A survey on fault tolerance in small and large scale wireless sensor networks

Fault tolerance is one of the most important wireless sensor networks requirements. It ensures that the network continues to function correctly even when some components fail. In fact, fault tolerance is a need in this type of networks due to sensor node characteristics, radio communications and hostile environments in which these networks are deployed. In this survey, we give an overview of WSN mechanisms that provide or improve the fault tolerance property of wireless sensor networks. However, the different solutions presented in this survey are not only intended to mechanisms dedicated to fault tolerance, but they also include all the mechanisms allowing the prevention of fault occurrence such as energy aware routing and data aggregation and compression. Besides the classification of fault tolerance mechanisms according to the tasks they target (data management, flow management), we also propose a new classification based on the network size, since the performance of the majority mechanisms depends on the size in terms of geographical area and number of nodes. Thus, a well performing protocol conceived for small networks may be inadequate for large networks and vice versa.