A joint secure and covert communication method based on dynamic mode switching mechanism

Abstract

The application discloses a kind of joint security and covert communication methods based on dynamic mode switching mechanism, which first executes scene task loading and parameter initialization, obtains the task parameter set and channel state information of current transmission period, obtains the reflection coefficient matrix of intelligent reflecting surface.Secondly, according to the channel state information and the reflection coefficient matrix, the candidate parameter set of security communication mode and covert communication mode is generated respectively, and the executable strategy set and the performance evaluation result of two modes are obtained.Finally, according to the performance evaluation result of security communication mode and the preset switching threshold, dynamic switching is carried out between security communication mode and covert communication mode, the system performance of safety rate calculation current period is obtained, and the task parameter of next transmission period is updated.The application solves the problem that security communication and covert communication are usually designed separately, and it is difficult to unify and coordinate control according to real-time channel state, exposure risk and transmission demand.

Description

Technical Field

[0001] This invention relates to the field of wireless communication security technology, and in particular to a joint confidentiality and covert communication method based on a dynamic mode switching mechanism. Background Technology

[0002] With the widespread deployment of wireless communication systems, communication signals propagate in open space, making them vulnerable to security threats such as eavesdropping, detection, interception, and interference. Traditional physical layer security technologies typically focus on secure communication, with the basic idea being to increase the system's security capacity by improving the channel quality difference between legitimate and illegitimate receivers, thereby reducing the risk of confidential information being illegally intercepted.

[0003] On the other hand, covert communication technology focuses more on the undetectability of the communication behavior itself. Its goal is not only to prevent the information content from being recovered, but also to minimize the ability of unauthorized monitoring terminals to determine whether "communication behavior exists." Such technologies typically use methods such as power control, artificial noise injection, or detection error constraints to make it difficult for unauthorized monitoring terminals to reliably distinguish noise from real transmitted signals.

[0004] In existing technologies, secure communication and covert communication are mostly designed and implemented as two relatively independent technical solutions. Secure communication solutions typically use metrics such as security capacity, signal-to-noise ratio, or outage probability as optimization objectives, while covert communication solutions usually use metrics such as detection error probability, false alarm probability, or missed detection probability as primary constraints. Due to their different focuses, existing solutions often lack a unified control framework in system implementation, making it difficult to flexibly switch between the two security modes based on channel conditions, exposure risks, and service requirements.

[0005] Meanwhile, the development of smart reflector technology has provided new means to enhance wireless physical layer security. By adjusting the reflection amplitude and phase of the smart reflector, the wireless propagation environment can be reconstructed, thereby enhancing the quality of legitimate links or weakening the reception capability of illicit monitoring directions. Furthermore, cooperative jammers, by transmitting artificial noise, can further increase the uncertainty of observations from illicit monitoring ends, providing auxiliary support for covert communication. However, in existing schemes, the reflection control of the smart reflector, the power control of the legitimate transmitter, and the operating state of the cooperative jammer are often designed separately, lacking a unified coordination mechanism, resulting in insufficient overall system adaptability.

[0006] Especially in scenarios with rapidly changing channels, varying obstructions, non-line-of-sight propagation, or significant fluctuations in environmental statistical characteristics, if the system consistently employs a single secure communication mode or a single covert communication mode, the following problems may arise: when the legitimate link is dominant, the system fails to fully utilize favorable channel conditions to improve secure transmission efficiency; and when illegal detection capabilities increase, the system struggles to switch to a transmission mode more suitable for suppressing detectability in a timely manner. Furthermore, existing solutions typically focus on single-link judgment and single-step execution control, lacking comprehensive utilization of candidate parameters, dual-mode performance, execution results, and historical feedback information, making it difficult to achieve continuous and stable joint secure transmission in complex wireless environments.

[0007] Therefore, it is necessary to propose a joint secure and covert communication method that can coordinate secure and covert communication under a unified framework, jointly configure intelligent reflectors and cooperative jammers, and dynamically switch modes based on real-time channel status and feedback results, so as to improve the overall security performance, environmental adaptability and engineering practical value of the system in complex wireless environments. Summary of the Invention

