Semi-static phase design method, system and medium for RIS-assisted communication system

Abstract

The present invention discloses a semi-static phase design method, system and medium for a RIS-assisted communication system, wherein the method comprises: establishing a channel model of a RIS-assisted link; exploring the working modes in different scenarios of RIS, and analyzing the phase design requirements of RIS in different scenarios; grouping RIS element surfaces according to the coverage requirements and channel models of RIS, and designing the phase compensation of each element surface by using beam broadening technology; and compensating for the gain loss caused by beam broadening by increasing the number of element surfaces. The present invention reasonably designs the phase of the subarray according to the indoor coverage requirements and the user data transmission rate requirements by using beam broadening technology, and provides relatively stable link support for mobile user terminals. The present invention can be widely used in the field of wireless communication optimization technology.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication optimization, and in particular to a semi-static phase design method, system and medium for a RIS-assisted communication system. Background Art

[0002] RIS features simple functions, a streamlined structure, and is easy to deploy. The size and shape of the reflective surface can be customized to meet specific needs, allowing it to be deployed on building exteriors, ceilings, factory interiors, windows, vehicle roofs, and even clothing. As a promising technical solution for 6G communication systems, RIS operates in three main modes for different deployment scenarios: static beam coverage, semi-static beam coverage, and dynamic beamforming. The static beam coverage mode presents a significant drawback: limited signal coverage. In this case, the RIS acts as a passive reflector and lacks phase design. In dynamic beamforming, the beam must track mobile users in real time, continuously adjusting and optimizing phase and base station power. This complicates channel estimation and increases system overhead in practical applications. In certain indoor environments, the semi-static beam coverage mode can provide stable link support for mobile users without ultra-high transmission rate requirements without increasing control overhead, making it suitable for specific communication scenarios. However, currently, there is a lack of deployment design solutions for these three modes in indoor scenarios.

[0003] Explanation of terms:

[0004] Reconfigurable Intelligent Surface (RIS): RIS technology is a technology that optimizes wireless signals in wireless transmission networks. RIS is composed of a large number of low-cost passive reflective elements. It can intelligently configure the wireless propagation environment by adjusting the phase / amplitude of signal reflection to improve communication system performance.

[0005] Semi-static: The RIS metasurface phase is designed based on operational needs. Once fixed, the beam direction is usually fixed as well, eliminating the need for real-time phase adjustment and preventing user-specific beamforming. The phase can be redesigned based on changes in operational conditions. Summary of the Invention

[0006] In order to at least partially solve one of the technical problems existing in the prior art, the present invention aims to provide a semi-static phase design method, system and medium for a RIS-assisted communication system.

[0007] The technical solution adopted in the present invention is:

[0008] A semi-static phase design method for a RIS-assisted communication system comprises the following steps:

[0009] Establish the channel model of RIS auxiliary link;

[0010] Explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios;

[0011] According to the coverage requirements and channel model of RIS, the RIS element surfaces are grouped and the phase compensation of each element surface is designed using beam broadening technology.

[0012] The gain loss caused by beam broadening is compensated by increasing the number of element surfaces.

[0013] Furthermore, the expression of the channel model is:

[0014]

[0015] Among them, P r is the received power, P t is the transmit power, G t , G r , G u Represent the transmitting antenna gain, receiving antenna gain and unit reflection gain respectively, d x d y represents the unit size, d1 and d2 represent the distance between transmitter and RIS and the distance between RIS and receiver respectively, θ t 、φ t are the elevation and azimuth angles of the incident signal, θ r 、φ r are the elevation angle and azimuth angle of the outgoing signal, respectively. g1 and g2 represent the g1th row and g2th column of the reconfigurable smart surface. is the radiation pattern of power, is the RIS unit reflection coefficient; G is the number of RIS element surfaces, G1 and G2 represent the number of RIS element surfaces in the Y and X directions respectively.

