Coverage time characteristics in sensor networks

We study the problem of coverage of a given area for a maximum duration using a set of battery-operated sensors. Each sensor has a fixed sensing range and a limited lifetime due to the finite battery capacity. Sensors can be activated and deactivated at any time. The goal of this paper is to a find a schedule, determining when to activate and deactivate each sensor, to maximize the time for which every point in the area is covered by at least one sensor. We present several algorithms for this problem and show experimental and theoretical evidences to their efficiency. We also present an algorithm for a new model of coverage, called weak coverage, that does not require each point of the region to be covered all times, as long as the regions that are not covered are small.