Large-array intelligent metasurface codebook optimizing and switching method and device

Abstract

The invention provides a large-array intelligent metasurface codebook optimization and switching method and device, and belongs to the technical field of wireless communication. Aiming at the problem of low efficiency of a traditional codebook selection method in a high-speed moving scene of a user, the invention provides an intelligent optimization method and device, which can efficiently position optimal codebook configuration in a codebook library through a quick search mechanism. According to the method, in combination with signal-to-noise ratio feedback driving, multiple groups of configurations in a codebook library are tested step by step, and a gain optimization module is combined, so that the optimal beam forming effect is achieved, and the method does not need to depend on accurate position information of a user. Besides, a clockwise adjacent codebook test strategy is introduced, the redundancy calculation and traversal time is shortened, and it is ensured that in the user moving process, codebooks can be rapidly switched, and stable communication quality is kept. The algorithm has the advantages of real-time response and complexity reduction, is suitable for 5G and other high-speed mobile communication scenes, and effectively improves the signal transmission efficiency and the communication reliability.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a codebook optimization method and a codebook switching method and device for a large array intelligent metasurface. Background Art

[0002] 5G physical layer technologies are generally able to adapt to spatially and temporally varying wireless environments, but signal propagation is inherently random and largely uncontrollable.

[0003] For the reasons mentioned above, intelligent metasurfaces (IRS) are considered a promising new technology to reconfigure wireless propagation environments through software-controlled reflections. Specifically, IRS are planes composed of a large number of low-cost passive reflective elements, each of which is able to independently induce amplitude and / or phase changes in the incident signal, thereby collaboratively achieving fine three-dimensional (3D) reflection beamforming. In stark contrast to existing transmitter / receiver wireless link adaptation techniques, IRS actively modifies the wireless channel between them by adjusting the surface diode voltage.

[0004] The voltage control range of the control end can be determined based on the IRS characteristics, but the user moves at a high speed, so it is necessary to more intelligently control the multi-bit voltage change and find the optimal codebook more quickly. In this regard, I studied a large array intelligent metasurface codebook optimization and switching method and device. Summary of the invention

[0005] In wireless communication systems assisted by large arrays of intelligent metasurfaces, beamforming technology is the key to achieving efficient signal transmission. However, since the intelligent metasurface controls the direction of the reflected beam by adjusting the phase of the reflective unit, different metasurface configurations correspond to different beam effects. The system needs to select the best configuration from multiple feasible configurations (codebooks) to enhance signal strength and communication quality. Traditional codebook selection methods usually take a long time to perform global search, especially when the number of codebooks is large, the search efficiency is greatly reduced, and it cannot meet the needs of fast and accurate configuration in actual networks.

[0006] In order to meet the above challenges, the present invention proposes a codebook optimization method and device based on a large array of intelligent metasurfaces, which can quickly find a configuration that matches a fixed angle and has the best gain in multiple codebooks. Specifically, the present invention is implemented by the following steps:

[0007] Generate codebook library: First, based on the structural characteristics of large array smart metasurfaces, an existing algorithm is used to generate a codebook library containing 60 sets of codebooks for smart metasurfaces. Each set of codebooks represents a specific beamforming configuration, covering different phase adjustments and direction settings, ensuring that the codebook library can cover different transmission requirements and angles.

[0008] Codebook optimization method: A specially designed codebook optimization method is used in the generated 60 codebook libraries. This method combines the feedback information of the network environment with the optimization model, and can quickly locate the codebook that matches the target angle. On this basis, the codebook with the best gain effect is selected through gain evaluation. This method can effectively reduce redundant calculations, improve optimization efficiency, and ensure that the best codebook is selected in a short time.

[0009] Optimal codebook selection for fixed angles: When the user moves or the environment changes, the phase setting of the smart metasurface is adjusted to ensure that the beam is always aimed at the target user. For each fixed angle, the above optimization method is used to quickly locate the best configuration in the codebook library to ensure the best signal gain effect in different locations and environments.

