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The chemical tracers dispersed by turbulent motion in the environment display rather complex and even chaotic properties. Meanwhile, chemical tracer detecting sensors with air sampling consume significant energy. Hazardous chemical releases are rare events. If all sensors in a wireless chemical sensor network (WCSN) are left in the active state continuously, it would result in significant power consumption. Therefore, dynamic sensor activation is crucial for the longevity of WCSNs. Moreover, the statistical characteristics of chemical tracers to be detected (temporal and spatial correlations, etc.) and placement of chemical sensors can also become the key parameters that influence the WCSN design and performance. In this paper, we investigate the effect of spatial correlation of a chemical tracer field, and also the effect of network topology, on the performance of a WCSN that employs an epidemiology-based dynamic sensor activation protocol. We present a simulation framework that comprises models of the spatially correlated tracer field, individual chemical sensor nodes, and the sensor network. After validating this simulation framework against an analytical model, we perform simulation experiments to evaluate the effect of spatial correlation and network topology on selected performance metrics: response time, level of sensor activation, and network scalability. Our simulations show that spatial correlation of chemical tracer field has a detrimental effect on the performance of a WCSN that uses an epidemiological activation protocol. The results also suggest that a WCSN with random network topology has poorer performance compared to one with a regular grid topology in this application.
Date of Publication: Aug. 2012