Powerline Communication in Home-Building Automation Systems

Domotics, Smart Home Systems, Ambient Intelligence are all terms that describe the intelligent cooperation of several different equipments to manage the home environment in an intelligent, safe and comfortable way. The same idea is also applicable to bigger constructions, and in that case it takes the name of Building Automation. Whatever term one wants to use, it refers to a multidisciplinary field that includes informatics, electronics, automation and telecommunication, and also touches fields like building constructions and architecture. In fact, during the process of designing a building, people have to consider appropriate spaces for the electric plant, and if the presence of a domotic system is planned, it is better to take it into account during the design phase, just to optimize spaces, the amount of used wires, the position of the modules and so on. There are really many home system producers in the world (Smart Home Systems, EIB-Konnex, Lonworks, Bticino, Vimar, Duemmegi, EasyDom Corporation, Futurware, Digital Cybermasters, Hills Home Systems, Intellihome etc, just to mention a few) , and their products differ from each others in many characteristics, such as functionality, dimension, weight, typology of installation, materials, net topology, power consumes, aesthetic appearance, communication protocol and communication mean. Regarding this last point, the majority of the domotic systems, especially in Europe, tend to use a dedicated bus cable to exchange data among modules, to make the communication link more robust and reliable. Lately, using radio communication is in fashion, but radio modules, respect to their equivalent standard ones, are more expensive, and in the bargain many people don’t want to use them due to the fear of radio signals (even if it were proved that they are completely harmless). Another communication mean, that is often not taken into account, is the powerline. In point of fact, using the installed poweline wires to send information is a very smart idea: there is no additional cost to install other dozens of meters of wires, there is not the necessity to break the walls and to do building works at home, there are no interferences with other devices (like in the radio communication case) or reflection problems (like in the infrared case), there is the possibility to put the modules in every place (it is sufficient to have an electrical socket in the nearness, or to use an extension cable), there is no need to have an extra power source (usually, in a bus cable domotic system, there is a direct voltage generated by a power supply and distribuited on the whole domotic net). Moreover, powerline communication (PLC, also called BPL in the USA, where the acronym stays for Broadband over Power Line, or NPL, Narroband over Power Line) is not only used in a home environment to create a virtual net among domotic modules, but is also used on the power distribution net to perform actions like reading the electricity meter, monitoring the power consumes and the state of a building, finding faults along the net, detecting illegal electricity usages and to solve the so-called last mile problem , that is the problem related to the final leg of delivering connectivity from a communications provider to a customer. In fact a cheap possibility to cover this final leg is using powerline communication. The intent of this work is therefore to illustrate, going into more details, advantages and disadvantages of the powerline communication systems (PLCS), to show the differences between PLCS for power distribution net and PLCS for home and building environments, to indagate the methods to send data over the powerline, to explain which are the automations that is possible to connect and to control in a powerline domotic system and to show some case studies tackled by the authors

EXPERIMENTAL ACTIVITY AND ANALYSIS OF PLC TECHNOLOGY IN VARIOUS SCENARIOS

Power line communications (PLCs) have become a key technology in the telecommunication world, both in terms of stand-alone technology or a technology that can complement other systems, e.g., radio communications. Since PLCs exploit the existing power delivery grid to convey data signals, the application scenarios are multiple. Historically, PLCs have been deployed in outdoor low voltage (< 1 kV) power distribution networks for the automatic metering and the management of the loads. Today, the evolution of the electrical grid toward an intelligent and smart grid that dynamically manages the generation, the distribution and the consumption of the power makes this technology still relevant in this scenario. Therefore, PLCs have raised significant interest in recent years for the possibility of delivering broadband Internet access and high speed services to homes and within the home. The increase in demand for such services has inspired the research activity in the in-home scenario, both toward the direction of the development of independent or integrated solutions, with respect to already existing technologies. Another application scenario that has not been deeply investigated yet is the in-vehicle one, which includes the in-car, in-plane and in-ship scenario. Since the power grid has not been designed for data communications, the transmission medium is hostile and exhibits high attenuation, multipath propagation and frequency selectivity, due to the presence of branches, discontinuities and unmatched loads. For the proper design of a power line communication (PLC) system, good knowledge of the grid characteristics in terms of propagation channel and disturbances is required. In this respect, we have performed experimental measurement campaigns in all the aforementioned scenarios. We aimed to investigate the grid characteristics from a telecommunication point of view. In this thesis, we present the results of our experimental activity. Firstly, we analyze the outdoor low voltage and industrial scenario. We have carried out a measurement campaign in an artificial network that can resemble either an outdoor low voltage power distribution network or an industrial or marine power system. We have focused on the channel frequency response, the line impedance and the background PLC noise, within the narrow band and the broad band frequency ranges. Then, we focus on the in-home scenario. In this context, we have studied the impact of the electrical devices (loads) connected to the power grid on the PLC medium characteristics and on the quality of the data communication. Their behavior has been investigated both in the time and frequency domain, in terms of load impedance and impulsive noise components that they inject into the network. Finally, we consider in-vehicle PLC, in particular the in-ship and in-car environment. Firstly, we summarize the results of a channel measurement campaign that we have carried out in a large cruise ship focusing on the low voltage power distribution network in the band 0-50 MHz. Thus, we present the results of an entire PLC noise and channel measurement campaign that we have performed in a compact electrical car

