Optimal constant-window backoff scheme to increase throughput and fairness of IEEE 802.11 DCF in single-hop networks

Anouar, Hicham;Bonnet, Christian
Research report RR-05-153

In this work, we propose and analyze a backoff enhancement for IEEE802.11 DCF. We first analyze the performance of DCF multiple access scheme under general load conditions in single hop configuration and we provide an accurate delay statistics model that consider the self-loop probability in every backoff state. We prove then the short-term unfairness of the binary exponential backoff used by IEEE802.11 by defining channel capture probability as fairness metric. Motivated by the results on fairness, we introduce an optimal constant-window backoff scheme and we compare its performance to IEEE802.11 DCF with Binary exponential backoff scheme. Numerical results show that the proposed retransmission scheme increases both the throughput and fairness of IEEE 802.11 DCF while remaining insensitive to traffic intensity. The analysis is then extended to consider the finite queueing capacity at nodes buffers using results from the delay analysis. NS2 simulations validate the obtained results.

Systèmes de Communication
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