Wireless Location Technologies and Applications

Technologies for location and tracking are fast maturing with an array of new techniques, new algorithms, system designs, and trials bringing location-based services into everyday life. This once niche technology is maturing and gaining wider acceptance, thus finding more and more applications every day. The development of communications systems that include location and tracking capabilities has generated great interest also in the fields of cellular and wireless local/per-sonal area networks. A host of potential new services can be enabled by suitably accurate location and tracking facilities in conjunction with appropriate communications and data transfer platforms. Researchers worldwide are pushing the boundaries of precision, low-cost, component reusabil-ity, and ease of field deployment. From established radio techniques, such as WLAN (e.g., IEEE 802.11 a/b/g) to emerging WPAN networks (e.g., Blue-tooth and IEEE 802.15.4) to newer ultra-wideband (UWB) systems (e.g., IEEE 802.15.3a and IEEE 802.15.4a), and further previously unconsidered technologies such as digital TV signals, a common denominator to drive adoption and growth is implementing innovative services on top of data transfer. Whether the positioning techniques are based on signal strength, time of flight, or fingerprinting techniques, they offer the potential to improve and optimize traditional services (as diverse as flight navigation or data routing) or bring to life new applications relying on the knowledge of the location of the wireless nodes. A large number of issues must be addressed to move from coarse delay measurement to useful range estimation for tracking purposes. Issues include generation of accurate de-lay/ranging estimates, proper operation in dense multipath environments, delay/ranging information sharing between nodes, computationally efficient algorithms, algorithms for low infrastructure environments, dealing with nonline of sight as well as integration with usable applications. The aim of this special issue is to address the state of the art in wireless location technologies and applications with particular emphasis on accurate results in low infrastructure environments. We classified the 16 contributions into 3 major categories , namely, performance analysis, algorithms, and systems/ applications. " Systematic errors and location accuracy in wireless networks " by Harri Saarnisaari and Timo Bräysy is the first paper in the category " performance analysis " and provides a unified error-propagation-law-based tool to analyze measurement and systematic errors. The tool is used in order to compare hyperbolic (time delay based), direction finding, received signal strength (RSS), and relative RSS (RRSS), location systems. The obtained analytical results verify several intuitive expectations, for example, that the …