A Collision-free Based Rotational Listening Strategy (RLS) for IEEE 802.15.4 WPAN

The standard IEEE 802.15.4 medium access control (MAC) protocol is designed for low-power transmissions in low-rate and short-distance wireless personal area networks (WPANs). The modified CSMA/CA contention protocol suffers from inefficient channel utilization that is mainly caused by no carrier sensing during backoff. Nodes usually perceive channel busy after backoff but channel may be idle during backoff period. Moreover, standard protocol can not get rid of collisions. In this article, we propose a rotational listening strategy (RLS) to improve the opportunity of success transmissions in IEEE standard protocol. In RLS, to behave like a contention-free network, channel access period is partitioned into a number of mini-slots, in which one mini-slot is allotted for one node, and channel sensing of a node is restricted on its own mini-slots. Simulation results demonstrate that RLS indeed improves the transmission efficiency and conserves energy.