Adaptive Analog Nonlinear Algorithms and Circuits for Improving Signal Quality in the Presence of Technogenic Interference

Nikitin, Alexei V.; Davidchack, Ruslan L.; Sobering, Timothy J.

doi:10.1109/milcom.2013.197

Cited by 6 publications

(19 citation statements)

References 25 publications

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“…The lower panels of Figure 4 quantify such peakedness of the receiver signal z(t) = I(t) + iQ(t) in terms of the measure K dBG found in [2,3]: where the angular brackets denote time averaging. This measure of peakedness is based on an extension of the classical definition of kurtosis ( [13], for example) to complex variables ( [14], for example).…”

Section: Impulsive Nature Of Interchannel Interferencementioning

confidence: 93%

“…More comprehensive descriptions of NDLs, with detailed analysis and examples of various NDL configurations, nonadaptive as well as adaptive, can be found in [1][2][3].…”

Section: Nonlinear Differential Limitersmentioning

confidence: 99%

“…A comprehensive discussion and illustrative examples of various dependencies of the NDL parameters on the difference signal can be found in [1][2][3]. For example, one can set the quality factor in Equation 12 to a constant value and allow the time parameter τ to be a nondecreasing function of the absolute value of the difference signal satisfying the following equation:…”

Section: Higher Order Ndlsmentioning

confidence: 99%

“…In particular, impulsive interference that is characterized by a frequent occurrence of outliers (i.e., relatively high-amplitude, short-duration events) can be effectively mitigated by the nonlinear differential limiters (NDLs) described in [1][2][3][4] and in Section 3 of this paper. An NDL can be configured to behave linearly when the input signal does not contain outliers, but when the outliers are encountered, the nonlinear response of the NDL limits the magnitude of the respective outliers in the output signal.…”

Section: Introductionmentioning

confidence: 99%

“…Following the dynamic nature of the ad hoc networks, where the networks themselves are scalable and adaptive, and include spectrum sensing and dynamic re-configuration of the network parameters, interference mitigation tools are needed to be scalable and adaptive to the dynamically changing interference. Adaptive NDLs (ANDLs) [2,3] have been developed to address this challenge.…”

Section: Introductionmentioning

confidence: 99%

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Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

Nikitin

Davidchack

Smith

2015

EURASIP J. Adv. Signal Process.

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In a perfect world, we would have 'brick wall' filters, no-distortion amplifiers and mixers, and well-coordinated spectrum operations. The real world, however, is prone to various types of unintentional and intentional interference of technogenic (man-made) origin that can disrupt critical communication systems. In this paper, we introduce a methodology for mitigating technogenic interference in communication channels by analog nonlinear filters, with an emphasis on the mitigation of out-of-band and adjacent-channel interference. Interference induced in a communications receiver by external transmitters can be viewed as wide-band non-Gaussian noise affecting a narrower-band signal of interest. This noise may contain a strong component within the receiver passband, which may dominate over the thermal noise. While the total wide-band interference seen by the receiver may or may not be impulsive, we demonstrate that the interfering component due to power emitted by the transmitter into the receiver channel is likely to appear impulsive under a wide range of conditions. We give an example of mechanisms of impulsive interference in digital communication systems resulting from the nonsmooth nature of any physically realizable modulation scheme for transmission of a digital (discontinuous) message. We show that impulsive interference can be effectively mitigated by nonlinear differential limiters (NDLs). An NDL can be configured to behave linearly when the input signal does not contain outliers. When outliers are encountered, the nonlinear response of the NDL limits the magnitude of the respective outliers in the output signal. The signal quality is improved in excess of that achievable by the respective linear filter, increasing the capacity of a communications channel. The behavior of an NDL, and its degree of nonlinearity, is controlled by a single parameter in a manner that enables significantly better overall suppression of the noise-containing impulsive components compared to the respective linear filter. Adaptive configurations of NDLs are similarly controlled by a single parameter and are suitable for improving quality of nonstationary signals under time-varying noise conditions. NDLs are designed to be fully compatible with existing linear devices and systems and to be used as an enhancement, or as a low-cost alternative, to the state-of-art interference mitigation methods.

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Section: Impulsive Nature Of Interchannel Interferencementioning

confidence: 93%

“…More comprehensive descriptions of NDLs, with detailed analysis and examples of various NDL configurations, nonadaptive as well as adaptive, can be found in [1][2][3].…”

Section: Nonlinear Differential Limitersmentioning

confidence: 99%

Section: Higher Order Ndlsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

Nikitin

Davidchack

Smith

2015

EURASIP J. Adv. Signal Process.

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Hidden Outlier Noise and its Mitigation

Nikitin¹,

Davidchack

2019

IEEE Access

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In addition to ever-present thermal noise, various communication and sensor systems can contain significant amounts of interference with outlier (e.g. impulsive) characteristics. Such outlier noise can be efficiently mitigated in real-time using intermittently nonlinear filters. Depending on the noise nature and composition, improvements in the quality of the signal of interest will vary from "no harm" to substantial. In this paper, we explain in detail why the underlying outlier nature of interference often remains obscured, discussing the many challenges and misconceptions associated with state-of-art analog and/or digital nonlinear mitigation techniques, especially when addressing complex practical interference scenarios. We then focus on the methodology and tools for real-time outlier noise mitigation, demonstrating how the "excess band" observation of outlier noise enables its efficient in-band mitigation. We introduce the basic real-time nonlinear components that are used for outlier noise filtering, and provide examples of their implementation. We further describe complementary nonlinear filtering arrangements for wide-and narrow-band outlier noise reduction, providing several illustrations of their performance and the effect on channel capacity. Finally, we outline "effectively analog" digital implementations of these filtering structures, discuss their broader applications, and comment on the ongoing development of the platform for their demonstration and testing.Index Terms-Analog filter, digital filter, electromagnetic interference (EMI), impulsive noise, intermittently nonlinear filter, man-made interference, non-Gaussian noise, nonlinear signal processing, outlier noise, technogenic interference.

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Analog-Domain Mitigation of Outlier Noise in the Process of Analog-to-Digital Conversion

Nikitin

Davidchack

2018

2018 IEEE International Conference on Communications (ICC)

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Adaptive Analog Nonlinear Algorithms and Circuits for Improving Signal Quality in the Presence of Technogenic Interference

Cited by 6 publications

References 25 publications

Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

Hidden Outlier Noise and its Mitigation

Analog-Domain Mitigation of Outlier Noise in the Process of Analog-to-Digital Conversion

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