Method and system for calculating vehicle to roadside unit communication delay

Abstract

The application is suitable for the field of Internet of Vehicles communication technology, and provides a communication delay calculation method and system for vehicles and road side units, which comprises the following steps: obtaining traffic flow parameters and road side unit layout parameters of a target section; calculating communication probabilities of a vehicle with an upstream road side unit and a downstream road side unit respectively according to the traffic flow parameters and the road side unit layout parameters; calculating communication delay when the vehicle communicates with the upstream road side unit; calculating communication delay when the vehicle communicates with the downstream road side unit; and determining expected communication delay between the vehicle and the road side unit based on the communication probabilities and the communication delays. The method can effectively improve the accuracy of communication delay estimation in the expressway network environment, and provide accurate and reliable quantitative basis for intelligent expressway road side unit layout optimization, vehicle-road cooperation business and the like.

Description

Technical Field

[0001] This invention belongs to the field of vehicle-to-everything (V2X) communication technology, and particularly relates to a method and system for calculating communication delay between a vehicle and a roadside unit. Background Technology

[0002] In recent years, with the rapid development of technologies such as vehicle-to-everything (V2X) and wireless communication, highway vehicle-road cooperative systems have accelerated from pilot demonstrations to large-scale application. Roadside units (RSUs) are intelligent sensing and communication facilities deployed on the roadside within the V2X system. They can collect road traffic information, issue traffic control commands, and interact with connected vehicles, thereby improving vehicle safety and efficiency and enhancing the performance of the V2X system.

[0003] Communication delay between vehicles and roadside units (LSUs) is a crucial indicator for ensuring the stable operation of vehicle-road cooperative services on highways and supporting intelligent driving decision-making. In a connected environment, vehicles communicate with LSUs through direct transmission and multi-hop relay. When a vehicle is within the communication range of a LSU, they communicate directly; otherwise, they communicate via multi-hop relay. Multi-hop relay includes instant communication and ferry communication. When the headway between two adjacent vehicles is within the vehicle-to-vehicle (V2V) communication radius, instant communication is possible. Once the headway exceeds the V2V communication radius, ferry communication occurs, and the vehicle moves forward until it enters the communication range of the LSU and communicates directly with it. Typically, in real-world traffic scenarios, the dynamic and uncertain nature of traffic flow means that the headway between connected vehicles is often unpredictable. Therefore, communication delay between vehicles and LSUs is affected by factors such as the dynamics and uncertainties of traffic flow. To accurately understand the communication delay between vehicles and roadside units on highways, it is necessary to establish a method for calculating the communication delay between vehicles and roadside units based on factors such as the deployment location of upstream and downstream roadside units, traffic flow, connected vehicle penetration rate, and probability distribution of headway.

[0004] Currently, some research has been conducted both domestically and internationally on communication delays in vehicle-to-everything (V2X) networks. These studies mainly consider factors such as link switching, signal attenuation, and network congestion, and use basic stochastic models such as uniform distribution and Poisson distribution to describe the vehicle distribution pattern. They analyze the average communication time and basic delay of vehicles under a single roadside unit and establish a preliminary delay calculation model. However, the existing research still has the following problems to be solved: (1) Most existing research is based on uniform distribution, Poisson distribution, etc., to make macroscopic estimates of communication delays. It does not adequately consider the dynamics and uncertainties of traffic flow and the penetration rate of connected vehicles, lacks refined probabilistic models, and is difficult to accurately estimate the communication delay between vehicles and roadside units; (2) Existing technologies mostly calculate communication delays for a single roadside unit, and cannot distinguish the differentiated communication states between vehicles and upstream and downstream RSUs, making it difficult to solve the overall expected communication delay between vehicles and roadside units. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for calculating communication delay between vehicles and roadside units, aiming to solve the problems mentioned in the background art.

[0006] This invention is implemented as follows: a method for calculating communication delay between a vehicle and a roadside unit, comprising the following steps:

[0007] Obtain traffic flow parameters and roadside unit layout parameters for the target road segment; the traffic flow parameters include the probability distribution of traffic volume, vehicle speed, connected vehicle penetration rate, and headway of the upstream and downstream road segments; the roadside unit layout parameters include the layout location of the roadside units; the roadside units include upstream roadside units and downstream roadside units;

[0008] Based on traffic flow parameters and roadside unit layout parameters, calculate the communication probability between vehicles and upstream and downstream roadside units respectively;

[0009] Calculate the communication delay when the vehicle communicates with the upstream roadside unit;

[0010] Calculate the communication delay when the vehicle communicates with the downstream roadside unit;

[0011] Based on the communication probability and communication delay, the expected communication delay between the vehicle and the roadside unit is determined.

