A Time-Varying Graph-Based Delay-Tolerant Data Dissemination Method and System

Abstract

The present invention relates to the field of vehicle networking communication technologies, and particularly to a delay-tolerant data distribution method and system based on a time-varying graph. The delay-tolerant data distribution method based on a time-varying graph includes: through a time-varying graph data transmission model with delay constraints, multiple vehicle-mounted nodes exchange initial data with each other to obtain the communication data and link data of each vehicle-mounted node; an unmanned aerial vehicle collects the communication data and link data, and obtains the channel capacity, transmission rate, and transmission delay based on the link data; the unmanned aerial vehicle calculates the network utility value according to the transmission rate and transmission delay, and uses the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay; the unmanned aerial vehicle calls the k data distribution algorithm based on the channel capacity, communication transmission rate, and communication transmission delay to distribute the communication data to multiple vehicle-mounted nodes. The present invention provides real-time and reliable data transmission for delay-sensitive vehicle networking applications, and improves the communication efficiency of vehicle networking.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle - to - everything (V2X) communication, and particularly to a delay - tolerant data distribution method and system based on a time - varying graph. Background Art

[0002] V2X mainly provides core services such as traffic accident early warning, traffic positioning management, and information provision oriented to user satisfaction, and realizes better traffic control by pushing road status information and real - time traffic flow monitoring. Enhancing the perception ability of roadside infrastructure helps the coordinated development of intelligent connected vehicles and smart cities. The continuous evolution of V2X application scenarios and service capabilities also helps to improve the perception ability of autonomous driving, reduce the impact of adverse environmental factors such as occlusion and bad weather on the single - vehicle perception ability, and assist in alleviating the contradiction between the computing power and power consumption of autonomous driving.

[0003] However, in - vehicle networks, infrastructure (base stations and roadside units) is static, and there are communication - restricted situations in specific cases, such as high - traffic demands in hotspots and damage to infrastructure in emergencies. At the same time, the rapid movement of vehicles generates a highly dynamic network topology, and the occlusion of obstacles also leads to problems of large node - density differences and incomplete network coverage, reducing communication efficiency. Summary of the Invention

[0004] Embodiments of the present invention provide a delay - tolerant data distribution method and system based on a time - varying graph. The technical solutions are as follows:

[0005] On the one hand, a delay - tolerant data distribution method based on a time - varying graph is provided. This method is implemented by an electronic device, and the method includes:

[0006] This method is implemented by a delay - tolerant data distribution system based on a time - varying graph. The delay - tolerant data distribution system based on a time - varying graph includes multiple vehicle - mounted nodes and unmanned aerial vehicles (UAVs).

[0007] The method includes:

[0008] Through a time - varying graph data transmission model with delay constraints, the multiple vehicle - mounted nodes exchange initial data with each other to obtain communication data and link data of each vehicle - mounted node.

[0009] The UAV collects the communication data and link data, and obtains the channel capacity, transmission rate, and transmission delay based on the link data.

[0010] The UAV calculates the network utility value according to the transmission rate and the transmission delay, and uses the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay.

[0011] Based on the channel capacity, the communication transmission rate, and the communication transmission delay, the drone calls the k - data distribution algorithm to distribute the communication data to the multiple vehicle nodes.

[0012] Optionally, the time - varying graph data transmission model with delay constraints consists of multiple vehicle nodes;

[0013] The multiple vehicle nodes exchange initial data with each other to obtain the communication data and link data of each vehicle node, including:

[0014] When the target vehicle node exchanges data with an adjacent node, the target vehicle node transmits the initial data to the adjacent node, and the target vehicle node and the adjacent node obtain the communication data and link data;

[0015] When the target vehicle node exchanges data with a non - adjacent node, the target vehicle node transmits the initial data to the non - adjacent node through one or more relay nodes, and the target vehicle node and the non - adjacent node obtain the communication data and link data.

[0016] Optionally, the drone calculates the network utility value according to the transmission rate and the transmission delay, including:

[0017] The drone establishes a transmission rate utility function and a transmission delay utility function. According to the transmission rate utility function and the transmission delay utility function, it obtains the transmission rate utility value and the transmission delay utility value, and calculates the network utility value based on the transmission rate utility value and the transmission delay utility value.

