Noise Mitigation Methods Research Articles

A novel error detection & concealment technique for videos streamed over error prone channels

In video streaming services and applications, impulse noise occurs due to transmission errors or sometimes it is introduced during signal acquisition. The work presented in this paper proposes a novel impulse noise detection and mitigation (INDAM) method that can significantly recover video frames heavily impaired by impulse noise. The proposed technique uses cyclic redundancy check (CRC) method to create an error mask of the received impaired video frames. This error mask contains pixel-by-pixel error information of the video frames and is exploited further to mitigate the error from the impaired video frame. Each impaired pixel in the video frame is replaced by the average of its corresponding error-free neighboring pixels’ values, hence removing the impaired pixels and replacing them with the newly calculated average. The proposed technique uses the error mask created from the CRC method and uses only those pixels which do not contain error for calculating the averages. Results show that INDAM outperforms other contemporary methods in terms of peak signal to noise ratio (PSNR) and structural similarity index metric (SSIM).

NLIN Mitigation Using Turbo Equalization and an Extended Kalman Smoother

We develop a method for inter-channel nonlinear interference noise (NLIN) mitigation, based on Turbo equalization and an extended Kalman smoother. The method exploits both the unique statistical properties of NLIN and soft-decision information from the code structure, to obtain improved channel state estimation and symbol detection. The error-free information rate is improved by up to 0.3 b/symbols/polarization, for a 1000 km, 64-QAM, 32 Gbaud transmission over standard fiber.

Joint Channel Estimation and Impulsive Noise Mitigation Method for OFDM Systems Using Sparse Bayesian Learning

The impulsive noise can deteriorate sharply the performance of orthogonal frequency division multiplexing (OFDM) systems. In this paper, we propose a novel joint channel impulse response estimation and impulsive noise mitigation algorithm based on compressed sensing theory. In this algorithm, both the channel impulse response and the impulsive noise are treated as a joint sparse vector. Then, the sparse Bayesian learning framework is adopted to jointly estimate the channel impulse response, the impulsive noise, and the data symbols, in which the data symbols are regarded as unknown parameters. The Cramer–Rao Bound is derived for the benchmark. Unlike the previous impulsive noise mitigation methods, the proposed algorithm utilizes all subcarriers without any a priori information of the channel and impulsive noise. The simulation results show that the proposed algorithm achieves significant performance improvement on the channel estimation and bit error rate performance.

An ultra-compact low temperature scanning probe microscope for magnetic fields above 30 T.

We present the design of a highly compact high field scanning probe microscope (HF-SPM) for operation at cryogenic temperatures in an extremely high magnetic field, provided by a water-cooled Bitter magnet able to reach 38 T. The HF-SPM is 14 mm in diameter: an Attocube nano-positioner controls the coarse approach of a piezoresistive atomic force microscopy cantilever to a scanned sample. The Bitter magnet constitutes an extreme environment for scanning probe microscopy (SPM) due to the high level of vibrational noise; the Bitter magnet noise at frequencies up to 300 kHz is characterized, and noise mitigation methods are described. The performance of the HF-SPM is demonstrated by topographic imaging and noise measurements at up to 30 T. Additionally, the use of the SPM as a three-dimensional dilatometer for magnetostriction measurements is demonstrated via measurements on a magnetically frustrated spinel sample.

Life Cycle Assessment of Railway Ground-Borne Noise and Vibration Mitigation Methods Using Geosynthetics, Metamaterials and Ground Improvement

Significant increase in the demand for freight and passenger transports by trains pushes the railway authorities and train companies to increase the speed, the axle load and the number of train carriages/wagons. All of these actions increase ground-borne noise and vibrations that negatively affect people who work, stay, or reside nearby the railway lines. In order to mitigate these phenomena, many techniques have been developed and studied but there is a serious lack of life-cycle information regarding such the methods in order to make a well-informed and sustainable decision. The aim of this study is to evaluate the life-cycle performance of mitigation methods that can enhance sustainability and efficacy in the railway industry. The emphasis of this study is placed on new methods for ground-borne noise and vibration mitigation including metamaterials, geosynthetics, and ground improvement. To benchmark all of these methods, identical baseline assumptions and the life-cycle analysis over 50 years have been adopted where relevant. This study also evaluates and highlights the impact of extreme climate conditions on the life-cycle cost of each method. It is found that the anti-resonator method is the most expensive methods compared with the others whilst the use of geogrids (for subgrade stiffening) is relatively reliable when used in combination with ground improvements. The adverse climate has also played a significant role in all of the methods. However, it was found that sustainable methods, which are less sensitive to extreme climate, are associated with the applications of geosynthetic materials such as geogrids, composites, etc.

Noise mitigation methods for ion detectors operating with a direct view of high temperature plasmas.

