Wireless secure communication method based on camouflage activation mechanism and index direction modulation

Abstract

This invention relates to the field of wireless communication technology, specifically to a secure wireless communication method based on a spoofing activation mechanism and index direction modulation, comprising the following steps: S1, system configuration; S2, receiver group allocation: based on the receiver group selection bits of the current time slot and the state of the active receiver group of the previous time slot, the active receiver group of the current time slot is determined according to a preset dynamic switching rule; S3, bit segment selection; S4, modulation symbols; S5, directional transmission: the transmitter constructs a precoding matrix based on the channel vector of the legitimate receiver, preprocesses the index direction modulation symbols through the precoding matrix to obtain the transmitted signal, and wirelessly transmits the transmitted signal through a directional beam generated by the precoding matrix. The directional beam forms spatial nulls in the direction of the inactive receiver and the eavesdropping end; S6, information bit stream recovery. This invention, by designing a special bit-to-symbol mapping rule, enables the legitimate receiver to correctly recover the true index.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically to a secure wireless communication method based on spoofing activation mechanism and index direction modulation. Background Technology

[0002] With the continuous evolution of fifth-generation mobile communication (5G) and future next-generation wireless communication technologies, the demand for high speed, large-scale user access, and ultra-low latency in communication systems is becoming increasingly urgent. However, the open wireless channel environment is highly vulnerable to security threats such as eavesdropping. Therefore, how to achieve secure transmission at the physical layer has become a key research focus for both academia and industry.

[0003] The core idea of ​​physical layer security technology is to build a security protection system by utilizing the inherent characteristics of wireless channels. Relying on the spatiotemporal uniqueness and non-replicability of wireless channel parameters, it blocks the decoding path of eavesdroppers at the signal transmission level. Directional modulation (DM) technology, through the beam design of the antenna array, can ensure correct demodulation of the signal in the desired direction at the legitimate receiver, while disrupting constellation mapping and introducing interference in the undesired direction, thus achieving secure transmission. However, this technology has a significant limitation: if the eavesdropper is in the same or similar direction of incoming wave as the legitimate receiver, the security protection capability of DM will be greatly reduced or even completely ineffective. To solve this problem, existing technologies combine DM with index modulation (IM) to form indexed DM technology. This technology uses receiver indices and constellation symbols to jointly carry information, thereby achieving secure transmission of wireless signals and improving system security performance to a certain extent. However, when the eavesdropper has similar or even better system resources than the legitimate receiver, is in a similar direction of arrival, and has cluster reception capabilities, the security of existing index direction modulation technology is still seriously inadequate. The eavesdropper can use high-performance receiver arrays and optimal detection algorithms to correctly demodulate the receiver index and constellation symbols, causing the system's security protection mechanism to fail.

