Intelligent reflection method for wireless secure access facing multiple two-way eavesdroppers

Abstract

The application provides a smart reflection method for wireless security access of multiple two-way eavesdroppers, comprising the following steps: step 1, establishing a wireless network security access system; step 2, designing an asymmetric two-way smart metasurface reflection beam direction; step 3, detecting channel state information related to the smart metasurface reflection unit; step 4, calculating the null space of the wireless channel; step 5, calculating the beam pointing of the maximum channel gain of the legal wireless communication in the null space; step 6, the access point AP and the legal terminal respectively send data symbols to the smart metasurface reflection unit, and the smart metasurface reflection unit reflects the two-way data symbols reaching at the moment to the access point AP and the legal terminal according to the beam pointing obtained in step 5; and step 7, the access point AP and the legal terminal respectively decode the received data stream as receivers. The application can significantly improve the security performance and data transmission performance of the wireless network security access network.

Description

TECHNICAL FIELD

[0001] The application relates to an intelligent reflection method for wireless secure access of multiple bidirectional eavesdroppers. BACKGROUND

[0002] When the existing wireless network secure access network is used, the network security problem that one illegal station eavesdrops on the downlink and one illegal station eavesdrops on the uplink occurs at the same time, so that an intelligent metasurface reflection beam vector needs to be designed to realize that the reflected downlink data and the reflected uplink data cannot be acquired by the corresponding downlink eavesdropping station and the corresponding uplink eavesdropping station. In order to solve the network security problem of wireless network access, the intelligent metasurface reflection technology has made great progress in recent years. At present, there are three main ways for the network security scene of wireless network secure access: all illegal stations eavesdrop on the downlink data, all illegal stations eavesdrop on the uplink data, and each illegal station eavesdrops on the uplink and downlink data at the same time. However, these methods are very special scenes and cannot solve more general network security access scenes, that is, one illegal station eavesdrops on the uplink data, the illegal station is usually located near the AP and is usually far away from the legal station, and at the same time, one illegal station eavesdrops on the downlink data, the illegal station is usually located near the legal station and is usually far away from the AP.

[0003] The above problems should be considered and solved in the design process of the intelligent metasurface reflection method for the wireless network secure access of the eavesdropping uplink illegal station and the eavesdropping downlink illegal station. SUMMARY

[0004] The purpose of the application is to provide an intelligent metasurface reflection method for wireless network secure access of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations, which can improve the security performance of the wireless network when the illegal eavesdropping uplink data station and the illegal eavesdropping downlink data station eavesdrop on the wireless network at the same time, and further ensure the high efficiency of the security rate of data transmission of the wireless network.

[0005] The technical solution of the application is:

[0006] An intelligent metasurface reflection method for wireless network secure access of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations, comprising the following steps:

[0007] Step 1, establish a wireless network security access system; the wireless network security access system includes an access point AP (Access point, AP), a legal terminal, an illegal station near the access point AP, an illegal station around the legal terminal, an intelligent metasurface reflection unit (two illegal stations, one closer to the AP, and one closer to the legal terminal, an illegal station around the access point AP continuously monitors the signal symbols reflected by the intelligent metasurface unit, and the goal is to eavesdrop on the uplink data stream, because the illegal station is located around the access point AP, it is far away from the legal station, resulting in that the eavesdropping station around the access point AP cannot directly eavesdrop the signal from the legal station, but only eavesdrop the reflected signal from the intelligent metasurface. Similarly, an illegal station near the legal station continuously monitors the signal symbols reflected by the intelligent metasurface, and the goal is to eavesdrop on the downlink data stream, because the illegal station is located near the legal station, it is far away from the access point AP, resulting in that the illegal station near the legal station directly eavesdrops the signal from the access point AP, but only eavesdrops the signal reflected by the intelligent metasurface);

[0008] Step 2, design an asymmetric two-way intelligent metasurface reflection beam direction;

