Method and device for resisting perception and communication eavesdropping in STAR-RIS assisted ISAC system

Abstract

The invention discloses a method and a device for resisting perception and communication eavesdropping in an STAR-RIS auxiliary ISAC system. The method comprises the following steps: establishing an STAR-RIS auxiliary ISAC system model; constructing a target optimization problem by taking maximization of the secrecy rate of a communication end as an optimization purpose and taking a communication beam, a sensing beam and a transmission / reflection coefficient of the STAR-RIS as optimization variables; and solving a target optimization problem by adopting an alternating optimization algorithm based on successive convex approximation and penalty dual decomposition. According to the method, the reflection end and the transmission end of the STAR-RIS are divided into a sensing area and a communication area, and the communication security and the sensing security of the STAR-RIS assisted ISAC system are considered at the same time; by using an alternating optimization algorithm based on successive convex approximation and penalty dual decomposition, on the premise of ensuring the sensing end performance and sensing security, the security rate of a communication end is maximized by optimizing transmission / reflection coefficients of a communication beam, a sensing beam and the STAR-RIS in the STAR-RIS assisted ISAC system, so that the security of the STAR-RIS assisted ISAC system is ensured.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a method and device for counteracting perception and communication eavesdropping in a STAR-RIS-assisted ISAC system. Background Art

[0002] Due to the rapid development of connected devices and mobile services, spectrum resources are becoming increasingly scarce. Traditionally, most commercial communication systems operate mainly in frequency bands below 6 GHz, coexisting peacefully with radar sensing systems used for applications such as air traffic control and weather observation. However, with the increasing demand for wireless connectivity, wireless communications have begun to expand to higher frequencies, such as millimeter waves, terahertz and even visible light bands, which has led to increasingly serious frequency band overlap problems with existing radar sensing systems. If the traditional independent design approach is continued to be used to develop communication and radar sensing systems, significant mutual interference will be caused. Therefore, it is urgent to adopt a joint design concept to reduce interference and improve spectrum utilization efficiency by achieving spectrum sharing and technical compatibility. At the same time, with the advancement of digital communication technology and the development of fields such as massive MIMO (multiple input multiple output), millimeter wave communication, and terahertz technology, the boundary between communication and radar has gradually blurred, allowing the two to be better integrated and resource sharing to be achieved not only at the software level but also at the hardware level. Looking to the future, the sixth generation (6G) mobile communication network is expected to provide not only ultra-high-speed data services, but also high-precision wireless sensing functions, which is of great significance for promoting the construction of smart cities and the application of remote information technology. It is against this background that the integrated communication and sensing (ISAC) has become an important direction in the current 6G technology research and development.

[0003] ISAC is a new type of information processing technology. It realizes the synergy of perception and communication capabilities by sharing hardware resources and information flow, thereby significantly improving the system's spectrum efficiency, hardware utilization efficiency and overall information processing efficiency. The core of this technology lies in the flexible reuse of time and frequency resources, the multifunctional integration of hardware platforms, and the joint optimization design at the airport and protocol levels, aiming to build a unified framework that can simultaneously and efficiently perform data transmission and environmental perception tasks. The essence of ISAC lies in its dual-function support characteristics, that is, seamless integration of communication and perception capabilities in the same system architecture, the two complement each other and promote each other. Although ISAC has shown great potential, it has also encountered a series of challenges in the process of transformation to practical applications. Specifically, the performance of the ISAC system is highly dependent on the specific propagation environment, especially in high-frequency signal transmission, the path loss is large, and the signal strength of the non-line-of-sight (NLOS) path is weak. In addition, the line-of-sight path is easily blocked by surrounding objects. These factors together lead to limited coverage and many blind spots.

[0004] As an emerging technology, intelligent metasurface (RIS) provides innovative solutions to the challenges faced by integrated communication and perception (ISAC) technology by integrating multiple low-cost passive components into an artificial surface. The core of intelligent metasurface (RIS) lies in its intelligent controller that can dynamically adjust the phase response of each component and accurately control the propagation path of wireless signals, thereby breaking through the limitations of traditional wireless propagation environments and realizing customized propagation environments to adapt to specific system requirements. However, traditional intelligent metasurfaces (RIS) only have the function of signal reflection, which limits the service range to the 180-degree half plane between the base station and the intelligent metasurface (RIS), resulting in a coverage blind spot. In order to overcome this limitation, the transmissive-reflective dual-function reconfigurable intelligent surface (STAR-RIS) came into being, which can not only reflect signals, but also transmit signals to achieve 360-degree all-round coverage. The uniqueness of the transmissive-reflective dual-function reconfigurable intelligent surface (STAR-RIS) is that it can simultaneously process the transmission and reflection of the incident signal, providing services for users on both sides of it, greatly enhancing the flexibility and coverage capability of the system. The integration of STAR-RIS technology and ISAC concept can not only significantly expand the coverage of the system and improve communication and perception performance, but also effectively reduce deployment costs and operating power consumption, open up new development paths for wireless communication and sensing fields, and bring more innovation opportunities.

