Impulse noise

About: Impulse noise is a research topic. Over the lifetime, 4816 publications have been published within this topic receiving 63970 citations.

Fourier-Bessel error performance analysis and evaluation of M-ary QAM schemes in an impulsive noise environment

Abstract: The authors derive closed-form expressions for the BER (bit error rate) performance of coherent M-ary quadrature amplitude modulated (QAM) system in the presence of an additive combination of Gaussian and highly impulsive noise by using a Fourier-Bessel series expansion method. The model used for the impulse noise, which closely models atmospheric and/or ignition noise, consists of a stream of Poisson impulses with areas distributed according to a bilateral Rayleigh probability distribution function. Although the methodology is general enough to accommodate any M-ary QAM scheme, they present analytical as well as some computer simulated results for 16-, 64-, and 256-QAM systems. An almost insignificant increase of the truncation error with the increase of the modulation levels verifies that the proposed method of analysis can be a useful tool in evaluating the performance of very large-alphabet M-ary QAM systems, e.g. M>or=256. >

Sparse representation prior and total variation-based image deblurring under impulse noise

Abstract: In this paper, we study the image recovery problem where the observed image is simultaneously corrupted by blur and impulse noise. Our proposed patch-based model contains three terms: the sparse representation prior, the total variation regularization, and the data-fidelity term. We are interested in the two-phase approach. The first phase is to identify the possible impulse noise positions; the second phase is to recover the image via the patch-based model using noise position information. An alternating minimization method is then applied to solve the model. This approach works extremely well for image deblurring under salt-and-pepper noise. However, as the detection for random-valued noise is usually unreliable, extra work is then needed. Indeed, to get better recovery results for the latter case, we combine the two separate phases to simultaneously detect the random-valued noise positions and to recover the image. The numerical experiments clearly demonstrate the super performance of the proposed methods.

Space-time coding over fading channels with impulsive noise

Abstract: Impulsive, non-Gaussian noise is prevalent in wireless environments. We adopt an impulsive noise model over multi-input-multi-output (MIMO) channels and discuss receiver and code design over fading channels with impulsive noise. We derive code design criteria for the so-called genie-aided, and minimum distance receivers, both of which yield criteria identical to the nonimpulsive, Gaussian noise case. We also study the performance of certain space-time block codes (STBCs) and space-time trellis codes (STTC) over impulsive noise channels with the genie-aided receiver (GAR) and minimum distance receiver (MDR). The performance loss incurred by the impulsive nature of the noise is shown to increase with the diversity order for the MDR. To approximate the good performance of the practically unrealistic GAR, we propose a maximum a posteriori (MAP) receiver, whose performance can be tightly lower bounded by the GAR. We simplify the optimal MAP receiver by an approximation and show that for alt cases of practical interest, only 2 terms in the approximation are sufficient to get a near-MAP performance. Simulations corroborate our analytical findings

Impulse noise mitigation for OFDM using decision directed noise estimation

Abstract: The paper describes a new technique for mitigating the effects of impulse noise in OFDM. An estimate is made of the noise component in each received input sample. The estimates are based on the transmitted data. No pilot tones are required. When the estimate is large enough to indicate that impulse noise is present in the sample, the estimated noise component is subtracted from the input sample before final demodulation. Estimates of the noise are obtained from preliminary decisions based on the noisy signal. The technique is effective because the energy from each noise impulse is spread across the received spectrum. The technique can also be applied to multicarrier CDMA. Simulations show that, in cases of practical importance, the symbol error rate can be reduced by several orders of magnitude.

Comparative Evaluation of Methodologies for T-Wave Alternans Mapping in Electrograms

Abstract: Electrograms (EGM) recorded from the surface of the myocardium are becoming more and more accessible. T-wave alternans (TWA) is associated with increased vulnerability to ventricular tachycardia/fibrillation and it occurs before the onset of ventricular arrhythmias. Thus, accurate methodologies for time-varying alternans estimation/detection in EGM are needed. In this paper, we perform a simulation study based on epicardial EGM recorded in vivo in humans to compare the accuracy of four methodologies: the spectral method (SM), modified moving average method, laplacian likelihood ratio method (LLR), and a novel method based on time-frequency distributions. A variety of effects are considered, which include the presence of wide band noise, respiration, and impulse artifacts. We found that 1) EGM-TWA can be detected accurately when the standard deviation of wide-band noise is equal or smaller than ten times the magnitude of EGM-TWA. 2) Respiration can be critical for EGM-TWA analysis, even at typical respiratory rates. 3) Impulse noise strongly reduces the accuracy of all methods, except LLR. 4) If depolarization time is used as a fiducial point, the localization of the T-wave is not critical for the accuracy of EGM-TWA detection. 5) According to this study, all methodologies provided accurate EGM-TWA detection/quantification in ideal conditions, while LLR was the most robust, providing better detection-rates in noisy conditions. Application on epicardial mapping of the in vivo human heart shows that EGM-TWA has heterogeneous spatio-temporal distribution.