Code Division Multiple Access (CDMA) has been regarded as an important part of the third generation wireless communication systems. However, due to its inherent multiple access interference, the performance of CDMA can be severely degraded as the number of subscribers increases. To fully utilize the potential of CDMA systems, multiuser detection can be used. In recent years, multiuser detection has been subject to extensive research and various schemes have been proposed. This thesis will consider the multiuser detection for convolutionally coded CDMA systems. In the conventional interference cancellation schemes, the interference cancellation and the Viterbi decoding are separated. The coded bits are treated as independent bits during interference cancellation. Since the coded bits are...[ Read more ]

Code Division Multiple Access (CDMA) has been regarded as an important part of the third generation wireless communication systems. However, due to its inherent multiple access interference, the performance of CDMA can be severely degraded as the number of subscribers increases. To fully utilize the potential of CDMA systems, multiuser detection can be used. In recent years, multiuser detection has been subject to extensive research and various schemes have been proposed. This thesis will consider the multiuser detection for convolutionally coded CDMA systems. In the conventional interference cancellation schemes, the interference cancellation and the Viterbi decoding are separated. The coded bits are treated as independent bits during interference cancellation. Since the coded bits are, in fact, constrained by the channel coding, it is found that a joint interference cancellation and Viterbi decoding scheme can provide better interference cancellation. This thesis will introduce a new multiuser interference cancellation scheme, which we shall refer to as Joint Parallel Interference Cancellation with Interleaving (JPICI). This scheme combines parallel interference cancellation and memory truncated Viterbi decoding together with interleaving. Numerical results will show that the proposed scheme can significantly improve the system performance. We will further apply the idea of JPICI to an iterative multiuser receiver, which employs the iterative decoding process, and form an JPICI-based iterative multiuser receiver. Simulation results will show that the proposed scheme can improve the system performance compared to the conventional iterative multiuser receiver.