[0018] Optionally, the step of calling the k - data distribution algorithm to distribute the communication data to multiple vehicle nodes based on the channel capacity, the communication transmission rate, and the communication transmission delay includes:

[0019] Set the carrier for sending data according to the channel capacity, the communication transmission rate, and the communication transmission delay;

[0020] Based on the k - data distribution algorithm, send the communication data to multiple vehicle nodes through the carrier.

[0021] Optionally, the step of sending the communication data to the vehicle node based on the k - data distribution algorithm includes:

[0022] S51. Set the data set to be sent as K, the data set currently owned by the vehicle node as data u , and the number of data distribution stages as a, and let a = 1;

[0023] S52. Judge whether data u is equal to K. If data uIf it is equal to K, then transfer to step S55 for execution. If data u is not equal to K, then execute step S53;

[0024] S53. The vehicle node broadcasts its own data and receives new data from neighboring vehicle nodes;

[0025] S54. The vehicle node adds the received new data and updates data u , let a = a + 1, and execute step S52;

[0026] S55. The communication terminates, outputs the stage number a, and saves the stage number a.

[0027] On the other hand, a delay-tolerant data distribution system based on a time-varying graph is provided. The system is applied to implement a delay-tolerant data distribution method based on a time-varying graph. The delay-tolerant data distribution system based on a time-varying graph includes multiple vehicle nodes and unmanned aerial vehicles, where:

[0028] Through a time-varying graph data transmission model with delay constraints, the multiple vehicle nodes exchange initial data with each other to obtain the communication data and link data of each vehicle node.

[0029] The unmanned aerial vehicle collects the communication data and link data, obtains the channel capacity, transmission rate, and transmission delay based on the link data; calculates the network utility value according to the transmission rate and the transmission delay, and uses the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay; based on the channel capacity, the communication transmission rate, and the communication transmission delay, calls the k data distribution algorithm to distribute the communication data to the multiple vehicle nodes.

[0030] Optionally, the time-varying graph data transmission model with delay constraints is composed of multiple vehicle nodes;

[0031] The multiple vehicle nodes are further used for:

[0032] When the target vehicle node exchanges data with an adjacent node, the target vehicle node transmits the initial data to the adjacent node, and the target vehicle node and the adjacent node obtain the communication data and link data;

[0033] When the target vehicle node exchanges data with a non-adjacent node, the target vehicle node transmits the initial data to the non-adjacent node through one or more relay nodes, and the target vehicle node and the non-adjacent node obtain the communication data and link data.

[0034] Optionally, the unmanned aerial vehicle is further used for:

[0035] The drone establishes a transmission rate utility function and a transmission delay utility function, obtains a transmission rate utility value and a transmission delay utility value according to the transmission rate utility function and the transmission delay utility function, and calculates a network utility value according to the transmission rate utility value and the transmission delay utility value.

[0036] Optionally, the drone is further configured to:

[0037] Set the carrier for transmitting data according to the channel capacity, the communication transmission rate, and the communication transmission delay;

[0038] Based on the k data distribution algorithm, send the communication data to multiple vehicle-mounted nodes through the carrier.

[0039] Optionally, the drone is further configured to:

[0040] S51. Set the set of data to be sent as K, the set of data currently owned by the vehicle-mounted node as data u , and the number of data distribution stages as a, and let a = 1;

[0041] S52. Determine whether data u is equal to K. If data u is equal to K, then go to step S55. If data u is not equal to K, then execute step S53;

[0042] S53. The vehicle-mounted node broadcasts its own data and receives new data from neighboring vehicle-mounted nodes;

[0043] S54. The vehicle-mounted node adds the received new data and updates data u , let a = a + 1, and execute step S52;

[0044] S55. Terminate the communication, output the stage number a, and save the stage number a.

[0045] On the other hand, an electronic device is provided. The electronic device includes a processor and a memory. At least one instruction is stored in the memory, and the at least one instruction is loaded and executed by the processor to implement the above-mentioned delay-tolerant data distribution method based on a time-varying graph.

[0046] On the other hand, a computer-readable storage medium is provided. At least one instruction is stored in the storage medium, and the at least one instruction is loaded and executed by a processor to implement the above-mentioned delay-tolerant data distribution method based on a time-varying graph.

