A method for partitioned RIS collaborative assisted symbiotic secure communication

Abstract

This invention proposes a method for RIS-assisted co-existing secure communication, comprising establishing a RIS-assisted co-existing secure communication system model, virtually dividing the RIS into TC and CJ regions, constructing a primary system for transmitting confidential primary signals and a secondary system for transmitting secondary signals based on the TC region, and constructing a cooperative interference system based on the CJ region; taking maximizing the achievable secure rate of the primary system as the optimization objective, and combining the minimum rate threshold constraint of the secondary system, the RIS phase shift constraint, and the PTx transmit power constraint, constructing a joint optimization problem for optimizing the RIS phase shift vector and the PTx transmit beamforming vector; decoupling the joint optimization problem into a PTx transmit beamforming optimization subproblem and a RIS phase shift optimization subproblem, and solving them using the SOCP algorithm based on alternating optimization to obtain the final resource allocation scheme. This invention can improve the reliability and security of primary and secondary signal transmission, and also improve spectrum utilization through regional cooperation.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, to reconfigurable intelligent surfaces (RIS) and symbiotic wireless communication technology, and particularly to a RIS collaborative assisted symbiotic secure communication method. Background Technology

[0002] With the exponential growth in the number of IoT devices, issues such as spectrum and energy consumption in communication systems are becoming increasingly prominent. As one of the key candidate technologies for 6G, symbiotic communication combines the advantages of environmental backscattering and cognitive radio, achieving efficient spectrum resource reuse while significantly reducing system power consumption. However, subsystems in symbiotic communication networks rely on backscattering communication, and their signal transmission is susceptible to obstruction, channel fading, and interference, resulting in limited communication link reliability and coverage. RIS, as a novel electromagnetic modulation technology, can intelligently reconstruct the wireless propagation environment by dynamically adjusting the amplitude and phase of the reflecting unit, achieving proactive control over signal coverage enhancement and interference suppression. This provides a new technological dimension for overcoming traditional channel fading bottlenecks and improving system energy efficiency.

[0003] While RIS improves the coverage of primary and secondary links, the additional reflection paths it introduces can be exploited by malicious eavesdroppers, posing new security threats to the system. Therefore, new solutions are urgently needed to address the inherent security issues of RIS-assisted symbiotic communication. The literature Zhang C, Zhou H, Long R, et al. Partition-based RIS for MU-MISOSymbiotic Radios[J]. IEEE Internet of Things Journal, 2025, 12(15): 30619-30633. divides the RIS into two parts, one part is responsible for transmitting the main signal and the other part transmits the main and secondary signals. Under the constraint of the quality of service of the main and secondary signals, the resource allocation problem of minimizing system power consumption is studied. The literature Lyu B, Du H, Hua M, et al. RIS-Assisted Integrated Sensing and Symbiotic Radio Systems[J]. IEEE Wireless Communications Letters, 2025, 14(4): 1144-1148. studies the problem of RIS-assisted integrated sensing and symbiotic communication, in which the two parts of the partitioned RIS transmit the main and secondary signals respectively, providing performance gain for the sensing target. Although these methods improve the reliability of symbiotic communication by utilizing the information relay characteristics of RIS, they do not consider the information transmission security problem and the corresponding resource allocation problem. The cooperative interference characteristics of RIS need to be further developed. Summary of the Invention

[0004] To address the technical problems of existing technologies that fail to fully utilize the cooperative jamming characteristics of RIS (Radio Resonance Interference System), struggle to effectively ensure the secure transmission of primary and secondary signals, and lack corresponding resource allocation strategies, this invention proposes a partitioned RIS cooperative-assisted symbiotic secure communication method. In a RIS-assisted symbiotic communication system, a virtual partitioning strategy is employed to assist the transmission of primary and secondary signals, reducing the received signal quality for eavesdroppers. This method can be applied to scenarios where cellular and IoT communications coexist in complex electromagnetic environments. This invention virtually divides the RIS into a Transmission Construction (TC) region and a Cooperative Jamming (CJ) region, and jointly optimizes the transmit beamforming vector of the primary transmitter (PTx) and the reflection coefficient matrices of the two RIS regions. This approach not only utilizes the dual functions of RIS information relay and cooperative jamming to improve the reliability and security of primary and secondary signal transmission, but also improves spectrum utilization through regional cooperation, thereby achieving a balance between security performance gains, system cost, and design complexity.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for partitioned RIS collaborative assisted symbiotic secure communication includes:

[0007] Step 1: Establish a symbiotic secure communication system model assisted by RIS reconfigurable smart surface. When constructing the secure communication system model, the RIS reconfigurable smart surface is virtually divided into a TC transmission construction area and a CJ cooperative interference area. Based on the TC transmission construction area, a main system for transmitting confidential main signals and a secondary system for transmitting secondary signals are constructed. Based on the CJ cooperative interference area, a cooperative interference system is constructed.

[0008] Step 2: With maximizing the achievable safe rate of the main system as the optimization objective, and combining the minimum rate threshold constraint of the subsystem, the phase shift constraint of the RIS reconfigurable smart surface, and the transmit power constraint of the PTx main transmitter, a joint optimization problem is constructed to optimize the phase shift vector of the RIS reconfigurable smart surface and the transmit beamforming vector of the PTx main transmitter.

[0009] Step 3: Decouple the joint optimization problem into a PTx main transmitter transmit beamforming optimization subproblem and a RIS reconfigurable smart surface phase shift optimization subproblem, and solve them using the SOCP second-order cone programming resource allocation algorithm based on alternating optimization to obtain the final resource allocation scheme.

[0010] Furthermore, the RIS-based reconfigurable smart surface-assisted symbiotic secure communication system model includes: equipped with The PTx main transmitter with one antenna is equipped with The RIS reconfigurable smart surface consists of one reflector unit, one single-antenna IR integrated receiver, and one single-antenna Eve malicious eavesdropper; there are no direct links between the PTx master transmitter and the IR integrated receiver or the Eve malicious eavesdropper; the RIS reconfigurable smart surface is virtually divided into units with a number of... The number of TC transmission construction areas and units is The CJ cooperative jamming zone and the TC zone have dual functions. On the one hand, they assist the PTx master transmitter in achieving secure transmission of confidential master signals to the IR integrated receiver. On the other hand, they establish reliable transmission of sensing secondary signals from the PTx master transmitter to the IR integrated receiver through backscattering. The CJ cooperative jamming zone modulates the incident radio frequency signal from the PTx master transmitter into a jamming signal to degrade the channel quality of Eve's malicious eavesdroppers.

