Implementing BPL Technology

Plug It In

Combining power and data on the same wire isn't new. The phone company has been powering your phone for decades with its central office switch over the same wires that carry voice. And the recent IEEE 802.3af PoE (power over Ethernet) standard has made it possible to provide more power across LAN wiring for VoIP (voice over IP) phones and wireless APs (access points).

Products that let you use your home's electrical wiring to transport data have been around for years. With the HomePlug 1.0 standard developed by the HomePlug Powerline Alliance, products from multiple vendors, such as DSL routers and Ethernet/USB adapters, may be plugged into home receptacles so they can communicate with one another using a single wiring system. Telkonet, meanwhile, offers large apartment buildings and hotels LAN connectivity using their electrical wiring and its own proprietary technology. As a matter of fact, Donald Trump uses Telkonet's iBridge in many of his buildings.BPL technology is similar, but it faces much bigger technical challenges. The obvious advantage of BPL is that it uses the electrical power infrastructure that already delivers power to just about every home and business in the United States. It's just a matter of utilities installing equipment that transmits data signals along with the electrical current. Then all you need to do is plug into the wall receptacle. But it hasn't been easy for utilities to crack into the business of providing broadband local voice and data services--it takes time and plenty of capital to provision cable to homes and businesses, and not all electric utilities will deploy BPL.

Aside from the costs associated with provisioning such a service, power lines can experience interference, which makes BPL tricky to deploy successfully. Power lines don't have shielding, so anything transmitted along them can leak into the surrounding environment. The 2-MHz to 30-MHz spectrum for shortwave radio, for instance, overlaps with BPL's 2-MHz to 80-MHz frequency range--a fact not lost on ham radio operators. The Federal Communications Commission now requires BPL providers to work closely with these radio operators to filter out portions of the spectrum that cause problems, and in some cases to decrease power or even shut down the BPL service until the interference is eliminated.

Still, there are some real incentives for utilities to choose BPL. For example, they can use the data-transmission capabilities to provide internal communications through VoIP, and use BPL for remotely monitoring customers' power meters over high-speed connections. BPL also could help them more easily pinpoint outages without dispatching a technician. So on a hot summer day, a utility could turn off some air conditioners long enough to avert a major outage, but not so long as to cause major discomfort. Another selling point is that a utility could use BPL to strengthen national security by remotely monitoring the power grid, gas pipelines and other critical resources with networked video cameras.

Utilities such as Cinergy, Solvay Electric and Con Edison get around some of the BPL deployment challenges by using systems integrators to set up and run their BPL services. The integrators, in turn, pay each utility a royalty for the use of its infrastructure. They can then offer Internet access without the costs of installing a cabling infrastructure--plus there's less CPE, which decreases support costs and, therefore, overall service costs for businesses. ISPs such as EarthLink are getting into the action, too, adding BPL to their list of broadband access options.

BPL can't easily compete where cable and DSL are already well-entrenched, so BPL makes the most sense in areas that provide limited broadband options. It complements other broadband options, too: BPL can extend the reach of DSL and back-haul WiMAX wireless base stations, for instance, which could help expand broadband to rural areas. BPL alone can't support these low-density areas because the equipment costs too much to carry the service there. The bottom line is that having yet another broadband alternative should keep your service options competitive and more affordable.So how is BPL provisioned? Electric utilities have three classifications of power lines: high, medium and low voltage. Think of the high-voltage lines as the backbone or core of the distribution system. Usually around 70,000 volts, these lines terminate at substations that distribute the power at approximately 7,000 volts over the power lines you see strung across poles along streets and roads. Medium-voltage lines must be taken down to 110 or 220 volts before entering subscribers' homes. This is accomplished with a transformer that serves six to 10 homes.

Introduced into the power grid at the substations, data travels across the medium- and low-voltage lines to reach the end user. High-voltage lines are too noisy to co-exist with the data signals in the 2-MHz to 80-MHz frequency range. Getting data to the low-voltage lines that enter into subscribers' homes is problematic because the transition through the transformer creates enough noise to destroy the signal altogether. There are several ways for a utility to remedy this, including installing a coupler that essentially bypasses the transformer and delivers the data signal safely from the medium-voltage lines to the subscribers on the other side. Then the user can plug an inexpensive modem into any power receptacle, which in turn translates the signal to Ethernet. This is more flexible than cable or DSL access, which terminates in only one location.

