A link transmission performance analysis method and device and a storage medium

Abstract

The application relates to the technical field of Internet of Vehicles, and discloses a link transmission performance analysis method, device and storage medium, the method comprises the following steps: acquiring the basic delay and the basic packet loss rate of a current candidate link in a target section under a preset traffic state, and collecting real-time traffic condition parameters of the target section at the current time; calculating a traffic condition influence index according to the real-time traffic condition parameters, and correcting the basic delay based on the traffic condition influence index to obtain a delay estimation value; acquiring a measured packet loss rate of the current candidate link, and calculating a transmission performance score of the current candidate link according to the basic delay, the basic packet loss rate, the delay estimation value and the measured packet loss rate. The application solves the problem of insufficient measurement accuracy of the existing vehicle-road communication link transmission performance evaluation method.

Description

Technical Field

[0001] This invention relates to the field of vehicle networking technology, specifically to a link transmission performance analysis method, device, and storage medium. Background Technology

[0002] With the rapid development of intelligent connected vehicles and vehicle-road-cloud integration technologies, Cellular Vehicle-to-Everything (C-V2X) has become the mainstream communication standard supporting vehicle-road cooperative perception and information sharing. In complex traffic environments with mixed traffic of people and vehicles, such as urban arterial roads and intersections, multiple types of traffic participants coexist. It is necessary to maintain multiple transmission channels under both PC5 direct connection and Uu cellular communication standards in parallel to achieve low-latency and reliable interaction between roadside perception information, cloud-based decision commands, and vehicle status data. Currently, relevant standards and engineering practices generally adopt an end-to-end latency calculation method based on the difference between send and receive timestamps. This method calculates the overall transmission latency by recording the message sending time and the terminal receiving time, and sets a fixed latency threshold based on the application scenario to evaluate link performance. This method has been widely used in scenarios such as testing of vehicle-road cooperative roadside perception systems and sharing perception data.

[0003] However, existing latency measurement methods do not incorporate the dynamic changes in road traffic conditions into the model. When real-time traffic parameters such as vehicle speed and the number of conflicting targets at intersections fluctuate significantly, the measured results deviate considerably from the actual communication latency, failing to accurately reflect the actual transmission performance of the link under the current operating environment. This deviation is particularly pronounced in typical scenarios such as peak congestion and tunnels, directly affecting the accuracy of the timestamps of the sensing data and the reliability of the vehicle-side fusion sensing results. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a link transmission performance analysis method, apparatus and storage medium to solve the problem of insufficient measurement accuracy of existing vehicle-to-everything (V2X) link transmission performance evaluation methods.

[0005] In a first aspect, embodiments of the present invention provide a link transmission performance analysis method, the method comprising: Obtain the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and collect the real-time traffic condition parameters of the target road segment at the current moment; The traffic condition impact index is calculated based on the real-time traffic condition parameters, and the base delay is corrected based on the traffic condition impact index to obtain the delay estimate. Obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, the base packet loss rate, the delay estimate, and the measured packet loss rate.

[0006] Furthermore, obtaining the basic latency and basic packet loss rate of the current candidate link in the target road segment under a preset traffic condition includes: Collect latency samples and packet loss rate samples of the current candidate link in a single link communication; Identify a stable traffic state on the target road segment as the preset traffic state, and record the target traffic condition parameters corresponding to the preset traffic state; Based on the target traffic condition parameters, candidate delay samples and candidate packet loss rate samples are selected from the delay samples and the packet loss rate samples, respectively. The median of the candidate delay samples is used as the base delay, and the median of the candidate packet loss rate samples is used as the base packet loss rate.

[0007] Furthermore, the traffic condition parameters include at least one of the following parameters: vehicle operating speed, number of conflicting targets, and business sensitivity; The calculation of the traffic condition impact index based on the real-time traffic condition parameters includes: The first vehicle speed in the real-time traffic condition parameters is compared with the second vehicle speed in the target traffic condition parameters, and normalized using a preset speed mapping function to obtain a normalized vehicle speed value; and / or, The number of first conflict targets in the real-time traffic condition parameters is compared with the number of second conflict targets in the target traffic condition parameters, and normalized using a preset conflict target number mapping function to obtain a normalized value for the number of conflict targets; and / or, The first business sensitivity in the real-time traffic condition parameters is compared with the second business sensitivity in the target traffic condition parameters, and normalized by a preset business sensitivity mapping function to obtain a normalized business sensitivity value. The traffic condition impact index is obtained by fusing the normalized values ​​of the vehicle speed and / or the normalized values ​​of the number of conflicting targets and / or the normalized values ​​of the business sensitivity according to the preset impact weights corresponding to the normalized values ​​of the normalized values ​​of each parameter.

[0008] Furthermore, the step of correcting the base delay based on the traffic condition impact index to obtain the delay estimate includes: The traffic condition impact index is added to a preset benchmark value to obtain the traffic condition correction coefficient. The estimated time delay is obtained by multiplying the base time delay by the traffic condition correction factor.

[0009] Furthermore, the step of calculating the transmission performance score of the current candidate link based on the base latency, the base packet loss rate, the latency estimate, and the measured packet loss rate includes: Get the current allowed latency and the current allowed packet loss rate, and get the allowed latency and the allowed packet loss rate under the preset state; Based on the base latency and the allowed latency under the preset state, the latency occupancy ratio under the preset state is determined, and based on the latency estimate and the current allowed latency, the current latency occupancy ratio is determined. Based on the base packet loss rate and the allowed packet loss rate under the preset state, determine the packet loss rate occupancy ratio under the preset state, and based on the measured packet loss rate and the current allowed packet loss rate, determine the current packet loss rate occupancy ratio. The transmission performance score of the current candidate link is calculated based on the preset state delay occupancy ratio, the current delay occupancy ratio, the preset state packet loss rate occupancy ratio, the current packet loss rate occupancy ratio, and the preset scoring weight.

[0010] Furthermore, after calculating the transmission performance score of the current candidate link, the method further includes: The transmission performance score is compared with a preset valid threshold and a preset invalid threshold, wherein the preset invalid threshold is less than the preset valid threshold; If the transmission performance score is greater than or equal to the preset valid threshold, the current candidate link is determined to be a fully valid link; or, if the transmission performance score is greater than or equal to the preset invalid threshold and less than the preset valid threshold, the current candidate link is determined to be a conditionally available link; or, if the transmission performance score is less than the preset invalid threshold, the current candidate link is determined to be a failed link.

[0011] Furthermore, the method also includes: When there are multiple fully effective links, the current latency occupancy ratio of each fully effective link is compared, and the fully effective link with the smallest current latency occupancy ratio is selected as the main transmission link. The communication middleware issues a channel switching command to configure the fully effective link as the first priority, the conditionally available link as the second priority, and the failed link as the third priority. Wherein, the first priority is to allocate the current business awareness message according to the first allocation weight, the second priority is to allocate the current business awareness message according to the second allocation weight, and the third priority is to stop allocating the current business awareness message, wherein the first allocation weight is greater than the second allocation weight.

[0012] Furthermore, the method also includes: Obtain measured data during the link communication process in the target road segment; Based on the measured data, update the base latency and base packet loss rate under the preset traffic conditions, and / or update the preset impact weights used to calculate the traffic condition impact index, and / or update the preset scoring weights used to calculate the transmission performance score, and / or update the preset thresholds used to determine the link effectiveness.

[0013] Secondly, embodiments of the present invention provide a link transmission performance analysis apparatus, the apparatus comprising: The acquisition module is used to acquire the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and to collect the real-time traffic condition parameters of the target road segment at the current moment. The correction module is used to calculate the traffic condition impact index based on the real-time traffic condition parameters, and to correct the base delay based on the traffic condition impact index to obtain the delay estimate. The calculation module is used to obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, the base packet loss rate, the delay estimate and the measured packet loss rate.

[0014] Thirdly, embodiments of the present invention provide a computer device, including: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method described in the first aspect or any corresponding embodiment thereof.

[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer instructions that cause a computer to perform the method described in the first aspect or any of its corresponding embodiments.

