Abstract
Code Division Multiple Access (CDMA) becomes an important access scheme in recent years because of its several advantages such as higher capacity, anti-jamming. It also has emerged as the basic technique for the realization of the physical layer of third generation (3G) wireless network. However, because of the multipath fading effect, the receiver will receive many replicas of the transmitted signal. These replicas arrive at the receiver with slightly time differences and amplitude decay. This will cause the problem in demodulating received signal. Another source of interference is the multiple access interference (MAI). The multiple access interference is produced when there are multiple users using the same frequency band simultaneously in the CDMA system. In order to suppress the interference, several multiuser detectors have been proposed, including the parallel interference cancellation (PIC) scheme. In this thesis, an algorithm is proposed, which combines the interference cancellation scheme with delay estimation. Some delay estimation methods have been proposed, e.g. delay estimation by ML and AML method. In this thesis, an interference cancellation receiver incorporating the delay estimation and the interference projection method is introduced. Compared to original interference cancellation receiver, we can demodulate the information signal without knowing the power of transmitted signal and the propagation delay. So, the proposed receiver is clearly more fit the practical communication situation. We can observe the parameter simulation to check if the demodulation performance gets better under the improvement of the performance of the delay estimation.