Power resource allocation method of difunctional intelligent reflector auxiliary system

Abstract

The invention relates to the technical field of wireless communication, in particular to a power resource allocation method of a difunctional intelligent reflector auxiliary system, which comprises the following steps: a reconfigurable intelligent reflector is provided with N reflecting elements, two users are provided, and a first time slot and a second time slot are included; the malicious monitor successfully decodes the worst case of the hidden information; solving the optimization problem to obtain an optimized safety probability; the obtained final optimal solution is substituted into a target function, and the maximum system safety probability can be obtained; the method has the beneficial effects that a malicious monitor tries to detect and decode the hidden information sent by the base station and the cooperative relay user. Under the limitation of user communication reliability, power distribution coefficients under two different time slots are optimized to obtain the maximum safety probability of the system, and the safety performance of the system is improved. According to the invention, the communication safety performance of the system is improved, and the method has great application value.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a power resource allocation method for a dual-function intelligent reflector auxiliary system. Background Art

[0002] The integration of IoT technology with industrial manufacturing, communications, logistics and other industries can create huge value. The era of the Internet of Everything is approaching us at a visible speed, and application scenarios based on the IoT have become the most popular research at present. However, in the process of the rapid development of the IoT, communication security issues in various application scenarios are emerging in an endless stream. Timely detection and discovery of communication security threats or early defense are important means to combat threats.

[0003] The solution to traditional communication security is upper-layer encryption technology. However, with the continuous development of large-scale computer technology, the computing resources available to attackers are increasing, which also makes the possibility of brute-force password cracking gradually increase. In addition, encrypted data will arouse greater suspicion of attackers during transmission, and attackers will invest more resources to crack these encrypted data information that may be of extremely high value. Another way to achieve communication security is physical layer security. The inherent characteristics of the channel, such as randomness and uniqueness, are used to improve the security of the system, fundamentally ensuring that the information cannot be interpreted by illegal eavesdroppers, effectively making up for the shortcomings of the above-mentioned cryptographic security technology. However, the above two technologies still expose the communication link and cannot protect the low detectability of communication transmission, which is a very fatal problem in communication. Against this background, covert communication technology came into being. Covert communication, also known as low detection probability communication, is a new type of secure communication method. Its purpose is to prevent eavesdroppers from detecting the communication behavior between legitimate devices. It can effectively protect the security of wireless communications and has attracted great attention from domestic and foreign academic and industrial circles.

[0004] Smart reflective surface (RIS) is an artificial two-dimensional material of sub-wavelength size, usually composed of metal, dielectric and adjustable elements, which can be equivalently characterized as a radio link control circuit. RIS has a large number of low-power reflective elements, which are the core of RIS. The main function of RIS is to control the reflection phase and amplitude of the incident signal through software programming according to the communication link information fed back by signal propagation. It is essentially the adjustment of capacitance, resistance and inductance, so as to intelligently adjust the wireless environment, provide new spatial freedom for the system, achieve the purpose of enhancing the performance of wireless links, and pave the way for the realization of intelligent and programmable wireless environment. According to the channel parameters, the reflected signal is constructively added with the signal of other paths, which can enhance the power of the desired signal at the receiving end, improve the communication quality, enhance the capacity and expand the coverage. The basic idea of ​​non-orthogonal multiple access (NOMA) is to use non-orthogonal transmission at the transmitting end and achieve correct demodulation through the serial interference cancellation (SIC) receiver at the receiving end, which solves the problem of spectrum resource shortage to a certain extent. Compared with traditional orthogonal multiple access technology, the significant feature of NOMA is that it allows multiple users to transmit different superimposed signals on the same spectrum and time resources through superposition coding and power multiplexing, and the signals are extracted at the receiving end using continuous interference cancellation. In addition, NOMA can ensure user fairness by allocating more transmission power to remote users and less power to near users.

