A RIS deployment method and system for non-cellular massive MIMO

Abstract

The present invention discloses a RIS deployment method and system for non-cellular massive MIMO, comprising: constructing a non-cellular massive MIMO point, wherein the point is evenly distributed in a plane, and an eavesdropper Eve exists in the system; utilizing RIS to enhance the physical layer security of the system, and calculating the downlink safe rate achievable by a target user under the assistance of RIS; taking the maximization of the safe rate of the target user as the objective function, obtaining the optimal phase shift and deployment position of RIS; the present invention can greatly improve the safe rate of the eavesdropped user without introducing additional system energy consumption; in a non-cellular massive MIMO system with an eavesdropper, for the first time, jointly optimizing the RIS phase shift and position deployment, so as to enhance the physical layer security of the system.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a RIS deployment method and system for non-cellular large-scale MIMO. Background Art

[0002] Cell-free massive MIMO technology can eliminate cell boundary restrictions by using densely deployed access points, alleviate or even eliminate the serious inter-cell interference in traditional massive MIMO systems, and also eliminate the difference between center and edge users due to balanced access point distribution, ensuring seamless service quality under high-speed mobility. However, ultra-dense access point deployment adds a large number of additional wired backhaul links and backhaul data transmission, which increases system energy consumption.

[0003] RIS integrates a large number of low-cost passive reflective elements with phase shift controllers. It can reflect the incident signal to the desired direction by adjusting the phase of the reflective element, thereby effectively improving the strength of the received signal. Compared with traditional relay equipment, RIS has no noise amplification and self-interference, and is also characterized by low energy consumption and easy deployment. Therefore, in the communication system, replacing some access points with RIS can greatly reduce the system energy consumption; adding RIS to the original system can achieve a considerable rate increase. Due to its unique advantages, RIS has been proposed as a solution to the energy consumption problem of non-cellular large-scale MIMO systems.

[0004] Due to the inherent broadcast characteristics of wireless signals, any user within the coverage area can theoretically receive wireless signals and launch various attacks (eavesdropping, surveillance, etc.). RIS phase adjustment can simultaneously increase the signal strength of legitimate users and weaken the signal strength of illegal users, thereby improving the security rate of legitimate users and showing good performance in improving system security.

[0005] However, existing RIS-assisted cell-free massive MIMO research has not yet addressed the impact of RIS location deployment in the secure communication problem. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the above existing problems, the present invention is proposed. Therefore, the present invention provides a RIS deployment method for non-cellular massive MIMO to solve the problem that the traditional method does not consider the impact of RIS location deployment on secure communication and the poor physical security of the system.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a RIS deployment method for non-cellular massive MIMO, comprising:

[0010] Construct a cell-free massive MIMO point, where the point is evenly distributed in a plane, and an eavesdropper Eve exists in the system;

[0011] Use RIS to enhance the physical layer security of the system and calculate the target user's achievable safe downlink rate with the assistance of RIS;

[0012] Taking the maximization of the target user's safety rate as the objective function, the optimal phase shift and deployment position of RIS are obtained.

[0013] As a preferred solution of the RIS deployment method of non-cellular massive MIMO according to the present invention, the step of constructing a non-cellular massive MIMO point includes:

[0014] Suppose there is a non-cellular massive MIMO system with M access points, K users evenly distributed in the plane, and an eavesdropper in the system;

[0015] Among them, all access points, users and eavesdroppers are single-antenna devices.

[0016] As a preferred solution of the RIS deployment method of non-cellular massive MIMO described in the present invention, wherein: using RIS to enhance the physical layer security of the system includes:

[0017] The wireless channel between the mth access point and the kth user consists of two parts: a direct link and a reflection link. The direct link is a Rayleigh channel and is expressed as:

[0018]

[0019] Among them, β mk represents the large-scale fading coefficient of the direct link from the mth access point to the kth user, h mk represents the small-scale fading coefficient of the direct link from the mth access point to the kth user;

[0020] The reflection link consists of two links from the access point to the RIS and from the RIS to the user. The link from the mth access point to the RIS is expressed as:

[0021]

[0022] In the formula, all subscripts m represent the mth access point, subscript r represents the RIS, subscript k represents the kth user, and subscript e represents the eavesdropper; β mr represents the large-scale fading coefficient of the link from the mth access point to the RIS, K mr represents the Ricean K factor of the mth access point to RIS link, and Respectively represent g mr The LoS component and NLoS component of RIS; the link from RIS to the kth user is expressed as:

