A method, system and terminal for analyzing security transmission performance of multi-hop cognitive relay

Abstract

The application belongs to the technical field of radio communication, and discloses a secret transmission performance analysis method, system and terminal of multi-hop cognitive relay, a bottom multi-hop cognitive network model based on cooperation of PUs and SUs is constructed, an auxiliary relay node realizes communication between an auxiliary source node S and a destination node D by collecting radio frequency energy of a PU-Tx, and S and the auxiliary relay node control transmission power of themselves; an artificial scrambling signal is set for the last-hop relay node to cause interference to a passive eavesdropper E; expressions of a secret outage probability SOP, a secret throughput SC and an energy efficiency EE of the system are derived and calculated to realize performance analysis of the system model. The application analyzes performance of secret transmission of a secondary user realized by multi-hop EH relay cooperation assistance under a bottom mode, the last-hop relay node simultaneously sends an interference signal and an actual transmission signal, thereby reducing a capacity of eavesdropping, and extending a communication link in a horizontal direction to provide reliable guarantee for long-distance communication.

Description

Technical Field

[0001] This invention belongs to the field of radio communication technology, and in particular relates to a method, system and terminal for analyzing the secure transmission performance of multi-hop cognitive relay. Background Technology

[0002] Due to the rapid development of the 5G industry in recent years, a large number of mobile devices need to access communication networks, but available spectrum resources are limited, and the shortage of spectrum resources is becoming increasingly serious. Cognitive radio technology is considered an effective means to improve the utilization of wireless spectrum. At present, there are three main communication modes: bottom layer mode, coverage mode, and interleaving mode. In military communication networks, primary users (PUs) and secondary users (SUs) usually need to share the same licensed frequency band for cooperative communication. Therefore, this type of research is mainly conducted in the bottom layer mode and coverage mode.

[0003] In low-level mode, when a new primary user (PU) appears on the frequency band where a secondary user (SU) is operating, the SU does not need to immediately switch spectrum, but must adjust its transmit power to keep it below the maximum interference threshold acceptable to the primary user (PU). This limits the SU's performance, and this limited SU transmit power may reduce network coverage.

[0004] Due to the complexity of the battlefield environment, direct communication between secondary users is often unsatisfactory due to various environmental factors. Therefore, many research works have added relay nodes to secondary user communication, including fixed ground relays and mobile airborne unmanned aerial vehicle (UAV) relays. These relay nodes improve the robustness and stability of the communication link. Existing technologies, such as "Li, E., Ma, L., & Hao, S. Security and Reliability Analysis of Relay Selection in Cognitive Relay Networks[J]. Wireless Personal Communications, 2022, 123: 3103-3125." and "Ye, J., Liu, Z., Zhao, H., Pan, G., Ni, Q., & Alouini, M. Relay selections for secondary underlay CR systems with energy harvesting[J]. IEEE Transactions on Cognitive Communications and Networking, 2019, 5(2): 3583-369.", mention that suitable relays can be selected from a set containing multiple relay nodes to transmit data simultaneously, preventing communication interruption due to the failure of a single relay node. The above research only adds one relay node to the communication link, forming a two-hop communication link. Even with multiple relay nodes available, the improvement is only in the vertical direction. However, as the number of relay nodes increases, the overall energy consumption of the link also increases, leading to insufficient energy supply. Therefore, energy harvesting (EH) technology has been proposed in existing technologies. This allows relay nodes to harvest wind and solar energy from the natural environment, or radio frequency signal energy from the radio frequency environment and store it in their equipped batteries for further processing of received signals. Typically, the signal processing technologies used by relay nodes mainly include decoding and forwarding (DF) and amplifying and forwarding (AF). DF is mainly suitable for high signal-to-noise ratio (SNR) environments; AF is suitable for low signal-to-noise ratio (SNR) environments. This technology can amplify severely fading signals, but it also amplifies noise, causing interference.Two energy harvesting strategies for obtaining energy from radio frequency sources were proposed in the existing technology “Liu,Y.,Mousavifar,SA,Deng,Y.,Leung,C.,&Elkashlan,M.Wireless Energy Harvesting in a Cognitive Relay Network.IEEE Transactions on Wireless Communications,2016,15(4):249-250.”: a time-switching strategy and a power-splitting strategy.

[0005] Due to the problem of unauthorized users eavesdropping on legitimate users' communication data in the communication environment, the current approach no longer uses keys and complex algorithms to prevent passive eavesdropping. Instead, physical layer technology is adopted to utilize the physical characteristics of wireless channels to maintain the security of confidential information. In existing technologies, the probability of confidentiality interruption is used as an indicator to measure the confidentiality performance of the system, maintaining the communication security of legitimate users under the condition of achieving a predetermined data transmission rate. The existing technology "Goel, S., Negi, R. Guaranteeing secrecy using artificial noise[J].IEEE transmissionwireless communication,2008,7(6):2180-2189." also proposes adding artificial scrambling signals during signal transmission. Since legitimate users know the prior information of the artificial scrambling signals, they can easily eliminate interference when receiving a mixed signal of real and scrambling signals. However, passive eavesdroppers cannot accurately identify the interference, thereby reducing the signal-to-noise ratio at the eavesdropper's location and further enhancing the confidentiality of the communication link.