[0005] At the same time, STAR-RIS's full spatial coverage and the broadcast nature of the channels can easily lead to signal eavesdropping. How to ensure the security of the system while improving the communication and perception capabilities of the ISAC system with STAR-RIS is a very important issue.

[0006] In the current research, some security designs for the STAR-RIS-assisted ISAC system have emerged. For example, there is an active eavesdropper at the communication end or the sensing end in the STAR-RIS-assisted ISAC system; at the same time, some researchers consider that the sensing user at the STAR-RIS sensing end may be a potential eavesdropper and thus eavesdrop on the information of the communication user. However, in practical applications, due to perception errors and limited detection resolution, the position of the target cannot always be perfectly obtained. For example, given N antennas arranged in a uniform linear structure with a half-wavelength spacing, the angular resolution is approximately calculated as 2 / N (inrad), which means that the target within this angular interval cannot be detected individually. When the position of the target can only be roughly sensed within an angular region, a wider beam needs to be formulated to the region to avoid missing the target. However, focusing the beam to a spatial region will inevitably increase the risk of information leakage, thus requiring a robust security waveform design.

[0007] However, there are technologies that have begun to study the perceived security in traditional ISAC, but no researcher has considered the perceived security under the SATR-RIS assisted ISAC system. Summary of the invention

[0008] In order to overcome the deficiencies in the prior art, the present invention provides a method for counteracting perception and communication eavesdropping in a STAR-RIS assisted ISAC system, a corresponding device, an electronic device and a computer-readable storage medium.

[0009] The technical solution of the present invention to solve the above technical problems is:

[0010] A method for countering perception and communication eavesdropping in a STAR-RIS-assisted ISAC system comprises the following steps:

[0011] Step S1: Establishing the STAR-RIS-assisted ISAC system model;

[0012] Step S2: Taking maximizing the confidentiality rate of the communication end as the optimization purpose, the communication beam, the sensing beam and the transmission / reflection coefficient of STAR-RIS as the optimization variables, constructing a target optimization problem;

[0013] Step S3: using an alternating optimization algorithm of successive convex approximation and penalized dual decomposition to solve the target optimization problem.

[0014] As a preferred solution of the present invention, in step S1, the STAR-RIS assisted ISAC system model consists of an ISAC base station, a STAR-RIS with N elements, a single-antenna communication user, a single-antenna communication eavesdropper, a single-antenna sensing target and a single-antenna sensing eavesdropper; wherein the antenna array of the ISAC base station adopts a uniform linear array arrangement; the array of the elements of the STAR-RIS adopts a uniform planar array arrangement; the ISAC base station simultaneously sends communication signals and sensing signals, and the communication signals can be used to assist sensing.

[0015] As a preferred solution of the present invention, in step S2, by optimizing the communication beam w c , sensing beam w s and the transmission / reflection coefficient θ of STAR-RIS t ,θ r , maximize the confidentiality rate of the communication end; where,

[0016] The target optimization problem is:

[0017]

[0018] Where: (1a) represents the transmit power constraint of the ISAC base station; (1b) and (1c) represent the amplitude constraint and phase shift constraint of the coupled STAR-RIS, respectively; (1d) and (1e) represent the gain constraints at the sensing target and the sensing eavesdropper, respectively; P t Represents the maximum transmission power of the ISAC base station; R c represents the confidentiality rate at the communication user; β n,t ,β n,r and φ n,t ,φ n,r are the amplitude and phase shift of the reflection coefficient and transmission coefficient of the coupled phase-shifted STAR-RIS, respectively; P s represents the beam gain at the sensing target; P s,e represents the beam gain at the sensing eavesdropper, τ s ,τ s,e Respectively represent the set thresholds;

[0019] Among them, the confidentiality rate R at the communication user c The calculation formula is:

[0020]

[0021] Among them, the beam gain P at the sensing target s and the beam gain P at the eavesdropper s,e They are:

[0022]

[0023] Where: G represents the channel gain from ISAC base station to STAR-RIS; h s ,h s,e They represent the channel gains from SATR-RIS to the sensing target and the sensing eavesdropper respectively; Represents the Gaussian white noise variance at the communication user and the communication eavesdropper.

