Energy-aware adaptive restricted access window for IEEE 802.11ah based networks

Restricted Access Window (RAW) has been introduced for IEEE 802.11ah MAC layer to decrease collision probability. However, both the number of devices involved and duration of a RAW affect the transmission energy and overhead information. In this paper, we study the energy efficiency of the uplink communications of IEEE 802.11ah networks and propose an access window algorithm using probability theory to find an optimal number of devices contending in adaptive RAW size. We formulate the problem of RAW optimization based on the overall energy consumption of different transmission states and the data rate in one RAW. The optimal solution is derived by applying a Hill Climbing approach. Simulation results show that our proposed algorithm outperforms existing RAW on uplink energy efficiency.