在本篇論文中，討論兩種系統。一個是引導符號插入的調變系統，而另一個是差分相位調變系統。在引導符號插入的調變系統，提出一個結合通到預測與渦輪編碼的演算法，所提出的通道預測方法是基於最小平方適合理論。此方法和線性信最佳的最小平均平方差錯誤的通道預測相比，它並不需要考慮衰減速率或雜訊變異的通道參數。
對渦輪編碼差分相位調變系統在有相關性的平坦衰減通道，兩種架構在本篇論文被提出，一個是近似最佳的軟輸入軟輸出順向逆向最大事後機率偵測，另一個是次佳的順向逆向多符號差分圓半徑解碼。一個串接疊代軟輸入軟輸出順向逆向最大事後機率偵測與軟輸入軟輸出解碼器被提出來在不降低性能下來降低計算複雜度。模擬結果顯示順向逆向最大事後機率偵測和事後機率解調器、軟輸入軟輸出最大事後機率偵測、軟輸入軟輸出多符號差分圓半徑解碼比起來，在較低的複雜度下可以提供相同或更好的位元錯誤率。雖然複雜度要比疊代濾波器多差分偵測架構來的高，但可以提供較好的位元錯誤率
輸入軟輸出多符號差分圓半徑解碼在複雜度隨偵測長度成平方下，可以提供次佳的性能。爲了進一步減少複雜度，用於差分相位調變編碼系統的順向逆向多符號差分圓半徑解碼被提出，主要的想法是將偵測的區間分成兩個次區間，這兩個次區間分別執行順向逆向的程序。模擬結果顯示順向逆向多符號差分圓半徑解碼和軟輸入軟輸出多符號差分圓半徑解碼比起來，有幾乎相同的性能和較低的複雜度。

In this thesis, two systems are discussed. One is pilot symbol assisted modulation (PSAM) system, and the other is differential modulation system. For PSAM system, the algorithm of iterative channel estimation and turbo decoding is proposed. The proposed channel estimation is based on least squared fitting (LSF) theorem. Compared with the linear optimum MMSE (minimum mean square error) channel estimation, it doesn’t require any channel characteristic like as fading rate or noise variance.
For turbo-coded differential phase shift keying (DPSK) systems under correlated flat fading channels, two schemes are proposed. One is the near optimal schme, soft-input soft-output (SISO) forward/backward maximum a posteriori (FB-MAP), and the other is the suboptimal scheme, Forward/Backward multiple-symbol differential sphere decoder (FB-MSDSD). A serial iterative structure of SISO FB-MAP detection and SISO turbo decoder is proposed to reduce the computational complexity of MAP detection without performance degradation. The simulation results show that the FB-MAP detection scheme offers the same or better bit error rate (BER) performance with lower computational complexity when compared with a posteriori probability (APP) demodulator, SISO MAP detection and SISO MSDSD scheme. And, though the computational complexity is higher than iterative filtered multiple differential detection (IF-MDD) schemes, the proposed detection scheme can have better BER performance.
The SISO MSDSD can offer suboptimal performance and its complexity is quadratic with detection length. To further reduce the complexity, the FB-MSDSD scheme for coded DPSK systems is proposed. The key idea is that the detection interval is split into two subintervals which are processed in the forward and backward directions respectively. Simulation results show that the proposed scheme has almost the same performance and lower complexity when compared with the SISO-MSDSD scheme with the same detection length.

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