Contention-Limited Access Strategies in IEEE 802.15.4 Beacon-Enabled Networks

Medium access control (MAC) protocols for wireless sensor networks (WSNs) have been extensively investigated in the last years. Although several different protocols have been proposed, and some have been implemented as proprietary protocols in commercial devices, the IEEE 802.15.4 MAC protocol is widely adopted in today´s devices. As a result, energy-saving strategies that can be implemented in compliance with IEEE 802.15.4 can be considered of great relevance. In particular, in beacon-enabled networks much energy can be wasted due to contention among nodes sending data to the coordinator. In this paper, we investigate strategies that can reduce this energy waste by splitting the contention window into multiple contention-limited slots. We consider two different alternatives, and propose efficient algorithms that can be used to assign nodes to these slots based on their traffic conditions. The resulting strategies are evaluated by simulation in terms of energy consumption. Finally, a proof-of-concept is discussed to illustrate the feasibility of our proposal.