Date Added: Nov 2010
The location of a mobile user has become an important requirement for modern applications in the area of ubiquitous computing. The Global Positioning System (GPS) is still the leading technology for outdoor navigation, but the situation is not as clear-cut when it comes to indoor positioning. There are a number of proposed designs based on technologies such as ultrasound, Bluetooth, infrared, Wi-Fi, GSM networks or other types of radios. The shortcomings of these systems are mostly related to laborious deployment, low accuracy or expensive/dedicated hardware. In practice, one typically has to make a trade-off between the accuracy performance and the deployment costs, such that the solution becomes cost effective.