the CSI is shown, which is conducive to the implementation of the scheme. The terminal device obtains the equivalent channel through the precoding reference signal, and then determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients through the equivalent channel. Thus, the indication of the N spatial-frequency joint vectors is realized.

[0028] In another possible implementation, the terminal device determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients from the P reference signal port-frequency domain basis vector pairs according to N reference signal port-frequency domain joint vectors, including:

[0029] The terminal device projects the vector component corresponding to the reference signal port of each reference signal port-frequency domain joint vector in the N reference signal port-frequency domain joint vectors on the frequency domain basis vector matrix to obtain N first combination coefficient matrices, each first combination coefficient matrix in the N first combination coefficient matrices includes P first combination coefficients, one first combination coefficient in the P first combination coefficients is associated with one reference signal port-frequency domain basis vector pair in the P reference signal port-frequency domain basis vector pairs, and the frequency domain basis vector matrix includes N fbasis frequency domain basis vectors;

[0030] The terminal device determines the M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs according to the N first combination coefficient matrices.

[0031] The terminal device determines the first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs as the M sets of first combination coefficients.

[0032] In this implementation, the specific implementation process of the terminal device determining the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients is shown, which is conducive to the implementation of the scheme.

[0033] In another possible implementation, the method further includes:

[0034] The terminal device projects the equivalent channel on the N reference signal port-frequency domain joint vectors to obtain N sets of second combination coefficients, and the N spatial-frequency joint vectors and the N sets of second combination coefficients are used to determine the precoding matrix.

[0035] In the implementation, the terminal device can obtain the N groups of second combination coefficients through the equivalent channel, thereby realizing the indication of the precoding matrix. The precoding matrix is represented by linear combination of the N spatial-frequency joint vectors and the N groups of second combination coefficients, thereby reducing the overhead of the terminal device feedback PMI.

[0036] In another possible implementation, the spatial domain basis vector matrix is expressed as

[0037] wherein Q 11 is a first diagonal sub-block matrix, Q 22 is a second diagonal sub-block matrix, the first diagonal sub-block matrix corresponds to a first antenna panel of the network device in each polarization direction, the second diagonal sub-block matrix corresponds to a second antenna panel of the network device in each polarization direction, the dimension of the first diagonal sub-block matrix is determined according to the dimension of the transmission antenna port in each polarization direction of the first antenna panel, the dimension of the second diagonal sub-block matrix is determined according to the dimension of the transmission antenna port in each polarization direction of the second antenna panel, and the first antenna panel and the second antenna panel are not in the same plane.

[0038] The second aspect of the application provides a channel state information feedback method, comprising:

[0039] The network device performs precoding processing on the reference signal according to the spatial domain basis vector matrix to obtain a precoded reference signal, the spatial domain basis vector matrix includes at least one spatial domain basis vector, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port, and different spatial domain basis vectors in the spatial domain basis vector matrix are associated with different reference signal ports; the network device sends the precoded reference signal to the terminal device; and the network device receives the CSI sent by the terminal device; wherein the CSI is determined by the terminal device according to the received precoded reference signal; the CSI includes first indication information and second indication information; the first indication information is used for indicating M reference signal port-frequency domain basis vector pairs, and the second indication information is used for indicating M groups of first combination coefficients; the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients are used for determining N spatial-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0040] In the above technical solution, the network device receives the CSI sent by the terminal device. The CSI includes first indication information and second indication information; the first indication information is used for indicating M reference signal port-frequency domain basis vector pairs, and the second indication information is used for indicating M groups of first combination coefficients. The network device can determine N spatial-frequency joint vectors in combination with the M spatial-frequency basis vectors and the M groups of first combination coefficients. The terminal device can efficiently compress and feedback the channel matrix (also referred to as the precoding matrix) on the joint spatial-frequency domain.

[0041] In a possible implementation, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one of the M groups of first combination coefficients is associated with one of the M space-frequency basis vectors, and each of the N space-frequency joint vectors comprises a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0042] In this implementation, a specific implementation of the terminal device indicating the N space-frequency joint vectors is provided. Each space-frequency joint vector can be represented by a linear combination of the M space-frequency basis vectors and the M groups of first combination coefficients, thereby reducing the overhead of the terminal device feeding back the N space-frequency joint vectors.

[0043] In another possible implementation, each of the M groups of first combination coefficients comprises N first combination coefficients, and one of the N first combination coefficients is associated with one of the N space-frequency joint vectors.

[0044] In this implementation, each group of first combination coefficients comprises N first combination coefficients, thereby realizing the indication of the N space-frequency joint vectors by the terminal device.

[0045] In another possible implementation, the CSI further comprises third indication information, the third indication information being used to indicate N groups of second combination coefficients associated with the N space-frequency joint vectors, and the N space-frequency joint vectors and the N groups of second combination coefficients being used to determine a precoding matrix.

[0046] In this implementation, the terminal device takes full advantage of the sparsity of the channel in the angle-delay domain (joint space and frequency domain) to represent the channel by a linear combination of the N space-frequency joint vectors. Since the channel is more sparse in the joint space-frequency domain, the number of space-frequency joint vectors required to represent the channel is less than the number of space-frequency component matrices determined in the double-domain compression scheme. This is conducive to reducing the overhead of the second combination coefficients reported by the terminal device to represent the channel. In other words, in the case of the same feedback overhead, the feedback accuracy of the PMI is improved. The network device further receives the third indication information, and the N groups of second combination coefficients and the N space-frequency joint vectors are used to determine a precoding matrix to be fed back, and the downlink data is processed and transmitted through the precoding matrix, which is conducive to improving the communication transmission performance.

[0047] In another possible implementation, the sending period of the first indication information and the second indication information is a first period, the sending period of the third indication information is a second period, and the length of the first period is greater than the length of the second period.

[0048] In the implementation mode, since the space-frequency joint vector can represent the statistical variation rule of the channel in the joint space-frequency domain and is a slowly-varying quantity, the first indication information and the second indication information can be reported in a longer period compared with other CSI reporting quantities, thereby reducing the overhead of the terminal device feedback PMI. Since some channel characteristics of the channel are instantaneously changed, the terminal device can report the N groups of second combination coefficients in a short period. The above technical solution adopts a mode of long-period feedback of the N space-frequency joint vectors and short-period feedback of the N groups of second combination coefficients. Compared with the double-domain compression scheme, the overhead of the terminal device feedback PMI is smaller as a whole, or in other words, the feedback accuracy of the PMI in the technical solution of the present application is higher under the same feedback overhead.

[0049] In another possible implementation mode, the length of the first period is 100 milliseconds (ms), 200 ms, or 300 ms; and the length of the second period is 5 ms, 10 ms, or 20 ms. As can be seen, the length of the first period is much greater than the length of the second period, thereby facilitating reduction of the feedback overhead.

[0050] In another possible implementation mode, the network device configures the length of the first period and the length of the second period for the terminal device through an RRC message, a MAC CE, or DCI.

[0051] In another possible implementation mode, one group of second combination coefficients in the N groups of second combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0052] In the implementation mode, a specific implementation mode of the terminal device indicating the precoding matrix is provided. The precoding matrix is represented by linear combination of the N space-frequency joint vectors, and the sparsity of the channel in the joint space-frequency domain is fully utilized, thereby reducing the overhead of the terminal device feedback PMI.

[0053] In another possible implementation mode, each group of second combination coefficients in the N groups of second combination coefficients includes R or 2xR second combination coefficients; wherein R is equal to the number N r of receive antenna ports of the terminal device; or R is equal to the value N RANK of the rank corresponding to the precoding matrix.

[0054] In the above technical solution, each group of second combination coefficients includes N r or 2xN r second combination coefficients, thereby realizing feedback of the channel information corresponding to each receive antenna port by the terminal device. Or, each group of second combination coefficients includes N RANK or 2xN RANK second combination coefficients, thereby realizing feedback of the precoding vector corresponding to each data stream by the terminal device.

[0055] In a possible implementation form of the method, the method further includes:

[0056] The network device determines the precoding matrix according to the CSI and the spatial basis vector matrix.

[0057] In this implementation form, the network device can determine the precoding matrix according to the CSI and the spatial basis vector matrix, thereby facilitating improvement of communication transmission performance. For example, the network device can perform precoding processing on downlink transmission data through the precoding matrix, thereby improving communication transmission performance.

[0058] In a possible implementation form of the method, the network device determines the precoding matrix according to the CSI and the spatial basis vector matrix, including:

[0059] The network device determines, according to the first indication information, M reference signal port-frequency basis vector pairs;

[0060] The network device determines, according to the spatial basis vector matrix, a spatial basis vector associated with a reference signal port in the M reference signal port-frequency basis vector pairs;

[0061] The network device determines M spatial-frequency basis vectors through the frequency basis vector in the M reference signal port-frequency basis vector pairs and the spatial basis vector associated with the reference signal port in the M reference signal port-frequency basis vector pairs, each spatial-frequency basis vector in the M spatial-frequency basis vectors being associated with a spatial basis vector and a frequency basis vector;

[0062] The network device determines N spatial-frequency joint vectors according to the M groups of first combination coefficients and the M spatial-frequency basis vectors;

[0063] The network device determines the precoding matrix according to the N spatial-frequency joint vectors and N groups of second combination coefficients.

[0064] In this implementation form, a specific implementation process in which the network device determines the precoding matrix according to the CSI and the spatial basis vector matrix is shown, thereby facilitating implementation of the scheme.

[0065] In a possible implementation form of the method, the method further includes:

[0066] The network device determines the spatial basis vector matrix according to a dimension of a transmission antenna port of the network device and / or a form of the transmission antenna port, the dimension of the transmission antenna port being used to represent a number of transmission antenna ports of the network device in a horizontal direction and a number of transmission antenna ports of the network device in a vertical direction, and the form of the transmission antenna port being determined according to a form of a transmission antenna array surface of the network device.

[0067] In the implementation, the network device can select a spatial domain basis vector matrix that is adapted to the dimension and form of the transmission antenna ports of the network device according to the form of the transmission antenna ports of the network device. For example, the antenna panel is an irregular antenna panel, and the network device can realize matching of the spatial domain basis vector matrix and the form of the transmission antenna ports of the antenna panel through the implementation. Thus, the feedback performance of the channel state information of the terminal device is improved, and the feedback precision of the PMI is improved. The problem of loss of the feedback precision of the PMI caused by the mismatch between the spatial domain basis vector selected by the terminal device and the transmission antenna ports of the antenna panel on the network device side is avoided. The applicability and flexibility of the scheme are improved. For the terminal device, the processing complexity of the terminal device is reduced.

[0068] In another possible implementation, the spatial domain basis vector matrix is expressed as

[0069] wherein Q 11 is a first diagonal sub-block matrix, and Q 22 is a second diagonal sub-block matrix, the first diagonal sub-block matrix corresponds to a first antenna panel in each polarization direction of the network device, the second diagonal sub-block matrix corresponds to a second antenna panel in each polarization direction of the network device, the dimension of the first diagonal sub-block matrix is determined according to the dimension of the transmission antenna ports in each polarization direction of the first antenna panel, the dimension of the second diagonal sub-block matrix is determined according to the dimension of the transmission antenna ports in each polarization direction of the second antenna panel, and the first antenna panel and the second antenna panel are not in the same plane.

[0070] In the implementation, for the two antenna panels that are not in the same plane, a possible form of the spatial domain basis vector matrix is provided, and the diagonal sub-block matrix is used to represent the transmission antenna ports of the two antenna panels, so that the spatial domain basis vector matrix is matched with the form of the transmission antenna ports of the antenna panel.

[0071] The third aspect of the application provides a channel state information feedback method, comprising:

[0072] The terminal device receives a first precoding reference signal from the first network device; wherein the first precoding reference signal is obtained by performing precoding processing on a first reference signal according to a first spatial domain basis vector matrix, the first spatial domain basis vector matrix includes at least one first spatial domain basis vector, one first spatial domain basis vector in the first spatial domain basis vector matrix is associated with one reference signal port, and different first spatial domain basis vectors in the first spatial domain basis vector matrix are associated with different reference signal ports.

[0073] The terminal device receives a second precoded reference signal from the second network device; wherein the second precoded reference signal is obtained by precoding processing a second reference signal according to a second spatial domain basis vector matrix, the second spatial domain basis vector matrix comprising at least one second spatial domain basis vector, one second spatial domain basis vector in the second spatial domain basis vector matrix being associated with one reference signal port, different second spatial domain basis vectors in the second spatial domain basis vector matrix being associated with different reference signal ports;

[0074] The terminal device determines a first CSI according to the first precoded reference signal; wherein the first CSI comprises first indication information, second indication information and fifth indication information, the first indication information being used for indicating D1 first reference signal port-frequency domain basis vector pairs, the second indication information being used for indicating D1 groups of first combination coefficients; the D1 first reference signal port-frequency domain basis vector pairs and the D1 groups of first combination coefficients being used for determining E1 first space-frequency joint vectors, D1 and E1 both being integers greater than or equal to 1, the fifth indication information being used for indicating E1 groups of third combination coefficients associated with the E1 first space-frequency joint vectors;

[0075] The terminal device determines a second CSI according to the second precoded reference signal; wherein the second CSI comprises third indication information, fourth indication information and sixth indication information, the third indication information being used for indicating D2 second reference signal port-frequency domain basis vector pairs, the fourth indication information being used for indicating D2 groups of second combination coefficients; the D2 second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients being used for determining E2 second space-frequency joint vectors, D2 and E2 both being integers greater than or equal to 1; the sixth indication information being used for indicating E2 groups of fourth combination coefficients associated with the E2 second space-frequency joint vectors; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients being used for indicating multi-site inter-relative information between the first network device and the second network device; the E1 first space-frequency joint vectors, the multi-site inter-relative information and the E1 groups of third combination coefficients being used for determining a first precoding matrix corresponding to the first network device; the E2 second space-frequency joint vectors, the multi-site inter-relative information and the E2 groups of fourth combination coefficients being used for determining a second precoding matrix corresponding to the second network device;

[0076] The terminal device sends the first CSI and the second CSI to the first network device.

[0077] In the technical solution, in a multi-site cooperation scenario, the terminal device can receive a first precoded reference signal from a first network device (one of the sites) and a second precoded reference signal from a second network device (another site). Then, the terminal device determines a first CSI based on the first precoded reference signal and a second CSI based on the second precoded matrix, and reports the information to the first network device, so as to realize compression feedback of the channel matrix (precoding matrix) in the joint space-frequency domain by the terminal device. Thus, the first network device and / or the second network device can determine the corresponding precoding matrix, and the multi-site cooperation transmission can be realized.

[0078] In a possible implementation, the method further includes:

[0079] The terminal device receives a third precoded reference signal from a third network device; the third precoded reference signal is obtained by precoding processing of a third reference signal according to a third spatial domain basis vector matrix, the third spatial domain basis vector matrix includes at least one third spatial domain basis vector, one third spatial domain basis vector in the third spatial domain basis vector matrix is associated with one reference signal port, and different third spatial domain basis vectors in the third spatial domain basis vector matrix are associated with different reference signal ports.

[0080] The terminal device determines a third CSI according to the third precoded reference signal; the third CSI includes eighth indication information, ninth indication information, and tenth indication information. The eighth indication information is used to indicate D3 third reference signal port-frequency domain basis vector pairs, the ninth indication information is used to indicate D3 groups of fifth combination coefficients; the D3 third reference signal port-frequency domain basis vector pairs and the D3 groups of fifth combination coefficients are used to determine E3 third space-frequency joint vectors, D3 and E3 are integers greater than or equal to 1; the tenth indication information is used to indicate E3 groups of sixth combination coefficients associated with the E3 third space-frequency joint vectors; the E1 group of third combination coefficients, the E2 group of fourth combination coefficients, and the E3 group of sixth combination coefficients are used to indicate multi-site inter-site relative information between the first network device, the second network device, and the third network device; the multi-site inter-site relative information is determined with the first network device as a reference site.

[0081] The terminal device sends the third CSI to the first network device.

[0082] In this implementation, when the multi-site includes three network devices, the terminal device reports the CSI corresponding to the three network devices to the first network device. Thus, the first network device can determine the precoding matrix corresponding to each network device, or the CSI corresponding to each network device is reported.

[0083] The fourth aspect of the present application provides a channel state information feedback method, including:

[0084] The first network device performs precoding processing on the first reference signals according to a first spatial domain basis vector matrix to obtain first precoded reference signals, the first spatial domain basis vector matrix including at least one first spatial domain basis vector, one first spatial domain basis vector in the first spatial domain basis vector matrix being associated with one reference signal port, different first spatial domain basis vectors in the first spatial domain basis vector matrix being associated with different reference signal ports;

[0085] The first network device sends the first precoded reference signals to the terminal device;

[0086] The first network device receives the first CSI and the second CSI from the terminal device;

[0087] The first CSI includes first indication information, second indication information, and fifth indication information, the first indication information being used to indicate D1 first reference signal port-frequency domain basis vector pairs, the second indication information being used to indicate D1 groups of first combination coefficients; the D1 first reference signal port-frequency domain basis vector pairs and the D1 groups of first combination coefficients are used to determine E1 first space-frequency joint vectors, D1 and E1 are both integers greater than or equal to 1, and the fifth indication information is used to indicate E1 groups of third combination coefficients associated with the E1 first space-frequency joint vectors;

[0088] The second CSI includes third indication information, fourth indication information, and sixth indication information, the third indication information being used to indicate D2 second reference signal port-frequency domain basis vector pairs, the fourth indication information being used to indicate D2 groups of second combination coefficients; the D2 second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used to determine E2 second space-frequency joint vectors, D2 and E2 are both integers greater than or equal to 1; the sixth indication information is used to indicate E2 groups of fourth combination coefficients associated with the E2 second space-frequency joint vectors; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients are used to indicate multi-site inter-relative information between the first network device and the second network device; the E1 first space-frequency joint vectors, the multi-site inter-relative information, and the E1 groups of third combination coefficients are used to determine a first precoding matrix corresponding to the first network device; the E2 second space-frequency joint vectors, the multi-site inter-relative information, and the E2 groups of fourth combination coefficients are used to determine a second precoding matrix corresponding to the second network device.

[0089] In the above technical solution, in a multi-site cooperation scenario, the first network device receives the first CSI and the second CSI from the terminal device. The terminal device jointly compresses and feeds back a channel matrix (a precoding matrix) in a space-frequency domain. Thus, the first network device and / or the second network device can determine corresponding space-frequency joint vectors, and multiple network devices can perform multi-site cooperation transmission.

[0090] In a possible implementation manner, the method further includes:

[0091] The first network device determines a first precoding matrix corresponding to the first network device according to the first CSI, the second CSI and the first spatial domain basis vector matrix.

[0092] In this implementation, the first network device can determine the first precoding matrix corresponding to the first network device in combination of the first CSI, the second CSI and the first spatial domain basis vector matrix. The first network device can perform downlink transmission based on the first precoding matrix, thereby facilitating improvement of communication transmission performance.

[0093] In another possible implementation, the method further includes:

[0094] The first network device sends the first CSI and the second CSI to the second network device.

[0095] In this implementation, the first network device can send the first CSI and the second CSI to the second network device. This facilitates the second network device to determine a second precoding matrix corresponding to the second network device. The second network device performs downlink transmission based on the second precoding matrix, thereby facilitating improvement of communication transmission performance.

[0096] In another possible implementation, the method further includes:

[0097] The first network device determines a second precoding matrix corresponding to the second network device according to the first CSI, the second CSI and the second spatial domain basis vector matrix.

[0098] The first network device sends seventh indication information to the second network device, where the seventh indication information is used to indicate the second precoding matrix.

[0099] In this implementation, the first network device can determine the second precoding matrix corresponding to the second network device based on the first CSI, the second CSI and the second spatial domain basis vector matrix, and indicate the second precoding matrix to the second network device. This facilitates the second network device to perform downlink transmission based on the second precoding matrix, thereby facilitating improvement of communication transmission performance.

