Performance analysis of routing protocols for vehicle safety communications on the freeway

In a freeway vehicular ad hoc network (VANET) environment, an efficient ad hoc routing protocol plays a very important role to enhance the safety of passengers. This paper presents the latest result of simulation model of three mobile ad hoc routing protocols: destination-sequenced distance-vector protocol (DSDV), dynamic source routing (DSR) and ad hoc on-demand distance vector (AODV). The performance of three protocols under constant bit rate traffic is evaluated and compared with five quality indices. The simulation results show that both the reactive routing protocols, DSR and AODV, have better performance than the proactive routing protocol DSDV. DSDV has largest packet loss rate and smallest system throughput among the three protocols. This paper also shows that the effect of varying mobility has undeniably influenced the performance of both reactive routing protocols. DSR is better in the protocol overhead than AODV. However, there is critical jitter variation in the DSR. As a whole, AODV is more appropriate than DSR for the freeway VANET.

I. Introduction

Over the last two decades, the total length of freeways in China has rapidly increased. At present, it is over 60,000 kilometers. Although traditional passive safety systems such as seatbelts and air-bags have been the norm equipment in the vehicle, the number of traffic fatalities on the freeway still rises every year [1]. In particular, chain collision accidents occurred on a freeway will result in more losses of lives and properties. In order to avoid these collisions, the proactive safety systems have been introduced to warn the driver if a vehicle is in a blind spot or if the vehicle inadvertently leaves its lane [2]. The next step in advanced proactive safety is to allow vehicles to share information about the traffic state directly between each other and with infrastructure using wireless communications. The kind of wireless communications is regarded as vehicular ad hoc network (VANET), which can provide communications among nearby vehicles, and between vehicles and nearby fixed roadside equipment.