An improved interference alignment secure transmission method to avoid eliminating useful signals

Abstract

The present invention belongs to the field of wireless communication technology, and specifically relates to an improved interference alignment secure transmission method for avoiding elimination of useful signals; the method comprises: a confidential transmitting end sends a confidential signal to a receiving end, and a non-confidential transmitting end sends a non-confidential signal to a receiving end; the receiving end comprises a confidential receiving end, a non-confidential receiving end and an eavesdropping user; an improved interference alignment algorithm for avoiding elimination of useful signals is used to process the transmitting signal and the receiving signal to obtain a transmitting scheme and a receiving scheme; a maximum security rate objective function is constructed according to the transmitting scheme and the receiving scheme; the maximum security rate objective function is solved to obtain an optimal power allocation scheme for a confidential transmitting end; and signal secure transmission is performed according to the transmitting scheme, the receiving scheme and the optimal power allocation scheme for a confidential transmitting end; the present invention avoids the problem that a traditional interference alignment algorithm may cause elimination of useful signals, and can guarantee the service quality of confidential users to the greatest extent on the basis of ensuring security performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to an improved interference alignment safety transmission method for avoiding elimination of useful signals. Background Art

[0002] Due to the open and broadcast characteristics of wireless channels, wireless communications are extremely vulnerable to eavesdropping by illegal users. Therefore, ensuring the security of communications in wireless environments is a key issue. As a supplement to traditional cryptography-based encryption methods, physical layer security technology uses the physical characteristics of wireless channels to achieve highly secure transmission and has received widespread attention. The introduction of the eavesdropping channel model and the concept of security capacity has laid the foundation for the development of physical layer security transmission. If the reliability of the main channel (defined as the channel between the legitimate users Alice and Bob) is higher than the reliability of the eavesdropping channel (defined as the channel between the illegal user Eve and the sender Alice), then the legitimate user Bob can achieve correct decoding, while the illegal user Eve cannot.

[0003] On the other hand, interference is usually minimized, eliminated or avoided in wireless networks. However, contrary to this traditional view, methods have recently emerged to improve secure communications by taking advantage of the inherent interference in wireless networks. From this point of view, networks based on Interference Alignment (IA) are more secure. This is because the interference from legitimate transmitters is aligned at legitimate receivers and can be eliminated, however, these interferences can disrupt potential eavesdropping.

[0004] Therefore, in order to improve the security of information transmission in wireless networks, some anti-eavesdropping schemes have been proposed. For example, a multi-user interference alignment network introduces artificial noise to ensure the security of transmission. This scheme uses the traditional interference alignment algorithm to design the precoding matrix and interference suppression matrix of the transceiver, but this limits the application of the algorithm in practice. On this basis, a novel anti-eavesdropping scheme based on interference alignment network has emerged, but this scheme uses traversal capacity as a performance indicator and does not consider security interruption. When the instantaneous channel state information (CSI) of the eavesdropping node is unknown, it is impossible to maintain a stable security rate on the fading channel. Therefore, security interruption cannot be absolutely avoided. In addition, there is a scheme for secure transmission based on artificial noise in interference alignment wireless networks, but this scheme fixes the power distribution between confidentiality signals and AN signals and cannot adapt to the dynamic changes of wireless networks.

[0005] In addition, traditional interference alignment algorithms may lead to the elimination of useful signals. The signal elimination problem will seriously affect the effective performance of the interference alignment algorithm, especially when transmitting higher priority information such as confidential information. The signal elimination problem will affect the service quality of the target user.