[0016] Furthermore, RIS is deployed on indoor walls or ceilings. The analysis of RIS phase design requirements in different scenarios includes:

[0017] When the RIS operates in static beam coverage mode, as a passive reflector, the phase compensation of all RIS element surfaces is constant;

[0018] When RIS operates in dynamic beamforming mode, the phase of the RIS element surface is optimized in real time to enable passive beamforming of the RIS to continuously provide link support to mobile user terminals;

[0019] For scenarios with preset transmission rate requirements, the phase design of the RIS passive reflector is carried out by combining the two working modes: static beam coverage mode and dynamic beamforming mode. On the one hand, the data transmission rate is guaranteed to meet the minimum requirements of the user terminal, and on the other hand, it can provide stable reflection link support for mobile user terminals without the need for real-time phase optimization.

[0020] Furthermore, when the RIS operates in a static beam coverage mode, if the user terminal is located at a position where the signal incident angle and the signal exit angle are equal, the user terminal obtains a greater performance gain.

[0021] Furthermore, the RIS has G element surfaces in a square structure, divided into G1 columns and G2 rows; the G1 column is divided into Q x sub-regions, using Q xq Indicates that each region has τ x =G / Q x Element surface, Q x =1, 2, ..., G1; divide G2 into Q y sub-regions, using Q yq Indicates that each region has τ y =G / Q y Element surface, Q y =1, 2, ..., G2.

[0022] Furthermore, the RIS element surfaces are grouped according to the coverage requirements and channel model of the RIS, and the phase compensation of each element surface is designed using beam broadening technology, including:

[0023] The gain of the channel model is obtained, and the gain and beam widening technology are combined to perform phase compensation on the sub-arrays in each area of ​​the RIS. The coverage range is improved at the expense of gain, so that the user terminal can obtain relatively stable link support throughout the entire mobile range.

[0024] Furthermore, the gain β of the channel model is constructed and expressed using the relative position relationship between the base station, the RIS, and the user terminal. The specific expression is as follows:

[0025]

[0026] Where G1 and G2 represent the number of element surfaces of RIS in the Y and X directions respectively, θ t 、φ t are the elevation and azimuth angles of the incident signal, θ r 、φ r are the elevation and azimuth angles of the outgoing signal, d x d y represents the unit size, and λ represents the signal wavelength.

[0027] Furthermore, performing phase compensation on the sub-arrays in each area on the RIS includes:

[0028] The total phase compensation of RIS Decomposed into ε in the X and Y directions x and ε y , let the first and second terms of array gain β be S1 and S2 respectively, β=S1·S2, for different regions Q xq , Q yq Different phase designs are performed on the metasurface:

[0029]

[0030]

[0031] Let v q = sinθ t cosφ t +sinθ r cosφ r ,

[0032] The phase compensation in the X direction is as follows:

[0033] Obtain the emission angle θ based on the possible position changes of the user in the indoor environment r ,φ r The fluctuation range of ψ(θ, φ) = (sinθ t cosφ t +sinθ r cosφ r )'s upper and lower bounds v max , v min ;

[0034] The total coverage is determined by the number of subarrays Q x The influence of the number of element surfaces G1 must satisfy (Q x -1)Δ s-a ≥v max -v min , in order to satisfy the user to get relatively stable link support in the entire mobile range, the phase ε is designed according to the coverage range of the mobile user. xq as follows:

[0035]

[0036] The design in formula (1) can always make v q In a subarray Q xq within the beam coverage area.

[0037] Another technical solution adopted in the present invention is:

[0038] A semi-static phase design system for a RIS-assisted communication system, comprising:

[0039] A model building module for building a channel model for the RIS auxiliary link;

[0040] The demand analysis module is used to explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios;

[0041] Phase compensation module, which is used to group RIS element surfaces according to the RIS coverage requirements and channel model, and design the phase compensation of each element surface using beam broadening technology;

[0042] The gain compensation module is used to compensate for the gain loss caused by beam broadening by increasing the number of metasurfaces.

