Communication method and communication device

Abstract

The invention provides a communication method and a communication device, in the method, a first substrate is provided, and the first substrate is a region-level channel substrate provided by a channel map and can be used as prior information to be sent to a terminal, so that the overhead of a reference signal is reduced. Moreover, after the terminal performs channel measurement based on the reference signal, only the position index of the first substrate can be fed back, and information such as indexes and long-period coefficients of one or more base vectors forming the first substrate does not need to be fed back, so that the feedback overhead can be reduced.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a communication method and a communication device. Background Art

[0002] Currently, the solution for implementing channel reconstruction based on reference signals has problems of large reference signal resource overhead and large long-period base feedback overhead. For example, the codebook of the 3rd generation partnership project (3GPP) release 16 (R16) only utilizes the sparse characteristics of the channel in the angle-delay domain, and it is necessary to report the spatial domain, frequency domain bases, and combination coefficients, resulting in a relatively large feedback overhead. Another example is that the codebook of 3GPP release 18 (R18) further considers the sparse characteristics of the channel and the rule that different channel characteristics change at different speeds over time, and designs a codebook feedback method combining long and short periods to reduce the feedback overhead; however, as the number of antennas increases, the overhead of the reference signals to be configured increases sharply, and the feedback overhead also increases sharply. Summary of the Invention

[0003] A communication method and a communication device provided by this application can send the first base as prior information to the first device, which is beneficial to reducing the reference signal overhead. Moreover, the first device only feeds back the position index and short-period superposition coefficients at the first base, which is beneficial to reducing the feedback overhead.

[0004] In a first aspect, this application provides a communication method, which is executed by a first device. For example, the first device can be a terminal, or a component of a terminal (such as a processor, a chip, or a chip system, etc.), and can also be a logic module that can implement all or part of the terminal functions. Among them, the first device receives the indication information of the first base, and the indication information of the first base indicates the projection coefficient of the first base on the quantization base of the first base and the column index of the quantization base of the first base; after receiving the indication information of the first base, the first device can determine and record the first base. The first device receives the first reference signal and determines the first channel matrix based on the first reference signal. Further, the first device can determine the first superposition coefficient vector based on the second base constructed by the first channel matrix and the position index of the first reference signal in the spatial-frequency domain in the corresponding row of the first base. For example, assume that the dimension of the first channel matrix is M×N 1 *1, and the dimension of the second base is M×N 1 *L, where M is the number of antenna ports for receiving the first reference signal, and N 1 is the number of frequency domain units carrying the first reference signal. The first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L×1, and M and N 1is a positive integer, and L is less than or equal to MN 1 . The first device can select the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determine the position indices of the K superposition coefficient vectors in the first superposition coefficient vector to form a second basis selection vector. Further, the first device can send the second superposition coefficient vector and the second basis selection vector.

[0005] In this method, the first device can receive the indication information of the first basis and the first reference signal. The first reference signal can be a sparse reference signal, which is beneficial to reducing the overhead of the reference signal. And based on the indication information of the first basis, the first device can determine that the position index of the first reference signal in the space-frequency domain corresponds to the corresponding row of the first basis, so that the first device can calculate short-period coefficients (such as the second superposition coefficient vector) based on the channel estimation result of the sparse reference signal and report them, which is beneficial to reducing the feedback overhead.

[0006] In a possible implementation, the first device multiplies the second superposition coefficient vector by the third basis to obtain a second channel matrix; the third basis is composed of the corresponding columns of the K position indices in the second basis selection vector in the first basis.

[0007] In this method, the first device can determine the projection of the channel matrix based on the corresponding columns of the K position indices in the first basis, and the channel matrix can be recovered by combining the projection of the channel matrix with the short-period coefficients, which is beneficial to reducing the calculation overhead.

[0008] In a possible implementation, the first device performs channel estimation based on the second reference signal to obtain a third channel matrix. The second reference signal is the reference signal received before the first reference signal, and the second reference signal and the first reference signal are of the same type of reference signal. The first device determines a fourth basis based on the third channel matrix, determines the common subspace where the fourth basis intersects with the first basis as the first common subspace, and determines the subspace of the fourth basis excluding the first common subspace as the first non-common subspace. The first device sends the indication information of the first non-common subspace. The indication information of the first non-common subspace indicates the projection coefficients of the first non-common subspace on the quantization basis of the first non-common subspace and the column indices of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L 1 column basis vectors, and L 1 is a positive integer.

[0009] In this method, the first device may further perform channel estimation on a second reference signal (also referred to as a historical reference signal) to obtain a third channel matrix (also referred to as a historical channel matrix), so that the first device can determine the projection of the historical channel matrix. Further, the first device can determine a first non-common subspace, that is, the first non-common subspace is the non-common subspace of the projection of the historical channel matrix and the projection of the current channel matrix, which characterizes the difference between the projection of the historical channel matrix and the projection of the current channel matrix, thus facilitating the update of the first basis based on this difference and improving the accuracy of channel estimation.

[0010] In a possible implementation, the first device receives first indication information indicating the frequency-domain position for transmitting a third reference signal. The first device transmits the third reference signal based on the first indication information.

[0011] In this method, the first device may also receive first indication information of a third reference signal (such as an uplink reference signal), and thus transmit the third reference signal based on the indication of the first indication information, so that the receiving end of the third reference signal can perform channel estimation based on the third reference signal to recover channel state information.

[0012] In a second aspect, the present application provides a communication method, which is performed by a second device. For example, the second device may be a network device (such as a base station), or be performed by a component of the network device (such as a processor, a chip, or a chip system, etc.), and may also be a logic module capable of implementing all or part of the functions of the network device. Among them, the second device transmits indication information of a first basis, and the indication information of the first basis indicates the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis. The second device transmits a first reference signal, so that the receiving end of the first reference signal can perform channel estimation based on the first reference signal to obtain a first channel matrix, and the receiving end of the first reference signal can determine a first superposition coefficient vector based on the first channel matrix and the second basis constructed from the position index of the first reference signal in the spatial-frequency domain at the corresponding row of the first basis, and thus determine that the K superposition coefficient vectors with the largest amplitudes in the first superposition coefficient vector form a second superposition coefficient vector, and the position indices of the K superposition coefficient vectors in the first superposition coefficient vector form a second basis selection vector. The second device receives the second superposition coefficient vector and the second basis selection vector.

[0013] In this method, the second device can determine the first basis, and transmit the indication information of the first basis and the first reference signal. The first reference signal may be a sparse reference signal, which is beneficial to reducing the overhead of the reference signal. And the data volume of the second superposition coefficient vector and the second basis selection vector received by the second device is small, indicating a low feedback overhead. Further, the second device can recover the channel state information based on these two types of feedback and the first basis.

[0014] In a possible implementation, the second device multiplies the second superposition coefficient vector by the third basis to obtain a second channel matrix; the third basis is composed of the corresponding columns of the first basis at K position indices in the second basis selection vector.

[0015] In this method, the second device can determine the projection of the channel matrix based on the corresponding columns of the first basis at K position indices, and combine the projection of the channel matrix with the short-period coefficients to recover the channel matrix, which helps to reduce the computational overhead.

[0016] In a possible implementation, the second device receives indication information of a first non-common subspace, and the indication information of the first non-common subspace indicates the projection coefficients of the first non-common subspace on the quantization basis of the first non-common subspace and the column indices of the quantization basis of the first non-common subspace. The second device performs Schmidt orthogonalization on the first basis and the first non-common subspace to obtain a fifth basis, and sends indication information of the fifth basis. Wherein, the indication information of the fifth basis indicates the fifth basis, or indicates the projection coefficients of the fifth basis on the quantization basis of the fifth basis and the column indices of the quantization basis of the fifth basis.

[0017] In this method, when the first device determines the non-common subspace of the projection of the historical channel matrix and the projection of the current channel matrix, it can indicate this non-common subspace (i.e., the first non-common subspace) to the second device. The specific indication method includes only indicating the projection coefficients of the first non-common subspace and the column indices of the quantization basis, which helps to reduce the feedback overhead. Moreover, after the second device determines the first non-common subspace, it can also update the first basis based on the first non-common subspace to obtain a fifth basis, and subsequently use the fifth basis to quantize the channel matrix, which helps to improve the accuracy of recovering the channel state information. Optionally, the second device can also send indication information of the fifth basis to the core network device, which helps the core network device to update the basis information and update the channel map.

[0018] In a possible implementation, the second device sends first indication information, and the first indication information indicates the frequency domain position for sending a third reference signal. The second device receives the third reference signal.

[0019] In this method, the second device can also send the first indication information to indicate the first device to send the third reference signal, so that the channel state information can be recovered based on the third reference signal.

[0020] In a possible implementation, the second device determines a fourth channel matrix based on a third reference signal, and determines a third superimposed coefficient vector based on the fourth channel matrix and a sixth basis constructed from corresponding rows of a first basis at position indices of the third reference signal in the spatial-frequency domain. The second device determines that the F superimposed coefficients with the largest amplitudes in the third superimposed coefficient vector form a fourth superimposed coefficient vector, and determines position indices of the F superimposed coefficients in the third superimposed coefficient vector to form a fourth basis selection vector. The second device multiplies the fourth superimposed coefficient vector by a seventh basis, where the seventh basis is formed from corresponding columns of a fifth basis at K position indices in the fourth basis selection vector.

[0021] In this method, the second device can perform channel estimation and recovery of channel state information based on an uplink reference signal (such as SRS).

[0022] In a possible implementation, the second device sends a first request message to a core network device, where the first request message requests to obtain a channel map, or requests to obtain basis information corresponding to a first device in the channel map. The second device receives a first response message, where the first response message includes the channel map, or basis information corresponding to the first device in the channel map.

[0023] In this method, the second device can request a core network device to obtain a channel map, thereby obtaining basis information (such as a first basis) based on the channel map, and can send the basis information to the first device as prior information, which helps reduce the overhead of reference signals.

[0024] In a possible implementation, the second device performs channel estimation based on a fourth reference signal to obtain a plurality of sixth channel matrices, where the plurality of sixth channel matrices include channel state information in the spatial-frequency domain dimension. The fourth reference signal is a reference signal received before the third reference signal, and the fourth reference signal and the third reference signal are reference signals of the same type. The second device determines an eighth basis based on the plurality of sixth channel matrices.

[0025] In a possible implementation, the second device determines a second common subspace that is the intersection of the eighth basis and the first basis, and determines a second non-common subspace that is the subspace of the eighth basis excluding the second common subspace, where the second non-common subspace is used to update the fifth basis.

[0026] In the above method, the second device can generate a corresponding eighth basis based on information of a historical SRS signal, thereby obtaining difference information (such as a second non-common subspace) between the first basis and the information of the historical SRS signal, and thus updating the channel basis, which helps improve the reconstruction accuracy of channel state information.

[0027] In a possible implementation, the second device performs Schmidt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis. The second device determines the fifth superposition coefficient vector based on the corresponding rows of the fourth channel matrix and the spatial-frequency positions of the SRS signals in the ninth basis, and determines the sixth superposition coefficient vector and the sixth basis selection vector based on the fifth superposition coefficient vector. The second device multiplies the sixth superposition coefficient vector by the tenth basis to obtain the sixth channel matrix, thereby realizing the reconstruction of the channel state information.

[0028] In a third aspect, the present application provides a communication method, which is implemented by the interaction between a first device and a second device. For example, the first device may be a terminal, and the second device may be a network device. The communication method includes the following steps: The second device sends indication information of a first basis, and the indication information of the first basis indicates the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis; correspondingly, the first device receives the indication information of the first basis. The second device sends a first reference signal, and correspondingly, the first device receives the first reference signal and determines a first channel matrix based on the first reference signal. Further, the first device may determine a first superposition coefficient vector based on the first channel matrix and the position index of the first reference signal in the spatial-frequency domain in the corresponding rows of the first basis. The first device selects the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determines the position indexes of the K superposition coefficient vectors in the first superposition coefficient vector to form a second basis selection vector. The first device may send the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0029] In this method, the first device may receive the indication information of the first basis and the first reference signal, and the first reference signal may be a sparse reference signal, which is beneficial to reducing the overhead of the reference signal. And based on the indication information of the first basis, the first device can determine the position index of the first reference signal in the spatial-frequency domain in the corresponding rows of the first basis, so that the first device can calculate short-period coefficients (such as the second superposition coefficient vector) based on the channel estimation result of the sparse reference signal and report them, which is beneficial to reducing the feedback overhead. The data volume of the second superposition coefficient vector and the second basis selection vector received by the second device is small, indicating that the feedback overhead is low. Further, based on these two types of feedback and the first basis, the second device can restore the channel state information.

[0030] Optionally, other implementations in this communication method may refer to the corresponding descriptions in the first aspect and the second aspect, and will not be elaborated here.

[0031] Fourthly, the present application provides a communication device. The communication device may be a terminal, or a component of a terminal (such as a processor, a chip, or a chip system, etc.), or a device that can be used in combination with a terminal. In a possible implementation manner, the communication device may include a functional module, and the functional module may be a hardware circuit, software, or a combination of a hardware circuit and software.

[0032] In a possible implementation manner, the communication device includes a communication unit and a processing unit. The communication unit is configured to receive indication information of a first basis, where the indication information of the first basis indicates projection coefficients of the first basis on a quantization basis of the first basis and column indexes of the quantization basis of the first basis. The processing unit is configured to determine and record the first basis. The communication unit is further configured to receive a first reference signal, and the processing unit is further configured to determine a first channel matrix based on the first reference signal. The processing unit is further configured to determine a first superposition coefficient vector based on the first channel matrix and position indexes of the first reference signal in the spatial-frequency domain at corresponding rows of the first basis. The processing unit is further configured to select K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vector to form a second superposition coefficient vector, and determine position indexes of the K superposition coefficient vectors in the first superposition coefficient vector to form a second basis selection vector. The communication unit is further configured to send the second superposition coefficient vector and the second basis selection vector.

[0033] In a possible implementation manner, the processing unit is configured to multiply the second superposition coefficient vector by a third basis to obtain a second channel matrix; the third basis is composed of K position indexes in the second basis selection vector at corresponding columns of the first basis.

[0034] In a possible implementation manner, the processing unit is configured to perform channel estimation based on a second reference signal to obtain a third channel matrix, where the second reference signal is a reference signal received before the first reference signal, and the second reference signal and the first reference signal are reference signals of the same type. The processing unit is configured to determine a fourth basis based on the third channel matrix, determine a first common subspace where the fourth basis intersects with the first basis as a first common subspace, and determine a subspace of the fourth basis excluding the first common subspace as a first non-common subspace. The communication unit is configured to send indication information of the first non-common subspace, where the indication information of the first non-common subspace indicates projection coefficients of the first non-common subspace on a quantization basis of the first non-common subspace and column indexes of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L 1 column basis vectors, and L 1 is a positive integer.

