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UBC Theses and Dissertations

Interference mitigation and alignment for interference-limited communication systems Rahman, Md. Jahidur


With limited availability of the communication spectrum and ever-increasing demands for high-data-rate services, it is natural to reuse the same time-frequency resource to the greatest degree possible. Depending on the nature of transmission and reception of the users, this leads to different instances of interference, e.g., inter-user interference in an interference network and self-interference in a Full-Duplex (FD) transmission. With a goal to mitigate such interference, in this thesis we investigate emerging interference-limited communication systems, such as FD, Device-to-Device (D2D), and Power Line Communication (PLC). To this end, we propose advanced solutions, namely self-interference mitigation and Interference Alignment (IA). With an objective to reduce the power consumption, we study transceiver design for FD multi-cell Multi-Input Multi-Output (MIMO) systems with guaranteed Quality of Service (QoS). Considering realistic self-interference models and robustness against Channel State Information (CSI) uncertainty, our numerical results reveal transmission scenarios and design parameters for which replacing half-duplex with FD systems is beneficial in terms of power minimization. If the system is not power constrained, however, a natural objective is to optimize the total throughput given a power budget. Nonetheless, throughput maximization underserves the users that experience poor channels, which leads to QoS unfairness. Therefore, we propose a fair transceiver design for FD multi-cell MIMO systems, which can be implemented in a distributed manner. We further extend our design to enforce robustness against CSI uncertainty. As a second contribution within this design theme, the concept of robust fair transceiver design is also extended for D2D communications, where unlike the self-interference in FD transmission, the users suffer from strong inter-user interference. Recognizing that simultaneous multiple connections in PLC contribute to (interuser) interference-limited communication, we introduce IA techniques for PLC networks, for which the results confirm a significant sum-rate improvement. To overcome the implementation burden of CSI availability for IA techniques, we then study Blind Interference Alignment (BIA) for PLC X-network, and show that the characteristics of the PLC channel thwart simple implementation of this technique via impedance modulation. We therefore resort to a transmission scheme with multiple receiving ports, which can achieve the maximum multiplexing gain for this network.

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