Road side unit deployment method and device based on intersection node hierarchical activation mechanism

Abstract

The invention discloses a road side unit deployment method and device based on an intersection node hierarchical activation mechanism. The method comprises the following steps: quantifying a flow fluctuation value of each road by adopting a flow time sequence analysis technology; screening out a sub-region with remarkable flow fluctuation as a preferential deployment region; establishing a weighted graph model, storing intersection position information as node attributes, storing road types and road flow fluctuations as edge attributes, and marking intersections of candidate deployment road side units as to-be-activated nodes; calculating an edge weight and a node weight, setting a to-be-activated threshold value based on a statistical result of the node weight, and obtaining a first-layer to-be-activated node set according to the node weight and the to-be-activated threshold value; iteratively activating the remaining unactivated nodes to obtain a second layer of to-be-activated node set; and outputting all the to-be-activated nodes as activated nodes to obtain a final road side unit deployment scheme. According to the invention, the optimal balance between the deployment number of the road side units and the monitoring coverage is realized, and the deployment cost is obviously reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-road cooperation, and more specifically, to a method and device for deploying roadside units based on a hierarchical activation mechanism of intersection nodes. Background Art

[0002] With the rapid development of urbanization and the national economy, the number of automobiles in use is continuously increasing, and the problem of road traffic congestion is becoming increasingly serious. As an infrastructure unit for collecting and analyzing traffic data in a vehicle ad-hoc network, a roadside unit (RSU) is a key device for realizing intelligent roads and vehicle-road cooperation. In the planning of urban roads, due to the high cost of roadside units, they cannot be deployed at every road intersection. Therefore, under the consideration of both deployment costs and coverage requirements for traffic flow, the deployment strategy is particularly important.

[0003] In traditional deployment strategies, roadside units are often evenly arranged along roads at a certain fixed distance. Such a deployment lacks accurate analysis of actual traffic flow and demand, and may result in insufficient coverage or over-coverage in sections with uneven vehicle density, leading to too few or too many deployed roadside units and a low cost-benefit ratio. Summary of the Invention

[0004] The present invention aims to provide a method and device for deploying roadside units based on a hierarchical activation mechanism of intersection nodes to address the deficiencies of existing methods, improve the coverage range and traffic flow monitoring ability of roadside units, minimize the number of deployments, and reduce costs.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions: A method for deploying roadside units based on a hierarchical activation mechanism of intersection nodes, characterized by comprising: S1, taking the urban road network structure and in-vehicle GPS travel trajectories as data bases, and using traffic time series analysis technology to quantify the traffic flow fluctuation values of each road; S2, according to the traffic flow fluctuation values of each road, screening out sub-regions with significant traffic flow fluctuations as priority deployment regions, and preprocessing the road network data within the priority deployment regions; S3, establishing a weighted graph model for the preprocessed priority deployment regions, storing intersection location information as node attributes, and storing road types and road traffic flow fluctuations as edge attributes, and identifying intersections where roadside units are to be candidate-deployed as nodes to be activated; S4. Calculate the edge weights and node weights of the weighted graph model respectively using multi-attribute weighting and node degree. Subsequently, set an adaptive activation threshold to be determined based on the statistical results of all node weights within the priority deployment area. Obtain the first-layer set of nodes to be activated through the partial order relationship between the node weights and the activation threshold to be determined; S5. Iteratively activate the remaining unactivated nodes. Check whether the condition of being directly connected to the nodes to be activated is satisfied through the neighborhood influence function, and obtain the second-layer set of nodes to be activated until all nodes in the priority deployment area are nodes to be activated or can be covered by the nodes to be activated; S6. Output all nodes to be activated as activated nodes to obtain the final roadside unit deployment plan.