[0035] In a possible implementation, the communication unit is configured to receive first indication information, where the first indication information indicates the frequency-domain position for transmitting a third reference signal. The processing unit is configured to transmit the third reference signal via the communication unit based on the first indication information.

[0036] In a fifth aspect, the present application provides a communication device. The communication device may be a network device, or a component of a network device (such as a processor, a chip, or a chip system, etc.), or a device capable of being used in conjunction with a network device. In a possible implementation, the communication device may include functional modules, and the functional modules may be hardware circuits, software, or a combination of hardware circuits and software.

[0037] In a possible implementation, the communication device includes a communication unit and a processing unit. Among them, the communication unit is configured to transmit indication information of a first basis, where the indication information of the first basis indicates the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis. The communication unit is further configured to transmit a first reference signal, so that the receiving end of the first reference signal can perform channel estimation based on the first reference signal to obtain a first channel matrix, and the receiving end of the first reference signal can determine a first superposition coefficient vector based on the first channel matrix and the second basis constructed from the position index of the first reference signal in the spatial-frequency domain in the corresponding row of the first basis, and then determine a second superposition coefficient vector formed by selecting the K superposition coefficient vectors with the largest magnitudes in the first superposition coefficient vector, and the position indexes of the K superposition coefficient vectors in the first superposition coefficient vector form a second basis selection vector. The communication unit is further configured to receive the second superposition coefficient vector and the second basis selection vector.

[0038] In a possible implementation, the processing unit is configured to multiply the second superposition coefficient vector by a third basis; the third basis is formed by the K position indexes in the second basis selection vector in the corresponding columns of the first basis.

[0039] In a possible implementation, the communication unit is configured to receive indication information of a first non-common subspace, where the indication information of the first non-common subspace indicates the projection coefficient of the first non-common subspace on the quantization basis of the first non-common subspace and the column index of the quantization basis of the first non-common subspace. The processing unit is configured to perform Schmidt orthogonalization processing on the first basis and the first non-common subspace to obtain a fifth basis, and the communication unit is configured to transmit indication information of the fifth basis. Among them, the indication information of the fifth basis indicates the fifth basis, or indicates the projection coefficient of the fifth basis on the quantization basis of the fifth basis and the column index of the quantization basis of the fifth basis.

[0040] In a possible implementation, the communication unit is used to send first indication information, and the first indication information indicates the frequency domain position for sending a third reference signal. The communication unit is also used to receive the third reference signal.

[0041] In a possible implementation, the processing unit is used to determine a fourth channel matrix based on the third reference signal, and determine a third superposition coefficient vector based on the fourth channel matrix and a sixth basis constructed from corresponding rows of the first basis according to the position indices of the third reference signal in the spatial-frequency domain. The processing unit is also used to determine a fourth superposition coefficient vector composed of the F superposition coefficients with the largest amplitudes in the third superposition coefficient vector, and determine the position indices of the F superposition coefficients in the third superposition coefficient vector to form a fourth basis selection vector. The processing unit is further used to multiply the fourth superposition coefficient vector by a seventh basis to obtain a fifth channel matrix, and the seventh basis is composed of the corresponding columns of the fifth basis according to K position indices in the fourth basis selection vector.

[0042] In a possible implementation, the communication unit is used to send a first request message to the core network device, and the first request message requests to obtain a channel map or requests to obtain the basis information corresponding to a first device in the channel map. The communication unit is also used to receive a first response message, and the first response message includes the channel map or the basis information corresponding to the first device in the channel map.

[0043] In a possible implementation, the processing unit is used to perform channel estimation based on a fourth reference signal to obtain a plurality of sixth channel matrices. The plurality of sixth channel matrices include channel state information in the spatial domain dimension. The fourth reference signal is a reference signal received before the third reference signal, and the fourth reference signal and the third reference signal are reference signals of the same type. The processing unit is used to determine an eighth basis based on the plurality of sixth channel matrices.

[0044] In a possible implementation, the processing unit is used to determine the common subspace where the eighth basis and the first basis intersect as a second common subspace, and determine the subspace of the eighth basis excluding the second common subspace as a second non-common subspace, and the second non-common subspace is used to update the fifth basis.

[0045] In a possible implementation, the processing unit is used to perform Schmidt orthogonalization processing on the fifth basis and the second non-common subspace to obtain a ninth basis. The processing unit is used to determine a fifth superposition coefficient vector based on the fourth channel matrix and the spatial-frequency position of the SRS signal in the corresponding rows of the ninth basis, and determine a sixth superposition coefficient vector and a sixth basis selection vector based on the fifth superposition coefficient vector. The processing unit is used to multiply the sixth superposition coefficient vector by a tenth basis to obtain a sixth channel matrix, thereby realizing the reconstruction of the channel state information.

[0046] For the fourth and fifth aspects, as an example, the processing unit may be a processor, and the communication unit may be a transceiver unit, a transceiver, or a communication interface. It can be understood that when the communication device is a communication equipment (such as a terminal or a network device), the communication unit may be a transceiver in the communication device (for example, the transceiver includes a transmitter and a receiver), which is implemented, for example, through an antenna, a feeder, a codec, etc. in the communication device. Or, if the communication device is a chip disposed in a device, the processing unit may be a processing circuit, a logic circuit, etc. of the chip, and the communication unit may be an input / output interface of the chip, such as an input / output circuit, a pin, etc.

[0047] In a sixth aspect, the present application provides a communication device, including: a processor for executing instructions; optionally, the communication device further includes a memory for storing the instructions, and when the instructions are executed by the processor, the communication device is caused to implement at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect, and the methods in the second aspect and any possible implementation manner of the second aspect. Optionally, the processor and the memory are coupled.

[0048] In a seventh aspect, the present application provides a communication system, which includes at least one of the devices or equipment in the above fourth aspect to the sixth aspect, such that the at least one of the devices or equipment executes at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect, and the methods in the second aspect and any possible implementation manner of the second aspect.

[0049] In an eighth aspect, the present application provides a computer-readable storage medium, on which instructions are stored, and when the instructions are run on a computer, the computer is caused to execute at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect, and the methods in the second aspect and any possible implementation manner of the second aspect.

[0050] In a ninth aspect, the present application provides a computer program product, including instructions, and when the instructions are run on a computer, the computer is caused to execute at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect, and the methods in the second aspect and any possible implementation manner of the second aspect.

[0051] In a tenth aspect, the present application provides a chip, which includes a processor (or logic circuit). Optionally, the chip may further include a communication interface (or interface) for implementing at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect; the methods in the second aspect and any possible implementation manner of the second aspect. In a possible implementation, if the chip is the smallest processing unit in a whole machine, the chip may be a processor, or may include a processor and a memory, or may further include a processor, a memory, and a transceiver for implementing at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect; the methods in the second aspect and any possible implementation manner of the second aspect.

[0052] In an eleventh aspect, the present application provides a chip system. The chip system includes a processor and an interface. Optionally, it may further include a memory for implementing at least one of the following: the methods in the first aspect and any possible implementation manner of the first aspect; the methods in the second aspect and any possible implementation manner of the second aspect. The chip system may be composed of chips, or may include chips and other discrete devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of a communication system provided by the present application;

[0054] Figure 2 A schematic diagram of a network element structure provided by the present application;

[0055] Figure 3 A schematic diagram of a channel map;

[0056] Figure 4 A schematic diagram of a process for a network device and a terminal to perform CSI measurement;

[0057] Figure 5 A schematic diagram of a R16 codebook structure;

[0058] Figure 6 A schematic diagram of equivalently representing a channel matrix H with column vectors;

[0059] Figure 7 A schematic diagram of matrix decomposition of a spatio-frequency joint channel h;

[0060] Figure 8 A schematic diagram of a feedback process of a spatio-frequency joint long and short period combined codebook;

[0061] Figure 9 A schematic diagram of a process of a communication method provided by the present application;

[0062] Figure 10Schematic diagram of a downlink channel reconstruction process enabled by combining a channel map with CSI-RS provided by this application;

[0063] Figure 11 Schematic diagram of a downlink channel reconstruction and channel basis update process enabled by combining a channel map with CSI-RS provided by this application;

[0064] Figure 12 Schematic diagram of a downlink channel reconstruction process enabled by combining a channel map with CSI-RS and SRS provided by this application;

[0065] Figure 13 Schematic diagram of a downlink channel reconstruction and channel basis update process enabled by combining a channel map with CSI-RS and SRS provided by this application;

[0066] Figure 14 Schematic diagram of a channel reconstruction and channel basis update process enabled by combining a channel map with SRS provided by this application;

[0067] Figure 15 Schematic diagram of a communication device provided by this application;

[0068] Figure 16 Schematic diagram of another communication device provided by this application. Detailed implementation manners

[0069] The communication method provided by this application can be applied to a communication system 1000 as Figure 1 shown. For example, the communication system includes a radio access network (RAN) 100, where the RAN 100 includes at least one RAN node (such as Figure 1 110a and 110b in Figure 1 , collectively referred to as 110), and may further include at least one terminal (such as Figure 1 120a - 120j in

[0070] RAN100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, and a future radio access system defined in 3GPP. RAN100 can also include two or more different radio access systems as described above. RAN100 can also be an open RAN (O-RAN).

[0071] RAN nodes, also known as radio access network devices, RAN entities, or access nodes, are used to help terminals access a communication system wirelessly. In one application scenario, RAN nodes can be base stations, evolved NodeBs (eNodeBs), transmission reception points (TRPs), next generation NodeBs (gNBs) in a 5th generation (5G) mobile communication system, next generation NodeBs in a 6th generation (6G) mobile communication system, and base stations in future mobile communication systems. RAN nodes can be macro base stations (such as Figure 1 110a in Figure 1 ), or micro base stations or indoor stations (such as

[0072] In another application scenario, the wireless access of a terminal can be assisted through the cooperation of multiple RAN nodes, and different RAN nodes respectively implement some functions of a base station. For example, the RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). Here, the CU completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the function of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control layer and the medium access control (MAC) layer of the base station, and can also complete some or all of the functions of the physical layer. For the specific descriptions of the above various protocol layers, reference can be made to the relevant technical specifications of 3GPP. The RU can be used to implement the functions of transmitting and receiving radio frequency signals. The CU and the DU can be two independent RAN nodes, or can be integrated in the same RAN node, for example, integrated in the baseband unit (BBU). The RU can be included in the radio frequency device, for example, included in the remote radio unit (RRU) or the active antenna unit (AAU). The CU can be further divided into two types of RAN nodes: CU-control plane and CU-user plane.

[0073] In different systems, the RAN node may have different names. For example, in the O-RAN system, the CU can be called an open CU (O-CU), the DU can be called an open DU (O-DU), and the RU can be called an open RU (O-RU). The RAN node in the embodiments of the present application can be implemented in the form of a software module, a hardware module, or a combination of a software module and a hardware module. For example, the RAN node can be a server loaded with the corresponding software module. The embodiments of the present application do not limit the specific technologies and specific device forms adopted by the RAN node. For the convenience of description, in the following text, the base station is used as an example of the RAN node for description.

[0074] A terminal is a device with wireless transceiver capabilities that can send signals to a base station or receive signals from a base station. A terminal can also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely applied in various scenarios, such as device-to-device (D2D), vehicle to everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, etc. A terminal can be a mobile phone, tablet computer, computer with wireless transceiver capabilities, wearable device, vehicle, airplane, ship, robot, robotic arm, smart home device, etc. Embodiments of this application do not limit the specific technologies and specific device forms adopted by the terminal.

[0075] The base station and the terminal can be in fixed positions or movable. The base station and the terminal can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; they can also be deployed on water; they can also be deployed on airplanes, balloons, and artificial satellites. Embodiments of this application do not limit the application scenarios of the base station and the terminal.

[0076] The roles of the base station and the terminal can be relative. For example, Figure 1 the helicopter or drone 120i in [figure] can be configured as a mobile base station. For the terminals 120j that access the radio access network 100 through 120i, the terminal 120i is a base station; but for the base station 110a, 120i is a terminal, that is, the communication between 110a and 120i is through the radio air interface protocol. Of course, the communication between 110a and 120i can also be through the interface protocol between base stations. At this time, relative to 110a, 120i is also a base station. Therefore, both the base station and the terminal can be uniformly referred to as communication devices. Figure 1 The 110a and 110b in [figure] can be referred to as communication devices with base station functions. Figure 1 The 120a - 120j in [figure] can be referred to as communication devices with terminal functions.

[0077] Communication can be carried out between a base station and a terminal, between base stations, or between terminals through licensed spectrum, unlicensed spectrum, or both simultaneously; communication can be carried out through spectrum below 6 gigahertz (GHz), through spectrum above 6 GHz, or using both spectrum below 6 GHz and spectrum above 6 GHz simultaneously. Embodiments of this application do not limit the spectrum resources used for wireless communication.

[0078] In embodiments of this application, the functions of a base station can also be performed by modules (such as chips) in the base station or by a control subsystem with base station functions. The control subsystem with base station functions here can be a control center in the above application scenarios such as smart grid, industrial control, intelligent transportation, and smart city. The functions of a terminal can also be performed by modules (such as chips or modems) in the terminal or by a device with terminal functions.

[0079] In this application, the base station sends a downlink signal or downlink information to the terminal, and the downlink information is carried on a downlink channel; the terminal sends an uplink signal or uplink information to the base station, and the uplink information is carried on an uplink channel. In order to communicate with the base station, the terminal needs to establish a wireless connection on a cell controlled by the base station. The cell that has established a wireless connection with the terminal is called the serving cell of the terminal. When the terminal communicates with the serving cell, it is also interfered by signals from neighboring cells.

[0080] Among them, the core network may include, but is not limited to, one or more of the following devices or network elements: access and mobility management function (AMF), location management function (LMF), map management function (MMF), etc. Among them, AMF is mainly responsible for mobility management in the mobile network, such as user location update, user registration to the network, user handover, etc. LMF is mainly responsible for obtaining location information such as user location. MMF is mainly responsible for storing channel characteristics based on location information and generating channel maps, etc.

[0081] Optionally, the network element structure involved in this application is as Figure 2 shown, mainly including the following network elements and modules:

[0082] (1) Radio resource control (RRC) signaling interaction module: A module for the base station and the terminal to send and receive RRC signaling.