[0043] Another technical solution adopted in the present invention is:

[0044] A semi-static phase design system for a RIS-assisted communication system, comprising:

[0045] at least one processor;

[0046] at least one memory for storing at least one program;

[0047] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0048] Another technical solution adopted in the present invention is:

[0049] A computer-readable storage medium stores a program executable by a processor, wherein the program executable by the processor is used to perform the method described above when executed by the processor.

[0050] The beneficial effects of the present invention are as follows: the present invention utilizes beam broadening technology to reasonably design the phase of the subarray according to indoor coverage requirements and user data transmission rate requirements, thereby providing relatively stable link support for mobile user terminals. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following introduction is made to the drawings of the embodiments of the present invention or the related technical solutions in the prior art. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative work.

[0052] Figure 1 This is a flowchart of the steps of a semi-static phase design method for a RIS-assisted communication system according to an embodiment of the present invention;

[0053] Figure 2 RIS reflection diagram according to an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of several application scenarios of RIS in an embodiment of the present invention;

[0055] Figure 4 1 is a schematic diagram of the performance distribution of a RIS-assisted link system according to an embodiment of the present invention;

[0056] Figure 5 2 is a schematic diagram of beam broadening in an embodiment of the present invention;

[0057] Figure 6 It is an expansion of the surface structure of the RIS element in the embodiment of the present invention;

[0058] Figure 7 1 is a phase design comparison diagram of three schemes in an embodiment of the present invention;

[0059] Figure 8 Schematic diagram of compensation transmission rate VS user coordinates for different numbers of element surfaces in an embodiment of the present invention;

[0060] Figure 9 is a comparison chart of transmission rates under different design parameters in an embodiment of the present invention;

[0061] Figure 10 FIG. 4 is a schematic diagram of deploying multiple RISs in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The 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 are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided for ease of explanation only and do not limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0063] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0064] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0065] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0066] The first existing technical solution proposes a new three-dimensional (3D) wireless system architecture based on aerial RIS (ARIS), with flexible coverage. This architecture maximizes the worst-case signal-to-noise ratio (SNR) at all locations in the target area by jointly optimizing the transmit beamforming of the source node, the placement of the AIRS, and 3D passive beamforming. However, this solution is based on high-altitude deployment optimization and is primarily targeted at open outdoor environments, making it less suitable for optimizing indoor RIS deployment locations. Furthermore, the channel model employed does not consider radiation patterns.

[0067] The second existing technical solution, developed during research on RIS-assisted communication network deployment, found that when the RIS is used as a passive reflector (all element surfaces have fixed phases, but the physical tilt angle can be adjusted), users within a certain range can achieve fairly high channel gain. However, by implementing phase compensation for the RIS as a reconfigurable smart surface, a wider range of users can be covered. However, this solution fails to combine the advantages of both the RIS as a reconfigurable smart surface and as a passive reflector, and does not address phase design for the RIS deployed at a fixed location.

[0068] In order to overcome the deficiencies in the prior art, an embodiment of the present invention provides a semi-static beamforming phase design for a downlink communication system assisted by RIS. For some common indoor scenarios, RIS can be used to fill in blind spots / expand coverage, and by rationally designing phase compensation, beam widening technology can be used to provide relatively stable reflection link support for mobile users within the coverage area without the need to adjust the phase compensation of the RIS element surface in real time. Combining the advantages of RIS as a passive reflective surface and a reconfigurable intelligent surface, the RIS-assisted wireless network deployment environment is greatly simplified, providing a new approach for the research on large-scale deployment of RIS. This promotes the optimization of RIS-assisted communication systems and accelerates the implementation of RIS in smart factories.

[0069] like Figure 1 As shown, this embodiment provides a semi-static phase design method for a RIS-assisted communication system. For a fixed-location RIS structure indoors, this method leverages the advantages of RIS as a passive reflector and reconfigurable smart surface and utilizes beam broadening technology to provide relatively stable link support for users within a certain coverage area. This provides a new deployment strategy for future large-scale RIS deployments. The method specifically includes the following steps:

[0070] S1. Establish a channel model for the RIS auxiliary link.

