A lightweight soft-state tracking framework for dense mobile ad hoc networks

In a mobile ad hoc network, tracking protocols need to deal with - in addition to the mobility of the target - the mobility of the intermediate nodes that maintain a track toward the target. To address this problem, we propose the MDQT (Mobility-enhanced Distributed QuadTree) tracking framework. MDQT employs a static cell abstraction to mask the mobility of the nodes and provide the illusion of a logical static network overlaid on the mobile network. MDQT implements this virtual static network layer in a lightweight/communication-free manner by exploiting the soft-state principle and the snooping feature of wireless communication. Through simulation, we study the impacts of the mobile node percentage and target mobility speed on the system performance. Simulation results show that the success rate of tracking is mostly unaffected by the speed of mobile nodes, but degrades slightly with the increases in mobile node percentage. On the other hand, the cost measurements (latency, average hops, and retry rate) are more sensitive to the mobility speed, and remain unaffected by the increase of mobile node percentage owing to our soft-state design approach. We find that even at very high mobility speeds (50 m/s), low update rates (1 update per second), and 100% node mobility, the success rate of MDQT tracking is above 85% and the latency is comparable with that of static networks. (C) 2010 Elsevier B.V. All rights reserved.