Subject: [NEXTEL-1] Commentary 4Mobility - Me Thinks They Doth Protest Too Much! - 3 December 2002

From: Marcel <[email-masked]>
Date: Tue, 03 Dec 2002 21:25:43 -0500

Me Thinks They Doth Protest Too Much!

The 3G Americas organization, which represents the GSM/GPRS/EDGE/UMTS/WCDMA camp in the
Americas, has published yet another white paper, this one "proving" that
GSM/GPRS/EDGE/UMTS/WCDMA is the most spectral efficient set of technologies on the face of
the planet and that companies that have decided to embrace these wireless digital
standards have made the correct choice.

I don't understand why these folks feel the need to publish these white papers. Since most
wireless networks in the Americas have already decided which migration path to take, such
papers are not designed to convince network owners that they should embrace the
GSM/GPRS/EDGE/WCDMA migration path. I suspect that these papers are designed to assure
companies that have decided on this path that they made the "right" decision. It reminds
me of a group of venture capitalists who years ago invested in pen computing technologies.
They all went to a conference on pen computing and spent their time assuring each other
that they had made a wise investment.

The author of this 3G Americas report as well as the report that claims that GSM can
become more spectrally efficient happens to be a colleague and friend. Unfortunately, he
based these projects on information provided to him from the GSM community. I can find no
evidence that any of the "facts" presented were verified against information from the
CDMA2000 community, Qualcomm or the CDMA Developers Group. There are no systems that meet
the final UMTS specifications and there are only a few WCDMA systems in operation. Since
not all of these are in full operation, it is difficult to compare and contrast what is
real and working versus what has been promised but not delivered. On the other hand, there
are twenty-four CDMA2000 1X and three CDMA 2000 1xEV-DO systems in full commercial
operation.

The Issues

The issues I have with the report as published have to do with statements such as the
following:

1) GPRS IP packet data service delivers effective throughputs of up to 40 Kbps using
coding schemes 1-2.
a. This is a misrepresentation. The GSM community added the downlink and uplink data
speeds together to come up with this number. The current technology supports about 10 Kbps
per time slot. A GPRS system that uses two time slots from the cell site to the mobile
device and one time slot from the mobile device to the cell site is providing 20 Kbps down
to the device and 10 Kbps from the device to the cell site. The GPRS community would call
this a 30-Kbps system.

2) GPRS coding schemes 1-4, this option for operators boosts speeds of GPRS service by 33%
and increases capacity.
a. This is true. However, the coding scheme that can be used depends upon how "clean"
the airlink is between the mobile device and the base station. The more interference or
noise there is, the lower the coding scheme that must be used and, therefore, the lower
the data rates. The only way that an operator gets this 33% speed increase and increased
capacity is if the air link is really "clean."

3) EDGE third-generation technology effectively triples GPRS data rates and doubles its
spectral efficiency.
a. An interesting claim and I will concede this point with the caveat that EDGE data rates
degrade as one moves away from the center of a cell. In fact, test results I have reviewed
show that EDGE coverage at full data rates will require at least a 33% increase in the
number of GPRS cell sites.
b. However, it now appears as if the first EDGE phones will use EDGE only in an outbound
direction, and will use existing GPRS technology from the phone back to the network. This
may help the coverage issue but limits the uplink to a practical speed of 20 Kbps (2 slots
of GPRS).

4) WCDMA radio link supports flexible, integrated voice/data services with peak rates of 2
Mbits/second
a. I will have to take issue with this statement. Of the three WCDMA systems operating
today (only NTT DoCoMos FOMA system is commercial), none offer data rates anywhere near
this speed. In fact, the newest system in final testing by J-Phone in Japan is not
offering ANY data. As voice traffic increases, data rates decline; as data traffic
increases, voice traffic capacity declines.
b. Because WCDMA uses a single 5-MHz carrier, a 10-MHz WCDMA system (5 MHz for cells and 5
MHz for mobiles) supports a single voice-and-data carrier. CDMA2000 1X uses a 1.25-MHz
carrier and can support four carriers on a 10-MHz system. Depending on demand, some of
these carriers can be voice-and-data (data speed peak of 144 Kbps) and some data with
speeds of up to 2 Mbps. Voice and data traffic do not have to be balanced on data-only
carriers and they do not compete for the total bandwidth. This means that a CDMA2000
1xEV-DO system will deliver higher data rates more consistently than a WCDMA system.

