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    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/8912


    題名: 衰弱通道下差調及同調相位鍵移調變的天線分集轉換;Antenna Diversity Transforms for Differentially Coherent and Coherent PSK Modulations over Fading Channels
    作者: 黃富鑫;Fuh-Hsin Hwang
    貢獻者: 電機工程研究所
    關鍵詞: 衰弱通道;相位鍵移調變;天線分集;分集轉換;fading channels;PSK modulation;antenna diversity;diversity transform
    日期: 2003-09-27
    上傳時間: 2009-09-22 11:37:32 (UTC+8)
    出版者: 國立中央大學圖書館
    摘要: 本論文主要探討傳送天線分集架構的三種實現方法,這些方法適用於非頻擇性的衰弱通道,所考慮的天線分集轉換不需要估測通道狀態。在第一種方法中,發射端由一個我們提出的非線性轉換器、NT 分支的差異相位鍵移(N-DPSK)調變器、傳送天線與正交波形修整器所構成。針對N-DPSK調變,我們同時考慮不具多餘符元及具多餘符元的非線性轉換。在第二種方法中,我們使用決策回饋差異相位偵測(DF-DD)來取代第一種方法中傳統的差異相位偵測(2DD),以改善前者在快速衰弱通道下錯誤性能的衰退。在第三種方法,我們重新探討前面所提出的分集架構,改用同調的相位鍵移調變(N-PSK)來傳輸,同時在接收端加入多重天線及最大比例組合器(maximal ratio combiner; MRC) 進一步增進錯誤性能。論文中我們同時對N-PSK及N-DPSK,設計兩種非線性的分集轉換,包括:「直接方塊轉換」(direct block transform)及「循環轉換」(cyclic transform)。這兩種轉換機制會使轉換後的信號區塊具有本質性的空間分集增益,以對抗快速衰弱的通道效應。針對差異同調或同調傳輸,我們提出最大可能性決策接收器來將接收到的信號區塊逐個偵測。文中並推導出各系統之方塊錯誤率(block error probability; BEP)的聯集上界,來評估其錯誤性能。經由推導的聯集上界或切斷率(cutoff rate)的近似式,定義簡單的轉換優勢指數(transform merit figure; TMF)來加速轉換的搜尋。結果顯示,「循環轉換」具有與「直接方塊轉換」相當或較優的錯誤性能,且能大量增加搜尋效率。 根據數值與電腦模擬結果,與現存的相關系統比較,我們提出的系統,在斟酌個別的因素下(如:錯誤性能、傳輸率、偵測延遲、衰弱頻寬等),具有相當或較優的表現。 In this thesis, we consider two approaches of antenna diversity transforms, which operate on the frequency-nonselective fading channels without the knowledge of channel state information. The diversity transforms are designed for three antenna diversity schemes. For the first one, the proposed transmitter consists of a nonlinear block transformer and N_T branches of differential phase modulators, orthogonal pulse shapers and transmit antennas. Both redundancy-free and extended constellations for $N$-DPSK signaling formats are taken into account. Based on the first scheme, the second is proposed to enhance the error performance by using decision feedback differential detection at the receiver. Instead of N-DPSK, in the third scheme we consider coherent N-PSK for the previous diversity system combined with maximal ratio combining at the receiver. In this thesis, two nonlinear transform approaches including the direct block transform and cyclic transform are presented. The resultant signaling mechanism merits intrinsic spatial diversity within each transmitted block, which is resistant to rapid channel fading. The maximum-likelihood receivers are developed to detect the received diversity signal block by block. The expressions of the union bound are derived to assess the block error probability (BEP) characteristics of the proposed diversity schemes. Use the derived approximation of the BEP bounds or cutoff rate expression to define the transform merit figures for searching good transforms. It is analytically shown that the diversity systems employing the searched short-blocklength transforms can offer comparable or enhanced error performance to those existing blind transmit schemes when the trade-offs of decision delay, transmission rate and fading bandwidth are considered.
    顯示於類別:[電機工程研究所] 博碩士論文

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