[0006] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0007] Existing technologies aim to add a relay node to the subsystem to form a two-hop relay link, resulting in limited transmission distance of the entire link, restricted horizontal transmission, small coverage area, and inability to achieve reliable long-distance communication between sub-users. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method, system, and terminal for secure transmission performance analysis of multi-hop cognitive relays, and particularly relates to a method, system, medium, device, and terminal for secure transmission performance analysis of multi-hop cognitive relays based on energy harvesting and artificial scrambling.

[0009] This invention is implemented as follows: a method for analyzing the secure transmission performance of multi-hop cognitive relays. The method includes: constructing a low-level multi-hop cognitive network model based on PU and SU cooperation; enabling auxiliary relay nodes to communicate between auxiliary source node S and destination node D by collecting RF energy from PU-Tx; simultaneously, S and the auxiliary relay nodes should control their transmission power below the interference threshold of PU-Rx; adding an artificial scrambling signal to the last-hop relay node to reduce the signal-to-noise ratio at the passive eavesdropper E to prevent eavesdropping on secure signals; deriving and calculating the system's secure interruption probability SOP, secure throughput SC, and energy efficiency EE expressions to achieve performance analysis.

[0010] Furthermore, the method for analyzing the secure transmission performance of multi-hop cognitive relay includes the following steps:

[0011] Step 1, System Model Construction: Construct the network model and the transmission model respectively;

[0012] Step 2, Performance Analysis: Analyze the probability of security interruption, security throughput, and energy efficiency respectively.

[0013] Furthermore, the construction of the network model in step one includes:

[0014] A decoding and forwarding model for secure communication is constructed, assisted by n cognitive relays (SUs). The system model includes two networks: SU and PU. The SU network consists of a source node S, a legitimate destination node D, and n relays R. i (1≤i≤n); The PU network includes a primary user transmitter PU-Tx and a primary user receiver PU-Rx; an illegal eavesdropper E exists near the destination node. Assume each node is configured with a single antenna and operates in half-duplex mode, with n auxiliary relays R... i Energy is harvested from the PU-Tx radio frequency environment for decoding and forwarding. To reduce the quality of the eavesdropping channel, the nth relay node R... n Artificial scrambling is sent to E. Since the destination node has prior information about the scrambled signal, the scrambled signal can be eliminated at the legitimate destination node, allowing the destination node to receive information normally. Because the distance between the source node S and the destination node D is relatively large, E cannot eavesdrop on the signals transmitted between all nodes before the nth auxiliary relay.

[0015] Furthermore, the construction of the transmission model in step one includes:

[0016] Assume all channels follow Rayleigh fading, and the channel coefficients are h. ij ,i∈{S,R i (1≤i≤n)}j∈{R i (1≤i≤n),D,E},h ij~CN(0,σ ij 2 The channel gain is g. ij =h ij 2 g ij Follows the mean λ ij The exponential distribution of g ij ~exp(λ ij All relay nodes perform energy harvesting and EH according to the time switching strategy; when the total information transmission time is T, the entire communication process is divided into two time slots. The first time slot is the EH phase of n auxiliary relays, which lasts for αT (0 < α < 1), and α is called the time allocation factor.

[0017] The expression for the energy collected by the EH-assisted relay is:

[0018]

[0019] Among them, P T η is the transmission power of PU-Tx, and η is the energy harvesting factor. It is PU-Tx and R i Channel gain.

[0020] The second time slot is the stage where n auxiliary relays transmit the signal from S to D and E. The transmission time for each relay is fixed and the same. Therefore, the transmission duration for each relay node is... In the second time slot, the signal received by relay node R1 is:

[0021]

[0022] Among them, P s It is the transmission power of S. x is the channel gain of S and R1. s The signal emitted by S is n1, which is additive white Gaussian noise n1~CN(0,σ) 2 ).

[0023] Similarly, R i The received signal (1<i≤n) is:

[0024]

[0025] Among them, P i-1 It is R i-1 The transmission power h of (1<i≤n) i-1,i It is R i-1 With R i The channel gain, n i It is additive white Gaussian noise, n i ~CN(0,σ 2).

[0026] Since the system operates in low-level mode, the transmission power of each auxiliary relay node is within the PU-Rx interference threshold I. th Under the constraint that the transmission power of the nth relay node is P n Then ξP n Used to transmit real signals, (1-ξ)P n The signal ξ, used for transmitting artificially scrambled signals, is called the power allocation factor. The signal received by D is:

[0027]

[0028] Where, x n It is R n The transmitted signal, h n,D It is R n The channel gain up to D, where x0 is the artificially scrambled signal.

