A Graph-based Performance Analysis of the 802.11p MAC Protocol for Safety Communications in Highway Vehicular Ad Hoc Networks

We address the performance of the 802.11p protocol in terms of the packet delivery ratio (PDR) and the packet reception ratio (PRR) for broadcasting safety messages in highway environments. Regarding the semi-sparse and intermediate traffic, we try to answer to questions such as what are the upper, dominant and lower bounds of PDR and PRR in each traffic condition? How they may deviate from their average values? and What fraction of vehicles may experience such bounds? To answer to such questions, we propose to consider the communication graph formed among vehicles as a special type of the complex networks and we apply the recently proposed obligatory attachment ruleto synthesize such network structures. Then, we compute some of the important structural properties of the communication graph in VANETS including the one-hop and two-hop degree distributions, the clustering coefficient and the average number of common neighbours. Next, we show how these structural properties could be combined with the state-of-the-art medium access control layer performance analysis methods, resulting in a hybrid framework which can be applied to provide the answers to the aforementioned questions. The accuracy of the results obtained through the application of the proposed hybrid framework is discussed through comparison with simulation results.