[0004] Therefore, current technology lacks a wireless transmission system that can balance transmission rate and security performance even when the eavesdropping party also has cluster reception capabilities. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a wireless secure communication method based on a spoofing activation mechanism and index direction modulation (DRA). By designing a special bit-to-symbol mapping rule, the legitimate receiver can correctly recover the true index, while the eavesdropper, lacking the DRA rule, cannot correctly decode it.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a wireless secure communication method based on spoofing activation mechanism and index direction modulation, comprising the following steps: S1, System Configuration: Secure wireless signal transmission is achieved based on index direction modulation technology. A wireless communication system is configured, which has a built-in transmitter, a legitimate receiver, and an eavesdropping terminal. The transmitter obtains the channel information of the legitimate receiver and shares the security state set, state transition table, and receiver domain generation rules with the legitimate receiver in advance. S2, Bit Hierarchy: This involves dividing the input information bits of each time slot into state transition bits. Intra-domain index bits and constellation symbols Bit Among them, the state transition bits are used to select the transition edge of the safe state, the domain index bits are used to select the active receiving unit in the candidate receiving domain, and the constellation symbol bits are used to determine the M-ary amplitude-phase modulation symbol. S3, Receive domain reconstruction: Based on the security status of the previous time slot, the state transition bits of the current time slot, and the frame-level perturbation parameters, the transmitter determines the current security status through the state transition table and generates the current candidate receive domain according to the receive domain generation rules. S4, Activation Index Determination: Based on the index bits within the domain, the transmitter selects a legitimate receiving unit in the current candidate receiving domain as the active receiving unit for the current time slot, and decouples the physical index of the active receiving unit from the current security state; S5, Index Beam Symbol Generation: The transmitter selects an M-ary amplitude-phase modulation symbol according to the constellation symbol bits, and loads the amplitude-phase modulation symbol into the index position corresponding to the active receiving unit to form an index beam modulation symbol; S6, Directional precoding transmission: The transmitter constructs a precoding matrix that satisfies the power focusing and sidelobe suppression conditions based on the channel information of the legitimate receiving unit. After preprocessing the index beam modulation symbol, it transmits it wirelessly so that the direction of the active receiving unit can obtain effective receiving power and the interference in the direction of the non-active legitimate receiving unit is kept below a preset threshold. S7, State-assisted recovery: The legitimate receiver performs joint detection on the received signal to obtain the estimated values ​​of the active receiver unit index and the M-ary amplitude-phase modulation symbol; the legitimate receiver combines the security state of the previous time slot, the currently detected receiver domain, and the shared state transition table to deduce the state transition bit, and then merges it with the domain index bit and constellation symbol bit to recover the complete information bit stream.

[0007] Furthermore, in S1, the set of security states contains no less than two security states; each security state corresponds to at least one candidate reception domain, which is determined by the reception domain generation rule, rather than fixing all legitimate reception units equally into two receiver groups; the reception domain generation rule takes the physical index of the reception unit as input and permutes or reorganizes the set of legitimate reception units to generate candidate reception domains that vary with frames or time slots, making it difficult for unlicensed receivers to deduce the real information bit mapping relationship from the observed physical active reception unit index.

[0008] Furthermore, in S2, the state transition table is a reversible mapping table; given the previous time slot security state and frame-level perturbation parameters, different state transition bits correspond to different next security states, enabling the legitimate receiver to uniquely deduce the state transition bits from the current security state.

[0009] Furthermore, in S3, when selecting an active receiver from the active receiver group based on the receiver selection bit within the group, the binary value of the receiver selection bit within the group is mapped to the valid receiver with the corresponding sequence number within the active receiver group, which serves as the unique active receiver for the current time slot.

[0010] Furthermore, in S4, the M-ary amplitude-phase modulation adopts the quadrature phase-shift keying (QPSK) modulation method. Based on the binary value of the constellation symbol bits, it is mapped to the corresponding amplitude-phase modulation symbol in the QPSK constellation diagram. Combined with the position index of the activated receiver and the modulation symbol, the index direction modulation symbol is generated.

[0011] Furthermore, in S5, when the transmitter constructs the precoding matrix based on the channel vector of the legitimate receiver, the column vectors of the precoding matrix correspond one-to-one with the channel vectors of each legitimate receiver. Only the column vector of the precoding matrix corresponding to the active receiver in the current time slot has a non-zero value, while the other column vectors are all zero values, so that the preprocessed transmitted signal forms a power-focused directional beam only in the direction of the active receiver.

[0012] Furthermore, in S5, the transmitter is configured with a uniform linear antenna array. Based on the carrier wavelength and the element spacing of the antenna array, and combined with the incoming wave direction of several different legitimate receivers, a free space channel vector corresponding to each legitimate receiver is constructed for the design of the precoding matrix.

[0013] Furthermore, in S6, the legitimate receiver employs the maximum likelihood detection algorithm, based on the minimum Euclidean distance criterion, to jointly detect the received signal, and simultaneously completes the identification and demodulation of the active receiver index and the M-ary amplitude-phase modulation symbol.