[0083] (2) MAC signaling interaction module: A module for the base station and the terminal to send and receive Media Access Control - Control Element (MAC-CE) signaling.

[0084] (3) Physical layer (PHY) signaling and data interaction module: A module for the base station and the terminal to send and receive uplink / downlink control signaling (such as physical downlink control channel (PDCCH), physical uplink control channel (PUCCH)), and uplink / downlink data (such as data transmitted on the physical downlink shared channel (PDSCH), data transmitted on the physical uplink shared channel (PUSCH)).

[0085] (4) The base station communicates with the AMF through the NG-C interface. The AMF is equivalent to a router for the base station to communicate with the LMF / MMF. The LMF realizes the location estimation of the UE, and the map construction process is completed in the LMF / MMF. The AMF communicates with the LMF / MMF through the NLs interface.

[0086] It can be understood that in this application, PDSCH, PDCCH, PUSCH, and PUCCH are only examples of the downlink data channel, downlink control channel, uplink data channel, and uplink control channel respectively. In different systems and different scenarios, the data channel and the control channel may have different names, and this application does not limit this.

[0087] It should be noted that:

[0088] In the embodiments of this application, "send" and "receive" represent the direction of signal transmission. For example, "send information to the terminal" can be understood as the destination of the information being the terminal device, which can include directly sending through the air interface, and also include indirectly sending through the air interface by other units or modules. "Receive information from the network device" can be understood as the source of the information being the network device, which can include directly receiving from the network device through the air interface, and can also include indirectly receiving from the network device through the air interface by other units or modules. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface.

[0089] In other words, the sending and receiving can be carried out between devices, for example, between a network device and a terminal device, or can be carried out within a device, for example, sending or receiving between components, modules, chips, software modules or hardware modules within a device through a bus, trace or interface.

[0090] It can be understood that the information may be processed accordingly between the source end and the destination end of the information sending, such as encoding, modulation, etc., but the destination end can understand the valid information from the source end. Similar expressions in this application can be understood similarly and will not be elaborated here.

[0091] In the embodiments of this application, "indication" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a piece of information (such as the indication information described below) is called the information to be indicated. Then, in the specific implementation process, there are many ways to indicate the information to be indicated. For example, but not limited to, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated, etc. It is also possible to indirectly indicate the information to be indicated by indicating other information, where there is an association relationship between the other information and the information to be indicated; it is also possible to only indicate a part of the information to be indicated, while the other parts of the information to be indicated are known or pre-agreed. For example, the arrangement order of each piece of information pre-agreed (such as protocol pre-definition) can be used to realize the indication of specific information, thereby reducing the indication overhead to a certain extent. This application does not limit the specific manner of indication. It can be understood that for the sender of the indication information, the indication information can be used to indicate the information to be indicated, and for the receiver of the indication information, the indication information can be used to determine the information to be indicated.

[0092] For the convenience of understanding, the definitions of relevant terms involved in this application are introduced in detail below:

[0093] 1. Channel map:

[0094] The channel map can be understood as a database for storing channel characteristics based on location information; the channel characteristics include but are not limited to channel statistical covariance matrix, angular spectrum, delay spectrum, path loss, etc. For example, Figure 3 is a schematic diagram of a channel map. In this channel map, the physical cells are divided at a two-dimensional grid level (such as Figure 3 each square in is called a grid point), and each grid point stores several channel characteristics (such as channel statistical covariance matrix, angular spectrum, delay spectrum, path loss, etc.) in the form of a matrix, vector, or scalar.

[0095] Among them, a common method for constructing a channel map is to build a database based on historical measurement data and establish a mapping relationship between location information and channel characteristics. However, historical measurement data has limitations. For example, historical measurement data is usually based on channel characteristics at known locations, and interpolation methods are used to complete the channel characteristics at unknown locations, so as to obtain the channel map of the entire cell. With the development of digital twin technology, the channel map can be obtained through channel twin technology. For example, a computer can combine a priori environmental maps (such as including measured environmental information), and use electromagnetic simulation to calculate and simulate the reflection, diffraction, and scattering characteristics of communication multipaths, so as to obtain a deterministic channel for constructing the channel map.

[0096] 2. Channel Map-Assisted Communication Technology:

[0097] With the increase in system bandwidth, the increase in the number of terminal antennas, the increase in network load, the explosion of wireless channel dimensions (such as wireless channel dimensions can be extended to multiple dimensions such as spatial domain, spatio-frequency domain, and frequency domain), and the limitation of pilot measurement resources, high-precision measurement of wireless channels faces huge challenges. The accurate measurement of wireless channels is the cornerstone of mobile communication network research and is crucial for the design, analysis, and optimization of wireless communication networks. However, traditional wireless channel measurement methods based on reference signals (such as pilot symbols) are difficult to meet the requirements of the development of technologies such as large bandwidth and multiple antennas. To solve the problem of limited measurement resources of reference signals in wireless communication systems, the channel map can be used to achieve channel measurement with low pilot overhead. For example, the channel covariance matrix at a specific location can be provided through the channel map, and the sounding reference signal (SRS) overhead can be reduced based on this channel covariance matrix.

[0098] 3. Downlink Channel Reconstruction Technology:

[0099] In a 5G communication system, the adoption of massive multiple input multiple output (MIMO) technology is beneficial to improving the spectral efficiency of the system. When using MIMO technology, when the network device sends data to the terminal device, signal precoding needs to be performed according to the channel state information (CSI).

[0100] In a time division duplexing (TDD) system, the downlink CSI can be obtained according to channel reciprocity. For example, the downlink channel can be estimated by sending uplink SRS data. With the increase in the number of users and the continuous increase in load, the round-robin transmission of SRS in a large bandwidth scenario may lead to insufficient SRS resources and serious channel aging.

[0101] In a frequency division duplexing (FDD) system, due to the large frequency offset between the uplink and downlink channels, the uplink channel and the downlink channel do not satisfy the direct reciprocity relationship, and the uplink channel information cannot be used for accurate downlink precoding. In an FDD system, it is necessary for the user to feedback the CSI of the downlink channel to the base station.

[0102] For example, Figure 4 As a schematic diagram of the process for a network device and a terminal to perform CSI measurement, it may include the following steps:

[0103] Step 1: The network device sends channel measurement configuration information to the terminal. This channel measurement configuration information is used for the configuration of channel measurement, such as indicating the time of channel measurement to the terminal.

[0104] Step 2: The network device sends a channel state information reference signal (CSIRS) to the terminal, and this pilot is used for channel measurement. For example, the terminal receives the CSI-RS and performs measurements based on the CSI-RS to obtain CSI feedback information. Optionally, the CSI-RS can also be referred to as the CSI-RS pilot.

[0105] Step 3: The terminal sends channel state information to the network device. For example, the terminal sends channel state information such as a rank indicator (RI), a channel quality indicator (CQI), and a precoding matrix indicator (PMI) to the network device.

[0106] Step 4: The network device sends data to the terminal based on the CSI. Among them, the network device determines precoding information for sending service data according to the CSI feedback by the terminal, so as to perform the transmission of service data.

[0107] Optionally, channel state information (CSI) includes information used to describe the channel attributes of a communication link and reported by a receiving device to a transmitting device in a wireless communication system. For example, CSI may include, but is not limited to, precoding matrix indicator (PMI), rank indicator (RI), channel quality indicator (CQI), CSI-RS resource indicator (CRI), and layer indicator (LI), etc. It should be understood that the specific content of CSI listed above is only for illustrative purposes and should not constitute any limitation to this application. CSI may include one or more of the above-listed items, or may include other information used to characterize CSI other than the above-listed items, which is not limited in this application.

[0108] 4. Solution of R16 codebook for realizing channel reconstruction based on reference signals:

[0109] For example, the R16 codebook is a spatial-frequency domain double-domain compression codebook that compresses the channels of all subbands in the frequency domain, and the codebook structure satisfies formula (1):

[0110]

[0111] Wherein, is the spatial domain compression matrix, is the combination coefficient matrix, is the frequency domain compression matrix, N 1 and N 2 are the numbers of horizontal antenna ports and vertical antenna ports of the base station respectively, L is the number of spatial domain bases, and M is the number of frequency domain bases. For example, Figure 5 is a schematic diagram of an R16 codebook structure, which shows each matrix and its dimensions. Optionally, spatial-frequency domain double-domain compression means quantizing using the sparsity of the channel in the spatial domain and the sparsity in the frequency domain, reducing the number of weighted coefficients required to be reported, thereby realizing the compression of the channel matrix.

[0112] However, the R16 codebook only utilizes the sparse characteristics of the channel in the angle-delay domain, that is, the correlation characteristics of the spatial domain information on different subbands for feedback and compression. For example, it is necessary to feedback the spatial domain, frequency domain bases, and combination coefficients, and the feedback overhead is large. And because the bases need to be reported, it is stipulated in the protocol that both the spatial domain and frequency domain bases are discrete Fourier transform (DFT) codebooks, which limits the sparsity of the combination coefficient matrix W 2 . In addition, in an actual channel, especially in a scenario where the channel propagation environment changes slowly, the change speed of the bases is very slow and can be fed back in a long period, while R16 does not support reporting the bases and combination coefficients with different periods.

[0113] 5. Scheme of R18 codebook for channel reconstruction based on reference signals:

[0114] In order to sparsely represent the channel in the spatio-frequency domain, fully exploit the sparse characteristics of the channel, and consider the law that different channel characteristics change at different speeds over time. For example, the path angle-delay information (spatio-frequency joint basis) changes slowly while the path superposition coefficient (superposition coefficient corresponding to the basis) changes rapidly. The R18 codebook scheme for channel reconstruction based on reference signals designs a codebook feedback method that combines long and short periods, which is beneficial to reducing the feedback overhead. For example, the following describes the two cases of spatio-frequency joint compression and feedback, and spatio-frequency independent compression and feedback respectively.

[0115] Case 1: Spatio-frequency joint compression and feedback:

[0116] Taking the downlink channel as an example, assuming the terminal is a single-antenna, the channel matrix of the terminal satisfies formula (2):

[0117]

[0118] where, is the spatial domain compression matrix, is the frequency domain compression matrix, is the combination coefficient matrix (which is a diagonal matrix), M is the number of base station antennas, L is the number of channel multipaths, N is the number of frequency units (for example, the frequency unit is a subcarrier or a resource element (RE) or a resource block (RB) or a resource block group (RBG) or a sub-band). For example, Figure 6 is a schematic diagram of the channel matrix H equivalently represented by column vectors. It can be seen that Figure 6 the channel H represented by the matrix in the spatial-frequency domain 1 , H 2 , …, H t can be equivalently represented by the column vectors h 1 , h 2 , …, h t in the spatio-frequency domain. The equivalent column vectors satisfy formula (3):

[0119]

[0120] where, diag(C) represents the column vector composed of the diagonal elements of matrix C ⊙ represents the Khatri-Rao product. For example, a l is the l-th column of A, is the Kronecker product, bl is the l-th column of B, where l is an integer greater than 0. The l-th column (i = 1, …, N) of the matrix F*⊙S satisfies formula (4):

[0121]

[0122] where denotes the Kronecker product, where[:, l] represents the l-th column of the matrix. The above operation can represent the channel represented by a matrix in the spatial-frequency domain by a spatial-frequency domain column vector.

[0123] where, for the channel h represented by a column vector, its statistical covariance matrix satisfies formula (5):

[0124]

[0125] where denotes taking the expectation of a random number / matrix, U is the matrix composed of the eigenvectors of the covariance matrix R h The i-th column of U is the i-th eigenvector of R h The corresponding eigenvalue is the i-th element on the diagonal of the diagonal matrix Λ. The eigenvalues corresponding to each column of U are the elements on the diagonal of the diagonal matrix Λ, and the elements on the diagonal of Λ are arranged from large to small. The average covariance matrix between polarizations satisfies formula (6):

[0126]

[0127] where h + is the channel corresponding to the positive polarization, h- is the channel corresponding to the negative polarization, is the average covariance matrix The matrix composed of the eigenvectors of The i-th column of is the i-th eigenvector of The corresponding eigenvalue is the i-th element on the diagonal of the diagonal matrix The eigenvalues corresponding to each column of are the elements on the diagonal of the diagonal matrix The elements on the diagonal of are arranged from large to small. Then the instantaneous channel satisfies formula (7):

[0128]

[0129] where U p is the matrix composed of the first P columns of the basis U. The channel has sparse characteristics in the angular-delay domain (i.e., only some elements in are non-zero or have large values), and the angular-delay changes slowly (i.e., at different times h 1, h 2 …h t , U can be considered to be basically unchanged or changing slowly, while varies with time). In addition, using the Karhunen-Loeve decomposition, when expanding h based on the eigenvectors corresponding to the P largest eigenvalues of the matrix R h (i.e., the first P columns U p of U), the truncated statistical mean square error is the smallest. Considering that the statistical covariance matrix can be approximated by the statistical covariance matrix after polarization averaging, the instantaneous channel h satisfies Equation (8):

[0130]

[0131] where is the matrix formed by the first columns of denotes the Kronecker product. When designing the CSI feedback scheme, can perform quantization feedback on with a relatively long period, and perform quantization feedback on in a short period or an aperiodic manner.

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

[0133] S1: The UE performs spatio-frequency joint covariance matrix statistics on the downlink channel and performs inter-polarization averaging to obtain Perform singular value decomposition (SVD) or eigenvalue decomposition on to obtain the matrix of eigenvectors The UE truncates the matrix and selects the columns corresponding to the largest eigenvalues to form the matrix contains most of the energy of the channel (the choice of P can be determined by the UE itself, or the gNB specifies an optional range and then the UE makes a choice).

[0134] S2: The UE approximates the matrix of statistical eigenvectors using the DFT codebook, that is, find W f , W s , C 1 such that or where W f and W sis a sub - matrix composed of partial columns of the oversampled DFT matrix, representing the beam / basis vectors in the frequency domain and the spatial domain respectively; C 1 is the projection on the quantization matrix W 1 and can correct W 1 to the statistical feature matrix The W f , W s , and C 1 are reported to the base station in a long period (optionally, "long period" is used to distinguish from the "short period" in the following text. It doesn't necessarily mean that the reporting periods of these matrices are the same because the time - varying scales of each matrix may vary. For example, C 1 probably changes faster with time than W f , W s . Therefore, different feedback - period granularities can be used).