We have developed an ion current measurement instrument with a direct view of a plasma that reduces the particle and radiation-induced noise current it detects by over three orders of magnitude, from tens of microamps to tens of nanoamps. This is accomplished using electric fields, magnetic fields, and physical shielding that limit the flux of particles and radiation into the instrument and suppress the secondary electrons produced within it by particle and radiation impact. Operation of this detector in various configurations, without an ion beam, has allowed identification of the sources of noise current. In our experimental setup, the largest noise contributors were found to be plasma ions and photoelectric emission due to UV radiation.

Measurement of pattern roughness and local size variation using CD-SEM

Measurement of line edge roughness (LER) is discussed from four aspects: edge detection, power spectrum densities (PSD) prediction, sampling strategy, and noise mitigation. General guidelines and practical solutions for LER measurement today are introduced. Advanced edge detection algorithms such as the wave-matching method are shown to be effective for robustly detecting edges from low SNR images, whereas a conventional algorithm with weak filtering is still effective in suppressing SEM noise and aliasing. An advanced PSD prediction method such as the multitaper method is effective in suppressing sampling noise within a line edge to analyze, whereas a number of lines are still required for suppressing line-to-line variation. Two types of SEM noise mitigation methods, such as the “apparent noise floor” subtraction method and LER-noise decomposition using regression analysis, are verified to successfully mitigate SEM noise from PSD curves. These results are extended to local critical-dimension uniformity (LCDU) measurement to clarify the impact of SEM noise and sampling noise on LCDU.

Electromagnetic Noise Mitigation for Ultrafast on-Die Temperature Sensing in High-Power Modules

Real-time junction temperature measurements can be very beneficial for improving power converter's design, performance, and reliability. Junction temperature sensing using an on-die diode sensor is a promising solution. However, a strong low-pass filter is usually applied to filter out the sensor's noise during switching transients, which reduces the sensor's bandwidth. This paper aims to improve the sensing system's bandwidth to achieve an ultrafast real-time junction temperature measurement. Three noise coupling mechanisms have been identified and verified by both simulations and experiments. The noise coupling model-based crosstalk capacitances estimation method is proposed and validated. Noise mitigation methods are proposed, thus only a 200-kHz low-pass filter is needed for the noise suppression purpose, which is a significant improvement from the current field implementation of tens of hertz bandwidth.

Low‐density parity check coded orthogonal frequency division multiplexing for PLC in non‐Gaussian noise using LLRs derived from effective noise probability density functions

In this study, the performance of irregular low-density parity check (LDPC) coded orthogonal frequency division multiplexing (COFDM) utilising 4096 quadrature amplitude modulation (4096-QAM) is investigated over multipath power-line communication (PLC) channel. The effective complex-valued ratio distributions of the noise samples at the zero-forcing equaliser output considering both frequency-selective multipath PLCs, background and impulsive noise are derived, in addition to the condition for optimum detection of 4096-QAM and the bit error rate (BER). Moreover, the performance of the LDPC decoder is improved by computing the log-likelihood ratios (LLRs) required for soft decoding based on the derived probability density functions. Numerical results obtained using the newly derived LLRs demonstrate a significant performance improvement compared to the conventional receiver that uses blanking impulsive noise mitigation method and LLR computed based on the Gaussian distribution. Furthermore, EXtrinsic Information Transfer chart analysis demonstrates that the proposed approach requires fewer iterations for convergence compared to the conventional receiver. Finally, utilising channel bandwidth of 22.4 MHz, the proposed system offers an improvement of 111 Mbps over the conventional system to reach a maximum data throughput of 256 Mbps for a signal-to-noise ratio of 39 dB and BER of 10 -5 .

Analysis and Mitigation of Striping Noise in Two Water Vapor Sounding Channels of Global Precipitation Measurement (GPM) Microwave Imager

AbstractThe Global Precipitation Measurement (GPM) Microwave Imager (GMI) plays an important role in monitoring global precipitation. In this study, an along-track striping noise is found in GMI observations of brightness temperatures for the two highest-frequency channels—12 and 13—with their central frequencies centered at 183.31 GHz. These two channels are designed for sounding the water vapor in the middle and upper troposphere. The pitch maneuver data of deep space confirmed an existence of striping noise in channels 12 and 13. A striping noise mitigation method is used for extracting the striping noise from the earth scene or deep space measurements of brightness temperatures by combining the principle component analysis (PCA) with the ensemble empirical mode decomposition (EEMD) method. A power spectrum density analysis indicated that the frequency of striping noise ranges between 0.06 and 0.533 s−1, where the right bound of 0.533 s−1of frequency is exactly the inverse of the time (i.e., 1.875 s) it takes for the GMI to complete one conical scan line. The magnitude of striping noise in the brightness temperature observations of GMI channels 12 and 13 is about ±0.3 K. It is shown that after striping noise mitigation, the observation minus model simulation (O − B) distributions of both the earth scene and deep space brightness temperatures show no visible striping features.

