現今無線通訊的研究中，常以分集(diversity)的技術來增加訊號傳輸的準確性。於現實環境中，接收端常為手機或運算及功率皆非充足的其它行動裝置為多，而因此利用時空碼(space-time codes)使分集的特性應用在運算及功率皆較充足的基地台傳送端。
　　多重輸入多重輸出(MIMO)的系統中，亦有轉移接收端運算以及複雜度，傳送最佳化多重輸入多重輸出(TO-MIMO)的架構，將通道估測與接收訊號結合(combining)的運算轉移至基地台傳送端。
　　本篇論文其一在探討正交分頻多工調變(OFDM)的分頻多工(FDD)調變系統中，如何將簡化接收端的技術結合，且找出利用引導位元(pilot symbol)與訊號編排後達成通道估測的原則，並分析其利弊以提出一個實際可行的系統架構。而另一則是在不同的可行架構中與布雷斯特系統做比較，探討資料量與效能間的取捨問題。

　　For the researches of wireless communications nowadays, diversity technologies are likely used to ensure the accuracy of signal transmission. In the real world, receivers are usually those mobile receivers without strong computing ability and enough power, like cell phones. It makes us to use Space-Time (ST) Codes to apply diversity techniques to the base stations which are sufficient for computing and power. In the Multi-Input Multi-Output (MIMO) system, there is also a structure that can put the computing at the base station, called Transmit Optimization (TO)-MIMO. That can do channels estimation and signals combining at the base station.
　　This thesis discusses the combination of above techniques with Orthogonal Frequency Division Modulation (OFDM) systems. We also address on how to setup a format of pilot and data symbols to make channel estimation work. We shall analyze and design a practical system structure and compare it with the V-BLAST system to find a trade off between them.

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