[0047] The beneficial effects brought by the technical solution provided in the embodiments of the present invention at least include:

[0048] The present invention uses a time-varying graph to describe the dynamic topology of the unmanned aerial vehicle (UAV)-assisted vehicular network. By combining the transmission delay with the time-varying graph, a data transmission model with delay constraints for the time-varying graph is proposed. By adding a delay factor to the original time-varying graph model, the data transmission model with delay constraints for the time-varying graph can be widely applied to delay-tolerant network scenarios. The present invention proposes a data distribution method based on k-token transmission in the UAV-assisted vehicular network. Thanks to the flexible and rapid deployment characteristics of UAVs, deploying UAVs on demand can provide services such as dynamic coverage and relaying for wireless communication, make up for the deficiencies of the ground-based vehicular network, have the ability to provide elastic services, better respond to sudden service demands, provide real-time and reliable data transmission for delay-sensitive vehicular network applications, and improve the communication efficiency of the vehicular network. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0050] Figure 1 is a flowchart of a delay-tolerant data distribution method based on a time-varying graph provided by an embodiment of the present invention;

[0051] Figure 2 is a block diagram of a data distribution process based on a k-data distribution algorithm provided by an embodiment of the present invention;

[0052] Figure 3 is a system block diagram of a delay-tolerant data distribution method based on a time-varying graph provided by an embodiment of the present invention;

[0053] Figure 4 is a schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0055] An embodiment of the present invention provides a delay-tolerant data distribution method based on a time-varying graph. This method can be implemented by an electronic device, which can be a terminal or a server. As Figure 1 shown in the flowchart of the delay-tolerant data distribution method based on a time-varying graph, the processing flow of this method can include the following steps:

[0056] S1. Through the data transmission model with delay constraints for the time-varying graph, multiple vehicle-mounted nodes exchange initial data with each other to obtain the communication data and link data of each vehicle-mounted node.

[0057] Optionally, the time-varying graph data transmission model with delay constraints consists of multiple vehicle nodes;

[0058] Multiple vehicle nodes exchange initial data with each other to obtain the communication data and link data of each vehicle node, including:

[0059] When the target vehicle node exchanges data with an adjacent node, the target vehicle node transmits the initial data to the adjacent node, and the target vehicle node and the adjacent node obtain the communication data and link data;

[0060] When the target vehicle node exchanges data with a non-adjacent node, the target vehicle node transmits the initial data to the non-adjacent node through one or more relay nodes, and the target vehicle node and the non-adjacent node obtain the communication data and link data.

[0061] In a feasible implementation, as a basic tool for seeking solutions to corresponding problems in dynamic networks, graph theory can provide complex theoretical analysis. Research work often abstracts network topologies into various graphs, such as arbitrary graphs, linear graphs, and complete graphs. The methods for describing dynamic network topologies mainly include instantaneous graphs, aggregated graphs, and time-varying graphs. Instantaneous graphs consider network topologies with a time constant. The disadvantage is that they do not consider the time-varying characteristics of the network and cannot predict the evolution state of the dynamic network. Aggregated graphs focus on the network topology over a period of time and can only reflect the characteristics of static networks. Their advantage is that many mature characteristics of static graphs can be used for network analysis. However, due to the rapid movement of vehicles and drones, communication links may be valid for a very short time. In actual network analysis, when instantaneous graphs and aggregated graphs are used to describe network topologies, time information will be omitted. At the same time, combined with the delay-sensitive characteristics of data transmission, the transmission delay is integrated into the time-varying graph, and a data transmission model of a delay-tolerant time-varying graph DTVG (Delay-tolerant Time-Varying Graph) is proposed. This model can be widely applied to delay-tolerant network topology scenarios;

[0062] The delay-tolerant time-varying graph DTVG data transmission model is expressed as G = (V, E, T, f(r l ), ζ). G represents the graph abstracted from the vehicle network topology; V represents the topology network vertices; E represents the topology network communication links; T is the network life cycle, and the network life cycle is divided into the same time intervals, represented by T1, T2, …, T n represents; f(r l ) reflects the transmission gain of the corresponding link. If the communication link l does not exist at a given moment, then f(r l ) is zero, r lLet \(R\) be the link transmission rate. The fluctuation range of the link transmission rate is determined by the hardware characteristics of the terminal device and the coding rate, and the specific value is determined according to the channel quality and delay conditions; \(\zeta\) represents the transmission delay threshold between nodes. If the threshold is exceeded, the transmission is invalid, that is, the link transmission needs to meet the following conditions for success.