[0016] The method provided in this application has the following beneficial effects: The method provided in this application establishes a quantifiable and comparable benchmark for dynamic evaluation of link performance by acquiring the baseline latency and baseline packet loss rate under preset traffic conditions as a reference, and simultaneously collecting real-time traffic condition parameters. This enables subsequent analysis to anchor the inherent transmission characteristics of the link under typical conditions, eliminating fixed deviations caused by differences in road segments and hardware deployments. By calculating a traffic condition impact index based on real-time traffic condition parameters, the method quantifies the degree of deviation of the current traffic state relative to the preset state, and corrects the baseline latency based on this index to obtain a latency estimate. This allows the latency calculation results to adaptively match changes in the dynamic traffic environment, such as current vehicle speed and the number of conflicting targets, significantly reducing the deviation between the calculated value and the actual transmission latency. By acquiring the measured packet loss rate of the current candidate link, and comprehensively calculating the transmission performance score by combining the baseline latency, baseline packet loss rate, latency estimate, and measured packet loss rate, the method unifies and quantifies the link transmission quality of the two dimensions of latency and packet loss rate into a comparable score, enabling objective ranking and direct comparison of the comprehensive transmission performance of different links under the current conditions. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the link transmission performance analysis method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the delay estimation calculation process according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the link transmission performance scoring and validity determination process according to an embodiment of the present invention; Figure 4 This is a schematic flowchart of a method for calculating vehicle-road-cloud multi-link communication latency and determining link validity based on integrated traffic conditions, according to an embodiment of the present invention. Figure 5 This is a structural block diagram of a link transmission performance analysis device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] According to embodiments of the present invention, a link transmission performance analysis method, apparatus, and storage medium are provided. It should be noted that the steps shown in the flowcharts in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowcharts, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0021] This embodiment provides a method for analyzing link transmission performance. Figure 1 This is a flowchart of a link transmission performance analysis method according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps: Step S101: Obtain the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and collect the real-time traffic condition parameters of the target road segment at the current moment.

[0022] In this embodiment of the application, obtaining the basic latency and basic packet loss rate of the current candidate link in the target road segment under a preset traffic condition includes: Step A1: Collect latency samples and packet loss rate samples of the current candidate link in a single link communication.

[0023] Specifically, the current candidate link refers to a specific transmission channel that provides communication services for vehicle-road-cloud services on the target road segment within the current evaluation period, covering types such as V2V direct short links or I2C2V cross-network long links; a single link communication refers to a complete transmission process from the sending end sending a sensing message to the receiving end successfully receiving the message; the latency sample refers to the end-to-end total latency value obtained by summing five components in a single link communication: physical layer transmission latency, MAC layer scheduling latency, protocol stack encapsulation and parsing latency, queuing latency, and edge or cloud sensing processing latency; the packet loss rate sample refers to the proportion of messages that fail to reach the receiving end within a single link communication or a short observation window to the total number of messages sent.

[0024] During data collection, the physical layer transmission latency, MAC scheduling latency, and protocol stack encapsulation and parsing latency are obtained by reading the underlying communication driver and protocol stack logs of the roadside RSU and vehicle-mounted OBU. Simultaneously, the queuing latency is calculated based on the current concurrent sensing message volume per second and by calling the M / M / 1 queuing model. Furthermore, the edge or cloud sensing processing latency is calculated based on the number of intersection targets sensed by the roadside radar and cameras. The sum of these five components yields a single latency sample, as shown in the following formula:

[0025] in, For the target road section and candidate links Communication delay samples; This refers to the physical layer transmission delay. This is for MAC layer scheduling latency; To reduce latency in edge or cloud-based sensing and processing; Encapsulate parsing latency for the protocol stack; This is to delay queuing time.

[0026] The packet loss rate sample P is calculated by comparing the total number of messages sent by the sender and the total number of messages actually received by the receiver within the same time period, and then using the ratio of the difference between the two to the total number of messages sent.

[0027] Step A2: Identify the stable traffic conditions on the target road segment as the preset traffic conditions, and record the target traffic condition parameters corresponding to the preset traffic conditions.

[0028] Specifically, the target road segment refers to the specific road section where communication latency assessment is currently performed, such as an intersection in a city or a continuous road segment. A stable traffic state refers to a typical traffic scenario that occurs frequently in long-term observations on the target road segment, with small fluctuations in traffic flow parameters and relatively stable communication latency and packet loss rate. This state is taken as the preset traffic state. The target traffic condition parameters corresponding to the preset traffic state include the second vehicle operating speed, the second number of conflicting targets, and the second service sensitivity. The second vehicle operating speed refers to the normal driving speed of vehicles on the target road segment under the preset traffic state. The second number of conflicting targets refers to the total number of targets such as pedestrians, non-motorized vehicles, and other vehicles that need to be perceived and fused within the intersection or road segment under the preset traffic state. The second service sensitivity refers to the quantitative value of resource allocation and real-time requirements corresponding to the current service type under the preset traffic state.

[0029] When identifying the preset traffic conditions, the system performs statistical analysis on the massive delay samples and packet loss rate samples collected over a long period of time for the target road segment. The mean and variance of the samples under different traffic conditions are calculated respectively. The combination of conditions that appears most frequently and whose delay standard deviation is lower than the preset threshold is selected as the preset traffic conditions with stable operation. At the same time, the typical operating parameters corresponding to this condition are recorded.

[0030] Step A3: Based on the target traffic condition parameters, candidate delay samples and candidate packet loss rate samples are selected from the delay samples and packet loss rate samples, respectively.

[0031] Specifically, candidate delay samples are those delay samples selected from all delay samples collected, whose corresponding traffic conditions at that time match the target traffic condition parameters of the preset traffic state. Similarly, candidate packet loss rate samples are those corresponding packet loss rate samples selected from all packet loss rate samples according to the same matching conditions. Matching means that the deviations between the real-time vehicle speed, number of conflicting targets, and business sensitivity at the time of sample collection and the second vehicle speed, second number of conflicting targets, and second business sensitivity recorded under the preset traffic state are all controlled within a preset tolerance range.

[0032] During the screening process, each collected delay sample and its corresponding traffic condition parameters at the collection time are traversed. It is determined whether the traffic condition at that time matches the target traffic condition parameters of the preset traffic state. Only delay samples that meet all matching conditions are retained as candidate delay samples. The same screening logic is applied to the packet loss rate sample set to obtain candidate packet loss rate samples.

[0033] Step A4: Use the median of the candidate delay samples as the base delay, and the median of the candidate packet loss rate samples as the base packet loss rate.

[0034] Specifically, the baseline latency refers to the typical end-to-end total latency required for a candidate link to complete a single communication under preset traffic conditions, used to characterize the baseline communication time of the link under stable operating conditions; the baseline packet loss rate refers to the typical message loss ratio of a candidate link under preset traffic conditions, used to characterize the baseline transmission reliability of the link under stable operating conditions. Both are measured using the median because the median is insensitive to extreme outliers in the data and can more robustly reflect the typical level of concentrated distribution under preset traffic conditions.

[0035] In implementation, all samples in the selected candidate latency sample set are sorted in ascending order of value, and the sample value in the middle position after sorting is taken as the base latency; if the total number of candidate latency samples is even, the arithmetic mean of the two middle sample values ​​is taken as the base latency. The same median operation is performed on the candidate packet loss rate sample set to obtain the base packet loss rate. The specific calculation formula is as follows:

[0036]

[0037] in, The base delay of the current candidate link l on the target road segment r; Median{} is the median operator; This is a sample of the communication delay of the current candidate link l on the target road segment r under a preset traffic condition; The base packet loss rate of the current candidate link l on the target road segment r; This is a sample of the packet loss rate of the current candidate link l on the target road segment r under the preset traffic conditions; The preset traffic conditions for the target road segment r are given. The median is calculated using the above method. and This refers to the basic latency and basic packet loss rate of the link under preset traffic conditions, which serve as an important benchmark for subsequent latency correction and link scoring.

[0038] By collecting latency and packet loss rate samples of current candidate links in a single link communication, raw data support is provided for subsequent basic parameter calculations. By identifying stable traffic conditions on the target road segment as preset traffic conditions and recording the corresponding target traffic condition parameters, a unified operating condition reference benchmark is established for the screening of latency and packet loss rate. Candidate latency samples and candidate packet loss rate samples are screened from all samples based on the target traffic condition parameters, and abnormal samples under unstable operating conditions are eliminated to ensure that the samples participating in the calculation are all in a scenario consistent with the preset traffic conditions. By using the median of the candidate latency samples as the basic latency and the median of the candidate packet loss rate samples as the basic packet loss rate, the characteristic that the median is insensitive to extreme outliers is used to robustly reflect the typical communication performance level of the candidate links under the preset traffic conditions.

[0039] Step S102: Calculate the traffic condition impact index based on real-time traffic condition parameters, and correct the base delay based on the traffic condition impact index to obtain the delay estimate.

