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Báo cáo hóa học: " A Technique for Dominant Path Delay Estimation in an OFDM System and Its Application to Frame "

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: A Technique for Dominant Path Delay Estimation in an OFDM System and Its Application to Frame | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2006 Article ID 86147 Pages 1-8 DOI 10.1155 WCN 2006 86147 A Technique for Dominant Path Delay Estimation in an OFDM System and Its Application to Frame Synchronization in OFDM Mode of WMAN Ch. Nanda Kishore and V. U. Reddy Hellosoft India Pvt Ltd. 8-2-703 Road no. 12 Banjara Hills Hyderabad 500 034 India Received 15 February 2006 Revised 22 June 2006 Accepted 10 October 2006 Recommended for Publication by Sangarapillai Lambotharan Orthogonal frequency division multiplexing OFDM is a parallel transmission scheme for transmitting data at very high rates over time dispersive radio channels. In an OFDM system frame synchronization and frequency offset estimation are extremely important for maintaining orthogonality among the subcarriers. Recently several techniques have been proposed for frame synchronization in OFDM system. In multipath environment the transmitted signal arrives at the receiver through direct and multiple delayed paths. In some cases it is possible that power of the signal arriving through delayed path may be larger than that of the direct path earliest path if there is no direct path . In those cases estimate of the frame boundary may be shifted by a quantity equal to the delay of the dominant path. In such cases there will be intersymbol interference ISI in the demodulated symbols unless the frame boundary estimate is preadvanced such that it dwells in the ISI-free portion of cyclic prefix or at the symbol boundary. In this paper we propose a method for estimating the shift in the frame boundary estimate using a preamble having two identical halves. We assume that frame boundary and frequency offset estimation have been performed prior to the estimation of the shift. We also examine the quality of the frequency offset estimate when the frame boundary estimate is shifted from the desired value. The proposed method is applied to downlink synchronization in