| Technological advances in VLSI, MEMS, and wireless communication have ushered in a new age of miniature, low cost, low-energy, micro-sensors. Networks of such devices, called Wireless Sensor Networks (WSNs), promise to revolutionize sensing across a range of civil, scientific, military and industrial applications. The potentially high impact of this technology and the complex challenges it poses have spurred intense interest in the research, military and commercial communities. However, sensors often have limited energy, computational ability, and storage capacity. Therefore protocols that manage the different aspects of the sensors' operation in terms of collecting and processing data, as well as support services such as localization and synchronization have to be developed and must work efficiently within the constraints of the limited available resources---this is an extremely challenging task.; The first contributions of our research are in developing application-specific, light-weight, energy efficient protocols for various critical sensor subsystems and services including: information dissemination, storage management, and localization. Based on experiences with these diverse applications, subsystems and services, we represent the basic sensor network design goal as a balance between the application-level utility of operations and the cost of operations in terms of resources. Quantifying these values (utility and cost) allows sensor nodes to determine how to carry out decisions (data collection and dissemination, as well as services related operations) most effectively at each sensor. However, the local estimate of utility and resource cost may not be accurate when considered globally. As a result, we have also introduced the concept of context, which represents some globally available information that has significant influence on the local estimate of either utility or resource cost. We formalize these ideas and investigate the challenges in applying them in a real sensor network system. We call this approach a Holistic Approach for Protocol Design in Sensor Networks.; Implementing the holistic approach requires a novel abstraction that explicitly exposes the cost and utility of operations so the estimated benefit of a decision can be compared against its cost. To that end, we propose a novel file system based abstraction for sensor networks that has several desirable properties for both system developers and application developers. A key feature of this abstraction is namespaces, which lets applications organize sensor networks in an application-specific manner; we advocate a standard resource namespace that exposes resource information, such as the available energy or storage space on a given sensor node, to the application. We demonstrate how a range of canonical sensor network applications can be built around the concept of namespace to provide richer yet resource efficient interfaces to sensor network users. Finally, we developed a scalable energy-efficient resource discovery framework so that heterogeneous sensors can discover resources in a platform independent manner. |