[0006] The embodiment of the present invention also provides a roadside unit deployment device based on the intersection node hierarchical activation mechanism, which includes: A data acquisition unit, which is used to quantify the traffic flow fluctuation values of each road by using the traffic flow time series analysis technology based on the urban road network structure and the on-vehicle GPS travel trajectory as the data basis; A road network preprocessing unit, which is used to screen out sub-regions with significant traffic flow fluctuations as the priority deployment area according to the traffic flow fluctuation values of each road, and preprocess the road network data within the priority deployment area; A road network topological unit, which is used to establish a weighted graph model for the preprocessed priority deployment area, store the intersection location information as node attributes, and store the road type and road traffic flow fluctuations as edge attributes, and mark the intersections where roadside units are to be deployed as nodes to be activated; The first-layer unit to be activated, which is used to calculate the edge weights and node weights of the weighted graph model respectively using multi-attribute weighting and node degree. Subsequently, set an adaptive activation threshold to be determined based on the statistical results of all node weights within the priority deployment area. Obtain the first-layer set of nodes to be activated through the partial order relationship between the node weights and the activation threshold to be determined; The second-layer unit to be activated, which is used to iteratively activate the remaining unactivated nodes. Check whether the condition of being directly connected to the nodes to be activated is satisfied through the neighborhood influence function, and obtain the second-layer set of nodes to be activated until all nodes in the priority deployment area are nodes to be activated or can be covered by the nodes to be activated; An intersection deployment unit, which is used to output all nodes to be activated as activated nodes to obtain the final roadside unit deployment plan.

[0007] The present invention also provides a roadside unit deployment device based on the intersection node hierarchical activation mechanism, which includes a processor and a memory. A computer program is stored in the memory, and the computer program can be executed by the processor to implement a roadside unit deployment method based on the intersection node hierarchical activation mechanism as described above.

[0008] The present invention also provides a computer-readable storage medium, on which computer-readable instructions are stored. When the computer-readable instructions are executed by a processor of the device where the computer-readable storage medium is located, a method for deploying roadside units based on an intersection node hierarchical activation mechanism as described above is implemented.

[0009] In summary, compared with the prior art, the present invention has the following beneficial effects: The present invention calculates the road traffic flow fluctuation by analyzing in-vehicle GPS trajectory data, screens high-fluctuation areas as priority deployment areas, adopts a weighted graph model and a partial order relation determination method, introduces an adaptive to-be-activated threshold and a neighborhood influence function, and deploys roadside units in a hierarchical and graded manner. Specifically, the present invention integrates attributes such as intersection positions, road types, and traffic flow fluctuations into a topological graph, preferentially activates high-value nodes through weight calculation and to-be-activated threshold setting, and ensures that unactivated nodes can be covered by to-be-activated nodes, finally forming an efficient and low-cost roadside unit deployment scheme. The present invention can accurately locate traffic demand hotspots, optimize resource allocation, and adaptively adjust the deployment in combination with dynamic traffic flow data, significantly improving the communication efficiency, coverage ability, and economy of the vehicle-road cooperation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0011] Figure 1 The figure shows a schematic flow chart of a method for deploying roadside units based on an intersection node hierarchical activation mechanism provided by Embodiment 1 of the present invention; Figure 2 The figure shows a schematic principle diagram of a method for deploying roadside units based on an intersection node hierarchical activation mechanism provided by Embodiment 1 of the present invention; Figure 3 The figure shows a schematic result diagram of a method for deploying roadside units based on an intersection node hierarchical activation mechanism provided by Embodiment 1 of the present invention; Figure 4 The figure shows a schematic diagram of a device for deploying roadside units based on an intersection node hierarchical activation mechanism provided by Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0013] To better understand the technical solutions of the present invention, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0014] It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0016] It should be understood that the term "and / or" used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0017] Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (stated condition or event)" may be interpreted as "when determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)".

[0018] The "first / second" mentioned in the embodiments is only to distinguish similar objects and does not represent a specific order for the objects. It can be understood that the "first / second" can be interchanged in a specific order or sequence when allowed. It should be understood that the objects distinguished by "first / second" can be interchanged under appropriate circumstances so that the embodiments described here can be implemented in an order other than those illustrated or described here.

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments: Embodiment 1 Embodiment 1 of the present invention provides a method for deploying roadside units based on an intersection node hierarchical activation mechanism, which can be implemented by a roadside unit deployment device based on the intersection node hierarchical activation mechanism (hereinafter referred to as the deployment device). Specifically, it is executed by one or more processors in the deployment device.

[0020] In this embodiment, the deployment device can be an electronic device equipped with a processor. The processor has a computer program for the method of deploying roadside units based on the intersection node hierarchical activation mechanism and the computer program can be executed. For example, a computer, a smart phone, a smart tablet, a workstation, etc., which are not limited herein.

