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In this paper, we present a sparse spatial spectrum estimation method which provides superresolution direction-finding performance and accurate signal power estimation simultaneously. Compressive sensing ideas are used in conjunction with a postulated model for the covariance matrix of the array output instead of the output itself. Following a preliminary analysis of the method and a geometric interpretation...
Recently, a technique named `blind decorrelation' was proposed by which we can blindly diagonalize correlation matrices of isotropic noises observed by particular crystal-shape sensor arrays. This technique enables us to estimate the power of unknown target signals, which may improve the performance of inverse filters such as the Wiener filter. It was clarified that several classes of crystal-shape...
Real-time acquisition and tracking of sniper bullet trajectory is important in various military operations. While the majority of the existing work on gunshot is based on acoustic sensors, such technologies cannot provide timely response because sound propagates much slower than a bullet does. In this paper, we propose the use of an array processing framework that uses multi-frequency continuous-wave...
We propose a new method for offline calibration of a sensor array with respect to position, gain and phase errors of the sensor elements. We model the effect of position errors explicitly, such that they can be corrected parametrically using a least-squares formulation. This is equivalent to the already existing maximum-likelihood position estimator, but does not require a minimal number of calibration...
We address the problem of recovering a continuous-time (space) signal from several blurred and noisy sampled versions of it, a scenario commonly encountered in super-resolution (SR) and array-processing. We show that discretization, a key step in many SR algorithms, inevitably leads to inaccurate modeling. Instead, we treat the problem entirely in the continuous domain by modeling the signal as a...
A modified least squares adaptive steered beamformer that aims to eliminate the excess weight noise induced by a strong desired signal is proposed. It functions by alternating projections of the array data onto a subspace orthogonal to both the desired signal and interferences. The desired signal can be finally recovered, while retaining interference cancellation, by the use of a commutation property...
In this paper, a Multiple Input Multiple Output (MIMO) monostatic sonar scheme that can deal with multiple targets is presented, where orthogonal waveforms are transmitted simultaneously. Meanwhile the Capon estimator for this sonar system is derived in detail. And the performance of the MIMO sonar is analyzed via experiments in an anechoic water tank, as compared with its phased-array counterpart...
In this paper, half-and full-duplex relay processing matrices and source-destination beamforming vectors are jointly optimized based on a minimum mean-square-error (MMSE) formulation under inequality constraints on the transmit power of the source and the relays. Through BER simulations, we illustrate that the full-duplex method performs better than the half-duplex method in various signal-to-noise...
Source localization is based on the spectral matrix algebraic properties. Propagator, and Ermolaev-Gershman (EG) noneigenvector algorithms exhibit a low computational load. Propagator is based on the spectral matrix partitioning. EG algorithm obtains an approximation of noise subspace using an adjustable power parameter of the spectral matrix and choosing a threshold value. These algorithms are efficient...
Through-the-wall radar imaging (TWRI) is a versatile application which demands the collection and processing a large number of data, both along the spatial and frequency dimensions. Compressive sensing (CS) is an attractive approach for reducing the number of data samples, without a significant degradation of the original image that is generated using the full array aperture and frequency band. In...
This paper proposes a robust reduced-rank scheme and algorithms for adaptive beamforming based on joint iterative optimization (JIO) of adaptive filters. The scheme provides an efficient way to deal with filters with large number of elements. It consists of a bank of full-rank adaptive filters that forms a transformation matrix and an adaptive reduced-rank filter that operates at the output of the...
A novel approach for broadband beamforming in the presence of multi-path signals is proposed based on a frequency invariant transformation. In this approach, the received array signals are first processed by a frequency invariant beamforming network and then a traditional narrowband adaptive beamformer is applied to its output. It is shown that with the proposed structure, the cancellation of the...
A least squares approach to the design of frequency invariant beamformers (FIBs) in subbands is proposed. In this approach, the desired fullband beam response is first expressed as a function of the subband beamformer coefficients, and then a closed form solution is obtained based on a constrained least squares formulation. Two design examples are provided, with one based on a uniform linear array...
The downlink minimum bit error rate (MBER) transmit beamforming is directly derived based on the uplink MBER receive beamforming for time division duplex (TDD) space-division multiple-access (SDMA) multiple-input multiple-output systems, where the base station (BS) is equipped with multiple antennas to support multiple single-antenna mobile terminals (MTs). It is shown that the relationship between...
The ability to detect more or less accurately the Direction Of Arrival (DOA) of an emitting source depends on the actual DOA. It makes sense to study the DOA estimation error in the direction where it is the lowest possible, and in a neighborhood of this direction that we refer to as the aperture. A performance measure is derived from the Cramer-Rao bound (CRB) and is evaluated relatively to the aperture...
When sampling only a coarse set of azimuth and elevation angles for a 2-D array, the resulting angle of arrival errors often lead to target nulling in adaptive beamformers. Methods currently used to alleviate these errors often prevent target nulling at the expense of source localisation. In this paper, we show how the robust Capon beamformer, exploiting a flat ellipsoidal uncertainty set of the array...
Block diagonalization (BD) is a linear precoding technique to eliminate inter-user interference (IUI) in multiple-input multiple-output (MIMO) multiuser wireless communication systems. In this paper, a limited feedback-based BD algorithm with Grassmannian codebook is studied. When the number of bits available for feeding back channel state information (CSI) from multiple terminals to the base station...
We propose a new architecture, the compressive sampling (CS) array, for array based applications, by exploiting compressive sampling in the spatial domain. With random projections (or selections) of the array elements, we can transform a large size array into a small size array. We also propose two approaches of direction-of-arrival (DoA) estimation using our CS array, I. (joint) CS recovery, and...
Direction finding with coherent source waveforms is of practical importance in radar array processing, e.g. for specular multipath propagation. Furthermore, high-resolution methods require an accurately calibrated array. In this paper, we combine local and global manifold correction with maximum likelihood direction finding using the method of alternating projections. We use simulations to study the...
A novel robust beamformer is proposed to suppress the coherent interferences while maintaining a distortionless response for the desired signal with direction-of-arrival (DOA) estimation errors. By dividing the received array data vector into two sub-vectors and subtracting one sub-vector from the other, a new data vector is obtained, based on which a set of constraints is formed for calculating the...
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