[0023]

[0024] Among them, β rk represents the large-scale fading coefficient of the link from RIS to the kth user, K rk represents the Ricean K factor of the RIS to k-th user link, and Respectively represent g rk The LoS component and NLoS component of

[0025] The phase shift matrix of RIS is expressed as:

[0026]

[0027] in, represents the phase shift of the incident signal by the lth reflective element of RIS, L represents the number of reflective elements of RIS; set ρ mk represents the gain coefficient of the reflection link between the mth access point and the kth user. When the mth access point and the kth user are both within the RIS reflection range, ρ mk =1, otherwise ρ mk =0;

[0028] The direct link g mk Reflection link with gain factor Adding them together, the total wireless channel from the mth access point to the kth user is:

[0029]

[0030] The total wireless channel from the mth access point to the eavesdropper e is:

[0031]

[0032] The superscript H represents the conjugate transpose operator, g me represents the direct link between the mth access point and the eavesdropper e, represents the reflection link with gain coefficient between the mth access point and the eavesdropper e.

[0033] As a preferred solution of the RIS deployment method of non-cellular massive MIMO according to the present invention, the calculation of the downlink safe rate achievable by the target user under the assistance of RIS includes:

[0034] Calculate the safe rate R sec =log2(1+SNR k )-log2(1+SNR e );

[0035] Signal-to-noise ratio (SNR) of the eavesdropped user k It is expressed as:

[0036]

[0037] The eavesdropper's signal-to-noise ratio (SNR) e It is expressed as:

[0038]

[0039] The superscript * indicates the conjugate operator. and is the noise power of the eavesdropped user and the eavesdropper, p d is the transmission power of each access point; k' represents any one of the k-1 users except the kth user; M represents both the total number of access points and the mark of the last access point; represents the product of the LoS components of the reflection link from the mth AP to the kth user; represents the power gain of the reflection link from the mth AP to the kth user;

[0040] in

[0041] Indicates the amplitude of the reflection link from the mth AP to the kth user;

[0042] in

[0043]

[0044] It represents the calculation factor of the target user's useful signal power.

[0045] As a preferred solution of the RIS deployment method of non-cellular massive MIMO described in the present invention, wherein: maximizing the security rate of the target user is taken as the objective function, including:

[0046] With the goal of maximizing the traversal security rate of the eavesdropped user, under the constraints of RIS phase shift and position, the optimal RIS phase shift and optimal position deployment are found, and the following optimization problem is established:

[0047]

[0048]

[0049] (x r ,y r )∈S.

[0050] Among them, (x r ,y r ) are the location coordinates of RIS; S represents the regional scope of the system.

[0051] As a preferred solution of the RIS deployment method of non-cellular massive MIMO according to the present invention, obtaining the optimal phase shift and deployment position of the RIS includes:

[0052] The optimization problem is solved using a gradient descent alternating iterative algorithm to obtain the optimal RIS phase shift and optimal position deployment.

[0053] As a preferred solution of the RIS deployment method of non-cellular massive MIMO according to the present invention, the gradient descent alternating iteration algorithm includes:

[0054] Set the RIS initial position to The initial phase shift matrix is ​​Φ 0 , substituting the two into the calculation formula of the safety rate, we get Initialize the iteration step size s1, s2> 0, the iteration termination error σ> 0, and the iteration variables i, j = 0;

[0055] Calculate the decreasing direction of the safe rate to the RIS phase shift matrix Iterate the RIS phase shift Based on this, a new safe rate is obtained, which is recorded as

[0056] Set i=i+1 and repeat R sec (Φ i+1 ) calculation steps until |R sec (Φ i+1 )-R sec (Φ i )|<σ, the optimal value of phase shift is Φ opt =Φ i+1 ;

[0057] Calculate the safe rate of descent direction to the RIS deployment location Iterate on RIS deployment locations Based on this, a new safe rate is obtained, which is recorded as

[0058] Set j = j + 1, repeat The calculation steps are as follows: So far, the optimal value of the deployment position is

[0059] Repeat all the above calculation steps until Get the optimal phase shift Φ of RIS opt and optimal deployment location

[0060] In a second aspect, the present invention provides a RIS deployment system for non-cellular massive MIMO, comprising:

[0061] RIS controller module, responsible for coordinating and managing the entire RIS network;

[0062] The base station module is responsible for communicating with the user equipment and interacting with the RIS controller module to transmit data to the correct RIS and user equipment modules;

[0063] RIS module for beamforming and signal enhancement;

[0064] The user equipment module is used to communicate with the base station module, receive beamforming signals from the RIS, and send data back to the base station module.

