臺灣博碩士論文加值系統

多輸入多輸出(Multiple-Input Multiple-Output, MIMO)系統能在劇烈變動的通訊環境，利用空間性分集特性改善接收品質，空間性分集的作法主要是時空碼技術，然而在超高速移動通道中，因受到都卜勒效應影響，通道狀態快速變化，令時空碼的基本假設無法成立，故我們研究的目的即在改進時空碼架構，解決時空碼無法在超高速移動下使用的問題，因高速鐵路系統具有所有超高速移動環境的特性，故研究場景設定在高速鐵路環境下。首先探討時空碼失效的原因，接者介紹DDST演算法，研究其針對高速移動設計的觀念，並將DDST作為效能比較標準，以利於觀察改進架構的改善程度。之後利用高鐵環境存在直視波路徑，以及固定路徑資訊兩項特性，設計改進架構，最後利用智慧型天線技術，讓時空碼效能突破自然因素的限制，得以在高速鐵路環境中，幫助系統克服不良通訊衰變。

第一章 緒論......................................................1
1.1 前言........................................................1
1.2 研究動機與目的..............................................3
1.3 通道模擬參數設定............................................3
1.3.1 都卜勒效應參數........................................3
1.3.2 多路徑衰減參數........................................5
1.3.3 Rayleigh衰減分佈及通道模型............................6
1.3.4 Ricean衰減分佈及通道模型.............................10
1.3.5 無線連接架構.........................................12
1.3.6 高速鐵路環境.........................................13
1.4 多輸入多輸出系統...........................................14
1.5 論文架構...................................................19

第二章 MIMO分集特性於超高速環境下的效能分析.............21
2.1 研究動機與目的.............................................21
2.2 分集效應...................................................22
2.2.1 分集種類.............................................22
2.2.2 分集階級.............................................22
2.3 接收端分集.................................................23
2.4 傳輸端分集.................................................25
2.4.1 時空籬柵碼..........................................25
2.4.2 正交性時空方塊碼.....................................27
2.4.3 差分性時空方塊碼 ....................................30
2.5 電腦模擬結果...............................................33
2.5.1 分集階級之模擬及討論.................................33
2.5.2 移動環境之模擬及討論.................................35
2.5.3 增加符元速率以符合假設...............................37
2.6 結論.......................................................38

第三章 時空碼架構於超高速移動環境下演算法之效能改進......39
3.1 研究動機與目的.............................................39
3.2 雙差分時空碼...............................................40
3.2.1 DDST演算法原理及架構介紹............................40
3.2.2 DDST在群集通道模型中的效能討論......................47
3.3 運用固定通道已知資訊.......................................50
3.3.1 接收訊號—都卜勒頻率補償.............................51
3.3.2 通道估測—都卜勒相位補償.............................53
3.4 敏感度討論.................................................59
3.4.1 角度敏感度...........................................60
3.4.2 都卜勒偏移估測誤差敏感度.............................61
3.5 結論.......................................................62

第四章 時空碼之改進架構效能瓶頸討論.........................65
4.1 研究動機及目的.............................................65
4.2 改進作法的效能瓶頸.........................................66
4.2.1 不完美直視波通道模型一...............................67
4.2.2 不完美直視波通道模型二...............................69
4.2.3 造成效能瓶頸的原因...................................71
4.3 利用智慧型天線突破瓶頸.....................................71
4.4 結論.......................................................78

第五章 全文總結與未來展望.....................................79
5.1 全文總結...................................................79
5.2 可行的發展方向.............................................83

參考文獻.......................................................85

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