[0029] The signal received by E is:

[0030]

[0031] Where, x n It is R n The transmitted signal, h n,E It is R n The channel gain up to E, where x0 is the artificially scrambled signal.

[0032] Furthermore, the probability analysis of security breach in step two includes:

[0033] Throughout the communication process, the condition for the relay to successfully decode the source information is the channel capacity C of the relay link. i,j Exceeding the target data rate R s Assume that the target data rate of each node in the communication system is the same, which is R. s Due to the channel gain g ij Follows the mean λ ij The exponential distribution of g, therefore g ij The probability density function is:

[0034]

[0035] The cumulative distribution function is:

[0036] F ij =1-exp(-λ ij x) (7)

[0037] Due to the power P of source node S s Due to the interference threshold limitation of PU-Rx, Relay node Ri Transmission power P i It is limited by EH and also by the interference threshold of PU-Rx;

[0038]

[0039] The first hop relay R1 successfully decoded x. s The probability is:

[0040]

[0041] Similarly, R i Successfully decoded x i-1 The probability is:

[0042]

[0043] in, f X (x) is g i-1,i The probability density function, f Y (y) is The probability density function.

[0044] D successfully decoded x n The channel capacity at that time is:

[0045]

[0046] E successfully decoded x n The channel capacity at that time is:

[0047]

[0048] Define the system's secure throughput as:

[0049]

[0050] in,[·] + = max[0,·].

[0051] Signal-to-noise ratio of the signal received at point D Signal-to-noise ratio of the signal received at point E The expressions are as follows:

[0052]

[0053]

[0054] The probability of secure transmission of D is defined as the channel capacity being greater than or equal to the predefined transmission rate R. s Then R is realized n The probability of achieving secure communication with D is:

[0055]

[0056] R n The derivation process of the probability of achieving secure communication to D is as follows:

[0057] 1 hour, Right now Then there is

[0058]

[0059]

[0060]

[0061] Due to channel gain g ij Follows the mean λ ij If it follows an exponential distribution, then and The probability density function (PDF) is divided into:

[0062]

[0063]

[0064] remember: a=(1-ξ)I th b=ξI th , but

[0065]

[0066] ②When hour, but

[0067]

[0068]

[0069]

[0070] In summary, R n The probability of achieving secure communication with D is:

[0071]

[0072] Based on the derivation of the interruption probability of each node, the system interruption probability is:

[0073]

[0074] Furthermore, the confidential throughput analysis in step two includes:

[0075] When the communication duration is T, the total duration for information transmission is (1-α)T. At a target data rate of R... s In this case, the probability of the system achieving secure transmission is (1-SOP), therefore, the confidential throughput of the system within time T is defined as:

[0076] SC=(1-SOP)(1-α)R S (28)

[0077] Furthermore, the energy efficiency analysis in step two includes:

[0078] If the transmission duration is T, then the total duration for information transmission is (1-α)T. At a target data rate of R... s In this case, the system's energy efficiency is expressed as:

[0079]

[0080] Another objective of this invention is to provide a secure transmission performance analysis system for multi-hop cognitive relay using the aforementioned secure transmission performance analysis method. The secure transmission performance analysis system for multi-hop cognitive relay includes:

[0081] The network model building module is used to build a low-level multi-hop cognitive network model based on the cooperation of PU and SU. The auxiliary relay node collects the radio frequency energy of PU-Tx, while S and the auxiliary relay node must control their own transmission power. In addition, an artificial scrambling signal is added to the last hop relay node to reduce the received signal-to-noise ratio at the passive eavesdropper E, so as to realize secure communication from the auxiliary source node S to the destination node D.

[0082] The system performance analysis module is used to derive and calculate the system's security interruption probability SOP, security throughput SC, and energy efficiency EE expression to achieve system performance analysis.

[0083] Another object of the present invention is to provide a computer device, the computer device including a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform the steps of the secure transmission performance analysis method for multi-hop cognitive relay.

[0084] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the secure transmission performance analysis method for multi-hop cognitive relay.

[0085] Another objective of this invention is to provide an information data processing terminal for implementing the secure transmission performance analysis system of the multi-hop cognitive relay.

[0086] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0087] First, addressing the technical problems existing in the prior art and the difficulty of solving them, this paper closely analyzes, in conjunction with the technical solution to be protected by this invention and the results and data obtained during the research and development process, how the technical solution of this invention solves the technical problems, and the inventive technical effects brought about by solving these problems. The specific description is as follows:

[0088] To address the current challenges of spectrum scarcity, energy shortages, and physical layer security, this invention proposes a low-level multi-hop cognitive network model based on PU and SU cooperation. The auxiliary relay node enables communication between the auxiliary source node S and the destination node D by collecting the radio frequency signal energy of the PU-Tx. Simultaneously, S and the auxiliary relay node should control their own transmission power to avoid interference to the PU-Rx exceeding a specified threshold. Furthermore, this invention adds an artificial scrambling signal to the last-hop relay node, causing some interference to the passive eavesdropper E, thereby enhancing the system's secure communication. This invention derives and calculates the system's secure interruption probability SOP, secure throughput SC, and energy efficiency EE expressions. Experimental simulation results demonstrate the effectiveness of the system and the correctness of the method.

