A locating mechanism for multiple mobile nodes in wireless sensor networks

Current tracking applications in sensor networks lack bi-directional communications with mobile objects. They have a passive communication relationship with unidirectional location data messages routed from mobile objects to the central processing node. In order for an object tracking system to be an "active" tracking system, where the user of the system is able to control the mobile objects in various ways, the system first needs an efficient way to deliver control messages to a mobile object, other than a simple flooding of the control messages. This paper presents an efficient detection method for multiple mobile nodes, which yields a reduction in the number of flooding messages by adopting the hybrid solution of combining a fill-scale flooding and a constrained flooding for the delivery of control messages. Simulation shows that our solution provides about 90% to 10% of reduction on both energy consumption and network traffic comparing to full-scale flooding when the number of mobile nodes increases by 1 to 9.