Communications over electrical power lines (PLs) is an old idea that dates back to the early 1900’s, when the first patents were filed in this area[1]. Actually, as technology matured, there are many types and different classifications of Power Line Telecommunications (PLT) systems.

The two main types of PLT systems are the “access PLT” that covers the “last mile” between the electricity supply sub-station and the user, and the other is called “indoor PLT” – which aims to distribute data (coming for example from access PLT or Digital Subscriber Line) within building via the electricity sockets[2]. In indoor applications two different system types could be used – Single Input, Single Output (SISO) PLT in which the phase (live) and the neutral wire are used, and Multiple Input, Multiple Output (MIMO) PLT in which additionally the ground wire is in use. Furthermore, there are two generations of PLT systems: Initial PLT systems, using frequencies up to 80 MHz and offering less than 100 Mbit/s bitrate and new high speed PLT systems, using frequencies up to 300 MHz and offering up to 1 Gbit/s bitrate.

 

At the present time there is a considerable number of chipsets for PLT systems available on the market, and this fact allows not only multinational giant firms, but also SMEs (Small and Medium sized Enterprises) to get involved in the design and production of such systems.

One of the main issues that arise from the use of these systems is that the electrical power lines used by PLT systems are not designed for Data communications and consequently not shielded. Therefore part of the energy injected by the PLT system into the electrical network is radiated, resulting in a huge mesh antenna. Initially, serious electromagnetic compatibility issues caused interference with licensed radio broadcast reception. Nowadays, in addition the coexistence of PLT systems with wireless (Wi-Fi or ZigBee) and high speed digital subscriber lines (VDSL-2 or G.Fast), data transmission shall be considered. However, the lack of specifications or standards for PLT means that PLT equipment placed on the market does not take into account the necessary protection requirements for this coexistence.

For this reason, standardisation work has been reactivated both at European and international level. At European level, the applicable regulation for PLT equipment is the Electromagnetic Compatibility (EMC) Directive 2014/30/EU, that repealed in 2016 the EMC Directive 2004/108/EC. In 2009, the European Standardisation Organisations CENELEC and ETSI were asked by the European Commission to start developing new standards for PLT taking into account the new technologies, services and industrial needs.

In response, ETSI addressed this enquiry to its existing Technical Committee (TC) with the same name Power Line Telecommunications (PLT), which has published various technical requirements and specifications since the year 2000. In recent years, a convergence between the work of TC PLT and TC ATTM (Access, Terminals, Transmission and Multiplexing) was observed and starting from 2015 several joint meetings between the two committees have been organised. The final decision was that the committees shall merge and at the plenary meeting of the ETSI Board, held in September 2017, it was noted the closure of TC PLT (Power Line Telecommunications) and the transfer of the ongoing work programme under TC ATTM (Access, Terminals, Transmission and Multiplexing).

This decision naturally affected the work programmes and the Terms of Reference (ToR) of some of the workgroups in TC ATTM. Workgroup ATTM TM6 (Transmission and Multiplexing No. 6) already included in its programme the draft of TS 103 452: ”Test Specification for Co-Existence mechanism between PLT and VDSL2/G.Fast” and added to its ToR the responsibility over the standardisation of the in-building Power Line Telecommunications (PLT) systems. In similar way, the working group ATTM SDMC (Sustainable Digital Multiservice Cities) added a new point in its ToR: “Standardisation works on Power Line Telecommunications (PLT) systems inside public buildings and communication between public buildings and furniture”.

At the plenary meeting of ETSI TC ATTM, held in November 2017, the new work programmes and the updated ToRs of both of the working groups have been approved. In this way, a complete new field of work started for the development of standards within this committee.

 

 

 

[1] Galli et al. , 2011. For the Grid and Through the Grid: The Role of Power Line Communications in the Smart Grid. Online available at https://arxiv.org/pdf/1010.1973.pdf

[2] EBU Technical, 2010. Power Line Telecommunications (PLT). Online available at https://tech.ebu.ch/docs/tech-i/ebu_tech-i_005.pdf