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Performance analysis of geography-limited broadcasting in multihop wireless networks

In multihop wireless networks, delivering a packet to all nodes within a specified geographic distance from the source is a packet forwarding primitive (geography-limited broadcasting), which has a wide range of applications including disaster recovery, environment monitoring, intelligent transportation, battlefield communications, and location-based services. Geography-limited broadcasting, however, relies on all nodes having continuous access to precise location information, which may not be always achievable. In this paper, we consider achieving geography-limited broadcasting by means of the time-to-live (TTL) forwarding, which limits the propagation of a packet within a specified number of hops from the source. Because TTL operation does not require location information, it can be used universally under all conditions. Our analytical results, which are validated by simulations, confirm that TTL-based forwarding can match the performance of the traditional location-based geography-limited broadcasting in terms of the area coverage as well as the broadcasting overhead. It is shown that the TTL-based approach provides a practical trade-off between geographic coverage and broadcast overhead. By not delivering the packet to a tiny fraction of the total node population, all of which are located near the boundary of the target area, TTL-based approach reduces the broadcast overhead significantly. This coverage-overhead trade-off is useful if the significance of packet delivery reduces proportionally to the distance from the source. Copyright © 2011 John Wiley & Sons, Ltd.