Mutual channel feature extraction method and apparatus

Abstract

The application provides a reciprocity channel feature extraction method and device, the method comprising: obtaining an uplink channel feature sequence based on a first channel estimation result, wherein the first channel estimation result represents a channel estimation result of a demodulation reference signal corresponding to an uplink signal; obtaining a downlink signal time-frequency domain parameter sequence based on a first time-frequency domain parameter, wherein the first time-frequency domain parameter represents a time-frequency domain parameter of a demodulation reference signal corresponding to a downlink signal; and performing reciprocity channel feature extraction on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on an uplink-downlink symbol time difference to obtain a reciprocity channel feature sequence, wherein the uplink-downlink symbol time difference is calculated according to a frame number, a time slot number and a symbol number. The application realizes non-interactive extraction of a reciprocity channel feature sequence.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a method and apparatus for extracting reciprocal channel features. Background Technology

[0002] Existing Physical Layer Key Generation (PLKG) technologies typically only consider L1 layer communication implementation, or require the communicating parties to exchange channel characteristic-related parameter information to obtain reciprocal channel characteristics, such as frame number and time slot number, and assume that the uplink and downlink channel bandwidths or feature lengths are the same, such as fixed channel bandwidth.

[0003] In real-world communication scenarios, uplink and downlink time-frequency domain resources are controlled and scheduled by L1 / L2 signaling. The time intervals and bandwidths are not fixed, resulting in the time intervals and lengths of the channel feature sequences obtained by both communicating parties being inconsistent, and a large number of sequences that do not meet the reciprocity requirements exist.

[0004] Therefore, there is an urgent need for a reciprocal channel feature extraction method and apparatus to solve the above problems. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a method and apparatus for reciprocal channel feature extraction.

[0006] In a first aspect, the present invention provides a reciprocal channel feature extraction method, applied to network devices, the method comprising: Based on the first channel estimation result, an uplink channel feature sequence is obtained, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal; Based on the first time-frequency domain parameters, the downlink signal time-frequency domain parameter sequence is obtained, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal; Based on the uplink and downlink symbol time difference, reciprocal channel features are extracted from the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence to obtain a reciprocal channel feature sequence. The uplink and downlink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

[0007] According to a reciprocal channel feature extraction method provided by the present invention, the step of obtaining an uplink channel feature sequence based on a first channel estimation result includes: Receive multiple uplink signals; During the decoding process of the physical uplink shared channel, channel estimation is performed on the demodulation reference signals corresponding to multiple uplink signals to obtain multiple first channel estimation results, and the timestamp, frame number, slot number, symbol number and resource block number corresponding to each first channel estimation result are obtained. Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first channel estimation results, the uplink channel feature sequence is obtained.

[0008] According to a reciprocal channel feature extraction method provided by the present invention, the step of obtaining a downlink signal time-frequency domain parameter sequence based on a first time-frequency domain parameter includes: Send multiple downlink signals; During the coding process of the physical downlink shared channel, the first time-frequency domain parameters of the demodulation reference signals corresponding to the multiple downlink signals are obtained; Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first time-frequency domain parameters, the downlink signal time-frequency domain parameter sequence is obtained.

[0009] According to a reciprocal channel feature extraction method provided by the present invention, the reciprocal channel feature extraction is performed on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain a reciprocal channel feature sequence, including: Read the uplink channel feature sequence based on the frame sequence number, and sequentially obtain the uplink channel feature frame sequence number in the current uplink channel feature sequence; Based on a preset coherence time, at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame sequence is determined from multiple downlink signal time-frequency domain parameter sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; The uplink and downlink symbol time difference is calculated based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence. The downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the current target uplink-downlink symbol time difference is the uplink-downlink symbol time difference with the smallest absolute value.

[0010] According to a reciprocal channel feature extraction method provided by the present invention, the step of determining at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame sequence from multiple downlink signal time-frequency domain parameter sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the downlink signal time-frequency domain parameter sequence and the current uplink channel characteristic frame number; The downlink signal time-frequency domain parameter sequence that has a time interval less than the preset coherence time and whose frame number is the same as the current uplink channel feature frame number is determined as the target downlink signal time-frequency domain parameter sequence.

[0011] According to a reciprocal channel feature extraction method provided by the present invention, the method further includes: When the time interval is less than the preset coherence time and there is no downlink signal time-frequency domain parameter sequence with the same frame number as the current uplink channel feature frame number, the downlink signal time-frequency domain parameter sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target downlink signal time-frequency domain parameter sequence, wherein the preset frame interval is obtained based on the preset coherence time.

[0012] According to a reciprocal channel feature extraction method provided by the present invention, the step of calculating the uplink-downlink symbol time difference based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence includes: Obtain the first time slot number and the first symbol number, wherein the first time slot number represents the time slot number corresponding to the current uplink channel feature frame number; and the first symbol number represents the symbol number corresponding to the current uplink channel feature frame number. Obtain the second time slot number and the second symbol number, wherein the second time slot number represents the time slot number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence; and the second symbol number represents the symbol number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence. Calculate the first frame sequence time difference between the current uplink channel feature frame sequence number and the frame sequence number of the target downlink signal time-frequency domain parameter sequence; Calculate the time difference between the first time slot number and the second time slot number; Calculate the first symbol time difference between the first symbol sequence number and the second symbol sequence number; The uplink and downlink symbol time differences are calculated based on the first frame sequence number time difference, the first time slot number time difference, and the first symbol time difference.

[0013] According to a reciprocal channel feature extraction method provided by the present invention, determining the reciprocal channel feature sequence by combining the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel feature sequence is as follows: When the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference is a reciprocal downlink sequence of the previous uplink channel feature sequence, the current target uplink-downlink symbol time difference is compared with the previous target uplink-downlink symbol time difference. If it is determined that the current target uplink and downlink symbol time difference is less than the previous target uplink and downlink symbol time difference, the previous uplink channel feature sequence is discarded, and the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence. If it is determined that the current target uplink and downlink symbol time difference is greater than or equal to the previous target uplink and downlink symbol time difference, the downlink signal time-frequency domain parameter sequence corresponding to the current second smallest absolute uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

[0014] According to a reciprocal channel feature extraction method provided by the present invention, the method further includes: If it is determined that there are multiple downlink signal time-frequency domain parameter sequences corresponding to the current target uplink and downlink symbol time differences, all of which are reciprocal downlink sequences of the current uplink channel feature sequence, then the reciprocal downlink sequence with the maximum resource block length and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

[0015] According to a reciprocal channel feature extraction method provided by the present invention, the method further includes: If the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

[0016] Secondly, the present invention also provides a reciprocal channel feature extraction device, applied to network equipment, the device comprising: The first extraction module is used to obtain an uplink channel feature sequence based on the first channel estimation result, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal; The second extraction module is used to obtain a sequence of time-frequency domain parameters of the downlink signal based on the first time-frequency domain parameters, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal; The first reciprocal channel feature extraction module is used to extract reciprocal channel features from the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain a reciprocal channel feature sequence. The uplink and downlink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

[0017] Thirdly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the reciprocal channel feature extraction method as described above.

[0018] Fourthly, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the reciprocal channel feature extraction method as described above.

[0019] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the reciprocal channel feature extraction method as described above.

[0020] The reciprocal channel feature extraction method and apparatus provided by this invention, with the provision of channel estimation and time-frequency domain parameter information interfaces, extracts the channel features and time-frequency domain parameters of the uplink and downlink shared channel based on the data transmission protocol of the physical uplink and downlink shared channel, thereby realizing non-interactive reciprocal channel feature sequence extraction. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a physical layer key generation scheme in the prior art; Figure 2 This is one of the flowcharts illustrating the reciprocal channel feature extraction method provided by the present invention; Figure 3 A schematic diagram of the time-frequency domain parameters and channel feature sequences provided by the present invention; Figure 4 A schematic diagram illustrating reciprocal uplink and downlink channel feature extraction provided by the present invention; Figure 5 This is the second flowchart illustrating the reciprocal channel feature extraction method provided by the present invention. Figure 6 A schematic diagram of the physical layer key generation process based on interactive reciprocal channel feature extraction provided by the present invention; Figure 7 This is one of the structural schematic diagrams of the reciprocal channel feature extraction device provided by the present invention; Figure 8 A second schematic diagram of the reciprocal channel feature extraction device provided by the present invention; Figure 9 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] The PLKG scheme is a novel cryptographic scheme for key generation based on the characteristics of wireless channels. Figure 1 This is a schematic diagram of a physical layer key generation scheme in the prior art, for reference only. Figure 1 As shown, due to the reciprocity of the channel during coherence time, the communicating parties (such as Alice and Bob) can extract highly correlated channel features, such as... and After processing with algorithms such as quantization, harmonic error correction, and privacy amplification, both communicating parties can obtain a consistent random sequence, i.e., the physical layer key, namely Key_Alice and Key_Bob.

[0025] Since the communication environment changes with time and space, and this change has a certain degree of randomness and unpredictability, the channel characteristics extracted by both parties also change with time and space, thereby generating a dynamic key with "true randomness" to achieve lightweight, low-latency end-to-end encryption.

[0026] Existing PLKG schemes can be widely used in various wireless communication systems. Among them, channel feature extraction is the core preprocessing stage of channel key generation. The goal is to extract high-entropy, reciprocal and stable feature parameters from time-varying wireless channels to provide the original entropy source for subsequent quantization negotiation.

[0027] Due to the characteristics of existing wireless communication such as parameter sets, partial bandwidth, and dynamic scheduling, the time-frequency domain physical parameters such as the time interval and bandwidth of uplink and downlink communication are not fixed. Therefore, it is necessary to design more applicable channel feature extraction algorithms to improve the practicality of physical layer keys in communication scenarios.

[0028] Existing PLKG schemes typically only consider the communication implementation at the L1 layer, or require the communicating parties to exchange relevant parameter information of the channel characteristics to obtain reciprocal channel characteristics, such as frame number and time slot number; and assume that the uplink and downlink channels have the same bandwidth or channel characteristic length, such as fixed channel bandwidth.

[0029] In real-world communication scenarios, the allocation of time-frequency domain resources for uplink and downlink communication is determined by L1 / L2 control signaling scheduling, and the time intervals and bandwidths for uplink and downlink communication are not fixed. Therefore, the time intervals and sequence lengths corresponding to the channel feature sequences acquired by both communicating parties are not fixed, resulting in a large number of uplink and downlink channel feature sequences that do not meet reciprocity requirements. Furthermore, existing interactive reciprocity-based channel feature extraction schemes consume significant communication resources and can leak uplink and downlink time-frequency domain parameter information, impacting the usability of physical layer keys.

[0030] To address the problems existing in the prior art, this invention provides a non-interactive reciprocal channel feature extraction method. This method, when providing channel estimation and time-frequency domain parameter information interfaces in a communication scenario, extracts channel features and time-frequency domain parameters of the uplink and downlink shared channels based on the data transmission protocols of Physical Uplink Shared Channel (PUSCH) and Physical Downlink Shared Channel (PDSCH). This achieves non-interactive reciprocal channel feature sequence extraction, effectively improving the practicality of physical layer keys in real-world communication scenarios.

[0031] Figure 2 This is one of the flowcharts illustrating the reciprocal channel feature extraction method provided by the present invention, such as... Figure 2 As shown, this invention provides a reciprocal channel feature extraction method, applied to network devices, the method comprising: Step 201: Based on the first channel estimation result, obtain the uplink channel feature sequence, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal.

[0032] In this invention, after the terminal (taking Bob on the terminal side as an example) establishes a wireless communication connection with the network device (Alice on the base station side as an example) through random access, Alice receives the uplink signal sent by Bob. .

[0033] According to the communication protocol, during the PUSCH decoding process, Alice obtains the channel estimation result of the corresponding Demodulation Reference Signal (DMRS), which is denoted as the first channel estimation result. Simultaneously, record the time-frequency domain parameters corresponding to the channel estimation result, such as the uplink receive timestamp. Uplink received frame sequence number Uplink receive time slot number Uplink received symbol sequence number Number of uplink received resource blocks (RBs) These channel estimation results, arranged in a certain order, constitute the uplink channel characteristic sequence, which reflects the characteristic information of the uplink channel.

[0034] Step 202: Based on the first time-frequency domain parameters, obtain the downlink signal time-frequency domain parameter sequence, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal.

[0035] In this invention, Alice sends downlink signals to Bob via a wireless channel. During the PDSCH encoding process based on the communication protocol, the time-frequency domain parameters of the demodulation reference signal (DMRS) corresponding to the downlink signal are obtained and denoted as the first time-frequency domain parameters, including the downlink transmission timestamp. Downlink transmission frame sequence number Downlink transmission slot number Downlink transmission symbol sequence number Downlink RB transmission quantity The time-frequency domain parameters of these downlink signals acquired multiple times are arranged in a certain order to form a sequence of downlink signal time-frequency domain parameters, which records the characteristic information of the downlink signal in the time-frequency domain.