[0006] In summary, there is an urgent need for a secure transmission method that can avoid eliminating useful signals, can take into account security interruptions, avoid eliminating useful signals, and can adapt to dynamic changes in wireless networks. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention proposes an improved interference alignment secure transmission method that avoids eliminating useful signals. The method comprises:

[0008] S1: The secure transmitter sends a secure signal to the receiver, and the non-secure transmitter sends a non-secure signal to the receiver; the receiver includes a secure receiver, a non-secure receiver, and an eavesdropping user;

[0009] S2: The transmitted signal and the received signal are processed by using an improved interference alignment algorithm that avoids eliminating useful signals to obtain a transmitting scheme and a receiving scheme;

[0010] S3: Construct the objective function of maximizing the safety rate according to the transmission scheme and the receiving scheme;

[0011] S4: Solve the objective function of maximizing the security rate and obtain the optimal power allocation scheme for the secure transmitter; perform signal secure transmission according to the transmission scheme, the receiving scheme and the optimal power allocation scheme for the secure transmitter.

[0012] Preferably, the process of processing the transmitted signal and the received signal using the improved interference alignment algorithm that avoids eliminating the useful signal includes:

[0013] S21: taking the left singular vector and the right singular vector corresponding to the maximum singular value of the main channel as the beamforming vector of the secure transmitting end and the receiving vector of the secure receiving end respectively;

[0014] S22: Initialize the non-confidential transmitting end beamforming vector and AN precoding matrix;

[0015] S23: Calculate the interference covariance matrix of the confidential receiving end according to the beamforming vector of the confidential transmitting end and the AN precoding matrix; Calculate the interference covariance matrix of the non-confidential receiving end according to the beamforming vector of the confidential transmitting end, the beamforming vector of the non-confidential transmitting end and the AN precoding matrix;

[0016] S24: calculating a receiving vector of the non-confidential receiving end according to the interference covariance matrix of the non-confidential receiving end;

[0017] S25: Calculate the system interference leakage according to the receiving vector of the confidential receiving end, the interference covariance matrix of the confidential receiving end, the receiving vector of the non-confidential receiving end, and the interference covariance matrix of the non-confidential receiving end;

[0018] S26: setting a threshold of the number of iterations; when the interference leakage converges or exceeds the threshold of the number of iterations, outputting the beamforming vector of the non-confidential transmitting end, the receiving vector of the non-confidential receiving end and the AN precoding matrix; otherwise, executing step S27;

[0019] S27: Calculate the interference covariance matrix of the confidential transmitting end and the interference covariance matrix of the non-confidential transmitting end according to the receiving vector of the confidential receiving end and the receiving vector of the non-confidential receiving end; update the transmitting end beamforming vector and AN precoding matrix according to the interference covariance matrix of the confidential transmitting end and the interference covariance matrix of the non-confidential transmitting end, and return to step S23.

[0020] Furthermore, the formula for calculating the interference covariance matrix of the confidentiality receiving end is:

[0021]

[0022] Among them, Q b represents the interference covariance matrix of the confidential receiver, P represents the signal transmission power, H bj represents the channel from the jth non-secure transmitter to the secure receiver, v j represents the jth non-confidential transmitter beamforming vector, K represents the number of non-confidential transmitters, represents the number of non-confidential signals, and H ba represents the channel from the secure transmitter to the secure receiver, W a represents the AN precoding matrix.

[0023] Furthermore, the formula for calculating the interference covariance matrix of the non-confidential receiving end is:

[0024]

[0025] Among them, Q k represents the interference covariance matrix of the non-confidential receiving end, P represents the signal transmission power, K represents the number of non-confidential transmitting ends, H kj represents the channel from the jth non-secure transmitter to the kth non-secure receiver, v j represents the jth non-confidential transmitting end beamforming vector, H ka represents the channel from the secure transmitter to the kth non-secure receiver, v a represents the confidential transmitter beamforming vector, d an represents the number of non-confidential signals, W a represents the AN precoding matrix.

[0026] Furthermore, the formula for calculating the receiving vector of the non-confidential receiving end is:

[0027] u k =x1[Q k ]

[0028] Among them, u k represents the receiving vector of the kth non-confidential receiving end, x1[Q k ] represents the eigenvector corresponding to the minimum eigenvalue of the interference covariance matrix of the kth non-confidential receiving end.