[0014] Furthermore, in S6, when demodulating the state transition bits, the central processing unit reconstructs the candidate receiving domains corresponding to each security state of the current time slot based on the currently detected physical active receiving unit index, combined with the security state of the previous time slot and the candidate receiving domain generation rules; in the candidate receiving domains, it determines the current security state and its index within the domain that match the current physical active receiving unit index, and according to the preset state transition rules or state inverse mapping table, it demaps the transition relationship from the security state of the previous time slot to the security state of the current time slot into state transition bits.

[0015] Furthermore, the legitimate receiving end includes several distributed receiving units, which are distributed in different spatial locations or different receiving directions and are connected to the same central processing unit through optical fiber links. The central processing unit determines the security state, candidate receiving domain, and intra-domain index corresponding to the current time slot based on the detected physical active receiving unit index and amplitude-phase modulation symbol, combined with the historical security state and candidate receiving domain generation rules. It then recovers the state transition bits, intra-domain index bits, and constellation symbol bits according to the preset state inverse mapping rules, thereby reconstructing the complete information bit stream.

[0016] The above approach has the following beneficial effects: 1. This scheme, by introducing a security state set, candidate reception domain generation rules, and a state transition mapping mechanism, hides the real active receiver unit index within the dynamically changing security state and candidate reception domain, thus eliminating the fixed one-to-one correspondence between the physical active index and the real information bits. The legitimate receiver unit set is permuted or reorganized to generate candidate reception domains that change with time slots. Therefore, even if an unauthorized receiver possesses similar spatial observation capabilities, distributed reception capabilities, or strong joint detection capabilities as a legitimate receiver, it is difficult to deduce the mapping relationship between the current security state, candidate reception domain, intra-domain index, and real information bits solely from the observed physical active receiver unit index. This ultimately results in the demodulation bit error rate of the index information consistently remaining around 0.5, thereby improving the physical layer security performance of the index direction modulation system in clustered passive eavesdropping scenarios.

[0017] 2. This scheme, while maintaining the index-direction modulation transmission structure, divides the input information bits into state transition bits, intra-domain index bits, and constellation symbol bits. It also uses dynamic candidate receive domains to carry index information, enhancing the concealment of the index bits without altering the amplitude-phase modulation symbol transmission method. Legitimate receivers pre-synchronize and share the seed, state transition rules, candidate receive domain generation rules, and state inverse mapping rules. Therefore, after completing the joint detection of the physical activation receiver unit index and amplitude-phase modulation symbols, it can recover the current security state, candidate receive domains, and intra-domain indexes by combining the frame sequence number and historical security states, and further demap to obtain the state transition bits, intra-domain index bits, and constellation symbol bits. Compared to traditional index-direction modulation schemes that solely rely on fixed receiver index mapping, this scheme can increase the mapping identification difficulty for unlicensed receivers while maintaining index carrying capacity and constellation symbol carrying capacity, thus achieving a better balance between transmission efficiency, legitimate reception reliability, and physical layer security.