[0011] Both the main system and the secondary system sequentially include a PTx main transmitter, a TC transmission construction area of ​​the RIS reconfigurable smart surface, and an IR integrated receiver. The Eve malicious eavesdropper eavesdrops on the confidential main signal reflected by the TC transmission construction area. Based on the dual function of the TC transmission construction area, the main system is used to transmit the confidential main signal, and the secondary system is used to transmit the secondary signal. The cooperative jamming system sequentially includes a PTx main transmitter, a CJ cooperative jamming area of ​​the RIS reconfigurable smart surface, an Eve malicious eavesdropper that jointly receives the signal transmitted by the CJ cooperative jamming area, and an IR integrated receiver.

[0012] Furthermore, establishing a RIS-based reconfigurable smart surface-assisted symbiotic secure communication system model also includes constructing a channel model, with specific methods including:

[0013] Considering the quasi-static block fading channel model, the channel coefficients of the TC transmission construction region from the PTx master transmitter to the RIS reconfigurable smart surface are defined respectively. Channel coefficients of the CJ cooperative interference region from the PTx master transmitter to the RIS reconfigurable smart surface. Channel coefficients from the TC transmission build-up area to the IR integrated receiver Channel coefficients from the CJ cooperative interference zone to the IR integrated receiver ; Channel coefficients from TC transmission construction area to Eve malicious eavesdropper Channel coefficients from the CJ cooperative interference zone to the Eve malicious eavesdropper. Establish large-scale fading models and small-scale fading models for all communication links. The large-scale fading model is as follows: ,in, Indicates the path loss of the communication link. For the path loss at the reference distance, Represents the distance between two nodes. Indicates the reference distance. It is the path loss exponent; small-scale fading is modeled as a Rice distribution;

[0014] The model for a RIS-reconfigurable smart surface-assisted symbiotic secure communication system is established, which also includes modeling the transmitted signals of the PTx master transmitter, modeling the received signals of the IR integrated receiver and the Eve malicious eavesdropper, modeling the achievable secure rate of the IR integrated receiver decoding the confidential master signal, and modeling the achievable rate of the IR integrated receiver decoding the secondary signal.

[0015] Furthermore, the transmitted signal modeling of the PTx master transmitter includes: the signal transmitted by the PTx master transmitter to the IR integrated receiver is... ,in, This represents the transmit beamforming vector of the PTx main transmitter. The confidential master signal sent by the PTx master transmitter in the l-th time slot to the IR integrated receiver satisfies , This represents the expectation operation and follows a cyclically symmetric complex Gaussian distribution. ;

[0016] Modeling of received signals from an integrated IR receiver and an Eve malicious eavesdropper, including:

[0017] ;

[0018] ;

[0019] in, The received signal of the IR integrated receiver in the l-th time slot. For Eve's malicious eavesdropper, the received signal in the l-th time slot, The reflection coefficient matrix of the TC transmission construction area. The phase shift vector for the TC transmission construction region. The unit corresponding to the TC transmission construction area phase shift, This indicates the diagonalization operation. The reflection coefficient matrix of the CJ cooperative interference zone. The phase shift vector of the CJ cooperative interference region. Units corresponding to the CJ cooperative interference zone phase shift, To transmit the sensing sub-signal of the TC transmission construction area, The interference signal modulated by the CJ cooperative interference zone. This refers to the received noise at the integrated IR receiver. For Eve's malicious eavesdropper, the received noise;

[0020] Achievable secure rate for decoding confidential master signals using an integrated IR receiver Modeling, including:

[0021] ;

[0022] ;

[0023] ;

[0024] in, The achievable rate for decoding the main signal s in an integrated IR receiver. The achievable rate at which Eve's malicious eavesdropper receives the main signal s; Equivalent channel matrix from the TC transmission construction area to the IR integrated receiver, and equivalent channel matrix from the CJ cooperative interference area to the IR. The equivalent channel matrix from the TC transmission construction area to the Eve malicious eavesdropper. Equivalent channel matrix from CJ cooperative interference zone to Eve malicious eavesdropper , Indicates conjugate transpose; This represents the noise variance received at the IR integrated receiver. The noise variance received at Eve's malicious eavesdropper's location;

[0025] Modeling the achievable rate of decoding secondary signals in an integrated IR receiver, including: decoding the confidential primary signal. Then, first subtract the main signal, then decode the secondary signal c. When the time slot ratio of the main signal to the secondary signal... Based on the maximum ratio combining principle, the signal-to-interference-plus-noise ratio (SIR) of the decoded secondary signal by the IR integrated receiver is calculated, and the achievable rate of the decoded secondary signal by the IR integrated receiver is calculated based on the SIR of the decoded secondary signal, as shown in the following formula:

[0026] ;

[0027] ;

[0028] in, The signal-to-interference-plus-noise ratio (SIR) of the sub-signal decoded by the IR integrated receiver.

[0029] Furthermore, the joint optimization problem described in step three is expressed as:

[0030] ;

[0031] in, Let be the objective function. This is the minimum rate threshold constraint for the subsystem. Phase shift constraints for the TC transmission construction region, Phase shift constraints for the CJ cooperative interference region To constrain the transmit power of the PTx main transmitter, This is the minimum rate threshold for decoding sub-signals in an IR integrated receiver. This represents the peak power of the PTx master transmitter.

[0032] Furthermore, the joint optimization problem is decoupled into a PTx master transmitter transmit beamforming optimization subproblem and a RIS reconfigurable smart surface phase shift optimization subproblem, including:

[0033] S3.1. By introducing a simplified power term, the logarithms in the objective function are transformed into a linear form by subtracting them. The first set of auxiliary variables is introduced to constrain the logarithmic term in the objective function, resulting in the first set of inequality constraints. Based on the first set of inequality constraints, a reconstruction optimization problem with a separable structure and a linear objective function is constructed.

[0034] S3.2 Construction of the PTx main transmitter transmit beamforming optimization subproblem: By fixing the phase shift of the RIS reconfigurable smart surface in the reconfiguration optimization problem, the initial subproblem of PTx main transmitter transmit beamforming optimization is obtained. The SDR method is used to handle the non-convex constraint of the RIS phase shift. and After obtaining the processed phase shift convex constraints, a second set of auxiliary variables is introduced to perform an equivalent transformation on the first set of inequality constraints to obtain a second set of inequality constraints. The non-convex constraints in the second set of inequality constraints are processed using the SCA method to obtain a third set of inequality constraints. Based on the processed phase shift convex constraints, the convex constraints in the second set of inequality constraints, and the third set of inequality constraints, the final sub-problem of PTx main transmitter transmit beamforming optimization is constructed by combining the initial sub-problem of PTx main transmitter transmit beamforming optimization.

