# Multisignal Cooperative Processing Method for Internet of Vehicles Based on Data-Driven Edge Computing Method

Authors: Lei Wang
Journal: Security and Communication Networks
 (2022)

---

## Abstract

With the rapid development of Internet of Vehicles applications, more and more data are generated. How to effectively distribute content in the Internet of Vehicles to meet the service quality requirements of users has become one of the industry pain points in the field of smart cars and autonomous driving. In order to solve the shortage of local computing resources of vehicles, a vehicle edge network is proposed, which uses data-driven edge computing to offload vehicle tasks to a mobile edge computing server to reduce overall network energy consumption and meet task latency requirements. In addition, in order to reduce the end-to-end delay, caching technology is adopted at the network edge, which can reduce the content transmission delay. This paper focuses on the problem of computing offloading in the data-driven edge computing method in the context of the Internet of Vehicles. Simulation experiments have proved its superiority compared with the traditional offloading method, and the delay and energy consumption are better than the traditional method. First, the basic concepts of the Internet of Vehicles and MEC are introduced; second, the TOAI algorithm flow chart and the computing tasks of the offloading work of the Internet of Vehicles are introduced; then, based on MEC and partial offloading, the task offloading problem is modeled and solved; the problem of unloading collaborative content under networking is solved, and the simulation results are analyzed and verified. The simulation experiment not only shows that the proposed algorithm optimizes the efficiency of the task under the average unit but also shows the effectiveness of this method, which lays a foundation for the engineering implementation of the algorithm. The experimental results show that the average task completion rate is increased by 0.58%, and the average unit task energy consumption is increased by 0.32%, which improves the practicability of the system.


---

## Body

## 1. Introduction

With the rapid development of Internet of things and wireless communication technology, automobile has become an important mobile device connected to the Internet. As an indispensable part of modern life, automobile has brought unprecedented convenience and freedom to mankind and narrowed the geographical distance of people all over the world [1]. Vehicles can run a variety of computing intensive applications, such as image aided navigation, intelligent vehicle control, traffic management, in car entertainment, and augmented reality. These computing intensive applications not only require a lot of computing resources to process complex data but also have strict requirements for time delay [2]. As a typical application of the automotive industry in the Internet of things, the Internet of vehicles is an intelligent transportation system with great potential. Vehicles interact with other vehicles, people, road facilities, and other information through various modules with communication, perception, calculation, and storage functions, so as to form the Internet of vehicles and intelligent transportation system [3]. Provide vehicle users with low delay and high reliability services, improve traffic efficiency, and reduce traffic congestion and accidents. The handling intelligence and service diversity of automobiles have become the development direction of many automobile manufacturers [4]. For example, Tesla's electric vehicle series and BYD have installed advanced on-board intelligent terminals and interactive screens. With the support of advanced hardware foundations such as on-board embedded mobile processors, it is possible for many previously unimaginable on-board applications to be installed in today's smart cars. Under this background, the automatic driving technology of vehicles has also developed rapidly [5]. However, due to the high mobility of vehicles, the underlying topology of the Internet of vehicles and wireless links are highly dynamic. The traditional network architecture cannot meet the business needs of the Internet of vehicles due to its static, unitary, and high delay limitations [6]. Some vehicles with limited resources cannot provide enough computing resources to meet the needs of some applications. They often have more stringent requirements on computing resources and processing delay. How to solve the problem of insufficient resources in the Internet of vehicles has become an important challenge for the multisignal collaborative processing of the Internet of vehicles [7]. The unloading of computing tasks in edge computing is a key research issue, that is, whether computing tasks should be executed locally or unloaded to edge nodes or the cloud. Different task unloading schemes have a great impact on task completion delay and mobile device energy consumption.This paper focuses on the problem of computing offload in the data-driven edge computing method under the background of the Internet of vehicles. Simulation experiments show that it is superior to the traditional offload method in terms of time delay and energy consumption. First, this paper introduces the basic concepts of the Internet of vehicles and MEC and divides the tasks into two types: unloaded subtasks and nonunloaded subtasks according to the task attributes; second, this paper introduces the flow chart of TOAI algorithm and the computing tasks of the unloading work of the Internet of vehicles and proposes a computing resource allocation method to realize the computing resource allocation of the unloading tasks of vehicles by MEC server; then, based on MEC and partial unloading, the problem of task unloading is modeled and solved; finally, the problem of unloading collaborative content under the Internet of vehicles is solved, and the simulation results are analyzed and verified.Based on the data-driven edge calculation method, this paper studies the multisignal cooperative processing method of vehicle networking. Its innovations are as follows:(1)
Using data-driven edge algorithm, according to the requirements of different tasks, the task unloading is completed by multirelay-assisted computing unloading strategy. It can effectively relieve the calculation pressure at the overloaded MEC server, improve the scalability of MEC, and optimize the total task processing delay of intelligent vehicle group.(2)
This algorithm can keep the queue of computing nodes in the system stable and meet the requirements of deadline and minimize the average execution energy consumption of vehicle users in the system. Compared with the traditional local computing method, the unloading of computing tasks alleviates the lack of computing power of vehicles, reduces the time delay of task execution, and reduces the energy consumption of vehicles.(3)
The algorithm realizes the sharing of computing resources of all MEC servers, which makes the load of each MEC server in the system more balanced, improves the processing efficiency of all tasks in the whole vehicle networking system, and realizes the calculation of vehicle tasks in the system with the minimum cost.The research is divided into five sections. The first section describes the development background of the Internet of vehicles and wireless communication technology. The basic concepts of Internet of vehicles and MEC are introduced. The second section introduces and analyzes the flow chart of TOAI algorithm and the calculation task of the unloading work of the Internet of vehicles. The related research is analyzed. In Section3, the relevant technologies of the Internet of vehicles are analyzed. The establishment of system model based on data-driven edge computing method is described. Based on MEC and partial unloading, the task unloading problem is modeled and solved. The problem of collaborative content unloading in network environment is solved, and the simulation results are analyzed and verified. Section 4 analyzes the simulation results. Experiments show that the algorithm not only optimizes the efficiency of the task under the average unit. The validity of the method is proved, which lays a foundation for the engineering implementation of the algorithm.


