Modeling IEEE 802.11 DCF with Finite Retry Limits

Abstract

The IEEE 802.11 is the dominating standard for wireless local area networks (WLANs). IEEE 802.11 uses Distributed Coordination Function (DCF) protocol with Binary exponential backoff (BEB) algorithm for packet transmission. In WLANs, the performance metrics such as throughput and end-to-end delay greatly depend on packet transmission procedure. The packet transmission procedure can be represented with a Markov chain model. Till now, several Markov chain models have been developed for evaluating the performance of IEEE 802.11 wireless networks. Yet, these models cannot truthfully calculate the performance of the network. Moreover, the existing models suffer with high packet collisions resulting in degradation of throughput particularly under congested environments. In order to overcome this, a new packet transmission procedure for DCF protocol is introduced in this paper considering both packet retry limits and transmission errors. A mathematical analysis is carried out for transmission probability and the throughput of the network is analyzed. Simulation results show significant improvement in throughput of DCF protocol under basic access and request-to-send/clear-to-send (RTS/CTS) access mechanisms using the proposed model when compared with the existing models Keywords: DCF, IEEE 802.11, Markov chain model, Throughput. .