[0010] In a wireless communication system assisted by a large array of intelligent metasurfaces, when a user moves, in order to maintain signal quality and ensure the continuity and smoothness of communication, it is necessary to switch the codebook of the intelligent metasurface in real time according to the change of the user's position, thereby adjusting the angle of beamforming. However, when the user moves faster, since the codebook library contains a large number of codebooks, using a traversal method to try to switch the codebooks one by one will result in a high algorithm complexity, affecting the response speed and system performance. Therefore, a method that can quickly switch codebooks is needed to meet the real-time communication needs when the user moves.

[0011] In order to overcome the above challenges, the present invention proposes a fast codebook switching method and device based on a large-array intelligent metasurface, which can quickly select and switch to the optimal codebook configuration from the codebook library according to the signal information fed back during the user's movement, ensuring that good communication quality can be maintained when the user moves.

[0012] The key innovation of this method is that it does not need to obtain the precise positioning information of the terminal, and can achieve the optimal codebook switching by relying only on the signal-to-noise ratio (SNR) information fed back by the USRP receiver.

[0013] Working principle of the method: Codebook selection driven by signal-to-noise ratio feedback: The method proposed in the present invention dynamically adjusts the beamforming of the smart metasurface by monitoring the real-time signal-to-noise ratio information fed back by the USRP receiver. Whenever the signal-to-noise ratio changes significantly, the method automatically determines whether the codebook needs to be switched to optimize the beam direction and gain effect.

[0014] Fast codebook switching mechanism: Different from the traditional traversal search method, this method constructs a fast search mechanism to efficiently locate the codebook that best matches the current channel conditions in a codebook library containing 60 codebooks.

[0015] This mechanism uses intelligent methods to jointly optimize gain and beam direction, reducing redundant calculations and unnecessary search steps, and can quickly complete codebook switching when two users move at fast speeds.

[0016] No positioning dependency: The method does not need to rely on the precise location information of the user equipment, and only needs to adjust the codebook according to the SNR change of the received signal.

[0017] By analyzing the SNR change trend in real time, the change in the current user's relative position can be inferred, so as to select the appropriate beam direction and gain configuration. This method greatly simplifies the complexity of the system, avoids dependence on the positioning system, and improves the practicality and applicability of the method.

[0018] Optimization of intelligent metasurface configuration information: In addition to selecting the appropriate beamforming direction through SNR feedback, the method also uses a further gain optimization module to ensure that the selected codebook can not only align with the user's moving direction, but also provide the best signal enhancement effect in the current environment. By combining beamforming and gain optimization, the system can maintain efficient and stable communication in complex wireless environments.

[0019] The composition of the large array intelligent metasurface codebook optimization and switching device includes: codebook generation and library construction module, control end regulation module, signal-to-noise ratio measurement and feedback module, signal-to-noise ratio driven codebook selection module, fast codebook switching module, network side equipment, large array intelligent metasurface equipment, control equipment and terminal. The device can dynamically adjust the codebook according to different scenarios. For example, in different communication environments such as indoors, outdoors, cities, and rural areas, the device can select the optimal codebook configuration through real-time analysis of feedback information. This multi-scenario adaptive capability ensures that the system can provide efficient communication services in various complex environments.

[0020] Beneficial Effects

[0021] From the above, it can be seen that the large-array intelligent metasurface codebook optimization switching method and device provided by the present invention improves the codebook selection efficiency, reduces unnecessary calculations and redundant steps, significantly improves the efficiency of codebook selection, and shortens the response time. This method can not only quickly determine the optimal beam direction, but also combine the gain optimization module to ensure that the selected codebook can provide the optimal signal enhancement effect in the current environment, thereby improving the quality and reliability of communication. This device innovatively divides the processes of constructing a codebook library, controlling codebook switching, feedback on codebook control effects, optimizing the codebook library, and switching the optimal codebook into five main modules, and designs the above process as an integral device, ensuring that the device can provide efficient codebook optimization and switching services in various complex environments.

