Some useful services in cellular radio networks and also a class of handove
r algorithms require knowledge of the present position and velocity of mobi
les. This paper deals with a method to track mobiles by on-line monitoring
of held strength data of surrounding base stations at successive time point
s. Such data is available in present global system for mobile communication
(GSM) systems each 0.48 s and also in code-division multiple-access (CDMA)
systems for transmission control. Because of strong random fluctuations of
the signals, appropriate smoothing is the key point of the procedure. We d
evelop a locally linear prediction model of successive positions as a basis
for Kalman filtering. This approach turns out to be extremely successful,
achieving average mislocations of 70 m in simulated test runs. Further impr
ovement is possible by using external geographical information.