Geographic Routing in Intermittently-connected Mobile Ad Hoc Networks : Algorithms and Performance Models

Abstract: Communication is a key enabler for cooperation. Thus to support efficient communication humanity has continuously strived to improve the communication infrastructure. This infrastructure has evolved from heralds and ridden couriers to a digital telecommunication infrastructures based on electrical wires, optical fibers and radio links. While the telecommunication infrastructure efficiently transports information all over the world, there are situations when it is not available or operational. In many military operations, and disaster areas, one cannot rely on the telecommunication infrastructure to support communication since it is either broken, or does not exist. To provide communication capability in its absence, ad hoc networking technology can be used to provide a dynamic peer-based communication mechanism. In this thesis we study geographic routing in intermittently connected mobile ad hoc networks (IC-MANETs).For routing in IC-MANETs we have developed a beacon-less delay-tolerant geographic routing protocol named LAROD (location aware routing for delay-tolerant networks) and the delay-tolerant location service LoDiS (location dissemination service). To be able to evaluate these protocols in a realistic environment we have used a military reconnaissance mission where unmanned aerial vehicles employ distributed coordination of their monitoring using pheromones. To be able to predict routing performance more efficiently than by the use of simulation, we have developed a mathematical framework that efficiently can predict the routing performance of LAROD-LoDiS. This framework, the forward-wait framework, provides a relationship between delivery probability, distance, and delivery time. Provided with scenario specific data the forward-wait framework can predict the expected scenario packet delivery ratio.LAROD-LoDiS has been evaluated in the network simulator ns-2 against Spray and Wait, a leading delay-tolerant routing protocol, and shown to have a competitive edge, both in terms of delivery ratio and overhead. Our evaluations also confirm that the routing performance is heavily influenced by the mobility pattern. This fact stresses the need for representative mobility models when routing protocols are evaluated.