A wireless power communication method based on a multi-antenna relay system

Abstract

The present disclosure relates to a wireless power communication method based on a multi-antenna relay system. The method comprises the following steps: establishing a multi-antenna relay system model; the multi-antenna relay system comprises a source node, a destination node, a relay node and a plurality of eavesdropping nodes E i Wherein, the relay node is equipped with K antennas, and the other nodes are each equipped with a single antenna; the multi-antenna relay system performs wireless power communication based on a PS protocol; according to the result of wireless power communication, an ergodic secrecy rate is derived, thereby measuring the secrecy transmission performance gain of the multi-antenna relay system. The wireless power communication method based on the multi-antenna relay system can effectively improve the secrecy transmission performance of the multi-antenna relay system while solving the problem of limited signal processing energy in the multi-antenna relay system.

Description

Technical Field

[0001] This disclosure relates to the field of communication security technology, and in particular to a wireless power-carrying communication method based on a multi-antenna relay system. Background Technology

[0002] With the gradual popularization of 5G mobile communication and the rapid development of Internet of Things (IoT) technology, the application fields of wireless communication are becoming increasingly broad. However, due to the openness and complexity of wireless channels, the problem of information leakage is becoming increasingly prominent, posing a huge challenge to the secure transmission of information.

[0003] Simultaneous wireless information and power transfer (SWIPT) technology utilizes the energy-carrying characteristic of radio frequency signals, enabling network nodes to collect energy while receiving information. This technology provides an effective solution to the problem of energy constraints at network nodes and has been applied in various networks.

[0004] However, SWIPT still faces several challenges in addressing security threats across various scenarios: First, when targeting untrusted relay networks, it often relies on a single, fixed eavesdropping node, lacking application in scenarios with multiple eavesdropping nodes. Second, when using friendly jammers for signal-assisted transmission, it primarily focuses on a specific stage of the relay system's transmission process, or only considers the part of the secure signal transmission being intercepted, leaving the risk of information leakage still significant throughout the entire transmission process across all nodes. Therefore, it is necessary to address one or more of the aforementioned technical solutions to enhance the physical layer security performance of multi-antenna relay systems.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this disclosure is to provide a wireless power-carrying communication method based on a multi-antenna relay system to enhance the physical layer security performance of the multi-antenna relay system.

[0007] This disclosure provides a wireless power-carrying communication method based on a multi-antenna relay system, the method comprising the following steps:

[0008] Establish a model of a multi-antenna relay system; this multi-antenna relay system includes a source node, a destination node, a relay node, and several eavesdropping nodes E. i The relay node is equipped with K antennas, while other nodes are equipped with only a single antenna.

[0009] The multi-antenna relay system performs wireless power-carrying communication based on the PS protocol;

[0010] Based on the results of wireless energy-carrying communication, the achievable secure rate of traversal is derived, thereby measuring the secure transmission performance gain of the multi-antenna relay system.

[0011] In an exemplary embodiment of this disclosure, in the step of establishing the multi-antenna relay system model, all nodes operate in half-duplex mode; when the multi-antenna relay system transmits signals, the internal interference between all antennas can be completely self-cancelled; all eavesdropping nodes are able to eavesdrop on the confidential signals transmitted by the multi-antenna relay system at each stage of wireless power-carrying communication; the location distribution of the eavesdropping nodes follows an independent Poisson process; there is only one source node, one destination node, and one relay node.

[0012] In an exemplary embodiment of this disclosure, during the wireless power-carrying communication process of the multi-antenna relay system based on the PS protocol, one communication cycle includes two phases with equal time slots, wherein...

[0013] The first stage includes the following processes:

[0014] Source node S with power P S Sends an energy-carrying radio frequency signal x to relay node R sr The destination node D uses power P D A friendly interference signal carrying energy is transmitted to the relay node R. dj The relay node R uses one antenna R according to the PS protocol. i The system receives both types of energy-carrying signals and divides the received signals into two parts according to a power splitting structure: one part is the EH module used for energy acquisition, and the other part is the IT module used for signal transmission.

[0015] The second phase includes the following processes:

[0016] The relay node R uses the energy collected by the EH module to amplify and forward the signal from the IT module to the destination node D; simultaneously, the relay node R uses another antenna R j They emitted coordinated jamming signals to continue interfering with the eavesdroppers.

[0017] In an exemplary embodiment of this disclosure, the proportion of signals entering the EH module is ρ, and the proportion of signals entering the IT module is 1-ρ, where ρ is a power splitting factor, 0<ρ<1.

[0018] In an exemplary embodiment of this disclosure, the antenna R i The formula for the optimal legal signal transmission antenna includes:

[0019]

[0020] Where K represents the number of antennas; C M The channel capacity of the optimal legal signal is represented by ρ; the power splitting factor is represented by θ; and the power allocation coefficient is represented by E. R P represents the energy collected by the relay node. R The signal amplified and forwarded by the relay node represents the power; T represents the communication period; i represents the index of the antenna number, 1≤i≤K; γ D Indicates the received signal-to-interference-plus-noise ratio at the destination node;

[0021] The optimal legal signal transmission antenna R i The formula for the received signal includes:

[0022]

[0023] Among them, P S This represents the power of the signal transmitted by the source node S; This represents the small-scale fading between the i-th transmission antenna of the source node S and the relay node R; x represents the average channel gain between the i-th transmit antenna of the source node S and the relay node R; sr Indicates radio frequency signal; P D This indicates the power of the friendly interference signal transmitted by the destination node D; This represents the small-scale fading between the i-th transmission antenna of the destination node D and the relay node R; x represents the average channel gain between the i-th transmit antenna of the destination node D and the relay node R; dj This indicates a friendly interference signal; This represents the additive white Gaussian noise at the i-th transmission antenna;

[0024] In the first stage, the formula for relay node R to collect energy includes:

[0025]

[0026] Where η represents the energy conversion efficiency, 0 < η < 1; N0 represents the magnitude of the additive white Gaussian noise at the i-th transmission antenna;

[0027] The formulas for signal transmission at relay node R include:

[0028]

[0029] The superscript IT indicates the information transmission IT module.

