以外來資訊轉換圖設計調變器映射規則於位元交錯調變碼之迭代解碼系統

Abstract

本論文利用外來資訊轉換圖 (Extrinsic Information Transfer Chart，EXIT- Chart) 聯合設計調變器映射規則 (Labeling) 與外部編碼器以增進位元交錯調變碼之迭代解碼系統 (Bit-Interleaved Coded Modulation with Iterative Decoding，BICM-ID) 的性能。針對均勻的調變星座，我們提出一個有系統的調變星座映射規則的設計方法以得到一組具有好的外來資訊轉換圖特性的映射規則；對每一種外部編碼器皆可以從中選擇出一個最理想的映射規則，使解調器和解碼器的轉換特性曲線能相交在外來資訊轉換圖上越遠的位置而且讓區線間的通道能夠打開以達到理想的錯誤率。我們還擴展此映射規則設計方法到多維度的調變星座上，多維度調變星座將一群位元映射到一組以一維度星座調變的符號使系統的設計上具有更高的彈性與潛在性能的提升。經由模擬結果證實我們的設計比傳統的設計提供了卓越的訊雜比增益

In this thesis, constellation labeling is jointly designed with the outer code by using an EXIT-chart based analysis to improve the performance of bit-interleaved coded modulation with iterative decoding (BICM-ID). A systematic design method is proposed to obtain a set of labelings with good EXIT-chart characteristics for the regular one-dimensional (complex) modulation. Given an outer code, the best matched labeling can be employed to improve the BER performance. Furthermore, the method is extended to the multi-dimensional modulation case, where a group of bits are mapped to a vector of one-dimensional complex symbols. This general mapping strategy allows for more flexibility and potential performance improvements. Verified by the simulation results, our design provides a significant SNR gain over the conventional ones.