張進福臺灣大學：電信工程學研究所鄭旭城Cheng, Hsiu-ChengHsiu-ChengCheng2007-11-272018-07-052007-11-272018-07-052007http://ntur.lib.ntu.edu.tw//handle/246246/58722隨著無線通訊與高速鐵路的迅速興起，在高鐵環境提供高傳輸速率的需求也跟著增加。OFDM技術由於對符碼間干擾有較高的抵抗力而能達到較高的資料速率，近來獲得廣泛的研究，包括IEEE 802.11與IEEE 802.16等標準皆將其納入最新的規範當中。而在不同的都卜勒頻率之下，利用導航符號協助之通道估測法的準確度將與導航符號的排列方式息息相關。本論文將首先描述導航符號排列方式對不同都卜勒頻率的影響，並透過模擬顯示802.16系統參數在高速移動下的效能表現。接著根據取樣定理與通道參數，我們設計一種新的導航符號排列方式並與傳統的802.16訊框格式比較。最後，我們利用鐵路環境可預測的特性試著增加系統效能。With the rapid growth of wireless communications and high speed rail, the need for high speed data transmission in high speed train environment is increased. Orthogonal Frequency Division Multiplexing (OFDM) is recently becoming very popular for achieving high data rates due to its resistance to ISI. OFDM has also been chosen as the transmission method for many standards, such as the IEEE 802.11 and 802.16. The accuracy of pilot-aided channel estimation at a desired Doppler frequency is highly dependent on how the pilots are arranged. In this paper, we describe the effect of Doppler frequency on different pilot arrangements in wireless OFDM systems and simulate the performance using the parameters of the IEEE 802.16 standard in high mobility environment. According to sampling theorem and channel parameters, we propose a new pilot insertion scheme and compare it with conventional 802.16 frame format. In the end, we use characterization of rail environment to improve system performance.誌謝........................................................i 中文摘要..................................................iii 英文摘要....................................................v 第一章 緒論................................................1 1.1前言.............................................1 1.2研究背景.........................................2 1.3鐵路環境無線連結的方式...........................4 1.3.1單鏈架構...............................4 1.3.2雙鏈架構...............................6 1.4基礎建設規劃.....................................8 1.4.1通訊環境...............................8 1.4.2遮蔽效應...............................9 1.4.3都卜勒效應............................................10 1.4.4細胞規劃..............................11 1.5總結....................................................13 第二章 高速移動環境對OFDM系統的影響.......................17 2.1 前言...................................................17 2.2 通道模型.......................................17 2.3 通道參數.......................................22 2.3.1 時間擴散與同調頻寬...................22 2.3.2 都卜勒效應與同調時間.................23 2.4 正交分頻多工系統簡介...........................23 2.5 OFDM系統的次載波間干擾.........................28 2.6 不同pilot排列方式對效能的影響..................30 2.7 結論...........................................37 第三章 高速鐵路環境下802.16d/e頁框格式效能之分析...........39 3.1 前言...........................................39 3.2 802.16簡介.....................................40 3.3 IEEE 802.16d/e實體層標準介紹...................41 3.4 802.16d/e WirelessMAN-OFDM正交分頻多工實體層簡介.........................................................42 3.5 IEEE 802.16d/e訊框格式在高速移動下之效能.......47 3.6 提出的改善方法.................................48 3.7 相位調整.......................................53 3.8 結論...........................................57 第四章 高速鐵路環境的可預測性..............................61 4.1 前言...................................................61 4.2 都卜勒頻率的可預測性...........................61 4.3 相位旋轉的可預測性.............................65 4.4 通道完全已知...................................66 4.5 結論...........................................67 第五章 全文總結與未來展望..................................69 5.1 總結...................................................69 5.2 未來的研究方向.................................70 參考文獻...................................................73en-US高速鐵路OFDM802.16導航符號排列方式鐵路環境特性high speed railpilot arrangementcharacterization of rail environmentthesis