Space-Time Multi-Carrier CDMA Receiver with Enhanced Interference Suppression

A major requirement in future advanced wireless communication systems is high transmission data rate. Unfortunately, multipath fading limits a system's transmission rate. To mitigate this problem, the multi-carrier (MC) transmission scheme is proposed which is robust to frequency selective fading. In this thesis, we consider a new multiple access technique based on a combination of code-division multiple access (CDMA) and MC transmission, called MC CDMA system. The proposed technique can be categorized into two types: one spreads across frequency domain, and the other spreads across time domain. We then propose an adaptive antenna array receiver for the two types of MC CDMA systems. The antenna array receiver provides an extra dimension for space division multiple access (SDMA), which can be used to reduce the interference from other users. This makes it an effective remedy for overcoming the near-far problem and potential solution for increasing the capacity. Furthermore, we propose a scheme of multistage parallel interference cancellation (MPIC) and transmission power control (TPC) methods to reduce the multiple access interference (MAI) from other users. From simulation results, we demonstrate that the proposed space-time receiver outperforms the conventional time-only MC CDMA receiver in the presence of strong MAI.