[0036] Step 203: Based on the uplink and downlink symbol time difference, perform reciprocal channel feature extraction on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence to obtain a reciprocal channel feature sequence, wherein the uplink and downlink symbol time difference is calculated based on the frame number, time slot number and symbol number.

[0037] In this invention, the coherence time is first estimated based on the communication scenario. And convert it into an equivalent frame interval. Then, Alice reads the uplink channel feature sequence in frame number order and searches the downlink signal time-frequency domain parameter sequence for frames with a time interval less than the coherence time. And sequences with the same frame number.

[0038] Furthermore, the uplink and downlink symbol time difference is calculated based on the frame sequence number, time slot sequence number, and symbol sequence number corresponding to uplink reception / downlink transmission. The formula is: ; in, Represents the parameter set; , which represents the time difference between the uplink channel feature frame number and the frame number of the downlink signal time-frequency domain parameter sequence, i.e., the time difference of the first frame number; , indicating the time difference of the first time slot number; , indicating the time difference of the first symbol.

[0039] When a sequence that meets the requirements exists in the time-frequency domain parameter sequence of the downlink signal, select... The sequence with the smallest absolute value is used as the reciprocal downlink sequence of the current uplink channel characteristic sequence.

[0040] Through the above steps, the reciprocal channel feature sequence is finally obtained. These sequences have the characteristic of uplink and downlink reciprocity and can be used for subsequent physical layer key generation.

[0041] In this invention, the base station can also choose to read the downlink signal time-frequency domain parameter sequence and the uplink channel feature sequence in frame number order to realize reciprocal channel feature extraction. The specific steps can refer to the above process of reciprocal channel feature extraction of uplink channel feature sequence and downlink signal time-frequency domain parameter sequence.

[0042] The reciprocal channel feature extraction method provided by this invention, with the provision of channel estimation and time-frequency domain parameter information interfaces, extracts the channel features and time-frequency domain parameters of the uplink and downlink shared channel based on the data transmission protocol of the physical uplink and downlink shared channel, thereby achieving non-interactive reciprocal channel feature sequence extraction.

[0043] Based on the above embodiments, obtaining the uplink channel feature sequence based on the first channel estimation result includes: Receive multiple uplink signals; During the decoding process of the physical uplink shared channel, channel estimation is performed on the demodulation reference signals corresponding to multiple uplink signals to obtain multiple first channel estimation results, and the timestamp, frame number, slot number, symbol number and resource block number corresponding to each first channel estimation result are obtained. Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first channel estimation results, the uplink channel feature sequence is obtained.

[0044] In this invention, the network device (receiving end) captures multiple uplink signals sent by the sending end (e.g., user equipment) from the air interface. These uplink signals carry user data, control information, and other content, serving as information carriers in the communication process.

[0045] The physical uplink / downlink shared channel is the uplink channel used to transmit user data and other information. In communication protocols, decoding the received uplink / downlink signals is a crucial step in recovering the original data. The decoding process involves various signal processing steps to eliminate noise, interference, and other factors introduced during transmission, thereby reconstructing the information sent by the transmitter.

[0046] DMRS is a specific signal embedded in the uplink / downlink signal, and its function is to assist the receiver in channel estimation. Channel estimation involves analyzing the received signal (DMRS) to infer the channel characteristics experienced by the signal during transmission, such as channel fading and phase changes. In this invention, the base station obtains the channel estimation result of the corresponding DMRS during the PUSCH decoding process. (i.e., the first channel estimation result) By performing channel estimation on the DMRS corresponding to multiple uplink signals, multiple channel estimation results can be obtained.

[0047] Then, a series of time-frequency domain parameters are obtained, including: Uplink Receive Timestamp Used to record the specific time point when the channel estimation results occur, accurate to a certain time unit, which helps to analyze and track channel characteristics in the time dimension.

[0048] Uplink received frame sequence number Communication systems typically divide time into frames, and the frame number is used to identify the frame in which the current channel estimation result is located, which facilitates segmented management and analysis of the entire communication process.

[0049] Uplink receive time slot number Within each frame, it is further divided into multiple time slots. The time slot number is used to determine the specific time slot position of the channel estimation result within the frame, thus more precisely locating the time unit of signal transmission.

[0050] Uplink received symbol sequence number Each time slot contains multiple symbols, which are smaller units of time. The symbol number is used to accurately indicate the symbol position corresponding to the channel estimation result, further refining the time positioning.

[0051] Uplink received resource block count In the frequency domain, the available frequency band is divided into multiple resource blocks (RBs). The number of resource blocks is used to represent the range of frequency domain resources involved in the channel estimation results, reflecting the occupancy of the signal in the frequency domain.

[0052] This invention obtains the aforementioned time-frequency domain parameters, thereby accurately describing the time-frequency position of each channel estimation result.

[0053] In one embodiment, a sufficiently large number of execution rounds, n, is selected based on the communication scenario, and the process is repeated n times to obtain n sets of channel estimation results and time-frequency domain parameters. In practice, to obtain more comprehensive and accurate uplink channel characteristics, the above process of receiving signals, channel estimation, and obtaining time-frequency domain parameters needs to be repeated multiple times. The selection of the number of execution rounds, n, needs to be determined based on the specific communication scenario, such as the complexity of the communication environment and the required accuracy of channel characteristics. The number of execution rounds is pre-measured and statistically obtained by the physical layer key generation algorithm to determine the appropriate number of execution rounds for different scenarios, ensuring that various characteristics of the uplink channel can be fully captured.

[0054] By repeatedly executing the above process, multiple sets of first channel estimation results and their corresponding time-frequency domain parameters are obtained. These data are then arranged and combined in a specific order (e.g., according to timestamps) to form an uplink channel characteristic sequence. This sequence contains characteristic information of the uplink channel at different times and frequency domain positions, comprehensively reflecting the changes in the uplink channel and providing crucial information for subsequent communication system optimization, secure key generation, and other operations. For example, in physical layer secure communication, the uplink channel characteristic sequence can be used to generate physical layer keys, achieving more secure communication; in terms of communication system optimization, the analysis of the channel characteristic sequence allows for the adjustment of system parameters, improving communication quality and efficiency.

[0055] Based on the above embodiments, obtaining the downlink signal time-frequency domain parameter sequence based on the first time-frequency domain parameter includes: Send multiple downlink signals; During the coding process of the physical downlink shared channel, the first time-frequency domain parameters of the demodulation reference signals corresponding to the multiple downlink signals are obtained; Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first time-frequency domain parameters, the downlink signal time-frequency domain parameter sequence is obtained.

[0056] In this invention, the base station sends multiple downlink signals to the terminal. For example, in a mobile communication network, the base station continuously sends multiple downlink signals, which may contain different service data and are dynamically adjusted and sent according to factors such as network conditions and user needs. The base station transmits the encoded and modulated signals through a wireless channel according to certain rules and protocols so that the receiving end (terminal) can receive and process them.

[0057] PDSCH is a downlink channel used to transmit important information such as user data. Before transmitting downlink signals, the base station needs to encode the data. The encoding process includes multiple steps such as source coding and channel coding. Source coding is used to compress data, remove redundancy, and improve transmission efficiency; channel coding is used to increase data redundancy so that possible errors can be detected and corrected during transmission, ensuring reliable data transmission.

[0058] DMRS is a specific signal embedded in downlink / uplink signals. Terminals can use DMRS to estimate channel characteristics, such as channel fading and phase changes, thereby compensating and correcting the received signal and recovering the original transmitted data.

[0059] During PDSCH encoding, the base station determines the time-frequency domain parameters of the DMRS corresponding to the downlink signal according to the communication protocol. These parameters include: Uplink transmission timestamp Used to accurately record the specific time point of DMRS transmission, which helps to locate and analyze the signal in the time dimension, ensuring that the terminal can receive and process the signal at the correct time.

[0060] Uplink transmission frame sequence number Communication systems typically divide time into frames, with frame numbers used to identify the current frame in which the DMRS is located. This facilitates segmented management and scheduling of the entire communication process, such as transmitting different types of data or performing different control operations in different frames.

[0061] Uplink transmission slot sequence number Each frame is further divided into multiple time slots. The time slot number is used to determine the specific time slot position of DMRS within the frame, which allows for more detailed allocation of time resources and improves the time slot utilization of the communication system.

[0062] Uplink transmission symbol sequence number Each time slot contains multiple symbols, which are smaller units of time. The symbol number is used to precisely indicate the symbol position corresponding to the DMRS, further refining the time positioning and ensuring that the terminal can accurately identify and process the DMRS.

[0063] Uplink RB number In the frequency domain, the communication system divides the available frequency band into multiple resource blocks (RBs). The number of RBs represents the range of frequency domain resources occupied by the DMRS, reflecting the distribution of the signal in the frequency domain. The terminal can extract the DMRS at the corresponding frequency domain location based on this parameter.

[0064] Since the base station needs to send multiple downlink signals, it will acquire multiple time-frequency domain parameters of DMRS, namely the first time-frequency domain parameters.

[0065] In one embodiment, the base station selects a sufficiently large number of execution rounds, n, based on the communication scenario, and repeatedly executes the relevant process to obtain n sets of time-frequency domain parameters. In actual communication, in order to obtain the time-frequency domain characteristics of the downlink signal more comprehensively and accurately, it is necessary to repeatedly send the downlink signal and obtain the corresponding time-frequency domain parameters. The selection of the number of execution rounds, n, needs to be determined based on the specific communication scenario, such as the complexity of the communication environment and the required accuracy of the time-frequency domain parameters.

[0066] In this invention, the number of execution rounds can be pre-measured and statistically obtained by the physical layer key generation algorithm to determine the appropriate number of execution rounds for different scenarios, so as to ensure that various changing characteristics of the downlink signal in the time-frequency domain can be fully captured. For example, in high-speed mobile communication scenarios, the channel changes rapidly, and a larger number of execution rounds may be needed to obtain a sufficient number of time-frequency domain parameter samples; while in static or low-speed mobile scenarios, the number of execution rounds can be relatively small.

[0067] By repeatedly transmitting downlink signals and acquiring time-frequency domain parameters as described in the above embodiments, multiple sets of first time-frequency domain parameters are obtained. These parameters are then arranged and combined in a specific order (e.g., according to the order of timestamps) to form a downlink signal time-frequency domain parameter sequence. This sequence contains the time-frequency domain characteristic information of the downlink signal at different times and frequency domain positions, comprehensively reflecting the changes in the downlink signal during transmission. For example, by analyzing the time-frequency domain parameter sequence, the time-varying characteristics of the channel and frequency-selective fading can be understood, providing important basis for communication system optimization, resource allocation, and physical layer secure communication. In physical layer secure communication, the downlink signal time-frequency domain parameter sequence can be used to generate physical layer keys, achieving more secure communication; in terms of communication system resource allocation, time-frequency resources can be rationally allocated based on the time-frequency domain parameter sequence, improving the system's transmission efficiency and performance. Figure 3 This is a schematic diagram of the time-frequency domain parameters and channel feature sequences provided by the present invention. The overall data structure of the channel feature sequences and time-frequency domain parameters extracted by the present invention can be referred to. Figure 3 As shown.

[0068] Based on the above embodiments, the reciprocal channel feature extraction of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain the reciprocal channel feature sequence includes: Read the uplink channel feature sequence based on the frame sequence number, and sequentially obtain the uplink channel feature frame sequence number in the current uplink channel feature sequence; Based on a preset coherence time, at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame sequence is determined from multiple downlink signal time-frequency domain parameter sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; The uplink and downlink symbol time difference is calculated based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence. The downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the current target uplink-downlink symbol time difference is the uplink-downlink symbol time difference with the smallest absolute value.

[0069] In this invention, the base station reads the uplink channel feature sequence in frame number order. During communication, uplink channel feature data is transmitted and stored in units of frames, each frame having its own specific frame number. The base station uses a specific reading mechanism to sequentially obtain the frame number of each frame from the stored or transmitted uplink channel feature sequence, thereby determining the position of the currently processed uplink channel feature frame within the entire sequence. For example, assuming the uplink channel feature sequence has 10 frames, the base station will sequentially read the frame numbers of frame 1, frame 2, ..., frame 10 for subsequent processing of each frame.

