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Title: | 行動式多輸入多輸出正交分頻多工系統中聯合傳送機與接收機波束合成之設計 Design of Joint Transmitter-Receiver Beamforming in Mobile MIMO OFDM Systems |
Authors: | Chun-Hao Liu 劉峻豪 |
Advisor: | 闕志達(Tzi-Dar Chiueh) |
Keyword: | 聯合波束合成, Joint Beamforming, |
Publication Year : | 2009 |
Degree: | 碩士 |
Abstract: | 為滿足下個世代無線通訊傳輸的高頻譜使用率,高效率以及低錯誤率傳輸的要求,多輸入多輸出正交分頻多工(MIMO-OFDM)的技術應運而生。甚者,要是我們能透過聯合傳送機與接收機做波束合成的同步設計,不但可以更進一步充分利用通道資訊(CSI),而且使得設計複雜度合適地分配在傳送機與機收機。
傳統的聯合波束合成設計通常假設在靜態或是低速移動的通道環境下進行設計。本論文針對這點,將其重點擴展到高速移動的環境下做設計,並且使用最佳化(optimization)技巧和遞迴式平行干擾消除法(iterative parallel interference cancellation)同時對抗由MIMO系統產生的天線間干擾(inter-antenna interference)和由OFDM系統產生的載波間干擾(inter-carrier interference)。 本論文另一個重點在於考慮傳統聯合波束合成設計假設上的缺點-假設在傳送端與接收端擁有完美的通道資訊。事實上通道資訊在接收端被估測後會有估測誤差(estimation error),回傳通道資訊給傳送端也會有回傳延遲(feedback delay)。針對這些不完美的通道資訊,我們不僅評估了它們對聯合波束合成的影響,還提出了使用低複雜度(low complexity)的通道預估(channel prediction)技巧對回傳延遲做補償,例如用一個聯合計算架構(joint calculation structure)可以大大降低所需運算複雜度,或是採用快速收斂的遞迴式可抗噪性演算法。最後搭配外傳送機與接收機(outer transceiver),本系統可以更進一步達到高水準的系統效能。 In order to satisfy several advantages such as high utility rate of frequency spectrum, high efficiency of transmission rate and low error rate in wireless communication systems, MIMO-OFDM has been proposed for many years as a hot topic to achieve high quality of service. Furthermore, if we can design transmitter and receiver synchronously using joint beamforming technique, in addition to take full advantage of channel state information (CSI), we can also distribute design complexity on both transmitter and receiver appropriately. Traditionally, joint beamforming technique is usually designed under static or low mobility channel assumption. Our thesis focuses on channel condition with high mobility, and we use optimization technique with iterative parallel interference cancellation scheme to oppose inter-antenna interference from MIMO system and inter-carrier interference from OFDM system simultaneously. Another point in this thesis is considering the drawback of traditional joint beamforming design-assuming perfect CSI on both TX and RX. In fact, estimation error occurs after CSI is estimated in RX, and feedback CSI from RX to TX will cause feedback delay. In the light of these drawbacks, we not only evaluate the influence of these effects on joint beamforming, we also propose using low complexity channel prediction scheme to compensate for feedback delay, such as a joint calculation structure to greatly reduce computational complexity, or a recursive algorithm which can oppose noise in a high convergence rate. Finally, cascading with an outer transceiver, our system can further achieve a high level performance. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/44060 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 電子工程學研究所 |
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ntu-98-1.pdf Restricted Access | 1.73 MB | Adobe PDF |
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