Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/6061
標題: 無線通訊高頻譜效益正交重疊調變技術之應用
Bandwidth Efficiency Quadrature Overlapping Modulation for Applications in Wireless Communications
作者: 洪一紳
Hung, Ethan
關鍵字: Modulation;調變技術;Quadrature Overlapping;Detection;Decision Feedback;Soft MLSD;Hard MLSD;Optimum Receiver;Sub-Optimum Receiver;正交重疊;偵測技術;決定回授;軟性最相近序列偵測;硬性最相近序列偵測;最佳接收器;次佳接收器
出版社: 電機工程學系
摘要: 
隨著多媒體與無線通訊的蓬勃發展,無線頻帶的需求日益殷切,如何在在有限的無線頻寬中傳輸大量的資料是重要的課題。
正交重疊調變技術是一種具有高頻帶利用效益的調變技術,其主要原理是在載波調變之前先利用波形整型技術先對基頻訊號整型,再經波形的重疊處理,再送至載波調變。此項調變技術較原OQPSK, MSK調變技術擁有較大之衰落因子(roll-off factor),以正交重疊升餘弦調變為例,其旁波瓣功率頻譜密度衰減速度可達 ,因此有較高的頻帶效益。
在本論文中研究不同的接收器對正交重疊調變的適應性。理論分析及模測試數種偵測技術,包括半波週期偵測、全波週期相似性偵測、全波週期平均波形濾波器、中央半波週期相似性偵測、中央半波週期平均波形濾波器、決定回授、硬性最相近序列偵測和軟性最相近序列偵測。並以Matlab應用程式完成各項的模擬測試。結果顯示,軟性最相近序列偵測為最佳接收器,而中央半波週期平均波形濾波器為次佳接收器且具有優點如結構簡單和無延遲效應。結果並顯示,適當的組合如波週期平均波形濾波器配合QOTC波形調變不僅具有更高頻譜效益,更能降低誤碼率。

With the booming growth of multimedia and wireless communications, the demand for wireless bandwidth is urgent. So, how to transmit more information within a limited bandwidth is an important issue.
Quadrature Overlapping Modulation has been proven a bandwidth efficiency modulation technique. The main theories are the baseband pulse waveform shapping of overlapping pulse and quadrature combining before carrier modulation. This modulation technique can possess a larger roll-off factor. For example, the sidelobes of Quadrature Overlapped Raised-Cosine (QORC) modulation drop off much faster ().
Several types of receivers are investigated about the adaptation with Quadrature Overlapping Modulation. Analysis and simulations of several kinds of detection schemes are presented, including Half Symbol Period Correlation, Whole Symbol Period Correlation, Whole Symbol Period Average Waveform Matched Filter, Central Half Symbol Period Correlation, Central Half Symbol Period Average Waveform Matched Filter, Decision Feedback, Hard Maximum Likelihood Sequence Detection (Hard MLSD) and Soft Hard Maximum Likelihood Sequence Detection (Soft MLSD). Simulation was done with Matlab, the result shows that the Soft MLSD is the optimum detection and Central Half Symbol Period Average Waveform Matched Filter could be considered as the sub-optimum detection for high performance evaluation and advantages of ‘simple structure' and ‘no delay'. It also shows that the combination of sub-optimum detection with QOTC modulation performs outstandingly both in bandwidth efficient aspect and bit-error-rate performance.
URI: http://hdl.handle.net/11455/6061
Appears in Collections:電機工程學系所

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