Research On Stable Optimization Mapping Algorithm Of Service Function Chain In Autonomous Transportation System

In the future,a large number of emerging services with low delay and high speeds will arise in the Autonomous Transportation System(ATS),such as holographic sensing,workshop collaborative sensing.These services need to be provided in vehicle-road cooperative network by using Service Function Chain(SFC)as the computational transmission mode.Therefore,Network Function Virtualization(NFV)technology is introduced in ATS to decouple network functions from hardware devices for flexible mapping of SFC,enhancing the service capacity of the network.However,compared with the static physical network which has widely deployed SFC mapping technology,the mobility of vehicles in vehicle-road cooperative networks will cause instability of communication links,including limited Link Lifetime(LLT)and inhomogeneous link reliability,which will lead to the risk of interruption and failure of the mapped SFC.Focusing on the above problems,this paper aims to enhance the stability of SFC mapping in mobile scenarios,and studies the SFC mapping optimization scheme for vehicle-road cooperative network by improving the mapping feasible duration and ensuring link reliability respectively.The details are shown as follows:In order to increase the Mapping feasible duration(MFD)of feasible SFC under finite LLT,the LLTs value vehicle-road links and vehicle-vehicle links are firstly analyzed respectively.Secondly,a linear integer programming model is established to maximize the MFD under the constraint of the set of feasible conditions of SFC mapping,where the problem is NP-hard.Finally,to solve the problem with reduced complexity,a pruning strategy is designed by considering the node attributes,link attributes and link correlation,and a low-complexity combinatorial optimization mapping algorithm for SFC in vehicle-road cooperative network is constructed.Simulation results show that compared with the existing device location mapping algorithm and attribute sorting algorithm,the proposed algorithm can effectively improve the MFD and has a higher mapping success rate.In this paper,three stages are used to solve the link reliability guarantee mapping.First,the reliability of vehicle-to-vehicle link is analyzed by using stochastic geometry and moment generating function theory,and then the unreliable link is filtered out.Second,the subgraph isomorphism is improved from its basic idea,and the optimization pruning strategy with matching divergence probability is used to further reduce the algorithm complexity.Finally,the mapping order of service is sorted with the fitness of vehicle nodes to be mapped,so as to make full use of network resources and improve the mapping success rate of multi-service sets.Simulation experiments show that compared with the existing algorithms,the proposed algorithm solves the link unreliability problem in SFC mapping and improves the mapping success rate of multi-service sets effectively.