利用外來資訊轉換圖設計位元交錯調變碼之迭代解碼系統

Abstract

外來資訊轉換圖是一個在迭代解碼系統中很好的分析解碼收斂行為的工具，在位元交錯調變碼的解碼系統中，位元對應的設計對於提升系統效能是非常重要的，藉由不同的平均位元差異數來改變訊號偵測器轉換曲線的斜率，因而從中選出一個最適合外部碼的位元對應方式。我們說明了這樣的作法的確可以大幅的改善系統效能。在這篇論文中，我們還提出了利用外來資訊轉換圖來設計柵欄移除(trellis-pruned)迴旋碼和穿刺(punctured)迴旋碼在位元交錯調變碼解碼系統中來達到不同的系統需求。

In the bit-interleaved coded modulation systems with iterative decoding (BICM-ID), a good labeling (bit mapping) is one of the key factors that dictate the system performance. In this thesis, Extrinsic Information Transfer (EXIT) chart, a popular tool to analyze the convergence behavior of an iterative decoding system, is employed for the labeling design. By changing the slopes of the detector transfer curves and selecting the most suitable labeling for the outer code, we show that the system performance can be significantly improved. In addition, EXIT chart is employed to design good trellis-pruned and punctured convolutional codes in BICM-ID systems to provide different levels of performance and code rate trade off.