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研究生:林正偉
研究生(外文):Cheng-Wei Lin
論文名稱:後置快速傅立葉轉換之逐用戶波束成型演算法於存在時間相關路徑的多用戶正交分頻多工系統
論文名稱(外文):A Blind Post-FFT User-by-user Beamforming Algorithm for Multiuser OFDM Systems in the Presence of Temporally Correlated Paths
指導教授:祁忠勇
指導教授(外文):Chong-Yung Chi
學位類別:碩士
校院名稱:國立清華大學
系所名稱:通訊工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2008
畢業學年度:96
語文別:中文
論文頁數:49
中文關鍵詞:正交分頻多工峰度後置快速傅立葉轉換波束成型器
外文關鍵詞:OFDMkurtosispost-FFTbeamformer
相關次數:
  • 被引用被引用:0
  • 點閱點閱:272
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  • 下載下載:39
  • 收藏至我的研究室書目清單書目收藏:1
最近,祁忠勇教授與彭俊賢博士等人提出了一個於後置快速傅立葉轉換(post-FFT)下基於子載波平均的多級盲波束成型演算法(MSBFA)應用於正交分頻多工(OFDM)系統。而且也已經知道,多級盲波束成型演算法可有效的工作於存在空間相關路徑(Spatially Correlated Paths)與通道衰落(channel fading)的環境。然而,此演算法在檢測與估計時是對接收的路徑信號採逐路徑信號分離,因此會有較長的時間延遲。有鑑於此,在本篇論文中我們提出了逐用戶盲波束成型演算法(UUBFA);相對比於多級盲波束成型演算法,逐用戶盲波束成型演算法在結構上採用平行處理的想法,使我們可以在一級之中,從接收的路徑信號中分離出同一用戶的所有路徑信號。這不僅使檢測與估計的時間延遲縮短,更適用於軟硬體的實作;論文第六章透過電腦模擬可以發現逐用戶盲波束成型演算法除了擁有以上優點外還保有了多級盲波束成型演算法優良的性能,如:在一個符號區間(Symbol block)內完成所有的解調;性能接近非盲的最小化方均誤差波束成型器(Nonblind MMSE beamformer)。另外在論文末段,針對環境中存在時間相關路徑(Temporally Correlated Paths),使用了快速峰度最大化演算法(FKMA)進行補償,並提出了渦輪峰度最大化波束成型器(TKMBF)於多級盲波束成型演算法可以有效對抗嚴苛的環境(不論是在環境中是否存在時間相關路徑信號或是空間路徑信號或是兩者同時存在的情況)。
Recently, Peng and Chi et al. proposed a block-by-block blind post-FFT multistage beamforming algorithm (MSBFA) based on subcarrier averaging for a multiuser orthogonal frequency division multiplexing (OFDM) system, which works well under multipath block fading channels even in the presence of correlated paths. However, the MSBFA is a sequential path-by-path detection algorithm, thereby
resulting in long detection latency as the total number of paths of all the active users is large. In this paper, a blind multistage user-by-user beamforming algorithm (UUBFA) is proposed, which, in contrast to the MSBFA, detects all the path signals for one individual user and meanwhile achieves the maximum diversity gain through a blind maximum ratio combining processing at each stage. In addition to achieving the same performance as the MSBFA, the parallel signal processing structure of the proposed UUBFA is well suited to software and hardware implementations. At the end of thesis, we used FKMA [7] to find the frequency domain equalizer. Finally we proposed the MSBFA (TKMBF) which perfoms well in the presence of both temporally and/or spatially correlated paths.
1 前言 . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 多用戶 OFDM 系統下波束成型之信號模型 . . . . . . . . . 5
2.1 前置快速傅立葉轉換波束成型架構下之信號模型 . . . . . 8
2.2 後置快速傅立葉轉換波束成型架構下之信號模型 . . . . . 10
3 子載波平均 . . . . . . . . . . . . . . . . . . . . . . 12
4 現存演算法介紹 . . . . . . . . . . . . . . . . . . . . 14
4.1 基於子載波平均傅立葉波束成型器與峰度最大化波束成型器 16
4.1.1 傅立葉波束成型器 . . . . . . . . . . . . . . . . . 16
4.1.2 峰度最大化波束成型器 . . . . . . . . . . . . . . . 17
4.1.3 混合 Fourier-KMBF 波束成型器 . . . . . . . . . . . 20
4.2 基於子載波平均的多級波束成型演算法 (MSBFA) . . . . . 21
5 提出的演算法應用於OFDM系統 . . . . . . . . . . . . . . 24
5.1 提出的逐用戶盲波束成型演算法 (UUBFA) . . . . . . . . 24
5.2 空間相關信號下的波束成型 . . . . . . . . . . . . . . 28
5.3 時間相關信號下的波束成型 . . . . . . . . . . . . . . 29
6 模擬結果 . . . . . . . . . . . . . . . . . . . . . . . 38
7 結論 . . . . . . . . . . . . . . . . . . . . . . . . . 45
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