Quantized peak based impulsive noise blanking in powerline communications

Accurate channel-estimation algorithms are critical for enhancing the throughput of wireless communication systems, including millimetre wave (mmWave) multiple-input multiple-output (MIMO) systems, where precise channel knowledge enables reliable signal detection and beamforming. In practical wireless environments, impulsive non-Gaussian noise with unknown statistics often occurs due to electromagnetic interference and harsh propagation conditions, significantly degrading estimation accuracy and overall system performance. In this context, the maximum correntropy criterion (MCC) has emerged as an attractive solution for robust channel estimation that outperforms state-of-the-art algorithms. However, the MCC-based algorithm’s performance is sensitive to the tuning of hyperparameters, which is challenging in the presence of non-Gaussian noise, such as impulsive noise (IN). Furthermore, a recent genre of kernel width sampling methods makes MCC hyperparameter-free and allows for asymptotic convergence to the squared-error performance of MCC with the ideal kernel width. To ensure their practical applicability, convergence analysis is essential to theoretically guarantee stability and performance under various IN scenarios. This study presents convergence analysis of hyperparameter-free MCC-based channel estimation for mmWave MIMO systems considering various IN scenarios. To validate the theoretical analysis, simulations are conducted on practical mmWave MIMO system models. Simulation results closely match the analytical findings, which confirms the accuracy and effectiveness of the analysis we here present.

Power Lines Communication (PLC) deals with the transmission of data through the use of power lines. It is one emerging infrastructure for the home area network of Smart Grid (SG). There are two types of additive noise significantly affects the performance of PLC systems, namely background noise and impulsive noise. And the noise effects of both background noise and impulsive noise are taken from Bernoulli-Gaussian Process. The log-normal distribution has been used to model the PLC channel. As power lines are not designed for data communication. Because of signal attenuation and Electromagnetic Compatibility (EMC) regulations, the PLC link has low coverage and capacity To mitigate the EMC issue, the concept of Cognitive Radio (C.R.) is used in PLC. In this paper, receiver diversity scheme namely L-channel Selection Combining (SC) and Maximal Ratio Combining (MRC) is used for improving the Signal to Noise Ratio (SNR) to improve overall the reliability system. The system performance is evaluated in terms of Outage Probability for SC and MRC.

Millimeter wave (mmWave) communication is a resplendent technology for the Fifth Generation (5G) systems. This outdoor cellular system, 5G, is expected to provide internet connections 40 times faster and with at least four times more coverage worldwide than the current 4G Long Term Evolution (LTE) wireless communications standard. However, mmWave communication system performance could be degraded severely by the non-Gaussian Impulsive Noise (IN) and this will create a cruel task to mitigate such harmful effect and modify the impairments in the system. In this paper, blanking and clipping filters are utilized in order to enhance the capability of the communication system in suppressing IN. The problem of receiver design for large antenna arrays at both the base station and mobile station in the presence of IN is modeled using Gaussian mixture model. The results reveal that the proposed algorithms of blanking and clipping are able to minimize the bit error rate.

Broadband communications for indoor power-line networks with impulsive noise using orthogonal frequency division multiplexing (OFDM) is considered. From earlier investigations, it is known that this channel suffers from multipath fading and frequency selectivity along with man-made impulsive bursty noise. Nevertheless, the calculated channel capacity limit promises very high data rates over this channel. Enhancement techniques, such as coding can help an OFDM system to tackle impulsive noise burst. In this paper, the bit error rate (BER) performance of the OFDM system under impulsive noise and frequency fading is theoretically analyzed and closed form expression for the performance is derived. Two different impulsive noise environment models are studied and it is confirmed that both models represent the same environment. Furthermore, a theoretical upper bound on the performance of coded OFDM system is obtained, given perfect interleaving. The effect of the interleaver length on coding performance is also studied. Simulations show that the upper bound is quite tight for the case of employing a longer interleaver. The effect of interleaver size on the system performance is studied, as well

One of the challenges of modulation techniques used in Fifth-Generation (5G) is their robustness in noisy environment. Conventional Orthogonal Frequency Division Multiplexing (OFDM) cannot be considered as a 5G waveform in its original form because of its certain limitations, such as performance degradation by impulsive noise (IN) and high peak to average power ratio (PAPR). Numerous modulation schemes proposed for 5G communications are able to overcome these drawbacks. Generalised Frequency Division Multiplexing (GFDM) is one of them. This paper analyses the performance of GFDM in presence of Additive White Gaussian Noise (AWGN), IN and Narrow Band Interference (NBI). It is found that GFDM is able to perform better than OFDM and Vector Orthogonal Frequency Division Multiplexing (VOFDM) in presence of noises, which can potentially be present in 5G applications. Simulation results show that GFDM achieve lower PAPR and Symbol Error Rate (SER) and an average of 10.73 dB and 4.73 dB gain in Signal to Noise Ratio (SNR) in presence of IN and combined IN and NBI respectively, as compared to OFDM and VOFDM.