[0135] S3: The UE calculates the codebook C 1 , C 1 to be fed back according to the instantaneous channel h and the W 2 , C 2 obtained in S2. C 1 , C 1 can be the projection of the instantaneous channel h on W 2 , i.e., C 1 =(W 1 ) H h; or C 2 can be calculated in other forms (for example, when the columns of W 1 , C 1 are not orthogonal, W 1 , C 1 needs to be orthogonalized). The UE feeds back C 2 to the base station in a short period or aperiodically for reconstructing the downlink channel.

[0136] The above CSI compression reporting scheme is mapped to the codebook form to satisfy formula (9):

[0137]

[0138] where ⊙ represents the KR (Khatri - Rao) product. For example, Figure 7 is a schematic diagram of the matrix decomposition of the spatio - frequency joint channel h. Figure 7 In it, h is the spatio - frequency joint channel, M is the number of base - station antennas (dual - polarized array), and N is the number of frequency units (sub - carrier granularity or RB granularity or RBG granularity or sub - band granularity). Since W f , W s , C 1 are used to quantify and approximate Therefore, 2K≥P is satisfied, where K is the number of columns of matrix W s . is the DFT basis for quantizing the spatio-frequency joint basis

[0139] Case 2: Spatio-frequency independent compression and feedback:

[0140] Taking the downlink channel as an example, assuming the terminal is a single-antenna, the channel matrix of the terminal satisfies formula (10):

[0141] H≈S′C 1 C 2 C 3 F′ h (10)

[0142] where is the spatial domain basis, which is a matrix composed of B spatial domain vectors; is the frequency domain basis, which is a matrix composed of F frequency domain vectors. is the first superposition coefficient matrix, which represents the coefficient matrix composed of multiple groups of spatial domain vector coefficients; is the second superposition coefficient matrix, which represents the coefficient matrix composed of the weighted coefficients corresponding to a group of spatio-frequency vectors formed by each of the B spatial domain vectors and each of the F frequency domain vectors; is the third superposition coefficient matrix, which represents the matrix composed of multiple groups of frequency domain vector coefficients. B is the number of spatial domain vectors determined by the network device or the terminal; K S represents the number of weighted coefficients corresponding to each spatial domain vector; D represents the number of weighted coefficients corresponding to each frequency domain vector; F is the number of frequency domain vectors determined by the network device or the terminal.

[0143] Optionally, a spatial domain vector may also be referred to as a beam vector, a spatial beam basis vector, or a spatial basis vector. The length of the spatial domain vector may be the number of transmit antenna ports M in a polarization direction, where M is a positive integer greater than 1. For example, if the spatial domain vector is a column vector or a row vector of length M, then the M column vectors or row vectors correspond to the M transmit antenna ports, respectively, and this application does not limit this. Each element in the spatial domain vector may represent the weight of each antenna port. Based on the weights of each antenna port represented by each element in the spatial domain vector, the signals of each antenna port are linearly superimposed to form an area with a strong signal in a certain direction or certain directions in space. Optionally, the spatial domain vector may be determined based on a DFT vector. In other words, the spatial domain vector may be a DFT vector. The spatial domain vector may be, for example, a DFT vector defined in a type II codebook in 3GPP technical specification TS 38.214 version 15 (release 15, R15).

[0144] Optionally, a frequency domain vector (frequency domain vector), also known as a frequency domain basis vector, is a vector used to represent the law of change of the channel in the frequency domain. A frequency domain vector can represent a law of change. Since the signal can reach the receiving antenna from the transmitting antenna through multiple paths when it is transmitted through a wireless channel. Multipath delay causes frequency selective fading, which is the change of the frequency domain channel. Therefore, different frequency domain vectors can be used to represent the law of change of the channel in the frequency domain caused by delays on different transmission paths. The length of the frequency domain vector can be determined by the number of frequency domain units to be reported configured by the network side in the reporting bandwidth, or it can be a protocol predefined value. This application does not limit the length of the frequency domain vector. Among them, the reporting bandwidth can, for example, refer to the CSI reporting bandwidth (CSI-ReportingBand) carried in the CSI reporting configuration in the high-level signaling (such as an RRC message). The length of the frequency domain vector can be denoted as N, where N is a positive integer greater than 1. The frequency domain vector can, for example, be a column vector or a row vector whose length includes N. This application does not limit it.

[0145] Optionally, the space-frequency joint basis can characterize the common features of the space domain and the frequency domain; for example, the space-frequency joint basis is a matrix constructed by one or more space-frequency domain basis vectors. Among them, the space-frequency domain basis vectors can represent the change law of the channel in the frequency domain and the signal characteristics in a certain direction or certain directions in space. For example, the feature description of the space domain vector and the frequency domain vector can be referred to in the previous text, which will not be repeated here.

[0146] Corresponding to the channel decomposition method shown in formula (10), the mapping to the codebook form satisfies formula (11):

[0147]

[0148] Among them, is the spatial domain basis of the downlink channel determined by the network device or terminal, is the frequency domain basis of the downlink channel determined by the network device or terminal. W S The calculation method satisfies formulas (12) and (13):

[0149]

[0150] U S =W S C 1 (13)

[0151] Among them, is the spatial domain statistical covariance matrix of H, is R S The matrix composed of the eigenvectors of, U S The eigenvalue corresponding to each column of is the element on the diagonal of the diagonal matrix and the elements on the diagonal of Λ S The elements on the diagonal are arranged from large to small, denotes taking the expectation of a random number / matrix. W f The calculation method of is to satisfy formulas (14) and (15):

[0152]

[0153]

[0154] Among them, is the frequency domain statistical covariance matrix of H, is R F The matrix composed of the eigenvectors of, U F The eigenvalue corresponding to each column of is the element on the diagonal of the diagonal matrix and the elements on the diagonal of Λ F The elements on the diagonal are arranged from large to small.

[0155] For example, Figure 8 is a schematic diagram of the air-frequency joint long and short period combined codebook feedback process. For example, assume that the configuration of the base station includes 64T dual-polarized antennas, 50RB, and 64 DFT column vectors are used for approximation The number of columns is 13, Long period feedback W 1 C 1 , with a period of T L ; Short period feedback C 2 , with a period of T S。During each long - period base feedback, ignore W 1 For the required feedback amount, it is necessary to perform feedback on the 64×13 = 832 coefficients that make up C 1 It can be seen that the feedback overhead of the joint space - frequency long - and short - period combined codebook is relatively large. In addition, the base station also needs to configure CSI - RS with 32 ports for measuring channel information, and the pilot overhead is large. As the number of antennas increases and the frequency band rises, the pilot overhead increases sharply.

[0156] Therefore, this application provides a communication method. In this method, the base station uses the region - level channel base provided by the channel map as prior information (which can be the joint space - frequency base U, the spatial base U S , the frequency - domain base U F , or it can be the spatial compression matrix W s , the frequency - domain compression matrix W f , this application does not make a limitation). Then, the joint space - frequency base U is sent to the UE in a long - period manner, and sparse CSI - RS is sent in a short - period manner. After receiving the sparse CSI - RS, the UE calculates the superposition coefficient C 2 and performs short - period feedback. At the same time, the column index value of the joint space - frequency base is updated and fed back, which is beneficial to reducing the feedback overhead.

[0157] In order to reduce the overhead of the reference signal and the feedback overhead of the reference signal, this application provides a communication method. This method effectively reduces the overhead of the reference signal and the feedback overhead of the reference signal by sending the channel base information based on the channel map, which is beneficial to improving the channel reconstruction accuracy.

[0158] For example, Figure 9 is a schematic flowchart of a communication method provided by this application. This method can be implemented by the interaction between a first device and a second device. The first device in this application can be a terminal or a module applied to a terminal, and the second device can be a network device or a module applied to a network device. This method includes the following steps:

[0159] S101, the second device sends the indication information of the first base; correspondingly, the first device receives the indication information of the first base.

[0160] For example, according to the introduction of the R16 and R18 codebook solutions for channel reconstruction based on reference signals in the foregoing text, the matrix of the channel of the terminal can be equivalently represented by a column vector in the spatio-frequency domain. The terminal determines the channel based on CSI-RS, and the base station restores the channel based on the quantization basis and coefficients fed back by the terminal. Therefore, in this embodiment, the second device can directly send the indication information of the first basis (for indicating the first basis to the first device), so that the first device can directly obtain the basis information. And, different from the R16 and R18 codebook solutions (the channel basis is quantized and fed back to the base station side after being calculated on the terminal side, so there is a precision loss in the basis obtained by the base station side calculation), the first basis in this embodiment is the region-level channel basis (prior information) provided by the channel map, and the second device can obtain the channel basis without quantization loss according to the channel map, which is beneficial to improving the CSI reconstruction accuracy.

[0161] Among them, the indication information of the first basis indicates the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis; the first basis is composed of L column basis vectors, and L is a positive integer. For example, the quantization basis of the first basis is any one of a DFT codebook, a fast Fourier transformation (FFT) codebook, an oversampled DFT codebook, an oversampled FFT codebook, or a codebook determined based on a preset rule, which is not limited in this application.

[0162] Among them, the basis vector is determined based on the quantization basis. For example, the basis vector is a DFT basis vector (the DFT basis vector is a vector determined based on the DFT codebook), an FFT basis vector (the FFT basis vector is a vector determined based on the FFT codebook), an oversampled DFT basis vector (the oversampled DFT basis vector is a vector determined based on the oversampled DFT codebook), an oversampled FFT basis vector (the oversampled FFT basis vector is a vector determined based on the oversampled FFT codebook), or any one of the vectors determined based on a preset rule. Assuming that one or more basis vectors are one or more DFT basis vectors, the first basis is a matrix composed of L column DFT basis vectors selected from the one or more DFT basis vectors (that is, the elements in the first basis satisfy a preset rule and have relevant characteristics).

[0163] Among them, the column index of the quantization basis of the first basis includes the indexes of the basis vectors constituting the first basis. For example, assuming that the first basis is obtained by quantization projection of the quantization basis of the first basis, for example, the quantization basis of the first basis can be a DFT codebook, then the first basis is obtained by quantization projection of the DFT codebook. However, there may be multiple DFT basis vectors arranged in sequence in the DFT codebook. Assuming that the 1st, 3rd, and 5th DFT basis vectors are selected to construct the first basis, the column index of the quantization basis of the first basis is {1, 3, 5}.

[0164] Optionally, the first basis is a spatio-frequency combined basis, or a spatial domain basis and a frequency domain basis. For example, assume that the first basis is a spatio-frequency combined basis U, and the quantization basis of the first basis is a DFT codebook. Then, the indication information of the first basis indicates the projection coefficients of the spatio-frequency combined basis U in the DFT codebook and the column index of the DFT codebook. It should be noted that the basis in this application can also be referred to as a codebook. For example, the first basis can also be referred to as the first codebook, the second basis can also be referred to as the second codebook, and so on. This application does not make any limitations.

[0165] Optionally, the specific implementation manner of the indication information of the first basis includes the following cases:

[0166] (1) Case 1: The indication information of the first basis includes the first basis. That is, the second device directly sends the first basis to the first device. For example, assume that the first basis is a spatio-frequency combined basis U. The second device uses PDCCH / PDSCH to send the spatio-frequency combined basis corresponding to the first device to the first device. M is the number of antennas of the second device, L is the number of paths, and N is the number of frequency units (for example, the frequency unit is a subcarrier or an RB or an RBG or a sub-band). It should be noted that the values in the first basis can be in complex form, and then the values in complex form need to be subjected to amplitude-phase quantization processing. The second device can obtain and send the first basis after amplitude-phase quantization processing.

[0167] (2) Case 2: The indication information of the first basis includes the projection coefficients of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis. That is, the second device indirectly indicates the first basis to the first device. For example, assume that the first basis is a spatio-frequency combined basis U. The second device can use the quantization basis B of the first basis constructed by one or more basis vectors to perform quantization processing on the spatio-frequency combined basis U. The quantization processing satisfies formula (16):

[0168] U = B × C 13 (16)

[0169] where B represents the quantization basis of the first basis, and C 13 represents the projection coefficients of the first basis on the quantization basis of the first basis. The role of C 13 is similar to the coefficient W in the previous text. 1 C 1 . Therefore, the indication information of the first basis includes the column index of the quantization basis of the first basis (indicating the basis vector used to quantize the spatio-frequency combined basis U) and C 13 . Another example, assume that the first basis is a spatial domain basis U S and a frequency domain basis U FWhen it is possible, the description in the process of spatio-frequency independent compression and feedback described in the first part of the foregoing can be referred to. For example, the spatial domain basis U S satisfies formula (13), and W is adopted S for quantization processing; the frequency domain basis U F satisfies formula (15), and W is adopted f for quantization processing.

[0170] Optionally, the second device can use PDCCH / PDSCH to send the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis to the first device; correspondingly, the first device receives the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis, so that the spatio-frequency joint basis U can be restored in combination with the quantization basis B of the first basis. Optionally, the quantization basis B of the first basis is known and the same for both the first device and the second device. Optionally, the indication overhead in case two is lower than that in case one, but the quantization basis B of the first basis needs to be preset (such as pre-stored) on both sides of the first device and the second device.

[0171] Optionally, before S101, the following steps are further included:

[0172] The second device sends a first request message to the core network device, and this first request message requests to obtain a channel map, so as to obtain the basis information corresponding to the first device. For example, as shown in the channel map Figure 3 When the first device moves to any grid in the channel map, the second device can trigger the first request message to request to obtain the basis information corresponding to the first device. Among them, the basis information is determined based on the channel map. For example, the second device can determine that the spatio-frequency joint basis is the first basis based on the path angle-delay information of the channel map. Optionally, if the core network device is an AMF, for example, the second device sends a first request message to the AMF; the AMF is equivalent to a router for the second device to communicate with the LMF / MMF, so the second device requests to obtain the channel map from the LMF / MMF through the AMF. Correspondingly, the LMF / MMF can send the channel map to the second device through the AMF. Therefore, after the second device obtains the channel map, it can determine the first basis based on the channel map.

[0173] S102, the second device sends a first reference signal; correspondingly, the first device receives the first reference signal.

[0174] Among them, the first reference signal is used to measure channel information, which can specifically be a downlink reference signal. The downlink reference signal can include, for example, CSI-RS, synchronization signal / physical broadcast channel block (SSB), or demodulation reference signal (DMRS), etc.

