Joint duty cycle and link adaptation for IEEE 802.15.4 beacon-enabled networks

The IEEE 802.15.4 beacon-enabled mode provides for energy savings through synchronization of active and sleep periods. Recent research proposes to employ adaptive duty cycling schemes in conjunction with active/sleep synchronization to reduce the coordinator idle listening problem and thus minimise energy consumption. Here, and motivated by the recent introduction of new 2.4GHz IEEE 802.15.4 radio chips that provide higher data rates than the standardised 250kb/s, we propose to further reduce nodes' battery energy consumption by combining link adaptation with adaptive duty cycling. The idea is that an increase in the data rate, when allowed by the signal quality estimation, will decrease the receiving time and therefore the duty cycle selection. With this aim, we propose in this paper a link adaptation policy for IEEE 802.15.4 multi-rate radio chips that does not incur any extra overhead and is aware of link asymmetries. Our simulation results show that, when our link adaptation is combined with state-of-the-art duty-cycling techniques, sensor node's energy efficiency is greatly improved with gains of up to 50%.