[0100] In another possible implementation, the method further includes:

[0101] The first network device receives third CSI from the terminal device; the third CSI comprises eighth indication information, ninth indication information and tenth indication information; the eighth indication information is used to indicate D3 third reference signal port-frequency domain basis vector pairs; the ninth indication information is used to indicate D3 groups of fifth combination coefficients; the D3 third reference signal port-frequency domain basis vector pairs and the D3 groups of fifth combination coefficients are used to determine E3 third space-frequency joint vectors; D3 and E3 are integers greater than or equal to 1; the tenth indication information is used to indicate E3 groups of sixth combination coefficients associated with the E3 third space-frequency joint vectors; the E1 group of third combination coefficients, the E2 group of fourth combination coefficients and the E3 group of sixth combination coefficients are used to indicate multi-site relative information between the first network device, the second network device and the third network device together; the multi-site relative information is determined with the first network device as a reference site;

[0102] The first network device determines the first precoding matrix corresponding to the first network device according to the first CSI, the second CSI and the first spatial domain basis vector matrix, comprising:

[0103] The first network device determines the first precoding matrix corresponding to the first network device according to the first CSI, the second CSI, the third CSI and the first spatial domain basis vector matrix.

[0104] In this implementation mode, the first network device determines the first precoding matrix corresponding to the first network device according to the first CSI, the second CSI, the third CSI and the first spatial domain basis vector matrix. The first network device can perform downlink transmission based on the first precoding matrix, thereby facilitating the improvement of communication transmission performance.

[0105] In another possible implementation mode, the method further comprises:

[0106] The first network device sends the first CSI, the second CSI and the third CSI to the second network device and the third network device respectively.

[0107] In this implementation mode, the first network device can send the first CSI, the second CSI and the third CSI to the second network device and the third network device. Thereby, the second network device can determine the second precoding matrix corresponding to the second network device. The second network device performs downlink transmission based on the second precoding matrix. The third network device can determine the third precoding matrix corresponding to the third network device. The third network device performs downlink transmission based on the third precoding matrix, thereby improving the communication transmission performance.

[0108] In another possible implementation mode, the method further comprises:

[0109] The first network device determines the second precoding matrix corresponding to the second network device according to the first CSI, the second CSI, the third CSI and the second spatial domain basis vector matrix.

[0110] The first network device determines a third precoding matrix corresponding to the third network device according to the first CSI, the second CSI, the third CSI and a third spatial domain basis vector matrix;

[0111] The first network device sends eleventh indication information to the second network device, and the eleventh indication information is used to indicate the second precoding matrix;

[0112] The first network device sends twelfth indication information to the third network device, and the twelfth indication information is used to indicate the third precoding matrix.

[0113] In this implementation, the first network device determines a second precoding matrix corresponding to the second network device according to the first CSI, the second CSI, the third CSI and a second spatial domain basis vector matrix, and indicates the second precoding matrix to the second network device. The first network device determines a third precoding matrix corresponding to the third network device according to the first CSI, the second CSI, the third CSI and a third spatial domain basis vector matrix, and indicates the third precoding matrix to the third network device. Therefore, the communication transmission performance is improved.

[0114] The fifth aspect of the present application provides a channel state information feedback method, comprising:

[0115] The second network device performs precoding processing on the second reference signal according to a second spatial domain basis vector matrix to obtain a second precoded reference signal, the second spatial domain basis vector matrix includes at least one second spatial domain basis vector, one second spatial domain basis vector in the second spatial domain basis vector matrix is associated with one reference signal port, and different second spatial domain basis vectors in the second spatial domain basis vector matrix are associated with different reference signal ports;

[0116] The second network device sends the second precoded reference signal to the terminal device;

[0117] The second network device receives the first CSI and the second CSI from the first network device, or the second network device receives the seventh indication information from the first network device;

[0118] The first CSI includes fifth indication information, and the fifth indication information is used to indicate E1 groups of third combination coefficients, E1 being an integer greater than or equal to 1; the second CSI includes third indication information, fourth indication information and sixth indication information, the third indication information is used to indicate D2 groups of second reference signal port-frequency domain basis vector pairs, the fourth indication information is used to indicate D2 groups of second combination coefficients; the D2 groups of second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used to determine E2 groups of second space-frequency joint vectors; the sixth indication information is used to indicate E2 groups of fourth combination coefficients associated with the E2 groups of second space-frequency joint vectors, D2 and E2 both being integers greater than or equal to 1; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients are used to indicate multi-site inter-relative information between the first network device and the second network device; the E2 groups of second space-frequency joint vectors, the multi-site inter-relative information and the E2 groups of fourth combination coefficients are used to determine a second precoding matrix corresponding to the second network device, and the seventh indication information is used to indicate the second precoding matrix corresponding to the second network device.

[0119] In the technical solution, the second network device receives the first CSI and the second CSI from the first network device, which facilitates the second network device to determine the E2 groups of second space-frequency joint vectors. Alternatively, the second network device receives the seventh indication information from the first network device and determines the second precoding matrix, thereby facilitating the second network device to perform downlink transmission based on the second precoding matrix and improving communication performance.

[0120] In a possible implementation manner, the method further includes:

[0121] The second network device determines the second precoding matrix corresponding to the second network device according to the first CSI, the second CSI and the second spatial domain basis vector matrix.

[0122] In this implementation manner, the second network device can determine the second precoding matrix corresponding to the second network device in combination with the first CSI, the second CSI and the second spatial domain basis vector matrix. The second network device can perform downlink transmission based on the second precoding matrix, thereby facilitating improvement of communication transmission performance.

[0123] In another possible implementation manner, the method further includes:

[0124] The second network device receives third CSI from the first network device, and the third CSI includes tenth indication information. The tenth indication information is used to indicate E3 groups of sixth combination coefficients associated with E3 groups of third space-frequency joint vectors; the E1 groups of third combination coefficients, the E2 groups of fourth combination coefficients and the E3 groups of sixth combination coefficients are used to indicate multi-site inter-relative information between the first network device, the second network device and a third network device; the multi-site inter-relative information is determined with the first network device as a reference site.

[0125] The second network device determines a second precoding matrix corresponding to the second network device according to the first CSI, the second CSI, and the second spatial-domain basis vector matrix, including:

[0126] The second network device determines a second precoding matrix corresponding to the second network device according to the first CSI, the second CSI, the third CSI, and the second spatial-domain basis vector matrix.

[0127] In this implementation, for the case that the multiple sites include the first network device, the second network device, and the third network device, the second network device receives the CSI corresponding to each network device fed back by the first network device, and determines a second precoding matrix corresponding to the second network device in combination with the CSI corresponding to each network device and the second spatial-domain basis vector matrix. The second network device can perform downlink transmission based on the second precoding matrix, thereby facilitating improvement of communication transmission performance.

[0128] The sixth aspect of the present application provides a communication device, including:

[0129] The transceiver module is configured to receive a precoding reference signal from a network device.

[0130] The processing module is configured to determine a CSI according to the precoding reference signal.

[0131] The transceiver module is configured to send the CSI to the network device.

[0132] The precoding reference signal is obtained by precoding processing a reference signal according to a spatial-domain basis vector matrix, the spatial-domain basis vector matrix includes at least one spatial-domain basis vector, one spatial-domain basis vector in the spatial-domain basis vector matrix is associated with one reference signal port, and different spatial-domain basis vectors in the spatial-domain basis vector matrix are associated with different reference signal ports; the CSI includes first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients; the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients are used to determine N space-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0133] In a possible implementation, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one group of first combination coefficients in the M groups of first combination coefficients is associated with one space-frequency basis vector in the M space-frequency basis vectors, and each space-frequency joint vector in the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0134] In another possible implementation manner, each of the M groups of first combination coefficients includes N first combination coefficients, and one of the N first combination coefficients is associated with one of the N spatial-frequency joint vectors.

[0135] In another possible implementation manner, the CSI further includes third indication information, the third indication information being used to indicate N groups of second combination coefficients associated with the N spatial-frequency joint vectors, the N spatial-frequency joint vectors and the N groups of second combination coefficients being used to determine the precoding matrix.

[0136] In another possible implementation manner, a sending period of the first indication information and the second indication information is a first period, and a sending period of the third indication information is a second period, a time length of the first period being greater than a time length of the second period.

[0137] In another possible implementation manner, the time length of the first period is 100 milliseconds (ms), 200 ms or 300 ms, and the time length of the second period is 5 ms, 10 ms or 20 ms. In this way, the time length of the first period is much greater than the time length of the second period, thereby facilitating reduction of feedback overhead.

[0138] In another possible implementation manner, the network device configures the time length of the first period and the time length of the second period for the communication apparatus through a radio resource control (RRC) message, a medium access control (MAC) control element (CE) or a downlink control information (DCI).

[0139] In another possible implementation manner, one of the N groups of second combination coefficients is associated with one of the N spatial-frequency joint vectors.

[0140] In another possible implementation manner, each of the N groups of second combination coefficients includes R or 2×R second combination coefficients, where R is equal to a number N of receive antenna ports of the communication apparatus, or R is equal to a value N of a rank corresponding to the precoding matrix. r RANK .

[0141] In another possible implementation manner, the processing module is specifically configured to:

[0142] determine an equivalent channel between the communication apparatus and the network device according to the precoding reference signal;

[0143] determine N reference signal port-frequency domain joint vectors according to the equivalent channel, where the N reference signal port-frequency domain joint vectors are projections of the N spatial-frequency joint vectors on a spatial domain basis vector matrix, and N is an integer greater than or equal to 1;

[0144] ​determining M reference signal port-frequency basis vector pairs and M sets of first combination coefficients from P reference signal port-frequency basis vector pairs according to N reference signal port-frequency joint vectors, P is equal to the number N of frequency basis vectors fbasis multiplied by the number K of reference signal ports, N fbasis less than or equal to the number K of frequency domain units, K is less than or equal to the number of transmit antenna ports of the network device.

[0145] In another possible implementation, the processing module is specifically configured to:

[0146] projecting vector components corresponding to reference signal ports of each reference signal port-frequency joint vector in the N reference signal port-frequency joint vectors on a frequency basis vector matrix to obtain N first combination coefficient matrices, each first combination coefficient matrix in the N first combination coefficient matrices includes P first combination coefficients, one first combination coefficient in the P first combination coefficients is associated with one reference signal port-frequency basis vector pair in the P reference signal port-frequency basis vector pairs, and the frequency basis vector matrix includes N fbasis frequency basis vectors;

[0147] determining M reference signal port-frequency basis vector pairs from P reference signal port-frequency basis vector pairs according to N first combination coefficient matrices;

[0148] determining the first combination coefficients associated with the M reference signal port-frequency basis vector pairs as M sets of first combination coefficients.

[0149] In another possible implementation, the processing module is further configured to:

[0150] projecting the equivalent channel on the N reference signal port-frequency joint vectors to obtain N sets of second combination coefficients, and the N spatial-frequency joint vectors and the N sets of second combination coefficients are used to determine the precoding matrix.

[0151] In another possible implementation, the spatial basis vector matrix is expressed as

[0152] wherein Q 11 is a first diagonal sub-block matrix, Q 22 is a second diagonal sub-block matrix, the first diagonal sub-block matrix corresponds to a first antenna panel in each polarization direction of the network device, the second diagonal sub-block matrix corresponds to a second antenna panel in each polarization direction of the network device, the dimension of the first diagonal sub-block matrix is determined according to the dimension of the transmit antenna port in each polarization direction of the first antenna panel, the dimension of the second diagonal sub-block matrix is determined according to the dimension of the transmit antenna port in each polarization direction of the second antenna panel, and the first antenna panel and the second antenna panel are not in the same plane.

[0153] The seventh aspect of the present application provides a communication device, comprising:

[0154] a processing module configured to perform precoding processing on the reference signals according to the spatial domain basis vector matrix to obtain precoded reference signals, the spatial domain basis vector matrix comprising at least one spatial domain basis vector, one spatial domain basis vector in the spatial domain basis vector matrix being associated with one reference signal port, and different spatial domain basis vectors in the spatial domain basis vector matrix being associated with different reference signal ports;

[0155] a transceiver configured to send the precoded reference signals to the terminal device and receive CSI sent by the terminal device;

[0156] The CSI is determined by the terminal device according to the received precoded reference signals; the CSI comprises first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients, the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients being used to determine N space-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0157] In a possible implementation, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one group of first combination coefficients in the M groups of first combination coefficients is associated with one space-frequency basis vector in the M space-frequency basis vectors, and each space-frequency joint vector in the N space-frequency joint vectors comprises a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0158] In another possible implementation, each group of first combination coefficients in the M groups of first combination coefficients comprises N first combination coefficients, and one first combination coefficient in the N first combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0159] In another possible implementation, the CSI further comprises third indication information, the third indication information being used to indicate N groups of second combination coefficients associated with the N space-frequency joint vectors, the N space-frequency joint vectors and the N groups of second combination coefficients being used to determine a precoding matrix.

[0160] In another possible implementation, a sending period of the first indication information and the second indication information is a first period, and a sending period of the third indication information is a second period, a length of the first period being greater than a length of the second period.

[0161] In another possible implementation, the length of the first period is 100 milliseconds (ms), 200 ms, or 300 ms, and the length of the second period is 5 ms, 10 ms, or 20 ms.

[0162] In another possible implementation, the communication device configures the duration of the first cycle and the duration of the second cycle for the terminal device via RRC messages, MAC CE, or DCI.

[0163] In another possible implementation, one set of second combination coefficients from the N sets of second combination coefficients is associated with one of the N space-frequency joint vectors.

[0164] In another possible implementation, each of the N sets of second combination coefficients contains R or 2×R second combination coefficients; where R is equal to the number of receiving antenna ports N of the terminal device. r Alternatively, R is equal to the value N of the rank corresponding to the precoding matrix. RANK .

[0165] In another possible implementation, the processing module is also used for:

[0166] The precoding matrix is ​​determined based on the CSI and the spatial basis vector matrix.

[0167] In another possible implementation, the processing module is specifically used for:

[0168] Based on the first indication information, determine M reference signal port-frequency domain basis vector pairs;

[0169] The spatial basis vectors associated with the reference signal ports in the M reference signal port-frequency domain basis vector pairs are determined based on the spatial basis vector matrix.

[0170] M space-frequency basis vectors are determined by the frequency domain basis vectors in the M reference signal port-frequency domain basis vector pairs and the spatial basis vectors associated with the reference signal ports in the M reference signal port-frequency domain basis vector pairs. Each of the M space-frequency basis vectors is associated with a spatial basis vector and a frequency domain basis vector.

[0171] N space-frequency joint vectors are determined based on the first combination coefficients of the M groups and the M space-frequency basis vectors;

[0172] The precoding matrix is ​​determined based on N joint space-frequency vectors and N sets of second combination coefficients.

[0173] In another possible implementation, the processing module is also used for:

[0174] The spatial basis vector matrix is ​​determined based on the dimension and / or shape of the transmitting antenna ports of the communication device. The dimension of the transmitting antenna ports is used to characterize the number of transmitting antenna ports in the horizontal direction and the number of transmitting antenna ports in the vertical direction of the network device, respectively. The shape of the transmitting antenna ports is determined based on the shape of the transmitting antenna array of the communication device.

[0175] In another possible implementation, the spatial domain basis vector matrix is expressed as

[0176] wherein Q 11 is a first diagonal sub-block matrix, Q 22 is a second diagonal sub-block matrix, the first diagonal sub-block matrix corresponds to a first antenna panel of the communication device in each polarization direction, the second diagonal sub-block matrix corresponds to a second antenna panel of the communication device in each polarization direction, the dimension of the first diagonal sub-block matrix is determined according to the dimension of a transmit antenna port in each polarization direction of the first antenna panel, the dimension of the second diagonal sub-block matrix is determined according to the dimension of a transmit antenna port in each polarization direction of the second antenna panel, and the first antenna panel and the second antenna panel are not in the same plane.

[0177] An eighth aspect of the present application provides a communication device, comprising:

[0178] a transceiver configured to receive a first precoded reference signal from a first network device, wherein the first precoded reference signal is obtained by precoding processing a first reference signal according to a first spatial domain basis vector matrix, the first spatial domain basis vector matrix comprises at least one first spatial domain basis vector, one first spatial domain basis vector in the first spatial domain basis vector matrix is associated with one reference signal port, and different first spatial domain basis vectors in the first spatial domain basis vector matrix are associated with different reference signal ports; and receive a second precoded reference signal from a second network device, wherein the second precoded reference signal is obtained by precoding processing a second reference signal according to a second spatial domain basis vector matrix, the second spatial domain basis vector matrix comprises at least one second spatial domain basis vector, one second spatial domain basis vector in the second spatial domain basis vector matrix is associated with one reference signal port, and different second spatial domain basis vectors in the second spatial domain basis vector matrix are associated with different reference signal ports.

[0179] The processing module is configured to determine first CSI according to the first precoding reference signal; wherein the first CSI comprises first indication information, second indication information and fifth indication information, the first indication information is used to indicate D1 first reference signal port-frequency domain basis vector pairs, the second indication information is used to indicate D1 groups of first combination coefficients; the D1 first reference signal port-frequency domain basis vector pairs and the D1 groups of first combination coefficients are used to determine E1 first space-frequency joint vectors, D1 and E1 are integers greater than or equal to 1, and the fifth indication information is used to indicate E1 groups of third combination coefficients associated with the E1 first space-frequency joint vectors; determine second CSI according to the second precoding reference signal; wherein the second CSI comprises third indication information, fourth indication information and sixth indication information, the third indication information is used to indicate D2 second reference signal port-frequency domain basis vector pairs, the fourth indication information is used to indicate D2 groups of second combination coefficients; the D2 second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used to determine E2 second space-frequency joint vectors, D2 and E2 are integers greater than or equal to 1; and the sixth indication information is used to indicate E2 groups of fourth combination coefficients associated with the E2 second space-frequency joint vectors; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients are used to indicate multi-site inter-relative information between the first network device and the second network device; the E1 first space-frequency joint vectors, the multi-site inter-relative information and the E1 groups of third combination coefficients are used to determine a first precoding matrix corresponding to the first network device; and the E2 second space-frequency joint vectors, the multi-site inter-relative information and the E2 groups of fourth combination coefficients are used to determine a second precoding matrix corresponding to the second network device.

[0180] The transceiver module is further configured to send the first CSI and the second CSI to the first network device.

[0181] In a possible implementation manner, the transceiver module is further configured to:

[0182] receive third precoding reference signals from a third network device; wherein the third precoding reference signals are obtained by precoding processing of third reference signals according to a third spatial domain basis vector matrix, the third spatial domain basis vector matrix comprises at least one third spatial domain basis vector, one third spatial domain basis vector in the third spatial domain basis vector matrix is associated with one reference signal port, and different third spatial domain basis vectors in the third spatial domain basis vector matrix are associated with different reference signal ports.

[0183] The processing module is further configured to:

[0184] determining third CSI according to the third precoding reference signal; wherein the third CSI comprises eighth indication information, ninth indication information and tenth indication information; the eighth indication information is used for indicating D3 third reference signal port-frequency domain basis vector pairs; the ninth indication information is used for indicating D3 groups of fifth combination coefficients; the D3 third reference signal port-frequency domain basis vector pairs and the D3 groups of fifth combination coefficients are used for determining E3 third space-frequency joint vectors; D3 and E3 are both integers greater than or equal to 1; the tenth indication information is used for indicating E3 groups of sixth combination coefficients associated with the E3 third space-frequency joint vectors; the E1 group of third combination coefficients, the E2 group of fourth combination coefficients and the E3 group of sixth combination coefficients are used for indicating multi-site inter-relative information between the first network device, the second network device and the third network device together; the multi-site inter-relative information is determined with the first network device as a reference site;

[0185] The transceiver module is further configured to:

[0186] send the third CSI to the first network device.

