Reliable Routing Protocols for Dynamic Wireless Ad Hoc and Sensor Networks

The vision of ubiquitous computing requires the development of devices and technologies, which can be pervasive without being intrusive. The basic components of such a smart environment will be small nodes with sensing and wireless communications capabilities, able to organize flexibly into a network for data collection and delivery. The constant improvements in digital circuit technology, has made the deployment of such small, inexpensive, low-power, distributed devices, which are capable of information gathering, processing, and communication in miniature packaging, a reality. Realizing such a network presents very significant challenges, especially at the protocol and software level. Major steps forward are required in the field of communications protocol, data processing, and application support. Although sensor nodes will be equipped with a power supply (battery) and embedded processor that makes them autonomous and self-aware, their functionality and capabilities will be very limited. The resource limitations of Wireless Sensor Networks (WSN), especially in terms of energy, require novel and collaborative approach for the wireless communication. Therefore, collaboration between nodes is essential to deliver smart services in a ubiquitous setting. Current research in this area generally assumes a rather static network, leading to a strong performance degradation in a dynamic environment. In this thesis we investigate new algorithms for routing in dynamic wireless environment and evaluate their feasibility through experimentation. These algorithms will be key for building self-organizing and collaborative sensor networks that show emergent behavior and can operate in a challenging environment where nodes move, fail and energy is a scarce resource. We develop the technology needed for building self-organizing and collaborative sensor networks using reconfigurable smart sensor nodes, which are self-aware, self-reconfigurable and autonomous. This technology will enable the creation of a new generation of sensors, which can effectively network together so as to provide a flexible platform for the support of a large variety of mobile sensor network applications. In this thesis, we address the dynamics of sink nodes, sensor nodes and event in the routing of wireless sensor networks, while maintaining high reliability and low energy consumption. The hypothesis is that this requires different routing protocols and approaches. The varying application scenarios of wireless sensor networks require different routing protocols and approaches as well. This thesis has three major contributions to the routing in dynamic wireless sensor networks. Firstly, a combination between a new multipath on-Demand Routing protocol and a data-splitting scheme which results in an efficient solution for high reliability and low traffic. Secondly, a cross-layered approach with a self-organizing medium access control protocol and a tightly integrated source routing protocol is designed for high mobility sensor networks. Finally, a data-centric approach based on cost estimation is designed to disseminate aggregated data from data source to destination with high efficiency.