[0040] In this embodiment, traffic condition parameters include at least one of the following parameters: vehicle speed, number of conflicting targets, and business sensitivity; the traffic condition impact index is calculated based on real-time traffic condition parameters, including: Step B1: Compare the first vehicle speed in the real-time traffic condition parameters with the second vehicle speed in the target traffic condition parameters, and normalize them using a preset speed mapping function to obtain a normalized vehicle speed value; and / or: Compare the first number of conflict targets in the real-time traffic condition parameters with the second number of conflict targets in the target traffic condition parameters, and normalize them using a preset conflict target number mapping function to obtain a normalized conflict target number value; and / or: Compare the first business sensitivity in the real-time traffic condition parameters with the second business sensitivity in the target traffic condition parameters, and normalize them using a preset business sensitivity mapping function to obtain a normalized business sensitivity value.

[0041] Specifically, the first vehicle speed refers to the actual vehicle speed collected on the target road segment at the current moment, and the second vehicle speed refers to the reference value of vehicle speed recorded under preset traffic conditions. The comparison between the two is used to measure the degree of deviation of the current vehicle speed from the stable operating condition. The first number of conflicting targets refers to the total number of pedestrians, non-motorized vehicles, and other vehicles that need to be fused and processed within the intersection or road segment area sensed by radar and cameras at the current moment, and the second number of conflicting targets refers to the reference value of the number of conflicting targets recorded under preset traffic conditions. The comparison between the two is used to reflect the change in the current perception fusion processing pressure. The first business sensitivity refers to the quantitative value of resource allocation and real-time requirements corresponding to the current business type, and the second business sensitivity refers to the reference value of business sensitivity recorded under preset traffic conditions. The comparison between the two is used to reflect the impact of changes in business priority. The preset speed mapping function, preset conflicting target number mapping function, and preset business sensitivity mapping function are conversion rules that transform the differences between the corresponding real-time parameters and preset parameters into dimensionless normalized values. The purpose of normalization is to eliminate the differences in the dimensions and numerical ranges of different parameters, so that subsequent fusion calculations are comparable.

[0042] During normalization, the difference between the speed of the first vehicle and the speed of the second vehicle are input into a preset speed mapping function, the difference between the number of the first conflict targets and the number of the second conflict targets are input into a preset conflict target number mapping function, and the difference between the first business sensitivity and the second business sensitivity is input into a preset business sensitivity mapping function. Each mapping function can be established based on historical operating data of the target road segment using methods such as linear mapping, segmented mapping, grade assignment, or nonlinear fitting. When the real-time parameters are equal to the preset parameters, the normalization value is 0. The specific formula is as follows:

[0043] in, This is the normalized value for vehicle speed. The preset speed mapping function for the target road segment r; The first vehicle's operating speed; The second vehicle speed is the target road segment r.

[0044]

[0045] in, This represents the normalized value for the number of conflicting targets. A preset collision target number mapping function for target road segment r; The number of primary conflict targets; The number of second conflicting targets for the target road segment r.

[0046]

[0047] in, This is a normalized value for business sensitivity. The preset business sensitivity mapping function for the target road segment r; Prioritize business sensitivity; The second business sensitivity of the target road segment r.

[0048] The above three normalized values , , These are used to represent changes in communication distance and coverage duration caused by changes in vehicle speed, changes in perception fusion processing pressure caused by changes in the number of conflicting targets, and changes in resource allocation and task priority caused by changes in service type.

[0049] Step B2: According to the preset influence weights corresponding to the normalized values ​​of each parameter, the normalized values ​​of vehicle speed and / or conflict target quantity and / or business sensitivity are fused and calculated to obtain the traffic condition influence index.

[0050] Specifically, the preset impact weight refers to the contribution ratio of the normalized value of vehicle speed, the normalized value of the number of conflicting targets, and the normalized value of business sensitivity in the fusion calculation. It reflects the degree of influence of different traffic condition parameters on the communication latency of the current candidate link. All weights are non-negative and the sum is 1. The traffic condition impact index is a quantitative indicator that comprehensively reflects the degree of influence of the current real-time traffic condition on the communication latency compared with the preset traffic condition. When the index is positive, it means that the current traffic condition is more complex than the preset condition and has an effect on increasing the latency. When it is negative, it means that the current condition is better than the preset condition and has an effect on reducing the latency. When it is close to 0, it means that the current condition is basically the same as the preset condition.

[0051] During the fusion calculation, the normalized value of vehicle speed, the normalized value of the number of conflict targets, and the normalized value of business sensitivity are multiplied by their respective preset influence weights, and then the three products are added together to obtain the traffic condition influence index. The specific formula is as follows:

[0052] in, The traffic condition impact index for the current candidate link l; Weight the impact of vehicle speed; This is the normalized value for vehicle speed. The number of conflicting targets affects the weighting; This represents the normalized value for the number of conflicting targets. The weight is influenced by business sensitivity; This is a normalized value for business sensitivity. The preset influence weights for each item satisfy the following constraints:

[0053]

[0054] The weights can be determined by regression fitting, gradient descent or other parameter calibration methods based on historical operating data of the target road segment, or they can be preset by engineers based on their experience in actual scenarios. Different weight allocations reflect the differences in the degree of influence of different traffic condition parameters on link delay.

[0055] Figure 2 This is a schematic diagram of the time delay estimate calculation process, as follows: Figure 2 As shown, the process comprises three closely linked calculation steps: First, basic latency is calculated by collecting underlying link communication parameters (including link medium type, distance and time slot parameters, number of concurrency and targets, etc.) to calculate physical layer latency, MAC scheduling latency, edge processing latency, protocol encapsulation latency, and queuing latency based on the M / M / 1 queuing model. The five components are then summed to obtain the basic latency. Second, correction coefficients are calculated by normalizing the current vehicle speed, number of conflicting targets, and business sensitivity using a preset mapping function, then fusing them into a traffic condition impact index according to preset influence weights, and adding it to a preset baseline value of 1 to obtain the correction coefficient. Finally, the basic latency is multiplied by the correction coefficient to obtain the estimated link latency under the current traffic conditions.

[0056] By comparing the first vehicle speed in the real-time traffic condition parameters with the second vehicle speed in the target traffic condition parameters and normalizing the vehicle speed using a preset speed mapping function, the impact of absolute speed differences between different road segments on the evaluation results is eliminated. By comparing the number of the first conflict target with the number of the second conflict target and normalizing the number of conflict targets using a preset conflict target number mapping function, a unified quantification of the differences in the number of targets at different intersections is achieved. By comparing the first business sensitivity with the second business sensitivity and normalizing the business sensitivity using a preset business sensitivity mapping function, a unified representation of the real-time requirements of different business types is achieved. By fusion calculation according to the preset influence weights corresponding to each normalized value, a traffic condition influence index is obtained, which comprehensively reflects the combined influence of the three dimensions of vehicle speed, number of conflict targets, and business sensitivity on the current link latency.

[0057] In this embodiment of the application, the time delay is corrected based on the traffic condition impact index to obtain the time delay estimate, including: adding the traffic condition impact index to a preset benchmark value to obtain a traffic condition correction coefficient; and multiplying the basic time delay by the traffic condition correction coefficient to obtain the time delay estimate.

[0058] Specifically, the preset baseline value is a fixed base used to convert the traffic condition impact index into a correction coefficient. This baseline value is set to 1, indicating that when the traffic condition impact index is 0, the correction coefficient is 1, meaning that the base delay does not need any correction when the current traffic condition is completely consistent with the preset traffic state. The traffic condition correction coefficient is a dimensionless scaling factor used to quantify the comprehensive amplification or reduction effect of the current traffic condition on the link delay compared to the preset traffic state. A value greater than 1 indicates that the current condition is more complex than the preset state and the delay increases; a value equal to 1 indicates that the two are comparable; and a value less than 1 indicates that the current condition is better than the preset state and the delay decreases. The delay estimate is the predicted delay value under the current traffic condition obtained by multiplying the base delay by the correction coefficient, and it is used to replace the original base delay in subsequent link scoring.

[0059] The traffic condition impact index is added to the preset baseline value 1 to obtain the traffic condition correction coefficient. Then, the base delay is multiplied by the correction coefficient to obtain the estimated delay value under the current traffic condition. The specific formula is as follows:

[0060] in, Traffic condition correction factor for the current candidate link l; This represents the traffic condition impact index for the current candidate link l. When... hour, This indicates that the current traffic conditions are similar to the preset traffic conditions, and the basic time delay remains unchanged.

