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: Research Article Stable Transmission in the Time-Varying MIMO Broadcast Channel | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 617020 14 pages doi 2008 617020 Research Article Stable Transmission in the Time-Varying MIMO Broadcast Channel Adam L. Anderson 1 James R. Zeidler 1 and Michael A. Jensen2 1 Department of Electrical and Computer Engineering University of California San Diego CA 92093-0407 La Jolla USA 2 Department of Electrical and Computer Engineering Brigham Young University Provo UT 84602 USA Correspondence should be addressed to Adam L. Anderson a3anders@ Received 1 June 2007 Revised 28 September 2007 Accepted 19 December 2007 Recommended by Christoph Mecklenbrauker Both linear and nonlinear transmit precoding strategies based on accurate channel state information CSI can significantly increase available throughput in a multiuser wireless system. With propagation delay infrequent channel updates lag due to network layer overhead and time-varying node position or environment characteristics channel knowledge becomes outdated and CSI-based transmission schemes can experience severe performance degradation. This paper studies the performance of precoding techniques for the multiuser broadcast channel with outdated CSI at the transmitter. Traditional channel models as well as channel realizations measured by a wideband channel sounder are used in the analysis. With measured data from an outdoor urban environment it is further shown the existence of stable subspaces upon which transmission is possible without any instantaneous CSI at the transmitter. Such transmissions allow for consistent performance curves at the cost of initial suboptimality compared to CSI-based schemes. Copyright 2008 Adam L. Anderson 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 The time-varying multiuser .