[0070] In this invention, the base station first estimates the coherence time based on the communication scenario. (Unit: seconds). Coherence time Coherence time is a parameter closely related to the communication scenario. Different communication scenarios (such as indoor, outdoor, high-speed and low-speed mobile) have different channel characteristics, which affect the correlation of signals in the time domain and thus the estimation of coherence time. For example, in high-speed mobile scenarios, the channel changes rapidly, and the coherence time is relatively short; while in low-speed mobile or stationary scenarios, the channel changes slowly, and the coherence time is relatively long.

[0071] Obtaining coherence time Subsequently, the base station searches the downlink time-frequency domain parameter sequence for frames with a time interval less than the coherence time that are currently in the uplink channel feature frame. The sequence. Specifically, after the base station reads the uplink channel feature sequence in frame number order, it searches the downlink time-frequency domain parameter sequence for a time interval less than the coherence time of the current frame. And the same sequence as the current frame.

[0072] When the downlink signal time-frequency domain parameter sequence does not have a sequence that meets the requirements (i.e., the current frame time interval is less than the coherence time) (And sequences with the same frame number), the frame interval increases by 1 frame at a time until the frame interval equals 1 / 2. Continue searching for sequences that meet the time interval and frame interval requirements, and calculate the uplink and downlink symbol time difference. When the frame interval is greater than... If no sequence meets the requirements, discard the current channel feature sequence.

[0073] Specifically, if no matching sequence is found, the search range is expanded, and the frame interval is increased by one frame at a time until the frame interval equals the preset frame interval. The search continues until a sequence or frame interval that meets the criteria is found is found. And there is no sequence that meets the requirements (in this case, the current channel feature sequence is discarded), where the preset frame interval is... Coherence time Equivalent to Through this search process, at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame is determined.

[0074] Once the time-frequency domain parameter sequence of the target downlink signal is found, the base station calculates the uplink and downlink symbol time difference according to a specific formula. : .

[0075] By analyzing the differences in frame number, slot number, and symbol number between uplink and downlink, combined with parameter sets... The time difference between uplink and downlink symbols is accurately calculated. This time difference reflects the relative temporal position of the uplink and downlink signals and is used for subsequent reciprocal channel feature extraction.

[0076] Furthermore, the base station selects from the downlink signal time-frequency domain parameter sequence that meets the conditions. The sequence with the smallest absolute value is used as the reciprocal downlink sequence of the current uplink channel characteristic sequence. The uplink and downlink symbol time difference with the smallest absolute value indicates the highest degree of time matching between the uplink and downlink signals, better reflecting the reciprocity of the channel. For example, if there are multiple downlink signal time-frequency domain parameter sequences, the uplink and downlink symbol time differences between them and the current uplink channel characteristic sequence are calculated as follows: =2、 =-1、 =3, then the smallest absolute value is The corresponding downlink signal time-frequency domain parameter sequence will be selected as the reciprocal downlink sequence.

[0077] If this reciprocal downlink sequence is already matched, compare the current... Compared with the previous one The matching sequence is updated based on the comparison results. When multiple reciprocal downlink sequences exist in the uplink channel feature sequence, the sequence is updated according to the RB length and... The positive and negative rules select a unique reciprocal downlink sequence.

[0078] In one embodiment, when the reciprocal downlink sequence is in a matched state, the base station side will... Compared with the previous one (recorded as) Compare them. If < Discard the previously matched channel feature sequence, and the current channel feature sequence is compared with... The corresponding downlink sequence is matched as a reciprocal sequence, and the downlink sequence is set to a matched state; if ≥ ,choose The sequence with the second smallest absolute value is the reciprocal downlink sequence of the current uplink channel characteristic sequence.

[0079] Furthermore, when there are two or more reciprocal downlink sequences in the uplink channel characteristic sequence, the reciprocal downlink sequence with the largest RB length is selected as the unique reciprocal downlink sequence; if the RB lengths are equal, the sequence with the largest RB length is selected. A positive sequence is a unique reciprocal downlink sequence. These rules ensure that the final determined reciprocal channel characteristic sequence is optimal.

[0080] In this invention, the RB lengths of the reciprocal uplink channel characteristic sequence and the downlink signal time-frequency domain parameter sequence can also be compared. When they are inconsistent, the smaller RB length is used as the reference length to truncate the reciprocal uplink and downlink sequences.

[0081] Specifically, the base station can compare the RB lengths of the reciprocal uplink channel feature sequence and the downlink time-frequency domain parameter sequence. When the uplink and downlink RB lengths are inconsistent, the smaller RB length is used as the reference length to truncate the reciprocal uplink and downlink sequences, thereby ensuring the consistency of the uplink and downlink channel feature sequences in terms of data length, which facilitates subsequent channel processing and analysis.

[0082] Based on the above embodiments, determining at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame sequence from multiple downlink signal time-frequency domain parameter sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the downlink signal time-frequency domain parameter sequence and the current uplink channel characteristic frame number; The downlink signal time-frequency domain parameter sequence that has a time interval less than the preset coherence time and whose frame number is the same as the current uplink channel feature frame number is determined as the target downlink signal time-frequency domain parameter sequence.

[0083] In this invention, data in the communication system is transmitted and processed in units of frames. Each frame has a specific frame number, which not only identifies the order of the frames but also implies time information. Different frames are sent and received at different times, and there is a fixed time interval between frames.

[0084] When the base station reads the uplink channel feature sequence in frame number order, it obtains the frame number of the currently processed uplink channel feature frame. Simultaneously, the downlink signal time-frequency domain parameter sequence also corresponds to a specific frame number. Then, the time interval between the downlink frame and the current uplink frame is calculated. Since frames are transmitted continuously in time, if the system's frame structure and time base are known, the time interval can be calculated based on the difference in frame numbers.

[0085] Coherence time This value is estimated based on the type of current communication scenario and reflects the correlation of the channel in the time domain. During the coherence time, the characteristics of the channel can be considered essentially constant, meaning that the uplink and downlink channels are reciprocal. For example, in low-speed indoor communication scenarios, channel changes are relatively slow, and the coherence time may be long; while in high-speed outdoor scenarios, channel changes are rapid, and the coherence time is short.

[0086] In this invention, to ensure that the downlink signal and the current uplink signal are sufficiently close in time, one of the conditions for channel reciprocity is that the time interval is less than a preset coherence time. If the time interval is greater than the coherence time, the channel may have changed significantly, and the uplink and downlink channels no longer have reciprocity. In this case, the downlink signal cannot be used as a reciprocity reference for the current uplink signal.

[0087] Simultaneously, the frame sequence number is the same as the current uplink channel characteristic frame sequence number to ensure that the downlink signal corresponds logically to the current uplink signal. Even if the time interval meets the requirement, if the frame sequence numbers do not match, it may mean that the downlink signal is a response to other uplink signals or contains errors, and cannot be used as the reciprocal downlink sequence of the current uplink signal. Combining the above two conditions, the time-frequency domain parameter sequence of the corresponding downlink signal can be more accurately determined as the time-frequency domain parameter sequence of the target downlink signal.

[0088] Based on the above embodiments, the method further includes: When the time interval is less than the preset coherence time and there is no downlink signal time-frequency domain parameter sequence with the same frame number as the current uplink channel feature frame number, the downlink signal time-frequency domain parameter sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target downlink signal time-frequency domain parameter sequence, wherein the preset frame interval is obtained based on the preset coherence time.

[0089] In this invention, the base station processes the uplink channel feature sequence and attempts to find a matching target sequence from the downlink signal time-frequency domain parameter sequence. Normally, it first searches for a time interval shorter than a preset coherence time. Furthermore, the downlink signal time-frequency domain parameter sequence must have the same frame number as the current uplink channel feature frame number. However, there is a special case where no downlink signal time-frequency domain parameter sequence satisfying the above two conditions can be found within the current search range. In this case, a special processing strategy is required.

[0090] Preset frame interval Based on preset coherence time This is obtained through equivalent conversion. In communication systems, a frame is the basic unit of data transmission, and there is a fixed time interval between frames. To transform the time-domain concept of coherence time into a frame-domain concept, so as to facilitate searching and matching in a frame sequence, an equivalent conversion is required.

[0091] In this invention, assuming the duration of each frame in the system is 0.01 seconds, the coherence time is estimated through the communication scenario. (Unit: seconds) After that, a suitable preset frame interval needs to be found. , making Preset frame interval A maximum range for searching within a frame sequence is defined, representing the maximum forward or backward search centered on the current uplink frame. Within the frame range, search for downlink signal time-frequency domain parameter sequences that meet the conditions.

[0092] Furthermore, when the time interval is less than the preset coherence time... If, within the specified range, there is no downlink signal time-frequency domain parameter sequence with the same frame number as the current uplink channel characteristic frame number, it indicates that no suitable target sequence has been found under the current strict matching conditions. In this case, a more flexible search strategy is adopted: sequentially increasing the frame interval. Specifically, the initial frame interval can be considered as 0 (i.e., only searching downlink frames with the same frame number as the current uplink frame). When a search fails, the frame interval is sequentially increased by 1 frame. For example, after the first increase in frame interval, the search range expands to the range of one frame before and after the current uplink frame; after the second increase in frame interval, the search range expands to the range of two frames before and after the current uplink frame, and so on, until the frame interval equals the preset frame interval. .

[0093] During the search process where the frame interval increases sequentially, once a time interval less than the preset coherence time is found... And the frame interval increases to meet the preset frame interval. Once the downlink signal time-frequency domain parameter sequence is determined, this sequence is identified as the target downlink signal time-frequency domain parameter sequence. After determining the target downlink signal time-frequency domain parameter sequence, the base station needs to calculate the uplink and downlink symbol time difference using the formula for calculating the uplink and downlink symbol time difference.

[0094] If the frame interval is greater than If no suitable time-frequency domain parameter sequence exists, it means that a downlink signal time-frequency domain parameter sequence matching the current uplink channel feature sequence cannot be found in the current communication scenario. In this case, the current channel feature sequence should be discarded, as continuing to process it may not yield effective results and would waste system resources. The base station can then process the next uplink channel feature sequence and repeat the search and matching process described above.

[0095] Based on the above embodiments, the step of calculating the uplink / downlink symbol time difference based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence includes: Obtain the first time slot number and the first symbol number, wherein the first time slot number represents the time slot number corresponding to the current uplink channel feature frame number; and the first symbol number represents the symbol number corresponding to the current uplink channel feature frame number. Obtain the second time slot number and the second symbol number, wherein the second time slot number represents the time slot number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence; and the second symbol number represents the symbol number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence. Calculate the first frame sequence time difference between the current uplink channel feature frame sequence number and the frame sequence number of the target downlink signal time-frequency domain parameter sequence; Calculate the time difference between the first time slot number and the second time slot number; Calculate the first symbol time difference between the first symbol sequence number and the second symbol sequence number; The uplink and downlink symbol time differences are calculated based on the first frame sequence number time difference, the first time slot number time difference, and the first symbol time difference.

[0096] In this invention, the first time slot number represents the time slot number corresponding to the current uplink channel characteristic frame number. In a communication system, a frame is the basic unit of data transmission, and a frame is divided into multiple time slots, each of which can carry a certain number of symbols. By determining the current uplink channel characteristic frame number, the specific time slot number within that frame can be further located.

[0097] The first symbol number represents the symbol number corresponding to the current uplink channel characteristic frame number. Each time slot contains multiple symbols; a symbol is the smallest unit of data transmission and carries the actual information. After determining the current uplink channel characteristic frame number, the specific symbol number in the specific time slot within that frame can be found.

[0098] The second time slot number represents the time slot number corresponding to the frame number of the target downlink signal's time-frequency domain parameter sequence. The target downlink signal's time-frequency domain parameter sequence is determined after a series of search and matching processes and is correlated with the current uplink channel characteristic sequence. After determining the frame number of the target downlink signal, it is also necessary to locate the specific time slot number within that frame.

[0099] The second symbol number represents the symbol number corresponding to the frame number of the target downlink signal's time-frequency domain parameter sequence. After finding the frame number and time slot number of the target downlink signal, the specific symbol number within that time slot is further determined to facilitate subsequent calculation of the uplink and downlink symbol time difference.

[0100] First frame sequence number time difference Indicates the current uplink channel feature frame number Frame number of the time-frequency domain parameter sequence of the target downlink signal The time difference between uplink and downlink signals. This time difference reflects the time interval between uplink and downlink signals at the frame level, and is calculated using the following formula: .

[0101] First time slot time difference Indicates the first time slot number With the second time slot number The time difference between them reflects the time interval between uplink and downlink signals at the time slot level, and the calculation formula is as follows: .

[0102] First symbol time difference Indicates the first symbol number With the second symbol number The time difference between them reflects the time interval between uplink and downlink signals at the symbol level, and the calculation formula is as follows: .