A physical overlay framework for insider threat mitigation of power system devices

Nearly every aspect of modern life today, from businesses, transportation, and healthcare, depends on the power grid operating safely and reliably. While the recent push for a “Smart Grid” has shown promise for increased efficiency, security has often been an afterthought, leaving this critical infrastructure vulnerable to a variety of cyber attacks. For instance, devices crucial to the safe operation of the power grid are left in remote substations with their configuration interfaces completely open, providing a vector for outsiders as well as insiders to launch an attack. This paper develops the framework for an overlay network of gateway devices that provide authenticated access control and security monitoring for these vulnerable interfaces. We develop a working prototype of such a device and simulate the performance of deployment throughout a substation. Our results suggest that such a system can be deployed with negligible impact on normal operations, while providing important security mechanisms. By doing so, we demonstrate that our proposal is a practical and efficient solution for retro-fitting security onto crucial power system devices.M.S

Modelling and estimation of PLC channel for smart grid systems

Today’s power grid system has been from the years and has become old and unable to meet the future needs of this generation. In about a decade, our surroundings been digitalized progressively and we are more reliant on electricity than before.Our power grid ought to advance rapidly to adjust the changes that are occurring in our undeniably computerized society. The best answer for this is Smart Grid.They give a more effective, dependable, environment and secure option to our current grid system. Smart grid will be equipped to restore itself after a power outage or a climate related blackout.Smart grids will depend on several new and different innovative technologies. These new technologies will join together with the current grid to make a more productive, efficient and intelligent grid system. Smart grids will depend incredibly on two-way communications. Employing communication technologies into smart grid is difficult task. There is ongoing research for deciding what should be the best communication for smart grid and PLC creates a great interest because, power lines are everywhere and there is no need of installation cost. Power lines will reach to the last mile but problem with it is the noise and this can be reduced by using techniques like OFDM and allows high data rates of data. This model is a combination of communication model, power line model and noise model. The communication model is realized as the OFDM system, power lines are modelled from the transfer function of multipath signal environment and noise model are modelled as white noise. Radial Basis Function (RBF) networks are used to estimate the channel by using gradient decent method

Communications protocols for wireless sensor networks in perturbed environment

This thesis is mainly in the Smart Grid (SG) domain. SGs improve the safety of electrical networks and allow a more adapted use of electricity storage, available in a limited way. SGs also increase overall energy efficiency by reducing peak consumption. The use of this technology is the most appropriate solution because it allows more efficient energy management. In this context, manufacturers such as Hydro-Quebec deploy sensor networks in the nerve centers to control major equipment. To reduce deployment costs and cabling complexity, the option of a wireless sensor network seems the most obvious solution. However, deploying a sensor network requires in-depth knowledge of the environment. High voltages substations are strategic points in the power grid and generate impulse noise that can degrade the performance of wireless communications. The works in this thesis are focused on the development of high performance communication protocols for the profoundly disturbed environments. For this purpose, we have proposed an approach based on the concatenation of rank metric and convolutional coding with orthogonal frequency division multiplexing. This technique is very efficient in reducing the bursty nature of impulsive noise while having a quite low level of complexity. Another solution based on a multi-antenna system is also designed. We have proposed a cooperative closed-loop coded MIMO system based on rank metric code and max−dmin precoder. The second technique is also an optimal solution for both improving the reliability of the system and energy saving in wireless sensor networks

Physical layer security solutions against passive and colluding eavesdroppers in large wireless networks and impulsive noise environments