## 2. Related Work

Mobile computing is the extension and redevelopment of mobile cloud. Due to the requirements of low latency, high bandwidth, and high reliability of Internet of Vehicles, deploying servers near the edge of users has become a better choice than the cloud [8]. In MEC architecture, because the vehicle is closer to the edge server both logically and practically, the unloading delay is greatly reduced compared with cloud computing, and the pressure on the network transmission bandwidth is also greatly reduced for the short transmission distance [9]. Because of the superiority of data-driven edge computing, the research on it is also hot in recent years. According to different application scenarios and requirements, the research results in recent years are also different. Ge et al. put forward an energy-saving resource allocation scheme in MEC offloading service and established a time-delay constraint model of vehicle speed perception by using different vehicle speeds and task types. Then, the time delay and energy cost required for joint execution in local terminal and MEC server were calculated and then a joint optimization scheme of task offloading and resource allocation was formulated [10]. Puthal et al. put forward a multiobjective optimization problem of computing offload in fog computing environment. Combined with energy consumption and delay optimization, a framework of MEC calculation unloading and resource allocation is proposed. To solve the problem of long time delay caused by unloading vehicle-mounted tasks to cloud servers, this paper studies a task unloading algorithm, which can effectively optimize task delay and computing resource consumption in multiuser and multiserver vehicle edge computing scenarios. In order to reduce the time complexity, a hybrid intelligent optimization algorithm based on genetic algorithm and heuristic rules is proposed. A lot of simulations show that this algorithm can effectively reduce the task processing delay [11]. Wu et al. put forward task allocation and frequency scaling to achieve the best service in MEC uninstallation. A computational offload framework that offloads tasks from a single mobile device to multiple MEC servers aims to minimize the task processing delay and energy consumption of mobile devices by jointly optimizing task allocation decisions and CPU frequency of mobile devices [12]. Aiming at the selection of server nodes in the process of D task unloading, the resource scheduling problem of single and multiple objective functions is considered, and a heuristic algorithm is developed. However, due to the complexity of data dependency, a knowledge-driven service unloading decision framework based on Internet of Vehicles is proposed. In order to save the energy consumption of on-board equipment, under the scenario of multicore server MEC, the delay and energy consumption of the system are optimized by Lyapunov optimization method [13]. Ning et al., in order to meet the needs of IoT equipment, find a balanced scheme between energy consumption and delay. The problem is transformed into a multiobjective optimization problem, and the improved NSGA-II; is used to search the optimal solution. By considering the local cost and limited communication and computing resources, the migration decision is regarded as a multilabel classification problem, and the deep learning method is used to minimize the computing and unloading consumption [14]. Lv et al. put forward an energy-saving resource allocation algorithm based on alternating direction multiplier method, which transforms the original problem into an equivalent problem with separable objectives and constraints. By considering cloud migration strategy, computing task allocation, and CPU processing speed, computing tasks are migrated to minimize energy consumption. Combining optimization decision with computing resource allocation in VEC can effectively reduce the energy consumption of on-board equipment [15].Although scholars have done extensive research on the advantages of data-driven edge computing in the Internet of Vehicles, its development still faces some challenges, among which there are many issues worthy of study. After in-depth research on the extreme unloading of IoV intelligent terminals, this paper finds that for the same road section or similar areas, there are always many repetitive computing tasks when performing tasks such as augmented reality and video processing. Therefore, considering the waste of server resources, this paper designs a multisignal cooperative processing strategy based on the data-driven edge computing method. From the user's point of view, this method saves task processing delay; from the MEC's point of view, it greatly saves computing resources and reduces device energy consumption. This paper also considers the constraint relationship between the pricing strategy and the payment ability of smart vehicles and proposes a collaborative scheduling algorithm to select the best computing offloading method for users. Finally, it is proved by simulation that the strategy designed in this paper can effectively reduce the total delay of computing task offloading of smart cars in the Internet of Vehicles.


