在這篇論文裡,我們研究么正空間時間籬柵碼的解碼演算法。我們使用決定回授演算法作解碼,並以電腦模擬不同的觀察長度對錯誤效能的改進。我們再嘗試使用減少最佳籬柵狀態的方式作解碼,比較使用不同的籬柵狀態對錯誤效能的改進,並以此方法針對差分空時碼作解碼,在這裡考慮的通道為近似穩態平坦衰退通道(quasi-static flat fading channel)和連續平坦衰退通道(continuous flat fading channel)。 In this paper, we study the decoding algorithms for unitary space-time trellis codes. We use decision feedback algorithms for decoding. The improvement of error performance are verified by computer simulations with different observed length. We also propose to decode by reducing the state of optimal trellis. The error performance of using different number of trellis states are compared also. This decoding algorithms are applied to differential space-time codes as well. The channel considered here in are quasi-static flat fading channel and continuous flat fading channels.