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