A vehicle networking 5G base station site selection method for urban roads

Abstract

The application provides a vehicle networking 5G base station site selection method for urban roads, and belongs to the technical field of computer networks. The base station site selection problem of covering all areas with the least number of 5G base stations in urban roads is solved. The technical scheme comprises the following steps: S1: calculating the road network density of each road; S2: calculating the distance influence degree between intersections; S3: calculating the traffic flow level parameters of each road; S4: defining the communication demand metric and creating a weight coefficient matrix; S5: setting the constraint condition; S6: designing 5G base stations to cover all areas. The beneficial effects of the application are as follows: in the case of considering the service capability of the base station and minimizing the number of base stations, each base station can quickly assist all vehicles to access the network, thereby improving the data access speed and response time, reducing the network delay, and improving the performance and throughput of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer networks, and particularly relates to a 5G base station site selection method for urban roads. BACKGROUND

[0002] In real traffic applications, user demand is increasing, and 5G communication technology has emerged as the times require. It not only provides faster and more convenient communication services for humans, but also supports the connection of a large number of Internet of Things (IoT) devices. Compared with 4G networks, 5G networks have faster transmission rates and lower latencies, and can support more efficient and faster mobile communication services. Since the electromagnetic wave frequency range of 5G communication is 3GHz-300GHz, the working frequency is relatively high, and the diffraction and penetration ability of millimeter wave signals is weak. Therefore, to achieve the same signal coverage and connection stability as 4G communication, the deployment density of 5G base stations should be higher than that of 4G. However, the deployment of 5G base stations also needs to consider the cost and signal interference. If multiple base stations are set up in an area where one base station can already provide sufficient service, it will result in waste of cost and interference between multiple base stations, reducing the stability and reliability of network communication. The deployment of 5G base stations has become a major technical challenge.

[0003] Through domestic and foreign literature retrieval, it is found that the existing paper "A Bi-objective Optimal Scheme for 5G Base Station Deployment Based on BPSO" (Lecture Notes in Electrical Engineering, 2022) proposes two optimal target 0-1 programming models for 5G base stations based on coverage sets. A solution scheme based on a binary particle swarm optimization (BPSO) algorithm is proposed using the divide-and-conquer idea and parallelization strategy. First, the target area is divided into many smaller sub-areas using the hierarchical balanced iterative reduction clustering algorithm (BIRCH). Then, the BPSO algorithm is improved using sparse particle initialization and suppression factors, combined with parallel computing and memory mapping technology to solve each small sub-area. The purpose is to make the wireless signal coverage of 5G base stations as many as possible, but the cost problem of setting up base stations is not considered.

[0004] The existing paper "Link quality-guaranteed minimum-cost millimeter-wave base station deployment" (arXiv, 2021) proposes a method to solve the problem of millimeter wave BS deployment in urban environments, formulating the minimum-cost BS deployment problem as an integer nonlinear programming (INP). However, the upper limit of the number of users that a base station can serve has not been considered in the influence on the deployment of base stations.

[0005] The existing paper "Base Station Deployment Optimization in Federated Networks with Multi-Hop Communication" (Proceedings-IEEE Military Communications Conference MILCOM, 2022) aims to minimize the number of base stations by linear programming to plan the location of facilities, using trusted multi-hop (or relay) to reach remote devices, but cannot cover all areas in one hop.

[0006] The existing paper "Optimization of Millimeter-Wave Base Station Deployment in 5G Networks" (ICUFN, 2022) aims to minimize the number of base stations and proposes a two-step method to obtain the optimal deployment strategy under a given map. The first step is to apply Canny edge detection and open operation algorithm to detect the edges of the actual map, and the second step is to determine the deployment points on the map according to the quadtree traversal algorithm, achieving a coverage area close to 100%, but still not achieving full coverage and not considering the upper limit of the number of users that a base station can serve.

[0007] In summary, the above existing technologies do not combine the minimization of the number of base stations and the maximization of the coverage area, and do not consider the number of users that a base station can serve simultaneously. The algorithm of the present application takes the number of users that a base station can serve simultaneously as a constraint, achieving full coverage with the minimum number of base stations. Compared with the above technologies, the implementation steps of the present application are less and the load on the base station is lighter. SUMMARY

[0008] The purpose of the present application is to meet the demand for high-speed communication of vehicles and the requirement for cost control of base station deployment, and to reasonably site 5G base stations. Therefore, the present application provides a method for selecting the site of a 5G base station for vehicle networking on urban roads.

[0009] In order to achieve the above-mentioned purpose of the application, the technical solution adopted by the present application is as follows:

[0010] A method for selecting the site of a 5G base station for vehicle networking on urban roads, the method comprising the following steps:

[0011] S1: Calculate the road network density of each road; calculate the road network density of each road by ArcGIS software, and use the road network density as one of the factors to participate in the weight calculation;

[0012] In addition to providing map and data services for clients, the GIS server also supports all functions of GIS workstations on a shared central server, including mapping, spatial analysis, complex spatial query, advanced data editing, distributed data management, batch spatial processing, implementation of spatial geometric integrity rules, etc. The present application uses ArcGIS software to complete the calculation of road network density.

[0013] The road network density reflects the traffic congestion condition. If the roads in a region are dense, one base station can cover multiple roads. If the roads in a region are sparse, i.e. for a certain intersection, other intersections cannot serve it even if a base station is set up, then this intersection also needs to set up a base station to provide services for the roads nearby. Therefore, the road network density is taken as one of the elements to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0014] S2: Calculate the distance influence degree between intersections; determine whether two intersections can cover each other according to the distance between them. If they cannot cover each other, the distance influence degree is 0. If they can cover each other, the distance influence degree is the difference between the 5G base station communication radius and the distance. The distance influence degree between intersections is taken as one of the elements to participate in the weight calculation.

[0015] The distance between intersections reflects the coverage of the base station, i.e. if a 5G base station is set up at an intersection, it can be determined whether it can cover another intersection through the distance, so as to know whether the road between the two intersections can be covered by the base station of the intersection. Therefore, the present application only considers the coverage of the base station to the intersection. In addition, in order to determine whether to set up a base station at the intersection, the signal strength of the base station and the road vehicles also needs to be considered. The smaller the distance, the stronger the signal. The distance influence degree is calculated according to the distance between two intersections to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0016] S3: Calculate the traffic flow level parameter of each road; divide the intersections into four types, define a level parameter to judge the traffic flow according to the traffic flow per unit time of each intersection, and take it as one of the elements to participate in the weight calculation.