[0175] Optionally, the density of the first reference signal is positively correlated with the number of columns of the first basis. Specifically, the density ρ of the first reference signal is proportional to the number of columns L of the first basis. For example, the smaller L is, the smaller ρ is. It can be understood that the smaller the number of columns L of the first basis, the fewer the number of channel multipaths, and thus the fewer the values for which channel measurement is required. Correspondingly, the fewer the reference signals to be transmitted. Therefore, the density ρ of the first reference signal is proportional to the number of columns L of the first basis. For example, assume that the first basis is a spatio-frequency combined basis U, and the spatio-frequency combined basis corresponding to the first device is known. Among them, M is the number of antennas of the second device, L is the number of channel multipaths, and N is the number of frequency units. The second device sets the density ρ of the first reference signal based on the number of columns L of the spatio-frequency combined basis U, which can be to reduce the frequency-domain granularity from N to N 1 , thereby reducing the overhead of the reference signal.

[0176] S103. The first device determines a first channel matrix based on the first reference signal.

[0177] S104. The first device determines a first superimposed coefficient vector based on the first channel matrix and the second basis constructed from the position index of the first reference signal in the spatio-frequency domain in the corresponding rows of the first basis.

[0178] Among them, the first device can obtain the first channel matrix as the channel state information of the first reference signal in the corresponding spatio-frequency domain dimensions through channel estimation based on the first reference signal. For example, assume that the first reference signal is a CSI-RS signal. The first device performs channel estimation on this CSI-RS signal to obtain the first channel matrix h in the spatio-frequency domain dimensions. s Among them, the dimension of the first channel matrix is M×N 1 ×1. For example, h s satisfies M is the spatial granularity of the first reference signal (such as the number of antennas), and N 1 is the frequency-domain granularity of the first reference signal (such as the number of subcarriers or the number of RBs or the number of RBGs or the number of subbands, etc.).

[0179] Among them, the second basis constructed from the position index of the first reference signal in the spatio-frequency domain in the corresponding rows of the first basis is denoted as Us Among them, the dimension of the second basis is MN 1 ×L. For example, U s satisfies For example, the first device receives the first reference signal and can determine the position index of the first reference signal in the space-frequency domain; based on the position index of the first reference signal in the space-frequency domain (M and N 1 ), obtain the row corresponding to this position index from the first basis to form the second basis U s .

[0180] Among them, the first superposition coefficient vector is determined based on the first channel matrix and the corresponding row of the first basis of the position index of the first reference signal in the space-frequency domain, and satisfies formula (17):

[0181] c = pinv(U s )×h s (17)

[0182] Among them, c is the first superposition coefficient vector, h s is the first channel matrix, U s is the second basis, and pinv(A) represents the pseudo-inverse of matrix A. Optionally, formula (17) is only an example, and the first superposition coefficient vector can also satisfy a deformation based on formula (17), or satisfy other generation methods based on h s and U s , which is not limited in this application. Among them, the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L*1, and L is a positive integer; for example, c satisfies Optionally, the superposition coefficient vector represents the projection coefficient of the channel matrix on the basis.

[0183] S105, the first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0184] Among them, the second superposition coefficient vector includes K superposition coefficients, and the K superposition coefficients are the K elements with the largest amplitudes in the first superposition coefficient vector. K is a positive integer less than or equal to L. For example, it is known that the first superposition coefficient vector includes L superposition coefficients. Assuming that the K elements with the largest amplitudes among the L superposition coefficients form the second superposition coefficient vector c′, then c′ satisfies K satisfies 0 < K ≤ L. It can be understood that the K elements with the largest amplitudes among the L superposition coefficients satisfy that these K coefficients are greater than the L - K superposition coefficients among the L superposition coefficients other than these K coefficients; for example, assuming the L superposition coefficients are 1, 3, 4, 6, 2, 5, then L = 6; assuming K = 3, then the K elements with the largest amplitudes among all the elements of the L superposition coefficients include 4, 5, 6, that is, the second superposition coefficient vector includes three elements, which are 4, 5, 6 respectively.

[0185] Among them, the second basis selection vector includes the position indexes of the K superposition coefficients in the first superposition coefficient vector. For example, assuming the L superposition coefficients are 1, 3, 4, 6, 2, 5, then L = 6; assuming K = 3, then the second superposition coefficient vector includes three superposition coefficients, which are 4, 5, 6 respectively. The position indexes of these three superposition coefficients in the first superposition coefficient vector are 3, 6, 4 respectively, that is, the second basis selection vector includes three elements, which are 3, 4, 6 respectively.

[0186] Optionally, the first device sends the second superposition coefficient vector and the second basis selection vector. For example, the first device can send the second superposition coefficient vector and the second basis selection vector to the second device by using PUCCH / PUSCH. Optionally, the first device can report the second superposition coefficient vector in a short period, and the first device can report the second basis selection vector in a short period or a long period, which is not limited in this application.

[0187] It can be seen that the first device only needs to feedback K superposition coefficients (similar to the short - period superposition coefficients shown in Figure 8 ), and the position indexes of these K superposition coefficients in the first superposition coefficient vector (indicating the position indexes in the first basis), which is beneficial to reducing the feedback overhead. For example, since the second device knows the channel map and the first basis, the first device only needs to feedback the position indexes in the first basis, rather than the indexes of one or more basis vectors constituting the first basis and the long - period coefficients (such as the long - period superposition coefficients shown in Figure 8 ), thus reducing the feedback overhead.

[0188] In this embodiment, the first basis is the region - level channel basis provided by the channel map, and the second device sends the first basis to the first device as prior information, which is beneficial to reducing the reference signal overhead. And the first device only feedbacks the position indexes in the first basis and the short - period superposition coefficients, which is beneficial to reducing the feedback overhead.

[0189] I. The channel basis update method provided by this application:

[0190] Among them, the first device can multiply the second superposition coefficient vector by the third basis to obtain the second channel matrix, that is, to recover the CSI information. Further, the first device can determine the historical channel basis associated with the historical CSI information based on the recovered CSI information and the historical CSI information, and update the channel basis (such as updating the first basis) based on the historical channel basis.

[0191] For example, the channel basis update method provided in this application includes the following steps:

[0192] (1) The first device multiplies the second superposition coefficient vector by the third basis to obtain the second channel matrix. Among them, the third basis is composed of the corresponding columns of the first basis at K position indexes in the second basis selection vector. For example, the second channel matrix satisfies formula (18):

[0193] h = U′ × c′ (18)

[0194] Among them, h is the second channel matrix, U′ is the third basis, and c′ is the second superposition coefficient vector. For example, the second device obtains the corresponding columns of the first basis at the K position indexes according to the K position indexes in the second basis selection vector, and forms the third basis U′ with the corresponding columns. The dimension of the third basis is MN×K. For example, U′ satisfies Optionally, the second channel matrix can also satisfy the deformation of formula (18), or other implementation manners of generating the second channel matrix based on the second superposition coefficient vector and the third basis are not limited in this application.

[0195] (2) The first device determines the fourth basis based on multiple third channel matrices. Among them, the third channel matrix is the channel state information in the spatial-frequency domain dimension obtained by channel estimation based on the second reference signal. The second reference signal is the reference signal received before the first reference signal, and the second reference signal and the first reference signal are reference signals of the same type. For example, the second reference signal is the reference signal received before the first reference signal, that is, the second reference signal is the historical reference signal; among them, the second reference signal can be the reference signal received at the previous moment before the first device receives the first reference signal, or multiple reference signals received at several previous moments before receiving the second reference signal, which is not limited in this application. And the second reference signal and the first reference signal are reference signals of the same type (for example, if the first reference signal is CSI-RS, the second reference signal is also CSI-RS). The first device can obtain the third channel matrix in the spatial-frequency domain dimension by performing channel estimation based on the second reference signal. Since for the channel h represented by a column vector, its statistical covariance matrix satisfies formula (5), the statistical covariance matrix of the third channel matrix satisfies formula (19):

[0196]

[0197] Among them, R h is the statistical covariance matrix of the third channel matrix, and U h is the matrix composed of the eigenvectors of the covariance matrix R h (i.e., the fourth basis).

[0198] (3) The first device determines that the subspace where the fourth basis and the first basis intersect is the first common subspace. Among them, the subspace where the fourth basis and the first basis intersect is also called the common subspace of the fourth basis and the first basis. For example, the common subspace of the fourth basis U h and the first basis U is denoted as V (i.e., the first common subspace is V), and any vector v in V satisfies formula (20):

[0199]

[0200] Among them, P U =U(U H U) -1 U H is the projection matrix of U, is the projection matrix of U h .

[0201] (4) The first device determines the first non-common subspace, and the first non-common subspace includes the subspace of the fourth basis excluding the first common subspace. Among them, the subspace of the fourth basis excluding the first common subspace is also called the non-common subspace, or the subspace of the fourth basis orthogonal to the first common subspace. For example, the non-common subspace of the fourth basis U h excluding the first common subspace V is D, which satisfies formula (21):

[0202]

[0203] Among them, D is the first non-common subspace, represents the direct sum of subspaces.

[0204] (5) The first device sends the indication information of the first non-common subspace; correspondingly, the second device receives the indication information of the first non-common subspace. Among them, the indication information of the first non-common subspace indicates the projection coefficient of the first non-common subspace on the quantization basis of the first non-common subspace and the column index of the quantization basis of the first non-common subspace. Among them, the first non-common subspace is composed of L 1 column vectors. For example, the quantization basis of the first non-common subspace is any one of the DFT codebook, FFT codebook, oversampled DFT codebook, oversampled FFT codebook, or the codebook determined based on a preset rule, and the column vectors of the first non-common subspace are determined based on the above codebook.

[0205] Optionally, the implementation methods of the indication information of the first non-common subspace and the indication information of the first basis are similar; for example, the indication information of the first non-common subspace includes the first non-common subspace. That is, the first device directly sends the first non-common subspace D to the second device. For another example, the indication information of the first non-common subspace includes the projection coefficients of the first non-common subspace on the quantization basis of the first non-common subspace and the column indices of the quantization basis of the first non-common subspace. That is, the first device indirectly indicates the first non-common subspace to the second device. Assume that the first non-common subspace D can adopt an oversampled DFT basis W d for projection quantization (that is, the quantization basis of the first non-common subspace is the oversampled DFT basis W d ), then the first non-common subspace D satisfies formula (22):

[0206] D = W d C d (22)

[0207] where C d represents the projection coefficients of D on the oversampled DFT basis. Based on formula (22), the indication information of the first non-common subspace can include the projection coefficients C d , and the column indices of the quantization basis of the first non-common subspace. Optionally, the oversampled DFT basis W d is known and the same for both the first device and the second device.

[0208] (6) The second device performs Schmidt orthogonalization on the first basis and the first non-common subspace to obtain the fifth basis. For example, the second device receives the indication information of the first non-common subspace, and the indication information of the first non-common subspace includes the projection coefficients C d , and the column indices of the quantization basis of the first non-common subspace. The second device can restore the first non-common subspace D = W d C d , and determine that the fifth basis satisfies formula (23):

[0209] U p = oth{[U W d C d} (23)

[0210] where U p represents the fifth basis, and the dimension of the fifth basis is MN×(K + L 1 ), for example, U p satisfies oth{A} represents performing Schmidt orthogonalization on each column of matrix A. Among them, since quantization may destroy the orthogonality between the columns of the basis, orthogonalization processing is required.

[0211] Optionally, the second device sends indication information of the fifth basis. The implementation manner of the indication information of the fifth basis and the indication information of the first basis is similar; for example, the indication information of the fifth basis includes the fifth basis, then the second device sends the fifth basis U to the core network device p Correspondingly, the core network device receives the fifth basis U p . For another example, the indication information of the fifth basis includes the projection coefficients of the fifth basis on the quantization basis of the fifth basis and the column indices of the quantization basis of the fifth basis. Optionally, the second device may send indication information of the first non-common subspace (for example, directly indicating D or indicating W d and C d ), and the first basis U is known to the core network device. After receiving the indication information of the first non-common subspace, the core network device can also determine the fifth basis. That is, the second device indirectly indicates the fifth basis to the core network device. Optionally, the core network device is, for example, an AMF, and the AMF is equivalent to a router for the second device to communicate with the LMF / MMF. Then the second device sends the fifth basis U to the LMF / MMF through the AMF p . Optionally, the LMF / MMF can update the channel map based on the fifth basis U p ; for example, update the path angle-delay information of the corresponding grid in the channel map based on the path angle-delay information corresponding to the fifth basis.

[0212] Optionally, the first basis, the second basis, the third basis, the fourth basis, or the fifth basis described in the above second part and third part are of the same type of basis. The same type of basis is: a joint spatio-frequency basis, or, a spatial domain basis and a frequency domain basis. Among them, the joint spatio-frequency basis is a matrix constructed by one or more spatio-frequency domain basis vectors; the spatial domain basis is a matrix constructed by one or more spatial domain basis vectors, and the frequency domain basis is a matrix constructed by one or more frequency domain basis vectors. For example, assuming that the first basis is a joint spatio-frequency basis, then the first basis is a matrix constructed by one or more spatio-frequency domain basis vectors, which can represent the common characteristics of the spatial domain and the frequency domain; for another example, assuming that the first basis is a spatial domain basis and a frequency domain basis, then the first basis includes a matrix constructed by one or more spatial domain basis vectors and a matrix constructed by one or more frequency domain basis vectors (for example, a set of matrices), respectively representing the characteristics of the spatial domain and the frequency domain.

[0213] In this embodiment, the first device can determine the historical channel basis associated with the historical CSI information based on the recovered CSI information and the historical CSI information, and update and report the channel basis based on the historical channel basis, so that both the second device and the core network device can obtain the updated channel basis information, which is beneficial to improving the accuracy of channel estimation.

[0214] II. Interaction process between the first device and the second device when different reference signals are used and whether the channel basis is updated:

[0215] Example 1: Assume that the first reference signal is CSI-RS and the channel basis is not updated:

[0216] In this Example 1, the second device uses the region-level channel basis provided by the channel map as prior information (for example, the first basis can be a spatio-frequency joint basis U, a spatial domain basis U S , a frequency domain basis U F , or it can also be a spatial domain compression matrix W s , a frequency domain compression matrix W f , etc. Example 1 takes the spatio-frequency joint basis U as an example for illustration), and sends the region-level channel basis and the first reference signal; correspondingly, the first device calculates the short-period coefficient based on the region-level channel basis and the first reference signal, and reports the short-period coefficient and the position index in the first basis. The second device restores the full-dimensional CSI according to the full-dimensional channel basis provided by the map, the short-period coefficient, and the position index in the first basis.

[0217] For example, Figure 10 is a schematic diagram of a downlink channel reconstruction process enabled by combining a channel map and CSI-RS provided by this application. This process is realized by the interaction between the first device, the second device, and the core network device. The core network device in this application can be AMF / LMF / MMF. This process includes the following steps:

[0218] S201. The second device sends a first request message to the core network device. This first request message requests to obtain the channel map or requests to obtain the basis information of the first device in the channel map; correspondingly, the core network device receives the first request message.

