Joint sensor duty cycle scheduling with coverage guarantee

Using optical sensors for indoor monitoring has been widely adopted in many smart building applications. An important design problem in this space is to explore the tradeoff between energy consumption and coverage quality. While it is important that the sensors achieve full coverage (i.e., every interesting target point can be monitored by at least one sensors), it is often a waste of energy to keep sensors on all the time as events are typically stochastic and rare and most of the time the sensors are on idle monitoring. In this paper we design efficient sensor duty cycles to ensure that any target point of interest is still covered sufficiently frequently while only a subset of sensors are kept on at any time slot. We denote by the maximum dark length for each target point p as the maximum duration in which p is covered at least once. We formulate two optimization problems: the min max dark length scheduling and the min average dark length scheduling. For both versions we provide efficient, practical algorithms with provable approximation guarantee. The two algorithms have been tested on two real testbed scenarios to evaluate its efficiency and coverage quality.