[0030] In an exemplary embodiment of this disclosure, the antenna R jThe optimal interference signal transmission antenna was obtained using the Q-learning algorithm;

[0031] In the second phase, the relay node R utilizes the energy collected in the first phase via antenna R. i For signal Amplify and relay the signal, and transmit it through antenna R. j Transmit cooperative jamming signal x rj The transmitted signal is denoted as: Where G is the amplification factor, and the formula for G includes:

[0032]

[0033] The formula for obtaining the signal received by the destination node D includes:

[0034]

[0035] Among them, P R and P j Let P represent the power of the relay node amplifying and forwarding the signal and the power of the transmitted cooperative interference signal, respectively, to obtain the total power P. SUM =P R +P J , let P R =θP SUM Then P J =(1-θ)P SUM θ is the power distribution coefficient; n D x represents the additive white Gaussian noise at the receiving antenna of the destination node; rj Indicates the selected antenna R at the relay location. j Interference signals were sent.

[0036] In an exemplary embodiment of this disclosure, the process of deriving the achievable secure rate and analyzing the secure transmission performance gain of the system includes the following steps:

[0037] Based on the communication results of the first and second stages of wireless power-carrying communication, the signal-to-interference-plus-noise ratio (SINR) of the received signals at different nodes, as well as its probability density function and cumulative distribution function, are derived.

[0038] In an exemplary embodiment of this disclosure, for the first stage of wireless power-carrying communication:

[0039] Based on formula (1), the formulas for the cumulative distribution function and probability density function of the channel from source node S to relay node R are derived as follows:

[0040] and

[0041]

[0042] Among them, F X (x) represents the cumulative distribution function; f X (x) represents the probability density function; X represents the random variable; K represents the number of antennas; The rate parameter represents the exponential distribution of the channel between the i-th transmission antenna of the source node S and the relay node R.

[0043] The optimal legal signal transmission antenna R is derived from formula (2). i The received signal-to-interference-plus-noise ratio (SINR) is given by the formula:

[0044]

[0045] For the eavesdropping node E i The formula for the received signal includes:

[0046]

[0047] The formula for the SINR of the signal received by the most dangerous eavesdropping node includes:

[0048]

[0049] Among them, P S This represents the power of the signal transmitted by the source node S; Represents the source node S and any eavesdropping node E i Small-scale decay between intervals; Represents the source node S and any eavesdropping node E i Average channel gain between; P D This indicates the power of the friendly interference signal transmitted by the destination node D; Represents the destination point D and any eavesdropping node E. i Small-scale decay between intervals; This represents the destination node D and any eavesdropping node E. i The average channel gain between; N0 represents the magnitude of the additive white Gaussian noise at the i-th transmission antenna; i represents the index of the eavesdropping node; Φ E This represents the set of eavesdropping nodes; the superscript (1) indicates the first stage of the eavesdropping attack;

[0050] When all the total energy collected in the first stage is used for signal transmission in the second stage, the formula for the total power used for relay node amplification, forwarding, and transmission of cooperative interference signals includes:

[0051]

[0052] In an exemplary embodiment of this disclosure, the second stage of wireless power-carrying communication is described as follows:

[0053] According to formulas (5) and (6), when the destination node D and the relay node R interfere with each other's transmitted interference signals x dj and x rj Known a priori, and based on the principle of channel reciprocity... Formula (5) simplifies to:

[0054]

[0055] The formula for obtaining the SINR of the received signal at destination node D includes:

[0056]

[0057] For the most dangerous eavesdropping node E i The formulas for the received signal and its SINR are as follows:

[0058] and

[0059]

[0060] Wherein, the superscript (2) indicates the second stage of the eavesdropping attack; ρ represents the power splitting factor; P S P represents the power of the signal transmitted by the source node S; R This indicates the power of the relay node in amplifying and forwarding the signal; This represents the small-scale fading between the i-th transmission antenna of the source node S and the relay node R; This indicates that the i-th transmission antenna of relay node R is connected to any eavesdropping node E. i Small-scale decay between intervals; This represents the average channel gain between the i-th transmission antenna of the source node S and the relay node R; This indicates that the i-th transmission antenna of relay node R is connected to any eavesdropping node E. i Average channel gain between; S n and T n Indicates formula substitution symbols;

[0061] in,

[0062] In an exemplary embodiment of this disclosure, the formula for the traversal achievable security rate includes:

[0063]

[0064] in, and These represent the legal channel capacity and the eavesdropping channel capacity, respectively; (a) represents the code for the operation step, specifically using the inequality. To perform the calculations, formula (18) includes:

[0065]

[0066] Given the optimal legal signal transmission antenna R i and the optimal interference signal antenna R j The formula for calculating the achievable security rate through traversal includes:

[0067]

[0068]

[0069] in,

[0070] λ S =P S / N0,λ D =P D / N0;

[0071]

[0072] in, This indicates the achievable confidentiality rate during traversal; Represents the expectation operation; C S Indicates the capacity of the secure channel; λ represents the cumulative distribution function of the received signal-to-interference-plus-noise ratio at the eavesdropping node. S This represents the signal-to-noise ratio transmitted by the source node.

[0073] The technical solution provided in this disclosure includes at least the following beneficial effects:

[0074] This disclosure proposes a wireless power-carrying method based on a multi-antenna relay system, achieving secure physical layer transmission through a two-stage cooperative interference communication process. For non-collusive eavesdropping scenarios where the eavesdropper independently decodes information, this disclosure proposes two strategies based on cooperative interference security technology: optimal antenna selection (OAS) and optimal jamming antenna selection (OJAS) based on Q-learning. Furthermore, by utilizing the signal-to-interference-plus-noise ratio (SINR), probability density function, and cumulative distribution function corresponding to different channels, the achievable secure rate is derived, enabling the analysis of the impact of parameter variations in the multi-antenna relay system on the security performance of the transmission scheme. The proposed scheme effectively enhances the security performance of multi-antenna relay systems.

