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[FYI] (Fwd) Article: A Public Forum That's On Our Wavelength
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Date: Mon, 4 Jan 1999 16:32:08 -0500 (EST)
From: Andy Oram <firstname.lastname@example.org>
Subject: Article: A Public Forum That's On Our Wavelength
A PUBLIC FORUM THAT'S ON OUR WAVELENGTH
by Andy Oram
American Reporter Correspondent
CAMBRIDGE, MASS. -- Wouldn't you like to end the local
telephone monopoly for once and for all? How about offering digital
networks to school systems while sparing them the expense of tearing
up their walls to install wiring? And consider even grander wireless
visions, such as devices that can find hikers lost in a snowstorm or
the land mines that beset old battlegrounds.
All these hopes converged, along with even more startling
possibilities, in the many responses posted last month to an FCC
notice that suggested opening up a wide range of the radio spectrum to
digital transmissions. This notice, released by the FCC on September
1, referred to a class of devices called "ultra-wideband transmission
Companies interested in ultra-wideband technology propose a
number of interesting applications in radar and other particular
areas. But of most interest to the public is the possibility of using
the spectrum for general-purpose Internet access, transmitting packets
at blazing speeds without the need for costly phone lines.
The Internet is ideal for digital radio transmissions. The
characteristics that make it robust over wires are even better suited
to radio. Because the Internet Protocol breaks data into small packets
that can be sent in any order or at any speed, and because
higher-level protocols handle lost packets elegantly, the protocol
offers a built-in response to the natural noise and unreliability of
Democratic activists often speak of the importance of "public
spaces" like town meetings and city squares, where communities can
share ideas outside the control of commercial or government
rulekeepers. Just as the malling of America has reduced the time that
people spend in public spaces, the commercial division of the radio
spectrum threatens to fence in the media that most of us use for
information and entertainment.
Over the past decades, a proliferation of new technologies --
particularly cellular phones and digital television broadcasting --
has driven the FCC to sell or give away huge ranges of spectrum. These
ranges are strictly controlled by the companies who win them and
exploited for the highest-paying application, whether it be telephones
for the affluent or sports programming with high advertising
Thus, the aforementioned democratic activists have applauded
the idea of saving some of the spectrum as a "public space." Internet
radio is the perfect medium to use in that space.
In a seemingly magical defiance of everyday assumptions about
spectrum, everybody and anybody can transmit simultaneously in a
digital packet radio system. The system operates like Ethernet on a
campus network, where each device listens to just the transmissions it
wants to receive. But given the right frequency range, digital radio
can stretch much farther geographically than a campus network, and
send a large quantity of data faster.
Traditional radio broadcasting exploits, fairly uniformly, a
range of spectrum assigned by the FCC (or whatever body is responsible
in each country). For instance, suppose you tune your radio to station
90.1 FM. This means the radio will receive all radio waves coming
through the air from 90025 to 90175 kilohertz (thousands of vibrations
The frequency of the radio waves in FM radio map directly to
the frequency of pitches in the sounds being transmitted. Thus, the
lowest note that can be sent over the radio will be transmitted at
90025 kilohertz, and the highest overtone at 90175 kilohertz.
Note that the lower and upper limits represent a band slightly
less than 200 kilohertz in width. This number is a typical, moderate
amount of bandwidth. The whole band is centered on 90100 kilohertz or
90.1 megahertz, which gives the station its call number.
Digital transmissions operate in a completely different
manner. They use the range of frequencies available to the device as a
set of numbers to play with. Then they encode data using algorithms
that squeeze as much information into the bandwidth as possible (along
with compression, error-checking, and probably encryption for
Typically, the code is sent as a sequence of extremely short
pulses -- perhaps shorter than a nanosecond, which is one billionth of
a second. While copper phone lines struggle to deliver 56 kilobits a
second (or 1.5 megabits over the new ADSL technologies) comments to
the FCC on ultra-wideband transmission promised transmission speeds in
the gigabit range, given a sufficiently broad frequency range.
There are two questions to answer before permitting
ultra-wideband transmission. The first is whether the spectrum should
be used for these applications rather than to expand older offerings
like cellular phones. The conflict over limited spectrum makes enemies
of the cellular phone companies, represented by the Wireless
Information Networks Forum, or WINForum.
The second question is whether ultra-wideband transmissions
could interfere with current applications. A blip on your fancy
thousand-dollar digital TV screen would certainly be annoying; a
jammed transmission from an air traffic control tower to a pilot could
have somewhat worse consequences.