[0061] in, The time delay estimate is the current candidate link l on the target road segment r; The base delay of the current candidate link l on the target road segment r; This is the traffic condition correction coefficient for the current candidate link l. Through the above multiplication correction, the static base delay can be mapped to a delay estimate that dynamically adapts to the current traffic conditions, enabling subsequent link scores to truly reflect the impact of real-time conditions on communication performance.

[0062] By adding the traffic condition impact index to the preset benchmark value, a traffic condition correction coefficient is obtained, which transforms the overall deviation of the current traffic state from the preset traffic state into a dimensionless scaling factor. By multiplying the base delay by the traffic condition correction coefficient, a delay estimate is obtained, which dynamically maps the static base delay to a delay prediction value adapted to the current traffic condition, thereby realizing the quantitative correction of the impact of traffic conditions on communication delay in a multiplicative form.

[0063] Step S103: Obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, base packet loss rate, delay estimate and measured packet loss rate.

[0064] In this embodiment, the measured packet loss rate refers to the proportion of messages actually lost on the current candidate link at the current moment. It is used to compare with the baseline packet loss rate to evaluate the change in transmission reliability of the link under the current traffic conditions. This measured value reflects the real-time communication quality and forms a comparison with the baseline packet loss rate as a benchmark value under preset conditions. The difference between the two will directly affect the calculation result of the link comprehensive score. The measured packet loss rate has the same definition as the packet loss rate sample, both of which are the proportion of the number of messages that failed to reach the receiving end to the total number of messages at the sending end. However, the difference is that the measured packet loss rate is the real-time observation value at the current moment rather than a historical sample.

[0065] When obtaining the measured packet loss rate, the communication protocol stack of the vehicle-mounted OBU or roadside RSU is used to count the total number of messages sent by the sender and the total number of messages actually received by the receiver within a preset time window of the current candidate link. The difference between the two is divided by the total number of messages sent to obtain the measured packet loss rate.

[0066] In this embodiment of the application, the transmission performance score of the current candidate link is calculated based on the base latency, base packet loss rate, latency estimate, and measured packet loss rate, including: Step C1: Obtain the current allowed latency and the current allowed packet loss rate, as well as the allowed latency and the allowed packet loss rate under the preset state.

[0067] Specifically, the current allowable latency refers to the maximum end-to-end latency that the system can accept at the current moment under the current service type and traffic conditions. Exceeding this value will result in unacceptable service quality. The current allowable packet loss rate refers to the maximum packet loss rate that the system can accept at the current moment under the current service type and traffic conditions. Exceeding this value will result in unreliable transmission. The preset allowable latency refers to the baseline value of allowable latency determined based on the current service type and traffic conditions under preset traffic conditions. The preset allowable packet loss rate refers to the baseline value of allowable packet loss determined based on the current service type and traffic conditions under preset traffic conditions. Both are determined through the mapping relationship between service type, traffic conditions, and corresponding allowable values. Different service types and different conditions correspond to different allowable latency and allowable packet loss rates. For example, the allowable latency for emergency warning services may be more relaxed under congested conditions, while the allowable latency for routine sensing services is more stringent under smooth traffic conditions.

[0068] Identify the current service type and current traffic condition, and input the preset mapping functions F and G from the service type and traffic condition to the allowable latency and allowable packet loss rate, respectively, to obtain the current allowable latency and current allowable packet loss rate. Simultaneously, input the same mapping functions F and G for the service type and traffic condition under preset traffic conditions to obtain the allowable latency and allowable packet loss rate under preset conditions. The specific formulas are as follows:

[0069] in, Let be the current allowed delay at time t; A mapping function between business type, traffic conditions, and allowable delay; For the current business type; Let r be the current traffic conditions of the target road segment r at time t.

[0070]

[0071] in, Let t be the current allowed packet loss rate; This is a mapping function between business type, traffic conditions, and allowable packet loss rate.

[0072] Step C2: Determine the preset state delay occupancy ratio based on the base delay and the allowable delay under the preset state, and determine the current delay occupancy ratio based on the delay estimate and the current allowable delay.

[0073] Specifically, the preset state delay occupancy ratio is the ratio of the base delay to the allowable delay under the preset state. It measures the proportion of the baseline delay of the current candidate link to the allowable budget under the preset traffic conditions. The smaller the value, the more sufficient the delay margin of the link under the baseline state. The current delay occupancy ratio is the ratio of the estimated delay to the current allowable delay. It measures the proportion of the corrected delay estimate under the current traffic conditions to the current allowable budget. The smaller the value, the more sufficient the delay performance of the link under the current real-time conditions. The difference between the two occupancy ratios reflects the trend of delay occupancy of the candidate link from the preset state to the current state. A positive value indicates a decrease in the occupancy ratio and an improvement in the relative performance of the link, while a negative value indicates an increase in the occupancy ratio and a deterioration in the relative performance of the link.

[0074] When determining the above two delay occupancy ratios, the base delay is divided by the allowable delay under the preset state to obtain the preset state delay occupancy ratio; the corrected delay estimate is divided by the current allowable delay to obtain the current delay occupancy ratio, as shown in the following formula:

[0075] in, The preset state delay occupancy ratio of the current candidate link l; The base delay of the current candidate link l on the target road segment r; The allowed delay is set to the preset state.

[0076]

[0077] in, The current latency occupancy ratio of the current candidate link l at time t; The time delay estimate is the current candidate link l on the target road segment r; Let be the current allowed delay at time t. The occupancy ratio of the above two items. and This will be used as the input for subsequent comprehensive score calculations based on latency, and will be used to compare the latency performance changes of the link under the preset state and the current state.

[0078] Step C3: Determine the packet loss rate occupancy ratio under the preset state based on the base packet loss rate and the allowed packet loss rate under the preset state, and determine the current packet loss rate occupancy ratio based on the measured packet loss rate and the current allowed packet loss rate.

[0079] Specifically, the preset state packet loss rate occupancy ratio refers to the ratio of the base packet loss rate to the allowable packet loss rate under the preset state. It measures the proportion of the baseline packet loss rate of the current candidate link under the preset traffic conditions to the allowable packet loss budget at that time. The smaller this value, the more sufficient the transmission reliability margin of the link under the baseline state. The current packet loss rate occupancy ratio refers to the ratio of the measured packet loss rate to the current allowable packet loss rate. It measures the proportion of the real-time observed packet loss rate under the current traffic conditions to the current allowable packet loss budget. The smaller this value, the more ample the packet loss performance of the link under the current real-time conditions. The difference between the two occupancy ratios reflects the trend of packet loss rate occupancy of the candidate link from the preset state to the current state. A positive value indicates a decrease in occupancy ratio and an improvement in the relative reliability of the link, while a negative value indicates an increase in occupancy ratio and a deterioration in the relative reliability of the link.

[0080] When determining the above two packet loss rate occupancy ratios, the base packet loss rate is divided by the obtained preset allowed packet loss rate to obtain the preset allowed packet loss rate occupancy ratio; the measured packet loss rate is divided by the obtained current allowed packet loss rate to obtain the current packet loss rate occupancy ratio. The specific formulas are as follows:

[0081] in, The preset state packet loss rate occupancy ratio for the current candidate link l; The base packet loss rate of the current candidate link l on the target road segment r; Allowable packet loss rate under default conditions.

[0082]

[0083] in, The current packet loss rate occupancy ratio of the current candidate link l at time t; Let be the measured packet loss rate of the current candidate link l at time t; Let be the current allowed packet loss rate at time t. The above two items are the occupancy ratios. and This will be used as a dimension of packet loss rate in subsequent comprehensive score calculations to compare the changes in link transmission reliability between the preset state and the current state.

[0084] Step C4: Calculate the transmission performance score of the current candidate link based on the preset state delay occupancy ratio, the current delay occupancy ratio, the preset state packet loss rate occupancy ratio, the current packet loss rate occupancy ratio, and the preset scoring weight.

[0085] Specifically, the preset scoring weights refer to the respective contribution ratios of the latency and packet loss rate dimensions in calculating the overall transmission performance score of the link. This includes two weights: latency evaluation weight and packet loss rate evaluation weight. Both are non-negative and sum to 1, used to adjust the relative importance of latency and packet loss rate in the final score. The transmission performance score is a comprehensive value obtained by weighted summation of the differences in latency occupancy and packet loss rate occupancy between the preset and current states. This score quantifies the overall performance change of the current candidate link under the current traffic conditions compared to the preset traffic state. A positive score indicates that the current overall performance of the link is better than the preset state, a negative score indicates that it is worse than the preset state, and a score closer to 0 indicates that it is basically equivalent to the preset state.

