Resource-Aware routing in delay and disruption tolerant networks

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to mention a few. This thesis studies the resource-aware routing problem in DTNs along four lines. First, the thesis presents the design and comparative evaluation of a delay-tolerant routing protocol (ORWAR) which optimises message transmission and bandwidth usage during opportunistic encounters. This is done through the estimation of contact duration between nodes, selection of the most suitable message to forward at any contact opportunity, and message differentiation. Second, the thesis proposes a hybrid scheme whereby opportunistic and infrastructure-based communication can be combined to overcome network partitions and packet losses. Collaboration between two networks characterised by different capacities, costs, and performance levels has been shown to be not only cost-effective, but also capable of increasing network survivability in the combined network. Third, it proposes and evaluates a mathematical model that can be used to compute the optimal level of redundancy and replication of a routing protocol as a function of message characteristics. Fourth, a holistic approach to resources is proposed, where variations in the spatial and temporal distribution of various resources can feed strategies to reduce resource consumption. Using estimates of vicinity resources, a routing protocol may not only use up fewer resources overall, but may also consume resources preferentially from nodes with higher resource levels, sparing whenever possible those with limited supplies