Communication method based on multiple terminals, storage medium, and electronic device

Abstract

The application discloses a kind of communication method based on multiple terminals, storage medium and electronic equipment.Communication technical field is related, the method includes: based on the pCSI- RS and downlink CSI- RS of target terminal, the first uplink CSI of target terminal is determined;Based on the pCSI- RS of other terminal sent by base station, the phase of the uplink CSI of other terminal is obtained;According to the first uplink CSI of target terminal, the phase of the uplink CSI of other terminal, obtain global uplink CSI matrix;Based on global uplink CSI matrix, the uplink precoding weight corresponding to target terminal is obtained;Based on uplink precoding weight, by the mode of coherent transmission with other terminal, target data stream is sent to base station.The application solves the technical problem that distributed low-power terminal in related art cannot efficiently obtain uplink channel information, leading to the inability to achieve efficient uplink coherent cooperative transmission.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more specifically, to a communication method, storage medium, and electronic device based on multiple terminals. Background Technology

[0002] In wireless communication systems, especially in cell edge scenarios, uplink transmission performance is generally poor due to limited transmit power at terminals. To improve uplink throughput and coverage, Cooperative Joint Transmission (CJT) technology has been proposed in recent years. This technology uses multiple terminals to transmit the same data stream on the same time-frequency resources, forming a virtual distributed antenna array, thus achieving a trade-off between beamforming gain and multiplexing gain. However, the implementation of this technology heavily relies on terminals accurately acquiring uplink channel state information (CSI) and achieving time-frequency synchronization and transmit / receive reciprocity calibration among terminals. In Time Division Duplex (TDD) systems, theoretically, uplink CSI can be derived from downlink CSI using uplink and downlink channel reciprocity. However, in practice, factors such as hardware differences between terminals, local oscillator frequency offset, clock drift, and inconsistent path propagation delays severely disrupt channel reciprocity between terminals and the base station. In related technologies, uplink CSI is estimated solely by receiving uplink sounding reference signals (SRS) from each terminal at the base station. However, this information is only held by the base station and cannot be effectively distributed to distributed terminals. Consequently, terminals cannot obtain uplink channel phase information from other terminals, making it impossible to collaboratively design globally optimal precoding. Therefore, in related technologies, each terminal struggles to obtain a complete uplink CSI matrix (including its own and other terminals' channels to the base station), resulting in the inability to achieve truly distributed coherent beamforming. The uplink performance of low-power terminals at the cell edge remains severely limited, and efficient long-distance multi-terminal uplink coherent cooperative transmission is difficult to achieve. Currently, no effective solution has been proposed to address these issues. Summary of the Invention

[0003] This invention provides a communication method, storage medium, and electronic device based on multiple terminals, to at least solve the technical problem in related technologies where distributed low-power terminals cannot efficiently obtain uplink channel information, thus preventing the realization of efficient uplink coherent cooperative transmission.

[0004] According to one aspect of the present invention, a communication method based on multiple terminals is provided, comprising: determining a first uplink channel state information (CSI) of the target terminal based on a precoded channel state information reference signal pCSI-RS of a target terminal among multiple terminals transmitted by a base station, and a downlink channel state information reference signal CSI-RS corresponding to the target terminal, wherein pCSI-RS is used for reciprocity calibration between the corresponding terminal and the base station; obtaining the phase of the uplink CSI of other terminals based on pCSI-RS of other terminals transmitted by the base station, wherein the other terminals are terminals other than the target terminal among the multiple terminals; obtaining a global uplink CSI matrix from the multiple terminals to the base station according to the first uplink CSI of the target terminal and the phase of the uplink CSI of other terminals; obtaining the uplink precoding weight corresponding to the target terminal based on the global uplink CSI matrix; and transmitting a target data stream to the base station by coherent transmission with other terminals based on the uplink precoding weight, wherein coherent transmission is used to instruct the multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, so as to form a transmission gain of a virtual distributed antenna array on the multiple terminal side.

[0005] According to another aspect of the present invention, a communication method based on multiple terminals is also provided, comprising: transmitting downlink CSI-RS corresponding to each of the multiple terminals to a corresponding terminal; transmitting pCSI-RS corresponding to each of the multiple terminals to a corresponding terminal; receiving a target data stream transmitted by the multiple terminals based on corresponding uplink precoding weights via coherent transmission, wherein the uplink precoding weights are obtained based on the global uplink CSI matrix of the corresponding terminal, the global uplink CSI matrix representing the uplink CSI matrix from the multiple terminals to the base station, the global uplink CSI matrix being obtained based on the first uplink CSI of the corresponding terminal and the phase of the uplink CSIs of other terminals besides the corresponding terminal; the first uplink CSI being obtained based on the pCSI-RS and CSI-RS of the corresponding terminal; the phase of the uplink CSIs of other terminals being obtained based on the corresponding pCSI-RS; and coherent transmission being used to instruct the multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, so as to form a transmission gain of a virtual distributed antenna array on the multiple terminal side.

[0006] According to another aspect of the present invention, a non-volatile storage medium is also provided, which stores a plurality of instructions adapted for a communication method based on multiple terminals to be loaded by a processor and executed at any one of them.

[0007] According to another aspect of the present invention, an electronic device is also provided, including one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement any one of the communication methods based on multiple terminals.

[0008] According to another aspect of the present invention, a computer program product is also provided, including a computer program that, when executed by a processor, implements the steps of any of the communication methods based on multiple terminals.

[0009] In this embodiment of the invention, the first uplink channel state information (CSI) of the target terminal is determined based on the precoded channel state information reference signal pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink channel state information reference signal CSI-RS corresponding to the target terminal. The pCSI-RS is used for reciprocity calibration between the corresponding terminal and the base station. Based on the pCSI-RS of other terminals transmitted by the base station, the phase of the uplink CSI of other terminals is obtained, wherein the other terminals are terminals other than the target terminal among multiple terminals. According to the first uplink CSI of the target terminal and the phase of the uplink CSI of other terminals, a global uplink CSI matrix from multiple terminals to the base station is obtained. Based on the global uplink CSI matrix, the uplink precoding weight corresponding to the target terminal is obtained. Based on the uplink precoding weight, the target data stream is sent to the base station by coherent transmission with other terminals. Coherent transmission is used to instruct multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights. This forms a virtual distributed antenna array transmission gain on the multiple terminal sides, achieving the goal of long-distance uplink communication for distributed low-power terminals. This is achieved by having the terminals reconstruct the global uplink CSI matrix based on pCSI-RS and CSI-RS and autonomously calculate the precoding weights, enabling multiple terminals to spatially coherently transmit the same data stream on the same time-frequency resources. This realizes the technical effect of spatially coherently superimposing the same target data stream on the same time-frequency resources by multiple low-power terminals, improving the equivalent array gain of the base station receiver, and achieving efficient uplink coherent cooperative transmission of distributed low-power terminals. This solves the technical problem in related technologies where distributed low-power terminals cannot efficiently obtain uplink channel information, resulting in the inability to achieve efficient uplink coherent cooperative transmission. Attached Figure Description

[0010] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0011] Figure 1This is a flowchart of a communication method based on multiple terminals according to an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of uplink coherent joint transmission communication between an optional base station and multiple terminals according to an embodiment of the present invention.

[0013] Figure 3 This is a flowchart of a communication method based on multiple terminals according to an embodiment of the present invention;

[0014] Figure 4 This is a schematic diagram of uplink multi-stream coherent joint transmission communication between multiple nodes and multiple terminals on the base station side according to an embodiment of the present invention.

[0015] Figure 5 This is a flowchart of an optional communication method based on multiple terminals according to an embodiment of the present invention;

[0016] Figure 6 This is a schematic diagram of a communication device based on multiple terminals according to an embodiment of the present invention;

[0017] Figure 7 This is a schematic diagram of another communication device based on multiple terminals according to an embodiment of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] According to an embodiment of the present invention, a method embodiment for communication based on multiple terminals is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0021] Figure 1 This is a flowchart of a communication method based on multiple terminals according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0022] Step S102: Based on the precoded channel state information reference signal pCSI-RS of the target terminal among multiple terminals sent by the base station, and the downlink channel state information reference signal CSI-RS corresponding to the target terminal, determine the first uplink channel state information CSI of the target terminal. pCSI-RS is used for transceiver reciprocity calibration between the corresponding terminal and the base station.

[0023] The executing entity for steps S102 to S110 can be any one of multiple terminals. This embodiment's method can be applied to uplink coherent joint transmission communication scenarios between a base station and multiple terminals. Figure 2 This is a schematic diagram of an optional uplink coherent joint transmission communication between a base station and multiple terminals according to an embodiment of the present invention. Figure 2 As shown, multiple transceiver points (two transceiver panels) of a base station communicate with multiple terminals. These terminals are located at relatively large distances between the transceiver points. To improve uplink transmission power, coherent cooperative transmission can be employed. This involves multiple terminals sharing data and utilizing uplink channel information to form coherent beamforming, creating a "virtual" terminal and increasing uplink transmission power. This scenario has the following characteristics: the distances between the terminals and the base station's transceiver points are all relatively large; the distances between the multiple terminals are relatively small; and the multiple terminals and the base station's multiple transceiver points are in a quasi-synchronous state, meaning the time delay difference between all terminals and all nodes is less than the system's cyclic prefix time. To achieve uplink coherent transmission (CJT), the terminals need to obtain accurate uplink CSI. Furthermore, uplink coherent cooperative transmission primarily aims to achieve a tradeoff between beamforming gain and multiplexing gain. At low signal-to-noise ratios, it is necessary to fully exploit the beamforming gain to achieve high-performance transmission.

[0024] In this step, the base station sends its dedicated pCSI-RS to the target terminal. This signal is generated based on the terminal's uplink channel characteristics and is used as a reference signal to calibrate the reciprocity of the transceiver channels between the terminal and the base station. Simultaneously, the target terminal receives the downlink CSI-RS sent by the base station and obtains its own downlink channel state information relative to the base station based on this signal. By combining the reciprocity calibration information carried in the pCSI-RS with the downlink channel information reflected in the CSI-RS, the target terminal can determine its own antenna port's uplink channel state information relative to the base station's reference antenna port. This process does not rely on channel information from other terminals or a centralized processing unit. The transceiver reciprocity calibration is used to calculate and compensate for gain deviation and phase offset in the signal transmission and reception paths between the terminal and the base station.

[0025] Optionally, the base station includes base stations from the 3rd Generation Partnership Project (3GPP). The terminal includes user equipment, machine-type communication terminals, or IoT terminals in the 3GPP network, integrated into mobile phones, tablets, or embedded electronic devices. The terminal supports a Multiple-Input Multiple-Output (MIMO) architecture with 2 to 8 antennas, supporting simultaneous reception of CSI-RS and pCSI-RS. The base station is configured with multiple transceiver points, each containing at least one antenna port. All transceiver points and all terminals are in a quasi-synchronous state, with a latency difference less than the system cyclic prefix length. Quasi-synchronization is achieved through Precision Time Protocol (PTP) or Global Positioning System (GPS) timing to ensure that the transmission latency difference between the terminal and each transceiver point is less than the system cyclic prefix length, thereby eliminating uplink CSI phase mismatch caused by latency deviation.

