Performance analysis of improved IEEE 802.11 infrastructure power saving under time-correlated channel errors

Wireless enabled portable devices must operate with the highest possible energy efficiency while still maintaining a minimum level and quality of service to meet the user's expectations. In this paper we analyse the performance of a new pointer-based medium access control protocol that was designed to significantly improve the energy efficiency of user terminals in wireless local area networks. The new protocol, pointer controlled slot allocation and resynchronisation (PCSAR) protocol is based on the existing IEEE 802.11 point coordination function (PCF) standard. PCSAR reduces energy consumption by removing the need for power saving stations to remain awake and listen to the channel. Using OPNET, simulations were performed to compare the performance of PCSAR with the infrastructure power saving mode of IEEE 802.11, PCF-PS. The simulation results demonstrate a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless network consisting of an access point and eight stations in power saving mode, the energy saving was up to 28% while using PCSAR instead of PCF-PS, depending upon frame error rate and channel loading. The results also show that PCSAR offers significantly reduced uplink (UL) access delay over PCF-PS while modestly improving UL throughput.