[0012] Furthermore, the steps for calculating the communication probability between a vehicle and both upstream and downstream roadside units, based on traffic flow parameters and roadside unit deployment parameters, specifically include:

[0013] Based on the probability distribution of the headway between connected vehicles in the upstream section, calculate the probability that connected vehicles in the upstream section can communicate and the expected headway when they can communicate; based on the probability distribution of the headway between connected vehicles in the downstream section, calculate the probability that connected vehicles in the downstream section can communicate and the expected headway when they can communicate.

[0014] Based on the distance from the vehicle to the communication boundary of the upstream roadside unit, the upstream road segment between the communication boundary of the upstream roadside unit and the vehicle is determined. Based on the expected number of headway distances on the upstream road segment, the probability that the vehicle can communicate with the upstream roadside unit in real time is calculated.

[0015] Based on the distance from the vehicle to the communication boundary of the downstream roadside unit, the downstream road segment between the communication boundary of the downstream roadside unit and the vehicle is determined. Based on the expected number of headway distances on the downstream road segment, the probability that the vehicle can communicate with the downstream roadside unit in real time is calculated.

[0016] Based on the distances between the vehicle and the upstream roadside unit and the vehicle and the downstream roadside unit, determine whether the vehicle is closer to the upstream roadside unit or the downstream roadside unit:

[0017] When a vehicle is close to an upstream roadside unit, the probability of communication between the vehicle and the upstream roadside unit is the probability of the vehicle being able to communicate with the upstream roadside unit instantly, calculated above. The probability of communication between the vehicle and the downstream roadside unit is 1 minus the probability of the vehicle being able to communicate with the upstream roadside unit instantly.

[0018] When a vehicle is close to a downstream roadside unit, the probabilities of the vehicle communicating with the upstream roadside unit and with the downstream roadside unit are calculated in three scenarios: the first scenario is that the vehicle can communicate instantly with both the upstream and downstream roadside units; the second scenario is that the vehicle can communicate instantly with the upstream roadside unit but cannot communicate instantly with the downstream roadside unit; and the third scenario is that the vehicle cannot communicate with the upstream roadside unit.

[0019] Furthermore, the method for calculating the probability that a vehicle can communicate instantly with an upstream roadside unit or the probability that a vehicle can communicate instantly with a downstream roadside unit specifically includes:

[0020] The largest set of vehicles that can communicate continuously and instantly on the road segment between the upstream roadside unit communication boundary or the downstream roadside unit communication boundary and the vehicle is called a vehicle cluster; the vehicle cluster can communicate with connected vehicles within the communication range of the upstream roadside unit or the downstream roadside unit.

[0021] Based on the probability distribution of the headway between connected vehicles in the upstream or downstream road segment, calculate the probability that all connected vehicles on the road segment can form a vehicle cluster.

[0022] Based on the length of the vehicle cluster and the remaining road length of the road segment, calculate the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit.

[0023] The probability of all connected vehicles forming a vehicle cluster is multiplied by the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit to obtain the probability that a vehicle can communicate instantly with the upstream or downstream roadside unit.

[0024] Furthermore, the steps for calculating the communication delay when the vehicle communicates with the upstream roadside unit specifically include:

[0025] The vehicle communicates with the upstream roadside unit via real-time communication, specifically including... Real-time communication between vehicles and real-time communication between a single vehicle and a roadside unit; This represents the desired headway on the upstream road segment.

[0026] Get the time of a single vehicle-to-vehicle communication Time of communication with a single vehicle-roadside unit The communication delay when the vehicle communicates with the upstream roadside unit. .

[0027] Furthermore, the steps for calculating the communication delay when the vehicle communicates with the downstream roadside unit specifically include:

[0028] Vehicles communicate with downstream roadside units through instant communication and ferry communication, specifically including vehicle-to-vehicle instant communication, ferry communication and vehicle-to-roadside unit instant communication.

[0029] The distance between the front ends of connected vehicles that is greater than the vehicle-to-vehicle communication radius is used as the ferry communication trigger distance;

[0030] Determine the position of the ferry communication triggering interval in the headway sequence between the vehicle and the downstream roadside unit;

[0031] Based on the vehicle-to-vehicle instantaneous communication time, ferry communication time and vehicle-to-roadside unit instantaneous communication time corresponding to different occurrence locations, calculate the communication delay corresponding to each occurrence location;

[0032] The communication delays corresponding to each location are weighted and summed according to their respective occurrence probabilities to obtain the communication delay when the vehicle communicates with the downstream roadside unit.