Ergodic chaotic parameter modulation (ECPM) has recently been proposed as a viable modulation technique for power-line communications (PLC) due to its robustness to multipath conditions and low complexity in receiver design. While performance of ECPM has been found to be satisfactory in limited noise conditions, performance issues for other hostile challenges in the power-line environment, such as narrowband and impulsive noise, have not been extensively studied for this technique. Numerous studies have been performed on direct-sequence spread-spectrum (DSSS) modulation used in a wireless channel. The technique has been found to be well suited for a mobile environment due to its resistance to multipath fading and inherent narrowband interference suppression capability. For this study, PLC performance is investigated for both the DSSS and ECPM receiver for PLC. A signal-to-noise ratio (SNR) analysis is presented which investigates the noise-limiting properties of the power-line channel. This work provides a detailed insight to communication system performance in a power-line environment that includes the presence of significant narrowband and impulsive noise. It is concluded that while DSSS significantly outperforms ECPM in terms of bit-error rate for a Gaussian white noise-limited channel, the performance of the two techniques is similar for low SNR communication dominated by narrowband or impulsive noise. While the implementation of DSSS is more complex, ECPM is found to be less robust to low-frequency interference

In order to identify the parameters of nonlinear Hammerstein model which are contaminated by colored noise and peak noise, the least absolute deviation (LAD) is selected as the objective function to solve the problem of large residual square when the identification data is disturbed by the impulse noise which obeys symmetrical alpha stable (SαS) distribution. However, LAD cannot meet the need of differentiability required by most algorithms. To improve robustness and to solve the nondifferentiable problem, an approximate least absolute deviation (ALAD) objective function is established by introducing a deterministic function to replace absolute value under certain situations. The proposed method is derived from ALAD criterion and extended stochastic gradient method. Due to the differentiability of the objective function, we can get a recursive identification algorithm which is simple and easy to calculate compared with LAD. The convergence of the proposed identification method is also proved by Lyapunov stability theory, and the simulation experiments show that the proposed method has higher accuracy and stronger robustness than the least square (LS) method in the identification of Hammerstein model with colored noise and impulse noise. The impact of impulse noise can be restrained effectively.

Impulsive noise interference is a significant problem for the Integrated Services Digital Broadcasting for Terrestrial (ISDB-T) receivers due to its effect on the orthogonal frequency division multiplexing (OFDM) signal. In this paper, an adaptive scheme to suppress the effect of impulsive noise is proposed. The impact of impulsive noise can be detected by using the guard band in the frequency domain; furthermore the position information of the impulsive noise, including burst duration, instantaneous power and arrived time, can be estimated as well. Then a time-domain window function with adaptive parameters, which are decided in terms of the estimated information of the impulsive noise and the carrier-to-noise ratio (CNR), is employed to suppress the impulsive interference. Simulation results confirm the validity of the proposed scheme, which improved the bit error rate (BER) performance for the ISDB-T receivers in both AWGN channel and Rayleigh fading channel.

Although Power Line Communication (PLC) is not a new technology, its use to support data transmission over low voltage (LV) distribution networks is still the focus of ongoing research. This thesis focuses on the channel modelling and performance evaluation of narrowband (NB) PLC system. First, the channel modelling approaches of PLC are studied. Then, the proposed PLC channel modelling method based on the bottom-up approach for LV narrowband PLC in a frequency band between 9 kHz and 490 kHz is presented. This proposed model employs the transmission and scattering matrix methods to calculate the transfer function of a typical LV PLC network which comprises two common cable types (copper cables and aluminium conductor steel reinforced). Unlike the top-down approaches, this model is scalable as the network complexity increases and can better describe the network behaviour as a function of physical parameters.In addition, the noise characteristics and popular noise reduction techniques of PLC are studied. The major impairment to the PLC is the impulsive noise which is mainly generated by the switching transient in the network. Hence, a new technique is proposed to mitigate the impact of impulsive noise on data transmission over power lines. This proposed technique is an optimal Clipping/Blanking nonlinearity technique which is based on the minimum bit error rate (BER) search. Results obtained from the simulation of this technique demonstrate that performance has been enhanced in the NB-PLC system. The performance of the narrowband PLC system is also evaluated in both physical (PHY) and medium access control (MAC) layers. Since Orthogonal Frequency Division Multiplexing (OFDM) is a suitable modulation scheme for hostile environment of the power line, it is used to evaluate the PHY layer performance. As a result of the PHY layer performance analyses, it is found that the BER performance between neighbouring points in the typical LV PLC network is reasonable, but communication beyond one hop have to rely on upper layer protocols. In the MAC layer performance evaluation of the PLC system, the widely known random access MAC protocol that uses the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) will be utilised. The MAC performance evaluation of the PLC system demonstrates a significant packet loss in LV PLC network even with a light traffic condition due to the noisy channel. Furthermore, the goodput declines abruptly once the individual transmission rate is high enough to block the network. In addition, the simulation results show that the channel errors can be reduced by adjusting the MAC parameters to allow the re-transmissions mechanisms to recoup the lost packets.

