Enhancement of AODV Routing Protocol by using Large Vehicles in VANETs on Highway

In recent years, many routing protocols that take into account particular vehicular ad hoc network (VANET) characteristics such as higher vehicle speeds and mobility patterns have been proposed. Most of the existing VANET routing protocols largely neglect vehicles as obstacles in VANETs. Obstacle shadowing caused by large vehicles such as trucks or buses more negatively affects packet transmission performance than some other type of fading affects the performance in highway scenarios because the direction of packet forwarding is limited only to that along the highway, i.e., the forward and backward directions on the highway. Large vehicles have not only the negative effect of obstacle shadowing but also a positive effect due to their higher antenna position. Antennas of large vehicles are placed at higher positions than those of standard-size vehicles. A higher antenna position can achieve a longer transmission distance. In this paper, we propose a new Ad hoc On-Demand Distance Vector (AODV) routing protocol using large vehicles (AODV-LV) that exploits the positive effect of large vehicles. AODV-LV preferentially selects large vehicles as nodes for rebroadcasting route request (RREQ) packets. To investigate the performance of AODV-LV, we compare it with an existing improved AODV routing protocol. Our simulation results show that AODV-LV outperforms the existing protocol from the standpoints of packet delivery ratio and delay.