[0017] The road traffic flow reflects the traffic flow per unit time of the road. The base station should be placed at the intersection with large traffic flow as much as possible to provide networking services for more vehicles. Therefore, the traffic flow is taken as one of the elements to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0018] S4: Define the communication demand metric and create the weight coefficient matrix; use the road network density, the distance influence degree between intersections and the level parameter to judge the road traffic flow, calculate the communication demand metric of each road through the formula and fill it into the weight coefficient matrix.

[0019] The communication demand metric is defined, a weight coefficient matrix reflecting the road network density, the distance influence degree between intersections and the road daily traffic volume is designed, and the demand degree of each road for the base station is embodied;

[0020] According to the communication demand metric, the 5G base station site selection is carried out, and the covered intersections are selected for the intersections where the base stations are arranged, so that the number of base stations is minimized and the base stations can cover the whole area, so that the application selects the base station setting place and the covered intersection to minimize the number of base stations and maximize the average weight in the urban scene, so as to guarantee the high efficiency and high reliability of data transmission.

[0021] S5: setting a constraint condition; taking the upper limit of the number of users that can be served by one base station as the constraint condition, and selecting the covered intersection of each base station;

[0022] Since the number of users that can be served by a base station is limited, the maximum number of users that can be provided with online service by one base station at the same time is taken as a constraint, that is, the total number of users in the area covered by the base station is less than or equal to the upper limit of the number of users that can be served by the base station.

[0023] S6: designing 5G base station to cover the whole area; taking the maximum number of users that can be served by a base station at the same time as a constraint, and selecting the intersection where the 5G base station is arranged and the covered intersection to maximize the average weight, so as to realize covering the whole area with the least number of base stations.

[0024] S1 specifically includes the following steps:

[0025] Using ArcGIS software, the whole area is divided into a plurality of grids with a certain length of distance as the grid side length, the number of roads in each grid and the road intersection condition are calculated, and the road network density is calculated;

[0026] The higher the road network density is, the more sufficient the road supply is, and the more the traffic flow and the passenger flow are, so that one base station can cover more intersections and provide services for more vehicles and pedestrians.

[0027] The road network density of the road between intersection i and intersection j is obtained by corresponding the coordinates of the center points of the intersections to each grid in the area

[0028] S2 specifically includes the following steps:

[0029] The distance between intersections is calculated according to the coordinates of the center points of the intersections, and then the distance influence degree is calculated according to the distance by the following steps to participate in the weight calculation:

[0030] The center points of the intersections are taken as the preliminary sites of the 5G base stations, a suitable place is selected as the 5G base station setting point, and the coordinates of the center points of the intersections are read to calculate the distance between the intersections by the coordinates;

[0031] The smaller the distance between two intersections, the greater the relevance, that is, the closer the intersection, the more intersections a base station can cover, and the stronger the signal received by vehicles in the road. Therefore, considering the distance factor to select the intersection and its covered intersection where the base station is set, the number of intersections covered by a base station can be as large as possible, so as to cover the entire area with the least number of base stations and improve data transmission efficiency.

[0032] Suppose the communication radius of a 5G base station is R, the square of the Euclidean distance between different intersections is calculated according to formula (1), and each intersection selects the nearby covered intersection according to the distance to generate the covered intersection array L of intersection i i [s], s is the array element label, i is the intersection identifier; if the distance between intersection i and intersection j satisfies the condition D(i,j)≥R 2 , then the two intersections are covered intersections of each other and are included in the covered intersection array L of each other i [s]; let η i,j be the distance between intersections i and j, then:

[0033] D(i,j)=(x i -x j ) 2 +(y i -y j ) 2 (7)

[0034]

[0035] where i and j represent intersection i and intersection j respectively, (x i ,y i ) and (x j ,y j ) are the coordinates of the center points of intersection i and intersection j, D(i,j) is the square of the Euclidean distance between intersection i and j, and η i,j is the distance between intersection i and j.

[0036] The difference between the communication radius of a 5G base station and the distance between intersections is R-η i,j ; if the distance between intersections does not exceed the communication radius R of the base station, the two intersections are covered intersections of each other, the smaller the difference, the greater the distance, and the weaker the signal; if the distance between intersections exceeds the communication radius R of the base station, it is considered as unable to cover; the above two cases are called distance influence degree, and the specific calculation method is as follows:

[0037]

[0038] where R is the communication radius of a 5G base station, and ξ i,j is the distance influence degree between intersections.

[0039] From formula (3), when the two intersections can cover each other, the distance influence degree ξ i,j is smaller, the relevance of the two intersections is smaller, and when the two intersections cannot cover each other, the distance influence degree ξ i,j is 0, that is, the two intersections cannot be associated.

[0040] S3 specifically includes the following steps:

[0041] For the judgment of the traffic volume: the larger the traffic volume, the more the number of vehicles, the greater the demand for the base station, so the base station is set in the place with large traffic volume, and is close to the intersection with large traffic volume as much as possible. Therefore, the traffic volume is one of the elements participating in the weight calculation to select the intersection and the covered intersection for setting the 5G base station;

[0042] The intersection is divided into four types, which are small intersection, medium intersection, large intersection and super large intersection;

[0043] Let the intersection type be T, and the road traffic volume be K. According to the different intersection types T and different road traffic volumes K, set the traffic volume level parameter M. Specifically as follows:

[0044] The T values of the four road types are respectively set to 0, 1, 2 and 3, that is, when T=0, it is a small intersection; when T=1, it is a medium intersection; when T=2, it is a large intersection; and when T=3, it is a super large intersection. The maximum traffic volume per unit time of the small intersection is not more than 1200 vehicles / hour; the maximum traffic volume per unit time of the medium intersection is between 1200 vehicles / hour and 2400 vehicles / hour; the maximum traffic volume per unit time of the large intersection is between 2400 vehicles / hour and 4000 vehicles / hour; and the maximum traffic volume per unit time of the super large intersection is more than 4000 vehicles / hour;

[0045] According to the maximum traffic volume per unit time, the traffic volume per unit time of different intersection types is divided into three levels:

