IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement

In WLAN the medium access control (MAC) protocol is the main element for determining the efficiency in sharing the limited communication bandwidth of the wireless channel. This paper focuses on the efficiency of the IEEE 802.11 standard for wireless LANs. Specifically, we derive an analytical formula for the protocol capacity [Kur 84]. From this analysis we found i) the theoretical upper bound of the IEEE 802.11 protocol capacity; ii) that the standard can operate very far from the theoretical limits depending on the network configuration; iii) that an appropriate tuning of the backoff algorithm can drive the IEEE 802.11 protocol close to its theoretical limits. Hence we propose a distributed algorithm which enables each station to tune its backoff algorithm at run-time. The performances of the IEEE 802.11 protocol, enhanced with our algorithm, are investigated via simulation. The results indicate that the enhanced protocol is very close to the maximum theoretical efficiency.