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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/8100

    Title: 低密度同位元檢查碼在數位資料儲存系統之研究;Study of Low-Density Parity-Check Codes on Digital Storage Systems
    Authors: 彭博詮;Po-Chuan Peng
    Contributors: 通訊工程研究所
    Keywords: 光記錄通道;部份反應/最佳估算;最大事後機率偵測器;低密度同位元檢查碼;LDPC;DVD;PRML;Turbo Equalizer;BCJR
    Date: 2005-06-27
    Issue Date: 2009-09-22 11:18:07 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 為提高數位資料儲存系統之記錄密度和資料傳輸速率,近期文獻所提出接收端架構為渦輪等化器(Turbo Equalizer),藉由內外碼的訊息傳遞達到優異的效能,內碼部分為通道偵測部分,資料儲存系統常用比較先進之訊號處理技術,利用等化器將讀回信號等化成部份反應信號以降低雜訊接著再利用最佳估算偵測法則即BCJR法則(BCJR Algorithm)將信號還原為數位資料,此種訊號處理技術稱為部份反應/最佳估算(Partial Response and Maximum Likelihood Detection, PRML)通道技術,可將數位儲存通道視作碼率為1之迴旋碼,外部碼則為PRML光學通道外部加入錯誤更正碼,使用了渦輪碼為外碼,此架構稱為BCJR偵測器/渦輪碼渦輪等化器,該類系統需要用到三個串連式(Serial)的最大事後機率演算法模組(內部PRML讀回訊號偵測利用一個BCJR模組,外部渦輪碼解碼器,由兩個平行系統迴旋碼組成,需要利用兩個BCJR模組),雖然有很好的錯誤更正效能,但解碼延遲過長,在即時(Real Time)系統上無法應用。 本論文改善此缺點,使內部偵測演算法由原先耗時的串連BCJR演算法改變為快速的平行(Parallel)架構,加入視窗的概念,將演算法改為Window-BCJR,並加入TMTR調變碼(TMTR Modulated Code),使訊號更適合在媒體上記錄,並於外部碼採用擁有平行解碼架構之低密度同位元檢查碼(LDPC),形成效能優異且解碼延遲小之全平行渦輪等化器。 The advanced signal processing technique referred to as the partial response and maximal likelihood (PRML) channel is usually employed in the digital recording systems to increase the recording density and/or data transmission rate. In addition, a turbo equalization scheme was investigated in which a turbo code consisted of two parallel systematic convolutional codes was employed as an outer code and the BCJR detection of the TMTR-coded partial response channel was employed as an inner code.But this kind of Turbo Equalizer is too slow. We proposed a new turbo equalization scheme the window-BCJR detection for the TMTR-coded partial response channel can be processed in a parallel way and the decoding delay could be ignored, the decoding of the outer code is the low-density parity-check (LDPC) codes. The recent research for the turbo decoding has been focused on the LDPC codes due to that a parallel processing architecture for decoding of the LDPC codes is possible, and this leads to a short decoding delay.We instead of using turbo codes the low density parity check (LDPC) codes are employed as the outer code in the turbo equalization scheme. The turbo decoding for the TMTR-coded partial response channel with the LDPC codes will be investigated.
    Appears in Collections:[通訊工程研究所] 博碩士論文

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