A New Approach on Analysis of IEEE 802.11 DCF in Non-Saturated Wireless Networks

Many performance evaluations for IEEE 802.11 distributed coordination function (DCF) have been formerly reported in the literature; most studies are based on saturation analysis, and a few models under a finite load condition adopt an M/G/l queuing system. However, using M/G/l queuing only considers the first moment of frame service time to derive the probability of transmission queue being vacant. In this paper, we model the DCF using parallel space-time Markov chain (PSTMC), in which frame arrivals are tracked by monitoring the transmission queue during transitions between successive states of the space-time Markov chain. The proposed framework provides the possibility of modeling the contention phase, backoff and post-backoff procedures, and the transmission queue status. The proposed framework is validated by the simulation results.