[0089] Second, considering the technical solution as a whole or from a product perspective, the technical effects and advantages of the technical solution to be protected by this invention are specifically described as follows:

[0090] This invention primarily analyzes the performance of multi-hop EH relay collaborative assistance for secondary users to achieve secure transmission in the low-level mode. The last-hop relay node simultaneously transmits both interference and real transmission signals, thereby reducing the channel capacity at the eavesdropping point. Based on this, a new power allocation strategy is proposed for the last-hop relay node, achieving synchronous transmission of interference and real signals. This invention focuses on analyzing links with multi-hop relays, extending the communication link horizontally to provide reliable guarantees for long-distance communication.

[0091] Third, as supplementary evidence of the inventive step of the claims of this invention, it is also reflected in the following important aspects:

[0092] The commercial value of the technical solution of this invention after transformation and the expected benefits are as follows:

[0093] This invention utilizes cognitive radio technology to enable the PU and SU to share the same licensed spectrum, solving the problem of wireless spectrum shortage. It also extends the communication link length horizontally, enabling reliable long-distance transmission and expanding communication coverage. Equipped with an energy harvesting device to obtain energy from the natural environment or radio frequency signals in the radio frequency environment, it addresses the energy shortage problem and reduces costs. Furthermore, the technique of adding artificial scrambling signals effectively prevents passive eavesdroppers from intercepting confidential signals. Attached Figure Description

[0094] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0095] Figure 1 This is a flowchart of the secure transmission performance analysis method for multi-hop cognitive relay provided in this embodiment of the invention;

[0096] Figure 2 This is a schematic diagram of the system model provided in an embodiment of the present invention;

[0097] Figure 3 This is a schematic diagram of transmission time slot division provided in an embodiment of the present invention;

[0098] Figure 4 The embodiments of the present invention provide different α cases for R s Schematic diagram illustrating the impact on SOPs;

[0099] Figure 5 The embodiments of the present invention provide different α cases for R s Schematic diagram of the impact on SC;

[0100] Figure 6 The different I provided in the embodiments of the present invention th In the case of R s Schematic diagram illustrating the impact on SOPs;

[0101] Figure 7 The different I provided in the embodiments of the present invention th In the case of R s Schematic diagram of the impact on SC;

[0102] Figure 8 The embodiments of the present invention provide different α cases for R s Schematic diagram illustrating the impact on EE;

[0103] Figure 9 The different I provided in the embodiments of the present invention thIn the case of R s Schematic diagram illustrating the impact on EE;

[0104] Figure 10 This is a schematic diagram illustrating the impact of artificial scrambling on SOPs provided in an embodiment of the present invention;

[0105] Figure 11 This is a schematic diagram illustrating the effect of artificial scrambling on SC provided in an embodiment of the present invention. Detailed Implementation

[0106] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0107] To address the problems existing in the prior art, this invention provides a method, system, and terminal for analyzing the secure transmission performance of multi-hop cognitive relay. The invention will now be described in detail with reference to the accompanying drawings.

[0108] I. Explanatory and Illustrative Embodiments. To enable those skilled in the art to fully understand how the present invention is specifically implemented, this section provides an explanatory and illustrative description of the embodiments described in the claims.

[0109] like Figure 1 As shown, the secure transmission performance analysis method for multi-hop cognitive relay provided in this embodiment of the invention includes the following steps:

[0110] S101, construct a low-level multi-hop cognitive network model based on the cooperation between PU and SU, and enable the auxiliary relay node to communicate with the auxiliary source node S and the destination node D by collecting the radio frequency energy of PU-Tx;

[0111] S102, S controls its own transmission power with the auxiliary relay node; sets an artificial scrambling signal for the last hop relay node to interfere with the passive eavesdropper E;

[0112] S103 derives and calculates the system's security interruption probability SOP, security throughput SC, and energy efficiency EE expression to realize system model performance analysis.

[0113] As a preferred embodiment, the secure transmission performance analysis method for multi-hop cognitive relay provided by this invention specifically includes the following steps:

[0114] 1. System Model

[0115] 1.1 Network Model

[0116] This invention proposes a decoding and forwarding model assisted by n cognitive relays, with an eavesdropping channel present in the last hop. For example... Figure 2As shown, the system includes two networks. The SU network includes: one source node S, one valid destination node D, and n relays R. i The network consists of (1≤i≤n) nodes; the PU network includes: a primary user transmitter PU-Tx, a primary user receiver PU-Rx; and an illegal eavesdropping node E exists near the destination node. Assume each node is configured with a single antenna and operates in half-duplex mode, with n auxiliary relays R... i It can harvest energy from the PU-Tx radio frequency environment for its own decoding and forwarding (DF). To reduce the quality of the eavesdropping channel, the nth relay node R... n Artificial scrambling is sent to E. We assume that the destination node has prior information about the scrambling signal, so the scrambling signal can be eliminated at the legitimate destination node, allowing the destination node to receive information normally. Because the distance between the source node S and the destination node D is relatively large, E will not be able to eavesdrop on the signals transmitted between all nodes before the nth auxiliary relay.