[0035] S3.3 Construction of the RIS Reconfigurable Smart Surface Phase Shift Optimization Subproblem: Fixing the transmit beam vector of the PTx master transmitter in the reconfiguration optimization problem, we obtain the initial subproblem of the RIS reconfigurable smart surface phase shift optimization. Introducing a third set of auxiliary variables to perform equivalent transformations on the first set of inequality constraints, we obtain a fourth set of inequality constraints. The non-convex constraints in the fourth set of inequality constraints are processed using the SCA method to obtain a fifth set of inequality constraints. Based on the convex constraints in the fourth set of inequality constraints and the fifth set of inequality constraints, combined with the initial subproblem of the RIS reconfigurable smart surface phase shift optimization, we construct the final subproblem of the RIS reconfigurable smart surface phase shift optimization.

[0036] Furthermore, the implementation method of step S3.1 includes:

[0037] S3.11, Simplify the power term: Let the received power of the main signal at the IR terminal be: The interference and noise power of the main signal at the IR terminal are: The received power of the main signal at the Eve terminal is: The interference and noise power of the main signal at the Eve terminal is: ;

[0038] S3.12. Transform the objective function into a linear form by subtracting the logarithms, and introduce the first set of auxiliary variables. For the logarithmic term in the objective function , and Apply constraints:

[0039] ;

[0040] therefore, , The non-convex constraint is transformed into the first set of inequality constraints;

[0041] S3.13. Based on the first set of inequality constraints, construct a reconstruction optimization problem with a separable structure and a linear objective function:

[0042] .

[0043] Furthermore, the implementation method of step S3.2 is as follows:

[0044] S3.21. The phase shift of the RIS reconfigurable smart surface in the fixed reconfiguration optimization problem yields the initial sub-problem for optimizing the transmit beamforming of the PTx master transmitter:

[0045] ;

[0046] S3.22, Introduce the second set of auxiliary variables By performing an equivalent transformation on the first set of inequality constraints, we obtain the second set of inequality constraints:

[0047] ;

[0048] ;

[0049] ;

[0050] S3.23. The SCA method is used to process the non-convex constraints (12b), (12c), (13a), and (13d) in the second set of inequality constraints to obtain the third set of inequality constraints:

[0051] ;

[0052]

[0053] in, , , , ; As the initial value, , , This is the solution obtained in the nth iteration. This indicates the operation of taking the real part;

[0054] S3.24. Based on the convex constraints in the second set of inequalities and the third set of inequalities, and combined with the initial sub-problem of PTx main transmitter transmit beamforming optimization, construct the final sub-problem of PTx main transmitter transmit beamforming optimization:

[0055] .

[0056] Furthermore, the implementation method of step S3.3 is as follows:

[0057] S3.31. By fixing the transmit beam vector of the PTx master transmitter in the reconfiguration optimization problem, we obtain the initial sub-problem of RIS reconfigurable smart surface phase shift optimization:

[0058] ;

[0059] S3.32. Using the SDR method to handle non-convex constraints of RIS phase shift. and :make , Then the phase shift mode constraint is transformed into a convex constraint: , It is a positive semi-definite matrix. , , , Represents the rank operation of a matrix;

[0060] S3.33, Introduce a third set of auxiliary variables By performing an equivalent transformation on the first set of inequality constraints, we obtain the fourth set of inequality constraints:

[0061] ;

[0062] ;

[0063] ;

[0064] in, Represents the trace operation of a matrix. , , , ;

[0065] S3.34. The SCA method is used to process the non-convex constraints in the fourth set of inequality constraints to obtain the fifth set of inequality constraints:

[0066] ;

[0067] S3.35. Based on the convex constraints in the fourth set of inequalities and the fifth set of inequalities, and combined with the initial sub-problem of RIS reconfigurable smart surface phase shift optimization, construct the final sub-problem of RIS reconfigurable smart surface phase shift optimization:

[0068] .

[0069] Furthermore, a second-order cone programming resource allocation algorithm based on alternating optimization (SOCP) is used to solve the problem, including:

[0070] The final subproblem of beamforming optimization for the T1 and PTx main transmitters is in SOCP form and is solved using the CVX toolbox in MATLAB.

[0071] The final subproblem of phase shift optimization for T2 and RIS reconfigurable smart surfaces is further relaxed into a convex semidefinite programming form using the SDR method, thus removing constraints. and Then use the CVX tool to solve it. If the solution is obtained... Matrix and If the rank of the matrix is ​​1, then for Matrix and The matrix is ​​subjected to singular value decomposition to obtain the solution of the phase shift vector of the TC transmission construction region. Solution of the phase shift vector of the CJ cooperative interference region Otherwise, use Gaussian randomization to obtain a solution that meets the conditions; then transfer the solution of the phase shift vector of the constructed region. Solution of phase shift vector of cooperative interference region Projecting onto the unit modulus constraint set yields a suboptimal solution. and To ensure the convergence of the algorithm, the following strategy is used for updates:

[0072] ;

[0073] T3. Repeat T1-T2 until the algorithm converges.

[0074] The beneficial effects of this invention are as follows:

[0075] First, this invention employs a RIS partitioned collaborative assisted symbiotic secure communication system, dividing the RIS into a TC region and a CJ region. The TC region enhances the channel from the PTx to the integrated receiver (IR) by adjusting the phase configuration, thereby improving signal strength and communication quality. The CJ region generates interference signals through backscatter modulation and then degrades the received signal quality of eavesdroppers by adjusting the phase configuration, effectively ensuring the security of the symbiotic communication system.

[0076] Secondly, this invention fully utilizes the dual functions of signal enhancement and cooperative interference of RIS partitioning. Through partitioning, its information relay and interference assistance capabilities can be utilized more effectively, realizing function reuse and simplifying the network system architecture.

[0077] Third, the present invention adopts a combined active beamforming and passive phase shift modulation strategy, which can adaptively adjust the phase configuration according to different communication requirements and environmental conditions, thereby improving design flexibility and adaptability. Attached Figure Description

[0078] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0079] Figure 1 This is a flowchart of the present invention.

[0080] Figure 2 This is a schematic diagram of the system model of the present invention.

[0081] Figure 3 This is the iterative convergence graph of the present invention.