[0046] When T=0, that is, in a small intersection, if the traffic volume per unit time K is less than 1200 vehicles / hour, the level parameter M=1, otherwise the level parameter is set to M=3;

[0047] When T=1, that is, in a medium intersection, if the traffic volume per unit time K is less than 1200 vehicles / hour, the level parameter M=1, if 1200≤K≤2400 vehicles / hour, the level parameter M=2, and if K>2400 vehicles / hour, the level parameter M=3;

[0048] When T=2, that is, in a large intersection, if the traffic volume per unit time K is less than 2400 vehicles / hour, the level parameter M=1, if 2400≤K≤4000 vehicles / hour, the level parameter M=2, and if K>4000 vehicles / hour, the level parameter M=3;

[0049] When T=3, i.e. in a super-large intersection, if the traffic volume K per unit time is less than 4000 vehicles / hour, the level parameter M=1, otherwise the level parameter is set to M=3;

[0050] S4 specifically comprises the following steps:

[0051] According to the design calculation formula of the three elements of steps S1, S2 and S3, fill the road communication demand weight into the weight coefficient matrix Q;

[0052] For the problem of realizing intersection full coverage of the set 5G base station, three factors in S1, S2 and S3 are used to participate in weight calculation: the road network density The more dense the road network, the more intersections, the more intersections a base station can cover, and the more vehicles it can serve; the distance influence degree ξ i,j between intersections, the greater the distance, the fewer intersections a base station can cover, and the worse the signal, which is easy to cause problems of base station resource waste and untimely response; the level parameter M judging the traffic volume, which sets the base station to the road with large traffic volume to respond to more vehicles in time;

[0053] Define the communication demand weight ρ between an intersection i and an intersection j, and the calculation method is the sum of the road network density and the traffic volume parameter level M multiplied by the distance influence degree between intersections, i.e.:

[0054]

[0055] To ensure accuracy, normalize the weight ρ (linearly scale the data to [0, 1]), that is, take the maximum value of M and ξ i,j in formula (4) as the denominator, so that the maximum weight ρ' is in the interval [0, 1]:

[0056]

[0057] Where R is the 5G base station communication radius, is the road network density, ξ i,j is the distance influence degree, and M is the traffic volume level parameter.

[0058] S5 specifically comprises the following steps:

[0059] To prevent the base station from being overloaded, the maximum number of users that the base station can serve at the same time is used as a constraint condition to select the intersections covered by each base station to ensure the service quality of the base station;

[0060] Since the number of users that a 5G base station can serve is not infinite, a standard 5G base station can provide 20-30 thousand users to surf the Internet at the same time, but there may be more than one user in a vehicle;​

[0061] In order to guarantee the quality of service of the 5G base station, the upper limit of the number of users that the 5G base station can simultaneously serve is set to several, which is set as a constraint condition;

[0062] According to the traffic flow of the road, it is judged whether the number of users in the road exceeds the service capability of the base station. If it exceeds, it will no longer cover other intersections. If it does not exceed, it will select the intersection with a traffic flow less than the number of users that the base station can still serve to cover.

[0063] S6 specifically includes the following steps:

[0064] In order to save costs, it is required to minimize the number of 5G base stations, but the set base station can cover all intersections; in order to prevent multiple base stations from responding to the task of the same vehicle and occupying the channel, it is ensured that only one base station provides service for one intersection.

[0065] Suppose there are B intersections in the area, each intersection is identified from 1 to B, and the intersection set is N={1, 2, …, B};

[0066] The position coordinates of the center point of intersection i are (x i ,y i ), i=1, 2, …, B;

[0067] The center point of each intersection is taken as a preliminary site of the 5G base station. In these intersections, the 5G base station is set according to the following specific steps to select a suitable place to achieve the goal of minimizing the number of base stations to achieve full coverage of the area;

[0068] Define the intersection set C that determines the setting of the 5G base station, C={Z1, Z2, …, Z f}, Z is the intersection where the base station is set, and f is the total number of intersections where the base station is set;

[0069] In order to determine whether the intersection is a determined base station setting intersection, three types of intersections need to be defined, namely, intersections where it is not decided whether to place a base station, intersections where a base station is placed, and intersections where a base station is not placed; the three types of intersection identification are U, A, and P, respectively. The site flag vector e i is constructed:

[0070]

[0071] The set of intersections covered by the intersection where the base station is placed is called the covered intersection set W i ; let i be the intersection identifier, and O max be the upper limit of the number of users that the 5G base station can simultaneously serve;

[0072] The following steps are performed:

[0073] S601: Obtain the coordinates of the center of each intersection, read the road network density data file, match the coordinates given in the road network density file with the coordinates of the center of the intersection, and obtain the road network density of each road

[0074] S602: Calculate the distance between intersections by coordinates, and then calculate the distance influence degree ξ according to formula (3) i,j ;

[0075] S603: Read the traffic volume level parameter M of each road;

[0076] S604: Create a Bx B weight coefficient matrix Q, and fill the weight of each road into the weight coefficient matrix Q according to formula (4) p';

[0077] S605: Input the weight coefficient matrix Q and the upper limit of the number of 5G base station users O max ;

[0078] S606: Initialize the category of all intersections to U;

[0079] S607: Traverse the intersection category of all intersections;

[0080] S608: Calculate the number of intersections H of category U that can be covered if a base station is placed at each intersection, for example, H i The number of intersections of category U that can be covered after setting a base station at intersection i, that is, the coverable intersection set L of intersection i i The number of intersections of category U in [s];

[0081] S609: If there is H i = 0, set a 5G base station at intersection i, and set the intersection category to A;

[0082] S610: If there is H i = 1, set a 5G base station at the only coverable intersection of intersection i, and set the intersection category to A;

[0083] S611: If there is no intersection with H value of 0 or 1 in the region, in order to realize that one base station covers as many intersections as possible, set a 5G base station at the intersection with the largest H value, and set the intersection category to A;

[0084] S612: Recalculate the H value of each intersection;

[0085] S613: If the coverable road traffic volume sum of the intersection i where the 5G base station has been set is greater than O max , arrange the coverable intersections of it in order of H value from small to large to produce a list H sort ;

[0086] S614: If H sort , remove the intersection with the largest H value from the list H ;j = H j +1,j and j+1 intersections can be the last covered intersection of i, compare the order of j and j+1 intersections and the weight of the set point in all connected road weights, select the intersection with high order to cover, the covered intersection category is set to P, and the covered intersection set W of intersection i is added i ;

[0087] S615: if H sort ≠ H j ≠ H j +1,j can be the last covered intersection of i, and the covered intersection set of i is added in order according to the order of H sort , the intersection category is set to P, and the covered intersection set W of intersection i is added i ;

[0088] S616: return to step S607 until all intersection categories are not U;

[0089] S617: add the intersection in state A to set C;

[0090] S618: output the intersection set C of the 5G base station and their covered intersection set W i .