[0026] Optionally, pCSI-RS is transmitted aperiodically, dynamically triggered by the base station based on the uplink CSI update frequency. Before each pCSI-RS transmission, the base station confirms that all cooperating terminals (i.e., multiple terminals) have completed SRS reporting and channel estimation. In this embodiment, by setting the precoded channel state information reference signal pCSI-RS to be transmitted aperiodically, and dynamically triggering its transmission timing by the base station based on the uplink channel state information update frequency, while confirming that all cooperating terminals have completed the reporting of the sounding reference signal SRS and channel estimation before each transmission, it is ensured that pCSI-RS is activated only when the channel state changes significantly and all terminals have accurate downlink channel estimation results. This avoids the reciprocity calibration failure problem caused by channel mismatch due to fixed-period transmission or the failure of cooperating terminals to complete channel estimation.

[0027] In one optional embodiment, determining the first uplink CSI of the target terminal based on the pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink CSI-RS corresponding to the target terminal, includes: estimating the downlink CSI of the target terminal based on the downlink CSI-RS of the target terminal; obtaining the reciprocity calibration coefficient of the target terminal relative to the reference antenna port of the base station based on the pCSI-RS of the target terminal; and performing phase compensation on the downlink CSI according to the reciprocity calibration coefficient to obtain the first uplink CSI.

[0028] In this embodiment, the target terminal independently estimates its downlink channel state information using the downlink CSI-RS sent by the base station, and calculates the reciprocity calibration coefficient of its own transmit / receive channel relative to the base station reference antenna port by combining it with the pCSI-RS sent by the same base station. Then, it performs accurate phase compensation of the downlink CSI using the reciprocity coefficient, directly reconstructing a high-precision first uplink CSI without relying on the collaborative calculation or distributed calibration of other terminals or central nodes. Thus, in a distributed architecture, a single terminal achieves autonomous and low-error acquisition of its own uplink channel. This uplink CSI serves as the core input for constructing the global uplink CSI matrix. After being fused with the uplink CSI phase information of other terminals, it supports the target terminal in generating accurate uplink precoding weights. Ultimately, it enables multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources, forming the transmission gain of a virtual distributed antenna array on the base station side. This effectively avoids the problem of cooperative beamforming failure caused by difficulties in reciprocity calibration and high costs of uplink CSI acquisition, significantly improving the long-distance uplink coherent cooperative transmission performance of low-power terminals at the cell edge.

[0029] As an optional embodiment, the number of orthogonal ports of pCSI-RS can be set to be equal to the product of the number of antenna ports on the base station side participating in cooperative reception and the total number of antenna ports of multiple terminals; the number of antenna ports on the base station side participating in cooperative reception is M, the total number of antenna ports of multiple terminals is N, the number of orthogonal ports of pCSI-RS is M×N, and each orthogonal port corresponds to a combination of a terminal antenna port and a base station antenna port. This allows the base station to independently transmit reciprocity calibration signals for each terminal-base station antenna pair, thereby achieving complete reciprocity calibration for all possible antenna links between all terminals and the base station. The target terminal obtains the amplitude and phase of the first uplink CSI based on its corresponding pCSI-RS and CSI-RS, and extracts the phase information of its uplink CSI by combining it with the pCSI-RS of other terminals. This allows for the fusion of multiple global uplink CSI matrices from the terminal to the base station, ensuring high-precision alignment of the uplink channel phase of each terminal. Based on this, the target terminal calculates the uplink precoding weights according to the global CSI matrix, and applies their respective weights to the other terminals on the same time-frequency resources (i.e., time resources and frequency resources) for spatial coherent superposition. This enables the uplink signals of multiple distributed terminals to form a joint transmission gain of a virtual distributed antenna array on the base station side, thereby effectively avoiding the phase mismatch problem caused by incomplete reciprocity calibration in multi-terminal, multi-antenna scenarios. This achieves high-precision, long-distance uplink coherent cooperative transmission, significantly improving the uplink transmission performance of low-power terminals at the cell edge and the overall spectral efficiency of the system.

[0030] As an optional implementation, the downlink CSI-RS transmitted by the base station can be configured as a multi-antenna port downlink channel state information reference signal as defined by the 3GPP 5th Generation New Radio (5G NR) standard. It can be configured as a periodic, semi-persistent, or aperiodic transmission mode, and the port mapping of the CSI-RS can follow the antenna port numbering rules defined in the technical specification TS38.211 of the 3GPP standard. Alternatively, the CSI-RS can be a beam domain CSI-RS, which performs spatial domain multiplexing through a predefined set of beam indices. Each beam index corresponds to a beam pointing to a specific spatial direction, and the beam set is dynamically configured by the base station according to the statistical characteristics of the uplink CSI. In this embodiment, the base station transmits downlink channel state information reference signals (CSI-RS) using multiple antenna ports as defined in the 3GPP 5G NR standard. The configuration supports periodic, semi-persistent, or aperiodic transmission modes, and the port mapping strictly follows the antenna port numbering rules specified in 3GPP TS38.211. Alternatively, it can use beam-domain CSI-RS, achieving spatial domain multiplexing through a predefined set of beam indices. Each beam index corresponds to a beam pointing in a specific spatial direction, and this beam set is dynamically configured by the base station based on the statistical characteristics of the uplink channel state information. This ensures that the downlink channel information acquired by the terminal is fully compatible with 5G in terms of protocol standardization, time-frequency resource flexibility, and spatial dimension adaptability. The NR system requires that the standardized CSI-RS transmission mechanism and spatial multiplexing strategy enable the target terminal to accurately complete the transmit-receive reciprocity calibration based on its corresponding pCSI-RS and CSI-RS, and reliably derive its own first uplink CSI. At the same time, it can accurately obtain the uplink CSI phase information of other terminals by combining their pCSI-RS, thereby constructing a high-precision, dynamically adapted global uplink CSI matrix. Ultimately, this enables multiple distributed terminals to perform spatial coherent superposition on the same time-frequency resources with cooperative precoding weights, effectively enhancing the array gain of the received signal on the base station side, significantly improving the uplink transmission performance and system spectral efficiency of low-power terminals at the cell edge, and avoiding the technical bottlenecks of inaccurate global CSI construction and unstable cooperative transmission caused by non-standard downlink channel reference signal configuration.

[0031] It should be noted that due to the frequency offset between the terminal and the reference antenna, the phase of the calibration coefficients also changes with the frequency offset. Therefore, when using the calibration coefficients, it is necessary to calculate the phase change based on the time difference between the time of use and the time of use of precoding, as well as the frequency difference between the terminal and the reference antenna, to obtain the phase of the calibration coefficients at the time of use. For this purpose, it is necessary to track the frequency offset between the terminal and the reference antenna. The reference antenna can obtain multiple frequency offsets between the terminal and the reference antenna by transmitting downlink tracking reference signals (TRS), and then calculate the change in the phase of the calibration coefficients based on the frequency offset, effectively compensating for the changes in the uplink channel.

[0032] As an optional embodiment, after each terminal obtains the reciprocity calibration coefficient based on its own downlink CSI and pCSI-RS, it further tracks the carrier frequency offset between the terminal and the base station reference antenna to dynamically compensate for the phase change of the calibration coefficient, so as to achieve time-frequency tracking of the uplink CSI. The carrier frequency offset is estimated by comparing the phase change of the pilot symbol in the downlink CSI-RS with the phase change of the corresponding pilot in the pCSI-RS, and frequency offset compensation is performed by the least squares method or Kalman filtering algorithm. In this embodiment, each terminal first obtains the first uplink channel state information of the target terminal based on the pCSI-RS and downlink CSI-RS sent by the base station, and extracts the phase information of its uplink CSI using the pCSI-RS of other terminals to construct a global uplink CSI matrix for multi-terminal collaboration to support coherent transmission. On this basis, by comparing the phase change of the pilot symbol in the downlink CSI-RS with the phase difference of the corresponding pCSI-RS pilot, the carrier frequency offset between the target terminal and the base station reference antenna is estimated in real time, and the phase drift of the calibration coefficient is dynamically compensated by the least squares method or Kalman filtering algorithm. This effectively suppresses the uplink CSI time-frequency inaccuracy problem caused by frequency offset, improves the stability and accuracy of the global uplink CSI matrix, ensures the accuracy of uplink precoding weight calculation, and finally realizes high-gain coherent cooperative transmission of multiple terminals on the same time-frequency resources, significantly improving the uplink transmission performance and long-distance cooperative communication capability of low-power terminals at the cell edge.

[0033] As an optional embodiment, after acquiring the uplink CSI, the base station performs time-domain alignment and frequency-domain alignment on the SRS of each terminal. Time-domain alignment is achieved by estimating the arrival time offset of the SRS of each terminal, and frequency-domain alignment is achieved by compensating for the frequency offset of the local oscillator of each terminal. Specifically, the time-domain alignment of SRS is calculated by cross-correlation operation to determine the peak offset between the SRS sequence of each terminal and the base station reference sequence, and the frequency-domain alignment is estimated by comparing the phase offset of the SRS pilot on a predefined subcarrier and corrected by using a frequency offset compensation filter.

[0034] In this embodiment, after acquiring the uplink channel state information of each terminal, the base station further performs time-domain and frequency-domain alignment processing on the sounding reference signals (SRS) reported by the terminals. Time-domain alignment calculates the cross-correlation peak offset between the SRS sequences of each terminal and the base station reference sequence to accurately estimate and compensate for the differences in terminal signal arrival times. Frequency-domain alignment analyzes the phase offset of the SRS pilot on predefined subcarriers to estimate the frequency deviation of the local oscillator of each terminal and uses a frequency offset compensation filter for dynamic correction. This eliminates the uplink channel phase misalignment problem caused by the inconsistency of propagation delay between terminals and local clock drift, significantly improving the time-frequency consistency and spatial coherence of the uplink CSI. This ensures that the subsequently constructed global uplink CSI matrix accurately reflects the real channel characteristics between each terminal and the base station, thereby ensuring the accuracy of uplink precoding weight calculation. This enables multiple terminals to achieve high-gain spatial coherent superposition on the same time-frequency resources, ultimately forming a stable virtual distributed antenna array reception effect on the base station side. This effectively overcomes the problem of coherent cooperation performance degradation caused by time-frequency deviation of distributed terminals, significantly improving the long-distance uplink transmission performance of low-power terminals at the cell edge and the overall system throughput.

