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Báo cáo hóa học: " Downlink Channel Estimation in Cellular Systems with Antenna Arrays at Base Stations Using Channel Probing with Feedback"

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: Downlink Channel Estimation in Cellular Systems with Antenna Arrays at Base Stations Using Channel Probing with Feedback | EURASIP Journal on Applied Signal Processing 2004 9 1330-1339 2004 Hindawi Publishing Corporation Downlink Channel Estimation in Cellular Systems with Antenna Arrays at Base Stations Using Channel Probing with Feedback Mehrzad Biguesh Department of Communication Systems University of Duisburg-Essen Bismarckstrasse 81 47057 Duisburg Germany Em ail biguesh@sent5.uni-duisburg.de Alex B. Gershman Department of Communication Systems University of Duisburg-Essen Bismarckstrasse 81 47057 Duisburg Germany Email gershman@sent5.uni-duisburg.de Received 21 May 2003 Revised 4 December 2003 In mobile communication systems with multisensor antennas at base stations downlink channel estimation plays a key role because accurate channel estimates are needed for transmit beamforming. One efficient approach to this problem is channel probing with feedback. In this method the base station array transmits probing training signals. The channel is then estimated from feedback reports provided by the users. This paper studies the performance of the channel probing method with feedback using a multisensor base station antenna array and single-sensor users. The least squares LS linear minimum mean square error LMMSE and a new scaled LS SLS approaches to the channel estimation are studied. Optimal choice of probing signals is investigated for each of these techniques and their channel estimation performances are analyzed. In the case of multiple LS channel estimates the best linear unbiased estimation BLUE scheme for their linear combining is developed and studied. Keywords and phrases antenna array downlink channel channel estimation training sequence. 1. INTRODUCTION In recent years transmit beamforming has been a topic of growing interest 1 2 3 4 5 . The aim of transmit beamforming is to send desired information signals from the base station array to each user and at the same time to minimize undesired crosstalks that is to satisfy a certain quality of service constraint for each user. .