[0022] The present invention is particularly suitable for scenarios where users move at high speed, reducing the risk of communication interruption caused by changes in user positions. The method does not require obtaining precise positioning information of users, reduces system complexity, simplifies the actual deployment process, and improves the applicability of the system, especially in scenarios where precise positioning cannot be obtained in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of a large array intelligent metasurface codebook optimization method of the present invention;

[0024] Figure 2 It is a flow chart for implementing a large array intelligent metasurface codebook switching method of the present invention;

[0025] Figure 3 This is a schematic diagram of the control end connecting to FPGA and DAC to achieve the control of the intelligent metasurface;

[0026] Figure 4 It is a flow chart of a large array intelligent metasurface codebook optimization and switching device of the present invention; DETAILED DESCRIPTION

[0027] The present invention proposes a codebook optimization and fast switching method and device based on large-array intelligent metasurface (IRS) technology. The method quickly searches for the optimal codebook in the codebook library, thereby dynamically adjusting the beamforming during the user's movement to ensure the stability and quality of signal transmission. The device includes a codebook generation and library construction module, a control end regulation module, a signal-to-noise ratio measurement and feedback module, a signal-to-noise ratio driven codebook selection module, and a fast codebook switching module. Through the division of labor of these modules, the system can achieve fast optimization and switching of the codebook, adapt to the user's mobile scenario, and ensure the efficiency and stability of communication.

[0028] Figure 1 The flowchart of a large array intelligent metasurface codebook optimization method of the present invention includes:

[0029] Step 101: Generate a codebook library and import it into the control end. First, the system uses an existing generation algorithm to generate a codebook library of 60 groups of codebooks. Each group of codebooks contains different phase modulation combinations, representing different smart metasurface configurations. The purpose of generating this codebook library is to ensure that the smart metasurface can achieve different beamforming at multiple angles to adapt to different user locations and channel conditions.

[0030] The generated 60 sets of codebook libraries are imported into the control end of the smart metasurface through the data interface. The control end can process the codebook through hardware devices such as FPGA (field programmable gate array) and DAC (digital-to-analog converter), and use the codebook library as a list of available configurations for the smart metasurface to prepare for subsequent beamforming adjustment operations.

[0031] The large array intelligent metasurface (3-bit state) has 8 voltage control states, each of which corresponds to a different electromagnetic wave phase deflection, and the maximum phase change can be about 350°. In the design, these 8 voltage control states are assigned digital codes, namely 0, 1, 2, 3, 4, 5, 6 and 7. In the FPGA program, these 8 voltage values ​​are mapped to the above digital codes.

[0032] According to the relative angle of the two users to the IRS (intelligent metasurface), 60 control codebooks are generated and stored in the codebook library, and each codebook corresponds to 60 columns of voltage states of the IRS. The control end stores the codebook library containing 60 codebooks in a txt file as the input control codebook library.

[0033] Step 102: Input the codebook into the IRS board for switching operation. Under the synergy of the built-in FPGA and DAC of the control end, the system inputs 60 codebooks into the IRS board one by one at a certain time interval (such as 0.5 seconds).

[0034] The control end inputs the codebook serially into the FPGA, and the FPGA controls the DCA to output 60 columns of voltage values ​​in parallel, thereby completing the configuration and regulation of the large-array intelligent metasurface.

[0035] As the core component of the intelligent metasurface system, the IRS board can adjust the phase of the reflection unit according to different codebook configurations so that the reflected signal beam is directed in different directions to cover the target area or track moving users.

[0036] The time interval for each codebook switching is designed to be 0.5 seconds in order to complete the testing of all codebooks in a short time and ensure that the system can respond quickly to changes in channel conditions.

[0037] Through this batch codebook switching mechanism, the system can complete the testing of all codebooks in a shorter time to ensure that the optimal configuration is found.

[0038] Step 103: The signal-to-noise ratio is fed back to the control terminal. Figure 3 , the signal power P output by USRP at the transmitting end TX =10dBm, carrier frequency f c =5.8GHz, signal bandwidth BW = 16MHz, transmission gain G TX =10dB, modulation mode M mod =16QAM.

[0039] The USRP device can set the transmit power by configuring the power control parameters, and can also change the modulation mode according to the quality of the channel. The commonly used modulation modes in the measurement and debugging process are: M mod =8PSK, and Mmod =16QAM.

[0040] When each codebook is applied to the smart metasurface, the USRP (Universal Software Radio Peripheral) device measures the received signal quality. The signal power P at the USRP input at the receiving end RX =-113dBm, carrier frequency f c =5.8GHz, signal bandwidth BW = 16MHz, receiving gain G RX =20dB, where the signal-to-noise ratio calculated by the system is SNR=23.60dB.