Research and Mitigation on EMI Noise for PV Converter

Photovoltaic (PV) systems have been widely used for power generation and renewable energy. Conducted electromagnetic interference (EMI) noise have generated, which affect the performance of other device and the grid. In the paper, the measurement uncertainty of artificial mains network (AMN) has been analyzed. The conducted EMI noise mechanism and noise mitigation methods have been proposed, including transistor filter and well grounding design strategies. The simulation and experiment results show that the conducted EMI noise generated by a certain convert can be suppressed well and pass EN 55011 and EN 55022 standards, thus good realization and validation.

A preliminary investigation of noise impact within metro stations in the urban city of Guangzhou, China.

The noise in the metro station is synthesized from a variety of different noise sources. Excessive noise exposure will bring serious impacts on humans' health. To alleviate the shortage of the urban land, most metro stations are planning to develop convenience stores and shopping malls. In order to evaluate the potential noise impact on humans' comfort in the metro stations, this study selected four representative stations of Guangzhou Metro Line 1 to carry out a preliminary questionnaire survey of 226 respondents for the perception and perform a noise measurement. Additionally, platform screen doors as a potential method for noise mitigation were examined. The results show that the noise caused by trains was dominant in the metro stations; however, the noise impact by public broadcast and passengers cannot be ignored. The noise levels of the transfer stations were obviously greater than the normal stations, especially during the peak hours. In addition, people in the metro stations have potential exposure to noise that the noise levels exceed the criteria limit of China, which would bring discomfort for humans; however, the normal activities of people would not be impacted. The platform screen doors should be further improved or relevant noise mitigation methods should be taken into account to reduce the noise level within the criteria limit.

Iterative impulse noise and large scale single frequency noise mitigation for underwater acoustic OFDM

Joint and separate designs for impulse noise and large scale single frequency noise mitigation are proposed to ensure high robustness in orthogonal frequency division multiplexing (OFDM) systems. Iterative design is used to obtain a better performance. Simulation results and experimental results are show that the proposed methods are efficient to mitigate interference and improve system performance. Furthermore, joint large scale single frequency noise and impulse noise mitigation method is better than other proposed methods.

Life Cycle Cost Evaluation of Noise and Vibration Control Methods at Urban Railway Turnouts

A focus of the railway industry over the past decades has been to research, find and develop methods to mitigate noise and vibration resulting from wheel/rail contact along track infrastructure. This resulted in a wide range of abatement measures that are available for today’s engineers. The suitability of each method must be analysed through budget and timeframe limitations, which includes building, maintenance and inspection costs and time allocation, while also aiming at delivering other benefits, such as environmental impact and durability of infrastructure. There are several situations that need noise and vibration mitigation methods, but each design allocates different priorities on a case-by-case basis. Traditionally, the disturbance caused by railways to the community are generated by wheel/rail contact sound radiation that is expressed in different ways, depending on the movement of the rolling stock and track alignment, such as rolling noise, impact noise and curve noise. More specifically, in special trackworks such as turnouts (or called “switches and crossings”), there are two types of noise that can often be observed: impact noise and screeching noise. With respect to the screeching (or flanging), its mitigation methods are usually associated with curve lubrications. In contrast, the impact noise emerges from the sound made by the rolling stock moving through joints and discontinuities (i.e., gaps), resulting in various noise abatement features to minimise such noise impact. Life cycle analysis is therefore vital for cost efficiency benchmarking of the mitigation methods. The evaluation is based on available data from open literature and the total costs were estimated from valid industry reports to maintain coherency. A 50-year period for a life cycle analysis is chosen for this study. As for the general parameters, an area with a high density of people is considered to estimate the values for a community with very strict limits for noise and vibration.

Awireless passive radar system for real-time through-wall movement detection

In this paper, a reconfigurable real-time passive wireless detection system is described. The system is based on software-defined radio (SDR) architecture. The signal processing method and processing flow that enable through-wall target detection are introduced. The high-speed noise and interference mitigation methods implemented in the system for through-wall target detection are also described. A series of experimental results are presented for both large and small human body movements in through-wall scenarios. It is shown that the high-resolution Doppler event history implemented in the system enables the system to recognize and distinguish a range of body movements. The results demonstrate that this real-time SDR-based wireless detection system is a low-cost solution for human movement and recognition, with a range of applications.