[0021] As Figure 1 shown, a method for deploying roadside units based on an intersection node hierarchical activation mechanism includes steps S1 to S6.

[0022] S1, based on the urban road network structure and vehicle-mounted GPS travel trajectories as data, use flow time series analysis technology to quantify the flow fluctuation values of each road.

[0023] As Figure 2 shown, specifically, the calculation method of the flow fluctuation value of the road is:

[0024]

[0025] Where is the flow fluctuation of road , is the flow in the th time period, is the average flow of road , is the number of time periods in a day, and are the minimum and maximum values of the flow fluctuations of all roads in this area respectively, is the normalized road flow fluctuation.

[0026] S2, according to the flow fluctuation values of each road, screen out sub-regions with significant flow fluctuations as priority deployment regions, and preprocess the road network data in the priority deployment regions.

[0027] Specifically, step S2 includes: S21, select an area of interest from the real road network as the experimental area.

[0028]

[0029] Where represents the experimental area, Represents each longitude and latitude coordinate point in the road data.

[0030] S22. For each road in the road network data , if its geometry intersects with the research area , then this road is retained within the research area.

[0031]

[0032] Among them, R represents the set of original road network data, r is a road in the road network data, is the set of cropped road network data.

[0033] S23. Integrate intersections that are too close into one intersection. Specifically, the calculation model for determining whether intersections are too close is:

[0034] Among them, represents the set of all intersections identified by analyzing the road network, represents the intersection and the intersection the distance between them, represents the minimum distance threshold, selected according to the actual deployment scenario and the dispersion degree of intersection distribution in the road network, represents the set of intersections obtained after applying the distance constraint condition.

[0035] S3. Establish a weighted graph model for the preprocessed priority deployment area, store the intersection location information as node attributes, and store the road type and road traffic flow fluctuations as edge attributes, and identify the intersections of candidate deployed roadside units as nodes to be activated.

[0036] Specifically, step S3 includes: S31. Create an empty weighted undirected graph and an empty set of nodes to be activated A , where is the set of nodes, where is the set of edges, W is the set of weights.

[0037] S32. Each node contains the following attributes:

[0038] Among them, represents the node unique identifier, represents the longitude and latitude coordinates, represents the node weight.

[0039] S33, each edge contains the following attributes:

[0040] Among them, represents the edge unique identifier, represents the road type, including arterial roads, primary roads, secondary roads, tertiary roads, etc., represents the weight of the edge.

[0041] S4. Calculate the edge weights and node weights of the weighted graph model respectively using the multi-attribute weighted sum and node degree, and then set an adaptive activation threshold based on the statistical results of the weights of all nodes within the priority deployment area. Determine the first-layer set of nodes to be activated through the partial order relationship between the node weights and the activation threshold.

[0042] Specifically, step S4 includes: S41. According to the road traffic flow fluctuation and road type, the calculation formula for the weight of the edge is:

[0043] Among them, 、 represent adjustment coefficients, which are used to flexibly adjust the relative importance of traffic flow fluctuation and road type in weight calculation. Generally, is set to 7, is set to 3. is the traffic flow fluctuation after normalization, represents the road type weight function. Due to its importance in the traffic network, the weight of the arterial road is set to 1, the primary road is 0.8, the secondary road is 0.5, and the tertiary road is 0.1.

[0044] S42. After obtaining the weight of the edge, the formula for calculating the node weight is:

[0045] Among them, deg(v i ) represents the node degree, that is, the number of edges connected to this node, the set of edges connected to node represents the sum of the weights of the edges connected to this node.

[0046] S43. Based on the weights of all nodes in the area, set the activation threshold. The specific calculation method is:

[0047] Among them, is the threshold to be activated, k is the adaptive experience adjustment parameter, is the mean value of the node weights, k is the experience adjustment parameter (e.g., 1, 1.5, 2), and the selection of this parameter needs to be determined according to the actual deployment scenario and the degree of dispersion of the weights in the road network. If the distribution of the node weights in the road network is relatively dispersed, a relatively large k value may be required to balance the influence of different nodes; conversely, if the weight distribution is relatively concentrated, a relatively small k value can be selected. By adjusting the k value, the activation threshold can be scientifically and reasonably set according to the overall situation of the node weights in the region, providing an important reference basis for subsequent deployment decisions of roadside units, etc.