[0018] 3. This solution does not require additional RF hardware links or the introduction of highly complex encryption algorithms and signal processing procedures. It can be implemented simply by modifying the baseband symbol mapping logic at the software level. The engineering implementation is simple, the hardware modification cost is low, and it has strong industrialization and large-scale deployment value. It can seamlessly adapt to the core application requirements of 5G and future next-generation wireless communication systems for high-speed, high-security, and low-complexity transmission. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the method steps in an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention; Figure 2 This is a schematic diagram of a wireless communication system model according to an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention; Figure 3 This is a schematic diagram of the wireless communication system flow of an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention; Figure 4 This is a schematic diagram of receiver index selection in an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention; Figure 5 This is a schematic diagram of the detection algorithm for the legitimate receiver in an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention; Figure 6This is a schematic diagram showing the total BER variation curves of the legitimate party and the eavesdropping party in the traditional IDM and DRA-IDM methods when the eavesdropping party knows the user's location and different signal-to-noise ratios are set, according to an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention. Figure 7 This is a schematic diagram showing the receiver index BER variation curves of the legitimate party and the eavesdropping party in the traditional IDM and DRA-IDM methods when the eavesdropping party knows the user's location and different signal-to-noise ratios are set. This is an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention. Figure 8 This is a schematic diagram showing the constellation symbol BER variation curves of the legitimate party and the eavesdropping party in the traditional IDM and DRA-IDM methods when the eavesdropping party knows the user's location and different signal-to-noise ratios are set. This is an embodiment of the wireless secure communication method based on spoofing activation mechanism and index direction modulation of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] The following detailed description illustrates the specific implementation method: Example: As attached Figure 1As shown: A wireless secure communication method based on masquerade activation mechanism and index direction modulation includes the following steps: S1, System Configuration: Secure wireless signal transmission is achieved based on indexed direction modulation technology. A wireless communication system is configured, which includes a transmitter, a legitimate receiver, and an eavesdropping terminal. The transmitter acquires the channel information of the legitimate receivers and shares a set of secure states, a state transition table, and a receiver domain generation rule with the legitimate receivers in advance. The set of secure states contains at least two secure states. Each secure state corresponds to at least one candidate receiver domain, which is determined by the receiver domain generation rule, rather than fixing all legitimate receivers into two receiver groups. The receiver domain generation rule takes the physical index of the receiver as input and permutes or reorganizes the set of legitimate receivers to generate candidate receiver domains that vary with frames or time slots, making it difficult for unauthorized receivers to deduce the true information bit mapping relationship from the observed physical active receiver index.

[0024] S2, Bit Hierarchy: This involves dividing the input information bits of each time slot into state transition bits. Intra-domain index bits and constellation symbols Bit The state transition bits are used to select the transition edge of the security state, the domain index bits are used to select the active receiving unit in the candidate receiving domain, and the constellation symbol bits are used to determine the M-ary amplitude-phase modulation symbol. The state transition table is a reversible mapping table. Given the security state of the previous time slot and the frame-level perturbation parameters, different state transition bits correspond to different next security states, so that the legitimate receiver can uniquely deduce the state transition bits from the current security state.

[0025] S3, Receiver domain reconstruction: Based on the security status of the previous time slot, the state transition bits of the current time slot, and the frame-level perturbation parameters, the transmitter determines the current security status through the state transition table and generates the current candidate receiver domain according to the receiver domain generation rules; when selecting an active receiver from the active receiver group based on the receiver selection bits within the group, the binary value of the receiver selection bits within the group is mapped to the valid receiver with the corresponding sequence number within the active receiver group, which serves as the unique active receiver for the current time slot.

[0026] S4, Modulation Symbol: Activation Index Determination: Based on the index bits within the domain, the transmitter selects a valid receiving unit in the current candidate receiving domain as the active receiving unit for the current time slot, and decouples the physical index of the active receiving unit from the current security state; M-ary amplitude-phase modulation adopts quadrature phase-shift keying (QPSK) modulation, which maps the binary values ​​of the constellation symbol bits to the corresponding amplitude-phase modulation symbols in the QPSK constellation diagram, and generates index direction modulation symbols by combining the position index of the active receiver with the modulation symbols.

[0027] S5, Directional Transmission: Index Beam Symbol Generation: The transmitter selects an M-ary amplitude-phase modulation symbol based on the constellation symbol bits and loads the amplitude-phase modulation symbol into the index position corresponding to the active receiver unit to form an index beam modulation symbol; when the transmitter constructs the precoding matrix based on the channel vector of the legitimate receiver, the column vectors of the precoding matrix correspond one-to-one with the channel vectors of each legitimate receiver. Only the column vector of the precoding matrix corresponding to the active receiver in the current time slot has a non-zero value, and the other column vectors are all zero values, so that the preprocessed transmitted signal forms a power-focused directional beam only in the direction of the active receiver; the transmitter is configured with a uniform linear antenna array, and based on the carrier wavelength and the element spacing of the antenna array, combined with the incoming wave direction of several different legitimate receivers, constructs the free space channel vector corresponding to each legitimate receiver for the design of the precoding matrix.

