The problem of 2D angle estimation (azimuth and elevation) of multiple plane waves incident on a uniform circular array (UCA) of antennas is considered. Two eigenstructure-based estimation algorithms that operate in beamspace and employ phase mode excitation-based beamformers have been developed. The first, UCA-RB-MUSIC, is a beamspace version of MUSIC that offers numerous advantages over element space operation, including reduced computation, as subspace estimates are obtained via real-valued eigendecompositions, enhanced performance in correlated source scenarios due to the attendant forward-backward averaging effect, and the applicability of Root-MUSIC. The second, UCA-ESPRIT, represents a significant advance in the area of 2D angle estimation. It is a novel closed-form algorithm that provides automatically paired source azimuth and elevation estimates. With UCA-ESPRIT, the eigenvalues of a matrix have the form /spl mu//sub i/=sin /spl theta//sub i/e/sup j/spl phi/(i/), where /spl theta//sub i/ and /spl phi//sub i/ are the elevation and azimuth angles, respectively. Expensive search procedures being thus avoided, UCA-ESPRIT is superior to existing 2D angle estimation algorithms with respect to computational complexity. Finally, asymptotic expressions for the variances of the element space MUSIC and UCA-RB-MUSIC estimators for the 2D scenario have been derived. Results of simulations that compare UCA-RB-MUSIC and UCA-ESPRIT and also validate the theoretical performance expressions are presented. >

Eigenstructure techniques for 2-D angle estimation with uniform circular arrays

Wireless localization techniques are an area that has attracted interest from both industry and academia, with self-localization capability providing a highly desirable characteristic of wireless sensor networks. Localization Algorithms and Strategies for Wireless Sensor Networks encompasses the significant and fast growing area of wireless localization techniques. This book provides comprehensive and up-to-date coverage of topics and fundamental theories underpinning measurement techniques and localization algorithms. A useful compilation for academicians, researchers, and practitioners, this Premier Reference Source contains relevant references and the latest studies emerging out of the wireless sensor network field.

Localization Algorithms and Strategies for Wireless Sensor Networks: Monitoring and Surveillance Techniques for Target Tracking

The problem of estimating the direction of arrivals (DOA) of narrowband sources impinging on a uniform circular array is considered. We present a method that uses as input the values of a small number of uniformly spaced beams and apply a model-fitting approach taking into account the statistical properties of the beams. The approach, which is called the "global matched filter" fits simultaneously to the observations all the elements needed to explain them. It chooses, among all the representations satisfying a constraint with a sensible physical interpretation, the one with minimal energy. The method drastically improves upon the conventional beamformer and has a performance comparable with the best high-resolution (HR) techniques. It further applies when the number of sources exceeds the number of sensors: a situation that cannot be handled by standard HR techniques.

On the application of the global matched filter to DOA estimation with uniform circular arrays

We present a preprocessing technique that in conjunction with spatial smoothing circumvents the difficulty of direction-of-arrival estimation of coherent signals in the case of uniform circular arrays. Special consideration is given to problems arising in practice, such as mutual coupling and array geometry imperfections. Simulation results illustrating the performance of this scheme in conjunction with the MUSIC method are included. >

Direction finding of coherent signals via spatial smoothing for uniform circular arrays

From the Publisher:
Sensors arrays are used in diverse applications across a broadrange of disciplines. Regardless of the application, however, the tools of sensor array signal processing remain the same. Furthermore, whether your interest is in acoustic, seismic, mechanical, or electromagnetic wavefields, they all have a common mathematical framework. Mastering this framework and those tools lays a strong foundation for more specialized study and research.

Sensor Array Signal Processing helps build that foundation. It unravels the underlying principles of the subject without reference to any particular application. Instead, the author focuses on the common threads that exist in wavefield analysis. After introducing the basic equations governing different wavefields, the treatment includes topics from simple beamformation, spatial filtering, and high resolution DOA estimation to imaging and reflector mapping.
It studies different types of sensor configurations, but focuses on the uniform linear and circular arrays-the most useful configurations for understanding array systems in practice.

Unique in its approach, depth, and quantitative focus, Sensor Array Signal Processing offers the ideal starting point and an outstanding reference for those working or interested in medical imaging, astronomy, radar, communications, sonar, seismology-any field that studies propagating wavefields.
Its clear exposition, numerical examples, exercises, and wide applicability impart a broad picture of array signal processing unmatched by any other text on the market.

Sensor Array Signal Processing

The problem of estimating the directions of arrival of narrowband plane waves impinging on a uniform circular array with M identical sensors uniformly distributed around a circle is considered. Specifically, the authors study a transformed data sequence that is equal to a reordering of the inverse discrete Fourier transform sequence corresponding to the outputs of a circular array with M elements uniformly distributed around the array circumference. It is shown that the transformed sequence may be processed using a ROOT MUSIC based approach to estimate the elevations and azimuths of the observed sources. Any root estimated via ROOT MUSIC which is on or close to the unit circle indicates the presence of a source at the elevation under consideration and an azimuth equal to the phase of the root. Experimental results are provided to demonstrate the advantages of processing the transformed data. >

W. Hong

Papers

On the application of uniform linear array bearing estimation techniques to uniform circular arrays