[0009] Step 3, the access point AP and the legal terminal jointly detect the channel state information related to the intelligent metasurface reflection unit, including the wireless channel coefficients of the two link directions between the access point AP and the intelligent metasurface reflection unit, the wireless channel coefficients of the two link directions between the legal terminal and the intelligent metasurface reflection unit, the wireless channel coefficients from the intelligent metasurface reflection unit to the illegal station near the access point AP, the wireless channel coefficients from the intelligent metasurface reflection unit to the illegal station around the legal terminal, the downlink transmit power value of the access point AP, and the uplink transmit power value of the legal terminal;

[0010] Step 4, according to the obtained wireless channel coefficients, calculate the null space of the wireless channel from the intelligent metasurface reflection unit to the illegal station near the access point AP, and the null space of the wireless channel from the intelligent metasurface reflection unit to the illegal station around the legal terminal corresponding to all illegal stations in the two link directions;

[0011] Step 5, according to the obtained wireless channel coefficients, calculate the beam pointing direction with the maximum channel gain in the null space of the legal wireless communication in the two link directions of the access point AP to the intelligent metasurface reflection unit link direction and the legal terminal to the intelligent metasurface reflection unit link direction;

[0012] Step 6, the access point AP and the legitimate terminal each send data symbols to the intelligent metasurface reflecting unit, and the intelligent metasurface reflecting unit reflects the two-way data symbols reaching it according to the beam pointing moment obtained in step 5 to the access point AP and the legitimate terminal;

[0013] Step 7, the access point AP and the legitimate terminal respectively decode the data streams received as receivers.

[0014] In step 1, the access point AP, the intelligent metasurface reflecting unit and the legitimate terminal all adopt full-duplex protocol;

[0015] All the illegal sites are in the eavesdropping state, and all the illegal sites, the legitimate terminal, the access point AP and the intelligent metasurface reflecting unit work at the same frequency;

[0016] The illegal site near the access point AP eavesdrops the information of the uplink;

[0017] The illegal site around the legitimate terminal eavesdrops the information of the downlink.

[0018] Each eavesdropping site intelligently receives the reflected signal from the intelligent metasurface reflecting surface.

[0019] Step 2 includes: for the case that one illegal site eavesdrops the uplink and one illegal site eavesdrops the downlink at the same time, designing the beam pointing of the intelligent metasurface reflection with the maximum data transmission rate of the safe (designing the intelligent metasurface reflection beam in the eavesdropping channel null space to realize safe communication) asymmetric bidirectional wireless link (step 4 is to obtain the eavesdropping channel null space), and the access point AP and the legitimate terminal complete the asymmetric bidirectional cooperative wireless communication based on the current intelligent metasurface reflection beam.

[0020] In step 2, the access point AP and the legitimate terminal send their respective data symbols to the intelligent metasurface reflection unit at the same time, when the two signals reach the intelligent metasurface reflection unit, the intelligent metasurface reflection unit reflects the two mixed data symbol data streams according to the set direction (the beam pointing direction set in step 2), and the reflected two information data streams reach the access point AP (corresponding to the uplink) and the legitimate terminal (corresponding to the downlink) respectively, and the access point AP and the legitimate terminal decode the corresponding data service as receivers. Among them, a non-legitimate station around the access point AP continuously monitors the signal symbols reflected by the intelligent metasurface unit, and the goal is to eavesdrop the uplink data stream. Since the non-legitimate station is located around the access point AP, it is far away from the legitimate station, so the eavesdropping station around the access point AP cannot directly eavesdrop the signal from the legitimate station, but only eavesdrop the reflected signal from the intelligent metasurface. Similarly, a non-legitimate station near the legitimate station continuously monitors the signal symbols reflected by the intelligent metasurface, and the goal is to eavesdrop the downlink data stream. Because the non-legitimate station is located near the legitimate station, it is far away from the access point AP, so the non-legitimate station near the legitimate station directly eavesdrops the signal from the access point AP, but only eavesdrops the signal reflected by the intelligent metasurface.