[0063] S2. The drone collects communication data and link data, and obtains the channel capacity, transmission rate, and transmission delay based on the link data.

[0064] In a feasible implementation, the vehicle-mounted node exchanges data through a delay-constrained time-varying graph data transmission model to obtain link data. The link data includes basic data of the communication link such as the maximum link transmission rate that the communication link can send, link bandwidth, packet length, and signal-to-interference-plus-noise ratio (SINR). The channel capacity can be calculated according to the link bandwidth, and the calculation formula is as shown in Equation (1) below:

[0065] c l =W log(1 + SINR)……(1)

[0066] where \(c\) l is the channel capacity, \(W\) is the link bandwidth, and SINR is the signal-to-interference-plus-noise ratio.

[0067] The transmission delay can be calculated according to the channel capacity and the packet length, and the calculation formula is as shown in Equation (2) below:

[0068] d l =H / (c l -r l )……(2)

[0069] where \(d\) l is the transmission delay, \(H\) is the packet length, \(c\) l is the channel capacity, and \(r\) l is the link transmission rate.

[0070] S3. The drone calculates the network utility value according to the transmission rate and the transmission delay, and uses the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay.

[0071] Optionally, the drone calculates the network utility value according to the transmission rate and the transmission delay, including:

[0072] The drone establishes a transmission rate utility function and a transmission delay utility function. According to the transmission rate utility function and the transmission delay utility function, it obtains the transmission rate utility value and the transmission delay utility value, and calculates the network utility value based on the transmission rate utility value and the transmission delay utility value.

[0073] In a feasible implementation manner, since the link transmission rate is affected by the hardware characteristics of the terminal device and the coding rate, there is a certain value range for setting the link transmission rate. The problem of how to maximize the network utility is transformed into selecting an appropriate link transmission rate to maximize the network utility.

[0074] Establish a transmission rate utility function U(r l ) and a transmission delay utility function V(d l ), and the calculation formulas are as shown in the following formula (3):

[0075] U(r l ) = log(r l ); V(d l ) = log(d l )...(3)

[0076] According to the transmission rate utility function U(r l ) and the transmission delay utility function V(d l ), calculate the maximum network utility, and the calculation formula is as shown in the following formula (4):

[0077]

[0078] Among them, the first constraint condition means that the transmission rate should not exceed the maximum capacity of the link, the second constraint condition means that the transmission delay should be within the delay threshold range to ensure the effective transmission of data, and the third constraint condition means that the link transmission power range is [p min , p max to reduce signal interference. By solving this problem, while ensuring the data transmission performance, the network utility is maximized.

[0079] S4. The drone distributes the communication data to multiple vehicle-mounted nodes by invoking the k data distribution algorithm based on the channel capacity, communication transmission rate, and communication transmission delay.

[0080] Optionally, distributing the communication data to multiple vehicle-mounted nodes by invoking the k data distribution algorithm based on the channel capacity, communication transmission rate, and communication transmission delay includes:

[0081] S41. Set the carrier for sending data according to the channel capacity, communication transmission rate, and communication transmission delay;

[0082] S42. Based on the k data distribution algorithm, send the communication data to multiple vehicle-mounted nodes through the carrier.

[0083] Optionally, as Figure 2 shown, sending the communication data to the vehicle-mounted nodes based on the k data distribution algorithm in S42 may include the following steps S421 - S425:

[0084] S421. Set the data set to be sent as K, and the data set currently owned by the vehicle-mounted node as data u , and the number of data distribution stages is a. Let a = 1;

[0085] S422. Determine whether data u is equal to K. If data u is equal to K, then go to step S425. If data u is not equal to K, then execute step S423;

[0086] S423. The vehicle-mounted node broadcasts its own data and receives new data from neighboring vehicle-mounted nodes;

[0087] S424. The vehicle-mounted node adds the received new data and updates data u , let a = a + 1, and execute step S422;

[0088] S425. The communication terminates, outputs the stage number a, and saves the stage number a.

[0089] In a feasible implementation, assume there are n nodes. In each round of communication, each node will exchange information with its neighboring nodes. The time-varying graph is used to analyze the dynamic topological structure of each round. Assume that the time-varying graph can be regarded as continuously connected within the standard time slot, or at least connected within 1 interval, to reveal the data transmission characteristics in the dynamic network. For example, if all nodes broadcast information in each round, then at least one node will obtain additional information, that is, new data has been distributed in the network.