[0117] 1.2 Transmission Model

[0118] Assume all channels follow Rayleigh fading, and the channel coefficients are h. ij ,i∈{S,R i (1≤i≤n)}j∈{R i (1≤i≤n),D,E},h ij ~CN(0,σ ij 2 The channel gain is g. ij =|h ij | 2 g ij Follows the mean λ ij The exponential distribution, i.e., g ij ~exp(λ ij All relay nodes are capable of energy harvesting (EH) and perform EH according to a time-switching strategy, such as... Figure 3 As shown, assuming the total time for information transmission is T, the entire communication process is divided into two time slots. The first time slot is the EH phase of n auxiliary relays, lasting for αT (0 < α < 1), where α is called the time allocation factor.

[0119] The expression for the energy collected by the EH-assisted relay is:

[0120]

[0121] Among them, P T η is the transmission power of PU-Tx, and η is the energy harvesting factor. It is PU-Tx and R i Channel gain.

[0122] The second time slot is the stage where n auxiliary relays transmit the signal from S to D and E. Assuming that the transmission time of each relay is fixed and the same, the transmission duration of each relay node is... In the second time slot, the signal received by relay node R1 is:

[0123]

[0124] Among them, P s It is the transmission power of S. x is the channel gain of S and R1. s The signal emitted by S is n0, which is additive white Gaussian noise n0~CN(0,σ) 2 ).

[0125] Similarly, R i The received signal (1<i≤n) is:

[0126]

[0127] Among them, P i-1 It is R i-1 The transmission power h of (1<i≤n) i-1,i It is R i-1 With R i The channel gain, n i It is additive white Gaussian noise, n i ~CN(0,σ 2 ).

[0128] Since the system operates in low-level mode, the transmission power of each auxiliary relay node should be within the PU-Rx interference threshold I. th Under the constraints, assume the transmission power of the nth relay node is P. n Then ξP n Used to transmit real signals, (1-ξ)P n The signal ξ, used to transmit artificially scrambled signals, is called the power allocation factor. The signal received by D is:

[0129]

[0130] Where, x n It is R n The transmitted signal, h n,D It is R n The channel gain up to D, where x0 is the artificially scrambled signal.

[0131] The signal received by E is:

[0132]

[0133] Where, xn It is R n The transmitted signal, h n,E It is R n The channel gain up to E, where x0 is the artificially scrambled signal.

[0134] 2. Performance Analysis

[0135] 2.1 Analysis of the probability of security breach

[0136] Throughout the communication process, the condition for the relay to successfully decode the source information is the channel capacity C of the relay link. i,j Exceeding the target data rate R s Assume that the target data rate of each node in the communication system is the same, R. s Due to the channel gain g ij Follows the mean λ ij The exponential distribution of has a probability density function as:

[0137]

[0138] The cumulative distribution function is:

[0139] F ij =1-exp(-λ ij x) (7)

[0140] Due to the power P of source node S s Limited by the interference threshold of PU-Rx, therefore Relay node R i Transmission power P i It is limited by EH and also by the interference threshold of PU-Rx;

[0141]

[0142] The first hop relay R1 successfully decoded x. s The probability is:

[0143]

[0144] Similarly, R i Successfully decoded x i-1 The probability is:

[0145]

[0146] in, f X (x) is g i-1,i The probability density function, f Y (y) is The probability density function.

[0147] D successfully decoded x n The channel capacity at that time is:

[0148]

[0149] E successfully decoded x n The channel capacity at that time is:

[0150]

[0151] Define the system's secure throughput as:

[0152]

[0153] in,[·] + = max[0,·].

[0154] Signal-to-noise ratio of the signal received at point D Signal-to-noise ratio of the signal received at point E The expressions are as follows:

[0155]

[0156]

[0157] The probability of secure transmission of D is defined as the channel capacity being greater than or equal to the predefined transmission rate R. s Then R is realized n The probability of achieving secure communication with D is:

[0158]

[0159] The following continues the derivation of R from (5). n The probability of achieving secure communication with D:

[0160] ① hour, Right now Then there is

[0161]

[0162]

[0163]

[0164] Due to channel gain g ij Follows the mean λ ij If it follows an exponential distribution, then and The probability density function (PDF) is divided into:

[0165]

[0166]

[0167] remember: a=(1-ξ)I th b=ξI th , but

[0168]

[0169] ②When hour, but

[0170]

[0171]