[0021] Step 4 includes: constructing all interference channel spaces, multiplying the wireless channel coefficient corresponding to each element of the intelligent metasurface reflection surface of the access point AP by the wireless channel coefficient from the corresponding element to the eavesdropping downlink non-legitimate station (located near the legitimate station), each element corresponds to a product result, and all product results form a row vector; the wireless channel coefficient corresponding to each element of the intelligent metasurface reflection surface of the legitimate terminal is multiplied by the wireless channel coefficient from the corresponding element to the eavesdropping uplink non-legitimate station (located near the access point AP), and all product results form a row vector; write the two row vectors as the first two rows of a matrix, and the subsequent other rows are all zeros. The matrix is a square matrix, which completes the construction of the interference channel space; for the eavesdropping channel space, use the singular value decomposition method to obtain the null space of the channel space corresponding to all eavesdropping stations.

[0022] The intelligent metasurface reflection unit includes a communication module, a control module, a calculation module of an eavesdropping channel null space, an asymmetric bidirectional intelligent metasurface reflection beam direction design module, and a data storage module.

[0023] The communication module is used to complete the transmitter signal processing of the access point AP to the downlink data stream, the transmitter signal processing of the legitimate terminal to the uplink data stream, the receiver signal processing of the access point AP to the uplink data stream, and the receiver signal processing of the legitimate terminal to the downlink data stream.

[0024] The control module is used for controlling time synchronization of the whole wireless network security access system, and obtaining corresponding null space according to a calculation result of the eavesdropping channel null space calculation module (the null space is calculated by the eavesdropping channel null space calculation module, and the control module is used for controlling time synchronization of the whole wireless network security access system).

[0025] The asymmetric bidirectional intelligent metasurface reflected beam direction design module is used for designing the intelligent metasurface reflected beam in the null space.

[0026] The data storage module is used for storing the null space result output by the control module, storing the reflected beam result of the asymmetric bidirectional intelligent metasurface reflected beam direction design module, storing the wireless channel coefficients of the access point AP and the intelligent metasurface reflecting unit, storing the wireless channel coefficients between the intelligent metasurface reflecting unit and the legal terminal, storing the wireless channel coefficients from the intelligent metasurface reflecting unit to the eavesdropping uplink illegal station, storing the wireless channel coefficients from the intelligent metasurface reflecting unit to the eavesdropping downlink illegal station, storing the transmission power value of the access point AP, and storing the transmission power value of the legal station.

[0027] Further, the asymmetric bidirectional intelligent metasurface reflected beam direction design module is arranged in the intelligent metasurface reflecting unit or is separately arranged.

[0028] Further, the eavesdropping channel null space calculation module is further used for performing the content of step 4.

[0029] The present application has the advantages that the present application is an intelligent metasurface reflection method for wireless network security access in the presence of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations, constructs the null space of the wireless channel corresponding to all illegal stations, designs the intelligent metasurface reflected beam vector in the null space, and can significantly improve the security performance and data transmission performance of the wireless network security access network. The method can adapt to the intelligent metasurface reflection scene for wireless network security access in the presence of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations, and is suitable for the intelligent metasurface reflection unit scene in which the uplink and the downlink are reflected at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0031] Figure 1 is a schematic diagram of a wireless network security access system in an embodiment of the present application.

[0032] Figure 2It is a description diagram of the intelligent metasurface reflection designer for the security access of the wireless network in the presence of the eavesdropping uplink illegal station and the eavesdropping downlink illegal station in the embodiment.

[0033] Figure 3 It is a flowchart of the intelligent metasurface reflection method for the security access of the wireless network in the presence of the eavesdropping uplink illegal station and the eavesdropping downlink illegal station in the embodiment. DETAILED DESCRIPTION