## 3. Methodology

### 3.1. Overview of Internet of Vehicles-Related Technologies

The Internet of Vehicles provides a safer and more convenient transportation environment through the interoperability and interconnection between smart cars and auxiliary devices. However, the rapid growth of connected vehicles will become a bottleneck for the development of the Internet of Vehicles. One of the main problems of the Internet of Vehicles is the limited ability to process information. It is difficult for the on-board unit of a smart car to process the information collected by itself and other related devices (such as sensors in the road environment) [16]. Uncontrollable data such as vehicle driving and road mapping may even affect national security. The development of intelligent automobile and networking is inexorable in the future. In the future, the security system of the Internet of vehicles should be considered from a personal point of view and will not be afraid to ride smart cars because of concerns about network security, including driverless cars. Second, considering from the national level, vehicles will not be allowed to enter or leave important places or military sites because of the sensor devices used by vehicles. As a component of the Internet of Things (IOT), the Internet of Vehicles has played an important role in increasing driving safety and improving road traffic. However, due to the advent of the Internet of Everything era and the rapid increase in the number of vehicles, more and more in-vehicle applications and the generation of large amounts of data have brought new challenges to the Internet of Vehicles: how to provide a more reliable and effective in-vehicle content distribution service to meet the needs of users, requirements [17]. In order to solve this problem, the vehicle edge network is a feasible paradigm, that is, the integration of mobile edge computing and the Internet of Vehicles, with its advantages, help the development of vehicle network. With the rise of the Internet of vehicles, the vehicle intelligent terminal market has developed rapidly. With the development and popularization of 4G network, it is more and more popular to use smart phones to control on-board intelligent terminals to control cars.As shown in Figure1, the vehicle edge network can be divided into the following parts.Figure 1
Structure diagram of vehicle edge network.(1) The vehicle node layer is mainly composed of intelligent vehicles with sensing, computing, storage, and communication capabilities. The vehicle itself deploys a large number of sensing devices, such as cameras, GPS, and radar, which can detect and collect data information of the body and the surrounding environment; the vehicle nodes can locally process some computing tasks to meet the delay requirements; the vehicle nodes are installed with on-board units communication modules such as V2I, V2V, and V2X can exchange data with roadside infrastructure such as base stations or neighboring vehicles through V2I, V2V, V2X, and other communication methods; vehicle nodes can store part of the content, and in the V2V stage, as a content provider to distribute content to further expand content Scope of distribution. (2) Mobile edge server layer: the edge service layer mainly includes drones, parked vehicles, pedestrians, and buildings. These nodes may be in a stationary state or in a moving state and can receive requests from vehicle nodes, process them, or upload them to the infrastructure layer processing. (3) Infrastructure layer: the infrastructure layer mainly includes base stations equipped with edge computing servers, macro base stations, and roadside units (RSUs). Compared with vehicle nodes, it has higher computing and storage capabilities and is close to vehicle nodes. It can process most of the delay-sensitive vehicle requests and return the processing results. (4) Cloud server layer: the cloud service layer is composed of cloud services. It has extremely complex computing and processing capabilities, can process massive data and various service requests in parallel, and play the role of central control [18].In IOV, the vehicle collects various information in real time through its own sensors, radio frequency identification system, and other equipment and communicates with other vehicles or roadside equipment. IOV will realize the real-time information transmission of vehicle to people (V2P), vehicle to vehicle (V2V), and vehicle to infrastructure (V2I) to ensure the safety, intelligence, and convenience of the traffic environment. The most important thing is to improve the safety of the vehicle driving environment. Figure2 shows vehicle wireless communication diagram.Figure 2
