Vehicle density, vehicle speed and packet inter-arrival time analysis in IEEE 802.11p EDCA based VANETs

Vehicular ad-hoc networks (VANETs) are considered as a key component of future Intelligent Transportation Systems (ITS). The IEEE 802.11p standard modifies the IEEE 802.11a to adapt to vehicular networks. In the MAC sublayer, the IEEE 802.11p standard uses Enhanced Distributed Channel Access (EDCA) mechanism to provide differentiated media access by defining four access categories (ACs). However, VANET characteristics such as network size, high speed, fast topology changes, traffic density, can greatly affect network performance, especially for the MAC sub-layer. Therefore, important issues arise about the ability of this standard to provide reliable and efficient services for vehicular environment. Since test beds are still limited, computer simulations are very useful for the automobile industry. This paper present a simulation-based analysis of the impact of the vehicle density, vehicle speed and packet inter-arrival time on the performance of the IEEE 802.11p EDCA mechanism in VANET. Throughput, average delay and packet delivery ratio (PDR) were considered as evaluation metrics. The obtained results confirm that IEEE 802.11p EDCA provides an effective differentiation service mechanism that can be adapted to critical ITS applications. However, we noted a performance degradation in extreme cases. As in large number of communicating vehicles, very high speeds, and high transmission rates.