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It is known that computational loads of the propagator method (PM) can be significantly smaller, e.g., one or two order, than those of MUSIC and ESPRIT because the PM does not require any eigenvalue decomposition (EVD) of the cross-correlation matrix and singular value decomposition (SVD) of the received data. However, the PM of the parallel shape array has nonnegligible drawbacks such as 1) requirement of pair matching between the 2-D azimuth and elevation angle estimation which is an exhaustive search and 2) estimation failure problems when elevation angles are between 70[degrees] and 90[degrees]. The purpose of this paper is to show a way to remove these problems in the PM without additional computational loads. This paper will employ one or two L-shape arrays because the parallel shape used in the PM may cause the aforesaid problems. Simulation results verify that the PM with one or two L-shape configurations can remove these problems and improve the performance of the PM significantly, e.g., almost 5 dB in signal to noise ratio for the parameters used in this paper. Index Terms--Antenna array, direction-of-arrival angle (DOA) estimation, propagator method (PM), Smart antenna.

In this paper, we present an algorithm to estimate the direction of the arrival angles (DOAs) from noncoherent one-dimensional (1-D) signal sources such as binary phase shift keying (BPSK) and M-ary amplitude shift keying (MASK). The proposed algorithm can provide a more precise DOA estimation and can detect more signals than well-known classical subspace-methods MUSIC and ESPRIT for the 1-D signals. The complexity is the same as that of ESPRIT since the proposed algorithm uses the same array geometry and subarray processing that ESPRIT does. The main differences between the proposed algorithm and the ESPRIT algorithm are as follows: 1) the number of overlapping array elements between two subarrays is equal to M in the proposed algorithm, while in ESPRIT the maximum number of overlapping elements is M--1, where M denotes the total number of array elements, and 2) the proposed algorithm employs the conjugate of rotation matrix (CRM) [PHI]* while ESPRIT uses [PHI] with no conjugate for the second subarray geometry. Index Terms--Antenna arrays, array signal processing, direction-of-arrival angle (DOA) estimation, ESPRIT, MUSIC.

In this paper, we addressed the problem of estimating the two-dimensional (2D) Direction of Arrival (DOA) elevation and azimuth angles for multiple sources. The proposed method employs Propagator Method (PM) in conjunction with parallel factor (PARAFAC) model using a new antenna array configuration. The proposed method overcomes two main drawbacks in the existing 2D DOA schemes: use of high computation eigenvalue decomposition (EVD) or singular value decomposition (SVD), and complex pair-matching methods for elevation and azimuth angles in case of multiple sources. Therefore, significant reduction in computational load and complexity is achieved. Computer simulations demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) Direction-of-Arrivals (DOA) estimation for elevation and azimuth angles assuming noncoherent, mixture of coherent and noncoherent, and coherent sources using extended three parallel uniform linear arrays (ULAs) is proposed. Most of the existing schemes have drawbacks in estimating 2D DOA for multiple narrowband incident sources as follows: use of large number of snapshots, estimation failure problem for elevation and azimuth angles in the range of typical mobile communication, and estimation of coherent sources. Moreover, the DOA estimation for multiple sources requires complex pair-matching methods. The algorithm proposed in this paper is based on first-order data matrix to overcome these problems. The main contributions of the proposed method are as follows: (1) it avoids estimation failure problem using a new antenna configuration and estimates elevation and azimuth angles for coherent sources; (2) it reduces the estimation complexity by constructing Toeplitz data matrices, which are based on a single or few snapshots; (3) it derives parallel factor (PARAFAC) model to avoid pair-matching problems between multiple sources. Simulation results demonstrate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We addressed the problem of two-dimensional (2D) direction-of-arrival (DOA) elevation and azimuth angles estimation for multiple uncorrelated signals using L-shaped antenna array configuration. The key points of the proposed method are the following: (1) it obtains azimuth and elevation angles through construction of three cross-correlation matrices from the collected data of the received signals; this implies that the noise reduces significantly in the reconstructed data matrices; (2) it derives a parallel factor analysis (PARAFAC) model and applies trilinear least squares method to avoid pair matching problem between 2D DOA azimuth and elevation angles for multiple sources; (3) it does not require spectral peak searching; and (4) it has better 2D DOA estimation compared with signal parameters via rotational invariance technique and fourth-order signal parameters via rotational invariance technique. Simulation results demonstrate the estimation accuracy and the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Two dimensional (2-D) direction-of-arrival (DOA) elevation and azimuth angles estimation for uncorrelated sources using L-shaped array is presented in this letter. The key points of the proposed method are the following: 1) The proposed scheme obtains the cross-correlation matrix between the subarrays data to construct a data matrix with free noise; 2) employ only linear operations on the data matrix hence low computational complexity; 3) it has better angle estimation with no failure in practical mobile elevation angle range (70°-90°). Simulation results demonstrate that the proposed method has better performance and lower computational complexity compared to the existing schemes. [ABSTRACT FROM PUBLISHER]

