Background
Broadband Power Line (BPL) is a form of power line carrier technology (PLC) using existing power line infrastructure to deliver broadband services to homes and business. Power Line Communications has been around for a very long time from simple narrow band signalling and control systems, (the tones you hear over your stereo), to in-building spread spectrum systems such as "Home-Plug", (now available from retail outlets), to the multi home broadband distribution system – BPL.

BPL is a technology in the very early stages of adoption. Systems are installed throughout Europe, USA, Asia, Africa, and New Zealand. Most of these systems are small trials, however commercial roll-out is happening now in Europe and the U.S. According to PLC company representatives at the Sydney conference, 150,000 homes have BPL available in the U.S., and Fiji is about to adopt BPL technology in October with the help of Development Bank funding ahead of a proposed rollout throughout the nations of the South Pacific. Hong Kong, Malaysia, Singapore, and Indonesia are also adopting the technology. BPL is projected to have 9% of the broadband traffic in Europe by 2008. The news is not all supportive of BPL technology, and Japan has rejected the technology due to interference problems and pending further investigation, http://www.jarl.or.jp/English/4_Library/A-4-1_News/jn0208.htm.

In Australia the utility companies are very interested in BPL technology and the Federal Minister, Senator Richard Alston, has commissioned a report on the suitability of BPL technology to the Australian environment, (Parsons Brinckerhoff Associates). While acknowledging some technical difficulties, that report is likely to be very supportive of the speedy introduction of BPL technology in Australia.

The Interference Problem
The case for and against the adoption of BPL is complex and there are many issues to work through on both sides, a major issue being the cross-interference problem. The frequencies used are between DC and 80 MHz (different systems use different frequencies) and there are several modulation schemes. Most BPL systems in present use are OFDM (orthogonal frequency-division multiplexing – essentially a multi-carrier system) or DSSS (direct-sequence spread spectrum). The peak-to-average ratio of these systems can vary, depending on how many carriers are present in a given measurement channel. OFDM has the advantage of being able to dynamically block out parts of the spectrum in response to interference, (A good primer on OFDM is at http://www.wi-lan.com (click on technology, then white papers).

Power lines make very poor RF transmission lines, are full of discontinuity’s, and are notorious radiators of electromagnetic noise. The gain of the power-line as a radiator increases rapidly with frequency - a radiating conductor with relatively low emissions at 0.1 MHz can have emissions tens of dB higher at HF. (Calculated Levels from Broadband Over Power Line Systems and their Impact on Amateur Radio Communications Circuits, Ed Hare, ARRL, July 2003). The interference potential from BPL to other spectrum users working with weak signals in the HF and low VHF spectrum is very high and extremely widespread. This has been clearly demonstrated by ARRL testing of trial BPL systems operating in the U.S. as well as testing in many other countries including Japan and in Europe, http://www.arrl.org/tis/info/html/plc/.

BPL is said to be a polluter of the radio spectrum, causing a large rise in the `noise floor’ in urban areas akin to "radio smog". The introduction of BPL systems could make a mockery of existing EMC legislation requiring manufacturers of electronic and electrical equipment to meet rigid emission limits designed to protect the radio "noise floor" and guarantee the performance and co-working of sensitive radio equipment.

The ARRL has clearly demonstrated the interference effects of BPL on Amateur Radio communications, and also demonstrated strong interference from quite low power HF transmitters into the BPL network, using BPL test sites running in the U.S. They have presented a detailed submission to an FCC "Notice of Enquiry" into BPL systems.

The ARRL has also demonstrated that laboratory measurements of radiated emissions, and also computer modelling schemes, do not correlate well to real world measurements. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-03-100A1.doc All ARRL information and technical papers are available from http://www.arrl.org/tis/info/html/plc/. There are also a host of links to other BPL information sites and suppliers of the technology.

The BBC is also concerned about interference to it’s short wave broadcasts, especially as most receivers use inefficient internal antennas and are often placed close to mains power wiring, ("Do EMC Limits protect Broadcasting as intended", Stott, BBC R&D). New digital technologies emerging for high fidelity streaming of HF broadcasting may mean a revival of short wave broadcasting as a mainstream entertainment medium.

