Calculation of Coverage Relationship between Camera Sensor Node and Scalar Sensor Node in Two-Tier Wireless Multimedia Sensor Networks

For energy-constrained wireless multimedia sensor networks (WMSNs), how to minimize the energy consumption while still capturing the events images with low latency becomes a crucial question in the design. A good solution for this question is using two-tier network, in which the camera sensor nodes should only be woken up when an event is detected by the scalar sensor nodes within its sensing field. In this solution, a key step is to know the coverage relationship between the camera sensor nodes and the scalar sensor nodes. Therefore we study the sensing models of these two kinds of sensor nodes and define the coverage relationship between them in this paper. An algorithm to calculate the coverage relationship between these two kinds of sensor nodes is presented. Thus, during the working process of the network, by saving the coverage relationship table in its memory, each camera sensor node can easy to know whether they cove the events or not.