A robust direction-of-arrival estimation method for impulsive noise environments

In the context of two-dimensional (2-D) direction of arrival (DOA) estimation in impulsive noise environments, this paper extends the coprime array to a crossed V-shaped distributed structure and proposes a novel exponential weighted adaptive generalized covariance (EWAGC) based on the study of impulsive noise characteristics. Building on this, a redundant averaging dual-scale EWAGC-ESPRIT algorithm is introduced, which can adaptively adjust the suppression level of impulsive noise with varying intensities, enhancing the robustness of the estimation. Simulation results validate the superior performance of the proposed method in solving the 2-D DOA estimation problem in impulsive noise environments.

Direction of arrival (DOA) estimation has emerged as a promising technology for many military and civilian applications, such as radio astronomy and wireless communications. However, it remains very challenging to estimate DOA for distributed sources within impulsive noise environments. As is widely known, the utilization of the subspace technology in array signal processing can enable high-resolution DOA estimation. In many instances, most of these algorithms assume that the noise is Gaussian. Considering the impulsive noise environments, the derivative of the error function is derived as the iteratively weighted factor in the objective function of low-rank decomposition. Two iterative algorithms are proposed to compute the signal subspace to implement DOA estimation for coherently distributed sources. To further improve the DOA estimation accuracy and increase the number of estimated sources, the virtual data samples are reconstructed from the extended co-prime array. Simulation results confirm that the two proposed impulsive noise suppression algorithms provide better performance than the existing algorithms. The virtual data samples that are reconstructed from the extended co-prime array can be utilized as the effective inputs for subspace-like algorithms.

To solve the problem that the traditional ambiguity function cannot well reflect the time-frequency distribution characteristics of linear frequency modulated (LFM) signals due to the presence of impulsive noise, two robust ambiguity functions: correntropy-based ambiguity function (CRAF) and fractional lower order correntropy-based ambiguity function (FLOCRAF) are defined based on the feature that correntropy kernel function can effectively suppress impulsive noise. Then these two robust ambiguity functions are used to estimate the direction of arrival (DOA) of narrowband LFM signal under an impulsive noise environment. Instead of the covariance matrix used in the ESPRIT algorithm by the spatial CRAF matrix and FLOCRAF matrix, the CRAF-ESPRIT and FLOCRAF-ESPRIT algorithms are proposed. Computer simulation results show that compared with the algorithms only using ambiguity function and the algorithms only using the correntropy kernel function-based correlation, the proposed algorithms using ambiguity function based on correntropy kernel function have good performance in terms of probability of resolution and estimation accuracy under various circumstances. Especially, the performance of the FLOCRAF-ESPRIT algorithm is better than the CRAF-ESPRIT algorithm in the environment of low generalized signal-to-noise ratio and strong impulsive noise.

In this paper, we propose a modified time-domain channel estimation algorithm for OFDM systems working under impulsive noise conditions. The proposed method employs two time-domain windows to reduce additive white Gaussian noise and impulsive noise components included in the estimated channel impulse response (CIR). Meanwhile, the impulse noise equalizer further eliminates the impulse noise. As a result, the modified algorithm can overcome the mean-square error (MSE) floor caused by the conventional method in impulsive noise environment. Simulation results demonstrate that the proposed algorithm can significantly improve the MSE performance compared with the conventional estimation method, and provides about 3dB improvement in SNR for the same BER values in DVB system.

In order to realize the high-resolution multipath Time Difference Of Arrival (TDOA) estimation which is not limited by the resolution limit of correlation method under impulsive noise environment, a Correntropy Expectation-Maximum (CEM) high resolution multipath TDOA estimation algorithm is proposed based on the Maximum Correntropy Criterion (MCC). The multipath TDOA is estimated by transforming multi-dimensional optimization problems into multiple one-dimensional optimization problems. The simulation results show that the CEM algorithm has good estimation performance under strong impulsive noise and low SNR environment, and the selection of kernel size in CEM algorithm is not depend on the prior information of the impulsive noise.