[0035] It should be noted that when multiple terminals collaborate, the terminals need to obtain accurate channel state information. For time-division duplex systems, the reciprocity of uplink and downlink channels can be utilized; the uplink channel can be obtained from the downlink channel through reciprocity calibration. However, due to time and frequency deviations between terminals, as well as differences in terminal transceiver hardware circuits, the overall air interface channel is not reciprocal. To enable the terminal to obtain uplink channel information, reciprocity calibration and time / frequency tracking are required. One method is for the terminal to transmit an uplink sounding reference signal (SRS), allowing the base station to estimate the uplink CSI from each terminal antenna to each base station antenna. Assuming the total number of antennas for all terminals is K, and the total number of antennas for all base stations is M, then the dimension of the uplink channel matrix is ​​M×K. Specifically, calibration can be performed, but is not limited to, through any of the following methods:

[0036] Method 1: Calibration of all K antennas on the terminal is implemented only. Taking a channel of a certain subcarrier as an example, the base station uses a single port as a reference. The phase of the channel gain conjugate from all terminal antenna ports to the reference antenna port is taken as the precoding weight of the reference signal. K orthogonal precoding reference signals (pCSI-RS) are used. The design of this reference signal can adopt the demodulation reference signal (DMRS) method of 3GPP 5G NR. In this method, based on downlink CSI and reciprocity calibration, each terminal can only obtain the uplink channel information between its own antenna port and the base station antenna port.

[0037] Method 2: Achieve calibration of all antenna ports of the base station and all antenna ports of the terminal. Taking the channel of a certain subcarrier as an example, based on the channel matrix between all terminal antenna ports and all antenna ports of the base station, take the conjugate phase of all its elements as the precoding weight, and use KM orthogonal pCSI-RS. The design of pCSI-RS can adopt the demodulation reference signal (DMRS) method of 3GPP 5G NR.

[0038] Method 3: After receiving the pCSI-RS transmitted by the base station, the terminal estimates the calibration coefficients on each subcarrier. Taking Method 1 as an example, further processing using interpolation or noise reduction methods can obtain the calibration coefficients between each terminal and the reference antenna at that moment. Taking Method 2 as an example, the calibration coefficients between the terminal and each antenna in a set of base station antennas can be obtained. The network side sets one antenna port among all base station antennas as the reference antenna. From the calibration coefficients between the terminal and each antenna in the set of base station antennas, the calibration coefficients of the terminal relative to the reference antenna are determined to achieve consistency of calibration benchmarks for all terminals.

[0039] Method 4: The base station-side nodes employ massive MIMO antennas, and the antennas undergo beam consistency calibration. Based on the system's beam scanning, the base station-side nodes establish beam alignment with the terminals. In this scenario, reciprocity calibration for all terminals only requires using the beam of one node as a reference port. In this case, all nodes on the base station side use the same beam set for uplink SRS reception, downlink CSI-RS transmission, and pCSI-RS transmission. Correspondingly, the uplink and downlink channels are beam domain channels between the terminal and the base station node, and the calibration coefficients are the calibration coefficients between the terminal and the reference beam.

[0040] In an optional embodiment, before determining the uplink CSI of the target terminal based on the pCSI-RS of the target terminal among multiple terminals transmitted by the base station and the downlink CSI-RS corresponding to the target terminal, the method further includes: transmitting an uplink sounding reference signal SRS to the base station, so that the base station can determine the pCSI-RS corresponding to each of the multiple terminals, wherein the pCSI-RS is obtained based on the second uplink CSI of the corresponding terminal, and the second uplink CSI is obtained based on the SRS of the corresponding terminal.

[0041] In this embodiment, the target terminal sends an uplink sounding reference signal (SRS) to the base station, enabling the base station to accurately obtain the corresponding second uplink channel state information based on the SRS reported by each terminal. Based on this, the base station generates a precoded channel state information reference signal (pCSI-RS) corresponding to each terminal, thus providing a true and reliable channel basis for the base station to subsequently send pCSI-RS and downlink CSI-RS to the target terminal. The target terminal uses its received pCSI-RS and downlink CSI-RS, combined with the reciprocity principle, to accurately derive the first uplink CSI. Simultaneously, it obtains the phase information of its uplink CSI based on the pCSI-RS of other terminals. This process involves using information to construct a global uplink CSI matrix covering all cooperating terminals, and then calculating uplink precoding weights suitable for cooperative transmission. Ultimately, it enables coherent cooperative uplink transmission among multiple terminals based on accurate channel awareness. This process, through the SRS feedback mechanism, effectively avoids the problem of missing uplink CSI acquisition caused by difficulties in reciprocity calibration for distributed terminals, ensuring that the generation of pCSI-RS is based on evidence, improving the accuracy of the first uplink CSI and the completeness of the global CSI matrix. It overcomes the technical bottleneck in related technologies where long-distance low-power terminals cannot participate in efficient cooperative beamforming, and significantly improves the uplink transmission performance of cell edge terminals and the overall system cooperation efficiency.

[0042] As an optional embodiment, the uplink SRS transmitted by multiple terminals can be configured as the multi-antenna port uplink sounding reference signal defined by the 3GPP 5GNR standard, and the SRS is transmitted on the time-frequency resource block indicated by the base station through downlink control information (DCI). The time-frequency resource block includes at least one resource block pair, and each resource block pair contains a continuous subcarrier within a time slot and a symbol period. In this embodiment, multiple terminals transmit uplink sounding reference signals (SRS) conforming to the 3GPP 5G NR standard and complete the transmission on time-frequency resource blocks precisely indicated by the base station through downlink control information (DCI). These time-frequency resource blocks consist of at least one pair of resource blocks, each containing a continuous subcarrier within a time slot and a symbol period. This ensures that the structure and transmission timing of the uplink SRS strictly match the expected input format of the base station's side channel estimation algorithm, enabling the base station to accurately obtain the uplink channel response of each terminal based on the standard-compatible SRS. This, in turn, works with the phase information derived from pCSI-RS and CSI-RS to construct a stable and high-precision global uplink CSI matrix. Ultimately, this allows multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resource according to their respective uplink precoding weights, forming the transmission gain of a virtual distributed antenna array. This effectively overcomes the channel measurement inaccuracies and calibration drift caused by non-standard SRS formats or ambiguous resource allocation, significantly improving the reliability and gain performance of long-distance distributed terminal collaborative uplink transmission.

[0043] Optionally, when the base station uses a large-scale array antenna and completes transmit / receive beam consistency calibration, pCSI-RS, CSI-RS, and SRS are all based on the same set of predefined beams for transmission and reception. The terminal calibration reference is a reference beam of the base station, and the uplink CSI is a beam domain channel, which is represented as a set of complex gains in each beam direction. The beam set is generated by the base station based on historical SRS measurement results, and each beam corresponds to a beam index. The beam index ranges from 0 to B-1, where B is the total number of beams, and the beam direction is determined by a discretized grid of azimuth and elevation angles.

[0044] In this embodiment, when the base station deploys a massive MIMO antenna and completes transmit / receive beam consistency calibration, it uniformly uses a predefined beam set generated from historical SRS measurement results for pCSI-RS, CSI-RS, and SRS transmission and reception. A reference beam from the base station is used as the calibration benchmark for all terminals. This allows the uplink channel state information to be represented in beam domain form as a set of complex gains in each discrete beam direction. The beam direction is defined by a discretized grid composed of azimuth and elevation angles, and the beam index ranges from 0 to B-1. This transforms the complex multi-antenna port reciprocity calibration problem into a finite-dimensional... The beam gain estimation problem involves the target terminal obtaining its first uplink CSI based on its dedicated pCSI-RS and downlink CSI-RS, while inferring the phase information of its uplink CSI using the pCSI-RS of other terminals. This information is then fused to form a global uplink CSI matrix, which accurately reflects the channel response of all terminals in a unified beam domain. This avoids phase drift and calibration errors caused by inconsistencies in the transmit and receive channels, allowing terminals to collaboratively generate accurate uplink precoding weights without performing complex real-time channel inversion or additional calibration procedures. This enables multiple terminals to achieve spatial coherent superposition on the same time-frequency resources.

[0045] Optionally, when calculating pCSI-RS precoding, the base station uses one base station antenna port as a reference port and performs conjugate compensation only on the uplink CSI phase of each terminal antenna port relative to the reference port. The number of pCSI-RS quadrature ports is equal to the total number of terminal antenna ports. Alternatively, when calculating pCSI-RS precoding, the base station uses all base station antenna ports as references and performs conjugate compensation on the uplink CSI phase of each terminal-base station antenna pair. The number of pCSI-RS quadrature ports is equal to the product of the total number of terminal antenna ports and the total number of base station antenna ports.

[0046] In this embodiment, the base station achieves efficient acquisition of terminal-side reciprocity calibration and uplink CSI phase through two flexible pCSI-RS precoding strategies: First, using a single base station antenna port as a reference, conjugate compensation is performed only on the uplink CSI phase of each terminal antenna port relative to the reference port, making the number of pCSI-RS quadrature ports equal to the total number of terminal antenna ports, significantly reducing signaling overhead and terminal processing complexity, and ensuring that the terminal can quickly complete its own accurate uplink CSI calibration under low power conditions; Second, using all base station antenna ports as references, conjugate compensation is performed independently on the uplink CSI phase of each terminal-base station antenna pair, expanding the number of pCSI-RS quadrature ports to [missing information]. The product of the total number of antenna ports of the terminal and the total number of antenna ports of the base station fully preserves the phase correlation information of the multipath channels between the terminal and the base station, enabling the terminal to accurately obtain the uplink CSI phase of other terminals and support the high-fidelity construction of the global uplink CSI matrix. Through differentiated design, the two take into account system overhead and calibration accuracy respectively, and coordinate on the terminal side to realize the synchronization of key phase information required for low-complexity and high-accuracy distributed uplink coherent cooperation. This effectively avoids the bottleneck of signaling redundancy or phase inaccuracy caused by the ambiguity of the reciprocity calibration mechanism, improves the scalability of multi-terminal collaborative transmission and system resource utilization, and ultimately realizes the performance leap of long-distance uplink coherent superposition transmission of low-power terminals at the cell edge.

[0047] Step S104: Based on the pCSI-RS of other terminals sent by the base station, obtain the phase of the uplink CSI of other terminals, where other terminals are terminals other than the target terminal among multiple terminals.

[0048] In this step, the base station sends pCSI-RS signals to multiple terminals, which contain precoded information related to other terminals. The target terminal receives these pCSI-RS signals from the base station for other terminals and, based on the received signal content, obtains the phase information of the uplink channel of other terminals. This process does not rely on the target terminal's own uplink channel estimation, but rather extracts the phase characteristics of the corresponding uplink channel of other terminals by parsing the reference signals that the base station precodes and sends specifically for other terminals, thereby achieving direct acquisition of the uplink channel phase of terminals other than its own.

[0049] In one optional embodiment, obtaining the phase of the uplink CSI of other terminals based on the pCSI-RS of other terminals transmitted by the base station includes: estimating the product signal of the uplink channel phase of other terminals and the downlink CSI of the target terminal based on the pCSI-RS of other terminals; and performing phase decoupling on the product signal according to the downlink CSI of the target terminal to obtain the phase of the uplink CSI of other terminals.

[0050] Optionally, phase decoupling includes dividing the product signal by the conjugate of the downlink CSI of the target terminal to extract the phase of the uplink CSI of other terminals. The phase of the uplink CSI of other terminals is in complex form with an amplitude of 1, and only the phase information is retained to construct the global uplink CSI matrix.