[0103] Furthermore, according to the given formula The time difference of the first frame sequence number calculated in the above embodiment. Time difference of the first time slot number Time difference with the first symbol Substituting these values ​​into the formula allows for the accurate calculation of the uplink and downlink symbol time difference. In this invention, This represents a parameter set, with different parameter sets corresponding to different parameters such as subcarrier spacing and symbol duration.

[0104] Based on the above embodiments, determining the reciprocal channel feature sequence as the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel feature sequence includes: When the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference is a reciprocal downlink sequence of the previous uplink channel feature sequence, the current target uplink-downlink symbol time difference is compared with the previous target uplink-downlink symbol time difference. If it is determined that the current target uplink and downlink symbol time difference is less than the previous target uplink and downlink symbol time difference, the previous uplink channel feature sequence is discarded, and the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence. If it is determined that the current target uplink and downlink symbol time difference is greater than or equal to the previous target uplink and downlink symbol time difference, the downlink signal time-frequency domain parameter sequence corresponding to the current second smallest absolute uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

[0105] In this invention, to achieve efficient utilization of uplink and downlink channel reciprocity, it is necessary to find a downlink signal time-frequency domain parameter sequence that matches the current uplink channel feature sequence. This matching relationship can be measured by the uplink and downlink symbol time difference. The smaller the uplink and downlink symbol time difference, the better the temporal alignment of the uplink and downlink channel features, and the higher the matching degree.

[0106] In this invention, the system maintains a set of matched downlink signal time-frequency domain parameter sequences, each of which has established a reciprocal relationship with a certain uplink channel feature sequence. When processing the current uplink channel feature sequence, it checks whether the downlink signal time-frequency domain parameter sequence corresponding to the currently calculated target uplink-downlink symbol time difference already exists in the system as a reciprocal downlink sequence of the previous uplink channel feature sequence. If so, the subsequent comparison and decision-making process begins.

[0107] In one embodiment, it is assumed that a reciprocal downlink signal time-frequency domain parameter sequence D1 has been found for the uplink channel feature sequence U1, and the uplink and downlink symbol time differences between them have been recorded. Now, a new uplink channel feature sequence U2 is processed, and its uplink and downlink symbol time differences with multiple downlink signal time-frequency domain parameter sequences are calculated. It is found that the downlink sequence corresponding to one of the time differences is D1, and at this point, the initial condition is satisfied.

[0108] After satisfying the initial conditions, the target uplink and downlink symbol time difference (denoted as ) is calculated from the current uplink channel characteristic sequence. The uplink and downlink symbol time difference (denoted as ) corresponding to the previous uplink channel characteristic sequence Then, a numerical comparison is performed. This step is to determine whether the currently found match is better than the previously recorded matches.

[0109] If the currently calculated uplink and downlink symbol time difference Less than the uplink and downlink sign time difference of the previous record This indicates that the currently found downlink signal time-frequency domain parameter sequence has a higher degree of matching with the current uplink channel feature sequence and is more time-aligned. Therefore, the previous uplink channel feature sequence that established a reciprocal relationship with this downlink sequence will be discarded (because the current match is better), and the current uplink channel feature sequence and the corresponding downlink signal time-frequency domain parameter sequence will be determined as the new reciprocal channel feature sequence, while updating the relevant matching status information.

[0110] If the currently calculated uplink and downlink symbol time difference Greater than or equal to the sign time difference between the previous record and the previous record This indicates that the current match is not as good as the previously recorded match. In this case, the current match will not be selected. Instead, the downlink signal time-frequency domain parameter sequence corresponding to the second smallest absolute time difference from all calculated uplink and downlink symbol time differences will be selected and used to determine the reciprocal channel feature sequence along with the current uplink channel feature sequence. This is done to find a more suitable match while ensuring a certain degree of matching.

[0111] By following the steps above, the optimal uplink and downlink channel matching relationship can be dynamically selected, thereby improving the efficiency and accuracy of channel reciprocity utilization.

[0112] Based on the above embodiments, the method further includes: If it is determined that there are multiple downlink signal time-frequency domain parameter sequences corresponding to the current target uplink and downlink symbol time differences, all of which are reciprocal downlink sequences of the current uplink channel feature sequence, then the reciprocal downlink sequence with the maximum resource block length and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

[0113] In uplink and downlink channel reciprocity processing, an uplink channel feature sequence may find multiple matching downlink signal time-frequency domain parameter sequences, i.e., multiple reciprocal downlink sequences exist. However, for the simplicity and effectiveness of subsequent processing, it is necessary to select a unique reciprocal downlink sequence from these multiple reciprocal downlink sequences and combine it with the current uplink channel feature sequence to form a reciprocal channel feature sequence. In this invention, the selection rules are mainly based on two key factors: resource block (RB) length and uplink / downlink symbol time difference.

[0114] Specifically, when processing the current uplink channel feature sequence, the uplink and downlink symbol time differences between the uplink channel feature sequence and multiple downlink signal time-frequency domain parameter sequences are calculated. When it is found that there are more than one downlink signal time-frequency domain parameter sequence that meets certain matching conditions with the target uplink and downlink symbol time differences calculated from the current uplink channel feature sequence, and thus can all be considered as reciprocal downlink sequences of the current uplink channel feature sequence, the subsequent conditional judgment scenario is entered.

[0115] In the presence of multiple reciprocal downlink sequences, the resource block (RB) lengths corresponding to these sequences are first compared. A resource block is the basic unit used to allocate spectrum resources in a communication system. A larger RB length means a stronger information transmission capacity carried by the downlink sequence, enabling more efficient use of spectrum resources for data transmission. Therefore, the reciprocal downlink sequence with the largest RB length is selected, and it, along with the current uplink channel characteristic sequence, is determined as the reciprocal channel characteristic sequence.

[0116] Through the above steps, this invention can rationally and effectively select a unique reciprocal downlink sequence based on two key factors: resource block length and uplink / downlink symbol time difference, when multiple reciprocal downlink sequences exist. This reciprocal downlink sequence is then combined with the current uplink channel characteristic sequence to form a reciprocal channel characteristic sequence, providing accurate and reliable channel information for subsequent communication processing.

[0117] Based on the above embodiments, the method further includes: In the case of multiple reciprocal downlink sequences with maximum resource block length, the target reciprocal downlink sequence and the current uplink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the target reciprocal downlink sequence represents a reciprocal downlink sequence with a positive uplink-downlink symbol time difference among multiple reciprocal downlink sequences with maximum resource block length.

[0118] In this invention, when processing the current uplink channel feature sequence, the matching degree between the uplink channel feature sequence and multiple downlink signal time-frequency domain parameter sequences is calculated. One key indicator is the resource block length. After calculation and comparison, it is found that there are more than one downlink signal time-frequency domain parameter sequence that not only forms a reciprocal relationship with the current uplink channel feature sequence, but also has the largest corresponding resource block length among all possible reciprocal downlink sequences. In this case, a subsequent screening process is required to determine the unique target reciprocal downlink sequence.

[0119] Specifically, when multiple reciprocal downlink sequences with the maximum resource block length exist, the uplink and downlink symbol time differences between these sequences and the current uplink channel characteristic sequence are further compared. The uplink and downlink symbol time difference reflects the degree of time alignment between the uplink and downlink channels. The positive reciprocal downlink sequence is used as the target reciprocal downlink sequence because, in the design and actual operation of communication systems... A positive value may indicate a better fit to the system's preset time relationship, better time alignment characteristics, or greater advantages for subsequent signal processing and communication operations. After determining the target reciprocal downlink sequence, it is combined with the current uplink channel characteristic sequence to obtain a unique reciprocal channel characteristic sequence. In one embodiment, if multiple reciprocal downlink sequences with positive uplink / downlink symbol time differences exist among multiple reciprocal downlink sequences of maximum resource block length, then performance-related indicators such as signal strength and signal-to-noise ratio can be used. By comprehensively comparing these indicators, the optimal one among the multiple reciprocal downlink sequences with positive uplink / downlink symbol time differences can be selected as the target reciprocal downlink sequence. Alternatively, if it is impossible to distinguish the quality of sequences through other explicit indicators, a random selection method can be used to determine one of the multiple reciprocal downlink sequences with positive uplink / downlink symbol time differences as the target reciprocal downlink sequence.

[0120] This invention, by comparing resource block lengths and then comparing uplink and downlink symbol time differences when the lengths are equal, ensures that a unique reciprocal downlink sequence is determined for the current uplink channel characteristic sequence, thus obtaining a unique reciprocal channel characteristic sequence. This avoids confusion and uncertainty caused by multiple possible matching sequences. Furthermore, selecting the reciprocal downlink sequence with the largest resource block length can fully utilize spectrum resources and improve information transmission efficiency; while selecting a sequence with a positive uplink and downlink symbol time difference helps improve uplink and downlink channel time alignment, reduces errors and interference in signal processing, and thus optimizes the performance of the entire communication system.

[0121] Figure 4 A schematic diagram of reciprocal uplink and downlink channel feature extraction provided by the present invention can be referred to. Figure 4As shown, the left side represents different frames of the uplink channel feature sequence, the right side represents different frames of the downlink signal time-frequency domain parameter sequence, and the arrow in the middle represents the correspondence between uplink and downlink frames, reflecting the reciprocity characteristics of the uplink and downlink channels.

[0122] exist Figure 4 The image is labeled with frames k-2, k-1, k, k+1, and k+2, which have corresponding frames in both the uplink and downlink channels. Each frame in the uplink channel is associated with a corresponding frame in the downlink channel. For example, the uplink frame k-2 is connected to the downlink frame k-2, and the uplink frame k-1 is connected to the downlink frame k-1. This indicates that, ideally, the uplink and downlink channels have a certain correspondence for the same frame number, reflecting the reciprocity of the channels.

[0123] When selecting reciprocal downlink sequences, the selection is based on the magnitude of the uplink and downlink symbol time difference. Sequences with small time differences that meet the criteria are chosen as reciprocal sequences to ensure effective utilization of channel reciprocity. In this invention, based on this frame correspondence relationship and strategies such as resource block length processing and time difference calculation, channel reciprocity can be effectively utilized, simplifying the channel estimation process and improving the efficiency and performance of the communication system. For example, by accurately matching uplink and downlink frames, uplink channel characteristics can be better utilized to infer downlink channel characteristics, reducing the number of pilot signals required for downlink channel estimation and thus saving system resources.

[0124] Based on the above embodiments, the method further includes: If the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

[0125] In this invention, after obtaining the reciprocal channel feature sequence, the resource block lengths allocated to its corresponding uplink channel feature sequence and downlink signal time-frequency domain parameter sequence are checked respectively. If the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence are not equal, the two resource block lengths are compared, and the smaller one is selected as the reference length for subsequent truncation processing. In this invention, selecting the smaller length as the reference ensures that the truncated sequence can completely retain valid information, while also making the uplink and downlink sequence lengths consistent.

[0126] In this invention, based on a determined smaller resource block length, both the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence are truncated, retaining the portion of the sequence equal to the reference length and removing the portion exceeding the reference length. After truncation, the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence are consistent, thus satisfying the requirements of subsequent signal processing and transmission operations.

[0127] By using a smaller resource block length as a baseline and truncating it, this invention can keep the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence consistent, retaining as much effective information as possible, and maximizing the utilization of effective information under existing conditions to improve the performance of the communication system.

[0128] Based on the above embodiments, the reciprocal channel feature extraction of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain the reciprocal channel feature sequence includes: Read the downlink signal time-frequency domain parameter sequence based on the frame sequence number, and sequentially obtain the downlink signal time-frequency domain parameter frame sequence number in the current downlink signal time-frequency domain parameter sequence; Based on a preset coherence time, at least one target uplink channel feature sequence corresponding to the current downlink signal time-frequency domain parameter frame number is determined from multiple uplink channel feature sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; The uplink and downlink symbol time difference is calculated based on the current downlink signal time-frequency domain parameter frame number and the target uplink channel characteristic sequence frame number. The uplink channel feature sequence corresponding to the current target uplink and downlink symbol time difference and the current downlink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence, wherein the current target uplink and downlink symbol time difference is the uplink and downlink symbol time difference with the smallest absolute value.

[0129] Based on the above embodiments, determining at least one target uplink channel feature sequence corresponding to the current downlink signal time-frequency domain parameter frame number from multiple uplink channel feature sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the uplink channel feature sequence and the frame number of the current downlink signal time-frequency domain parameter; The uplink channel feature sequence that has a time interval less than the preset coherence time and whose frame number is the same as the frame number of the current downlink signal time-frequency domain parameter is determined as the target uplink channel feature sequence.