[0024] As a preferred solution of the present invention, in step S3, a penalty dual decomposition algorithm is adopted to introduce auxiliary variables Dual variable λ t ,λ r and penalty parameter ρ, we get the augmented Lagrangian problem of the original problem:

[0025]

[0026] Then the augmented Lagrangian problem is decomposed into three sub-problems: c ,w s}Sub-problem 1: Regarding the variable {θ t ,θ r Sub-problem 2 of} and about variables , and solve subproblems 1, 2, and 3 respectively.

[0027] As a preferred embodiment of the present invention, regarding the variable {w c ,w s The first sub-problem of} is a non-convex problem, and its solution process is:

[0028] The augmented Lagrangian problem can be rewritten as:

[0029]

[0030] Based on the successive convex approximation SCA method, we introduce auxiliary variables {p, q, t} to obtain:

[0031]

[0032] Based on the successive convex approximation SCA method, Taylor expansion is performed on the non-convex part variables of equations (8b), (8c), (8d), and (8e):

[0033]

[0034] Where: μ = h H ΘG represents the total channel gain from STAR-RIS to the communication user, and the set {w c (m), w s(m), t(m)} are the values ​​of the variables in the mth iteration. Since the problem is convex with respect to the variables, CVX is used to solve it, and the optimal solution is obtained through multiple rounds of iterations.

[0035] As a preferred embodiment of the present invention, t ,θ r The second sub-problem of} is a non-convex problem, and its solution process is:

[0036] The augmented Lagrangian problem can be rewritten as:

[0037]

[0038] Based on the successive convex approximation SCA method, we introduce auxiliary variables {a, b, l} to obtain:

[0039]

[0040] Based on the successive convex approximation (SCA) method, Taylor expansion is performed on the non-convex part variables of equations (11a), (11b), (11c), and (11d):

[0041]

[0042] Where: v = diag (h H )G represents the partial channel gain from STAR-RIS to the user, and the set {θ t (m),θ r (m),l(m)} is the value of the variable in the mth iteration. Since the problem is convex with respect to the variable, CVX is used to solve it, and the optimal solution is obtained through multiple rounds of iterations.

[0043] As a preferred embodiment of the present invention, The solution process of sub-problem 3 is:

[0044] The augmented Lagrangian problem can be rewritten as:

[0045]

[0046] Where: η i =-θ i +ρλ i ;

[0047] By expanding formula (13), the original problem can be equivalently transformed into:

[0048]

[0049] Sub-problem 3 is further divided into two parts: Sub-problem 4 and about phase shift Sub-problem 5: Assume

[0050] Among them, about the amplitude The fourth sub-problem is:

[0051]

[0052] set up For the nth element, equation (15) can be transformed into:

[0053]

[0054] Get the optimal amplitude solution:

[0055]

[0056] Among them, the phase shift The fifth sub-problem is:

[0057]

[0058] Through formula (6c), we get:

[0059]

[0060] Then formula (18) is:

[0061]

[0062] This results in the minimum phase shift solution:

[0063]

[0064] Right now:

[0065]

[0066] A device for countering perception and communication eavesdropping in a STAR-RIS-assisted ISAC system, comprising:

[0067] Model building module: used to build the STAR-RIS assisted ISAC system model;

[0068] Objective function construction module: used to construct an objective optimization problem with the optimization purpose of maximizing the confidentiality rate of the communication end and the transmission / reflection coefficients of the communication beam, the sensing beam and STAR-RIS as optimization variables;

[0069] Alternating optimization module; used to maximize the system's confidentiality rate while ensuring perceived security by continuously iterating and optimizing variables, dual variables, and penalty parameters.

[0070] An electronic device includes a central processing unit and a memory, wherein the central processing unit is used to call and run a computer program stored in the memory to execute the steps of the method for counteracting perception and communication eavesdropping in the STAR-RIS assisted ISAC system.

[0071] A computer-readable storage medium stores a computer program implemented by the method for countering perception and communication eavesdropping in the STAR-RIS-assisted ISAC system in the form of computer-readable instructions. When the computer program is called and executed by a computer, the steps included in the corresponding method are executed.

[0072] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0073] 1. The method for countering perception and communication eavesdropping in the STAR-RIS-assisted ISAC system of the present invention divides the reflection and transmission ends of STAR-RIS into a perception area and a communication area, while taking into account the communication security and perception security of the STAR-RIS-assisted ISAC system; by utilizing an alternating optimization algorithm based on successive convex approximation and penalized dual decomposition, under the premise of ensuring the performance and security of the perception end, the communication beam, the perception beam and the transmission / reflection coefficient of STAR-RIS in the STAR-RIS-assisted ISAC system are optimized to maximize the security rate of the communication end, thereby ensuring the security of the STAR-RIS-assisted ISAC system.