[0041] Signal-to-noise ratio is an important indicator to measure communication quality. It reflects the strength ratio of the signal to the noise. A higher signal-to-noise ratio means better communication quality.

[0042] The device on the USRP side will record the current signal-to-noise ratio after each codebook switch and transmit the signal-to-noise ratio information back to the control side through the UDP protocol (User Datagram Protocol). The UDP protocol is a lightweight transmission protocol that can achieve fast data transmission and is suitable for real-time communication scenarios.

[0043] In this way, the control end can obtain the signal-to-noise ratio data corresponding to each codebook in real time, providing a basis for subsequent optimal codebook selection.

[0044] Step 104: Calculate and output the best codebook. After receiving the signal-to-noise ratio data sent back by the USRP, the control end matches and records each set of codebooks with the corresponding signal-to-noise ratio information.

[0045] Next, the control end will sort these data and select the codebook according to the signal-to-noise ratio. The system will select the codebook with the highest signal-to-noise ratio as the optimal codebook in the current environment.

[0046] This optimal codebook will be used in subsequent beamforming operations to ensure that the smart metasurface can provide users with the best signal gain and communication quality under current channel conditions.

[0047] This process achieves the selection of the optimal codebook through real-time signal-to-noise ratio feedback without relying on user positioning information, thereby improving the response speed and adaptability of the system.

[0048] After each codebook switch, the measured SNR values ​​are SNR1, SNR2, …SNR n (where n is the total number of codebooks, such as 60 codebooks in this embodiment.) The goal of the system is to select the codebook that maximizes the SNR value by comparing all SNR values, that is:

[0049] SNR optimal=max(SNR1,SNR2,…,SNR n )

[0050] Optimal Codebook C optimal The selection rules are:

[0051] C optimal =C i where i = argmax(SNR i )

[0052] Where i is the corresponding codebook index, and the codebook with the highest SNR value is found. This optimal codebook corresponds to the best beamforming and signal gain that the smart metasurface can provide under the current channel conditions.

[0053] According to communication theory, the higher the signal-to-noise ratio, the better the communication quality of the system and the lower the bit error rate (BER). The specific relationship between the bit error rate and SNR can be approximately expressed by the following formula:

[0054] For the common QPSK (quadrature phase shift keying) modulation method, the bit error rate formula is:

[0055]

[0056] For 16QAM (16-order quadrature amplitude modulation) modulation, the bit error rate formula is:

[0057]

[0058] Where Q(x) is the Q function, which represents the right tail probability of the Gaussian distribution:

[0059]

[0060] By comparing the SNR values ​​under different codebook configurations, the system can not only select the optimal codebook to improve the signal-to-noise ratio, but also reduce the bit error rate under specific modulation methods, thereby significantly improving communication reliability and data transmission rate.

[0061] Figure 2 The present invention is a flowchart of a large array intelligent metasurface codebook switching method, comprising:

[0062] Step 201: Codebook library construction and matrix arrangement. In the intelligent metasurface (IRS) assisted wireless communication system, the adjustment of beamforming depends on different codebook configurations. For the control range of plus or minus 60°, with each 5° as a control unit, there are 276 codebooks, each corresponding to a different metasurface angle configuration.

[0063] In order to facilitate the optimization for two users, firstly, the codebooks need to be written into the preferred codebook library according to the different positions (angles) of the two users.

[0064] Specific steps: The optimization method generates a codebook library, which contains 276 codebooks. Each codebook is arranged according to the corresponding angle of user 1 and user 2.

[0065] According to the pre-calculated beam direction or angle, the optimal codebook is placed in the library and forms a matrix library in a certain order, represented as C, where each element C i,j represents the codebook configuration for user 1 and user 2 at positions i and j.

[0066] The resulting matrix can be expressed as:

[0067]

[0068] Where m represents the possible angle or position of user 1, and n represents the possible angle or position of user 2.

[0069] Step 202: Codebook input and selection. Next, the optimal codebook library is imported into the control end, and the random codebook switching mechanism is enabled by the control end. At the control end, the system will randomly select a codebook from the matrix according to actual needs, and input the codebook information into the large array intelligent metasurface so that the metasurface can adjust the transmission direction of the signal through beamforming.

[0070] The control end randomly selects a codebook from the matrix library each time, denoted as C i,j , where i and j correspond to the positions of user 1 and user 2 in the matrix respectively.

