臺灣博碩士論文加值系統

最大化相似資料序列估測已經是著名的接收器偵測資料序列的技術，部份原因是對衰退通道之容忍度高與抗干擾之能力，以及有較佳的位元錯誤率表現。
本篇論文以著名的期望值最大化(Expected-maximization簡稱EM)演算法進行資料序列與碼際干擾(intersymbol interference簡稱ISI)通道係數的聯合估測。
這裡我們使用狀態縮減(Reduced state)技術的方法與研究期望值最大化(EM)演算法在碼際干擾通道下，接收器編碼資料序列的估測性能。本論文以基於EM演算法及狀態縮減技術之編碼資料序列及通道聯合估測方法模擬分析位元錯誤率的表現。所提出之方法會較一般EM演算法在ISI通道上的聯合通道與資料序列估測可以有較好之性能表現。

MLSE (maximum likelihood sequence estimation) has been a well-known technique to estimate transmitted sequence for receiver; some reasons are that it has good performance of higher tolerance and anti-disturbance for fading channels, and it can achieve lower BER (bit-error-rates).
The paper presents a well-known method for using EM (expected-maximum) algorithm to precede a joint estimation of both transmitted sequence and ISI (intersymbol interference) channel coefficients problem.
Here we use technique with reduced state method and study EM algorithm performance of coded data sequence estimation over ISI channels. The paper that is based on EM algorithm and technique with reduced state method jointly estimates both coded data sequence and ISI channels, and we simulate performance of BER. The method we proposed performs better than joint sequence / channel estimation based on general EM algorithm over ISI channels.

章節目錄
中文摘要……………………………………………………………………0-1
英文摘要……………………………………………………………………0-2
第一章 簡介…………………………………………………………… 1-1
1.1文獻探討……………………………………………………………… 1-1
1.2 研究動機………………………………………………………………1-2
1.3 章節描述………………………………………………………………1-2
第二章 碼際干擾通道介紹…………………………………………… 2-1
2.1 記憶通道(成因、干擾、固定高斯) ……………………………… 2-1
2.1.1線性等化器原理…………………………………………………… 2-3
2.1.2等化器問題描述…………………………………………………… 2-6
2.2資料序列估測的方法………………………………………………… 2-7
第三章 Viterbi演算法…………………………………………………3-1
3.1迴旋編碼器和格子圖………………………………………………… 3-1
3.2迴旋碼的解碼………………………………………………………… 3-2
3.3 Viterbi解碼………………………………………………………… 3-5
第四章 期望-最大化演算法介紹……………………………………4-1
4.1離散通訊系統接收器模型…………………………………………… 4-1
4.2最大似然序列估測與期望-最大化演算法步驟………………………4-2
4.2.1等效通道狀態轉移圖……………………………………………… 4-2
4.2.2 期望-最大化演算法步驟………………………………………… 4-3
4.3在固定常數碼際干擾通道係數下估測資料序列…………………… 4-5
第五章碼際干擾通道通道編碼資料序列之估測…………………………5-1
5.1編碼資料序列估測之處理方法流程與期望-最大化演算法改 …… 5-1
5.1.1 期望-最大化演算法及迴旋碼解碼器………… …………………5-1
5.1.2具決策迴授路徑之期望-最大化演算法……………………………5-2
5.2系統模擬條件………………………………………………………… 5-2
5.3系統模擬分析………………………………………………………… 5-2
5.4 碼際干擾通道編碼資料序列估測之結論……………………………5-4
第六章 狀態減少技術之編碼資料序列估測-基於期望-最大化演算法.………………………………………………………………………………6-1
6.1如何減少Viterbi演算法的狀態數目…………………………………6-1
6.2 Viterbi演算法中通道狀態與迴旋碼解碼狀態之合併…………… 6-2
6.3狀態減少技術基於期望-最大化演算法………………………………6-3
6.4系統模擬分析與結論………………………………………………… 6-6
第七章 論文結果與討論…………………………………………………7-1
參考文獻……………………………………………………………………7-2
圖表目錄
第二章
圖2.1線性橫向濾波器…………………………………………………… 2-9
圖2.2等化器之系統方塊圖……………………………………………… 2-9
圖2.3等化器之系統方塊圖簡圖………………………………………… 2-10
圖2.4 (圖2.3)各點的離散訊號圖……………………………………… 2-10
第三章
圖3.1 (2,1,2)迴旋碼編碼器電路……………………………………… 3-7
圖3.2 狀態圖(圖中數字表示 )………………………………………… 3-7
圖3.3 格子圖………………………………………………………………3-7
圖3.4 Viterbi演算法示意圖…………………………………………… 3-8
圖3.5(a) Viterbi解碼的基本步驟………………………………………3-8
圖3.5(b) Viterbi解碼的基本步驟………………………………………3-9
圖3.5(c) Viterbi解碼的基本步驟………………………………………3-9
圖3.5(d) Viterbi解碼的基本步驟………………………………………3-9
圖3.5(e) Viterbi解碼的基本步驟………………………………………3-10
第四章
圖4.1 三條路徑無線通道模型方塊圖……………………………………4-7
圖4.2 等效通道狀態轉移圖………………………………………………4-7
圖4.3等效通道狀態轉移圖之格子圖表示……………………………… 4-8
圖4.4 EM演算法估測流程圖………………………………………………4-8
第五章
圖5.1 ISI通道編碼資料序列估測流程方塊圖………………………… 5-5
圖5.2 編碼資料序列估測之EM演算法流程圖……………………………5-5
圖5.3 輸出資料序列決策迴授之估測流程圖……………………………5-6
圖5.4 本論文所提決策迴授之EM演算法流程圖…………………………5-6
圖5.5 不同ISI通道脈衝響應EM演算法與Hard Decision (sign) 方法之BER比較圖………………………………………………………………… 5-7
圖5.6 固定的ISI通道、不同SNR條件下，傳輸資料長度對於各個演算法之比較圖………………………………………………………………………5-7
圖5.7 經過編碼與未經編碼的EM演算法與Hard Decision (sign)方法比較圖……………………………………………………………………………5-8
表5.1 g值估測之MSE(mean square error)比較……………… ………5-8
第六章
圖6.1 經過濾波的迴旋碼資料序列與以EM演算法偵測之系統方塊圖…6-9
圖6.2 迴旋碼狀態與通道狀態示意圖……………………………………6-9
表6.1 超級狀態示意表……………………………………………………6-9
表6.2 超級狀態轉移表……………………………………………………6-10
表6.3 超級狀態轉移情形與通道輸出表…………………………………6-11
圖6.3 超級狀態11之格子圖說明…………………………………………6-12
圖6.4 超級狀態20之格子圖說明…………………………………………6-12
圖6.5 超級狀態29之格子圖說明…………………………………………6-13
圖6.6 不同演算法對於SNR資料序列估測的BER表現圖(較輕ISI影響)6-13
圖6.7 SNR固定6dB時，不同演算法對於INR資料序列估測的BER表現圖
(較輕ISI影響)…………………………………………………………… 6-14
圖6.8 不同演算法對於SNR資料序列估測的BER表現圖(較大ISI影響 6-14
圖6.9 SNR固定6dB時，不同演算法對於INR資料序列估測的BER表現圖
(較大ISI影響)…………………………………………………………… 6-15
圖6.10 傳輸資料序列位元長度對於演算法的 BER比較圖…………… 6-15
表6.4 狀態數目比較表……………….……………… …………………6-16

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