Duty-Cycling in Synchronized IEEE 802.15.4 Cluster-Tree Networks

IEEE 802.15.4 devices operating in beacon-enabled mode synchronize their beacon transmissions to restrict collisions and increase network lifetime. Other avenues of conserving energy in these resource constrained networks is via adaptive duty-cycling. This can be achieved by accounting for the idle listening of a coordinator and its associated devices. But, duty-cycling in a synchronized network often results in loss of synchronization and necessitates re-synchronization. In this paper, we first showcase the scope for additional energy savings in a synchronized network that can be accounted for using a adaptive duty-cycling scheme. Thereafter, we present the necessary condition that needs to be met to perform duty-cycling. We analytically determine the associated cost of synchronization in presence of an active duty-cycling mechanism and compare it with the energy conserved by performing the later. The simulation results concur with our findings and emphasize on the need for operation of synchronization and duty-cycling schemes in sync with each other to boost the overall energy savings of the network.