[0075] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0076] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0077] Figure 1 A schematic diagram illustrating the steps of a wireless power-carrying communication method based on a multi-antenna relay system in an exemplary embodiment of this disclosure;

[0078] Figure 2 This diagram illustrates a multi-antenna relay system model according to an exemplary embodiment of this disclosure.

[0079] Figure 3 A schematic diagram illustrating the signal and energy transmission process in a multi-antenna relay system according to an exemplary embodiment of the present disclosure is shown.

[0080] Figure 4 The simulation experiment illustrating exemplary embodiments of this disclosure shows the ergodic attainable security rate of the system under three different schemes as a function of the transmit signal-to-noise ratio λ. S A graph showing the changes;

[0081] Figure 5 The graphs showing the traversal reach of the security rate as a function of energy conversion efficiency η under three different schemes in simulation experiments of exemplary embodiments of the present disclosure are illustrated.

[0082] Figure 6 A graph showing the traversal achievable security rate of the system in an exemplary embodiment of this disclosure as a function of the power splitting factor ρ is presented.

[0083] Figure 7 A graph showing the ergonomically achievable security rate of the system in an exemplary embodiment of this disclosure as a function of the number of relay antennas K is presented.

[0084] Figure 8 This diagram illustrates the impact of changes in the relative positions of nodes on the secure transmission performance of the system in an exemplary embodiment of this disclosure. Detailed Implementation

[0085] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0086] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0087] This example implementation provides a wireless power-carrying communication method based on a multi-antenna relay system, referencing... Figure 1 As shown, the method may include the following steps:

[0088] Step S101: Establish a multi-antenna relay system model; the multi-antenna relay system includes a source node, a destination node, a relay node, and several eavesdropping nodes E. i The relay node is equipped with K antennas, while other nodes are equipped with only a single antenna.

[0089] Step S102: The multi-antenna relay system performs wireless power-carrying communication based on the PS protocol;

[0090] Step S103: Based on the results of wireless power-carrying communication, the achievable secure rate of traversal is derived, thereby measuring the secure transmission performance gain of the multi-antenna relay system.

[0091] The steps of the method described above in this example implementation will now be explained in more detail.

[0092] In step S101, the multi-antenna relay system model of this disclosure includes a source node S, a destination node D, a relay node R, and several eavesdropping nodes E. i In this configuration, except for relay node R, which is equipped with K antennas, all other nodes are equipped with only a single antenna. Furthermore, relay node R has energy harvesting capabilities, allowing it to convert the energy carried by the signal into its own energy. To more closely resemble the deployment of network nodes in reality, this disclosure utilizes stochastic geometry theory to model the eavesdropping nodes, where the location distribution of eavesdroppers follows a density λ. EAn independent Poisson point process (PPP), denoted as PPPΦ. E In this disclosure, all nodes operate in half-duplex mode, and the internal interference between all antennas in the multi-antenna relay system can be completely self-cancelled when transmitting signals; all eavesdropping nodes can eavesdrop on the confidential signals transmitted by the multi-antenna relay system at each stage of wireless power-carrying communication; and considering that there is no direct link between the source node S and the destination node D due to the influence of deep fading or severe obstacles, it is necessary to complete the signal and power exchange by means of relay node R.

[0093] In step S102, during the wireless power-carrying communication process based on the PS protocol in the multi-antenna relay system, one communication cycle includes two phases with equal time slots:

[0094] Step S1021 is the first stage, which includes the following process: Source node S with power P S Sends an energy-carrying radio frequency signal x to relay node R sr The destination node D uses power P D Transmit a friendly jamming signal carrying energy to relay node R dj The relay node R uses one antenna R according to the PS protocol. i The system receives both types of energy-carrying signals and divides the received signals into two parts according to the power splitting (PS) structure: one part is the energy harvesting (EH) module, and the other part is the information transmission (IT) module.

[0095] Step S1022 is the second stage, which includes the following process: Relay node R uses the energy collected by the EH module to amplify and forward the signal from the IT module to the destination node D; simultaneously, relay node R uses another antenna R j They emitted coordinated jamming signals to continue interfering with the eavesdroppers.

[0096] According to the appendix Figure 2 and attached Figure 3As shown, step S102 specifically includes the following: According to the SWIPT technique, in the first stage, after the relay node R receives the mixed signal from the source node S and the destination node D, according to the power splitting structure of the signal, when the splitting factor is ρ (0 < ρ < 1), the mixed signal is divided into two parts. One part is used for energy harvesting, and the remainder is used for signal transmission. The proportion entering the EH module is ρ, and the portion entering the IT module for information processing is 1-ρ. In the second stage, the relay node R uses the energy harvested by the EH module in the first stage to send the signal in the IT module to the destination node D; simultaneously, the relay node R uses antenna R... j By sending cooperative jamming signals to continue interfering with eavesdroppers, the system ultimately achieves secure two-stage transmission of both signals and energy.

