Using Mobile Elements as Dynamic Bridges in Sparse Wireless Sensor Networks

Abstract

Sparse Wireless Sensor Networks using several mobile nodes and a small number of static sensor nodes have been widely used for many applications, especially for traffic-generated pollution monitoring. This paper proposes a method for data collection and forwarding using Mobile Elements (MEs), which are moving on predefined trajectories in contrast to previous works that use a mixture of MEsand static nodes. In our method, MEscan be used as data collector as well as dynamic bridges for data transfer. We design the trajectories in such a way, that they completely cover the deployed area and data will be gradually forwarded from outermost trajectories to the center whenever a pair of MEs contacts each other on an overlapping road distance of respective trajectories. The method is based on direction-oriented level and weight assignment. We analyze the contact opportunity for data exchange while MEs move. The method has been successfully tested for traffic pollution monitoring in an urban area.