A Stable Routing Protocol for Highway Mobility over Vehicular Ad-Hoc Networks

Vehicular ad hoc network (VANET) is a promising technology to enable the communications among vehicles. In intelligent transportation systems (ITSs), VANETs have many unstable channel characteristics such as short transmission time, low packet delivery ratio, frequent link breakage and rapidly changing topology caused by high mobility. One of the critical issues is the design of stable and scalable routing algorithms that are robustness to frequent path disruptions caused by vehicles' mobility. Previous stable routing protocols in VANETs have been generally focused on vehicle position and velocity based on the ignorance of the channel conditions. This paper argues the use of vehicles movement information including highway mobility model besides position, direction, velocity and digital mapping of roads to predict how long a route will last. And the channel state information is introduced to calculate every moving vehicle's transmission range. In this way, a new vehicular reliability model is proposed to facilitate the reliable routing in VANETs. The communication-link reliability is defined as the routes' stable lifetime. The well-known ad-hoc on-demand distance vector (AODV) routing protocol is extended to propose our reliable ad-hoc on-demand distance vector routing protocol AODV-L. To evaluate the proposed routing protocol, we compared the traditional AODV routing protocol with AODV-L through OMNET++. Simulation results demonstrate that AODV-L outperforms significantly the AODV routing protocol in terms of better delivery ratio and less end-to-end delay.