[0097] To simplify the analysis without loss of generality, the wireless power-carrying communication disclosed herein considers scenarios combining large-scale and small-scale fading. The large-scale fading employs a free-space propagation model, while the small-scale fading employs a quasi-static flat Rayleigh fading model. Therefore, the channel gain from node i to node j can be expressed as g. ij =L ij |h ij | 2 Where i,j∈{S,R,D,E}, d ij Let represent the distance between node i and node j, and α be the path loss coefficient. ij | 2 Follows the mean μ ij The exponential distribution, μ ij Let represent the average channel gain between nodes i and j. Assume that the channel between any two identical nodes is reciprocal, and that the noise at the receiving antennas of different nodes is additive white Gaussian noise (AWGN) with a mean of 0 and a variance of N0, specifically denoted as:

[0098] Because the channel conditions differ before and after each antenna of a multi-antenna relay node R completes signal transmission, this disclosure selects an antenna from the multi-antenna relay node R that maximizes the legal channel capacity between the source node S and the destination node D, based on the utilization of wireless channel resources and information transmission rate, to assist in signal transmission before signal transmission. This process is the optimal antenna selection (OAS) strategy, where the selected antenna R... i The formula for the optimal legal signal transmission antenna includes:

[0099]

[0100] Where K represents the number of antennas; C M The channel capacity of the optimal legal signal is represented by ρ; the power splitting factor is represented by θ; and the power allocation coefficient is represented by E. R P represents the energy collected by the relay node. R γ represents the power of the relay node amplifying and forwarding the signal; T represents the communication period; i represents the index of the antenna number (1≤i≤K); D This indicates the received signal-to-interference-plus-noise ratio (SIR) at the destination node.

[0101] In the first stage, the optimal legal signal transmission antenna R i The formula for the received signal includes:

[0102]

[0103] Among them, P S This represents the power of the signal transmitted by the source node S; This represents the small-scale fading between the i-th transmission antenna of the source node S and the relay node R; x represents the average channel gain between the i-th transmit antenna of the source node S and the relay node R; sr Indicates radio frequency signal; P D This indicates the power of the friendly interference signal transmitted by the destination node D; This represents the small-scale fading between the i-th transmission antenna of the destination node D and the relay node R; x represents the average channel gain between the i-th transmit antenna of the destination node D and the relay node R; dj This indicates a friendly interference signal; This represents the additive white Gaussian noise at the i-th transmission antenna.

[0104] The energy collected by relay node R and the signal transmission formulas for entering the IT module are respectively as follows:

[0105] and

[0106]

[0107] Where η represents the energy conversion efficiency, 0 < η < 1; N0 represents the magnitude of the additive white Gaussian noise at the i-th transmission antenna; the superscript IT represents the Information Transmission (IT) module.

[0108] In the second phase, relay node R utilizes the energy collected in the first phase through antenna R. i For signal Amplify and relay the signal, and transmit it through antenna R. j Transmit cooperative jamming signal xrj The transmitted signal is denoted as: Where G is the amplification factor, and the formula for G includes:

[0109]

[0110] The formula for obtaining the signal received by the destination node D includes:

[0111]

[0112] Among them, P R and P j Let P represent the amplified forwarding signal power and the transmitted cooperative interference signal power of the relay node, respectively, to obtain the total power P. SUM =P R +P J , let P R =θP SUM Then P J =(1-θ)P SUM θ is the power distribution coefficient; n D x represents the additive white Gaussian noise at the receiving antenna of the destination node; rj Indicates the selected antenna R at the relay location. j Interference signals were sent.

[0113] Antenna R j As the optimal jamming antenna, since the optimal power splitting factor is significantly affected by the channel and other coefficients, this disclosure selects the antenna based on the optimal jamming antenna selection (OJAS) strategy using the Q-learning algorithm to enhance adaptability to the channel environment. This strengthens the system's security performance and addresses the uncertainty of transmission environment changes. The Q-learning algorithm is an algorithm where an agent analyzes the reward obtained from each action in the current state to adopt a strategy. It includes two processes: dynamic iterative update and behavioral decision-making. This disclosure defines the state space H, action space A, reward function r, and Q-value function Q(S) in the training of a multi-antenna relay system. t A t The parameters are defined as follows:

[0114] (1) State space (H): Key factors affecting the system's security performance mainly include the selection of the infecting antenna and its corresponding interference power. Furthermore, due to R... i ≠R jTherefore, one antenna needs to be selected from the (K-1) antennas configured at the relay node for cooperative communication, and each antenna on the relay node represents a state. Thus, the state space of the system is defined geometrically as H = H(R). j )={H1,H2,...,H K-1}

[0115] (2) Action space (A): According to the state space, when in a given state S t During the interactive learning process with the environment, there are three possible actions: maintaining the original state A0, moving to the next new state (A0), etc. + ) and move to the previous old state (A) - Therefore, the action space can be represented as: A = {A0, A...} + A -}

[0116] (3) The reward function (r) is used to select an interfering antenna to weaken the quality of the eavesdropping channel and enhance the mutual information of the legitimate channel. In other words, the optimal antenna selection aims to improve the system's security performance. Therefore, this disclosure sets the reward function r to the signal transmission security capacity. At this point, the end-to-end channel capacity is used, combined with maximum ratio combining (MRC) technology, to calculate the maximum amount of information the eavesdropper can obtain. Therefore, the reward function r can be expressed as:

[0117] Where, γ D This indicates the received signal-to-interference-plus-noise ratio (SIR) at the destination node.

[0118] (4) Q-value function Q(S) t A t The state-action value function is defined as the Q-value, representing the expected value of the discounted reward function obtained by executing the policy in the current state. The Q-value function is updated by combining the Bellman criterion and according to the formula... Perform iterations.

[0119] Here, φ∈(0,1] represents the learning rate that controls the convergence speed, and λ∈(0,1] represents the discount factor that controls the proportion of historical reward values ​​in the current reward. All actions taken and the Q-values ​​generated after receiving the reward function are recorded in the Q-table, and it needs to be initialized to zero before the data training begins.

[0120] Therefore, the target node is regarded as an agent in reinforcement learning. The target node adopts an ε-greedy policy to select actions from the currently given S. t Choose a state A from the options. tIt learns by interacting with the environment, and the environment then receives r and the next state S from the learning results. t+1 Then, the Q-table is updated using the obtained reward values. During the interactive learning process, actions need to be continuously selected and reward values ​​received, and then the Q-table updated. Through step-by-step training and updates, the Q-table eventually converges, and the state corresponding to the maximum accumulated reward value in the table is the antenna index number selected for cooperative communication in this model. The specific training process of the Q-learning algorithm is shown in Table 1.