[0071] This codebook is then sent to the IRS board, and beamforming is adjusted according to the codebook to optimize the reflection direction and gain of signal transmission.

[0072] Step 203: Signal-to-noise ratio measurement and feedback. After each codebook switch, the USRP device measures the signal-to-noise ratio information of the metasurface reflection signal in real time and feeds back the measured signal-to-noise ratio to the control end through the UDP protocol.

[0073] The measured signal-to-noise ratios of user 1 and user 2 are set to SNR1 and SNR2 respectively. After the control end receives the feedback signal from the USRP, it will record the signal-to-noise ratio information corresponding to each codebook to facilitate subsequent comparison and selection.

[0074] Step 204: SNR comparison and optimal codebook selection. After obtaining the SNR information under multiple codebooks, the control end needs to quickly select the optimal codebook from the codebooks near the current user's location. In order to speed up this process, the present invention adopts a method of testing the SNR of the codebooks around the current location one by one in a clockwise order. This method can ensure that when the user moves, the system can quickly find the optimal codebook, thereby ensuring the communication quality.

[0075] Specific steps: Preliminary selection of the current codebook position. Assume that the current positions of user 1 and user 2 are the i-th row and j-th column in the matrix, that is, the currently used codebook is C i,j At this time, the control end will make a preliminary judgment based on the measured signal-to-noise ratios SNR1(i, j) and SNR2(i, j). If the signal-to-noise ratio meets the minimum requirements of the system, the current codebook will be maintained to continue communication.

[0076] If the signal-to-noise ratio does not meet expectations, the system will initiate further codebook optimization process.

[0077] Test the surrounding codebooks clockwise. In order to quickly obtain the optimal codebook configuration, the system will start from the current codebook C i,j The signal-to-noise ratio test is performed on the surrounding codebooks. The specific operation is to start from the first codebook on the left of the current position, test the adjacent codebooks in a clockwise order, and record their corresponding signal-to-noise ratios.

[0078] The clockwise test order of the adjacent codebook is:

[0079] Codebook C on the left i,j-1 ;

[0080] Codebook C in the upper left corner i-1,j-1 ;

[0081] The codebook C above i-1,j ;

[0082] Codebook C in the upper right corner i-1,j+1 ;

[0083] Codebook C on the right i,j+1 ;

[0084] Codebook C in the lower right corner i+1,j+1 ;

[0085] The codebook C below i+1,j ;

[0086] Codebook C in the lower left corner i+1,j-1 .

[0087] Each selected codebook will be subject to signal-to-noise ratio measurement and feedback. The specific process is as follows: The control end selects each surrounding codebook in turn, such as C i,j-1, and measure the signal-to-noise ratios of user 1 and user 2 under this codebook based on the information fed back by the USRP device, which are recorded as SNR1(i,j-1) and SNR2(i,j-1) respectively.

[0088] The system will record the SNR and of the codebook and continue to select the next adjacent codebook, such as C i-1,j-1 , repeat the same measurement and recording process.

[0089] Find the codebook with the maximum signal-to-noise ratio. After a round of clockwise testing, the control end will compare the signal-to-noise ratios of all tested codebooks. Specifically, the system will calculate the sum of the signal-to-noise ratios of each codebook at the positions of user 1 and user 2, using the following formula:

[0090] SNR total =SNR1+SNR2

[0091] The system will find the SNR total The largest codebook, denoted by C optimal ,Right now:

[0092]

[0093] Where (i', j') is the current codebook C i,j Codebook collection for surrounding tests.

[0094] Further iterative optimization. If the current round of clockwise testing fails to find the optimal codebook that meets the conditions, the system will continue to find the maximum signal-to-noise ratio and codebook C optimal The codebook is tested again clockwise around until a codebook that satisfies the communication quality is found.

[0095] In each iteration, the system selects a new central codebook and repeats the above clockwise test process. This localized optimization strategy greatly reduces the amount of calculation required to traverse the codebook, ensuring that the system can find the optimal codebook in the shortest time.

[0096] Advantages of this method: Compared with traversing all codebooks globally, this method of testing clockwise around the current codebook greatly reduces the number of tests and can quickly find the optimal codebook near the user's current location. This not only improves the efficiency of codebook switching, but also ensures a smooth transition of communication quality when the user moves quickly.

