Reliable and energy-efficient wireless sensor networks for surveillance and monitoring

We consider a class of surveillance and monitoring wireless sensor networks, where sensors are highly energy constrained. The goal is to explore the design space of energy-efficient/conserving communication mechanisms and protocols for this class of applications, and to gain a better understanding of the resulting performance implications and trade-offs.; This dissertation consists of two main parts. In the first part we focus on a generic surveillance and monitoring sensor network and examine how energy efficiency might be achieved via topology control, or duty-cycling of the sensor nodes. This approach aims at prolonging the network lifetime by turning sensors on and off periodically and by utilizing the redundancy in the network. Duty-cycling naturally degrades the network performance, for turning off the nodes' sensory devices results in intermittent monitoring capability and turning off the nodes' transceivers results intermittent communication capability.; Within this part, we examine the fundamental relationship between the reduction in sensor duty cycle and the required network density for a fixed performance measure, in particular network coverage and connectivity. We then establish a semi-Markov model that can be used to derive the distribution of coverage and connectivity durations when the sensors are randomly duty-cycled. We further present coordinated duty-cycling algorithms that maintain monitoring coverage and network connectivity, respectively. We also provide a comprehensive comparison study on a class of algorithms, through which we highlight the trade-offs between costs expended in obtaining information, communication, and computation in the design of such algorithms.; In the second part of the dissertation, we study two task scenarios, each with specific functionality requirement, assuming that basic network coverage and connectivity are provided. The first scenario concerns the self-monitoring of a surveillance sensor network, and the second scenario concerns the energy-efficient delivery of packets to an unknown destination. These may be viewed as case studies where we investigate energy-efficient design of specific networking algorithms as well as the design trade-offs involved for given performance requirements.