Mobile position tracking by TDOA-Doppler hybrid estimation in mobile cellular system

An effective method is presented for position tracking of a moving mobile terminal (MT). The method is based on time/distance difference of arrival (TDOA) estimation and Doppler measurements. TDOA locationing based on Chan's method provides an analytical solution which is closer to the Cramer-Rao Lower Bound(CRLB).However its accuracy is affected by multi-access interferences and non-line-of-sight(NLOS), thus making Doppler-aided positioning a good complementary technique due to its independency of the above effects. After acquiring the initial position of NIT using TDOA information, the moving track is estimated by a hybrid method which combines TDOA with Doppler. Simulation results show this hybrid method can achieve better performance than TDOA or Doppler technique.