在單載波區塊傳送系統中，處理由多路徑通道造成的符元間干擾是個重要的議題。最大概似偵測器具有最佳錯誤率效能，但當所用調變技術之星座點個數及區塊長度增加時，其複雜度呈指數增加。為了降低其複雜度，我們將樹狀搜尋演算法應用於此系統。傳統樹狀搜尋演算法需使用QR分解產生樹狀結構，但在實際系統的區塊長度下，QR分解之複雜度仍相當龐大。在本篇論文中，利用在傳送端與接收端皆已知的訓練序列，可不需使用QR分解就能產生樹狀結構，但此做法會增加樹狀搜尋的複雜度。為了克服此問題，我們使用頻域線性前置處理提升其效能。模擬結果顯示，我們提出的演算法與傳統樹狀搜尋演算法比較下，錯誤率效能相近，且整體複雜度較低。

In single-carrier block transmission systems, intersymbol interference (ISI) induced by multipath channels is an important issue. The optimal solution is the maximum likelihood detector (MLD), but its complexity is exponential in constellation size and block size. In order to reduce the complexity of MLD, we apply the tree search algorithm in the thesis. In the conventional tree search algorithms, QR decomposition is used to generate the tree structure. However, the complexity of QR decomposition is very high for the block sizes adopted in practical systems. In this thesis, we propose a tree search algorithm without QR decomposition by exploiting the training sequence that is known at both the transmitter and receiver. This however increases the complexity in tree traversal if the same performance level is to be maintained. To overcome this issue, frequency domain linear preprocessing is incorporated. Simulation results show that the proposed algorithm achieves a performance similar to that of conventional tree search algorithm with a lower overall complexity.

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