[0219] S202. The core network device sends a first response message to the second device. This first response message includes the channel map or the basis information of the first device in the channel map; correspondingly, the second device receives the first response message.

[0220] For example, the channel map is as Figure 3As shown, when the first device moves to any grid in the channel map, the second device can trigger a first request message to request the entire channel map or request the base information corresponding to the first device in the channel map. The base information is determined based on the channel map. For example, based on the path angle-delay information of the channel map, the spatio-frequency joint base can be determined. Then, the spatio-frequency joint base corresponding to the first device is determined based on the path angle-delay information of the grid where the first device is located. Optionally, the core network device includes, for example, AMF / LMF / MMF. The interaction between the second device and the core network device can refer to the corresponding description in S101 and will not be elaborated here.

[0221] S203. The second device sends the indication information of the first base; correspondingly, the first device receives the indication information of the first base.

[0222] The specific implementation manner of S202 can refer to the corresponding description in S101. For example, assuming that the first base is the spatio-frequency joint base U, the second device uses PDCCH / PDSCH to send the spatio-frequency joint base corresponding to the first device to the first device or sends the column index of the first base in the quantization base of the first base and C to the first device 13 , which will not be elaborated here.

[0223] Optionally, when the first base is the spatial domain base U S , the frequency domain base U F , it can also be the spatial domain compression matrix W s , the frequency domain compression matrix W f , etc., the processing flow is similar to the flow described in S101. For example, assuming that the first base includes the spatial domain base U S and the frequency domain base U F , the second device sends the spatial domain base U S and the frequency domain base U F corresponding to the first device to the first device, or sends the projection coefficients of the spatial domain base U S and the frequency domain base U F in the quantization base B of the first base respectively, and the column index of the first quantization base.

[0224] S204. The second device sends the CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0225] Among them, the specific implementation of S203 can refer to the corresponding description in S102. For example, the second device sends a CSI-RS signal to the first device for downlink channel measurement. Optionally, the density ρ of the CSI-RS signal is proportional to the number of columns L of the first basis. For example, the second device can reduce the density of the CSI-RS signal, thereby reducing the overhead of the CSI-RS signal.

[0226] S205, the first device determines a first channel matrix based on the CSI-RS signal.

[0227] S206, the first device determines a first superposition coefficient vector based on the first channel matrix and a second basis constructed from the position indices of the CSI-RS signal in the corresponding rows of the first basis in the spatial-frequency domain.

[0228] Among them, the specific implementation of S205 and S206 can refer to the corresponding description in S103 and S104. For example, the first device estimates the corresponding first channel matrix based on the received CSI-RS signal and searches for the corresponding rows in the first basis according to the position indices of the CSI-RS signal in the spatial-frequency domain to form the second basis so as to determine the first superposition coefficient vector c.

[0229] S207, the first device determines a second superposition coefficient vector and a second basis selection vector based on the first superposition coefficient vector.

[0230] S208, the first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0231] Among them, the specific implementation of S207 and S208 can refer to the corresponding description in S105. For example, the first device selects the K superposition coefficients with the largest amplitudes from the first superposition coefficient vector to form the second superposition coefficient vector, and determines the K position indices of these K superposition coefficients in the first superposition coefficient vector to form the second basis selection vector. The first device sends the second superposition coefficient vector (including K superposition coefficients) and the second basis selection vector (including K index values) to the second device.

[0232] S209, the second device multiplies the second superposition coefficient vector by the second basis to obtain a second channel matrix.

[0233] Among them, the specific implementation of S209 can refer to the description of the second channel matrix in the third part, which will not be elaborated here. Therefore, the second device realizes the recovery of CSI information.

[0234] Optionally, when the first reference signal is other downlink reference signals (such as SSB / DMRS, etc.) and the channel map is not updated, the specific implementation process is similar to that of Example 1. For example, replacing the first reference signal CSI-RS with other downlink reference signals, and the other processes remain unchanged, which will not be elaborated here.

[0235] In this Example 1, the first basis is the region-level channel basis provided by the channel map. The second device sends the first basis to the first device as prior information, which helps to reduce the reference signal overhead. Moreover, the first device only feeds back the position index and short-period superposition coefficient at the position of the first basis, which can reduce the feedback overhead compared with feeding back the entire channel basis.

[0236] Example 2: Assume that the first reference signal is CSI-RS, and the scheme for updating the channel map:

[0237] Based on Example 1, this Example 2 adds a process in which the first device calculates the statistical channel basis according to the historical CSI reconstruction result, updates and reports the information of the newly added channel basis, thereby realizing the update of the channel basis information, which is beneficial to improving the channel reconstruction accuracy.

[0238] For example, Figure 11 is a schematic diagram of a process for enabling downlink channel reconstruction and channel basis update by combining a channel map with CSI-RS provided by this application. This process is realized by the interaction among the first device, the second device, and the core network device. This process includes the following steps:

[0239] S301. The second device sends a first request message to the core network device. This first request message requests to obtain the channel map, or requests to obtain the basis information corresponding to the first device in the channel map. Correspondingly, the core network device receives the first request message.

[0240] S302. The core network device sends a first response message to the second device. This first response message includes the channel map, or the basis information corresponding to the first device in the channel map. Correspondingly, the second device receives the first response message.

[0241] S303. The second device sends the indication information of the first basis. Correspondingly, the first device receives the indication information of the first basis.

[0242] S304. The second device sends the CSI-RS signal. Correspondingly, the first device receives the CSI-RS signal.

[0243] S305. The first device determines the first channel state information based on the CSI-RS signal.

[0244] S306. The first device determines a first superposition coefficient vector based on a second basis constructed from the first channel state information corresponding to the CSI-RS signal and the position index of the CSI-RS signal in the spatial-frequency domain in the corresponding row of the first basis.

[0245] S307. The first device determines a second superposition coefficient vector and a second basis selection vector based on the first superposition coefficient vector.

[0246] S308. The first device sends the second superposition coefficient vector and the second basis selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second basis selection vector.

[0247] S309. The second device multiplies the second superposition coefficient vector by a third basis to obtain a second channel matrix.

[0248] For the specific implementation manners of the above S301 - S309, reference can be made to the corresponding descriptions in S101 - S105 and S201 - S209, which will not be elaborated here.

[0249] S310. The first device determines a fourth basis based on the third channel matrix.

[0250] For the specific implementation manner of this step, reference can be made to the descriptions of the fourth basis and the third channel matrix in the third part. For example, the third channel matrix is the channel state information in the spatial-frequency domain obtained by channel estimation based on a second reference signal; the second reference signal is the reference signal received before the first reference signal, that is, the second reference signal is a historical reference signal; the second reference signal and the first reference signal are of the same type of reference signal (for example, if the first reference signal is CSI-RS, then the second reference signal is also CSI-RS); the fourth basis satisfies formula (19), and other related descriptions, which will not be elaborated here.

[0251] S311. The first device determines the common subspace where the fourth basis and the first basis intersect as the first common subspace.

[0252] S312. The first device determines a first non-common subspace, and the first non-common subspace includes the subspace of the fourth basis excluding the first common subspace.

[0253] For the specific implementation manners of S311 and S312, reference can be made to the descriptions of the first non-common subspace, the first common subspace, and the common subspace where the fourth basis and the first basis intersect in the third part. For example, the first non-common subspace D satisfies formula (21), the first common subspace V is the common subspace of the fourth basis U h and the first basis U, and any vector v in V satisfies formula (20), and other related descriptions, which will not be elaborated here.

[0254] S313, the first device sends indication information of a first non-common subspace; correspondingly, the second device receives the indication information of the first non-common subspace.

[0255] For the specific implementation of S313, reference can be made to the description of the indication information of the first non-common subspace in Part III. For example, the first device directly sends the first non-common subspace D to the second device, or sends the projection coefficients of the first non-common subspace on the quantization basis of the first non-common subspace and the column indices of the quantization basis of the first non-common subspace to the second device, as well as other related descriptions, which will not be elaborated here.

[0256] S314, the second device performs Schmidt orthogonalization on the first basis and the first non-common subspace to obtain a fifth basis.

[0257] S315, the second device sends indication information of the fifth basis to the core network device.

[0258] For the specific implementation of S314 and S315, reference can be made to the description of the fifth basis and the indication information of the fifth basis in Part III. For example, the fifth basis U p satisfies formula (23), as well as other related descriptions, which will not be elaborated here.

[0259] Optionally, when the first reference signal is other downlink reference signals (such as SSB / DMRS, etc.) and the channel map is not updated, the specific implementation process is similar to that of Example 2. For example, the first reference signal is replaced by other downlink reference signals such as CSI-RS, and other processes remain unchanged, which will not be elaborated here.

[0260] In this Example 2, the first basis is the region-level channel basis provided by the channel map. The second device distributes the first basis to the first device as prior information, which helps to reduce the reference signal overhead. Moreover, the first device only feeds back the position index and short-period superposition coefficients at the position of the first basis, which can reduce the feedback overhead compared with feeding back the entire channel basis. Additionally, the first device can update and report the channel basis based on historical CSI information and the recovered CSI information, which helps to further update the channel map and improve the accuracy of the channel map.

[0261] Example 3: Assume that the first reference signal is CSI-RS, and the first device sends a third reference signal to enable the second device to perform channel estimation based on the first reference signal and the third reference signal:

[0262] This Example 3 is based on Example 1, and adds a process in which the first device sends a third reference signal (such as the uplink reference signal SRS) to enable the second device to perform channel estimation based on the third reference signal and recover CSI, which helps to improve the CSI reconstruction accuracy.

[0263] For example, Figure 12 FIG. Figure 12 is a schematic diagram of a downlink channel reconstruction process enabled by combining a channel map with CSI-RS and SRS. This process is implemented through the interaction between a first device, a second device, and a core network device. This process includes the following steps:

[0264] S401, the second device sends a first request message to the core network device. This first request message requests to obtain a channel map, or requests to obtain base information corresponding to the first device in the channel map; correspondingly, the core network device receives the first request message.

[0265] S402, the core network device sends a first response message to the second device. This first response message includes the channel map, or the base information corresponding to the first device in the channel map; correspondingly, the second device receives the first response message.

[0266] S403, the second device sends indication information of a first base; correspondingly, the first device receives the indication information of the first base.

[0267] S404, the second device sends a CSI-RS signal; correspondingly, the first device receives the CSI-RS signal.

[0268] S405, the first device determines a first channel matrix based on the CSI-RS signal.

[0269] S406, the first device determines a first superposition coefficient vector based on the first channel matrix and a second base constructed from the position index of the CSI-RS signal in the spatial-frequency domain in the corresponding row of the first base.

[0270] S407, the first device determines a second superposition coefficient vector and a second base selection vector based on the first superposition coefficient vector.

[0271] S408, the first device sends the second superposition coefficient vector and the second base selection vector; correspondingly, the second device receives the second superposition coefficient vector and the second base selection vector.

[0272] For the specific implementation manners of the above S401 - S408, reference can be made to the corresponding descriptions in S101 - S105 and S201 - S208, which will not be elaborated here.

[0273] S409, the second device sends first indication information; correspondingly, the first device receives the first indication information.

[0274] S410, the first device sends a third reference signal based on the first indication information; correspondingly, the second device receives the third reference signal.

[0275] Among them, the third reference signal is used to measure channel information, which may specifically be an uplink reference signal. For example, the uplink reference signal may include SRS, etc., which is not limited in this application.

[0276] Among them, the first indication information indicates the frequency-domain position of the third reference signal. For example, assuming that the third reference signal is SRS, the first indication information indicates the frequency-domain position of SRS, such as indicating the frequency-domain unit (such as RE / RB, etc.) carrying SRS.

[0277] Optionally, the first indication information may also indicate the resource pattern of the third reference signal. For example, assuming that the third reference signal is SRS, the second device may indicate the resource pattern of the uplink reference signal (such as SRS pattern) to the first device through the first indication information.

[0278] Optionally, the first indication information indicates the density of the third reference signal; the density of the third reference signal is positively correlated with the length of the second superimposed coefficient vector. Specifically, the density of the third reference signal is proportional to the length of the second superimposed coefficient vector. For example, the smaller the length of the second superimposed coefficient vector, the fewer the number of channel multipaths, and thus the fewer the values that need to be measured for channel measurement; correspondingly, the fewer the reference signals that need to be sent, and the smaller the density of the third reference signal. Optionally, the second device may set the density of the third reference signal based on the length of the second superimposed coefficient vector. For example, the spatial granularity of the third reference signal is reduced from M to M 2 , and the frequency-domain granularity is reduced from N to N 2 , thereby reducing the overhead of the reference signal.

[0279] S411, the second device determines a fourth channel matrix based on the third reference signal.

[0280] S412, the second device determines a third superimposed coefficient vector based on the fourth channel matrix and the sixth basis constructed from the corresponding rows of the first basis at the position index of the third reference signal in the spatio-frequency domain.

[0281] Among them, the second device may perform channel estimation based on the third reference signal, and the obtained fourth channel matrix is the channel state information of the third reference signal in the spatio-frequency domain. For example, assuming that the third reference signal is an SRS signal, the first device performs channel estimation on the SRS signal, and the obtained fourth channel matrix in the spatio-frequency domain is Among them, the dimension of the fourth channel matrix is M 2 N 2 ×1. For example, Satisfy M 2 Is the spatial granularity of the third reference signal, and N 2 Is the frequency-domain granularity of the third reference signal.

[0282] Among them, the position index of the third reference signal in the spatial-frequency domain is the sixth basis constructed from the corresponding row of the first basis as Among them, the dimension of the sixth basis is M 2 N 2 ×L. For example, Satisfy For example, the second device receives the third reference signal and can determine the position index of the third reference signal in the spatial-frequency domain; based on the position index of the third reference signal in the spatial-frequency domain (M 2 and N 2 ), obtain the corresponding row of the position index from the first basis to form the sixth basis Among them, the number of columns of the sixth basis is the same as that of the first basis.

[0283] Among them, the third superposition coefficient vector is determined based on the fourth channel matrix and the sixth basis constructed from the corresponding row of the first basis corresponding to the position index of the third reference signal in the spatial-frequency domain, and satisfies formula (24):

[0284]

[0285] Among them, c srs is the third superposition coefficient vector, is the fourth channel matrix, is the sixth basis, and pinv(A) represents the pseudo-inverse of matrix A. Optionally, formula (24) is only an example, and the third superposition coefficient vector can also satisfy the deformation based on formula (24), or satisfy other generation methods based on and , which are not limited in this application. Among them, the third superposition coefficient vector includes E superposition coefficients, the dimension of the third superposition coefficient vector is E*1, and E is a positive integer; for example, c srs satisfies

[0286] S413. The second device determines the fourth superposition coefficient vector and the fourth basis selection vector.