[0033] Furthermore, the step of determining the expected communication delay between the vehicle and the roadside unit based on the communication probability and communication delay specifically includes:

[0034] Determine whether the vehicle is within the communication range of the upstream roadside unit or the downstream roadside unit:

[0035] If the vehicle is within the communication range of the upstream or downstream roadside unit, the expected communication delay between the vehicle and the roadside unit is the time of a single vehicle-roadside unit communication.

[0036] If the vehicle is not within the communication range of the upstream and downstream roadside units, the expected communication delay is calculated based on whether the vehicle is closer to the upstream or downstream roadside unit:

[0037] When a vehicle is close to an upstream roadside unit, the communication probability between the vehicle and the upstream roadside unit is multiplied by its corresponding communication delay, and then the communication probability between the vehicle and the downstream roadside unit is multiplied by its corresponding communication delay to obtain the expected communication delay.

[0038] When the vehicle is close to the downstream roadside unit, the communication delay is calculated for three scenarios. The communication delays for each scenario are weighted and summed according to their respective probabilities of occurrence to obtain the expected communication delay.

[0039] Another object of the present invention is to provide a communication delay calculation system between a vehicle and a roadside unit, for implementing the above-mentioned communication delay calculation method between a vehicle and a roadside unit, comprising:

[0040] The information acquisition module is used to acquire traffic flow parameters and roadside unit layout parameters for the target road segment;

[0041] The communication probability calculation module is used to calculate the communication probability between a vehicle and the upstream and downstream roadside units based on traffic flow parameters and roadside unit deployment parameters.

[0042] The upstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the upstream roadside unit;

[0043] The downstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the downstream roadside unit;

[0044] The expected communication delay calculation module is used to determine the expected communication delay between the vehicle and the roadside unit based on the communication probability and communication delay.

[0045] The communication delay calculation method between vehicles and roadside units provided by this invention establishes a refined probabilistic model of vehicle-roadside unit communication based on information such as traffic flow, probability distribution of headway, connected vehicle penetration rate, and deployment location of roadside units. By calculating the communication probability and communication delay between vehicles and upstream and downstream roadside units respectively, the expected communication delay between vehicles and roadside units can be accurately obtained. This method can effectively improve the accuracy of communication delay estimation in highway connected environments, providing accurate and reliable quantitative basis for intelligent highway roadside unit deployment optimization and vehicle-road cooperative services. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the communication delay calculation method between a vehicle and a roadside unit provided in an embodiment of the present invention.

[0047] Figure 2 This diagram illustrates the communication probability and delay between a vehicle and its upstream and downstream roadside units; in the diagram, RSU refers to a roadside unit.

[0048] Figure 3 This is a schematic diagram of the communication range and boundaries of the roadside unit; in the diagram, RSU refers to the roadside unit. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] like Figure 1 As shown, in one embodiment of the present invention, a method for calculating the communication delay between vehicles and roadside units in a highway connected environment is provided, based on the dynamic and uncertain nature of traffic flow on highways and the deployment location of roadside units. This method provides reliable support for highway vehicle-to-everything (V2X) communication delay estimation, roadside unit layout optimization, and vehicle cooperative driving control. The method specifically includes the following steps:

[0051] S1. Obtain traffic flow parameters and roadside unit layout parameters for the target road segment; the traffic flow parameters include the probability distribution of traffic volume, vehicle speed, connected vehicle penetration rate, and headway of the upstream and downstream road segments; the roadside unit layout parameters include the layout location of the roadside units; the roadside units include upstream roadside units and downstream roadside units.

[0052] S2. Based on traffic flow parameters and roadside unit layout parameters, calculate the communication probability between the vehicle and the upstream and downstream roadside units respectively.

[0053] S3. Calculate the communication delay when the vehicle communicates with the upstream roadside unit;

[0054] S4. Calculate the communication delay when the vehicle communicates with the downstream roadside unit;

[0055] S5. Based on the communication probability and communication delay, determine the expected communication delay between the vehicle and the roadside unit.

