An Energy-efficient MAC Protocol with Delay-bounded Downlink Traffic Scheduling Strategy for 802.11 Wireless LANs

Abstract

In the protocol, the access point (AP) schedules the downlink traffic with precise schedule information, which is appended in the redesigned traffic indication map (TIM). To reduce the overhead of control frames, only the schedule information of STAs that wake up at current Beacon interval (BI) is embedded in TIM. The mobile stations (STAs) learn their service time from TIM and choose an energy efficient way to retrieve the downlink data. The protocol is designed to meet different delay requirements of different applications, not just focused on minimizing the average delay of the network. And the Early Deadline First (EDF) strategy is applied on AP to guarantee the delay bound of data frames. We also find the maximal traffic load which the network can bear to guarantee that all the data flow can be scheduled within one schedule cycle. Through theoretical analysis and simulations, we demonstrate that our protocol presents a better performance than IEEE 802.11 and other protocols not only in energy efficiency but also in delay performance of data packets.