Energy efficiency driven random access in WLAN system

Due to the time-varying property of wireless networks, users will opportunistically exploit the channel with random access. In this paper, we focus on the energy efficiency of Wireless Local Area Networks (WLANs), in which users communicate with each other or get access to the outside network by contending for the transmission opportunity to Access Point (AP). Energy is consumed during the contention, probing and transmission processes. Hence, in order to achieve the optimal energy efficiency, we design the Energy Efficiency Driven Random Access (EEDRA) strategy that specifies when to stop contention and start transmission, as well as the power level that should be used for transmission. We first apply the optimal stopping theory to maximize the energy efficiency and adopt a bisection algorithm to solve the maximum expected energy efficiency. Then the tradeoff between energy efficiency and throughput is investigated and comparison among different random access strategies is conducted. Lastly, the performance of the proposed strategy is evaluated through numerical results.