Introduction

As part of the studies on the compatibility between radiocommunication systems and high data rate telecommunication systems using electricity power supply or telephone distribution wiring (Question ITU-R 221/1), this Report covers the use of the radio spectrum and associated protection requirements of radiocommunication services in respect to impact of power line telecommunications (PLT) in the VHF and UHF bands. It complements Report ITU-R SM.2158 which already provides information and guidance for the frequency bands from the LF bands up to about 80 MHz.

Recent developments of PLT technology show that PLT systems can use frequencies going far beyond 80 MHz. Future technological developments may even make the use of frequencies in the UHF bands possible for PLT.

There are presently two main families of PLT applications:

– Access (outdoor) PLT whose target market is the last mile (i.e. 1.2 km) between the electricity supply substation and the subscriber and could be therefore an alternative means of access to the telecommunication local loop.

– Indoor PLT whose aim is to distribute signals (coming for example from access PLT from DSL or even from data sources within homes and without connection to an access network) to the mains electricity socket outlets inside buildings.

According to the information available, frequencies above 80 MHz are currently only used by indoor PLT systems.

The ITU-T Recommendation G.9960 (06/2010) – Unified high-speed wire-line based home networking transceivers – System architecture and physical layer specification, contained a physical layer specification for such PLT systems using frequencies up to 100 MHz. This version merged 3 previously approved ITU-T Recommendations: G.9960 Foundation (2009), ITU-T G.9960 Amendment 1 (2009) and ITU-T G.9960 Corrigendum 1 (2009). The 100 MHz power line base-band profile has been modified to reduce the upper frequency limit from 100 MHz to 80 MHz. It is expected that further cooperation between ITU-R and ITU-T should allow a reconsideration of this frequency limitation in ITU-T Recommendation G.9960.

It should be noted that there are already indoor PLT systems on the market which follow other specifications than Recommendation ITU-T G.9960 and use frequencies going up to about 300 MHz or even beyond.

Such PLT indoor systems potentially offer transmission rates of several hundred Mbit/s via the normal electrical power wiring inside every building. HD-film streaming and online-gaming in the home are applications which may require such transmission rates. The implementation of such PLT systems and their technical characteristics can vary considerably.

Because electrical power lines are not designed for the transmission of high data rate signals, PLT signals on electrical power lines have the potential of causing interference to radiocommunication services.

Radio Regulations (RR) No. 15.12 requires that: "Administrations shall take all practicable and necessary steps to ensure that the operation of electrical apparatus or installations of any kind, including power and telecommunication distribution networks, but excluding equipment used for industrial, scientific and medical applications, does not cause harmful interference to a radiocommunication service and, in particular, to a radionavigation or any other safety service operating in accordance with the provisions of these Regulations¹".

This ITU-R Report provides in its Chapter 3 information on radio system characteristics and protection criteria for a lot of possibly impacted radiocommunication systems operating between 80 and 470 MHz. It is intended to extend this ITU-R Report step by step, eventually covering all radiocommunication systems concerned in this frequency range. Depending on the future development of PLT systems, it might become necessary to consider also possible impacts on radiocommunication systems operating above 470 MHz.

"¹ 15.12.1 and 15.13.1 In this matter, administrations should be guided by the latest relevant ITU-R Recommendations."