Regulation occurs on local, regional, national and worldwide levels. There are regulatory bodies such as the IEC or FCC, there are standards-making entities such as CENELEC, CISPR and ETSI and there are national and local authorities that control regulations on a political level.
Powerline is a product re-using existing networks that were not designed for such use, in dimensions that were neither foreseen nor intended for those networks. Regulation tries to cover the new issues resulting from the Powerline overlay over the existing networks.
For the purposes of regulation, there are emissive (radiation) aspects that come into play because an RF modulation is used on the electric networks and RF radiates as those networks are neither perfectly terminated and adapted coaxial conductors, nor perfectly matched antenna structures.
Here the argument is crucial if the resulting radiation is “unintentional” or “intentional”. If it is held to be unintentional, then it is subject to existing regulations as “RF frequency noise”. The regulator has set fairly stringent values that RF noise must not exceed (dependent on frequency). Those values are so low that for Powerline applications, given the “leaky” network structures, modulation levels that are permissible no longer give an adequate range of transmission on the networks. An albeit costly remedy is to use repeaters to increase the range.
Most countries take the values established internationally and then add their own “safety pillow” of extra restrictions just to be on the safe side. For that reason, the FCC Part 15 in the US can specify relatively lenient values (that the Powerline industry could live with) while a country like the UK can have much more stringent values that are absolutely prohibitive for Powerline applications.
More and more, Powerline engineers in Europe suggest that a good solution would be to adopt the FCC Part 15 levels world wide. But, so far, standards organizations remain opposed to this idea.
In Europe we shall see “harmonised” standards eventually that apply to all EC members. The EC is reviewing this area of rule making actively. Alas, that will take some time, experts expect such standards now for 2004 or later.
Regulatory activity, especially standard making, is a painfully slow process. It takes years before new regulation can be applied. Some countries have, either tacitly or by legal action, jumped the gun and have given the Powerline industry some temporary laws to operate until regulation kicks in.
The NB30 law in Germany was passed on March 30, 2001 and legalised Powerline applications in Germany. Ascom claimed that all their systems abided by NB30. This was the basis for the strong activity by RWE in Germany in 2001/2002, RWE has now exited that market, only the systems in Mannheim (Main.Net) and those implemented by EnBW in the south remain.
Sweden took the tacit approach. Where there is no plaintiff there does not need to be a judge. If nobody complains about RF interference, then there is no reason to set up and enforce restrictions.
Austria ruled in July 2001 that the Powerline industry could go ahead, as long as they would abide by all applicable regulation of the EC. That was an ambigous political statement. No regulations of the EC were immediately applicable, but those in the offing would be prohibitively stringent. There were several pockets of market activity in Austria, by EVN, by the City of Linz and by TIWAG in Tyrol. In all cases the number of connected customers remained relatively small.
So what applicable regulation, akin to the German NB30, does the EC have? None, so far. A mandate for CENELEC exists to develop PLC standards. The Commission did not object to PLC, thus tacitly accepted it. Moreover, the European Parliament recognized PLC as an accepted legal way of electronic communications (wire based broadband systems).
Radiation is not the only concern of the regulators. Certain regulations pertaining to conductive modes of electricity can also be applied, particularly since we are dealing with electric networks that are based on conduction.
The standard EN50083 is for cable based systems and can be construed to apply to Powerline systems. The CENELEC standard EN55022 set limits for the voltage or current on a conductor, in a given frequency range. Network structures that represent ill-matched antennas for RF frequencies are then governed by another set of rules and restrictions.
A way will have to be found to write rules consistent with and harmonised with a set of regulations that have all been made before we had PLC, but specifically adapted to the requirements of the Powerline technology.
On a practical level, electromagnetic radiation, for instance permissible under NB30, cannot be actually generated on the network on the grounds of conductive electrical restrictions that come from EN55022. That impacts the permissible modulation voltage, which via the network impedance (that is variable in the frequency range of interest) gives us the modulation power. Thus, regulations coming from different regulatory areas are also not compatible.
EN55022 is a European standard. Complying with it in Powerline applications means that a reasonable business on that basis is all but impossible. Regulatory relief is therefore very much needed.
The question of coexistence continues to be the most important issue for the standard making bodies if Powerline is going to be a viable mass deployed technology. Standards making bodies have been working on this issue for more than a year now.
Coexistence means that in-house systems can coexist with access systems without mutual interference; that in-house systems can coexist with other in-house systems nearby without interference…
The method adopted for in-house to access coexistence is the frequency band split. The frequency spectrum is split into a lower area (below perhaps 10 – 12 MHz) for the use of access systems, and the rest above the split point for in-house systems. This method implies that a narrower frequency band is available for each of the two application areas, therefore less information throughput, perhaps 7 – 8 Mb/s may ultimately be expected for access, and even less for in-house. The modulation levels will have to be about 10 dB lower for the higher frequency band, as more radiation is expected there.
It continues to take an enormous effort and require great vigilance by all of the Powerline protagonists to collectively influence and control the standards making activities such that regulation of a particular, pertinent aspect, does not inadvertently go into a direction that may be adverse to the future viability of Powerline.