[0028] S6, Directional Precoding Transmission: The transmitter constructs a precoding matrix that satisfies power focusing and sidelobe suppression conditions based on the channel information of the legitimate receiver unit. After preprocessing the index beam modulation symbol, it transmits wirelessly to ensure that the direction of the active receiver unit obtains effective received power and keeps the interference in the direction of the non-active legitimate receiver unit below a preset threshold. The legitimate receiver uses the maximum likelihood detection algorithm based on the minimum Euclidean distance criterion to jointly detect the received signal and simultaneously complete the identification and demodulation of the active receiver index and the M-ary amplitude-phase modulation symbol. When demodulating the state transition bits, the central processing unit reconstructs the candidate receiver domains corresponding to each security state of the current time slot based on the currently detected physical active receiver unit index, combined with the security state of the previous time slot and the candidate receiver domain generation rules. In the candidate receiver domains, the current security state and its index within the domain that match the current physical active receiver unit index are determined. Based on the preset state transition rules or state inverse mapping table, the transition relationship from the security state of the previous time slot to the security state of the current time slot is demapped into state transition bits.

[0029] S7, State-assisted recovery: The legitimate receiver performs joint detection on the received signal to obtain the estimated values ​​of the active receiver unit index and the M-ary amplitude-phase modulation symbol; the legitimate receiver combines the security state of the previous time slot, the currently detected receiver domain, and the shared state transition table to deduce the state transition bit, and then merges it with the domain index bit and constellation symbol bit to recover the complete information bit stream.

[0030] The legitimate receiving end includes several distributed receiving units, which are located in different spatial locations or different receiving directions and are connected to the same central processing unit through optical fiber links. The central processing unit determines the security state, candidate receiving domain, and intra-domain index corresponding to the current time slot based on the detected physical active receiving unit index and amplitude-phase modulation symbols, combined with the historical security state and candidate receiving domain generation rules. It then recovers the state transition bits, intra-domain index bits, and constellation symbol bits according to the preset state inverse mapping rules, thereby reconstructing the complete information bit stream.

[0031] The specific implementation process is as follows: Wireless communication system model diagram as shown below. Figure 2 As shown, the transmitter (Alice) is equipped with The antenna, the legitimate (Bob) receiver is equipped with... The root of the distributed single antenna, and , Only one of the antennas The root antenna is activated, and the eavesdropper (Eve) is configured with... Bob employs a distributed single-antenna receiver architecture. To ensure spatial multiplexing, Bob's receivers are distributed in different directions, and these receivers also possess joint detection capabilities. When the digital signal is transmitted from the receiver to Bob's central processing unit via an optical fiber link, this unit can perform various signal processing tasks, including signal detection and decoding. This technology uses QPSK modulation, which not only has high spectral efficiency and strong anti-interference capabilities but is also relatively simple to implement in circuits. Furthermore, based on the concept of directional modulation, the transmitter projects the modulated signal onto all receivers, where Bob receives the correct constellation signal, while Eve receives a scrambled constellation signal. Figure 3 A system flowchart of the method of the present invention is shown.

[0032] In the DRA-IDM system, Alice configures a uniform linear array to generate a directional beam pointing towards Bob; therefore, the free-space channel vector is: (1) (2) in, The wavelength is and the antenna spacing is .

[0033] From a bitstream perspective, the input bitstream is divided into The index of the legitimate receiver is divided into three parts, namely, and , and . (1) front Bits are used to select the receiver group: if Then the first The receiver group index of the bit remains the same as the previous one. Otherwise, the receiver group index will be different. According to this special mapping rule, assuming the bit is... The receiver group selected on bit is ,Right now Then the first The receive group index on the bit can be obtained according to the following formula: (3) Also in In this case, It can be obtained using the following formula: (4) (2) Bits determine receiver selection within a group: Based on the determination of the receiver group, the following is used... Bits from receiver group Select a receiver index Therefore, the index of the receiver activated in DRA-IDM is different from the index generated by a traditional IDM. Unlike other methods, the actual index information is hidden during the switching of the receiver group. Since the eavesdropper is unaware of the hidden information mechanism, the eavesdropper cannot correctly demodulate the sender's information.