The Technology Drivers

Measurement and Control of the Power Network.
There are many reasons why Utility companies could benefit from BPL. The spot price for electricity in peak periods can be as high as $10,000 per MWH and the peak this winter was the highest on record. This summer is expected to be higher. Naturally, utility companies are trying to find ways to even out peak demand, http://www.nemmco.com.au/. Electricity generating networks are expected to change to reflect the service obligation that new information technologies will place on them. In the next 15 years or so information technology is expected to consume 50% of all power generated and in this high tech environment power outages will not be tolerated. Electricity supply will need to improve in availability and quality, (voltage/frequency etc). It is also expected that the electricity generation network will become less centralised and more distributed as smaller "greener" generators come on-line like wind farms, and other inter-active power generation systems where excess power is sold back to the network. Add to this the need for remote meter reading, the likely uptake of Kyoto protocols for carbon emissions, and the fact that almost 10% of all electricity is "lost", and it’s easy to see the pressure on Utilities to gather information from deep within their network, and to be able to control distribution and load on a micro-level. Energy management like switching off air conditioners or heaters in low risk areas while maintaining essential services would be preferable to a large area black-out. Spreading the peak load and monitoring distribution would allow more efficient generation and lower carbon emissions.

Competitive Broadband Access
Broadband access in Australia is expensive due in large part to the pricing strategies of a few large players. Lack of true competition between cable networks and Telstra networks has held back broadband development. BPL has the potential to broadband local communities through established infrastructure and allow local councils, utilities, etc. to offer competitive broadband services. TransACT in the ACT is seen as an example of community broadband services, http://www.transact.com.au. In many ways the move would be from Telco provided solutions which are resistant to change, to more flexible community based "knowledge" solutions. The BPL supporters in the US have gone as far as suggesting BPL is a supporting technology to "Homeland Security" by providing a redundant data network for disaster communications.

Rural Access
By allowing communities to provide local broadband access, BPL can help reduce the digital divide between the city and the bush. Telemedicine and distance education are two applications that would be attractive, however due to the nature of the technology BPL would probably be restricted to around country towns rather than remote rural properties.

The "Last mile" problem
A major problem in the roll-out of any network has always been the connection from a local hub into the customer premises. This is a very expensive and time consuming part of the service provision with running of cables, drilling of holes, pulling of wires and negotiating with property owners and strata Body Corporate's. This has proven so difficult for cable operators that multi-story apartment blocks are often avoided altogether. BPL provides a solution to the "last mile", as by feeding the broadband signal down the power line there is no need to enter the premises. The customer simply purchases a piece of equipment and plugs it in to the power point. Ultimately this lowers the cost of broadband services.

The Standards Position

EMC Standards
In Australia, no specific standard applies to "Broadband Power Line" systems. "The ACA currently has no mandatory standards for PLC equipment that transmits information on frequencies above 525 kHz. Although there are no standards at present, penalties apply in accordance with section 197 of the Radiocommunications Act 1992 to a person or company who knowingly or recklessly causes interference to radiocommunications services", http://internet.aca.gov.au/acainterwr/consumer_info/fact_sheets/industry_fact_sheets/fsi23.pdf As no specific standard exists, the generic EMC standards would be applied, (AS/NZ 4251 and AS/NZ 4252). However the generic standards are designed for point-source radiators where the radiation is limited to a very small geographic area.

Distributed radiation systems, such as the leaky power lines of the BPL system, have a much more harmful effect by creating interference over extremely large (city wide) areas. This interference is continuous and cannot be easily avoided by changing receiver location, (such as moving a vehicle).

As the C-tick is the basis for all Australian telecommunications regulation any equipment must carry a C-tick, effectively tying PBL systems into the standards environment. There is a suggestion that the generic emission standards need to be relaxed in order to take into account BPL, or at least a specific category within the standard made for BPL which allows higher emission than other applications. However the standards have been through an extensive public consultation process worldwide, and assembled wise men and women have determined that these emission levels provide balance between competing needs. It is the central plank of the "compatibility levels" concept that is the engineering basis for all of the EMC emission / immunity standards. The full story is in the basic CISPR documentation.

Ron Jackson from Zener Electric thinks BPL could be a good thing... "as long as it complies with the generic emission standards. Even if there comes to be a specific BPL standard, the limits would essentially be at the generic (domestic) levels simply because the applications are so universal. However, if the limits are to be higher that the generic emission limits, then on the grounds of compatibility, not to mention of fairness, it would be reasonable, perhaps essential, to raise the limits for everything. Such a wholesale change has enormous implications for the global electrical industry and all of a sudden, it turns into a world trade issue. To just take the situation within Europe, a large part of the CE mark process is aimed directly at removing non tariff barriers to trade between member states". The IARU plans to participate in International Telecommunication Union Radiocommunication Sector (ITU-R) study group sessions concerning the interference potential of high data rate telecommunication systems using power lines- BPL. http://www.iaru-r1.org/news-02feb03.html

Inter-working Standards
There is currently no standard for the interworking of PLC/BPL systems. Currently if `Home-Plug’ is installed in a situation where there is a BPL service the two systems will clash and may prevent operation of each. There is work being done on developing a set of interworking standards for PLC systems. There is also no standard for the connection of different supply grids running BPL.