[0071] The free-space path loss model of RIS-assisted wireless communication is related to the distance between the transmitter / receiver and the RIS, the size of the RIS, the near-field / far-field effects of the RIS, and the radiation patterns of the antenna and unit cells. Therefore, when deploying RIS in indoor environments, these factors must be fully considered to maximize system performance. At the same time, various practical factors such as deployment / operation costs, user needs / distribution, spatial constraints, and the propagation environment must also be taken into account.

[0072] See also Figure 2 ,θ t 、φ t is the information parameter about the incident angle, θ r 、φ r is the information parameter about the exit angle. According to the existing comprehensive path loss model, the expression of the channel model is as follows:

[0073]

[0074] Among them, P r is the received power, P t is the transmit power, G t , G r , G u Represent the transmitting antenna gain, receiving antenna gain and unit reflection gain respectively, d x d yIndicates the unit size, d1 and d2 represent the distance between transmitter and RIS and the distance between RIS and receiver respectively. is the radiation pattern of power (comprehensive coefficient of transmitting antenna pattern + receiving antenna pattern + unit reflection pattern), is the RIS unit reflection coefficient. The difference in propagation distance of the element surface is determined by the incident and exit angles. G is the number of RIS element surfaces. G1 and G2 represent the number of element surfaces in the X and Y directions of the RIS respectively (g1 and g2 represent the number of element surfaces). Assume that the peak radiation direction of the transmitting antenna and the receiving antenna are both pointing to the center of the RIS, that is,

[0075] S2. Explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios.

[0076] When reconfigurable smart surfaces are deployed in complex indoor environments, common working modes include static beam coverage, such as Figure 3 As shown in the scenario for user 2 in (a), the RIS is deployed on an indoor wall or ceiling, blocking the direct link between user 2 and the transmitter. The RIS operates in static beam coverage mode. As a passive reflector, the phase compensation of all components is constant. A significant performance gain can only be achieved when user 2 is at a position where the incident and exit angles are equal. The RIS cannot provide stable link support for user 2 who needs to move indoors. Figure 3 In the scenario for user 1 in (a), the RIS is deployed on an indoor wall or ceiling and operates in dynamic beamforming mode. As user 1 moves, the phase of the RIS element surface is optimized in real time using a corresponding algorithm. This passive beamforming of the RIS can replace the MIMO antenna to continuously provide good link support to the mobile user. However, this approach is complex and expensive to implement, especially in multi-user scenarios.

[0077] In some scenarios where a particularly high transmission rate is not required, we can combine the two working modes and make some phase design on the passive reflector. On the one hand, the data transmission rate can meet the user's minimum requirements, and on the other hand, it can provide stable reflection link support for mobile users without the need for real-time phase optimization. Figure 3 As shown in the scenario of user 1 in (b), after properly designed phase, a certain array gain is sacrificed but the coverage of the beam is expanded, so that the user can obtain stable channel gain while moving within a certain range. Figure 3 As shown in (b), for users 2 and 3, the designed phase does not require phase adjustment even in multi-user scenarios. The performance gain of the multi-user system can be improved by optimizing power allocation and other methods, providing relatively stable channel support for multiple users.

[0078] Figure 4 Channel gain simulation diagram for RIS as a reconfigurable smart surface to achieve dynamic beamforming and RIS as a passive reflector to provide link support:

[0079] Depend on Figure 4 (a) It can be seen that for a single-user system, RIS, as a reconfigurable smart surface, adjusts phase compensation so that the user can obtain a higher channel gain within a circular area. The channel gain gradually decays with the increase of the radius. Figure 4 (b) shows that RIS, as a passive reflector, can also provide higher channel gain in a very small coverage area, but it exhibits a greater degree of attenuation depending on the user's location.

[0080] S3. According to the coverage requirements and channel model of RIS, the RIS element surfaces are grouped and the phase compensation of each element surface is designed using beam broadening technology.