[0097] Real-time dynamic switching: This method does not need to obtain the user's specific location information, but adjusts it through the signal-to-noise ratio information fed back by the USRP device in real time. This means that the system can dynamically adjust the configuration of the smart metasurface during the user's movement, thereby always maintaining the best signal transmission effect.

[0098] When the user moves, the control end will dynamically switch the codebook according to the real-time signal-to-noise ratio fed back by the USRP. The USRP end will feed back the SNR information of user 1 and user 2 to the control end, and the control end will perform codebook switching control.

[0099] Each time the user moves, a search is performed in the codebook matrix based on the user's current location, and the codebook with the highest signal-to-noise ratio is selected.

[0100] Figure 4 The present invention is a flow chart of a large array intelligent metasurface codebook optimization and switching device, including:

[0101] Module 1001: Codebook generation and library construction module: Responsible for generating and storing codebook libraries for large array smart metasurfaces. Based on the system structure, 60 or more codebooks are generated, each representing a different beamforming configuration. Key steps: Generate codebooks based on the structural characteristics of the IRS; import the codebook library into the control end as input for subsequent beamforming; ensure that the codebook library covers different phase adjustments and direction settings.

[0102] Module 1002: Control end control module: Implement the application of codebooks on the smart metasurface based on FPGA and DAC. By processing each codebook, the voltage and phase configuration of the smart metasurface are regulated. Key steps: The control end accesses FPGA and DAC to process the codebook; the codebook is input into the IRS board in parallel, and beamforming is achieved through voltage adjustment; the control end is responsible for switching the codebook and controlling the application time of each codebook.

[0103] Module 1003: Signal-to-noise ratio measurement and feedback module: The USRP receiver measures the received signal strength, especially the signal-to-noise ratio (SNR), after each codebook switch, and feeds it back to the control end. Key steps: After each codebook switch, the USRP device measures the signal-to-noise ratio of the received signal; the signal-to-noise ratio data is transmitted back to the control end via the UDP protocol.

[0104] Module 1004: SNR-driven codebook selection module: Determine the optimal codebook in the current environment through the feedback of SNR information to ensure the optimal beamforming. This module optimizes the codebook selection in combination with gain evaluation. Key steps: Collect the SNR information after each codebook application; select the codebook with the best gain effect according to the SNR; dynamically adjust the beamforming of the smart metasurface.

[0105] Module 1005: Fast codebook switching module: When the user moves at high speed, a fast search mechanism is constructed to quickly switch to the optimal codebook configuration to ensure the continuity and stability of communication. Key steps: Use the feedback SNR information to determine whether the codebook needs to be switched; use the fast search mechanism to quickly locate the optimal codebook in 60 sets of codebooks; the system uses a localized clockwise search strategy to reduce the amount of calculation for traversing the codebook.

Claims

1. A large array intelligent metasurface codebook optimization and switching method and device, characterized in that: Importing a codebook library containing multiple groups of codebooks, each group of codebooks is configured based on different columns of a large array of smart metasurfaces, and is used to control the voltage state of a reflection unit of the large array of smart metasurfaces to adjust the direction of a reflected beam; The imported codebooks are input into the intelligent metasurface in groups at fixed time intervals through the FPGA and DAC hardware devices on the control side to test the beamforming effect of each group of codebooks. Based on the signal-to-noise ratio (SNR) feedback of the received signals of the two user devices, the control end evaluates the beamforming effect of each set of codebooks and records the optimal codebook into the codebook library to optimize the beamforming; The optimized codebook is used to generate the codebook matrix according to different angles of the two users: Where m represents the possible angle or position of user 1, n represents the possible angle or position of user 2, and each element C in the matrix i,j represents the codebook configuration for user 1 and user 2 at positions i and j; When the position of the user equipment changes, by real-time monitoring of the SNR of the user end, the control end selects the adjacent codebooks in the codebook matrix clockwise and calculates the signal-to-noise ratio and SNR of each codebook at the positions of user 1 and user 2: total =SNR1+SNR2, the system is selected so that SNR total The largest codebook C i,j As the current optimal codebook.