[0034] The application is applied to a wireless network security access system, which comprises an access station (AP), a legal terminal, an illegal station (eavesdropping uplink data) located near the AP, an illegal station (eavesdropping downlink data) located near the legal terminal, and an intelligent metasurface reflection unit. The AP, the intelligent metasurface reflection unit and the legal terminal all adopt a full-duplex protocol, all the illegal stations are in an eavesdropping state, and all the illegal stations, the legal terminal, the AP and the intelligent metasurface reflection unit work at the same frequency. The asymmetric bidirectional intelligent metasurface reflection beam direction design considers the case that one illegal station eavesdrops the uplink and one illegal station eavesdrops the downlink simultaneously, designs the beam pointing of the intelligent metasurface reflection with the maximum data transmission rate of the safe asymmetric bidirectional wireless link, and the AP and the legal terminal complete the asymmetric bidirectional cooperative wireless communication based on the current intelligent metasurface reflection beam. The AP and the legal terminal simultaneously send respective data symbols to the intelligent metasurface reflection unit, when the two signals reach the intelligent metasurface reflection unit, the intelligent metasurface reflects the mixed data symbol data stream according to the set direction. The reflected two-way information data stream reaches the AP (corresponding to the uplink) and the legal terminal (corresponding to the downlink) respectively, and the AP and the legal terminal decode the corresponding data service as receivers. Among them, an illegal station near the AP continuously monitors the signal symbols reflected by the intelligent metasurface unit, and the target is to eavesdrop the uplink data stream, since the illegal station is located near the AP, it is far away from the legal station, so that the eavesdropping station near the AP cannot directly eavesdrop the signal from the legal station, and only eavesdrops the reflected signal from the intelligent metasurface. Similarly, an illegal station near the legal station continuously monitors the signal symbols reflected by the intelligent metasurface, and the target is to eavesdrop the downlink data stream, since the illegal station is located near the legal station, it is far away from the AP, so that the illegal station near the legal station directly eavesdrops the signal from the AP, and only eavesdrops the reflected signal from the intelligent metasurface. The application can significantly improve the security performance and communication performance of the wireless network access in the presence of illegal eavesdropping terminals in two link directions.

[0035] EMBODIMENT

[0036] An intelligent metasurface reflection method for wireless network security access in the presence of eavesdropping uplink illegal sites and eavesdropping downlink illegal sites simultaneously, such as Figure 1 and Figure 3 , applied to a wireless network security access system, the wireless network security access system includes an access point (AP), a legal terminal, an illegal site near the AP (eavesdropping uplink information), an illegal site near the legal terminal (eavesdropping downlink information), and an intelligent metasurface reflection unit. The AP, the intelligent metasurface reflection unit, and the legal terminal all use full-duplex protocol, all illegal sites are in eavesdropping state, and all illegal sites, the legal terminal, the AP, and the intelligent metasurface reflection unit work at the same frequency. The asymmetric bidirectional intelligent metasurface reflection beam direction design will consider the case of eavesdropping uplink by one illegal site and eavesdropping downlink by one illegal site simultaneously, design the beam pointing of the intelligent metasurface reflection with the maximum data transmission rate of the safe asymmetric bidirectional wireless link, and the AP and the legal terminal complete the asymmetric bidirectional cooperative wireless communication based on the current intelligent metasurface reflection beam. The AP and the legal terminal send their respective data symbols to the intelligent metasurface reflection unit at the same time, when the two signals reach the intelligent metasurface reflection unit, the intelligent metasurface reflects the mixed data symbol data stream according to the set direction. The reflected two-way information data stream reaches the AP (corresponding to the uplink) and the legal terminal (corresponding to the downlink) respectively, and the AP and the legal terminal decode the corresponding data service as receivers. Among them, an illegal site near the AP continuously monitors the signal symbols reflected by the intelligent metasurface unit, aiming to eavesdrop the uplink data stream, since the illegal site is located near the AP, it is far away from the legal site, resulting in that the eavesdropping site near the AP cannot directly eavesdrop the signal from the legal site, but only eavesdrop the reflected signal from the intelligent metasurface. Similarly, an illegal site near the legal site continuously monitors the signal symbols reflected by the intelligent metasurface, aiming to eavesdrop the downlink data stream, since the illegal site is located near the legal site, it is far away from the AP, resulting in that the illegal site near the legal site directly eavesdrops the signal from the AP, but only eavesdrops the signal reflected by the intelligent metasurface. The present application can significantly improve the security performance and communication performance of wireless network access in the presence of illegal eavesdropping terminals in two link directions.

[0037] The intelligent metasurface reflection method for wireless network security access facing the coexistence of eavesdropping uplink illegal sites and eavesdropping downlink illegal sites can construct the null space of the wireless channel corresponding to all illegal sites, and design the reflection beam vector of the intelligent metasurface in the null space, which can significantly improve the network security performance and data transmission performance of the wireless network security access network. The method can adapt to the intelligent metasurface reflection scene facing the coexistence of eavesdropping uplink illegal sites and eavesdropping downlink illegal sites for wireless network security access, and is suitable for the intelligent metasurface reflection unit scene of simultaneous reflection of uplink and downlink.

