Approximation algorithms for maximum target coverage in directional sensor networks

Target coverage is a fundamental problem in wireless sensor networks. To preserve energy, the minimum coverage problem, which aims at covering a given area or a set of interesting points with the minimum number of sensors, has been extensively studied for general sensor networks with omni-directional sensors. In this paper we address the coverage problem in directional sensor networks in which sensors have tunable directions and can only cover one direction at a time. Given a set of target points and a set of sensors, we investigate the problem of assigning directions to the sensors such that the number of target points in the sensing area is maximized. We prove the greedy algorithm is a polynomial time 1/2-factor approximation solution for this maximization problem and provide a tight example for this ratio. We also investigate a variant of this problem and provide an approximation solution for it with similar performance guarantee.