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標題: 高階QAM通信系統的盲蔽式等化與載波恢復協同 設計與模擬
Design and Simulation of Joint Blind Equalization and Carrier Recovery for High-Order QAM Communication System
作者: 白政達
pai, Cheng-Ta
關鍵字: Carrier Recovery;載波恢復器;Blind Equalization;等化器
出版社: 電機工程學系所
在混合光纖與同軸電纜(HFC,Hybrid-Fiber-and-Coaxial)的通訊傳輸當中,隨著時代的進步,對於傳輸時頻寬的要求也跟著提高了,而在提高頻寬的同時,也產生了許多的問題。例如,為了增加頻寬使用率而造成的符元間干擾(ISI,Inter-Symbol Interference),及在傳輸過程當中所受到的相位偏移的影響,皆會造成我們在提高傳輸頻寬時的困難。我們藉由[3]當中的盲蔽式等化器演算法效能的提高,去增加有線通訊系統的接收機效能。我們以MCMA+DD/DD[3]的等化器演算法與CMA 等化器演算法,分別加入均方根餘弦濾波器驗證系統組合架構的可行性及效能,並比較在64/256/1024 的QAM 調變系統中等化器演算法與均方根餘弦濾波器在同步系統當中的收斂結果。而後調整載波恢復器的架構,變動相位鑑別器、 迴路濾波器及數值控制振盪器的參數設定與處理訊號的順序,去得到一個收斂效能較好的載波恢復器。觀察在各階調變系統中雜訊干擾對載波恢復器效能的影響後,利用載波恢復器與MCMA+DD 及CMA 等化器演算法的搭配去對接收信號進行收斂。在第一階等化器的運作模式,我們利用不同等化器去對接收信號進行通道效應的消除,使載波恢復器可以在較乾淨的環境去進行相位偏移的補償;在載波恢復器收斂後,我們再切換等化器演算法的運作方式,使接收端可以得到更低的符元錯誤率(SER,symbol error rate)及均方誤差(MSE,mean square error)。

In Hybrid-Fiber-and-Coaxial the transmission of communications ,the transmission bandwidth demands increase with the progress of the times ,but also generated a lot of problems。For example, to increase bandwidth usage caused by the ISI, and in the course of transmission by the phase offset by the impact will cause us all to improve bandwidth at the difficulties. We By [3] of the Bi-blind Equalizer improve the performance of algorithms, the cable communications system to increase the effectiveness of receivers.
We used modified constant modulus algorithm (MCMA) + decision-directed (DD) / DD [3] the equalizer algorithms and constant modulus algorithm(CMA) equalizer algorithms , respectively square-root raised cosine (SRRC) filter verification system structure of the composition of the feasibility and effectiveness, and to compare in 64/256/1024 the QAM modulation system in the equalizer algorithms and square-root raised cosine filter are in synchronization the convergence results. Then adjust the structure for carrier recovery, phase detector, loop filter, numerically controlled oscillator and set the parameters and signal processing the order, to get a better performance of convergence for the carrier recovery. Observed in various order of modulation system noise interference on carrier recovery for the impact of performance, and the use of carrier recovery for MCMA + DD and the CMA equalizer with algorithms to receive the signal convergence。Equalizer mode of operation in the first stage, we use different algorithms to eliminate Equalizer receive signals in the channel effect, the carrier could resume in a relatively clean environment to carry out the transmission phase shift of compensation; The carrier recovery for convergence, we Equalizer algorithms to switch the mode of operation so that the receiver can get a lower symbol error rate(SER) and mean square error(MSE).
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