[0029] Furthermore, the formula for calculating system interference leakage is:

[0030]

[0031] Where I represents the system interference leakage, u k represents the receiving vector of the kth non-confidential receiving end, Q k represents the interference covariance matrix of the kth non-confidential receiver, u b represents the receiving vector of the confidential receiver, Q b represents the interference covariance matrix of the secure receiver, and K represents the number of non-secure transmitters.

[0032] Furthermore, the formula for calculating the interference covariance matrix of the confidential transmitter is:

[0033]

[0034] in, represents the interference covariance matrix of the non-confidential transmitter, P represents the signal transmission power, H ba represents the channel from the secure transmitter to the secure receiver, u b represents the receiving vector of the confidential receiver, u k represents the receiving vector of the kth non-confidential receiving end, H ka represents the channel from the secure transmitter to the kth non-secure receiver, and K represents the number of non-secure transmitters.

[0035] Furthermore, the formula for calculating the interference covariance matrix of the non-confidential transmitting end is:

[0036]

[0037] in, represents the interference covariance matrix of the kth non-confidential transmitter, P represents the signal transmission power, H bk represents the channel between the kth non-secure transmitter and the secure receiver, u b represents the receiving vector of the confidential receiver, u jrepresents the receiving vector of the jth non-confidential receiving end, H jk represents the channel between the kth non-confidential transmitter and the jth non-confidential receiver, and K represents the number of non-confidential transmitters

[0038] The beneficial effects of the present invention are as follows: the present invention takes into account the problem that interference alignment may lead to signal elimination, selects the left (right) singular vector corresponding to the maximum singular value of the main channel as the beamforming vector, avoids the problem that the traditional interference alignment algorithm may lead to the elimination of useful signals, so that the signal to noise ratio at the confidential receiving end can be improved, the security rate can also be further improved, and the security of information transmission is enhanced; the present invention assumes that the base station only knows the statistical CSI of the eavesdropping node, the present invention takes into account security interruption, and finds the optimal security transmission strategy under a given security interruption probability, and has a wider range of application scenarios; the present invention can dynamically adjust the power allocation between the AN signal and the confidential signal according to different channel state information of the main channel and the channel quality of the eavesdropping channel, thereby improving the security performance of the system; in a multi-user interference network, the priority and security requirements of users transmitting confidential information are relatively high, and the present invention can guarantee the service quality of confidential users to the greatest extent on the basis of ensuring security performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a wireless communication system model in the present invention;

[0040] Figure 2 A flow chart of an improved interference alignment secure transmission method for avoiding elimination of useful signals in the present invention;

[0041] Figure 3 This is a graph showing the relationship between the interference leakage of the system and the signal-to-interference-noise ratio of the confidential signal as the number of iterations changes. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The present invention proposes an improved interference alignment secure transmission method to avoid eliminating useful signals, such as Figure 1 The method comprises the following:

[0044] S1: The secure transmitter sends a secure signal to the receiver, and the non-secure transmitter sends a non-secure signal to the receiver; the receiver includes a secure receiver, a non-secure receiver, and an eavesdropping user.

[0045] like Figure 2 As shown, a wireless communication system is constructed, in which a legal transmitter (confidential transmitter) Alice transmits confidential messages to a legal receiver (confidential receiver) Bob. At the same time, there are other K legal transmitters (non-confidential transmitters Tx1, ..., TxK) that transmit non-confidential information, K legal receivers (non-confidential receivers Rx1, ..., RxK) and a passive eavesdropping node Eve; it is assumed that each transmitter is equipped with M transmitting antennas, each receiver is equipped with N receiving antennas, and the eavesdropping node has a single receiving antenna. It is assumed that all legal channels are independent under quasi-flat fading, the eavesdropping channels are independent of each other, and both the legal channel and the eavesdropping channel obey a cyclic symmetric complex Gaussian distribution with zero mean and unit variance. The local channel state information (Channel State Information, CSI) of the legal channel is known. Due to the passive characteristics of the eavesdropping user Eve, the present invention assumes that the base station only knows Eve's statistical CSI. The confidential transmitter Alice transmits confidential information and transmits AN (artificial noise), that is, a non-confidential signal to destroy eavesdropping, so Alice's transmission signal can be constructed as:

