Coded-OFDM for PLC systems in non-Gaussian noise channels

PhD ThesisNowadays, power line communication (PLC) is a technology that uses the power line grid for communication purposes along with transmitting electrical energy, for providing broadband services to homes and offices such as high-speed data, audio, video and multimedia applications. The advantages of this technology are to eliminate the need for new wiring and AC outlet plugs by using an existing infrastructure, ease of installation and reduction of the network deployment cost. However, the power line grid is originally designed for the transmission of the electric power at low frequencies; i.e. 50/60 Hz. Therefore, the PLC channel appears as a harsh medium for low-power high-frequency communication signals. The development of PLC systems for providing high-speed communication needs precise knowledge of the channel characteristics such as the attenuation, non-Gaussian noise and selective fading. Non-Gaussian noise in PLC channels can classify into Nakagami-m background interference (BI) noise and asynchronous impulsive noise (IN) modelled by a Bernoulli-Gaussian mixture (BGM) model or Middleton class A (MCA) model. Besides the effects of the multipath PLC channel, asynchronous impulsive noise is the main reason causing performance degradation in PLC channels. Binary/non-binary low-density parity check B/NB-(LDPC) codes and turbo codes (TC) with soft iterative decoders have been proposed for Orthogonal Frequency Division Multiplexing (OFDM) system to improve the bit error rate (BER) performance degradation by exploiting frequency diversity. The performances are investigated utilizing high-order quadrature amplitude modulation (QAM) in the presence of non-Gaussian noise over multipath broadband power-line communication (BBPLC) channels. OFDM usually spreads the effect of IN over multiple sub-carriers after discrete Fourier transform (DFT) operation at the receiver, hence, it requires only a simple single-tap zero forcing (ZF) equalizer at the receiver. The thesis focuses on improving the performance of iterative decoders by deriving the effective, complex-valued, ratio distributions of the noise samples at the zeroforcing (ZF) equalizer output considering the frequency-selective multipath PLCs, background interference noise and impulsive noise, and utilizing the outcome for computing the apriori log likelihood ratios (LLRs) required for soft decoding algorithms. On the other hand, Physical-Layer Network Coding (PLNC) is introduced to help the PLC system to extend the range of operation for exchanging information between two users (devices) using an intermediate relay (hub) node in two-time slots in the presence of non-Gaussian noise over multipath PLC channels. A novel detection scheme is proposed to transform the transmit signal constellation based on the frequency-domain channel coefficients to optimize detection at the relay node with newly derived noise PDF at the relay and end nodes. Additionally, conditions for optimum detection utilizing a high-order constellation are derived. The closedform expressions of the BER and average BER upper-bound (AUB) are derived for a point-to-point system, and for a PLNC system at the end node to relay, relay to end node and at the end-to-end nodes. Moreover, the convergence behaviour of iterative decoders is evaluated using EXtrinsic Information Transfer (EXIT) chart analysis and upper bound analyses. Furthermore, an optimization of the threshold determination for clipping and blanking impulsive noise mitigation methods are derived. The proposed systems are compared in performance using simulation in MATLAB and analytical methods.Ministry of Higher Education in Ira

Fifty Years of Noise Modeling and Mitigation in Power-Line Communications.

Building on the ubiquity of electric power infrastructure, power line communications (PLC) has been successfully used in diverse application scenarios, including the smart grid and in-home broadband communications systems as well as industrial and home automation. However, the power line channel exhibits deleterious properties, one of which is its hostile noise environment. This article aims for providing a review of noise modeling and mitigation techniques in PLC. Specifically, a comprehensive review of representative noise models developed over the past fifty years is presented, including both the empirical models based on measurement campaigns and simplified mathematical models. Following this, we provide an extensive survey of the suite of noise mitigation schemes, categorizing them into mitigation at the transmitter as well as parametric and non-parametric techniques employed at the receiver. Furthermore, since the accuracy of channel estimation in PLC is affected by noise, we review the literature of joint noise mitigation and channel estimation solutions. Finally, a number of directions are outlined for future research on both noise modeling and mitigation in PLC

On Performance Characterization of Cascaded Multiwire-PLC/MIMO-RF Communication System

The flexibility of radio frequency (RF) systems and the omnipresence of power cables potentially make the cascaded power line communication (PLC)/RF system an efficient and cost-effective solution in terms of wide coverage and high-speed transmission. This letter proposes an opportunistic decode-and-forward (DF)-based multi-wire/RF relaying system to exploit the advantages of both techniques. The outage probability, bit error rate, and system channel capacity are correspondingly chosen to analyze the properties of the proposed system, which are derived in closed-form expressions and validated via Monte-Carlo simulations. One can observe that our proposed system outperforms the wireless-only system in terms of coverage and data rate, especially when there exists a non-line-of-sight (NLoS) connection between the transmitter and receiver pair.Comment: 5 pages, 4 figure

