Connectivity-aware Medium Access Control in platoon-based Vehicular Ad Hoc Networks

Because of the space and time dynamics of moving vehicles, network connectivity is an important performance metric to affect packet delivery in Vehicular Ad Hoc Networks (VANETs). Grouping vehicles into platoons in VANETs can improve road safety, change the network connectivity, and even reduce channel access collisions. Unfortunately, network connectivity is often ignored in the design of exiting MAC protocols for VANETs. In this paper, we analyze the connectivity probability and present a connectivity-aware Medium Access Control (MAC) protocol for platoon-based VANETs. A multi-priority Markov model is presented to derive the relationship between the connectivity probability and the system saturated throughput. Based on variable traffic status and network connectivity, a multi-channel reservation scheme is adopted to dynamically adjust the length of the Control CHannel (CCH) interval and the Service CHannel (SCH) interval for the improvement of the system performance, in terms of network throughput and the priority packet transmission opportunities for platoons. As a result, some important observations to the design and analysis of such communication systems are provided.