Abstract
We explore the estimation of a two-dimensional (2D) nonsymmetric coherently distributed (CD) source using L-shaped arrays. Compared with a symmetric source, the modeling and estimation of a nonsymmetric source are more practical. A nonsymmetric CD source is established through modeling the deterministic angular signal distribution function as a summation of Gaussian probability density functions. Parameter estimation of the nonsymmetric distributed source is proposed under an expectation maximization (EM) framework. The proposed EM iterative calculation contains three steps in each cycle. Firstly, the nominal azimuth angles and nominal elevation angles of Gaussian components in the nonsymmetric source are obtained from the relationship of rotational invariance matrices. Then, angular spreads can be solved through one-dimensional (1D) searching based on nominal angles. Finally, the powers of Gaussian components are obtained by solving least-squares estimators. Simulations are conducted to verify the effectiveness of the nonsymmetric CD model and estimation technique.
Highlights
Point source models are commonly used in applications such as wireless communications, radar and sonar systems, distributed source models which have considered multipath propagation and the surface features of targets tend to perform better
Through modeling the nonsymmetric deterministic angular signal distribution function by Gaussian mixture, we have presented a parameter estimation method under an expectation maximization (EM) framework based on L-shaped arrays
We have considered the problem of estimating a nonsymmetric 2D coherently distributed (CD) source under L-shaped arrays
Summary
Point source models are commonly used in applications such as wireless communications, radar and sonar systems, distributed source models which have considered multipath propagation and the surface features of targets tend to perform better. Position localization estimators based on distributed source models have proved to be more precise in multipath scenarios compared with point source models. With information of surface features, the distributed source models have potential application for high-resolution underwater acoustical imaging. Sources may be classified into coherently and incoherently distributed sources [1]. A coherently distributed (CD) source is defined as the signal components arriving from different angles within the range of extension that are coherent. For an incoherently distributed (ID) source, these components are uncorrelated. The modeling and estimation of a CD source are considered
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