Characterizing and mitigating communication challenges in wireless and mobile networks
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Wireless and Mobile (WAM) networks have been evolving and extending their reach to more aspects of human activity for years. As such, networks have been deployed in wider and broader physical range and circumstances, so that end-to-end contemporaneous connectivity is no longer guaranteed. To address this connectivity challenge, recent research work on Disruption Tolerant Network (DTN) paradigm uses intermediate nodes to store data while waiting for transfer opportunities towards the destination. However, this work differs from conventional research work in WAM, e.g., Mobile Ad hoc Network (MANET) routing, since the connectivity assumptions are so different. In this thesis, we present the WAM Continuum framework which aims to provide a unified treatment of wireless and mobile networks. The framework is based on the construction of a WAM continuum that defines the space of networks and a corresponding formalism by which one can group related WAMs into classes that map into design and operational regimes. We show a specific instantiation of this framework that classifies networks according to their path properties and apply it to networks described by traces from both real platforms and synthesized mobility models. Effect of introducing controllable node mobility, e.g., message ferrying, is quantitatively evaluated in our study. We extend this framework in a manner that enables the classification of a WAM's energy "sufficiency" depending on a combination of the network connectivity properties, available energy, and power management scheme. As another extension under the same WAM continuum framework, this thesis studies the interaction of mobile computation collaboration and underlying network connectivity characteristics. Classification results from our framework indicate that heterogeneous connectivity may exist in WAM networks. In such cases, protocols from different routing paradigms need to work together to provide effective data communication. We focus on integration of MANET routing and message ferrying in clustered DTNs. A hybrid routing approach is developed in which both MANET routing and message ferrying are used to explore available connectivity in clusters via gateway nodes. Different data aggregation as well as transmission scheduling algorithms are proposed. To achieve better performance, we also study the ferry route design problem in the clustered DTNs and develop three route design algorithms. This thesis work also includes our experience to address challenges associated with new data communication requirements in oil field operations at remote areas. Backed up by a comprehensive measurement study of long range data links provided by satellite and cellular services, we develop a WAM network where multiple data links are jointly used to achieve an effective data communication solution in the challenged environment.