[0121] Table 1: Optimal Interference Antenna Selection Algorithm Based on Q-learning

[0122]

[0123]

[0124] Step S103 includes the following steps:

[0125] Step S1031: Based on the communication results of the first and second stages of wireless power-carrying communication, derive the signal-to-dryness ratio (SINR) and its probability density function and cumulative distribution function for the signals received by different nodes. Specifically, in this example, for the first stage of wireless power-carrying communication:

[0126] Based on formula (1), the formulas for the cumulative distribution function and probability density function of the channel from source node S to relay node R are derived as follows:

[0127] and

[0128]

[0129] Among them, F X (x) represents the cumulative distribution function; f X (x) represents the probability density function; X represents the random variable; K represents the number of antennas; The rate parameter represents the exponential distribution of the channel between the i-th transmission antenna of the source node S and the relay node R.

[0130] The optimal legal signal transmission antenna R is derived from formula (2). i The received signal-to-interference-plus-noise ratio (SINR) is given by the formula:

[0131]

[0132] For the eavesdropping node E i The formula for the received signal includes:

[0133]

[0134] The formula for the SINR of the signal received by the most dangerous eavesdropping node includes:

[0135]

[0136] Among them, P S This represents the power of the signal transmitted by the source node S; Represents the source node S and any eavesdropping node E i Small-scale decay between intervals; Represents the source node S and any eavesdropping node E i Average channel gain between; P D This indicates the power of the friendly interference signal transmitted by the destination node D; Represents the destination point D and any eavesdropping node E. i Small-scale decay between intervals; This represents the destination node D and any eavesdropping node E. i The average channel gain between; N0 represents the magnitude of the additive white Gaussian noise at the i-th transmission antenna; i represents the index of the eavesdropping node; Φ E This represents the set of eavesdropping nodes; the superscript (1) indicates the first stage of the eavesdropping attack.

[0137] When all the total energy collected in the first stage is used for signal transmission in the second stage, the formula for the total power used for relay node amplification, forwarding, and transmission of cooperative interference signals includes:

[0138]

[0139] According to formulas (5) and (6), when the destination node D and the relay node R interfere with each other's transmitted interference signals x dj and x rj Known a priori, and based on the principle of channel reciprocity... Formula (5) simplifies to:

[0140]

[0141] Therefore, the formula for obtaining the SINR of the received signal at destination node D includes:

[0142]

[0143] Similarly, for the most dangerous eavesdropping node E i The formulas for the received signal and its SINR are as follows:

[0144]

[0145]

[0146] Wherein, the superscript (2) indicates the second stage of the eavesdropping attack; ρ represents the power splitting factor; P S P represents the power of the signal transmitted by the source node S; R This indicates the power of the relay node in amplifying and forwarding the signal; This represents the small-scale fading between the i-th transmission antenna of the source node S and the relay node R; This indicates that the i-th transmission antenna of relay node R is connected to any eavesdropping node E. i Small-scale decay between intervals; This represents the average channel gain between the i-th transmission antenna of the source node S and the relay node R; This indicates that the i-th transmission antenna of relay node R is connected to any eavesdropping node E. i Average channel gain between; S n and T n The substitution symbol is used in Formula 17 below.

[0147] in,

[0148] Step S1032: Based on the calculation results of step S1031, the ergodic secrecy rate is derived. This disclosure analyzes system performance and, based on the concept of ergodic secrecy capacity (ESC), which is the maximum transmission rate achievable by a legitimate user while ensuring that an eavesdropper cannot obtain confidential information, the ergodic secrecy rate is defined as the lower limit of the ergodic secrecy capacity. Therefore, the formula for the ergodic secrecy rate proposed in this disclosure includes:

[0149]

[0150] in, and These represent the legal channel capacity and the eavesdropping channel capacity, respectively; (a) represents the code for the operation step, specifically using the inequality. To perform the calculations, formula (18) includes:

[0151]

[0152] in, This indicates the achievable confidentiality rate during traversal; Represents the expectation operation; C S Indicates the capacity of the secure channel.

[0153] Under the OAS and OJAS strategies, the formulas for calculating the achievable security rate include:

[0154]

[0155]

[0156] in,

[0157] λ S =P S / N0,λ D =P D / N0;

[0158]

[0159] in, λ represents the cumulative distribution function of the received signal-to-interference-plus-noise ratio at the eavesdropping node. S Indicates the signal-to-noise ratio transmitted by the source node;

[0160] The specific process of solving the expressions for I1 and I2 is as follows:

[0161]

[0162]

[0163] in, It means "equivalent to".

[0164] Based on the properties of logarithmic functions, M and N represent the numerator and denominator of the received signal SINR at the destination node, respectively. In step (b), utilizing the monotonicity of functions In(x) and exp(x), and considering that In(1 / x) (x>0) is a convex function, according to Jensen's inequality, the inequality is... Established, thus enabling further calculations and get:

[0165]

[0166] Where Φ≈0.577215 represents the Euler constant.

[0167] Calculate I2, which can be obtained from the SINR of the signals received by the eavesdropping nodes in the first and second stages.

[0168]

[0169]

[0170] Then we get:

[0171]

[0172] get:

[0173]

[0174] To simplify the analysis and solution process, and considering high signal-to-noise ratio scenarios, inequalities are used... Approximating the signal-to-interference-plus-noise ratio (SIR) received by the eavesdropping node, we obtain:

[0175]

[0176] The cumulative distribution function of the received signal-to-interference-plus-noise ratio at the eavesdropping node can be expressed as:

[0177]

[0178] Then, the expressions for I3 and I4 are calculated respectively, where Where Ei(·) represents the exponential integral function, specifically defined as

[0179] Then we can obtain the single integral form of the formula after asymptotic analysis of the traversal achievable security rate.

[0180] In summary, this disclosure presents a wireless power-carrying communication method based on a multi-antenna relay system. This paper considers a scenario with multiple eavesdroppers randomly distributed and studies the security performance of the power-carrying network when using the PS power harvesting protocol. Based on this, an approximate expression for the system ergonomic achievable security rate of the proposed scheme is obtained through theoretical analysis. The variation law of this security index with relevant important parameters is obtained, thereby enhancing the physical layer security performance of the multi-antenna relay system.

