Dependability evaluation of Wireless Sensor Networks: Redundancy and topological aspects

Dependability analysis of Wireless Sensor Networks (WSN) is mandatory in order to investigate critical aspects that can affect the correct functioning of a WSN application. Starting from a Markov reward model that allows us to capture the behavior of a single sensor node, we propose an analytical technique to evaluate dependability parameters of the whole WSN. In particular, we investigate the WSN reliability, defined as the probability that at least k sensor nodes are alive at time t, and the WSN producibility defined as the probability that at least k sensor nodes are able to communicate with the sink at time t. Such parameters are measured under different working conditions and varying the number of redundant nodes as well as the network topologies. Analyzing such dependability parameters, important metrics can be exploited, such as the expected lifetime of the WSN and the average producibility during the functioning time, that can help designers during the setting phase of the network.