Advanced Algorithms for Multi-Antenna and Multi-Carrier Communication Systems

In recent years, the demands for reliable high rate multimedia and data transmission in wireless communications have increased tremendously. Multi-antenna and multi-carrier communications provide both theoretically attractive and technically practical solutions to satisfy these requirements. This thesis aims at designing and studying advanced algorithms for multi-antenna and multi-carrier communications. In the first part of the thesis, we propose bandwidth-efficient blind spatial signature estimation algorithms based on time-varying user power loading and parallel factor (PARAFAC) analysis. Compared with the earlier approaches, our algorithms do not require any knowledge of the propagation channel and/or sensor array manifold and are applicable to more general class of scenarios. In the second part of the thesis, blind multiuser separation-detection algorithms for directsequence code-division multiple access (DS-CDMA) systems based on the robust fitting of PARAFAC models are proposed. These algorithms provide an improved bandwidth efficiency and robustness against impulsive ambient noise as compared with the earlier approaches. The third part of the thesis is devoted to linear multiuser receivers for joint space-time decoding and interference rejection in multiple-input multiple-output (MIMO) systems that use orthogonal space-time block codes (OSTBCs) and erroneous channel state information (CSI). Using different approaches to model the CSI mismatch, robust linear receivers based on worst-case performance optimization and stochastic programming are proposed, respectively. The proposed receivers greatly enhance the robustness of the communication systems against CSI mismatches. The fourth part of the thesis focuses on the issue of channel fading mitigation for the orthogonal frequency division multiplexing (OFDM) communication systems. In particular, a new linear block precoding technique based on the maximization of the mean cutoff rate is developed. Compared with the earlier precoding techniques, our precoder provides better performance and requires less channel knowledge at the transmitter. Also, adaptive approaches for OFDM-based communication systems are studied in the case when the transmitter has only one bit of CSI per subcarrier obtained through a low-rate feedback. Optimal parameters for these adaptive algorithms are derived. Imperfections of the feedback channel are considered and their impact on the performance of the adaptive techniques is investigated.