Another approach is to put an AP on the pole outside of the business or home, using 802.11b wireless. This is feasible because the AP can be placed anywhere on the medium-voltage lines and reach multiple homes without requiring any extra equipment between the medium-voltage lines and the business or home. The disadvantage of this approach is that it uses unlicensed radio spectrum on the same frequencies as many cordless phones, microwave ovens and other APs that nearby business or home neighbors might be operating on the same channel.

For systems that deliver the data directly to an electrical receptacle, couplers are used on the medium-voltage lines to bypass transformers completely. This adds equipment installation and support costs for the utility. Another problem is that the signal travels only about 1,500 feet before it requires boosting. Vendors such as Ambient and Amperion offer repeaters to extend this distance, but the need for repeaters makes it cost-prohibitive for utilities to deliver BPL to low-volume, rural locations.

Although the electric utility can't use its high-voltage wires to transport data, it can use its rights of way to install fiber for connecting to an ISP.While power-line interference is no longer a major stumbling block for BPL service deployment, security remains problematic. Theoretically, data can be "sniffed" when it leaks out into the airwaves, and there is nothing to stop the signal transmitted to one user from being sent to any of the other six to 10 users served by the same low-voltage transformer. VPNs and SSL encryption can help secure BPL: Most businesses already rely on these for at-home workers or those who use the Internet for access. BPL equipment may include encryption, though in some cases it is only 56-bit, which is easily cracked. But as long as you "turn on" strong encryption, you can protect yourself from sniffers.

Meanwhile, there are potential interference problems with BPL if you use electrical wiring for local-area communications within a building. The signals can interfere with one another and interrupt the data transmission. This is being addressed by the HomePlug Powerline Alliance, which has worked with the United Powerline Council (UPLC) to come up with a solution. The Alliance's latest standard, HomePlug AV, allows internal communications among devices within the home or small office, or even within a large building like a school or hotel. It is also compatible with the next generation of utility BPL equipment.

And the next generation of chipsets will make it possible to carry more bandwidth over the allowable frequencies, so BPL transmissions can attain speeds of hundreds of megabits per second. BPL services will then be able to compete with carriers and cable operators in triple-play services (voice, video and data). These faster BPL products are expected to become available to utilities later this year.

You may still hear some vehement opposition from disgruntled ham radio operators complaining about BPL interference, but it doesn't appear that the FCC considers such interference an obstacle to the technology's adoption today. Carol Mattey, a former FCC official currently with Deloitte and Touche, says the FCC believes the potential benefits of BPL far outweigh any possible problems that may result from interference.

Of course, there's nothing stopping states from imposing their own restrictions on BPL. However, the National Association of Regulatory Utility Commissioners is attempting to establish guidelines that would limit the impact of regulation by individual states, Mattey says. NARUC supports the development of BPL as a viable competitor to cable and DSL access, which will benefit business and residential broadband customers.This won't completely guarantee smooth sailing, because states are still free to come up with their own regulations, and ham radio operators will be vigilant about monitoring possible interference problems. Some BPL trials have been shut down altogether when BPL operators didn't follow the FCC guidelines. But BPL equipment manufacturers and designers are working to eliminate interference.

So if you're on the lookout for an alternate broadband service--or if you can't get broadband for some of your sites--call your utility now to find out its plans for BPL. It's becoming a real option for high-speed Internet access.

Peter Morrissey is a full-time faculty member of Syracuse University's School of Information Studies and a contributing editor for Network Computing. Write to him at [email protected].

Sites To See

Amperion, www.amperion.com: BPL equipment manufacturer that uses 802.11b for the last mileCurrent Technologies, www.currenttechnologies.com: Full line of BPL products for end users and electrical utilities

HomePlug Powerline Alliance, www.homeplug.com: Promoter of power line networking technology and standards

EarthLink, www.earthlink.com: Independent ISP using BPL as an option for access

Main.net Communications, www.mainnet-plc.com/index.htm: Provides direct access from wall receptacles using Ethernet, USB and analog connections

Telkonet, www.telkonet.com: Provides networking over electrical wiring options for hotels and apartment buildings0