[0130] Based on the above embodiments, the method further includes: If the time interval is less than the preset coherence time and there is no uplink channel feature sequence with the same frame number as the current downlink signal time-frequency domain parameter number, the uplink channel feature sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target uplink channel feature sequence, wherein the preset frame interval is obtained based on the preset coherence time.

[0131] Based on the above embodiments, the step of calculating the uplink / downlink symbol time difference based on the current downlink signal time-frequency domain parameter frame number and the frame number of the target uplink channel feature sequence includes: Obtain the third time slot number and the third symbol number, wherein the third time slot number represents the time slot number corresponding to the current downlink signal time-frequency domain parameter frame number; and the third symbol number represents the symbol number corresponding to the current downlink signal time-frequency domain parameter frame number. Obtain the fourth time slot number and the fourth symbol number, wherein the fourth time slot number represents the time slot number corresponding to the frame number of the target uplink channel feature sequence; and the fourth symbol number represents the symbol number corresponding to the frame number of the target uplink channel feature sequence. Calculate the second frame sequence time difference between the current downlink signal time-frequency domain parameter frame number and the frame number of the target uplink channel feature sequence; Calculate the time difference between the second time slot number and the third time slot number and the fourth time slot number; Calculate the second symbol time difference between the third symbol number and the fourth symbol number; The uplink and downlink symbol time differences are calculated based on the second frame sequence number time difference, the second slot number time difference, and the second symbol time difference.

[0132] Based on the above embodiments, determining the reciprocal channel feature sequence as the uplink channel feature sequence corresponding to the current target uplink-downlink symbol time difference and the current downlink signal time-frequency domain parameter sequence includes: When the uplink channel feature sequence corresponding to the current target uplink and downlink symbol time difference is a reciprocal uplink sequence of the previous downlink signal time-frequency domain parameter sequence, the current target uplink and downlink symbol time difference is compared with the previous target uplink and downlink symbol time difference. If it is determined that the current target uplink and downlink symbol time difference is less than the previous target uplink and downlink symbol time difference, the previous downlink signal time-frequency domain parameter sequence is discarded, and the uplink channel feature sequence corresponding to the current target uplink and downlink symbol time difference and the current downlink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence. If it is determined that the current target uplink and downlink symbol time difference is greater than or equal to the previous target uplink and downlink symbol time difference, the uplink channel feature sequence corresponding to the current second smallest absolute value uplink and downlink symbol time difference and the current downlink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence.

[0133] Based on the above embodiments, the method further includes: If it is determined that there are multiple uplink channel feature sequences corresponding to the current target uplink and downlink symbol time difference, all of which are reciprocal uplink sequences of the current downlink signal time-frequency domain parameter sequence, the reciprocal uplink sequence with the maximum resource block length and the current downlink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence.

[0134] Based on the above embodiments, the method further includes: In the case of multiple reciprocal uplink sequences with maximum resource block length, the target reciprocal uplink sequence and the current downlink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence, wherein the target reciprocal uplink sequence represents a reciprocal uplink sequence with a positive uplink-downlink symbol time difference among multiple reciprocal uplink sequences with maximum resource block length.

[0135] Based on the above embodiments, the method further includes: If the resource block lengths of the downlink signal time-frequency domain parameter sequence and the uplink channel feature sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

[0136] It should be noted that, in this invention, the base station can also choose to read the downlink signal time-frequency domain parameter sequence and the uplink channel feature sequence in frame number order to achieve reciprocal channel feature extraction. The extraction process of the reciprocal channel feature sequence based on the downlink signal time-frequency domain parameter sequence and the uplink channel feature sequence is similar to the extraction process of the reciprocal channel feature sequence based on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence provided in the above embodiments. Therefore, this invention will not elaborate on the extraction process of the reciprocal channel feature sequence based on the downlink signal time-frequency domain parameter sequence and the uplink channel feature sequence.

[0137] Furthermore, this invention chooses to generate and transmit the harmonic error correction information at the base station side, primarily because the base station has higher computing power and also to facilitate the subsequent synchronous distribution of other information (such as quantum keys) at the base station side. In actual deployment, the harmonic error correction information can also be generated and transmitted at the terminal side.

[0138] Figure 5 This is a second flowchart illustrating the reciprocal channel feature extraction method provided by the present invention, as shown below. Figure 5 As shown, this invention provides a reciprocal channel feature extraction method applied to a terminal, the method comprising: Step 501: Based on the second channel estimation result, obtain the downlink channel feature sequence, wherein the second channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the downlink signal.

[0139] In this invention, after the terminal (Bob on the terminal side) establishes a wireless communication connection with the network device (Alice on the base station side) through random access, Bob receives the downlink signal sent by Alice. .

[0140] According to the communication protocol, during the PDSCH decoding process, Bob obtains the channel estimation result of the corresponding demodulation reference signal (DMRS), which is denoted as the second channel estimation result. Simultaneously, record the time-frequency domain parameters corresponding to the channel estimation result, such as the downstream reception timestamp. Downlink received frame sequence number Downlink receive time slot number Downlink Received Symbol Sequence Number Number of downlink receive resource blocks (RBs) These channel estimation results, arranged in a certain order, constitute a downlink channel feature sequence, which reflects the characteristic information of the downlink channel.

[0141] Step 502: Based on the second time-frequency domain parameters, obtain the uplink signal time-frequency domain parameter sequence, wherein the second time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the uplink signal; In this invention, Bob sends an uplink signal to Alice via a wireless channel. During the PUSCH encoding process based on the communication protocol, the time-frequency domain parameters of the demodulation reference signal (DMRS) corresponding to the uplink signal are obtained and denoted as the second time-frequency domain parameters, including the uplink transmission timestamp. Uplink transmission frame sequence number Uplink transmission slot sequence number Uplink transmission symbol sequence number Number of uplink RBs sent The time-frequency domain parameters of these uplink signals acquired multiple times are arranged in a certain order to form an uplink signal time-frequency domain parameter sequence, which records the characteristic information of the uplink signal in the time-frequency domain.

[0142] Step 503: Based on the downlink-uplink symbol time difference, perform reciprocal channel feature extraction on the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence to obtain a reciprocal channel feature sequence, wherein the downlink-uplink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

[0143] In this invention, the coherence time is first estimated based on the communication scenario. And convert it into an equivalent frame interval. Then, Bob reads the uplink signal time-frequency domain parameter sequence in frame number order, and searches the downlink channel feature sequence for frames with a time interval less than the coherence time. And sequences with the same frame number.

[0144] Furthermore, based on the frame sequence number, time slot sequence number, and symbol sequence number corresponding to downlink reception / uplink transmission, the downlink / uplink symbol time difference is calculated. The formula is: ; in, Represents the parameter set; , which represents the time difference between the frame number of the uplink signal time-frequency domain parameter and the frame number of the downlink channel characteristic sequence, i.e., the time difference of the fourth frame number; , indicating the time difference of the fourth time slot number; , indicating the time difference of the fourth symbol.

[0145] When a sequence that meets the requirements exists in the downlink channel characteristic sequence, select... The sequence with the smallest absolute value is used as the reciprocal downlink sequence of the current uplink signal time-frequency domain parameter frame number.

[0146] Through the above steps, the reciprocal channel feature sequence is finally obtained. These sequences have the characteristic of uplink and downlink reciprocity and can be used for subsequent physical layer key generation.

[0147] In this invention, the terminal side can also choose to read the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence in frame number order to realize reciprocal channel feature extraction. The specific steps can refer to the above process of reciprocal channel feature extraction of uplink channel feature sequence and downlink signal time-frequency domain parameter sequence.

[0148] The reciprocal channel feature extraction method provided by this invention, with the provision of channel estimation and time-frequency domain parameter information interfaces, extracts the channel features and time-frequency domain parameters of the uplink and downlink shared channel based on the data transmission protocol of the physical uplink and downlink shared channel, thereby achieving non-interactive reciprocal channel feature sequence extraction.

[0149] Based on the above embodiments, obtaining the downlink channel feature sequence based on the second channel estimation result includes: Receive multiple downlink signals; During the decoding process of the physical downlink shared channel, channel estimation is performed on the demodulation reference signals corresponding to multiple downlink signals to obtain multiple second channel estimation results, and the timestamp, frame number, slot number, symbol number and resource block number corresponding to each second channel estimation result are obtained; Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the second channel estimation results, the downlink channel feature sequence is obtained.

[0150] In this invention, the terminal receives multiple downlink signals sent by network devices. These downlink signals carry user data, control information, and other content, serving as information carriers during the communication process.

[0151] In this invention, the terminal side obtains the channel estimation result of the corresponding DMRS during the PDSCH decoding process. (i.e., the second channel estimation result) By performing channel estimation on the DMRS corresponding to multiple downlink signals, multiple channel estimation results can be obtained.

[0152] Then, a series of time-frequency domain parameters are obtained, including: downlink receive timestamp. Downlink received frame sequence number Downlink receive time slot number Downlink Received Symbol Sequence Number Number of downlink received resource blocks This invention obtains the aforementioned time-frequency domain parameters to accurately describe the time-frequency position of each channel estimation result.

[0153] In one embodiment, by executing the above process multiple times, multiple sets of second channel estimation results and their corresponding time-frequency domain parameters are obtained. These data are arranged and combined in a certain order (e.g., according to the order of timestamps) to form a downlink channel feature sequence.

[0154] Based on the above embodiments, obtaining the uplink signal time-frequency domain parameter sequence based on the second time-frequency domain parameters includes: Send multiple uplink signals; During the coding process of the physical uplink shared channel, the second time-frequency domain parameters of the demodulation reference signals corresponding to the multiple uplink signals are obtained; Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the second time-frequency domain parameters, the uplink signal time-frequency domain parameter sequence is obtained.

[0155] In this invention, the terminal sends multiple uplink signals to the base station. The terminal transmits the coded and modulated signals through a wireless channel according to certain rules and protocols, so that the base station can receive and process them.

[0156] PUSCH is the uplink channel used to transmit important information such as user data. Before sending uplink signals, the terminal needs to encode the data.

[0157] DMRS is a specific signal embedded in the uplink signal. During PUSCH encoding, the terminal side determines the time-frequency domain parameters of the DMRS corresponding to the uplink signal according to the communication protocol. These parameters include: downlink transmission timestamp. Downlink transmission frame sequence number Downlink transmission slot number Downlink transmission symbol sequence number Downlink RB transmission quantity .

[0158] Since the terminal needs to send multiple uplink signals, it will obtain multiple time-frequency domain parameters of DMRS, namely the second time-frequency domain parameters.

[0159] In one embodiment, the terminal selects a sufficiently large number of execution rounds n based on the communication scenario and repeatedly executes the relevant process to obtain n sets of time-frequency domain parameters. In actual communication, in order to obtain the time-frequency domain characteristics of the uplink signal more comprehensively and accurately, it is necessary to repeatedly send the uplink signal and obtain the corresponding time-frequency domain parameters. The selection of the number of execution rounds n needs to be determined based on the specific communication scenario, such as the complexity of the communication environment and the required accuracy of the time-frequency domain parameters.

[0160] In this invention, the number of execution rounds can be pre-measured and statistically obtained by the physical layer key generation algorithm to determine the appropriate number of execution rounds in different scenarios, so as to ensure that various changing characteristics of the uplink signal in the time and frequency domain can be fully captured.

[0161] By repeatedly performing the process of sending uplink signals and acquiring time-frequency domain parameters as described in the above embodiments, multiple sets of second time-frequency domain parameters are obtained. These parameters are then arranged and combined in a specific order (e.g., according to the order of timestamps) to form an uplink signal time-frequency domain parameter sequence. This sequence contains time-frequency domain characteristic information of the uplink signal at different times and frequency positions, comprehensively reflecting the changes in the uplink signal during transmission. The overall data structure of the channel feature sequence and time-frequency domain parameters extracted by this invention can be found in [reference needed]. Figure 3 As shown.

[0162] Based on the above embodiments, the reciprocal channel feature extraction of the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence based on the downlink-uplink symbol time difference, to obtain the reciprocal channel feature sequence, includes: Read the uplink signal time-frequency domain parameter sequence based on the frame sequence number, and sequentially obtain the uplink signal time-frequency domain parameter frame sequence number in the current uplink signal time-frequency domain parameter sequence. Based on a preset coherence time, at least one target downlink channel feature sequence corresponding to the current uplink signal time-frequency domain parameter frame number is determined from multiple downlink channel feature sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; The uplink-downlink symbol time difference is calculated based on the current uplink signal time-frequency domain parameter frame number and the target downlink channel characteristic sequence frame number. The downlink channel feature sequence corresponding to the current target downlink symbol time difference and the current uplink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence, wherein the current target downlink symbol time difference is the downlink symbol time difference with the smallest absolute value.

