Target coverage-oriented deployment of rechargeable directional sensor networks with a mobile charger

With the advance on wireless energy transfer, it is reliable and favorable to power a directional sensor network (DSN) by wireless charging. This paper investigates how to deploy a rechargeable DSN using a mobile charger (MC) with the least number of nodes for perpetual target coverage subject to the limited sensing angles of directional sensors and limited energy capacity of the MC. We prove that the proposed problem is NP-hard. Next, we formulate it as a mixed integer nonlinear program to determine the smallest subset of sites to place sensors and the working directions of sensing nodes. Then, we propose two algorithms, i.e., an energy-bounded minimum-cost deployment and a relaxed-linear-program and repairing-based deployment. The simulation results demonstrate that the latter has higher success rate and solution quality than the former at the expense of more computational time.