Adaptive channel estimation algorithm for QS-CDMA signals

In this paper, we consider an adaptive channel estimator for quasi-synchronous CDMA (QS-CDMA) systems, where mobiles synchronize their transmission to a common GPS-generated clock. An extended Kalman filter (EKF) is employed to track user delays and channel coefficients. QR decomposition with the M-algorithm (QRD-M) is proposed for data detection. However, due to the EKF, the computational complexity is still high. To minimize this computational complexity, we employ an adaptive channel estimator for QS-CDMA signals, where the EKF is adaptively applied depending on the quasi-stationarity of the channel in two symbol intervals.