在分碼多工存取(CDMA)行動通訊系統中，除了比傳統的分頻多工存取(FDMA)和分時多工存取(TDMA)多了分碼傳輸的技術，在干擾上也增添了多重存取干擾(MAI)，因此在解調時需要考量消除干擾的技術。本篇論文以直接序列(direct sequence)展頻技術調變之分碼多工存取系統，再利用多載子傳輸搭配正交分頻多工(OFDM)來降低頻率選擇性衰減通道(frequency-selective fading channel)對系統的影響，並使用續列干擾消除偵測器（SIC），來減少干擾，進而提高系統
的效能。
為了能有效利用續列干擾消除偵測器，還必須知道每個使用者的傳輸振幅，但是在傳輸訊號的過程當中，受到多重路徑影響的關係，使接收端接收訊號時會收到不同時間延遲、不同通道振幅衰減的加成訊號，這會使得估測振幅的工作變的困難。因此本文提出一個能同時估測出通道和傳輸者振幅的方法，並將所估測到的資料，配合原來續列干擾消除偵測器，並利用Maximum Ratio Combining (MRC)或Equal Gain Combining (EGC)的技術來還原訊號，以得到一個更合乎實
際狀況之接收器。

Because the Code Division Multiple Access (CDMA) mobile communication system, has the code division scheme in comparison with traditional frequency division multiple access (FDMA) and time division multiple access (TDMA), therefore, the system will have more serious multiple access interference (MAI). In order to cancel the interference, a interference cancellation scheme in demodulating is required. In this thesis the CDMA systems with direct-sequence (DS) spread spectrum modulation is discussed and the multi-carrier transmission and the orthogonal frequency division multiplexing (OFDM) to against the frequency-selective fading channel are used. In the receiver, the successive interference cancellation (SIC) scheme is used to reduce the interference, and then improves the performance of
receiver.
By using the SIC scheme efficiently, the transmitting amplitude for every user must be known. However, the receiver will receive many replicas of the transmitted signal with slightly time difference and amplitude decay because of the multi-path fading during signal transmission. This may cause the difficulty in estimating the amplitude. A method which can estimate the amplitude and channel gain simultaneously is introduced in this thesis. We can use this information together with the SIC scheme and the technique of maximum ratio combining (MRC) or equal gain combining (EGC) to obtain a more practical communication receiver.

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