[0038] The intelligent metasurface reflection method for wireless network security access facing the coexistence of eavesdropping uplink illegal sites and eavesdropping downlink illegal sites can construct the null space of the wireless channel corresponding to all illegal sites, and design the reflection beam vector of the intelligent metasurface in the null space, which can significantly improve the network security performance and data transmission performance of the wireless network security access network. The method can adapt to the intelligent metasurface reflection scene facing the coexistence of eavesdropping uplink illegal sites and eavesdropping downlink illegal sites for wireless network security access, and is suitable for the intelligent metasurface reflection unit scene of simultaneous reflection of uplink and downlink. Figure 3 , comprising the following steps,

[0039] Step 1, the access point (AP) and the legal terminal jointly detect the channel state information related to the intelligent metasurface reflection unit, including the wireless channel coefficients of the two link directions between the AP and the intelligent metasurface reflection unit, the wireless channel coefficients of the two link directions between the legal terminal and the intelligent metasurface reflection unit, the wireless channel coefficients from the intelligent metasurface reflection unit to the illegal site near the AP, the wireless channel coefficients from the intelligent metasurface reflection unit to the illegal site near the legal terminal, the downlink transmission power value of the AP, and the uplink transmission power value of the legal terminal;

[0040] Step 2, according to the obtained wireless channel coefficients, the null space of the wireless channel corresponding to all illegal sites in the two link directions is calculated;

[0041] Step 3, according to the obtained wireless channel coefficients, the beam pointing with the maximum channel gain of the legal wireless communication in the above null space in the two link directions is calculated;

[0042] Step 4, the AP and the legal terminal respectively send data symbols to the intelligent metasurface reflection unit, and the intelligent metasurface reflection unit reflects the two arriving data symbols to the AP and the legal terminal according to the designed beam pointing;

[0043] Step 5, the AP and the legal terminal as receivers respectively decode the received data stream.

[0044] In the embodiment, when the intelligent metasurface reflection unit faces the coexistence of one eavesdropping uplink illegal site and one eavesdropping downlink illegal site, the reflection beam direction is designed, and the reflection beam pointing is designed in the null space of the wireless channel corresponding to all illegal sites. The method can improve the network security performance and data transmission performance of the wireless network security access network, and ensure safe wireless access.

[0045] As Figure 2The application discloses an intelligent metasurface reflection method for wireless network security access of an eavesdropping uplink illegal site and an eavesdropping downlink illegal site, and the intelligent metasurface reflection unit comprises a communication module, a control module, an eavesdropping channel null space calculation module and an asymmetric bidirectional intelligent metasurface reflection beam direction design module,

[0046] The communication module is used for completing transmitter signal processing of the AP on a downlink data stream, transmitter signal processing of a legal terminal on an uplink data stream, receiver signal processing of the AP on the uplink data stream and receiver signal processing of the legal terminal on the downlink data stream.

[0047] The control module is used for controlling time synchronization of the whole wireless network security access system, and obtaining a corresponding null space according to a calculation result of the eavesdropping channel null space calculation module.

[0048] The asymmetric bidirectional intelligent metasurface reflection beam direction design module is used for designing an intelligent metasurface reflection beam in the null space in the control module.

[0049] The data storage module is used for storing a null space result output by the control module, storing a reflection beam result of the asymmetric bidirectional intelligent metasurface reflection beam direction design module, storing wireless channel coefficients of the AP and the intelligent metasurface reflection unit, storing wireless channel coefficients between the intelligent metasurface reflection unit and the legal terminal, storing wireless channel coefficients from the intelligent metasurface reflection unit to the eavesdropping uplink illegal site, storing wireless channel coefficients from the intelligent metasurface reflection unit to the eavesdropping downlink illegal site, storing a transmitter power value of the AP and storing a transmitter power value of the legal site.