[0172]

[0173] In summary, R n The probability of achieving secure communication with D is:

[0174]

[0175] Based on the derivation of the interruption probability of each node, the system interruption probability is:

[0176]

[0177] Furthermore, the confidential throughput analysis in step two includes:

[0178] When the communication duration is T, the total duration for information transmission is (1-α)T. At a target data rate of R... s In this case, the probability of the system achieving secure transmission is (1-SOP), therefore, the confidential throughput of the system within time T is defined as:

[0179] SC=(1-SOP)(1-α)R S (28)

[0180] Furthermore, the energy efficiency analysis in step two includes:

[0181] If the transmission duration is T, then the total duration for information transmission is (1-α)T. At a target data rate of R... s In this case, the system's energy efficiency is expressed as:

[0182]

[0183] The secure transmission performance analysis system for multi-hop cognitive relay provided in this invention includes:

[0184] The network model building module is used to build a low-level multi-hop cognitive network model based on the cooperation between PU and SU, and to assist relay nodes in realizing communication between the auxiliary source node S and the destination node D by collecting the radio frequency energy of PU-Tx.

[0185] The transmission power control module is used by S and the auxiliary relay node to control their own transmission power; it also sets an artificial scrambling signal for the last hop relay node to interfere with the passive eavesdropper E.

[0186] The system performance analysis module is used to derive and calculate the system's security interruption probability SOP, security throughput SC, and energy efficiency EE expression to achieve system performance analysis.

[0187] II. Application Examples. To enable those skilled in the art to fully understand how the present invention is specifically implemented, this section provides explanatory examples that expand upon the technical solutions of the claims.

[0188] This invention constructs a cognitive radio network for cooperative communication between a Purpose Utility (PU) and a Subscriber Unit (SU), employing energy harvesting-based multi-cognitive relays to assist the SU in communication. This approach reduces transmission costs by moving away from the traditional method of expanding communication range through additional base stations. Furthermore, the invention introduces artificial scrambling signals to interfere with passive eavesdroppers near the destination. The novel system proposed in this invention effectively ensures reliable transmission for the SU.

[0189] III. Evidence of the Relevant Effects of the Embodiments. The embodiments of the present invention have achieved some positive effects during research and development or use, and indeed possess significant advantages compared to existing technologies. The following description, in conjunction with data, charts, and other materials from the experimental process, illustrates these advantages.

[0190] This invention provides a cognitive radio network model for cooperative communication between the PU and SU, such as... Figure 1 , Figure 2 As shown, each auxiliary relay node is equipped with an energy harvesting device. Figure 3 As shown, the entire transmission process is divided into two transmission time slots. The first stage is the energy harvesting stage, with a duration of αT. The second stage is the data transmission stage, with a duration of (1-α)T.

[0191] Furthermore, this invention provides simulations and analyses to verify the impact of factors such as the predetermined target data rate, energy harvesting time, and interference power limitations on the security interruption probability (SOP), security throughput (SC), and energy efficiency (EE). First, the number of auxiliary repeaters is n = 4, meaning the journey from source node S to destination node D requires 5 hops. The energy harvesting factor η = 0.9, and the channel gains on the S to D link are as follows: g s,1 =0.7, g 1,2 =0.8, g 2,3 =0.75, g 3,4 =0.85, g 4,D =0.6. The channel gain from the last-hop drone-assisted relay to the eavesdropping node E is g. 4,E =0.5, the channel gains of the energy harvesting links from PU-Tx to each relay are respectively, g T,1 =0.5g T,2 =0.55, g T,3 =0.52, g T,4 =0.63. The channel gains of each relay to PU-Rx, S and the interference link, are respectively, g S,P =0.6, g 1,P =0.58, g 2,P =0.7, g 3,P =0.65, g 4,P =0.72. Furthermore, the transmission power P of PU-Tx... T =20w, communication duration T=20, mean σ of additive white Gaussian noise for each transmission channel 2 =1. The following simulation experiments will be used to analyze the secure transmission performance of the system.

[0192] First, the predetermined target rate R is detected based on different time allocation factors α. s The impact on the security interruption probability (SOP) and security throughput (SC). For example... Figure 4 As shown, when the interference power threshold is I th In an environment with a power distribution factor of ξ = 0.5 and time distribution factors of α = 0.1, α = 0.3, α = 0.6, and α = 0.7, simulation results show that the SOP increases with R... s The process of increasing is continuous; when α = 0.6, when R s When the speed reaches 3 bps, the system is about to completely shut down. Within the defined R... s In this case, the SOP is affected by α; the larger the value of α, the greater the probability of system interruption. Furthermore, as... Figure 5 As shown, the system's secure throughput SC is also affected by R. s With the influence of α, as R sAs α increases, it continuously decreases. Experimental results show that when the system is at I... th It performs best compared to other environments in an environment with 10W and α=0.1.

