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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/8144


    Title: 使用MIMO架構的通道估測來降低OFDM架構下LMDS系統的同頻干擾;Reducing the Co-channel Interference of OFDM-based LMDS Systems by MIMO Structured Channel Estimation
    Authors: 廖健宏;Chien-Hung Liao
    Contributors: 通訊工程研究所
    Keywords: 區域多點分配服務;多重輸入多重輸出;正交分頻多工;OFDM;LMDS;MIMO
    Date: 2006-06-29
    Issue Date: 2009-09-22 11:19:19 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 由於LMDS乃是使用28GHz之雙向數位式細胞系統,同頻干擾(Co-channel Interference) 對於系統性能是一個限制因素,尤其LMDS的下傳鏈路(Downstream)通常有較高的容量,因此在下傳鏈路的同頻干擾比上傳鏈路(Upstream)嚴重。正交分頻多工(Orthogonal Frequency Division Multiplexing; OFDM)是一套有效率的方法,可以傳輸高速率資料及對抗碼際干擾(Inter-symbol Interference)和多路徑傳輸的衰減。本論文主要是探討如何提昇以OFDM為基礎之區域多點分配服務系統的性能,我們將模擬LMDS的寬頻通道、架構OFDM傳輸系統,利用多重輸入多重輸出(Multi-Input-Multi-Output; MIMO)架構來估測用戶端(Subscriber)與基地台(Base station) 與細胞間干擾之干擾台(Interfering Stations)之通道頻率響應,並 以估測的通道頻率響應來實現通道等化(Channel Equalization)。如此一來,細胞間的干擾可以有效地降低。本論文也會討論利用調適性調變(Adaptive modulation)技術,以提昇系統的效能。 LMDS usually operates at millimeter-wave frequencies about 28 GHz and it is a two-way digital cellular system, co-channel interference is the limiting factor of system performance. In the downstream, the channel capacity is higher than that in the upstream, and the co-channel interference of the downstream is more serious than that of the upstream. In order to reduce the co-channel interference, we apply the orthogonal frequency division multiplexing (OFDM) to the LMDS system to simulate the OFDM-Based LMDS. OFDM is an efficient and suitable technique to combat ISI in wideband channels. Since each OFDM sub-carriers has a very narrow spectrum. It can transmit high data rate and combat the inter-symbol interference and the multipath fading. In this thesis, we will improve the performance of OFDM-Based LMDS system by using MIMO structured channel estimation. In order to promote systematic efficiency, this thesis will adopt adaptive modulation techniques too.
    Appears in Collections:[通訊工程研究所] 博碩士論文

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