Communication Technologies for Smart Grid: A Comprehensive Survey

With the ongoing trends in the energy sector such as vehicular electrification and renewable energy, smart grid is clearly playing a more and more important role in the electric power system industry. One essential feature of the smart grid is the information flow over the high-speed, reliable and secure data communication network in order to manage the complex power systems effectively and intelligently. Smart grids utilize bidirectional communication to function where traditional power grids mainly only use one-way communication. The communication requirements and suitable technique differ depending on the specific environment and scenario. In this paper, we provide a comprehensive and up-to-date survey on the communication technologies used in the smart grid, including the communication requirements, physical layer technologies, network architectures, and research challenges. This survey aims to help the readers identify the potential research problems in the continued research on the topic of smart grid communications

Caractérisation et modélisation du canal et du bruit pour les réseaux CPL MIMO domestiques

Power Line Communication (PLC) technology provides the omnipresence of high speed data services without requiring the installation of new infrastructure. The existing household electrical wiring which is used to deliver the electrical energy to the house is utilized by the PLC technology as a transmission channel. The data rates of several hundreds of Mbps are realized by the PLC technology. In most developed countries the cable used for household electrical wiring consists of three wires: Phase (P), Neutral (N) and Protective Earth (PE). The existing PLC systems use the P-N port to transmit and receive the signals. It is a typical single input single output (SISO) transmission. The inclusion of the PE wire at transmit and receive outlets leads to the availability of multiple transmit/receive ports which in turn leads to the realization of a MIMO communication channel. The principle objective of this thesis is to study and explore the inhome PLC channels in the MIMO context. The main objectives of the thesis are categorized as the following: ¿ Development of a channel sounding protocol to perform extensive channel and noise measurements on the inhome PLC networks, with the objective of generating a rich and realistic database. Evaluation of the MIMO PLC channel capacity by utilizing the database obtained from the measurements. ¿ Characterization and modeling of the inhome MIMO PLC channel through a set of parameter by utilizing the measured channel data. Evaluation of the performance of the channel model by comparing the simulated channels parameters with the measured ones. ¿ Characterization and modeling of the MIMO power line noise through various parameters by utilizing the measured noise data. Evaluation of the performance of the noise model by comparing the simulated noise characteristics with the measured noise.La technologie Courants Porteurs en Ligne (CPL) répond aux besoins de couverture des services à haut débit sans nécessiter l'installation de nouvelle infrastructure. Dans la plupart des pays développés, le câble utilisé pour construire le réseau domestique d'énergie est constitué de trois fils : le fil de Phase (P), le fil de Neutre (N) et le fil de Terre (en anglais, Protective Earth, PE). Les systèmes CPL actuels utilisent les fils P et N (que l'on notera port P-N) pour émettre et recevoir des signaux de manière différentielle. Typiquement, il s'agit d'un mode transmission utilisant un capteur à l'émission et un capteur à la réception, ce que l'on nomme généralement transmission Single Input Single Output (SISO). Dans le domaine de la communication sans fil, les techniques Multiple Input Multiple Output (MIMO) sont largement employées pour augmenter la capacité du canal. Elles consistent à utiliser plusieurs antennes à l'émission et plusieurs antennes à la réception et bénéficier ainsi de la diversité du canal. Dans le contexte CPL, la présence du fil PE dans les prises électriques de transmission et de réception permet d'envisager la possibilité d'utiliser plusieurs ports d'émission et de réception, ce qui constitue un canal de communication MIMO. Des mesures et des simulations réalisées pour les canaux de transmission CPL ont montré une nette augmentation de la capacité du canal en utilisant les techniques MIMO par rapport aux systèmes traditionnels SISO. L'objectif principal de cette thèse est l'étude et l'exploration des canaux CPL domestiques dans le contexte MIMO. Il s'agit d'une étude détaillée des technologies CPL existantes et d'une investigation des caractéristiques des canaux CPL MIMO. Les objectifs principaux de la thèse sont : Le développement d'un protocole de sondage afin de réaliser des mesures intensives du canal de transmission et du bruit électromagnétique sur les réseaux CPL domestiques. L'objectif est de générer une base de données riche et réaliste. La base de données obtenue par les mesures permettra d'évaluer la capacité du canal CPL MIMO. La caractérisation et la modélisation du canal de transmission CPL MIMO domestique via un ensemble de paramètres, en utilisant les mesures de canal obtenues par la campagne de mesure. La performance du modèle de canal sera évaluée par la comparaison entre les canaux simulés et les canaux mesurés. La caractérisation et la modélisation du bruit électromagnétique CPL MIMO via plusieurs paramètres, en utilisant les mesures de bruit obtenues par la campagne de mesure. La performance du modèle de bruit sera évaluée par la comparaison entre le bruit simulé et le bruit mesuré