[0008] To address the problems in existing technologies where secure and covert communication are typically designed separately, making unified coordination and control based on channel conditions and exposure risks difficult, and lacking a linkage mechanism between intelligent reflector reflection control, legitimate transmitter transmission control, and cooperative jammer operation, resulting in insufficient system adaptability and limited overall security performance in complex wireless environments, this invention provides a joint secure and covert communication method based on intelligent reflectors. This invention introduces intelligent reflectors for controllable reconstruction of the wireless propagation environment and combines this with the artificial noise assistance capability of cooperative jammers. Based on channel state information, candidate transmission parameter sets are constructed for both secure and covert communication modes. The communication performance of the two modes is evaluated, and dynamic switching between secure and covert communication modes is performed according to preset switching rules, thereby selecting the more suitable transmission method under different channel conditions and risk levels. After determining the target communication mode, the reflection parameters of the intelligent reflector, the transmission parameters of the legitimate transmitter, and the operating state of the cooperative jammer are coordinated and controlled. The control parameters for the next transmission cycle are updated based on the reception feedback and mode execution results of the current transmission cycle, forming a closed-loop adaptive adjustment mechanism for continuous transmission. This improves the system's security, concealment, and transmission reliability in complex wireless scenarios. To achieve the above objectives, the present invention adopts the following technical solution: S01: Execute scenario task loading and parameter initialization, and obtain the task parameter set for the current transmission cycle.

[0009] S02: Based on the task parameter set, obtain the channel state information and the reflection coefficient matrix of the intelligent reflector.

[0010] S03: Based on the channel state information and the reflection coefficient matrix, generate candidate parameter sets for secure communication mode and covert communication mode respectively, and perform feasibility screening to obtain the executable strategy set for secure communication mode and covert communication mode.

[0011] S04: Calculate the performance evaluation results of the secure communication mode based on the set of executable strategies for the secure communication mode.

[0012] S05: Based on the set of executable strategies for covert communication mode, calculate the effective transmission capacity of legitimate links and the probability of detection errors by illegal monitoring terminals to obtain the performance evaluation results of covert communication mode.

[0013] S06: Based on the performance evaluation results of the secure communication mode and the preset switching threshold, determine whether to switch the transmission mode, dynamically switch between secure communication mode and covert communication mode, and determine and execute the target communication mode.

[0014] S07: Based on the target communication mode and the detection error probability at the monitoring end, obtain the overall security rate, and calculate the system performance for the current period based on the performance evaluation results of the secure communication mode and the covert communication mode.

[0015] S08: Based on system performance and security rate, obtain the reception feedback and mode execution result of the current transmission cycle, and update the control parameters of the next transmission cycle based on the reception feedback and mode execution result, so as to feed back the updated control parameters to step S01 and enter the next round of adaptive iteration.

[0016] The beneficial effects of this invention are as follows: This invention adopts a technical solution that combines intelligent reflector-assisted transmission, dynamic switching between secure and covert communication modes, cooperative jamming, and cross-transmission cycle feedback updates. This solves the problems in existing technologies where secure and covert communication are typically designed separately, making it difficult to coordinate and control them in a unified manner based on real-time channel conditions, exposure risks, and transmission requirements. It also addresses the lack of linkage between intelligent reflector reflection control, legitimate transmitter transmission control, and cooperative jamming control, as well as the system's insufficient adaptability in complex wireless environments. This results in more accurate characterization of the wireless propagation environment, flexible selection of secure or covert communication modes based on channel conditions, enhanced transmission effectiveness in legitimate directions, suppression of interception or detection by illegal monitoring terminals, and improved system security, covertness, and transmission reliability. Furthermore, by updating the control parameters for the next transmission cycle through received feedback, it achieves closed-loop adaptive adjustment during continuous transmission. Therefore, this invention possesses stronger scene adaptability, more stable comprehensive security performance, and higher engineering application value in complex wireless environments. Attached Figure Description

[0017] Figure 1This is a scene model diagram of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 The graph shows a performance comparison of the interruption probability as a function of low transmit signal-to-noise ratio. Figure 4 The graph shows a performance comparison of the interruption probability as a function of high transmit signal-to-noise ratio. Figure 5 The graph shows a performance comparison of traversal rate as a function of low transmit signal-to-noise ratio. Figure 6 The simulation comparison graph shows the performance of traversal rate as a function of high transmit signal-to-noise ratio. Figure 7 This is a simulation graph showing how the safety rate changes with the switching threshold. Detailed Implementation

[0018] Example 1: This invention provides a joint secure and covert communication method based on a dynamic mode switching mechanism. More specifically, it relates to a physical layer secure transmission method that achieves coordinated switching between secure and covert communication modes in complex wireless propagation environments by combining channel state awareness, candidate parameter generation, dual-mode performance evaluation, mode switching decision, parameter optimization execution, and feedback updates.