[0082] Figure 4 The maximum PTx transmit power of this invention Simulation results of the impact on the safe achievable rate of the main signal.

[0083] Figure 5 The maximum PTx transmit power of this invention Simulation results of the impact on the achievable rate of the secondary signal.

[0084] Figure 6 The figure shows the simulation results of the effect of the number of RIS units M on the achievable speed in this invention. Detailed Implementation

[0085] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0086] A method for partitioned RIS (Resilient Surface Array) collaborative assisted symbiotic secure communication constructs a symbiotic secure communication system using a master transmitter (PTx), a reconfigurable smart surface (RIS), an integrated receiver (IR), and a single-antenna malicious eavesdropper (Eve). The master transmitter (PTx) transmits confidential signals to the integrated receiver (IR), while the malicious eavesdropper (Eve) intercepts the confidential information transmitted by the master transmitter (PTx). Simultaneously, the reconfigurable smart surface (RIS), acting as a secondary transmitter (STx), reflects secondary signals back to the integrated receiver (IR). The RIS, through partitioned collaboration, ensures the reliability of secondary signal transmission and reduces the probability of the master signal being intercepted by the malicious eavesdropper (Eve). Figure 1 As shown, the specific implementation methods include:

[0087] Step 1: Establish a symbiotic secure communication system model assisted by RIS reconfigurable smart surface. When constructing the secure communication system model, the RIS reconfigurable smart surface is virtually divided into a transmission construction (TC) region and a cooperative jamming (CJ) region. Based on the TC region, a main system for transmitting confidential primary signals and a secondary system for transmitting sensing secondary signals are constructed. Based on the CJ region, a cooperative jamming system is constructed.

[0088] In the embodiments of this application, such as Figure 2 As shown, the reconfigurable smart surface RIS-assisted symbiotic secure communication system includes: a device equipped with The PTx of the root antenna, one with The RIS has one reflector element, the IR has one single-antenna unit, and the Eve has one single-antenna unit; due to the presence of buildings, there are no direct links between PTx and IR, or Eve. The RIS is virtually divided into two regions, TC and CJ, with the following number of elements: and ,satisfy The TC area has a dual function: on the one hand, it assists the PTx in achieving secure transmission of confidential master signals to the IR; on the other hand, it establishes reliable transmission of sensing secondary signals through backscattering. The CJ area modulates the incident radio frequency signal into an interference signal to degrade the quality of the eavesdropping channel and improve the system's secure communication performance.

[0089] The main system consists of a main transmitter (PTx), a reconfigurable smart surface (RIS) TC area, and an integrated receiver (IR). A malicious eavesdropper, Eve, intercepts the confidential main signals reflected from the TC area. The main system is used to transmit confidential, high-speed, and important main signals (such as mobile communications, user data, and payment information). Security is its top priority; it cannot be eavesdropped on by Eve. The secondary system consists of a main transmitter (PTx), a reconfigurable smart surface (RIS) TC area, and an integrated receiver (IR). The secondary system is used to transmit minor, small-data, low-power sensing signals (such as temperature, humidity, location, and sensor data from IoT devices). High speed is not a priority; only reliable and uninterrupted connectivity is required. The cooperative jamming system consists of a main transmitter (PTx), a reconfigurable smart surface (RIS) CJ area, Eve (the receiver), and an IR that jointly receive signals transmitted from the CJ cooperative jamming area.

[0090] The work process is as follows:

[0091] The transmission path of the confidential master signal (master system): PTx transmits the confidential master signal into space, and the signal propagates in the form of radio frequency waves; the confidential master signal arrives at the TC and CJ regions of RIS at the same time; the TC region adjusts its own reflection coefficient to perform directional enhancement reflection of the confidential master signal, and accurately reflects the signal to IR; IR successfully receives and decodes the confidential master signal through the reflection path of RIS-TC region; Eve simultaneously receives the confidential master signal reflected from RIS-TC region and attempts to eavesdrop and crack it.

[0092] The transmission path of the sensing sub-signal (subsystem): The sub-signal has no independent transmitter; its energy comes entirely from the radio frequency signal emitted by the PTx. The TC region performs backscatter modulation on the incident PTx radio frequency signal, loading the sensing data into the reflected signal. The component carrying the sensing information in the modulated reflected signal is the sensing sub-signal. The TC region reflects the modulated signal to the IR. The IR first decodes the main signal, then removes it from the received mixed signal, and then decodes the sub-signal to complete the reliable transmission of the subsystem.

[0093] The transmission path of the CJ area interference signal (security protection): The CJ area receives the radio frequency signal transmitted by PTx and modulates it into a special pseudo-random interference signal; the CJ area reflects the interference signal in a directional manner towards Eve's location, and Eve simultaneously receives the confidential main signal from the TC area and the interference signal from the CJ area; the interference signal greatly reduces Eve's signal reception quality, making it unable to crack the confidential main signal.

[0094] In this embodiment of the application, a quasi-static block fading channel model is considered. The process of establishing the channel model is as follows:

[0095] First, identify all communication links in the system and define the channel coefficients:

[0096] The channel coefficients of the TC region from PTx to RIS are expressed as follows: ;

[0097] The channel coefficients for the CJ region from PTx to RIS are expressed as follows: ;

[0098] The channel coefficients from the TC area to the IR are expressed as follows: ;

[0099] The channel coefficients from the CJ region to the IR are expressed as follows: ;

[0100] The channel coefficient from TC area to Eve is expressed as: ;

[0101] The channel coefficients from CJ region to Eve are expressed as follows: ;

[0102] in, This represents the number of antennas in PTx. The number of TC area units, This represents the number of units in the CJ region.

[0103] Furthermore, large-scale fading models and small-scale fading models are established for all communication links:

[0104] Large-scale fading is modeled as follows: ,in, Indicates the path loss of the communication link. For the path loss at the reference distance, Represents the distance between two nodes. Indicates the reference distance. It is the path loss index. dB m, The specific calculations need to be based on the node coordinates. The coordinates of PTx, RIS, IR, and Eve are (0,0)m, (50,0)m, (45,2)m, and (50,2)m, respectively. .

[0105] Small-scale fading is modeled as a Rice distribution, which can be represented as: ,in It is the Rice factor; Represents the line-of-sight component, where This represents the array steering vector at the receiver / transmitter. The number of antennas / elements at the receiving / transmitting end, determined by the angle of arrival. and starting angle Decide, This represents the conjugate transpose operation. (Non-line-of-sight component) Each of its elements independently follows a complex Gaussian random distribution, i.e. .