[0048] S44, traverse the nodes in the sub-region, judge the partial order relationship between the node weights and the threshold to be activated, if , then add this node to the set of nodes to be activated A to obtain all the nodes greater than the threshold to be activated, which is the first-layer set of nodes to be activated .

[0049] S5, iteratively activate the remaining unactivated nodes, check whether the condition of being directly connected to the nodes to be activated is satisfied through the neighborhood influence function, and obtain the second-layer set of nodes to be activated until all the nodes in the sub-region have been to be activated or can be covered by the nodes to be activated.

[0050] Specifically, step S5 includes: S51, the activation state of the node is represented by the activation indication function :

[0051] Initialize the activation state of the node to 0. S52, for all nodes , define its neighbor node set , and this set represents all the nodes connected to :

[0052] S53, neighborhood influence function:

[0053] S54, each node meets the condition of being to be activated, or at least one neighbor node is to be activated.

[0054]

[0055] Among them, n is the total number of nodes, Aij represents the j-th neighbor node of the i-th node in the set A of nodes to be activated; the meaning of the above formula is: If for each node in the neighbor nodes , it satisfies that it has not joined the set of nodes to be activated , and it has no direct connection with any node in the set of nodes to be activated , then the node is set to be activated and added to the set , and the second-layer set of nodes to be activated is obtained. in

[0056] S55. When all nodes satisfy (the node is already in the set of nodes to be activated), or is connected to a certain node in the set of nodes to be activated , that is, there exists such that (the node can be covered by the nodes to be activated), then the activation stops.

[0057] S6. Output all the nodes to be activated as activated nodes to obtain the final roadside unit deployment plan.

[0058] The result of the final roadside unit deployment is as Figure 3 shown. Specifically, Figure 3 in

[0059] the lines of different colors represent roads of different levels. Among them, the red edges represent arterial roads, the yellow edges represent first-class roads, the green edges represent second-class roads, the blue edges represent third-class roads, the red circles represent the activated nodes, that is, the road intersections where roadside units need to be deployed, and the white circles represent the unactivated nodes. In the embodiment of the present invention, by analyzing the on-vehicle GPS trajectory data to calculate the road traffic flow fluctuations, screening the high-fluctuation areas as the priority deployment areas, adopting the weighted graph model and the partial order relation determination method, introducing the adaptive activation threshold and the neighborhood influence function, the roadside units are deployed in layers and grades. Specifically, the present invention integrates attributes such as intersection positions, road types, and traffic flow fluctuations into the topological graph, preferentially activates high-value nodes through weight calculation and activation threshold setting, and ensures that the unactivated nodes can be covered by the activated nodes, and finally forms an efficient and low-cost roadside unit deployment plan. The present invention can accurately locate the traffic demand hotspots, optimize the resource allocation, and at the same time adaptively adjust the deployment in combination with the dynamic traffic flow data, significantly improving the communication efficiency, coverage ability, and economy of the vehicle-road cooperation system.

[0060] Example 2 As shown in Figure 4 the figure, an embodiment of the present invention provides a roadside unit deployment device based on an intersection node hierarchical activation mechanism, including: A data acquisition unit 101, configured to quantify the traffic fluctuation values of each road by using a traffic time series analysis technique based on the urban road network structure and the in-vehicle GPS travel trajectory as data bases; A road network preprocessing unit 102, configured to screen out sub-regions with significant traffic fluctuations as priority deployment regions according to the traffic fluctuation values of each road, and preprocess the road network data within the priority deployment regions; A road network topological unit 103, configured to establish a weighted graph model for the preprocessed priority deployment region, store the intersection position information as node attributes, and store the road type and road traffic fluctuations as edge attributes, and identify the intersections where the roadside units to be deployed are located as nodes to be activated; A first-layer node-to-be-activated unit 104, configured to calculate the edge weights and node weights of the weighted graph model by using multi-attribute weighting and node degree respectively, and then set an adaptive activation threshold based on the statistical results of all node weights within the priority deployment region, and obtain a first-layer node-to-be-activated node set through the partial order relationship judgment between the node weights and the activation threshold; A second-layer node-to-be-activated unit 105, configured to iteratively activate the remaining unactivated nodes, and check whether the conditions for being directly connected to the nodes to be activated are met through a neighborhood influence function, and obtain a second-layer node-to-be-activated node set until all nodes in the priority deployment region are nodes to be activated or can be covered by the nodes to be activated; An intersection deployment unit 106, configured to output all nodes to be activated as activated nodes, and obtain a final roadside unit deployment plan.