[0019] This embodiment provides a scenario for joint secure and covert communication based on a smart reflective surface, such as... Figure 1 As shown, the communication scenario includes a legitimate transmitter, a legitimate receiver, an illegal monitoring unit, a cooperative jammer, and a smart reflector. The legitimate transmitter transmits signals, the legitimate receiver receives signals, the illegal monitoring unit listens for or detects communication activities, the cooperative jammer transmits artificial noise in covert communication mode, and the smart reflector reconstructs the wireless propagation environment by adjusting the reflection parameters of each reflection unit to enhance transmission in the legitimate direction and suppress reception in the illegal monitoring direction. In this embodiment, the system constructs candidate transmission strategies for both secure and covert communication modes based on channel state information and evaluates the performance of both modes. When current channel conditions are more favorable for improving secure transmission capabilities, the system selects the secure communication mode; when the current environment requires reducing the probability of communication activities being detected, the system selects the covert communication mode. After determining the target communication mode, the control unit coordinates the reflection parameters of the smart reflector, the transmission parameters of the legitimate transmitter, and the operating status of the cooperative jammer, and updates the control parameters for the next cycle based on the reception feedback of the current transmission cycle, thereby achieving dynamic adjustment for continuous transmission. Based on the above system scenario, Embodiment 2 will further explain the method execution flow of the present invention.

[0020] Example 2: like Figure 2 As shown, without altering the aforementioned inventive concept, the joint confidentiality and covert communication method can be refined into eight interconnected execution steps. These eight execution steps illustrate the specific implementation of the present invention in scenarios involving intelligent reflective surface assistance, dynamic switching of security modes, and cooperative interference control, and do not constitute an additional limitation on the scope of protection of the claims.

[0021] Step S01: Scene task loading and parameter initialization At the beginning of each transmission cycle, the control terminal reads the service type, preset switching threshold, power limit, number of reflection units, and historical status information of the current transmission cycle to form a set of task parameters for the current cycle.

[0022] Step S02: Channel State Information Acquisition and Reflection Coefficient Matrix Construction Based on the task parameter set, the control terminal controls the legitimate transmitter and the cooperative jammer to send training sequences, obtains the channel state information from the legitimate transmitter to the smart reflector, from the smart reflector to the legitimate receiver, from the smart reflector to the illegal monitoring terminal, and from the cooperative jammer to the smart reflector, and obtains the reflection coefficient matrix of the smart reflector.

[0023] The reflection coefficient matrix of the intelligent reflective surface is represented as follows: in, This represents the reflection coefficient matrix of the intelligent reflective surface. This represents a diagonal matrix consisting of diagonal elements. This indicates the number of reflective units in the intelligent reflective surface. Indicates the first The amplitude coefficient of each reflecting unit, Indicates the first Phase shift coefficient of each reflecting unit, Represents the imaginary unit. Represents the natural constant.

[0024] Step S03: Generation of dual-mode candidate parameters and selection of executable strategies Generation of candidate parameters for secure communication mode: Based on the reflection coefficient matrix, candidate strategies for secure communication mode are constructed. In this mode, the cooperative jammer remains silent. Based on the equivalent cascaded channel gain of the link from the legitimate transmitter to the legitimate receiver enhanced by the intelligent reflector, and combined with the task parameter set, a set of candidate parameters for secure communication mode is generated. The equivalent cascaded channel gain of the link from the legitimate transmitter to the intelligent reflector to the legitimate receiver can be expressed as: in, This represents the channel vector from the smart reflector to the legitimate receiver. This represents the channel vector from the legitimate transmitter to the smart reflector. Represents the channel vector The One element, Represents the channel vector The One element, This indicates the transpose operation. This represents the reflection coefficient matrix of the intelligent reflective surface. Indicates the first The amplitude coefficient of each reflecting unit, Indicates the first Phase shift coefficient of each reflecting unit, This represents the modulo operation. This indicates the number of reflective units in the intelligent reflective surface.