[0181] This disclosure presents numerical analysis and simulation experiments on the security performance of the multi-antenna relay system for wireless power-carrying communication, and compares it with Scheme 1 and Scheme 2. Scheme 1 is the MRNCJ scheme (multiple relay non-cooperative jamming), which uses multiple relays to achieve secure transmission through non-cooperative jamming; Scheme 2 is the DSCJ scheme (destination-assisted single-stage cooperative jamming), which is secure transmission through single-stage cooperative jamming assisted by the destination node.

[0182] Simulation parameter settings

[0183] The simulations disclosed herein employ the Monte Carlo method, and all simulation results are 10. 6 The results are obtained by averaging the values ​​from multiple simulations. Specific simulation parameters are shown in Table 2. Unless otherwise specified, the parameter values ​​given in Table 2 will be used in the simulations thereafter.

[0184] Table 2: Simulation Parameters

[0185]

[0186] Results Analysis

[0187] By comparing the security performance of the relay system with that of Schemes 1 and 2 under different parameters, as shown in the appendix, the following parameters are obtained. Figure 4 As shown in Figure (1), three different schemes were compared. On the one hand, under low signal-to-noise ratio (SNR) conditions, the DSCJ scheme performed relatively better in the SNR range of approximately 10dB to 25dB. It is worth noting that the confidentiality rate of the MRNCJ scheme has an upper limit. As the SNR increases, the improvement trend of the system security performance of Scheme 1 gradually slows down. This is mainly because, for the MRNCJ scheme, when the transmit SNR increases, the SINR of the eavesdropping node for receiving the confidential signal also increases; when the SINR of the source node's transmitted signal exceeds a certain threshold, the rate of change of its confidentiality rate approaches 0. The schemes proposed in this disclosure and Scheme 2, which use cooperative interference signals for assistance, also have better confidentiality performance. This shows that the cooperative interference scheme plays a very important role in the confidential transmission of system information. (2) In all three schemes, the ergonomically achievable secure rate of the system steadily increases. At an ergonomically achievable secure rate of 4 bits / s / Hz, the scheme proposed in this disclosure achieves a gain of approximately 9.4 dB. This is because, with the increase in transmit SNR, the relay node can collect sufficient energy for secure transmission. In particular, as the transmit SNR continues to increase, the scheme proposed in this disclosure achieves an even higher ergonomically achievable secure rate. This is due to the use of cooperative interference, which affects both stages of the relay node's transmission. Therefore, the scheme proposed in this disclosure exhibits the best security performance under high transmit SNR conditions compared to schemes 1 and 2. Furthermore, under the same transmit SNR constraint, when the legitimate signal transmit SNR is higher than 40 dB, the theoretical values ​​of the scheme proposed in this disclosure and the DSCJ scheme are in better agreement with the simulation results, demonstrating that the given ergonomically achievable secure rate expression closely approximates the performance of the exact analytical expression.

[0188] See attached document Figure 5 , attached Figure 5This paper compares the ergonomically achievable secure rate of a system under three different schemes, showing the variation with energy conversion efficiency. Simulation results demonstrate that, under the same transmit signal-to-noise ratio (SNR) constraint, the ergonomically achievable secure rate of the system exhibits a monotonically increasing trend with increasing energy conversion efficiency in all three schemes. Furthermore, the scheme proposed in this disclosure outperforms the other two schemes for different energy conversion efficiencies. This is because a larger η value allows the relay node to collect more energy. Under the same splitting factor, a smaller EH module burden allows the relay node to allocate more power to transmitting secure signals. The rate of change of the ergonomically achievable secure rate indicates that the scheme proposed in this disclosure has higher energy security efficiency. Additionally, when the energy conversion efficiency is less than 0.6, increasing the energy conversion efficiency is more effective than increasing the transmit SNR; when the energy conversion efficiency is in the range of 0.6–0.9, the ergonomically achievable secure rate can be improved by continuously increasing the transmit SNR. The scheme proposed in this disclosure provides different ideas and methods for improving the security performance of the system.

[0189] See attached document Figure 6 , attached Figure 6 A comparison is presented of the ergonomically achievable security rate as a function of the signal power splitting factor under three different schemes. (See attached diagram.) Figure 5 As shown, when the power splitting factor approaches 1, the ergonomically achievable security rate of the system first increases and then decreases, and the ergonomically achievable security performance of the system rapidly improves from 0.1 to around 0.4. This is mainly because when the power splitting factor increases within a certain range, the IT module receives more energy, which is used to increase the transmission power of the relay node, thereby improving the reception of the secure signal at the destination node. Simultaneously, in the second stage, the signal-to-interference-plus-noise ratio (SNR) received by the eavesdropping node gradually decreases, thus improving the ergonomically achievable security rate. Furthermore, when the power splitting factor exceeds the optimal value, the ergonomically achievable security rate gradually decreases. This is because the energy used by the relay node for information reception gradually decreases in this stage, and the received signal strength gradually weakens. At this point, the poor signal strength has a negative impact on the ergonomically achievable security rate, so even though the transmission power P... R While the signal-to-interference-plus-noise ratio (SNR) increases, the end-to-end SNR of communication actually decreases. At the optimal splitting factor, the signal strength of relay node R for information transmission and energy harvesting tasks can be effectively balanced, maximizing system security. Furthermore, at the source node transmit ratio λ... S With the same power splitting factor ρ, increasing the power allocation coefficient θ can improve the ergodic achievable security rate of the system. This is because the power used to transmit friendly interference signals increases, thus improving security performance. Furthermore, it can be seen that although increasing λ... SThe system could have achieved an increased traversal reachable security rate, but in reality, the traversal reachable security rate is decreasing. This indicates that finding the optimal system parameters is crucial for achieving secure transmission while conserving energy resources.

