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Mathematical Problems in Engineering
Volume 2013, Article ID 307342, 8 pages
http://dx.doi.org/10.1155/2013/307342
Research Article

Channel Estimation for DS-CDMA Systems: A Partial Difference Equation Approach

1School of Control Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061, China
2School of Control Science and Engineering, The University of Jinan, Jiwei Road 106, Jinan 250022, China

Received 23 January 2013; Accepted 25 February 2013

Academic Editor: Xiaojie Su

Copyright © 2013 Wei Wang and Chunyan Han. 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.

Abstract

In the communications literature, a number of different algorithms have been proposed for channel estimation problems with the statistics of the channel noise and observation noise exactly known. In practical systems, however, the channel parameters are often estimated using training sequences which lead to the statistics of the channel noise difficult to obtain. Moreover, the received signals are corrupted not only by the ambient noises but also by multiple-access interferences, so the statistics of observation noises is also difficult to obtain. In this paper, we will investigate the channel estimation problem for direct-sequence code-division multiple-access (DS-CDMA) communication systems with time-varying multipath fading channels. The channel estimator is designed by applying a partial difference equation approach together with the innovation analysis theory. This method can give a sufficient and necessary condition for the existence of an channel estimator.