[0187] The ninth aspect of the present application provides a communication device, comprising:

[0188] a processing module configured to perform precoding processing on a first reference signal according to a first spatial domain basis vector matrix to obtain a first precoding reference signal; the first spatial domain basis vector matrix comprises at least one first spatial domain basis vector; one first spatial domain basis vector in the first spatial domain basis vector matrix is associated with one reference signal port; different first spatial domain basis vectors in the first spatial domain basis vector matrix are associated with different reference signal ports;

[0189] a transceiver module configured to send the first precoding reference signal to a terminal device; and receive first CSI and second CSI from the terminal device;

[0190] The first CSI comprises first indication information, second indication information and fifth indication information; the first indication information is used for indicating D1 first reference signal port-frequency domain basis vector pairs; the second indication information is used for indicating D1 groups of first combination coefficients; the D1 first reference signal port-frequency domain basis vector pairs and the D1 groups of first combination coefficients are used for determining E1 first space-frequency joint vectors; D1 and E1 are both integers greater than or equal to 1; the fifth indication information is used for indicating E1 groups of third combination coefficients associated with the E1 first space-frequency joint vectors;

[0191] The second CSI includes third indication information, fourth indication information and sixth indication information, the third indication information is used for indicating D2 second reference signal port-frequency domain basis vector pairs, the fourth indication information is used for indicating D2 groups of second combination coefficients; the D2 second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used for determining E2 second space-frequency joint vectors, and D2 and E2 are integers greater than or equal to 1; the sixth indication information is used for indicating E2 groups of fourth combination coefficients associated with the E2 second space-frequency joint vectors; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients are used for indicating multi-site inter-relative information between the communication device and the second network device; the E1 first space-frequency joint vectors, the multi-site inter-relative information and the E1 groups of third combination coefficients are used for determining a first precoding matrix corresponding to the communication device; and the E2 second space-frequency joint vectors, the multi-site inter-relative information and the E2 groups of fourth combination coefficients are used for determining a second precoding matrix corresponding to the second network device.

[0192] In a possible implementation, the processing module is further configured to:

[0193] determine the first precoding matrix corresponding to the communication device according to the first CSI, the second CSI and the first spatial domain basis vector matrix.

[0194] In another possible implementation, the transceiver module is further configured to:

[0195] send the first CSI and the second CSI to the second network device.

[0196] In another possible implementation, the processing module is further configured to:

[0197] determine the second precoding matrix corresponding to the second network device according to the first CSI, the second CSI and the second spatial domain basis vector matrix.

[0198] The transceiver module is further configured to:

[0199] send seventh indication information to the second network device, the seventh indication information being used for indicating the second precoding matrix.

[0200] In another possible implementation, the transceiver module is further configured to:

[0201] receive third CSI from the terminal device; wherein the third CSI comprises eighth indication information, ninth indication information and tenth indication information; the eighth indication information is used to indicate D3 third reference signal port-frequency domain basis vector pairs; the ninth indication information is used to indicate D3 groups of fifth combination coefficients; the D3 third reference signal port-frequency domain basis vector pairs and the D3 groups of fifth combination coefficients are used to determine E3 third space-frequency joint vectors; D3 and E3 are both integers greater than or equal to 1; the tenth indication information is used to indicate E3 groups of sixth combination coefficients associated with the E3 third space-frequency joint vectors; the E1 group of third combination coefficients, the E2 group of fourth combination coefficients and the E3 group of sixth combination coefficients are used to indicate multi-site relative information between the communication device, the second network device and the third network device together; the multi-site relative information is determined with the communication device as a reference site;

[0202] The processing module is specifically configured to:

[0203] determine a first precoding matrix corresponding to the communication device according to the first CSI, the second CSI, the third CSI and the first spatial domain basis vector matrix.

[0204] In another possible implementation, the transceiver module is further configured to:

[0205] send the first CSI, the second CSI and the third CSI to the second network device and the third network device respectively.

[0206] In another possible implementation, the processing module is further configured to:

[0207] determine a second precoding matrix corresponding to the second network device according to the first CSI, the second CSI, the third CSI and the second spatial domain basis vector matrix;

[0208] determine a third precoding matrix corresponding to the third network device according to the first CSI, the second CSI, the third CSI and the third spatial domain basis vector matrix;

[0209] The transceiver module is further configured to:

[0210] send eleventh indication information to the second network device, the eleventh indication information being used to indicate the second precoding matrix;

[0211] send twelfth indication information to the third network device, the twelfth indication information being used to indicate the third precoding matrix.

[0212] The tenth aspect of the present application provides a communication device, comprising:

[0213] The processing module is configured to perform precoding processing on the second reference signals according to a second spatial domain basis vector matrix to obtain second precoded reference signals, the second spatial domain basis vector matrix comprising at least one second spatial domain basis vector, one second spatial domain basis vector in the second spatial domain basis vector matrix being associated with one reference signal port, and different second spatial domain basis vectors in the second spatial domain basis vector matrix being associated with different reference signal ports.

[0214] The transceiver module is configured to send the second precoded reference signals to the terminal device, receive the first CSI and the second CSI from the first network device, or receive the seventh indication information from the first network device.

[0215] The first CSI comprises fifth indication information, the fifth indication information being used to indicate E1 groups of third combination coefficients, E1 being an integer greater than or equal to 1; the second CSI comprises third indication information, fourth indication information and sixth indication information, the third indication information being used to indicate D2 groups of second reference signal port-frequency domain basis vector pairs, the fourth indication information being used to indicate D2 groups of second combination coefficients; the D2 groups of second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used to determine E2 groups of second space-frequency joint vectors; the sixth indication information is used to indicate E2 groups of fourth combination coefficients associated with the E2 groups of second space-frequency joint vectors, D2 and E2 both being integers greater than or equal to 1; the E1 groups of third combination coefficients and the E2 groups of fourth combination coefficients are used to indicate multi-site inter-relative information between the first network device and the communication apparatus; the E2 groups of second space-frequency joint vectors, the multi-site inter-relative information and the E2 groups of fourth combination coefficients are used to determine a second precoding matrix corresponding to the communication apparatus, and the seventh indication information is used to indicate the second precoding matrix corresponding to the communication apparatus.

[0216] In a possible implementation manner, the processing module is further configured to:

[0217] determine the second precoding matrix corresponding to the communication apparatus according to the first CSI, the second CSI and the second spatial domain basis vector matrix.

[0218] In another possible implementation manner, the transceiver module is further configured to:

[0219] receive third CSI from the first network device, wherein the third CSI comprises tenth indication information, the tenth indication information being used to indicate E3 groups of sixth combination coefficients associated with E3 groups of third space-frequency joint vectors; the E1 groups of third combination coefficients, the E2 groups of fourth combination coefficients and the E3 groups of sixth combination coefficients are used to indicate multi-site inter-relative information between the first network device, the communication apparatus and a third network device, the multi-site inter-relative information being determined with the first network device as a reference site.

[0220] The processing module is specifically configured to:

[0221] The communication device determines a second precoding matrix corresponding to the communication device according to the first CSI, the second CSI, the third CSI, and the second spatial domain basis vector matrix.

[0222] The eleventh aspect of the present application provides a communication device, the communication device comprising a processor. The processor is configured to invoke and run a computer program stored in a memory, so that the processor implements any one of the implementation manners in any one of the first aspect to the fifth aspect.

[0223] Optionally, the communication device further comprises a transceiver, and the processor is further configured to control the transceiver to transceive signals.

[0224] Optionally, the communication device comprises a memory, and the memory stores the computer program.

[0225] The twelfth aspect of the present application provides a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out any one of the implementation manners in any one of the first aspect to the fifth aspect.

[0226] The thirteenth aspect of the present application provides a computer-readable storage medium comprising computer instructions which, when executed by a computer, cause the computer to carry out any one of the implementation manners in any one of the first aspect to the fifth aspect.

[0227] The fourteenth aspect of the present application provides a chip device comprising a processor configured to be connected to a memory, invoke a program stored in the memory, and cause the processor to carry out any one of the implementation manners in any one of the first aspect to the fifth aspect.

[0228] The fifteenth aspect of the present application provides a communication system, the communication system comprising the communication device of the sixth aspect and the communication device of the seventh aspect.

[0229] The sixteenth aspect of the present application provides a communication system, the communication system comprising the communication device of the eighth aspect, the communication device of the ninth aspect, and the communication device of the tenth aspect.

[0230] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0231] As described in the above technical solution, the terminal device receives a precoded reference signal from the network device; then, the terminal device determines the Channel Identity (CSI) based on the precoded reference signal and sends the CSI to the network device. The CSI includes first indication information and second indication information. The first indication information indicates M reference signal port-frequency domain basis vector pairs, and the second indication information indicates M sets of first combination coefficients. The M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients are used to determine N space-frequency joint vectors, where M and N are both integers greater than or equal to 1. Therefore, in the technical solution of this application, the terminal device feeds back the first and second indication information to the network device. The first indication information indicates M reference signal port-frequency domain basis vector pairs, and the second indication information indicates M sets of first combination coefficients. This enables the network device to determine N space-frequency joint vectors using the M space-frequency basis vectors and the M sets of first combination coefficients. This achieves efficient compression feedback of the channel matrix (also known as the precoded matrix) in the joint space-frequency domain by the terminal device. Attached Figure Description

[0232] Figure 1 A schematic diagram of a communication system provided in an embodiment of this application;

[0233] Figure 2 Another schematic diagram of the communication system provided in the embodiments of this application;

[0234] Figure 3 A schematic diagram of the control plane and data plane protocol stacks of a network element provided in an embodiment of this application;

[0235] Figure 4 A schematic diagram of a channel state information feedback method provided in an embodiment of this application;

[0236] Figure 5A A schematic diagram of the antenna panel of a network device provided in an embodiment of this application;

[0237] Figure 5B Another schematic diagram of the antenna panel of the network device provided in the embodiments of this application;

[0238] Figure 6 A schematic diagram of PMI feedback provided for an embodiment of this application;

[0239] Figure 7 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0240] Figure 8 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0241] Figure 9 This is a schematic diagram of the structure of the terminal device provided in the embodiments of this application;

[0242] Figure 10 A structural schematic diagram of a network device provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0243] The embodiment of the present application provides a channel state information feedback method and a communication device, which are used for enabling a network device to determine a space-frequency joint vector representing joint space-frequency domain compression, so that a terminal device can efficiently compress and feed back a channel matrix (also referred to as a precoding matrix) on a joint space-frequency domain.

[0244] The technical solutions of the embodiment of the present application can be applied to various wireless communication systems, for example, a 5th generation (5G) system or new radio (NR), a long term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD), a universal mobile telecommunication system (UMTS), a mobile communication system after a 5G network (for example, a 6G mobile communication system), a vehicle to everything (V2X) communication system, and the like. The wireless communication system to which the present application is applicable includes a terminal device and a network device, and the terminal device and the network device can communicate with each other.

[0245] The terminal device and the network device of the present application are described below.

[0246] The terminal device can be a wireless terminal device capable of receiving scheduling and indication information of the network device. The wireless terminal device can be a device that provides voice and / or data connectivity for a user, or a handheld device with a wireless connection function, or another processing device connected to a wireless modem.

[0247] Terminal device, also known as user equipment (UE), mobile station (MS), mobile terminal (MT), etc., is a device including wireless communication function (providing voice / data connectivity to users), for example, handheld device with wireless connection function. At present, some examples of terminal device are: mobile phone, tablet computer, notebook computer, palm computer, notebook computer, wireless router, mobile internet device (MID), wearable device, virtual reality (VR) device, augmented reality (AR) device, wireless terminal in industrial control, wireless terminal in self driving, wireless terminal in Internet of Vehicles, wireless terminal in remote medical surgery, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, or wireless terminal in smart home, etc. For example, wireless terminal in Internet of Vehicles can be vehicle-mounted device, whole vehicle device, vehicle-mounted module, vehicle, etc. Wireless terminal in industrial control can be robot, etc. For example, wireless terminal in self driving can be unmanned aerial vehicle.

[0248] Network devices can be devices within a wireless network. For example, a network device can be a radio access network (RAN) node that connects terminal devices to a wireless network, and can also be called a radio access network device. A radio access network device is a device deployed in a radio access network to provide wireless communication functions for terminal devices. A non-limiting example of a radio access network device is a base station, which can be various forms of macro base stations, micro base stations (also called small stations), relay stations, access points (APs), wearable devices, vehicle-mounted devices, etc. Base stations can also be transmission and reception points (TRPs), transmission measurement functions (TMFs), etc. Exemplarily, the base station involved in the embodiments of this application can be a base station in a new radio (NR) network. In 5G NR, base stations can also be called transmission reception points (TRPs), transmission points (TPs), next-generation node Bs (ngNBs), or evolutionary node Bs (eNBs or eNodeBs) in long-term evolution (LTE) systems. In a broader sense, they can also be baseband units (BBUs), remote radio units (RRUs), active antenna units (AAUs), remote radioheads (RRHs), centralized units (CUs), distributed units (DUs), positioning nodes, etc.

[0249] Figure 1 This is a schematic diagram of a communication system according to an embodiment of this application. Please refer to... Figure 1 , Figure 1 The communication system shown includes network devices and terminal devices. The communication system includes one or more network devices and one or more terminal devices. In the communication system, UE1 through UE6 can all communicate with the network devices. Simultaneously, UE4, UE5, and UE6 can also form a communication system. For example, a network device can send downlink information to UE5, and UE5 can send downlink information to UE4 or UE6. Optionally, Figure 1The illustrated communication system can be an LTE system, or a 5G mobile communication system, or a mobile communication system after the 5G network (for example, a 6G mobile communication system).

[0250] Figure 2 Another schematic diagram of the communication system of the embodiments of the present application is shown. Please refer to Figure 2 , Figure 2 The communication system includes network devices and terminal devices. The communication system includes one or more network devices and one or more terminal devices.

[0251] In the communication system, in one possible implementation, one network device can communicate with one or more terminal devices. For example, as shown in Figure 2 Network device 1 communicates with terminal device 1 and terminal device 2 respectively. Network device 3 communicates with terminal device 2 and terminal device 3 respectively. In another possible implementation, multiple network devices can communicate with one terminal device, that is, multiple network devices simultaneously serve one terminal device. For example, network device 1, network device 2 and network device 3 simultaneously serve terminal device 2.

[0252] For example, the partial control plane and data plane protocol stack structure of the network element involved in the present application is shown in Figure 3 The network device and the terminal device both have the following modules:

[0253] Radio resource control (RRC) layer signaling interaction module: the network device and the terminal device can send and receive RRC signaling based on this module.

[0254] Media access control (MAC) layer signaling interaction module: the network device and the terminal device can send and receive media access control-control element (MAC-CE) signaling based on this module.

[0255] Physical (PHY) layer signaling and data exchange module: The network device and the terminal device can transmit and receive uplink / downlink control signaling based on the module, for example, the signaling can include signaling carried by a physical downlink control channel (PDCCH), signaling carried by a physical uplink control channel (PUCCH), and the like. Alternatively, the network device and the terminal device can transmit and receive uplink / downlink data based on the module, for example, the data can include data carried by a physical downlink shared channel (PDSCH), data carried by a physical uplink shared channel (PUSCH), and the like.

[0256] It should be understood that the above is only some examples of the communication system involved in the present application, and the communication system to which the communication method and the communication device provided by the present application are applied can include but is not limited to the above communication system.

[0257] Some technical terms involved in the present application are introduced below.

[0258] 1. Channel state information (CSI): In a wireless communication system, information reported by a receiving end (such as a terminal device) to a transmitting end (such as a network device) to describe the channel properties of the wireless communication link between the transmitting end and the receiving end. The CSI can include but is not limited to precoding matrix indication (PMI), rank indicator (RI), channel quality indicator (CQI), channel state information reference signal (CSI-RS resource indicator (CRI), and layer indicator (LI).

[0259] 2. Precoding matrix indicator (PMI): used to indicate a precoding matrix. In this application, for example, the PMI can include indication information of M reference signal port-frequency domain basis vector pairs (i.e., the first indication information in the embodiments below), indication information used to indicate M groups of first combination coefficients (i.e., the second indication information in the embodiments below), and indication information used to indicate N groups of second combination coefficients (i.e., the third indication information in the embodiments below). For details, please refer to the relevant description below. For example, the precoding matrix can be a precoding matrix determined by the terminal device based on a channel matrix of a frequency domain unit (e.g., the frequency domain length of a frequency domain unit can be a subband, or a resource block (RB), or Y times of a subband, Y<=1, and the value of Y can be 1 or 1 / 2). The channel matrix can be determined by the terminal device through channel estimation or based on channel reciprocity. It should be understood that the specific manner in which the terminal device determines the precoding matrix is not limited to the above.

[0260] The indication information in this document is described below. For example, the first indication information, the second indication information, and the third indication information in the embodiments below are applicable to the relevant indication description of the indication information below.

[0261] In this document, "used to indicate" can include direct indication and indirect indication. For example, when describing that "indication information" is used to indicate A, it can include that the indication information directly indicates A or indirectly indicates A, and it does not mean that A is necessarily carried in the indication information.

[0262] The information indicated by the indication is referred to as the to-be-indicated information. In the specific implementation process, there are many ways to indicate the to-be-indicated information, for example, but not limited to, the to-be-indicated information can be directly indicated, such as the to-be-indicated information itself or an index of the to-be-indicated information. The to-be-indicated information can also be indirectly indicated by indicating other information. There is an association between the other information and the to-be-indicated information. Only a part of the to-be-indicated information can be indicated, and the other part of the to-be-indicated information is known or agreed in advance. For example, the indication of a specific information can also be achieved by means of the arrangement order of each information agreed in advance (for example, specified by a protocol), thereby reducing the indication overhead to a certain extent. At the same time, the common part of each information can be identified and uniformly indicated to reduce the indication overhead caused by separately indicating the same information. For example, those skilled in the art should understand that a precoding matrix is composed of precoding vectors, and each precoding vector in the precoding matrix can have the same part in terms of composition or other attributes.

[0263] In addition, the specific indication manner can also be various existing indication manners, for example but not limited to the indication manners described above and various combinations thereof. The specific details of various indication manners can refer to the prior art, which will not be described herein. As can be seen from the above, for example, when multiple pieces of information of the same type need to be indicated, the indication manners of different information can be different. In the specific implementation process, the required indication manner can be selected according to the specific needs, and the selected indication manner is not limited by the embodiments of the application. In this way, the indication manners involved in the embodiments of the application should be understood as covering various methods that can enable the to-be-indicated party to know the to-be-indicated information.

[0264] For example, the precoding matrix can be obtained by singular value decomposition (SVD) on the channel matrix or the covariance matrix of the channel matrix, or can also be obtained by eigenvalue decomposition (EVD) on the covariance matrix of the channel matrix. It should be understood that the determination manners of the precoding matrix listed above are only examples and should not constitute any limitation on the present application.

[0265] The precoding matrix can be directly used for downlink data transmission, or can be subjected to some beamforming methods, for example, including zero forcing (ZF), regularized zero-forcing (RZF), minimum mean-squared error (MMSE), maximum signal-to-leakage-and-noise (SLNR), etc., to obtain a final precoding matrix used for downlink data transmission. The present application does not make any limitation thereon. In the absence of any specific description, the precoding matrix involved in the following can be a precoding matrix determined based on the method provided by the present application.

[0266] It can be understood that the precoding matrix determined by the terminal device can be understood as a to-be-fed back precoding matrix. The terminal device can indicate the to-be-fed back precoding matrix through the PMI, so as to facilitate the network device to recover the corresponding precoding matrix based on the PMI. It can be understood that the precoding matrix recovered by the network device based on the PMI can be the same as or similar to the to-be-fed back precoding matrix described above. In downlink data transmission, the higher the approximation degree between the precoding matrix determined by the network device according to the PMI and the precoding matrix determined by the terminal device, the more suitable the precoding matrix determined by the network device for downlink data transmission is to the channel state, and thus the reception quality of the signal can be improved.

[0267] 3、Antenna port: can be understood as a transmitting antenna identified by a receiving device, or a receiving antenna identified by a transmitting device; or a spatially distinguishable transmitting antenna or receiving antenna, which can be referred to as a physical antenna here.

