| With the rapid development of the Internet of Things,the Internet of cellular vehicles has gradually entered public life.In a general sense,the Internet of Vehicles can be understood as the integration technology of intelligent transportation,which applies the technology of the Internet of Things to the field of transportation system to realize the information exchange and sharing between vehicles and all things.C-V2 X vehicle topology in urban environment is highly dynamic and the load capacity of vehicle nodes is limited.In order to improve the utilization of vehicle cache and reduce the load of base station,this paper mainly studies how to conduct cooperative cache between vehicle nodes and base station on the basis of vehicle network joint.Firstly,a vehicle cache node selection algorithm under load constraints—Mininum Dominant Set Algorithm Based on Node max（Nmax MDS）is proposed.By defining the link stability measure,the predictive weight adjacency matrix is constructed to describe the vehicle topological relationship at a micro level.Secondly,the objective function is constructed under load constraints and non-overlapping coverage constraints to achieve full coverage with the least cache nodes and maximize cluster average link weight.Finally,the concept of greed is introduced and the node states are reasonably defined to solve the minimum dominant set of vehicle topology under load constraints,and the service neighbor nodes are selected optimally.Simulation results show that the proposed algorithm is close to the global optimal in terms of the number of cache nodes and the mean of cluster average link weight,and the repeated response rate is constant zero,the request response rate can reach the theoretical upper bound,and the cache source response times can be effectively increased.Secondly,in order to relieve the communication load of the base station as the edge Cache source in C-V2 X and improve the data transmission efficiency,the Neighbor Cache Greedy Complementary Collaboration Algorithm（NGCC）was proposed.Under the constraints of node topology and transmission delay,the algorithm adopts the greedy flooding cache node allocation order,and cooperates with the most popular cache files cached by neighboring nodes.The result is not only a trade-off between the redundancy of the cache and the diversity of the cache,increasing the response rate of the request,but also increasing the service coverage of the high popularity files,thereby reducing the transmission delay.Simulation results show that the request response rate of the proposed algorithm is close to the optimal value of exhaustive verification,which is obviously better than the most popular cache algorithm and random cache algorithm,and has lower cache space occupancy and higher request response rate. |