Schematic diagram of vehicle wireless communication.As a key technology in 5G era, MEC has always been a key research direction in academia and industry. At present, microcloud and fog computing technologies are similar to MEC. Microcloud is a new network architecture, which is a combination of mobile computing and cloud computing technology. It is the middle layer of the three-layer network architecture composed of mobile terminals, microcloud and cloud. Microcloud technology is dedicated to ultra-low delay transmission of tasks. Compared with fog computing and MEC, microcloud is mainly used in mobile enhancement to supplement sufficient computing resources for mobile devices [19]. In addition, microcloud can run directly on mobile terminals (such as vehicles and aircraft). Fog computing technology refers to the distribution of computing, control, and storage resources to users or system devices close to users, so as to extend cloud computing resources to the edge network. The concepts of MEC, microcloud and fog computing are similar. Their basic idea is to migrate cloud computing resources to edge networks, so they all belong to the category of edge computing [20]. The three have only minor differences in some details, and their differences are summarized as shown in Table 1.Table 1
Differences between MEC, fog computing, and microcloud.
ComparedMECMicrocloudZero calculationDeployment locationNetwork edgeAt the edge of the network or running on the terminalNetwork edgeContext awarenessHighLowMediumProximityOne or more jumpsA jumpA jumpCommunication rangeSecondarySmallSmallApplication awarenessSupportNot supported by itselfSupportCollaboration—NoPartial collaborationBusiness application scenariosAR/VR, internet of things, internet of vehiclesInternet of thingsInternet of thingsIn the Internet of Vehicles, the main function of MEC is to provide computing resources and storage space for vehicles. These functions enable the combination of MEC and the Internet of Vehicles to achieve real-time and efficient processing of information. The MEC server is deployed on the base station or RSU side. Compared with cloud computing, the MEC server is deployed closer to the vehicle, making it easier and faster to provide localized services to vehicle users. The task vehicle connects with the base station or RSU through V2I communication and sends computing tasks. After receiving the computing tasks, the road infrastructure directly transmits them to the nearby MEC server through wired connections. The MEC server allocates computing resources and processes the tasks. The calculation result is returned to the mission vehicle through the RSU or the base station. In a cooperative relay system, the relay nodes are not dedicated to relaying, these nodes also transmit their own information. Whether the wireless mesh network based on layer 2 or layer 3, its essence is a multihop network. The communication quality, reliability, and efficiency between two adjacent nodes are the basis to ensure the excellent performance of wireless mesh networks. Cooperative relay technology can make full use of the information of multihop path from the source node to the destination node. Furthermore, it can improve the performance of the wireless link between the source node and the destination node, so as to meet the communication quality requirements between the two nodes of the wireless mesh network. The forwarding of other information is on a voluntary basis, a voluntary concept also known as collaborative diversity or collaborative diversity. In cooperative relay, each node can be a source and or a relay node. There are two types of relay nodes standardized by 3GPP : I-type and II-type. Their comparison is shown in Table2:Table 2
Relay node type table.
CharacteristicＩ- typeＩI- typeRelay modeIn-band/out-of-band transmissionIn-band transmissionHas its own physical cell identification.Yes, for coverage expansion.NoApplication scenarioUsed for transmitting synchronization signals and resource allocationWhich is used for improving the throughput and service quality of user equipmentCommunication modeHalf duplex/full duplexHalf-duplexRealizeComplex and costly.Simple and low cost.The relay transmission strategy in the Internet of Vehicles is a practical solution to make full use of cooperative relay technology. A relay technique that avoids excessive resource usage is called opportunistic relay selection or optimal relay selection. In ORS, the source node inquiries about the available equipment by broadcasting, and the transceiver terminal and the relay node establish a communication connection after exchanging the channel state information. The process involves parsing the CSI and selecting the repeater that meets the requirements. The centralized/distributed algorithm acts on the repeater selection process to assist in the end-to-end information transmission. In order to reduce the excessive use of channel resources, the selected relay device uses one channel to complete data communication.