This paper reports on findings on the analysis of the fast Fourier transform (FFT) hybrid power line communication (PLC) - visible light communication (VLC) system (PLC- VLC) based on ACO-OFDM in impulsive noise, when the perfect nulling technique is utilized to combat noise in the system. In this work, we develop theoretical expressions that describe the error floors realized in the system due to perfect nulling. Perfect nulling refers to a noise mitigation technique that perfectly identifies impulsive noise locations in a string of data samples and clips them to zero, leading to an error floor at a high Signal to Noise (SNR) ratio. Thus, the principal contribution of this paper is to analyze and derive theoretical Bit Error Rate (BER) expressions for the error floor achieved by a BPSK OFDM signal in the FFT hybrid PLC-VLC system based on asymmetrically clipped optical - orthogonal frequency division multiplexing (ACO-OFDM), in a channel corrupted with Added White Gaussian Noise (AWGN) and impulsive noise. The derived theoretical BER results will be compared to the error floors obtained through simulations.

Power line communication (PLC) utilizes power lines for the purpose of electronic data transmission. The performance of a PLC system is significantly affected by the additive and multiplicative power line noises; the additive noises are of two types, namely background noise and impulsive noise. Whereas, the multiplicative PLC noise leads to fading in the received signal strength. In this paper, we evaluate the performance of a PLC system over log-normal fading channel under Nakagami-m distributed additive background noise assuming binary phase shift keying modulation scheme. The analysis involving log-normal fading is very complicated. Hence we use a novel gamma approximation to log-normal distribution for our analysis. We evaluate the probability density function of the decision variable. A closed-form expression of the analytical average bit error rate of the considered system is derived. We also compute the diversity order of the considered PLC system. The validity of the derived analytical expressions is closely verified by the simulation results.

In this paper, an algorithm that estimates the parameters of impulse noise (IN) is proposed in power line communication. The Peak to Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) symbol sent by the transmitter is reduced by the selective mapping (SLM) technology. In addition, the peak value of each OFDM symbol is sent with a separate control channel. At receiver, the frequency characteristics of IN is calculated using the received peak value and the OFDM symbol. The noise used for simulation comes from actual measurement. Results from simulations show that the proposed algorithm can estimate the IN well under different IN environments, and the obtained parameters are very valuable for mitigating IN in power line communication.

Power line communication (PLC) is an emerging technology for the realization of smart grid and home automation. It utilizes existing power line infrastructure for data communication in addition to the transmission of power. The PLC channel behaves significantly different from the wireless channel; and it is characterized by signal attenuation as well as by additive noise and multiplicative noise effects. The additive noise consists of background noise and impulsive noise; while the multiplicative noise results in fading of the received signal power. This paper investigates the impact of the channel characteristics on the capacity performance of a PLC system over Rayleigh fading channel with frequency-distance dependent attenuation and colored Nakagami-m distributed additive noise. We derive the exact closed-form expressions for the distribution of the instantaneous signal-to-noise ratio (SNR). Since closed-form expression of the capacity for channels with non-Gaussian noise is extremely difficult to obtain, we choose to use the lower limit of the PLC capacity to facilitate our analysis. Monte Carlo simulation results are used to verify the derived analytical expressions.

In power-line channels impulsive noise (IN) is commonly reduced using a blanking technique in which the received signal is zeroed whenever it exceeds a certain threshold value.Determining an appropriate threshold however is critical to the performance of this technique as erroneously blanking unaffected parts of the signal will significantly degrade the system performance.In this paper, we show that the performance of this technique is sensitive not only to the blanking threshold but also to the transmitted signal's peak-to-average power ratio (PAPR).With this in mind we propose to implement single-carrier FDMA (SC-FDMA), which inherently has low PAPR, and address the issue of optimizing the blanking threshold for such technique.The results reveal that significant improvements can be achieved with respect to the probability of blanking error, as well as achieving up to 4dB SNR improvement relative to the conventional OFDM case.Furthermore, it will be shown that in some cases of SC-FDMA, not only a significant SNR enhancement can be achieved but also it is possible to optimally blank IN irrespective of the noise characteristics.

Nonlinear preprocessors, including clipping, blanking, and joint blanking/clipping have been proposed to be employed in orthogonal frequency-division multiplexing systems for mitigating the impulsive noise in power-line communications. In this paper, we propose using a new variant of nonlinear preprocessor, namely, deep clipping, to mitigate the impulsive noise. In contrast to clipping, blanking, and joint blanking/clipping, where one or two thresholds is used to detect if the impulsive noise occurs, and if the impulsive noise occurs how to handle it, deep clipping is characterized by two alternative parameters, namely, a threshold and a depth factor. By optimizing the two parameters, we find that deep clipping achieves better signal-to-noise ratio (SNR) performance than clipping, blanking, and joint blanking/clipping. In addition, we present a mathematical expression for deep clipping and show that the SNR expressions regarding conventional clipping, blanking, and joint blanking/clipping can be easily obtained by using our analytical methods. © 1986-2012 IEEE.