利用外來資訊轉換圖設計第一類混合自動重傳之位元對應在位元交錯調變碼之迭代解碼系統

Abstract

在現代的無線通訊系統中，位元交錯調變碼被利用來克服瑞雷（Rayleigh）衰減通道，而混和自動重傳機制則可用來提升系統的吞吐量，兩者均是下一世代通訊系統所採用的重要技術。在本論文中，我們針對第一類混和自動重傳機制（Type-I Hybrid Auto-retransmission Request）在位元交錯調變碼之迭代解碼（BICM-ID）系統架構下提出一個位元對應（Labeling）及解碼器（Decoder）設計的方法。利用外來資訊轉換圖（EXIT Chart）這個強大的工具，我們提出一個可根據外部錯誤更正碼來設計重傳時所用位元對應的演算法。根據所找出的位元對應，我們利用鏈路調節（Link adaptation）的概念在不同的通道訊雜比（SNR）下使用不同的位元對應來的到較佳的品質。最後，我們根據3GPP的渦輪碼（Turbo Code）提出一個新穎的解碼器設計，結合適當的位元對應具有優於現今3GPP規範裡設計的品質

In modern wireless communication systems, bit-interleaved coded modulation（BICM）is used to overcome the Rayleigh fading channel, and the HARQ (Hybrid Auto-retransmission Request) technique is used to improve the system throughput. In this thesis, we propose new labeling and decoder designs for Type-I HARQ for BICM-ID systems. Based on the EXIT (Extrinsic Information Transfer) chart, we develop as algorithm to search for good labeling for retransmission that well matches with the outer cod. The concept of link adaptation is realized by using different labeling at different SNR (signal to noise ratio) to achieve a better performance. Finally, a novel decoding strategy is proposed along with the proposed labeling design for turbo code in 3GPP specification. It is shown that the new design outperforms the existing one.