tailieunhanh - Báo cáo hóa học: " Joint Frequency Ambiguity Resolution and Accurate Timing Estimation in OFDM Systems with Multipath Fading"

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: Joint Frequency Ambiguity Resolution and Accurate Timing Estimation in OFDM Systems with Multipath Fading | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2006 Article ID 62173 Pages 1-7 DOI WCN 2006 62173 Joint Frequency Ambiguity Resolution and Accurate Timing Estimation in OFDM Systems with Multipath Fading Jun Li 1 Guisheng Liao 1 and Shan Ouyang2 1 National Laboratory of Radar Signal Processing Xidian University Xi an 710071 China 2 Department of Communication and Information Engineering Guilin University of Electronic Technology Guilin 541004 China Received 29 May 2005 Revised 28 September 2005 Accepted 4 November 2005 Recommended for Publication by Lawrence Yeung A serious disadvantage of orthogonal frequency-division multiplexing OFDM is its sensitivity to carrier frequency offset CFO and timing offset TO . For many low-complexity algorithms the estimation ambiguity exists when the CFO is greater than one or two subcarrier spacing and the estimated TO is also prone to exceeding the ISI-free interval within the cyclic prefix CP . This paper presents a method for joint CFO ambiguity resolution and accurate TO estimation in multipath fading. Maximumlikelihood ML principle is employed and only one pilot symbol is needed. Frequency ambiguity is resolved and accurate TO can be obtained simultaneously by using the fast Fourier transform FFT and one-dimensional 1D search. Both known and unknown channel order cases are considered. Computer simulations show that the proposed algorithm outperforms some others in the multipath fading channels. Copyright 2006 Jun Li 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 Orthogonal frequency-division multiplexing OFDM is an effective technique to deal with the multipath fading channel in high-rate wireless communications 1 . It has been chosen for the European digital audio and video .