[0081] In the embodiment of the present invention, beam broadening technology is used to change the antenna pattern shape by changing various parameters of the phased array antenna, so that it has a wider main lobe. The gain part β of the channel model can be constructed and expressed by the relative position relationship between the base station, RIS, and user. Let Using the knowledge of geometric series we can get:

[0082]

[0083]

[0084] When sinθ t cosφ t +sinθ r cosφ r =0, sinθ t sinφ t +sinθ r sinφ r =0, at this time β reaches the maximum value G1G2. The beam widening technology is to design the phase so that the antenna array has a wider main lobe to improve the coverage range. Figure 3 In the indoor scenario shown, RIS is deployed on the wall. When the user group moves, in order to ensure the coverage, phase compensation is required in both X and Y directions. The specific design steps are as follows: RIS has G element surfaces, a square structure, divided into G1 columns and G2 rows. We divide G1 column into Q x sub-regions, using Q xq Indicates that each region has τ x =G / Q x Element surface, Q x=1, 2, ..., G1, note that it must satisfy Divide column G2 into Q y sub-regions, using Q yq Indicates that each region has τ y =G / Q y Element surface, Q y =1,2,...,G2, satisfying Design sub-arrays in each area and perform phase compensation uniformly to obtain a larger coverage range at the expense of a certain gain.

[0085] We compensate the total phase of RIS Decomposed into ε in the X and Y directions x and ε y For the convenience of expression, let the first and second terms of the array gain β be S1 and S2 respectively, and β = S1·S2. xq , Q yq Different phase designs are performed on the metasurface:

[0086]

[0087]

[0088] Let v q = sinθ t cosφ t +sinθ r cosφ r , We can use the function for the above conversion process The properties of the image are explained:

[0089] like Figure 5 As shown, the peak of the function is at v q = 0, we have |S(0)| = G1. For a single user, the set of function values ​​​​of 0 is g1=1,2,...,G1-1。 S(v q ) is a multi-peak function of oscillation attenuation. The present invention adopts beam broadening technology and only considers v q The coverage width of the three main peaks near zero is half of the maximum main peak width, and the rest of the waveforms are ignored. Before phase optimization, the beam coverage width is The user only needs to meet the location condition v q →0 has better channel gain The signal strength at other locations is greatly attenuated; after optimizing the phase, the user's location condition v q Satisfy v min ≤v q ≤v maxWhen , a relatively stable channel gain can be obtained. Since the gains of the two outermost sub-arrays are small, we define the optimized Q x The total beam coverage of the superposition of the sub-arrays is (Q x -1)Δ s-a .

[0090] in The beam coverage width of each sub-array is θ. We take the X-axis direction as an example to analyze and obtain the emission angle θ according to the possible position changes of the user in the indoor environment. r ,φ r The fluctuation range of Ψ(θ,φ)=(sinθ t cosφ t +sinθ r cosφ r )'s upper and lower bounds v max , v min .

[0091] The total coverage is determined by the number of subarrays Q x The influence of the number of element surfaces G1 must satisfy (Q x -1)Δ s-a ≥v max -ν min , in order to satisfy the user to get relatively stable link support in the entire mobile range, the present invention designs the phase ε according to the coverage range of the mobile user. xq as follows:

[0092]

[0093] The above design can always make v q In a subarray Q xq In the beam coverage range of , for this subarray function, there is |S(-ε xq )|=G1 / Q x , the Y-axis phase design method is the same as above.

[0094] The following is described with reference to specific embodiments:

[0095] Simulation main parameter settings: To highlight the simulation results, the deployment method of RIS is similar to Figure 3 Slightly different, deployed close to the wall, incident angle sinθ t 、cosφ t No change, let θ t =90°,φ t =180°. Number of RIS element surfaces G = 256, G1 = G2 = 16, θ t =90°,φ t=180°, divide the RIS into 4 areas (Q=4) in the X and Y directions. According to the deployment height of 12 (m), the user's exit angle θ in this area is calculated. r The range of variation is approximately φ r The range is (0, 2π),

[0096] Beam coverage width of the subarray At this time, v max -v min ≤(Q-1)Δ s-a , further design the phase compensation in the X direction according to the above design scheme, The same design is performed in the Y direction.