Optimized mitigation of impulsive noise in OFDM system using CSI

This paper presents comparison between different impulsive noise mitigation techniques in orthogonal-frequency-division-multiplexing (OFDM) systems, which affect the performance of underlying communication system in terms of the bit-error-rate (BER). The main focus is on Zhidkov’s (ZKV) method and Jia’s method for impulsive noise mitigation using imperfect channel-state-information (CSI). Though former scheme appears to be a promising peak detection method based on the variance of estimated impulsive noise, but latter composite-comparison-value (CCV) method is found to be outperforming in alleviating the adverse effects of impulsive noise in frequency-domain, at the receiving end. In ZKV and CCV methods, different parametric values are optimized to suppress the impulsive noise under fading conditions in the presence of perfect CSI. Simulation results are presented for performance evaluation of these impulsive noise suppression schemes using imperfect CSI for the different modulation schemes, which illustrate the efficacy of CCV method in the field of communication engineering.

An adaptive recursive noise compensator for impulsive noise mitigation over OFDM power line communication

Powerline networks are recently being used for broadband data transmission such as Internet, image and video delivery. Improving the quality of broad transmission over PLC channel is of great importance and an area of current interests. In this paper, we propose a novel estimation and noise mitigation method for power line communication (PLC) systems in impulsive noise environments. For this purpose, an adaptive recursive noise compensator (ARNC) algorithm is proposed, based on an iterative estimation of the impulsive noise, using the signal to impulsive noise power ratio (SINR), and the peak to average power ratio (PAPR) in the time domain after channel equalization and OFDM demodulation. A new clipping/blanking function is introduced to estimate and detect the impulsive bursts. When bit error rate (BER) and mean square error (MSE) are evaluated, the proposed method achieves high performance in an attenuated 15-paths condition. The signal-to-noise (SNR) improvements obtained by the proposed algorithm can achieve 11–18dB under Eb/No=0dB and more than 12dB at BER=10−3 for OFDM signal using quadratic phase-shift keying (QPSK) modulation.

Striping noise mitigation in ATMS brightness temperatures and its impact on cloud LWP retrievals

AbstractAdvanced Technology Microwave Sounder (ATMS) on board Suomi National Polar‐orbiting Partnership (NPP) satellite provides global distributions of microwave brightness temperature measurements at 22 temperature and humidity sounding channels twice daily. However, the differences between observations and brightness temperature simulations exhibit a systematic along‐track striping noise for all channels. In this study, a set of 22 “optimal” filters is designed to remove the striping noise in different channels. It is shown that the original method for ATMS striping noise mitigation developed by Qin et al. () can be simplified and made suitable for use in an operational context. Impacts of striping noise mitigation on small‐scale weather features are investigated by comparing ATMS cloud liquid water path (LWP) retrieved before and after striping noise mitigation. It is shown that the optimal filters do not affect small‐scale cloud features while smoothing out striping noise in brightness temperatures. It is also shown that the striping noise is present in the LWP retrievals if the striping noise in brightness temperatures of ATMS channels 1 and 2 is not removed. The amplitude of the striping noise in LWP is linearly related to the magnitude of striping noise in ATMS brightness temperature observations.

Impulsive noise estimation and suppression in OFDM systems over in‐home power line channels

SummaryThis paper proposes a new adaptive iterative method to impulsive noise mitigation in OFDM systems over in‐home power line channels. The performance of impulsive noise mitigation methods based on OFDM decreases when the impulsive noise energy is higher than a certain threshold. To compensate for the limitations of these systems and to be able to adopt it for all sub‐carriers, here, the 64‐QAM constellation is applied together with Alamouti space time coding to transmit, MIMO In‐home power line channel and zero‐forcing estimate (ZFE) with continuous loop impulsive noise detection and mitigation together with maximum‐likelihood detection (MLD) are adopted to receive. At the receiver, after ZFE, impulsive noise detection algorithm based on adaptive threshold for estimating the impulsive noise, determines the locations and amplitudes of the impulsive noises. The effect of impulsive noise on the noise symbols using the mask based on the soft decision method is reduced. Later, using MLD, the original signal is estimated. The algorithm is simulated and analyzed, and its performance is compared to other methods. The results show the superiority and robustness of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.

A Feedforward Partial Phase Noise Mitigation in the Time-Domain using Cyclic Prefix for CO-OFDM Systems

We propose a blind feedforward phase noise mitigation method in the time-domain for a coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. By exploiting the redundancy of the cyclic prefix (CP), the proposed scheme acquires the overall phase noise difference information during an OFDM block and attempts to mitigate the phase noise in the time domain using a linear approximation. The proposed algorithm mitigates common phase error (CPE) and inter-carrier-interference (ICI) due to phase noise simultaneously, improving the system performance, especially when decision-directed equalizers are used. The simulation results demonstrate the effectiveness of the proposed feedforward phase noise mitigation approach in time domain.