The Mobility Impact in IEEE 802.11p Infrastructureless Vehicular Networks

Vehicular ad hoc networks (VANETs) are an extreme case of mobile ad hoc networks (MANETs). High speed and frequent network topology changes are the main characteristics of vehicular networks. These characteristics lead to special issues and challenges in the network design, such as in medium access control (MAC). Due to the high speed and frequent network partitions, it is difficult to design a MAC scheme in VANETs that satisfies quality-of-service (QoS) requirements in all network scenarios. In this paper, we provide an evaluation of the mobility impact on the IEEE 802.11p MAC performance. In this evaluation, we identify a new unfairness problem in the vehicle-to-vehicle (V2V) communications. To achieve better performance, we propose two dynamic contention window mechanisms to alleviate network performance degradation due to high mobility. Simulation results demonstrate the effectiveness of the proposed MAC schemes.