THE FINAL CONNECTION?

Advanced Search

ABOUT EEI

INDUSTRY ISSUES

PRODUCTS AND SERVICES

MEETINGS

MAGAZINE

NEWSROOM

home > magazine > editorial content

•	calendar
•	editorial index
•	guidelines

THE FINAL CONNECTION?

Brett Kilbourne is associate counsel with the United Telecom Council (UTC) in Washington, DC. For more information on UTC's "2001 Powerline Telecommunications Report," visit www.utc.org.

Just a few years ago, powerline telecommunications technology held more promise than commercial reality. Today, it has begun to prove itself and is opening up new markets for electric utilities.

The promise of powerline telecommunications (PLT) is great. Imagine: You can plug in your computer and get on the internet through the powerline...automate your electrical appliances via the wires already attached to your home...get low-cost Internet access, climate control, and lighting control for your office building and pay your bill to the electric company.

Why not? Utilities, after all, have used similar powerline technology for internal communications purposes for decadesÂ€€and the connection to the customer already exists.

The concept of digital PLT for commercial consumption started with Nortel in 1997. It partnered with United Utilities under the name NOR.WEB to conduct limited trials in Manchester, in the United Kingdom. The company reported data throughput rates of 1 megabit per second (MBPS)Â€€but even then those rates were considered low compared to cable modem service (at 2 MBPS), digital subscriber lines (DSL, at 3-9 MBPS), and high-speed DSL (XDSL, which now reaches 32 MBPS). NOR.WEB also encountered regulatory issues as it tried to comply with strict radio-frequency (RF) emission standards proposed by OFTEL, the U.K. telecommunications regulator. Nortel officially pulled the plug on NOR.WEB in September 1999, tersely describing it as "uneconomic." Even though the already-installed powerlines made things easier, the coupling equipment had installation costs per household of $300-$330. And with the slow throughput rates, Nortel simply couldn't make the business case.

Then, Media Fusion claimed that it had achieved PLT speeds of 2.5 gigabits per second via transformer-piercing signals. But while that technology still exists, no working product was ever demonstrated in public, and the company has fired its chairman and inventor.

The reputation of PLT suffered (and is still recovering) from the "vaporware" image that was created. Even recently, the future of PLT did not seem to go much further than the drawing boardÂ€€a tempting idea with a lot of unresolved issues.

But PLT has undergone a resurgence. Currently, there are companies that are actually deploying service in Europe, albeit on a limited basis. Here in the United States, other companies are courting utilities as partners for PLT trials and investment. While these trials have restored credibility to the technology, utilities are understandably cautious when they hear unsubstantiated claims concerning it. On the other hand, the latest deployments may shake the PLT vaporware reputation and demonstrate that it is economically viable and as good as or better than other broadband services.

Last Mile Standing
PLT is distinct from low bit-rate powerline carrier (PLC) systems that utilities use to monitor and control electrical loads on their networks. PLT technology amplifies the communications signal over the powerlines to provide "last mile" broadband accessÂ€€ offering Internet, voice, and streaming video and audioÂ€€to residential and commercial subscribers.

PLT works by sending the signal from the substation, across the medium- and/or low-voltage distribution lines, and into the home, where the signal is received by a modem. The modem converts the signal for recognition by the peripheral devices that are running off the PLT system. As such, a few key components are necessary. First and foremost is the silicon chipset for the transmitting device. The second is the PLT modem. Finally, most PLT access technologies require that the signal bypass the electric transformer, so there must be a coupler.

In much the same way as DSL sends a digital signal over the voice signal on a telephone line, PLT sends a digital signal on frequencies separate from the noise created by the powerline's electrical current. The similarities between PLT and DSL end there because DSL does not contend with the same level of "noise" on the telephone line that exists on powerlines.

Within the broadband access application are two markets: access itself and home networking. Utilities are primarily interested in the access application, and this is the main reason for interest in PLT in Europe. But home networking products based on PLT will be deployed soon and may have an impact on potential access applications.

PLT is scalable and leverages existing infrastructure, so service could be deployed quickly, relatively inexpensively (despite NOR.WEB's experience four years ago), and with minimal sunk costs. In the United States, home networking applications will drive the market. There has been some delay while silicon chipset prototypesÂ€€necessary to separate the communications from the power in the line and then distribute it to home or officeÂ€€have been developed. Now that the prototypes are near production, there may still be time for PLT to gain market share. Although DSL and cable modem have a head start, many providers of these broadband services have halted the deployment of equipment due to financial difficulties. This may provide a window of opportunity for PLT.

