Coverage, connectivity and failure recovery control of wireless sensor networks under mobility

Abstract

Recent advances in micro-electro-mechanical technology, embedded systems and wireless communications, with demands for greater user mobility have provided a major impetus toward the development of deployable, controllable, and self-healing mobile sensor networks. This thesis considers mobile sensors and the control of their mobility. The objective of this thesis is to present a novel sensor movement control strategy in which a commander controls a cluster of mobile sensors to monitor a target region ahead of the commander, and in the direction of the commander's movement. Once the speed and direction of the movement of the commander are changed, the new positions of the sensors are decided by our control algorithm, and the sensors move to their new positions at a speed and in a direction also determined by the algorithm. After an upper bounded adjustment time, the sensors will all arrive at their new positions and the commander monitors a new region by these sensors. Connectivity between sensors during movement is guaranteed. Simulation results are presented to demonstrate the effectiveness of the movement strategy. Since mobile sensor failure is inevitable and always results in data unavailability and communication unavailability faults, this thesis also presents a fault tolerance strategy, in which an estimation recovery mechanism is used to solve data unavailability fault. An algorithm is introduced which determines the movement of backup sensors in order to guarantee that the network bi-connected, and hence can withstand single sensor faults, and therefore solve communication unavailability problem.