Network interference management for security and efficiency
Abstract
The first part of the dissertation investigates secure communication with cooperative jamming. For artificial noise (AN) and noise forwarding (NF) schemes, the design of the optimal covariance matrices of the transmit signals that maximize the secrecy rate is addressed. It is shown that the original nonconvex design problems can be transformed into a sequence of convex optimization problems to reduce the complexity of the problems. The robust system design under imperfect channel state information is also considered. The properties of the optimal covariance matrices are investigated. In many cases, it is shown that beamforming is optimal, and the solutions can further be derived analytically. In addition, due to poor channel condition or inaccurate channel estimation, for the AN scheme, a positive secrecy rate may not be achieved or the secrecy rate may not be improved. Under various scenarios, necessary and sufficient conditions for the AN scheme to improve the secrecy rate or achieve a positive secrecy rate are studied. The second part of the dissertation studies downlink interference coordination for indoor small cell networks. The goal is to improve the performance of users at the edges of cells while maintaining the average performance of the system. A scalable, cluster-based fractional frequency reuse (FFR) scheme is proposed to improve the performance of cell-edge users. Multiple cells are organized into clusters that are chosen based on interference patterns. The FFR pattern is generated in a hierarchical manner to eliminate heavy intra-cluster interference and avoid severe inter-cluster interference aggregation on frequency bands with high frequency reuse factor values. Simulations validate the effectiveness of the proposed scheme to improve the cell-edge user throughput, and implementation requirements are also identified.
Degree
Ph.D.
Advisors
Lehnert, Purdue University.
Subject Area
Electrical engineering
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