Channel modelling and relay for powerline communications

The thesis discusses the channel modelling and relay techniques in powerline communications (PLC) which is considered as a promising technology for the Smart Grid communications, Internet access and home area network (HAN). In this thesis, the statistical PLC channel characteristics are investigated, a new statistical channel modelling method is proposed for the in-door PLC. Then a series of the relay protocols are suggested for the broadband communications over power grid. The statistical channel modelling method is proposed to surmount the limits of the traditional deterministic PLC channel models such as multipath model and transmission line model. To develop the channel model, the properties of the multipath magnitudes, interval between the paths, cable loss and the channel classification are investigated in detail. Then, each property is described by statistical distribution or formula. The simulation results show that the statistical model can describe the PLC channels as accurate as deterministic models without the topology information which is a time-consuming work for collecting. The relay transmission is proposed to help PLC adapting the diverse application scenarios. The protocols covers the main relay aspects which include decode/amplify forwarding, single/ multiple relay nodes, full/half duplex relay working mode. The capacity performance of each protocol is given and compared. A series of the facts which improve the performance of the PLC networks are figured out according to simulation results. The facts include that the decode-and-forward is more suitable for the PLC environment, deviation or transforming station is better location for placing relay node and full duplex relay working mode help exploiting the capacity potential of the PLC networks. Some future works are pointed out based on the work of statistical channel model and relay. In the last part of this thesis, an unit based statistical channel model is initialled for adapting various PLC channel conditions, a more practical relay scenario which contains multiple data terminals is proposed for approaching the realistic transmission scenario. At last, the relay for the narrowband PLC Smart Grid is also mentioned as future research topic

Resource allocation technique for powerline network using a modified shuffled frog-leaping algorithm

Resource allocation (RA) techniques should be made efficient and optimized in order to enhance the QoS (power & bit, capacity, scalability) of high-speed networking data applications. This research attempts to further increase the efficiency towards near-optimal performance. RA’s problem involves assignment of subcarriers, power and bit amounts for each user efficiently. Several studies conducted by the Federal Communication Commission have proven that conventional RA approaches are becoming insufficient for rapid demand in networking resulted in spectrum underutilization, low capacity and convergence, also low performance of bit error rate, delay of channel feedback, weak scalability as well as computational complexity make real-time solutions intractable. Mainly due to sophisticated, restrictive constraints, multi-objectives, unfairness, channel noise, also unrealistic when assume perfect channel state is available. The main goal of this work is to develop a conceptual framework and mathematical model for resource allocation using Shuffled Frog-Leap Algorithm (SFLA). Thus, a modified SFLA is introduced and integrated in Orthogonal Frequency Division Multiplexing (OFDM) system. Then SFLA generated random population of solutions (power, bit), the fitness of each solution is calculated and improved for each subcarrier and user. The solution is numerically validated and verified by simulation-based powerline channel. The system performance was compared to similar research works in terms of the system’s capacity, scalability, allocated rate/power, and convergence. The resources allocated are constantly optimized and the capacity obtained is constantly higher as compared to Root-finding, Linear, and Hybrid evolutionary algorithms. The proposed algorithm managed to offer fastest convergence given that the number of iterations required to get to the 0.001% error of the global optimum is 75 compared to 92 in the conventional techniques. Finally, joint allocation models for selection of optima resource values are introduced; adaptive power and bit allocators in OFDM system-based Powerline and using modified SFLA-based TLBO and PSO are propose

Noise modeling for standard CENELEC A-band power line communication channel

Power line communications (PLC) usage of low-voltage electrical power supply network as a medium of communication provides an alternative for the telecommunication access and in-house communication. Historically, power lines were majorly used for controlling appliances, however, with recent technology advancements power lines are now able to compete favorably and successfully with other relatively stable home automation and networking technologies like fixed line and wireless. Regardless of the advantages PLC has to offer, like every other communication technology, it has its own technical challenges it must overcome to be fully deployed and maximize its full potential. Such challenges includes noise, which can originate from appliances connected across the network or can be coupled unto the network. Harmful interference to other wireless spectrum users such as broadcast stations, and signal attenuation are other challenges faced by usage of the power line as a communication medium. PLC suffers the risk of not living up to its full development as a reliable means of communication if proper understanding of the channel potential and characteristic is not known. Therefore, understanding of the channel potential and characteristics can be obtained through measurement and modeling of the PLC channel. This model and measurements of the channel characteristics can then be utilized in designing a good PLC system which is able to withstand and mitigate the effect of the different kind of noise and disturbance present on the PLC network. This research therefore aims at formulizing and modeling the error pattern/behavior of noise and disturbances of an in-house CENELEC A-band based on experimental measurements. This is achieved by carrying out a real time experimental measurement of noise over a complete day to show the noise behavior. Error sequences are then generated from the measurement for the different classes of noise present on the CENELEC A-band and the use of Fritchman model, a Markovian chain model, is then employed to model the CENELEC A-band channel. This involves the use of Baum-Welch algorithm (an iterative algorithm) to estimate the model parameters of the three-state Markovian Fritchman model assumed. This precise channel model can then be used to design a good PLC system and facilitate the design of efficient coding and/or modulation schemes to enhance reliable communication on the PLC network. Therefore, answering the question of “how to formulize and model the error pattern/behavior of noise and disturbances of an in-house CENELEC A-band based on experimental measurements”