Wireless networks have experienced rapid evolutions toward sustainability, scalability and interoperability. The digital economy is driven by future networked societies to a more holistic community of intelligent infrastructures and connected services for a more sustainable and smarter society. Furthermore, an enormous amount of sensitive and confidential information, e.g., medical records, electronic media, financial data, and customer files, is transmitted via wireless channels. The implementation of higher layer key distribution and management was challenged by the emergence of these new advanced systems. In order to resist various malicious abuses and security attacks, physical layer security (PLS) has become an appealing alternative. The basic concept behind PLS is to exploit the characteristics of wireless channels for the confidentiality. Its target is to blind the eavesdroppers such that they cannot extract any confidential information from the received signals. This thesis presents solutions and analyses to improve the PLS in wireless networks. In the second chapter, we investigate the secrecy capacity performance of an amplify-andforward (AF) dual-hop network for both distributed beamforming (DBF) and opportunistic relaying (OR) techniques. We derive the capacity scaling for two large sets; trustworthy relays and untrustworthy aggressive relays cooperating together with a wire-tapper aiming to intercept the message. We show that the capacity scaling in the DBF is lower bounded by a value which depends on the ratio between the number of the trustworthy and the untrustworthy aggressive relays, whereas the capacity scaling of OR is upper bounded by a value depending on the number of relays as well as the signal to noise ratio (SNR). In the third chapter, we propose a new location-based multicasting technique, for dual phase AF large networks, aiming to improve the security in the presence of non-colluding passive eavesdroppers. We analytically demonstrate that the proposed technique increases the security by decreasing the probability of re-choosing a sector that has eavesdroppers, for each transmission time. Moreover, we also show that the secrecy capacity scaling of our technique is the same as for broadcasting. Hereafter, the lower and upper bounds of the secrecy outage probability are calculated, and it is shown that the security performance is remarkably enhanced, compared to the conventional multicasting technique. In the fourth chapter, we propose a new cooperative protocol, for dual phase amplify-andforward large wireless sensor networks, aiming to improve the transmission security while taking into account the limited capabilities of the sensor nodes. In such a network, a portion of the K relays can be potential passive eavesdroppers. To reduce the impact of these untrustworthy relays on the network security, we propose a new transmission protocol, where the source agrees to share with the destination a given channel state information (CSI) of source-trusted relay-destination link to encode the message. Then, the source will use this CSI again to map the right message to a certain sector while transmitting fake messages to the other sectors. Adopting such a security protocol is promising because of the availability of a high number of cheap electronic sensors with limited computational capabilities. For the proposed scheme, we derived the secrecy outage probability (SOP) and demonstrated that the probability of receiving the right encoded information by an untrustworthy relay is inversely proportional to the number of sectors. We also show that the aggressive behavior of cooperating untrusted relays is not effective compared to the case where each untrusted relay is trying to intercept the transmitted message individually. Fifth and last, we investigate the physical layer security performance over Rayleigh fading channels in the presence of impulsive noise, as encountered, for instance, in smart grid environments. For this scheme, secrecy performance metrics were considered with and without destination assisted jamming at the eavesdropper’s side. From the obtained results, it is verified that the SOP, without destination assisted jamming, is flooring at high signal-to-noise-ratio values and that it can be significantly improved with the use of jamming

Investigation of Orthogonal Frequency Division Multiplexing Based Power Line Communication Systems

