正交分頻多工系統下運用虛擬載波改良盲目波束成型特徵值分析之演算法設計;Improved Blind Beamforming of Eigen-based Schemes in OFDM Systems with Virtual Carriers

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题名:	正交分頻多工系統下運用虛擬載波改良盲目波束成型特徵值分析之演算法設計;Improved Blind Beamforming of Eigen-based Schemes in OFDM Systems with Virtual Carriers
作者:	甘偉民;Kan,Wei-min
贡献者:	通訊工程學系在職專班
关键词:	特徵值;盲目;波束成型;虛擬;eigen;blind;beamform;virtual
日期:	2015-07-23
上传时间:	2015-09-23 13:26:38 (UTC+8)
出版者:	國立中央大學
摘要:	正交分頻多工系統通訊方式為E-UTRAN所採用，先前有一篇研究名為「正交分頻多工系統下適應型天線陣列運用虛擬載波進行干擾抑制」可降低同頻強干擾，進而達到良好的表現。該篇研究是基於特徵值分析方法，並在一個正交分頻多工符碼區間內，利用非零值之資訊子載波來估測發送訊號加上干擾及雜訊之空間關係矩陣；以及利用零值之虛擬子載波來估測干擾及雜訊之空間關係矩陣。進而波束成型權重向量的解答就是兩個評估空間矩陣之最大廣義特徵向量。上述方法看似完美，但不幸的是它的表現會隨著子載波總數增加而變的非常差。在此篇論文內，我們不但發現了錯誤率表現變差的原因，並想到了利用閒置資訊子載波去改善空間關係矩陣的評估結果。此外，本篇論文亦提出了二維區段估測方法來解決上述表現變差之問題，甚至於子載波總數達到2048。而此子載波數目係在E-UTRAN標凖中最大子載波數。最後，本篇論文藉由一連串的實驗，進行發展出如何決定在頻域及時域上之區段大小的方法。;The Orthogonal frequency division multiplexing (OFDM) communication system is adopted for transmission by Evolved-Universal Terrestrial Radio Access Network (E-UTRAN). A former research, “Adaptive Antenna Arrays for Interference Cancellation in OFDM Communication Systems With Virtual Carriers”, can cancel strong co-channel interferences to achieve competitive performances. This research is based on Eigen-analysis and it estimates the spatial correlation matrix of signal-plus-interference-plus-noise by choosing samples from information subcarriers (nonzero-value) and estimates the spatial correlation matrix of interference-plus-noise by selecting samples from virtual subcarriers (zero-value) in one OFDM symbol duration. The solution of the beamforming weight vector by Eigen-analysis is the “largest” generalized eigenvector corresponding to the estimated matrix pencil. Unfortunately, those schemes look perfect but their performances become worse as the increasing of subcarriers. In this thesis, we find out the reason for bad performances and utilize the “idle data subcarriers” to enhance the estimation of spatial correlation matrix. Besides, we propose the “2D-grouping” method to improve the bad performance problem even the subcarrier number equals to 2048 that is the maximal number of subcarriers in E-UTRAN. Finally, this thesis also develops the scheme to decide the grouping range in frequency and time domains by a serious of experiments.
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