Status of Development
Most PLT components are still in development, but they are expected to be commercially available this year, including modems from distributors such as Earthlink and Best Buy.

There are at least 11 companies that are developing PLT products. These companies are in various stages of progress, but they have reported that their products would deliver greater throughput over longer distances than was thought possible just two years ago. Advanced modulation techniques have boosted throughput to 2-10 MBPS, which is comparable to other broadband access technologies. And that means PLT could potentially compete in the marketplace, especially for residential customers. The business case for deploying PLT has become more attractive.

Many of the PLT companies have conducted trials, but few have publicly announced them. Ambient Corporation and Mainnet, however, are two companies that have trumpeted their work. Ambient has partnered both with ConEd and with Sumitomo Electric Industries. Mainnet has partnered with both MVV (a German utility) and PowerTrust (a U.S.-based energy marketer).

Ambient's trials are still in the alpha stage but have demonstrated the capability to deliver both consumer services (such as Internet, telephony, video-on-demand, content, and smart appliances) and utility services (such as load switching/balancing, outage reporting, and automated meter reading). Mainnet has launched commercial service with plans to serve 3,000 MVV customers in Mannheim. In the United States, it has conducted a trial in Georgia with Cowetta-Fayette Electric Cooperative.

Three other commercial deployments have begun or will begin shortly in Germany.

Oneline, a subsidiary of the German utility E.ON, has offered service to a limited number of utility customers, and the response reportedly has been overwhelming.

RWE, the largest utility in Germany, is partnering with PLT provider Ascom to roll out its own service this summer.

Another smaller German utility, Energie Baden-Wuerttemberg, is planning to link up 7,500 customers in the southern town of Ellwangen this summer, even though its technology partner Siemens announced that it is suspending its PLT project to focus on traditional broadband technologies such as DSL.

The other technology companies working on PLT are Adaptive Networks, DS2, Enikia, Ilevo, Intellon, Keyin Telecom (now called XEline), and NAMS/Nisko.

Benefits, Challenges
There are a variety of inherent advantages for utilities to deploy PLT.

The technology makes more efficient use of utility infrastructure.

It permits utilities to offer service more quickly and inexpensively than competing broadband technologies because it does not require the deployment of new communications cable.

Utilities avoid sunk costs if a subscriber switches from PLT to a different broadband technology.

PLT is capable of reaching more customers than the leading broadband access technologies.

PLT could be ideal for delivering broadband access to rural and under-served areas, where other carriers cannot or have chosen not to deploy DSL, cable modem, or other broadband services. Policymakers are struggling to bridge the so-called "digital divide"Â€€the gap between providers and customers who currently do not have access to broadband services. Congress is seeking to stimulate rural broadband deployment through subsidies. Meanwhile, the Federal Communication Commission's most recent report on the deployment of advanced telecommunications services has substantiated claims that the information superhighway bypasses low-income and minority consumers.

But despite advances in the last two years, five obstacles remain to the deployment of PLT in North America: inadequate signal-to-noise ratio; interference; problems with bypassing transformers; segmentation of the feeder; and safety and procedural concerns.

Of these, interference and transformer bypass are acute in North America. Whereas European power systems typically provide electricity to more than 50 customers per transformer, the network architecture in the United States generally serves a maximum of 15 customers per transformer. With the exception of Mainnet, most companies believe that the transformer must be bypassed. So, the costs of couplers to achieve this can be apportioned among more customers in Europe than in the United States.

Moreover, European 240-volt secondary distribution lines use three-phase shielded cable, whereas North American 120-volt secondary lines are unshielded, so interference to and from PLT may be greater in the United States than in Europe. This interference may either attenuate the signal or prevent its reception altogether.

Segmentation of the feeder is an obstacle inherent to PLT. Subscribers share the capacity available at the network node, so congestion could occur during periods of heavy use, reducing the throughput. Accordingly, segmentation of the feeder (that is, using separate lines) may be necessary to reduce the number of the subscribers sharing the same network node. This isn't a problem, of course, when there are only a few subscribers.