[0091] Compared with the prior art, the present application has the following beneficial effects:

[0092] 1、The present application sets a weight coefficient matrix, which reflects the demand degree of roads for base stations through road network density, distance influence degree and traffic flow level parameters, and is called weight. According to the weight size, the intersection or road that needs the base station more is closer to the base station, and the service efficiency of the base station is improved.

[0093] 2、The present application sets the maximum number of users that can be served by the base station as a constraint condition, which can guarantee the service quality of the base station. The computing capacity of the base station is limited, if many roads and intersections are only served by one base station, and the number of users in this area has far exceeded the load capacity of the base station, by setting this constraint condition, the base station can provide networking services for more roads and intersections within the capacity range.

[0094] 3、The method can realize the least number of base stations to cover the whole area. Under the constraint of the maximum number of users that a base station can serve at the same time, the method uses the idea of trying to serve more intersections with one base station to design the method, so as to realize the least number of base stations set, and the intersections that cannot be covered by other base stations are set with base stations to realize the coverage of the whole area. Therefore, the method can realize the least number of base stations, so as to realize the minimum cost; and can realize the coverage of the whole area, so that all intersections and roads have base stations to serve them, and the load capacity of the base station will not be exceeded.

[0095] The application can quickly assist all vehicles to access the network under the condition of considering the service capacity of the base station and minimizing the number of base stations, so as to improve the data access speed and response time, reduce the network delay, and improve the performance and throughput of the system. BRIEF DESCRIPTION OF DRAWINGS

[0096] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, which together with the embodiments of the application are used to explain the application, and do not constitute a limitation on the application.

[0097] Figure 1 It is a whole flowchart of the method of the application.

[0098] Figure 2 It is a flowchart for judging the traffic flow in the weight coefficient matrix of the application.

[0099] Figure 3 It is an example diagram of the road network density involved in the weight coefficient matrix of the application. DETAILED DESCRIPTION

[0100] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below in combination with the drawings and embodiments. Of course, the specific embodiments described here are only used to explain the application, and do not limit the application.

[0101] Embodiment 1

[0102] Referring to Figure 1 A vehicle networking 5G base station site selection method for urban roads, the method comprising the following steps:

[0103] S1: calculating the road network density of each road; the road network density of each road is calculated by ArcGIS software, and the road network density is taken as one of the factors to participate in the weight calculation;

[0104] In addition to providing map and data services for clients, the GIS server also supports all functions of GIS workstations on a shared central server, including mapping, spatial analysis, complex spatial query, advanced data editing, distributed data management, batch spatial processing, implementation of spatial geometric integrity rules, etc. The present application uses ArcGIS software to complete the calculation of road network density.

[0105] The road network density reflects the traffic congestion condition. If the roads in a region are dense, one base station can cover multiple roads. If the roads in a region are sparse, i.e. for a certain intersection, other intersections cannot serve it even if a base station is set up, then this intersection also needs to set up a base station to provide services for the roads nearby. Therefore, the road network density is taken as one of the elements to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0106] S2: Calculate the distance influence degree between intersections; determine whether two intersections cover each other according to the distance between them. If they cannot cover each other, the distance influence degree is 0. If they can cover each other, the distance influence degree is the difference between the 5G base station communication radius and the distance. The distance influence degree between intersections is taken as one of the elements to participate in the weight calculation.

[0107] The distance between intersections reflects the coverage of the base station, i.e. if a 5G base station is set up at an intersection, it can be determined whether it can cover another intersection through the distance, so as to know whether the road between the two intersections can be covered by the base station of the intersection. Therefore, the present application only considers the coverage of the base station to the intersection. In addition, in order to determine whether to set up a base station at the intersection, the signal strength of the base station and the road vehicles also needs to be considered. The smaller the distance, the stronger the signal. The distance influence degree is calculated according to the distance between two intersections to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0108] S3: Calculate the traffic flow level parameter of each road; divide the intersections into four types, define a level parameter to judge the traffic flow according to the traffic flow per unit time of each intersection, and take it as one of the elements to participate in the weight calculation.

[0109] The road traffic flow reflects the traffic flow per unit time of the road. The base station should be placed at the intersection with large traffic flow as much as possible to provide networking services for more vehicles. Therefore, the traffic flow is taken as one of the elements to participate in the weight calculation to select the intersection where the 5G base station is set up and the covered intersections.

[0110] S4: Define the communication demand metric and create the weight coefficient matrix; use the road network density, the distance influence degree between intersections and the level parameter to judge the road traffic flow, calculate the communication demand metric of each road through the formula and fill it into the weight coefficient matrix.

[0111] The communication demand metric is defined, a weight coefficient matrix reflecting the road network density, the distance between intersections and the influence degree and the road daily traffic volume is designed, and the demand degree of each road for the base station is embodied;

[0112] According to the communication demand metric, the 5G base station site selection is performed, and the covered intersections are selected for the intersections where the base stations are arranged, so that the number of base stations is minimized and the base stations can cover the whole area, so that the application proposes to select the base station arrangement site and the covered intersection in the urban market to minimize the number of base stations and maximize the average weight, so as to guarantee the high efficiency and high reliability of data transmission.

[0113] S5: Setting a constraint condition; taking the upper limit of the number of users that can be served by one base station as a constraint condition, and selecting the covered intersection of each base station;

[0114] Since the number of users that can be served by a base station is limited, the maximum number of users that can be provided with online service by one base station at the same time is taken as a constraint, that is, the total number of users in the area covered by the base station is less than or equal to the upper limit of the number of users that can be served by the base station.