[0051] In this embodiment, by utilizing the precoded channel state information reference signal pCSI-RS from other terminals transmitted by the base station, combined with the target terminal's own known downlink channel state information CSI, the product signal of the uplink channel phase of other terminals and the downlink CSI of the target terminal is first estimated. Then, based on the precise known characteristics of the target terminal's downlink CSI, phase decoupling processing is performed on this product signal, thereby directly separating the uplink channel phase information of other terminals. This process does not rely on the central node to aggregate or exchange complete channel data from each terminal, nor does it require additional signaling overhead, enabling the target terminal to operate in a distributed architecture. It autonomously completes the accurate calculation of the uplink CSI phase of other terminals and combines it with the uplink CSI amplitude measured by itself to construct a global uplink CSI matrix from multiple terminals to the base station. Then, it generates cooperative uplink precoding weights, and finally realizes that multiple terminals can spatially coherently superimpose the target data stream on the same time and frequency resources according to their respective precoding weights. This forms the transmission gain of a virtual distributed antenna array on the base station side, thereby effectively breaking through the cooperative beamforming bottleneck caused by the difficulty of reciprocity calibration and the high cost of uplink CSI acquisition for distributed terminals, and significantly improving the long-distance uplink coherent transmission performance of low-power terminals at the cell edge.

[0052] Uplink channel phase refers to the purely physical propagation phase shift of a radio signal transmitted from the antenna port of another terminal (e.g., terminal j), after passing through free space propagation, multipath reflection, fading, and other physical processes, and arriving at the base station's receiving antenna port. Uplink channel phase is determined solely by the wireless propagation environment (e.g., distance, time delay, environmental reflectors). It is an inherent, objectively existing physical property of the channel itself, and this indicator is the ideal target for achieving spatial coherent superposition. If all terminals can accurately know and apply each other's uplink channel phase, their signals can be perfectly superimposed in phase when they arrive at the base station, achieving maximum beamforming gain. The phase of uplink CSI refers to the phase component in the uplink channel state information ultimately obtained by the terminal through signal processing and used for precoding calculations. The uplink CSI phase equals the uplink channel phase plus the reciprocity calibration error phase plus the phase drift caused by frequency / time offset. In other words, the uplink CSI phase includes not only the uplink channel phase corresponding to the wireless propagation channel, but also system errors such as non-reciprocity of the terminal and base station RF front-end hardware (e.g., oscillator frequency deviation, analog circuit phase shift), and time synchronization errors. This indicator is the basis for the terminal's actual precoding operation. Due to hardware non-reciprocity, the terminal cannot directly use the downlink CSI phase as the uplink precoding phase; it must be calibrated through mechanisms such as pCSI-RS to eliminate system errors and make the uplink CSI phase as close as possible to the true uplink channel phase.

[0053] Specifically, the uplink CSI phase of other terminals j obtained by terminal i (the target terminal) is derived through a decoupling process after estimating the product signal of "uplink channel phase of other terminals j" and "downlink CSI of terminal i". This phase value includes the uplink propagation phase of other terminals j and also implicitly contains the relative calibration coefficient information obtained after pCSI-RS calibration. In other words, the uplink CSI phase in this embodiment is essentially the uplink channel phase obtained through decoupling, but after reciprocity calibration. In this embodiment, although the terminal cannot directly measure the physical uplink channel of other terminals, terminal i can reconstruct the uplink CSI phase of other terminals through the shared pCSI-RS signaling mechanism, thereby constructing a global uplink CSI matrix. This enables each terminal to calculate a coordinated precoding weight, ensuring that data streams transmitted on the same time-frequency resources achieve spatial coherent superposition at the base station, thereby forming the transmission gain of the virtual distributed antenna array.

[0054] As an optional embodiment, each terminal derives the phase of the uplink CSI of other terminals based on its own downlink CSI and the pCSI-RS received from other terminals. Then, it further estimates the relative frequency offset between other terminals and the base station by observing the changing trend of this phase in continuous time slots, and predicts the time-varying characteristics of the uplink CSI based on this frequency offset. The frequency offset estimation adopts the phase difference method within a sliding window, with a window length of K consecutive time slots, K≥3. The phase difference value is then input into the linear prediction model after median filtering to generate a prediction compensation factor. In this embodiment, each terminal derives the uplink CSI phase of other terminals based on the precoded channel state information reference signal pCSI-RS sent by the base station and its own downlink CSI-RS. Then, it dynamically collects the phase difference value by using a sliding window mechanism through the phase change trend within K consecutive time slots (K≥3). After eliminating sudden noise interference by median filtering, the filtered difference sequence is input into the linear prediction model to generate an accurate prediction compensation factor. This factor is used to correct the time-varying drift of the uplink CSI phase of other terminals caused by relative frequency offset in real time. This effectively stabilizes the temporal consistency of the global uplink CSI matrix, ensuring that the uplink precoded weights calculated by the target terminal maintain high accuracy and robustness in the long-term coherent transmission of multiple terminals. This significantly improves the stability and transmission performance of uplink cooperative beamforming gain of long-distance low-power terminals at the cell edge.

[0055] As an optional implementation, the base station transmits downlink CSI-RS, allowing the terminal to estimate the downlink channel information from the base station antenna to itself. Based on the terminal's calibration coefficients and phase differences, the uplink CSI from the terminal to all base station antennas can be obtained after calibration. This method provides the uplink CSI from the terminal itself to all base station antennas, but the terminal is unaware of the uplink CSIs from other terminals to the base station. For uplink communication, there is a lack of a central processing unit among all terminals to aggregate uplink channel information and calculate the joint uplink precoding vector. Therefore, to obtain the maximum uplink beamforming gain, one approach is for each terminal to obtain the uplink channel information from all terminals to all base station antennas.

[0056] In this embodiment, the base station can send two types of downlink reference signals to each terminal: one is the CSI-RS for obtaining downlink channel information between the base station antenna and the terminal, and the other is the pCSI-RS for reciprocity calibration. The pCSI-RS, besides enabling the terminal to obtain calibration coefficients, can also be used to obtain the phase of the uplink CSI of other terminals. Specifically, the terminal receives not only its own calibration reference signal but also calibration signals sent from the base station antenna to other terminals. The calibration signals of other terminals (i.e., pCSI-RS) contain the coupled product of the uplink channel phase of the other terminals and the target terminal's own downlink CSI. The target terminal uses its own downlink CSI estimated through CSI-RS to decouple this coupled signal, thereby obtaining the phase of the uplink CSI of other terminals. According to this embodiment, the terminal can obtain the phase of the uplink CSI of other terminals. However, due to the frequency offset between the terminal and the base station, the channel phase will drift linearly over time. To achieve accurate coherent superposition when other terminals transmit data, the target terminal not only needs to know the current uplink CSI phase of other terminals but also needs to predict the CSI phase of other terminals at future times. Therefore, the target terminal needs to estimate the frequency offset of other terminals relative to the base station by tracking the rate of change of their uplink CSI phase over time. Specifically, the target terminal can estimate the frequency offset of other terminals by observing the cumulative change of their uplink CSI phase in the time domain and separating the phase rotation component caused by their own frequency offset. Based on the estimated frequency offset of other terminals, the target terminal can calculate the change in phase over time, and then perform time-domain tracking and prediction of the uplink CSI phase of other terminals to ensure that the precoding phase used by each terminal remains synchronized with the signal phase received by the base station during multi-terminal cooperative transmission.

[0057] Step S106: Based on the first uplink CSI of the target terminal and the phase of the uplink CSI of other terminals, obtain the global uplink CSI matrix of multiple terminals to the base station.

[0058] In this step, based on the target terminal's first uplink CSI and the phase of the uplink CSIs of other terminals, a global uplink CSI matrix is ​​constructed from multiple terminals to the base station. The first uplink CSI reflects the channel response between the target terminal and all antenna ports of the base station, while the phase of the uplink CSIs of other terminals can be obtained by jointly solving the precoded channel state information reference signal (pCSI-RS) sent by the base station and the terminal's own downlink CSI-RS. This phase information does not include amplitude and is only used to recover the phase characteristics of the channels of other terminals. By combining the complete uplink CSI of the target terminal with the uplink CSI phases of the other terminals, a complete channel matrix covering all terminals to all antenna ports of the base station is formed, thereby achieving distributed aggregation of the global uplink channel state, enabling each terminal to obtain the complete channel phase relationship required for cooperative transmission with other terminals.

[0059] It should be noted that, in this embodiment, the global uplink CSI matrix is ​​used to indicate the uplink channel phase structure from multiple terminals (i.e., all cooperating terminals) to the base station, and includes a joint estimate of the target terminal's complete uplink CSI and the uplink CSI phase of other terminals. That is, the uplink CSI matrix obtained by each terminal contains two parts: its own uplink CSI to all antennas of the base station, and the uplink CSI phase information from all other terminals to all antennas of the base station derived through pCSI-RS. The phase information is in complex form, and the amplitude is a normalized value of 1. The dimension of the uplink CSI matrix can be M×(N×L), where M is the total number of antenna ports of the base station, N is the number of antenna ports of a single terminal, and L is the number of cooperating terminals. The amplitude of the non-self parts of the matrix is ​​indicated by the base station as a fixed value through signaling or set based on channel power estimates.

[0060] Step S108: Based on the global uplink CSI matrix, obtain the uplink precoding weights corresponding to the target terminal.

[0061] In this practical step, the uplink precoding weights corresponding to the target terminal are obtained based on the global uplink CSI matrix. This process calculates the precoding weights suitable for the target terminal by utilizing the uplink channel information from all terminals to all antenna ports of the base station contained in the global uplink CSI matrix, combined with the number of uplink data streams of the target terminal. Since the global uplink CSI matrix already covers the uplink channel status of all terminals, the target terminal can perform precoding design based on this complete matrix without relying on local or partial channel information. This ensures that the generated precoding weights can coordinate with all terminals participating in uplink coherent transmission, achieving optimal adaptation to the overall channel characteristics.

[0062] In one optional embodiment, the uplink precoding weights corresponding to the target terminal are obtained based on the global uplink CSI matrix, including: determining the conjugate transpose of the global uplink CSI matrix; multiplying the global uplink CSI matrix and the conjugate transpose to obtain the channel correlation matrix; and performing eigenvalue decomposition on the channel correlation matrix to obtain the uplink precoding weights.

[0063] In this embodiment, by utilizing the pCSI-RS of the target terminal and its corresponding downlink CSI-RS among multiple terminals sent by the base station, the first uplink channel state information (CSI) of the target terminal is accurately calculated. Furthermore, the phase information of the uplink CSI of other terminals is extracted based on their pCSI-RS, thereby constructing a global uplink CSI matrix covering all terminals. Subsequently, by calculating the conjugate transpose of this global uplink CSI matrix and multiplying it with the original matrix, a channel correlation matrix (or covariance matrix) characterizing the joint channel characteristics of multiple terminals is formed (used to describe the statistical correlation of signals between different antenna ports of the base station and the terminal; in this matrix, the diagonal elements represent the channel power (sum of squared gains) of the corresponding antenna port, and the off-diagonal elements represent the statistical correlation of signals between different antenna ports; if the element value is very small (e.g., close to 0), it indicates that the channels of the corresponding two antenna ports are orthogonal (independent); if the element value is very large, it indicates that the corresponding two antenna ports are highly correlated). Further eigenvalue decomposition of the channel correlation matrix is ​​performed to obtain the optimal uplink precoding weights that can be used independently by each terminal. This allows each terminal to independently derive an accurate precoding strategy that enables spatial coherent superposition without relying on the distributed computing of the central node. Ultimately, the target data stream is transmitted collaboratively on the same time-frequency resources, forming the transmission gain of a virtual distributed antenna array on the base station side. This effectively overcomes the bottleneck of collaborative beamforming caused by the difficulty of reciprocity calibration and the high cost of uplink CSI acquisition in distributed terminals, significantly improving the long-distance uplink transmission performance of low-power terminals at the cell edge and the overall energy efficiency of the system.