[0056] In practical applications, communication between vehicles and roadside units is affected by traffic flow. Considering the dynamic and uncertain nature of traffic flow, for a vehicle at any location x and any time t on a highway, it sometimes communicates with upstream roadside units and sometimes with downstream roadside units, such as... Figure 2 As shown. Considering the communication efficiency between vehicles and roadside units (RSUs), for both upstream and downstream RSUs, vehicles will choose to communicate with the RSU with the lower communication delay. Specifically, for a vehicle at any location x and any time t on the highway, the probability of communication between the vehicle and the upstream / downstream RSU is calculated based on the distance between the vehicle and the upstream / downstream RSU, the traffic flow on the upstream / downstream road segments, the penetration rate of connected vehicles, and the probability distribution of headway. and the communication probability between vehicles and downstream roadside units Then, the communication delay when the vehicle communicates with the upstream roadside unit is calculated. And communication delays when vehicles communicate with downstream roadside units. When a vehicle is within the communication range of an upstream / downstream roadside unit, it can communicate directly with the roadside unit, and the communication delay is the time of a single vehicle-roadside unit communication. Otherwise, the expected communication delay between the vehicle and the roadside unit will be calculated based on the communication probability and communication delay between the vehicle and the upstream / downstream roadside unit. ,as follows:

[0057] .

[0058] The method provided in this invention can improve the accuracy of communication delay calculation results between highway vehicles and roadside units, overcoming the estimation bias caused by existing models ignoring the dynamics and randomness of traffic flow and the differences in the proportion of connected vehicles. Based on the high-precision quantitative results of expected communication delay, it can guide the scientific optimization of roadside unit locations and spacing, reducing communication blind spots and latency exceeding standards caused by redundant or insufficient hardware deployment. Furthermore, it can provide reliable data benchmarks for upper-level services such as vehicle-road cooperative control, autonomous driving cooperative scheduling, and intelligent highway management, ensuring that the latency parameters of various connected services are designed to fit actual road operating conditions, and facilitating the efficient and stable implementation of intelligent highway vehicle-road cooperative systems.

[0059] In a preferred embodiment of the present invention, step S2 specifically includes:

[0060] S21. Based on the probability distribution of the headway between connected vehicles in the upstream section, calculate the probability that connected vehicles in the upstream section can communicate and the expected headway when they can communicate; based on the probability distribution of the headway between connected vehicles in the downstream section, calculate the probability that connected vehicles in the downstream section can communicate and the expected headway when they can communicate.

[0061] S22. Based on the distance from the vehicle to the communication boundary of the upstream roadside unit, determine the upstream road segment between the communication boundary of the upstream roadside unit and the vehicle. Based on the expected headway on the upstream road segment, calculate the probability that the vehicle can communicate with the upstream roadside unit in real time.

[0062] S23. Based on the distance from the vehicle to the communication boundary of the downstream roadside unit, determine the downstream road segment between the communication boundary of the downstream roadside unit and the vehicle. Based on the expected headway on the downstream road segment, calculate the probability that the vehicle can communicate with the downstream roadside unit in real time.

[0063] S24. Based on the distance between the vehicle and the upstream roadside unit and the distance between the vehicle and the downstream roadside unit, determine whether the vehicle is closer to the upstream roadside unit or the downstream roadside unit:

[0064] When a vehicle is close to an upstream roadside unit, the probability of communication between the vehicle and the upstream roadside unit is the probability of the vehicle being able to communicate with the upstream roadside unit instantly, calculated above. The probability of communication between the vehicle and the downstream roadside unit is 1 minus the probability of the vehicle being able to communicate with the upstream roadside unit instantly.

[0065] When a vehicle is close to a downstream roadside unit, the probabilities of the vehicle communicating with the upstream roadside unit and with the downstream roadside unit are calculated in three scenarios: the first scenario is that the vehicle can communicate instantly with both the upstream and downstream roadside units; the second scenario is that the vehicle can communicate instantly with the upstream roadside unit but cannot communicate instantly with the downstream roadside unit; and the third scenario is that the vehicle cannot communicate with the upstream roadside unit.

[0066] The calculation method for the probability that a vehicle can communicate instantly with an upstream roadside unit or the probability that a vehicle can communicate instantly with a downstream roadside unit specifically includes:

[0067] The largest set of vehicles that can communicate continuously and instantly on the road segment between the upstream roadside unit communication boundary or the downstream roadside unit communication boundary and the vehicle is called a vehicle cluster; the vehicle cluster can communicate with connected vehicles within the communication range of the upstream roadside unit or the downstream roadside unit.