[0086] In the calculation, the current delay occupancy ratio is subtracted from the preset state delay occupancy ratio to obtain the change in delay occupancy ratio, which is then multiplied by the delay evaluation weight; the current packet loss rate occupancy ratio is subtracted from the preset state packet loss rate occupancy ratio to obtain the change in packet loss rate occupancy ratio, which is then multiplied by the packet loss rate evaluation weight; the two weighted results are added together to obtain the transmission performance score of the current candidate link, as shown in the following formula:

[0087] in, This represents the transmission performance score of the current candidate link l. As a weight for time delay evaluation; Preset state delay occupancy ratio; This represents the current latency occupancy rate. Assess the weighting of packet loss rate; The packet loss rate is the pre-defined percentage for the current state. This represents the current packet loss rate. The preset scoring weights for each item satisfy the following constraints:

[0088]

[0089] When the candidate link is in a preset traffic state and ,at this time When the current latency occupancy ratio of the link is less than the preset occupancy ratio or the current packet loss rate occupancy ratio is less than the preset occupancy ratio, the corresponding difference item is positive, and the link comprehensive score will be greater than 0, indicating that the current comprehensive performance of the link is better than the baseline level under the preset traffic conditions.

[0090] By acquiring the current allowed latency and current allowed packet loss rate, and by acquiring the allowed latency and allowed packet loss rate under preset conditions, a unified evaluation scale was established for both the preset and current states, respectively, for the two dimensions of latency and packet loss rate. By determining the latency occupancy ratio under preset conditions based on the base latency and the allowed latency under preset conditions, and by determining the current latency occupancy ratio based on the latency estimate and the current allowed latency, the absolute values ​​of latency under preset and current states were transformed into relative occupancy levels within their respective allowable budgets, achieving comparable quantification of latency performance under different states. Furthermore, by determining the latency occupancy ratio based on the base packet loss rate and the allowed packet loss rate under preset conditions... The packet loss rate is determined by setting the preset state packet loss rate occupancy ratio and by setting the current packet loss rate occupancy ratio based on the measured packet loss rate and the current allowed packet loss rate. The absolute values ​​of the packet loss rates in the preset state and the current state are converted into relative occupancy levels within their respective allowable budgets. The transmission performance score is obtained by weighted summation based on the difference between the preset state latency occupancy ratio and the current latency occupancy ratio, the difference between the preset state packet loss rate occupancy ratio and the current packet loss rate occupancy ratio, and the preset scoring weights. This integrates the relative changes in latency and packet loss rate, and quantitatively reflects the direction and degree of the overall performance deviation of the current candidate link relative to its preset traffic state.

[0091] In this embodiment of the application, after calculating the transmission performance score of the current candidate link, the method further includes: Step S201: The transmission performance score is compared with a preset valid threshold and a preset invalid threshold, wherein the preset invalid threshold is less than the preset valid threshold.

[0092] In this embodiment, the preset effective threshold refers to the minimum transmission performance score required to determine whether a candidate link has reached a fully effective state. When the link score is higher than or equal to the threshold, the link is considered to have excellent communication quality and can be used as the main transmission channel. The preset invalid threshold refers to the upper limit of the transmission performance score required to determine whether a candidate link has failed. When the link score is lower than the threshold, the link is considered to have severely deteriorated communication quality and should be blocked. The preset invalid threshold is lower than the preset effective threshold. Typically, the preset effective threshold is a value less than or equal to 0, while the preset invalid threshold is a smaller negative value. The range between the two is used to indicate that the link is in a conditionally usable state, that is, the performance has degraded but it can still be used in an emergency.

[0093] When determining link validity, the transmission performance score of the current candidate link is compared with a preset valid threshold and a preset invalid threshold. The link status level is determined based on whether the score falls into one of three different intervals. The specific determination criteria are as follows: Fully valid link Conditional available links Failed Link in, This represents the transmission performance score of the current candidate link l. The preset effective threshold; To preset an invalid threshold, both conditions must be met. By dividing candidate links into three levels—fully valid, conditionally available, and invalid—a clear basis is provided for subsequent link priority configuration and service message scheduling.

[0094] In step S202, if the transmission performance score is greater than or equal to a preset valid threshold, the current candidate link is determined to be a fully valid link; or, if the transmission performance score is greater than or equal to a preset invalid threshold and less than a preset valid threshold, the current candidate link is determined to be a conditionally available link; or, if the transmission performance score is less than a preset invalid threshold, the current candidate link is determined to be a failed link.

[0095] In this embodiment, a fully effective link refers to a candidate link whose transmission performance score reaches or exceeds a preset effective threshold, indicating that the link has excellent overall communication quality under the current traffic conditions, and its latency and packet loss performance are within acceptable ranges. It can be directly used as the main transmission channel for service-aware messages. A conditionally usable link refers to a candidate link whose transmission performance score is between the preset invalid threshold and the preset effective threshold (including the lower limit, excluding the upper limit), indicating that the link's overall performance has decreased under the current conditions but still has a certain communication capability. It can only be used as a backup channel when the main link is congested. A failed link refers to a candidate link whose transmission performance score is lower than the preset invalid threshold, indicating that the link's latency or packet loss has seriously deteriorated and cannot meet the basic communication requirements of the current service. It should be directly shielded by the communication middleware to avoid invalid transmission and resource waste.

[0096] Based on the comparison between the transmission performance score and a preset threshold, link status is determined according to the following three branch conditions: if the transmission performance score is not lower than the preset valid threshold, it is determined to be a fully valid link; if the transmission performance score is between the preset invalid threshold and the preset valid threshold, it is determined to be a conditionally usable link; if the transmission performance score is lower than the preset invalid threshold, it is determined to be a failed link. Through this three-level interval determination, candidate links are clearly classified into one of the three status levels: fully valid, conditionally usable, or failed, providing a direct basis for subsequent link priority configuration and awareness message allocation and scheduling in the communication middleware.

[0097] Figure 3 This is a schematic diagram of the link transmission performance scoring and validity determination process, such as... Figure 3As shown, after obtaining the latency estimate and the measured packet loss rate, the process calculates two types of occupancy ratios: For the latency dimension, the ratio of the base latency to the allowable latency under the preset state is used as the preset state latency occupancy ratio, and the ratio of the latency estimate to the current allowable latency is used as the current latency occupancy ratio; for the packet loss rate dimension, the ratio of the base packet loss rate to the allowable packet loss rate under the preset state is used as the preset state packet loss rate occupancy ratio, and the ratio of the measured packet loss rate to the current allowable packet loss rate is used as the current packet loss rate occupancy ratio. Based on this, the latency evaluation weight and the packet loss rate evaluation weight are multiplied by the change in each of the above two occupancy ratios (preset state occupancy ratio minus current state occupancy ratio) and summed to obtain the link transmission performance score. A positive score indicates that the current performance is better than the preset state, and a negative score indicates that it is worse than the preset state. Finally, the score is compared with the preset valid threshold and the preset invalid threshold: when the score is not lower than the valid threshold, it is determined to be a fully valid link; when the score is between the invalid threshold and the valid threshold (including the invalid threshold and excluding the valid threshold), it is determined to be a conditionally usable link; when the score is lower than the invalid threshold, it is determined to be a failed link.

[0098] By comparing transmission performance scores with preset valid and invalid thresholds, and utilizing the relationship between the preset invalid threshold and the preset valid threshold, three non-overlapping hierarchical intervals are established. When the transmission performance score is greater than or equal to the preset valid threshold, the current candidate link is determined to be a fully valid link, and links with overall performance better than or equivalent to the preset state are selected as high-confidence available channels. When the transmission performance score is greater than or equal to the preset invalid threshold and less than the preset valid threshold, the current candidate link is determined to be a conditionally available link, identifying links with degraded performance but still possessing limited communication capabilities as emergency backups. When the transmission performance score is less than the preset invalid threshold, the current candidate link is determined to be a failed link, accurately filtering out links with severely degraded overall performance to avoid invalid transmission and resource waste.

[0099] In this embodiment of the application, the method further includes: Step D1: When there are multiple fully valid links, compare the current latency occupancy ratio of each fully valid link and select the fully valid link with the smallest current latency occupancy ratio as the main transmission link.

[0100] Specifically, the primary transmission link refers to the link that is preferentially selected from multiple fully effective links as the main communication channel to carry the current service-aware message. This link has the best latency occupancy performance and can provide the most timely transmission service for the service. The current latency occupancy ratio is defined as the ratio of the estimated latency to the current allowable latency. The smaller the value, the more sufficient the latency margin of the link under the current operating conditions, and the better the real-time communication performance. When multiple fully effective links exist, the one with the smallest latency occupancy ratio needs to be selected as the primary transmission link to ensure that the current service-aware message is transmitted through the channel with the best latency performance.

