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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/18449

Title: 正交分頻多工系統S&C同步方法之修正改善研究
Modification of the S&C Synchronization Method for a OFDM System
Authors: Wai-Tse Sun
孫維澤
Contributors: NTOU:Department of Communications Navigation and Control Engineering
國立臺灣海洋大學:通訊與導航工程系
Keywords: 同步;時間偏移;載波頻率偏移;正交分頻多工
Synchronization;Time Offset;Carrier Frequency Offset;OFDM
Date: 2010
Issue Date: 2011-07-04
Abstract: 正交分頻多工(Orthogonal Frequency Division Multiplexing, OFDM) 技術具有對抗頻率選擇性衰減與高頻寬效益等優點。而同步是必須克服的問題之一。時間偏移會造成符元間干擾(Inter Symbol Inference, ISI),進而降低資料傳輸正確率。載波頻率偏移會造成載波間干擾(Inter Carrier Interference, ICI),使得系統位元錯誤率(Bit Error Rate, BER)大幅增加。 S&C方法是在西元1997年由T.M. Schmidl and D.C. Cox[1]所提出,本論文針對OFDM系統之S&C同步問題,提出三個改善方法。S&C方法在估測時間偏移方面,時間定量(Timing Metric)有嚴重的平頂問題,首先提出修正式S&C,利用擾亂碼加於CP(Cyclic Prefix)改善平頂問題。再者利用最大概似估計觀念用在S&C Preamble,提出修正式S&C最大概似估計法。最後再提出修正式S&C反覆最大概似估計法,模擬顯示對於時間及頻率偏移能更進一步提昇準度。
Orthogonal Frequency Division Multiplexing (OFDM) technique has the advantages of high data rata transmission and robustness to the multipath fading. However, OFDM systems have two major drawbacks. First, the time offset problem will cause the Inter Symbol Inference (ISI). Second, the frequency offset problem will also greatly degrade the system performance. S&C method was proposed by T.M. Schmidl and D.C. Cox[1] in 1997. In this paper, we propose three modified methods to improve the S&C synchronization method problem for OFDM system .Simulation results demonstrate the abilities of the proposed methods for the synchronization problem.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97670030
http://ntour.ntou.edu.tw/ir/handle/987654321/18449
Appears in Collections:[通訊與導航工程學系] 博碩士論文

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