[0163] In this invention, the terminal reads the uplink signal time-frequency domain parameter sequence in frame number order. During communication, the uplink signal time-frequency domain parameter sequence is transmitted and stored in units of frames, each frame having its own specific frame number. The terminal uses a specific reading mechanism to sequentially obtain the frame number of each frame from the stored or transmitted uplink signal time-frequency domain parameter sequence, thereby determining the position of the currently processed uplink signal time-frequency domain parameter frame within the entire sequence.

[0164] In this invention, the terminal side first estimates the coherence time based on the communication scenario. (Unit: seconds).

[0165] Obtaining coherence time Subsequently, the terminal searches the downlink channel feature sequence for frames with time-frequency domain parameters of the current uplink signal whose time interval is less than the coherence time. The sequence. Specifically, after the terminal reads the uplink signal time-frequency domain parameter sequence in frame number order, it searches the downlink channel feature sequence for a time interval less than the coherence time of the current frame. And the same sequence as the current frame.

[0166] When no matching sequence exists in the downlink channel feature sequence (i.e., the current frame time interval is less than the coherence time) (And sequences with the same frame number), the frame interval increases by 1 frame at a time until the frame interval equals 1 / 2. Continue searching for sequences that meet the time interval and frame interval requirements, and calculate the uplink and downlink symbol time difference. When the frame interval is greater than... If no sequence meets the requirements, discard the current time-frequency domain parameter frame number.

[0167] Specifically, if no matching sequence is found, the search range is expanded, and the frame interval is increased by one frame at a time until the frame interval equals the preset frame interval. The search continues until a sequence or frame interval that meets the criteria is found is found. And there is no sequence that meets the requirements (in this case, the current frequency domain parameter sequence is discarded), where the preset frame interval Coherence time Equivalent to Through this search process, at least one target downlink channel feature sequence corresponding to the current uplink signal time-frequency domain parameter frame is determined.

[0168] Once the target downlink channel characteristic sequence is found, the terminal side calculates the uplink symbol time difference according to a specific formula. : .

[0169] By analyzing the differences in frame number, slot number, and symbol number between uplink and downlink, combined with parameter sets... The time difference between downlink and uplink symbols is accurately calculated. This time difference reflects the relative temporal position of the downlink and uplink signals and is used for subsequent reciprocal channel feature extraction.

[0170] Furthermore, the terminal selects from the downlink channel feature sequence that meets the conditions. The sequence with the smallest absolute value is used as the reciprocal downlink sequence of the current uplink signal's time-frequency domain parameter sequence. The downlink-uplink symbol time difference with the smallest absolute value indicates the highest degree of time matching between the uplink and downlink signals, better reflecting the reciprocity of the channel.

[0171] If this reciprocal downlink sequence is already matched, compare the current... Compared with the previous one The matching sequence is updated based on the comparison results. When there are multiple reciprocal downlink sequences for the uplink signal's time-frequency domain parameter frame number, the sequence is updated according to the RB length and... The positive and negative rules select a unique reciprocal downlink sequence.

[0172] In one embodiment, when the reciprocal downlink sequence is in a matched state, the terminal side will... Compared with the previous one (recorded as) Compare them. If < Discard the previously matched time-frequency domain parameter sequence, and then match the current uplink signal time-frequency domain parameter sequence with... The corresponding downlink sequence is matched as a reciprocal sequence, and the downlink sequence is set to a matched state; if ≥ ,choose The sequence with the second smallest absolute value is the reciprocal downlink sequence of the current uplink signal time-frequency domain parameter sequence.

[0173] Furthermore, when there are two or more reciprocal downlink sequences in the uplink signal time-frequency domain parameter sequence, the reciprocal downlink sequence with the largest RB length is selected as the unique reciprocal downlink sequence; if the RB lengths are equal, the sequence with the largest RB length is selected. A positive sequence is a unique reciprocal downlink sequence. These rules ensure that the final determined reciprocal channel characteristic sequence is optimal.

[0174] In this invention, the reciprocal uplink signal time-frequency domain parameter frame number and the RB length of the downlink channel characteristic sequence can also be compared. When they are inconsistent, the smaller RB length is used as the reference length to truncate the reciprocal uplink and downlink sequences.

[0175] Specifically, the terminal side can compare the RB lengths of the reciprocal downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence. When the uplink and downlink RB lengths are inconsistent, the smaller RB length is used as the reference length to truncate the reciprocal uplink and downlink sequences, thereby ensuring the consistency of the uplink and downlink channel feature sequences in terms of data length, which facilitates subsequent channel processing and analysis.

[0176] Based on the above embodiments, determining at least one target downlink channel feature sequence corresponding to the current uplink signal time-frequency domain parameter frame number from multiple downlink channel feature sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the downlink channel feature sequence and the frame number of the current uplink signal time-frequency domain parameter; The downlink channel feature sequence that has a time interval less than the preset coherence time and whose frame number is the same as the frame number of the current uplink signal time-frequency domain parameter is determined as the target downlink channel feature sequence.

[0177] In this invention, when the terminal reads the uplink signal time-frequency domain parameter sequence in frame number order, it obtains the frame number of the currently processed uplink signal time-frequency domain parameter frame. Simultaneously, the downlink channel characteristic sequence also corresponds to a specific frame number. Then, the time interval between the downlink frame and the current uplink frame is calculated. Since frames are transmitted continuously in time, if the system's frame structure and time base are known, the time interval can be calculated based on the difference in frame numbers.

[0178] In this invention, in order to ensure that the downlink signal and the current uplink signal are sufficiently close in time, one of the conditions for channel reciprocity is that the time interval is less than the preset coherence time.

[0179] Simultaneously, the frame sequence number is the same as the current uplink channel feature frame sequence number. Combining these two conditions, the corresponding downlink channel feature sequence is more accurately determined as the target downlink channel feature sequence. Based on the above embodiment, the method further includes: If the time interval is less than the preset coherence time and there is no downlink channel feature sequence with the same frame number as the current uplink signal time-frequency domain parameter number, the downlink channel feature sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target downlink channel feature sequence. The preset frame interval is obtained based on the preset coherence time.

[0180] In this invention, the terminal side processes the uplink signal time-frequency domain parameter sequence and attempts to find a matching target sequence from the downlink channel feature sequence. Normally, it first searches for a time interval shorter than a preset coherence time. Furthermore, the downlink channel feature sequence must have the same frame number as the current uplink signal's time-frequency domain parameter frame number. However, there is a special case where no downlink channel feature sequence satisfying both conditions can be found within the current search range. In this case, a special processing strategy is required.

[0181] Furthermore, when the time interval is less than the preset coherence time... If, within the specified range, there is no downlink channel feature sequence with the same frame number as the current uplink signal's time-frequency domain parameter frame number, it indicates that no suitable target sequence has been found under the current strict matching conditions. In this case, a search strategy that sequentially increases the frame interval is adopted.

[0182] During the search process where the frame interval increases sequentially, once a time interval less than the preset coherence time is found... And the frame interval increases to meet the preset frame interval. Once the downlink channel characteristic sequence is determined, it is identified as the target downlink channel characteristic sequence. After determining the target downlink channel characteristic sequence, the terminal needs to calculate the uplink symbol time difference using the formula for calculating the uplink symbol time difference.

[0183] If the frame interval is greater than If no suitable channel feature sequence exists, it means that in the current communication scenario, a downlink channel feature sequence matching the current uplink signal time-frequency domain parameter sequence cannot be found. In this case, the current time-frequency domain parameter sequence should be discarded, as continuing to process it may not yield effective results and would waste system resources. The terminal can then process the next uplink signal time-frequency domain parameter sequence and repeat the search and matching process.

[0184] Based on the above embodiments, the step of calculating the uplink-downlink symbol time difference based on the current uplink signal time-frequency domain parameter frame number and the frame number of the target downlink channel feature sequence includes: Obtain the seventh time slot number and the seventh symbol number, wherein the seventh time slot number represents the time slot number corresponding to the current uplink signal time-frequency domain parameter frame number; and the seventh symbol number represents the symbol number corresponding to the current uplink signal time-frequency domain parameter frame number. Obtain the eighth time slot number and the eighth symbol number, wherein the eighth time slot number represents the time slot number corresponding to the frame number of the target downlink channel feature sequence; and the eighth symbol number represents the symbol number corresponding to the frame number of the target downlink channel feature sequence. Calculate the fourth frame sequence time difference between the current uplink signal time-frequency domain parameter frame number and the frame number of the target downlink channel feature sequence; Calculate the time difference of the fourth time slot number between the seventh time slot number and the eighth time slot number; Calculate the fourth symbol time difference between the eighth symbol sequence number and the eighth symbol sequence number; The downlink and uplink symbol time differences are calculated based on the fourth frame sequence number time difference, the fourth time slot number time difference, and the fourth symbol time difference.

[0185] In this invention, the seventh time slot number represents the time slot number corresponding to the frame number of the current uplink signal time-frequency domain parameter.

[0186] The seventh symbol number represents the symbol number corresponding to the frame number of the current uplink signal time-frequency domain parameter.

[0187] The eighth time slot number represents the time slot number corresponding to the frame number of the target downlink channel characteristic sequence. The target downlink channel characteristic sequence is determined after a series of search and matching processes and is related to the time-frequency domain parameter sequence of the current uplink signal. After determining the frame number of the target downlink signal, it is also necessary to locate the specific time slot number within that frame.

[0188] The eighth symbol number represents the symbol number corresponding to the frame number of the target downlink channel characteristic sequence. After finding the frame number and time slot number of the target downlink signal, the specific symbol number within that time slot is further determined in order to calculate the uplink symbol time difference subsequently.

[0189] Fourth frame sequence time difference Indicates the frame order of the current uplink signal's time-frequency domain parameters. Frame number of the target downlink channel characteristic sequence The time difference between them. This time difference reflects the time interval between the uplink and downlink signals at the frame level, and is calculated using the following formula: .

[0190] Fourth time slot number time difference Indicates the seventh time slot number With the eighth time slot number The time difference between them reflects the time interval between the uplink and downlink signals at the time slot level, and the calculation formula is as follows: .

[0191] Fourth symbol time difference Indicates the seventh symbol number With the eighth symbol number The time difference between them reflects the time interval between the uplink and downlink signals at the symbol level, and the calculation formula is as follows: .

[0192] Furthermore, according to the given formula The time difference of the fourth frame sequence number calculated in the above embodiment. Time difference of the fourth time slot Time difference with the fourth symbol Substituting into the formula, the uplink and downlink symbol time difference can be accurately calculated. .

[0193] Based on the above embodiments, determining the reciprocal channel feature sequence as the downlink channel feature sequence corresponding to the current target uplink symbol time difference and the current uplink signal time-frequency domain parameter sequence includes: When the downlink channel feature sequence corresponding to the current uplink symbol time difference under the target is a reciprocal downlink sequence of the time-frequency domain parameter sequence of the previous uplink signal, the current uplink symbol time difference under the target is compared with the previous uplink symbol time difference under the target. If it is determined that the uplink symbol time difference under the current target is less than the uplink symbol time difference under the previous target, the time-frequency domain parameter sequence of the previous uplink signal is discarded, and the downlink channel feature sequence corresponding to the uplink symbol time difference under the current target and the time-frequency domain parameter sequence of the current uplink signal are determined as the reciprocal channel feature sequence. If it is determined that the uplink symbol time difference under the current target is greater than or equal to the uplink symbol time difference under the previous target, the downlink channel feature sequence corresponding to the second smallest absolute value downlink symbol time difference and the current uplink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence.

[0194] In this invention, to achieve efficient utilization of uplink and downlink channel reciprocity, it is necessary to find a downlink channel feature sequence that matches the time-frequency domain parameter sequence of the current uplink signal. This matching relationship can be measured by the downlink-uplink symbol time difference. The smaller the downlink-uplink symbol time difference, the better the temporal alignment of the uplink and downlink channel features, and the higher the matching degree.

[0195] In this invention, the system maintains a set of matched downlink channel feature sequences, each of which has established a reciprocal relationship with a certain uplink signal time-frequency domain parameter sequence. When processing the current uplink signal time-frequency domain parameter sequence, it checks whether the downlink channel feature sequence corresponding to the currently calculated target downlink symbol time difference already exists in the system as a reciprocal downlink sequence of the previous uplink signal time-frequency domain parameter sequence. If so, the subsequent comparison and decision-making process begins.

[0196] After satisfying the initial conditions, the target coefficient line symbol time difference (denoted as ) is calculated from the current uplink signal time-frequency domain parameter sequence. The uplink symbol time difference (denoted as ) corresponding to the time-frequency domain parameter sequence of the previous uplink signal. Then, a numerical comparison is performed. This step is to determine whether the currently found match is better than the previously recorded matches.

