Networks power up
- By William Jackson
- Apr 22, 2005
Technology to transmit data over electrical lines is starting to mature. The Navy sees its benefits.
Networking at sea: The Navy's Afloat Lab uses electrical wiring to connect computers.
Courtesy of Office of Naval Research
Efficient, cost-effective networking, both within and between organizations, remains fertile ground for innovation. One still-emerging technology promises to bring the power of communication to the electrical lines that already serve homes, businesses and government facilities.
Connectivity over power lines is beginning to see its first real-world implementations both for in-building LANs and last-mile broadband Internet access. It's a technology that's been coming for a while, but a handful of companies have developed next-generation products that may start catching on.
'Our biggest challenge is from people who ask, 'Does that really work?' ' said Ronald W. Pickett, CEO of Tel- konet Inc. of Germantown, Md.
Some government agencies say it does.
Telkonet has been promoting its PlugPlus power line communications system in both the government and commercial marketplaces. The system has been used to provide Internet access in a number of hotels and apartment buildings. The Navy is testing it for use with the Navy-Marine Corps Intranet, and the company recently partnered with GTSI Corp. of Chantilly, Va., to help sell more solutions to government customers.
'The only place I've seen it working is in a couple of pilots we have going, and it works well,' said NMCI technical director Col. Robert Baker. 'It saves you from having to wire a building.'
Outside of buildings, companies such as Communication Technologies Inc. of Chantilly, Va., are using city power lines to provide broadband Internet service in Manassas, Va. Com- tek received a 10-year franchise from Manassas last July.
Comtek CEO Joseph E. Fergus said the company had a waiting list of 1,300 customers ready to pay $28.95 per month for residential service and $39.95 for commercial service at speeds comparable to digital subscriber lines or cable modem.
Fergus called communities with 25,000 to 100,000 potential customers a 'real sweet spot' for the technology, and said the company expects to make the service available to all 12,500 homes and 2,500 businesses in Manassas this year.Will agencies plug in?
But the question is, beyond pilots and small-scale programs will the technology lure agencies? Experts' opinions are mixed.
In-building networking over wires, and broadband power line Internet access are two different solutions to two different requirements'with varying prospects for success. The latter solution gets most of the attention. In an April 2004 speech, President Bush touted broadband over power lines as an important new technology, and a recent study by Washington's New Millennium Research Council concluded that 2005 'could be the time the technology begins its emergence as a viable competitor in the broadband market.'
The former use of electrical lines'in-building networking'is less glamorous but could deliver more measurable benefits.
Telkonet, which recently earned FIPS-140-2 certification from the National Institute of Standards and Technology, has tested its PlugPlus system on the Office of Naval Research's Afloat Lab, a research vessel stationed in Annapolis, Md. It has also been deployed as part of the NASA Extreme Environment Mission Operations, which uses an underwater lab to approximate deep-space conditions.
'We are an in-building solution only,' Pickett said.
Data service is brought into a building or vessel through a 10/100 Ethernet port on a Telkonet Gateway, a router that converts the signal to a power line carrier protocol. A Tel- konet Coupler delivers the signal to the circuit breaker. It is then distributed over electrical wiring. The Telkonet iBridge, which plugs in- to a power outlet, converts the PLC signal back to Ethernet. Computers plug into an Ethernet port on the iBridge.
The company also makes a Telkonet eXtender, which is a repeater that enterprises can use to boost the PLC signal inside a building, if necessary.
Through the iBridge, the Gateway product monitors 70 channels over the power lines, switching data to different channels to avoid interference from spikes in electrical power. The Gateway is designed to support up to 1,000 users, although Pickett said the largest installation so far has 200 users. One Gateway with one eXtender is serving a 350-unit apartment building in Manhattan, he said.
As for bandwidth, the system provides from 5Mbps to 35Mbps, depending on distance and conditions.
Col. Baker was intrigued by the technology when he saw a demonstration of PlugPlus at an NMCI symposium in December. It was later tested aboard the Afloat Lab and is also running in a number of Navy offices.
'It works aboard ship,' he said. How valuable it is in an office environment 'depends on what your object is.'
He doubts that it would be cost-effective in a new building that already has an adequate networking infrastructure. But it could have a niche in retrofitting ex- isting buildings. By networking systems over existing power lines, agencies could avoid construction issues in older buildings where asbestos might be present, or they could speed up installation in temporary facilities, such as short-lease, store-front offices used by recruiters.
'You just take the device with you and plug it into the new place,' Baker said.
'I can see wide tactical applications for this in the field,' he said. 'That's where I think the greatest growth could come.'Overseas applications
Although he couldn't confirm it, Baker said he'd heard that forces in Iraq were using the system. In fact, Telkonet in De- cember announced it was working with the State Department to include power line communications in a new media center in Baghdad.
While users can appreciate the possibilities of using indoor wiring for local networking, using power lines to connect beyond the walls of a facility faces an unclear future. 'We have not done anything with WAN on power lines,' Baker said.
Experts say there is growing interest in using outdoor power lines to connect buildings and campuses to the Internet. After all, power lines are everywhere'if you have a computer, you already have electricity. But as a wide area networking technology, it has established competition, from DSL to fiber optics.
Robert G. Olsen, professor of electrical engineering at Washington State University and a contributor to the NMRC study, warned against overly optimistic forecasts for broadband over power lines.
'I don't believe BPL will give you any better performance than DSL or cable,' Olsen said.
Power companies for years have used their transmission lines to carry data at relatively low speeds for system monitoring. Moving data on electrical lines relies on the same principle as DSL and cable data service: There is ex- cess capacity on existing transmission lines. All that is needed is to separate digital data from the existing power supply, voice traffic or video signal.
NMRC in its study identified more than 20 trial or pilot programs undertaken by utilities in 2004 and found that 'some companies expect that they can obtain 20 percent of the market share for broadband in their service areas within several years.'
Comtek's Manassas rollout is the first citywide deployment of the technology. Comtek supplies free BPL modems to customers and symmetrical speeds of 500Kbps to 10Mbps.
But an April 2004 report in Telecommunications Policy, a journal from Elsevier Inc., concluded that power line communications 'is unlikely to gain a market share greater than a few percent in the next few years.'
Power lines pose two significant challenges to service providers: Distance and transformers. Signals lose power quickly at the high frequencies used for data transmission, requiring repeaters to boost the signal.
In addition, the transformers that step down power from transmission line strength to building strength effectively block data signals, requiring some kind of workaround.
Such workarounds have not been standardized. Some companies have proprietary technologies for passing signals through or around the transformers. Other providers avoid the transformer altogether by using wireless links to get the signal from the pole to the building.Lack of standards
There is also no marriage at this time between LANs that use electrical wiring and last-mile broadband power line systems. Nor is there a standardized interface between broadband transmission from outside power lines and systems that distribute the service inside a building.
What's more, the possibility of radio interference from above-ground power lines, especially to ham radio operators, also remains an issue.
The actual impact on ham radio operators has not been determined, but the FCC has placed limits on the amount of radio frequency signal allowed to 'bleed' from lines and has banned harmful interference to licensed radio operators, although it has not defined what is harmful. Power line service providers will have to 'notch,' or reduce power in of- fending frequencies, if interference is reported.
Rahul Tongia of Carnegie Mellon University's School of Computer Science, author of the Telecommunications Policy report, concluded that power line communications 'does not appear to represent a major disruptive technology.'
Even Comtek's Fergus described broadband over power lines as just one part of a service delivery package that includes cable, DSL, fiber and wireless. Whether its opportunities outweigh the challenges will be worked out in the next few years.