Modeling and QoS Analysis of IEEE 802.11 Broadcast Scheme in Vehicular Ad Hoc Networks

Quality of Service (QoS) and queue management are critical issues for broadcast scheme of IEEE 802.11 systems in Vehicular Ad hoc Networks (VANETs). However, existing 1-dimensional models of broadcast scheme in VANETs are unable to capture the complete QoS performance and queueing behavior due to the lack of an adequate finite buffer model. We present a 2-dimensional Markov chain that integrates the broadcast scheme of the 802.11 system and queueing processes into one model. The extra dimension, that models the queue length, accurately capture important QoS measures for realistic 802.11 broadcast systems with finite buffer under finite load. We derive an simplified method for solving the steady state probabilities of the Markov chain. The solutions are validated by extensive simulations. Based on this model, we also show numerical results to analyze the performance of the broadcast scheme in VANETs in terms of collision probability, throughput, queue length, and QoS measures, including blocking probability and queueing delay.