2. The method according to claim 1, characterized in that The codebook selection mechanism driven by signal-to-noise ratio feedback does not require the precise location information of the user device. It only relies on the signal-to-noise ratio value fed back by the receiving USRP device, which is transmitted back to the control end through the UDP protocol. The beam direction and gain configuration of the smart metasurface are dynamically adjusted according to the SNR changes.

3. The method according to claim 1, characterized in that The fast codebook switching mechanism reduces the computational complexity of global codebook traversal by constructing a fast search algorithm. It adopts a clockwise search strategy for the surrounding codebooks of the current codebook in the local area of ​​the codebook matrix and selects the optimal codebook based on the following formula: Where (i', j') is the current codebook C i,j Codebook collection for surrounding tests.

4. The method according to claim 1, characterized in that The generation of each set of codebooks in the codebook library to be tested is based on the phase adjustment capability of the intelligent metasurface. The codebook library covering different beamforming configurations is generated based on the eight voltage control states of the IRS system (corresponding to eight discrete states of phase deflection from 0° to 350°).

5. The method according to claim 1, characterized in that The configuration of the codebook library can support mobile scenarios of multiple users. The codebook matrix is ​​represented as a two-dimensional matrix, where rows represent different angular positions of user 1, columns represent different angular positions of user 2, and each matrix element represents the optimal codebook for user 1 and user 2 at the corresponding angle.

6. The method according to claim 1, characterized in that The signal quality evaluation of the signal-to-noise ratio feedback is to sort the SNR values ​​under each codebook received by the control end, select the codebook with the highest signal-to-noise ratio, and use the bit error rate formula: Evaluate the quality of communications.

7. The method according to claim 1, characterized in that The intelligent metasurface adjusts the voltage state of the reflection unit in real time through the control end, so that the reflected beam is always facing the direction of the target user, and automatically adjusts the codebook based on SNR feedback to optimize communication quality and signal gain to adapt to the user's high-speed mobile scenario.

8. The method according to claim 1, characterized in that This method can be used in complex wireless environments. The control end selects the appropriate beamforming direction through real-time SNR feedback and combines it with the gain optimization module to ensure that the reflected beam after codebook switching can provide the best signal enhancement effect and maintain the stability of system communication.

9. A large array intelligent metasurface codebook optimization and switching device according to claim 1, characterized in that: It includes: codebook generation and library construction module, control end regulation module, signal-to-noise ratio measurement and feedback module, signal-to-noise ratio driven codebook selection module, fast codebook switching module, network side equipment, large array intelligent metasurface equipment, control equipment and terminal.

10. A large array intelligent metasurface codebook optimization and switching device as claimed in claim 9, characterized in that: The codebook generation and library construction module is used to generate and store a codebook library for a large array of smart metasurfaces, and based on the system structure, a certain number of codebooks are generated, each codebook represents a different beamforming configuration; Control end control module: used to realize the control of the codebook on the smart metasurface. Through the control end, the FPGA and DAC are connected, and each codebook is input into the IRS board in parallel. The beamforming is realized by adjusting the voltage corresponding to the codebook, and the voltage and phase configuration of the smart metasurface are controlled. Signal-to-noise ratio measurement and feedback module: used to measure the received signal strength after each codebook switch. After each codebook switch, the USRP receiver measures the signal strength parameters, especially the signal-to-noise ratio, and feeds it back to the control end through the UDP protocol; SNR-driven codebook selection module: used to determine the optimal codebook in the current environment. It selects the optimal codebook for beamforming based on the feedback of SNR information. This module optimizes the codebook based on gain evaluation and generates an optimized codebook matrix. Fast codebook switching module: It is used to build a fast search mechanism and use a localized clockwise search strategy to reduce the amount of codebook traversal calculations when the user moves at high speed, quickly switch to the optimal codebook configuration, and ensure the continuity and stability of communication; The network side device comprises a transceiver antenna, a USRP, a memory, a processor, and a computer program stored in the memory and executable on the processor; when the processor executes the program, the steps of the codebook optimization and switching method described in any one of claims 1 to 8 are implemented; Large array intelligent metasurface equipment: including intelligent metasurfaces containing a large number of reflection units and power supply; Control device: includes FPGA, DAC, memory, processor, and computer program stored in the memory and executable on the processor.

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