[0190] Appendix Figure 7 This paper compares the changes in system security performance of the proposed scheme under different combinations with random antenna selection (RAS) and random jamming antenna selection (RJAS) strategies, with varying numbers of antennas configured at relay nodes. The proposed scheme includes optimal antenna selection (OAS) and optimal jamming antenna selection (OJAS) strategies. It can be seen that under all four combinations, the ergonomically achievable security rate increases with the number of antennas, and the security performance is significantly enhanced when the number of antennas is between 5 and 15. This is because as the number of antennas increases, the probability of encountering a more favorable environment for transmitting secure information increases, thus continuously improving the ergonomically achievable security rate. Furthermore, when the number of antennas is 15, compared to the combination of OAS and RJAS strategies, and the combination of RAS and OJAS strategies, the OAS and OJAS strategy combination in the proposed scheme increases the ergonomically achievable secure rate by 1.19 bit / s / Hz and 0.72 bit / s / Hz, respectively. This is because the OAS strategy increases the capacity of the legitimate channel, and combined with the friendly interference scheme, reduces the quality of the eavesdropping channel, ultimately increasing the ergonomically achievable secure rate. Moreover, the OAS and OJAS strategies in the proposed scheme can increase the ergonomically achievable secure rate by approximately 1.59 bit / s / Hz and 1.1 bit / s / Hz, respectively, demonstrating the performance advantage of the proposed scheme.

[0191] Appendix Figure 8 This study considers the variation of the achievable security rate with the coordinates of the relay node and the eavesdropping node in a scenario where the eavesdropping node is determined. The relevant parameters are set as follows: the relay node's coordinates are located at (x...). R At position 3), the eavesdropping node is located at (x E At position -3), the transmit signal-to-interference-plus-noise ratio λ S=50dB. It can be seen that, firstly, when the relay node is close to the destination node and the eavesdropping node is close to the source node, the traversal achievable security rate approaches 0, at which point the possibility of information leakage is greatest. This is because, in the first stage of energy-carrying communication, the greater the distance from the source node to the relay node, the smaller the distance from the eavesdropping node to the source node. At this time, the signal-to-interference-plus-noise ratio (SNR) of the legitimate signal dominates compared to the SNR of the friendly interference signal sent by the destination node. In the second stage of energy-carrying communication, because the distance between the relay node and the eavesdropping node is greater, and the interference signal sent by the relay node is less effective, the system's security performance decreases, and the probability of successful eavesdropping increases. Secondly, when both the relay node and the eavesdropping node are close to the destination node, the corresponding traversal achievable security rate reaches 6.96 bits / s / Hz, at which point the system's security performance is best. This is because, in the first stage of energy-carrying communication, the eavesdropping node, being close to the destination node, experiences the best interference effect from friendly interference signals, resulting in a reduced SINR for the eavesdropping node. In the second stage, because the distance between the eavesdropping node and the relay node is minimal, the interference signal emitted by the relay node has the greatest effect. Furthermore, as the relay node moves further away from the source node, path loss becomes more severe, and the strength of legitimate signals gradually weakens. Therefore, the system's security performance is optimal at this stage. Finally, from the appendix... Figure 8 It can be seen that there exists a region where the EASR is approximately 0. In the proposed scheme, properly setting the location of the relay node will help improve the system's security performance. Simulation experiments show that when the eavesdropping node approaches the source node, the relay node should be located near the source node; when the eavesdropping node approaches the destination node, the relay node should be located near the destination node.

[0192] Simulation results verify the correctness of the theoretical analysis, showing that the proposed scheme can effectively enhance the system's security performance. Furthermore, the proposed scheme can balance system security performance and information transmission by seeking the optimal power splitting factor. In addition, properly setting the location of relay nodes can also significantly improve the traversal achievable security rate.

[0193] It should be noted that although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted. Furthermore, it is readily understood that these steps may be performed synchronously or asynchronously, for example, across multiple modules / processes / threads.

[0194] It should be noted that although several units of the system for executing actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units. Some or all of the units can be selected to achieve the purpose of this disclosure according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

[0195] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A wireless power-carrying communication method based on a multi-antenna relay system, characterized in that, Includes the following steps: Establish a model of a multi-antenna relay system; this multi-antenna relay system includes a source node, a destination node, a relay node, and several eavesdropping nodes. The relay node is equipped with K Each node has one antenna, while all other nodes are equipped with only a single antenna. The multi-antenna relay system performs wireless power-carrying communication based on the PS protocol; Within a communication cycle, there are two phases with equal time slots. The first stage includes the following processes: Source node S With power To relay node R Sending radio frequency signals carrying energy , destination node D With power To the relay node R Transmit a friendly jamming signal carrying energy. The relay node R According to the PS protocol, use one antenna. The system receives both types of energy-carrying signals and divides the received signals into two parts according to a power splitting structure: one part is the EH module used for energy acquisition, and the other part is the IT module used for signal transmission. The second phase includes the following processes: The relay node R The energy collected by the EH module is used to amplify and forward the signal from the IT module to the destination node. D Meanwhile, the relay node R Using another antenna They emitted coordinated jamming signals to continue interfering with the eavesdroppers; Based on the results of wireless energy-carrying communication, the secure rate achievable through traversal is derived, thereby measuring the secure transmission performance gain of the multi-antenna relay system. The proportion of signals entering the EH module is: The proportion of signals entering the IT module is ,in, Power splitting factor, ; The antenna The formula for the optimal legal signal transmission antenna includes: （1） in, K Indicates the number of antennas; This represents the channel capacity of the optimal legal signal; Indicates the power splitting factor; Indicates the power distribution factor; This represents the energy collected by the relay node; This indicates the power of the relay node in amplifying and forwarding the signal; T Indicates the communication cycle; i The index indicating the antenna number. ; Indicates the received signal-to-interference-plus-noise ratio at the destination node; The optimal legal signal transmission antenna The formula for the received signal includes: （2） in, Indicates the source node S The power of the transmitted signal; Indicates the source node S and relay nodes R The i Small-scale fading between root transmission antennas; Indicates the source node S and relay nodes R The i Average channel gain between root transmission antennas; Indicates radio frequency signal; Indicates the destination node D The power at which friendly interference signals are transmitted; Indicates the destination node D and relay nodes R The i Small-scale fading between root transmission antennas; Indicates the destination node D and relay nodes R The i Average channel gain between root transmission antennas; This indicates a friendly interference signal; Indicates the first i Additive white Gaussian noise at the root transmission antenna; In the first phase, relay nodes R The formulas for energy harvesting include: （3） in, Indicates energy conversion efficiency. ; N 0 indicates the first i The magnitude of additive white Gaussian noise at the root transmission antenna; relay node R The formulas for signal transmission include: （4） The superscript IT indicates the information transmission IT module; The antenna As the optimal antenna for transmitting interference signals, this antenna... Q - Obtained by the learning algorithm; In the second phase, the relay node R The energy collected in the first stage is used through the antenna For signal Amplify and relay the signal, and transmit it via antenna. Transmit cooperative jamming signals The transmitted signal is denoted as: ,in, G The magnification factor is the value of the amplification factor. G The formulas include: （5） Obtain the target node D The formula for the received signal includes: （6） in, and Let the power of the relay node amplifying and forwarding the signal and the power of the transmitted cooperative interference signal be represented respectively, and the total power be obtained. ,make ,but , θ Power allocation factor; This represents additive white Gaussian noise at the receiving antenna of the destination node; Indicates the antenna selection at the relay location. Interference signals were sent.