[0046]

[0047] Alice’s transmission power is P a ; φ∈[0,1] represents P a The proportion allocated to confidential signals; x a and They represent the data symbols transmitted by Alice and their corresponding beamforming vectors respectively; and They represent the signals transmitted by Alice, including d an The data stream of an AN signal and its corresponding AN precoding matrix.

[0048] The other K transceivers in the system are used to transmit messages to the target user and to disrupt potential eavesdropping. If the transmission power of each transmitter is P k , Then the transmission signal of the non-confidential transmitter Txk is:

[0049]

[0050] Among them, x k With v k They represent the data symbol transmitted by Txk and its corresponding beamforming vector respectively.

[0051] At the secure receiver Bob, the received signals at the non-secure receiver Rxk and the eavesdropping user Eve can be expressed as follows after receiving and merging:

[0052]

[0053]

[0054]

[0055] Among them, the channel between Alice to Bob, Rxk and Eve is expressed as and The channel between Txj to Bob, Rxk and Eve is represented as and j,k∈{1,…,K}. In particular, H ba and H kk They represent the direct links between Alice-Bob and Txk-Rxk respectively. b ,n k ,n e Respectively represent the additive white Gaussian noise vectors at Bob, Rxk and Eve; u b represents the receiving vector at Bob, u k represents the beamforming vector of Rxk, h ea represents the channel between Alice and Eve, h ej Represents the channel between the jth non-confidential transmitter and Eve.

[0056] S2: The transmitted signal and the received signal are processed by using an improved interference alignment algorithm that avoids eliminating useful signals to obtain a transmission scheme and a reception scheme.

[0057] In order to avoid eliminating confidential signals, the present invention uses an improved interference alignment algorithm that avoids eliminating useful signals to optimize the beamforming design of Alice and Bob, and processes the transmitted and received signals; specifically:

[0058] S21: Select the main channel H respectively ba The left singular vector and the right singular vector corresponding to the maximum singular value are used as the beamforming vector v of Alice at the confidential transmitter. a and the confidential receiving end Bob beamforming vector u b .

[0059] S22: Initialize the non-confidential transmitter Txk beamforming vector v k and AN precoding matrix W a ; and respectively satisfy and Represents the identity matrix.

[0060] S23: Based on the non-confidential transmitting end beamforming vector v kand AN precoding matrix W a Calculate the interference covariance matrix Q of the secure receiver b ; According to the confidential transmitter beamforming vector v a , the non-confidential transmitting end beamforming vector v k and AN precoding matrix W a Calculate the interference covariance matrix Q of the non-confidential receiver k .

[0061] In order to enable the receiver to estimate the interference covariance matrix, in the interference alignment process, through the cooperation between transmitters, the power of each beam of the K transmitters and Alice is fixed to be the same, all P, that is, P1 = P2 = ... = P K =P,P a =(d an +1)P; the formula for calculating the interference covariance matrix of the confidentiality receiving end is:

[0062]

[0063] Among them, Q b represents the interference covariance matrix of the confidential receiver, P represents the signal transmission power, H bj represents the channel from the jth non-secure transmitter to the secure receiver, v j represents the jth non-confidential transmitter beamforming vector, K represents the number of non-confidential transmitters, d an represents the number of non-confidential signals, H ba Represents the channel from the secure transmitter to the secure receiver.