[0061] Example 3 An embodiment of the present invention provides a roadside unit deployment device based on an intersection node hierarchical activation mechanism, which includes a processor, a memory, and a computer program stored in the memory. The computer program can be executed by the processor to implement a roadside unit deployment method based on an intersection node hierarchical activation mechanism as described in Example 1.

[0062] Example 4 An embodiment of the present invention provides a computer-readable storage medium, and the computer-readable storage medium includes a stored computer program, wherein when the computer program runs, it controls the device where the computer-readable storage medium is located to execute a roadside unit deployment method based on an intersection node hierarchical activation mechanism as described in Example 1.

[0063] In several embodiments provided by the embodiments of the present invention, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of devices, methods, and computer program products according to multiple embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0064] In addition, the functional modules in each embodiment of the present invention can be integrated together to form an independent part, or each module can exist separately, or two or more modules can be integrated to form an independent part.

[0065] If the described functions are implemented in the form of software functional modules 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, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, an electronic device, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, etc., which can store program codes. It should be noted that in this article, the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article, or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article, or device including the said element.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for deploying roadside units based on an intersection node hierarchical activation mechanism, characterized in that Including: S1. Based on the urban road network structure and in-vehicle GPS travel trajectories as data, adopt flow time series analysis technology to quantify the flow fluctuation values of each road; S2. According to the flow fluctuation values of each road, screen out sub-regions with significant flow fluctuations as priority deployment regions, and preprocess the road network data within the priority deployment regions; S3. Establish a weighted graph model for the preprocessed priority deployment regions, store intersection location information as node attributes, and store road types and road flow fluctuations as edge attributes. Identify intersections where roadside units are to be deployed as nodes to be activated; S4. Calculate the edge weights and node weights of the weighted graph model using multi-attribute weighting and node degree respectively. Subsequently, set an adaptive activation threshold based on the statistical results of all node weights within the priority deployment region. Determine through the partial order relationship between the node weights and the activation threshold to obtain the first set of nodes to be activated; S5. Iteratively activate the remaining unactivated nodes, and verify whether the condition of being directly connected to the nodes to be activated is satisfied through the neighborhood influence function to obtain the second set of nodes to be activated until all nodes in the priority deployment region are to be activated or can be covered by the nodes to be activated; S6. Output all nodes to be activated as activated nodes to obtain the final roadside unit deployment plan.

2. The method for deploying roadside units based on the intersection node hierarchical activation mechanism according to claim 1, wherein The calculation method of the flow fluctuation value of the road is as follows: Among them, is the traffic fluctuation value of the road , is the traffic volume in the th time period, is the average traffic volume of the road , is the number of time periods in a day, and are the minimum and maximum values of the traffic fluctuation values of all roads in the area respectively, is the normalized traffic fluctuation value of the road.

3. A roadside unit deployment method based on an intersection node hierarchical activation mechanism according to claim 1, characterized in that The preprocessing of the road network data within the priority deployment region specifically is: Identify intersections for the road information in the road network within the priority deployment region. One road intersection may generate two or more intersection points. Remove duplicate intersection points at the same intersection: Among them, represents the region of interest, represents each longitude and latitude coordinate point in the road data, , are respectively the minimum and maximum values of the coordinate point in the x direction, , are respectively the minimum and maximum values of the coordinate point in the y direction; For each road in the road network data , if its geometry intersects with the region of interest , then the road is retained within the study area; Among them, R represents the set of original road network data, and r is a road in the road network data. is the set of road network data after cropping; Integrate intersections that are too close to each other into one intersection. Among them, the calculation model for judging whether intersections are too close to each other is: Among them, represents the set of all intersections identified by analyzing the road network, represents an intersection and intersection the distance between, represents the minimum distance threshold for determining whether intersections are too close to each other, represents the set of intersections obtained after applying the distance constraint condition.