Thus, it is no surprise that the main question that commenters
to the FCC wrangled over was whether ultra-wideband would cause
significant interference. On the cautionary side lay the WINForum and
other users of existing applications; the more sanguine responders
included companies that create digital devices for various
purposes. While both sides submitted models filled with mind-numbing
equations, they tended to talk past each other.
WINForum devotes many pages to finding the rate of
interference (as a function of the speed with which the digital
devices transmit pulses, the bandwidth of the device that is being
interfered with, or both). But interestingly, they do not try to
predict the amount of interference that would hurt operation.
Their submission says that "the current rules permit high
relative levels of interference...for some emission types" and "the
rules are excessively strict for some emission types." While advising
limits on the power of ultra-wideband devices, the submission does not
go so far as to say categorically that the levels of interference are
expected to be harmful.
The most concrete -- and alarming -- evidence in the WINForum
comments comes in a table comparing normal noise to potential
interference from digital devices. The worst case shows an enormous
amount of interference (ten thousand times as much as normal noise), a
But the conditions under which this amount of interference
would occur are a high rate of transmissions in a narrow frequency
range -- not the actual conditions called for in the ultra-wideband
proposal. The conditions used by real devices in this proposal are
closer to those shown in the opposite corner of the table, where
interference is shown to be only a few times greater than normal
A more forgiving comment comes from Multispectral Solutions,
claiming that ultra-wideband devices should be prohibited from
frequencies used by current applications. It softens this requirement
by saying that common forms of control over signals "can result in
systems which can avoid operation in restricted bands." In other
words, the comment believes ultra-wideband devices are still feasible
even with restrictions on the frequencies used.
More than one comment measured the output of an ultra-wideband
digital device against that of a personal computer and found them very
similar. The personal computer is just one example of the hundreds of
types of everyday equipment that emit noise in the frequencies
occupied by current applications but obviously do not interfere with
these applications. The commenters thus claim that the digital
devices are safe.
For instance, the Time Domain Corporation says that "literally
billions" of devices already emit noise in the frequencies that the
FCC has to protect. And the XtremeSpectrum telecom company, claiming
to use its own "worst case assumptions," finds that the cumulative
effects of many devices would be no worse than the interference of a
single device. Their model was confirmed by the Interval Research
Corporation, who concluded that "substantial noise build-up does not
and will not occur."
Ultra-wideband proponents go so far as to suggest that these
devices can make good use of an overcrowded spectrum precisely because
they use the same frequencies as traditional applications like
television. The TV station and the Internet digital device can share
the frequencies, each using it in a way appropriate to its medium
without knowing each other exists.
The current FCC inquiry is not the first time a public space
for digital radio has been proposed. In 1995, the FCC received a
petition for bandwidth that could be used by schools and other public
institutions for low-cost digital transmissions. The source of the
petition, interestingly, was neither a phone company nor a public
interest group, but Apple Computer.
In 1997, the FCC did allocate some of the requested spectrum
in what it called Unlicensed National Information Infrastructure
(UNII) bands. The name reflected the rhetoric of the time, but the
allocation was severely limited and found almost no takers.
Community networking expert Dave Hughes, in his typically
frank comment to the current inquiry, calls the UNII allocation a
failure. It was supposed to permit low-cost devices, extend over wide
areas so as to facilitate rural communications, and offer high
bandwidth, but fell hopelessly short in all three promises.
Hughes reports that a typical device for UNII costs nine
thousand dollars, operates at a range of only three miles, and
delivers measly bandwidth. He enthusiastically supports the current
ultra-wideband proposal and has done more than everyone else put
together to publicize the issue.
Yesterday was the deadline for comments to the FCC on
ultra-wideband. Given the clashing views of experts from different
sides and the low visibility that the issue has in the public eye, the
FCC will probably take quite a while to decide whether the technology
becomes an everyday reality.
Andy Oram is moderator of the Cyber Rights mailing list for
Computer Professionals for Social Responsibility, and an editor at
O'Reilly & Associates.
This opinion piece appears tomorrow in the American Reporter (go to
http://www.american-reporter.com/ and look under "Ideas and Columns").
On Wednesday the piece will also be found online (along with suitable
hypertext links and an index of related articles) at:
The article can be redistributed online, with author and newspaper
attributions intact, for non-profit use. For printing or commercial
use, please contact Joe Shea, publisher of the American Reporter, at
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