[0068] Based on the probability distribution of the headway between connected vehicles in the upstream or downstream road segment, calculate the probability that all connected vehicles on the road segment can form a vehicle cluster.

[0069] Based on the length of the vehicle cluster and the remaining road length of the road segment, calculate the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit.

[0070] The probability of all connected vehicles forming a vehicle cluster is multiplied by the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit to obtain the probability that a vehicle can communicate instantly with the upstream or downstream roadside unit.

[0071] In practical applications, the specific implementation method of step S2 above is as follows:

[0072] For a vehicle at any location x and any time t on a highway, it can only communicate with upstream roadside units via instant communication, while it can communicate with downstream roadside units via both instant communication and ferry communication. Let... , These represent the traffic flow on the upstream and downstream road sections, respectively. , Indicates the speed of vehicles on the upstream and downstream sections of the road. , This indicates the penetration rate of connected vehicles in upstream and downstream road sections, where 's' represents the headway between connected vehicles. , Let represent the probability distribution of the headway between connected vehicles on the upstream and downstream road sections. , The definition is as follows:

[0073] ;

[0074] .

[0075] make Let represent the vehicle-to-vehicle (V2V) communication radius. Then, the probability that vehicles connected to the internet on the upstream road segment can communicate (i.e., the probability that the distance between vehicle heads does not exceed the V2V communication radius) is: The probability that vehicles connected to the internet in the downstream section can communicate is The desired headway for vehicles to communicate with each other when connected to the internet on the upstream section is: The desired headway for vehicles to communicate with each other on the downstream road section is... .make , This indicates the distance from the vehicle to the communication boundary of the upstream / downstream roadside unit. , Indicates the corresponding upstream and downstream road sections, such as Figure 3 As shown, then , The expected number of front-end distances are respectively , .

[0076] The largest set of vehicles capable of continuous real-time communication on the current road segment is called a vehicle cluster. Specifically, for an upstream roadside unit, vehicles can only communicate with that roadside unit via real-time communication. All vehicles on the road form a vehicle cluster, and this cluster can communicate with vehicles within the communication range of the upstream roadside unit. Based on the probability distribution of the headway between connected vehicles, The probability that all vehicles can form a vehicle cluster is The length of the vehicle cluster is The remaining road length is The probability that this vehicle cluster can communicate with vehicles within the communication range of the upstream roadside unit is that the headway is greater than 1. and less than The probability, i.e. The probability that a vehicle can communicate instantly with the upstream roadside unit is then... Similarly, the probability that a vehicle can communicate instantly with downstream roadside units can be obtained as follows: Considering communication efficiency, for both upstream and downstream roadside units, vehicles will choose to communicate with the roadside unit that has the least communication delay. , This indicates the location of the upstream and downstream roadside units. The following discussion will cover the communication probability between vehicles and the upstream and downstream roadside units under different scenarios.

[0077] When the vehicle is close to the upstream roadside unit (i.e.) ):

[0078] For the upstream roadside unit, the vehicle can only communicate instantly with that unit. Considering the vehicle's proximity to the upstream roadside unit and the low latency of instant communication, the vehicle will prioritize communicating with the upstream roadside unit. Therefore, the probability of communication between the vehicle and the upstream roadside unit is... The communication probability with downstream roadside units is .

[0079] When the vehicle is close to the downstream roadside unit (i.e.) The following three scenarios are discussed, and the probabilities of different scenarios and the communication probability between the vehicle and the roadside unit are shown in Table 1.

[0080] Scenario 1: The vehicle can communicate instantly with both upstream and downstream roadside units. In this case, because the vehicle is closer to the downstream roadside unit, it chooses to communicate with the downstream roadside unit.

[0081] Scenario 2: The vehicle can communicate instantly with the upstream roadside unit but cannot communicate instantly with the downstream roadside unit. Considering the short time required for instant communication, the vehicle chooses to communicate with the upstream roadside unit.

[0082] Scenario 3: The vehicle cannot communicate with the upstream roadside unit. In this case, the vehicle can only communicate with the downstream roadside unit.

[0083] Table 1. Probability of different scenarios and communication probability between vehicles and roadside units

[0084]

[0085] In a preferred embodiment of the present invention, step S3 specifically includes:

[0086] The vehicle communicates with the upstream roadside unit via real-time communication, specifically including... Real-time communication between vehicles and real-time communication between a single vehicle and a roadside unit; The desired headway distance on the upstream road segment; the time of a single vehicle-to-vehicle communication. Time of communication with a single vehicle-roadside unit The communication delay when the vehicle communicates with the upstream roadside unit. .

