Powerline Update

2002 Update on the Powerline Industry

Regulatory Developments

Complexity

The regulatory field is complex. 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 reusing 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.

Emissions

For the purposes of regulation, there are emissive (radiative) 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.

The Chimney Approach

During the past year, various attempts have been made to get some “exceptions” for certain frequency ranges, where higher power levels would be tolerated. One such attempt was called the “chimney” approach originally proposed by Siemens and Ascom.

Since each country has agreed those noise levels on an International basis, it is hard to see how such a country then could grant exceptions. But then, the rules specifying such noise levels have not been made considering the requirements of Powerline.

International / Country Specific

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.

In Europe we shall see “harmonised” standards eventually that apply to all EC members. During the past year, the EC has started to review this area of rule making.

Temporary Laws

The not so good news (for the industry) is that 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.

Germany - The NB30 law in Germany was passed on March 30, 2001 and legalised Powerline applications in Germany allowing the Powerline industry to go forward. Ascom claims that all their current systems abide by NB30. This is the basis for the strong activity by RWE in Germany. Eventually NB30 will be superseded by an appropriate EC regulation, a harmonised standard.

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 - Yet other countries take a political “out” - 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.

EC / Harmonised Standards

So what applicable regulation, akin to the German NB30, does the EC have? None, so far, but a Joint EC Meeting took place in Brussels March 5, 2001. It resulted in a mandate for CENELEC 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 electroniccommunications (wire based broadband systems).

A standard European operating framework is still missing. Harmonised standards may be expected by 2003, which will then override NB30 and NPT1517.

But there is not just radiation, 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.

In the practical case, electromagnetic radiation as for instancepermissible 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.

The situation is even worse, because we are dealing not just with the two aspects of the radiativeand conductive regulations, but several more that come from other areas that precede Powerline applications and now lead to conflicts in law, interpretation and interest.

Standards like the EN55022 are continually reworked, so there is an evolutionary process of massaging the existing regulatory framework to accommodate new needs.

Coexistance - Access / In-Home

The standard making bodies have been working on the question of coexistence for more than a year now and this is the most important issue to be dealt with if we assume that Powerline applications are coming.

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 in the neighbourhood 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 takes a real effort 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. For example, a recent session by a CISPR committee started to address definitions of “data port” parameters that, if passed as initially proposed, would have caused severe difficulties for Powerline applications.