[0064] In one optional embodiment, when the number of target data streams is a specified number, the channel correlation matrix is ​​eigenvalued to obtain uplink precoding weights, including: performing eigenvalue decomposition on the channel correlation matrix to obtain multiple eigenvalues; and obtaining the uplink precoding weights based on the specified number of eigenvalues ​​with the largest value among the multiple eigenvalues.

[0065] In this embodiment, based on the precoded channel state information reference signal pCSI-RS of the target terminal among multiple terminals transmitted by the base station and its corresponding downlink CSI-RS, the first uplink channel state information (CSI) of the target terminal is first determined, and the phase information of its uplink CSI is obtained by combining the pCSI-RS of other terminals, thereby constructing a global uplink CSI matrix from multiple terminals to the base station. On this basis, when the number of target data streams is a specified number, eigenvalue decomposition is performed on the channel correlation matrix to extract multiple eigenvalues, and only the eigenvectors corresponding to the largest specified number of eigenvalues ​​are selected as uplink precoding weights, thereby ensuring that the generated precoding scheme strictly matches the actual number of transmitted data streams, avoiding beamforming gain loss or multiplexing efficiency reduction caused by weight dimension mismatch, and finally realizing the coordinated optimization of beamforming accuracy and system capacity in multi-terminal collaborative uplink coherent transmission, effectively improving the uplink transmission performance and reliability of long-distance cooperative communication of low-power terminals at the cell edge under conditions of difficult reciprocity calibration.

[0066] In one optional embodiment, when the number of target data streams is a specified number, the uplink precoding weights corresponding to the target terminal are obtained based on the global uplink CSI matrix, including: determining the matching degree between multiple precoding matrices in a preset codebook and the global uplink CSI matrix, wherein the codebook is a set containing multiple precoding matrices, and the column vector of each precoding matrix corresponds to a precoding direction; determining a specified number of precoding matrices with the highest matching degree from the multiple precoding matrices; and obtaining the uplink precoding weights based on the precoding directions corresponding to the specified number of precoding matrices.

[0067] In this embodiment, the first uplink CSI of the target terminal is constructed by coordinating the precoded channel state information reference signal pCSI-RS sent by the base station with the downlink CSI-RS, and the uplink CSI phase of other terminals is derived by combining the pCSI-RS of other terminals to form a global uplink CSI matrix. Then, for scenarios where the target data stream is of a specified number, a preset codebook mechanism is introduced. Each column vector in each precoded matrix in the codebook corresponds to a precoded direction (i.e., a spatial beam or spatial layer). The matching degree between each precoded matrix in the codebook and the global uplink CSI matrix is ​​evaluated, and the specified number of precoded matrices with the highest matching degree are selected. The uplink precoded weights are directly constructed by the precoded directions represented by their corresponding column vectors, thereby avoiding high-complexity matrix operations. Without relying on the high-performance computing capabilities of the terminal side, the precoded scheme required for multi-terminal collaborative uplink coherent transmission is generated efficiently and with low overhead. This ensures that long-distance uplink spatial coherent superposition can still be stably achieved under the condition of limited low-power terminal resources at the cell edge, effectively improving the base station transmission gain and the overall system throughput performance.

[0068] As an optional implementation, each terminal can be configured to use a pre-defined codebook when calculating uplink transmission precoding. The codebook is based on the codebook defined by the 3GPP 5GNR standard, and the best N precoding weight vectors are matched according to the uplink channel matrix obtained locally. The codebook is a beam codebook based on Discrete Fourier Transform (DFT), and its basis vectors are generated by DFT matrices of length P, where P is the number of physical elements of the terminal antenna array, and each precoding vector is a linear combination of DFT basis vectors. In this embodiment, each terminal uses a codebook defined by the 3GPP 5G NR standard as a precoding codebook based on the locally acquired uplink channel matrix. This codebook generates basis vectors from a discrete Fourier transform (DFT) matrix of length P, where P is the number of physical elements in the terminal antenna array. Each precoding vector is formed by a linear combination of DFT basis vectors. Thus, without relying on high-complexity operations such as eigenvalue decomposition or matrix inversion, the optimal N precoding weight vectors can be quickly selected by simply looking up a table or using a finite linear combination matching method. Combined with the global uplink CSI matrix jointly constructed by the pCSI-RS and CSI-RS issued by the base station, the terminal achieves low-complexity and low-latency uplink precoding calculation locally. This effectively avoids the bottleneck of being unable to adapt to the hardware capabilities of low-power terminals due to excessive computational overhead. Ultimately, while maintaining the uplink coherent cooperative transmission gain of multiple terminals, the overall energy efficiency and deployment feasibility of the system are significantly improved.

[0069] Uplink precoding weight calculation is implemented in a distributed manner across all terminals. The completeness of the uplink CSI obtained by each terminal allows for the calculation of the corresponding uplink precoding weights on each terminal separately. Specifically, a terminal can obtain its singular value decomposition (SFD) based on the locally obtained uplink CSI, denoted as H, as H = UDV H The uplink precoding vector is selected from the eigenvectors of the matrix V with the largest singular value, based on the number of uplink data streams. In this case, the number of uplink data streams should be less than the number of columns in the H matrix. For example, when the terminal only knows the uplink channels between itself and all base station antennas, the number of uplink data streams should be less than or equal to the minimum number of antennas for all terminals.

[0070] It should be noted that, considering the large number of terminals participating in CJT and their close proximity, multiple base station nodes participate in cooperative reception, while the nodes on the base station side are relatively far apart, and all terminals are in a synchronized state with all nodes. In this case, under the condition of sharing uplink data information, it is assumed that each terminal only knows its own uplink channel information to each base station node. Therefore, distributed precoding can be used to achieve coherent cooperative transmission in the uplink. Assume that the uplink channel from terminal k to L nodes (without loss of generality, assume L uplink data streams) is represented as h. 1,k h 2,k , h l,k, …, h L,k Then the precoded signal of terminal k can be represented as When the number of users is large and L is small, L nodes can receive and detect the uplink L data streams through a simple receiver, which will not be described in detail here.

[0071] Step S110: Based on the uplink precoding weight, the target data stream is sent to the base station through coherent transmission with other terminals. The coherent transmission is used to instruct multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, so as to form the transmission gain of a virtual distributed antenna array on the multiple terminal sides.

[0072] In this step, based on the calculated uplink precoding weights, multiple terminals transmit the same target data stream spatially in a weighted manner on the same time-frequency resources, each according to its independently acquired uplink precoding weights. This results in the coherent superposition of electromagnetic waves when the signals transmitted by each terminal reach the base station due to the phase and amplitude coordination of the precoding weights. This leads to a concentrated enhancement of signal energy at the base station receiver, which is equivalent to constructing a virtual distributed antenna array composed of dispersed terminal antennas, thereby improving the transmission gain of the target data stream at the base station.

[0073] In wireless communication systems, a data stream refers to a set of independent symbol sequences transmitted in parallel on specific time-frequency resources. Each data stream corresponds to an independent transmission channel in a spatial dimension and can be transmitted by mapping precoding vectors to antenna ports. The uplink precoding weights of other terminals are obtained by using the same method as obtaining the uplink precoding weights of the target terminal.

[0074] In one optional embodiment, the target data stream is shared by a designated terminal to terminals other than the designated terminal among multiple terminals via a designated frequency band or a designated communication link before coherent transmission is performed; or it is broadcast by the designated terminal to terminals other than the designated terminal. The designated terminal is the holder of the target data stream, the designated frequency band is a frequency band that does not participate in the coherent transmission, and the designated communication link is a communication link that does not participate in the coherent transmission.

[0075] In this embodiment, by having a designated terminal securely and reliably share the target data stream to other terminals using a designated frequency band or communication link that does not participate in uplink coherent transmission before performing coherent transmission, or by distributing the target data stream to all terminals except the designated terminal via broadcast, the strict isolation of the data sharing process from subsequent coherent transmission in terms of time and frequency resources can be effectively achieved. This avoids resource contention, signal interference, or latency jitter caused by the sharing process occupying uplink transmission resources. As a result, it ensures that the uplink precoding weights generated based on the global uplink CSI matrix can accurately guide multi-terminal collaborative coherent transmission, significantly improving the stability, reliability, and spectral efficiency of the target data stream uplink transmission in long-distance, low-power scenarios. Ultimately, this solves the technical problem of limited coherent collaborative transmission performance caused by defects in the data sharing mechanism of distributed terminals.

[0076] Optionally, after sharing uplink data information, multiple terminals employ their own calculated uplink transmission precoding to perform uplink coherent cooperative transmission on the same time-frequency resources. Uplink data information sharing is achieved through data links in other frequency bands or of different standards, including Wi-Fi, Bluetooth, device-to-device (D2D) communication, or dedicated control channels. Uplink data information sharing can also be achieved by the terminal sending data broadcasting the data stream to other cooperating terminals, with the other terminals performing decoding and forwarding. This ensures that all terminals transmit the same data vector on the same time-frequency resources, and the broadcast data stream carries the terminal identifier, data stream index, and precoding index.

[0077] Optionally, before multiple terminals perform uplink coherent cooperative transmission on the same time-frequency resources, the base station instructs each terminal on the transmit power level through downlink control signaling. Each terminal adjusts its transmit power according to the power level and its own precoding gain to achieve uplink signal power balance. The transmit power level is dynamically indicated by the Transmit Power Control (TPC) command field. The TPC field has a value range of 0 to 3, corresponding to power adjustment steps of -4dB, -1dB, +1dB, and +4dB, and the adjustment is based on the path loss estimate between the terminal and the base station and normalized.

[0078] In this embodiment, to address the uplink signal power imbalance caused by differences in precoding gain and uneven path loss among terminals during multi-terminal uplink coherent cooperative transmission, the base station dynamically issues a transmit power level indicated by the TPC field via downlink control signaling. The TPC field ranges from 0 to 3, corresponding to four power adjustment steps: -4dB, -1dB, +1dB, and +4dB. After receiving the power level instruction, each terminal performs normalization compensation calculations based on its own calculated uplink precoding gain and the estimated path loss from the terminal to the base station. This accurately adjusts the actual transmit power, ensuring that the power level of signals transmitted by all terminals on the same time-frequency resources reaches the base station after spatial coherent superposition. This effectively eliminates the fluctuations in received signal strength caused by differences in individual terminal characteristics, significantly improves the transmit gain stability and coherent synthesis efficiency of the virtual distributed antenna array on the base station side, and ultimately achieves efficient and reliable uplink cooperative transmission for long-distance low-power terminals under complex channel conditions.