Where Does Fibre End and BPL Start?
BPL networks consist of a backbone fibre network ring that is connected through a node to the medium voltage or low voltage power lines, which then take the BPL signal to the customer. A critical question in the design of a BPL network from a financial and also an interference point of view is: how deep into the network does the fibre go? The closer the fibre goes to the customer, the less is the power required to provide an adequate signal, and one would suppose the less interference radiated, (this needs to be measured and confirmed). Deep fibre systems would also allow greater bandwidth and data speeds as required by the new technologies such as video on demand or MPEG4. However taking the fibre to the curb or the closest power pole is also more expensive than say to the closest medium voltage to low voltage transformer, and slower to roll-out. In a risky business environment where "owning the customer" is paramount importance it’s likely that utility companies will attempt to use the quickest and cheapest technology to get started, and then take the fibre deeper into the network as customer numbers, revenue, and applications grow.

The Case Against BPL
Apart from the obvious cross-interference problems and the lack of appropriate standards regulation, there are other problems with BPL. In many ways the proposed BPL system is a dinosaur. In today’s society the need is for faster data allowing the new digital formats such as MP4 and Video-on-Demand to be transferred quickly. Traditional multi-drop cable and BPL systems are built on 1960’s cable architecture and will not provide sufficient bandwidth to each home for tomorrow’s applications. Rather a deep fibre network with a minimum of homes connected to each node will be required. For these reasons the "window of opportunity" for deployment of BPL systems’ is quite narrow.

Graham Wilson of Silicon Harbour Technologies believes the solution to the `last mile’ problem may be a DIY solution where customers arrange for their own fibre or twisted pair connection to the curb-side fibre network. As there is no electrical safety problem with fibre technology this is a possibility, and would provide the highest bandwidth into the home. Fibre can be strung along the existing poles, wrapped around live wires, or woven into the neutral conductor on high voltage power lines, and has very little visual impact. TransACT is already providing a deep fibre service in the ACT.

Due to the transmission losses involved BPL systems would probably not be effective in providing broadband access to very remote areas and do nothing to address the inequity of access to broadband services for the outback, where satellite systems will provide the only viable alternative. Long high voltage earth return distribution lines, as used in remote Australia, are more akin to a terminated long wire antenna than an RF transmission line. The service would mainly be delivered to those already well served by conventional broadband cable, ADSL networks, or point to multi-point microwave in cities, or to localised areas around country towns. Telstra Countrywide is working to provide broadband access in rural Australia.

Australia is a country that relies more heavily on HF radio than most. Our military, civilian, and emergency communications systems rely heavily on HF radio, and the Over The Horizon Radar System processes very weak signals indeed. BPL technology needs to be very carefully evaluated in this light. The real problem is that BPL is one of those things that "can be shown to work" at the trial stage and if the users "get hooked", its very difficult to terminate such a system, no matter how poor it is in reality.

A Sociologists View
"Technological Determinism" is a sociological term given to the concept that technology is a driving force for social change, and that technology sets the conditions for the operation of the political system. Some believe it, some don’t. Marx would say that technology establishes a particular set of power relationships. Technology shapes politics and politics shapes technology – both are interdependent. The chairman of the FCC, Michael Powell, is a fan of BPL as a third broadband pipe into the home and for it’s potential to open up more competition. "the commissions goal must be to achieve the greatest amount of bandwidth for the greatest number of people". This opening up of competition and increasing citizens access to broadband services is a far more important issue for governments than interference to a few HF users. Certainly, as there is Ministerial interest in the technology in Australia, BPL must be taken as a serious contender here also. For Radio Amateurs this means that BPL will effect them no-matter what, and the extent to which Amateurs play a pro-active role will determine their own future. When German radio amateurs opposed the introduction of BPL the reaction of their Government was that only 80,000 radio amateurs, (of which only about 30,000 were active), should not be allowed to prevent the adoption of a technology which would benefit the German population as a whole, (anecdote from Conference on Powerline Broadband, Sydney, Dr Juergen Bender, of Parsons Brinckerhoff Associates). Our aim must be to demonstrate that the social benefits of yet another broadband delivery system need to be weighed against the problems encountered by a whole range of diverse spectrum users.

Strategy
There are two obvious ways to go: Oppose the introduction of BPL at all costs. This seems a risky way to go considering the strong industry and political pressure for the uptake of the technology. To oppose the technology altogether would be to close the door on any possible negotiation, and drive information from trials underground away from public view. To me, this seems to be the position the ARRL has taken. OR Participate in the dialogue surrounding BPL with a view to influencing standards and regulation development. This seems to me like a more realistic approach. In many ways the ACA is the key to the interference problems with BPL. By arguing for regulation requiring a deep fibre network with low injected power, and orthogonal frequency-division multiplexing modulation, the interference problems should be minimised, (however this needs to be confirmed with real life measurements under various data conditions).