[0005] Although there are many existing studies on the physical layer security or covert communication of RIS-assisted NOMA systems, there is a certain gap in the research on optimizing resource allocation and improving system security in dual-function RIS-assisted NOMA systems. Summary of the invention

[0006] The purpose of the present invention is to provide a power resource allocation method for a dual-function intelligent reflector auxiliary system to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a power resource allocation method for a dual-function intelligent reflector auxiliary system, applicable to a network system including a base station, a dual-function intelligent reflector, an edge user, a cooperative relay user and a malicious monitor, except for the dual-function intelligent reflector, all devices are configured with a single antenna, and the method comprises the following steps:

[0008] The reconfigurable intelligent reflective surface has N reflective elements, the user has two, and includes a first time slot and a second time slot;

[0009] The worst case scenario in which the malicious monitor successfully decodes the hidden information is as follows: 1) In the first time slot, the malicious monitor successfully detects and decodes the hidden information; 2) In the first time slot, the malicious monitor successfully detects the hidden information but fails to decode it, but in the second time slot, the malicious monitor successfully detects and decodes the hidden information; 3) In the first time slot, the malicious monitor does not detect the hidden information; in the second time slot, the malicious monitor successfully detects and decodes the hidden information;

[0010] Solve the optimization problem and obtain the optimized safety probability;

[0011] By substituting the final optimized solution into the objective function, the maximum system safety probability can be obtained.

[0012] Preferably, in the first time slot, the channel parameters from the base station to the reconfigurable intelligent metasurface, the malicious monitor, and from the reconfigurable intelligent metasurface to the cooperative relay user, the edge user, and the malicious monitor are respectively use represents the phase matrix of RIS in the first time slot, where θ n (1) is the phase of the nth reflective element, satisfying |

[0013] The second time slot: cooperative relay users to reconfigurable smart metasurface, edge users and malicious monitors. The channel parameters from the reconfigurable smart metasurface to edge users and malicious monitors are use represents the phase matrix of RIS in the second time slot, where is the phase of the nth reflective element, satisfying

[0014] Preferably, in the first time slot, the signal received by the cooperative relay user is The signal received by the edge user is Where P s ≤P max is the transmission power of the base station, which is less than the maximum transmission power P max , v u and ν d are the additive Gaussian white noise at the cooperative relay user and the edge user, ω u and ω d are the power allocation coefficients of cooperative relay users and edge users, respectively, u and x d are the unit power information of cooperative relay users and edge users respectively. The cooperative user decodes x u The signal-to-interference-noise ratio is After serial interference elimination, the cooperative user decoding x is obtained. dThe signal-to-interference-noise ratio is Edge User Decoding x u The signal-to-interference-noise ratio is After serial interference elimination, the edge user decoding x is obtained. d The signal-to-interference-noise ratio is in and Represents the noise power.

[0015] Preferably, the probability of interruption of decoding information of the cooperative relay user and the edge user in the first time slot is:

[0016]

[0017] According to the Neyman-Pearson lemma, there are two situations when a malicious monitor receives a signal, namely It means that the malicious monitor did not detect the base station sending covert information; It represents the situation that the malicious monitor detects that the base station sends hidden information. Assuming that the malicious monitor uses a power detector to detect whether the base station sends hidden information, and considering the situation of infinite detection samples, the average receiving power of the malicious monitor in the two cases can be expressed as:

[0018]

[0019] The detection error probability of a malicious monitor is obtained as:

[0020]

[0021] Malicious surveillance detects that the base station transmits hidden information, that is, Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is The probability of successful decoding by a malicious observer is:

[0022]

[0023] Preferably, the signal received by the user at the edge of the second time slot is Where P u is the transmission power of the cooperative relay user in the second time slot, is the power allocation coefficient of edge user information and interference information, x j is the unit power interference information sent by the cooperative relay user. After perfect serial interference elimination, the edge user decodes x d The signal-to-interference-noise ratio is The signal-to-interference-to-noise ratio of edge user decoding c is At the edge of the second time slot, the user decodes x dThe interruption probability of and c is:

[0024]

[0025] Preferably, the malicious monitor receives the signal in two situations, namely It means that the malicious monitor does not detect the situation where the cooperative relay user sends covert information; It represents the situation where the malicious monitor detects the cooperative relay user sending hidden information. The average receiving power of the malicious monitor in the two cases is expressed as:

[0026]

[0027] The detection error probability of a malicious monitor is obtained as:

[0028]

[0029] Preferably, the malicious monitor detects that the remote user transmits hidden information, that is, Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is:

[0030]

[0031] The probability of successful decoding by a malicious observer is:

[0032]

[0033] Preferably, by allocating the power coefficients ω of two different time slots d and The optimization of maximizing the system safety probability can be expressed mathematically as follows:

