Title: Multiuser channel estimation for closely spaced multipath CDMA signals using the unscented Kalman filter

Authors: Zahid Ali, Mohamed Adnan Landolsi, Mohammad A. Deriche

Addresses: Department of Electrical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. ' Department of Electrical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. ' Department of Electrical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia

Abstract: The paper introduces time delay and channel gain estimation for closely spaced multipaths in code division multiple access (CDMA) systems using the unscented Kalman filter (UKF). Given the non-linear dependency of the channel parameters on the received signals in multiuser/multipath scenarios, an iterative and non-linear filtering approach, namely UKF has been applied. The UKF produces channel estimates with the minimum mean-square error (MMSE) with an improved accuracy and consistency. A performance comparison with the conventional extended Kalman filter (EKF) has also been made. The UKF, which is a derivative-free Kalman filtering approach, avoids the errors associated with linearisation in the EKF. The Cramer-Rao lower bound (CRLB) has been derived for the proposed estimator and the simulation results clearly show that the UKF is simpler to implement and more resilient to near-far problem in CDMA networks.

Keywords: CDMA channel estimation; nonlinear recursive filtering; Kalman filters; multiple access interference; code division multiple access; CDMA networks.

DOI: 10.1504/IJUWBCS.2009.029004

International Journal of Ultra Wideband Communications and Systems, 2009 Vol.1 No.2, pp.151 - 158

Available online: 20 Oct 2009 *

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