A new BPSK receiver based on the statistical characteristics of impulsive radio noise is proposed. First, the statistical characteristics of impulsive radio noise are investigated, and it is proved that the quadrature components of impulsive noise are dependent. Next, with the consideration of the dependence between these components, a new BPSK receiver designed for impulsive noise is proposed, and it is shown that a great performance improvement is achieved by using this receiver. Moreover, the impulsive noise emitted from a microwave oven is experimentally measured, and the performance of this proposed receiver under the microwave oven noise environment is evaluated.

This paper reports a solution to a linear blind equalizer used in communication systems under the effect of two factors: i) An unknown linear inter symbol interference and ii) the impulsive noise satisfying the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> -stable distribution. First, a constellation matching error-based cost function associated with the linear equalizer is designed to effectively compensate for the inter symbol interference and suppress the influence of the impulsive noise. Second, an improved form of the proposed cost function is derived through the finite alphabet property of information symbols. The theoretical analysis shows that the improved cost function significantly reduces the local minima and converges more stably in high-order modulation systems. Furthermore, based on the special structure of the designed cost function, a modified Newton scheme is constructed to quickly minimize it, and then the corresponding optimal blind equalizer can be obtained. Finally, computer simulations are presented to demonstrate the robust equalization performance and fast convergence of the novel algorithm under both impulsive and Gaussian noise environments.

A full-space unambiguous direction of arrival (DOA) estimation can be achieved by only using one single vector hydrophone. And it provides spatial advantage for solving the DOA estimation. The paper proposes a novel method for DOA estimation of single vector hydrophone based on the steered minimum variance (STMV) algorithm, which applies the STMV algorithm of the array signal processing to the single vector hydrophone. With the 3×1 dimensional steered matrix, the single vector hydrophone not only has the ability of high-resolution DOA estimation, but also improves the robustness of the algorithm and reduces the calculation amount of the algorithm. The simulation data and lake test data are used for experimental verification, and STMV algorithm is compared with the cross-spectrum method and the conventional beamforming (CBF) method. The research results have shown that the STMV algorithm has higher DOA estimation capability, better robustness, and lower computational complexity.

This paper takes an Alpha-stable distribution as the noise model to solve the parameter estimation problem of bistatic multiple-input multiple-output (MIMO) radar system in the impulsive noise environment. For a moving target, its echo often contains a time-varying Doppler frequency. Furthermore, the echo signal may be corrupted by a non-Gaussian noise. It causes the conventional algorithms and signal models degenerating severely in this case. Thus, this paper proposes a new signal model and a novel method for parameter estimation in bistatic MIMO radar system in the impulsive noise environment. It combines the fractional lower-order statistics (FLOS) and fractional power spectrum density (FPSD), for suppressing the impulse noise and estimating parameters of the target in fractional Fourier transform domain. Firstly, a new signal array model is constructed based on the $$\alpha $$ź-stable distribution model. Secondly, Doppler parameters are jointly estimated by peak searching of the FLOS---FPSD. Furthermore, two modified algorithms are proposed for the estimation of direction-of-departure and direction-of-arrival (DOA), including the fractional power spectrum density based on MUSIC algorithm (FLOS---FPSD---MUSIC) and the fractional lower-order ambiguity function based on ESPRIT algorithm (FLOS---FPSD---ESPRIT). Simulation results are presented to verity the effectiveness of the proposed method.

The performance of multilevel quadrature partial-response systems (QPRS) in the presence of an additive combination of Gaussian and impulsive noise is analytically evaluated by means of the Fourier-Bessel series expansion method. The model of the impulsive noise used, which closely models atmospheric and/or man-made electromagnetic interference, consists of a stream of Poisson impulses with areas distributed according to a power Rayleigh probability density function. Analytical performance evaluation results are presented for 9, 49, and 225 QPR systems. The results indicate severe system performance degradation, especially for highly bandwidth-efficient systems (e.g. 225 QPRS), mostly due to the long error bursts caused by the impulsive noise tails. However, a qualitative comparison between these results and the corresponding performance results of equivalent QAM schemes demonstrates that 49 QPRS could be a suitable choice for microwave radio or HDTV satellite links operating in pure impulsive noise environments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Channel estimation in Underwater Acoustic Communication (UAC) faces significant challenges due to the non-Gaussian, impulsive noise in ocean environments and the inherent high dimensionality of the estimation task. This paper introduces a robust channel estimation algorithm by solving an l1−l1 optimization problem via the Alternating Direction Method of Multipliers (ADMM), effectively exploiting channel sparsity and addressing impulsive noise outliers. A non-monotone backtracking line search strategy is also developed to improve the convergence behavior. The proposed algorithm is low in complexity and has robust performance. Simulation results show that it exhibits a small performance deterioration of less than 1 dB for Channel Impulse Response (CIR) estimation in impulsive noise environments, nearly matching its performance under Additive White Gaussian Noise (AWGN) conditions. For Delay-Doppler (DD) doubly spread channel estimation, it maintains Bit Error Rate (BER) performance comparable to using ground truth channel information in both AWGN and impulsive noise environments. At-sea experimental validations for channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems further underscore the fast convergence speed and high estimation accuracy of the proposed method.

