Date of Award

Spring 1-1-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Computer Science

First Advisor

Douglas Sicker

Second Advisor

Lijun Chen

Abstract

It is well-recognized that our dependence on mobile communications grows; however, users of wireless devices may encounter inadequate coverage due to a variety of shortage and outage circumstances. There are also cost and law issues associated with the problem of inadequate wireless coverage. This is an especially urgent issue in disaster areas where the access to outside world is critical for rescue operations. In this thesis, a self-organizing communication framework is presented for extending wireless coverage for mobile devices, without requiring modifications of existing wireless infrastructures. Participating devices form a hybrid cellular mobile ad hoc network (hybrid cellular-MANET), relaying data off net through the nodes that have both sufficient cellular forwarding capabilities and adequate battery charge level. In a hybrid cellular-MANET, the mobility of the users/devices cause continuous topology and role changes, and the battery energy is critical for communicating with the outside world. To solve these identified challenging problems, a low-complexity, mobility-aware, energy-aware, multi-path data routing mechanism (HMANET) is designed for this framework. The proposed routing includes two major components: a baseline routing that includes a locally reactive and hence low-complexity routing sub-component to handle mobility; and an energy-aware multi-path routing that is motivated by an energy optimization problem and uses only local information. Packet-level simulations show that the proposed routing scheme achieves good performance in delay, packet delivery, adaptiveness to mobility, and energy consumption. In addition, this framework is implemented in Android devices. People can install the corresponding Android application on smartphones and tablets, and use it to form a hybrid cellular-MANET to extend wireless coverage. The results from conducted phone-in-the-loop emulations show that the proposed routing scheme can achieve more effcient energy utilization. Lastly, a fully functioning microblogging system is built for smart devices in disaster areas to validate the feasibility of hybrid cellular-MANETs. The experimental results show that the HMANET protocol statistically outperforms the classic Hybrid Wireless Mesh Protocol (HWMP) used in the IEEE 802.11s standard in terms of adaptiveness to role change and mobility in the hybrid cellular-MANET.

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