energy-efficient capture of stochastic events by global- and local-periodic network coverage
We consider a high density of sensors randomly placed in a geographical area for event monitoring. The monitoring regions of the sensors may have significant overlap, and a subset of the sensors can be turned off to conserve energy, thereby increasing the lifetime of the monitoring network. Prior work in this area does not consider the event dynamics. In this paper, we show that knowledge about the event dynamics can be exploited for significant energy savings, by putting the sensors on a periodic on/off schedule. We discuss energy-aware optimization of the periodic schedule for both cases of a synchronous and an asynchronous network. Under the periodic scheduling, coordinated sleep by the sensors can be applied orthogonally to minimize the redundancy of coverage and further improve the energy efficiency. We consider four points in the design space: synchronous periodic scheduling with and without coordinated sleep, and asynchronous periodic scheduling with and without coordinated sleep. We show that the asynchronous network exceeds the synchronous network in the coverage intensity, thereby increasing the effectiveness of the event capture, though it may also reduce the opportunities for coordinated sleep. When the sensor density is high, the asynchronous network with coordinated sleep can achieve extremely good event capture performance while being highly energy-efficient.
network coverage periodic scheduling energy efficiency event capture coordinated sleep protocol sensor network