Landmark-based routing using real-time urban traffic information in VANET

摘要

Most of existing VANET routing protocols are optimized locally, overtaking the global view of the whole network. In this paper, we propose a novel routing protocol in city VANET named Landmark-based routing using global real-time traffic (LRRT), which is beaconless and AP-assisted. First of all, we present a density estimation scheme to understand the global density information for designing routing protocol. Vehicles in the network periodically update their locations and report to APs, while APs gather these real-time reports in their coverage in order to build local density table. Then the global density information is available by sharing local density information between adjacent APs. Furthermore, we design LRRT for data transmission. Once upon data transmitting, vehicles apply to APs for the global density information, which is used to weight the length of all possible roads from source to destination. The shortest path algorithm Dijkstra is presented to output the optimized route, which consists of a series of consecutive junctions on the overlay network. In addition, on the underlay network, packets are forwarded hop-by-hop as the rule of improved Greedy algorithm. The simulation results in a typical urban scenario under NS2 show that LRRT reaches highly credible global density information, and outperforms two other representative protocols in terms of packet delivery ratio and overhead.