A priori methods for fault tolerance in wireless sensor networks

The wireless sensor networks (WSN) represent a very promising domain. They can be used in a large variety of applications due to their easy deployment and their low cost of construction. These networks are composed of plenty of sensor nodes that are deployed in the monitoring field, and they form a multihop self-configured network by means of wireless communication. Sensor nodes have processing, perception and communication ability. However, they are subject to different forms of failures that affect their reliability. These problems include hardware failures and computer attacks which are, nowadays, a real threat constantly growing. The fault tolerance is considered as a critical issue and a very interesting subject of research in wireless sensor networks (WSN). To realize some applications such as disaster relief, medical care, environmental monitoring and military surveillance, reliability is fundamental and essential. Without secure routing and successful transmission, many applications of wireless sensor networks cannot work. Because of the sensitivity of many applications of sensor networks, several research projects have been conducted in order to find solutions to these networks in the presence of failures and intrusions. All the fault- tolerant approaches are characterized by their own disadvantages and advantages, making them adapted to various applications. In this paper we describe the common failures of sensor nodes and the different methods using to guarantee the proper functioning of the network, and also a theoretical modeling of a probabilistic combinatorial optimization problem is explored in order to minimize the energy consumption and improve fault-tolerance for WSN.