[0025] Candidate parameter generation for covert communication mode: Based on the reflection coefficient matrix, candidate strategies for covert communication mode are constructed. In this mode, the cooperative jammer is activated and transmits artificial noise to increase the uncertainty of observations from the illegal monitoring end. The equivalent cascaded channel gain of the cooperative jammer-intelligent reflector-legitimate receiver link is combined with the artificial noise and the task parameter set to generate the candidate parameter set for covert communication mode. The equivalent cascaded channel gain of the cooperative jammer-intelligent reflector-legitimate receiver link can be expressed as: in, This represents the channel vector from the smart reflector to the legitimate receiver. This represents the channel vector from the cooperative jammer to the smart reflector. Represents the channel vector The One element, Represents the channel vector The One element, This indicates the transpose operation. This represents the reflection coefficient matrix of the intelligent reflective surface. Indicates the first The amplitude coefficient of each reflecting unit, Indicates the first Phase shift coefficient of each reflecting unit, This represents the modulo operation. This indicates the number of reflective units in the intelligent reflective surface.

[0026] And the transmission power of the cooperative jammer In the interval The distribution is uniformly distributed on the upper surface, and its probability density function is: in, The probability density function representing the transmit power of the cooperative jammer; Indicates the transmit power of the cooperative jammer; Indicates the power value variable; The maximum allowable transmission power for use as a jammer.

[0027] The control unit performs feasibility screening on the candidate parameter sets for secure and covert communication modes based on reception reliability and power budget constraints, thereby obtaining the corresponding executable strategy sets for each. The reason for employing a dual-mode candidate parameter generation and executable strategy screening technique is that the optimization objectives for secure and covert communication modes differ. The former focuses more on the difference in reception capabilities between legitimate and illegitimate links, while the latter focuses more on reducing the detection capability of unauthorized monitoring terminals on communication behavior. Therefore, it is necessary to construct two types of candidate strategies separately.

[0028] Step S04: Performance Evaluation of Secure Communication Mode Based on the executable policy set of the secure communication mode, the receiving performance of the legitimate receiver and the illegitimate monitoring end under the secure communication mode is evaluated. The received signal of the legitimate receiver under the secure communication mode can be represented as: in, Indicating that the legitimate receiver in secure communication mode is at the [number]th [time / location] The received signal at each sampling time, This represents the channel vector from the smart reflector to the legitimate receiver. This represents the reflection coefficient matrix of the intelligent reflective surface. This represents the channel vector from the legitimate transmitter to the smart reflector. This represents the path loss of the link from the legitimate sender to the smart reflector to the legitimate receiver. This indicates that the legitimate sender is at the 1st rank. The signal sent at each sampling time This indicates a legitimate noise signal at the receiver side. This indicates the transpose operation. This represents the square root operation.

[0029] The signal-to-noise ratio (SNR) of a legitimate receiver and an illegitimate monitoring receiver in secure communication mode can be expressed as follows: in, This represents the signal-to-noise ratio (SNR) of the legitimate receiver in secure communication mode. This indicates the signal-to-noise ratio (SNR) of the unauthorized monitoring terminal under secure communication mode. Indicates the system's transmit power. This represents the channel vector from the intelligent reflector to the illegal monitoring terminal. This represents the path loss of the link between the legitimate sender, the smart reflector, and the illegitimate monitor. Indicates the legitimate receiver end-to-end noise power. This indicates the noise power at the illegal monitoring end.

[0030] The rates of legitimate receivers and illegitimate monitoring devices, as well as the instantaneous security capacity, can be further expressed as: in, This indicates the data rate of the legitimate receiving end in secure communication mode. This indicates the data rate that can be obtained by an unauthorized monitoring device under secure communication mode. This represents the signal-to-noise ratio (SNR) of the legitimate receiver in secure communication mode. This indicates the signal-to-noise ratio (SNR) of the unauthorized monitoring terminal under secure communication mode. Indicates instantaneous security capacity. Indicates system bandwidth. This indicates taking the larger of the result within the parentheses and zero.

[0031] Whether a secure communication mode is suitable for the current transmission environment depends on whether the legitimate receiver has sufficient channel advantage over the illegitimate monitoring end. Therefore, it is necessary to quantitatively evaluate the received signals, signal-to-noise ratio, data rate, and instantaneous security capacity of the legitimate receiver and the illegitimate monitoring end, so as to provide a basis for subsequent mode switching decisions.

[0032] Step S05: Performance Evaluation of Covert Communication Mode Based on the executable strategy set of covert communication mode, the effective transmission capability of the legitimate receiver and the detection error probability of the illegitimate monitoring end under covert communication mode are evaluated. The received signal of the legitimate receiver under covert communication mode can be represented as: in, This represents the channel vector from the smart reflector to the legitimate receiver. This represents the channel vector from the legitimate transmitter to the smart reflector. This represents the channel vector from the cooperative jammer to the smart reflector. This indicates that the legitimate sender is at the 1st rank. The signal sent at each sampling time This represents the path loss of the link from the legitimate sender to the smart reflector to the legitimate receiver. This represents the path loss of the cooperative jammer-smart reflector-legitimate receiver link. Indicates the cooperative jammer in the first Interference signals sent at each sampling time, This indicates a legitimate receiver end-to-end noise signal.

