TAILIEUCHUNG - Bài giảng về: BỂ BÙN HOẠT TÍNH

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems–Part I: MIMO Case | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 549197 8 pages doi 2010 549197 Research Article Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems-Part I MIMO Case Erol Onen 1 Aydin Akan EURASIP Member 1 and Luis F. Chaparro EURASIP Member 2 1 Department of Electrical and Electronics Engineering Istanbul University Avcilar 34320 Istanbul Turkey 2 Department of Electrical and Computer Engineering University of Pittsburgh Pittsburgh PA 15261 USA Correspondence should be addressed to Aydin Akan akan@ Received 1 February 2010 Accepted 14 May 2010 Academic Editor Lutfiye Durak Copyright 2010 Erol Onen 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. Multiple-input multiple-output MIMO systems hold the potential to drastically improve the spectral efficiency and link reliability in future wireless communications systems. A particularly promising candidate for next-generation fixed and mobile wireless systems is the combination ofMIMO technology with Orthogonal Frequency Division Multiplexing OFDM . OFDM has become the standard method because of its advantages over single carrier modulation schemes on multipath frequency selective fading channels. Doppler frequency shifts are expected in fast-moving environments causing the channel to vary in time that degrades the performance of OFDM systems. In this paper we present a time-varying channel modeling and estimation method based on the Discrete Evolutionary Transform to obtain a complete characterization of MIMO-OFDM channels. Performance of the proposed method is evaluated and compared on different levels of channel noise and Doppler frequency shifts. 1. Introduction The major challenges in future wireless communications systems are increased spectral .

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