Likewise, the signal-to-noise ratio is another drawback to adapting power-lines for communications purposes. Powerlines are a hostile environment for a communications signal because of unpredictable electrical loads and other variables. A simple solution to the noise problem is to raise the digital signal's frequency to a level sufficiently separate from the electrical noise to reduce the interference potential. Still, the noise level may vary considerably from outlet to outlet, house to house, day to night. The only certain thing is that the noise level increases closer to the source of the load. The typical household is the noisiest environment on the network, particularly if air conditioners are operating (though hair dryers and vacuum cleaners don't help either). So, most PLT technologies amplify the digital signal between 1-30 megahertz (MHz) to build in a sufficient margin from regular current (at 60 hertz) and the aberrations from electrical spikes that may occur during heavy loads.

Amplifying the frequency creates a dilemma. If the digital frequency is high, the signal will attenuate to a greater degree, shortening the range of communications. If more power is used to boost the range, it increases the potential for interference to other devices. It also risks violating regulations on the limits for RF and conductive emissions that exist in North America, Europe, and elsewhere.

Hence, the newer PLT technologies use advanced encoding and modulation techniques that permit the signal to be carried closer to the electrical noise floor without interference or attenuation. Spread spectrum is one solutionÂ€€the signal is packetized across multiple frequencies by the transmitter and reassembled by the receiver at the customer's premises. The problem with spread spectrum is that it requires that more data be added to the address of each packet, consuming bandwidth, which is already in short supply on a PLT system.

Another solution that has gained popularity is orthogonal frequency division multiplexing (OFDM). This simply divides the available spectrum into many narrowband, low data-rate carriers (or subcarriers). Each subcarrier can be modulated again using various formats. No encoding is necessary, so bandwidth is conserved. As a result, OFDM resolves interference and attenuation and boosts throughput by making more efficient use of the spectrum. One PLT provider claims that data rates of 100 MBPS are possible using OFDM.

Of course, there are a host of safety concerns, primarily associated with bypassing the transformer. The coupler must prevent the medium voltage in distribution lines from migrating beyond the transformer. There is also the more fundamental question of ensuring that electrical service is not impaired by the addition of PLT. Moreover, developers will have to demonstrate that the hardware is safe; and utility crews will need additional training.

Regulatory Barriers
Some of the biggest regulatory issues facing PLT are RF and conductive emission limits. These are designed to reduce the potential for RF to be radiated from or conducted back onto the lines, which can cause interference to other devices connected to the lines or to wireless communications. In the United States there are no emission limits that specifically apply to PLT, but there are general limits that might.

Meanwhile, Germany has recently established laws for PLT emissions. Although the German laws are strict, only one PLT company (Siemens) has dropped outÂ€€evidence that PLT presumably can comply.

The technology also may be subject to varying degrees of regulation depending on the service it offers. These regulations may come from local, state, or federal jurisdictions. For example, there are similarities between streaming video via PLT and cable television service. If that PLT service were regulated as a cable service, it would be subject to franchise regulations by state and local jurisdictions. In addition, there are federal regulations of the content on cable television that could apply.

In addition, the use of one wire to deliver electricity and telecommunications services raises affiliate transaction and pole attachment issues. If a utility subsidiary handles the PLT business, there may be complicated matters of asset valuation and so on. If the utility is subject to pole attachment regulations at either the state or federal level, there may be difficult issues with respect to the rates, terms, and conditions for attachments used to provide PLT. The utility's use of rights-of-way may also be affected.

Worth Another Look
Now that companies have begun to prove that PLT works and can compete with other broadband technologies, they must now contend with the practical problems of delivering products to market. They need to adopt standards to avoid interference with each other's products and with other consumer products that are connected to the lines in the home. They need to find manufacturers that can produce affordable silicon chipsets. They also need to work closely with powerline owners to ensure that these products do not interfere with the safe, reliable, and efficient delivery of electricity.

Right now, Europe is the main testing ground for commercial deployment, but the experience gained there should help companies like Ambient deploy service in the United States more quickly. And while the technical differences in the U.S. electrical grid make PLT economics problematic, there may be some advantages, as well. For example, the fact that there are fewer North American homes per transformer might lessen the congestion from too many subscribers. Moreover, demand for broadband in the United States is greater than in Europe, and as policymakers search for technologies that can reach rural or underserved subscribers, PLT may qualify as a candidate for subsidies or reduced regulatory burdens.

In addition, with its automated meter reading and home-networking capabilities, PLT could reduce costs through demand-side management applications and enable the collection of customer data in a robust manner.

As energy companies seek new revenue streams and services, PLT could be a low-risk strategy. But look before you leap. PLT is still young, and many developers hold the details of their systems close to the vest. Also, the economics are hazy, while the technical and regulatory obstacles are clear. The best advice? Get involved and learn the technology.

| | | | |