Energy-conservation in 802.11 WLANs via transmission-strategy-aware airtime allocation

In a typical 802.11 wireless local area network (WLAN), different wireless stations may communicate with the access point (AP) with different transmission rates, transmit-power levels, and data payload sizes. Such phenomenon is often referred to as transmission-strategy diversity. In this paper, we study the energy-conservation problem in 802.11 WLANs in the presence of transmission-strategy diversity. This problem is addressed from a unique angle – the system-level fairness which is quite different from most of current research that focuses on improving the performance of each individual wireless station. To emphasize fair energy consumption among contending stations, we introduce a new fairness notion, called energy-conservation fairness, which is in sharp contrast to the conventional throughput fairness and airtime fairness. Another contribution of this paper is an energy-efficient scheme that allocates airtime shares to contending stations so as to achieve combined airtime and energy-conservation fairness. Our simulation results show that, when the energy-conservation fairness is considered, both aggregate system throughput and overall system energy-efficiency can be improved significantly with all contending stations consuming a similar amount of energy.