This paper presents a novel method for the two-dimensional direction of arrival (DOA) estimation based on QR decomposition. A configuration with two uniform linear antenna arrays (ULAs) is employed for the joint estimation of elevation (θ) and azimuth (φ) angles. Q data matrix will estimate the azimuth angle while R data matrix will estimate the elevation angle. The proposed method utilizes only a single snapshot of the received data and constructs a Toeplitz data matrix. This reduces the computational complexity of the proposed method to O((N + 1)²) from O(N³) for SVD based methods. The structure of the data matrix also favors the 2D DOA estimation for both coherent and non-coherent source signals. Simulation results are presented, and performance of the proposed method is compared with the Matrix Pencil method for 2D DOA estimation of multiple incident source signals. [ABSTRACT FROM AUTHOR]

In this paper, we present five different approaches to estimate direction of arrival (DOA) of multiple incident RF sources. The proposed methods are based on extracting the signal and noise subspaces from the Q matrix, R matrix, or both Q and R matrices of the QR decomposed received data matrix. The angle of the signal arrival is extracted from the signal subspace by using similar techniques as employed by MUSIC and ESPRIT methods. The simulation results are shown which verify accurate DOA estimates for both single and two sources. In addition, an experimental verification of the proposed methods is also presented. The methods are implemented in LabVIEW software and a prototype is built using National Instruments (NI) hardware. Furthermore, the details of experimental procedures are presented which includes interfacing the uniform linear array (ULA) of antennas with the NI-PXI platform, phase difference calibration between the RF receivers, and selection of transmitter and receiver parameters. The experimental results are shown for a single and two RF sources lying at arbitrary angles from the array reference, which verify the successful real-time implement-ability of the proposed DOA estimation methods. [ABSTRACT FROM AUTHOR]

In this letter, we addressed the problem of estimating the time delay and the frequencies of noisy sinusoidal signals received at two spatially separated sensors. We employ the Propagator Method (PM) in conjunction with the well-known MUSIC/ root-MUSIC algorithm; the proposed method would generate estimates of the unknown parameters. Such estimates are based on the observation and/or covariance matrices. Moreover, the PM does not require the eigenvalue decomposition (EVD) or singular value decomposition (SVD) of the cross-spectral matrix (CSM) of received signals; therefore, a significant improvement in computational load is achieved. Computer simulations are also included demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A response by Nizar Tayem and Hyuck M. Kwon to a letter to the editor about their article "L-Shape Two-Dimensional Arrival Angle Estimation With Propagator Method" that was published in the previous issue is presented.

In this paper, we present an algorithm to estimate the direction of the arrival angles (DOAs) from noncoherent one-dimensional (1-D) signal sources such as binary phase shift keying (BPSK) and M-ary amplitude shift keying (MASK) The proposed algorithm can provide a more precise DOA estimation and can detect more signals than we D-known classical subspace.methods MUSIC and ESPRIT for the 1-D signals. The complexity is the same as that of ESPRIT since the proposed algorithm uses the same array geometry and subarray processing that ESPRIT does. The main differences between the proposed algorithm and the ESPRIT algorithm are as follows: 1) the number of overlapping array elements between two subarrays is equal to M in the proposed algorithm, while in ESPRIT the maximum number of overlapping elements is M - 1, where M denotes the total number of array elements, and 2) the proposed algorithm employs the conjugate of rotation matrix (CRM) V while ESPRIT uses 1 with no conjugate for the second subarray geometry. [ABSTRACT FROM AUTHOR]

A response by Jean-Pierre Delmas to a letter to the editor about the article on Conjugate ESPRIT is presented.