In this paper, we present a radio frequency (RF) front-end design for increasing robustness of non-coherent energy detection based impulse radio (IR) ultra-wideband (UWB) receivers in impulsive noise environment. Robustness against impulsive noise is achieved by on chip LNA-bandpass filter (BPF) circuit, which also works as a clipper for high energy impulsive noise bursts. The electrostatic discharge (ESD), wirebond, pad capacitance, and the chip package model are co-designed with wideband cascode LNA structure. These unwanted capacitive and inductive elements are designed as a part of input BPF. The LNA output stage includes an inductor that is coupling with the input capacitance of the VGA block results in additional filtering. In the post-layout simulations, 45 dB impulsive noise compression has been achieved. It has been shown that the RF front-end and LNA output stage reduces the impulsive noise and increases the noise performance of the IR-UWB receiver, hence becoming robust against the impulsive noise.

Impulse noise is a potential impairment of very-high speed digital subscriber line (VDSL) services. VDSL systems are protected from impulse noise using a combination of Reed-Solomon coding and interleaving. Since there are two competing proposals for VDSL, the first one based on the use of QAM line code and the second one using DMT modulation, it is interesting to compare their performance in terms of immunity to impulse noise. The paper presents a comparison of the behavior of QAM-VDSL and DMT-VDSL in the presence of impulse noise in real configurations. The required interleaving delay to correct all the generated errors for both systems is investigated. It is shown that when no notches are used in the radio-amateur bands, QAM and DMT systems require similar delays in order to achieve the same level of protection against impulse noise. However, when notches are implemented, DMT-VDSL achieves higher rates than QAM-VDSL. Therefore, larger error-correcting code redundancy can be used, which results in lower end-to-end delays for DMT-VDSL systems.

Direction of arrival (DOA) estimation under impulsive noise has always been an important research area in array signal processing. The traditional methods under impulsive noise mostly rely on prior parameters and have high computational complexity. Based on the filtering theory, we present an effective pretreatment filtering technology to cut out the impulse mixed in the array received data and employ the nonuniform linear array to improve the estimation performance further. First, according to the amplitude characteristics of impulse noise, the pretreatment filtering technology is proposed to cut out the impulse based on the median filter and sliding average filter, which is valid for both strong and weak impulsive noise. Second, the minimum redundant array is adopted to carry out array virtual expansion so that the array aperture can be increased and the estimation performance can be improved. Finally, based on the idea of matrix reconstruction, we propose the improved estimation of signal parameters via rotational invariance techniques algorithm and an improved root multiple signal classification algorithm for DOA estimation. Theoretical analysis and simulation results show that the proposed method has a simple processing process, small calculation load, good array expansion ability, and excellent noise adaptability. Moreover, the proposed methods greatly improve the direction-finding performance under the condition of low signal-to-noise ratio and strong impulsive noise.

The optimum detection and the design of trellis-coded modulation (TCM) signals under an impulsive noise environment are investigated. The optimum TCM receiver designed for impulsive noise is proposed, and it is shown that the TCM signals achieve better performance than the uncoded ones. Computer simulation shows that this optimum receiver, which is simple and easy to realize, gives a coding gain from several decibels up to several tens of decibels and that the performance improvement achieved by increasing the number of states of the convolutional codes is greater than that achieved under Gaussian noise. Moreover, from the capacity of the impulsive noise channel with phase modulated signals, it is shown that it is possible to achieve an improvement in performance by using the optimum TCM signal design methods, which are based on the statistical characteristics of the noise. >