[0079] Optionally, the uplink coherent cooperative transmission can be configured to use Orthogonal Frequency Division Multiplexing (OFDM) waveforms, and each terminal can transmit simultaneously on the same OFDM symbol and the same subcarrier group. The subcarrier group is determined by the base station through Resource Indicator Value (RIV). In this embodiment, the uplink coherent cooperative transmission adopts an orthogonal frequency division multiplexing (OFDM) waveform, and each terminal transmits simultaneously on the same OFDM symbol and the same subcarrier group. The subcarrier group is uniformly assigned by the base station through resource allocation assignment information (RIV). This mechanism ensures that all participating terminals synchronously transmit the target data stream modulated by their respective uplink precoding weights on precisely aligned time-frequency resources, thereby avoiding phase mismatch and signal cancellation caused by transmission timing or frequency domain position offset. This allows the base station to effectively superimpose signals from multiple distributed terminals, forming a stable virtual distributed antenna array transmission gain. This overcomes the coherence failure problem caused by misaligned time-frequency resources in traditional distributed cooperation, significantly improving the uplink transmission performance of low-power terminals at the cell edge and the reliability of long-distance coherent cooperative transmission.

[0080] Through steps S102 to S108, based on the precoded channel state information reference signal (pCSI-RS) and downlink channel state information reference signal (CSI-RS) sent by the base station, the first uplink channel state information of the target terminal is accurately derived without the need for direct exchange of channel information between terminals. Furthermore, the uplink channel phase information of other terminals is extracted using their pCSI-RS, thereby constructing a global uplink CSI matrix covering all participating terminals. Then, based on this global matrix, the uplink precoding weight of the target terminal is calculated, enabling multiple distributed terminals to operate on the same time-frequency resources with their own independent precoding weights. Spatially coherently superimposing the same target data stream ultimately forms the transmission gain of a virtual distributed antenna array on the terminal side. This effectively overcomes the technical bottleneck in related technologies where distributed terminals cannot achieve cooperative beamforming due to difficulties in reciprocity calibration and high costs of uplink CSI acquisition. It significantly improves the uplink transmission performance of low-power terminals at the cell edge, achieving long-distance, high-reliability uplink coherent cooperative transmission. This solves the problems of limited cooperative capabilities of distributed terminals, low uplink throughput of edge users, and insufficient efficiency of long-distance cooperative transmission in related technologies, achieving a synergistic optimization effect of improving the overall uplink capacity and coverage of the system and reducing terminal power consumption and signaling overhead.

[0081] Specifically, using the method in this embodiment, each terminal does not need to rely on the base station to centrally calculate or broadcast the complete uplink CSI. Instead, it can reconstruct the global uplink CSI matrix locally in a distributed manner simply by receiving pCSI-RS and CSI-RS, significantly reducing signaling overhead and the complexity of inter-terminal cooperation. By jointly deriving the uplink CSI phase of other terminals using downlink CSI and pCSI-RS, accurate estimation of the uplink channel phase of multiple terminals in a time-division duplex system is achieved. This supports multiple terminals to perform spatial coherent superposition of the same data stream on the same time-frequency resources, improving the equivalent array gain of the base station receiver. Without increasing the terminal's transmit power, the beamforming gain of the virtual distributed antenna array improves the uplink signal-to-noise ratio from the terminal to the base station, which helps to improve the uplink coverage performance and transmission reliability of low-power terminals at the cell edge.

[0082] According to embodiments of the present invention, another embodiment of a communication method based on multiple terminals is also provided. Figure 3 This is a flowchart of a communication method based on multiple terminals according to an embodiment of the present invention, such as... Figure 3 As shown, the method includes the following steps:

[0083] Step S202: Send the downlink CSI-RS corresponding to each of the multiple terminals to the corresponding terminal;

[0084] Step S204: Send the pCSI-RS corresponding to each of the multiple terminals to the corresponding terminal;

[0085] Step S206: Receive the target data stream transmitted by multiple terminals based on corresponding uplink precoding weights via coherent transmission. The uplink precoding weights are obtained based on the global uplink CSI matrix of the corresponding terminal. The global uplink CSI matrix represents the uplink CSI matrix from multiple terminals to the base station. The global uplink CSI matrix is ​​obtained based on the first uplink CSI of the corresponding terminal and the phase of the uplink CSIs of other terminals besides the corresponding terminal. The first uplink CSI is obtained based on the pCSI-RS and CSI-RS of the corresponding terminal. The phase of the uplink CSIs of other terminals is obtained based on their corresponding pCSI-RS. Coherent transmission is used to instruct multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, thereby forming the transmission gain of a virtual distributed antenna array on the multiple terminal sides.

[0086] Step S202 refers to the fact that the execution entity of step S206 can be the base station. In this embodiment, the base station sends its corresponding pCSI-RS and CSI-RS to each terminal respectively, so that each terminal can deduce its own uplink CSI to the base station by combining its received downlink CSI-RS and pCSI-RS, and further use the pCSI-RS of other terminals to obtain the phase information of the uplink channel of these terminals, thereby constructing a global uplink CSI matrix covering all cooperating terminals locally; based on this global matrix, each terminal can independently calculate the uplink precoding weight suitable for cooperative transmission, and perform spatial coherent superposition with the same data stream on the same time-frequency resources, so that the base station receiver can regard multiple physically dispersed terminal antennas as a virtual distributed array, effectively improving the uplink transmission gain, realizing the coordinated optimization of beamforming and multiplexing gain, and avoiding the high overhead and synchronization complexity of directly sharing complete channel state information between terminals.

[0087] In an optional embodiment, before sending the pCSI-RS corresponding to each of the multiple terminals to the corresponding terminal, the method further includes: receiving uplink SRS sent by the multiple terminals respectively; determining the second uplink CSI corresponding to each of the multiple terminals based on the uplink SRS sent by the multiple terminals respectively; and obtaining the pCSI-RS corresponding to each of the multiple terminals based on the second uplink CSI corresponding to each of the multiple terminals.

[0088] In this embodiment, the base station receives uplink SRS transmitted by multiple terminals to obtain the second uplink CSI from each terminal to the base station. Based on this second uplink CSI, it generates a pCSI-RS for reciprocity calibration, avoiding the technical bottleneck of inaccurately constructing the global uplink CSI matrix on the terminal side due to a lack of uplink channel feedback. After the generated pCSI-RS and downlink CSI-RS are jointly transmitted to each terminal, the terminal can combine its own pCSI-RS and CSI-RS to recover the first uplink CSI, while simultaneously utilizing the pCSI-RS of other terminals. The uplink CSI phase information is obtained to construct a complete global uplink CSI matrix containing the phase relationship of the multi-terminal cooperative channel, and the accurate uplink precoding weight is calculated accordingly. Based on this weight, multiple terminals perform spatial coherent superposition of the target data stream on the same time-frequency resources, enabling the terminal side to realize the transmission gain of the virtual distributed antenna array. This effectively overcomes the limitation that distributed terminals cannot cooperate in beamforming due to the difficulty of reciprocity calibration and the high cost of uplink CSI acquisition, and significantly improves the long-distance uplink coherent transmission performance and system multiplexing gain of low-power terminals at the cell edge.

[0089] In an optional embodiment, before sending the downlink CSI-RS corresponding to each of the multiple terminals to the corresponding terminal, the method further includes: sending downlink control signaling to the multiple terminals respectively, wherein the downlink control signaling is used to instruct coherent transmission to be performed on the same time-frequency resources, and the downlink control signaling carries downlink indication information, which includes at least the number of target data streams, the number of multiple terminals, the antenna port information of the corresponding terminal, and the antenna port information of the base station.

[0090] In this embodiment, the base station first explicitly instructs multiple terminals to perform coherent transmission on the same time-frequency resources via downlink control signaling. This signaling carries the number of target data streams, the number of participating terminals, the antenna port configuration of each terminal, and the base station's own antenna port information. This allows each terminal to accurately obtain the coordination parameters set by the base station for coherent transmission before calculating the uplink precoding weights. Based on this, the terminal constructs a first uplink CSI by combining its received CSI-RS and pCSI-RS, and derives the phase information of its uplink CSI using the pCSI-RS of other terminals. This results in the synthesis of an uplink CSI matrix containing global coordination relationships, ultimately generating uplink precoding weights that precisely match the base station's receiving capabilities. Multiple terminals then perform spatial coherent superposition of the target data streams on the same resources based on these weights, ensuring that the transmit beams of each terminal achieve phase alignment and energy convergence at the base station. This stably constructs the transmit gain of the virtual distributed antenna array, effectively avoiding the problems of uplink precoding mismatch and base station receiving structure failure caused by a lack of coordination parameter configuration guidance, thus achieving efficient uplink coordinated transmission for long-distance, low-power terminals.

[0091] Optionally, downlink indication information can be set, including the number of data streams sent by the terminals (i.e., the target data stream), the number of cooperating terminals (i.e., the number of multiple terminals), the number of antenna ports per terminal, the total number of antenna ports on the base station side, and the reference antenna port number on the base station side selected by all terminal antenna ports. On the same time-frequency resources, the data vectors (or parallel data streams) sent by multiple terminals are the same. The dimension of the data vector, i.e., the number of data streams, is calculated by the base station side based on the uplink CSI.

[0092] In an optional embodiment, before receiving the target data streams sent by multiple terminals based on corresponding uplink precoding weights via coherent transmission, the method further includes: determining the number of target data streams as a specified number based on the second uplink CSI corresponding to each of the multiple terminals, wherein the second uplink CSI is obtained based on the uplink SRS of the corresponding terminal.

[0093] In this embodiment, the base station receives uplink SRS actively reported by multiple terminals, independently estimates the second uplink CSI corresponding to each terminal, and statically or dynamically determines the number of target data streams suitable for multi-terminal coherent cooperative transmission based on the local channel quality and available rank information reflected by the CSI. This avoids the high overhead and reciprocity calibration problems caused by relying on global uplink CSI calculation on the base station side. Subsequently, the base station sends downlink CSI-RS and pCSI-RS. Each terminal uses its received pCSI-RS and CSI-RS to jointly derive the first uplink CSI and integrates the uplink CSI phase information obtained by other terminals through pCSI-RS to construct... A global uplink CSI matrix is ​​used to calculate the corresponding uplink precoding weights for each data stream. Finally, the target data stream is transmitted coherently on the same time-frequency resources, with the number of streams strictly matching the specified number determined by the SRS feedback. This mechanism enables precise setting of the number of data streams solely through SRS feedback on the terminal side, without relying on the base station to acquire or jointly process the uplink channel status of all terminals in real time. This significantly reduces system signaling overhead and computational complexity, while ensuring that distributed low-power terminals can still achieve efficient, stable, and scalable uplink coherent cooperative transmission under long-distance and non-ideal reciprocity conditions. This effectively improves the uplink throughput performance of cell edge terminals and the overall resource utilization efficiency of the system.