### 3.2. System Model Establishment Based on Data-Driven Edge Computing Method

Aiming at the problem of task interruption due to real-time changes in-vehicle speed in mobile edge computing IoV scenarios, a task offloading strategy to avoid cross-region interruption of nonuniform vehicles in IoV is proposed. The strategy adopts the mechanism of task segmentation. Under the condition of satisfying the delay constraint, according to the initial speed of the vehicle entering the cell, the vehicle's residence time in the cell is estimated, and then according to the task request, the server allocates resources to the in-vehicle equipment. According to the obtained server resources, the corresponding amount of tasks to be processed is offloaded to the server for processing. Therefore, a computing task offloading strategy to avoid transmission interruption in the Internet of Vehicles is proposed. According to the speed of the vehicle entering the cell, the residence time of the vehicle in the cell is estimated. The number of task units that should be processed so that the server allocates server resources to its on-board equipment. The specific steps of the TOAI scheme are shown in Figure3:Figure 3
TOAI algorithm flow chart.In the vehicle networking model, DSRC technology can be adopted. Vehicles communicate with RSU through V2I, and MEC servers are deployed in RSU, which can provide computing resources for vehicle tasks, reduce task processing delay, reduce vehicle energy consumption, and save battery power. The task unloading decision of vehicle will change dynamically with time. For the convenience of analysis, it is assumed that the coverage of roadside units is the whole road in the current cell, and the coverage of base stations in each cell does not overlap, and its size is determined by the transmission power of RSU. Because its coverage is small, the calculation task may need to go through multiple cells to complete. This group of vehicles can be represented asI=1,2,…,i, the edge server can be represented as M=1,2,…,m, the task unloading times of on-board equipment in a single cell can be represented as J=1,2,…,j, assuming that Si represents the size of on-board tasks, Ni represents the number of units to be processed after task segmentation, and U represents the data size of each task cell:(1)Ni=SiU.When a vehicle enters the community, its position information, speed information, and the remaining distance out of the community can be obtained in real time by the control center. The vehicle retention timeτij, lij indicates the remaining distance out of the community, and vi indicates the current speed of the vehicle. The required server resource fij is allocated for the vehicle initiating the task request:(2)fij=αi⋅nij⋅U/β1⋅β2⋅nij⋅Uτij−Rij.When the vehicle-mounted equipment unloads the computing task unitnij to the MEC server for execution, the corresponding transmission delay tijup will be generated when the task is transmitted through the wireless network:(3)tijup=β1⋅β2⋅nij⋅URij,Bi represents the bandwidth, and Pt represents the transmission power of data transmission of vehicle-mounted equipment. The vehicle-mounted equipment unloads the task to the MEC server, and the required computing resources are αi⋅nij⋅U. The MEC server allocates the computing capacity fij of a single vehicle, and the processing delay tijex executed by the MEC server is(4)tijex=ℓji⋅αi⋅nij⋅URij.The task of the vehicle generated at momentt consists of two different subtasks. Among them, the nonunloadable subtasks can only be executed locally in the vehicle, and the unloadable subtasks are determined by the unloading decision and are executed locally or unloaded to the MEC server M for execution. The decision vector indicates the proportion of the number of unloaded subtasks to the total number of unloaded subtasks. Unloadable subtasks are unloaded to MEC server M for execution, and the rest of the unloaded subtasks are executed locally in the vehicle, that is, partial unloading mode. The subtask unloading decision and execution process is shown in Figure 4:Figure 4
Decision and execution process of subtask unloading.Considering that the sum of the upload delay of MEC server, the task processing delay and the waiting delaytiw of vehicles waiting for the server to allocate computing resources is regarded as the task completion delay, because the number of task processing results is small, its return delay can be ignored, and the delay of vehicles performing tasks in this community is Li:(5)Li=∑j=1Jtijup+∑jtijex+tiw.The fading factor of RSU’s uplink channel is represented byh, the Gaussian noise power is represented by n0, and the transmission data efficiency of vehicle i's upload calculation task in the j th cycle is represented by Cij with the relation of d:(6)Cij=Bi⋅log1+Pt⋅dij−r⋅h2n0.In order to optimize the server stability and realize the fairness of vehicles, the standard deviation of task completion rate is used to measure it. UseXi to indicate the task completion rate of a single vehicle:(7)Xi=∑i=1iNij.Usex− to indicate the average task completion rate of all vehicles:(8)x−=∑i=1tNir∑i=1INi.If the vehicle leaves the community or the task has been processed, it is deemed that the current vehicle task is processed and the server resources are released. According to the actual residence time of vehicles in the community, calculate the number of task unitsNir completed in the community. The objective function is(9)min∑i=1ILi∑i=1INri.