[0106] In this embodiment of the application, it is also necessary to perform modeling of the PTx transmission signal, modeling of the IR and Eve reception signals, modeling of the achievable secure rate of the IR decoding confidential primary signal, and modeling of the achievable rate of the IR decoding secondary signal.

[0107] In this embodiment of the application, the modeling of the PTx transmission signal includes: the signal transmitted by the PTx to the IR is... ,in This represents the transmit beamforming vector of PTx. It is the confidential master signal sent to the IR in the l-th time slot PTx, which satisfies , This represents the expectation operation, and it follows a cyclically symmetric complex Gaussian distribution, i.e. .

[0108] In this embodiment, the received signal modeling of IR and Eve includes: based on the functions of the TC and CJ regions, the received signals of IR and Eve in the l-th time slot can be represented as follows:

[0109] (1);

[0110] (2);

[0111] in, For the IR received signal in the l-th time slot, For Eve's received signal in the l-th time slot, The reflection coefficient matrix of the TC region. The phase shift vector of the TC region. The unit corresponding to the TC area phase shift, This indicates the diagonalization operation. Here is the reflection coefficient matrix for the CJ region. The phase shift vector of the CJ region. For the unit corresponding to the CJ area phase shift, This is the secondary sensing signal of the TC region. Interference signal modulated in the CJ region. This is the received noise at the IR position. This represents the received noise at Eve.

[0112] Assuming the IR uses serial interference cancellation, the main signal s is decoded first, and the perceived secondary signal c and interference z are treated as noise. Therefore, the signal-to-interference-plus-noise ratio (SINR) of the IR decoded main signal is:

[0113] (3);

[0114] in, This represents the mathematical expectation of the statistical distributions of the perceived sub-signal c and the interference signal z. This represents the noise variance received at the IR port.

[0115] Similarly, Eve decodes the SINR of the confidential master signal as follows:

[0116] (4);

[0117] in, This represents the noise variance received at Eve.

[0118] In this embodiment of the application, the achievable secure rate modeling of IR decoding of the confidential master signal includes: to facilitate the solution of subsequent optimization problems, setting the equivalent channel matrix from the TC area to the IR... Equivalent channel matrix from CJ region to IR The equivalent channel matrix from TC region to Eve The equivalent channel matrix from CJ region to Eve The achievable rate of the IR decoding master signal s can be expressed as:

[0119] (5);

[0120] Similarly, the achievable rate at which Eve receives s is:

[0121] (6);

[0122] Therefore, the achievable secure rate for IR decoding of the confidential master signal is:

[0123] .

[0124] In this embodiment of the application, the achievable rate modeling of the IR decoding sub-signal includes:

[0125] IR in decoding confidential master signals Then, first subtract the main signal, and then decode and sense the secondary signal c. When hour, Given the time slot ratio between the primary signal and the sensing secondary signal, based on the maximum ratio combining principle, the SINR of the IR decoded secondary signal is:

[0126] (7);

[0127] Therefore, the achievable rate of the IR decoded sub-signal can be expressed as:

[0128] .

[0129] Step 2: With maximizing the achievable safe rate of the main system as the optimization objective, and combining the minimum rate threshold constraint, RIS phase shift constraint, and PTx transmit power constraint of the subsystem, construct a joint optimization problem to optimize the RIS phase shift vector and the PTx transmit beamforming vector.

[0130] In this embodiment of the application, the optimization problem is expressed as:

[0131] (8);

[0132] in, Let be the objective function. This is a minimum rate threshold constraint for the subsystem, used to guarantee the minimum quality of service for the sub-signal. For phase shift constraints in the TC region, For phase shift constraints in the CJ region, For PTx transmit power constraints, This is the minimum rate threshold for IR decoding to sense the secondary signal. This represents the peak power of PTx.

[0133] Step 3: Decouple the joint optimization problem into a PTx transmit beamforming optimization subproblem and a RIS phase shift optimization subproblem, and solve them using a second-order cone programming (SOCP) resource allocation algorithm based on alternating optimization to obtain the final resource allocation scheme.

[0134] In this embodiment of the application, the optimization problem is decoupled into a PTx transmit beamforming optimization sub-problem and a RIS phase shift optimization sub-problem, including:

[0135] By introducing auxiliary variables, the logarithmic subtraction in the objective function is transformed into a linear form, and the non-convex constraints are transformed into a series of inequality constraints, as follows:

[0136] First, simplify the power term:

[0137] Let the received power of the main signal at the IR terminal be: ;

[0138] The interference and noise power of the main signal at the IR terminal are: ;

[0139] The received power of the main signal at the Eve terminal is: ;

[0140] The interference and noise power of the main signal at the Eve terminal are: .

[0141] Furthermore, to transform the subtraction of logarithms in the objective function into a linear form, an auxiliary variable is introduced. By processing equations (5) and (6), we can obtain:

[0142] (9);

[0143] therefore, , The non-convex constraint is transformed into a series of inequality constraints.

[0144] Furthermore, based on the above equation, the optimization problem (8) in step two can be transformed into:

[0145] .

[0146] The above steps, by increasing the number of variables, reconstruct a complex optimization problem that is highly nonlinear, nonconvex, and coupled with variables into a problem with a separable structure, a linear objective function, and a more standard constraint form. Furthermore, using the contradiction method, it can be easily proven that the constraints in equation (9) are equal at the optimal solution, so equation (10) is equivalent to equation (8).

[0147] In this embodiment, the optimization of PTx transmit beamforming is discussed. This involves the phase shift between the two regions of RIS. and If we fix and eliminate constraints unrelated to RIS, then the optimization problem (10) becomes as follows:

[0148] (11);

[0149] Furthermore, auxiliary variables are introduced. Then equation (9) can be transformed into:

[0150] (12);

[0151] , , Phase shift here and Since it is fixed and no longer a variable, it is not placed in parentheses, and the same applies to formula (13).

[0152] (13);

[0153] Furthermore, observing equations (12) and (13), it can be seen that constraints (12a), (12d), (13b), and (13c) are convex, while constraints (12b), (12c), (13a), and (13d) are concave. The SCA method can be used to handle non-convex constraints. Therefore, by utilizing the first-order Taylor expansion and equations... The above non-convex constraint can be transformed into:

[0154] (14);

[0155] in, , , , ; As the initial value, , , This is the solution obtained in the nth iteration. This indicates the operation of taking the real part.

