Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cressler, John; Committee Member: Gerhardt, Rosario; Committee Member: Ingram, Mary Ann; Committee Member: Papapolymerou, John; Committee Member: Shen, Shyh-Chiang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

In downlink multi-user multiple-input multiple-output (MU-MIMO) systems, different users, even multiple data streams serving one user, might require different quality-of-services (QoS). The transceiver should allocate resources to different users aiming at satisfying their QoS requirements. In order to design the optimal transceiver, channel state information is necessary. In practice, channel state information has to to be estimated, and estimation error is unavoidable. Therefore, robust transceiver design, which takes the channel estimation uncertainty into consideration, is important. For the previous robust transceiver designs, bounded estimation errors or Gaussian estimation errors were assumed. However, if there exists unknown distributed interference, the distribution of the channel estimation error cannot be modeled accurately a priori. Therefore, in this thesis, we investigate the robust transceiver design problem in downlink MU-MIMO system under probabilistic QoS constraints with arbitrary distributed channel estimation error. To tackle the probabilistic QoS constraints under arbitrary distributed channel estimation error, the transceiver design problem is expressed in terms of worst-case probabilistic constraints. Two methods are then proposed to solve the worst-case problem. Firstly, the Chebyshev inequality based method is proposed. After the worst-case probabilistic constraint is approximated by the Chebyshev inequality, an iteration between two convex subproblems is proposed to solve the approximated problem. The convergence of the iterative method is proved, the implementation issues and the computational complexity are discussed. Secondly, in order to solve the worst-case probabilistic constraint more accurately, a novel duality method is proposed. After a series of reformulations based on duality and S-Lemma, the worst-case statistically constrained problem is transformed into a deterministic finite constrained problem, with strong duality guaranteed. The resulting problem is then solved by a convergence-guaranteed iteration between two subproblems. Although one of the subproblems is still nonconvex, it can be solved by a tight semidefinite relaxation (SDR). Simulation results show that, compared to the non-robust method, the QoS requirement is satisfied by both proposed algorithms. Furthermore, among the two proposed methods, the duality method shows a superior performance in transmit power, while the Chebyshev method demonstrates a lower computational complexity. / published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Accurate reproduction of RF transmissions for test and development has been out of reach for some time. The testing of RF equipment, multipath generation and downstream TM processing systems has been done in the past with varying levels of accuracy. In the past the techniques of checking TM equipment worked, but lacked realism that real TM transmissions provide. This paper describes the development of an IF recorder for range TM. We discuss the usage of a recorder with multiple channels, time correlation, channel skew capability, IF over IP capabilities and file management will allow repeatable, realistic testing of TM systems.

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Electrical Engineering / Doctoral / Doctor of Philosophy

No description available.

This thesis presents solutions and studies related to the design of reconfigurable and wideband receiver circuits for system-on-chip (SoC) radiometer front-ends within the millimetre-wave (mm-wave) range. Whereas many of today’s mm-wave front-ends are bulky and costly due to having discrete RF components, single-chip receiver modules could potentially result in a wider use for emerging applications such as wireless communication, short range radar and passive imaging security sensors if realised with adequate performances and at a lower cost. Three main topics are considered in this thesis, monolithic integration of low-loss RF-MEMS (Dicke) switch networks and switched LNAs in MMIC/RFIC foundry processes, designs of SiGe wideband (IF) amplifier and broadband power detectors up to W-band (75-110 GHz). Low-loss and high isolation GaAs and SiGe RF-MEMS switch networks were designed and characterised for the 30-110 GHz range. A GaAs MEMS Dicke switch network has a measured minimum loss of 1 dB and maximum isolation of 19 dB at 70-96 GHz, respectively, making it a potential candidate in Dicke switched radiometer receivers. Furthermore, single-chip 30 GHz and W-band MEMS Dicke switched LNA designs have been realised for the first time in SiGe BiCMOS and GaAs mHEMT processes, respectively. For a targeted 94 GHz passive imaging application two different receiver topologies have been investigated based on direct-detection and direct-conversion (heterodyne) architectures. An optimised detector design fabricated in a 0.13 μm SiGe process achieves a more wideband input matching than earlier silicon W-band detectors and is competitive with reported III-V W-band detectors in terms of a higher responsivity and similar NEP. A SiGe 2-37 GHz high-gain differential (IF) amplifier design achieves a more wideband matching and an order of magnitude higher linearity than a recent single-ended SiGe LNA. The SiGe IF amplifier was integrated on-chip with a power detector in a 5-35 GHz IF section. Their broadband properties compared with other IF amplifier/detector RFICs, make them suitable for W-band down-conversion receivers with a larger pre-detection bandwidth and improved sensitivity. The experimental results successfully demonstrate the feasibility of the SiGe 5-35 GHz IF section for high performance SoC W-band radiometers using a more wideband heterodyne receiver architecture.

Thesis (Ph. D.)--University of New South Wales, 2003.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 77-79). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 127-130). Also available via the Internet.