臺灣博碩士論文加值系統

本論文旨在研究多載波分碼多重近接(multi-carrier coded- division multiple-access, MC-CDMA)系統的位元錯誤率(bit error rate, BER)與使用者容量之效能表示式，其中應用了包括三角式(triangular)與線性式(linear)結構的天線配置；除此之外，亦假設通訊通道分支是工作於呈現具有相關性之Nakagami-m分布的衰落環境之中。系統位元錯誤率(bit error rate, BER)的推導過程中，採取計算隨機過程的特徵函數(characteristic function, CF)方式，以避開利用其他複雜的分析方法，藉以求得接收端輸出訊雜比(signal-to-noise, SNR)的機率密度函數(probability density function, pdf)。最後經由數值分析之結果顯示，MC-CDMA系統之效能確實會受制於不同之天線的配置方式與衰落通道的相關性所影響，依此，本論文所分析的結果，值得提供即將進入第4代無線通訊系統的參考依據，此乃本文之貢獻。

The system BER (bit error rate) and user capacity performance for MC-CDMA (multi-carrier coded-division multiple-access) communi- cation systems are investigated in this paper. The different antenna configurations include triangular and liner configuration antenna array are applied. In addition, the branch is assumed operating in correlated Nakagami-m fading environments. We adopted the CF(characteristic function) to solve the pdf (probability density function) of the SNR (signal-to-noise ratio) at the MRC (maximal ratio combining) output instead of other complicated analysis methods. Finally, the numerical results obviously show that the performance degradation of the MC-CDMA system is sensitive to the correlation of fading channels, which is validated by comparing to some of the results shown in published researches.

目錄

封面內頁
簽名頁
博碩士論文暨電子檔案上網授權書．．．．．．．．．．．．．iii
中文摘要．．．．．．．．．．．．．．．．．．．．．．．．iv
英文摘要．．．．．．．．．．．．．．．．．．．．．．．v
誌謝．．．．．．．．．．．．．．．．．．．．．．．．．．vi
目錄．．．．．．．．．．．．．．．．．．．．．．．．．．vii
圖目錄．．．．．．．．．．．．．．．．．．．．．．．．．x
表目錄．．．．．．．．．．．．．．．．．．．．．．．．．xii
符號說明．．．．．．．．．．．．．．．．．．．．．．．．xiii

第一章 緒論．．．．．．．．．．．．．．．．．．．．．．1
1.1 研究動機與目的．．．．．．．．．．．．．．．．1
1.2 論文綱要．．．．．．．．．．．．．．．．．．．2
第二章 訊號衰落．．．．．．．．．．．．．．．．．．．．4
2.1 訊號衰落的介紹．．．．．．．．．．．．．．．．4
2.2 多重路徑及多重衰落簡介．．．．．．．．．．．．5
2.3 多重路徑衰落所造成的效應．．．．．．．．．．．6
2.4 衰落的形式分類．．．．．．．．．．．．．．．．7
2.4.1 小尺度衰落．．．．．．．．．．．．．．7
2.4.1.1 時間延遲擴散．．．．．．．．．．7
2.4.1.2 時域上的變動性．．．．．．．．．8
2.4.2 大尺度衰落．．．．．．．．．．．．．．10
2.4.2.1 路徑損耗．．．．．．．．．．．．10
2.4.2.2 遮蔽效應．．．．．．．．．．．13
2.5衰落通道的數學模型．．．．．．．．．．．．．．．14
第三章 CDMA系統簡介．．．．．．．．．．．．．．．．17
3.1 前言．．．．．．．．．．．．．．．．．．．．17
3.2 DS-CDMA系統．．．．．．．．．．．．．．．．．17
3.3 MC-CDMA系統．．．．．．．．．．．．．．．．．19
3.4 多載波直序式(MC-CDMA)系統．．．．．．．．．．22
3.5 Multicarrier(MT)-CDMA系統．．．．．．．．．．．24
第四章 常用通信波道統計分佈介紹與比較．．．．．．．．．27
4.1 前言．．．．．．．．．．．．．．．．．．．．．27
4.2 Normal(Gaussian)衰落分佈．．．．．．．．．．．．27
4.3 Rayleigh衰落分佈．．．．．．．．．．．．．．．．30
4.4 Rice衰落分佈．．．．．．．．．．．．．．．．．．32
4.5 Nakagami衰落分佈．．．．．．．．．．．．．．．36
第五章 在相關性Nakagami衰落通道下MC-DS-CDMA系統
效能之研究．．．．．．．．．．．．．．．．．．40
5.1 工作環境說明．．．．．．．．．．．．．．．．．40
5.2 不同的天線配置架構下MC-CDMA系統效能之分 析．．．．．．．．．．．．．．．．．．．．．．41
5.3 MC-CDMA的系統模型．．．．．．．．．．．．．．42
5.3.1 通道模型．．．．．．．．．．．．．．．44
5.3.2 接收機模型．．．．．．．．．．．．．．46
5.3.3 性能分析．．．．．．．．．．．．．．．49
5.3.4 數值結果．．．．．．．．．．．．．．．50
5.4 MC-CDMA之系統架構．．．．．．．．．．．．．54
5.4.1 發射器架構．．．．．．．．．．．．．．54
5.4.2 接收器架構．．．．．．．．．．．．．．56
5.5 MC-CDMA效能分析．．．．．．．．．．．．59
5.5.1 多使用者．．．．．．．．．．．．．．．63
5.5.2 單使用者．．．．．．．．．．．．．．．65
5.5.3 數值分析結果．．．．．．．．．．．．．66
第六章 結論．．．．．．．．．．．．．．．．．．．．．．73
參考文獻．．．．．．．．．．．．．．．．．．．．．．．．74