[0268] 4、Reference signal port: a reference signal port can be understood as a virtual antenna or a logical antenna, which can be a weighted combination of multiple physical antennas, and the weighting coefficients are related to the precoding matrix loaded on the reference signal. If the precoding matrix loaded on the reference signal can be an identity matrix, at this time, one antenna port is configured for each virtual antenna, each virtual antenna corresponds to one physical antenna, and each antenna port can correspond to one reference signal or one reference signal port. If the precoding matrix loaded on the reference signal is not an identity matrix, at this time, multiple antenna ports are configured for one virtual antenna, one virtual antenna corresponds to multiple physical antennas, and multiple antenna ports can correspond to one reference signal or one reference signal port. For example, if the reference signal is CSI-RS, the reference signal port can be referred to as a CSI-RS port; if the reference signal is a demodulation reference signal (DMRS), the reference signal port can be referred to as a DMRS port.

[0269] 5、Frequency domain unit: the unit of frequency domain resource, which can represent different frequency domain resource granularity. The frequency domain unit may, for example, include but is not limited to one subband, one resource block (RB), one subcarrier, one resource block group (RBG), or one precoding resource block group (PRG), etc. In addition, the frequency domain length of one frequency domain unit can also be Y times of the CQI subband, Y <= 1, and the value of Y can be 1 or 1 / 2.

[0270] 6、Spatial domain basis vector: also can be called beam vector, spatial domain vector, spatial domain beam basis vector. One or more spatial domain basis vectors constitute a spatial domain basis. Each spatial domain basis vector corresponds to a transmit beam of the transmitting end device. Each element in the spatial domain basis vector can be represented as the weight of each antenna port. Based on the weight of each antenna port represented by each element in the spatial domain basis vector, the signals of each antenna port are linearly superimposed to form a region with strong signals in a certain direction in space. Optionally, the spatial domain basis vector is taken from a two-dimensional discrete fourier transform (DFT) matrix. Each column vector in the two-dimensional DFT matrix can be called a two-dimensional DFT vector. In other words, the spatial domain basis vector can be a two-dimensional DFT vector, which can be usually used to describe a beam formed by superimposing a horizontal beam and a vertical beam.

[0271] 7、Frequency domain basis vector: also can be called frequency domain vector, which is a vector that can be used to represent the variation law of the channel in the frequency domain. One or more frequency domain basis vectors constitute a frequency domain basis. Each frequency domain basis vector can represent a variation law. When the signal is transmitted through the wireless channel, it can pass through multiple paths from the transmitting antenna to the receiving antenna. The frequency selective fading caused by multipath delay is the variation of the frequency domain channel. Therefore, different frequency domain basis vectors can be used to represent the variation law of the channel in the frequency domain caused by the delay on different transmission paths. Optionally, the frequency domain basis vector can select a DFT matrix or an inverse discrete fourier transform (IDFT) matrix (i.e., the conjugate transpose matrix of the DFT matrix). In other words, the frequency domain basis vector can be a DFT vector or an IDFT vector.

[0272] The length of the frequency domain basis vector can be determined by the number of frequency domain units to be reported in the reported bandwidth, can be determined by the length of the reported bandwidth, or can be a protocol predefined value. The length of the frequency domain basis vector is not limited in the present application. The reported bandwidth can refer to the CSI reporting bandwidth (CSI-ReportingBand) carried in the CSI reporting configuration in the high layer signaling (for example, RRC message).

[0273] 8、Spatial frequency basis vector: determined by a spatial domain basis vector and a frequency domain basis vector. For example, a spatial frequency basis vector can be a vector formed by the Kronecker product of a spatial domain basis vector and a frequency domain basis vector. If the transmitting antenna of the network device is a single-polarized antenna, the number of rows of a spatial frequency basis vector is (M1×M2)×N f and the number of columns is 1, or the number of rows is 1 and the number of columns is (M1×M2)×N fwhere M1 is the number of transmit antenna ports of the network device in the horizontal direction, M2 is the number of transmit antenna ports of the network device in the vertical direction, N f is the number of frequency domain units. It should be understood that if the transmit antenna of the network device is a dual-polarized antenna, the number of rows in one space-frequency basis vector is 2×(M1×M2)×N f and the number of columns is 1, or the number of rows is 1 and the number of columns is 2×(M1×M2)×N f .

[0274] 9、Space-frequency joint vector: a vector used to represent the variation law of the channel in the joint space-frequency domain. One or more space-frequency joint vectors constitute a space-frequency joint basis. In this application, if the transmit antenna of the network device is a single-polarized antenna, the number of rows in the space-frequency joint vector matrix is (M1×M2)×N f and the number of columns is N, or the number of rows is N and the number of columns is (M1×M2)×N f , where M1 is the number of transmit antenna ports of the network device in the horizontal direction, M2 is the number of transmit antenna ports of the network device in the vertical direction, N f is the number of frequency domain units, and N is the number of space-frequency joint vectors used to represent the variation law of the channel in the joint space-frequency domain, i.e., the number of multipaths, i.e., the number of identifiable multipaths between the network device and the terminal device. It should be understood that if the transmit antenna of the network device is a dual-polarized antenna, the number of rows in the space-frequency joint vector matrix is 2×(M1×M2)×N f and the number of columns is N, or the number of rows is N and the number of columns is 2×(M1×M2)×N f .

[0275] 10、Reference signal port-space-frequency basis vector pair: used to represent the combination of the reference signal port selected by the terminal device and the space-frequency basis vector. One reference signal port-space-frequency basis vector pair corresponds to one reference signal port and one space-frequency basis vector. One reference signal port corresponds to one space domain basis vector, and the space domain basis vector and the space-frequency basis vector constitute one space-frequency basis vector.

[0276] 11、The related definitions of the mathematical symbols involved in this application include:

[0277] 1) A H , represents the conjugate transpose of matrix A.

[0278] 2) A * , represents the conjugate of matrix A.

[0279] 3) A T : represents the transpose of matrix A.

[0280] 3GPP R16 technical specification proposes a double-domain compression codebook scheme, that is, the channel matrix is compressed and fed back on the spatial domain and the frequency domain respectively. The precoding matrix can be represented by the weighted sum of the space-frequency component matrix constructed by at least one spatial domain basis vector and at least one frequency domain basis vector. Specifically, the network device sends a CSI-RS to the terminal device. The terminal device measures the downlink channel through the CSI-RS. The terminal device selects a spatial domain basis vector, a frequency domain basis vector and determines the corresponding linear combination coefficient through the downlink channel measurement result. Specifically, one spatial domain basis vector and one frequency domain basis vector correspond to one space-frequency basis vector. For each space-frequency basis vector, the terminal device determines a set of corresponding linear combination coefficients. Then, the terminal device reports the index of the selected at least one spatial domain basis vector, the index of the selected at least one frequency domain basis vector, and the linear combination coefficient corresponding to each space-frequency basis vector to the network device. The network device determines at least one space-frequency component matrix according to the at least one spatial domain basis vector and the at least one frequency domain basis vector selected by the terminal device, wherein one spatial domain basis vector and one frequency domain basis vector can uniquely determine one space-frequency component matrix, and then determines the precoding matrix in combination with the corresponding combination coefficient, that is, the precoding matrix is represented by the linear combination of the at least one space-frequency component matrix.

[0281] From the above technical solution, it can be seen that the double-domain compression codebook is compressed on the spatial domain and the frequency domain respectively for the channel matrix. However, how to more efficiently compress and feed back the channel matrix is a problem worth considering.

[0282] The present application provides corresponding technical solutions for enabling the network device to determine a space-frequency joint vector representing joint space-frequency domain compression, thereby realizing efficient compression and feedback of the channel matrix (also referred to as the precoding matrix) on the joint space-frequency domain by the terminal device.

[0283] The technical solutions of the present application will be described below in conjunction with specific embodiments.

[0284] Figure 4 A schematic diagram of a channel state information feedback method provided by an embodiment of the present application. Please refer to Figure 4 The method comprises:

[0285] 401. The network device performs precoding processing on the reference signal according to the spatial domain basis vector matrix to obtain a precoded reference signal.

[0286] The spatial domain basis vector matrix comprises at least one spatial domain basis vector, and one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port. Alternatively, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port. Different spatial domain basis vectors in the spatial domain basis vector matrix are associated with different reference signal ports.

[0287] The reference signal is a reference signal carried on the reference signal port. The reference signal can be a CSI-RS, or other reference signals such as a synchronization signal block (SSB), a DMRS, etc., and the specific embodiments of the present application are not limited in this regard. It should be noted that in the embodiments of the present application, the reference signal is taken as an example of a CSI-RS.

[0288] Optionally, the spatial domain basis vector matrix is an N t ×K matrix (i.e., the number of rows is N t and the number of columns is K), and the reference signal can be represented as a K × 1 matrix. Wherein, N t is the number of transmitting antenna ports of the network device, N t is an integer greater than or equal to 1; K is the number of reference signal ports, and K is less than or equal to N t .

[0289] Each column vector in the spatial domain basis vector matrix is a spatial domain basis vector, and each spatial domain basis vector in the spatial domain basis vector matrix is associated with a reference signal port. Different spatial domain basis vectors are associated with different reference signal ports. Each row vector in the spatial domain basis vector matrix is associated with an antenna port.

[0290] For example, the reference signal port is a CSI-RS port. The spatial domain basis vector matrix is represented as The first column vector in the spatial domain basis vector matrix corresponds to the CSI-RS port 0, the second column vector corresponds to the CSI-RS port 1, and so on, and the Kth column vector corresponds to the CSI-RS port K-1. The first row vector in the spatial domain basis vector matrix corresponds to the antenna port 0, the second row vector corresponds to the antenna port 1, and so on, and the N t th row vector corresponds to the antenna port N t -1. The reference signal can be represented as a matrix In the matrix S, s1 represents the CSI-RS carried on the CSI-RS port 0, s2 represents the CSI-RS carried on the CSI-RS port 1, and so on, and s K represents the CSI-RS carried on the CSI-RS port K-1. The network device multiplies the spatial domain basis vector matrix by the matrix S to obtain a precoded reference signal. That is, the precoded reference signal can be represented as:

[0291] That is, the network device can use the spatial basis vector matrix as a precoding matrix to map the reference signal carried by the CSI-RS port to each transmitting antenna port of the network device. That is, the first row vector in the spatial basis vector matrix multiplied by the matrix S is the CSI-RS transmitted on the antenna port 0. The second row vector in the spatial basis vector matrix multiplied by the matrix S is the CSI-RS transmitted on the antenna port 1. Similarly, the N t th row vector in the spatial basis vector matrix multiplied by the matrix S is the CSI-RS transmitted on the antenna port N t -1. The above process can be understood as the process of the network device mapping the CSI-RS on the CSI-RS port to the antenna port. It should be understood that the precoding reference signal is the precoding of the network device on the reference signal in a frequency domain unit. A frequency domain unit is the basic unit of the network device precoding the reference signal in the frequency domain, that is, the precoding matrix used by the network device on different frequency domain units can be the same or different.

[0292] It should be noted that the above example is an example of starting from 0 for the number of reference signal ports. In actual application, the number of reference signal ports can also start from 0. For example, the number of reference signal ports starts from 1, and the specific application is not limited in the present application.

[0293] Optionally, the at least one spatial basis vector included in the spatial basis vector matrix is at least one spatial basis vector selected by the network device from the pre-configured spatial basis vector, or the spatial basis vector matrix is determined by the network device.

[0294] The following describes a possible implementation. Optionally, Figure 4 The embodiment shown also includes step 401a. Step 401a can be performed before step 401.

[0295] 401a, the network device determines the spatial basis vector matrix according to the dimension of the transmitting antenna port and the form of the transmitting antenna port of the network device.

[0296] Wherein, the dimension of the transmitting antenna port is used to represent the number of transmitting antenna ports in the horizontal direction and the number of transmitting antenna ports in the vertical direction of the network device respectively. The form of the transmitting antenna port is determined according to the form of the transmitting antenna array surface of the access network device.

[0297] For example, the dimension of the transmit antenna ports is 2x2, which means the network device has two transmit antenna ports in the horizontal direction and two transmit antenna ports in the vertical direction. The dimension of the transmit antenna ports is 4x2, which means the network device has four transmit antenna ports in the horizontal direction and two transmit antenna ports in the vertical direction. It should be understood that the transmit antenna ports of the network device can also be one-dimensional, i.e., the number of transmit antenna ports in the horizontal direction is 1, or the number of transmit antenna ports in the vertical direction is 1.

[0298] Optionally, the antenna panel of the network device is an irregular antenna panel. For example, the antenna panel is composed of multiple panels, different panels are not in the same plane, or the antenna panel is one panel, and the transmit antenna ports on the panel are not uniformly distributed. Exemplarily, Figure 5A The network device shown uses a distributed single-polarized antenna panel, which is composed of two single-polarized panels, and the two panels are not in the same plane, and the dimension of the transmit antenna ports of each panel is 4x2. That is, 4 ports in the horizontal direction and 2 ports in the vertical direction. The two panels are connected by a cable, and the cable is not in the same plane as the two panels. Figure 5A It can be seen that, if the two panels are regarded as one large panel, the antenna ports on the large panel are not uniformly distributed.

[0299] The network device can adapt to the 16x16-dimensional spatial domain basis vector matrix of the two antenna panels. The spatial domain basis vector matrix can be represented as wherein Q 11 , Q 22respectively, are diagonal sub-block matrices, specifically, 8x8 dimensional two-dimensional DFT matrices corresponding to 4 ports in horizontal direction and 2 ports in vertical direction. All other elements in the spatial domain basis vector matrix are 0. That is, the transmitting antenna ports of each antenna panel are uniformly and regularly distributed, but the transmitting antenna ports of the two panels as a whole are irregularly distributed. Therefore, the spatial domain basis vector matrix shown above is more suitable for the transmitting antenna port form of the real antenna panel. The network device performs precoding processing on the reference signal by using the spatial domain basis vector matrix determined according to the dimension of the transmitting antenna port and the form of the transmitting antenna port, so that the precoding loaded on the reference signal matches the actual antenna form, thereby facilitating improvement of the feedback accuracy of the PMI. If the irregular distribution of the transmitting antenna ports in the antenna panel is not considered, the terminal device performs joint measurement and feedback of the channel state information by regarding the two distributed panels as a whole. That is, for the two antenna panels as a whole, that is, 8 ports in horizontal direction and 2 ports in vertical direction, the spatial domain basis vector matrix used by the terminal device is a 16x16 dimensional two-dimensional DFT matrix corresponding to 8 ports in horizontal direction and 2 ports in vertical direction. Since the distribution of the transmitting antenna ports of the antenna panel is non-uniform, and the two-dimensional DFT matrix is determined on the basis of regarding the antenna panel as a whole and considering that the antenna ports are uniformly distributed, therefore, the network device uses the two-dimensional DFT matrix as the spatial domain basis vector matrix, which causes the two-dimensional DFT matrix to be mismatched with the form of the transmitting antenna ports of the antenna panel, thereby causing the feedback accuracy of the PMI to decrease.

[0300] Yet another example, Figure 5B The network device shown above uses a dual-polarized distributed antenna panel, which is spliced by two dual-polarized panels, and the two panels are not on the same plane, and the dimension of the number of transmitting antenna ports in each polarization direction of each panel is 2x2. That is, 2 ports in horizontal direction and 2 ports in vertical direction. By Figure 5B It can be seen that, if the two panels are regarded as a whole panel, the antenna ports on the panel are not uniformly distributed.

[0301] The network device can adapt to the 16x16 dimensional spatial domain basis vector matrix of the two antenna panels. The spatial domain basis vector matrix can be represented as Q 1 , Q 2 respectively, are two 8x8 dimensional diagonal sub-block matrices corresponding to two polarization directions, and all other elements in the spatial domain basis vector matrix are 0. For the diagonal sub-block matrix Q i , in the i-th polarization direction, it can be represented as wherein Specifically, the 4x4 two-dimensional DFT matrix corresponds to the horizontal direction 2-port and the vertical direction 2-port. That is, the transmission antenna ports of each antenna panel are uniformly and regularly distributed, but the transmission antenna ports of the two panels as a whole are irregularly distributed. Therefore, the spatial domain basis vector matrix shown above is more suitable for the form of the transmission antenna ports of the real antenna panel. The network device performs precoding processing on the reference signal through the spatial domain basis vector matrix, thereby facilitating the improvement of the feedback accuracy of the PMI. If the irregular distribution of the transmission antenna ports in the antenna panel is not considered, the terminal device measures and feeds back the channel state information jointly as a whole of the two distributed panels. That is, for the two antenna panels as a whole, that is, each polarization is 4-port in the horizontal direction and 2-port in the vertical direction, and usually the same set of spatial domain basis vectors are shared by the two polarization directions, the spatial domain basis vector matrix adopted by the terminal device is a 16x16 block diagonal matrix, each polarization direction corresponds to a diagonal sub-block matrix, and each diagonal sub-block matrix is the same 8x8 two-dimensional DFT matrix corresponding to the horizontal direction 4-port and the vertical direction 2-port. Since the distribution of the transmission antenna ports of the antenna panel is non-uniform, and the two-dimensional DFT matrix is determined on the basis of considering the antenna panel as a whole and assuming that the antenna ports are uniformly distributed, therefore, the network device uses the two-dimensional DFT matrix as the diagonal sub-block matrix in each polarization direction of the spatial domain basis vector matrix, which causes the spatial domain basis vector matrix to be mismatched with the form of the transmission antenna ports of the antenna panel, thereby causing the feedback accuracy of the PMI to decrease.

[0302] In the above step 401a, the configuration freedom of the spatial domain basis vector is in the network device, and the network device can determine the spatial domain basis vector matrix that is adapted to the dimension and form of the transmission antenna ports according to the form of the transmission antenna ports of the network device.

[0303] Therefore, for the scenario of the irregular antenna panel, the network device can determine the spatial domain basis vector matrix in combination with the dimension of the transmission antenna ports and the form of the transmission antenna ports, so that the spatial domain basis vector matrix is matched with the form of the transmission antenna ports of the antenna panel, thereby facilitating the improvement of the feedback accuracy of the PMI.

[0304] It should be noted that the above describes the spatial domain basis vector matrix determined by the network device on one frequency domain unit. On N f frequency domain units, the network device determines N f spatial domain basis vector matrices. That is, one frequency domain unit corresponds to one spatial domain basis vector matrix.

[0305] It should be noted that the precoding reference signals transmitted by the network device on different frequency domain units can be generated by the same spatial domain basis vector matrix, or can be generated by different spatial domain basis vector matrices, and the application does not limit the specific implementation. That is, the spatial domain basis vector matrices corresponding to different frequency domain units can be the same or different.

[0306] 402、The network device transmits the precoding reference signal to the terminal device. Correspondingly, the terminal device receives the precoding reference signal from the network device.

[0307] Specifically, the network device transmits the precoding reference signal to the terminal device through N f transmit antenna ports in each of the N t frequency domain units. Correspondingly, the terminal device receives the precoding reference signal from the network device through N f transmit antenna ports on the N t frequency domain units.

[0308] 403、The terminal device determines the CSI according to the precoding reference signal.

[0309] The CSI includes first indication information and second indication information. The first indication information and the second indication information are used to indicate N spatial-frequency joint vectors. The N spatial-frequency joint vectors are used to represent the variation of the channel from the network device to the terminal device in the joint spatial-frequency domain. N is an integer greater than or equal to 1. The N spatial-frequency joint vectors serve as the basis for the terminal device to determine the precoding matrix.

[0310] The first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs. M is an integer greater than or equal to 1 and less than or equal to N t ×N f .