Power Line Communication (PLC) has the potential to become the preferred technique for providing broadband to homes and offices with the advantage of eliminating the need for new wiring infrastructure and reducing the cost. Power line grids, however, present a hostile channel for data communication, since the fundamental purpose of the power line channel was only the transmission of electric power at 50/60 Hz frequencies. The development of PLC systems for providing broadband applications requires an adequate knowledge of the power line channel characteristics. Various types of noise and multipath effects are some of the limitations for power line channels which need to be considered carefully in designing PLC systems. An effect of an impulsive noise characterized with short durations is identified as one of the major impairment in PLC system. Orthogonal Frequency Division Multiplexing (OFDM) technique is one of the modulation approaches which has been regarded as the modulation technique for PLC systems by most researchers in the field and is used in this research study work. This is because it provides high robustness against impulsive noise and minimizes the effects of multipath. In case of impulsive noise affecting the OFDM system, this effect is spread over multiple subcarriers due to Discrete Fourier Transform (DFT) at the receiver. Hence, each of the transmitted communication symbols is only affected by a fraction of the impulsive noise. In order to achieve reliable results for data transmission, a proper power line channel with various noise models must be used in the investigations. In this research study work, a multipath model which has been widely accepted by many researchers in the field and practically proven in the Tanzanian power line system is used as the model for the power line channel. The effects of different scenarios such as variations in direct path length, path number, branch length and load on the channel frequency response are investigated in this research work. Simulation results indicate the suitability of multi-carrier modulation technique such as an OFDM over the power line channels. To represent the actual noise scenario in the power line channel, an impulsive noise and background noise are classified as the two main noise sources. A Middleton class A noise is modelled as an impulsive noise, whereas the background noise is modelled as an Additive White Gaussian Noise (AWGN). The performance of PLC system based on OFDM is investigated under Middleton Class A and AWGN noise scenarios. It is observed that Bit Error Rate (BER) for the impulsive noise is higher than the background noise. Since channel coding can enhance the transmission in a communication system, Block code and convolutional codes have been studied in this research work. The hamming code chosen as a type of the block code, whereas the Trellis Coded Modulation (TCM) selected from the category of the convolutional channel codes and modelled in Matlab2013b. Although TCM code produces improvements in the Signal-to-Noise Ratio (SNR), they do not perform well with Middleton class A noise. A rectangular 16-QAM TCM based on OFDM provides better BER rate compared to the general TCM

Energy efficient multi channel packet forwarding mechanism for wireless sensor networks in smart grid applications

Multichannel Wireless Sensor Networks (MWSNs) paradigm provides an opportunity for the Power Grid (PG) to be upgraded into an intelligent power grid known as the Smart Grid (SG) for efficiently managing the continuously growing energy demand of the 21st century. However, the nature of the intelligent grid environments is affected by the equipment noise, electromagnetic interference, and multipath effects, which pose significant challenges in existing schemes to find optimal vacant channels for MWSNs-based SG applications. This research proposed three schemes to address these issues. The first scheme was an Energy Efficient Routing (ERM) scheme to select the best-optimized route to increase the network performance between the source and the sink in the MWSNs. Secondly, an Efficient Channel Detection (ECD) scheme to detect vacant channels for the Primary Users (PUs) with improved channel detection probability and low probability of missed detection and false alarms in the MWSNs. Finally, a Dynamic Channel Assignment (DCA) scheme that dealt with channel scarcities by dynamically switching between different channels that provided higher data rate channels with longer idle probability to Secondary Users (SUs) at extremely low interference in the MWSNs. These three schemes were integrated as the Energy Efficient Multichannel Packet Forwarding Mechanism (CARP) for Wireless Sensor Networks in Smart Grid Applications. The extensive simulation studies were carried through an EstiNet software version 9.0. The obtained experimental simulation facts exhibited that the proposed schemes in the CARP mechanism achieved improved network performance in terms of packets delivery ratio (26%), congestion management (15%), throughput (23%), probability of channel detection (21%), reduces packet error rate (22%), end-to-end delay (25%), probability of channel missed-detection (25%), probability of false alarms (23.3%), and energy consumption (17%); as compared to the relevant schemes in both EQSHC and G-RPL mechanisms. To conclude, the proposed mechanism significantly improves the Quality of Service (QoS) data delivery performance for MWSNs in SG

Smart Sensor Data Acquisition in trains

Whether for work or leisure, we see a large number of people traveling by train every day. In order to ensure the comfort and safety of passengers, it must be checked whether the composition is working normally. For this purpose, a constant monitoring of a train must be done, followed by a diagnosis of the com-position, prediction of failures and production of alarms in the event of any anomaly. To perform monitoring on a train, it is necessary to collect data from sensors distributed along its carriages and send them to a software system that performs the diagnosis of the composition in a fast and efficient way. The description of the activities necessary for monitoring of a train imme-diately refers to topics such as distributed systems, since the intended system will have to integrate several sensors distributed along the train, or Smart Systems, since each sensor must have the capacity to not only acquire data, but also trans-mit it, preferably, wirelessly. However, there are some obstacles to the implementation of such a system. Firstly, the existence of sources of distortions and noise in the medium interferes both in the acquisition and transmission of data and secondly the fact that the sensors distributed along the train are not prepared to be connected directly to a software system. This dissertation seeks to find a solution for the problems described by im-plementing a data acquisition system that is distributed and takes advantage of the current technologies of low-cost sensor nodes as well as web technologies for sensor networks