For many reasons amateurs should NOT attempt to go this alone. We need to form an association with other MF/HF/low VHF users to put a united voice opposing radio `smog’. Other like-minded groups are defence, safety, CB operators, 4WD groups, broadcast band and shortwave broadcasters, aircraft operators, etc. We Should Attend all BPL conferences and meetings and voice technical concerns. Form a new association of concerned spectrum users, hold regular meetings, and lobby the ACA and government agencies. Approach Australian Standards Committee TE/3 to consider the impact of BPL on the Australian and worldwide EMC standards framework. Review all available documentation and prepare technical responses. Participate in all trials and measure emission levels. Refer ARRL technical papers to IEC emission limits.

Summary
BPL is a technology in the very early stages of adoption. PBL is a dinosaur technology which if adopted has the capacity to cause very high levels of HF and low VHF noise interference. Many organisations in many countries have demonstrated the adverse effects of BPL interference on HF and low VHF communications. There is a wide body of information both technical and anecdotal. The interference works both ways. Low power HF transmitters have been demonstrated to interfere with BPL networks. There will be many agencies, companies, broadcasters, and individuals adversely affected by the introduction of BPL. There is no existing ACA telecommunications or EMC standard specific for BPL. The appropriate standards are the generic EMC emission standards.

There is pressure to relax generic emission standards, which has implications for the entire electronics industry. There are better ways to provide competitive bandwidth. BPL, as it is likely to be introduced, will not meet the bandwidth requirements of the new information formats such as MP4 or Video-on-Demand. BPL is a very attractive technology to power utility companies allowing energy management and control of the distribution system as well as increased revenue from broadband services. PBL increases competition in broadband services and provides broadband services in towns not currently serviced by the Telco’s at low start-up costs. Amateurs must be involved in the BPL standards and regulation process. This is best done from within an alliance of other affected organisations and individuals. The deep fibre systems (fibre to the curb) using orthogonal frequency-division multiplexing modulation are likely to have the least potential for HF interference.

Australian Communications Authority position as of 11 Sept 2003

as taken from ACA website

Note: "The ACA currently has no mandatory standards for PLC equipment that transmits information on frequencies above 525 kHz. Although there are no standards at present, penalties apply in accordance with section 197 of the Radiocommunications Act 1992 to a person or company who knowingly or recklessly causes interference to radiocommunications services." Industry fact sheet: EMC requirements for powerline communications equipment. Powerline communications (PLC) equipment delivers voice and digital services over existing power lines. To manage the risk of unwanted emissions or interference by PLC equipment to radio-based services, the Australian Communications Authority (ACA) has recognised European and international standards to cover this type of equipment under its electromagnetic compatibility (EMC) regulatory arrangements. This fact sheet talks about mandatory standards for PLC equipment intended for low voltage installations only. The ACA at present has no mandatory standard in its EMC regime for PLC equipment intended for high voltage distribution systems. PLC equipment for low voltage installations-installations connected to the general electrical mains supply-is required to comply with one of the following standards mandated by the ACA.

1. EN 50065-1 Signalling on low voltage electrical installations in the frequency range 3kHz to 148.5 kHz-Part 1: General requirements, frequency bands and electromagnetic disturbances. EN 50065-1 applies to electrical equipment using signals in the frequency range 3 kHz to 148.5 kHz to transmit information on low voltage electrical systems, either on the public supply system or within installations in consumers' premises.

2. IEC 61000-3-8 Electromagnetic Compatibility (EMC) - Part 3: Limits-Section 8: Signalling on low-voltage electrical installations -Emission levels, frequency bands and electromagnetic disturbance levels. IEC 61000-3-8 applies to equipment using signals in the frequency range from 3 kHz up to 525 kHz to transmit information on low voltage electrical installations either on the public supply system or within customers'premises. It specifies disturbance limits in the frequency range from 3kHz up to 400 GHz. PLC equipment comes under Compliance Level 2-the compliance level for a medium risk device. To comply with Compliance Level 2, the supplier of the device must: 1. prepare a description of the device; 2. make a Declaration of Conformity for the device; and 3. demonstrate conformity with the applicable standard by testing or technical assessment. In-house testing will be acceptable for this compliance level.

Please note: the ACA currently has no mandatory standards for PLC equipment that transmits information on frequencies above 525 kHz. Although there are no standards at present, penalties apply in accordance with section 197 of the Radiocommunications Act 1992 to a person or company who knowingly or recklessly causes interference to radiocommunications services.

More information
For more information on EMC C-Tick regulatory arrangements, contact any ACA Office or the EMC section, Radiocommunications Standards Team on Telephone (02) 6219 5258 or Fax (02) 6219 5231

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