[0311] M reference signal port-frequency domain basis vector pairs are used to indicate the reference signal port and the frequency domain basis vector selected by the terminal device. The spatial domain basis vector associated with the reference signal port in one reference signal port-frequency domain basis vector pair and the frequency domain basis vector in the reference signal port-frequency domain basis vector pair are used to determine one spatial-frequency basis vector. The M reference signal port-frequency domain basis vector pairs correspond to M spatial-frequency basis vectors, and different reference signal port-frequency domain basis vector pairs correspond to different spatial-frequency basis vectors. For example, the reference signal port-frequency domain basis vector pair is reference signal port 1-frequency domain basis vector 1, which indicates that the terminal device selects reference signal port 1 and frequency domain basis vector 1. The network device can determine the corresponding spatial-frequency basis vector through the spatial domain basis vector associated with the reference signal port 1 and the frequency domain basis vector 1. The network device can determine one corresponding spatial-frequency basis vector through one reference signal port-frequency domain basis vector pair. Therefore, the M reference signal port-frequency domain basis vector pairs correspond to M spatial-frequency basis vectors. One group of first combination coefficients in the M groups of first combination coefficients is associated with one spatial-frequency basis vector in the M spatial-frequency basis vectors. Or, one group of first combination coefficients in the M groups of first combination coefficients is associated with one spatial-frequency basis vector in the M spatial-frequency basis vectors. It should be noted that, optionally, the frequency domain basis vector selected by the terminal device can be selected by the terminal device from the preconfigured frequency domain basis vector. “Preconfigured” can mean that the network device pre-indicates to the terminal device through signaling, so that the terminal device determines the corresponding content according to the signaling, and the content can be pre-saved.

[0312] N spatial-frequency joint vectors can be determined through the M spatial-frequency basis vectors and the M groups of first combination coefficients. Any one spatial-frequency joint vector in the N spatial-frequency joint vectors is a linear combination of the M spatial-frequency basis vectors based on the M groups of first combination coefficients.

[0313] Specifically, one spatial-frequency joint vector can be represented by linear combination of the M spatial-frequency basis vectors and the M groups of first combination coefficients. For example, formula 1 represents the N spatial-frequency joint vectors:

[0314]

[0315] wherein the matrix Each column vector of the matrix B is a spatial-frequency joint vector; each column vector b m of the matrix B (1≤m≤M) is a spatial-frequency basis vector; and the combination coefficient matrix C 13 has a dimension of M×N, and each row corresponds to one group of first combination coefficients. For the nth spatial-frequency joint vector, there are

[0316] Any one of the spatial-frequency joint vectors is a linear combination of the M spatial-frequency basis vectors based on a first combination of M coefficients. A first combination of coefficients includes N first coefficients. For example, the first combination of M coefficients in the above Formula 1 includes N first coefficients. The Nth first coefficient in the first combination of M coefficients is used to represent the weight of the Nth spatial-frequency joint vector in the Mth spatial-frequency basis vector. It should be noted that the value of M and the value of N can be configured by the network device to the terminal device, or determined by the terminal device and reported to the network device, or determined by negotiation between the network device and the terminal device, or predefined by the communication protocol, which is not limited in the present application. 13 As shown in the above Formula 2, each row vector is a first combination of coefficients, and each row vector includes N elements, and each element is a first coefficient. For example, the Mth first combination of coefficients in the M first combinations of coefficients includes N first coefficients. The Nth first coefficient in the N first coefficients is used to represent the weight of the Nth spatial-frequency joint vector in the Mth spatial-frequency basis vector. It should be noted that the value of M and the value of N can be configured by the network device to the terminal device, or determined by the terminal device and reported to the network device, or determined by negotiation between the network device and the terminal device, or predefined by the communication protocol, which is not limited in the present application.

[0317] Optionally, the CSI further includes third indication information, and the third indication information is used to indicate N second combinations of coefficients associated with the N spatial-frequency joint vectors. The precoding matrix can be determined by the N spatial-frequency joint vectors and the N second combinations of coefficients.

[0318] In a possible implementation, one of the N second combinations of coefficients is associated with one of the N spatial-frequency joint vectors. The precoding matrix is a linear combination of the N spatial-frequency joint vectors based on the N second combinations of coefficients.

[0319] Specifically, taking a single-polarized antenna as an example, the precoding matrix is linearly approximated and combined by the N spatial-frequency joint vectors and the N second combinations of coefficients. For example, the precoding matrix W can be represented as the following Formula 2.

[0320]

[0321] wherein H is a precoding matrix or a channel matrix to be fed back, including R column vectors h r (1≤r≤R); Each column vector h is a spatial-frequency joint vector. The combination coefficient matrix C2 has a dimension of N×R, and each row corresponds to a second combination of coefficients. One column vector in W represents a channel corresponding to one receive antenna port of the terminal device or a precoding vector corresponding to one data stream. For the rth receive antenna port or the rth data stream, there are r is an integer greater than or equal to 1 and less than or equal to R. R is the number of second coefficients in a second combination of coefficients corresponding to one polarization direction. For details, please refer to the relevant introduction in the following.

[0322] Specifically, taking a dual-polarized antenna as an example, the number of transmit antenna ports in one polarization direction is N t / 2, and two polarization directions share one set of space-frequency joint vectors. The precoding matrix is linearly approximated and combined by N space-frequency joint vectors and N sets of second combination coefficients, wherein the N sets of second combination coefficients contain corresponding linear coefficients in each polarization direction. For example, formula 3 represents the precoding matrix W:

[0323]

[0324] wherein W is a precoding matrix or a channel matrix to be fed back, including R column vectors; is a component of the rth column vector in the xth polarization direction, x = 1 or 2. Each column vector of W is a space-frequency joint vector; the row vectors of the same row in the combination coefficient matrix C2 in two polarization directions are as follows and is a set of second combination coefficients. One column vector in W represents a channel corresponding to one receive antenna port of the terminal device or a precoding vector corresponding to one data stream. For the rth receive antenna port or the rth data stream, the components in each polarization direction are r is an integer greater than or equal to 1 and less than or equal to R.

[0325] The following introduces the number R of second combination coefficients corresponding to one set of second combination coefficients in one polarization direction in the N sets of second combination coefficients.

[0326] 1. One set of second combination coefficients in the N sets of second combination coefficients corresponds to N r second combination coefficients in one polarization direction, N r is the number of receive antenna ports of the terminal device.

[0327] 2. One set of second combination coefficients in the N sets of second combination coefficients corresponds to N RANK second combination coefficients in one polarization direction, N RANK is the value of the rank corresponding to the precoding matrix. The number of data streams transmitted between the network device and the terminal device is equal to the rank corresponding to the precoding matrix. N RANK is an integer greater than or equal to 1 and less than or equal to N r .

[0328] Specifically, when the transmit antenna is a single-polarized antenna, any set of second combination coefficients contains R second combination coefficients, and when the transmit antenna is a dual-polarized antenna, any set of second combination coefficients contains 2×R second combination coefficients. R is equal to the number N r of receive antenna ports of the terminal device or the value N of the rank corresponding to the precoding matrix.RANK .

[0329] It should be noted that, optionally, the CSI includes a PMI, and the PMI is used to indicate a precoding matrix. The first indication information, the second indication information, and the third indication information can also be information included in the PMI.

[0330] The following describes a possible implementation of the step 403 in combination with the steps 403a to 403c.

[0331] 403a. The terminal device determines, according to a precoding reference signal, an equivalent channel between the terminal device and the network device.

[0332] The terminal device receives, through N f frequency domain units, precoding reference signals of N t transmit antenna ports sent by the network device. The terminal device performs channel estimation by using the precoding reference signals to obtain the equivalent channel. For example, the equivalent channel estimated by the terminal device on the wth frequency domain unit can be represented as H (z) P, z is an integer greater than or equal to 1 and less than or equal to N f . The dimension of H (z) P is N r × K. Where P is a spatial domain basis vector matrix loaded on the reference signal by the network device, and H (z) is a channel matrix corresponding to the zth frequency domain unit.

[0333] 403b. The terminal device determines N reference signal port-frequency domain joint vectors according to the equivalent channel.

[0334] The N reference signal port-frequency domain joint vectors are equivalent to projections of N spatial-frequency joint vectors on a spatial domain basis vector matrix. The projection can be understood as a linear transformation of mapping the spatial-frequency joint vectors to a spatial domain basis vector space.

[0335] For example, a matrix composed of N spatial-frequency joint vectors is represented as wherein contains N column vectors, and each column vector is a spatial-frequency joint vector. Then, a matrix composed of the N reference signal port-frequency domain joint vectors can be represented as Any column vector of the matrix composed of the N reference signal port-frequency domain joint vectors is a reference signal port-frequency domain joint vector.

[0336] Specifically, the terminal device can determine an equivalent channel corresponding to each frequency domain unit in the N f frequency domain units. The terminal device determines the N reference signal port-frequency domain joint vectors based on statistical characteristics of the equivalent channels at multiple time instants.

[0337] For example, the terminal device determines N f equivalent channel accumulations corresponding to a plurality of time instants and a plurality of frequency domain units to obtain a reference signal port-frequency domain joint covariance matrix Then, the terminal device performs eigenvalue decomposition on the reference signal port-frequency domain joint covariance matrix to obtain eigenvectors to obtain N reference signal port-frequency domain joint vectors. The reference signal port-frequency domain joint covariance matrix may be expressed as:

[0338]

[0339] wherein, is a covariance matrix obtained by accumulating the original channel H (n) (i.e., the real channel measured by the reference signal without precoding, rather than the equivalent channel). U is the right unitary matrix of the covariance matrix. The first N columns of U * are used as N spatial-frequency joint vectors for characterizing the change rule of the channel. That is, U * is the conjugate of U. denotes a matrix composed of the first N column vectors in U * . includes N column vectors, and each column vector is a spatial-frequency joint vector. α t is a filter coefficient, denotes a block diagonal matrix with dimensions of (N t ×N f )×(N f ×N×K), and each block on the main diagonal is a matrix P with dimensions of N t ×K, and the elements at other positions are all 0. N f is the number of frequency domain units. Therefore, the matrix composed of N reference signal port-frequency domain joint vectors can be expressed as

[0340] 403c. The terminal device determines M reference signal port-frequency domain basis vector pairs and M groups of first combination coefficients from the P reference signal port-frequency domain basis vector pairs according to the N reference signal port-frequency domain joint vectors.

[0341] wherein, P is equal to the number of frequency domain basis vectors N fbasis multiplied by the number of reference signal ports K. N fbasis is less than or equal to the number of frequency domain units. Optionally, K is less than or equal to the number of transmit antenna ports of the network device.

[0342] The following introduces a possible implementation of step 403c in combination with steps 403c.1 to 403c.3.

[0343] Step 403c.1: The terminal device projects each reference signal port-frequency domain joint vector in the N reference signal port-frequency domain joint vectors onto the frequency domain basis vector matrix F, to obtain N first combination coefficient matrices , where the vector component corresponding to the reference signal port pair in each reference signal port-frequency domain joint vector is projected onto the frequency domain basis vector matrix F to obtain the vector component corresponding to the reference signal port pair in the first combination coefficient matrix

[0344] Each of the N first combination coefficient matrices includes P first combination coefficients, one of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs; or one group of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs. Different first combination coefficients are associated with different reference signal port-frequency domain basis vector pairs. That is, each first combination coefficient is a KxN fbasis matrix. Each element in the first combination coefficient matrix corresponds to a reference signal port-frequency domain basis vector pair. The row number of the element in the first combination coefficient matrix is the reference signal port number associated with the reference signal port-frequency domain basis vector pair corresponding to the element, and the column number of the element in the first combination coefficient matrix is the number of the frequency domain basis vector associated with the reference signal port-frequency domain basis vector pair corresponding to the element.

[0345]

[0346] The dimension of the frequency domain basis vector matrix F is N f x N fbasis . The above step 403c.1 is introduced taking an example that the frequency domain basis vector matrix includes N fbasis frequency domain basis vectors. N fbasis may be equal to or less than N f . f m is the mth frequency domain basis vector in the frequency domain basis vector matrix, and m is an integer greater than or equal to 1 and less than or equal to N fbasis .

[0347] The correspondence between the vector component corresponding to the reference signal port in each reference signal port-frequency domain joint vector and the reference signal port-frequency domain joint vector can be represented by the following formula:

[0348]

[0349] Optionally, the number of frequency domain basis vectors in the frequency domain basis vector matrix is related to the at least one frequency domain unit N f . The at least one frequency domain basis vector included in the frequency domain basis vector matrix is selected by the terminal device from the preconfigured frequency domain basis vectors.

[0350] Step 403c.2: The terminal device determines M reference signal port-frequency basis vector pairs from the P reference signal port-frequency basis vector pairs according to the N first linear combination coefficient matrices.

[0351] For example, the terminal device adds the amplitude square of the same position elements in each of the N first combination coefficient matrices to obtain a coefficient energy sum matrix with dimensions of KxN fbasis As introduced above, each element in each first combination coefficient matrix corresponds to a reference signal port-frequency basis vector pair. Therefore, it is known that each element in the coefficient energy sum matrix corresponds to a reference signal port-frequency basis vector pair, and the reference signal port-frequency basis vector pair corresponding to the elements at the same position in the first combination coefficient matrix and the coefficient energy sum matrix is the same. Then, the terminal device selects M elements with the largest values from the coefficient energy matrix. The terminal device takes the reference signal port-frequency basis vector pairs corresponding to the M elements with the largest values as the M reference signal port-frequency basis vector pairs.

[0352] Step 403c.3: The terminal device determines M groups of first combination coefficients according to the M reference signal port-frequency basis vector pairs.

[0353] As known from the above step 403c.1, each first combination coefficient matrix includes P first combination coefficients, and one first combination coefficient in the P first combination coefficients is associated with one reference signal port-frequency basis vector pair. The terminal device can obtain the first combination coefficients associated with the M reference signal port-frequency basis vector pairs from the N first combination coefficient matrices respectively to obtain the M groups of first combination coefficients. Each group of first combination coefficients in the M groups of first combination coefficients includes the first combination coefficients associated with one reference signal port-frequency basis vector pair, and different groups of first combination coefficients include the first combination coefficients associated with different reference signal port-frequency basis vector pairs.

[0354] Optionally, each of the M groups of first combination coefficients comprises N first combination coefficients. As known from step 403c.1, each of the first combination coefficient matrices comprises P first combination coefficients, and one of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs. Different first combination coefficients are associated with different reference signal port-frequency domain basis vector pairs. Thus, for a certain reference signal port-frequency domain basis vector pair, each of the first combination coefficient matrices comprises one first combination coefficient associated with the reference signal port-frequency domain basis vector pair. Therefore, for a certain reference signal port-frequency domain basis vector pair, N of the N first combination coefficient matrices comprise N first combination coefficients associated with the reference signal port-frequency domain basis vector pair. Thus, one group of first combination coefficients associated with the reference signal port-frequency domain basis vector pair comprises N first combination coefficients. The same is true for other reference signal port-frequency domain basis vector pairs.

[0355] Thus, each spatial-frequency joint vector is approximated by a linear combination of M spatial-frequency basis vectors, and the spatial-frequency joint vector describes the statistical characteristics of the channel in the joint spatial-frequency domain. For example, the spatial-frequency joint vector is an eigenvector obtained by performing eigenvalue decomposition on the long-term statistical covariance matrix of the channel. Therefore, the spatial-frequency joint vector changes relatively slowly in the time domain, and the terminal device can determine to report the N spatial-frequency joint vectors in a long period (i.e., a first period). That is, the terminal device can determine to report the first indication information and the second indication information in the first period. The period length of the first period can be 200 ms (milliseconds), 300 ms, or 400 ms, and is not limited specifically.

[0356] Optionally, step 403 further comprises step 403d.

[0357] 403d. The terminal device obtains N groups of second combination coefficients according to the equivalent channel and the N reference signal port-frequency domain joint vectors.

[0358] For example, the N groups of second combination coefficients can be denoted as C2, and the specific representation is as shown in the following formula 5:

[0359]

[0360] The matrix composed of the N reference signal port-frequency domain joint vectors can be denoted as is an equivalent channel between the network device and the terminal device.

[0361] Specifically, the terminal device can determine to report N sets of second combination coefficients to the network device in a short period (i.e., a second period), that is, the terminal device can determine to report third indication information to the network device in the second period. Since some channel characteristics of the channel change rapidly, the terminal device can determine to report N sets of second combination coefficients to the network device in a short period. For example, the energy, phase, and the like of the channel. Exemplarily, the period length of the second period can be 5 ms, 10 ms, or 20 ms, which is not limited in the present application. It should be understood that the long period and the short period are relative concepts, and the length of the first period is greater than the length of the second period, for example, the length of the first period is multiple integer times of the length of the second period. Exemplarily, the period length of the first period can be 100 ms, and the period length of the second period can be 5 ms.

[0362] Two reporting modes of the N sets of second combination coefficients are introduced below.

[0363] 1. When the feedback is the channel information corresponding to each receive antenna port, that is, the to-be-fed-back quantity is a precoding matrix, the terminal device can feed back the second combination coefficients corresponding to multiple receive antennas of the terminal device.

[0364] 2. When the feedback is the precoding vector corresponding to each data stream, that is, the to-be-fed-back quantity is a channel matrix, singular value decomposition is performed on the second combination coefficients corresponding to all receive antennas to obtain the second combination coefficients corresponding to each data stream.

[0365] In the technical solution of the present application, the terminal device fully utilizes the sparsity of the channel in the angle domain and the delay domain (joint space domain and frequency domain) to realize the linear combination representation of the joint space and frequency domain channel with N space and frequency joint vectors. Since the channel is more sparse in the joint space and frequency domain, the number of space and frequency joint vectors required to represent the channel in the technical solution of the present application is less than the number of space and frequency component matrices determined in the double-domain compression scheme. This is conducive to reducing the feedback overhead of the terminal device. Or, in the case of the same feedback overhead, the feedback accuracy of the PMI is improved.

[0366] Further, since the space domain basis vector matrix loaded on the reference signal port by the network device is determined based on the shape of the antenna panel transmission antenna port, the space domain basis vector matrix is matched with the shape of the antenna panel transmission antenna port. Therefore, for the scene of irregular antenna panels, the technical solution of the present application is conducive to improving the feedback accuracy of the PMI; or, the technical solution of the present application is conducive to reducing the feedback overhead of the PMI.

[0367] Further, the spatial domain basis vectors respectively associated with the M spatial frequency basis vectors are the spatial domain basis vectors associated with the reference signal ports selected by the terminal device. The M groups of first combination coefficients are obtained by the terminal device through equivalent channel estimation. As described above, the M spatial frequency basis vectors and the M groups of first combination coefficients are used to determine the N spatial frequency joint vectors. That is, the spatial frequency basis vectors are one group of parameters used to determine the N spatial frequency joint vectors. In addition to the M spatial frequency basis vectors, the network device further needs to combine the M groups of first combination coefficients to jointly determine the N spatial frequency joint vectors. Then, the network device combines the N spatial frequency joint vectors and the N groups of second combination coefficients to determine the precoding matrix. Instead of directly determining the spatial frequency basis vectors from the spatial domain basis vectors and the frequency domain basis vectors selected by the terminal device as the N spatial frequency joint vectors. In this way, the N spatial frequency joint vectors are more suitable for the characteristics of the downlink channel between the network device and the terminal device. That is, the feedback accuracy of the PMI is improved.

[0368] Therefore, according to the technical solution described above, the codebook in the scheme of the present application can be expressed as:

[0369] W dl = W SF C 13 C2 Formula 6

[0370] Wherein, W dl represents the codebook in the scheme of the present application, W SF is a reference signal port-frequency domain basis vector pair selection matrix, with a dimension of (N f ×K)×M, indicating that M reference signal port-frequency domain basis vector pairs are selected from N f ×K reference signal port-frequency domain basis vector pairs. Only one element in each column vector of the reference signal port-frequency domain basis vector pair selection matrix is 1, and the rest are 0. And each column vector has a different position of 1. C 13 is M groups of first combination coefficients, with a dimension of M×N. When the transmitting antenna is a single-polarized antenna, C2 is N groups of second combination coefficients, with a dimension of N×R. When the transmitting antenna is a dual-polarized antenna, C2 is N groups of second combination coefficients corresponding to each polarization direction, with a dimension of 2N×R. For details, please refer to C2 in the aforementioned formula 3.

[0371] The network device can determine the precoding matrix according to the codebook shown in the above formula 6 and the spatial domain basis vector matrix. Then, the network device can design the precoding matrix used for data transmission according to the precoding matrix.

