An Improved Geocast for Mobile Ad Hoc Networks

Geographic addressing of packets within mobile ad hoc networks enables novel applications, including hard real-time engagement simulation in military training systems, geographic command and control functions in training and emergency communications, and commercial messaging applications as well. The most scalable implementation of geoaddressing is via a geocast protocol, where nodes selectively retransmit packets based on local decision rules. Well-designed retransmission heuristics yield scalable geographic flooding that outperforms alternative geoaddressing approaches. However, previous geocast implementations, while effective, fall into two categories. Approaches based on flooding are unscalable due to the high load they generate. Scalable approaches, on the other hand, have trouble in complex environments, lacking sufficient intelligence about the necessary directionality of packet flow. The present paper defines a novel geocast heuristic, the Center Distance with Priority (CD-P) Heuristic, which both significantly improves on reliability of existing scalable geocasts and yet also remains scalable as scenario complexity increases. This paper describes the new technique as well as an evaluation study comparing it to previous approaches.