[0064] The formula for calculating the interference covariance matrix of the non-confidential receiving end is:

[0065]

[0066] Among them, Q k represents the interference covariance matrix of the non-confidential receiver, H kj represents the channel from the jth non-secure transmitter to the kth non-secure receiver, v j represents the jth non-confidential transmitting end beamforming vector, H ka represents the channel from the secure transmitter to the kth non-secure receiver.

[0067] S24: Based on the interference covariance matrix Q of the non-confidential receiving end k Calculate the receiving vector u of the non-confidential receiving end k .

[0068] The formula for calculating the receiving vector of the non-confidential receiving end is:

[0069]

[0070] Among them, u k represents the receiving vector of the kth non-confidential receiving end, x1[Q k ] represents the eigenvector corresponding to the minimum eigenvalue of the interference covariance matrix of the kth non-confidential receiving end.

[0071] S25: Based on the receiving vector u of the confidential receiving end b , the interference covariance matrix Q of the confidential receiver b , the receiving vector u of the non-confidential receiving end k and the interference covariance matrix Q of the non-confidential receiver k Computing system interference leakage.

[0072] According to the receiving vector u of the confidential receiving end b and the interference covariance matrix Q of the confidential receiver b Calculate the interference leakage of the confidential receiver Bob, the calculation formula is:

[0073]

[0074] According to the receiving vector u of the non-confidential receiving end k and the interference covariance matrix Q of the non-confidential receiver k Calculate the interference leakage of the non-confidential receiving end Rxk, the calculation formula is:

[0075]

[0076] Therefore, the total interference leakage of the system is:

[0077]

[0078] S26: Set the iteration number threshold; when the interference leakage converges or exceeds the iteration number threshold, output the non-confidential transmitting end beamforming vector v k , the receiving vector u of the non-confidential receiving end k and AN precoding matrix W a ; Otherwise, execute step S27.

[0079] Set the interference leakage stop criterion, that is, when the interference leakage converges or exceeds the iteration number threshold, stop the iteration and output the transmission scheme, that is, the non-confidential transmitting end beamforming vector v k and AN precoding matrix W a And the receiving vector is the receiving vector u of the non-confidential receiving end k .

[0080] S27: Based on the receiving vector u of the confidential receiving end b and the receiving vector u of the non-confidential receiving end kCalculate the interference covariance matrix of the confidential transmitter and the interference covariance matrix of the non-confidential transmitter According to the interference covariance matrix of the confidential transmitter and the interference covariance matrix of the non-confidential transmitter Update the transmit beamforming vector v k and AN precoding matrix W a , return to step S23.

[0081] The formula for calculating the interference covariance matrix of the confidential transmitter is:

[0082]

[0083] in, represents the interference covariance matrix of the non-confidential transmitter, H ba represents the channel from the secure transmitter to the secure receiver, u k represents the receiving vector of the kth non-confidential receiving end, H ka represents the channel from the secure transmitter to the kth non-secure receiver.

[0084] The formula for calculating the interference covariance matrix of the non-confidential transmitter is:

[0085]

[0086] in, represents the interference covariance matrix of the kth non-confidential transmitter, H bk represents the channel from the kth non-secure transmitter to the secure receiver, u b represents the confidential transmitter beamforming vector, u j represents the receiving vector of the jth non-confidential receiving end, H jk represents the channel from the kth non-secure transmitter to the jth non-secure receiver.

[0087] The formula for updating the transmit beamforming vector is:

[0088]

[0089] in, Representation Matrix The eigenvector corresponding to the smallest eigenvalue.

[0090] The formula for updating the AN precoding matrix is:

[0091]

[0092] in, Representation Matrix The eigenvectors corresponding to the first d smallest eigenvalues.

[0093] S3: Construct the objective function of maximizing the safety rate based on the transmission scheme and the receiving scheme.