[0050] Figure 2 The asymmetric bidirectional intelligent metasurface reflection beam direction designer is an illustrative diagram, and a centralized controller is adopted, the controller needs to acquire all related parameters, including wireless channel coefficients and transmitter power values, and then designs an intelligent metasurface reflection beam direction, the asymmetric bidirectional intelligent metasurface reflection beam direction designer can be placed in the legal terminal, can be placed in the access site or can be separately arranged, for example, Figure 1 .

[0051] The intelligent metasurface reflection method for secure access of a wireless network in the presence of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations has the following advantages: firstly, the wireless access capabilities of the eavesdropping uplink illegal stations and the eavesdropping downlink illegal stations are considered simultaneously in the design process of the reflection beam direction of the intelligent metasurface, that is, the eavesdropping uplink illegal stations do not simultaneously eavesdrop on the downlink, and the eavesdropping downlink illegal stations do not simultaneously eavesdrop on the uplink, and the corresponding null space is calculated in the wireless channel space corresponding to all illegal stations, so that the wireless information emitted by the reflection beam cannot reach all illegal stations; and secondly, the design target of the reflection beam is to maximize the matching of the wireless channels of the two link directions of the legal stations in the channel null space of the illegal stations. The mechanisms of the two aspects ensure that the network security performance of the intelligent metasurface reflection method for secure access of a wireless network in the presence of eavesdropping uplink illegal stations and eavesdropping downlink illegal stations reaches the best performance.

[0052] In specific implementations, the present application provides a computer storage medium and a corresponding data processing unit, wherein the computer storage medium can store a computer program, and the computer program can run the invention content and part or all steps in each embodiment of the intelligent reflection method for secure access of a wireless network in the presence of multiple bidirectional eavesdroppers when executed by the data processing unit. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), or the like.

[0053] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present application can be realized by means of a computer program and its corresponding general hardware platform. Based on such understanding, the technical solutions in the embodiments of the present application can be embodied in the form of a computer program, i.e., a software product, which can be stored in a storage medium and includes a plurality of instructions for causing an equipment (which can be a personal computer, a server, a single-chip microcomputer, a MUU, or a network device, etc.) containing a data processing unit to execute the method described in each embodiment or some parts of the embodiments of the present application.

[0054] The present application provides an intelligent reflection method for secure access of a wireless network in the presence of multiple bidirectional eavesdroppers. There are many methods and ways to implement this technical solution, and the above description is only the preferred embodiment of the present application. It should be noted that, for ordinary skilled persons in the technical field, without departing from the principles of the present application, several improvements and refinements can be made, which should also be considered as the protection scope of the present application. The components not explicitly described in the embodiments can be implemented using existing technology.

Claims

1. A smart reflecting method for wireless secure access against multiple bidirectional eavesdroppers, characterized in that, The method comprises the following steps: Step 1, establishing a wireless network security access system, the wireless network security access system comprising an access point AP, a legitimate terminal, an illegal station located near the access point AP, an illegal station located around the legitimate terminal, and an intelligent metasurface reflecting unit; Step 2, designing an asymmetric two-way intelligent metasurface reflecting beam direction; Step 2 comprises: for the case that eavesdropping of uplink by an illegal station and eavesdropping of downlink by an illegal station occur simultaneously, designing a beam direction of the intelligent metasurface reflection with the maximum data transmission rate of the secure asymmetric two-way wireless link, and the access point AP and the legitimate terminal completing asymmetric two-way cooperative wireless communication based on the current intelligent metasurface reflecting beam; Step 3, the access point AP and the legitimate terminal jointly detecting channel state information related to the intelligent metasurface reflecting unit, including wireless channel coefficients of two link directions between the access point AP and the intelligent metasurface reflecting unit, wireless channel coefficients of two link directions between the legitimate terminal and the intelligent metasurface reflecting unit, wireless channel coefficients of the intelligent metasurface reflecting unit to the illegal station near the access point AP, wireless channel coefficients of the intelligent metasurface reflecting unit to the illegal station around the legitimate terminal, a downlink transmission power value of the access point AP, and an uplink transmission power value of the legitimate terminal; Step 4, calculating zero spaces of wireless channels of all illegal stations corresponding to the wireless channels of the two link directions of the intelligent metasurface reflecting unit to the illegal station near the access point AP and the intelligent metasurface reflecting unit to the illegal station around the legitimate terminal according to the obtained wireless channel coefficients; Step 5, calculating a beam direction with the maximum channel gain in the zero space for the legitimate wireless communication of the two link directions of the access point AP to the intelligent metasurface reflecting unit and the legitimate terminal to the intelligent metasurface reflecting unit according to the obtained wireless channel coefficients; Step 6, the access point AP and the legitimate terminal respectively sending data symbols to the intelligent metasurface reflecting unit, and the intelligent metasurface reflecting unit reflecting the two arriving data symbols to the access point AP and the legitimate terminal according to the beam direction obtained in step 5; Step 7, the access point AP and the legitimate terminal respectively decoding the received data streams as receivers.

