ABSTRACT ZHANG, HONGYUAN. MIMO Communications Systems: Antenna Selection and

ZHANG, HONGYUAN. MIMO Communications Systems: Antenna Selection and Interference Mitigation. (Under the direction of Professor HUAIYU DAI). Multiple-input multiple-output (MIMO) techniques have evolved as one of the key enabling technologies to address the ever-increasing demand for high-speed wireless data access on current and emerging wireless communication networks. In this dissertation, we explore some important problems in point-to-point and multiuser MIMO systems, making certain contributions to both theory and practice of this timely research topic Antenna selection provides a new form of diversity in MIMO systems with low cost and relatively small overhead increase. In the first part of this dissertation, we investigate this technique, concerning (1) associated diversity property analysis in MIMO spatial multiplexing systems with practical coding and decoding schemes; (2) fast algorithm design with good tradeoff between performance and complexity, especially in correlated fading channels; (3) practical implementation in commercial high-throughput wireless local area networks. The first two problems above are addressed via novel and effective geometric tools. These tools are also extended to analyze some open problems in MIMO study, in particular the diversity-multiplexing tradeoff in V-BLAST and SDMA systems employing ordered successive interference cancellation (SIC). While for some systems it is sufficient to consider single-user performance, many others need to address the impairments due to the coexistence of multiple users, especially for cellular systems with universal frequency reuse, which usually undergo severe interference in the downlink. Conventional interference mitigation strategies are typically not effective in high data rate and MIMO scenarios, especially for the downlink. Then in the latter part of this dissertation, we focus on the study of interference mitigation in multiuser multicell MIMO downlink, and investigate the potential of cooperative transmission among adjacent base stations (BS) for effectively combating co-channel interference. Our study starts with a quasi-synchronous model to obtain performance upper bounds, by which we also explore some other advantages like channel rank/conditioning improvement and macro-diversity protection. When considering a more practical channel model, in which signals from different BS’s in the downlink arrive asynchronously at each MS, we propose some novel and effective pre-coding algorithms achieving different levels of tradeoffs between interference mitigation and computational complexity. These algorithms are extended to the scenarios where timing information cannot be perfectly acquired at the cooperative BS’s. In summary, we have tackled some open and interesting problems in MIMO study, in particular, the diversity analysis for MIMO spatial multiplexing systems with antenna selection and practical coding and decoding schemes, and the impact of ordering on the performance of SIC (V-BLAST) receivers. The underlying geometric tools for these analyses may find applications in other relevant fields as well. We have also endeavored to improve the performance of MIMO systems in real operating scenarios and accelerate their employment in future wireless networks, with contributions in fast and practical antenna selection algorithms, and co-channel interference mitigation with base-station cooperation explicitly considering the effect of signal asynchronism and timing errors. MIMO Communications Systems: Antenna Selection and Interference Mitigation by Hongyuan Zhang A dissertation submitted to the Graduate Faculty of North Carolina State University In partial fulfillment of the Requirements for the degree of Doctor of Philosophy Electrical Engineering Raleigh, NC August, 2006