圖目錄

圖 2.1電磁波傳輸之三種主要物理現象．．．．．．．．．5
圖 2.2 自由空間路徑損耗模型．．．．．．．．．．．．．10
圖 2.3 多路徑傳輸衰落效應．．．．．．．．．．．．．．15
圖 3.1 DS-CDMA系統發射機架構圖．．．．．．．．．．．18
圖 3.2 DS-CDMA系統發射信號頻譜圖．．．．．．．．．．19
圖 3.3 DS-CDMA系統RAKE接收機架構圖．．．．．．．19
圖 3.4 MC-CDMA發射器架構圖．．．．．．．．．．．．20
圖 3.5 MC-CDMA發射信號頻譜圖．．．．．．．．．．．21
圖 3.6 MC-CDMA接收器架構圖．．．．．．．．．．．．21
圖 3.7 修正型的MC-CDMA發射器架構圖．．．．．．．．21
圖 3.8 修正型的MC-CDMA發射信號頻譜圖．．．．．．．22
圖 3.9 Multicarrier DS-CDMA發射器架構圖．．．．．．．．23
圖 3.10 Multicarrier(MC)-DS-CDMA發射信號頻譜圖．．．．23
圖 3.11 Multicarrier(MC)-DS-CDMA接收器架構圖．．．．．24
圖 3.12 MT-CDMA發射器架構圖．．．．．．．．．．．．25
圖 3.13 MT-CDMA發射信號頻譜圖．．．．．．．．．．．25
圖 3.14 MT-CDMA接收器架構圖．．．．．．．．．．．．26
圖 4.1 單變數Gaussian衰落信號包封機率密度函數．．．．28
圖 4.2 單變數Rayleigh衰落信號包封機率密度函數．．．．31
圖 4.3 單變數Rice衰落信號包封機率密度函數．．．．．．35
圖 4.4 單變數Nakagami衰落信號包封機率密度函數．．．．38
圖 5.1 MC-CDMA 系統的傳送模型．．．．．．．．．．．52
圖 5.2 m=3和 N=3時訊雜比和誤碼率為線性陣列時的圖形．52
圖 5.3 m=3和 N=3時訊雜比和誤碼率為三角形陣列時的圖形53
圖5.4 m=3和 N=3時訊雜比和誤碼率為不同陣列時的圖形．53
圖5.5 N=3, and K=32時訊雜比和誤碼率三角形陣列結構跟不同 的衰減參數．．．．．．．．．．．．．．．．．．．58
圖 5.6 單載波的頻寬．．．．．．．．．．．．．．．．．55
圖 5.7 多載波的頻寬．．．．．．．．．．．．．．．．．55
圖 5.8 發射器架構圖．．．．．．．．．．．．．．．．．56
圖 5.9 接收器架構圖．．．．．．．．．．．．．．．．．57
圖 5.10 偏頻干擾頻譜圖．．．．．．．．．．．．．．．58
圖 5.11 單使用者情況下，在不同的衰落係數下的效能．．．67
圖 5.12 多使用者情況下，在不同的衰落係數下的效能．．68
圖 5.13 多使用者情況下，在不同長度的展頻碼下的效能．68
圖 5.14 在不同的衰落係數下的使用者數量對位元錯誤率．69
圖 5.15 不同的使用者數量下的，相關係數改變後的效能．．69
圖 5.16 不同的衰落係數下的，相關係數改變後的效能．．．70
圖 5.17 單載波下，不同干擾功率對信號功率的比值．．．．70
圖 5.18 多載波下，不同干擾功率對信號功率的比值．．．．71
圖 5.19 在多載波和單載波下，偏頻干擾對位元錯誤率．．．71
圖 5.20 多載波下，有無偏頻干擾及不同相關係數下之效能．72
圖 5.21 單載波下，有無偏頻干擾及不同相關係數下之效能．72

