在單載波傳輸空間調變系統中，最大概似偵測器使用窮舉法，故擁有最佳之偵測效能，然而其複雜度也隨著星座點數與傳送天線數增加呈指數上升。相較於最大概似偵測器，樹狀搜尋演算法每層只保留當前最佳的M個路徑，故可以降低複雜度。現有文獻利用單載波傳輸空間調變系統其通道呈循環矩陣特性可直接使用樹狀搜尋，然而因通道衰減的緣故需要較大M值才能維持較低錯誤率，為了解決此問題，在訊號解調前通過頻域前置濾波器處理，可改善目標等效通道，提升其效能，然而以上兩者在星座點與傳送天線數較多情況下，樹狀搜尋複雜度仍然很高。本論文提出將二階段偵測演算法應用於樹狀搜尋中，首先偵測傳送天線序號，之後再做樹狀搜尋偵測調變符元，進一步降低樹狀搜尋範圍。根據模擬結果顯示，透過頻域前置濾波器處理的二階段偵測樹狀搜尋演算法其錯誤率令人滿意，且同時整體複雜度降低許多。

In the single-carrier spatial modulation (SCSM) systems, the maximum likelihood detector has the best detection performance since the exhaustive search is applied. However, the complexity increases exponentially with the number of constellation points and transmit antennas. Compared with the maximum likelihood detector, the tree search algorithms can reduce the complexity since it retains only the best M survivor paths at each layer. Previously, the M-algorithm was directly applied to the received signals by exploiting the block circulant structure in the channel matrix. Due to channel fading, however, the number of the survivor paths needs to be very large in order to retain a good detection performance. To overcome this issue, frequency-domain prefiltering can be used to improve the condition of the equivalent channel, but the complexity of tree search is still very high in the case of a large number of constellation points and transmit antennas. To reduce the tree search complexity, we propose in the thesis to apply the two-stage detection scheme to the tree search detectors. Specifically, the index of the transmit antenna is detected first before the tree search is performed to detect the modulation symbol transmitted over the given transmit antenna. Simulation results indicate that the two-stage detection scheme performs satisfactorily with the tree search detector that is assisted by the frequency-domain prefiltering. In the meanwhile, the overall complexity is considerably reduced.

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