Geographic location information is critical in wireless sensor network. Ÿe distributed sensors should organize a coordinate system so that the physical coordinates of any node or any detected object can be determined. Integrating GPS receivers on all the sensors are too expensive for huge-sized networks, so localization using limited numbers of GPS resources is very important for many tasks in sensor networks. Localization must be accurate and reliable while the cost must be as little as possible. To solve this important problem, many algorithms, hardware, and applications have been explored recently. However, several key issues to support accurate localization for critical detections in complex and real environments have not been solved adequately (Figure 31.1).