[0193] Secondly, based on different interference thresholds I th Detect the predetermined target rate R s The impact on the Standard Operating Procedure (SOP) for the probability of security breaches. For example... Figure 6 As shown, with time allocation factor α = 0.1, power allocation factor ξ = 0.5, and interference power thresholds I... th =3w, I th =10w, I th =15w, I th In an environment with a capacity of 20W, the Standard Operating Procedure (SOP) varies with R. s The process of increasing is continuous. Within a given R... s In this case, SOP and I th Related to the settings, when I th The larger the value of R, the smaller the system SOP. Simulation results show that when R... s When the value of I is in the range of 0.25 to 0.75, th The impact on the system's standard operating procedures (SOPs) is minimal. Furthermore, as... Figure 7 As shown, the system's secure throughput SC is also affected by R. s with I th The impact. When I th When determined, SC follows R s The process of increasing is constantly decreasing; when R s When determined, SC follows I th The increase is continuous. Experimental results show that when the system is at I... th It performs best compared to other environments in an environment with 20W and α=0.1, achieving the minimum SOP and the maximum SC.

[0194] Next, we examine the relationship between different time allocation factors α and different interference thresholds I. th Detect the predetermined target rate R s The impact on energy efficiency (EE). For example... Figure 8 , Figure 9 As shown, simulation results indicate that energy efficiency (EE) increases with the predetermined target rate R. s The process of increasing is constantly decreasing. Furthermore, Figure 8 The interference threshold I was displayed. th =7W, power allocation factor ξ=0.5, and time allocation factors α=0.1, α=0.3, α=0.6, α=0.7 respectively. In an environment where EE and R... s The relationship between them, in a given R sUnder these circumstances, EE decreases continuously as α increases. Figure 9 The time allocation factor α = 0.1, the power allocation factor ξ = 0.5, and the interference thresholds are shown as I. th =5w,I th =7w,I th =10w, I th =15w environment EE and R s The relationship between them, in a given R s In this case, EE with I th The process of increasing is constantly decreasing. By comparing α and I... th The impact on EE, the results show, at a given R s In this case, I th The effect on EE is greater than the effect of α on EE.

[0195] Finally, based on whether there is artificial scrambling in the nth hop auxiliary relay, the scrambling detection target rate R is determined. s The impact on the security interruption probability (SOP) and security throughput (SC). For example... Figure 10 , Figure 11 As shown, when α = 0.1, I th In an environment with a power distribution factor of ξ = 0.5, a simulation experiment was conducted to test the security performance of the nth-hop auxiliary relay with and without artificial scrambling. The results show that after adding an artificial scrambling signal with a power distribution factor of ξ = 0.5, the SOP (Security Operation Point) increases with R. s The increase in power distribution factor (PDF) is smaller than that of a system without artificial scrambling. At the same time, SC is also improved compared to SC, that is, the security performance of an artificially scrambling system with a power distribution factor (ξ) of 0.5 is significantly improved compared to a system without artificial scrambling.

