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研究生： 邱顯正
Hsien-cheng Chiu
論文名稱： 正交分頻多工系統通道估測基於可適性模型化通道參數估測
Model-Based Channel Estimation for OFDM with Adaptive Model Parameter Estimation
指導教授： 張大中
Dah-chung Chang
口試委員:
學位類別： 碩士
Master
系所名稱： 資訊電機學院 - 通訊工程學系
Department of Communication Engineering
畢業學年度： 95
語文別： 中文
論文頁數： 90
中文關鍵詞： 通道估測 、正交分頻多工
外文關鍵詞： OFDM, channel estimation
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    • 基於模型化通道估測法之正交分頻多工系統是利用均勻分布的領航訊號以最小平方法則演算法估測於局部區域內迴歸模型的通道參數。然而，要得到迴歸模型的通道參數必須使用較多的領航訊號才能有降低雜訊的效果，因此造成必須要有較大的記憶體容量和計算複雜度的缺點。基於局部區域之間模型參數的連續性，本論文提出新的模型化通道估測法，只需要與模型化通道參數相同數目的領航訊號，即可利用遞迴方程式達到持續有效的可適性通道模型參數估測，並且由於局部區域內只需要少量領航訊號數目，因此可以節省內插符元於迴歸模型時記憶體的容量。理論的分析和模擬皆顯示所提出的通道模型參數估測方式都可以得到較佳的性能。

    The OFDM model-based channel estimation technique uses the least squares method to estimate model parameters through uniformly distributed pilots in a local region. However, the regression model must use as many pilots as possible to reduce the effect of noises. Therefore, it increases storage size and computational complexity. Since model parameters has the continuity characteristics between neighboring local regions, a new model-based channel estimation method is proposed to adaptively estimate model parameters by recursive equations such that the required number of pilots is reduced, where the used number of pilots is the same as the number of model parameters and thus, the new algorithm reduces the required storage size for interpolating the symbols used in the regression model. Theoretical analyses and simulations show that better performance is obtained as well by the proposed parameter estimation method.

    第一章 研究動機與簡介................................. 1 第二章 正交分頻多工系統之基本原理與架構............... 3 2.1 位元映射(Mapping)成符元........................... 3 2.2 反離散傅立葉轉換.................................. 4 2.3 循環字首.......................................... 5 2.4 無線通道環境...................................... 7 2.5 離散傅立葉轉換.................................... 9 第三章 正交分頻多工系統之通道估測..................... 10 3.1 領航(Pilot)訊號的配置............................. 11 3.2 傳統的通道估測演算法.............................. 15 3.2.1 最小平方(LS)誤差通道估測........................ 15 3.2.2 線性最小平均平方誤差(LMMSE)通道估測............. 16 3.3 內插(Interpolation)方式的討論..................... 17 3.3.1 線性內插....................................... 17 3.3.2 2階多項式內插.................................. 18 3.3.3 Cubic內插...................................... 19 第四章 模型化通道估測................................. 22 4.1 2階多項式曲面模型(2-D)........................... 22 4.1.1 模型化2-D通道估測............................... 25 4.1.2 模型化2-D通道估測之性能分析..................... 27 4.1.3 討論............................................ 30 4.2 2階多項式曲線模型(1-D)........................... 31 4.2.1 模型化1-D通道估測............................... 33 4.2.2 模型化1-D通道估測之性能分析..................... 35 4.2.3 討論............................................ 39 4.3 可適性模型化通道參數估測.......................... 41 4.3.1 可適性估測...................................... 41 4.3.2 近似可適性LMS演算法............................. 43 4.3.3 可適性估測之性能分析............................ 45 4.3.4 討論............................................ 47 4.4 可調式的Beta值.................................... 49 4.5 Kalman Filter追蹤模型化通道參數................... 51 第五章 模擬與分析..................................... 53 5.1 Jakes’通道模型參數設定........................... 54 5.2 傳統通道估測之模擬與分析.......................... 57 5.3 1-D模型化通道參數估測之模擬與分析................. 62 5.4 可適性模型化通道參數估測之模擬與分析.............. 68 5.5 Kalman Filter追蹤模型化通道參數之模擬與分析....... 79 第六章 結論和未來展望................................. 87 參考文獻.............................................. 89

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