4. A roadside unit deployment method based on an intersection node hierarchical activation mechanism according to claim 1, characterized in that The specific process of establishing the weighted graph model is: Create an empty weighted undirected graph and an empty set of nodes to be activated A , where is a set of nodes, where is a set of edges, W is a set of weights; Each node includes the following attributes: Among them, represents the unique identifier of the node, represents the longitude and latitude coordinates, represents the node weight; Each edge includes the following attributes: Among them, represents the unique edge identifier, represents the road type, including arterial roads, primary roads, secondary roads, and tertiary roads; represents the weight of the edge.

5. A roadside unit deployment method based on an intersection node hierarchical activation mechanism according to claim 4, characterized in that Step S4 specifically is: According to the attributes of two types of edges, namely road type and road flow fluctuation, use the multi-attribute weighting function to calculate the edge weights. Subsequently, integrate the edge weights and calculate the node weights based on the node degree. The calculation methods of the edge weights and node weights are: Among them, and represent adjustment coefficients; is the flow fluctuation after normalization; represents the road type weight function; deg ( v i ) represents the degree of node , that is, the number of edges connected to this node; is the set of edges connected to node ; represents the sum of the weights of the edges connected to this node. Utilize the numerical distribution characteristics of node weights within the priority deployment region to develop an adaptive activation threshold generation mechanism to achieve dynamic response to road network environments of different scales and different characteristics. The calculation method of the activation threshold is: Among them, is the threshold to be activated, k is the adaptive experience adjustment parameter, is the mean value of the node weights; Traverse the nodes within the priority deployment region, judge the partial order relationship between the node weights and the activation threshold, and obtain all nodes greater than the activation threshold, which are the first set of nodes to be activated.

6. The method for deploying roadside units based on the intersection node hierarchical activation mechanism according to claim 4, wherein The specific process of obtaining the second set of nodes to be activated is: The activation state of the node is represented by an activation indication function as follows: Initialize the activation status of the nodes to 0; For all nodes , define the set of its neighbor nodes , which represents all nodes connected to : Neighborhood influence function: Each node Meets the requirement to be activated, or at least one neighboring node To be activated; where n is the total number of nodes, Aij represents the j-th neighbor node of the i-th node in the set A of nodes to be activated. The meaning of the above formula is: If for neighbor nodes Each node in , all satisfy that it has not been added to the set of nodes to be activated , and it is the same as the set of nodes to be activated Any node in No direct connection , then the node Set to be activated and add to the set of nodes to be activated , obtain the set of nodes to be activated in the second layer; When all nodes meet or is connected to a certain node in the set of nodes to be activated , that is, there exists such that , then the activation stops.

7. A roadside unit deployment method based on an intersection node hierarchical activation mechanism according to claim 1, characterized in that Output all the first and second sets of nodes to be activated as activated nodes, which is the final roadside unit deployment plan.

8. A roadside unit deployment device based on an intersection node hierarchical activation mechanism, characterized in that Including: Data acquisition unit, which is used to, based on the urban road network structure and in-vehicle GPS travel trajectories as data, adopt flow time series analysis technology to quantify the flow fluctuation values of each road; Road network preprocessing unit, which is used to, according to the flow fluctuation values of each road, screen out sub-regions with significant flow fluctuations as priority deployment regions and preprocess the road network data within the priority deployment regions; The road network topology unit is used to establish a weighted graph model for the preprocessed priority deployment area, store the intersection location information as node attributes, and store the road type and road traffic fluctuations as edge attributes, and identify the intersections of the candidate deployed roadside units as nodes to be activated; The first layer of units to be activated is used to calculate the edge weights and node weights of the weighted graph model by using multi-attribute weighted sum and node degree respectively. Subsequently, an adaptive activation threshold is set based on the statistical results of all node weights in the priority deployment area, and the first layer of nodes to be activated is obtained through the partial order relationship judgment between the node weights and the activation threshold; The second layer of units to be activated is used to iteratively activate the remaining unactivated nodes, and check whether the conditions for being directly connected to the nodes to be activated are met through the neighborhood influence function, and obtain the second layer of nodes to be activated until all the nodes in the priority deployment area are nodes to be activated or can be covered by the nodes to be activated; The intersection deployment unit is used to output all the nodes to be activated as activated nodes to obtain the final roadside unit deployment plan.

Images