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Student Number 955203028
Author CHIA-MU WU(吳珈穆)
Author's Email Address No Public.
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Department Communication Engineering
Year 2007
Semester 2
Degree Master
Type of Document Master's Thesis
Language zh-TW.Big5 Chinese
Title The OFDM System with a Semi-Blind Channel Tracking Algorithm
Date of Defense 2008-07-07
Page Count 81
Keyword
  • Channel Tracking
  • Semi-Blind
  • Abstract To deal with the channel effect in an OFDM time-varying channel, channel tracking is an important issue. We can have two methods to solve the channel effect problem. First, we use pilots to be inserted in transmitted signals, which significantly reduce the bandwidth efficiency. Second, we use a preamble along with decision feedback methods, which has better bandwidth efficiency than the first method. However, the drawback of the latter method is the requirement of a preamble between two successive data payloads. If the length of the frame is small, the bandwidth efficiency is also restricted. Therefore, we propose a semi-blind channel tracking method to improve the bandwidth efficiency. It is well-known that the decision feedback channel tracking method has the error propagation problem which can degrade the system performance. In contrast, the semi-blind channel tracking method applies a decision error criterion to change the use of the error control signal without the error propagation problem. Simulation results show that the proposed semi-blind channel tracking scheme has better BER performance than the decision feedback method.
    Table of Content 章節目錄
    第一章 序論1
    1.1.前言1
    1.2.研究動機2
    1.3.內容大綱2
    第二章 正交分頻多工系統之簡介3
    2.1.正交分頻多工系統之基本原理3
    2.2.循環字首4
    2.3.OFDM之優缺點5
    2.4.通道模型7
    2.4.1. 傑克斯通道模型簡介7
    2.4.2. 功率延遲數據圖(Power Delay Profile)9
    2.4.3. 自迴歸通道模型簡介11
    第三章 正交分頻多工系統之通道追蹤14
    3.1.802.11a之通道估測法14
    3.2.頻域之通道追蹤利用決策迴授機制16
    3.3.時域之通道追蹤利用決策迴授機制17
    3.4.平滑化通道估測19
    3.5.半盲目通道追蹤法21
    3.5.1. MCMA與相位回復演算法22
    3.5.2. Generalized Sato Algorithm(GSA)26
    3.5.3. Stop-and-Go Algorithm(SGA)27
    3.6.半盲目通道追蹤法與直接決策模型之切換準則28
    3.6.1. 通道追蹤模型切換28
    3.6.2. 切換法則29
    第四章 模擬與分析36
    4.1.系統以及通道模型之參數設定36
    4.2.不同Blind通道估測法利用自動切換準則之性能比較42
    4.3.MCMA與直接決策模式之切換準則模擬與分析44
    4.4.通道追蹤演算法之位元錯誤率性能模擬與分析55
    第五章 結論和未來展望65
    參考文獻67
    Reference 參考文獻
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    Advisor
  • Dah-Chung Chang(張大中)
  • Files
  • 955203028.pdf
  • approve in 2 years
    Date of Submission 2008-07-12

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