[0065] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein: the processor implements any step of the above method when executing the computer program.

[0066] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: the computer program implements any step of the above method when executed by a processor.

[0067] Compared with the prior art, the invention has the following beneficial effects: the present invention constructs a cellular-free massive MIMO point, which is evenly distributed in a plane and has an eavesdropper Eve in the system; RIS is used to enhance the physical layer security of the system, and the achievable downlink safe rate of the target user with the assistance of RIS is calculated; the optimal phase shift and deployment position of RIS are obtained by taking the maximization of the safe rate of the target user as the objective function; the present invention can greatly improve the safe rate of the eavesdropped user without introducing additional system energy consumption; in a cellular-free massive MIMO system with an eavesdropper, the RIS phase shift and position deployment are jointly optimized for the first time to enhance the physical layer security of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0069] Figure 1 The figure is an overall flow chart of a RIS deployment method for non-cellular massive MIMO according to an embodiment of the present invention. DETAILED DESCRIPTION

[0070] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0071] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0072] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0073] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0074] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0075] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] Example 1

[0077] Reference Figure 1 , which is the first embodiment of the present invention, and provides a RIS deployment method for non-cellular massive MIMO, including:

[0078] S1,construct a cell-free massive MIMO point uniformly distributed in the plane, and there is an eavesdropper in the system;

[0079] Furthermore, there is a non-cellular massive MIMO system with M = 20 access points, K = 10 users evenly distributed in a square plane area with a side length of 400 meters, and an eavesdropper in the system;

[0080] Among them, all access points, users, and eavesdroppers are single-antenna devices;

[0081] It should be noted that the distance between the eavesdropper and the target user does not exceed 10 meters;

[0082] S2, using RIS to enhance the physical layer security of the system, and calculating the target user's downlink safe rate that can be achieved with the assistance of RIS;

[0083] Furthermore, RIS is used to enhance the physical layer security of the system, including:

[0084] The wireless channel between the mth access point and the kth user consists of two parts: a direct link and a reflection link. The direct link is a Rayleigh channel and is expressed as:

[0085]

[0086] Among them, β mk represents the large-scale fading coefficient of the direct link from the mth access point to the kth user, h mk represents the small-scale fading coefficient of the direct link from the mth access point to the kth user;

[0087] Furthermore, the reflection link consists of two links from the access point to the RIS and from the RIS to the user. The link from the mth access point to the RIS is expressed as:

[0088]

[0089] In the formula, all subscripts m represent the mth access point, subscript r represents the RIS, subscript k represents the kth user, and subscript e represents the eavesdropper; β mr represents the large-scale fading coefficient of the link from the mth access point to the RIS, K mr represents the Ricean K factor of the mth access point to RIS link, and Respectively represent g mr The LoS component and NLoS component of RIS; the link from RIS to the kth user is expressed as:

[0090]

[0091] Among them, β rk represents the large-scale fading coefficient of the link from RIS to the kth user, K rk represents the Ricean K factor of the RIS to k-th user link, and Respectively represent g rk The LoS component and NLoS component of

[0092] The phase shift matrix of RIS is expressed as:

[0093]

[0094] in, represents the phase shift of the incident signal by the lth reflective element of RIS, L=36 represents the number of reflective elements of RIS; set ρ mk represents the gain coefficient of the reflection link between the mth access point and the kth user. When the mth access point and the kth user are both within the RIS reflection range, ρ mk =1, otherwise ρ mk =0;

[0095] Furthermore, the direct link g mk Reflection link with gain factor Adding them together, the total wireless channel from the mth access point to the kth user is:

[0096]

[0097] The total wireless channel from the mth access point to the eavesdropper e is:

[0098]

[0099] The superscript H represents the conjugate transpose operator, g me represents the direct link between the mth access point and the eavesdropper e, represents the reflection link with gain coefficient between the mth access point and the eavesdropper e;