[0033] The signal-to-noise ratio (SNR) of a legitimate receiver in covert communication mode can be expressed as: The data rate of a legitimate receiver in covert communication mode can be expressed as: The probability of detection error at an illegal monitoring terminal can be expressed as: in, This represents the signal-to-noise ratio (SNR) of the legitimate receiver in covert communication mode. This indicates the transmission power of a legitimate transmitter. This represents the self-interference cancellation coefficient. Indicates the transmit power of the cooperative jammer. This indicates the data rate of the legitimate receiver in covert communication mode. Indicates the probability of detection error. This represents the probability of a false alarm. Indicates the probability of a missed detection. This represents the channel vector from the smart reflector to the legitimate receiver. This represents the channel vector from the legitimate transmitter to the smart reflector. This represents the channel vector from the cooperative jammer to the smart reflector. This represents the path loss of the link from the legitimate sender to the smart reflector to the legitimate receiver. This represents the path loss of the cooperative jammer-smart reflector-legitimate receiver link. This indicates the valid receiver end-noise power.

[0034] Similarly, covert communication mode must not only ensure that the legitimate receiving end has basic data receiving capabilities, but also maximize the detection uncertainty of the illegitimate monitoring end. Therefore, it is necessary to simultaneously evaluate the effective transmission capability of the legitimate link and the detection error probability of the illegitimate monitoring end in order to comprehensively judge whether the mode can meet both transmission and covert requirements under the current conditions.

[0035] Step S06: Communication mode switching judgment Based on the performance evaluation results of the secure communication mode, the control terminal compares the instantaneous secure capacity with the preset switching threshold and generates a mode switching control command. When the instantaneous secure capacity is less than the preset switching threshold, it switches to the covert communication mode; otherwise, it maintains the secure communication mode. It dynamically switches between the secure communication mode and the covert communication mode to determine the target communication mode.

[0036] Using a single secure transmission mode is difficult to adapt to complex scenarios such as rapidly changing channels, environmental obstruction, and fluctuations in illegal monitoring capabilities. Therefore, it is necessary to make real-time decisions based on performance evaluation results and preset thresholds, and flexibly switch between secure communication mode and covert communication mode to improve the system's adaptability to environmental changes.

[0037] Step S07: Safety Rate Adjustment and Traversal Rate Evaluation Based on the target communication mode and the detection error probability at the detection end, the security rate under the current transmission conditions is calculated, and then the overall security performance of the system is evaluated. The security rate can be expressed as: in, This indicates the probability of interruption in secure communication mode. This indicates the probability of a detection error.

[0038] Furthermore, based on the performance evaluation results of the secure communication mode and the covert communication mode, the traversal rate for the current cycle is calculated, thereby evaluating the system performance for the current cycle. The traversal rate can be expressed as: in, This indicates the probability of interruption in secure communication mode. This indicates the data rate of the legitimate receiver in covert communication mode. Indicates instantaneous security capacity.

[0039] The reason for using both the security rate and the ergodic rate is that the security rate characterizes the system's effective secure transmission capability under the conditions of satisfying confidentiality and concealment constraints, while the ergodic rate characterizes the system's average transmission efficiency in a random channel environment. Because it involves the dynamic switching between secure and concealed communication modes, a single indicator is insufficient to fully reflect the system's current operating state. By jointly measuring the target mode using both the security rate and the ergodic rate, the overall performance of the system can be accurately evaluated.

[0040] Step S08: Receive feedback and perform cross-cycle updates After the current transmission cycle ends, the legitimate receiver reports the successful reception status, interruption probability, and mode execution result. The control unit assesses the exposure risk and transmission efficiency of the current system based on the security rate and traversal rate of the current cycle. When the security rate shows a downward trend, the control unit lowers the preset switching threshold for the next transmission cycle by a preset step size, reduces the proportion of the legitimate transmitter's transmission power in the parameter initialization value, and increases the transmission power of the cooperative jammer to enhance artificial noise, thereby improving the trigger probability and interference capability of the covert communication mode. When the security rate meets the service requirements but the traversal rate is lower than the set rate threshold, the control unit increases the preset switching threshold for the next transmission cycle by a preset step size, and increases the proportion of the legitimate transmitter's transmission power in the parameter initialization value to tend to trigger the high-transmission-efficiency secure communication mode. At the same time, if a single communication mode is frequently interrupted in multiple consecutive cycles, the control unit adjusts the strategy invocation order in the next cycle, prioritizing the parameter evaluation of another mode, thus forming a closed-loop adaptive control mechanism for continuous transmission cycles.

