A system for locating a number of devices (112-130) by measuring signals transmitted between known location devices (112-118, 134-138, 214-218, 224-228) and unknown location devices (120-130, 222), and signals transmitted between pairs of unknown location devices (120-130, 222), entering signal measurements...http://www.google.de/patents/US20020122003?utm_source=gb-gplus-sharePatent US20020122003 - Method and apparatus for location estimation