在高傳輸資料量的無線通訊環境中，多載波分碼多重存取(Multi-Carrier Code Division Multiple Access, MC-CDMA)系統能提供相當好的實現應用，有別於傳統CDMA系統將展頻碼擴展在時域上，MC-CDMA為將展頻碼擴展在頻域上的系統，然而在上行鏈路的頻率選擇性衰減通道環境中，會使得正交碼失去其正交性，因而造成嚴重的多用戶干擾問題(Multi-User Interference, MUI)，近年來有學者提出一種梳狀頻譜的分碼多重存取技術，有效的解決多用戶間干擾的問題，其做法為對每個用戶分組，並將其傳輸資料使用展頻碼擴展在間隔形式的子載波群上，每個子載波只提供給特定用戶使用，因此，在上行鏈路的頻率選擇性衰減通道環境中，訊號到達接收端能夠保有其互相正交的特性。然而，梳狀頻譜分碼多重存取系統所使用的CS碼在頻域上並非等振幅且在頻譜上並沒有達到全散度，亦即某部分頻譜會變為零，這些現象會導致系統效能變差。
稀疏高斯整數完美序列(Sparse Gaussian Integer Perfect Sequence, SGIPS)，為一實部與虛部皆為整數的複數序列，此序列的任意循環位移互相正交，再者，序列所具有的非零值與序列長度無關，另一項特性為，序列的零值數目遠大於非零值數目，藉由這些特性我們使用稀疏高斯整數完美序列作為我們系統的展頻碼，並且提出一項新式梳狀頻譜分碼多重存取系統，由模擬結果顯示，我們所提出的系統位元錯誤率表現比傳統CS-CDMA來的優越，使用正交相移鍵控(QPSK)調變方式，並觀察錯誤率為10-4情況下，我們的系統優於傳統CS-CDMA具有3dB的增益。

Multi-Carrier Code Division Multiple Access (MC-CDMA) is a promising approach to the challenge of providing high data rate wireless communication. It can be interpreted as CDMA with the spreading taking place in the frequency rather than temporal domain. However, due to the frequency selective fading channel for uplink, the orthogonality among various spreading codes is lost and it causes multi-user interference (MUI). Recently, the comb-spectrum (CS) CDMA system without MUI was proposed. One user’s data are spread on an assigned interleaved subcarrier group. Since a subcarrier is only assigned to one user. Therefore, for uplink, the orthogonality among spreading codes can be restored perfectly in the frequency selective fading channel. However, the spectrum of the CS code is not flat and parts of spectrum are zeros which cause the bit error rate (BER) degradation.
A sequence of complex number is called Sparse Gaussian Integer Perfect Sequence (SGIPS) whose real parts and imaginary parts are both integers and whose any cyclic shift is orthogonal to each other. Moreover, the number of nonzero elements of GIPS is independent on the sequence length and much less than the sequence length. In this paper, the SGIPS is utilized as the spreading codes and a novel comb-spectrum code division multiple access system is proposed. From simulation results, the BER of the proposed systems is better than the traditional CS-CDMA systems. For quadrature phase shift keying, the proposed scheme gains about 3dB when BER = 10-4.

論文審定書 i
致謝 ii
中文摘要 iii
Abstract iv
目錄 v
圖次 vii
第一章 導論 1
1.1 研究背景 2
1.2 研究動機 3
1.3 論文架構 4
第二章 CDMA系統介紹 5
2.1 傳統CDMA系統來源與架構 5
2.2 多載波CDMA系統 8
2.3 CP-CDMA系統 13
2.4 CS-CDMA系統 17
第三章 稀疏高斯完美序列 23
3.1 完美序列的演進 23
3.2 高斯完美序列 24
3.3 建構稀疏高斯完美序列 27
第四章 新式梳狀頻譜分碼多重存取系統 30
4.1 發射機架構 30
4.2 接收機架構 32
4.3 系統效能探討 33
第五章 模擬結果與討論 36
5.1 系統錯誤率比較 36
5.2 CFO效能的比較 39
5.3 PAPR效能的比較 41
第六章 結論 43
參考文獻 44
中英對照表 49
縮寫對照表 53

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