[0197] If the currently calculated downlink / uplink symbol time difference Less than the uplink sign time difference of the previous record This indicates that the currently found downlink channel feature sequence has a higher degree of matching with the current uplink signal time-frequency domain parameter sequence and is more time-aligned. Therefore, the previous uplink signal time-frequency domain parameter sequence that established a reciprocal relationship with this downlink sequence will be discarded (because the current match is better), and the current uplink signal time-frequency domain parameter sequence and the corresponding downlink channel feature sequence will be determined as the new reciprocal channel feature sequence, while updating the relevant matching status information.

[0198] If the currently calculated downlink / uplink symbol time difference Greater than or equal to the next-to-upper sign time difference of the previous record This indicates that the current match is not as good as the previously recorded match. In this case, the current match will not be selected. Instead, the downlink channel feature sequence corresponding to the second smallest absolute value of the time difference between all calculated uplink and downlink symbols will be chosen, and this sequence, along with the current uplink signal's time-frequency domain parameter sequence, will be used to determine the reciprocal channel feature sequence. This is done to find a more suitable match while ensuring a certain degree of matching.

[0199] By following the steps above, the optimal uplink and downlink channel matching relationship can be dynamically selected, thereby improving the efficiency and accuracy of channel reciprocity utilization.

[0200] Based on the above embodiments, the method further includes: If it is determined that there are multiple downlink channel feature sequences corresponding to the uplink symbol time difference under the current target, all of which are reciprocal downlink sequences of the current uplink signal time-frequency domain parameter sequence, the reciprocal downlink sequence with the maximum resource block length and the current uplink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence.

[0201] In this invention, when processing the current uplink signal time-frequency domain parameter sequence, the uplink symbol time difference between the uplink signal time-frequency domain parameter sequence and multiple downlink channel feature sequences is calculated. When it is found that there are more than one downlink channel feature sequence that meets certain matching conditions with the target uplink symbol time difference calculated from the current uplink signal time-frequency domain parameter sequence, and thus can all be considered as reciprocal downlink sequences of the current uplink signal time-frequency domain parameter sequence, the subsequent condition judgment scenario is entered.

[0202] In the presence of multiple reciprocal downlink sequences, the reciprocal downlink sequence with the largest RB length is selected, and it and the current uplink signal time-frequency domain parameter sequence are used to determine the reciprocal channel characteristic sequence.

[0203] Through the above steps, this invention can rationally and effectively select a unique reciprocal downlink sequence based on two key factors: resource block length and coefficient row symbol time difference, when multiple reciprocal downlink sequences exist. This sequence, together with the current uplink signal time-frequency domain parameter sequence, forms a reciprocal channel feature sequence, providing accurate and reliable channel information for subsequent communication processing.

[0204] Based on the above embodiments, the method further includes: In the case of multiple reciprocal downlink sequences with maximum resource block length, the target reciprocal downlink sequence and the current uplink signal time-frequency domain parameter sequence are determined as the reciprocal channel feature sequence, wherein the target reciprocal downlink sequence represents the reciprocal downlink sequence with a positive downlink-to-uplink symbol time difference among the multiple reciprocal downlink sequences with maximum resource block length.

[0205] In this invention, when processing the current uplink signal time-frequency domain parameter sequence, the matching degree between the uplink signal time-frequency domain parameter sequence and multiple downlink channel feature sequences is calculated. One key indicator is the resource block length. After calculation and comparison, it is found that there are more than one downlink channel feature sequence that not only forms a reciprocal relationship with the current uplink signal time-frequency domain parameter sequence, but also has the largest corresponding resource block length among all possible reciprocal downlink sequences. In this case, a subsequent screening process is required to determine the unique target reciprocal downlink sequence.

[0206] Specifically, when multiple reciprocal downlink sequences with the maximum resource block length exist, the downlink-uplink symbol time difference between these sequences and the current uplink signal time-frequency domain parameter sequence is further compared. The uplink and downlink symbol time difference reflects the degree of time alignment between the uplink and downlink channels. The positive reciprocal downlink sequence is used as the target reciprocal downlink sequence because, in the design and actual operation of communication systems... A positive value may indicate a more consistent timing relationship with the system's preset time parameters, better time alignment characteristics, or greater advantages for subsequent signal processing and communication operations. After determining the target reciprocal downlink sequence, combining it with the current uplink signal's time-frequency domain parameter sequence yields a unique reciprocal channel characteristic sequence.

[0207] This invention, by comparing resource block lengths and then, when lengths are equal, comparing uplink symbol time differences, ensures a unique reciprocal downlink sequence for the current uplink signal's time-frequency domain parameter sequence, thereby obtaining a unique reciprocal channel characteristic sequence. This avoids confusion and uncertainty caused by multiple possible matching sequences. Furthermore, selecting the reciprocal downlink sequence with the largest resource block length fully utilizes spectrum resources and improves information transmission efficiency; while selecting a sequence with a positive uplink symbol time difference helps improve uplink channel timing alignment, reduces errors and interference in signal processing, and thus optimizes the performance of the entire communication system.

[0208] Based on the above embodiments, the method further includes: If the resource block lengths of the uplink signal time-frequency domain parameter sequence and the downlink channel feature sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

[0209] In this invention, after obtaining the reciprocal channel feature sequence, the resource block lengths allocated to its corresponding uplink signal time-frequency domain parameter sequence and downlink channel feature sequence are checked respectively. If the resource block lengths of the uplink signal time-frequency domain parameter sequence and the downlink channel feature sequence are not equal, the two resource block lengths are compared, and the smaller one is selected as the reference length for subsequent truncation processing. In this invention, selecting the smaller length as the reference ensures that the truncated sequence can completely retain valid information, while also making the uplink and downlink sequence lengths consistent.

[0210] In this invention, based on a determined smaller resource block length, both the uplink signal time-frequency domain parameter sequence and the downlink channel feature sequence are truncated, retaining the portion of the sequence equal to the reference length and removing the portion exceeding the reference length. After truncation, the resource block lengths of the uplink signal time-frequency domain parameter sequence and the downlink channel feature sequence are consistent, thus satisfying the requirements of subsequent signal processing and transmission operations.

[0211] This invention uses a smaller resource block length as a reference length and performs truncation processing, which enables the resource block lengths of the uplink signal time-frequency domain parameter sequence and the downlink channel feature sequence to be consistent, retaining as much effective information as possible, and maximizing the utilization of effective information under existing conditions to improve the performance of the communication system.

[0212] In one embodiment, the acquired channel estimation results and uplink / downlink time-frequency parameters can be filtered based on the relative moving speeds of the base station and the terminal, and the parameter set configuration. For example, when the parameter set is configured as 1, i.e., the subcarrier spacing is 30Hz, all channel estimation results are retained in a high-speed moving scenario; in a medium-speed moving scenario, one set of channel estimation results is retained for each half-frame; and in a low-speed moving scenario, one set of channel estimation results is retained for each frame.

[0213] Furthermore, before extracting uplink and downlink reciprocal channel features, it is assumed that the features obtained by the base station side... The group channel estimation results and time-frequency domain parameters are as follows: ; ; ; Acquired on the terminal side The group channel estimation results and time-frequency domain parameters are as follows: ; ; .

[0214] In other words, effective uplink and downlink channel estimation results and time-frequency domain parameters should satisfy the following characteristics: The length of the uplink channel feature sequence obtained by the base station is equal to the length of the uplink time-frequency domain parameter sequence obtained by the terminal. The length of the downlink channel feature sequence obtained by the terminal is equal to the length of the downlink time-frequency domain parameter sequence obtained by the base station.

[0215] To ensure that the channel feature sequences and time-frequency domain parameter sequences obtained by the base station and terminal sides meet the above characteristics, in this embodiment, it is necessary to filter the obtained sequences, such as removing redundant broadcast signals and control signals in the downlink channel and redundant control signals in the uplink channel, so as to obtain effective channel estimation results and time-frequency domain parameters.

[0216] Figure 6 The schematic diagram of the physical layer key generation process based on interactionless reciprocal channel feature extraction provided by this invention can be referred to. Figure 6 As shown, Alice and Bob first need to establish a communication connection.

[0217] Then, Alice and Bob each acquire the channel features. For Alice, by sending downlink information and combining it with the frequency domain parameters of the downlink information, she repeats this process n times to filter out the uplink channel features, ultimately obtaining the uplink channel feature sequence. Bob's operation is similar: he sends uplink information and uses the frequency domain parameters of the uplink information, repeating this process the same number of times to obtain his own downlink channel feature sequence.

[0218] In the process of acquiring channel feature sequences, the uplink and downlink symbol time difference needs to be considered. For example, Alice and Bob both need to calculate the uplink and downlink symbol time difference according to a specific calculation method (such as the formula mentioned in the above embodiment), and select a suitable channel feature sequence based on the magnitude of the time difference and other conditions (such as resource block length).

[0219] Furthermore, Alice and Bob each quantize the channel feature sequences they have obtained. They then use their respective quantized channel feature sequences to generate preliminary keys, which are referred to as Key (Alice) and Key (Bob), respectively.

[0220] Next, Alice and Bob exchange error correction information, attempting to ensure that the keys they generate are consistent. Since noise and interference may exist in actual communication, the initially generated keys may differ; the error correction step aims to eliminate these differences. If error correction fails, some previous steps may need to be repeated, such as re-extracting channel features or adjusting the error correction strategy. Only after successful error correction can the next step, privacy amplification, proceed.

[0221] Even after error correction, although the keys of both parties are now identical, potential security vulnerabilities may still exist. The privacy amplification step further processes the key using specific algorithms to enhance its confidentiality and security, ultimately generating a final key that can be used for encrypted communication.

[0222] By employing a series of operations such as quantization, encryption, error correction, and privacy amplification, secure keys are generated using channel characteristics, thereby enabling secure communication based on channel reciprocity.

[0223] Based on the above embodiments, the reciprocal channel feature extraction of the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence based on the downlink-uplink symbol time difference, to obtain the reciprocal channel feature sequence, includes: Read the downlink channel feature sequence based on the frame sequence number, and obtain the downlink channel feature frame sequence number in the current downlink channel feature sequence in sequence; Based on a preset coherence time, at least one target uplink signal time-frequency domain parameter sequence corresponding to the current downlink channel feature frame sequence is determined from multiple uplink signal time-frequency domain parameter sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; Based on the current downlink channel feature frame number and the frame number of the target uplink signal time-frequency domain parameter sequence, the downlink-uplink symbol time difference is calculated. The uplink signal time-frequency domain parameter sequence corresponding to the current target uplink symbol time difference and the current downlink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the current target uplink symbol time difference is the uplink and downlink symbol time difference with the smallest absolute value.

[0224] Based on the above embodiments, determining at least one target uplink signal time-frequency domain parameter sequence corresponding to the current downlink channel feature frame sequence from multiple uplink signal time-frequency domain parameter sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the uplink signal time-frequency domain parameter sequence and the current downlink channel characteristic frame number; The uplink signal time-frequency domain parameter sequence whose time interval is less than the preset coherence time and whose frame sequence number is the same as the current downlink channel feature frame sequence number is determined as the target uplink signal time-frequency domain parameter sequence.

[0225] Based on the above embodiments, the method further includes: When the time interval is less than the preset coherence time and there is no uplink signal time-frequency domain parameter sequence with the same frame number as the current downlink channel feature frame number, the uplink signal time-frequency domain parameter sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target uplink signal time-frequency domain parameter sequence, wherein the preset frame interval is obtained based on the preset coherence time.

[0226] Based on the above embodiments, the step of calculating the downlink-uplink symbol time difference based on the current downlink channel feature frame number and the frame number of the target uplink signal time-frequency domain parameter sequence includes: Obtain the fifth time slot number and the fifth symbol number, wherein the fifth time slot number represents the time slot number corresponding to the current downlink channel feature frame number; and the fifth symbol number represents the symbol number corresponding to the current downlink channel feature frame number. Obtain the sixth time slot number and the sixth symbol number, wherein the sixth time slot number represents the time slot number corresponding to the frame number of the target uplink signal time-frequency domain parameter sequence; and the sixth symbol number represents the symbol number corresponding to the frame number of the target uplink signal time-frequency domain parameter sequence. Calculate the third frame sequence time difference between the current downlink channel feature frame sequence number and the frame sequence number of the target uplink signal time-frequency domain parameter sequence; Calculate the time difference of the third time slot number between the fifth time slot number and the sixth time slot number; Calculate the third symbol time difference between the fifth symbol number and the sixth symbol number; The downlink and uplink symbol time differences are calculated based on the time difference of the third frame sequence number, the time difference of the third time slot number, and the time difference of the third symbol.