## 3.1. Overview of Internet of Vehicles-Related Technologies

The Internet of Vehicles provides a safer and more convenient transportation environment through the interoperability and interconnection between smart cars and auxiliary devices. However, the rapid growth of connected vehicles will become a bottleneck for the development of the Internet of Vehicles. One of the main problems of the Internet of Vehicles is the limited ability to process information. It is difficult for the on-board unit of a smart car to process the information collected by itself and other related devices (such as sensors in the road environment) [16]. Uncontrollable data such as vehicle driving and road mapping may even affect national security. The development of intelligent automobile and networking is inexorable in the future. In the future, the security system of the Internet of vehicles should be considered from a personal point of view and will not be afraid to ride smart cars because of concerns about network security, including driverless cars. Second, considering from the national level, vehicles will not be allowed to enter or leave important places or military sites because of the sensor devices used by vehicles. As a component of the Internet of Things (IOT), the Internet of Vehicles has played an important role in increasing driving safety and improving road traffic. However, due to the advent of the Internet of Everything era and the rapid increase in the number of vehicles, more and more in-vehicle applications and the generation of large amounts of data have brought new challenges to the Internet of Vehicles: how to provide a more reliable and effective in-vehicle content distribution service to meet the needs of users, requirements [17]. In order to solve this problem, the vehicle edge network is a feasible paradigm, that is, the integration of mobile edge computing and the Internet of Vehicles, with its advantages, help the development of vehicle network. With the rise of the Internet of vehicles, the vehicle intelligent terminal market has developed rapidly. With the development and popularization of 4G network, it is more and more popular to use smart phones to control on-board intelligent terminals to control cars.As shown in Figure1, the vehicle edge network can be divided into the following parts.Figure 1
Structure diagram of vehicle edge network.(1) The vehicle node layer is mainly composed of intelligent vehicles with sensing, computing, storage, and communication capabilities. The vehicle itself deploys a large number of sensing devices, such as cameras, GPS, and radar, which can detect and collect data information of the body and the surrounding environment; the vehicle nodes can locally process some computing tasks to meet the delay requirements; the vehicle nodes are installed with on-board units communication modules such as V2I, V2V, and V2X can exchange data with roadside infrastructure such as base stations or neighboring vehicles through V2I, V2V, V2X, and other communication methods; vehicle nodes can store part of the content, and in the V2V stage, as a content provider to distribute content to further expand content Scope of distribution. (2) Mobile edge server layer: the edge service layer mainly includes drones, parked vehicles, pedestrians, and buildings. These nodes may be in a stationary state or in a moving state and can receive requests from vehicle nodes, process them, or upload them to the infrastructure layer processing. (3) Infrastructure layer: the infrastructure layer mainly includes base stations equipped with edge computing servers, macro base stations, and roadside units (RSUs). Compared with vehicle nodes, it has higher computing and storage capabilities and is close to vehicle nodes. It can process most of the delay-sensitive vehicle requests and return the processing results. (4) Cloud server layer: the cloud service layer is composed of cloud services. It has extremely complex computing and processing capabilities, can process massive data and various service requests in parallel, and play the role of central control [18].In IOV, the vehicle collects various information in real time through its own sensors, radio frequency identification system, and other equipment and communicates with other vehicles or roadside equipment. IOV will realize the real-time information transmission of vehicle to people (V2P), vehicle to vehicle (V2V), and vehicle to infrastructure (V2I) to ensure the safety, intelligence, and convenience of the traffic environment. The most important thing is to improve the safety of the vehicle driving environment. Figure2 shows vehicle wireless communication diagram.Figure 2
Schematic diagram of vehicle wireless communication.As a key technology in 5G era, MEC has always been a key research direction in academia and industry. At present, microcloud and fog computing technologies are similar to MEC. Microcloud is a new network architecture, which is a combination of mobile computing and cloud computing technology. It is the middle layer of the three-layer network architecture composed of mobile terminals, microcloud and cloud. Microcloud technology is dedicated to ultra-low delay transmission of tasks. Compared with fog computing and MEC, microcloud is mainly used in mobile enhancement to supplement sufficient computing resources for mobile devices [19]. In addition, microcloud can run directly on mobile terminals (such as vehicles and aircraft). Fog computing technology refers to the distribution of computing, control, and storage resources to users or system devices close to users, so as to extend cloud computing resources to the edge network. The concepts of MEC, microcloud and fog computing are similar. Their basic idea is to migrate cloud computing resources to edge networks, so they all belong to the category of edge computing [20]. The three have only minor differences in some details, and their differences are summarized as shown in Table 1.Table 1
Differences between MEC, fog computing, and microcloud.
ComparedMECMicrocloudZero calculationDeployment locationNetwork edgeAt the edge of the network or running on the terminalNetwork edgeContext awarenessHighLowMediumProximityOne or more jumpsA jumpA jumpCommunication rangeSecondarySmallSmallApplication awarenessSupportNot supported by itselfSupportCollaboration—NoPartial collaborationBusiness application scenariosAR/VR, internet of things, internet of vehiclesInternet of thingsInternet of thingsIn the Internet of Vehicles, the main function of MEC is to provide computing resources and storage space for vehicles. These functions enable the combination of MEC and the Internet of Vehicles to achieve real-time and efficient processing of information. The MEC server is deployed on the base station or RSU side. Compared with cloud computing, the MEC server is deployed closer to the vehicle, making it easier and faster to provide localized services to vehicle users. The task vehicle connects with the base station or RSU through V2I communication and sends computing tasks. After receiving the computing tasks, the road infrastructure directly transmits them to the nearby MEC server through wired connections. The MEC server allocates computing resources and processes the tasks. The calculation result is returned to the mission vehicle through the RSU or the base station. In a cooperative relay system, the relay nodes are not dedicated to relaying, these nodes also transmit their own information. Whether the wireless mesh network based on layer 2 or layer 3, its essence is a multihop network. The communication quality, reliability, and efficiency between two adjacent nodes are the basis to ensure the excellent performance of wireless mesh networks. Cooperative relay technology can make full use of the information of multihop path from the source node to the destination node. Furthermore, it can improve the performance of the wireless link between the source node and the destination node, so as to meet the communication quality requirements between the two nodes of the wireless mesh network. The forwarding of other information is on a voluntary basis, a voluntary concept also known as collaborative diversity or collaborative diversity. In cooperative relay, each node can be a source and or a relay node. There are two types of relay nodes standardized by 3GPP : I-type and II-type. Their comparison is shown in Table2:Table 2
Relay node type table.
CharacteristicＩ- typeＩI- typeRelay modeIn-band/out-of-band transmissionIn-band transmissionHas its own physical cell identification.Yes, for coverage expansion.NoApplication scenarioUsed for transmitting synchronization signals and resource allocationWhich is used for improving the throughput and service quality of user equipmentCommunication modeHalf duplex/full duplexHalf-duplexRealizeComplex and costly.Simple and low cost.The relay transmission strategy in the Internet of Vehicles is a practical solution to make full use of cooperative relay technology. A relay technique that avoids excessive resource usage is called opportunistic relay selection or optimal relay selection. In ORS, the source node inquiries about the available equipment by broadcasting, and the transceiver terminal and the relay node establish a communication connection after exchanging the channel state information. The process involves parsing the CSI and selecting the repeater that meets the requirements. The centralized/distributed algorithm acts on the repeater selection process to assist in the end-to-end information transmission. In order to reduce the excessive use of channel resources, the selected relay device uses one channel to complete data communication.