2. The method of claim 1, wherein, In step 1, the access point AP, the intelligent metasurface reflecting unit, and the legitimate terminal all adopt a full-duplex protocol; All illegal stations are in an eavesdropping state, and all illegal stations, the legitimate terminal, the access point AP, and the intelligent metasurface reflecting unit work at the same frequency; The illegal station located near the access point AP eavesdrops on the uplink information; The illegal station located around the legitimate terminal eavesdrops on the downlink information; Each eavesdropping station intelligently receives a reflected signal from the intelligent metasurface reflecting metasurface.

3. The method of claim 2, wherein, In step 2, the access point AP and the legitimate terminal send their respective data symbols to the intelligent metasurface reflection unit at the same time, and when the two signals reach the intelligent metasurface reflection unit, the intelligent metasurface reflection unit reflects the mixed data symbol data stream according to the set direction, and the reflected two information data streams reach the access point AP and the legitimate terminal respectively, and the access point AP and the legitimate terminal decode the corresponding data service as receivers.

4. The method of claim 3, wherein, Step 4 includes: constructing all interference channel spaces, multiplying the wireless channel coefficients corresponding to each element of the access point AP to the reflection surface of the intelligent metasurface by the wireless channel coefficients of the corresponding element to the eavesdropping downlink of the illegal site, each element corresponds to a product result, and all product results form a row vector; the wireless channel coefficients corresponding to each element of the legitimate terminal to the reflection surface of the intelligent metasurface are multiplied by the elements to the eavesdropping uplink of the illegal site, and all product results form a row vector; write the two row vectors as the first two rows of a matrix, and the subsequent other rows are all zeros, the matrix is a square matrix, and the construction of the interference channel space is completed; for the eavesdropping channel space, the singular value decomposition method is used to obtain the null space of the channel space corresponding to all eavesdropping sites.

5. The method of claim 4, wherein, The intelligent metasurface reflection unit includes a communication module, a control module, an eavesdropping channel null space calculation module, an asymmetric bidirectional intelligent metasurface reflection beam direction design module, and a data storage module. The communication module is used to complete the transmitter signal processing of the access point AP to the downlink data stream, the transmitter signal processing of the legitimate terminal to the uplink data stream, the receiver signal processing of the access point AP to the uplink data stream, and the receiver signal processing of the legitimate terminal to the downlink data stream.

6. The method of claim 5, wherein, The control module is used to control the time synchronization of the entire wireless network security access system, and obtain the corresponding null space according to the calculation result of the eavesdropping channel null space calculation module.

7. The method of claim 6, wherein, The asymmetric bidirectional intelligent metasurface reflection beam direction design module is used to design the intelligent metasurface reflection beam in the null space.

8. The method of claim 7, wherein, The data storage module is used to store the null space result output by the control module, store the reflection beam result of the asymmetric bidirectional intelligent metasurface reflection beam direction design module, store the wireless channel coefficients of the access point AP and the intelligent metasurface reflection unit, store the wireless channel coefficients between the intelligent metasurface reflection unit and the legitimate terminal, store the wireless channel coefficients of the intelligent metasurface reflection unit to the eavesdropping uplink illegal site, store the wireless channel coefficients of the intelligent metasurface reflection unit to the eavesdropping downlink illegal site, store the transmission power value of the access point AP, and store the transmission power value of the legitimate site.

9. The method of claim 8, wherein, The eavesdropping channel null space calculation module is also used to execute the content of step 4.

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