基於額外資訊相關性的合併訊源通道編碼機制

Abstract

在數位多媒體通訊系統裡，合併訊源通道編碼演算法可有效提升系統效能的強健性。本論文將針對位元及索引層級的疊代訊源通道解碼機制，探討系統傳送端兩項關鍵元件的設計。索引指定，先觀察疊代解碼過程中額外資訊相關性的實質變化，再配合二位元置換演算法以設計最佳的索引指定。至於交錯器的設計，我們從接收端的角度，提出適用於疊代訊源通道解碼的交錯器。最後經由附加性白高斯雜訊通道的系統模擬，驗證我們提出的索引指定與交錯器，有效提升了疊代解碼的效益與整體系統的強健性。

In digital multimedia communication , iterative source-channel decoding(ISCD) has been shown effective for error robustness by exploiting both the source residual redundancy and the channel-code redundancy . This thesis investigates the encode design for use in conjunction with bit-level as well as index-level ISCD . Firstly , we compare different index assignment schemes in terms of the correlation of extrinsic information resulting form the ISCD process .Also proposed is a correlation-based index assignment scheme . Secondly , we focus on the interleaver design based on the performance of iterative decoding . Simulation results indicate that the combined use of correlation-based index assignment and interleaver can improve the error robustness for AWGN channel.