Improved reliability of power line communication under alpha-stable noise

Unpredictable characteristics of power line communication (PLC) channels seriously affect the performance of the communication systems. Among these unpredictable characteristics, noise is considered to be the main source of errors in data transmission in PLC systems. Unlike conventional communication systems in which noise is usually modeled as additive white Gaussian noise (AWGN), its definition in PLC channels has a more complicated form. In order to design reliable PLC systems, it is essential to understand the features of noise in power line networks. Since the impulsive noise generated by electrical house appliances is one of the most significant noise types in PLC channel, it is very important to analyze these electrical devices with respect to their noise characteristics. In this paper, impulsive noise characteristics of various house appliances are analyzed over the frequency range of 30kHz-50MHz.

Advanced communication technologies has allowed the power-line communication (PLC) channel to be a transmission medium that enables the transferring of high-speed digital data over the classical indoor electrical wires. The development of PLC systems for Internet, voice, and data services requires measurement-based models of the transfer characteristics of the power-line network suitable for performance analysis by simulation. In this paper, a statistical-based and deterministic PLC channel frequency model was proposed. This model has the advantage of using only one parameter: the channel class. Related software is also developed. In this paper, this model is further improved to represent the measured impulse responses, and related software is developed. First, a PLC channel classification is realized, and an average magnitude and phase channel model by class is proposed. Second, the multipath behaviour of the PLC channel is introduced: a statistical-based channel magnitude generator is built, and a refined phase model is suggested. Finally, the related software is briefly described.

Power line communication (PLC) uses the highly developed infrastructure of the electrical energy distribution network for data transmission. Measurements are showing that a broadband use of PLC channels is possible. So, PLC is of interest to future broadband communication systems. Such systems will be heterogeneous in several respects, for example relative to the used transmission channel but also relative to the complexity of the participant nodes. Wittneben and Kuhn (see block VTC 2002 - Spring) presented a new class of space-time block codes for radio channels. These codes meet the requirements of future communication systems. They are highly flexible and can be adapted to the particular requests of the transmission. In this paper a PLC application of these codes is investigated. They are used as a basis for a scalable and efficient PLC channel coding scheme. This shows that this class of codes can be used as a generic coding scheme for heterogeneous networks. Alternatively, the PLC application can be considered as an example of the usage of the codes on a frequency selective channel with coloured noise. The applied linear block code optimally uses the diversity of the frequency selective channels in combination with OFDM. This leads to significant gains in performance in case of very frequency selective channels; for barely frequency selective channels or for an AWGN channel the performance is slightly better or not affected respectively. These performance results are presented for measured PLC channels.

Direct sequence code division multiple access (DS-CDMA) and M-ary frequency shift keying (MFSK) are two viable modulation schemes for broadband power line communication (PLC) channels, for multi-carrier and single carrier cases respectively. In this paper, we study the bit error rate (BER) performance of a synchronous DS-CDMA system and an MFSK system employing coherent detection for a PLC channel. The background noise present in PLC channel is assumed to follow Nakagami-m distribution as suggested by earlier works. Thereafter a comparison is drawn between the two modulation schemes. In order to draw the comparison at an equal level, we analyse the BER performances of the two systems having the same degree of transmitter/ receiver complexity along with the criteria of same bandwidth occupation, same transmission power as well as the same PLC channel characteristics. The study provides an insight as to how a small change in the parameter of a random variable (RV) describing the background power line noise has a marked influence on the BER performances of the two modulation schemes mentioned above. Also from the simulation results obtained it is quite evident that for a single user case, the MFSK system outperforms the DS-CDMA system at similar data rates.

This keynote discusses the behavior of noise in indoor power line communications (PLC) channels. Some ideas to improve system performance based on the knowledge of PLC noise are also introduced. The power-line noise at an outlet is the sum of noise waveforms produced and emitted to the lines from the appliances connected to the power-line network. In the design and the analysis of wireless communication systems, stationary additive white Gaussian noise (AWGN) is often assumed. In PLC systems, however, the statistical behavior of the man-made noise is quite different from that of the stationary AWGN. The fact that the noise in power-lines is not AWGN is often believed to be a cause of low quality of communications. However, Gaussian is the distribution of the largest entropy, and communications under non-Gaussian noise may achieve better performance if the system is designed to adapt the noise statistics. In other words, PLC systems retain large potential for performance improvement if the behavior of the noise is clarified and taken into account in the system design. For narrow-band indoor PLC, we have a mathematically tractable and accurate model based on experimental measurements. In this model, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power-line noise can be described in close form formula with a small set of parameters. In wide-band indoor PLC, we have made measurements with high speed sampling (50MHz) with long observation duration (10.4s).

