多媒體的高品質與高碼率要求，在未來無線通訊系統中越來越顯得重要。近年來，透過多傳送與接收天線在頻率非選擇性衰退通道下通訊之研究引起廣大的注意。其中一種方法為藉由提高傳送或接受端之天線數，以符合高通道容量與高碼率之要求，而時間空間碼建構方式普遍地被利用於多重傳送與接收天線系統上。此外，線性調變是一種簡單且快速的調變機制，在數位無線通訊上有著廣泛的利用。但是傳統時間空間碼線性調變結構，在頻率非選擇性衰退通道下將不再適用。事實上，在移動無線通訊系統內，傳送端與接受端天線數量受到極大限制。必須發展出在少量天線條件下，依然有高品質傳輸效率之編碼方式。
在本論文中，我們推導出在頻率非選擇性衰退通道下線性調變之時間空間碼設計準則，此準則是基於特殊的時間空間碼架構模型，此模型包括一個迴旋編碼器及一個空間編碼器。在相同的天線條件下，迴旋編碼器將提供更高的多重性增益，以保持高品質的傳輸率。而除法代數提供簡單的數學模式來建造線性調變之時間空間碼，以符合所推導出的時空碼準則。另外，我們放置一個交錯器於迴旋編碼器與空間編碼器間，以對抗與時間相關之衰退通道。而解碼結構為一個交解碼器與一個維特比解碼器。最後在相同頻寬效率下不同時間空間編碼做模擬圖之比較與探討。

In this thesis, we derive a new space-time code design criterion for linear modulation over frequency-nonselective fading channels. In order to achieve maximum transmit spatial diversity, we first adopt a method in the literature to use division algebras to design an inner space-time code length equal to the number of transmit antennas. Then this short inner space-time code in concatenated with a ring systematic convolutional encoder to encode a space-time code of full length to achieve the maximum transmit diversity. For practical channels, we place an interleaver between convolutional encoder and the mini space-time encoder to combat the correlated fading. Both theoretical analytic and simulation results show that our proposed coding scheme is very effective.

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