2. The wireless power-carrying communication method according to claim 1, characterized in that, In the step of establishing the multi-antenna relay system model, all nodes operate in half-duplex mode; when the multi-antenna relay system transmits signals, the internal interference between all antennas can be completely self-cancelled; all eavesdropping nodes can eavesdrop on the confidential signals transmitted by the multi-antenna relay system at each stage of wireless power-carrying communication; the location distribution of the eavesdropping nodes follows an independent Poisson process; there is only one source node, one destination node, and one relay node.

3. The wireless power-carrying communication method according to claim 1, characterized in that, The process of deriving the achievable secure rate and analyzing the secure transmission performance gain of the system includes the following steps: Based on the communication results of the first and second stages of wireless power-carrying communication, the signal-to-interference-plus-noise ratio (SINR) of the received signals at different nodes, as well as its probability density function and cumulative distribution function, are derived.

4. The wireless power-carrying communication method according to claim 3, characterized in that, For the first phase of wireless power-carrying communication: The source node is derived from formula (1). S To relay node R The formulas for the cumulative distribution function and probability density function corresponding to the channel are as follows: (7) and （8） in, Represents the cumulative distribution function; Represents the probability density function; X Represents a random variable; K Indicates the number of antennas; Indicates the source node S and relay nodes R The i The rate parameter of the channel between the root transmission antennas follows an exponential distribution; The optimal legal signal transmission antenna is derived from formula (2). The received signal dryness ratio (SINR) is given by a formula comprising: （9）； For eavesdropping nodes The formula for the received signal includes: （10）； The formula for the SINR of the signal received by the most dangerous eavesdropping node includes: （11） in, Indicates the source node S The power of the transmitted signal; Indicates the source node S and arbitrary eavesdropping nodes Small-scale decay between intervals; Indicates the source node S and arbitrary eavesdropping nodes Average channel gain between; Indicates the destination node D The power at which friendly interference signals are transmitted; Indicates the destination point D and arbitrary eavesdropping nodes Small-scale decay between intervals; Indicates the destination node D and arbitrary eavesdropping nodes Average channel gain between; N 0 indicates the first i The magnitude of additive white Gaussian noise at the root transmission antenna; This represents the set of eavesdropping nodes; the superscript (1) indicates the first stage of the eavesdropping attack; When all the total energy collected in the first stage is used for signal transmission in the second stage, the formula for the total power used for relay node amplification, forwarding, and transmission of cooperative interference signals includes: （12）。 5. The wireless power-carrying communication method according to claim 4, characterized in that, For the second phase of wireless power-carrying communication: According to formulas (5) and (6), when the destination node D and relay nodes R Interference signals transmitted by each and Known a priori, and based on the principle of channel reciprocity... Formula (5) simplifies to: （13）； Obtain the target node D Formula for SINR of the received signal include: （14）； For the most dangerous eavesdropping nodes The formulas for the received signal and its SINR are as follows: (15) and （16） The superscript (2) indicates the second stage of the eavesdropping attack; Indicates the power splitting factor; Indicates the source node S The power of the transmitted signal; This indicates the power of the relay node in amplifying and forwarding the signal; Indicates the source node S and relay nodes R The i Small-scale fading between root transmission antennas; Represents relay node R The i Root transmission antenna and arbitrary eavesdropping node Small-scale decay between intervals; Indicates the source node S and relay nodes R The i Average channel gain between root transmission antennas; Represents relay node R The i Root transmission antenna and arbitrary eavesdropping node Average channel gain between; and Indicates formula substitution symbols; in, (17).

6. The wireless power-carrying communication method according to claim 5, characterized in that, The formula for achieving a secure traversal rate includes: （18） in, and These represent the legal channel capacity and the eavesdropping channel capacity, respectively; a () represents the code for the operation step, specifically using inequalities. To perform the calculations, formula (18) includes: （19）； Given the optimal legal signal transmission antenna and optimal interference signal antenna The formula for calculating the achievable security rate through traversal includes: （20） in, , , ; in, This indicates the achievable confidentiality rate during traversal; This represents the expectation operation; Indicates the capacity of the secure channel; The cumulative distribution function representing the received signal-to-interference-plus-noise ratio at the eavesdropping node; This represents the signal-to-noise ratio transmitted by the source node.

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