[0090] There are mainly two ways for nodes to receive new data: the data obtained through allocation in the initialization stage or the data updated according to the received neighbor information. In the initialization stage, node u has k pieces of data, the data set is K, and the data of other nodes is empty. In each communication stage, the node broadcasts its own data, and the node that receives new data from its neighbor will add the data to the data set. When the communication node receives all the data, the iteration terminates, outputs the iteration stage number a, and saves the stage number a in the working log for inspection and maintenance.

[0091] The present invention uses a time-varying graph to describe the dynamic topology of an unmanned aerial vehicle (UAV)-assisted vehicle-to-everything (V2X) network. By combining transmission delay with the time-varying graph, a delay-constrained time-varying graph data transmission model is proposed. By adding a delay factor to the original time-varying graph model, the delay-constrained time-varying graph data transmission model can be widely applied to delay-tolerant network scenarios. The present invention proposes a data distribution method based on k-token transmission in a UAV-assisted V2X network. Thanks to the flexible and rapid deployment characteristics of UAVs, UAVs can be deployed on demand to provide services such as dynamic coverage and relaying for wireless communication, which can make up for the deficiencies of ground-based V2X networks, have the ability to provide elastic services, better respond to sudden service demands, provide real-time and reliable data transmission for delay-sensitive V2X applications, and improve the communication efficiency of V2X networks.

[0092] Figure 3 FIG. is a block diagram of a delay-tolerant data distribution system based on a time-varying graph shown according to an exemplary embodiment. This system is applied to implement a delay-tolerant data distribution method based on a time-varying graph. Referring to Figure 3 , the system includes multiple vehicle-mounted nodes and UAVs, where:

[0093] Through the delay-constrained time-varying graph data transmission model, multiple vehicle-mounted nodes exchange initial data with each other to obtain the communication data and link data of each vehicle-mounted node.

[0094] The UAV collects the communication data and link data, obtains the channel capacity, transmission rate, and transmission delay based on the link data; calculates the network utility value according to the transmission rate and transmission delay, and uses the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay; based on the channel capacity, communication transmission rate, and communication transmission delay, calls the k-data distribution algorithm to distribute the communication data to multiple vehicle-mounted nodes.

[0095] Optionally, the delay-constrained time-varying graph data transmission model is composed of multiple vehicle-mounted nodes;

[0096] The multiple vehicle-mounted nodes are further configured to:

[0097] When the target vehicle-mounted node exchanges data with an adjacent node, the target vehicle-mounted node transmits the initial data to the adjacent node, and the target vehicle-mounted node and the adjacent node obtain the communication data and link data.

[0098] When the target vehicle-mounted node exchanges data with a non-adjacent node, the target vehicle-mounted node transmits the initial data to the non-adjacent node through one or more relay nodes, and the target vehicle-mounted node and the non-adjacent node obtain the communication data and link data.

[0099] Optionally, the UAV is further configured to:

[0100] The UAV establishes a transmission rate utility function and a transmission delay utility function, obtains a transmission rate utility value and a transmission delay utility value according to the transmission rate utility function and the transmission delay utility function, and calculates a network utility value according to the transmission rate utility value and the transmission delay utility value.

[0101] Optionally, the drone is further used to:

[0102] The carrier for sending data is set according to the channel capacity, communication transmission rate and communication transmission delay;

[0103] Based on the k data distribution algorithm, the communication data is sent to multiple vehicle-mounted nodes through the carrier.

[0104] Optionally, the drone is further used for:

[0105] S51, set the data set to be sent to K, and the data set currently owned by the vehicle node to data u , the number of data distribution stages is a, let a = 1;

[0106] S52, judge data u Is it equal to K? If data u Equal to K, then go to step S55. If data u If it is not equal to K, then execute step S53;

[0107] S53, the vehicle-mounted node broadcasts its own data and receives new data from neighboring vehicle-mounted nodes;

[0108] S54, the vehicle node adds the received new data and updates the data u , let a=a+1, and execute step S52;

[0109] S55. Communication is terminated, the stage number a is output, and the stage number a is saved.

