  Overheads incurred by routing protocols diminish the capacity available for
relaying useful data in a mobile wireless ad hoc network. Discovering lower
bounds on the amount of protocol overhead incurred for routing data packets is
important for the development of efficient routing protocols, and for
characterizing the actual (effective) capacity available for network users.
This paper presents an information-theoretic framework for characterizing the
minimum routing overheads of geographic routing in a network with mobile nodes.
specifically, the minimum overhead problem is formulated as a rate-distortion
problem. The formulation may be applied to networks with arbitrary traffic
arrival and location service schemes. Lower bounds are derived for the minimum
overheads incurred for maintaining the location of destination nodes and
consistent neighborhood information in terms of node mobility and packet
arrival process. This leads to a characterization of the deficit caused by the
routing overheads on the overall transport capacity.
