EURASIP Journal on Wireless Communications and Networking 
Volume 2006 (2006), Article ID 47938, 12 pages
doi:10.1155/WCN/2006/47938

A Robust Parametric Technique for Multipath Channel Estimation in the Uplink of a DS-CDMA System

Vassilis Kekatos,1 Athanasios A. Rontogiannis,2 and Kostas Berberidis1

 1Department of Computer Engineering and Informatics and Research Academic Computer Technology Institute, University of Patras, Rio Patras 26500, Greece
2Institute of Space Applications and Remote Sensing, National Observatory of Athens, Palea Penteli, Athens 15236, Greece
Received 9 November 2004; Revised 22 November 2005; Accepted 28 December 2005

Recommended by Soura Dasgupta

Abstract

The problem of estimating the multipath channel parameters of a new user entering the uplink of an asynchronous direct sequence-code division multiple access (DS-CDMA) system is addressed. The problem is described via a least squares (LS) cost function with a rich structure. This cost function, which is nonlinear with respect to the time delays and linear with respect to the gains of the multipath channel, is proved to be approximately decoupled in terms of the path delays. Due to this structure, an iterative procedure of 1D searches is adequate for time delays estimation. The resulting method is computationally efficient, does not require any specific pilot signal, and performs well for a small number of training symbols. Simulation results show that the proposed technique offers a better estimation accuracy compared to existing related methods, and is robust to multiple access interference.