[0034]

[0035] Preferably, the specific operations of solving the optimization problem and obtaining the optimized safety probability include:

[0036] 1) Order The objective function is to find The maximum value of To simplify the optimization, it is assumed that the phase of each time slot RIS is perfectly aligned with the legal user. The optimization problem is expressed as:

[0037]

[0038] 2) Convert the target problem into two sub-problems Q1 and Q2, then sub-problem Q1 is expressed as:

[0039]

[0040] in Sub-question Q2 is expressed as:

[0041]

[0042] in

[0043] 3) Fixed ω d ,right Optimize, for the number of iterations k = 0, 1, 2..., fix Solving subproblem Q1 yields Then fix it Solving subproblem Q2 yields Continue to iterate until you are satisfied Get the intermediate solution

[0044] 4) As the initial point, a penalty function B is defined to handle the constraints. The penalty function is expressed as:

[0045]

[0046] 5) Fixed r = r k , the optimization problem becomes solving an unconstrained optimization problem Update by gradient descent Keep updating the penalty coefficient r and iterate until it satisfies Get the final optimized solution.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The power resource allocation method of the dual-function intelligent reflector auxiliary system proposed in the present invention is applicable to a network system including a base station, a dual-function intelligent reflector, an edge user, a cooperative relay user and a malicious monitor. Except for the intelligent reflector (RIS), all devices are configured with a single antenna. In the first time slot, the base station sends its own information to the cooperative relay user and the remote user through the reflection link of the intelligent reflector; in the second time slot, the cooperative relay user will communicate with the remote user through a direct link. At the same time, the RIS modulates its own message onto the cooperative relay signal and backscatters it to the remote user. In addition, the malicious monitor attempts to detect and decode the hidden information sent by the base station and the cooperative relay user. Under the limitation of user communication reliability, the power allocation coefficients in two different time slots are optimized to obtain the maximum security probability of the system, thereby improving the security performance of the system. The present invention improves the communication security performance of the system and has great application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] See also Figure 1 The present invention provides a technical solution: a power resource allocation method for a dual-function intelligent reflector auxiliary system, which is applicable to a network system including a base station, a dual-function intelligent reflector, an edge user, a cooperative relay user and a malicious monitor. Except for the dual-function intelligent reflector, all devices are configured with a single antenna. The method includes the following steps:

[0052] The reconfigurable intelligent reflective surface has N reflective elements, and the user has two, including the first time slot and the second time slot; in the first time slot, the channel parameters from the base station to the reconfigurable intelligent metasurface, the malicious monitor, and from the reconfigurable intelligent metasurface to the cooperative relay user, the edge user, and the malicious monitor are respectively use represents the phase matrix of RIS in the first time slot, where θ n (1) is the phase of the nth reflective element, satisfying

[0053] The second time slot: cooperative relay users to reconfigurable smart metasurface, edge users and malicious monitors. The channel parameters from the reconfigurable smart metasurface to edge users and malicious monitors are use represents the phase matrix of RIS in the second time slot, where is the phase of the nth reflective element, satisfying

[0054] In the first time slot, the signal received by the cooperative relay user is The signal received by the edge user is Where P s ≤P max is the transmission power of the base station, which is less than the maximum transmission power P max , v u and vd are the additive Gaussian white noise at the cooperative relay user and the edge user, ω u and ω d are the power allocation coefficients of cooperative relay users and edge users, respectively, u and x d are the unit power information of cooperative relay users and edge users respectively. The cooperative user decodes x u The signal-to-interference-noise ratio is After serial interference elimination, the cooperative user decoding x is obtained. d The signal-to-interference-noise ratio is Edge User Decoding x u The signal-to-interference-noise ratio is After serial interference elimination, the edge user decoding x is obtained. d The signal-to-interference-noise ratio is in and Represents the noise power.

