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TECH TALK: Next-Generation Networks: BPL

August 12th, 2005 · No Comments

Another technology which has been getting some buzz in recent times is broadband over power lines. The idea has been around for a long time. Wave Report writes:

Broadband power line (BPL) is the term coined by the FCC for new modems (BPL modems) used to deliver IP-based broadband services on electric power linesBPL modems use silicon chips designed to send signals over electric power lines, much like cable and DSL modems use silicon chips designed to send signals over cable and telephone lines. Advances in processing power enable new BPL modem chips to overcome difficulties in sending communications signals over the electric power lines that could not be overcome with less computing power. BPL modem speed, like cable and DSL modem speeds, is changing rapidly with each advance in new technology, so it would be difficult to make any generalization here that would be accurate or timely.

The FCC NOI discusses two types of BPL, In-house BPL and Access BPL. In-house BPL is a home networking technology that uses the transmission standards developed by the HomePlug Alliance. Access BPL is a new technology to carry broadband Internet traffic over medium voltage power lines. BPL modems that electric utilities and their service partners can install on the electric distribution network also are available now.

HowStuffWorks writes about how BPL works:

Both electricity and the RF used to transmit data vibrate at certain frequencies. In order for data to transmit cleanly from point to point, it must have a dedicated band of the radio spectrum at which to vibrate without interference from other sources.

Hundreds of thousands of volts of electricity don’t vibrate at a consistent frequency. That amount of power jumps all over the spectrum. As it spikes and hums along, it creates all kinds of interference. If it spikes at a frequency that is the same as the RF used to transmit data, then it will cancel out that signal and the data transmission will be dropped or damaged en route.

BPL bypasses this problem by avoiding high-voltage power lines all together. The system drops the data off of traditional fiber-optic lines downstream, onto the much more manageable 7,200 volts of medium-voltage power lines.
Once dropped on the medium-voltage lines, the data can only travel so far before it degrades. To counter this, special devices are installed on the lines to act as repeaters. The repeaters take in the data and repeat it in a new transmission, amplifying it for the next leg of the journey.

Recent investments by Google and IBM in this space have given it greater visibility. eWeek wrote:

Using a low-cost adapter, BPL (broadband over power line) customers can get high-speed Internet service using the wiring that already exists in their homes or offices.

The technology has been touted as having a number of benefits for users as well as for utility companies. Not only can it deliver broadband to areas that lack DSL or cable service, advocates say, but it also can boost power service reliability and track outage information more accurately by using network tracking capability.

Although utilities and technology companies have been tinkering with using power lines to carry data for nearly 20 years, within the past five years there has been increasing interest in commercialization.

Next Week: NGN (continued)


TECH TALK Next-Generation Networks+T

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