[0110] The present invention uses a time-varying graph to describe the dynamic topology of the drone-assisted Internet of Vehicles, combines the transmission delay with the time-varying graph to propose a delay-constrained time-varying graph data transmission model, and by adding a delay factor to the original time-varying graph model, the delay-constrained time-varying graph data transmission model can be widely used in delay-tolerant network scenarios. The present invention proposes a data distribution method based on k-token transmission in a drone-assisted Internet of Vehicles. Thanks to the flexible and rapid deployment of drones, on-demand deployment of drones can provide dynamic coverage, relay and other services for wireless communications, which can make up for the shortcomings of ground-based Internet of Vehicles, have the ability to provide flexible services, better respond to sudden service needs, and provide real-time and reliable data transmission for delay-sensitive Internet of Vehicles applications, thereby improving the efficiency of Internet of Vehicles communications.

[0111] Figure 4It is a schematic structural diagram of an electronic device 400 provided by an embodiment of the present invention. The electronic device 600 may vary greatly due to different configurations or performances, and may include one or more processors (central processing units, CPUs) 401 and one or more memories 402. Among them, at least one instruction is stored in the memory 402, and the at least one instruction is loaded and executed by the processor 401 to implement the steps of the above-mentioned time-varying graph-based delay-tolerant data distribution method.

[0112] In an exemplary embodiment, a computer-readable storage medium is also provided. For example, a memory including instructions, and the above instructions can be executed by a processor in a terminal to complete the above-mentioned time-varying graph-based delay-tolerant data distribution method. For example, the computer-readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0113] Those of ordinary skill in the art can understand that all or part of the steps of implementing the above embodiments can be completed by hardware, or can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk, or an optical disc, etc.

[0114] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A time-varying graph-based delay-tolerant data dissemination method, characterized in that The method is implemented by a delay-tolerant data distribution system based on a time-varying graph, and the delay-tolerant data distribution system based on a time-varying graph includes multiple vehicle nodes and unmanned aerial vehicles (UAVs). The method includes: Through a delay-constrained time-varying graph data transmission model, the multiple vehicle nodes exchange initial data with each other to obtain the communication data and link data of each vehicle node. Among them, the time-varying graph data transmission model with delay constraints is represented as G=(V, E, T, f(r l ), ζ); Among them, G represents the graph abstracted from the vehicle networking network topology; V represents the topology network vertices; E represents the topology network communication links; T is the network lifetime, and the network lifetime is divided into the same time intervals, represented by T1, T2, …, T n denotes; f(r l ) represents the transmission gain of the corresponding link. If the communication link l does not exist at a given moment, then f(r l ) is zero, r l is the link transmission rate, and the link transmission rate fluctuates within a range determined by the hardware characteristics of the terminal device and the coding rate; ζ represents the transmission delay threshold between nodes, and if it exceeds this threshold, the transmission is invalid; The UAVs collect the communication data and link data, and obtain the channel capacity, transmission rate, and transmission delay based on the link data. The UAVs calculate the network utility value according to the transmission rate and the transmission delay, and use the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay. Based on the channel capacity, the communication transmission rate, and the communication transmission delay, the UAVs call the k-data distribution algorithm to distribute the communication data to the multiple vehicle nodes. Among them, calling the k-data distribution algorithm based on the channel capacity, the communication transmission rate, and the communication transmission delay to distribute the communication data to multiple vehicle nodes includes: According to the channel capacity, the communication transmission rate, and the communication transmission delay, set the carrier for sending data. Based on the k-data distribution algorithm, send the communication data to multiple vehicle nodes through the carrier. Among them, sending the communication data to multiple vehicle nodes based on the k-data distribution algorithm includes: S51. Set the data set to be sent as K, and the data set currently owned by the vehicle node is data u , the number of data distribution stages is a, and let a = 1; S52. Determine if data u is equal to K. If data u is equal to K, then go to execute step S55. If data u is not equal to K, then execute step S53; S53. The vehicle node broadcasts its own data and receives new data from neighboring vehicle nodes. The in-vehicle node adds the newly received data and updates data u , let a = a + 1, and execute step S52; S55. The communication terminates, outputs the number of stages a, and saves the number of stages a.

