Power Conservation in wireless sensor network using receiver switch-off

Abstract

A wireless sensor network is a network of nodes equipped with sensors and capable of relaying their data to the monitoring station using multi-hop communication. Essentially, they operate using the ad hoc paradigm due to the unpredictable and dynamic topology. The lifetime of the nodes is limited to that of its battery. Thus in this work we try to conserve the battery by putting the nodes to sleep when they are not involved in any communication process.

Sensor nodes produce readings every fixed time interval and we try to leverage the predictability of the packet inter-arrival time to obtain the sleep periods. We model the inter-arrival times that a node observes in the form of a probability distribution function. A node may be forwarding packets from multiple sources and it associate this knowledge to every stream it is carrying. After a node captures a packet, using its knowledge it can predict the approximate arrival time of the next packet. It can try to sleep during this period. It thus conserves power.

In our study we show that simply forwarding the packet when they are received causes the predictability needed for this approach to be lost. We then propose an alternative approach, which is to maintain some local periodicity. This can be accomplished by delaying the packets. The multi-hop nature of the network causes these delays to accumulate and thus we have to consider the tolerances of the data packets to these delays. We then discuss the relation between the sleep durations possible and the delay tolerances of the packets. Finally, we explore the inter-dependence between packet loss, sleep duration, delay and the ultimate effect on the power savings.