本篇論文使用了M-ary 正交調變的DS-CDMA系統，模擬結果顯示出M-ary正交調變可以降低多人使用干擾效應 (MAI)。由於系統通道模型為AWGN與Rayleigh fading，所以使用了RAKE接收架構與Channel Estimation來抵抗多路徑通道的衰落的效應。 接著我們分析與模擬不同的干擾消除機制(IC)去消除MAI的干擾影響，在探討這些干擾消除機制時，將可瞭解平行干擾消除機制(PIC)與串聯干擾消除機制(SIC)的優缺點。同時我們也考慮了混合干擾消除機制(HIC)，因為它能夠改善PIC與SIC的缺點。 論文中的模擬結果顯示，使用了以上所述的技術後，可以得到較好的效能結果。 In this thesis, we use the M-ary orthogonal modulation in DS/CDMA system. The results show the Multiple Access Interference (MAI) is reduced due to M-ary orthogonal modulation compared with the case without orthogonal modulation. The system simulation models include AWGN and Rayleigh fading channel. So the rake structure and channel estimation technique can be used to combat multipath fading. Then we analyze and simulate different kinds of interference cancellation (IC) schemes to overcome MAI in DS/CDMA. Among ICs, we can see the advantage and disadvantage of traditional parallel interference cancellation (PIC) and serial interference cancellation (SIC). A hybrid interference cancellation by combining SIC and PIC is also considered. It can improves the disadvantage of PIC and SIC. The simulation results show that the performance enhancement can be achieved through M-ary orthogonal modulation, channel estimation and Improved IC technique.