[0094] As an optional implementation, multiple terminals can share uplink data information. When terminals are close to each other, short-range high-speed wireless communication technology can be used to share data. Alternatively, under the current communication standard, multiple terminals can take turns sending information; that is, the terminal to send data broadcasts the information to other terminals, and the other terminals use calculation or decoding forwarding to achieve data stream sharing. For uplink CJTs of multiple terminals at cell boundaries, obtaining beamforming gain is more important. To obtain beamforming gain, multiple terminals need to send the same data stream. After multiple terminals share uplink data information, on the same time and frequency resources, the data vectors (or parallel data streams) sent by multiple terminals are the same. The dimension of the data vector, i.e., the number of data streams, is calculated by the base station based on the uplink CSI. Therefore, the number of data streams sent by each terminal can be obtained as follows: multiple terminals share data information but do not share CSI; that is, the terminal only knows the CSI between itself and the base station antenna. In this case, the number of uplink data streams can be determined based on the minimum number of antennas of the terminal. The number of data streams sent by each terminal can also be obtained in the following ways: Figure 4 This is a schematic diagram of an optional uplink multi-stream coherent joint transmission communication between multiple nodes and multiple terminals on the base station side according to an embodiment of the present invention, as shown below. Figure 4 As shown, multiple terminals share data information, and the number of terminals participating in joint transmission is relatively large. Multiple nodes on the base station side cooperate in receiving data. Each node on the base station side is configured with a small number of antennas or beams, for example, one or two dual-polarized antennas, one or two dual-polarized beams. Therefore, the number of uplink data streams can be set to be less than or equal to the number of nodes on the base station side multiplied by the number of polarizations. Multiple terminals share data information, and each terminal has CSI between all terminal antennas and all base station antennas. In this case, the number of uplink data streams can also be calculated by the base station side based on the uplink CSI. Besides the above optional implementation methods, the number of uplink data streams can also be determined based on channel information, actual link budget information, and uplink rate requirements.

[0095] Based on the above embodiments and optional embodiments, the present invention proposes an optional implementation method, which can be applied to... Figure 2 In the uplink coherent joint transmission communication scenario shown, where the base station and multiple terminals are connected, Figure 5 This is a flowchart of an optional communication method based on multiple terminals according to an embodiment of the present invention, such as... Figure 5 As shown, the method includes:

[0096] S1, the base station side is configured with multiple transceiver points, and each transceiver point is configured with multiple antenna ports.

[0097] S2, the base station instructs multiple terminals in the downlink signaling that multiple terminals will implement uplink cooperative transmission within the specified bandwidth.

[0098] Specifically, the base station instructs multiple terminals to perform uplink cooperative transmission within the same specified time-frequency resources via downlink control signaling. Optionally, the downlink instruction information includes the number of data streams sent by the terminals, the number of cooperating terminals, the number of antenna ports for each terminal, the total number of antenna ports on the base station side, and the reference antenna port number selected by all terminal antenna ports on the base station side. After multiple terminals share uplink data information, the data vectors (or parallel data streams) sent by multiple terminals on the same time-frequency resources are the same. The dimension of the data vector, i.e., the number of data streams, is calculated by the base station side based on the uplink CSI.

[0099] S3, multiple terminals transmit uplink sounding reference signals (SRS). Among them, the uplink SRS transmitted by multiple terminals includes uplink SRS signals from multiple antenna ports of multiple terminals using 3GPP 5G New Radio (5G NR).

[0100] S4, The base station transmits downlink channel state information reference signals (CSI-RS). The CSI-RS transmitted by the base station includes downlink CSI-RS signals from multiple antenna ports on the 3GPP 5G NR base station side, or CSI-RS in the beam domain.

[0101] S5. To achieve reciprocity calibration for multiple terminals, the base station calculates a precoded channel state information reference signal (pCSI-RS) based on the uplink channel information (CSI) of each terminal, and then sends the pCSI-RS to multiple terminals. The pCSI-RS sent by the base station for calibration has the following characteristics: the precoding can use the conjugate of the uplink CSI phase as the precoding weight, and the number of orthogonal ports is the number of ports on the base station participating in cooperative reception multiplied by the total number of ports on the multiple terminals.

[0102] S6. At the terminal, on the one hand, based on pCSI-RS, the calibration coefficient of the terminal relative to one antenna port on the base station side can be obtained; on the other hand, the downlink CSI is obtained based on CSI-RS, and the uplink CSI of the terminal can be obtained after calibration. Taking a terminal i using a single antenna as an example, based on pCSI-RS, the reciprocity calibration coefficient of the time-division duplex transmit / receive channel of the terminal's antenna port relative to the reference antenna port on the base station side can be obtained. Based on the downlink CSI obtained from CSI-RS and the reciprocity calibration coefficient, the corresponding uplink CSI of terminal i can be obtained. To track uplink channel information, optionally, based on downlink channel parameter information, the frequency offset between the terminal and the base station can be tracked, and the changes in uplink channel information can be tracked through the frequency offset.

[0103] S7. Based on the uplink CSI obtained from CSI-RS and the pCSI-RS of other terminals transmitted by the base station, the phase of the uplink CSI of other terminals can be obtained; based on the uplink CSI of this terminal and the phase of the uplink CSI of other terminals, the uplink channel matrix of this terminal can be obtained.

[0104] Specifically, taking a single-antenna terminal i as an example, based on the downlink CSI of terminal i obtained from CSI-RS and the pCSI-RS of other terminals transmitted by the base station, the phase of the uplink CSI of other terminals can be obtained at terminal i. The phase of the uplink CSI of other terminals is used to construct an approximate global uplink channel matrix locally at the terminal. This allows for the calculation of an uplink precoding vector matching the spatial structure of the multi-terminal cooperative channel without acquiring the channel amplitude of other terminals, thereby achieving distributed uplink coherent transmission. Terminal i acquires the uplink CSI phase of other terminals to splice it with its own complete uplink CSI (including amplitude and phase) to form a "complete uplink channel matrix from all cooperating terminals to the base station." This enables the independent calculation of an uplink precoding vector matching the global channel, achieving coherent beamforming of a multi-terminal "virtual large array."

[0105] To track the uplink CSI of other terminals, at terminal i, based on the temporal changes in the uplink CSI phase of other terminals (e.g., terminal j), the frequency offset between terminal j and the base station is estimated, and then the changes in the uplink CSI of terminal j are tracked through the frequency offset. The uplink CSI matrix obtained by each terminal includes the uplink CSI matrix from the terminal itself to all antennas of the base station, and each terminal also obtains the uplink CSI matrix from all terminals to the base station.

[0106] S8, each terminal calculates its uplink transmission precoding weight (or precoding weight vector) based on its local uplink channel matrix and the number of uplink data streams. Specifically, each terminal may calculate its own uplink precoding vector based solely on its own uplink CSI matrix to the base station; or each terminal may calculate its own uplink precoding vector based solely on the uplink CSI matrices of all terminals to the base station.

[0107] Specifically, the terminal calculates the conjugate transpose of the uplink channel matrix, multiplies it by the uplink channel matrix, and then performs eigenvalue decomposition on the matrix. Based on the number N data streams to be transmitted, it selects N eigenvectors with eigenvalues ​​from largest to smallest to obtain the uplink precoding weights. Optionally, the terminal can match the optimal N uplink precoding weight vectors based on the uplink channel matrix and a pre-defined codebook. Specifically, based on the uplink channel matrix, the terminal selects the optimal N precoding weight vectors from a pre-defined precoding codebook defined in the 3GPP 5G NR standard using a matching metric. The codebook is a set containing multiple precoding matrices, where each column vector of a precoding matrix corresponds to a precoding direction. The terminal calculates the matching degree between the uplink channel matrix and each candidate matrix in the codebook, selects the codeword with the highest matching degree, and uses its column vector as the uplink precoding vector.

[0108] S9. After sharing data information between terminals, uplink precoding is used to achieve uplink coherent transmission between multiple terminals. Specifically, information sharing between terminals can use data links of other frequency bands or other standards. Information sharing between terminals is achieved through a non-5G NR wireless data link, which operates on a frequency band different from the 5G NR band and does not rely on base station scheduling; non-5G NR standards include one or more of Wi-Fi Direct, UWB, or Bluetooth Low Energy. Optionally, information between terminals can be transmitted by the terminal to send data broadcasting its information to other terminals, and then achieving uplink precoding coherent transmission on the same time-frequency resources through decoding and forwarding.

[0109] It should be noted that the method of this embodiment can achieve time-frequency synchronization and reciprocity calibration among multiple terminals, and each terminal can obtain the overall uplink channel information; the method of this embodiment can combine data sharing to obtain a trade-off between coherent beamforming gain and multiplexing gain for uplink of multiple terminals.

[0110] This embodiment also provides a communication device based on multiple terminals, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the terms "module" and "device" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0111] According to embodiments of the present invention, an apparatus embodiment for implementing the above-described communication method based on multiple terminals is also provided. Figure 6 This is a schematic diagram of the structure of a communication device based on multiple terminals according to an embodiment of the present invention, such as... Figure 6As shown, the above-mentioned communication device based on multiple terminals includes: a first uplink CSI determination module 600, an uplink CSI phase determination module 602, an uplink CSI matrix determination module 604, an uplink precoding weight acquisition module 606, and a first coherent transmission module 608, wherein:

[0112] The first uplink CSI determination module 600 is used to determine the first uplink channel state information (CSI) of the target terminal based on the precoded channel state information reference signal pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink channel state information reference signal CSI-RS corresponding to the target terminal. pCSI-RS is used for the transceiver reciprocity calibration between the corresponding terminal and the base station.

[0113] The uplink CSI phase determination module 602 is connected to the first uplink CSI determination module 600 and is used to obtain the phase of the uplink CSI of other terminals based on the pCSI-RS of other terminals sent by the base station. The other terminals are terminals other than the target terminal among multiple terminals.

[0114] The uplink CSI matrix determination module 604, connected to the uplink CSI phase determination module 602, is used to obtain a global uplink CSI matrix from multiple terminals to the base station based on the first uplink CSI of the target terminal and the phases of the uplink CSIs of other terminals.

[0115] The uplink precoding weight acquisition module 606 is connected to the uplink CSI matrix determination module 604 and is used to obtain the uplink precoding weight corresponding to the target terminal based on the global uplink CSI matrix.

[0116] The first coherent transmission module 608 is connected to the uplink precoding weight acquisition module 606. It is used to send the target data stream to the base station based on the uplink precoding weight by coherently transmitting with other terminals. The coherent transmission is used to instruct multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, so as to form the transmission gain of a virtual distributed antenna array on the multiple terminal sides.

[0117] According to embodiments of the present invention, an apparatus embodiment for implementing the above-described communication method based on multiple terminals is also provided. Figure 7 This is a schematic diagram of the structure of a communication device based on multiple terminals according to an embodiment of the present invention, such as... Figure 7 As shown, the above-mentioned communication device based on multiple terminals includes: a downlink CSI-RS transmission module 700, a pCSI-RS transmission module 702, and a second coherent transmission module 704, wherein:

[0118] The downlink CSI-RS transmission module 700 is used to transmit the downlink CSI-RS corresponding to each of multiple terminals to the corresponding terminal.