[0074] 2. The method for counteracting perception and communication eavesdropping in the STAR-RIS-assisted ISAC system of the present invention adds perception constraints to the STAR-RIS-assisted ISAC system model, and uses an alternating optimization algorithm based on successive convex approximation and penalized dual decomposition to solve the constructed target optimization problem, thereby obtaining the optimal communication beam, perception beam and STAR-RIS transmission / reflection coefficient. By adopting the optimal communication beam, perception beam and STAR-RIS transmission / reflection coefficient, even if there is a perceptual eavesdropper in the STAR-RIS-assisted ISAC system model, the amount of information eavesdropped can be minimized or even approximated to zero, thereby obtaining communication security performance close to that in the absence of a perceptual eavesdropper. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 Schematic diagram of the method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system of the present invention.

[0076] Figure 2 It is a schematic diagram of the STAR-RIS assisted ISAC system model in the present invention.

[0077] Figure 3This is a curve diagram showing how the confidentiality rate changes with power during the simulation process.

[0078] Figure 4 This is a curve diagram showing how the confidentiality rate changes with the threshold during the simulation process.

[0079] Figure 5 It is a structural block diagram of the device for counteracting perception and communication eavesdropping in the STAR-RIS assisted ISAC system of the present invention.

[0080] Figure 6 It is a schematic diagram of the structure of the computer device of the present invention. DETAILED DESCRIPTION

[0081] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0082] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0083] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0084] It will be understood by those skilled in the art that the "client", "terminal" and "terminal device" used herein include both devices with wireless signal receivers, which are devices with only wireless signal receivers without transmission capabilities, and devices with receiving and transmitting hardware, which are devices with receiving and transmitting hardware capable of two-way communication on a two-way communication link. Such devices may include: cellular or other communication devices such as personal computers, tablet computers, which have single-line displays or multi-line displays or cellular or other communication devices without multi-line displays; PCS (Personal Communications Service, personal communication system), which can combine voice, data processing, fax and / or data communication capabilities; PDA (Personal Digital Assistant, personal digital assistant), which may include a radio frequency receiver, pager, Internet / intranet access, web browser, notepad, calendar and / or GPS (Global Positioning System, global positioning system) receiver; conventional laptop and / or palmtop computers or other devices, which have and / or include a conventional laptop and / or palmtop computer or other device with and / or including a radio frequency receiver. The "client", "terminal" and "terminal device" used herein may be portable, transportable, installed in a vehicle (air, sea and / or land), or suitable for and / or configured to run locally, and / or in a distributed form, at any other location on the earth and / or in space. The "client", "terminal" and "terminal device" used herein may also be a communication terminal, an Internet terminal, a music / video playing terminal, for example, a PDA, a MID (Mobile Internet Device) and / or a mobile phone with a music / video playing function, or a smart TV, a set-top box and other devices.

[0085] The hardware referred to by the names such as "server", "client" and "service node" in the present invention is essentially an electronic device with equivalent capabilities to a personal computer. It is a hardware device with necessary components revealed by the von Neumann principle, such as a central processing unit (including an arithmetic unit and a controller), a memory, an input device and an output device. The computer program is stored in its memory, and the central processing unit calls the program stored in the external memory into the internal memory for execution, executes the instructions in the program, and interacts with the input and output devices to complete specific functions.

[0086] It should be pointed out that the concept of "server" referred to in the present invention can also be extended to the case of server clusters. According to the network deployment principle understood by those skilled in the art, the servers should be logically divided. In physical space, these servers can be independent of each other but can be called through interfaces, or integrated into a physical computer or a set of computer clusters. Those skilled in the art should understand this flexibility, and should not use it to restrict the implementation of the network deployment method of the present invention.

[0087] Unless expressly specified, one or more technical features of the present invention can be deployed on a server for implementation and accessed by a client through a remote call to obtain an online service interface provided by the server, or can be directly deployed and run on a client for access.

[0088] The neural network models referenced or may be referenced in the present invention, unless expressly specified, can be deployed on a remote server and remotely called on the client, or can be deployed on a client with sufficient device capabilities and directly called. In some embodiments, when it runs on the client, its corresponding intelligence can be obtained through transfer learning so as to reduce the requirements for the client hardware operating resources and avoid excessive occupation of the client hardware operating resources.

[0089] Unless expressly specified otherwise, the various data involved in the present invention can be stored remotely in a server or in a local terminal device, as long as it is suitable for being called by the technical solution of the present invention.

[0090] Those skilled in the art should know that, although the various methods of the present invention are described based on the same concept and thus present commonality to each other, unless otherwise specified, these methods can be independently executed. Similarly, for each embodiment disclosed in the present invention, they are all proposed based on the same inventive concept, therefore, concepts with the same expression, and concepts that are appropriately changed for convenience despite different expressions, should be understood as equivalent.

