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研究生:余之尹
研究生(外文):Yu,Chihyin
論文名稱:渦輪編碼之多使用者多輸入多輸出系統中之Tomlinson-Harashima預編碼研究
論文名稱(外文):Tomlinson-Harashima Precoding for Multiuser MIMO with Turbo codes
指導教授:邱茂清邱茂清引用關係沈文和
指導教授(外文):Chiu,MaochingSheen,Wernho
口試委員:陳喬恩劉維正邱茂清沈文和
口試委員(外文):Chen,ChiaoenLiu,WeichengChiu,MaochingSheen,Wernho
口試日期:2011-07-29
學位類別:碩士
校院名稱:國立中正大學
系所名稱:通訊工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2011
畢業學年度:99
語文別:中文
論文頁數:56
中文關鍵詞:多輸入多輸出預編碼渦輪碼對數似然值
外文關鍵詞:MIMOprecodingTurbo codeslog-likelihood ratio
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  • 被引用被引用:0
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  • 下載下載:4
  • 收藏至我的研究室書目清單書目收藏:0
在多天線輸入輸出(MIMO)系統中,當發射端完全知道通道狀態資訊時,我們可以預先在傳送端處理信號藉以消除多使用者之間彼此的干擾。在這本論文裡,我們將使用預編碼的技術將MIMO通道分解為數個平行通道。而在預編碼技術中,湯姆林森-賀洛希瑪預編碼(THP)為較有名的方式,此方法原先是設計在符號間干擾的通道,之後才衍生使用在MIMO系統中。
另外在一般討論THP的論文中,針對THP再搭配上錯誤更正碼的研究並不多,所以我們在論文中也將討論THP與渦輪碼結合之後的系統效能。
我們在研究THP與渦輪碼結合的過程中發現傳統的THP作法在與渦輪碼結合的過程中會因為模除器的關係而造成模除邊界對數似然值(LLR)的計算呈現不連續的現象,間接造成渦輪碼解碼可能的錯誤,於是我們提出了修正對數似然值的算法包括了使用等機率和已知機率的方法加以修正對數似然值外,也比較了其他論文所提出的方法。除此之外,我們發現傳統THP固定接收端使用者排序,會造成使用者間效能不一,為了達到公平性,我們將使用者順序平均地輪流以達到使用者間效能的公平性。
最後透過電腦模擬,我們發現THP與渦輪碼結合並利用修正對數似然值的方法在效能上會比傳統THP搭配渦輪碼的作法還要好。另外再搭配上使用者順序平均輪流的方式也有明顯的效能增益。

In multiple-input multiple-output (MIMO) systems, when the transmitter perfectly knows the channel state information, transmitted signal can be pre-processed to eliminate the interference between users. In this paper, we use the precoding techniques to decompose the MIMO channel into several parallel channels. Among all precoding techniques, Tomlinson-Harashima precoding (THP) is more famous and affective than the others. THP was originally designed for intersymbol interference (ISI) channels and was later extended to MIMO systems.
In general discussion about THP, there are few researches which focus on combining THP with error correction codes. In this thesis, we will evaluate the system performance on combining THP with Turbo codes in the thesis.
In combining THP with Turbo codes, we found out that there is a log-likelihood ratio (LLR) discontinuous computation problem caused by modulo operation at the receiver, which makes inaccurate LLR estimation and results in degradation of decoding. Therefore, we propose several methods to revise the LLR by using probability mass function (pmf) of the extended signal constellation. In addition, we find that if user order is fixed as in the conventional THP, it causes unfairness of performance between users. Therefore, we rotate users' order in a round robin fashion to achieve the fairness between users.
Finally, simulation results show that with the modified LLR, the performance can be improved significantly. In addition to this, rotating users in a round robin fashion also has performance improvement than that of fixed order one.

誌謝辭 i
中文摘要 ii
英文摘要 iii
目錄 iv
圖目錄 vi
表目錄 viii
第一章 簡介 1
1.1 動機 1
1.2 論文架構 2
第二章 MIMO多天線輸入輸出技術 3
2.1 MIMO多天線輸入輸出技術 3
2.1.1 MIMO系統模型 5
2.2 MIMO偵測器 7
2.2.1 強制零 (ZF) 8
2.2.2 最小均方誤差 (MMSE) 9
2.2.3 最大相似 (ML) 9
第三章 Tomlinson-Harashima預編碼系統的基本原理 10
3.1強制零(ZF)法則之Tomlinson-Harashima預編碼系統模型 10
第四章 渦輪碼基本原理 17
4.1 遞迴系統迴旋碼 17
4.2 渦輪碼編碼基本架構 20
4.2.1 3GPP-LTE渦輪碼編碼架構 22
4.2.2 3GPP-LTE渦輪碼交錯器架構 23
4.3 渦輪碼解碼基本原理 24
4.3.1 機率域BCJR解碼演算法 26
4.3.2 對數域BCJR解碼演算法 30
4.3.2 平行串接迴旋碼迭代解碼 33
第五章 擴展軟式反映射器 37
5.1 傳統模除反映射器 37
5.2 等機率之擴展軟式反映射器 40
5.3 已知機率之擴展軟式反映射器 43
5.4 已知星座點擴展之軟式反映射器 46
5.5 部分擴散之擴展軟式反映射器 47
5.6 使用者平均輪流之擴展軟式反映射器 48
第六章 模擬與分析 49
6.1 模擬結果 49
6.2 結論 54
參考文獻 55

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