## 3.2. System Model Establishment Based on Data-Driven Edge Computing Method

Aiming at the problem of task interruption due to real-time changes in-vehicle speed in mobile edge computing IoV scenarios, a task offloading strategy to avoid cross-region interruption of nonuniform vehicles in IoV is proposed. The strategy adopts the mechanism of task segmentation. Under the condition of satisfying the delay constraint, according to the initial speed of the vehicle entering the cell, the vehicle's residence time in the cell is estimated, and then according to the task request, the server allocates resources to the in-vehicle equipment. According to the obtained server resources, the corresponding amount of tasks to be processed is offloaded to the server for processing. Therefore, a computing task offloading strategy to avoid transmission interruption in the Internet of Vehicles is proposed. According to the speed of the vehicle entering the cell, the residence time of the vehicle in the cell is estimated. The number of task units that should be processed so that the server allocates server resources to its on-board equipment. The specific steps of the TOAI scheme are shown in Figure3:Figure 3
TOAI algorithm flow chart.In the vehicle networking model, DSRC technology can be adopted. Vehicles communicate with RSU through V2I, and MEC servers are deployed in RSU, which can provide computing resources for vehicle tasks, reduce task processing delay, reduce vehicle energy consumption, and save battery power. The task unloading decision of vehicle will change dynamically with time. For the convenience of analysis, it is assumed that the coverage of roadside units is the whole road in the current cell, and the coverage of base stations in each cell does not overlap, and its size is determined by the transmission power of RSU. Because its coverage is small, the calculation task may need to go through multiple cells to complete. This group of vehicles can be represented asI=1,2,…,i, the edge server can be represented as M=1,2,…,m, the task unloading times of on-board equipment in a single cell can be represented as J=1,2,…,j, assuming that Si represents the size of on-board tasks, Ni represents the number of units to be processed after task segmentation, and U represents the data size of each task cell:(1)Ni=SiU.When a vehicle enters the community, its position information, speed information, and the remaining distance out of the community can be obtained in real time by the control center. The vehicle retention timeτij, lij indicates the remaining distance out of the community, and vi indicates the current speed of the vehicle. The required server resource fij is allocated for the vehicle initiating the task request:(2)fij=αi⋅nij⋅U/β1⋅β2⋅nij⋅Uτij−Rij.When the vehicle-mounted equipment unloads the computing task unitnij to the MEC server for execution, the corresponding transmission delay tijup will be generated when the task is transmitted through the wireless network:(3)tijup=β1⋅β2⋅nij⋅URij,Bi represents the bandwidth, and Pt represents the transmission power of data transmission of vehicle-mounted equipment. The vehicle-mounted equipment unloads the task to the MEC server, and the required computing resources are αi⋅nij⋅U. The MEC server allocates the computing capacity fij of a single vehicle, and the processing delay tijex executed by the MEC server is(4)tijex=ℓji⋅αi⋅nij⋅URij.The task of the vehicle generated at momentt consists of two different subtasks. Among them, the nonunloadable subtasks can only be executed locally in the vehicle, and the unloadable subtasks are determined by the unloading decision and are executed locally or unloaded to the MEC server M for execution. The decision vector indicates the proportion of the number of unloaded subtasks to the total number of unloaded subtasks. Unloadable subtasks are unloaded to MEC server M for execution, and the rest of the unloaded subtasks are executed locally in the vehicle, that is, partial unloading mode. The subtask unloading decision and execution process is shown in Figure 4:Figure 4
Decision and execution process of subtask unloading.Considering that the sum of the upload delay of MEC server, the task processing delay and the waiting delaytiw of vehicles waiting for the server to allocate computing resources is regarded as the task completion delay, because the number of task processing results is small, its return delay can be ignored, and the delay of vehicles performing tasks in this community is Li:(5)Li=∑j=1Jtijup+∑jtijex+tiw.The fading factor of RSU’s uplink channel is represented byh, the Gaussian noise power is represented by n0, and the transmission data efficiency of vehicle i's upload calculation task in the j th cycle is represented by Cij with the relation of d:(6)Cij=Bi⋅log1+Pt⋅dij−r⋅h2n0.In order to optimize the server stability and realize the fairness of vehicles, the standard deviation of task completion rate is used to measure it. UseXi to indicate the task completion rate of a single vehicle:(7)Xi=∑i=1iNij.Usex− to indicate the average task completion rate of all vehicles:(8)x−=∑i=1tNir∑i=1INi.If the vehicle leaves the community or the task has been processed, it is deemed that the current vehicle task is processed and the server resources are released. According to the actual residence time of vehicles in the community, calculate the number of task unitsNir completed in the community. The objective function is(9)min∑i=1ILi∑i=1INri.


