IEEE 802.11 protocol: design and performance evaluation of an adaptive backoff mechanism

In Wireless LANs (WLANs) the medium access control (MAC) protocol is the main element that determines the efficiency of sharing the limited communication bandwidth of the wireless channel. Previous papers have shown that an appropriate tuning of the backoff algorithm can drive the IEEE 802.11 protocol close to its theoretical limits. In this work we analytically study the performance of the IEEE 802.11 protocol with a dynamically tuned backoff. Specifically, we investigate the sensitiveness of the dynamically tuned backoff algorithm to some network configuration and traffic parameters. Our results indicate that, under stationary traffic conditions, the capacity of the enhanced protocol approaches the theoretical upper bound value in all the configurations analyzed. Furthermore, we also show that the algorithm quickly re-tunes the backoff window size when the network traffic conditions change thus guaranteeing, even with non-stationary traffic conditions, a capacity that is very close to the optimal value. Robustness of the protocol to error conditions is also evaluated. In the paper it is shown the protocol correctly reacts to error conditions.