Design considerations for medium access control in resource constrained embedded wireless networks

Recent years have experienced a huge influx of daily life applications based on embedded wireless networks. While new applications with more demanding requirements and challenging deployment conditions are being explored, most of the existing networks suffer from communication deficiencies, inefficient use of resources, and inability to satisfy desired quality of service requirements. In order to carry on exploitation and exploration of embedded wireless networks in different daily life applications, there is a need for bridging the widening gulf between growing application demands and capabilities of the embedded networking solutions. Medium Access Control (MAC) protocols play a critically important role in embedded wireless communication and heavily influence the performance characteristics of a network. The increasing popularity of embedded wireless networks demand new MAC solutions that best suit to the application requirements and the deployment conditions. Vast literature exists on the fundamentals of MAC designs especially on their theoretical underpinnings. One of the biggest concerns for many researchers and practitioners is that a large number of the proposed MAC schemes when implemented in real applications often fail to provide the behaviour as seen in analytical and simulation studies. The underlying reasons mainly include lack of practical insights due to unavailability of prototype implementation and unrealistic deployment assumptions. This dissertation aims at bridging the gap between theory and practice of MAC protocols for embedded wireless networks through development of new protocols and analysis of existing solutions. The work mainly targets wireless sensor- and cognitive wireless networks. It investigates MAC design aspects with high practical significance: energy efficiency, spectrum agility, runtime reconfigurability and cross-layer methodologies. A novel solution of combining radio-triggered wake-ups with MAC protocols for extremely low-power operation and a specialized dual-radio based MAC design for highly energy efficient communication has been developed. An innovative MAC protocol is introduced for spectrum agility and distributed dynamic channel access in resource constrained embedded wireless networks. For enabling runtime reconfiguration to MAC solutions and fast prototyping, a component oriented framework is developed. Different cross-layer design approaches are investigated for MAC-routing stack optimization and achieving higher network efficiency. All the concepts introduced in this work have been validated through prototype implementation and extensive performance evaluation on real node testbeds under realistic application conditions. Furthermore, comparative empirical studies of the proposed solutions with existing state-of-the-art designs are conducted under the same traffic, network and spectral conditions. The experimental results indicate that the developed MAC protocols have high relevancy to real-world applications and deployment scenarios