[0094] Under the interference alignment condition, the interference and AN can be aligned and eliminated at the legitimate user Bob, but these interferences can destroy potential eavesdropping. Therefore, the signal-to-interference-plus-noise ratio (SINR) at Bob and Eve is calculated according to the transmission scheme and the receiving scheme:

[0095]

[0096]

[0097] Among them, γ b (φ) represents the signal-to-interference-to-noise ratio of the secure receiver, γ e (φ) represents the signal-to-interference-to-noise ratio of the eavesdropping user, and φ represents the transmission power P a The proportion allocated to confidential signals.

[0098] Since only the statistical CSI of the eavesdropping node is known, security interruption cannot be avoided. Next, we consider maximizing the security rate under the constraint of the interruption probability, and construct the maximum security rate objective function as follows:

[0099]

[0100] stPr(γ e (φ)>μ)=ε

[0101] Among them, R S represents Alice’s secure transmission rate, and ε represents the maximum allowed security interruption probability. represents the threshold value related to the outage probability, represents the effective signal-to-noise ratio at Bob. Next, we will optimize φ, let w(φ)μ / φ, then the above objective function can be rewritten as

[0102]

[0103] Solve the objective function of maximizing the security rate and obtain the optimal power allocation plan for the secure transmitter; perform secure signal transmission based on the transmission plan, the receiving plan and the optimal power allocation plan for the secure transmitter.

[0104] By solving the above objective function, we can get the optimal power allocation ratio φ * and the corresponding maximum safe rate That is, the optimal confidentiality transmitter power allocation scheme.

[0105] The transmitter and the receiver perform secure signal transmission according to the best secure transmission scheme, namely the transmission scheme, the receiving scheme and the optimal confidentiality transmitter power allocation scheme.

[0106] The present invention is evaluated as follows: Figure 3 As shown, the interference leakage of the improved interference alignment security transmission scheme of the present invention and the traditional interference alignment security transmission scheme can converge to a very small value as the number of iterations increases, that is, both schemes can achieve interference alignment. However, the signal-to-noise ratio of the confidential signal in the traditional interference alignment security transmission scheme gradually tends to 0 as the number of iterations increases, which indicates that the scheme eliminates the confidential signal when implementing interference alignment. In the present invention, the signal-to-noise ratio of the confidential signal does not decrease as the number of iterations increases, which verifies that the present invention can avoid the elimination of useful signals while achieving interference alignment, so the present invention is superior to the traditional interference alignment security transmission scheme.

[0107] The use of the present invention for confidential signal transmission can effectively avoid the situation where traditional interference alignment algorithms may eliminate useful signals. At the same time, in a multi-user interference network, users who transmit confidential information have higher priority and security requirements, and this solution can guarantee the service quality of confidential users to the greatest extent on the basis of ensuring security performance. In the case where the transmitter only knows the eavesdropping node statistical CSI, the present invention takes into account security interruptions and finds the optimal security transmission strategy under a given security interruption probability, which has a wider range of application scenarios. On the basis of interference alignment, the present invention takes into account the power distribution between confidential signals and AN signals, thereby further enhancing the security performance of the system.