[0115] S6: Designing a 5G base station to cover the whole area; taking the maximum number of users that can be served by a base station at the same time as a constraint, and selecting the intersection where the 5G base station is arranged and the covered intersection to maximize the average weight, so as to cover the whole area with the least number of base stations.

[0116] S1 specifically includes the following steps:

[0117] Using ArcGIS software, the whole area is divided into a plurality of grids with a grid side length of 1KM, the number of roads in each grid and the road intersection condition are calculated, and the road network density is calculated;

[0118] The higher the road network density is, the more sufficient the road supply is, and the more the traffic volume and the passenger flow are, so that one base station can cover more intersections and provide services for more vehicles and pedestrians. Taking the city C as an example, in order to facilitate observation and calculation, each grid is labeled in order, and the road network density data and Figure 3 The road network density visualization image is shown in FIG. 1; Figure 3 As shown in FIG. 1, the road network density in the middle area is larger, and the road network density in the grid with the label 774-775 is between 20.01-29.72;

[0119] The road network density between the intersection i and the intersection j is obtained by matching the coordinates of the center points of the intersections with each grid in the area

[0120] S2 specifically includes the following steps:

[0121] According to the intersection center point coordinates, the distance between intersections is calculated, and then the distance influence degree is calculated according to the distance according to the following steps, and the participation weight value is calculated:

[0122] The center point of each intersection is taken as a 5G base station preparation site, a suitable site is selected as a 5G base station setting point in it, the coordinates of each intersection center point are read, and the distance between each intersection is calculated through the coordinates;

[0123] The smaller the distance between two intersections, the greater the relevance, that is, the closer the intersection, the more intersections that can be covered by a base station, and the stronger the signal received by the vehicle in the road. Therefore, considering the distance factor to select the intersection and its covered intersection for setting the base station can make the number of intersections covered by a base station as much as possible, so as to realize the least number of base stations covering the entire area and improve the data transmission efficiency.

[0124] Suppose the communication radius of the 5G base station is R, the square of the Euclidean distance between different intersections is calculated according to formula (1), and each intersection selects the nearby covered intersection according to the distance to generate the covered intersection array L of intersection i i [s], s is the array element label, i is the intersection identifier; if the distance between intersection i and intersection j satisfies the condition D(i,j)≥R 2 , then the two intersections are covered intersections of each other and are included in the opposite covered intersection array L i [s]; let η i,j be the distance between intersection i and j, then:

[0125] D(i,j)=(x i -x j ) 2 +(y i -y j ) 2 (13)

[0126]

[0127] Where i and j represent intersection i and intersection j respectively, (x i ,y i ) and (x j ,y j ) are the coordinates of the center points of intersection i and intersection j, D(i,j) is the square of the Euclidean distance between intersection i and j, η i,j is the distance between intersection i and j;

[0128] The difference between the communication radius of the 5G base station and the distance between intersections is R-η i,jIf the distance between intersections does not exceed the base station communication radius R, the two intersections are covered intersections, the smaller the difference, the greater the distance, the weaker the signal; if the distance between intersections exceeds the base station communication radius R, it is considered as unable to cover; the above two cases are called distance influence degree, and the specific calculation method is as follows:

[0129]

[0130] Where R is the 5G base station communication radius, and ξ i,j is the distance influence degree between intersections.

[0131] According to formula (3), when the two intersections can cover each other, the distance influence degree ξ i,j is smaller, the smaller the relevance of the two intersections, and when the two intersections cannot cover each other, the distance influence degree ξ i,j is 0, that is, the two intersections cannot be associated.

[0132] S3 specifically includes the following steps:

[0133] For the judgment of traffic flow size: the larger the traffic flow, the more the number of vehicles, the greater the demand for base stations, so the base station should be set in the place with large traffic flow, and as close as possible to the intersection with large traffic flow. Therefore, the traffic flow is one of the elements participating in the weight calculation to select the intersection where the 5G base station is set and its covered intersection;

[0134] The intersections are divided into four types, namely small intersection, medium intersection, large intersection and super large intersection.

[0135] The traffic flow level parameter M is calculated according to Figure 2 , and the intersection type is T, and the road traffic flow is K. According to the different intersection types T and different road traffic flow K, the traffic flow level parameter M is set. The specific is as follows:

[0136] The T values of the four road types are respectively set as 0, 1, 2 and 3, that is, when T=0, it is a small intersection; when T=1, it is a medium intersection; when T=2, it is a large intersection; when T=3, it is a super large intersection; the maximum traffic flow per unit time of small intersection is not more than 1200 vehicles / hour; the maximum traffic flow per unit time of medium intersection is between 1200 vehicles / hour and 2400 vehicles / hour; the maximum traffic flow per unit time of large intersection is between 2400 vehicles / hour and 4000 vehicles / hour; the maximum traffic flow per unit time of super large intersection is more than 4000 vehicles / hour.

[0137] According to the maximum traffic flow per unit time, the traffic flow per unit time of different intersection types is divided into three levels:

[0138] When T=0, that is, in a small intersection, if the traffic flow K per unit time is less than 1200 vehicles / hour, then the level parameter M=1; otherwise, the level parameter is set to M=3.

[0139] When T=1, that is, in a medium-sized intersection, if the traffic flow K per unit time is less than 1200 vehicles / hour, then the level parameter M=1; if 1200≤K≤2400 vehicles / hour, then the level parameter M=2; if K>2400 vehicles / hour, then the level parameter M=3.

[0140] When T=2, that is, in a large intersection, if the traffic flow K per unit time is less than 2400 vehicles / hour, then the level parameter M=1; if 2400≤K≤4000 vehicles / hour, then the level parameter M=2; if K>4000 vehicles / hour, then the level parameter M=3.

[0141] When T=3, that is, in a super large intersection, if the traffic flow K per unit time is less than 4000 vehicles / hour, then the level parameter M=1; otherwise, the level parameter is set to M=3.

[0142] S4 specifically includes the following steps:

[0143] Based on the calculation formulas designed according to the three elements in steps S1, S2, and S3, the communication demand weights of each road are filled into the weight coefficient matrix Q.