[0041] Example 3: Based on the system scenario described in Embodiment 1 and the method flow described in Embodiment 2, this embodiment further explains the specific execution methods of the secure communication mode and the covert communication mode.

[0042] When the system determines that a secure communication mode is to be used, the control terminal configures the reflection parameters of the intelligent reflector based on the current channel state information, thereby increasing the equivalent channel gain in the direction of the legitimate receiver and controlling the cooperative jammer to remain silent. This enhances the reception capability of the legitimate receiver and reduces the information acquisition capability of the illegitimate monitoring end. In this mode, the system focuses on the difference in reception capability between the legitimate receiver and the illegitimate monitoring end to improve secure transmission performance. When the system determines that a covert communication mode is to be used, the control terminal configures the signal transmission parameters and the reflection parameters of the intelligent reflector while controlling the cooperative jammer to send artificial noise to increase the difficulty for the illegitimate monitoring end to determine the presence of communication. In this mode, the system focuses on reducing the detection capability of the illegitimate monitoring end and ensuring the basic reception performance of the legitimate receiver while meeting the covert transmission requirements. In this embodiment, the system does not use a single fixed communication mode, but dynamically switches between secure and covert communication modes based on the channel state, mode performance evaluation results, and preset switching conditions. By coordinating the reflection parameters of the intelligent reflector, the transmission parameters of the legitimate transmitter, and the operating status of the cooperative jammer, the system's adaptability and secure transmission capability in different wireless environments can be improved. After a transmission cycle ends, the control terminal updates the control parameters for the next transmission cycle based on the feedback from the legitimate receiver, so as to achieve dynamic adjustment and closed-loop control during continuous transmission.

[0043] Example 4: In the performance analysis graph of the instance, analysis refers to the accurate results of numerical calculation, while simulation refers to Monte Carlo simulation of the actual situation.

[0044] Combined with appendix Figure 3 and attached Figure 4 It can be seen that in both low and high signal-to-noise ratio (SNR) regions, the interruption probability of the present invention is lower than that of traditional single secure communication schemes, and the decreasing trend is more pronounced. This indicates that the present invention, by dynamically switching between secure and covert communication modes, can promptly select a more suitable transmission method based on channel conditions and environmental changes, thereby improving the transmission reliability of the system in different scenarios.

[0045] Combined with appendix Figure 5 and attached Figure 6 It can be seen that in the low-power range, the proposed solution, even with the introduction of a mode-switching mechanism, maintains good average transmission efficiency without significant performance loss. In the high-power range, the traversal rate of the proposed solution can continue to increase, demonstrating superior growth characteristics compared to traditional single-mode secure communication schemes. This indicates that the joint mechanism proposed in this invention can ensure both security and transmission efficiency, and to some extent alleviate the performance limitations of traditional schemes under high-power conditions.

[0046] Combined with appendix Figure 7 It can be seen that changes in the switching threshold directly affect the probability distribution of the system entering secure communication mode and covert communication mode, thus affecting the overall performance of security rate. This indicates that the present invention can achieve a flexible balance between transmission efficiency, confidentiality, and covertness by adjusting the switching threshold, thereby adapting to the differentiated security level and communication performance requirements of different application scenarios.

[0047] In summary, this invention does not simply superimpose secure communication and covert communication, but rather constructs a unified dynamic secure transmission framework through threshold decision-making, intelligent reflective surface reflection control, cooperative jamming mechanism, and feedback update mechanism. Compared to traditional single secure communication schemes, this invention has stronger scene adaptability and more stable overall security performance in complex wireless environments.

