在建立LDPC校驗矩陣時，通常會使用各種不同的演算法
建立相應且符合要求的校驗矩陣，其中EXIT chart就是一種
十分有效的方法，其中又分為一般型態，用於尋找維分布
數值，以及P-EXIT chart，用於搜尋特定結構的Protograph
based LDPC code 之基礎矩陣，這兩種方法皆可以獨立使用，
而在這之後，也衍生出了用於計算解調器互消息值的EXIT
chart，用於計算高階調變以及迭代式接收器(IDD)搭配不同維
分布的收斂值。而在本篇論文中，則是延伸了此一概念，除
了計算出適用於特定調變及迭代式接收器的維分布外，加入
了P-EXIT chart，並討論對於不同調變矩陣結構的影響，不僅
能提升建碼效率，同時也能提升效能並降低位元錯誤率。而
另一方面，即使提出了匹配特定調變以及迭代式接收器的建碼
演算法及其基礎矩陣，並提升了效能，也無法避面該矩陣出現
錯誤平層，換句話說，在得到較佳的解碼臨限值時，也同時有
著出現錯誤平層的風險，對錯誤更正碼而言錯誤平層的出現是
無法預期的，而在本論文中也會針對如何降低或是消除錯誤平
層一併討論，提出了另一個稱為位元可靠度ACE的演算法，主
要用於降低或是消除錯誤平層。本論文中將會討論三種不同
的調變，而各調變中又會有其不同的映射規則，搭配所提出的
演算法將可以建立專屬的基礎矩陣，不僅能維持效能，甚至能
有所提升，同時提升建碼效率。

In this thesis, the design of LDPC coded modulation is considered, where
conventional density evolution and importance sampling cannot be used.
Since non-zero codeword cannot be used for asymmetric channel, we introduce
a method to modify importance sampling. In addition, EXIT (extrinsic
information transfer) chart can't be applied to quantized PAM (pulseamplitude
modulation) since the Gaussian approximation for the soft values
may loss its accuracy. Therefore, density evolution is modied for LDPC
coded modulation. Although the use of gray labeling can achieve low threshold,
the error
oor performance can be enhanced using the proposed labeling.
The proposed labeling is searched for LDPC coded modulation, where the
labeling criterion is considered to lower error
oor. These techniques are applied
to LDPC coded MLC
ash memory systems which is an LDPC coded
modulation.

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I
第一章簡介. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
第二章基本介紹. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
第三章密度演化運用於LDPC編碼調變. . . . . . . . . . . . . . . . . . . . 15
第四章EXIT chart 應用於LDPC編碼調變. . . . . . . . . . . . . . . . .25
第五章位元可靠度ACE演算法. . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
第六章整合及模擬結果. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
第七章結論. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
參考文獻. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
i

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