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研究生: 顏健安
Yen-Chien An
論文名稱: 適用於OFDM系統下之通道模擬器研究與實現
Implementation of Configurable Mobile Multipath FadingChannel Emulator for OFDM System
指導教授: 陳逸民
Yih-Min Chen
口試委員:
學位類別: 碩士
Master
系所名稱: 資訊電機學院 - 通訊工程學系
Department of Communication Engineering
畢業學年度: 97
語文別: 中文
論文頁數: 98
中文關鍵詞: Jakes 模型FPGA發展板Rayleigh衰減通道通道模擬器OFDM發射器循環字首
外文關鍵詞: Rayleigh fading channel, Channel Emlator, OFDM transmitter, Cyclic prefix, FPGA development board, Jakes model
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  • 本論文最主要的目的是在如何實現建構出具備簡便操作、高彈性的模擬參數範圍、通道效應逼真、成本降低等特點之通道模擬器,並利用Veilog硬體描述語言,實現在FPGA發展板。通道衰減模擬器為通訊系統在設計與認證上,所不可或缺的一項測試工具,其中Jakes 模型由於具備架構簡單、符合電波散射理論並且能夠呈現都卜勒偏移頻率效應等優點,而廣泛的被應用於Rayleigh 衰減通道的模擬。
    在OFDM發射器,提出了一可行的OFDM調變方式的FPGA實現方法,並介紹IFFT與循環字首(Cyclic prefix)加入的具體電路。


    This paper principal objective is discuess how can channel simulator include easier operation, more flexible parameter choices, more realistic channel effect, and lower cost, and use the Verilog Hardware Description Language to implement a multipath fading channel emulator on FPGA development board. Fading channel simulator is one of the most important testing equipments for the design and identification of communication systems. Jake’s model is widely used on the simulation of a Rayleigh fading channel.
    In the OFDM Transmitter, an OFDM modulation structure based on FPGA is Presented.The circuits of IFFT and cyclic prefix joining are also present.

    摘要 ................................................................................................................................ i 英文摘要 ........................................................................................................................ ii 誌 謝 ........................................................................................................................... iii 目 錄 ........................................................................................................................... iv 圖 目 錄 ................................................................................................................... vi 表 目 錄 ..................................................................................................................... x 第一章 緒論 ................................................................................................................. 1 1.1 研究動機與背景 ............................................................................................... 1 1.2 章節提要 ........................................................................................................... 2 第二章 無線移動通道統計特性描述 ......................................................................... 3 2.1 無線移動通道簡介 ........................................................................................... 3 2.2 小尺度傳輸模型(Small Scale Propagation Model) .......................................... 5 2.2.1 多重路徑傳輸效應(Multipath Propagation Effect) ............................... 6 2.2.2 都卜勒效應 (Doppler Effect) .............................................................. 11 2.3 多重路徑衰減通道的模型 ............................................................................. 16 2.3.1 多重路徑衰減通道模型架構圖 ........................................................... 17 2.3.2 Rayleigh 衰減分佈與Ricean 衰減分佈 ............................................. 17 2.3.3 高斯白雜訊通道(Additive White Gaussian Noise Channel;AWGN) ... 18 第三章 歐規數位電視地面廣播系統簡介 ............................................................... 20 3.1 DVB-T 系統規格與參數 ................................................................................ 20 3.2 通道模型簡介 (Channel Model) ................................................................... 24 3.2.1 動態通道模型 (Time-varying Channel Model) .................................. 25 第四章 時變通道衰減模擬器對DVB-T 系統效能的影響 ..................................... 29 4.1 通道估測與等化 (Channel Estimation and Equalization) ............................. 31 v 4.1.1 最小平方法通道估測 (Least Square Channel Estimation) ................ 33 4.1.2 通道響應內插 (Interpolation of Channel Response) ......................................... 34 4.2 通道模擬 .......................................................................................................... 35 4.3 系統效能分析 .................................................................................................. 46 第五章 FPGA 實現多路徑衰減通道模擬器 ........................................................... 58 5.1 系統驗證平台介紹 .......................................................................................... 59 5.2 單緩衝記憶體機制 ......................................................................................... 60 5.3 通道模擬器(Channel Emulator) ...................................................................... 63 5.3.1 座標旋轉計算器(CORDIC) ................................................................. 64 5.3.2 Fading Generator(F.G) ........................................................................... 67 5.3.3 Mutipath Delay Generator (M.D.G) ...................................................... 69 5.3.4 Interpoaltor Generator (I.G)................................................................... 71 5.3.5 Complex multiplication(C.M) ............................................................... 72 5.4 AWGN 雜訊產生器 ........................................................................................ 74 第六章 結論與未來發展 ............................................................................................ 83 參考文獻 ....................................................................................................................... 84

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