[0119] pCSI-RS transmitting module 702 is connected to downlink CSI-RS transmitting module 700 and is used to transmit the pCSI-RS corresponding to each of multiple terminals to the corresponding terminal.

[0120] The second coherent transmission module 704, connected to the pCSI-RS transmission module 702, is used to receive target data streams transmitted by multiple terminals based on corresponding uplink precoding weights via coherent transmission. The uplink precoding weights are obtained based on the global uplink CSI matrix of the corresponding terminal. The global uplink CSI matrix represents the uplink CSI matrices from multiple terminals to the base station. The global uplink CSI matrix is ​​obtained based on the first uplink CSI of the corresponding terminal and the phase of the uplink CSIs of other terminals besides the corresponding terminal. The first uplink CSI is obtained based on the pCSI-RS and CSI-RS of the corresponding terminal; the phase of the uplink CSIs of other terminals is obtained based on their corresponding pCSI-RS. Coherent transmission is used to instruct multiple terminals to spatially coherently superimpose the target data streams on the same time-frequency resources according to their respective uplink precoding weights, thereby forming a transmission gain of a virtual distributed antenna array on the multiple terminal sides.

[0121] It should be noted that the above modules can be implemented by software or hardware. For example, for the latter, it can be implemented in the following ways: the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0122] It should be noted that the aforementioned first uplink CSI determination module 600, uplink CSI phase determination module 602, uplink CSI matrix determination module 604, uplink precoding weight acquisition module 606, and first coherent transmission module 608 correspond to steps S102 to S110 in the embodiments, and the aforementioned downlink CSI-RS transmission module 700, pCSI-RS transmission module 702, and second coherent transmission module 704 correspond to steps S202 to S206 in the embodiments. The instances and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should be noted that the above modules, as part of the device, can run in a computer terminal.

[0123] It should be noted that the optional or preferred implementation methods of this embodiment can be found in the relevant descriptions in the embodiments, and will not be repeated here.

[0124] The aforementioned communication device based on multiple terminals may further include a processor and a memory. The first uplink CSI determination module 600, the uplink CSI phase determination module 602, the uplink CSI matrix determination module 604, the uplink precoding weight acquisition module 606, the first coherent transmission module 608, the downlink CSI-RS transmission module 700, the pCSI-RS transmission module 702, and the second coherent transmission module 704 are all stored in the memory as program modules. The processor executes the aforementioned program modules stored in the memory to implement the corresponding functions.

[0125] The processor contains a core that retrieves the corresponding program modules from memory. One or more cores may be configured. Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory includes at least one memory chip.

[0126] According to an embodiment of this application, an embodiment of a non-volatile storage medium is also provided. Optionally, in this embodiment, the non-volatile storage medium includes a stored program, wherein, when the program is running, it controls the device where the non-volatile storage medium is located to execute any of the aforementioned communication methods based on multiple terminals.

[0127] Optionally, in this embodiment, the non-volatile storage medium may be located in any computer terminal in a group of computer terminals in a computer network, or in any mobile terminal in a group of mobile terminals, and the non-volatile storage medium includes stored programs.

[0128] Optionally, a program that controls the device containing the non-volatile storage medium to execute any of the above-mentioned communication method steps based on multiple terminals during program execution.

[0129] According to an embodiment of this application, an embodiment of a processor is also provided. Optionally, in this embodiment, the processor is used to run a program, wherein the program executes any of the aforementioned communication methods based on multiple terminals.

[0130] According to an embodiment of this application, an embodiment of a computer program product is also provided, which, when executed on a data processing device, is suitable for executing a program that initializes a communication method step based on multiple terminals, having any of the above-described steps.

[0131] This invention provides an electronic device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the communication method steps based on multiple terminals described above.

[0132] The order of the above embodiments of the present invention is merely for description and does not represent the superiority or inferiority of the embodiments.

[0133] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0134] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of modules described above can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between modules, and may be electrical or other forms.

[0135] The modules described above as separate components may or may not be physically separate. Similarly, the components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple modules. Some or all of the modules can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0136] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0137] If the aforementioned integrated modules are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable non-volatile storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a non-volatile storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned non-volatile storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0138] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A communication method based on multiple terminals, characterized in that, include: Based on the precoded channel state information reference signal pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink channel state information reference signal CSI-RS corresponding to the target terminal, the first uplink channel state information CSI of the target terminal is determined, wherein the pCSI-RS is used for transceiver reciprocity calibration between the corresponding terminal and the base station. Based on the pCSI-RS of other terminals transmitted by the base station, the phase of the uplink CSI of the other terminals is obtained, wherein the other terminals are terminals other than the target terminal among the plurality of terminals; Based on the first uplink CSI of the target terminal and the phase of the uplink CSI of the other terminals, a global uplink CSI matrix from the multiple terminals to the base station is obtained. Based on the global uplink CSI matrix, the uplink precoding weights corresponding to the target terminal are obtained; Based on the uplink precoding weights, the target data stream is sent to the base station through coherent transmission with the other terminals. The coherent transmission is used to instruct the multiple terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, so as to form the transmission gain of a virtual distributed antenna array on the multiple terminal sides.

2. The method according to claim 1, characterized in that, The determination of the first uplink CSI of the target terminal based on the pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink CSI-RS corresponding to the target terminal, includes: Based on the downlink CSI-RS of the target terminal, estimate the downlink CSI of the target terminal; Based on the pCSI-RS of the target terminal, obtain the reciprocity calibration coefficient of the target terminal relative to the reference antenna port of the base station; Based on the reciprocity calibration coefficient, phase compensation is performed on the downlink CSI to obtain the first uplink CSI.

3. The method according to claim 1, characterized in that, The process of obtaining the phase of the uplink CSI of other terminals based on the pCSI-RS transmitted by the base station includes: Based on the pCSI-RS of the other terminals, estimate the product signal of the uplink channel phase of the other terminals and the downlink CSI of the target terminal; Based on the downlink CSI of the target terminal, the product signal is phase decoupled to obtain the phase of the uplink CSI of the other terminals.

4. The method according to claim 1, characterized in that, The step of obtaining the uplink precoding weights corresponding to the target terminal based on the global uplink CSI matrix includes: Determine the conjugate transpose corresponding to the global uplink CSI matrix; Multiply the global uplink CSI matrix and its conjugate transpose to obtain the channel correlation matrix; The uplink precoding weights are obtained by performing eigenvalue decomposition on the channel correlation matrix.

5. The method according to claim 4, characterized in that, When the number of target data streams is a specified number, the step of performing eigenvalue decomposition on the channel correlation matrix to obtain the uplink precoding weights includes: The channel correlation matrix is ​​subjected to eigenvalue decomposition to obtain multiple eigenvalues; The uplink precoding weight is obtained based on the largest specified number of feature values ​​among the plurality of feature values.

6. The method according to claim 1, characterized in that, When the number of target data streams is a specified number, obtaining the uplink precoding weights corresponding to the target terminal based on the global uplink CSI matrix includes: Determine the matching degree between multiple precoding matrices in the preset codebook and the global uplink CSI matrix, wherein the codebook is a set containing the multiple precoding matrices, and the column vector of each precoding matrix corresponds to a precoding direction; From the plurality of precoding matrices, determine the specified number of precoding matrices with the highest matching degree; The uplink precoding weights are obtained based on the precoding directions corresponding to the specified number of precoding matrices.

7. The method according to any one of claims 1 to 6, characterized in that, Before determining the uplink CSI of the target terminal based on the pCSI-RS of the target terminal among multiple terminals transmitted by the base station, and the downlink CSI-RS corresponding to the target terminal, the method further includes: The uplink detection reference signal (SRS) is sent to the base station, which is used by the base station to determine the pCSI-RS corresponding to each of the plurality of terminals. The pCSI-RS is obtained based on the second uplink CSI of the corresponding terminal, and the second uplink CSI is obtained based on the SRS of the corresponding terminal.

8. The method according to any one of claims 1 to 6, characterized in that, The target data stream is shared by a designated terminal to other terminals among the plurality of terminals (excluding the designated terminal) via a designated frequency band or a designated communication link before the coherent transmission is performed; or it is broadcast by the designated terminal to the other terminals. Wherein, the designated terminal is the holder of the target data stream, the designated frequency band is the frequency band that does not participate in the coherent transmission, and the designated communication link is the communication link that does not participate in the coherent transmission.

9. A communication method based on multiple terminals, characterized in that, include: Send the downlink CSI-RS corresponding to each of the multiple terminals to the corresponding terminal; Send the pCSI-RS corresponding to each of the multiple terminals to the corresponding terminal; The system receives a target data stream transmitted by the plurality of terminals using a coherent transmission method based on corresponding uplink precoding weights. The uplink precoding weights are obtained based on the global uplink CSI matrix of the corresponding terminal. The global uplink CSI matrix represents the uplink CSI matrix from the plurality of terminals to the base station. The global uplink CSI matrix is ​​obtained based on the first uplink CSI of the corresponding terminal and the phase of the uplink CSIs of other terminals besides the corresponding terminal. The first uplink CSI is obtained based on the pCSI-RS and CSI-RS of the corresponding terminal. The phase of the uplink CSIs of the other terminals is obtained based on their corresponding pCSI-RS. The coherent transmission is used to instruct the plurality of terminals to spatially coherently superimpose the target data stream on the same time-frequency resources according to their respective uplink precoding weights, thereby forming a transmission gain of a virtual distributed antenna array on the plurality of terminal sides.

10. The method according to claim 9, characterized in that, Before sending the pCSI-RS corresponding to each of the plurality of terminals to the corresponding terminal, the method further includes: Receive uplink SRS sent by the plurality of terminals respectively; Based on the uplink SRS sent by the multiple terminals respectively, determine the second uplink CSI corresponding to each of the multiple terminals; Based on the second uplink CSI corresponding to each of the multiple terminals, the pCSI-RS corresponding to each of the multiple terminals is obtained.

11. The method according to claim 9, characterized in that, Before transmitting the downlink CSI-RS corresponding to each of the multiple terminals to the corresponding terminal, the method further includes: Downlink control signaling is sent to the plurality of terminals respectively, wherein the downlink control signaling is used to instruct the coherent transmission to be performed on the same time-frequency resources, and the downlink control signaling carries downlink indication information, which includes at least the number of target data streams, the number of the plurality of terminals, the antenna port information of the corresponding terminals, and the antenna port information of the base station.

12. The method according to claim 11, characterized in that, Before receiving the target data stream transmitted by the plurality of terminals based on corresponding uplink precoding weights via coherent transmission, the method further includes: Based on the second uplink CSI corresponding to each of the plurality of terminals, the number of target data streams is determined to be a specified number, wherein the second uplink CSI is obtained based on the uplink SRS of the corresponding terminal.

13. A non-volatile storage medium, characterized in that, The non-volatile storage medium stores multiple instructions, which are adapted to be loaded by a processor and executed by the processor to perform the communication method based on multiple terminals as described in any one of claims 1 to 12.

14. An electronic device, characterized in that, It includes one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the communication method based on multiple terminals as described in any one of claims 1 to 12.

15. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the communication method based on multiple terminals as described in any one of claims 1 to 12.

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