[0196] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0197] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for analyzing the secure transmission performance of multi-hop cognitive relay, characterized in that, The method for analyzing the secure transmission performance of multi-hop cognitive relay includes: constructing a low-level multi-hop cognitive network model based on the cooperation of primary user PU and secondary user SU; enabling auxiliary relay nodes to communicate with the destination node D by collecting the radio frequency energy of PU-Tx; simultaneously, S and the auxiliary relay nodes control their own transmission power; setting an artificial scrambling signal for the last-hop relay node to interfere with the passive eavesdropper E; deriving and calculating the system's secure interruption probability SOP, secure throughput SC, and energy efficiency EE expressions to achieve system model performance analysis; specifically including the following steps: Step 1, System Model Construction: Construct the network model and the transmission model respectively; Step 2, Performance Analysis: Analyze the probability of security interruption, security throughput, and energy efficiency respectively; The construction of the network model in step one includes: A decoding and forwarding model assisted by n cognitive relays is constructed, with an eavesdropping channel present at the last hop. The system model includes two networks: SU and PU. The SU network consists of a source node S, a legitimate destination node D, and n relays. The PU network includes a primary user transmitter (PU-Tx) and a primary user receiver (PU-Rx); simultaneously, there is an illegal eavesdropping node E near the destination node, where each node is configured with a single antenna and operates in half-duplex mode, and there are n auxiliary relays. Energy is harvested from the PU-Tx radio frequency environment for decoding and forwarding; the nth relay node Artificial scrambling is sent to E. When the destination node has prior information about the scrambling signal, the scrambling signal is eliminated on the legitimate destination node, thus enabling the destination node to receive information normally. Since the distance between the source node S and the destination node D is relatively far, E will not be able to eavesdrop on the signals transmitted between all nodes before the nth auxiliary relay. The construction of the transmission model in step one includes: When all channels follow Rayleigh fading, the channel coefficients are... , , The channel gain is , Follow the mean The exponential distribution, All relay nodes are energy harvesting nodes and perform EH (Energy Harnessing) according to a time-switching strategy; when the total information transmission time is T, the entire communication process is divided into two time slots. The first time slot is the EH phase for n auxiliary relays, lasting for a duration of T. , This is called the time allocation factor; The expression for the energy collected by the EH-assisted relay is: ， in, This refers to the transmission power of PU-Tx. It is an energy harvesting factor. It is PU-Tx and Channel gain; The second time slot is the stage where n auxiliary relays transmit the signal from S to D and E. Assuming the transmission time of each relay is fixed and the same, the transmission duration of each relay node is... The second time slot, relay node The received signal is: ， in, It is the transmission power of S. Is S and Channel gain, It is the signal emitted by S. It is additive white Gaussian noise. ; Similarly, The received signal is: ， in, yes Transmission power, yes and Channel gain, It is additive white Gaussian noise. ; Since the system operates in low-level mode, the transmission power of each auxiliary relay node should be within the PU-Rx interference threshold. Under the constraints; assuming the transmission power of the nth relay node is Then among them Used to transmit real signals, Used to transmit artificially scrambled signals. This is called the power allocation factor; the signal received by D is: ， in, yes The transmitted signal, yes Channel gain to D, It is an artificially added scrambling signal; This represents the additive noise at receiver D; This represents the additive noise at the eavesdropping end E; The signal received by E is: ， in, yes The transmitted signal, yes Channel gain to E, It is an artificially added scrambling signal; The probability analysis of security breach in step two includes: Throughout the communication process, the condition for the relay to successfully decode the source information is the channel capacity of the relay link. Exceeding the target data rate Assuming that the target data rate of each node in the communication system is the same. Due to channel gain Follow the mean The exponential distribution of has a probability density function as: ， The cumulative distribution function is: ， in, Indicates channel power gain A specific value; Due to the power of source node S Limited by the interference threshold of PU-Rx, therefore relay node Transmission power It is limited by EH and also by the interference threshold of PU-Rx; ， in Indicates the source node Channel power gain; Indicates the main user transmitter PU-Tx to the number relay nodes Channel power gain; Indicates the energy harvesting phase; Indicates the information transmission stage; This indicates the interference threshold at the PU receiver. This represents the number of relay nodes / number of time slots. Indicates energy conversion efficiency (0~1); This indicates the emission power of the energy emission node (or energy source); Indicates the corresponding power gain; First relay Successfully decoded The probability is: ， Similarly, Successfully decoded The probability is: ， in, , yes The probability density function, yes The probability density function; D successfully decoded The channel capacity at that time is: ， E successfully decoded The channel capacity at that time is: ， Define the system's secure throughput as: ， in, ; Signal-to-noise ratio of the signal received at point D The signal-to-noise ratio of the received signal at point E The expressions are as follows: ， ； The probability of secure transmission of D is defined as the channel capacity being greater than or equal to a predefined transmission rate. The probability of achieving secure communication with D is: Depend on Estimate the probability of achieving secure communication: ① hour, Right now Then there is ， ， ； Due to channel gain Follow the mean If it follows an exponential distribution, then and The probability density function PDF is divided into: ， ， remember: , , , , but ； X represents a random variable. ; Represents a random variable. ; Represents a random variable. ; Represents a constant. ; Represents a constant. ; Represents a constant. ; ②When hour, but ， ， ； In summary, for both of the above situations, The probability of achieving secure communication with D is: ， Based on the derivation of the interruption probability of each node, the system interruption probability is: ； The confidential throughput analysis in step two includes: when the communication duration is T, the total duration used for information transmission is... At the target data rate In this case, the probability of the system achieving secure transmission is Therefore, the system's security capability within time T is defined as follows: ， Energy efficiency analysis includes: if the transmission duration is T, then the total duration used for information transmission is... At the target data rate In this case, the system's energy efficiency is expressed as: 。 2. A secure transmission performance analysis system for multi-hop cognitive relay using the secure transmission performance analysis method described in claim 1, characterized in that, The secure transmission performance analysis system for multi-hop cognitive relay includes: The network model building module is used to build a low-level multi-hop cognitive network model based on the cooperation between PU and SU, and to assist relay nodes in realizing communication between the auxiliary source node S and the destination node D by collecting the radio frequency energy of PU-Tx. The transmission power control module is used by S and the auxiliary relay node to control their own transmission power; it also sets an artificial scrambling signal for the last hop relay node to interfere with the passive eavesdropper E. The system performance analysis module is used to derive and calculate the system's security interruption probability SOP, security throughput SC, and energy efficiency EE expression to achieve system performance analysis.

3. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the secure transmission performance analysis method for multi-hop cognitive relay as described in claim 1.

4. A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the secure transmission performance analysis method for multi-hop cognitive relay as described in claim 1.

5. An information data processing terminal, characterized in that, The information data processing terminal is used to implement the secure transmission performance analysis system for multi-hop cognitive relay as described in claim 2.

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