Fault tolerance techniques for wireless ad hoc sensor networks

Embedded sensor network is a system of nodes, each equipped with a certain amount of sensing, actuating, computation, communication, and storage resources. One of the key prerequisites for effective and efficient embedded sensor systems is development of low cost, low overhead, high resilient fault-tolerance techniques. Cost sensitivity implies that traditional double and triple redundancies are not adequate solutions for embedded sensor systems due to their high cost and high energy-consumption. We address the problem of embedded sensor network-fault-tolerance by proposing heterogeneous back-up scheme, where one type of resource is substituted with another. First we propose a broad spectrum of heterogeneous fault-tolerance techniques for sensor networks including the ones where communication and sensing are mutually backing up each other. Then, we focus our attention on two specific approaches where we back-up one type of sensors with another type of sensor. In the first, we assume faults that manifest through complete malfunctioning and in the second, we assume sensors where fault manifest through high level of error.