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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: Blind Channel Estimation for Space-Time Coded WCDMA Youngchul Sung | EURASIP Journal on Wireless Communications and Networking 2004 2 322-334 2004 Hindawi Publishing Corporation Blind Channel Estimation for Space-Time Coded WCDMA Youngchul Sung School of Electrical and Computer Engineering Cornell University Ithaca NY 14853 USA Email ys87@ece.cornell.edu Lang Tong School of Electrical and Computer Engineering Cornell University Ithaca NY 14853 USA Email ltong@ece.cornell.edu Ananthram Swami Army Research Laboratory 2800 Powder Mill Read Adelphi MD 20783 USA Email a.swami@ieee.org Received 29 November 2003 Revised 20 April 2004 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 Cramer-Rao bound and the bit error rate BER performance of the proposed algorithm is compared with that of differential schemes. Keywords and phrases space-time coding long code CDMA least squares blind channel estimation. 1. INTRODUCTION Future wireless systems will require high rate transmission of multimedia data over time-varying fading channels. This is especially the case for the downlink where a mix of voice low rate data and possibly images are transmitted to mobile users. To increase the capacity and provide reliable communication over fading channel diversity techniques in space and time are expected to play a crucial role 1 2 3 4 . A variety of space-time coding schemes have been proposed with multiple transmit antennas and a single or .