Abstract: For the characteristics of fast moving vehicles and rapid changing network links in vehicular Ad hoc networks,local maximum is often happened at road intersections in previous routing schemes.Based on road characteristics in urban environments,and supported by physical infrastructure and electronic conditions of the traffic light system,an intersection-relay-assisted routing(IRAR) scheme was proposed.By building a stochastic model of the road message delay,the global optimum forwarding path is got for each message,and local maximum is solved by relay assisted infrastructure.Furthermore,intersection forward mode and greedy straight way mode are designed according to the intersection location and straight way location of messages,separately.Finally,simulations are conducted to compare the proposed IRAR and the state-of-the-art schemes.Simulation results suggest that IRAR outperforms the compared schemes significantly in delivery ratio and delay.

Key words: Vehicular ad hoc network,Relay assisted,Routing scheme,Local maximum,Stochastic model