Closely spaced multipath channel estimation in CDMA networks using divided difference filter

Abstract

We investigate time delay and channel gain estimation for multipath fading code division multiple access (CDMA) signals using the second order divided difference filter (DDF). We consider the case of paths that are a fraction of chip apart, also knwon as closely spaced paths. Given the nonlinear dependency of the channel parameters on the received signals in multiuser/multipath scenarios, we show that the DDF achieves better performance than its linear counterparts. The DDF, which is a derivative-free Kalman filtering approach, avoids the errors associated with linearization in the conventional extended Kalman filter (EKF). The numerical results also show that the proposed DDF is simpler to implement, and more resilient to near-far interference in CDMA networks and is able to track closly spaced paths. © 2009 Springer-Verlag Berlin Heidelberg.