主動式多天線干擾消除技術-針對偷竊式感知無線電技術與正交多頻分工之設計

感知無線電技術(Cognitive Radio，CR)，在現今日新月異，逐漸趨近飽和的通訊環境裡，慢慢地佔有一席之地。它可以智慧地偵測並確認哪一個通訊頻帶正在使用，然後自動地將使用者轉換到沒有被佔用的頻帶上。而本篇論文正是建立在感知無線電技術下，進而延伸的新架構，我將它稱之為：主動式多天線干擾消除理論(MIMO Active Interference Cancellation Algorithm)。本篇論文將探討在3.5G WiMAX (Worldwide Interoperability for Microwave Access的縮寫，一般中譯為：全球互通微波存取)與UWB (Ultra WideBand是超寬帶無線技術的縮寫) 兩種通訊協定重疊並共存的情形。我們假定原使用者採用WiMAX技術，而第二使用者則是使用UWB的技術。在不影響原使用者的前題之下，第二使用者該如何用相同的頻段偷偷地傳送資料，並讓接收端準確無誤地得到資訊？主動式多天線干擾消除理論的提出，即是一種良好的辦法。本篇論文也提出了一種多天線盲道估測(MIMO Blind Channel Estimation)的方法，並與主動式干擾消除理論(Active Interference Cancellation Algorithm)作結合，我們將介紹兩者間的互利共存，也模擬出各種不同的結果進而討論、分析。在第二使用者的接收端部分，討論V-BLAST Algorithm(垂直-分層空時結構)，說明這種解碼器的優缺點，並提出改進的方式。在未來，會有越來越多的通訊系統、協定的產生，頻帶的使用與分配將會是最重要的課題。我們期許本篇論文(MIMO Active Interference Cancellation for Stealth Cognitive Radio on OFDM system)所提出的架構，盡可能地解決這樣的問題，讓未來的溝通更加完善。

關鍵字

感知無線電技術；主動式多天線干擾消除理論；全球互通微波存取；超寬帶無線技術；正交多頻分工

並列摘要

Cognitive Radio (CR) is considered as a promising approach for efficient utilization of precious radio spectrum resources. In this thesis, we present a new approach that combine active interference cancellation (AIC), Blind Channel Estimation and vertical Bell Laboratories Layered Space-Time (V-BLAST) techniques to transmit data through a multiple-input and multiple-output (MIMO) system within protected band which has been assigned for primary subscribers. This method allows the transmitter to transmit data in the protected band in a stealth fashion (as low as -120dB to -300dB) so that the primary subscribers will be unaware of the transmission. The simulation shows that BER performance in the protected band is as good as in the unprotected band. We have also construct a blueprint by simulating the scheme with the co-existence of 3.5G WiMAX and MB-OFDM UWB devices.

並列關鍵字

Cognitive Radio ； Active Interference Cancelation ； WiMAX ； UWB ； OFDM

參考文獻

[4] H. Yamaguchi, “Active Interference Cancellation Technique for MB-OFDM Cognitive Radio,” IEEE Microwave Conference, 2004.

[5] Bertrand Muquet, Marc de Courville and Pierre Duhamel, “Subspace-Base Blind and Semi-Blind Channel Estimation for OFDM systems”, IEEE Transactions on Signal Processing, Vol. 50, No. 7, July 2002.

[6] Ifiok Jarlath Umoh and Tokunbo Ogunfumi, “Semi-Blind Channel Estimation for OFDM Using Least Squares”, 2006 IEEE.

[7] J. Mitola III, “Cognitive Radio: Making software radios more personal,” IEEE Pers. Commun. ,vol. 6, no. 4, pp. 13-18, Aug. 1999.

[8] J. Mitola III, “Cognitive radio for flexible mobile multimedia communications,” in 1999 IEEE International Workshop on Mobile Multimedia Communications, 15-17 Nov. 1999, pp. 3-10.

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主動式多天線干擾消除技術-針對偷竊式感知無線電技術與正交多頻分工之設計

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