[0100] It should be noted that all large-scale fading coefficients adopt the model β = d -r ; d represents the Euclidean distance of the corresponding path, r represents the attenuation coefficient on the corresponding path; for all direct links, r = 3.4, for all reflection links, r = 2.1; all Rice K factors are 5dB; the LoS components of all Rice channels adopt the model express The lth element of , θ represents the arrival angle or departure angle of the corresponding path, and θ takes a random value between [0,2π]; the noise power The transmission power p of each access point d =30dBm;

[0101] S3, taking the maximization of the target user's safety rate as the objective function, the gradient descent alternating iterative algorithm is used to obtain the optimal phase shift and deployment position of RIS;

[0102] Furthermore, the steps of the gradient descent alternating iteration algorithm are as follows:

[0103] S301, set the RIS initial position to (Unit: meter), the initial phase shift matrix is ​​Φ 0 , substituting the two into the calculation formula of the safety rate, we get Initialize the iteration step size s1 = 0.1, s2 = 1, and the iteration termination error σ = 10 -5 , iteration variable i,j=0;

[0104] S302, calculate the decreasing direction of the safe rate to the RIS phase shift matrix Iterate the RIS phase shift Based on this, a new safe rate is obtained, denoted as R sec (Φ i+1 );

[0105] S303, set i=i+1, repeat S302 until |R sec (Φ i+1 )-R sec (Φ i )|<σ, the optimal value of phase shift is Φ opt =Φ i+1 ;

[0106] S304, calculate the descending direction of the safe speed to the RIS deployment position Iterate on RIS deployment locations Based on this, a new safe rate is obtained, which is recorded as

[0107] S305, set j=j+1, repeat S304 until So far, the optimal value of the deployment position is

[0108] S306, repeat S302 to S305 until Get the optimal phase shift Φ of RIS opt and optimal deployment location

[0109] Furthermore, this embodiment also provides a RIS deployment system for non-cellular massive MIMO, including:

[0110] RIS controller module, responsible for coordinating and managing the entire RIS network;

[0111] The base station module is responsible for communicating with the user equipment and interacting with the RIS controller module to transmit data to the correct RIS and user equipment modules;

[0112] RIS module for beamforming and signal enhancement;

[0113] The user equipment module is used to communicate with the base station module, receive beamforming signals from the RIS, and send data back to the base station module.

[0114] This embodiment further provides a computer device, which is applicable to the case of a RIS deployment method without cellular massive MIMO, including:

[0115] A memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the RIS deployment method of non-cellular massive MIMO as proposed in the above embodiment.

[0116] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0117] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the RIS deployment method for non-cellular massive MIMO is implemented as proposed in the above embodiment.

[0118] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0119] Example 2

[0120] Referring to Table 1, a second embodiment of the present invention provides a RIS deployment method for non-cellular massive MIMO, including:

[0121] The beneficial effects of the method of using the present invention are demonstrated by means of simulation experiments, wherein the experimental parameters are all the parameters involved in Example 1;

[0122] Table 1 Optimal RIS phase shift and position

[0123]

[0124]

[0125] The above table shows the influence of RIS deployment position on the safety rate. After optimizing the RIS deployment position and phase shift by the gradient descent alternating iterative algorithm, the safety rate of the system is significantly improved, proving the feasibility of the optimal RIS deployment method proposed in the present invention.

