Wireless position location system using forward pilot signal

We propose a handset based TDOA position location system for CDMA network. To avoid a critical modification of handset, the proposed system exploits several DLL modules of fingers or off-line DLL modules to estimate TOAs from base stations. Since synchronization performance of DLL is degraded by near-far effect in general, we adopt an interference cancellation technique subtracting the reconstructed pilot signal from received signal at a handset. It can increase hearability and enhance performance in estimating TOAs of weak pilot signals from other base stations. Furthermore, the error in estimating TOA is minimized by using N-th order polynomial approximation. Through computer simulations, we showed that the proposed system has improved performance in estimating parameters and locating positions.