5) High Speed Downlink Packet Access (HSDPA), an option for WCDMA that boosts peak data
rates to 10 Mbit/s, the highest of any cellular system.
a. As far as I can tell, HSDPA is not a commercially deployable technology today. It is
easy to publish specifications, harder to prove them and harder yet to implement them.
CDMA2000 1X and 1xEV-DO are in daily operation in multiple networks around the globe.

6) Quality-of-Service and multimedia support, available for EDGE and UMTS/HSDPA, enables
new applications such as video and voice over IP
a. Maybe so, but high-speed data services over WCDMA reduces voice capacity. In a CDMA2000
1xEV-DO system, the EV-DO carrier is used for data so the same number of voice channels
can be accommodated without diminishing data rates.

7) WLAN integration
a. There is no indication that GPRS or WCDMA can be more easily integrated into a Wireless
LAN/Wide-Area network than CDMA2000 1X or CDMA2000 1xEV-DO.

One of the biggest problems I have with this report is that it states that WCDMA
interoperates with GSM. Like this is a big deal. CDMA2000 1X also interoperates with GSM
as proven by tests of GSM 1X, an overlay of CDMA2000 1X and the GSM network that also
makes use of the MAPI backend of GSM. (With either technology the backend backhaul has to
be upgraded to provide for additional data capacity.) It also states that UMTS (WCDMA) is
capable of 2 Mbit/s data rates with average rates of 200-300 Kbit/s. We know from the
Korean and U.S. CDMA2000 1x and EV-DO systems that their average data rate is running at
500-800 Kbps!

One slide in the presentation is more than interesting. It states that EDGE is the most
spectrally efficient technology below 100 Kbit/s (wasnt EDGE supposed to support data
speeds of 384 Kbps?) and that UMTS is the most spectrally efficient above 100 Kbit/s. The
small print states that this is the result of a joint analysis by 3G Americas members and
the assumptions go on and on.

Looking at the charts in this report readers might come to believe that WCDMA is the best
possible technology to employ going forward--unless they understand the differences in
channel widths. A WCDMA system mixes 5-MHz voice-and-data channels with voice having
priority, while CDMA2000 1X mixes and matches voice-and-data and data-only 1.25-MHz
channels. With WCDMA, a 100-Kbps data transmission displaces more than 24 voice calls.
Obviously, mixing and matching data and voice channels makes more sense.

There is one more mitigating factor for GSM/GPRS and UMTS (WCDMA) in Europe where GSM/GPRS
systems are in the 900-MHz and 1800-MHz bands and UMTS will be in the 2100-MHz band. Why
is this important? At 2100 MHz, wireless operators will need to build out more than five
times the number of cell sites they presently have in the 900-MHz band to provide WCDMA
coverage that is equivalent to GMS coverage. Even in Europe where towers are better
accepted, operators will have a problem finding enough sites. If WCDMA is so spectrally
efficient, why will AT&T Wireless, which has more spectrum per market than any other
wireless operator, and Cingular Wireless need additional spectrum in order to build out
their systems while Sprint PCS and Verizon Wireless (CDMA) can provide true 3G
capabilities with the spectrum they now own?

This report has to have been designed to reinforce members' decisions regarding their
system upgrades. I could publish a report complete with documentation, charts, diagrams
and engineering formulas that shows the opposite point of view. Does any of this matter?
End users don't care about the differences between the technologies; they only care about
what the technology will provide in the form of advanced features and services, and at
what price.

What is important to wireless operators is whether they can complete their upgrades
without having to acquire more spectrum, how many device upgrades will be required of
their customers to take full advantage of network upgrades and how soon they can get these
new upgrades into operation. The technical stuff is just that: technical stuff for those
making upgrade decisions. Since most of these decisions have been made, why spend time and
effort on a report like this now?

I can only come up with two reasons. First, of course, is to convince Wall Street that
they are on the right track and Wall Street should not listen to the naysayers who are
growing more vocal about the differences between CDMA and GSM/GPRS. (It is sure nice to
have others chime in with what we have been saying for some time now.) Perhaps some
3G Americas members have been looking around and seeing their competitors offering
advanced services today with a wide range of device choices and wondering if they made the
right technology decision. This report might have also been designed to keep them in the
fold.

                                     Andrew M. Seybold