[0034] (3) Bit determines the constellation symbol: the last Bits are transmitted using conventional amplitude-phase modulation.

[0035] The DRA-IDM symbol vector can be represented as: (5) Alice's transmitted signal vector is: (6) Based on the characteristics of index modulation and directional modulation, the precoding matrix is ​​designed as follows: (7) Among them, the precoding matrix The column vector It can be represented as: (8) Then, Transmitted to the legitimate party via directional beamforming, in the DRA-IDM system, the selection of the active receiver is determined jointly by the previous and current time slots. The specific activation rules are as follows: Figure 4As shown. Assume the first valid receiver to activate in the previous time slot is the one that does so. If the active legitimate receiver in the current time slot is the same as the one in the previous time slot, then the active legitimate receiver switches to the second legitimate receiver. Based on this special mapping rule, the DRA-IDM scheme successfully disguises itself as a traditional IDM scheme, but the bit information is exactly the opposite of the traditional IDM scheme. Therefore, the eavesdropper will incorrectly decode the received information, thus improving transmission security.

[0036] The received signal vector at the valid end can be represented as: (9) (10) in, For Bob's direction, This is the channel vector between Alice and Bob. It is Gaussian white noise and .

[0037] For ease of explanation, symbols are used. Replace the symbol Based on formula (9), the maximum likelihood joint detection mathematical expression for the legitimate receiver is obtained, which simultaneously detects the active receiver index. and modulation symbols The expression is (11) in, This represents the set of receiver indices for Bob. The constellation symbol representing M-QAM.

[0038] In determining the active receiver index Subsequently, the legitimate receiving unit was identified as... (12) The input bits are determined by comparing the current group index with the previous receiver group index. (13) also, An active receiver index can be given by the following formula. (14) in, The remainder after b is divided by a. The flowchart of the valid square detection algorithm, which represents the demapping to the receiver's index bits, is as follows: Figure 5 As shown.

[0039] The received signal vector of the eavesdropping party can be represented as: (15) Assuming the eavesdropper successfully intercepts the transmitted signal, the mathematical expression for the maximum likelihood detection of the transmitted signal by the eavesdropper is: (16) However, since the eavesdropping party is unaware of the confidential information mapping scheme, therefore and Demapping directly from the received bits leads to suboptimal decoding performance. However, the proposed DRA-IDM scheme, with its unique bit-to-symbol mapping mechanism, can hide the true bit information, preventing eavesdroppers from decoding it without reducing the transmission rate, thus creating a promising secure transmission technology.

[0040] This example uses QPSK modulation, and the simulation parameters are set as follows: number of transmitter antennas. Number of valid receiver antennas Number of antennas at the eavesdropping receiver legitimate receiving end direction eavesdropping receiver direction Antenna spacing The carrier frequency was 1 GHz, and the number of simulations was 9e5.

[0041] The performance of this scheme was verified through MATLAB simulation, and the results are as follows: Figure 6 The overall bit error rate (BER) curves for the legitimate party and the eavesdropping party are shown for the DRA-IDM scheme and the traditional IDM scheme when there are 4 receive antennas. The legitimate party achieves similar bit error rate performance to the traditional IDM scheme in the DRA-IDM scheme; for the eavesdropping party, the DRA-IDM scheme performs worse than the traditional IDM scheme. More specifically, compared to the traditional IDM scheme, the eavesdropping party's bit error rate is significantly lower in the DRA-IDM scheme. There is approximately a 6dB performance loss, which is due to the introduction of the DRA mechanism. The current bit demapping is associated with the receiver group activated in the previous time slot. The average bit error rate of the DRA-IDM scheme needs to take into account both the previous time slot and the currently active receiver group. Therefore, as can be seen from the figure, the bit error rate of the eavesdropper is almost always around 0.5, which means that it is very difficult for the eavesdropper to correctly decode information from the DRA-IDM scheme. Figure 7The receiver index BER curves for the legitimate party and the eavesdropping party in the DRA-IDM scheme and the traditional IDM scheme with 4 receiving antennas are shown. From the perspective of the legitimate party, the DRA-IDM scheme achieves almost the same receiver index BER performance as the traditional IDM scheme. From the perspective of the eavesdropping party, the receiver index BER of the DRA-IDM scheme remains almost at 0.5, while in the traditional IDM scheme, the receiver index BER performance improves significantly with the increase of signal-to-noise ratio. This means that the eavesdropping party has a chance to correctly detect the receiver index information. Therefore, it can be verified that the DRA-IDM scheme hides the active receiver index, which can effectively prevent passive eavesdropping during information transmission.

