Performance modeling of the IEEE 802.11p EDCA mechanism for VANET

This paper develops an analytical model for analyzing the access performance of the IEEE 802.11p EDCA mechanism. A 2-D Markov chain is first constructed to describe the backoff procedure of an AC queue and establish a relationship between the transmission probability and collision probability of the AC queue. Then a 1-D infinite discrete-time Markov chain is constructed to describe the contention period of an AC queue and establish another relationship between the transmission probability and collision probability of the AC queue. The two Markov models take into account the saturation condition, standard parameters, backoff counter freezing, and internal collision. Based on the two Markov chains, an analytical model is further derived to describe the relationship between the parameters of an AC queue and the access performance of the AC queue in terms of the transmission probability and the collision probability, respectively. The effectiveness of the analytical model is verified through simulation results.