淡江大學機構典藏:Item 987654321/35687
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 64198/96992 (66%)
造访人次 : 7964439      在线人数 : 8849
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library & TKU Library IR team.
搜寻范围 查询小技巧：
  • 您可在西文检索词汇前后加上"双引号"，以获取较精准的检索结果
  • 若欲以作者姓名搜寻，建议至进阶搜寻限定作者字段，可获得较完整数据
    •  进阶搜寻


    jsp.display-item.identifier=請使用永久網址來引用或連結此文件: https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/35687


    题名: Frequency synchronization and channel estimation for OFDM systems over frequency-flat channels: ML and LS approaches.
    其它题名: 正交分頻多工系統在頻率平坦通道中之頻率同步和通道估測研究利用最大概似率與最小平方估測法之研究
    作者: 洪明志;Hong, Ming-chih
    贡献者: 淡江大學電機工程學系碩士班
    嚴雨田;Yen, Rainfield Y.
    关键词: 正交分頻多工系統;最大概似估計法;載波頻率偏移;都卜勒展延;最小平方法;Orthogonal frequency division multiplexing (OFDM);maximum-likelihood (ML) estimation;carrier frequency offset (CFO);Doppler spread;least squares
    日期: 2008
    上传时间: 2010-01-11 07:00:54 (UTC+8)
    摘要: 正交分頻多工系統是新的調變技術用來抵抗多路經衰減效應。IEEE802.11a將OFDM定為標準規格。OFDM系統的一些優點：如降低計算複雜度、對抗窄頻干擾的能力、頻率分級的利用等等。在這篇論文中，我們考慮聯合頻率偏移和通道估測，但是我們先假定時間同步化的工作已經完成了。OFDM系統是在一個頻率平坦的環境下所做的。在這裡我們提出使用最大概似（ML）估計演算法來做聯合頻率偏移和通道估測。模擬的步驟：我們利用梯度圖來求得頻率偏移估測，再根據頻率偏移估測來求得通道頻率反應。然後在矯正頻率偏移後，我們再以合理假設運用最小平方法(least squares)求得通道估測做一比較。最後再將理論值跟模擬作比較。
    Orthogonal frequency division multiplexing (OFDM) is a new generation modulation technique. OFDM system is robust against the fading effects of multipath propagation. The IEEE 802.11a applies OFDM for wireless local area networks (WLAN) as standard specification. OFDM has several advantages ：reduced computational complexity、exploitation of frequency diversity、and robust against narrowband interference. In this paper, we consider joint frequency offset and channel estimation assuming timing synchronization has been completed .Flat fading channels are considered. We use a maximum-likelihood (ML) algorithm to jointly estimate the frequency offset and the channel frequency response (CFR). By first obtaining the frequency offset estimation using gradient plot, then the CFR estimation is obtained from the frequency offset estimation result. Further, an alternative approach using a least squares formulation for channel estimation is also presented based on completion of the frequency offset correction. Simulations are performed to compare with theoretical predictions.
    显示于类别:[電機工程學系暨研究所] 學位論文

    文件中的档案:

    档案 大小格式浏览次数
    0KbUnknown505检视/开启

    在機構典藏中所有的数据项都受到原著作权保护.

    TAIR相关文章

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library & TKU Library IR teams. Copyright ©   - 回馈