[0372] 404, the terminal device sends the CSI to the network device. Correspondingly, the network device receives the CSI from the terminal device.

[0373] The content included in the CSI is described above.

[0374] Optionally, the terminal device can indicate the M reference signal port-frequency domain basis vector pairs to the network device in the form of a bitmap or a combination number. For example, there are P reference signal port-frequency domain basis vector pairs in total, P = K x N fbasis . The terminal device selects M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs. In a possible implementation, the terminal device indicates in the form of a bitmap. The terminal device can use a K x N fbasis bitmap to indicate, for example, the positions corresponding to the selected reference signal port-frequency domain basis vector pairs are set to 1, and the other positions are set to 0; or the positions corresponding to the selected reference signal port-frequency domain basis vector pairs are set to 0, and the other positions are set to 1. The terminal device reports the bitmap. In another possible implementation, the terminal device indicates in the form of a combination number. For selecting M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs, there are possible cases in total. Each possible case corresponds to a number x, where x is a positive integer greater than or equal to 1 and less than or equal to . The terminal device can report the number corresponding to the selected P reference signal port-frequency domain basis vector pairs.

[0375] As can be seen from the above scheme, the terminal device can indicate the reference signal port selected by the terminal device to the network device through the first indication information. The network device can determine the spatial domain basis vector associated with the reference signal port. Since the spatial domain basis vector matrix loaded by the network device on the reference signal port is determined by the network device based on the shape of the transmission antenna port of the antenna panel, the spatial domain basis vector matrix is matched with the shape of the transmission antenna port of the antenna panel. Therefore, for the scene of the irregular antenna panel, the technical scheme of the present application is beneficial to improving the feedback accuracy of the PMI; or in other words, it is beneficial to reducing the feedback overhead of the PMI. Thus, the problem of the decline of the PMI feedback accuracy caused by the mismatch between the spatial domain basis vector determined by the terminal device and the transmission antenna port of the antenna panel is avoided, and the applicability and flexibility of the scheme are improved.

[0376] In the technical solution, the terminal device indicates the N spatial-frequency joint vectors through the first indication information and the second indication information, and the spatial-frequency joint vector is a vector that can be used to represent the variation law of the channel in the joint spatial-frequency domain. The sparsity of the channel in the joint spatial-frequency domain is better, and the terminal device can select the complex coefficients of some delay-angle directions with higher energy to feed back, and the feedback amount is less than that of the double-domain compression scheme. In the double-domain compression scheme, the sparsity of the channel in the spatial domain and the frequency domain is limited. For example, the energy of the channel in some angle directions is higher, and the terminal device can select some angle directions with higher energy; the energy of the channel in some delay components is higher, and the terminal device can select some delay components with higher energy; and the network device determines the spatial-frequency components based on the angle directions and the delay components selected by the terminal device. Since the multipath signals with different arrival delays may have similar arrival angle directions, and the arrival delays of the multipath signals with different arrival angle directions may be similar, the multipath signals in the angle domain or the delay domain are superimposed together, and it is difficult to distinguish them, that is, the resolution of the channel in the angle domain and the delay domain is limited. Therefore, the sparsity of the channel in the joint spatial-frequency domain is better than the sparsity of the channel in the spatial domain and the frequency domain. Therefore, the number of the spatial-frequency joint vectors determined by the terminal device is less than the number of the spatial-frequency component matrix determined in the double-domain compression scheme. Therefore, it is beneficial to reduce the PMI feedback overhead. Or, in the same feedback overhead, the feedback accuracy of the PMI is improved.

[0377] The technical solution of the present application will be described below Figure 6 The feedback interaction process of the PMI of the technical solution of the present application is introduced as follows Figure 6 The terminal device determines M reference signal port-frequency vector pairs and M groups of first combination coefficients C 13 according to the precoding reference signal, and reports the first indication information for indicating the reference signal port-frequency basis vector pair selection matrix W SF and the second indication information for indicating the M groups of first combination coefficients C 13 in a long period (i.e. a first period), so that the network device can recover the N spatial-frequency joint vectors from the first indication information and the second indication information. In addition, the terminal device determines N groups of second combination coefficients C2 according to the measurement result obtained from the precoding reference signal, and reports the third indication information for indicating the N groups of second combination coefficients C2 in a short period (i.e. a second period), so that the network device can determine the precoding matrix according to the N groups of second combination coefficients and the N spatial-frequency joint vectors. Since the length of the first period is an integer multiple of the length of the second period, at the starting time of the first period, the terminal device not only reports W SF and C 13 , but also reports C2. It should be understood that the terminal can report W SF , C 13W and C2; W can also be reported in one signaling SF W and C 13 C2 in another signaling; W, C and C2 can also be reported in different signalings respectively; the present application does not limit this. SF W and C 13 W and C2; the present application does not limit this.

[0378] The terminal device adopts the manner of feeding back N space-frequency joint vectors in a long period and feeding back N groups of second combination coefficients in a short period. Compared with the double-domain compression scheme, the technical solution of the present application has smaller PMI feedback overhead of the terminal device, or in other words, has higher PMI feedback accuracy under the same feedback overhead.

[0379] Optionally, Figure 4 The embodiment shown also includes step 405. Step 405 can be performed after step 404.

[0380] 405. The network device determines a precoding matrix according to the CSI and the spatial domain basis vector matrix.

[0381] In addition, the network device can design a precoding matrix for data transmission according to the precoding matrix. Then, when the network device transmits a data signal, the network device can first perform precoding processing on the data signal through the precoding matrix for data transmission, and then transmit the precoding-processed data signal. For example, each terminal device feeds back a precoding matrix of a single user. The network device can jointly design a precoding matrix for data transmission according to the precoding matrices fed back by multiple terminal devices. Thus, interference suppression between users is achieved.

[0382] The following describes a possible implementation of the above step 405 in combination with steps 405a to 405e.

[0383] Step 405a: The network device determines M reference signal port-frequency domain basis vector pairs according to the first indication information.

[0384] Step 405b: The network device determines the spatial domain basis vector associated with each reference signal port respectively according to the M reference signal port-frequency domain basis vector pairs. It should be understood that one spatial domain basis vector is taken from the spatial domain basis vector matrix known by the network device.

[0385] As described above, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port. Therefore, the network device determines the reference signal port selected by the terminal device through the M reference signal port-frequency domain basis vector pairs, and determines the spatial domain basis vector associated with the reference signal port selected by the terminal device.

[0386] Step 405c, the network device determines M spatial-frequency basis vectors by the frequency domain basis vectors in the M reference signal port-frequency domain basis vector pairs and the spatial domain basis vectors respectively associated with each reference signal port in the M reference signal port-frequency domain basis vector pairs determined in step 405b.

[0387] One spatial-frequency basis vector in the M spatial-frequency basis vectors is associated with one spatial domain basis vector and one frequency domain basis vector.

[0388] Step 405d, the network device determines N spatial-frequency joint vectors according to the M sets of first combination coefficients and the M spatial-frequency basis vectors.

[0389] The representation of the N spatial-frequency joint vectors can refer to the related description of formula 1.

[0390] Step 405e, the network device determines a precoding matrix according to the N spatial-frequency joint vectors and the N sets of second combination coefficients.

[0391] The precoding matrix can refer to the related description of formula 2.

[0392] Specifically, the network device receives the first indication information and the second indication information sent by the terminal device according to the long period (i.e. the first period). Then, the network device determines N spatial-frequency joint vectors according to the first indication information and the second indication information. The network device receives the third indication information sent by the terminal device according to the short period (i.e. the second period). The network device determines N sets of second combination coefficients according to the third indication information. The network device determines a precoding matrix according to the N spatial-frequency joint vectors and the N sets of second combination coefficients.

[0393] It should be noted that the technical solution of the present application is applicable to a single site scenario and also applicable to a multi-site cooperative scenario. A single site can be understood as a network device, and the terminal device communicates with the network device. Multi-site can be understood as multiple network devices, and in this scenario, multiple network devices cooperate with each other to achieve common communication with the terminal device. The PMI feedback process between the terminal device and each site can be similar to the process of the above-described embodiments. Figure 4

[0394] For example, as Figure 2 ​As shown, the network device 1, the network device 2 and the network device 3 cooperate with each other to realize the communication transmission with the terminal device 2. That is, the above-mentioned multi-site cooperation scenario. For the multi-site cooperation scenario, the terminal device can feed back the CSI corresponding to each site to one of the sites. One site can be understood as one network device. Further, for the multi-site cooperation scenario, the terminal device also needs to further reflect the relative information between the multi-site channels in the CSI reporting. For example, the terminal device respectively completes the channel measurement and CSI determination process according to the process described in the above embodiment for each site, and determines the relative information (such as amplitude information, phase information, etc.) between the multi-sites according to the equivalent channels between the multi-sites and the terminal device. The terminal device can report the CSI of one site and the relative information between the multi-sites with reference to the CSI.

[0395] There are multiple ways to report the relative information between the multi-sites, and the following introduces several possible implementation manners.

[0396] Manner one: the terminal device can report the relative information between the multi-sites as part of the CSI corresponding to each site to one of the sites.

[0397] Optionally, in the manner one, the relative information between the multi-sites is reflected in the second combination coefficients, and the second combination coefficients are not simply quantified and reported separately for each site, which will lose the relative information between the multi-site channels, but the second combination coefficients corresponding to the multi-sites are jointly quantified and reported to one of the sites. Correspondingly, one of the sites receives the CSI corresponding to the multi-sites sent by the terminal device.

[0398] In a possible implementation manner, the site can forward the CSI corresponding to the multi-sites to the corresponding sites, and each site determines the precoding matrix of the site according to the spatial domain basis vector matrix of the site and the CSI corresponding to the multi-sites.

[0399] In another possible implementation manner, after one of the sites receives the CSI corresponding to the multi-sites sent by the terminal device, the other sites send the spatial domain basis vector matrix corresponding to the sites to the site in advance, and the site determines the precoding matrix of each site in the multi-sites, and then sends the precoding matrix of the other sites to the corresponding sites.

[0400] The following takes the first network device and the second network device as an example to introduce the manner one.

[0401] A first network device generates a first precoded reference signal (CSI) based on a first spatial basis vector matrix. The first spatial basis vector matrix includes at least one first spatial basis vector, with one first spatial basis vector associated with a reference signal port, and different first spatial basis vectors associated with different reference signal ports. The first network device then sends the first CSI to a terminal device. Upon receiving the first CSI, the terminal device determines a first CSI based on it. The first CSI includes first indication information, second indication information, and fifth indication information. The first indication information indicates D1 pairs of first reference signal port-frequency domain basis vectors; the second indication information indicates D1 sets of first combination coefficients; the D1 pairs of first reference signal port-frequency domain basis vectors and the D1 sets of first combination coefficients are used to determine E1 first space-frequency joint vectors, where D1 and E1 are both integers greater than or equal to 1; the fifth indication information indicates E1 sets of third combination coefficients associated with the E1 first space-frequency joint vectors.

[0402] The second network device generates a second precoded reference signal based on a second spatial basis vector matrix. The second spatial basis vector matrix includes at least one second spatial basis vector, with one second spatial basis vector associated with a reference signal port, and different second spatial basis vectors associated with different reference signal ports. After receiving the second precoded reference signal, the terminal device determines a second CSI based on it. The second CSI includes third, fourth, and sixth indication information; the third indication information indicates D2 pairs of second reference signal port-frequency domain basis vectors, and the fourth indication information indicates D2 sets of second combination coefficients; the D2 pairs of second reference signal port-frequency domain basis vectors and the D2 sets of third combination coefficients are used to determine E2 second space-frequency joint vectors, where D2 and E2 are both integers greater than or equal to 1. The sixth indication information indicates the E2 sets of fourth combination coefficients associated with E1 first space-frequency joint vectors. The E1 sets of third combination coefficients and the E2 sets of fourth combination coefficients together indicate the inter-site relative information between the first and second network devices.

[0403] Then, the terminal device can send the first CSI and the second CSI to the first network device. The first network device can then determine the first precoding matrix corresponding to the first network device based on the first CSI, the second CSI, and the first spatial basis vector matrix.

[0404] In one possible implementation, the first network device can send the first CSI and the second CSI to the second network device. Then, the second network device determines the second precoding matrix corresponding to the second network device based on the first CSI, the second CSI, and the second spatial basis vector matrix.

[0405] In another possible implementation, the first network device can obtain a second spatial domain basis vector matrix, and determine a second precoding matrix corresponding to the second network device according to the second spatial domain basis vector matrix, the first CSI and the second CSI. Then the first network device sends seventh indication information to the second network device, where the seventh indication information is used to indicate the second precoding matrix. Therefore, the second network device can determine the second precoding matrix.

[0406] Optionally, if the multi-site further includes a third network device, the third network device generates a third precoding reference signal according to a third spatial domain basis vector matrix. The third spatial domain basis vector matrix includes at least one third spatial domain basis vector matrix, and one of the third spatial domain basis vectors is associated with one reference signal port. Different third spatial domain basis vectors in the third spatial domain basis vector matrix are associated with different reference signal ports.

[0407] Then, the terminal device determines a third CSI according to the third precoding reference signal. The third CSI includes eighth indication information, ninth indication information and tenth indication information. The eighth indication information is used to indicate D3 third reference signal port-frequency domain basis vector pairs, the ninth indication information is used to indicate D3 groups of fifth combination coefficients; the D3 third reference signal port-frequency domain basis vector pairs and the D3 groups of fifth combination coefficients are used to determine E3 third space-frequency joint vectors, and D3 and E3 are both integers greater than or equal to 1. The tenth indication information is used to indicate E3 groups of sixth combination coefficients associated with the E3 third space-frequency joint vectors. The E1 groups of third combination coefficients, the E2 groups of fourth combination coefficients and the E3 groups of sixth combination coefficients are used to indicate multi-site relative information between the first network device, the second network device and the third network device together. The multi-site relative information is determined with the first network device as a reference site.

[0408] The terminal device can send the first CSI, the second CSI and the third CSI to the first network device. Then the first network device can determine a first precoding matrix corresponding to the first network device according to the first CSI, the second CSI, the third CSI and the first spatial domain basis vector matrix.

[0409] In a possible implementation, the first network device sends the first CSI, the second CSI and the third CSI to the second network device and the third network device respectively.

[0410] In another possible implementation, the first network device acquires the second spatial domain basis vector matrix and the third spatial domain basis vector matrix. The first network device determines a second precoding matrix corresponding to the second network device according to the second spatial domain basis vector matrix, the first CSI, the second CSI and the third CSI, and indicates the second precoding matrix to the second network device. The first network device determines a third precoding matrix corresponding to the third network device according to the third spatial domain basis vector matrix, the first CSI, the second CSI and the third CSI, and indicates the third precoding matrix to the third network device.

[0411] In a second mode, the terminal device can report the inter-multiple-site relative information to one of the multiple sites as an additional report.

[0412] In the second mode, one of the multiple sites receives the CSI corresponding to each of the multiple sites and the inter-multiple-site relative information sent by the terminal device.

[0413] In a possible implementation, after one of the multiple sites receives the CSI corresponding to each of the multiple sites and the inter-multiple-site relative information sent by the terminal device, the site can forward the CSI corresponding to other sites and the inter-multiple-site relative information corresponding to other sites to the corresponding sites, and then each site determines a precoding matrix of the site according to a spatial domain basis vector matrix of the site and the CSI corresponding to the site and the inter-multiple-site relative information.

[0414] In another implementation, after one of the multiple sites receives the CSI corresponding to each of the multiple sites and the inter-multiple-site relative information sent by the terminal device, other sites send their respective spatial domain basis vector matrices to the site in advance, and the site determines the precoding matrix of each of the multiple sites and sends the precoding matrix of other sites to the corresponding sites.

[0415] The following describes the second mode by taking the first network device and the second network device as an example.

[0416] The first network device generates a first precoded reference signal according to a first spatial domain basis vector matrix. The first spatial domain basis vector matrix includes at least one first spatial domain basis vector, one first spatial domain basis vector in the first spatial domain basis vector matrix is associated with one reference signal port, and different first spatial domain basis vectors in the first spatial domain basis vector matrix are associated with different reference signal ports. Then, the first network device sends the first precoded reference signal to the terminal device. After receiving the first precoded reference signal, the terminal device determines a first CSI according to the first precoded reference signal. The first CSI includes first indication information and second indication information, the first indication information is used to indicate D1 first reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate D1 groups of first combination coefficients; the D1 first reference signal port-frequency domain basis vector pairs and the D1 groups of first combination coefficients are used to determine E1 first space-frequency joint vectors, and D1 and E1 are both integers greater than or equal to 1.

[0417] The second network device generates a second precoded reference signal according to a second spatial domain basis vector matrix. The second spatial domain basis vector matrix includes at least one second spatial domain basis vector, one second spatial domain basis vector in the second spatial domain basis vector matrix is associated with one reference signal port, and different second spatial domain basis vectors in the second spatial domain basis vector matrix are associated with different reference signal ports. After receiving the second precoded reference signal, the terminal device determines a second CSI according to the second precoded reference signal. The second CSI includes third indication information and fourth indication information, the third indication information is used to indicate D2 second reference signal port-frequency domain basis vector pairs, and the fourth indication information is used to indicate D2 groups of second combination coefficients; the D2 second reference signal port-frequency domain basis vector pairs and the D2 groups of third combination coefficients are used to determine E2 second space-frequency joint vectors, and D2 and E2 are both integers greater than or equal to 1. The terminal device determines multi-site inter-relative information between the first network device and the second network device according to the first precoded reference signal and the second precoded reference signal.

[0418] Optionally, the first CSI further includes fifth indication information, the fifth indication information is used to indicate E1 groups of third combination coefficients associated with the E1 first space-frequency joint vectors. The E1 first space-frequency joint vectors, the multi-site inter-relative information, and the E1 groups of third combination coefficients are used to determine a first precoding matrix corresponding to the first network device.

[0419] Optionally, the second CSI further includes sixth indication information, the sixth indication information is used to indicate E2 groups of fourth combination coefficients associated with the E2 second space-frequency joint vectors, the E2 second space-frequency joint vectors, the multi-site inter-relative information, and the E2 groups of fourth combination coefficients are used to determine a second precoding matrix corresponding to the second network device.

[0420] Then, the terminal device can send the first CSI, the second CSI, and the inter-site relative information to the first network device. The first network device can then determine its corresponding first precoding matrix based on the first CSI, the first spatial basis vector matrix, and the inter-site relative information.

[0421] In one possible implementation, the first network device can send the second CSI and the inter-site relative information to the second network device. Then, the second network device determines the second precoding matrix corresponding to the second network device based on the second CSI, the second spatial basis vector matrix, and the inter-site relative information.

[0422] In another possible implementation, the first network device can acquire a second spatial basis vector matrix and determine a second precoding matrix corresponding to the second network device based on the second spatial basis vector matrix, the second CSI, and the inter-site relative information. Then, the first network device sends a seventh indication message to the second network device, which indicates the second precoding matrix. Therefore, the second network device can determine the second precoding matrix.

[0423] Optionally, if the multi-site configuration also includes a third network device, the third network device generates a third precoded reference signal based on a third spatial basis vector matrix. This third spatial basis vector matrix includes at least one third spatial basis vector matrix, and one third spatial basis vector is associated with a reference signal port. Different third spatial basis vectors in the third spatial basis vector matrix are associated with different reference signal ports.

[0424] Then, the terminal device determines the third CSI based on the third precoded reference signal. The third CSI includes an eighth indication information and a ninth indication information. The eighth indication information indicates D3 pairs of third reference signal port-frequency domain basis vectors, and the ninth indication information indicates D3 sets of fifth combination coefficients. The D3 pairs of third reference signal port-frequency domain basis vectors and the D3 sets of fifth combination coefficients are used to determine E3 third space-frequency joint vectors, where D3 and E3 are both integers greater than or equal to 1.