[0055] The probability of interruption of decoding information between cooperative relay users and edge users in the first time slot is:

[0056]

[0057] According to the Neyman-Pearson lemma, there are two situations when a malicious monitor receives a signal, namely It means that the malicious monitor did not detect the base station sending covert information; It represents the situation that the malicious monitor detects that the base station sends hidden information. Assuming that the malicious monitor uses a power detector to detect whether the base station sends hidden information, and considering the situation of infinite detection samples, the average receiving power of the malicious monitor in the two cases can be expressed as:

[0058]

[0059] The detection error probability of a malicious monitor is obtained as:

[0060]

[0061] Malicious surveillance detects that the base station transmits hidden information, that is, Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is The probability of successful decoding by a malicious observer is:

[0062]

[0063] The signal received by the edge user of the second time slot is Where Pu is the transmission power of the cooperative relay user in the second time slot, is the power allocation coefficient of edge user information and interference information, x j is the unit power interference information sent by the cooperative relay user. After perfect serial interference elimination, the edge user decodes x d The signal-to-interference-noise ratio is The signal-to-interference-to-noise ratio of edge user decoding c is At the edge of the second time slot, the user decodes x d The interruption probability of and c is:

[0064]

[0065] The worst case scenario in which a malicious monitor successfully decodes the hidden information is as follows: 1) In the first time slot, the malicious monitor successfully detects and decodes the hidden information; 2) In the first time slot, the malicious monitor successfully detects the hidden information but fails to decode it, but in the second time slot, the malicious monitor successfully detects and decodes the hidden information; 3) In the first time slot, the malicious monitor does not detect the hidden information; in the second time slot, the malicious monitor successfully detects and decodes the hidden information; The malicious monitor receives signals in two situations, namely It means that the malicious monitor does not detect the situation where the cooperative relay user sends covert information;

[0066] It represents the situation where the malicious monitor detects the cooperative relay user sending hidden information. The average receiving power of the malicious monitor in the two cases is expressed as:

[0067]

[0068] The detection error probability of a malicious monitor is obtained as:

[0069]

[0070] Malicious surveillance detects that the remote user is transmitting hidden information. Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is:

[0071]

[0072] The probability of successful decoding by a malicious observer is:

[0073]

[0074] Solve the optimization problem and get the optimized safety probability; by the power allocation coefficient ω of two different time slots d and The optimization of maximizing the system safety probability can be expressed mathematically as follows:

[0075]

[0076] The specific operations for solving the optimization problem and obtaining the optimized safety probability include:

[0077] 1) Order The objective function is to find The maximum value of To simplify the optimization, it is assumed that the phase of each time slot RIS is perfectly aligned with the legal user. The optimization problem is expressed as:

[0078]

[0079] 2) Convert the target problem into two sub-problems Q1 and Q2, then sub-problem Q1 is expressed as:

[0080]

[0081] in Sub-question Q2 is expressed as:

[0082]

[0083] in

[0084] 3) Fixed ω d ,right Optimize, for the number of iterations k = 0, 1, 2..., fix Solving subproblem Q1 yields Then fix it Solving subproblem Q2 yields Continue to iterate until you are satisfied Get the intermediate solution

[0085] 4) As the initial point, a penalty function B is defined to handle the constraints. The penalty function is expressed as:

[0086]

[0087] 5) Fixed r = r k , the optimization problem becomes solving an unconstrained optimization problem Update by gradient descent Keep updating the penalty coefficient r and iterate until it satisfies Get the final optimized solution.

[0088] By substituting the final optimized solution into the objective function, the maximum system safety probability can be obtained.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A power resource allocation method for a dual-function intelligent reflector auxiliary system, applicable to a network system including a base station, a dual-function intelligent reflector, an edge user, a cooperative relay user and a malicious monitor, except for the dual-function intelligent reflector, all devices are equipped with a single antenna, characterized in that: The method comprises the following steps: The reconfigurable intelligent reflective surface has N reflective elements, the user has two, and includes a first time slot and a second time slot; The worst case scenario in which the malicious monitor successfully decodes the hidden information is as follows: 1) In the first time slot, the malicious monitor successfully detects and decodes the hidden information; 2) In the first time slot, the malicious monitor successfully detects the hidden information but fails to decode it, but in the second time slot, the malicious monitor successfully detects and decodes the hidden information; 3) In the first time slot, the malicious monitor does not detect the hidden information; in the second time slot, the malicious monitor successfully detects and decodes the hidden information; Solve the optimization problem and obtain the optimized safety probability; By substituting the final optimized solution into the objective function, the maximum system safety probability can be obtained.