[0087] In a preferred embodiment of the present invention, step S4 specifically includes:

[0088] S41. Vehicles communicate with downstream roadside units through instant communication and ferry communication, specifically including vehicle-to-vehicle instant communication, ferry communication and vehicle-to-roadside unit instant communication.

[0089] S42. Obtain the distance between the front ends of the connected vehicles that is greater than the vehicle-to-vehicle communication radius as the ferry communication trigger distance;

[0090] S43. Determine the position of the ferry communication triggering interval in the headway sequence between the vehicle and the downstream roadside unit;

[0091] S44. Calculate the communication delay corresponding to each location based on the vehicle-to-vehicle instantaneous communication time, ferry communication time, and vehicle-to-roadside unit instantaneous communication time at different locations.

[0092] S45. The communication delays corresponding to each occurrence location are weighted and summed according to their respective occurrence probabilities to obtain the communication delay when the vehicle communicates with the downstream roadside unit.

[0093] In practical applications, the specific implementation method of step S4 above is as follows:

[0094] Vehicles can communicate with downstream roadside units via instant messaging and ferry communication. Specifically, firstly, vehicles within the downstream vehicle cluster communicate instantly; when a signal greater than [a certain value] occurs... After determining the headway, ferry communication is initiated. The vehicle then continues to travel to the communication range of the downstream roadside unit and establishes real-time communication with it. Therefore, the communication delay between the vehicle and the downstream roadside unit includes vehicle-to-vehicle real-time communication time, ferry communication time, and vehicle-to-roadside unit real-time communication time. The real-time communication and ferry communication times are determined by the headway. The location determines its appearance. (When the distance between the front of the vehicle...) When it appears at the k-th headway, the probability of it occurring is: At this time, the vehicle-to-vehicle real-time communication time is The ferry communication time is The real-time communication time between the vehicle and the roadside unit is Table 2 shows the distance between the front ends of the vehicles. The probability of appearing in different locations and the communication time; among which, Indicates the distance between the front of the vehicle Appears at the k-th headway. This represents the corresponding probability; Indicates the time of real-time vehicle-to-vehicle communication. Indicates ferry communication time. Indicates the real-time communication time between the vehicle and the roadside unit. This indicates the corresponding communication delay.

[0095] Table 2. Vehicle frontage distance Probability and communication time when appearing in different locations

[0096]

[0097] Based on the probability of different scenarios and their corresponding communication delays, the expected communication delay between the vehicle and the downstream roadside unit can be calculated as follows:

[0098] .

[0099] In a preferred embodiment of the present invention, step S5 specifically includes:

[0100] S51. Determine whether the vehicle is within the communication range of the upstream roadside unit or the downstream roadside unit:

[0101] S52. If the vehicle is within the communication range of the upstream or downstream roadside unit, the expected communication delay between the vehicle and the roadside unit is the time of a single vehicle-roadside unit communication.

[0102] S53. If the vehicle is not within the communication range of the upstream and downstream roadside units, the expected communication delay shall be calculated based on whether the vehicle is closer to the upstream or downstream roadside unit:

[0103] When a vehicle is close to an upstream roadside unit, the communication probability between the vehicle and the upstream roadside unit is multiplied by its corresponding communication delay, and then the communication probability between the vehicle and the downstream roadside unit is multiplied by its corresponding communication delay to obtain the expected communication delay.

[0104] When the vehicle is close to the downstream roadside unit, the communication delay is calculated for three scenarios. The communication delays for each scenario are weighted and summed according to their respective probabilities of occurrence to obtain the expected communication delay.

[0105] In practical applications, the specific implementation method of step S5 above is as follows:

[0106] When a vehicle is within the communication range of the upstream and downstream roadside units, it can communicate directly with the upstream and downstream roadside units. The expected communication delay is the time of a single vehicle-roadside unit communication, i.e. Otherwise, the expected communication delay between the vehicle and the roadside unit will be calculated based on the communication probability and communication delay between the vehicle and the upstream and downstream roadside units under different circumstances.

[0107] Specifically, when the vehicle is close to the upstream roadside unit (i.e. ):

[0108] Based on the communication probability and communication delay between the vehicle and the upstream and downstream roadside units, the expected communication delay between the vehicle and the roadside units can be obtained as follows:

[0109] ;

[0110] When the vehicle is close to the downstream roadside unit (i.e.) The following three scenarios are discussed according to the above method, and the expected communication delay between the vehicle and the roadside unit is given under different scenarios.

