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"Speaking of George Gilder": an
Excerpt
WirelessNOW presents the first of a series of excerpts from
the new book "Speaking of George Gilder," a compilation of
essays, speeches and interviews featuring the
sometimes-controversial industry notable. According to
author Frank Gregorsky, this book "is the only George
Gilder book for those with short attention spans - in short, a
Gilder assembly for the stressed-out majority."
Among his many accomplishments, Gilder was a co-founder of the
Discovery Institute in Seattle, where he was named the first senior
fellow and head of the group's technology and public-policy
program. He also co-launched "Forbes ASAP," a division of the
parent Forbes magazine group. Gilder also authors "The Gilder
Technology Report" newsletter, which is regarded as a digital
compass for investors.
In this first tidbit, Gilder participates in a 1997 Q&A session with
members of the IEEE regarding CDMA and its capabilities. In light
of current 3G wrangling over standards, this piece still is pertinent
today.
IEEE: You've been following the war between CDMA and TDMA
for dominance of the digital cellular and PCS markets. What is
happening in this arena?
GILDER: CDMA was launched in 1989 by Qualcomm, led by
Andrew Viterbi and Irwin Jacobs. It represents many technologies -
Java is another - that baffle the backers of its rivals by prevailing
against all odds because it fits with the dynamics of the Internet.
CDMA is a direct-sequence spread-spectrum solution that attracted
me because of its elegance for data bandwidth on demand and its
use of information theory - the concept of broadband noise as the
highest density source of information. I've been pushing it since
1989. It accords with Claude Shannon's thesis that digital
bandwidth can serve as a replacement for both power and
switching. This trade-off will become more and more attractive as
battery-powered mobile computers move up spectrum where
bandwidth is plentiful.
But it's a war out there. With 25 million mobile phones globally,
GSM is the only successful industrial policy of the European
Economic Community, period. The EEC contrived GSM in
response to the proliferation of analog standards in Europe, which
prevented roaming. There was a different analog standard in each
country.
By contrast, we had AMPS and a coherent analog mobile phone
system. So the EEC mandated GSM, a very conservative standard
with 200 kHz channels that achieved only a three-fold advantage
over analog. Nonetheless, it allowed Europe to jump ahead to
digital before we did. When Qualcomm introduced CDMA, it
precipitated one of the most dramatic standards battles ever.
IEEE: Why is it so intense?
GILDER: Even so it would seem today that, with 25 million
phones, GSM pretty much prevails. In fact, the potential for wireless
local loops, wireless Internet access and all the other applications of
PCS is so immense that 25 million represents only the beginning of
the game. And, although GSM certainly is a viable technology, it
looks like it will not prevail as the dominant global standard.
Suddenly, CDMA is taking off like a rocket.
For some reason, people were unusually intense in opposition to
CDMA technology. Bruce Lusignan, a brilliant professor of
electrical engineering at Stanford, said that CDMA, as Qualcomm
described it, violates the laws of physics, and this was quoted over
and over again. So the laws of physics - laws of God, if you will -
were involved in this debate! And because it was said to violate the
laws of physics, lots of people jumped to the conclusion that Irwin
Jacobs and Andrew Viterbi (of the Viterbi algorithm fame) were
pushing a technology scam.
IEEE: So this was the "cold fusion" of telephony?
GILDER: Yes. To old analog hands, CDMA seemed too good to
be true. It exploits the special advantages of digital which, unlike
analog, improves by the square of the bandwidth and requires
signal-to-noise ratios 40 dB lower. The same codes that spread out
the signal are inverted and used to "de-spread" it at the receiver.
The signal pops out above the background-noise level, and the real
noise spikes and ingress are spread and sink below the
background-noise levels.
It's magic if you don't get it.
I spent a fascinating day with Lusignan, and while he started by
trying to persuade me that, theoretically, no gains are realized by
moving from frequencies or time slots to codes, he ended up by
arguing quite earnestly that there was no reason to go digital. He
saw analog as elegant, efficient, convenient, robust, and just great,
and as incorporating a whole array of his patents.
When I discovered that the most sophisticated opponent of CDMA
was really opposing the whole digital revolution, it seemed to me
that the case was collapsing.
I then went to Thomas Cover, the leading information theorist at
Stanford. Cover likes CDMA, but confirmed that, in theory, a
time-division system would have just as much bandwidth as a
code-division system.
IEEE: So does CDMA give real gains?
GILDER: Yes. It works in practice but not in theory. Lusignan, of
course, is right that, in Shannon's terms, it does not matter how you
slice up the bandwidth. The limit will remain the same. But CDMA's
advantages derive from the efficiencies of digital, the exponential
advance of microchips and the decline of time-division multiplexing
for all data applications.
Whether in wires or in the air, TDMA is failing for data because it
does not correspond to the bursty flows of bits. Some time slots are
empty and others are flooded. If TDMA didn't work efficiently for
data in wires, how was it going to work in wireless? When I saw
that, I knew CDMA would prevail, because obviously Internet data
would be an absolutely essential application of any new-generation
wireless technology.
The key advantage of CDMA is it uses all the spectrum all the time,
so that it can accommodate bursts and it can accommodate
bandwidth on demand.
Also, the people who said it wouldn't work said it was too complex.
But, in digital semiconductors, the complexity sinks into the chip and
becomes simple. And so the fact that it was too complex in 1989 or
1990 was not relevant to 1995 or 1996, when you could put the
whole thing on a single ASIC, as Qualcomm is now doing.
IEEE: So, is CDMA working?
GILDER: It had its problems in the beginning. Managing all the
codes and power levels is very complex with CDMA. All signals
have to be received at about the same power or the system doesn't
work. Power was going to be a critical issue anyway because, with
any wireless application, battery issues are central. The CDMA
people had to solve the power-control issue, and they did.
Lo and behold, it turns out that power is a lot simpler to control than
time slots and frequency channels. As a result, CDMA uses
between one-tenth and one one-thousandth the average transmit
power of ordinary AMPS and GSM. This is radically more efficient,
and it's another huge win for CDMA.
(Editor's note: For more information regarding "Speaking of George
Gilder," contact Robert Crowther at the Discovery Institute,
206-292-0401, extension 107.)
This material is COPYRIGHT 1998 BY
CommunicationsNOW
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