Subject: [NEXTEL-1] Broadband Power Line Tutorial

From: [email-masked]
Date: Sun, 14 Sep 2003 03:19:37 -0400

Broadband Power Line Tutorial

By James Stenger

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 lines.
On April 23, 2003, the FCC adopted a Notice of Inquiry (NOI), expressing
enthusiasm about the potential of the BPL technology to enable electric
power lines to function as a third wire into the home, and create
competition with the copper telephone line and cable television coaxial
cable line. The FCC said that BPL service can be offered now using BPL
modems that comply with existing FCC Rules. However, the FCC also asked
whether changes to its rules are needed, either to remove unnecessary
barriers to BPL service or to protect other devices from interference from
BPL modems.

BPL 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. Products for in-home
networking using the electric outlets in your home (or office) are available
in stores now. In-house BPL products can comply relatively easily with the
radiated emissions limits in Part 15 of the FCC's Rules, because the
products connect directly with the low voltage electric lines inside your
home or office. In-home networking, while exciting and innovative, is not a
major policy concern for the FCC. What the FCC is really wrestling with is
how to get broadband Internet access over "the last mile" to the home.

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. Medium voltage power lines are the electric lines that you
see at the top of electric utility poles beside the roadways in areas that
do not have underground electric service. Typically there are three electric
lines (called phases A, B and C), each carrying several thousand volts. One
phase is usually enough to power the houses on a residential street, two or
even three phases can be joined together to power the big electric motors in
an industrial or commercial area. (You also may see a fourth wire that is
the ground wire.)

Inductive couplers are used to connect BPL modems to the medium voltage
power lines. An inductive coupler transfers the communications signal onto
the power line by wrapping around the line, without directly connecting to
the line. A major challenge is how to deliver the signal from the medium
voltage line to the low voltage line that enters your house, because the
transformer that lowers the electric power from several thousands volts down
to 220/110 is a potential road block to the broadband signal. Several
methods are now available that successfully solve this problem.

Interference issues between unlicensed devices, including BPL modems, and
other electronic devices are governed by Part 15 of the FCC's Rules. All
electronic devices sold in the U.S. have to meet FCC radio frequency (RF)
emissions limits. When BPL modems are installed on underground electric
lines, the communications signal is shielded by the conduit and the earth
and as a result is unlikely to cause interference to other communications
services. The FCC is more concerned about the interference potential of BPL
signals transmitted on exposed, overhead medium voltage power lines.

Public comment responding to the NOI on BPL is invited by the FCC, both from
the proponents of the new BPL service, i.e., electric utilities and BPL
vendors, as well as those who might be impacted by the BPL signals. For
example, on most electric utility poles you will notice that below the four
electric utility lines there is a lower segment of the pole where telephone
and cable television wires are attached (referred to as the communications
space). One of the questions the FCC asks is whether radiated signals from
access BPL systems on the electric power lines would interfere with signals
on the cable and telephone lines, and vice versa. We can expect a lively
debate in the comments filed in response to the NOI on this issue, since the
parties involved are competing for the same customers.

A more intelligent electric power grid. Speaking of competitors, why should
we care about any of this when 3G wireless cellular telephone networks,
wireless in-home networking and Wi-Fi hotspots claim to have the answer to
delivering broadband to everyone? Electric utilities are not just looking at
BPL as a way of entering the communications business. In fact, they may want
to leave that part of BPL to a partner, perhaps an ISP, a CLEC or a long
distance company looking for an alternative last mile path to their
customers. Electric utilities are interested in BPL because it can give them
an intelligent electric distribution grid. This could result in lower
electric power costs, less pollution and greater reliability and security.

A better connected appliance. What's interesting about BPL is that every
electric device is connected to the electric distribution network.
Potentially then, BPL could let chips in every electric device talk to each
other. Could we put a Wi-Fi, Blue Tooth or other wireless chip in every
appliance? Yes - but BPL may be a better solution. Those who had PC's before
the Internet exploded remember the difference in functionality between a
standalone PC and a networked PC. Networking every electric device together
over the power lines might result in a similar growth in productivity and
convenience for your home and office.

http://www.wave-report.com/tutorials/bpl.htm

========================================================================

FCC NOI
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-03-100A1.pdf

The HomePlug Alliance
http://www.homeplug.org/index_basic.html
WAVE Articles on Power Line Communications

CITI Powerline Communications III (March 2003)
http://www.wave-report.com/other-html-files/citipowerline3.htm

UPLC Annual Conference 2002
 http://www.wave-report.com/other-html-files/uplc2002.htm

CITI Powerline Communications II (August 2002)
http://www.wave-report.com/other-html-files/citipowerline2.htm

PLCA  - Power Line Communications Association
http://www.plca.net/

EPRI - Electric Power Research Institute
http://www.epri.com/

About the Author
The author of this tutorial on BPL, James A. Stenger, is a telecom lawyer in
Washington, D.C. He worked on BPL for two years leading up to the FCC NOI
adopted in April, 2003. He recently spoke on BPL at ISPCON 2003.

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