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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/9345

    Title: 可適性正交多工調變系統;Adaptive orthogonally multiplexed modulation systems
    Authors: 林維崙;Wei-Lun Lin
    Contributors: 電機工程研究所
    Keywords: 可適性調變;正交多工調變;orthogonally multiplexed modulation;Adaptive modulation
    Date: 2008-05-08
    Issue Date: 2009-09-22 11:45:50 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本論文為可適性調變技術採用了未編碼的正交多工調變信號於 瑞雷通道的研究。論文中提出了一個調變選擇法則,以便於正交多工 調變家族中挑選最適合通道且最具頻寬效益的調變。相較於傳統系 統,同調與差分同調的定功率可適性正交多工調變系統都展現出優異 的平均頻譜效益。此外,本論文所提之可適性正交多工調變系統搭載 了調變對應器與解對應器後,只需花費些微的運算量,便可以實現於 傳統的正交分頻多工系統之上。更進一步,本論文也探討了可適性正 交多工調變結合了前導信號調變在平緩衰落與時擇通道中的系統。其 中,兩種前導信號的信號格式的頻譜性能也在論文中加以分析。基於 此系統,本論文也分析了通道估測錯誤對於在結合了前導信號調變的 可適性正交多工調變系統所造成的影響,並提供估測錯誤與系統頻譜 效能之間的結果分析。 Adaptive transmission technique adopting uncoded orthogonally multiplexed modulation (OMM) signals is studied for flat Rayleigh fading channel. A modulation selection rule is proposed to choose spectrally efficient OMM signals in accordance with channel status. Both coherent and differentially coherent constant-power adaptive OMM (AOMM) systems are shown to significantly outperform the conventional constant-power adaptive modulation systems in average spectral efficiency. Additionally, the considered adaptive OMM systems with modulation mappers and demapping algorithms can be directly implemented over orthogonal frequency division multplexing based system structure with marginally additional implementation complexity. Furthermore, the pilot-symbol-assisted (PSA) AOMM systems are studied under frequency flatfaded channel with time selectivity. The spectral performance of two pilot patterns are analyzed. The impact over spectral performance caused by the estimation error is also examined for the PSA-AOMM systems.
    Appears in Collections:[電機工程研究所] 博碩士論文

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