, a sensor network is subject environment. In the not-too-distant future, tiny, dirt- to a unique set of resource constraints such as finite cheap sensors may be literally sprayed onto roads, walls, on-board battery power and limited network communi- or machines, creating a digital skin that senses a variety of cation bandwidth. In a typical sensor network, each physical phenomena of interest: monitor pedestrian or sensor node operates untethered and has a microproces- vehicular traffic in human-aware environments and in- sor and a small amount of memory for signal processing telligent transportation grids, report wildlife habitat and task scheduling. Each node is also equipped with one conditions for environmental conservation, detect forest or more sensing devices such as acoustic microphone fires to aid rapid emergency response, and track job flows arrays, video or still cameras, infrared (IR), seismic, or and supply chains in smart factories. Unlike current in- magnetic sensors. Each sensor node communicates formation services such as those on the Internet where wirelessly with a few other local nodes within its radio information can easily get stale or be useless because it is communication range. too generic, sensor networks promise to couple end users Sensor networks extend the existing Internet deep directly to sensor measurements and provide information into the physical environment. The resulting new net- that is precisely localized in time and/or space, according work is orders of magnitude more expansive and dynamic to the user's needs or demands. than the current TCP/IP network and is creating entirely With such technological advances come new new types of traffic that are quite different from what challenges for information processing in sensor networks. one finds on the Internet now. Information collected by What is needed are novel computational representations, and transmitted on a sensor network describes conditions algorithms and protocols, and design methodologies and of physical environments-