[0042] Figure 8 The diagram illustrates the constellation symbol BER curves for the legitimate party and the eavesdropping party in a DRA-IDM scheme and a traditional IDM scheme with four receiving antennas. From the perspective of the legitimate party, the constellation BER performance of the DRA-IDM scheme is the same as that of the traditional IDM scheme. This is because the confidential information mapping mechanism hides the active receiver index, which has no impact on the demodulation of the constellation symbols. From the perspective of the eavesdropping party, since the constellation symbols transmitted by the transmitter to the legitimate receiver are not disguised, the constellation BER performance of the DRA-IDM scheme is also the same as that of the traditional IDM scheme, further demonstrating the importance of introducing the DRA mechanism in secure transmission.

[0043] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A wireless secure communication method based on masquerading activation mechanism and index direction modulation, characterized in that, Includes the following steps: S1, System Configuration: Secure wireless signal transmission is achieved based on index direction modulation technology. A wireless communication system is configured, which has a built-in transmitter, a legitimate receiver, and an eavesdropping terminal. The transmitter obtains the channel information of the legitimate receiver and shares the security state set, state transition table, and receiver domain generation rules with the legitimate receiver in advance. S2, Bit Hierarchy: This involves dividing the input information bits of each time slot into state transition bits. Intra-domain index bits and constellation symbols Bit Among them, the state transition bits are used to select the transition edge of the safe state, the domain index bits are used to select the active receiving unit in the candidate receiving domain, and the constellation symbol bits are used to determine the M-ary amplitude-phase modulation symbol. S3, Receive domain reconstruction: Based on the security status of the previous time slot, the state transition bits of the current time slot, and the frame-level perturbation parameters, the transmitter determines the current security status through the state transition table and generates the current candidate receive domain according to the receive domain generation rules. S4, Activation Index Determination: Based on the index bits within the domain, the transmitter selects a legitimate receiving unit in the current candidate receiving domain as the active receiving unit for the current time slot, and decouples the physical index of the active receiving unit from the current security state; S5, Index Beam Symbol Generation: The transmitter selects an M-ary amplitude-phase modulation symbol according to the constellation symbol bits, and loads the amplitude-phase modulation symbol into the index position corresponding to the active receiving unit to form an index beam modulation symbol; S6, Directional precoding transmission: The transmitter constructs a precoding matrix that satisfies the power focusing and sidelobe suppression conditions based on the channel information of the legitimate receiving unit. After preprocessing the index beam modulation symbol, it transmits it wirelessly so that the direction of the active receiving unit can obtain effective receiving power and the interference in the direction of the non-active legitimate receiving unit is kept below a preset threshold. S7, State-assisted recovery: The legitimate receiver performs joint detection on the received signal to obtain the active receiver unit index and the estimated value of the M-ary amplitude-phase modulation symbol; The legitimate receiver combines the security status of the previous time slot, the currently detected receiving domain, and the shared state transition table to deduce the state transition bits, and then merges them with the domain index bits and constellation symbol bits to restore the complete information bit stream.