[0108] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation modes of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An improved interference alignment secure transmission method to avoid eliminating useful signals, characterized in that: include: S1: The secure transmitter sends a secure signal to the receiver, and the non-secure transmitter sends a non-secure signal to the receiver; the receiver includes a secure receiver, a non-secure receiver, and an eavesdropping user; S2: using an improved interference alignment algorithm that avoids eliminating useful signals to process the transmitted signal and the received signal to obtain a transmission scheme and a receiving scheme; the process of using the improved interference alignment algorithm that avoids eliminating useful signals to process the transmitted signal and the received signal includes: S21: taking the left singular vector and the right singular vector corresponding to the maximum singular value of the main channel as the beamforming vector of the secure transmitting end and the receiving vector of the secure receiving end respectively; S22: Initialize the non-confidential transmitting end beamforming vector and AN precoding matrix; S23: Calculate the interference covariance matrix of the confidential receiving end according to the beamforming vector of the confidential transmitting end and the AN precoding matrix; Calculate the interference covariance matrix of the non-confidential receiving end according to the beamforming vector of the confidential transmitting end, the beamforming vector of the non-confidential transmitting end and the AN precoding matrix; The formula for calculating the interference covariance matrix of the confidential receiver is: Among them, Q b represents the interference covariance matrix of the confidential receiver, P represents the signal transmission power, H bj represents the channel from the jth non-secure transmitter to the secure receiver, v j represents the jth non-confidential transmitter beamforming vector, K represents the number of non-confidential transmitters, d an represents the number of non-confidential signals, H ba represents the channel from the secure transmitter to the secure receiver, W a represents the AN precoding matrix; The formula for calculating the interference covariance matrix of the non-confidential receiving end is: Among them, Q k represents the interference covariance matrix of the non-confidential receiver, H kj represents the channel from the jth non-secure transmitter to the kth non-secure receiver, v j represents the jth non-confidential transmitting end beamforming vector, H ka represents the channel from the secure transmitter to the kth non-secure receiver, v a represents the confidential transmitter beamforming vector; S24: calculating a receiving vector of the non-confidential receiving end according to the interference covariance matrix of the non-confidential receiving end; The formula for calculating the receiving vector of the non-confidential receiving end is: you k =x1[Q k ] Among them, u k represents the receiving vector of the kth non-confidential receiving end, x1[Q k ] represents the eigenvector corresponding to the minimum eigenvalue of the interference covariance matrix of the kth non-confidential receiving end; S25: Calculate the system interference leakage according to the receiving vector of the confidential receiving end, the interference covariance matrix of the confidential receiving end, the receiving vector of the non-confidential receiving end, and the interference covariance matrix of the non-confidential receiving end; The formula for calculating system interference leakage is: Where I represents the system interference leakage, u b represents the receiving vector of the confidential receiving end; S26: setting a threshold of the number of iterations; when the interference leakage converges or exceeds the threshold of the number of iterations, outputting the beamforming vector of the non-confidential transmitting end, the receiving vector of the non-confidential receiving end and the AN precoding matrix; otherwise, executing step S27; S27: Calculate the interference covariance matrix of the confidential transmitting end and the interference covariance matrix of the non-confidential transmitting end according to the receiving vector of the confidential receiving end and the receiving vector of the non-confidential receiving end; Update the transmitting end beamforming vector and the AN precoding matrix according to the interference covariance matrix of the confidential transmitting end and the interference covariance matrix of the non-confidential transmitting end, and return to step S23; The formula for calculating the interference covariance matrix of the confidential transmitter is: in, represents the interference covariance matrix of the non-confidential transmitter; The formula for calculating the interference covariance matrix of the non-confidential transmitter is: in, represents the interference covariance matrix of the kth non-confidential transmitter, H bk represents the channel between the kth non-secure transmitter and the secure receiver, u j represents the receiving vector of the jth non-confidential receiving end, H jk represents the channel between the kth non-secure transmitter and the jth non-secure receiver; S3: Construct the maximum safety rate objective function based on the transmission scheme and the receiving scheme; the maximum safety rate objective function is as follows: stPr(γ e (φ)>μ)=ε Among them, R S represents the secure transmission rate of the secure transmitter, ε represents the maximum allowed secure interruption probability, μ represents the threshold related to the interruption probability, and γ represents the effective signal-to-noise ratio of the secure receiver; e (φ) represents the signal-to-interference-to-noise ratio of the eavesdropping user, and φ represents the power allocation ratio; S4: Solve the objective function of maximizing the security rate to obtain the optimal power allocation plan for the secure transmitter; perform secure signal transmission according to the transmission plan, the receiving plan and the optimal power allocation plan for the secure transmitter; wherein the optimal power allocation plan for the secure transmitter is the optimal power allocation ratio and its corresponding maximum security rate for the transmitter.

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