Cross-layer Greedy Routing Strategy Based On Cooperative Caching In VANET

VANET(Vehicular Ad-hoc Network)is a kind of centerless,self-organizing and multi-hop network with vehicles as the main part.But the traditional VANET system is facing new challenges due to its high-speed node mobility,dynamic topology,unstable wireless communication,and characteristics of self-organizing communication.This paper mainly studies the VANET routing algorithm based on cooperative caching in ICN(Information-Centric Networking)architecture.Firstly,combining VANET and NDN(Named Data Networking),Distributed Cooperative Virtual Caching Algorithm Based on NDN in VANET(DCVCA)is proposed to improve the diversity of caching contents in the network and the average hit rate.According to the mobility,nodes are clustered.In order to dynamically balance the density of caching contents in the network,cluster cooperation and inter-cluster cooperation are carried out respectively.In the inter-cluster cooperation strategy,the cluster head will take the idle cache space of cluster members as its virtual cache space.According to the value of contents and the level of cache space,the cluster head conducts cooperative caching within the cluster,avoiding content redundancy and ensuring that the high popularity content will be stored in its cache space.In cluster cooperation strategy,the cluster heads on the return path will calculate the cache probability of the content based on its cache value,the distance between current node and last cache node,and the mobility of the whole cluster nodes,aiming to achieve the reasonable distribution of the network cache.Secondly,aiming at the characteristics of VANET,a Cross-layer Greedy Routing Algorithm Based on Cooperative Caching in VANET(CGRA)is proposed to improve data transmission efficiency,distribute Interest packet and Data packet purposefully,and reduce the communication overhead in the network.In the process of routing decision,we choose the optimal next forwarding node from two aspects,one is the movement parameters of nodes,the other is communication parameters.A reliable neighbor node set is selected by movement parameters.And the optimal next forwarding node which is with low load and stable communication is selected by communication parameters.The communication parameters combine the average length of the MAC layer caching queue and the average number of data re-transmission.At the same time,the FIB table is improved to cut down the extra communication overhead and the time delay of data.And combining with the content location in the network,the distribution of Interest packet and the delivery of Data packet are more objective,which effectively reduces data forwarding hops and takes into account the communication overhead in the network.Finally,the performance of the proposed algorithms is verified through two aspects of performance indicators,one is the performance indicators in NDN cooperative caching,such as average hit rate and average hit hops,the other is the performance indicators of routing algorithm such as average hit rate,average hit hops,hit redundancy and average forwarding hops.The simulation results show that the cooperative caching ability is superior to the algorithm in the literature[19],and its routing ability is better than the traditional NDN routing algorithm.