[0156] Similarly, constraint (9e) can be transformed into , Therefore, we can obtain:

[0157] (15)

[0158] Finally, the subproblem of solving the transmit beamforming vector of PTx is expressed as follows:

[0159] (16);

[0160] Problem (16) is in SOCP form and can be solved using MATLAB's CVX toolbox.

[0161] In this embodiment of the application, for the RIS phase shift coefficient optimization subproblem, when the transmit beamforming vector of PTx is fixed, the optimization problem becomes:

[0162] (17);

[0163] Furthermore, the SDR method is used to handle the non-convex constraint of the RIS phase shift. Let , Then the phase shift mode constraint is transformed into a convex constraint: , It is a positive semi-definite matrix. , , Represents the rank operation of a matrix.

[0164] Furthermore, similar to the processing methods in equations (12) and (13), auxiliary variables are introduced. At this point, the non-convex constraint equation (12) can be transformed into:

[0165] (18);

[0166] (19);

[0167] in, Represents the trace operation of a matrix. , , , .

[0168] Furthermore, for the non-convex constraint equations (18b) and (19a), using a first-order Taylor expansion, we can obtain:

[0169] (20);

[0170] in, and It is the solution obtained during the nth alternating optimization.

[0171] Furthermore, regarding the rate constraint of the perceived sub-signal According to the introduction of auxiliary variables and This signal can be obtained regarding and The constraint relationship is Similarly, the rate of the perceived sub-signal can be obtained with respect to... The constraints are .

[0172] Therefore, solving the phase shift of RIS and The optimization subproblem can be expressed as:

[0173] (twenty one);

[0174] Since the phase shift constraint is non-convex, equation (21) cannot be solved directly. Using the Semi-Definite Relaxation (SDR) method, it is further relaxed into a convex semidefinite programming form, and then solved using the CVX tool. If the solution obtained... and If the rank of the matrix is ​​1, then by... and Singular value decomposition yields and Otherwise, use Gaussian randomization to obtain a suboptimal solution that meets the conditions. Then, the vector... and Projecting onto the unit modulus constraint set, we obtain and Where j is the imaginary unit (i.e., ), Represents the phase angle of x. Representing vectors The m-th element.

[0175] Due to suboptimal solutions generated by the SDR method or Gaussian randomization and However, it cannot be guaranteed that the solution to the objective function in the (n+1)th iteration will not be less than the value in the nth iteration, meaning it may not necessarily be better than the result in the previous iteration. Therefore, to ensure that the non-decreasing sequence of objective values ​​generated in each iteration is iterated, the following strategy is adopted for updating:

[0176] (twenty two);

[0177] when , At that time, because It is the global optimal solution to the optimization problem (18), which is derived from... , , And thus And it does not terminate if the convergence condition is not met.

[0178] The effectiveness of the proposed partitioned RIS cooperative assisted symbiotic secure communication method and resource allocation algorithm is verified through Matlab simulation. The parameters are set as follows: the number of antennas in PTx. The total number of emitter units in the partitioned RIS is The number of reflective units in both the TC and CJ regions is 16, that is... Both the IR and the eavesdropper use a single antenna. Path loss coefficient. Rice factor , The maximum number of iterations is 100, and the convergence accuracy is... .

[0179] Figure 3 This is the iterative convergence graph of the present invention. From... Figure 3 As can be seen, the proposed algorithm converges quickly after a finite number of iterations, which fully demonstrates its convergence. Furthermore, the safe reach rate of the main system gradually increases with the number of iterations, reflecting the effectiveness of the algorithm. With the increase of the maximum transmit power of PTx, the IR received signal quality is enhanced, and the security performance of the main system is improved.

[0180] Figure 4 The simulation curves show the impact of the maximum PTx transmit power of this invention on the secure achievable rate of the main signal. To further verify the effectiveness of the proposed algorithm, Figure 4The following comparative schemes were designed: 1) PTx random beamforming, i.e., only the phase shift coefficient of RIS is optimized, while the beamforming vector of PTx is randomly selected; 2) RIS random phase shift coefficient, i.e. only the beamforming vector of PTx is optimized, without randomly selecting the phase shift coefficients of the two regions of RIS; 3) Traditional scheme, i.e., the two regions of RIS are only used to construct the transmission of primary and secondary system signals, without considering the CJ region. Figure 4 As can be seen from the above, the proposed scheme is significantly better than the three comparative schemes in improving the secure transmission performance of the main signal. This is because the proposed scheme not only considers the RIS partitioning scheme and makes full use of the information relay and cooperative interference capabilities of RIS, but also the joint optimization of PTx beamforming and RIS phase shift coefficient further optimizes the system resources.

[0181] Figure 5 The maximum PTx transmit power of this invention Simulation curves showing the impact of the sub-signal's achievable rate. From... Figure 5 As can be seen, the proposed scheme is significantly better than the three comparative schemes in ensuring the reliable transmission performance of the secondary signal. This is because the proposed scheme considers the joint optimization of the phase shift coefficients of the TC and CJ regions of the RIS, which provides greater flexibility.

[0182] Figure 6 The figure shows the simulation curves illustrating the impact of the number of RIS units M on the achievable safe rate of the primary signal and the achievable rate of the secondary signal. With the increase in reflector units, the RIS provides greater freedom in signal design, thus improving both the reliability and security of the symbiotic communication system. Furthermore, through reasonable resource allocation, the improvement in the security of the primary system is greater than that of the reliability of the secondary system, which is a fundamental requirement for the coexistence of cellular and IoT systems.

[0183] In summary, the partitioned RIS cooperative assisted symbiotic secure communication method proposed in this invention can effectively improve the security and reliability of cooperative communication networks, and simulation results fully demonstrate its effectiveness.

[0184] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for partitioned RIS collaborative assisted symbiotic secure communication, characterized in that, include: Step 1: Establish a symbiotic secure communication system model assisted by RIS reconfigurable smart surface. When constructing the secure communication system model, the RIS reconfigurable smart surface is virtually divided into a TC transmission construction area and a CJ cooperative interference area. Based on the TC transmission construction area, a main system for transmitting confidential main signals and a secondary system for transmitting secondary signals are constructed. Based on the CJ cooperative interference area, a cooperative interference system is constructed. Step 2: With maximizing the achievable safe rate of the main system as the optimization objective, and combining the minimum rate threshold constraint of the subsystem, the phase shift constraint of the RIS reconfigurable smart surface, and the transmit power constraint of the PTx main transmitter, a joint optimization problem is constructed to optimize the phase shift vector of the RIS reconfigurable smart surface and the transmit beamforming vector of the PTx main transmitter. Step 3: Decouple the joint optimization problem into a PTx main transmitter transmit beamforming optimization subproblem and a RIS reconfigurable smart surface phase shift optimization subproblem, and solve them using the SOCP second-order cone programming resource allocation algorithm based on alternating optimization to obtain the final resource allocation scheme.

2. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 1, characterized in that, A RIS-based reconfigurable smart surface-assisted symbiotic secure communication system model includes: equipped with The PTx main transmitter with one antenna is equipped with The RIS reconfigurable smart surface consists of one reflector unit, one single-antenna IR integrated receiver, and one single-antenna Eve malicious eavesdropper; there are no direct links between the PTx master transmitter and the IR integrated receiver or the Eve malicious eavesdropper; the RIS reconfigurable smart surface is virtually divided into units with a number of... The number of TC transmission construction areas and units is The CJ cooperative jamming zone and the TC zone have dual functions. On the one hand, they assist the PTx master transmitter in achieving secure transmission of confidential master signals to the IR integrated receiver. On the other hand, they establish reliable transmission of sensing secondary signals from the PTx master transmitter to the IR integrated receiver through backscattering. The CJ cooperative jamming zone modulates the incident radio frequency signal from the PTx master transmitter into a jamming signal to degrade the channel quality of Eve's malicious eavesdroppers. Both the main system and the secondary system sequentially include a PTx main transmitter, a TC transmission construction area of ​​the RIS reconfigurable smart surface, and an IR integrated receiver. The Eve malicious eavesdropper eavesdrops on the confidential main signal reflected by the TC transmission construction area. Based on the dual function of the TC transmission construction area, the main system is used to transmit the confidential main signal, and the secondary system is used to transmit the secondary signal. The cooperative jamming system sequentially includes a PTx main transmitter, a CJ cooperative jamming area of ​​the RIS reconfigurable smart surface, an Eve malicious eavesdropper that jointly receives the signal transmitted by the CJ cooperative jamming area, and an IR integrated receiver.

3. The method for partitioned RIS cooperative assisted symbiotic secure communication according to claim 2, characterized in that, Establishing a RIS-based reconfigurable smart surface-assisted symbiotic secure communication system model also includes constructing a channel model, with specific methods including: Considering the quasi-static block fading channel model, the channel coefficients of the TC transmission construction region from the PTx master transmitter to the RIS reconfigurable smart surface are defined respectively. Channel coefficients of the CJ cooperative interference region from the PTx master transmitter to the RIS reconfigurable smart surface. Channel coefficients from the TC transmission build-up area to the IR integrated receiver Channel coefficients from the CJ cooperative interference zone to the IR integrated receiver ; Channel coefficients from TC transmission construction area to Eve malicious eavesdropper Channel coefficients from the CJ cooperative interference zone to the Eve malicious eavesdropper. Establish large-scale fading models and small-scale fading models for all communication links. The large-scale fading model is as follows: ,in, Indicates the path loss of the communication link. For the path loss at the reference distance, Represents the distance between two nodes. Indicates the reference distance. It is the path loss exponent; small-scale fading is modeled as a Rice distribution; The model for a RIS-reconfigurable smart surface-assisted symbiotic secure communication system is established, which also includes modeling the transmitted signals of the PTx master transmitter, modeling the received signals of the IR integrated receiver and the Eve malicious eavesdropper, modeling the achievable secure rate of the IR integrated receiver decoding the confidential master signal, and modeling the achievable rate of the IR integrated receiver decoding the secondary signal.

4. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 3, characterized in that, Modeling the transmitted signal of the PTx master transmitter, including: the signal transmitted by the PTx master transmitter to the integrated IR receiver. ,in, This represents the transmit beamforming vector of the PTx main transmitter. The confidential master signal sent by the PTx master transmitter in the l-th time slot to the IR integrated receiver satisfies , This represents the expectation operation and follows a cyclically symmetric complex Gaussian distribution. ; Modeling of received signals from an integrated IR receiver and an Eve malicious eavesdropper, including: ； ； in, The received signal of the IR integrated receiver in the l-th time slot. For Eve's malicious eavesdropper, the received signal in the l-th time slot, The reflection coefficient matrix of the TC transmission construction area. The phase shift vector for the TC transmission construction region. The unit corresponding to the TC transmission construction area phase shift, This indicates the diagonalization operation. The reflection coefficient matrix of the CJ cooperative interference zone. The phase shift vector of the CJ cooperative interference region. Units corresponding to the CJ cooperative interference zone phase shift, To transmit the sensing sub-signal of the TC transmission construction area, The interference signal modulated by the CJ cooperative interference zone. This refers to the received noise at the integrated IR receiver. For Eve's malicious eavesdropper, received noise; Achievable secure rate for decoding confidential master signals using an integrated IR receiver Modeling, including: ； ； ； in, The achievable rate for decoding the main signal s in an integrated IR receiver. The achievable rate at which Eve's malicious eavesdropper receives the main signal s; Equivalent channel matrix from the TC transmission construction area to the IR integrated receiver, and equivalent channel matrix from the CJ cooperative interference area to the IR. The equivalent channel matrix from the TC transmission construction area to the Eve malicious eavesdropper. Equivalent channel matrix from CJ cooperative interference zone to Eve malicious eavesdropper , Indicates conjugate transpose; This represents the noise variance received at the IR integrated receiver. The noise variance received at Eve's malicious eavesdropper's location; Modeling the achievable rate of decoding secondary signals in an integrated IR receiver, including: decoding the confidential primary signal. Then, first subtract the main signal, then decode the secondary signal c. When the time slot ratio of the main signal to the secondary signal... Based on the maximum ratio combining principle, the signal-to-interference-plus-noise ratio (SIR) of the decoded secondary signal by the IR integrated receiver is calculated, and the achievable rate of the decoded secondary signal by the IR integrated receiver is calculated based on the SIR of the decoded secondary signal, as shown in the following formula: ； ； in, The signal-to-interference-plus-noise ratio (SIR) of the sub-signal decoded by the IR integrated receiver.

5. The method for partitioned RIS collaborative assisted symbiotic secure communication according to any one of claims 1-4, characterized in that, The joint optimization problem described in step three is expressed as: ； Among them, the achievable secure rate for decoding confidential master signals using an integrated IR receiver. As the objective function, This is the minimum rate threshold constraint for the subsystem. Phase shift constraints for the TC transmission construction region, The unit corresponding to the TC transmission construction area phase shift, Phase shift constraints for the CJ cooperative interference region Units corresponding to the CJ cooperative interference zone phase shift, For PTx main transmitter transmit power constraints, This represents the transmit beamforming vector of the PTx main transmitter. This is the minimum rate threshold for decoding sub-signals in an IR integrated receiver. This represents the peak power of the PTx master transmitter.

6. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 5, characterized in that, The joint optimization problem is decoupled into a PTx master transmitter transmit beamforming optimization subproblem and a RIS reconfigurable smart surface phase shift optimization subproblem, including: S3.

1. By introducing a simplified power term, the logarithms in the objective function are transformed into a linear form by subtracting them. The first set of auxiliary variables is introduced to constrain the logarithmic term in the objective function, resulting in the first set of inequality constraints. Based on the first set of inequality constraints, a reconstruction optimization problem with a separable structure and a linear objective function is constructed. S3.2 Construction of the PTx main transmitter transmit beamforming optimization subproblem: By fixing the phase shift of the RIS reconfigurable smart surface in the reconfiguration optimization problem, the initial subproblem of PTx main transmitter transmit beamforming optimization is obtained. The SDR method is used to handle the non-convex constraint of the RIS phase shift. and After obtaining the processed phase shift convex constraints, a second set of auxiliary variables is introduced to perform an equivalent transformation on the first set of inequality constraints to obtain a second set of inequality constraints. The non-convex constraints in the second set of inequality constraints are processed using the SCA method to obtain a third set of inequality constraints. Based on the processed phase shift convex constraints, the convex constraints in the second set of inequality constraints, and the third set of inequality constraints, the final sub-problem of PTx main transmitter transmit beamforming optimization is constructed by combining the initial sub-problem of PTx main transmitter transmit beamforming optimization. S3.3 Construction of the RIS Reconfigurable Smart Surface Phase Shift Optimization Subproblem: Fixing the transmit beam vector of the PTx master transmitter in the reconfiguration optimization problem, we obtain the initial subproblem of the RIS reconfigurable smart surface phase shift optimization. Introducing a third set of auxiliary variables to perform equivalent transformations on the first set of inequality constraints, we obtain a fourth set of inequality constraints. The non-convex constraints in the fourth set of inequality constraints are processed using the SCA method to obtain a fifth set of inequality constraints. Based on the convex constraints in the fourth set of inequality constraints and the fifth set of inequality constraints, combined with the initial subproblem of the RIS reconfigurable smart surface phase shift optimization, we construct the final subproblem of the RIS reconfigurable smart surface phase shift optimization.

7. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 6, characterized in that, The implementation method of step S3.1 includes: S3.11, Simplify the power term: Let the received power of the main signal at the IR terminal be: The interference and noise power of the main signal at the IR terminal are: The received power of the main signal at the Eve terminal is: The interference and noise power of the main signal at the Eve terminal is: ; S3.

12. Transform the objective function into a linear form by subtracting the logarithms, and introduce the first set of auxiliary variables. For the logarithmic terms in the objective function , and Apply constraints: ； therefore, , The non-convex constraint is transformed into the first set of inequality constraints; S3.

13. Based on the first set of inequality constraints, construct a reconstruction optimization problem with a separable structure and a linear objective function: 。 8. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 7, characterized in that, The implementation method for step S3.2 is as follows: S3.

21. The phase shift of the RIS reconfigurable smart surface in the fixed reconfiguration optimization problem yields the initial sub-problem for optimizing the transmit beamforming of the PTx master transmitter: ； S3.22, Introduce the second set of auxiliary variables By performing an equivalent transformation on the first set of inequality constraints, we obtain the second set of inequality constraints: （12）； （13）； ； S3.

23. The SCA method is used to process the non-convex constraints (12b), (12c), (13a), and (13d) in the second set of inequality constraints to obtain the third set of inequality constraints: ； ； in, , , , ; As the initial value, , , This is the solution obtained in the nth iteration. This indicates the operation of taking the real part; S3.

24. Based on the convex constraints in the second set of inequalities and the third set of inequalities, and combined with the initial sub-problem of PTx main transmitter transmit beamforming optimization, construct the final sub-problem of PTx main transmitter transmit beamforming optimization: 。 9. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 8, characterized in that, The implementation method for step S3.3 is as follows: S3.

31. By fixing the transmit beam vector of the PTx master transmitter in the reconfiguration optimization problem, we obtain the initial sub-problem of RIS reconfigurable smart surface phase shift optimization: ； S3.

32. Using the SDR method to handle non-convex constraints of RIS phase shift. and :make , Then the phase shift mode constraint is transformed into a convex constraint: , It is a positive semi-definite matrix. , , , Represents the rank operation of a matrix; S3.33, Introduce a third set of auxiliary variables By performing an equivalent transformation on the first set of inequality constraints, we obtain the fourth set of inequality constraints: ； ； ； in, Represents the trace operation of a matrix. , , , ; S3.

34. The SCA method is used to process the non-convex constraints in the fourth set of inequality constraints to obtain the fifth set of inequality constraints: ； S3.

35. Based on the convex constraints in the fourth set of inequalities and the fifth set of inequalities, and combined with the initial sub-problem of RIS reconfigurable smart surface phase shift optimization, construct the final sub-problem of RIS reconfigurable smart surface phase shift optimization: 。 10. The method for partitioned RIS collaborative assisted symbiotic secure communication according to claim 9, characterized in that, The solution is obtained using the SOCP second-order cone programming resource allocation algorithm based on alternating optimization, including: The final subproblem of beamforming optimization for the T1 and PTx main transmitters is in SOCP form and is solved using the CVX toolbox in MATLAB. The final subproblem of phase shift optimization for T2 and RIS reconfigurable smart surfaces is further relaxed into a convex semidefinite programming form using the SDR method, thus removing constraints. and Then use the CVX tool to solve it. If the solution is obtained... Matrix and If the rank of the matrix is ​​1, then for Matrix and The matrix is ​​subjected to singular value decomposition to obtain the solution of the phase shift vector of the TC transmission construction region. Solution of the phase shift vector of the CJ cooperative interference region Otherwise, use Gaussian randomization to obtain a solution that meets the conditions; then transfer the solution of the phase shift vector of the constructed region. Solution of phase shift vector of cooperative interference region Projecting onto the unit modulus constraint set yields a suboptimal solution. and To ensure the convergence of the algorithm, the following strategy is used for updates: ； T3. Repeat T1-T2 until the algorithm converges.

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