[0287] Among them, the fourth superposition coefficient vector includes F superposition coefficients, and the F superposition coefficients are the F elements with the largest amplitudes in the third superposition coefficient vector. F is a positive integer less than or equal to E. The fourth basis selection vector includes the position indices of the F superposition coefficients in the third superposition coefficient vector (such as including F index values). It can be understood that the specific implementation manners of the fourth superposition coefficient vector and the fourth basis selection vector are similar to those of the second superposition coefficient vector and the second basis selection vector, and can refer to the corresponding descriptions above, which will not be elaborated here.

[0288] S414. The second device multiplies the fourth superposition coefficient vector by the seventh basis to obtain the fifth channel matrix.

[0289] Among them, the seventh basis is composed of the corresponding columns of the fifth basis indexed by F positions in the fourth basis selection vector. For example, similar to formula (18), the fifth channel matrix satisfies formula (25):

[0290] h srs = U' p × c' srs (25)

[0291] Among them, h srs is the fifth channel matrix, U' p is the seventh basis, and c' srs is the fourth superposition coefficient vector. For example, the second device obtains the corresponding columns of the fifth basis indexed by the F positions in the fourth basis selection vector, and forms the seventh basis U' p from the corresponding columns. The dimension of the seventh basis is MN × F. For example, U' p satisfies Optionally, the fifth channel matrix may also satisfy a deformation of formula (25), or other implementation manners of generating the fifth channel matrix based on the fourth superposition coefficient vector and the seventh basis are not limited in this application.

[0292] In this Example 3, the first basis is the region-level channel basis provided by the channel map. The second device sends the first basis to the first device as prior information, which helps to reduce the reference signal overhead. Moreover, the first device only feeds back the position indices and short-period superposition coefficients in the first basis, which can reduce the feedback overhead compared with feeding back the entire channel basis. In addition, the first device can also send an uplink reference signal, so that the second device can recover the CSI based on the uplink reference signal and the downlink reference signal, which helps to improve the CSI reconstruction accuracy.

[0293] Example 4: Assume that the first reference signal is CSI-RS, and the first device sends a third reference signal to enable the second device to perform channel estimation and channel basis update based on the first reference signal and the third reference signal:

[0294] Based on Example 3, this Example 4 adds a process in which the second device calculates the statistical channel basis according to the historical CSI reconstruction result, updates and reports the new channel basis information, thereby realizing the update of the channel basis information, which helps to improve the channel reconstruction accuracy.

[0295] For example, Figure 13 is a schematic diagram of a process for enabling downlink channel reconstruction and channel basis update by combining a channel map with CSI-RS and SRS provided by this application. This process is implemented through the interaction among the first device, the second device, and the core network device. This process includes the following steps:

[0296] S501. The second device sends a first request message to the core network device. The first request message requests to obtain a channel map or requests to obtain the base information corresponding to the first device in the channel map. Correspondingly, the core network device receives the first request message.

[0297] S502. The core network device sends a first response message to the second device. The first response message includes the channel map or the base information corresponding to the first device in the channel map. Correspondingly, the second device receives the first response message.

[0298] S503. The second device sends indication information of the first base. Correspondingly, the first device receives the indication information of the first base.

[0299] S504. The second device sends a CSI-RS signal. Correspondingly, the first device receives the CSI-RS signal.

[0300] S505. The first device determines a first channel matrix based on the CSI-RS signal.

[0301] S506. The first device determines a first superposition coefficient vector based on the second base constructed from the corresponding row of the first base according to the first channel matrix and the position index of the CSI-RS signal in the spatial-frequency domain.

[0302] S507. The first device determines a second superposition coefficient vector and a second base selection vector based on the first superposition coefficient vector.

[0303] S508. The first device sends the second superposition coefficient vector and the second base selection vector. Correspondingly, the second device receives the second superposition coefficient vector and the second base selection vector.

[0304] S509. The second device sends first indication information. Correspondingly, the first device receives the first indication information.

[0305] S510. The first device sends a third reference signal based on the first indication information. Correspondingly, the second device receives the third reference signal.

[0306] For the specific implementation manners of the above S501 - S510, reference can be made to the corresponding descriptions in S101 - S105 and S401 - S410, which will not be elaborated here.

[0307] S511. The second device determines a fourth channel matrix based on the third reference signal.

[0308] For example, assuming that the third reference signal is an SRS signal, the first device performs channel estimation on the SRS signal, and a fourth channel matrix in the spatial-frequency domain dimension can be obtained. Among them, the dimension of the fourth channel matrix is M 2 N2 ×1, for example, Meet M 2 Is the spatial domain granularity of the third reference signal, and N 2 Is the frequency domain granularity of the third reference signal.

[0309] S512. The second device determines the eighth basis based on multiple sixth channel matrices.

[0310] Among them, the sixth channel matrix is the channel state information in the spatial-frequency domain dimension obtained by channel estimation based on the fourth reference signal. The fourth reference signal is the reference signal received before the third reference signal, and the fourth reference signal and the third reference signal are reference signals of the same type. For example, the fourth reference signal is the reference signal received before the third reference signal, that is, the fourth reference signal is a historical reference signal; among them, the fourth reference signal can be the reference signal received at the previous moment before the second device receives the third reference signal, or can be multiple reference signals received at several previous moments before receiving the third reference signal, which is not limited in this application. And, the fourth reference signal and the third reference signal are reference signals of the same type (for example, if the third reference signal is SRS, then the fourth reference signal is also SRS). The second device can obtain the sixth channel matrix in the spatial-frequency domain dimension by performing channel estimation based on the fourth reference signal. Since for the channel h represented by a column vector, its statistical covariance matrix satisfies formula (5), the statistical covariance matrix of the sixth channel matrix also satisfies formula (19).

[0311] S513. The second device determines that the common subspace where the eighth basis and the first basis intersect is the second common subspace.

[0312] S514. The first device determines the second non-common subspace, and the second non-common subspace includes the subspace of the eighth basis excluding the second common subspace.

[0313] Among them, the common subspace where the eighth basis and the first basis intersect is also called the second common subspace. For example, any vector v in the second common subspace also satisfies formula (20). Among them, the subspace of the eighth basis excluding the second common subspace is also called the second non-common subspace, or is called the subspace of the eighth basis orthogonal to the second common subspace. For example, the second non-common subspace of the eighth basis excluding the second common subspace also satisfies formula (21).

[0314] S515. The second device performs Schmidt orthogonalization on the fifth basis and the second non-common subspace to obtain the ninth basis.

[0315] S516. The second device sends the indication information of the ninth basis; correspondingly, the core network device receives the indication information of the ninth basis.

[0316] For example, similar to formula (23), the second device determines that the ninth basis satisfies formula (26):

[0317] U p′ = oth{[U p D′]} (26)

[0318] where U p′ represents the ninth basis, and the dimension of the ninth basis is MN×(K + L 1 + L 2 ). For example, U p′ satisfies U p represents the fifth basis, and D′ represents the second non-common subspace.

[0319] Optionally, the second device sends indication information of the ninth basis. The implementation manner of the indication information of the ninth basis and the indication information of the first basis is similar; for example, the indication information of the ninth basis includes the ninth basis, then the second device sends the ninth basis U p′ , correspondingly, the core network device receives the ninth basis U p′ . Also for example, the indication information of the ninth basis includes the projection coefficients of the ninth basis on the quantization basis of the ninth basis and the column index of the quantization basis of the ninth basis. Optionally, the second device may send indication information of the second non-common subspace (for example, directly indicating D′ or indicating the column index of the quantization basis of the second non-common subspace and the projection coefficients of the second non-common subspace), and the fifth basis U p is known to the core network device, then after receiving the indication information of the second non-common subspace, the core network device can also determine the ninth basis. That is, the second device indirectly indicates the ninth basis to the core network device. Optionally, the core network device is, for example, an AMF, and the AMF is equivalent to a router for the second device to communicate with the LMF / MMF, then the second device sends the ninth basis to the LMF / MMF through the AMF. Optionally, the LMF / MMF can update the channel map based on the ninth basis; for example, based on the path angle-delay information corresponding to the ninth basis, update the path angle-delay information of the corresponding grid in the channel map.

[0320] S517. The second device determines the fifth superposition coefficient vector based on the fourth channel matrix and the spatial-frequency position of the SRS signal in the corresponding row of the ninth basis.

[0321] where the fifth superposition coefficient vector includes P superposition coefficients, and P is a positive integer. The specific implementation manner of this step can refer to the corresponding description in S104. For example, the second device determines the corresponding row of the ninth basis by looking up the position index of the SRS signal in the spatial-frequency domain, and determines that the fifth superposition coefficient vector satisfies formula (27):

[0322]

[0323] where c srs ′ is the fifth superposition coefficient vector, is the fourth channel matrix, which is composed of the corresponding rows of the ninth basis at the position indices of the third reference signal in the space-frequency domain.

[0324] In S518, the second device determines the sixth superposition coefficient vector and the sixth basis selection vector.

[0325] Among them, the sixth superposition coefficient vector includes Q superposition coefficients, and the Q superposition coefficients are the Q elements with the largest amplitudes among all the elements in the fifth superposition coefficient vector. The sixth basis selection vector includes the position indices of the Q superposition coefficients in the fifth superposition coefficient vector, and Q is a positive integer less than or equal to P.

[0326] The specific implementation manner of this step can refer to the description in S104. For example, the sixth superposition coefficient vector is c′ src , which is similar to the implementation manner of the second superposition coefficient vector, and the sixth basis selection vector is similar to the implementation manner of the second basis selection vector.

[0327] In S519, the second device multiplies the sixth superposition coefficient vector by the tenth basis to obtain the sixth channel matrix.

[0328] Among them, the tenth basis is composed of the corresponding columns of the ninth basis at the Q position indices in the sixth basis selection vector. For example, the specific implementation manner of this step can refer to the specific implementation manner of the second channel matrix described in the third part. Similar to formula (18), the sixth channel matrix satisfies formula (28):

[0329] h′ srs = U′ p′ × c′ srs (28)

[0330] where h′ srs is the sixth channel matrix, c′ srs is the sixth superposition coefficient vector, and U′ p′ is the tenth basis. For example, the second device obtains the corresponding columns of the ninth basis at the Q position indices according to the Q position indices in the sixth basis selection vector, and forms the tenth basis U′ p′ , and the dimension of the tenth basis is MN × Q. For example, U′ p′ satisfies Optionally, the sixth channel matrix can also satisfy the deformation of formula (28), or other implementation manners of generating the sixth channel matrix based on the sixth superposition coefficient vector and the tenth basis are not limited in this application.

[0331] In the fourth example, the first base is the region-level channel base provided by the channel map. The second device sends the first base to the first device as prior information, which helps reduce the reference signal overhead. Moreover, the first device only feeds back the position index and short-period superposition coefficients at the first base, which helps reduce the feedback overhead. Additionally, the first device can also send an uplink reference signal so that the second device can recover the CSI based on the uplink reference signal and the downlink reference signal, which helps improve the CSI reconstruction accuracy. Furthermore, the first device can update and report the channel base based on the historical CSI information and the recovered CSI information, which helps further update the channel map and improve the accuracy of the channel map.

[0332] Example 5: Assume a scenario where the first device sends a third reference signal to enable the second device to perform channel estimation and channel base update:

[0333] The channel estimation scheme provided in this Example 5 can be a scheme where the second device directly performs channel estimation and channel base update based on the SRS (not based on CSI-RS), which can improve the channel reconstruction accuracy.

[0334] For example, Figure 14 is a schematic diagram of a channel map combined with SRS enabling channel reconstruction and channel base update process provided by this application. This process is implemented through the interaction between the first device, the second device, and the core network device. This process includes the following steps:

[0335] S601. The second device sends a first request message to the core network device. This first request message requests to obtain the channel map or requests to obtain the base information corresponding to the first device in the channel map. Correspondingly, the core network device receives the first request message.

[0336] S602. The core network device sends a first response message to the second device. This first response message includes the channel map or the base information corresponding to the first device in the channel map. Correspondingly, the second device receives the first response message.

[0337] For the specific implementation manners of the above S601 and S602, reference can be made to the corresponding descriptions in S101 and S102 as well as S201 and S202, which will not be elaborated here.

[0338] S603. The second device sends first indication information. Correspondingly, the first device receives the first indication information.

[0339] S604. The first device sends an SRS signal based on the first indication information. Correspondingly, the second device receives the SRS signal.

[0340] S605. The second device determines a fourth channel matrix based on the SRS signal.

[0341] S606. The second device determines an eighth basis based on multiple sixth channel matrices.

[0342] S607. The second device determines that the common subspace where the eighth basis and the first basis intersect is the second common subspace.

[0343] S608. The first device determines a second non - common subspace, and the second non - common subspace includes the subspace of the eighth basis excluding the second common subspace.

[0344] S609. The second device performs Schmidt orthogonalization on the fifth basis and the second non - common subspace to obtain a ninth basis.

[0345] S610. The second device sends indication information of the ninth basis; correspondingly, the core network device receives the indication information of the ninth basis.

[0346] S611. The second device determines a fifth superposition coefficient vector based on the fourth channel matrix and the spatial - frequency position of the SRS signal in the corresponding rows of the ninth basis.

[0347] S612. The second device determines a sixth superposition coefficient vector and a sixth basis selection vector.

[0348] S613. The second device multiplies the sixth superposition coefficient vector by the tenth basis to obtain a sixth channel matrix.

[0349] Among them, the specific implementation manners of S603 - S613 can refer to the corresponding descriptions in S509 - S519, which will not be elaborated here.

[0350] In this Example 5, the first basis is the area - level channel basis provided by the channel map, and the second device sends the first basis to the first device as prior information, which is beneficial to reducing the reference signal overhead. Moreover, without considering the downlink reference signal, the first device can send an uplink reference signal so that the second device can also realize channel reconstruction based on the uplink reference signal SRS. In addition, the first device can update the channel basis based on the information of historical SRS signals and the information of current SRS signals, which is beneficial to further updating the channel map and improving the accuracy of the channel map.

[0351] It can be understood that, in order to implement the functions in the above - mentioned embodiments, the base station and the terminal include corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should easily realize that, combining the units and method steps of each example described in the embodiments disclosed in this application, this application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the way of hardware or computer software driving hardware depends on the specific application scenarios and design constraint conditions of the technical solution.