The characteristics of the power-line communication (PLC) channel are difficult to model due to the heterogeneity of the networks and the lack of common wiring practices. To obtain the full variability of the PLC channel, random channel generators are of great importance for the design and testing of communication algorithms. In this respect, we propose a random channel generator that is based on the top-down approach. Basically, we describe the multipath propagation and the coupling effects with an analytical model. We introduce the variability into a restricted set of parameters and, finally, we fit the model to a set of measured channels. The proposed model enables a closed-form description of both the mean path-loss profile and the statistical correlation function of the channel frequency response. As an example of application, we apply the procedure to a set of in-home measured channels in the band 2-100 MHz whose statistics are available in the literature. The measured channels are divided into nine classes according to their channel capacity. We provide the parameters for the random generation of channels for all nine classes, and we show that the results are consistent with the experimental ones. Finally, we merge the classes to capture the entire heterogeneity of in-home PLC channels. In detail, we introduce the class occurrence probability, and we present a random channel generator that targets the ensemble of all nine classes. The statistics of the composite set of channels are also studied, and they are compared to the results of experimental measurement campaigns in the literature.

It has been shown that power line communication (PLC) in the high frequency (HF) band is a feasible data transmission method for a future smart grid concept — a low-voltage direct current (LVDC) distribution system. Furthermore, PLC is proposed as a basis of the data network architecture in the LVDC system. In the analysis of the communication channel characteristics and the design of the communication system, channel modeling plays an essential role. A PLC channel model in the LVDC system is presented and analyzed in this paper. The channel model is implemented with a circuit simulator, which provides several advantages for the modeling; for instance, channel characteristics can be analyzed and modeled both in the time and frequency domain. In this paper, the PLC channel gain (including signal attenuation in the power cable) in the LVDC system is modeled in the frequency domain. The channel model is verified by and compared with measurements carried out in the PLC channel in an LVDC laboratory system.

This Keynote discusses the behavior of indoor power line communications (PLC) channels when used for broadband transmission. The focus is put on the channel response characteristics and, particularly, on its time variant character. In order to create a model for a certain communication channel two strategies can be adopted. The first one is to define a structural model, based on the knowledge of the physical properties of the medium. In our case, they are: the power grid layout, the kind of wires installed, the devices connected to them and the points where transmitter and receiver are placed. From this point, a behavioral model can be derived, by calculating the transmission line parameters of the different sections of wire, the transmission matrices and, finally, the channel frequency response. That is a bottom-up approach, increasing the level of abstraction. The second one is to define directly a behavioral model, which is a simplified representation of the expected channel in a statistical sense. It should be based on some prior knowledge of the medium nature to adopt a clever mathematical model. Then, an extensive measurement campaign has to be carried out on different scenarios to adjust the statistical parameters of the model. That is to follow a top-down approach. The second kind of modeling is traditional in wireless channels. For instance, in GSM an impulse response with few echoes is assumed, and the statistical parameters are selected according to the scenario.

Low voltage, in-home power-line communications (PLC) networks allow direct communication between smart meters (SM) and in-home devices (IHD). In order to minimize security issues, in many deployment scenarios transmission takes place only towards the IHD to display consumption data, with no backwards channel. As a result, channel estimation is difficult and it is necessary to use robust transmission techniques to mitigate the effect of the impulsive noise within the PLC channel. Performance of such system must be evaluated by taking into account realistic interference and channel models for a broad range of configurations. In this work we focus on performance in terms of bit error rate (BER) of a narrowband PLC (NB-PLC) operating in the CENELEC-C band (125–140 kHz) taking into account realistic noise models. Our system is based on binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) modulation.

Exponential demand for broadband applications has elicited renewed interest in characterizing noise in power line communication (PLC) networks for optimal error performance analysis. PLC is economical and ubiquitous, however due to multipath phenomena and nonstationary impulsive noise, the PLC channel is very harsh to signal transmission. Recent studies reveal that PLC noise is cyclostationary and modelling its characteristic should exploit the spectral and temporal redundancy. In addition, preliminary research shows that PLC noise exhibits self-similarity and can be predicted by fractal theory. In modelling noise employing fractal theory, the Hausdorff dimension (D) needs to be approximated. D is related to Hurst parameter (H), which is a measure of self-similarity. Hence, it is important to estimate H for accurate noise prediction using fractal theory. H parameter estimators assume stationarity in time series data. Therefore, preprocessing is required for the case of PLC noise before estimating H to make it stationary as periodicity and nonstatioanrity affects the H estimators. In this study, we remove the periodicity hidden in the PLC noise obtained from measurement campaign within several university offices, workshops and laboratories. Then long-range dependence is estimated from this pre-processed noise data by employing three estimation algorithms: R/S (rescaled adjusted range) method, aggregated variance method and absolute values of aggregated series method. Results from the said estimation methods though not the same, show that the Hurst parameters obtained from various noise measurements are greater than 0.5, implying presence of self-similarity with long-term memory. Results from this study will find valuable applications in PLC noise modelling using fractal and chaos theory and in error performance analysis in both narrowband and broadband PLC systems.

