Fast and Accurate Angle-of-arrival Estimation in an Analog Array

Qin, Chuen

Fast and Accurate Angle-of-arrival Estimation in an Analog Array

Qin, Chuen

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Publication Type:: Thesis
Issue Date:: 2020

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Field	Value	Language
dc.contributor.author	Qin, Chuen
dc.date.accessioned	2022-01-10T00:24:28Z
dc.date.available	2022-01-10T00:24:28Z
dc.date.issued	2020
dc.identifier.uri	http://hdl.handle.net/10453/152854
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Today, millimeter wave (mmWave) communications are becoming core technologies in the fifth-generation (5G) cellular communications. Angle of arrival (AoA) estimation is a critical and challenging problem for beamforming and channel estimation in mmWave systems. This thesis proposes several novel AoA estimation techniques for analog arrays. Three major techniques are presented in this thesis. In the first technique, a virtual-subarray based recursive AoA estimation scheme is proposed. The scheme obtains an exact AoA estimate from every two measurements and recursively improves the performance by updating beamforming weights. In this scheme, the single analog array is first divided into two virtual subarrays, two beamforming vectors are then applied to obtain two measurements, and a simple algorithm is finally applied to perform the AoA estimation from the two measurements. The “soft” probability function for the estimate is introduced to represent the likelihood and probability of the AoA estimation in a given direction. In the second technique, the basic virtual-subarray AoA (ViSA) estimation scheme is extended by considering more diverse subarray constructions and more than two measurements. Different subarray constructions are firstly proposed, and it is shown that they can lead to different accuracy of estimation under the same two-measurements estimation technique. Closed-form expressions for the statistics of the estimation error are provided. Based on the basic estimator, two methods are developed to combine multiple pairs of measurements, when they are obtained via sequential and multi-resolution scanning, respectively. Near-optimal estimators are derived for both methods, employing the maximum likelihood principle. In the third technique, AoA estimation based on Gaussian approximation is developed. The first two proposed techniques above use the phase and magnitude of the received signals for AoA estimation, and hence they require some specially designed training sequences. The third technique uses only the power of the received signals and hence can relax the training sequence design. The basic idea is to use a Gaussian function to approximate the array response, which is a sinc function for a uniform linear array in the ideal case. Although techniques based on the power difference between two scans have been developed using the original sinc function, they are very inflexible to use. Using the approximated Gaussian function, it is shown that the beam can be flexibly pointed to any direction and the AoA estimation can be obtained using a simple algorithm.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/152854/2/02whole.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.title	Fast and Accurate Angle-of-arrival Estimation in an Analog Array	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Today, millimeter wave (mmWave) communications are becoming core technologies in the fifth-generation (5G) cellular communications. Angle of arrival (AoA) estimation is a critical and challenging problem for beamforming and channel estimation in mmWave systems. This thesis proposes several novel AoA estimation techniques for analog arrays. Three major techniques are presented in this thesis. In the first technique, a virtual-subarray based recursive AoA estimation scheme is proposed. The scheme obtains an exact AoA estimate from every two measurements and recursively improves the performance by updating beamforming weights. In this scheme, the single analog array is first divided into two virtual subarrays, two beamforming vectors are then applied to obtain two measurements, and a simple algorithm is finally applied to perform the AoA estimation from the two measurements. The “soft” probability function for the estimate is introduced to represent the likelihood and probability of the AoA estimation in a given direction. In the second technique, the basic virtual-subarray AoA (ViSA) estimation scheme is extended by considering more diverse subarray constructions and more than two measurements. Different subarray constructions are firstly proposed, and it is shown that they can lead to different accuracy of estimation under the same two-measurements estimation technique. Closed-form expressions for the statistics of the estimation error are provided. Based on the basic estimator, two methods are developed to combine multiple pairs of measurements, when they are obtained via sequential and multi-resolution scanning, respectively. Near-optimal estimators are derived for both methods, employing the maximum likelihood principle. In the third technique, AoA estimation based on Gaussian approximation is developed. The first two proposed techniques above use the phase and magnitude of the received signals for AoA estimation, and hence they require some specially designed training sequences. The third technique uses only the power of the received signals and hence can relax the training sequence design. The basic idea is to use a Gaussian function to approximate the array response, which is a sinc function for a uniform linear array in the ideal case. Although techniques based on the power difference between two scans have been developed using the original sinc function, they are very inflexible to use. Using the approximated Gaussian function, it is shown that the beam can be flexibly pointed to any direction and the AoA estimation can be obtained using a simple algorithm.

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