Power consumption reduction in Wireless Sensor Networks through optimal synchronization

Operational lifetime of wireless sensor network (WSN) nodes is crucial in a variety of monitoring applications. As the radio chip is usually the most power-hungry component in small, low-cost WSN devices, battery lifetime can be extended by reducing the duty-cycle of the radio module. In fact, the wireless chip could be switched on just to run the tasks of the considered application, while it could be kept in sleep mode for all the rest of time. Of course, this approach is viable only if the monitoring tasks are scheduled periodically and if the devices are synchronized, namely if they have a common notion of time. Indeed, if nodes were unsynchronized, some of them might wake up when others are still sleeping and some connections could not be established. Since inter-node time synchronization can be maintained within known uncertainty boundaries only by repeatedly adjusting local clocks, synchronization activities can be also scheduled periodically. In this respect, this paper describes an analytical criterion to establish the value of the synchronization period minimizing the average power dissipated by a WSN node. The proposed analysis is validated by means of both simulation and experimental results.