[0097] The above solution does not need to optimize the phase in real time according to the user / device location, which can greatly simplify the network architecture and control overhead of large-scale RIS deployment. However, beam broadening technology sacrifices a certain amount of array gain. Due to the low cost of RIS element surface, such as Figure 6 As shown, the present invention compensates for array gain loss by increasing the number of RIS element surfaces. Gain compensation is achieved by increasing the number of low-cost element surfaces in the X (or Y) direction by N1·G1 (N2·G2) (N represents the number of rows added). Still taking the X direction as an example, adding N1 columns of element surfaces allows the first term S1 of the array gain β to be:

[0098]

[0099] There are two requirements for the selection of N1. First, It can be seen that when the number of element surfaces increases, the coverage of the array gain function will become smaller and smaller, and the coverage must satisfy (Q x -1)Δ s-a ≥v max -v min ; Second, as the surface size of the RIS element increases, the boundary between the far field and the near field will also change. In the present invention, we need to ensure that the user position meets the far-field channel model conditions of the RIS.

[0100] As an optional implementation, the specific steps of phase compensation are shown in Table 1 below:

[0101] Table 1

[0102]

[0103] Note: When selecting, you must consider the actual situation and ensure that parameters such as the number of divided areas and the number of element surfaces are integers.

[0104] As an optional embodiment, Figure 10As shown, using one or more RIS to perform the same phase design in different environments (with different actual parameters) can achieve the same effect as this embodiment and are all alternative solutions of the present invention.

[0105] The simulation results of the method analysis of this embodiment are as follows:

[0106] Figure 7 The figure shows the simulated relationship between data transmission rate and user location along the X-axis. This paper compares the performance curves of the RIS under three operating modes: Using beamforming technology achieves the highest data transmission rate while providing the largest coverage range and stable link support for mobile users. This technology requires real-time phase adjustment and compensation in the RIS, which incurs certain energy consumption. When the RIS acts as a passive reflector without phase optimization, its coverage range is greatly reduced, and users can only achieve high transmission rates within a very small range.

[0107] The beam-broadening technology employed in this paper designs the phase of the RIS in blocks based on indoor coverage and user transmission rate requirements, providing continuous and stable link support for mobile users (no RIS phase adjustment is required during mobility). Compared to passive reflectors, beam-broadening significantly improves coverage by properly designing the RIS phase, making it suitable for stable connections. Compared to beamforming, beam-broadening sacrifices some array gain but eliminates the need for real-time phase adjustment, reducing wireless network control overhead. Simulation results fully align with the theoretical analysis above.

[0108] S4. Compensate for the gain loss caused by beam broadening by increasing the number of metasurfaces.

[0109] Figure 8 The following figure shows the simulated relationship between data transmission rate and user position along the X-axis for different numbers of metasurfaces. Simulation results show that the gain loss caused by beam broadening can be compensated by appropriately increasing the number of metasurfaces. In semi-static operation mode, the performance improvement achieved by combining beam broadening with increasing the number of metasurfaces is significant. The simulation results are consistent with theoretical analysis. Furthermore, due to the low cost of RIS metasurfaces, increasing the number of metasurfaces is relatively inexpensive and feasible.

[0110] Figure 9 This figure shows the simulated relationship between data transmission rate and user location along the X-axis, obtained by selecting different parameters according to the coverage optimization process provided by the present invention. By properly adjusting the parameters, combining beam broadening technology with an increased number of metasurfaces can achieve superior coverage and maximum transmission rates compared to beamforming technology, demonstrating the effectiveness of the present invention.

[0111] In summary, this embodiment has the following advantages and beneficial effects compared to the prior art:

[0112] (1) In some indoor environments, for devices or users that do not require high-speed data transmission, beam broadening technology can provide users with relatively stable link support. For mobile users, it can provide high gain performance without the need for real-time phase compensation adjustment.

[0113] (2) As a new indoor deployment solution, the deployment method provided by the present invention can be applied to some specific indoor scenarios. By appropriately designing the phase, the beam coverage range is expanded and the number of metasurfaces is increased to improve the reflection link gain. There is no need for real-time phase optimization, which can simplify the architecture of large-scale RIS deployment to a certain extent.

