Cross-layer Routing Research In Vanet

As the medium for providing data transmission between vehicles,VANET has become a hot research field.Compared with the traditional wireless networks,VANET has the characteristics of fast node movement,uneven node density,and rapid change of network topology,as a result of which,the end-to-end transmission faces many challenges.In order to overcome these challenges,a suitable VANET routing protocol is particularly important.There are already many routing protocols designed specifically for VANET,but most existing routing protocols are designed only at the network layer and rarely take into account the effects of interference which results in bad performance of routings.To solve the above problems,in this thesis,a new cross-layer routing protocol is proposed.Firstly,the development history and research status of VANET are introduced.Then,the structure of VANET and the existing VANET technologies are introduced in detail.Next,the cross-layer routing proposed in this paper is introduced,it mainly contains two parts:(1)Firstly,Position-based resource selection algorithm in MAC layer is proposed.Unlike the traditional resource allocation algorithms,nodes select the time-frequency resources by their locations,so the interference between nodes is constrained by the locations of the nodes.(2)Then the Multi-metric routing in network layer is proposed.Every node constructs multiple metrics for each neighbor by collecting data collected by the lower layer including the Zone ID of Position-based resource selection algorithm in MAC layer and geographic location,the signal to interference and noise ratio,etc.When the forwarding decision needs to be made,the node combines the sub-metrics to select the optimal next hop node.Finally,the proposed cross-layer routing is simulated involving the simulation of position-based resource selection algorithm and compare with some existing VANET routings respectively.As research results show,the performance of position-based resource selection algorithm is different based on different resource pool division methods and different parameters configurations.Then,according to the simulation results including packet delivery ratio,average hop number and delay,compared with other VAN-ET routings,the cross-layer routing proposed in this thesis makes the average packet delivery ratio of the system significantly improved with almost no increase in overhead and delay.