Muti-scale temporal segmentation and outlier detection in sensor networks

Monitoring multimodal data generated by sensor networks for extracting information is a challenging task for the human observer. To manage the barrage of data, one needs to create mechanisms for identifying only those time intervals which are informative and worthy of further highlevel analysis either by machine or the human observer. We regard a time interval to be informative and contain an event if it is uncommon or distinct from routine background. Different events in general may unfold at different temporal scales. Here, we present a non-parametric distribution based approach for event detection in sensor network data. In this approach we employ multiple sliding windows at different scales to obtain the distribution of the data. We segment the temporal data stream and identify the potential event bearing candidates by comparing the present and past statistical behavior of the data. In the experiments we demonstrate the effect of optimum bin width selection on accuracy and the range of allowable window sizes and therefore time scales. We analyze the computational speed as well as the supporting empirical results on the bin width.