2. The power resource allocation method of a dual-function intelligent reflector auxiliary system according to claim 1, characterized in that: In the first time slot, the channel parameters from the base station to the reconfigurable smart metasurface, the malicious monitor, and from the reconfigurable smart metasurface to the cooperative relay user, the edge user, and the malicious monitor are use represents the phase matrix of RIS in the first time slot, where is the phase of the nth reflective element, satisfying The second time slot: cooperative relay users to reconfigurable smart metasurface, edge users and malicious monitors. The channel parameters from the reconfigurable smart metasurface to edge users and malicious monitors are use represents the phase matrix of RIS in the second time slot, where is the phase of the nth reflective element, satisfying 3. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 2 is characterized by: In the first time slot, the signal received by the cooperative relay user is The signal received by the edge user is Where P s ≤P max is the base station's transmit power, which is less than the maximum transmit power P max , v u and v d are the additive Gaussian white noise at the cooperative relay user and the edge user, ω u and ω d are the power allocation coefficients of cooperative relay users and edge users, respectively, u and x d are the unit power information of cooperative relay users and edge users respectively. The cooperative user decodes x u The signal-to-interference-noise ratio is After serial interference elimination, the cooperative user decoding x is obtained. d The signal-to-interference-noise ratio is Edge User Decoding x u The signal-to-interference-noise ratio is After serial interference elimination, the edge user decoding x is obtained. d The signal-to-interference-noise ratio is in and Represents the noise power.

4. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 3 is characterized by: The interruption probability of cooperative relay users and edge users decoding information in the first time slot is: According to the Neyman-Pearson lemma, there are two situations when a malicious monitor receives a signal, namely It means that the malicious monitor did not detect the base station sending covert information; It represents the situation that the malicious monitor detects that the base station sends hidden information. Assuming that the malicious monitor uses a power detector to detect whether the base station sends hidden information, and considering the situation of infinite detection samples, the average receiving power of the malicious monitor in the two cases can be expressed as: The detection error probability of a malicious monitor is obtained as: Malicious surveillance detects that the base station transmits hidden information, that is, Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is The probability of successful decoding by a malicious observer is:

5. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 4, characterized in that: The signal received by the edge user of the second time slot is Where P u is the transmission power of the cooperative relay user in the second time slot, is the power allocation coefficient of edge user information and interference information, x j is the unit power interference information sent by the cooperative relay user. After perfect serial interference elimination, the edge user decodes x d The signal-to-interference-noise ratio is The signal-to-interference-to-noise ratio of edge user decoding c is At the edge of the second time slot, the user decodes x d The interruption probability of and c is:

6. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 5, characterized in that: There are two situations when malicious monitors receive signals, namely It means that the malicious monitor does not detect the situation where the cooperative relay user sends covert information; It represents the situation where the malicious monitor detects the cooperative relay user sending hidden information. The average receiving power of the malicious monitor in the two cases is expressed as: The detection error probability of a malicious monitor is obtained as:

7. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 6, characterized in that: Malicious surveillance detects that the remote user is transmitting hidden information. Will try to hide the information x d Decode it and get the malicious monitor's decoded x d The signal-to-interference-noise ratio is: The probability of successful decoding by a malicious observer is:

8. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 7, characterized in that: By dividing the power of two different time slots by the coefficient ω d and The optimization of maximizing the system safety probability can be expressed mathematically as follows:

9. The power resource allocation method of the dual-function intelligent reflector auxiliary system according to claim 8, characterized in that: The specific operations for solving the optimization problem and obtaining the optimized safety probability include: 1) Order The objective function is to find The maximum value of To simplify the optimization, it is assumed that the phase of each time slot RIS is perfectly aligned with the legal user. The optimization problem is expressed as: 2) Convert the target problem into two sub-problems Q1 and Q2, then sub-problem Q1 is expressed as: in Sub-question Q2 is expressed as: in 3) Fixed ω d ,right Optimize, for the number of iterations k = 0, 1, 2..., fix Solving subproblem Q1 yields Then fix it Solving subproblem Q2 yields Continue to iterate until you are satisfied (∈1 is a small positive number), we get the intermediate solution 4) As the initial point, a penalty function B is defined to handle the constraints. The penalty function is expressed as: 5) Fixed r = r k , the optimization problem becomes solving an unconstrained optimization problem Update by gradient descent Keep updating the penalty coefficient r and iterate until it satisfies (∈2 is a small positive number), and the final optimized solution is obtained.

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