tailieunhanh - Báo cáo hóa học: " A Robust Parametric Technique for Multipath Channel Estimation in the Uplink of a DS-CDMA System"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: A Robust Parametric Technique for Multipath Channel Estimation in the Uplink of a DS-CDMA System | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2006 Article ID 47938 Pages 1-12 DOI 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 1 Department of Computer Engineering and Informatics and Research Academic Computer Technology Institute University of Patras 26500 Rio Patras Greece 2 Institute of Space Applications and Remote Sensing National Observatory of Athens 15236 Palea Penteli Athens Greece Received 9 November 2004 Revised 22 November 2005 Accepted 28 December 2005 Recommended for Publication by Soura Dasgupta The problem of estimating the multipath channel parameters of a new user entering the uplink of an asynchronous direct sequencecode 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. Copyright 2006 Vassilis Kekatos et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Direct sequence-code division multiple access DS-CDMA is a widely accepted multiple access technique already in use in .