EURASIP Journal on Wireless Communications and Networking 
Volume 2004 (2004), Issue 2, Pages 322-334
doi:10.1155/S1687147204406070

Blind Channel Estimation for Space-Time Coded WCDMA

Youngchul Sung,1 Lang Tong,1 and Ananthram Swami2

 1School of Electrical and Computer Engineering, Cornell University, Ithaca 14853, NY, USA
2Army Research Laboratory, 2800 Powder Mill Read, Adelphi 20783, MD, USA
Received 29 November 2003; Revised 20 April 2004

Abstract

A new blind channel estimation technique is proposed for space-time coded wideband CDMA systems using aperiodic and possibly multirate spreading codes. Using a decorrelating front end, the received signal is projected onto a subspace from which channel parameters can be estimated up to a rotational ambiguity. Exploiting the subspace structure of the WCDMA signaling and the orthogonality of the unitary space-time codes, the proposed algorithm provides a blind channel estimate via least squares. A new identifiability condition is established under the assumption that the system is not heavily loaded. The mean square error of the estimated channel is compared with the Cramér-Rao bound, and the bit error rate (BER) performance of the proposed algorithm is compared with that of differential schemes.