[0144] To address the issue of achieving full intersection coverage with the installed 5G base stations, three factors from S1, S2, and S3 are used in the weighting calculation: road network density. The denser the road network and the more intersections there are, the more intersections a single base station can cover, and therefore the more vehicles it can serve; the distance between intersections affects the efficiency ξ. i,j The greater the distance, the fewer intersections the base station can cover, and the weaker the signal, which can easily lead to waste of base station resources and untimely response. The level parameter M for judging the traffic volume allows the base station to be set up on roads with high traffic volume to respond to more vehicles in a timely manner.

[0145] Define a communication demand weight ρ between intersection i and intersection j, calculated using the road network density. The product of the sum of traffic flow parameter level M and the influence of the distance between intersections, i.e.:

[0146]

[0147] To ensure accuracy, the weights ρ are normalized (the data is linearly scaled to between [0,1]), i.e., the values ​​in formula (4) are taken as follows. M and ξ i,j The maximum value is used as the denominator, so that the final weight ρ′ is in the interval [0,1]:

[0148]

[0149] wherein R is a 5G base station communication radius, is a road network density, ξ i,j is a distance influence degree, and M is a traffic flow level parameter.

[0150] S5 specifically includes the following steps:

[0151] To prevent overloading of the base station, the maximum number of users that can be served by the base station at the same time is used as a constraint condition, and the intersections covered by each base station are selected to ensure the quality of service of the base station;

[0152] Since the number of users that can be served by a 5G base station is not infinite, a standard 5G base station can serve 20-30 thousand users at the same time, but there can be more than one user in a vehicle,

[0153] To ensure the quality of service of the 5G base station, the upper limit of the number of users that can be served by the 5G base station at the same time is set to 20,000, which is used as a constraint condition;

[0154] According to the road traffic flow, it is determined whether the number of users in the road exceeds the service capacity of the base station. If it exceeds, the base station does not cover other intersections, and if it does not exceed, the intersection with a traffic flow less than the number of users that can still be served by the base station is selected for coverage.

[0155] S6 specifically includes the following steps:

[0156] In order to save costs, the number of 5G base stations is required to be minimized, but the set base stations can cover all intersections; in order to prevent multiple base stations from responding to the task of the same vehicle and occupying the channel, it is ensured that only one base station provides service for an intersection.

[0157] Suppose there are B intersections in the region, each intersection is labeled from 1 to B, and the intersection set is N={1, 2,..., B};

[0158] The position coordinates of the center point of intersection i are (x i ,y i ), i=1, 2,..., B;

[0159] The center point of each intersection is used as a preliminary site of the 5G base station, and the 5G base station is set at a suitable location in these intersections according to the following specific steps to achieve the goal of minimizing the number of base stations to achieve full coverage of the region;

[0160] Define the intersection set C for setting the 5G base station, C={Z1, Z2,..., Z f}, Z is the intersection where the base station is set, and f is the total number of intersections where the base station is set;

[0161] In order to determine whether the intersection is a base station intersection, three intersection categories need to be defined, i.e. whether to place a base station intersection, place a base station intersection and do not place a base station intersection, and three category identifiers are U, A and P respectively, and a site flag bit vector e is constructed i :

[0162]

[0163] The intersection where the base station is placed is finally covered by the intersection set W i ; Let i be the intersection identifier, O max is the upper limit of the number of users that can be simultaneously served by the 5G base station

[0164] In the method, in order to output the final base station intersection and its covered intersection

[0165] Firstly, all intersection categories need to be set to U, i.e. whether to place a base station intersection or not

[0166] Secondly, whether to place a base station is determined according to the following steps, if a base station is placed, the category is converted to a base station intersection, i.e. the intersection category is converted to A, and is added to the set C

[0167] Finally, the base station intersection A selects the covered intersection, and the covered intersection category is converted to P, i.e. if the intersection i places a base station, the intersection j is selected as the covered intersection of the intersection i, then the intersection j category is P, and is added to the covered intersection set W i of the intersection i

[0168] Method steps

[0169] S601: Obtain the coordinates of the center points of each intersection, read the road network density data file, match the coordinates given in the road network density file with the coordinates of the center points of the intersections, and obtain the road network density of each road

[0170] S602: Calculate the distance between intersections through coordinates, and then calculate the distance influence degree ξ according to formula (3) i,j ;

[0171] S603: Read the traffic volume level parameter M of each road

[0172] S604: Create a Bx B weight coefficient matrix Q, fill the weight values of each road into the weight coefficient matrix Q according to formula (4) p'

[0173] S605: Input the weight coefficient matrix Q and the upper limit of the number of users of the 5G base station O max ;

[0174] S606: Initialize the category of all intersections to U

[0175] S607: Traverse the intersection categories of all intersections;

[0176] S608: Calculate the number of intersections H of category U that can be covered if a base station is placed at each intersection, i.e., H i Set the number of intersections of category U that can be covered after placing a base station at intersection i, i.e., the coverable intersection set L of intersection i i The number of intersections of category U in [s];

[0177] S609: If there exists H i = 0, set the 5G base station at intersection i and set the intersection category to A;

[0178] S610: If there exists H i = 1, set the 5G base station at the only coverable intersection of intersection i and set the intersection category to A;

[0179] S611: If there is no intersection with H value of 0 or 1 in the region, to achieve a base station covering as many intersections as possible, set the 5G base station at the intersection with the largest H value and set the intersection category to A;

[0180] S612: Recalculate the H value of each intersection;

[0181] S613: If the total traffic volume of the coverable road of the intersection i where the 5G base station has been set is greater than O max , arrange the coverable intersections of the intersection i in ascending order of H value to generate a list H sort ;

[0182] S614: If H sort in H j = H j + 1, both intersections j and j+1 can be the last coverable intersection of intersection i, compare the sorting of the weight values of intersections j and j+1 and the set point in the weight values of all connected roads, select the intersection with higher sorting to cover, set the category of the covered intersection to P, and add the covered intersection to the covered intersection set W of intersection i i ;

[0183] S615: If H sort in H j ≠ H j + 1, j can be the last coverable intersection of intersection i, add it to the covered intersection set of intersection i in ascending order of H sort , set the intersection category to P, and add it to the covered intersection set W of intersection i i ;

[0184] S616: Return to step S607 until all intersection categories are not U;

[0185] S617: Add the intersection with state A to set C;

[0186] S618: Outputs the set of intersections C for setting up 5G base stations, and the set of intersections W that are covered by them. i .