[0126] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A RIS deployment method for non-cellular massive MIMO, characterized in that: include: Construct a cell-free massive MIMO point, where the point is evenly distributed in a plane, and an eavesdropper Eve exists in the system; Use RIS to enhance the physical layer security of the system and calculate the target user's achievable safe downlink rate with the assistance of RIS; Taking the maximum safety rate of the target user as the objective function, the optimal phase shift and deployment position of RIS are obtained; Use RIS to enhance system physical layer security, including: The wireless channel between the mth access point and the kth user consists of two parts: a direct link and a reflection link. The direct link is a Rayleigh channel and is expressed as: Among them, β mk represents the large-scale fading coefficient of the direct link from the mth access point to the kth user, h mk represents the small-scale fading coefficient of the direct link from the mth access point to the kth user; The reflection link consists of two links from the access point to the RIS and from the RIS to the user. The link from the mth access point to the RIS is expressed as: In the formula, all subscripts m represent the mth access point, subscript r represents the RIS, subscript k represents the kth user, and subscript e represents the eavesdropper; β mr represents the large-scale fading coefficient of the link from the mth access point to the RIS, K mr represents the Ricean K factor of the mth access point to RIS link, and Respectively represent g mr The LoS component and NLoS component of RIS; the link from RIS to the kth user is expressed as: Among them, β rk represents the large-scale fading coefficient of the RIS to the kth user link, K rk represents the Ricean K factor of the RIS to k-th user link, and Respectively represent g rk The LoS component and NLoS component of The phase shift matrix of RIS is expressed as: in, represents the phase shift of the incident signal by the lth reflective element of RIS, L represents the number of reflective elements of RIS; set ρ mk represents the gain coefficient of the reflection link between the mth access point and the kth user. When the mth access point and the kth user are both within the RIS reflection range, ρ mk =1, otherwise ρ mk =0; The direct link g mk Reflection link with gain factor Adding them together, the total wireless channel from the mth access point to the kth user is: The total wireless channel from the mth access point to the eavesdropper e is: The superscript H represents the conjugate transpose operator, g me represents the direct link between the mth access point and the eavesdropper e, represents the reflection link with gain coefficient between the mth access point and the eavesdropper e; Calculate the target user's achievable safe downlink rate with the assistance of RIS, including: Calculate the safe rate R sec =log2(1+SNR k )-log2(1+SNR e ); Signal-to-noise ratio (SNR) of the eavesdropped user k It is expressed as: The eavesdropper's signal-to-noise ratio (SNR) e It is expressed as: The superscript * indicates the conjugate operator. and is the noise power of the eavesdropped user and the eavesdropper, p d is the transmission power of each access point; k′ represents any one of the k-1 users except the kth user; M represents both the total number of access points and the mark of the last access point; represents the product of the LoS components of the reflection link from the mth AP to the kth user; represents the power gain of the reflection link from the mth AP to the kth user; in: Indicates the amplitude of the reflection link from the mth AP to the kth user; in: The calculation factor representing the target user's useful signal power; The objective function is to maximize the safety rate of the target user, including: With the goal of maximizing the traversal security rate of the eavesdropped user, under the constraints of RIS phase shift and position, the optimal RIS phase shift and optimal position deployment are found, and the following optimization problem is established: Among them, (x r ,y r ) is the location coordinate of RIS; S represents the regional scope of the system; Obtain the optimal phase shift and deployment position of the RIS, including: The optimization problem is solved using a gradient descent alternating iterative algorithm to obtain the optimal RIS phase shift and optimal position deployment; The gradient descent alternating iterative algorithm comprises: Set the RIS initial position to The initial phase shift matrix is ​​Φ 0 , substituting the two into the calculation formula of the safety rate, we get Initialize the iteration step size s1, s2> 0, the iteration termination error σ> 0, and the iteration variables i, j = 0; Calculate the decreasing direction of the safe rate to the RIS phase shift matrix Iterate the RIS phase shift Based on this, a new safe rate is obtained, denoted as R sec (Φ i+1 ); Set i=i+1 and repeat R sec (Φ i+1 ) calculation steps until R sec (Φ i+1 )-R sec (Φ i )|<σ, the optimal value of phase shift is Φ opt =Φ i+1 ; Calculate the safe rate of descent direction to the RIS deployment location Iterate on RIS deployment locations Based on this, a new safe rate is obtained, which is recorded as Set j = j + 1, repeat The calculation steps are as follows: So far, the optimal value of the deployment position is Repeat all the above calculation steps until Get the optimal phase shift Φ of RIS opt and optimal deployment location 2. The RIS deployment method for non-cellular massive MIMO as claimed in claim 1, characterized in that: The method of constructing a cellular-free massive MIMO point includes: In a non-cellular massive MIMO system, there are M access points, K users are evenly distributed in the plane, and there is an eavesdropper in the system; Among them, all access points, users and eavesdroppers are single-antenna devices.