[0425] Optionally, the third CSI also includes tenth indication information, which is used to indicate the sixth combination coefficient of the E3 group associated with the E3 third space-frequency joint vectors. The E3 third space-frequency joint vectors, the inter-site relative information, and the sixth combination coefficient of the E3 group are used to determine the third precoding matrix corresponding to the third network device.

[0426] The terminal device determines multi-site relative information between the first network device, the second network device and the third network device according to the first precoding reference signal, the second precoding reference signal and the third precoding reference signal. The multi-site relative information is determined with the first network device as a reference site. The terminal device can send the first CSI, the second CSI, the third CSI and the multi-site relative information to the first network device. Then the first network device can determine a first precoding matrix corresponding to the first network device according to the first CSI, the first spatial domain basis vector matrix and the multi-site relative information.

[0427] In a possible implementation, the first network device sends the second CSI and the multi-site relative information to the second network device, and sends the third CSI and the multi-site relative information to the third network device.

[0428] In another possible implementation, the first network device obtains a second spatial domain basis vector matrix and a third spatial domain basis vector matrix. The first network device determines a second precoding matrix corresponding to the second network device according to the second spatial domain basis vector matrix, the second CSI and the multi-site relative information, and indicates the second precoding matrix to the second network device. The first network device determines a third precoding matrix corresponding to the third network device according to the third spatial domain basis vector matrix, the third CSI and the multi-site relative information, and indicates the third precoding matrix to the third network device.

[0429] In the above technical solution, in a multi-site cooperation scenario, each site can obtain a respective precoding matrix, thereby enabling multiple network devices to perform multi-site cooperation transmission.

[0430] The present application also provides a communication device, please refer to Figure 7 , Figure 7 The structure diagram of the communication device provided by the embodiment of the present application. The communication device 700 can be used to execute Figure 4 the steps performed by the terminal device in the embodiment shown in the above method embodiment. For details, please refer to the related introduction of the above method embodiment.

[0431] The communication device 700 includes a transceiver module 701 and a processing module 702.

[0432] The transceiver module 701 is configured to receive a precoding reference signal from a network device.

[0433] The processing module 702 is configured to determine a CSI according to the precoding reference signal.

[0434] The transceiver module 701 is configured to send the CSI to the network device.

[0435] The precoded reference signal is obtained by precoding a reference signal according to a spatial domain basis vector matrix, the spatial domain basis vector matrix includes at least one spatial domain basis vector, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port, and different spatial domain basis vectors in the spatial domain basis vector matrix are associated with different reference signal ports; the CSI includes first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients; the M reference signal port-frequency domain basis vector pairs are used to indicate reference signal ports and frequency domain basis vectors selected by the communication device 700; and the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients are used to determine N space-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0436] In a possible implementation, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one group of first combination coefficients in the M groups of first combination coefficients is associated with one space-frequency basis vector in the M space-frequency basis vectors, and each space-frequency joint vector in the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0437] In another possible implementation, each group of first combination coefficients in the M groups of first combination coefficients includes N first combination coefficients, and one first combination coefficient in the N first combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0438] In another possible implementation, the CSI further includes third indication information, the third indication information is used to indicate N groups of second combination coefficients associated with the N space-frequency joint vectors, and the N space-frequency joint vectors and the N groups of second combination coefficients are used to determine a precoding matrix.

[0439] In another possible implementation, a transmission period of the first indication information and the second indication information is a first period, and a transmission period of the third indication information is a second period, and a length of the first period is greater than a length of the second period.

[0440] In another possible implementation, the length of the first period is 100 milliseconds (ms), 200 ms, or 300 ms, and the length of the second period is 5 ms, 10 ms, or 20 ms.

[0441] In another possible implementation, one group of second combination coefficients in the N groups of second combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0442] In another possible implementation, each group of second combination coefficients in the N groups of second combination coefficients includes R or 2×R second combination coefficients; and R is equal to a number N of receive antenna ports of the communication device 700. r; or R equals a value N of a rank corresponding to the precoding matrix RANK . N RANK is an integer greater than or equal to 1 and less than or equal to N r .

[0443] In another possible implementation, the processing module 702 is specifically configured to:

[0444] determine an equivalent channel between the communication apparatus 700 and the network device according to the precoding reference signal;

[0445] determine N reference signal port-frequency domain joint vectors according to the equivalent channel; wherein the N reference signal port-frequency domain joint vectors are projections of N spatial-frequency joint vectors on a spatial domain basis vector matrix;

[0446] determine M reference signal port-frequency domain basis vector pairs and M groups of first combination coefficients from the P reference signal port-frequency domain basis vector pairs according to the N reference signal port-frequency domain joint vectors, P equals a number N fbasis of frequency domain basis vectors multiplied by a number K of reference signal ports, N fbasis is less than or equal to a number of frequency domain units, and K is less than or equal to a number of transmit antenna ports of the network device.

[0447] In another possible implementation, the processing module 702 is specifically configured to:

[0448] project vector components corresponding to reference signal ports of each of the N reference signal port-frequency domain joint vectors on the frequency domain basis vector matrix to obtain N first combination coefficient matrices, each of the N first combination coefficient matrices includes P first combination coefficients, one of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs, and the frequency domain basis vector matrix includes N fbasis frequency domain basis vectors.

[0449] determine the M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs according to the N first combination coefficient matrices;

[0450] determine the M groups of first combination coefficients as first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs.

[0451] In another possible implementation, the processing module 702 is further configured to:

[0452] project the equivalent channel on the N reference signal port-frequency domain joint vectors to obtain N groups of second combination coefficients, and the N spatial-frequency joint vectors and the N groups of second combination coefficients are used to determine the precoding matrix.

[0453] The application also provides another communication device, please refer to Figure 8 , Figure 8 The structural diagram of the communication device provided by the embodiment of the application. The communication device 800 can be used to execute the steps performed by the network device in the embodiment shown in the figure, please refer to the related introduction of the above method embodiment. Figure 4

[0454] The communication device 800 includes a transceiver module 801 and a processing module 802.

[0455] The processing module 802 is configured to perform precoding processing on the reference signals according to the spatial domain basis vector matrix to obtain precoded reference signals, the spatial domain basis vector matrix includes at least one spatial domain basis vector, one spatial domain basis vector in the spatial domain basis vector matrix is associated with one reference signal port, and different spatial domain basis vectors in the spatial domain basis vector matrix are associated with different reference signal ports.

[0456] The transceiver module 801 is configured to send the precoded reference signals to the terminal device and receive the CSI sent by the terminal device.

[0457] The CSI is determined by the terminal device according to the received precoded reference signals; the CSI includes first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, and the second indication information is used to indicate M groups of first combination coefficients; the M reference signal port-frequency domain basis vector pairs are used to indicate the reference signal ports and the frequency domain basis vectors selected by the terminal device; the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients are used to determine N space-frequency joint vectors, and M and N are both integers greater than or equal to 1.

[0458] In a possible implementation manner, the M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors; one group of first combination coefficients in the M groups of first combination coefficients is associated with one space-frequency basis vector in the M space-frequency basis vectors, and each space-frequency joint vector in the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M groups of first combination coefficients.

[0459] In another possible implementation manner, each group of first combination coefficients in the M groups of first combination coefficients includes N first combination coefficients, and one first combination coefficient in the N first combination coefficients is associated with one space-frequency joint vector in the N space-frequency joint vectors.

[0460] In another possible implementation manner, the CSI further includes third indication information, the third indication information is used to indicate N groups of second combination coefficients associated with the N space-frequency joint vectors, and the N space-frequency joint vectors and the N groups of second combination coefficients are used to determine a precoding matrix.

[0461] ​In a possible implementation, the first indication information and the second indication information are transmitted in a first period, and the third indication information is transmitted in a second period, and a length of the first period is greater than a length of the second period.

[0462] In a possible implementation, the length of the first period is 100 milliseconds (ms), 200 ms, or 300 ms, and the length of the second period is 5 ms, 10 ms, or 20 ms.

[0463] In a possible implementation, each of the N groups of second combination coefficients includes R or 2xR second combination coefficients.

[0464] In a possible implementation, each of the N groups of second combination coefficients includes R or 2xR second combination coefficients.

[0465] R is equal to a number N of receive antenna ports of the terminal device r , or R is equal to a value N of a rank corresponding to the precoding matrix RANK , N RANK is an integer greater than or equal to 1 and less than or equal to N r .

[0466] In a possible implementation, the processing module 802 is further configured to:

[0467] determine the precoding matrix according to the CSI and the spatial domain basis vector matrix.

[0468] In a possible implementation, the processing module 802 is specifically configured to:

[0469] determine the M reference signal port-frequency domain basis vector pairs according to the first indication information;

[0470] determine the spatial domain basis vectors respectively associated with the reference signal ports in the M reference signal port-frequency domain basis vector pairs according to the spatial domain basis vector matrix;

[0471] determine the M spatial frequency basis vectors according to the frequency domain basis vectors in the M reference signal port-frequency domain basis vector pairs and the spatial domain basis vectors respectively associated with the reference signal ports in the M reference signal port-frequency domain basis vector pairs, each of the M spatial frequency basis vectors being associated with a spatial domain basis vector and a frequency domain basis vector;

[0472] determine the N spatial frequency joint vectors according to the M groups of first combination coefficients and the M spatial frequency basis vectors;

[0473] determine the precoding matrix according to the N spatial frequency joint vectors and the N groups of second combination coefficients.

[0474] In another possible implementation manner, the processing module 802 is further configured to:

[0475] The spatial domain basis vector matrix is determined according to a dimension of a transmitting antenna port of the communication apparatus 800 and / or a form of the transmitting antenna port, the dimension of the transmitting antenna port is used to represent a number of transmitting antenna ports in a horizontal direction and a number of transmitting antenna ports in a vertical direction of the communication apparatus 800 respectively, and the form of the transmitting antenna port is determined according to a form of a transmitting antenna array surface of the communication apparatus 800.

[0476] In another possible implementation manner, the spatial domain basis vector matrix is represented as

[0477] wherein Q 11 is a first diagonal sub-block matrix, and Q 22 is a second diagonal sub-block matrix, the first diagonal sub-block matrix corresponds to a first antenna panel in each polarization direction of the communication apparatus 800, the second diagonal sub-block matrix corresponds to a second antenna panel in each polarization direction of the communication apparatus 800, a dimension of the first diagonal sub-block matrix is determined according to a dimension of a transmitting antenna port in each polarization direction of the first antenna panel, a dimension of the second diagonal sub-block matrix is determined according to a dimension of a transmitting antenna port in each polarization direction of the second antenna panel, and the first antenna panel and the second antenna panel are not in the same plane.

[0478] Figure 9 A simplified structural schematic diagram of a terminal device is shown. In order to facilitate understanding and illustration, Figure 9 In the figure, the terminal device takes a mobile phone as an example. As Figure 9 shown, the terminal device includes a processor, a memory, a radio frequency circuit, an antenna, and an input / output device.

[0479] The processor is mainly used for processing a communication protocol and communication data, controlling the terminal device, executing a software program, processing data of the software program, and the like.

[0480] The memory is mainly used for storing a software program and data.

[0481] The radio frequency circuit is mainly used for conversion between a baseband signal and a radio frequency signal and processing of the radio frequency signal.

[0482] The antenna is mainly used for receiving and transmitting a radio frequency signal in the form of an electromagnetic wave.

[0483] The input / output device, for example, a touch screen, a display screen, a keyboard, and the like, is mainly used for receiving data input by a user and outputting data to the user.

[0484] It should be noted that some kinds of terminal devices can not have the input / output device.

[0485] When data needs to be sent, the processor performs baseband processing on the data to be sent, and outputs a baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal, and sends the radio frequency signal in the form of an electromagnetic wave through an antenna. When data is sent to the terminal device, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data.

[0486] For ease of illustration, Figure 9 Only one memory and one processor are shown in the terminal device. In actual terminal device products, there can be one or more processors and one or more memories. The memory can also be referred to as a storage medium or a storage device, etc. The memory can be independent of the processor or integrated with the processor. The embodiments of the present application do not limit this.

[0487] In the embodiments of the present application, the antenna and the radio frequency circuit with transceiving functions can be regarded as a transceiving unit of the terminal device, and the processor with processing functions can be regarded as a processing unit of the terminal device.

[0488] As shown in Figure 9 , the terminal device includes a transceiving unit 910 and a processing unit 920. The transceiving unit can also be referred to as a transceiver, a transceiver, a transceiver, etc. The processing unit can also be referred to as a processor, a processing board, a processing module, a processing device, etc.

[0489] Optionally, the devices for implementing the receiving function in the transceiving unit 910 can be regarded as a receiving unit, and the devices for implementing the sending function in the transceiving unit 910 can be regarded as a sending unit, that is, the transceiving unit 910 includes a receiving unit and a sending unit. The transceiving unit can also be referred to as a transceiver, a transceiver, or a transceiver circuit, etc. The receiving unit can also be referred to as a receiver, a receiver, or a receiving circuit, etc. The sending unit can also be referred to as a transmitter, a transmitter, or a transmitting circuit, etc.

[0490] It should be understood that the transceiving unit 910 is used to perform the sending operation and the receiving operation of the terminal device in the above-mentioned method embodiments, and the processing unit 920 is used to perform other operations of the terminal device in the above-mentioned method embodiments, in addition to the transceiving operation.

[0491] When the terminal device is a chip, the chip includes a transceiving unit and a processing unit. The transceiving unit can be an input / output circuit or a communication interface; the processing unit is a processor or a microprocessor integrated on the chip or an integrated circuit or a logic circuit.

[0492] The present application also provides a network device. Please refer to Figure 10 , Figure 10Figure 1 is a structural schematic diagram of a network device 1000 provided by an embodiment of the present application. The network device 1000 can be applied to a system as shown in Figure 1 or Figure 2 , for example, the network device 1000 can be a network device in the system shown in Figure 1 or Figure 2 , to perform the functions of the network device in the above method embodiments. It should be understood that the following is only an example, and in future communication systems, the network device can have other forms and structures.

[0493] For example, in a 5G communication system, the network device 1000 can include a CU, a DU and an AAU. Compared with the network device in the LTE communication system, which is composed of one or more radio frequency units such as RRU and one or more BBUs:

[0494] The non-real-time part of the original BBU is split out and redefined as a CU, responsible for processing non-real-time protocols and services, part of the physical layer processing function of the BBU is combined with the original RRU and passive antenna into an AAU, and the remaining function of the BBU is redefined as a DU, responsible for processing physical layer protocols and real-time services. In short, the CU and the DU are distinguished by the real-time nature of the processing content, and the AAU is a combination of the RRU and the antenna.

[0495] The CU, DU and AAU can be separated or combined, so there are many network deployment forms. One possible deployment form is consistent with the traditional 4G network device, as shown in Figure 10 , the CU and the DU are deployed in the same hardware. It should be understood that Figure 10 is only an example and does not limit the scope of protection of the present application. For example, the deployment form can also be that the DU is deployed in the BBU machine room, the CU is centrally deployed or the DU is centrally deployed, and the CU is more centrally deployed.

[0496] The AAU 1100 can implement a transceiving function, referred to as a transceiving unit 1100, corresponding to the transceiving module 801 in Figure 8 . Alternatively, the transceiving unit 1100 can also be referred to as a transceiver, a transceiving circuit or a transceiver, which can include at least one antenna 1101 and a radio frequency unit 1102. Alternatively, the transceiving unit 1100 can include a receiving unit and a sending unit, the receiving unit can correspond to a receiver (or receiver, receiving circuit), and the sending unit can correspond to a transmitter (or transmitter, transmitting circuit). The CU and the DU 1200 can implement internal processing functions, referred to as processing units 1200, corresponding to the processing module 802 in Figure 8 . Alternatively, the processing unit 1200 can control the network device and the like, and can be referred to as a controller. The AAU, CU and DU can be physically arranged together or physically separated.

[0497] In addition, the network device is not limited to Figure 10 the illustrated form, and can be other forms: for example, including a BBU and an adaptive radio unit (ARU), or including a BBU and an AAU; can also be customer premises equipment (CPE), and can also be other forms, which are not limited by the present application.

[0498] In one example, the processing unit 1200 can be composed of one or more single boards, and the multiple single boards can jointly support a wireless access network of a single access mode (such as an LTE network), or can separately support wireless access networks of different access modes (such as an LTE network, a 5G network, a future network, or other networks). The CU and the DU 1200 further include a memory 1201 and a processor 1202. The memory 1201 is used to store necessary instructions and data. The processor 1202 is used to control the network device to perform necessary actions, for example, to control the network device to perform the operation processes of the network device in the above method embodiments. The memory 1201 and the processor 1202 can serve one or more single boards. That is, the memory and the processor can be separately arranged on each single board. Alternatively, the multiple single boards can share the same memory and processor. In addition, necessary circuits can also be arranged on each single board.

[0499] It should be understood that Figure 10 the network device 1000 illustrated can implement the network device functions involved in the method embodiments Figure 4 . The operations and / or functions of the various units in the network device 1000 are respectively used to implement the corresponding processes performed by the network device in the method embodiments of the present application. To avoid repetition, the detailed description is appropriately omitted here. Figure 10 The structure of the example network device is only one possible form, and should not constitute any limitation on the embodiments of the present application. The present application does not exclude the possibility of other forms of network device structures that may appear in the future.

[0500] The above CU and DU 1200 can be used to perform the actions implemented internally by the network device described in the preceding method embodiments, and the AAU 1100 can be used to perform the actions of sending or receiving by the network device to or from the terminal device described in the preceding method embodiments. For details, see the description in the preceding method embodiments, which will not be described here.

[0501] The embodiments of the present application also provide a communication system, which includes a terminal device and a network device. The terminal device is used to perform all or part of the steps of the terminal device in the embodiments described above. The network device is used to perform Figure 4 the network device functions involved in the method embodiments Figure 4all or part of the steps performed by the network device in the illustrated embodiment.

[0502] The embodiments of the present application further provide a computer program product comprising instructions which, when executed on a computer, cause the computer to carry out the method of any one of the above-mentioned Figure 4 embodiments.

[0503] The embodiments of the present application further provide a computer readable storage medium comprising computer instructions which, when executed on a computer, cause the computer to carry out the method of any one of the above-mentioned Figure 4 embodiments.

[0504] The embodiments of the present application further provide a chip device comprising a processor configured to be connected to a memory and to invoke a program stored in the memory to cause the processor to carry out the method of any one of the above-mentioned Figure 4 embodiments.

[0505] The processor mentioned in any one of the above embodiments can be a general central processing unit, a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling execution of the program of the method of any one of the above-mentioned Figure 4 embodiments. The memory mentioned in any one of the above embodiments can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM), etc.

[0506] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-mentioned system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0507] In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic. The division of the units is only a logical function division. There can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0508] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0509] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0510] The integrated unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, the part of the technical solutions of the present application that essentially contributes or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a ROM, a RAM, a magnetic disk or an optical disk, and various program code storage media.

[0511] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for feedback of channel state information, characterized in that, The method includes: The terminal device receives a precoded reference signal from the network device; The terminal device determines Channel State Information (CSI) based on the precoded reference signal; and The terminal device sends the CSI to the network device; The precoded reference signal is obtained by precoding the reference signal based on a spatial basis vector matrix. The spatial basis vector matrix includes at least one spatial basis vector, and one spatial basis vector in the spatial basis vector matrix is ​​associated with a reference signal port. Different spatial basis vectors in the spatial basis vector matrix are associated with different reference signal ports. The CSI includes first indication information and second indication information. The first indication information is used to indicate M reference signal port-frequency basis vector pairs, and the second indication information is used to indicate M sets of first combination coefficients. The M reference signal port-frequency basis vector pairs are used to indicate the reference signal port and frequency basis vector selected by the terminal device. The M reference signal port-frequency basis vector pairs and the M sets of first combination coefficients are used to determine N space-frequency joint vectors, where M and N are both integers greater than or equal to 1.

2. The method according to claim 1, characterized in that, The M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors. One set of first combination coefficients in the M sets of first combination coefficients is associated with one of the space-frequency basis vectors in the M space-frequency basis vectors. Each of the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M sets of first combination coefficients.