[0091] Unless the mutually exclusive relationship between the embodiments to be disclosed in the present invention is explicitly stated, the relevant technical features involved in the embodiments can be cross-combined to flexibly construct new embodiments, as long as such combination does not deviate from the creative spirit of the present invention and can meet the needs of the prior art or solve certain deficiencies in the prior art. Those skilled in the art should be aware of this flexibility.

[0092] See also Figure 1-Figure 2 The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system of the present invention comprises the following steps:

[0093] Step S1: Establishing the STAR-RIS-assisted ISAC system model;

[0094] In this embodiment, the STAR-RIS assisted ISAC system model consists of an ISAC base station, a STAR-RIS with N elements, a single-antenna communication user, a single-antenna communication eavesdropper, a single-antenna sensing target and a single-antenna sensing eavesdropper; wherein the antenna array of the ISAC base station adopts a uniform linear array arrangement; the array of elements in the STAR-RIS adopts a uniform planar array arrangement; the ISAC base station simultaneously sends communication signals and sensing signals, and the communication signals can be used to assist sensing.

[0095] Step S2: Taking maximizing the confidentiality rate of the communication end as the optimization purpose, the communication beam, the sensing beam and the transmission / reflection coefficient as the optimization variables, and constructing a target optimization problem;

[0096] By optimizing the communication beam w c , sensing beam w s and the transmission / reflection coefficient θ of STAR-RIS t ,θ r , while ensuring that the perceived target is at the lower threshold and the perceived eavesdropper is at the upper threshold, maximize the confidentiality rate of the communication end; therefore, the constructed target optimization problem is:

[0097]

[0098] Where: (1a) represents the transmit power constraint of the ISAC base station; (1b) and (1c) represent the amplitude constraint and phase shift constraint of the coupled STAR-RIS, respectively; (1d) and (1e) represent the gain constraints at the sensing target and the sensing eavesdropper, respectively; P t Represents the maximum transmission power of the ISAC base station; R c represents the confidentiality rate at the communication user; β n,t ,β n,r and φ n,t ,φ n,r are the amplitude and phase shift of the coupled phase-shifted STAR-RIS reflection coefficient and transmission coefficient respectively; P s represents the beam gain at the sensing target; P s,e represents the beam gain at the sensing eavesdropper, τ s ,τ s,e Respectively represent the set thresholds;

[0099] Among them, the confidentiality rate R at the communication user c The calculation formula is:

[0100]

[0101] Among them, the beam gain P at the sensing targets and the beam gain P at the eavesdropper s,e They are:

[0102]

[0103] Where: G represents the channel gain from ISAC base station to STAR-RIS; h s ,h s,e They represent the channel gains from SATR-RIS to the sensing target and the sensing eavesdropper respectively; Represents the Gaussian white noise variance at the communication user and the communication eavesdropper.

[0104] Step S3: Adopt the alternating optimization algorithm of successive convex approximation (SCA) and penalized dual decomposition (PDD) to solve the target optimization problem, that is, perform multiple rounds of iterations on the variables of problem 1 and sub-problem 2 internally through successive convex approximation (SCA) to obtain a higher quality solution, and continuously optimize the three sub-problems alternately, and continuously update the dual variables and penalty parameters externally, so as to obtain the solution of the original problem, that is, maximize the confidentiality rate of the system under the premise of ensuring perceived security;

[0105] First, the penalized dual decomposition (PDD) algorithm is used to introduce auxiliary variables Dual variable λ t ,λ r and penalty parameter ρ, we get the augmented Lagrangian problem of the original problem:

[0106]

[0107] Next, the augmented Lagrangian problem is decomposed into three sub-problems: c ,w s}Sub-problem 1: Regarding the variable {θ t ,θ r Sub-problem 2 of} and about variables , and solve subproblems 1, 2, and 3 respectively.

[0108] Among them, regarding the variable {w c ,w s The first sub-problem of} is a non-convex problem, and its solution process is:

[0109] (1) Rewrite the augmented Lagrangian problem as follows:

[0110]

[0111] (2) Based on the successive convex approximation SCA method, introducing auxiliary variables {p, q, t}, we can obtain:

[0112]

[0113] (3) Based on the successive convex approximation SCA method, Taylor expansion is performed on the non-convex part variables of equations (8b), (8c), (8d), and (8e):

[0114]

[0115] Where: μ = h H ΘG represents the total channel gain from STAR-RIS to the communication user, and the set {w c (m), w s (m), t(m)} are the values ​​of the variables in the mth iteration. This problem is convex with respect to the variables and can be solved using CVX. By performing multiple rounds of iterations on the variables, a higher quality solution can be obtained.