Claims

1. A joint confidential and covert communication method based on a dynamic mode switching mechanism, characterized in that, Includes the following steps: S1: Perform scenario task loading and parameter initialization, and obtain the task parameter set for the current transmission cycle; S2: Based on the task parameter set, obtain the channel state information and get the reflection coefficient matrix of the intelligent reflector; S3: Based on the channel state information and the reflection coefficient matrix, generate candidate parameter sets for secure communication mode and covert communication mode respectively, and perform feasibility screening to obtain the executable strategy set for secure communication mode and covert communication mode; S4: Calculate the performance evaluation results of the secure communication mode and the covert communication mode based on the executable policy set of the secure communication mode and the executable policy set of the covert communication mode, respectively. S5: Based on the performance evaluation results of the secure communication mode and the preset switching threshold, determine whether to switch the transmission mode, dynamically switch between the secure communication mode and the covert communication mode, determine and execute the target communication mode, obtain the overall security rate, and calculate the system performance of the current period. S6: Based on system performance and security rate, obtain the reception feedback and mode execution results of the current transmission cycle, and update the task parameters for the next transmission cycle based on the reception feedback and mode execution results.

2. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 1, characterized in that, The specific implementation of step S1 is as follows: at the beginning of each transmission cycle, the control terminal reads the service type, preset switching threshold, power limit, number of reflection units and historical status information of the current transmission cycle to form a set of task parameters for the current cycle.

3. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 2, characterized in that, The specific implementation of step S2 is as follows: based on the task parameter set, the control terminal controls the legitimate transmitter and the cooperative jammer to send training sequences, obtain the channel state information from the legitimate transmitter to the smart reflector, from the smart reflector to the legitimate receiver, from the smart reflector to the illegal monitoring terminal, and from the cooperative jammer to the smart reflector, and obtain the reflection coefficient matrix of the smart reflector; The reflection coefficient matrix of the intelligent reflective surface is represented as follows: in, This represents a diagonal matrix consisting of diagonal elements. This indicates the number of reflective units in the intelligent reflective surface. Indicates the first The amplitude coefficient of each reflecting unit, Indicates the first Phase shift coefficient of each reflecting unit, Represents the imaginary unit. Represents the natural constant.

4. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 3, characterized in that, In step S3, the candidate parameter sets for secure communication mode and covert communication mode are generated based on the channel state information and the reflection coefficient matrix, respectively. The specific implementation is as follows: Generation of candidate parameters for secure communication mode: Based on the reflection coefficient matrix, candidate strategies for secure communication mode are constructed. In this mode, the cooperative jammer remains silent, and the intelligent reflector enhances the equivalent cascaded channel gain of the link from the legitimate transmitter to the legitimate receiver. Combined with the task parameter set, a set of candidate parameters for secure communication mode is generated. The equivalent cascaded channel gain of the legitimate transmitter-smart reflector-legitimate receiver link is expressed as: in, This represents the channel vector from the smart reflector to the legitimate receiver. This represents the channel vector from the legitimate transmitter to the smart reflector. Represents the channel vector The One element, Represents the channel vector The One element, This indicates the transpose operation. Indicates the first The amplitude coefficient of each reflecting unit, Indicates the first Phase shift coefficient of each reflecting unit, This represents the modulo operation; Candidate parameter generation for covert communication mode: Based on the reflection coefficient matrix, candidate strategies for the covert communication mode are constructed. In this mode, the cooperative jammer is activated and transmits artificial noise. The equivalent cascaded channel gain of the cooperative jammer-intelligent reflector-legitimate receiver link is combined with the artificial noise and the task parameter set to generate the candidate parameter set for the covert communication mode. The equivalent cascaded channel gain of the cooperative jammer-intelligent reflector-legitimate receiver link is expressed as: in, This represents the channel vector from the cooperative jammer to the smart reflector. Represents the channel vector The One element; And the transmission power of the cooperative jammer In the interval Uniformly distributed on top, transmission power The probability density function is: in, The probability density function representing the transmit power of the cooperative jammer; Indicates the transmit power of the cooperative jammer; Indicates the power value variable; The maximum allowable transmission power for use as a jammer.

5. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 4, characterized in that, In step S3, the feasibility screening specifically involves: based on the candidate parameter set for secure communication mode and the candidate parameter set for covert communication mode, the control end performs feasibility screening on the candidate strategies for the two sets according to the reception reliability constraints and power budget constraints, thereby obtaining the executable strategy set for secure communication mode and the executable strategy set for covert communication mode respectively.

6. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 5, characterized in that, In step S4, the performance evaluation of the secure communication mode is as follows: Based on the executable policy set of the secure communication mode, the receiving performance of the legitimate receiver and the illegitimate monitoring end under the secure communication mode is evaluated. The received signal of the legitimate receiver under the secure communication mode is represented as follows: in, Indicating that the legitimate receiver in secure communication mode is at the [number]th [time / location] The received signal at each sampling time, This represents the path loss of the link from the legitimate sender to the smart reflector to the legitimate receiver. This indicates that the legitimate sender is at the 1st rank. The signal sent at each sampling time This indicates a legitimate noise signal at the receiving end. The signal-to-noise ratio (SNR) of a legitimate receiver and an illegitimate monitoring receiver in secure communication mode are expressed as follows: in, This represents the signal-to-noise ratio (SNR) of the legitimate receiver in secure communication mode. This indicates the signal-to-noise ratio (SNR) of the unauthorized monitoring terminal under secure communication mode. Indicates the system's transmit power. This represents the channel vector from the intelligent reflector to the illegal monitoring terminal. This represents the path loss of the link between the legitimate sender, the smart reflector, and the illegitimate monitor. Indicates the legitimate receiver end-to-end noise power. This indicates the noise power of an illegally monitored end. The rates of legitimate receivers and illegitimate monitoring devices, as well as the instantaneous security capacity, are expressed as follows: ， in, This indicates the data rate of the legitimate receiving end in secure communication mode. This indicates the data rate that can be obtained by an unauthorized monitoring device under secure communication mode. Indicates instantaneous security capacity. Indicates system bandwidth. This indicates taking the larger of the result within the parentheses and zero.

7. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 6, characterized in that, In step S4, the performance evaluation of the covert communication mode is as follows: Based on the executable strategy set of covert communication mode, the effective transmission capability of the legitimate receiver and the detection error probability of the illegitimate monitoring end under covert communication mode are evaluated. The received signal of the legitimate receiver under covert communication mode is represented as follows: in, This represents the channel vector from the cooperative jammer to the smart reflector. This represents the path loss of the cooperative jammer-smart reflector-legitimate receiver link. Indicates the cooperative jammer in the first Interference signals sent at each sampling time, This indicates a legitimate end-to-end noise signal. The signal-to-noise ratio (SNR) of a legitimate receiver in covert communication mode is expressed as: The data rate of a legitimate receiver in covert communication mode is expressed as: The probability of detection error at an illegal monitoring terminal is expressed as: in, This represents the signal-to-noise ratio (SNR) of the legitimate receiver in covert communication mode. This indicates the transmission power of a legitimate transmitter. This represents the self-interference cancellation coefficient. Indicates the transmission power of the cooperative jammer. This indicates the data rate of the legitimate receiver in covert communication mode. Indicates the probability of detection error. This indicates the probability of a false alarm. This indicates the probability of a missed detection.

8. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 7, characterized in that, The specific implementation process of step S5 is as follows: Based on the performance evaluation results of the secure communication mode, the control terminal compares the instantaneous secure capacity with the preset switching threshold and generates a mode switching control command. When the instantaneous secure capacity is less than the preset switching threshold, it switches to the covert communication mode; otherwise, it maintains the secure communication mode. It dynamically switches between the secure communication mode and the covert communication mode to determine the target communication mode. Based on the target communication mode and the detection error probability at the detection end, the security rate under the current transmission conditions is calculated, and the overall security performance of the system is evaluated. The security rate is expressed as: in, This indicates the probability of interruption in secure communication mode; Furthermore, based on the performance evaluation results of the secure communication mode and the covert communication mode, the traversal rate for the current cycle is calculated, and the system performance for the current cycle is evaluated. The traversal rate is expressed as: 。 9. The joint confidential and covert communication method based on a dynamic mode switching mechanism according to claim 8, characterized in that, In step S6, after the current transmission cycle ends, the legitimate receiver reports the successful reception status, interruption probability, and mode execution result. The control terminal updates the switching threshold, policy call order, and parameter initialization values ​​for the next transmission cycle based on the security rate and traversal rate of the current cycle, forming a closed-loop control mechanism for continuous transmission cycles, as follows: When the security rate shows a downward trend, the control terminal reduces the preset switching threshold for the next transmission cycle by a preset step size, and decreases the proportion of the transmission power of the legitimate transmitter in the parameter initialization value, while increasing the transmission power of the cooperative jammer to enhance artificial noise. When the security rate meets the service requirements but the traversal rate is lower than the set rate threshold, the control terminal increases the preset switching threshold for the next transmission cycle by a preset step size, and increases the proportion of the transmission power of the legitimate transmitter in the parameter initialization value. At the same time, if a single communication mode is frequently interrupted in multiple consecutive cycles, the control terminal adjusts the strategy invocation order in the next cycle, prioritizing the parameter evaluation of another mode, thus forming a closed-loop adaptive control mechanism for continuous transmission cycles.

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