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 Scheduling for Multiuser MIMO Downlink Channels with Ranking-Based Feedback | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 854120 14 pages doi 2008 854120 Research Article Scheduling for Multiuser MIMO Downlink Channels with Ranking-Based Feedback Marios Kountouris 1 Thomas Salzer 2 and David Gesbert3 1 Wireless Networking and Communications Group Department of Electrical and Computer Engineering The University of Texas at Austin Austin TX 78712 USA 2 France Telecom Research and Development Issy-les-Moulineaux 92794 France 3 Mobile Communications Department Eurecom Institute Sophia-Antipolis F-06904 France Correspondence should be addressed to Marios Kountouris mkountouris@ Received 28 June 2007 Revised 10 October 2007 Accepted 26 January 2008 Recommended by Christoph Mecklenbrauker We consider a multi-antenna broadcast channel with more single-antenna receivers than transmit antennas and partial channel state information at the transmitter CSIT . We propose a novel type of CSIT representation for the purpose of user selection coined as ranking-based feedback. Each user calculates and feeds back the rank an integer between 1 and W 1 of its instantaneous channel quality information CQI among a set of W past CQI measurements. Apart from reducing significantly the required feedback load ranking-based feedback enables the transmitter to select users that are on the highest peak quantile with respect to their own channel distribution independently of the distribution of other users. It can also be shown that this feedback metric can restore temporal fairness in heterogeneous networks in which users channels are not identically distributed and mobile terminals experience different average signal-to-noise ratio SNR . The performance of a system that performs user selection using ranking-based CSIT in the context of random opportunistic beamforming is analyzed and we provide design guidelines on the number of required past CSIT samples and the impact of finite W on .