[0187] Example 2

[0188] Based on Example 1

[0189] In S601~S604, first obtain the road network density, intersection distance and traffic flow level parameters, calculate the weight of each road according to formula (5), and fill it into the weight coefficient matrix Q of B×B;

[0190] In S605, input the weight coefficient matrix Q calculated in S604 and the upper limit O of the number of 5G base station users. max ;

[0191] In S606 to S608, all intersection categories are initialized to U, meaning all intersection categories are set to "undecided whether to place a base station"; then, all intersection categories are traversed, and the coverage array L of each intersection in S2 is used as the reference. i [s], calculate L i [s] The number of intersections classified as U, denoted as H. i 'i' represents the intersection sign;

[0192] In S609, if there exists an intersection i, its H value is 0, that is, H i =0 means that if a base station is set up at this intersection, no other intersection can be covered by it. Similarly, if a base station is set up at any other intersection, it cannot cover intersection i. Therefore, only if a base station is set up at intersection i can it provide services to the surrounding roads.

[0193] In S610, if there exists an intersection i, its H value is 1, that is, H i =1 indicates that if a base station is set up at this intersection, there will be exactly one intersection that can be covered by it, except for itself. Let's call it intersection j. We choose to set up the base station at intersection j because if we set up the base station at intersection i, it can only cover intersection j, while setting up the base station at intersection j can cover more intersections.

[0194] In S611, if the H value of an area has no intersections and is 0 or 1, then a base station is set up at the intersection with the largest H value, because the largest H value means that if a base station is set up at this intersection, it can cover the most intersections.

[0195] In S612, the H value of each intersection is recalculated because some intersections have become intersections with a fixed base station, and the intersection category is A instead of U. The H value is the number of intersections with the intersection category U that each intersection can cover.

[0196] In S613, based on the calculations in S612, it is known that the intersection where the base station is located can cover H intersections of type U. Since more connected intersections are more likely to be selected as coverage intersections by other intersections, priority is given to covering intersections with smaller H values. These intersections are then arranged in ascending order of H values ​​to generate a list H. sort ;

[0197] In S614, if the total traffic flow of the H intersections covered by the base station at intersection i is greater than 0... max This indicates that providing full coverage to all these intersections would exceed the service capacity of the base stations; therefore, only a portion of the intersections are covered, with the remaining intersections served by other base stations. If H sort In the diagram, the H values ​​of the j-th intersection and the (j+1)-th intersection are the same, and the sum of their traffic flows and the traffic flows of the preceding j-1 intersections is less than 0. max If both can be considered as the last intersection covered by intersection i, then we compare the importance of intersection i to these two intersections, that is, we assign H to each intersection. sort The roads that can be covered by the j-th intersection and the (j+1)-th intersection are sorted in descending order of weight, and the intersection with the higher ranking among them is selected for coverage.

[0198] In S615, if the total traffic flow of the H covered intersections is less than or equal to 0... max All H intersections are covered;

[0199] In S617-S618, return to S607 and repeat S607-S618 until the category of all intersections is no longer U; output the set of base station set C and its covered intersection set W. i .

[0200] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for site selection of 5G base stations for vehicle-to-everything (V2X) communication on urban roads, characterized in that, The method includes the following steps: S1: Calculate the road network density of each road; calculate the road network density of each road using ArcGIS software, and use the road network density as one of the elements in the weight calculation; S2: Calculate the distance influence between intersections; determine whether the two intersections cover each other based on the distance between them. If they do not cover each other, the distance influence is 0; if they do cover each other, the distance influence is the difference between the 5G base station communication radius and the distance; the distance influence between intersections is used as one of the factors in the weight calculation. S3: Calculate the traffic flow level parameters for each road; divide the intersections into four types, define a level parameter for judging the traffic flow level based on the traffic flow per unit time for each intersection, and use it as one of the elements in the weight calculation; S4: Define communication demand metrics and create a weighting coefficient matrix; using three factors—road network density, the influence of distance between intersections, and the level parameter for judging road traffic volume—calculate the communication demand metrics for each road using formulas and fill them into the weighting coefficient matrix; S5: Set constraints; The maximum number of users that a single base station can serve simultaneously is used as a constraint to select the intersections covered by each base station. S6: Design 5G base stations to cover the entire area; with the maximum number of users served by the base station at the same time as a constraint and the goal of maximizing the average weight, select the intersections where 5G base stations are set up and the intersections they cover, so as to achieve coverage of the entire area with the minimum number of base stations.

2. The method for site selection of 5G base stations for vehicle-to-everything (V2X) networks on urban roads according to claim 1, characterized in that, S1 specifically includes the following steps: Using ArcGIS software, the entire area is divided into squares with a certain distance as the grid side length. The number of roads in each grid and the road intersection situation are calculated to calculate the road network density. By mapping the coordinates of the center points of each intersection to each grid cell in the region, the road network density of the road between intersection i and intersection j can be obtained.

3. The method for site selection of 5G base stations for vehicle-to-everything (V2X) networks on urban roads according to claim 2, characterized in that, S2 specifically includes the following steps: Calculate the distance between intersections based on the coordinates of the intersection center point, and then calculate the distance influence degree based on the distance according to the following steps, which will be included in the weighting calculation: The center point of each intersection is used as a reserve site for 5G base stations. A suitable location is selected as the 5G base station setting point. The coordinates of the center point of each intersection are read, and the distance between each intersection is calculated using the coordinates. Let the communication radius of the 5G base station be R. Calculate the square of the Euclidean distance between different intersections according to equation (1). Select nearby intersections that can be covered by the 5G base station based on the distance, and generate an array L of intersections that can be covered by intersection i. i [s], where s is the array element index and i is the intersection identifier; if the distance between intersection i and intersection j satisfies the condition D(i,j)≥R 2 If these two intersections are mutually covered intersections, they are added to the array L of intersections that the other can cover. i In [s]; let η i,j Let i be the distance between intersections i and j, then: D(i,j)=(x i -x j ) 2 +(y i -y j ) 2 (1) Where i and j represent intersection i and intersection j respectively, (x i ,y i ) and (x j ,y j Let η be the coordinates of the center points of intersections i and j, respectively, and D(i,j) be the square of the Euclidean distance between intersections i and j. i,j Let i be the distance between intersections i and j. Let R be the communication radius of the 5G base station. Then the difference between the communication radius of the 5G base station and the distance between the intersections is R-η. i,j If the distance between intersections does not exceed the base station's communication radius R, then the two intersections are mutually covered intersections. The smaller the difference, the greater the distance and the weaker the signal. If the distance between intersections exceeds the base station's communication radius R, it is considered that there is no coverage. The above two situations are collectively referred to as the distance impact degree, and the specific calculation method is as follows: Where R is the communication radius of the 5G base station, ξ i,j The influence of distance between intersections; From formula (3), when the two intersections can cover each other, the distance influence ξ i,j The smaller the value ξ, the weaker the correlation between the two intersections. When the two intersections cannot be covered, the distance has a greater impact. i,j A value of 0 indicates that the two intersections cannot be connected.

