臺灣博碩士論文加值系統

在本篇論文中，探討正交分频分多工（Orthogonal Frequency-Division Multiplexing,OFDM）系统中，利用臨界值結合Regularized Least-Squares估計法進行稀疏通道估計處理。Regularized Least-Squares估計法利用通道係數的時域相關性，使用已知pilot資訊以及最新通道估計結果來更新通道。再進一步，考慮多重路徑通道係數所具有的稀疏特性，可以利用臨界值判斷處理來取得非零值通道係數，以進一步提升Regularized Least-Squares估計法的效能。最後模擬結果顯示，與傳統的最小平方法相比，臨界值結合Regularized Least-Squares估計法，在稀疏通道估測上可以有更低的均方誤差及更好的估計性能。

In this thesis,we combine thresholding with the Regularized Least- Squares method to estimate sparse channels in Orthogonal Frequency-Division Multiplexing systems.The Regularized Least-Squares method is based on temporal channel correlation,and this method uses recieved pilot symbol and latest channel information to update channels.Considering the sparse nature of multipath channels,the threshold can be used to get significant taps,and further improve the performance of the Regularized Least-Squares method.Simulation results show that compared to the Least Squares method channel estimation,the threshold combined with the Regularized Least-Squares method to estimate sparse channels can reduce the mean square error and better estimate performance.

第一章 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 OFDM 架構演進 3
2.2 OFDM 系統架構 4
2.3 調變(Modulation) 5
2.4 OFDM 正交特性(Orthogonal Property) 6
2.5 循環字首(Cyclic Prefix, CP) 7
2.6 pilot訊號排列 8
第三章 OFDM系統模型 11
3.1通道模型 11
3.2 系統模型 12
第四章 通道估測技術 14
4.1 最小平方法(Least Square Method，LS) 14
4.2 Regularized Least-Squres Method 15
第五章 估計稀疏通道演算法 20
5.1 Threshold-based modified Least Squres(TmLS)Method 20
5.2 臨界值結合Regularized LS估計法 24
第六章 分析模擬結果 25
第七章 結論 34
參考文獻 35

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