應用於非同調編碼調變系統之遞迴式相位同步設計

Abstract

隨著現有系統操作在低功率的情況下，turbo principle的解碼方式已成為主流，伴隨而知的同步問題逐漸越來越重要。在此論文裡，我們考慮編碼調製(coded modulation)的系統，此系統並沒有明確的提供同調相位的資訊。我們研究其演算法可針對相位的模糊(phase ambiguity)解決和估測在高斯(AWGN)通道下做模擬。 一個簡單實現的串接式(serially-concatenated)的編碼系統可利用迴旋的方式來解碼並加上相位的估測。在每次的迴旋解碼中，我們利用事後機率來估測相位，並在下一次解碼前做補償。我們將面對不同型態的相位模型做考量，並且得到不錯的錯誤率效果。

As communication systems operate at low signal-to-noise ratio conditions, synchronization may become a serious problem. In the thesis, we consider the coded modulation systems which are not explicitly provided with the information of coherent phases. We investigate algorithms for joint carrier phase estimation and ambiguity resolution for the AWGN channel. An easily-implemented serially-concatenated coding system is presented that can oper- ate with phase estimation technique which is integrated into the iterative decoding loop. At each iteration, we use soft information from MAP decoder to estimate the carrier phase and compensate it for the next iteration. Various phase models are taken into consideration. We can always achieve satisfactory error performance.