3. A RIS deployment system for non-cellular massive MIMO, based on the RIS deployment method for non-cellular massive MIMO according to any one of claims 1 to 2, characterized in that: include: RIS controller module, responsible for coordinating and managing the entire RIS network; The base station module is responsible for communicating with the user equipment and interacting with the RIS controller module to transmit data to the correct RIS and user equipment modules; RIS module for beamforming and signal enhancement; A user equipment module, used to communicate with the base station module, receive beamforming signals from the RIS, and send data back to the base station module; Use RIS to enhance system physical layer security, including: The wireless channel between the mth access point and the kth user consists of two parts: a direct link and a reflection link. The direct link is a Rayleigh channel and is expressed as: Among them, β mk represents the large-scale fading coefficient of the direct link from the mth access point to the kth user, h mk represents the small-scale fading coefficient of the direct link from the mth access point to the kth user; The reflection link consists of two links from the access point to the RIS and from the RIS to the user. The link from the mth access point to the RIS is expressed as: In the formula, all subscripts m represent the mth access point, subscript r represents the RIS, subscript k represents the kth user, and subscript e represents the eavesdropper; β mr represents the large-scale fading coefficient of the link from the mth access point to the RIS, K mr represents the Ricean K factor of the mth access point to RIS link, and Respectively represent g mr The LoS component and NLoS component of RIS; the link from RIS to the kth user is expressed as: Among them, β rk represents the large-scale fading coefficient of the RIS to the kth user link, K rk represents the Ricean K factor of the RIS to k-th user link, and Respectively represent g rk The LoS component and NLoS component of The phase shift matrix of RIS is expressed as: in, represents the phase shift of the incident signal by the lth reflective element of RIS, L represents the number of reflective elements of RIS; set ρ mk represents the gain coefficient of the reflection link between the mth access point and the kth user. When the mth access point and the kth user are both within the RIS reflection range, ρ mk =1, otherwise ρ mk =0; The direct link g mk Reflection link with gain factor Adding them together, the total wireless channel from the mth access point to the kth user is: The total wireless channel from the mth access point to the eavesdropper e is: The superscript H represents the conjugate transpose operator, g me represents the direct link between the mth access point and the eavesdropper e, represents the reflection link with gain coefficient between the mth access point and the eavesdropper e; Calculate the target user's achievable safe downlink rate with the assistance of RIS, including: Calculate the safe rate R sec =log2(1+SNR k )-log2(1+SNR e ); Signal-to-noise ratio (SNR) of the eavesdropped user k It is expressed as: The eavesdropper's signal-to-noise ratio (SNR) e It is expressed as: The superscript * indicates the conjugate operator. and is the noise power of the eavesdropped user and the eavesdropper, p d is the transmission power of each access point; k′ represents any one of the k-1 users except the kth user; M represents both the total number of access points and the mark of the last access point; represents the product of the LoS components of the reflection link from the mth AP to the kth user; represents the power gain of the reflection link from the mth AP to the kth user; in: Indicates the amplitude of the reflection link from the mth AP to the kth user; in: The calculation factor representing the target user's useful signal power; The objective function is to maximize the safety rate of the target user, including: With the goal of maximizing the traversal security rate of the eavesdropped user, under the constraints of RIS phase shift and position, the optimal RIS phase shift and optimal position deployment are found, and the following optimization problem is established: Among them, (x r ,y r ) is the location coordinate of RIS; S represents the regional scope of the system; Obtain the optimal phase shift and deployment position of the RIS, including: The optimization problem is solved using a gradient descent alternating iterative algorithm to obtain the optimal RIS phase shift and optimal position deployment; The gradient descent alternating iterative algorithm comprises: Set the RIS initial position to The initial phase shift matrix is ​​Φ 0 , substituting the two into the calculation formula of the safety rate, we get Initialize the iteration step size s1, s2> 0, the iteration termination error σ> 0, Iteration variables i,j = 0; Calculate the decreasing direction of the safe rate to the RIS phase shift matrix and iterate the RIS phase shift Based on this, a new safe rate is obtained, denoted as R sec (Φ i+1 ); Set i=i+1 and repeat R sec (Φ i+1 ) calculation steps until |R sec (Φ i+1 )-R sec (Φ i )|<σ, the optimal value of phase shift is Φ opt =Φ i+1 ; Calculate the safe rate of descent direction to the RIS deployment location Iterate on RIS deployment locations Based on this, a new safe rate is obtained, which is recorded as Set j = j + 1, repeat The calculation steps are as follows: So far, the optimal value of the deployment position is Repeat all the above calculation steps until Get the optimal phase shift Φ of RIS opt and optimal deployment location 4. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 2 are implemented.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 2 are implemented.

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