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研究生:李智惟
研究生(外文):Chih-Wei, Lee
論文名稱:應用於無線音頻傳輸之直接序列展頻通訊與耙型接收器之實現—使用FPGA
論文名稱(外文):An Implementation of DSSS and RAKE Receiver for Wireless Audio Transmission — Using FPGA
指導教授:溫志宏溫志宏引用關係
指導教授(外文):Jyh-Horng, Wen
學位類別:碩士
校院名稱:國立中正大學
系所名稱:電機工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:102
中文關鍵詞:無線音頻傳輸直接序列展頻耙型接收器
外文關鍵詞:Wireless Audio TransmissionDSSSRAKE ReceiverLeast SquareFPGA
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一般無線通訊系統中,訊號經由無線通道傳遞時,無可避免地會遭受各種干擾,除了能量衰減、雜訊之外,由於多重路徑(Multi-path)的傳遞,使得訊號以不同路徑在不同時間點到達接收端,而形成干擾。因此,有許多用來克服多重路徑效應的技術便陸續被提出;其中,耙型接收器(RAKE Receiver)便是其一。
而在展頻通訊中,當接收端解展頻(De-spreading)的同時,由於展頻碼(Spreading Code)的高自相關性(Auto-correlation),將只留下訊號強度最強的路徑,其餘路徑的訊號將被視為雜訊般地除去。但其實多重路徑的訊號是可以被加以運用的。使用耙型接收器便是此目的。
耙型接收器可將多重路徑的訊號加以分離,藉由通道估測(Channel Estimation)針對各路徑分別補償通道效應,之後將各路徑結合供決策電路使用,如此可提高雜訊比(Signal to Noise Ratio,SNR),達到低位元錯誤率(Bit Error Rate)。
在本論文中,將實現一個用於無線音頻傳輸系統(Wireless Audio Transmission System)的耙型接收器,搭配Least Square Estimation做為通道估測的方式,以克服室內環境中所生的多重路徑效應。

In wireless communication system, signals unavoidably suffer interference when transmitting through wireless channel. Besides energy decaying and noise, signals will arrive to receiver in different directions at different time due to multipath transmission. This effect is interference. As the result, many technologies that combat multi-path effect are introduced. One of them is RAKE Receiver.
In spread spectrum communication, because of high auto-correlation of the properties of spreading code, only the signal of the maximum energy will be de-modulated when receiver is de-spreading. Other signal that is produced by multi-path effect is ignored as noise. But these signals can be used for de-modulation. That’s why RAKE Receiver is used.
RAKE Receiver can take apart signals that are affected by multi-path, and estimate each path about delay time, fading gain, and phase shift. Then, RAKE Receiver will compensate these parameters to signal of each path, and combine signals after compensation for decision circuit. By the way, the signal to noise ratio (SNR) will be increased, and bit error rate (BER) of the system will be decreased.
This thesis will introduce and implement a RAKE Receiver for wireless audio transmission system. The RAKE receiver uses “Least Square Estimation” as channel estimation skill to combat multi-path effect in indoor environment.

前言…………………………………………………………I
摘要…………………………………………………………II
Abstract……………………………………………………III
目錄…………………………………………………………IV
圖目錄………………………………………………………V
表目錄………………………………………………………VI
第一章 簡介……………………………………………1-1
1.1 動機與背景……………………………………1-1
1.2 研究與實現方法………………………………1-1
1.3 論文架構說明…………………………………1-2
第二章 展頻通訊原理…………………………………2-1
2.1 展頻通訊分類…………………………………2-1
2.2 直接序列展頻通訊特性………………………2-2
2.3 展頻碼特性與Processing Gain………………2-4
2.4 耙型接收器………………………………………2-5
第三章 無線通道介紹……………………………………3-1
3.1 無線訊號的傳遞…………………………………3-1
3.2 多重路徑效應……………………………………3-2
3.3 室內多重路徑無線通道模型……………………3-4
第四章 系統架構介紹……………………………………4-1
4.1 系統規格說明……………………………………4-1
4.2 傳送端架構設計…………………………………4-2
4.2.1 DQPSK調變………………………………………4-2
4.2.2 直接序列展頻……………………………………4-3
4.2.3 Pulse Shaping和Over-sampling………………4-4
4.3 接收端架構設計…………………………………4-7
4.3.1 載波回復機制……………………………………4-7
4.3.1.1 針對Sample的載波回復機制……………………4-8
4.3.1.2 針對Symbol的載波回復機制……………………4-9
4.3.2 接收濾波器………………………………………4-10
4.3.3 通道估測技術……………………………………4-12
4.3.3.1 Least Square Estimation………………………4-12
4.3.3.2 平均通道估測雜訊影響的成分…………………4-17
4.3.3.3 Finger Selection………………………………4-17
4.3.4 耙型接收器………………………………………4-17
4.3.5 解展頻……………………………………………4-18
4.3.6 Peak Search………………………………………4-19
4.3.7 DQPSK解調變………………………………………4-19
第五章 Matlab模擬結果……………………………………5-1
5.1 室內多路徑無線通道之脈衝響應…………………5-1
5.2 通道估測結果………………………………………5-3
5.3 載波回復機制效能…………………………………5-20
5.4 耙型接收器效能……………………………………5-24
5.4.1 RAKE vs. Non-RAKE…………………………………5-24
5.4.2 Floating Point vs. Fixed Point………………5-28
5.5 結論…………………………………………………5-32
第六章 RTL模擬結果…………………………………………6-1
6.1 載波回復機制…………………………………………6-2
6.2 接收濾波器……………………………………………6-3
6.3 耙型接收器……………………………………………6-4
6.4 解展頻…………………………………………………6-5
6.5 Peak Search……………………………………………6-7
6.6 DQPSK解調變……………………………………………6-8
6.7 資源列表與結論…………………………………………6-9
第七章 討論與未來展望…………………………………………7-1
附錄A 參考文獻……………………………………………………A-1
附錄B 接收器電路功能驗證結果…………………………………B-1

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