On the fault-tolerant event region detection scheme with user-specified threshold in wireless sensor networks

The event region detection problem was investigated extensively in recent years for wireless sensor network. However, two known real environmental values (i.e., the normal value and the event value) are assumed in the previously proposed event detection schemes, and the optimal threshold is set to be the intermediate value of the real values. In this paper, the fault-tolerant event detection problem with unknown environmental value and user specified threshold is addressed. It is shown that the conventional temporal-correlation (TS), together with the temporal-spatial correlation (TSC) based fault tolerant event detection schemes could be extended to the event region detection application with user specified threshold. It is validated that, the temporal-spatial correlation based scheme outperforms the temporal-correlation based scheme in terms of fault-tolerant detection performance with some increase in the energy consumption. It is highlighted that, there exists an optimal threshold zone in both event detection schemes. More specifically, a larger threshold zone is preferable with the increase in noise variance and the variation range in the real values. It is also validated that, probabilistic distribution properties of the real values will affect the detection performance as well. Finally, a new performance metric of detection confidence is proposed to provide more information without any increase in the communication overhead. The work in this paper suggests that, the real environment value (or at least its range) and its probabilistic distribution property, the user specified threshold which corresponds to the user interest, together with the work conditions (background noise if it is available) should be taken into consideration to achieve a reasonable event detection performance in the practical design of event region detection scheme.