Design of Location Service for a Hybrid Network of Mobile Actors and Static Sensors
MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
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Location services are essential to many applications running on a hybrid of wirelessly-networked mobile actors and static sensors, such as surveillance systems and the Pursuer and Evader Game PEG. To our best knowledge, there has been no previous location service protocol for wireless sensor networks. A number of location service protocols have been proposed for mobile ad hoc networks, but they are not applicable to sensor networks due to the usually large per-hop latency between sensors. In this report, we present a distributed location service protocol DLSP for wireless sensor networks. Using a rigorous analysis of DLSP, we derive the condition for achieving a high packet-delivery ratio, and show how to configure the protocol parameters to ensure the scalability of DLSP. We prove that DLSP is scalable if the mobiles speed is below a certain fraction of the packet-transmission speed, which depends on a movement threshold. For example, if the movement threshold for the lowest-level location servers is the same as the radio range, the mobiles speed limit is one-tenth of the packet-transmission speed. The mobiles theoretical speed limit is one-fifth of the packet-transmission speed, beyond which DLSP cannot scale regardless of the movement threshold. Because DLSP suffers from a high location-update overhead, we propose an optimization, called DLSP with the Selected Neighbor DLSP-SN, which can reduce the update overhead by more than 70, while achieving a high packet-delivery ratio. Due to the griding effect, the average packets path length of DLSP-SN is longer than that of DLSP. This increases data-delivery cost for continuous data streams. In order to make a tradeoff between update and data-delivery costs, we present a greedy adaptation mechanism, called DLSP-ASN, which can make a significant improvement of overall energy-efficiency.
- Computer Systems Management and Standards
- Operations Research