Expected Routing Overhead for Location Service in MANETs under Flat Geographic Routing

We study routing overhead due to location information collection and retrieval in mobile ad-hoc networks employing geographic routing with no hierarchy. We first provide a new framework for quantifying overhead due to control messages generated to exchange location information. Second, we compute the minimum number of bits required on average to describe the locations of a node, borrowing tools from information theory. This result is then used to demonstrate that the expected overhead is Ω (n^1.5 log (n)), where n is the number of nodes, under both proactive and reactive geographic routing, with the assumptions that 1) nodes´ mobility is independent, and 2) nodes adjust their transmission range to maintain network connectivity. Finally, we prove that the minimum expected overhead under the same assumptions is Θ (n log (n)).