When GTE Mobilnet went digital here in Texas about 8 years ago, they went CDMA and I got a Motorola CDMA-type Startac.
Then, about 3 years ago when GTE Mobilnet merged into Cingular, they ripped out the CDMA infrastructure and went to TDMA. (Note that the article says Cingular went GSM, but that's not the case in Texas.)
Now, I worked for Motorola since before there were cellphones and followed their development from the beginning. Although Motorola was slow--disastrously slow, as it turned out--to switch their product line to digital, they were an early exponent of CDMA. (They also faced reality and actively developed and promoted GSM products in Europe.)
I was puzzled why Cingular took this apparent step backward, from CDMA to TDMA; I must assume that there was much more TDMA infrastructure in place among the companies that made up Cingular, and therefore the CDMA companies had to switch.
I had to get Cingular to change out not only my phone but also my permanent car adapter kit. And for the first time, I had to go to Motorola's (conquering) enemy, Nokia, for the phone.
Now, I'm wondering if Cingular will eventually scrap their TDMA and go to 3G (CDMA2K). I kind of hope so, at least if they'll swap my phone again
<)B^).
As to the voice quality, there is a tradeoff between clarity (and reliability) of calls on the one hand, and the battery consumption and number of available conversations on a channel, on the other. The engineers designing the digital systems (of whatever type) did a great deal of experimentation to see how not to give any more audio quality than analog systems, so that they could maximize the number of channels that a given site, and a given number of channels, could support.
In my experience and 'umble opinion, they shortchanged us a bit on the quality.
One final comment about the way technical standards are set in different areas of the world.
The author makes the point that the uniform and orderly adoption of an early digital cellular standard in Europe was both a blessing and a curse.
Something like this occurred with regard to high-definition TV in Japan. Like Europe, Japan has an infrastructure for making national technical decisions that is politically stronger than in the U.S. Like Europe with digital cellphones, Japan came to an early consensus on how they would implement a high-definition TV system. The US, on the other hand, had a comparatively messy and slow pluralistic approach. Well, something funny happened after the Japanese decided on their system, which was analog: namely, affordable massive digital computing power. So the US eventually adopted a digital HDTV standard, which essentially obsoleted the Japanese approach.
(Note that the article says Cingular went GSM, but that's not the case in Texas.)A conversion to GPRS (GSM) has commenced withing the old Southwestern Bell Mobile Systems/Cingular network. It seems that thismis the next de facto standard for 800 MHz Cellular among the biggies ...
Now, I worked for Motorola since before there were cellphones and followed their development from the beginning. Although Motorola was slow--disastrously slow, as it turned out--to switch their product line to digital, they were an early exponent of CDMA. (They also faced reality and actively developed and promoted GSM products in Europe.)Moto *had* teamed with Nortel for awhile - then that marriage fell apart ...
At one point we picked up a an engineer from Moto named Michael Thomas who had been with one of the teams in Ft. Worth doing CDMA development - he didn't seem to think they were making much progress at the time.
Shortly thereafter I had a chance to 'optimize' and massage some cellular system parameters in a small Motorola sytem and was NOT impressed with the operation of the Moto switch OR the operation of base station cellular infrastructure equipment. It was not as completely instrumented and the data backhauled (signal strengths, current serving cell and sector number, etc) as the Ericsson RBS 882 equipment was.
I was puzzled why Cingular took this apparent step backward, from CDMA to TDMA; I must assume that there was much more TDMA infrastructure in place among the companies that made up Cingular, and therefore the CDMA companies had to switch.All of Bell's gear was TDMA (IS-54 then later IS-136). When they bought out somebody else they changed-out that gear (it seems).
Now, I'm wondering if Cingular will eventually scrap their TDMA and go to 3G (CDMA2K). I kind of hope so, at least if they'll swap my phone again <)B^).They have made commitments to go GPRS (GSM format).
Source:
FCC's SEVENTH REPORT to Congress
Adopted: June 13, 2002 Released: July 3, 2002
Excerpt:
Cingular Wireless/AT&T Wireless – In January 2002, Cingular Wireless and AT&T Wirele ss announced the formation of an infrastructure joint venture to build out a GSM/GPRS network along 3,000 miles of interstate highways predominantly in western and midwestern states.---
TDMA is being phased out as its main advocates, AT&T Wireless and Cingular Wireless, have announced plans to overlay their existing TDMA networks with GSM/GPRS technology.159 Furthermore, the trade group that had represented TDMA technology announced in December 2001 that it was dissolving, as it had “successfully served its mission.”160
AT&T Wireless still expects to use TDMA for many years, but as reported in the Sixth Report, the company announced plans to overlay GSM/GPRS on its TDMA network in order to improve its wireless data capabilities and enhance its migration to 3G technology.161 By the end of 2001, AT&T Wireless had rolled out GSM/GPRS to 45 percent of the POPs covered by its network.162 AT&T Wireless has also announced that it plans to deploy GSM/GPRS in the network that it recently acquired through the purchase of TeleCorp.163
Cingular Wireless, which currently has a mix of TDMA (covering 70 percent of its POPs) and GSM (covering 30 percent of its POPs) networks, announced in October 2001 that it would overbuild its entire TDMA and remaining analog networks with GSM/GPRS.164 Cingular Wireless expects to have 50 percent of its POPs covered with GSM by the end of 2002 and the remainder covered by the end of 2003.165 Cingular Wireless will continue to provide TDMA service to its current customers, but it expects that many will upgrade to its GSM technology over time.166 Cingular Wireless said the national network upgrade will cost approximately $3 billion.167 And, as noted above, Cingular Wireless and AT&T Wireless have announced plans to build a GSM/GPRS network along 3,000 miles of interstate highways in a number of western and midwestern states.168
As a result of these industry developments, this report no longer distinguishes between TDMA and GSM networks in its analysis of digital coverage, but considers the two as one migration path towards more advanced digital capabilities. We recognize that TDMA as currently deployed will continue to be used by millions of subscribers for a number of years. Of the other four nationwide mobile telephone operators, Sprint PCS and Verizon Wireless use CDMA as their digital technology, VoiceStream uses GSM, and Nextel uses iDEN.