表目錄

表2. 1 不同環境下路徑損耗指數值．．．．．．．．．．．．13


符號說明

：訊號延遲時間．．．．．．．．．．．．．．．．．．．．8
：符際區間．．．．．．．．．．．．．．．．．．．．．．8
：展頻碼片週期．．．．．．．．．．．．．．．．．．．．9
：發射天線平均功率．．．．．．．．．．．．．．．．．．10
：發射天線增益．．．．．．．．．．．．．．．．．．．10
：接收天線平均功率．．．．．．．．．．．．．．．．．．10
：接收天線增益．．．．．．．．．．．．．．．．．．．10
：發射天線到接收天線距離．．．．．．．．．．．．．．．11
：載波波長．．．．．．．．．．．．．．．．．．．．．．11
：載波頻率．．．．．．．．．．．．．．．．．．．．．．11
：載波頻率．．．．．．．．．．．．．．．．．．．．．．11
：發射端與接收端的距離．．．．．．．．．．．．．．．．11
：平均路徑損耗．．．．．．．．．．．．．．．．．．12
：零平均值的高斯隨機變數．．．．．．．．．．．．．．13
：零平均值的高斯隨機變數的標準差．．．．．．．．．．．13
x：接收信號功率．．．．．．．．．．．．．．．．．．．．14
：區域平均信號功率．．．．．．．．．．．．．．．．．14
：取dB值之後的變異數．．．．．．．．．．．．．．．．14
：接收信號強度的平均值．．．．．．．．．．．．．．．．14
：接收信號的電壓有效值．．．．．．．．．．．．．．．．14
：接收信號的平均功率．．．．．．．．．．．．．．．．14
：傳送信號．．．．．．．．．．．．．．．．．．．．．15
：輸出信號．．．．．．．．．．．．．．．．．．．．．15
：迴旋積分．．．．．．．．．．．．．．．．．．．．．．15
：通道的脈衝響應．．．．．．．．．．．．．．．．．15
：高斯白雜訊．．．．．．．．．．．．．．．．．．．．15
δ(t)：脈衝函數．．．．．．．．．．．．．．．．．．．．．16
：第i條路徑的振幅或衰落係數．．．．．．．．．．．．16
：第i條路徑的路徑延遲．．．．．．．．．．．．．．．16
：第i條路徑的相位．．．．．．．．．．．．．．．．．16
：多重路徑之總數．．．．．．．．．．．．．．．．．．16
：第K個使用者的第i個展頻碼．．．．．．．．18
：第k個使用者展頻碼．．．．．．．．．．．．．．．18
N：展頻碼長度．．．．．．．．．．．．．．．．．．．．．19
：第N個載波頻率．．．．．．．．．．．．．．．．．．20
：相關係數．．．．．．．．．．．．．．．．．．．．．．29
為零階第一類修正貝氏函數．．．．．．．．．．．．．33
：Rice衰落因子．．．．．．．．．．．．．．．．33
：Marcum-Q 函數．．．．．．．．．．．．．．．．34
：訊號的功率頻譜密度．．．．．．．．．．．．．．．35
：第i個路徑所接收到信號之平均功率．．．．．．．．．．37
：第i個路徑所接收到Nakagami衰落係數．．．．．．．．37
：伽瑪(gamma)函數．．．．．．．．．．．．．．．．．37
：位元單位能量．．．．．．．．．．．．．．．．．．．．37
：滾輪因子．．．．．．．．．．．．．．．．．．．．．．54
：頻寬．．．．．．．．．．．．．．．．．．．．．．．54
：chip能量．．．．．．．．．．．．．．．．．．．．．．55
：代表實數的部份．．．．．．．．．．．．．．．．．55
：隨機載波相角．．．．．．．．．．．．．．．．．．．55
：每一個通道的複數低通脈衝響應．．．．．．．．56
：第i通道的衰落因子．．．．．．．．．．．．．．．．56
：第i通道的相角偏移量．．．．．．．．．．．．．．．56
：白高斯雜訊．．．．．．．．．．．．．．．．．．．57
：白高斯雜訊功率頻譜密度．．．．．．．．．．．．．．57
：偏頻干擾．．．．．．．．．．．．．．．．．．．．．57
：偏頻干擾功率頻譜密度．．．．．．．．．．．．．．57
JSR：干擾功率對信號功率的比值．．．．．．．．．．．．．57
L：多重路徑的數量．．．．．．．．．．．．．．．．．．．65
：偏頻干擾自相關函數．．．．．．．．．．．．．．．61
：雜訊自相關函數．．．．．．．．．．．．．．．．．61
： 傅利葉轉換．．．．．．．．．．．．．．．．61
：第i個分支的增益．．．．．．．．．．．．．．．．．．62
：多重存取干擾自相關函數．．．．．．．．．．．．．63
：單載波展頻碼長度．．．．．．．．．．．．．．．．．65
：單載波的能量．．．．．．．．．．．．．．．．．．．65

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