2. The wireless secure communication method based on masquerade activation mechanism and index direction modulation according to claim 1, characterized in that, In S1, the set of security states contains no less than two security states; each security state corresponds to at least one candidate reception domain, which is determined by the reception domain generation rule, rather than fixing all legal reception units equally into two receiver groups; the reception domain generation rule takes the physical index of the reception unit as input and permutes or reorganizes the set of legal reception units to generate candidate reception domains that vary with frames or time slots, making it difficult for unlicensed receivers to deduce the real information bit mapping relationship from the observed physical active reception unit index.

3. The wireless secure communication method based on camouflage activation mechanism and index direction modulation according to claim 2, characterized in that, In S2, the state transition table is a reversible mapping table; given the previous time slot security state and frame-level perturbation parameters, different state transition bits correspond to different next security states, enabling the legitimate receiver to uniquely deduce the state transition bits from the current security state.

4. The wireless secure communication method based on spoofing activation mechanism and index direction modulation according to claim 3, characterized in that, In S3, when selecting an active receiver from the active receiver group based on the receiver selection bit within the group, the binary value of the receiver selection bit within the group is mapped to the valid receiver with the corresponding sequence number within the active receiver group, which serves as the unique active receiver for the current time slot.

5. The wireless secure communication method based on spoofing activation mechanism and index direction modulation according to claim 4, characterized in that, In S4, the M-ary amplitude-phase modulation adopts the quadrature phase-shift keying (QPSK) modulation method. Based on the binary value of the constellation symbol bits, it is mapped to the corresponding amplitude-phase modulation symbol in the QPSK constellation diagram. Combined with the position index of the activated receiver and the modulation symbol, the index direction modulation symbol is generated.

6. The wireless secure communication method based on masquerade activation mechanism and index direction modulation according to claim 5, characterized in that, In S5, when the transmitter constructs the precoding matrix based on the channel vectors of the legitimate receivers, the column vectors of the precoding matrix correspond one-to-one with the channel vectors of each legitimate receiver. Only the column vector of the precoding matrix corresponding to the active receiver in the current time slot has a non-zero value, while the other column vectors are all zero values. This ensures that the preprocessed transmitted signal forms a power-focused directional beam only in the direction of the active receiver.

7. The wireless secure communication method based on masquerade activation mechanism and index direction modulation according to claim 6, characterized in that, In S5, the transmitter is configured with a uniform linear antenna array. Based on the carrier wavelength and the element spacing of the antenna array, and combined with the incoming wave direction of several different legitimate receivers, a free space channel vector corresponding to each legitimate receiver is constructed for the design of the precoding matrix.

8. The wireless secure communication method based on spoofing activation mechanism and index direction modulation according to claim 7, characterized in that, In S6, the legitimate receiver uses the maximum likelihood detection algorithm, based on the minimum Euclidean distance criterion, to jointly detect the received signal, and simultaneously complete the identification and demodulation of the active receiver index and the M-ary amplitude-phase modulation symbol.

9. The wireless secure communication method based on spoofing activation mechanism and index direction modulation according to claim 8, characterized in that, In S6, when demodulating the state transition bits, the central processing unit reconstructs the candidate receiving domains corresponding to each security state of the current time slot based on the currently detected physical active receiving unit index, combined with the security state of the previous time slot and the candidate receiving domain generation rules. In the candidate receiving domains, the current security state and its index within the domain that match the current physical active receiving unit index are determined, and the transition relationship from the security state of the previous time slot to the security state of the current time slot is demapped into state transition bits according to the preset state transition rules or the state inverse mapping table.

10. The wireless secure communication method based on masquerade activation mechanism and index direction modulation according to claim 9, characterized in that, The legitimate receiving end includes several distributed receiving units, which are located in different spatial locations or different receiving directions and are connected to the same central processing unit through optical fiber links. The central processing unit determines the security state, candidate receiving domain, and intra-domain index corresponding to the current time slot based on the detected physical active receiving unit index and amplitude-phase modulation symbols, combined with the historical security state and candidate receiving domain generation rules. It then recovers the state transition bits, intra-domain index bits, and constellation symbol bits according to the preset state inverse mapping rules, thereby reconstructing the complete information bit stream.

Images