3. The method according to claim 1 or 2, characterized in that, Each of the M groups of first combination coefficients includes N first combination coefficients, and one of the N first combination coefficients is associated with one of the N space-frequency joint vectors.

4. The method according to claim 1 or 2, characterized in that, The CSI also includes third indication information, which indicates N sets of second combination coefficients associated with the N space-frequency joint vectors, and the N sets of second combination coefficients are used to determine the precoding matrix.

5. The method according to claim 4, characterized in that, The first indication information and the second indication information are respectively sent in a first period, and the third indication information is sent in a second period. The duration of the first period is greater than the duration of the second period.

6. The method according to claim 5, characterized in that, The duration of the first period is 100 milliseconds (ms), 200 ms, or 300 ms; the duration of the second period is 5 ms, 10 ms, or 20 ms.

7. The method according to claim 4, characterized in that, One set of the N sets of second combination coefficients is associated with one of the N space-frequency joint vectors.

8. The method according to claim 4, characterized in that, Each of the N groups of second combination coefficients contains R or 2×R second combination coefficients; wherein the R is equal to a number N of receive antenna ports of the terminal device r ; or the R is equal to a value N of a rank corresponding to the precoding matrix RANK , the N r is an integer greater than or equal to 1, and the N RANK is an integer greater than or equal to 1 and less than or equal to the N r .

9. The method according to claim 1 or 2, characterized in that, The terminal device determines the Channel State Information (CSI) based on the precoding reference signal, including: The terminal device determines the equivalent channel between the terminal device and the network device based on the precoded reference signal; The terminal device determines N reference signal port-frequency domain joint vectors based on the equivalent channel; wherein, the N reference signal port-frequency domain joint vectors are projections of the N space-frequency joint vectors onto the spatial basis vector matrix; The terminal device determines the M reference signal port-frequency domain basis vector pairs and the M groups of first combination coefficients from P reference signal port-frequency domain basis vector pairs according to the N reference signal port-frequency domain joint vectors, where P is equal to the number N of frequency domain basis vectors fbasis multiplied by the reference signal port number K, where N fbasis is less than or equal to the number of frequency domain units, and K is less than or equal to the number of transmission antenna ports of the network device.

10. The method according to claim 9, characterized in that, The terminal device determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients from the P reference signal port-frequency domain basis vector pairs based on the N reference signal port-frequency domain joint vectors, including: The terminal device projects a vector component corresponding to a reference signal port of each of the N reference signal port-frequency domain joint vectors on a frequency domain basis vector matrix to obtain N first combination coefficient matrices, each of the N first combination coefficient matrices including P first combination coefficients, one of the P first combination coefficients being associated with one of the P reference signal port-frequency domain basis vector pairs, the frequency domain basis vector matrix including N fbasis frequency domain basis vectors. The terminal device determines the M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs based on the N first combination coefficient matrices; The terminal device determines the first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs as the M sets of first combination coefficients.

11. The method according to claim 10, characterized in that, The method further includes: The terminal device projects the equivalent channel onto the N reference signal port-frequency domain joint vectors to obtain N sets of second combination coefficients. The N space-frequency joint vectors and the N sets of second combination coefficients are used to determine the precoding matrix.

12. The method according to claim 1 or 2, characterized in that, The spatial basis vector matrix is ​​represented as follows in each polarization direction: ; Among them, the For the first diagonal sub-block matrix, the The first diagonal sub-block matrix corresponds to the first antenna panel in each polarization direction of the network device, and the second diagonal sub-block matrix corresponds to the second antenna panel in each polarization direction of the network device. The dimension of the first diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the first antenna panel, and the dimension of the second diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the second antenna panel. The first antenna panel and the second antenna panel are not on the same plane.

13. A method for feedback of channel state information, characterized in that, The method includes: The network device precodes the reference signal based on the spatial basis vector matrix to obtain a precoded reference signal. The spatial basis vector matrix includes at least one spatial basis vector. One spatial basis vector in the spatial basis vector matrix is ​​associated with one reference signal port. Different spatial basis vectors in the spatial basis vector matrix are associated with different reference signal ports. The network device sends the precoded reference signal to the terminal device; The network device receives Channel State Information (CSI) sent from the terminal device; Wherein, the CSI is determined by the terminal device based on the received precoded reference signal; the CSI includes first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, the second indication information is used to indicate M sets of first combination coefficients, the M reference signal port-frequency domain basis vector pairs are used to indicate the reference signal port and frequency domain basis vector selected by the terminal device; the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients are used to determine N space-frequency joint vectors, where M and N are both integers greater than or equal to 1.

14. The method according to claim 13, characterized in that, The M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors. One set of first combination coefficients in the M sets of first combination coefficients is associated with one of the space-frequency basis vectors in the M space-frequency basis vectors. Each of the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M sets of first combination coefficients.

15. The method according to claim 13 or 14, characterized in that, Each of the M groups of first combination coefficients includes N first combination coefficients, and one of the N first combination coefficients is associated with one of the N space-frequency joint vectors.

16. The method according to claim 13 or 14, characterized in that, The CSI also includes third indication information, which indicates N sets of second combination coefficients associated with the N space-frequency joint vectors, and the N sets of second combination coefficients are used to determine the precoding matrix.

17. The method according to claim 16, characterized in that, The transmission period of the first indication information and the second indication information is a first period, and the transmission period of the third indication information is a second period, wherein the duration of the first period is greater than the duration of the second period.

18. The method according to claim 17, characterized in that, The duration of the first period is 100 milliseconds (ms), 200 ms, or 300 ms; the duration of the second period is 5 ms, 10 ms, or 20 ms.

19. The method according to claim 16, characterized in that, One set of the N sets of second combination coefficients is associated with one of the N space-frequency joint vectors.

20. The method according to claim 16, characterized in that, Each of the N groups of second combination coefficients contains R or 2×R second combination coefficients; wherein the R is equal to a number N of receive antenna ports of the terminal device r ; or the R is equal to a value N of a rank corresponding to the precoding matrix RANK , the N r is an integer greater than or equal to 1, and the N RANK is an integer greater than or equal to 1 and less than or equal to the N r .

21. The method according to claim 13 or 14, characterized in that, The terminal device determines the Channel State Information (CSI) based on the precoding reference signal, including: The terminal device determines the equivalent channel between the terminal device and the network device based on the precoded reference signal; The terminal device determines N reference signal port-frequency domain joint vectors based on the equivalent channel; wherein, the N reference signal port-frequency domain joint vectors are projections of the N space-frequency joint vectors onto the spatial basis vector matrix; The terminal device determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients from the P reference signal port-frequency domain basis vector pairs based on the N reference signal port-frequency domain joint vectors, where P is equal to the number of frequency domain basis vectors N. fbasis Multiply by the number of reference signal ports K, the N fbasis The number of frequency domain units is less than or equal to the number of transmit antenna ports of the network device.

22. The method according to claim 21, characterized in that, The terminal device determines the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients from the P reference signal port-frequency domain basis vector pairs based on the N reference signal port-frequency domain joint vectors, including: The terminal device projects the vector components corresponding to the reference signal ports of each of the N reference signal port-frequency domain joint vectors onto a frequency domain basis vector matrix to obtain N first combination coefficient matrices. Each of the N first combination coefficient matrices includes P first combination coefficients, and one of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs. The frequency domain basis vector matrix includes N fbasis One frequency domain basis vector; The terminal device determines the M reference signal port-frequency domain basis vector pairs from the P reference signal port-frequency domain basis vector pairs based on the N first combination coefficient matrices; The terminal device determines the first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs as the M sets of first combination coefficients.

23. The method according to claim 22, characterized in that, The method further includes: The terminal device projects the equivalent channel onto the N reference signal port-frequency domain joint vectors to obtain N sets of second combination coefficients. The N space-frequency joint vectors and the N sets of second combination coefficients are used to determine the precoding matrix.

24. The method according to claim 13 or 14, characterized in that, The method further includes: The network device determines the precoding matrix based on the CSI and the spatial basis vector matrix.

25. The method according to claim 24, characterized in that, The network device determines the precoding matrix based on the CSI and the spatial basis vector matrix, including: The network device determines the M reference signal port-frequency domain basis vector pairs according to the first indication information; The network device determines the spatial basis vector associated with each reference signal port in the M reference signal port-frequency basis vector pairs based on the spatial basis vector matrix. The network device determines M space-frequency basis vectors through the frequency domain basis vectors in the M reference signal port-frequency domain basis vector pairs and the spatial basis vectors associated with each reference signal port in the M reference signal port-frequency domain basis vector pairs respectively. Each of the M space-frequency basis vectors is associated with a spatial basis vector and a frequency domain basis vector. The network device determines the N joint space-frequency vectors based on the M sets of first combination coefficients and the M space-frequency basis vectors; The network device determines the precoding matrix based on the N space-frequency joint vectors and N sets of second combination coefficients, wherein the N sets of second combination coefficients are associated with the N space-frequency joint vectors.

26. The method according to claim 13 or 14, characterized in that, The method further includes: The network device determines the spatial basis vector matrix based on the dimension and / or shape of the transmit antenna port of the network device. The dimension of the transmit antenna port is used to characterize the number of transmit antenna ports in the horizontal direction and the number of transmit antenna ports in the vertical direction of the network device, respectively. The shape of the transmit antenna port is determined based on the shape of the transmit antenna array of the network device.

27. The method according to claim 13 or 14, characterized in that, The spatial basis vector matrix is ​​represented as follows in each polarization direction: ; Among them, the For the first diagonal sub-block matrix, the The first diagonal sub-block matrix corresponds to the first antenna panel in each polarization direction of the network device, and the second diagonal sub-block matrix corresponds to the second antenna panel in each polarization direction of the network device. The dimension of the first diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the first antenna panel, and the dimension of the second diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the second antenna panel. The first antenna panel and the second antenna panel are not on the same plane.

28. A first communication device, characterized in that, The first communication device includes: The transceiver module is used to receive precoded reference signals from network devices; The processing module is used to determine Channel State Information (CSI) based on the precoding reference signal; and The transceiver module is also used to send the CSI to the network device; The precoded reference signal is obtained by precoding a reference signal based on a spatial basis vector matrix. The spatial basis vector matrix includes at least one spatial basis vector, and one spatial basis vector in the spatial basis vector matrix is ​​associated with a reference signal port. Different spatial basis vectors in the spatial basis vector matrix are associated with different reference signal ports. The CSI includes first indication information and second indication information. The first indication information is used to indicate M reference signal port-frequency basis vector pairs, and the second indication information is used to indicate M sets of first combination coefficients. The M reference signal port-frequency basis vector pairs are used to indicate the reference signal port and frequency basis vector selected by the first communication device. The M reference signal port-frequency basis vector pairs and the M sets of first combination coefficients are used to determine N space-frequency joint vectors, where M and N are both integers greater than or equal to 1.

29. The first communication device according to claim 28, characterized in that, The M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors. One set of first combination coefficients in the M sets of first combination coefficients is associated with one of the space-frequency basis vectors in the M space-frequency basis vectors. Each of the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M sets of first combination coefficients.

30. The first communication device according to claim 28 or 29, characterized in that, Each of the M groups of first combination coefficients includes N first combination coefficients, and one of the N first combination coefficients is associated with one of the N space-frequency joint vectors.

31. The first communication device according to claim 28 or 29, characterized in that, The CSI also includes third indication information, which indicates N sets of second combination coefficients associated with the N space-frequency joint vectors, and the N sets of second combination coefficients are used to determine the precoding matrix.

32. The first communication device according to claim 31, characterized in that, The first indication information and the second indication information are respectively sent in a first period, and the third indication information is sent in a second period. The duration of the first period is greater than the duration of the second period.

33. The first communication device according to claim 32, characterized in that, The duration of the first period is 100 milliseconds (ms), 200 ms, or 300 ms; the duration of the second period is 5 ms, 10 ms, or 20 ms.

34. The first communication device according to claim 32, characterized in that, One set of the N sets of second combination coefficients is associated with one of the N space-frequency joint vectors.

35. The first communication device according to claim 32, characterized in that, Each of the N groups of second combination coefficients contains R or 2×R second combination coefficients; Wherein, R is equal to the number N of the receiving antenna ports of the first communication device. r Alternatively, R is equal to the value N of the rank corresponding to the precoding matrix. RANK The N r N is an integer greater than or equal to 1. RANK It is greater than or equal to 1 and less than or equal to N. r Integers.

36. The first communication device according to claim 28 or 29, characterized in that, The processing module is specifically used for: The equivalent channel between the first communication device and the network device is determined based on the precoded reference signal; N reference signal port-frequency domain joint vectors are determined based on the equivalent channel; wherein, the N reference signal port-frequency domain joint vectors are the projections of the N space-frequency joint vectors onto the spatial basis vector matrix; Based on the N reference signal port-frequency domain joint vectors, the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients are determined from the P reference signal port-frequency domain basis vector pairs, where P is equal to the number of frequency domain basis vectors N. fbasis Multiply by the number of reference signal ports K, the N fbasis The number of frequency domain units is less than or equal to the number of transmit antenna ports of the network device.

37. The first communication device according to claim 36, characterized in that, The processing module is specifically used for: Projecting the vector components corresponding to the reference signal ports of each of the N reference signal port-frequency domain joint vectors onto the frequency domain basis vector matrix yields N first combination coefficient matrices. Each of the N first combination coefficient matrices includes P first combination coefficients, and one of the P first combination coefficients is associated with one of the P reference signal port-frequency domain basis vector pairs. The frequency domain basis vector matrix includes N fbasis One frequency domain basis vector; The M reference signal port-frequency domain basis vector pairs are determined from the P reference signal port-frequency domain basis vector pairs based on the N first combination coefficient matrices; The first combination coefficients associated with the M reference signal port-frequency domain basis vector pairs are determined as the M sets of first combination coefficients.

38. The first communication device according to claim 37, characterized in that, The processing module is also used for: The equivalent channel is projected onto the N reference signal port-frequency domain joint vectors to obtain N sets of second combination coefficients. The N space-frequency joint vectors and the N sets of second combination coefficients are used to determine the precoding matrix.

39. The first communication device according to claim 28 or 29, characterized in that, The spatial basis vector matrix is ​​represented as follows in each polarization direction: ; Among them, the For the first diagonal sub-block matrix, the The first diagonal sub-block matrix corresponds to the first antenna panel in each polarization direction of the network device, and the second diagonal sub-block matrix corresponds to the second antenna panel in each polarization direction of the network device. The dimension of the first diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the first antenna panel, and the dimension of the second diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the second antenna panel. The first antenna panel and the second antenna panel are not on the same plane.

40. A second communication device, characterized in that, The second communication device includes: The processing module is used to precode the reference signal according to the spatial basis vector matrix to obtain a precoded reference signal. The spatial basis vector matrix includes at least one spatial basis vector. One spatial basis vector in the spatial basis vector matrix is ​​associated with one reference signal port. Different spatial basis vectors in the spatial basis vector matrix are associated with different reference signal ports. The transceiver module is used to send the precoded reference signal to the terminal device and receive channel state information (CSI) sent from the terminal device. Wherein, the CSI is determined by the terminal device based on the received precoded reference signal; the CSI includes first indication information and second indication information; the first indication information is used to indicate M reference signal port-frequency domain basis vector pairs, the second indication information is used to indicate M sets of first combination coefficients, the M reference signal port-frequency domain basis vector pairs are used to indicate the reference signal port and frequency domain basis vector selected by the terminal device; the M reference signal port-frequency domain basis vector pairs and the M sets of first combination coefficients are used to determine N space-frequency joint vectors, where M and N are both integers greater than or equal to 1.

41. The second communication device according to claim 40, characterized in that, The M reference signal port-frequency domain basis vector pairs correspond to M space-frequency basis vectors. One set of first combination coefficients in the M sets of first combination coefficients is associated with one of the space-frequency basis vectors in the M space-frequency basis vectors. Each of the N space-frequency joint vectors includes a linear combination of the M space-frequency basis vectors based on the M sets of first combination coefficients.

42. The second communication device according to claim 40 or 41, characterized in that, Each of the M groups of first combination coefficients includes N first combination coefficients, and one of the N first combination coefficients is associated with one of the N space-frequency joint vectors.

43. The second communication device according to claim 40 or 41, characterized in that, The CSI also includes third indication information, which indicates N sets of second combination coefficients associated with the N space-frequency joint vectors, and the N sets of second combination coefficients are used to determine the precoding matrix.

44. The second communication device according to claim 43, characterized in that, The first indication information and the second indication information are respectively sent in a first period, and the third indication information is sent in a second period. The duration of the first period is greater than the duration of the second period.

45. The second communication device according to claim 44, characterized in that, The duration of the first period is 100 milliseconds (ms), 200 ms, or 300 ms; the duration of the second period is 5 ms, 10 ms, or 20 ms.

46. ​​The second communication device according to claim 43, characterized in that, One set of the N sets of second combination coefficients is associated with one of the N space-frequency joint vectors.

47. The second communication device according to claim 43, characterized in that, Each of the N groups of second combination coefficients contains R or 2×R second combination coefficients; Wherein, R is equal to the number N of the receiving antenna ports of the terminal device. r Alternatively, R is equal to the value N of the rank corresponding to the precoding matrix. RANK The N r N is an integer greater than or equal to 1. RANK It is greater than or equal to 1 and less than or equal to N. r Integers.

48. The second communication device according to claim 40 or 41, characterized in that, The processing module is also used for: The precoding matrix is ​​determined based on the CSI and the spatial basis vector matrix.

49. The second communication device according to claim 48, characterized in that, The processing module is specifically used for: The M reference signal port-frequency domain basis vector pairs are determined based on the first indication information; Based on the spatial basis vector matrix, determine the spatial basis vector associated with each reference signal port in the M reference signal port-frequency basis vector pairs; M space-frequency basis vectors are determined by the frequency domain basis vectors in the M reference signal port-frequency domain basis vector pairs and the spatial basis vectors associated with each reference signal port in the M reference signal port-frequency domain basis vector pairs respectively. Each of the M space-frequency basis vectors is associated with a spatial basis vector and a frequency domain basis vector. The N joint space-frequency vectors are determined based on the M sets of first combination coefficients and the M space-frequency basis vectors; The precoding matrix is ​​determined based on the N space-frequency joint vectors and the N sets of second combination coefficients, wherein the N sets of second combination coefficients are associated with the N space-frequency joint vectors.

50. The second communication device according to claim 40 or 41, characterized in that, The processing module is also used for: The spatial basis vector matrix is ​​determined based on the dimension of the transmitting antenna port of the second communication device and / or the shape of the transmitting antenna port. The dimension of the transmitting antenna port is used to characterize the number of transmitting antenna ports of the second communication device in the horizontal direction and the number of transmitting antenna ports in the vertical direction, respectively. The shape of the transmitting antenna port is determined based on the shape of the transmitting antenna array of the second communication device.

51. The second communication device according to claim 40 or 41, characterized in that, The spatial basis vector matrix is ​​represented as follows in each polarization direction: ; Among them, the For the first diagonal sub-block matrix, the The first diagonal sub-block matrix corresponds to the first antenna panel in each polarization direction of the second communication device, and the second diagonal sub-block matrix corresponds to the second antenna panel in each polarization direction of the second communication device. The dimension of the first diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the first antenna panel, and the dimension of the second diagonal sub-block matrix is ​​determined based on the dimension of the transmit antenna port in each polarization direction of the second antenna panel. The first antenna panel and the second antenna panel are not on the same plane.

52. A communication device, characterized in that, The communication device includes a processor; The processor is configured to execute a computer program or computer instructions in memory to perform the method as described in any one of claims 1 to 12; or to perform the method as described in any one of claims 13 to 27.

53. The communication device according to claim 52, characterized in that, The communication device also includes the memory.

54. A computer-readable storage medium, characterized in that, It stores a computer program thereon, which, when executed by a communication device, causes the communication device to perform the method as described in any one of claims 1 to 12, or causes the communication device to perform the method as described in any one of claims 13 to 27.

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