[0352] Figure 15 and Figure 16 FIG. 4 is a schematic structural diagram of a possible communication device provided for an embodiment of the present application. These communication devices can be used to implement the functions of the terminal or the base station in the above method embodiments, and thus can also achieve the beneficial effects possessed by the above method embodiments. In the embodiments of the present application, the communication device can be, for example Figure 1 as shown in Figure 1 terminal 120, or can be, for example

[0353] as Figure 15 shown in FIG. 5, base station 110, or can also be a module (such as a chip) applied to the terminal or the base station. Figures 9 to 14 As shown in FIG. 6, the communication device 1500 includes a processing unit 1510 and a transceiver unit 1520. The communication device 1500 is used to implement the functions of the terminal or the base station in the method embodiment shown above. Optionally, the transceiver unit 1520 can also be referred to as a communication unit. Optionally, the transceiver unit includes a transmitting unit and a receiving unit. The transmitting unit is used to transmit signals, and the receiving unit is used to receive signals.

[0354] For example, when the communication device 1500 is used to implement the functions of the terminal in the method embodiment shown in Figure 9 FIG. 7: The transceiver unit 1520 is used to receive the indication information of the first basis. The indication information of the first basis indicates the projection coefficient of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis. The processing unit 1510 is used to determine and record the first basis. The transceiver unit 1520 is further used to receive the first reference signal, and the processing unit 1510 is further used to determine the first channel matrix based on the first reference signal. The processing unit 1510 is further used to determine the first superposition coefficient vector based on the second basis constructed by the first channel matrix and the position index of the first reference signal in the spatial-frequency domain in the corresponding row of the first basis. The processing unit 1510 is further used to select the K superposition coefficient vectors with the largest amplitudes from the first superposition coefficient vectors to form the second superposition coefficient vector, and determine the position index of the K superposition coefficient vectors in the first superposition coefficient vector to form the second basis selection vector. The transceiver unit 1520 is further used to transmit the second superposition coefficient vector and the second basis selection vector.

[0355] Again, for example, when the communication device 1500 is used to implement the method shown in Figure 9When implementing the functions of the network device in the method embodiments shown: The transceiver unit 1520 is used to send the indication information of the first basis, and the indication information of the first basis indicates the projection coefficients of the first basis on the quantization basis of the first basis and the column index of the quantization basis of the first basis. The transceiver unit 1520 is also used to send a first reference signal, so that the receiving end of the first reference signal can perform channel estimation based on the first reference signal to obtain a first channel matrix, and the receiving end of the first reference signal can determine a first superposition coefficient vector based on the first channel matrix and the position index of the first reference signal in the spatial-frequency domain in the second basis constructed by the corresponding rows of the first basis, thereby determining that the K superposition coefficient vectors with the largest amplitudes in the first superposition coefficient vector form a second superposition coefficient vector, and the position indices of the K superposition coefficient vectors in the first superposition coefficient vector form a second basis selection vector. The transceiver unit 1520 is also used to receive the second superposition coefficient vector and the second basis selection vector. The processing unit 1510 is used to process the data received by the transceiver unit 1520.

[0356] For a more detailed description of the above processing unit 1510 and transceiver unit 1520, reference can be made to Figure 9 the relevant descriptions in the method embodiments shown.

[0357] Optionally, when the communication device 1500 is used to implement Figures 10 to 14 the functions of the terminal or the base station in the method embodiments, for a more detailed description of the above processing unit 1510 and transceiver unit 1520, reference can be made to Figures 10 to 14 the relevant descriptions in the method embodiments shown, which will not be elaborated here.

[0358] As Figure 16 shown, the communication device 1600 includes a processor 1610 and an interface circuit 1620. The processor 1610 and the interface circuit 1620 are coupled to each other. It can be understood that the interface circuit 1620 can be a transceiver or an input / output interface. Optionally, the communication device 1600 may further include a memory 1630, which is used to store the instructions executed by the processor 1610 or store the input data required for the processor 1610 to run the instructions or store the data generated after the processor 1610 runs the instructions. Sometimes, the interface circuit 1620 can also be understood as a part of the processor 1610, and in this case, the communication device 1600 includes the processor 1610.

[0359] When the communication device 1600 is used to implement Figure 9 the method shown, the processor 1610 is used to implement the functions of the above processing unit 1510, and the interface circuit 1620 is used to implement the functions of the above transceiver unit 1520. Optionally, when the communication device 1600 is used to implement Figures 10 to 14When implementing the method shown, the implementation manners of the processor 1610 and the interface circuit 1620 refer to the corresponding descriptions in the method embodiments, and will not be elaborated here.

[0360] When the above communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from a base station. It can be understood that the information is first received by other modules (such as a radio frequency module or an antenna) in the terminal and then sent by these modules to the terminal chip. The terminal chip sends information to the base station. It can be understood that the information is first sent to other modules (such as a radio frequency module or an antenna) in the terminal and then sent by these modules to the base station.

[0361] When the above communication device is a chip applied to a base station, the base station chip implements the functions of the base station in the above method embodiments. The base station chip receives information from a terminal. It can be understood that the information is first received by other modules (such as a radio frequency module or an antenna) in the base station and then sent by these modules to the base station chip. The base station chip sends information to the terminal. It can be understood that the information is sent to other modules (such as a radio frequency module or an antenna) in the base station and then sent by these modules to the terminal.

[0362] In this application, when entity A sends information to entity B, it can be that A directly sends to B, or A indirectly sends to B through other entities. Similarly, when entity B receives information from entity A, it can be that entity B directly receives the information sent by entity A, or entity B indirectly receives the information sent by entity A through other entities. Here, entity A and B can be RAN nodes or terminals, or modules inside RAN nodes or terminals. The sending and receiving of information can be information interaction between a RAN node and a terminal. For example, information interaction between a base station and a terminal; the sending and receiving of information can also be information interaction between two RAN nodes. For example, information interaction between a CU and a DU; the sending and receiving of information can also be information interaction between different modules within a device. For example, information interaction between a terminal chip and other modules of the terminal, or information interaction between a base station chip and other modules in the base station.

[0363] It can be understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0364] The method steps in the embodiments of the present application may be implemented in hardware or in software instructions executable by a processor. The software instructions may be composed of corresponding software modules, and the software modules may be stored in a random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, removable hard disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium may also be a component of the processor. The processor and the storage medium may be located in an ASIC. Additionally, the ASIC may be located in a base station or a terminal. The processor and the storage medium may also exist as discrete components in a base station or a terminal.

[0365] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable devices. The computer program or instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium can be any available medium that can be accessed by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it can also be an optical medium, such as a digital video disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or can include both volatile and non-volatile types of storage media.

[0366] In various embodiments of the present application, if there is no special explanation and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0367] It can be understood that the various numerical numbers involved in the embodiments of the present application are only for the convenience of description and do not limit the scope of the embodiments of the present application. The magnitudes of the sequence numbers of the above processes do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic.

[0368] In the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. In the text description of the present application, the character " / " generally represents an "or" relationship between the associated objects before and after; in the formula of the present application, the character " / " represents a "division" relationship between the associated objects before and after. "Including at least one of A, B, and C" can represent: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

Claims

1. A communication method, characterized in that, the method comprises: receiving indication information of a first basis, the indication information of the first basis indicating projection coefficients of the first basis on a quantization basis of the first basis and column indexes of the quantization basis of the first basis; the first basis is composed of L column basis vectors, and L is a positive integer; receiving a first reference signal and determining a first channel matrix based on the first reference signal; Determine a first superposition coefficient vector based on a second basis constructed from corresponding rows of the first basis at positions in the spatial-frequency domain of the first channel matrix and the first reference signal, where the dimension of the first channel matrix is M×N 1 *1, and the dimension of the second basis is M×N 1 *L, where M is the number of antenna ports receiving the first reference signal, and N 1 is the number of frequency-domain units carrying the first reference signal; the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L×1, and M and N 1 are positive integers, and L is less than or equal to M×N 1 ; transmitting a second superposition coefficient vector and a second basis selection vector, the second superposition coefficient vector including K superposition coefficients, the K superposition coefficients being the K elements with the largest amplitudes in the first superposition coefficient vector; the second basis selection vector includes position indexes of the K superposition coefficients in the first superposition coefficient vector, and K is a positive integer less than or equal to L.

2. The method according to claim 1, characterized in that, the method further comprises: multiplying the second superposition coefficient vector by a third basis to obtain a second channel matrix; the third basis is composed of corresponding columns of the first basis at K position indexes in the second basis selection vector.

3. The method according to claim 1, characterized in that, the method further comprises: determining a fourth basis based on a third channel matrix, the third channel matrix being channel state information in the spatial-frequency domain dimension obtained by channel estimation based on a second reference signal, the second reference signal being a reference signal received before the first reference signal, and the second reference signal and the first reference signal being reference signals of the same type; determining a first non-common subspace, the first non-common subspace including a subspace of the fourth basis excluding a first common subspace, the first common subspace being a common subspace where the fourth basis and the first basis intersect; Send the indication information of the first non-common subspace, where the indication information of the first non-common subspace indicates the projection coefficients of the first non-common subspace on the quantization basis of the first non-common subspace and the column indices of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L 1 column basis vectors, and the L 1 is a positive integer.

4. The method according to any one of claims 1 to 3, characterized in that, the method further comprises: receiving first indication information, the first indication information indicating a frequency-domain position for transmitting a third reference signal; transmitting the third reference signal based on the first indication information.

5. The method according to any one of claims 1 to 3, characterized in that, the first basis, the second basis, the third basis, the fourth basis, or the fifth basis is a same-type basis, and the same-type basis is: a spatial-frequency joint basis, or, a spatial domain basis and a frequency domain basis; wherein, the spatial-frequency joint basis is a matrix constructed by one or more spatial-frequency domain basis vectors; the spatial domain basis is a matrix constructed by one or more spatial domain basis vectors, and the frequency domain basis is a matrix constructed by one or more frequency domain basis vectors.

6. The method according to any one of claims 1 to 3, characterized in that, the basis vector is any one of a discrete Fourier transform (DFT) basis vector, a fast Fourier transform (FFT) basis vector, an oversampled DFT basis vector, an oversampled FFT basis vector, or a vector determined based on a preset rule.

7. A communication method, characterized in that, the method comprises: Send indication information of a first basis, where the indication information of the first basis indicates projection coefficients of the first basis on a quantization basis of the first basis and column indexes of the quantization basis of the first basis; the first basis is composed of L column basis vectors, and L is a positive integer; Send a first reference signal; Receive a second superposition coefficient vector and a second basis selection vector, where the second superposition coefficient vector includes K superposition coefficients, and the K superposition coefficients are the K elements with the largest magnitudes in the first superposition coefficient vector; the second basis selection vector includes the position indices of the K superposition coefficients in the first superposition coefficient vector, and the first superposition coefficient vector is obtained from a second basis constructed from the corresponding rows of the first basis based on the position indices of the first channel matrix and the first reference signal in the spatial-frequency domain, and the first channel matrix is determined based on the first reference signal; wherein, the dimension of the first channel matrix is M×N 1 *1, and the dimension of the second basis is M×N 1 *L, where M is the number of antenna ports transmitting the first reference signal, and N 1 is the number of frequency-domain units carrying the first reference signal; the first superposition coefficient vector includes L superposition coefficients, the dimension of the first superposition coefficient vector is L×1, and M and N 1 are positive integers, L is less than or equal to M×N 1 , and K is a positive integer less than or equal to L.

8. The method according to claim 7, wherein, the method further includes: Multiply the second superposition coefficient vector by a third basis to obtain a second channel matrix; the third basis is composed of corresponding columns of the first basis at K position indexes in the second basis selection vector.

9. The method according to claim 7, wherein, the method further includes: Receive indication information of a first non-common subspace, where the indication information of the first non-common subspace indicates projection coefficients of the first non-common subspace on a quantization basis of the first non-common subspace and column indexes of the quantization basis of the first non-common subspace; the first non-common subspace is composed of L 1 column basis vectors, and the L 1 is a positive integer; Perform Schmidt orthogonalization processing on the first basis and the first non-common subspace to obtain a fifth basis; Send the indication information of the fifth basis, where the indication information of the fifth basis indicates the fifth basis, or indicates the projection coefficient of the fifth basis on the quantization basis of the fifth basis and the column index of the quantization basis of the fifth basis; the fifth basis is composed of (L + L 1 ) column vectors.

10. The method according to any one of claims 7 to 9, wherein, the method further includes: Send first indication information, where the first indication information indicates a frequency domain position for sending a third reference signal; Receive a third reference signal.

11. The method according to any one of claims 7 to 9, wherein, The first basis, the second basis, the third basis, the fourth basis, or the fifth basis is a same type of basis, and the same type of basis is: a spatio-frequency joint basis, or, a spatial domain basis and a frequency domain basis; the spatio-frequency joint basis is a matrix constructed by one or more spatio-frequency domain basis vectors; the spatial domain basis is a matrix constructed by one or more spatial domain basis vectors, and the frequency domain basis is a matrix constructed by one or more frequency domain basis vectors.

12. The method according to any one of claims 7 to 9, wherein, The basis vector is any one of a discrete Fourier transform (DFT) basis vector, a fast Fourier transform (FFT) basis vector, an oversampled DFT basis vector, an oversampled FFT basis vector, or a vector determined based on a preset rule.

13. A communication device, wherein, It includes a communication unit and a processing unit, and the communication unit and the processing unit are used to execute the method according to any one of claims 1 to 6 or 7 to 12.

14. A communication device, wherein, It includes a processor and an interface circuit, the interface circuit is used to receive signals from other communication devices and transmit them to the processor or send signals from the processor to other communication devices, and the processor is used to implement the method according to any one of claims 1 to 6 or 7 to 12 through logic circuits or by executing code instructions.

15. A computer-readable storage medium, wherein, The computer-readable storage medium stores a computer program or instructions, and when the computer program or instructions are executed by a communication device, the method according to any one of claims 1 to 6 or 7 to 12 is implemented.

16. A chip system, wherein, The chip system includes a processor and an interface, and the processor is used to execute a computer program so that the chip system implements the method according to any one of claims 1 to 6 or 7 to 12.

17. A computer program product, wherein, Comprising instructions that, when executed on a computer, cause the computer to perform the method according to any one of claims 1 to 6 or 7 to 12.

18. A communication system, characterized in that the communication system comprises means for performing the method according to any one of claims 1 to 6 and means for performing the method according to any one of claims 7 to 12.

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