Adaptive parameter estimation using parallel Kalman filtering for spread spectrum code and Doppler tracking

We present a new digital direct-sequence (DS) receiver with joint estimation of code delay, multipath gains and Doppler shift. A parameter estimator consisting of a parallel bank of extended Kalman filters (EKF´s) extracts estimates of the timing, τ and the multipath coefficients, f_l distorting the received signal. A “detected” estimate of the Doppler shift, v_r distorting the received signal is also provided by the estimator. We compute the bit error rate that results when a RAKE matched filter uses the estimated parameters to detect the DPSK encoded binary data in the received signal. The bit-error rate (BER) is evaluated, and successful performance of the proposed receiver in the presence of Doppler shift distortion is observed in many cases. We demonstrate that the receiver can operate when the multipath coefficients vary in time (Doppler spread)