[0114] (3) The present invention compensates for the array gain loss caused by the beam broadening technology by increasing the number of low-cost element surfaces.

[0115] This embodiment further provides a semi-static phase design system for a RIS-assisted communication system, including:

[0116] A model building module for building a channel model for the RIS auxiliary link;

[0117] The demand analysis module is used to explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios;

[0118] Phase compensation module, which is used to group RIS element surfaces according to the RIS coverage requirements and channel model, and design the phase compensation of each element surface using beam broadening technology;

[0119] The gain compensation module is used to compensate for the gain loss caused by beam broadening by increasing the number of metasurfaces.

[0120] A semi-static phase design system for a RIS-assisted communication system according to this embodiment can execute a semi-static phase design method for a RIS-assisted communication system provided by a method embodiment of the present invention, can execute any combination of implementation steps of the method embodiment, and has the corresponding functions and beneficial effects of the method.

[0121] This embodiment further provides a semi-static phase design system for a RIS-assisted communication system, including:

[0122] at least one processor;

[0123] at least one memory for storing at least one program;

[0124] When the at least one program is executed by the at least one processor, the at least one processor implements Figure 1 The method shown.

[0125] A semi-static phase design system for a RIS-assisted communication system according to this embodiment can execute a semi-static phase design method for a RIS-assisted communication system provided by a method embodiment of the present invention, can execute any combination of implementation steps of the method embodiment, and has the corresponding functions and beneficial effects of the method.

[0126] The present application also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs Figure 1 The method shown.

[0127] This embodiment also provides a storage medium storing instructions or programs capable of executing a semi-static phase design method for a RIS-assisted communication system provided by an embodiment of the method of the present invention. When the instructions or program are executed, any combination of implementation steps of the embodiment of the method can be executed, achieving the corresponding functions and beneficial effects of the method.

[0128] In some optional embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided in an exemplary manner for the purpose of providing a more comprehensive understanding of the technology. The disclosed method is not limited to the operation and logic flow presented herein. Optional embodiments are contemplated in which the order of the various operations is changed and the sub-operations described as a part of a larger operation are performed independently.

[0129] Furthermore, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise indicated, one or more of the functions and / or features described may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in separate physical devices or software modules. It will also be understood that a detailed discussion of the actual implementation of each module is not necessary for understanding the present invention. More specifically, given the properties, functions, and internal relationships of the various functional modules in the devices disclosed herein, the actual implementation of the module will be understood within the ordinary skill of an engineer. Therefore, a person skilled in the art using ordinary skill will be able to implement the present invention set forth in the claims without undue experimentation. It will also be understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0130] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0131] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0132] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0133] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0134] In the above description of this specification, reference to the terms "one embodiment / example," "another embodiment / example," or "certain embodiments / examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0135] While 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 invention, and that the scope of the invention is defined by the claims and their equivalents.