[0101] During the selection process, once the current candidate link is determined to be a fully valid link, all candidate links marked as fully valid are aggregated, and the current latency occupancy ratio of each link at the current moment is extracted. By comparing the ratio values ​​of each link, the fully valid link with the smallest value is selected as the main transmission link.

[0102] Step D2: A channel switching command is issued through the communication middleware to configure fully effective links as the first priority, conditionally available links as the second priority, and failed links as the third priority. The first priority allocates current service-aware messages according to the first allocation weight, the second priority allocates current service-aware messages according to the second allocation weight, and the third priority stops allocating current service-aware messages. The first allocation weight is greater than the second allocation weight.

[0103] Specifically, the communication middleware is a software scheduling layer deployed between the vehicle, roadside, and cloud, responsible for dynamically routing and message distribution control of each transmission channel based on the link validity determination results. The channel switching command is a control signaling that the communication middleware can recognize and execute, used to adjust the priority and message allocation weight of each candidate link in the current service-aware message transmission. The first priority is the highest transmission level allocated to fully effective links, corresponding to the allocation of current service-aware messages according to the first allocation weight, ensuring that service data is sent first through the channel with the best performance. The second priority is the secondary transmission level allocated to conditionally available links, corresponding to the allocation of current service-aware messages according to the second allocation weight, and is only activated when the first priority link resources are insufficient or congestion occurs. The third priority is the lowest transmission level allocated to failed links, corresponding to the cessation of allocation of current service-aware messages to save communication resources. The first allocation weight is greater than the second allocation weight, used to reflect the difference in the number and proportion of different levels of links in message distribution.

[0104] In implementation, a channel switching command is sent to each communication node on the vehicle and roadside via a communication middleware. This command carries the channel identifiers and corresponding message allocation weights for fully active links, conditionally available links, and failed links. After the command is sent, each node allocates the current service-aware messages proportionally according to their weight values. That is, the sum of the allocation weights of all candidate links is 1, but the weight of failed links is 0. In reality, service-aware messages are only allocated proportionally between fully active links and conditionally available links. A higher allocation ratio ensures that the primary link undertakes the majority of message transmission tasks, while a lower allocation ratio ensures that the backup link only undertakes partial transmission when the primary link is congested or abnormal. This achieves differentiated scheduling of links with different effectiveness levels.

[0105] When multiple fully effective links exist, the current latency occupancy ratio of each fully effective link is compared, and the fully effective link with the lowest current latency occupancy ratio is selected as the primary transmission link. This ensures that current service-aware messages are transmitted preferentially through the channel with the most sufficient latency margin. By issuing channel switching instructions through the communication middleware, fully effective links are configured as the first priority, conditionally available links as the second priority, and failed links as the third priority, a clear distinction is achieved between the three link levels. The first priority allocates current service-aware messages according to the first allocation weight, the second priority allocates current service-aware messages according to the second allocation weight, and the third priority stops allocating current service-aware messages, with the first allocation weight being greater than the second allocation weight. This allows service messages to be allocated proportionally according to the link effectiveness level, ensuring that the primary link carries the vast majority of message transmissions while retaining the emergency carrying capacity of backup links and preventing the invalid occupancy of failed links.

[0106] In this embodiment of the application, the method further includes: acquiring measured data during the link communication process in the target road segment; updating the basic latency and basic packet loss rate under the preset traffic conditions based on the measured data, and / or updating the preset influence weights used to calculate the traffic condition influence index, and / or updating the preset scoring weights used to calculate the transmission performance score, and / or updating the preset threshold used to determine the effectiveness of the link.

[0107] Specifically, the measured data in this step refers to the actual operational data recorded during each link communication process on the target road segment, including the measured values ​​of communication latency, packet loss rate, vehicle speed, number of conflicting targets, business sensitivity, traffic condition correction coefficient, link score, and corresponding time information and road segment identification for each link. This data is temporarily stored by the roadside edge computing unit and then periodically uploaded to the cloud platform. The update refers to recalibrating and optimizing the various preset parameters in the model using the newly added measured data, so that the model can adapt to differentiated scenarios and long-term traffic flow changes. Among them, the update of the base latency and base packet loss rate depends on recalculating the median under the premise that the preset traffic state remains unchanged. The update of the preset influence weight and preset score weight depends on parameter calibration methods such as regression fitting or gradient descent. The update of the preset effective threshold and preset invalid threshold depends on the statistical analysis of the normal fluctuation range of the score distribution under natural conditions.

[0108] In implementation, newly added measured data is stored in a cloud storage database. A sliding window is used to extract valid samples from the most recent period, and the following four types of update operations are performed: First, candidate delay samples and candidate packet loss rate samples are selected from the window samples according to preset traffic conditions, and the median is recalculated to update the base delay and base packet loss rate; Second, based on the actual distribution of features such as vehicle speed, number of conflicting targets, and business sensitivity in the window samples, the normalization mapping relationship corresponding to these features is updated (i.e., the parameters of the normalization transformation function are adjusted) so that the normalized feature values ​​can better reflect the current data distribution; based on the updated normalized values... The algorithm performs regression fitting with the corresponding measured latency values ​​to recalibrate the weights of vehicle speed, number of conflicting targets, and business sensitivity, specifically using the least squares method to solve the optimization problem. Third, by comparing the scores of each link calculated in the window sample with the preset state scores, gradient descent or grid search methods are used to recalibrate the latency evaluation weights and packet loss rate evaluation weights, minimizing the deviation between the scoring results and actual link quality observations. Fourth, the mean and standard deviation of the scores of all candidate links in the window sample under preset traffic conditions are statistically analyzed, and updated preset valid and invalid thresholds are set based on the normal fluctuation range. All four update operations can be performed, or only some can be selected based on actual deployment needs to adapt to different model maintenance strategies.

[0109] By acquiring measured data from the link communication process in the target road segment, a continuous stream of real-world operational samples is accumulated for updating model parameters. By updating the baseline latency and baseline packet loss rate under preset traffic conditions based on the measured data, the baseline parameters can be adaptively adjusted according to long-term changes in the road environment and communication conditions. By updating the preset influence weights used to calculate the traffic condition influence index, the contribution ratio of each condition parameter to the latency impact can be continuously calibrated based on actual observation results. By updating the preset scoring weights used to calculate the transmission performance score, the relative importance of latency and packet loss rate in the scoring can be dynamically optimized according to actual business needs. By updating the preset thresholds used to determine link effectiveness, the strictness of the classification judgment can be automatically adjusted according to the normal fluctuation range of the score distribution under natural conditions.

[0110] Figure 4 A flowchart illustrating the method for calculating latency and determining link validity in multi-link communication between vehicles, roads, and the cloud under integrated traffic conditions is shown below. Figure 4 As shown, the method is divided into two main stages: the first stage is the baseline establishment stage, which completes the link topology initialization based on long-term operating data (covering four types of links: V2V, I2V, I2C2V, and V2C2V, clarifying the node composition and communication method of each link), and establishes a baseline parameter set under natural traffic conditions (including basic latency, natural traffic speed, number of conflicting targets under natural traffic conditions, and business sensitivity under natural traffic conditions, etc.); the second stage is the real-time evaluation and dynamic scheduling stage, which collects and normalizes the current vehicle speed, number of conflicting targets, and business sensitivity, and then calculates the traffic condition impact index and correction coefficient to obtain the latency estimate. Based on this, the allowable latency and allowable packet loss rate are determined according to the current business type. The latency occupancy ratio and packet loss rate occupancy ratio are calculated, and the transmission performance score is calculated according to the scoring formula. The links are divided into three levels: fully effective, conditionally available, and failed according to the preset threshold. Based on this, the primary and backup links are determined, message allocation and link switching are performed, and message allocation to failed links is stopped. In addition, the method also includes a closed-loop iterative optimization mechanism. By collecting communication logs (send and receive timestamps, packet loss statistics, scoring results, scheduling results, etc.) and updating the natural state baseline parameters, normalized mapping relationship, influence weight, scoring weight and judgment threshold based on historical data, the model achieves long-term adaptive optimization.