[0111] Scenario 1: The vehicle can communicate instantly with both upstream and downstream roadside units. In this case, because the vehicle is closer to the downstream roadside unit, it chooses to communicate with that unit. Therefore, the communication delay in Scenario 1 is:

[0112] .

[0113] Scenario 2: The vehicle can communicate instantly with the upstream roadside unit but cannot communicate instantly with the downstream roadside unit. Considering the short time required for instant communication, the vehicle chooses to communicate with the upstream roadside unit. Therefore, the communication delay in Scenario 2 is:

[0114] .

[0115] Scenario 3: The vehicle cannot communicate with the upstream roadside unit. In this case, the vehicle can only communicate with the downstream roadside unit. Therefore, the communication delay in Scenario 3 is:

[0116] .

[0117] Combining the probabilities of the above different scenarios If m=1,2,3, then the expected communication delay between the vehicle and the roadside unit is:

[0118] .

[0119] In another embodiment of the present invention, a communication delay calculation system for vehicles and roadside units is also provided, for implementing the above-described communication delay calculation method for vehicles and roadside units, including:

[0120] The information acquisition module is used to acquire traffic flow parameters and roadside unit layout parameters for the target road segment;

[0121] The communication probability calculation module is used to calculate the communication probability between a vehicle and the upstream and downstream roadside units based on traffic flow parameters and roadside unit deployment parameters.

[0122] The upstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the upstream roadside unit;

[0123] The downstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the downstream roadside unit;

[0124] The expected communication delay calculation module is used to determine the expected communication delay between the vehicle and the roadside unit based on the communication probability and communication delay.

[0125] It should be understood that although the steps in the flowcharts of the embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in each embodiment may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0126] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods.

[0127] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for calculating communication delay between a vehicle and a roadside unit, characterized in that, Includes the following steps: Obtain traffic flow parameters and roadside unit layout parameters for the target road segment; the traffic flow parameters include the probability distribution of traffic volume, vehicle speed, connected vehicle penetration rate, and headway of the upstream and downstream road segments; the roadside unit layout parameters include the layout location of the roadside units; the roadside units include upstream roadside units and downstream roadside units; Based on traffic flow parameters and roadside unit layout parameters, calculate the communication probability between vehicles and upstream and downstream roadside units respectively; Calculate the communication delay when the vehicle communicates with the upstream roadside unit; Calculate the communication delay when the vehicle communicates with the downstream roadside unit; Based on the communication probability and communication delay, the expected communication delay between the vehicle and the roadside unit is determined; The steps for calculating the communication probability between a vehicle and both upstream and downstream roadside units, based on traffic flow parameters and roadside unit deployment parameters, specifically include: Based on the probability distribution of the headway between connected vehicles in the upstream section, calculate the probability that connected vehicles in the upstream section can communicate and the expected headway when they can communicate; based on the probability distribution of the headway between connected vehicles in the downstream section, calculate the probability that connected vehicles in the downstream section can communicate and the expected headway when they can communicate. Based on the distance from the vehicle to the communication boundary of the upstream roadside unit, the upstream road segment between the communication boundary of the upstream roadside unit and the vehicle is determined. Based on the expected number of headway distances on the upstream road segment, the probability that the vehicle can communicate with the upstream roadside unit in real time is calculated. Based on the distance from the vehicle to the communication boundary of the downstream roadside unit, the downstream road segment between the communication boundary of the downstream roadside unit and the vehicle is determined. Based on the expected number of headway distances on the downstream road segment, the probability that the vehicle can communicate with the downstream roadside unit in real time is calculated. Based on the distances between the vehicle and the upstream roadside unit and the vehicle and the downstream roadside unit, determine whether the vehicle is closer to the upstream roadside unit or the downstream roadside unit: When a vehicle is close to an upstream roadside unit, the probability of communication between the vehicle and the upstream roadside unit is the probability of the vehicle being able to communicate with the upstream roadside unit instantly, calculated above. The probability of communication between the vehicle and the downstream roadside unit is 1 minus the probability of the vehicle being able to communicate with the upstream roadside unit instantly. When the vehicle is close to the downstream roadside unit, calculate the probability of the vehicle communicating with the upstream roadside unit and the probability of communicating with the downstream roadside unit in three scenarios: the first scenario is that the vehicle can communicate instantly with both the upstream and downstream roadside units; the second scenario is that the vehicle can communicate instantly with the upstream roadside unit but cannot communicate instantly with the downstream roadside unit; and the third scenario is that the vehicle cannot communicate with the upstream roadside unit. The steps for determining the expected communication delay between the vehicle and the roadside unit based on the communication probability and communication delay specifically include: Determine whether the vehicle is within the communication range of the upstream roadside unit or the downstream roadside unit: If the vehicle is within the communication range of the upstream or downstream roadside unit, the expected communication delay between the vehicle and the roadside unit is the time of a single vehicle-roadside unit communication. If the vehicle is not within the communication range of the upstream and downstream roadside units, the expected communication delay is calculated based on whether the vehicle is closer to the upstream or downstream roadside unit: When a vehicle is close to an upstream roadside unit, the communication probability between the vehicle and the upstream roadside unit is multiplied by its corresponding communication delay, and then the communication probability between the vehicle and the downstream roadside unit is multiplied by its corresponding communication delay to obtain the expected communication delay. When the vehicle is close to the downstream roadside unit, the communication delay is calculated for three scenarios. The communication delays for each scenario are weighted and summed according to their respective probabilities of occurrence to obtain the expected communication delay.