4. The method for site selection of 5G base stations for vehicle-to-everything (V2X) networks on urban roads according to claim 3, characterized in that, S3 specifically includes the following steps: Regarding the assessment of traffic volume: the greater the traffic volume and the more vehicles there are, the greater the demand for base stations. Intersections are classified into four types: small intersections, medium intersections, large intersections, and extra-large intersections. Let the intersection type be T and the road traffic volume be K. Based on the different intersection types T and different road traffic volumes K, set the traffic volume level parameter M.

5. The method for selecting a 5G base station site for vehicle-to-everything (V2X) communication on urban roads according to claim 4, characterized in that, S4 specifically includes the following steps: Based on the calculation formulas designed for the three elements in steps S1, S2, and S3, the communication demand weights for each road are filled into the weight coefficient matrix Q. To address the issue of achieving full intersection coverage with the installed 5G base stations, three factors from S1, S2, and S3 are used in the weighting calculation: road network density. The influence of distance between intersections ξ i,j The level parameter M for determining the traffic volume; Define a communication demand weight ρ between intersection i and intersection j, calculated using the road network density. The product of the sum of traffic flow parameter level M and the influence of the distance between intersections, i.e.: The weight ρ is normalized, that is, the value in formula (4) is taken as follows. M and ξ i,j The maximum value is used as the denominator, so that the final weight ρ′ is in the interval [0,1]: Where R is the communication radius of the 5G base station. For road network density, ξ i,j M represents the distance influence level, and M represents the traffic flow level parameter.

6. The method for site selection of 5G base stations for vehicle-to-everything (V2X) networks on urban roads according to claim 5, characterized in that, S5 specifically includes the following steps: To ensure the service quality of 5G base stations, a maximum number of users that a 5G base station can serve simultaneously is set as a constraint condition. The system determines whether the number of users on a road exceeds the service capacity of the base station based on the traffic flow. If it does, other intersections will no longer be covered. If it does not exceed the capacity, the system will select an intersection with traffic flow less than the number of users that the base station can still serve.

7. A method for selecting a 5G base station site for vehicle-to-everything (V2X) communication on urban roads according to claim 6, characterized in that, S6 specifically includes the following steps: Suppose there are B intersections in the area. Each intersection is labeled from 1 to B, and the set of intersections is N = {1, 2, ..., B}. The coordinates of the center point of intersection i are (x i ,y i ), i = 1, 2, ..., B; The center point of each intersection will be used as a reserve site for 5G base stations. 5G base stations will be set up at suitable locations in these intersections according to the following specific steps in order to achieve the goal of full coverage of the area with minimal number of base stations. Define the set of intersections C for setting up 5G base stations, C = {Z1, Z2, ..., Z...} f }, Z represents the intersection where the base station is set up, and f represents the total number of intersections where the base station is set up; To determine whether an intersection is a confirmed location for a base station, three intersection categories need to be defined: intersections where a base station placement is uncertain, intersections with a base station, and intersections without a base station. These categories are identified by the symbols U, A, and P, respectively, and a site marker bit vector e is constructed. i : The set of intersections ultimately covered by the intersection where the base station is placed is called the covered intersection set W. i Let i be the intersection sign, and O be the intersection sign. max This is the maximum number of users that a 5G base station can serve simultaneously. Perform the following steps: S601: Obtain the coordinates of the center points of each intersection, read the road network density data file, match the coordinates given in the road network density file with the coordinates of the intersection center points, and obtain the road network density of each road. S602: The distance between intersections is calculated using coordinates, and then the distance influence ξ is calculated according to formula (3). i,j ; S603: Read the traffic flow level parameter M for each road; S604: Create a weight coefficient matrix Q of B×B, and fill the weight of each road into Q according to formula (4)ρ′; S605: Input weight coefficient matrix Q, upper limit of 5G base station user count O max ; S606: Initialize the category of all intersections to U; S607: Iterate through the intersection categories of all intersections; S608: Calculate the number H of intersections of type U that can be covered after placing base stations at each intersection. i The number of intersections of type U that can be covered after setting up a base station for intersection i, i.e., the array L of intersections that intersection i can cover. i The number of intersections of category U in [s]; S609: If H exists i =0, set up a 5G base station at intersection i, and set the intersection category to A; S610: If H exists i =1, then a 5G base station is set up at the only intersection that can be covered at intersection i, and the intersection category is set to A; S611: If there are no intersections with an H value of 0 or 1 in the area, in order to achieve coverage of as many intersections as possible by one base station, a 5G base station shall be set up at the intersection with the highest H value and the intersection category shall be set to A. S612: Recalculate the H value for each intersection; S613: If a 5G base station has been set up at intersection i, the total traffic flow of the covered roads is greater than 0. max Sort the intersections that can be covered by the dictionary into ascending order of their H values, generating a list H. sort ; S614: If H sort H j =H j Intersections +1, j, and j+1 can all be the last intersection covered by intersection i. Compare the weights of intersections j and j+1 with the weights of the set point among the weights of all its connected roads, and select the intersection with the higher weight for coverage. The category of the covered intersection is set to P, and it is added to the set W of covered intersections of intersection i. i ; S615: If H sort H j ≠H j +1, j can be the last intersection covered by i, press H. sort Sort and add each intersection to the set of covered intersections i in turn, setting the intersection category to P, and then add it to the set of covered intersections W of intersection i. i ; S616: Return to step S607 until all intersection categories are not U; S617: Add the intersection with state A to set C; S618: Outputs the set of intersections C for setting up 5G base stations, and the set of intersections W that are covered by them. i .

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