[0136] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A semi-static phase design method for a RIS-assisted communication system, characterized in that: The following steps are involved: Establish the channel model of RIS auxiliary link; Explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios; According to the coverage requirements and channel model of RIS, the RIS element surfaces are grouped, and the phase compensation of each element surface is designed using beam broadening technology; The gain loss caused by beam broadening is compensated by increasing the number of element surfaces; The expression of the channel model is: Among them, P r is the received power, P t is the transmission power, G t , G r , G u Represent the transmitting antenna gain, receiving antenna gain and unit reflection gain respectively, d x d y represents the unit size, d1 and d2 represent the distance between the transmitter and RIS and the distance between the RIS and the receiver, respectively, and θ t ,φ t are the elevation angle and azimuth angle of the incident signal, θ r ,φ r are the elevation angle and azimuth angle of the outgoing signal, respectively. g1 and g2 represent the g1th row and g2th column of the reconfigurable smart surface. is the radiation pattern of power, is the RIS unit reflection coefficient; G is the number of RIS element surfaces, G1 and G2 represent the number of RIS element surfaces in the Y and X directions respectively; RIS is deployed on the indoor wall or ceiling. The phase design requirements of RIS in different scenarios are analyzed, including: When RIS works in static beam coverage mode, as a passive reflector, the phase compensation of all RIS element surfaces is constant; when RIS works in dynamic beamforming mode, the phase of the RIS element surface is optimized in real time to enable passive beamforming of RIS to continuously provide link support to mobile user terminals; In scenarios with preset transmission rate requirements, the phase of the passive reflector of RIS is designed by combining the two working modes of static beam coverage mode and dynamic beamforming mode: on the one hand, the data transmission rate meets the minimum requirements of the user terminal, and on the other hand, it can provide stable reflection link support for the mobile user terminal without the need for real-time phase optimization; The RIS element surfaces are grouped according to the coverage requirements and channel model of the RIS, and the phase compensation of each element surface is designed by using the beam broadening technology, including: Obtain the gain of the channel model, combine the gain and beam widening technology, and perform phase compensation on the sub-arrays in each area on the RIS, thereby increasing the coverage range at the expense of gain, so that the user terminal can obtain relatively stable link support within the entire mobile range; The gain β of the channel model is constructed and expressed using the relative position relationship between the base station, RIS, and the user terminal. The specific expression is as follows: In the formula, G1 and G2 represent the number of element surfaces of RIS in the Y and X directions respectively, θ t ,φ t are the elevation angle and azimuth angle of the incident signal, θ r ,φ r are the elevation angle and azimuth angle of the outgoing signal, d x d y represents the unit size, λ represents the signal wavelength; The phase compensation of the sub-arrays in each area on the RIS includes: The total phase compensation of RIS Decomposed into ε in the X and Y directions x and ε y , let the first and second terms of the array gain β be S1 and S2 respectively, β = S1·S2, for different regions Q xq , Q yq Different phase designs are performed on the metasurface: Let v q = sinθ t cosφ t +sinθ r cosφ r , Among them, the phase compensation in the X direction is as follows: Obtain the emission angle θ based on the possible position changes of the user in the indoor environment r ,φ r The fluctuation range of Ψ(θ, φ) = (sinθ t cosφ t +sinθ r cosφ r ) has an upper and lower bound v max , v min ; The total coverage is determined by the number of subarrays Q x The influence of the number of element surfaces G1 must satisfy (Q x -1)Δ s-a ≥v max -v min , in order to satisfy the user to get relatively stable link support in the entire mobile range, the phase ε is designed according to the coverage range of mobile users. xq as follows: The design in formula (1) always makes ν q In a subarray Q xq within the beam coverage area.

2. The semi-static phase design method of a RIS-assisted communication system according to claim 1, characterized in that: The RIS has G element surfaces, which are in a square structure and are divided into G1 columns and G2 rows. The G1 column is divided into Q x sub-regions, using Q xq Indicates that each region has τ x =G / Q x The surface of the element, Q x =1, 2, ..., G1; divide G2 into Q y sub-regions, using Q yq Indicates that each region has τ y =G / Q y The surface of the element, Q y =1, 2, ..., G2.

3. A semi-static phase design system for a RIS-assisted communication system, applied to a semi-static phase design method for a RIS-assisted communication system according to claim 1 or 2, characterized in that: include: A model building module, used to build a channel model of the RIS auxiliary link; The demand analysis module is used to explore the working modes of RIS in different scenarios and analyze the phase design requirements of RIS in different scenarios; A phase compensation module is used to group RIS element surfaces according to the coverage requirements and channel model of RIS, and design the phase compensation of each element surface using beam broadening technology; The gain compensation module is used to compensate for the gain loss caused by beam broadening by increasing the number of element surfaces.

4. A semi-static phase design system for a RIS-assisted communication system, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 1 to 2.

5. A computer-readable storage medium storing a program executable by a processor, characterized in that: The processor-executable program is used to perform the method according to any one of claims 1 to 2 when executed by the processor.

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