Provisioned placement of directional sensors for covering stationary targets

Directional sensor networks have been increasingly deployed in various contexts or environments such as banks, warehouses and museums. Directional sensors, in contrast to normal omnidirectional sensors, are characterized with limited sensing angles, and their sensing region is thus usually modeled by sectors. This paper considers the provisioned deployment of directional sensors for covering a fixed number of stationary discrete targets in a two-dimensional field. Minimizing the number of directional sensors used is desirable for financial concerns. Such minimization is formulated as an Integer Linear Programming problem, which is then proved to be NP-complete. Subsequently, three approximation algorithms named Induction, LP-based and Randomized are proposed in turn. Finally simulation results are given to compare the performance of the three approximation algorithms as well as the classic greedy algorithm.