Abstract:
Vehicular Ad-Hoc Networks (VANETs) are a sub form of Mobile Ad-Hoc Network that provide communication among vehicles (V2V) and vehicles to infrastructure (V2I). VANETs have been developed to offer reliable and efficient services on the roads. These services include safety applications (collision warning), and non-safety applications (video and voice). The IEEE 802.11p is an extension of the IEEE 802.11 standard to support wireless access into vehicular environments. However, the IEEE 802.11p standard does not perform well for VANETs under high traffic load and mobility. The is owing to the nature of contention-based channel access mechanism in IEEE 802.11p sharing a common radio frequency. The work in this paper presents a new scheme to improve the channel access coordination of 802.11p for V2I communication under high traffic and mobility. This scheme adaptively adjusts the contention window (CW) based on the times (deadlines) that the vehicles are about to exit the RoadSide Unit (RSU) coverage area. Priority service is given to vehicles with shorter deadlines and vice versa. The Network Simulator (NS-2) v.2.35 is used for simulation. According to simulation results, our proposed scheme outperforms the existing scheme in terms of throughput, packet loss ratio and packet delivery.
