  Vehicle-to-infrastructure and vehicle-to-vehicle communications has been
introduced to provide high rate Internet connectivity to vehicles to meet the
ubiquitous coverage and increasing high-data rate internet and multimedia
demands by utilizing the 802.11 access points (APs) used along the roadside. In
order to evaluate the performance of vehicular networks over WLAN, in this
paper, we investigate the transmisison and network performance of vehicles that
pass through AP by condidering contention nature of vehicles over 802.11 WLANs.
Firstly, we derived an analytical traffic model to obtain the number of
vehicles under transmision range of an AP. Then, incorporating vehicle traffic
model with Markov chain model and for arrival packets, MG1K queuing system, we
developed a model evaluating the performance of DCF mechanism with an optimal
retransmission number. Based on traffic model, we also derived the probability
of mean arrival rate to AP. A distinctive aspect of our work is that it
incorporates both vehicular traffic model and backoff procedure with M/G/1/K
queuing model to investigate the impact of various traffic load conditions and
system parameters on the vehicular network system. Based on our model, we show
that the delay and througput performance of the system reduces with the
increasing vehicle velocity due to optimal retransmision number m, which is
adaptively adjusted in the network with vehicle mobility.
