Power and rate optimization in wireless networks using convex relaxation

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In wireless communication, many resource allocation and management problems are related with optimization problems. In this dissertation, we consider nonconvex power and rate optimization problems in wireless networks such as DS-CDMA, OFDMA, cognitive network using convex relaxation. This dissertation deals with efficient numerical solutions for nonconvex optimization problems for a class of optimization problems in wireless communications systems. By using convex relaxation, we can approximate the solution of nonconvex optimization problems in wireless communication systems. In this dissertation, we considers a distributed utility maximization power control scheme in up-link DS-CDMA systems. Maximizing a utility function is solved by Lagrangian dual decomposition. Numerical result shows that the proposed algorithm achieves around 95% of the optimal utility maximization with a modest computational burden. Also, we considers a sum-rate maximizing power allocation problem under Gaussian cognitive multiple-access channel (MAC) environment, where primary and secondary users may communicate under mutual interference. Formulating the problem as a standard nonconvex quadratically constrained quadratic problem (QCQP) provides a simple method to find a solution using semidefinite relaxation (SDR). Numerical results show that the solution achieves the similar performance of the exhaustive search, within polynomial time. In addition, we considers a novel auction algorithm for subchannel allocation using the difference of throughput among subchannels to allow users to compete through bidding in OFDMA system. The algorithm we proposed can achieve a competitive fair subchannel allocation through auction mechanism. Numerical result shows that the proposed algorithm has the similar performance with sum rate maximization and guarantees fairness by minimizing user``s potential throughput loss.
Han, Young-Namresearcher한영남researcher
한국정보통신대학교 : 공학부,
Issue Date
393138/225023 / 020035337

학위논문(박사) - 한국정보통신대학교 : 공학부, 2009.2, [ viii, 90 p. ]


볼록 유연화; 최적화; 전력 전송률 제어; Optimization; Power and Rate Control; Convex Relaxation

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School of Engineering-Theses_Ph.D(공학부 박사논문)
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