[0116] Among them, about {θ t ,θ r The second sub-problem of} is a non-convex problem, and its solution process is:

[0117] (1) Rewrite the augmented Lagrangian problem as follows:

[0118]

[0119] (2) Based on the successive convex approximation SCA method, introducing auxiliary variables {a, b, l}, we can obtain:

[0120]

[0121] (3) Based on the successive convex approximation (SCA) method, Taylor expansion is performed on the non-convex part variables of equations (11a), (11b), (11c), and (11d):

[0122]

[0123] Where: v = diag (h H )G represents the partial channel gain from STAR-RIS to the communication user, and the set {θ t (m),θ r (m),l(m)} is the value of the variable in the mth iteration. Since the problem is convex for the variables {a,b,l}, CVX is used to solve it, and a higher quality solution is obtained by iterating the variables for multiple rounds.

[0124] Among them, about The solution process of sub-problem 3 is:

[0125] The augmented Lagrangian problem can be rewritten as:

[0126]

[0127] Where: η i =-θ i +ρλ i ;

[0128] By expanding formula (13), the original problem can be equivalently transformed into:

[0129]

[0130] Sub-problem 3 is further divided into two parts: Sub-problem 4 and about phase shift Sub-problem 5: Assume

[0131] Among them, about the amplitude The fourth sub-problem is:

[0132]

[0133] set up For the nth element, equation (15) can be transformed into:

[0134]

[0135] Get the optimal amplitude solution:

[0136]

[0137] Among them, the phase shift The fifth sub-problem is:

[0138]

[0139] Through formula (6c), we get:

[0140]

[0141] Then formula (18) is:

[0142]

[0143] Therefore, the minimum phase shift solution is:

[0144]

[0145] Right now:

[0146]

[0147] Finally, the process of the entire alternating optimization algorithm is as follows:

[0148] 1) Initialize the auxiliary variables, dual variables, penalty parameters, reduction factor c, and threshold γ introduced;

[0149] 2) By solving subproblem 1 and iterating the variables for multiple rounds, the optimal {w c ,w s}, solve subproblem 2 and iterate the variables for multiple rounds to obtain the optimal {θ t ,θ r}, by solving subproblems 4 and 5, we get the optimal Until the objective function converges;

[0150] 3) Calculation If δ≤γ, update the dual variable Otherwise, update the penalty parameter ρ = cρ;

[0151] 4) v = 0.9δ;

[0152] 5) Until δ converges.

[0153] See also Figure 3 and Figure 4 ,The performance of the scheme of the present invention is verified through simulation by comparing the three cases of different number of STAR-RIS components, no aware eavesdropper and random phase shift;

[0154] In the simulation, the following parameters are used: M = 8, N = 40, Pt = 1W, σ k =σ ke =σ s =σ se =-110dB, τ s =-91dB,τ s,e =-130dB, for easy observation, normalization is required. Γ s,e =-20dB, the large-scale fading of the channel is modeled as: d 0 is the unit distance, set to 1, α is the path loss factor, all set to 2.2; the channel model from STAR-RIS to four users is:

[0155]

[0156] Figure 3 The dynamic relationship between confidentiality rate and maximum power is vividly demonstrated.

[0157] It is revealed that as the power P tWith the increase of , the confidentiality rate values ​​show a steady upward trend. Among them, in this scheme, the scheme with N=50 STAR-RIS components shows a significant performance advantage compared with the scheme with N=40. It can be concluded that increasing the number of STAR-RIS components can effectively improve the system's degree of freedom and thus optimize the overall performance.

[0158] In the low-power transmission range, the traditional eavesdropper-unaware scheme performs better in terms of communication confidentiality, mainly because it has a lower demand for beamforming in this low-power transmission range, so it can focus more on communication confidentiality. However, as the power level increases, this performance advantage gradually weakens, and the gap between the two schemes gradually narrows. This trend reflects that while ensuring sensing performance, it is inevitable to allocate more resources to the communication area to meet the growing gain requirements.

[0159] In addition, the random phase STAR-RIS scheme exhibits the weakest communication confidentiality rate in the entire comparison, and this result shows that the transmission / reflection beamforming strategy of the present invention plays a key role in enhancing the confidentiality performance of the studied network.

[0160] Figure 4 The changes in confidentiality rates under different predetermined thresholds are shown.

[0161] As the threshold increases, the communication confidentiality of all schemes decreases because more gain needs to be allocated to the sensing target area; the gap between this scheme and the scheme with no perceived eavesdropper widens as the threshold increases, showing the importance of the beamforming capability of the STAR-RIS sensing area. The scheme with N = 50 performs better than the scheme with N = 40, and the random phase shift scheme performs the worst, highlighting the key role of a carefully designed beamforming strategy.