2. The method according to claim 1, wherein The delay-constrained time-varying graph data transmission model is composed of multiple vehicle nodes. The multiple vehicle nodes exchange initial data with each other to obtain the communication data and link data of each vehicle node, including: When the target vehicle node exchanges data with an adjacent node, the target vehicle node transmits the initial data to the adjacent node, and the target vehicle node and the adjacent node obtain the communication data and link data. When the target vehicle node exchanges data with a non-adjacent node, the target vehicle node transmits the initial data to the non-adjacent node through one or more relay nodes, and the target vehicle node and the non-adjacent node obtain the communication data and link data.

3. The method according to claim 1, characterized in that, The UAVs calculate the network utility value according to the transmission rate and the transmission delay, including: The UAVs establish a transmission rate utility function and a transmission delay utility function, obtain the transmission rate utility value and the transmission delay utility value according to the transmission rate utility function and the transmission delay utility function, and calculate the network utility value according to the transmission rate utility value and the transmission delay utility value.

4. A delay-tolerant data dissemination system based on a time-varying graph, characterized in that, The system is used to implement a delay-tolerant data distribution method based on a time-varying graph. The delay-tolerant data distribution system based on a time-varying graph includes multiple vehicle nodes and UAVs, where: The multiple vehicle nodes are used to exchange initial data through a delay-constrained time-varying graph data transmission model to obtain the communication data and link data of each vehicle node. Among them, the time-varying graph data transmission model with delay constraints is expressed as G=(V, E, T, f(r l ), ζ); Among them, G represents the graph abstracted from the vehicle networking network topology; V represents the topology network vertices; E represents the topology network communication links; T is the network lifetime, and the network lifetime is divided into the same time intervals, represented by T1, T2, …, T n denotes; f(r l ) represents the transmission gain of the corresponding link. If the communication link l does not exist at a given moment, then f(r l ) is zero, r l is the link transmission rate, and the link transmission rate fluctuates within a range determined by the hardware characteristics of the terminal device and the coding rate; ζ represents the transmission delay threshold between nodes, and transmission is invalid if it exceeds this threshold; The unmanned aerial vehicle is used to collect the communication data and link data, obtain the channel capacity, transmission rate, and transmission delay based on the link data; calculate the network utility value according to the transmission rate and the transmission delay, and use the transmission rate and transmission delay with the maximum network utility value as the communication transmission rate and communication transmission delay; call the K data distribution algorithm based on the channel capacity, the communication transmission rate, and the communication transmission delay to distribute the communication data to the multiple vehicle-mounted nodes; Wherein, the unmanned aerial vehicle is further used for: Set the carrier wave for sending data according to the channel capacity, the communication transmission rate, and the communication transmission delay; Based on the k data distribution algorithm, send the communication data to multiple vehicle-mounted nodes through the carrier wave; Wherein, the unmanned aerial vehicle is further used for: S51. Set the data set to be sent as K, and the data set currently owned by the vehicle node as data u , the number of data distribution stages is a, and let a = 1; S52. Determine data u whether it is equal to K. If data u is equal to K, then go to execute step S55. If data u is not equal to K, then execute step S53; S53. The vehicle-mounted node broadcasts its own data and receives new data from neighboring vehicle-mounted nodes; The in-vehicle node adds the newly received data and updates data u , let a = a + 1, and execute step S52; S55. The communication terminates, outputs the stage number a, and saves the stage number a.

5. The delay-tolerant data distribution system based on a time-varying graph according to claim 4, wherein The delay-constrained time-varying graph data transmission model consists of multiple vehicle-mounted nodes; The multiple vehicle-mounted nodes are further used for: When the target vehicle-mounted node exchanges data with an adjacent node, the target vehicle-mounted node transmits the initial data to the adjacent node, and the target vehicle-mounted node and the adjacent node obtain the communication data and link data; When the target vehicle-mounted node exchanges data with a non-adjacent node, the target vehicle-mounted node transmits the initial data to the non-adjacent node through one or more relay nodes, and the target vehicle-mounted node and the non-adjacent node obtain the communication data and link data.

6. The delay-tolerant data distribution system based on a time-varying graph according to claim 4, wherein The unmanned aerial vehicle is further used for: Establish a transmission rate utility function and a transmission delay utility function, obtain the transmission rate utility value and the transmission delay utility value according to the transmission rate utility function and the transmission delay utility function, and calculate the network utility value according to the transmission rate utility value and the transmission delay utility value.

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