Positioning technologies for implementation of the always best located algorithm

New services in wireless communications are enforcing needs for accurate indoor and outdoor location technologies. Existing technologies are offering different coverage and accuracy, but none a pervasive location service. This paper first assesses the coverage and accuracy of the fundamental positioning technologies - GPS, WLAN-based, and GSM-based (Cell-ID and Trilateration) - by systematic measurements in various environments both indoor and outdoor. Then, an Always Best Located (ABL) algorithm is introduced and experimental performance results obtained in real situations are presented.