[0111] As an example, this embodiment is deployed at a typical intersection of a main urban road, targeting non-motorized vehicle collision warning services. It uses an I2V (infrastructure-to-vehicle) link to transmit roadside sensing messages. The system hardware comprises three main parts: the vehicle-mounted terminal, the roadside terminal, and the central cloud platform. The vehicle-mounted terminal is equipped with an OBU terminal (including a vehicle positioning module, a 5G communication module, and a PC5 communication module) and an HMI (human-machine interface) terminal. The roadside terminal deploys RSU (Roadside Unit) devices, millimeter-wave radar and high-definition camera sensing units, edge MEC (Multi-access Edge Computing) nodes, and 5G base stations at each intersection. The central cloud platform is equipped with a cloud server cluster, a cloud storage database, and a cloud-based 5G gateway. The currently activated link in the service scenario is a dedicated I2V path, and the communication channel combination is a PC5 direct connection channel and a fiber optic transmission channel.

[0112] First, the multi-link topology management module of the cloud platform loads the dedicated path configuration of the I2V link according to the current non-motorized vehicle collision warning service type, reads hardware information such as fiber optic link length and RSU device underlying communication parameters, and locks the link type used by the current service, providing channel hardware parameter basis for subsequent component delay decomposition calculation.

[0113] Secondly, establish the basic parameters of natural traffic state for I2V links: Step 1: Collect long-term runtime latency samples. Based on the link topology and communication logs reported by each communication node, obtain the physical layer transmission latency. MAC layer scheduling delay and protocol stack encapsulation and parsing latency Read the number of concurrent sensing messages per second at the intersection, and use the M / M / 1 queuing model to solve for queuing latency. Read the number of targets detected in real time by radar and cameras, and calculate the edge MEC perception processing latency. Summing the above five components yields the single-link delay sample of the I2V candidate link l in the target road segment r, as shown in the following formula:

[0114] Step 2: Confirm the natural traffic conditions. Based on long-term observations, the cloud platform identifies the traffic conditions at the intersection that occur frequently and are relatively stable, and records them as follows: And record the typical operating parameters under this state: second vehicle operating speed Number of second conflict targets (Refers to the total number of targets that need to be sensed and fused within the intersection area), Second Business Sensitivity (The baseline sensitivity for non-motorized vehicle collision warning services).

[0115] Step 3: Determine the base time delay for natural traffic conditions. From all time delay samples, select those whose collection times belong to the preset traffic conditions. From the candidate latency samples, the median is taken as the base latency, and the following is calculated: .

[0116] Step 4: Determine the baseline packet loss rate for natural traffic conditions. From all packet loss rate samples, select those collected at the time of the preset traffic conditions. From the candidate packet loss rate samples, the median is taken as the base packet loss rate, and the following is calculated: .

[0117] The aforementioned basic parameters provide a stable benchmark for evaluating the difference between the current traffic condition and the natural traffic condition.

[0118] Secondly, current traffic condition parameters are collected and normalized: Step 1: Vehicle speed normalization. The onboard OBU reads the instantaneous vehicle speed at the current moment. By using a preset speed mapping function, it is compared with the speed of natural traffic conditions. By performing comparison and normalization, the normalized value of vehicle speed is obtained. .

[0119] Step 2: Conflict Target Count Normalization. Roadside radar and cameras count a total of 12 targets at the current intersection, including pedestrians and non-motorized vehicles. The edge MEC normalizes these targets against the natural traffic state's conflict target count using a pre-defined conflict target count mapping function. By performing comparative normalization, the normalized value of the number of conflicting targets is obtained. .

[0120] Step 3: Business Sensitivity Normalization. The edge MEC reads the current business identifier as a non-motorized vehicle collision warning, and uses a preset business sensitivity mapping function to normalize it with the business sensitivity under natural traffic conditions. By performing comparison and normalization, the normalized value of business sensitivity is obtained. .

[0121] The above normalization parameters transform the parameters under the current traffic conditions into dimensionless values ​​relative to the natural state, providing support for the subsequent calculation of the traffic condition impact index.

[0122] Next, the traffic condition impact index, correction coefficient, and time delay estimate are calculated: Step 1: Calculate the traffic condition impact index. Set the impact weights for vehicle speed, number of conflicting targets, and business sensitivity as follows:

[0123] The traffic condition impact index is obtained by multiplying each normalized value by its corresponding weight and then summing the results.

[0124] Step 2: Calculate the traffic condition correction factor. Add the traffic condition impact index to the preset baseline value 1 to obtain the correction factor: .

[0125] Step 3: Solving for the link delay estimate. Multiply the base delay by the correction factor to obtain the delay estimate under the current traffic conditions: .

[0126] The proposed solution calculates the link latency to be 25.92ms, while the actual device latency is 26.8ms, with an error of only 0.88ms. This is far superior to the traditional no-latency correction model, which has a calculation deviation of over 8ms.

[0127] Subsequently, the overall link score is calculated: Step 1: Determine the allowable latency and allowable packet loss rate. Based on the non-motorized vehicle collision warning service type, determine the allowable latency and allowable packet loss rate for both the preset and current states. Allowable latency under the preset state... Allowable packet loss rate Allowable delay under current traffic conditions Allowable packet loss rate .

[0128] Step 2: Calculate the latency occupancy ratio. Preset latency occupancy ratio: Current latency occupancy rate: .

[0129] Step 3: Calculate the packet loss rate occupancy ratio. The current measured packet loss rate is... Preset packet loss rate occupancy ratio: Current packet loss rate occupancy: .

[0130] Step 4: Calculate the overall score. Set the weight for latency evaluation. And packet loss rate evaluation weight The overall score is:

[0131]

[0132] Then, the link validity is determined: Set a uniform effective threshold for each link. and failure threshold Due to the current overall score of I2V links Therefore, this link is determined to be a fully valid link and can be used as the main transmission link to carry out the transmission of non-motorized vehicle collision warning messages.

[0133] Finally, the link scheduling output and model parameter update are as follows: Step 1: Link Scheduling Output. The communication middleware receives the "fully valid" determination result of the I2V link, sets the link as the primary transmission link, and allocates non-motorized vehicle collision warning messages according to normal priority; for other links determined to be available, the message allocation priority is reduced; for failed links, the allocation of current service messages is stopped.

[0134] Step 2: Historical Data Storage and Parameter Update. The roadside edge computing unit stores the measured latency, packet loss rate, vehicle speed, number of conflicting targets, service sensitivity, traffic condition correction coefficients, weights of each score, and the final score for this communication, and periodically uploads this data to the cloud platform. The cloud platform performs the following update operations based on the newly added historical data: updates the base latency and base packet loss rate using sliding window statistics and median update methods; updates the normalized mapping relationship, traffic condition influence weights, and score weights using regression fitting or gradient descent methods; and recalibrates the effective and ineffective thresholds based on the mean and standard deviation of the score distribution under natural conditions, achieving long-term continuous iterative optimization of model parameters.

[0135] This embodiment also provides a link transmission performance analysis device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0136] This embodiment provides a link transmission performance analysis device, such as... Figure 5 As shown, it includes: The acquisition module 51 is used to acquire the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and to collect the real-time traffic condition parameters of the target road segment at the current moment. The correction module 52 is used to calculate the traffic condition impact index based on real-time traffic condition parameters, and to correct the basic time delay based on the traffic condition impact index to obtain the time delay estimate. The calculation module 53 is used to obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, base packet loss rate, delay estimate and measured packet loss rate.

[0137] In this embodiment of the application, the acquisition module 51 is specifically used to collect latency samples and packet loss rate samples of the current candidate link in a single link communication; identify the stable traffic state of the target road segment as the preset traffic state, and record the target traffic condition parameters corresponding to the preset traffic state; based on the target traffic condition parameters, select candidate latency samples and candidate packet loss rate samples from the latency samples and packet loss rate samples respectively; use the median of the candidate latency samples as the base latency, and use the median of the candidate packet loss rate samples as the base packet loss rate.

[0138] In this application embodiment, the traffic condition parameters include at least one of the following parameters: vehicle operating speed, number of conflicting targets, and business sensitivity; The correction module 52 is specifically used to compare the first vehicle speed in the real-time traffic condition parameters with the second vehicle speed in the target traffic condition parameters, and normalize them using a preset speed mapping function to obtain a normalized vehicle speed value; and / or, to compare the first number of conflict targets in the real-time traffic condition parameters with the second number of conflict targets in the target traffic condition parameters, and normalize them using a preset conflict target number mapping function to obtain a normalized conflict target number value; and / or, to compare the first business sensitivity in the real-time traffic condition parameters with the second business sensitivity in the target traffic condition parameters, and normalize them using a preset business sensitivity mapping function to obtain a business sensitivity normalized value; and according to the preset influence weights corresponding to the normalized values ​​of each parameter, to perform a fusion calculation on the normalized vehicle speed value and / or the normalized conflict target number value and / or the normalized business sensitivity value to obtain a traffic condition influence index.