[0162] Based on any embodiment of the present invention, please refer to Figure 5 Another embodiment of the present invention further provides a device for a method of counteracting perception and communication eavesdropping in a STAR-RIS-assisted ISAC system, comprising a model building module, an objective function building module and an alternating optimization module, wherein the model building module is used to build a STAR-RIS-assisted ISAC system model; the objective function building module is used to build a target optimization problem with the optimization purpose of maximizing the confidentiality rate of the communication end and the transmission / reflection coefficient of the communication beam, the perception beam and the STAR-RIS as optimization variables; the alternating optimization module is used to maximize the confidentiality rate of the system under the premise of ensuring perception security by continuously iterating optimization variables, dual variables and penalty parameters.

[0163] The present invention considers the communication security and perception security of the STAR-RIS-assisted ISAC system; by utilizing an alternating optimization algorithm based on successive convex approximation and penalized dual decomposition, under the premise of ensuring the performance and security of the perception end, the communication beam, the perception beam and the transmission / reflection coefficient of STAR-RIS in the STAR-RIS-assisted ISAC system are optimized to maximize the security rate of the communication end, thereby ensuring the security of the STAR-RIS-assisted ISAC system.

[0164] Based on any embodiment of the present invention, please refer to Figure 6 Another embodiment of the present invention further provides an electronic device, which can be implemented by a computer device, such as Figure 6 As shown, a schematic diagram of the internal structure of a computer device. The computer device includes a processor, a computer-readable storage medium, a memory, and a network interface connected via a system bus. Among them, the computer-readable storage medium of the computer device stores an operating system, a database, and computer-readable instructions. The database may store a control information sequence. When the computer-readable instructions are executed by the processor, the processor can implement a method for counteracting perception and communication eavesdropping in a STAR-RIS-assisted ISAC system. The processor of the computer device is used to provide computing and control capabilities to support the operation of the entire computer device. The memory of the computer device may store computer-readable instructions. When the computer-readable instructions are executed by the processor, the processor can execute the method for counteracting perception and communication eavesdropping in a STAR-RIS-assisted ISAC system of the present invention. The network interface of the computer device is used to connect and communicate with a terminal. Those skilled in the art will understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present invention, and does not constitute a limitation on the computer device to which the scheme of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0165] In this embodiment, the processor is used to execute Figure 5 The memory stores the program code and various data required to execute the above modules. The network interface is used to transmit data between user terminals or servers. The memory in this embodiment stores the program code and data required to execute all modules / submodules in the device for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system of the present invention, and the server can call the program code and data of the server to execute the functions of all submodules.

[0166] The present invention also provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system described in any embodiment of the present invention.

[0167] The present invention also provides a computer program product, including a computer program / instruction, which, when executed by one or more processors, implements the steps of the method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system described in any embodiment of the present invention.

[0168] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments of the present invention can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the aforementioned storage medium can be a computer-readable storage medium such as a disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0169] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for countering perception and communication eavesdropping in a STAR-RIS-assisted ISAC system, characterized in that: The following steps are involved: Step S1: Establishing the STAR-RIS-assisted ISAC system model; Step S2: Taking maximizing the confidentiality rate of the communication end as the optimization purpose, the communication beam, the sensing beam and the transmission / reflection coefficient of STAR-RIS as the optimization variables, constructing a target optimization problem; Step S3: using an alternating optimization algorithm of successive convex approximation and penalized dual decomposition to solve the target optimization problem.

2. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 1, characterized in that: In step S1, the STAR-RIS assisted ISAC system model consists of an ISAC base station, a STAR-RIS with N elements, a single-antenna communication user, a single-antenna communication eavesdropper, a single-antenna sensing target and a single-antenna sensing eavesdropper; wherein the antenna array of the ISAC base station adopts a uniform linear array arrangement; the array of the elements of the STAR-RIS adopts a uniform planar array arrangement; the ISAC base station simultaneously sends communication signals and sensing signals, and the communication signals can be used to assist sensing.

3. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 2, characterized in that: In step S2, by optimizing the communication beam w c , sensing beam w s , and the transmission / reflection coefficient θ of STAR-RIS t ,θ r , maximize the confidentiality rate of the communication end; where, The target optimization problem is: s.t.||w c || 2 +||w s || 2 ≤P t ,(1a) R s ≥τ s ,(1d) R s,e ≤τ s,e ,(1e) Where: (1a) represents the transmit power constraint of the ISAC base station; (1b) and (1c) represent the amplitude constraint and phase shift constraint of the coupled STAR-RIS, respectively; (1d) and (1e) represent the gain constraints at the sensing target and the sensing eavesdropper, respectively; P t Represents the maximum transmission power of the ISAC base station; R c represents the confidentiality rate at the communication user; β n,t ,β n,r and φ n,t ,φ n,r are the amplitude and phase shift of the reflection coefficient and transmission coefficient of the coupled phase-shifted STAR-RIS, respectively; P s represents the beam gain at the sensing target; P s,e represents the beam gain at the sensing eavesdropper, τ s ,τ s,e They represent the set thresholds respectively; Among them, the confidentiality rate R at the communication user c The calculation formula is: Among them, the beam gain P at the sensing target s and the beam gain P at the eavesdropper s,e They are: Where: G represents the channel gain from ISAC base station to STAR-RIS; h s ,h s,e They represent the channel gains from SATR-RIS to the sensing target and the sensing eavesdropper respectively; Represents the Gaussian white noise variance at the communication user and the communication eavesdropper.

4. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 3, characterized in that: In step S3, the penalty dual decomposition algorithm is adopted, by introducing auxiliary variables Dual variable λ t ,λ r and penalty parameter ρ, we get the augmented Lagrangian problem of the original problem: Then the augmented Lagrangian problem is decomposed into three sub-problems: c ,w s }Sub-problem 1: Regarding the variable {θ t ,θ r Sub-problem 2 of} and about variables , and solve subproblems 1, 2, and 3 respectively.

5. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 4, characterized in that: About the variable {w c ,w s The first sub-problem of} is a non-convex problem, and its solution process is: The augmented Lagrangian problem can be rewritten as: Based on the successive convex approximation SCA method, we introduce auxiliary variables {p, q, t} to obtain: s.t.||w c || 2 +||w s || 2 ≤P t ,(8a) log2(1+t)≤q,(8c) Based on the successive convex approximation SCA method, Taylor expansion is performed on the non-convex part variables of equations (8b), (8c), (8d), and (8e): st||w c || 2 +||w s || 2 ≤P t ,(9a) Where: μ = h H ΘG represents the total channel gain from STAR-RIS to the communication user, and the set {w c (m), w s (m), t(m)} are the values ​​of the variables in the mth iteration. Since the problem is convex with respect to the variables, CVX is used to solve it, and the optimal solution is obtained through multiple rounds of iterations.

6. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 5, characterized in that: About {θ t ,θ r The second sub-problem of} is a non-convex problem, and its solution process is: The augmented Lagrangian problem can be rewritten as: stP s ≥τ s ,(10a) R s,e ≤τ s,e ,(10b) Based on the successive convex approximation SCA method, we introduce auxiliary variables {a, b, l} to obtain: log2(1+l)≤b,(11b) Based on the successive convex approximation (SCA) method, Taylor expansion is performed on the non-convex part variables of equations (11a), (11b), (11c), and (11d): Where: v = diag (h H )G represents the partial channel gain from STAR-RIS to the user, and the set {θ t (m),θ r (m),l(m)} is the value of the variable in the mth iteration. Since the problem is convex with respect to the variable, CVX is used to solve it, and the optimal solution is obtained through multiple rounds of iterations.

7. The method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to claim 6, characterized in that: about The solution process of sub-problem 3 is: The augmented Lagrangian problem can be rewritten as: st(6b),(6c),(13a) Where: η i = -θ i + ρυ i ; It should be noted that there may be an error in your original text. It is guessed that "ρλ" should be "ρυ". If this is not the case, please check and correct it in time. By expanding formula (13), the original problem can be equivalently transformed into: st(6b),(6c),(14a) Sub-problem 3 is further divided into two parts: Sub-problem 4 and about phase shift Sub-problem 5: Assume Among them, about the amplitude The fourth sub-problem is: st(6b),(15a) set up For the nth element, equation (15) can be transformed into: Get the optimal amplitude solution: Among them, the phase shift The fifth sub-problem is: st(6c),(18a) Through formula (6c), we get: Then formula (18) is: This results in the minimum phase shift solution: Right now:

8. A device for countering the method of sensing and communication eavesdropping in a STAR-RIS-assisted ISAC system according to any one of claims 1 to 7, characterized in that: include: Model building module: used to build the STAR-RIS assisted ISAC system model; Objective function construction module: used to construct an objective optimization problem with the optimization purpose of maximizing the confidentiality rate of the communication end and the transmission / reflection coefficients of the communication beam, the sensing beam and STAR-RIS as optimization variables; Alternate optimization module; It is used to maximize the system's confidentiality rate while ensuring perceived security by continuously iterating and optimizing variables, dual variables, and penalty parameters.

9. An electronic device, comprising a central processing unit and a memory, characterized in that: The central processor is used to call and run the computer program stored in the memory to execute the steps of the method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: It stores a computer program implemented by the method for countering perception and communication eavesdropping in the STAR-RIS assisted ISAC system according to any one of claims 1 to 7 in the form of computer-readable instructions, and when the computer program is called and executed by a computer, the steps included in the corresponding method are executed.

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