## 4. Result Analysis and Discussion

The comparison scheme ATOS adopted in this chapter considers the change of vehicle speed. Although the strategy idealizes the change of speed, even if the speed between different cells is changed, the vehicle speed inside the cell is idealized. The vehicle enters the cell at a uniform speed until it leaves the cell. According to the initial speed of the vehicle entering the cell, the residence time of the vehicle in the cell is calculated, so as to unload the corresponding task quantity. Comparison scheme: the task segmentation mechanism adopted by TOAI can more accurately determine which tasks need to be unloaded and estimate the retention time of the vehicle in the cell according to the current vehicle speed. If the retention time of the vehicle is long, the vehicle can make full use of the server resources to unload again. If the vehicle travels faster, the vehicle can obtain the calculated task results before leaving the cell. Unfinished tasks will be processed in the next cell. With the increase of arrival rate, the average number of completed task units decreases. The relationship between the average number of completed task units and different arrival rates is shown in Figure5:Figure 5
Average number of completed task units.The reason why the average number of task units completed gradually decreases is that when the number of vehicles stranded in the cell is small, the server resources can meet the resource requirements of each vehicle. With the gradual increase of the number of vehicles, the resource competition among vehicles leads to less computing resources for each vehicle, which cannot meet the computing requirements of vehicle tasks, resulting in a decrease in the number of task units completed by each vehicle. TOPR can complete more task units than TOAI. The reason is that TOPR considers the number of vehicles in the current cell and the delay constraint of a single task at the same time, so it decides to allocate server resources for on-board equipment, so as to make full use of server resources. However, TOAI only allocates resources to vehicles according to task delay constraints, which may lead to the situation that vehicles do not obtain server resources. For ATOS, the average number of completed task units is lower than the previous two strategies. The reason is that the vehicle has a long waiting delay. When the server resources are sufficient and the vehicle has not left the cell during actual driving, the vehicle does not make full use of the remaining resources of the server but waits to enter the next cell for task unloading. The task completion rate of a single cell refers to the ratio of the number of task units actually completed by the vehicle in the cell to the number of task units that should be completed by the current cell under delay constraints. Figure6indicates the average task completion rate of a single cell under different arrival rates.Figure 6
Average task completion rate.It can be seen from Figure6 that TOPR has obvious advantages over ATOS. The reason is that TOPR is suitable for nonuniform speed vehicles. It not only avoids the problem of cross-region interruption of task processing but also periodically adjusts the unloading strategy according to the current vehicle speed, so as to effectively use the server resources in the current cell and optimize the fairness of service quality between vehicles. For TOAI and TOPR, as the arrival rate increases, the average task completion rate of a single cell decreases. The reason why TOPR is better than TOAI is that TOPR not only processes task units under task delay constraints but also makes full use of server resources. Only considering the energy consumption of on-board equipment, with the increase of arrival rate, the average energy consumption per unit task in the three unloading strategies changes little because the energy consumption per unit task provides corresponding energy for the unloaded tasks. The relationship between average energy consumption per unit task and different arrival rates is shown in Figure 7.Figure 7
Average unit task energy consumption.The reason why the average unit task energy consumption of TOPR is higher than that of ATOS is that the unloading strategy periodically unloads task units according to the vehicle speed, which may cause more invalid transmissions than ATOS, waste the energy consumption of on-board equipment, and cause the average unit task energy consumption to be compared with that of ATOS. ATOS is larger. The reason why the average unit task energy consumption of TOPR is lower than that of TOAI is that the strategy more accurately unloads task units according to the vehicle speed, even if the invalid transmission caused is only a small part, and TOAI does not periodically unload tasks. Larger intracell variation will result in more invalid transmissions relative to TOPR. Here, the average utility is defined as the ratio of the system utility to the total number of vehicles, reflecting that when the time slice size is 10 and the number of iterations is 10, specifically, as the number of nodes increases, the average utility of the system increases, but the increase is getting slower. The experimental results show that the average task completion rate is increased by 0.58%, and the average unit task energy consumption is increased by 0.32%, which improves the practicability of the system. The simulation experiment not only shows that the proposed algorithm optimizes the efficiency of the task under the average unit but also shows the effectiveness of this method, which lays a foundation for the engineering implementation of the algorithm.


## 5. Conclusions

Based on the data-driven edge computing method, the multisignal collaborative processing method for vehicle networking is studied. The data-driven edge algorithm is adopted. According to the needs of different tasks, the multirelay-aided computing unloading strategy is adopted to complete the task unloading. It can effectively relieve the computing pressure when MEC server is overloaded, improve the scalability of MEC, and optimize the total task processing delay of intelligent vehicle group. The algorithm can keep the queue of computing nodes stable, meet the deadline, and minimize the average execution energy consumption of vehicle users in the system. Compared with the traditional local computing method, the unloading of computing tasks alleviates the lack of computing power of vehicles, reduces the delay of task execution, and reduces the energy consumption of vehicles. The algorithm realizes the sharing of computing resources of all MEC servers, makes the load of each MEC server in the system more balanced, improves the processing efficiency of all tasks in the vehicle networking system, and realizes the calculation of vehicle tasks in the system at the minimum cost.However, the study has certain limitations. The signal collaborative processing strategy proposed in this paper does not analyze the intelligent transportation system under the 5G big data scenario. There are certain application limitations, which need further analysis in the future.



---

*Source: 8412750-2022-11-23.xml*