[0139] In this embodiment of the application, the correction module 52 is specifically used to add the traffic condition impact index to the preset benchmark value to obtain the traffic condition correction coefficient; and to multiply the base delay by the traffic condition correction coefficient to obtain the delay estimate.

[0140] In this embodiment, the calculation module 53 is specifically used to obtain the current allowed latency and the current allowed packet loss rate, and to obtain the allowed latency and the allowed packet loss rate under a preset state; to determine the preset state latency occupancy ratio based on the basic latency and the allowed latency under the preset state, and to determine the current latency occupancy ratio based on the latency estimate and the current allowed latency; to determine the preset state packet loss rate occupancy ratio based on the basic packet loss rate and the allowed packet loss rate under the preset state, and to determine the current packet loss rate occupancy ratio based on the measured packet loss rate and the current allowed packet loss rate; and to calculate the transmission performance score of the current candidate link based on the preset state latency occupancy ratio, the current latency occupancy ratio, the preset state packet loss rate occupancy ratio, the current packet loss rate occupancy ratio, and the preset scoring weight.

[0141] In this embodiment of the application, the device further includes: a determination module, configured to compare the transmission performance score with a preset valid threshold and a preset invalid threshold, wherein the preset invalid threshold is less than the preset valid threshold; if the transmission performance score is greater than or equal to the preset valid threshold, the current candidate link is determined to be a fully valid link; or, if the transmission performance score is greater than or equal to the preset invalid threshold and less than the preset valid threshold, the current candidate link is determined to be a conditionally available link; or, if the transmission performance score is less than the preset invalid threshold, the current candidate link is determined to be a failed link.

[0142] In this embodiment of the application, the device further includes: a configuration module, configured to, when multiple fully effective links exist, compare the current latency occupancy ratio of each fully effective link and select the fully effective link with the smallest current latency occupancy ratio as the main transmission link; issue a channel switching instruction through a communication middleware to configure the fully effective link as the first priority, the conditionally available link as the second priority, and the failed link as the third priority; wherein, the first priority is to allocate the current service awareness message according to a first allocation weight, the second priority is to allocate the current service awareness message according to a second allocation weight, and the third priority is to stop allocating the current service awareness message, and the first allocation weight is greater than the second allocation weight.

[0143] In this embodiment of the application, the device further includes: an update module, used to acquire measured data during the link communication process in the target road segment; based on the measured data, update the basic latency and basic packet loss rate under the preset traffic conditions, and / or update the preset influence weight used to calculate the traffic condition influence index, and / or update the preset scoring weight used to calculate the transmission performance score, and / or update the preset threshold used to determine the effectiveness of the link.

[0144] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 6 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system).

[0145] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GPA), or any combination thereof.

[0146] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0147] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0148] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0149] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0150] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0151] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for analyzing link transmission performance, characterized in that, The method includes: Obtain the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and collect the real-time traffic condition parameters of the target road segment at the current moment; The traffic condition impact index is calculated based on the real-time traffic condition parameters, and the base delay is corrected based on the traffic condition impact index to obtain the delay estimate. Obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, the base packet loss rate, the delay estimate, and the measured packet loss rate.

2. The method according to claim 1, characterized in that, The acquisition of the basic latency and basic packet loss rate of the current candidate link in the target road segment under a preset traffic condition includes: Collect latency samples and packet loss rate samples of the current candidate link in a single link communication; Identify a stable traffic state on the target road segment as the preset traffic state, and record the target traffic condition parameters corresponding to the preset traffic state; Based on the target traffic condition parameters, candidate delay samples and candidate packet loss rate samples are selected from the delay samples and the packet loss rate samples, respectively. The median of the candidate delay samples is used as the base delay, and the median of the candidate packet loss rate samples is used as the base packet loss rate.

3. The method according to claim 2, characterized in that, The traffic condition parameters include at least one of the following parameters: vehicle speed, number of conflict targets, and business sensitivity; The calculation of the traffic condition impact index based on the real-time traffic condition parameters includes: The first vehicle speed in the real-time traffic condition parameters is compared with the second vehicle speed in the target traffic condition parameters, and normalized using a preset speed mapping function to obtain a normalized vehicle speed value; and / or, The number of first conflict targets in the real-time traffic condition parameters is compared with the number of second conflict targets in the target traffic condition parameters, and normalized using a preset conflict target number mapping function to obtain a normalized value for the number of conflict targets; and / or, The first business sensitivity in the real-time traffic condition parameters is compared with the second business sensitivity in the target traffic condition parameters, and normalized by a preset business sensitivity mapping function to obtain a normalized business sensitivity value. The traffic condition impact index is obtained by fusing the normalized values ​​of the vehicle speed and / or the normalized values ​​of the number of conflicting targets and / or the normalized values ​​of the business sensitivity according to the preset impact weights corresponding to the normalized values ​​of the normalized values ​​of each parameter.

4. The method according to claim 1, characterized in that, The step of correcting the base delay based on the traffic condition impact index to obtain the delay estimate includes: The traffic condition impact index is added to a preset benchmark value to obtain the traffic condition correction coefficient. The estimated time delay is obtained by multiplying the base time delay by the traffic condition correction factor.

5. The method according to claim 1, characterized in that, The step of calculating the transmission performance score of the current candidate link based on the base delay, the base packet loss rate, the estimated delay, and the measured packet loss rate includes: Get the current allowed latency and the current allowed packet loss rate, and get the allowed latency and the allowed packet loss rate under the preset state; Based on the base latency and the allowed latency under the preset state, the latency occupancy ratio under the preset state is determined, and based on the latency estimate and the current allowed latency, the current latency occupancy ratio is determined. Based on the base packet loss rate and the allowed packet loss rate under the preset state, determine the packet loss rate occupancy ratio under the preset state, and based on the measured packet loss rate and the current allowed packet loss rate, determine the current packet loss rate occupancy ratio. The transmission performance score of the current candidate link is calculated based on the preset state delay occupancy ratio, the current delay occupancy ratio, the preset state packet loss rate occupancy ratio, the current packet loss rate occupancy ratio, and the preset scoring weight.

6. The method according to claim 5, characterized in that, After calculating the transmission performance score of the current candidate link, the method further includes: The transmission performance score is compared with a preset valid threshold and a preset invalid threshold, wherein the preset invalid threshold is less than the preset valid threshold; If the transmission performance score is greater than or equal to the preset valid threshold, the current candidate link is determined to be a fully valid link; or, if the transmission performance score is greater than or equal to the preset invalid threshold and less than the preset valid threshold, the current candidate link is determined to be a conditionally available link; or, if the transmission performance score is less than the preset invalid threshold, the current candidate link is determined to be a failed link.

7. The method according to claim 6, characterized in that, The method further includes: When there are multiple fully effective links, the current latency occupancy ratio of each fully effective link is compared, and the fully effective link with the smallest current latency occupancy ratio is selected as the main transmission link. The communication middleware issues a channel switching command to configure the fully effective link as the first priority, the conditionally available link as the second priority, and the failed link as the third priority. Wherein, the first priority is to allocate the current business awareness message according to the first allocation weight, the second priority is to allocate the current business awareness message according to the second allocation weight, and the third priority is to stop allocating the current business awareness message, wherein the first allocation weight is greater than the second allocation weight.

8. The method according to claim 1, further comprising: Obtain measured data during the link communication process in the target road segment; Based on the measured data, update the base latency and base packet loss rate under the preset traffic conditions, and / or update the preset impact weights used to calculate the traffic condition impact index, and / or update the preset scoring weights used to calculate the transmission performance score, and / or update the preset thresholds used to determine the link effectiveness.

9. A link transmission performance analysis device, characterized in that, The device includes: The acquisition module is used to acquire the basic latency and basic packet loss rate of the current candidate link in the target road segment under the preset traffic conditions, and to collect the real-time traffic condition parameters of the target road segment at the current moment. The correction module is used to calculate the traffic condition impact index based on the real-time traffic condition parameters, and to correct the base delay based on the traffic condition impact index to obtain the delay estimate. The calculation module is used to obtain the measured packet loss rate of the current candidate link, and calculate the transmission performance score of the current candidate link based on the base delay, the base packet loss rate, the delay estimate and the measured packet loss rate.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to perform the method of any one of claims 1 to 8.

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