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Title: Application of frequency invariant constraints to wideband beamforming
Author: Zhao, Yong
ISNI:       0000 0004 2720 7116
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
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Different from the narrowband beamformer with a single frequency response, there exists a group of frequency responses for the wideband case since its received signal has significant frequency content. Thus it is crucial to find an effective way to achieve good frequency response consistency to the desired wideband signal. Otherwise there would be a lowpass filtering effect, causing distortion to some frequency components of it. In this thesis, we will focus on the topic of frequency invariance in the design of wideband beamformers. Firstly our effort comes to the design of a special class of fixed wideband beamformers called frequency invariant beamformer (FIB), which can form beams pointing to the signal of interest with a constant beamwidth. Secondly, in order to reduce high computational complexity in the case of large dimensioned wideband array, we study the subband design problem for fixed wideband beamformers, with an emphasis on the design of FIBs. Next we explore the idea of frequency invariance in the design of adaptive wideband beamformers, aiming t improve efficiency in degree of freedom (DOF) allocation and enhance robustness of the beamforming system. Firstly, we develop a novel linearly constrained beamformer with an improved output signal-to-interference-plus-noise ration (SINR) compared to traditional methods. In addition, two novel robust wideband beamformers against DOA estimation errors are also proposed. Compared with the original robust methods, a more efficient and effective control over the beamformer's response at the look direction region is achieved with improved overall performance. Finally, in order to extend the robustness to the general case with arbitrary array manifold errors, a novel robust wideband beamformer is proposed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available