2. The method for calculating communication delay between a vehicle and a roadside unit according to claim 1, characterized in that, The calculation method for the probability that a vehicle can communicate instantly with an upstream roadside unit or the probability that a vehicle can communicate instantly with a downstream roadside unit specifically includes: The largest set of vehicles that can communicate continuously and instantly on the road segment between the upstream roadside unit communication boundary or the downstream roadside unit communication boundary and the vehicle is called a vehicle cluster; the vehicle cluster can communicate with connected vehicles within the communication range of the upstream roadside unit or the downstream roadside unit. Based on the probability distribution of the headway between connected vehicles in the upstream or downstream road segment, calculate the probability that all connected vehicles on the road segment can form a vehicle cluster. Based on the length of the vehicle cluster and the remaining road length of the road segment, calculate the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit. The probability of all connected vehicles forming a vehicle cluster is multiplied by the probability that the vehicle cluster can communicate with vehicles within the communication range of the upstream or downstream roadside unit to obtain the probability that a vehicle can communicate instantly with the upstream or downstream roadside unit.

3. The method for calculating communication delay between a vehicle and a roadside unit according to claim 1, characterized in that, The steps for calculating communication delays when a vehicle communicates with an upstream roadside unit specifically include: The vehicle communicates with the upstream roadside unit via real-time communication, specifically including... Real-time communication between vehicles and real-time communication between a single vehicle and a roadside unit; This represents the desired headway on the upstream road segment. Get the time of a single vehicle-to-vehicle communication Time of communication with a single vehicle-roadside unit The communication delay when the vehicle communicates with the upstream roadside unit. .

4. The method for calculating communication delay between a vehicle and a roadside unit according to claim 1, characterized in that, The steps for calculating communication delays when a vehicle communicates with downstream roadside units specifically include: Vehicles communicate with downstream roadside units through instant communication and ferry communication, specifically including vehicle-to-vehicle instant communication, ferry communication and vehicle-to-roadside unit instant communication. The distance between the front ends of connected vehicles that is greater than the vehicle-to-vehicle communication radius is used as the ferry communication trigger distance; Determine the position of the ferry communication triggering interval in the headway sequence between the vehicle and the downstream roadside unit; Based on the vehicle-to-vehicle instantaneous communication time, ferry communication time and vehicle-to-roadside unit instantaneous communication time corresponding to different occurrence locations, calculate the communication delay corresponding to each occurrence location; The communication delays corresponding to each location are weighted and summed according to their respective occurrence probabilities to obtain the communication delay when the vehicle communicates with the downstream roadside unit.

5. A communication delay calculation system between a vehicle and a roadside unit, used to implement the communication delay calculation method between a vehicle and a roadside unit as described in any one of claims 1-4, characterized in that, include: The information acquisition module is used to acquire traffic flow parameters and roadside unit layout parameters for the target road segment; The communication probability calculation module is used to calculate the communication probability between a vehicle and the upstream and downstream roadside units based on traffic flow parameters and roadside unit deployment parameters. The upstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the upstream roadside unit; The downstream communication delay calculation module is used to calculate the communication delay when the vehicle communicates with the downstream roadside unit; The expected communication delay calculation module is used to determine the expected communication delay between the vehicle and the roadside unit based on the communication probability and communication delay.

Images