[0227] Based on the above embodiments, determining the reciprocal channel feature sequence as the uplink signal time-frequency domain parameter sequence corresponding to the current target uplink symbol time difference and the current downlink channel feature sequence includes: If the uplink signal time-frequency domain parameter sequence corresponding to the current target uplink symbol time difference is a reciprocal uplink sequence of the previous downlink channel characteristic sequence, the current target uplink symbol time difference is compared with the previous target uplink symbol time difference. If it is determined that the uplink symbol time difference under the current target is less than the uplink symbol time difference under the previous target, the previous downlink channel feature sequence is discarded, and the uplink signal time-frequency domain parameter sequence corresponding to the uplink symbol time difference under the current target and the current downlink channel feature sequence are determined as the reciprocal channel feature sequence. If it is determined that the uplink symbol time difference under the current target is greater than or equal to the uplink symbol time difference under the previous target, the uplink signal time-frequency domain parameter sequence corresponding to the second smallest absolute value downlink symbol time difference and the current downlink channel feature sequence are determined as the reciprocal channel feature sequence.

[0228] Based on the above embodiments, the method further includes: If it is determined that there are multiple uplink signal time-frequency domain parameter sequences corresponding to the uplink symbol time difference under the current target, all of which are reciprocal uplink sequences of the current downlink channel characteristic sequence, then the reciprocal uplink sequence with the maximum resource block length and the current downlink channel characteristic sequence are determined as the reciprocal channel characteristic sequence.

[0229] Based on the above embodiments, the method further includes: In the case of multiple reciprocal uplink sequences with maximum resource block length, the target reciprocal uplink sequence and the current downlink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the target reciprocal uplink sequence represents the reciprocal uplink sequence with a positive uplink-downlink symbol time difference among the multiple reciprocal uplink sequences with maximum resource block length.

[0230] Based on the above embodiments, the method further includes: If the resource block lengths of the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

[0231] It should be noted that, in this invention, the terminal side can also choose to read the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence in frame number order to realize reciprocal channel feature extraction. The extraction process of the reciprocal channel feature sequence based on the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence is similar to the extraction process of the reciprocal channel feature sequence based on the uplink time-frequency domain parameter sequence and the downlink signal feature sequence provided in the above embodiments. Therefore, this invention will not elaborate on the extraction process of the reciprocal channel feature sequence based on the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence.

[0232] The reciprocal channel feature extraction apparatus provided by the present invention is described below. The reciprocal channel feature extraction apparatus described below can be referred to in correspondence with the reciprocal channel feature extraction method described above.

[0233] Figure 7 This is one of the structural schematic diagrams of the reciprocal channel feature extraction device provided by the present invention, such as... Figure 7As shown, this invention provides a reciprocal channel feature extraction device applied to network equipment. The device includes a first extraction module 701, a second extraction module 702, and a first reciprocal channel feature extraction module 703. The first extraction module 701 is used to obtain an uplink channel feature sequence based on a first channel estimation result, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal. The second extraction module 702 is used to obtain a downlink signal time-frequency domain parameter sequence based on first time-frequency domain parameters, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal. The first reciprocal channel feature extraction module 703 is used to perform reciprocal channel feature extraction on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain a reciprocal channel feature sequence. The uplink and downlink symbol time difference is calculated based on the frame sequence number, time slot sequence number, and symbol sequence number.

[0234] The reciprocal channel feature extraction device provided by this invention, with the provision of channel estimation and time-frequency domain parameter information interfaces, extracts the channel features and time-frequency domain parameters of the uplink and downlink shared channel based on the data transmission protocol of the physical uplink and downlink shared channel, thereby realizing non-interactive reciprocal channel feature sequence extraction.

[0235] Figure 8 This is a second schematic diagram of the reciprocal channel feature extraction device provided by the present invention, as shown below. Figure 8 As shown, this invention provides a reciprocal channel feature extraction device applied to a terminal. The device includes a third extraction module 801, a fourth extraction module 802, and a second reciprocal channel feature extraction module 803. The third extraction module 801 is used to obtain a downlink channel feature sequence based on a second channel estimation result, wherein the second channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the downlink signal. The fourth extraction module 802 is used to obtain an uplink signal time-frequency domain parameter sequence based on second time-frequency domain parameters, wherein the second time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the uplink signal. The second reciprocal channel feature extraction module 803 is used to perform reciprocal channel feature extraction on the downlink channel feature sequence and the uplink signal time-frequency domain parameter sequence based on the downlink-uplink symbol time difference to obtain a reciprocal channel feature sequence. The downlink-uplink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

[0236] The reciprocal channel feature extraction device provided by this invention, with the provision of channel estimation and time-frequency domain parameter information interfaces, extracts the channel features and time-frequency domain parameters of the uplink and downlink shared channel based on the data transmission protocol of the physical uplink and downlink shared channel, thereby realizing non-interactive reciprocal channel feature sequence extraction.

[0237] The system provided in this embodiment of the invention is used to execute the above-described method embodiments. For specific processes and details, please refer to the above embodiments, which will not be repeated here.

[0238] Figure 9 This is a schematic diagram of the structure of the electronic device provided by the present invention, such as... Figure 9 As shown, the electronic device may include a processor 901, a communications interface 902, a memory 903, and a communication bus 904. The processor 901, communications interface 902, and memory 903 communicate with each other via the communication bus 904. The processor 901 can call logical instructions in the memory 903 to execute a reciprocal channel feature extraction method.

[0239] Furthermore, the logical instructions in the aforementioned memory 903 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0240] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the reciprocal channel feature extraction method provided by the above methods.

[0241] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the reciprocal channel feature extraction method provided in the above embodiments.

[0242] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0243] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0244] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting features from a reciprocal channel, characterized in that, Applied to network devices, the method includes: Based on the first channel estimation result, an uplink channel feature sequence is obtained, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal; Based on the first time-frequency domain parameters, the downlink signal time-frequency domain parameter sequence is obtained, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal; Based on the uplink and downlink symbol time difference, reciprocal channel features are extracted from the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence to obtain a reciprocal channel feature sequence. The uplink and downlink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

2. The reciprocal channel feature extraction method according to claim 1, characterized in that, The step of obtaining the uplink channel feature sequence based on the first channel estimation result includes: Receive multiple uplink signals; During the decoding process of the physical uplink shared channel, channel estimation is performed on the demodulation reference signals corresponding to multiple uplink signals to obtain multiple first channel estimation results, and the timestamp, frame number, slot number, symbol number and resource block number corresponding to each first channel estimation result are obtained. Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first channel estimation results, the uplink channel feature sequence is obtained.

3. The reciprocal channel feature extraction method according to claim 1, characterized in that, The step of obtaining the downlink signal time-frequency domain parameter sequence based on the first time-frequency domain parameters includes: Send multiple downlink signals; During the coding process of the physical downlink shared channel, the first time-frequency domain parameters of the demodulation reference signals corresponding to the multiple downlink signals are obtained; Based on the timestamp, frame number, slot number, symbol number, and number of resource blocks corresponding to each of the first time-frequency domain parameters, the downlink signal time-frequency domain parameter sequence is obtained.

4. The reciprocal channel feature extraction method according to any one of claims 1 to 3, characterized in that, The reciprocal channel feature extraction is performed on the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain the reciprocal channel feature sequence, including: Read the uplink channel feature sequence based on the frame sequence number, and sequentially obtain the uplink channel feature frame sequence number in the current uplink channel feature sequence; Based on a preset coherence time, at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame sequence is determined from multiple downlink signal time-frequency domain parameter sequences, wherein the preset coherence time is estimated based on the type of the current communication scenario; The uplink and downlink symbol time difference is calculated based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence. The downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel characteristic sequence are determined as the reciprocal channel characteristic sequence, wherein the current target uplink-downlink symbol time difference is the uplink-downlink symbol time difference with the smallest absolute value.

5. The reciprocal channel feature extraction method according to claim 4, characterized in that, The step of determining at least one target downlink signal time-frequency domain parameter sequence corresponding to the current uplink channel feature frame number from multiple downlink signal time-frequency domain parameter sequences based on a preset coherence time includes: Calculate the time interval between the frame number in the downlink signal time-frequency domain parameter sequence and the current uplink channel characteristic frame number; The downlink signal time-frequency domain parameter sequence that has a time interval less than the preset coherence time and whose frame number is the same as the current uplink channel feature frame number is determined as the target downlink signal time-frequency domain parameter sequence.

6. The reciprocal channel feature extraction method according to claim 5, characterized in that, The method further includes: When the time interval is less than the preset coherence time and there is no downlink signal time-frequency domain parameter sequence with the same frame number as the current uplink channel feature frame number, the downlink signal time-frequency domain parameter sequence with the time interval less than the preset coherence time and which satisfies the preset frame interval after the frame interval is increased is determined as the target downlink signal time-frequency domain parameter sequence, wherein the preset frame interval is obtained based on the preset coherence time.

7. The reciprocal channel feature extraction method according to claim 4, characterized in that, The calculation of the uplink / downlink symbol time difference based on the current uplink channel feature frame number and the frame number of the target downlink signal time-frequency domain parameter sequence includes: Obtain the first time slot number and the first symbol number, wherein the first time slot number represents the time slot number corresponding to the current uplink channel feature frame number; and the first symbol number represents the symbol number corresponding to the current uplink channel feature frame number. Obtain the second time slot number and the second symbol number, wherein the second time slot number represents the time slot number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence; and the second symbol number represents the symbol number corresponding to the frame number of the target downlink signal time-frequency domain parameter sequence. Calculate the first frame sequence time difference between the current uplink channel feature frame sequence number and the frame sequence number of the target downlink signal time-frequency domain parameter sequence; Calculate the time difference between the first time slot number and the second time slot number; Calculate the first symbol time difference between the first symbol sequence number and the second symbol sequence number; The uplink and downlink symbol time differences are calculated based on the first frame sequence number time difference, the first time slot number time difference, and the first symbol time difference.

8. The reciprocal channel feature extraction method according to claim 4, characterized in that, The step of determining the reciprocal channel feature sequence as the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference and the current uplink channel feature sequence includes: When the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink-downlink symbol time difference is a reciprocal downlink sequence of the previous uplink channel feature sequence, the current target uplink-downlink symbol time difference is compared with the previous target uplink-downlink symbol time difference. If it is determined that the current target uplink and downlink symbol time difference is less than the previous target uplink and downlink symbol time difference, the previous uplink channel feature sequence is discarded, and the downlink signal time-frequency domain parameter sequence corresponding to the current target uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence. If it is determined that the current target uplink and downlink symbol time difference is greater than or equal to the previous target uplink and downlink symbol time difference, the downlink signal time-frequency domain parameter sequence corresponding to the current second smallest absolute uplink and downlink symbol time difference and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

9. The reciprocal channel feature extraction method according to claim 4, characterized in that, The method further includes: If it is determined that there are multiple downlink signal time-frequency domain parameter sequences corresponding to the current target uplink and downlink symbol time differences, all of which are reciprocal downlink sequences of the current uplink channel feature sequence, then the reciprocal downlink sequence with the maximum resource block length and the current uplink channel feature sequence are determined as the reciprocal channel feature sequence.

10. The reciprocal channel feature extraction method according to claim 4, characterized in that, The method further includes: If the resource block lengths of the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence corresponding to the reciprocal channel feature sequence are inconsistent, the smaller resource block length is used as the reference length to truncate the reciprocal channel feature sequence.

11. A reciprocal channel feature extraction device, characterized in that, Applied to network devices, the device includes: The first extraction module is used to obtain an uplink channel feature sequence based on the first channel estimation result, wherein the first channel estimation result represents the channel estimation result of the demodulation reference signal corresponding to the uplink signal; The second extraction module is used to obtain a sequence of time-frequency domain parameters of the downlink signal based on the first time-frequency domain parameters, wherein the first time-frequency domain parameters represent the time-frequency domain parameters of the demodulation reference signal corresponding to the downlink signal; The first reciprocal channel feature extraction module is used to extract reciprocal channel features from the uplink channel feature sequence and the downlink signal time-frequency domain parameter sequence based on the uplink and downlink symbol time difference to obtain a reciprocal channel feature sequence. The uplink and downlink symbol time difference is calculated based on the frame number, time slot number, and symbol number.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the reciprocal channel feature extraction method as described in any one of claims 1 to 10.

13. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the reciprocal channel feature extraction method as described in any one of claims 1 to 10.

14. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the reciprocal channel feature extraction method as described in any one of claims 1 to 10.

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