NOMAD - A Hybrid Mobile Ad Hoc and Disruption Tolerant Routing Protocol for Tactical Military Networks

Abstract

There has been much research in recent years within the general field of mobile ad hoc networks (MANET) with many proposals submitted to the IETF for consideration. Delay or Disruption Tolerant Networking (DTN) is a relatively new field for routing, concerned with networks that experience long transmission delay or periods of disruption. Military forces around the globe have applied one or the other networking paradigms with varying degrees of success to their own problems of mobility at the lower tactical level (Brigade and below). The fundamental reason for this limited success is that many of the desired tactical scenarios at this level require a network that is not exclusively ad hoc or exclusively disrupted, but rather a network that dynamically adapts to a variety of mobility situations ranging from relatively stable, almost enterprise like, to completely disrupted. Synchronous MANET protocols have limited disruption tolerance at layer 3, and DTN routing protocols, which are further up the network stack, implement hop by hop asynchronous protocols that are unable to take advantage of prolonged network stability. The primary contribution of this thesis is NOMAD, a new hybrid routing protocol for military mobile ad hoc and disrupted networks. NOMAD is unique in that it operates as a proactive synchronous link state MANET protocol when the network is connected, but is able to seamlessly transition into asynchronous DTN mode when required. The results outlined in this thesis indicate that the hybrid NOMAD protocol provides a substantial improvement over standard synchronous MANET protocols. This thesis also makes a significant contribution with respect to synthetic mobility model generation. Mobility models are essential for the correct evaluation of any routing protocol. A mobility modelling tool called SWarMM (Synthetic Warfare Mobility Modelling) was also developed as part of this thesis. SWarMM provides an agent based simulation tool for generating credible synthetic mobility models for use with the discrete network simulation tools, such as OPNET and NS2.