In this paper, we present a capacity analysis for broadband power line communication (PLC) channels, impaired by the Bernoulli–Gaussian impulsive noise, exploiting both orthogonal frequency division multiplexing (OFDM) and single‐carrier frequency‐domain equalisation (SC‐FDE) techniques. First, we investigate point‐to‐point communications and formulate the continuous signal model for OFDM and SC‐FDE techniques in PLC environments and find the tight bounds derived for differential entropy of the non‐Gaussian noise samples. Capacity bounds and a certain capacity result for point‐to‐point PLC systems are also computed. Then, we analyse the capacity in the presence of a relay terminal between the transmitter and the receiver. In this part, we assume correlated noises between the relay and the receiver and derive general upper bound and achievable rate using partial decode‐and‐forward coding strategy for PLC channels. We also show that the obtained bounds coincide in degraded and reversely degraded special cases. Finally, using two statistical divergences, we compare the distances of the Bernoulli–Gaussian and Middleton class A noise models from the normal distribution of their background part and show that the Middleton class A noise is nearer to the Gaussian background noise than the Bernoulli–Gaussian. Therefore, the capacity curve for Middleton class A noise is between the capacity for the Gaussian background noise and the obtained capacity for the Bernoulli–Gaussian model. The obtained capacity theorems are also illustrated numerically. Copyright © 2014 John Wiley & Sons, Ltd.

We investigate the use of Low Rank Parity Check Codes (LRPC), originally designed for cryptography applications in the context of Power Line Communication (PLC). Particularly we propose a new code design and an efficient probabilistic decoding algorithm. The main idea of decoding LRPC codes is based on calculations of vector spaces over a finite field F q . This family of codes can be seen as the equivalent of classical LDPC codes for the rank metric. We compare the performance of this code against the Reed-Solomon Code (RS) through a PLC channel. We show by simulation that the proposed system outperforms the traditional scheme where the PLC channel is subjected to both impulsive noise and narrowband interference.

Power-line communication (PLC) networks have been increasingly used for constructing industrial IoT (internet of things) and home networking systems due to their low-cost installation and broad coverage feature. To guarantee the transmission reliability, ARQ (automatic repeat request) scheme is introduced into the link layer of reliable PLC networks, which allows the retransmission of a data frame several times so that it has a higher probability to be correctly received. However, current studies of performance analysis for PLC MAC (medium access control) protocol (i.e., IEEE 1901) do not take into account of the impact of ARQ scheme. To resolve this problem, we propose an analytical model to investigate the MAC performance of IEEE 1901 protocol for reliable PLC networks with ARQ scheme. In the modeling process, we first establish a PLC channel model to reflect the impacts of PLC channel types (containing Rayleigh fading and Log-normal fading), additive non-Gaussian noise feature and ARQ scheme on data transmission at link layer. Next, we employ Renewal theory and Queueing dynamics to capture the transmission attempt behavior of executing IEEE 1901 protocol in the unsaturated environment with finite transit buffer size. On the basis of combining these two models, we derive the closed-form expressions of 1901 MAC metrics considering the influence of the ARQ scheme. Furthermore, we prove that the proposed analytical model has the convergence property. Finally, we evaluate the MAC performance of 1901 protocol for reliable PLC networks with ARQ scheme and verify the proposed analytical model.

Power Line Communications (PLC) is regarded as the promising home networking technology for smart grid application since the PLC technology enables data transmission via the existing power line. The cooperation between PLC and Wireless Local Area Network (WLAN) will be an effective hybrid solution for Home Area Networks (HANs). In this paper, we consider that Transmission Control Protocol (TCP) packets are transmitting in heterogenous communications network based on PLC and WLAN. The existing TCP congestion control has low effectiveness due to the error-prone power line channel. Therefore, we propose an adaptive rate control to improve TCP performance in the hybrid PLC/WLAN HANs. We exploit the communications mechanism of WLAN to improve the PLC link utilization. The methodology of Heuristic Dynamic Programming (HDP) is employed to obtain the optimal rate policy. The bottleneck link capacity is estimated by neural network training. The sending rate is adapted according to the long-term quality of service (QoS) of applications. Simulation results illustrate that the proposed rate control effectively filters out the negative impact from the instantaneous impulse noise in PLC channel and outperforms the existing TCP.

The reliability and distance of Power Line Communication (PLC) are the most important factors, which limit the application of PLC in practice seriously. This paper discusses the specialties and the methods of building up the PLC networks, uses an improved Dynamic Ant Colony System algorithm (DACS) in dynamic routing of PLC networks, and the multi-path storage technology is given. The improved DACS enhanced the accuracy and efficiency of dynamic routing in two aspects, that is the best tours and the worst tours. A dynamic penalty on worst tours will open up chances for ants to navigate, limit intentions and provide cautions in an ant's decision to move. And ants can get better search guidance by concentrating only the best tours from all groups. The simulation and experimentation indicate that the improved DACS provides an effective dynamic routing method for the expansion of PLC. It is an effective method of improving the reliability of PLC.