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@mariolouis thank you that was my inclination as well
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Posted: 2003-01-31 08:24:00
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Well, the 850 Mhz networks most likely will be EGSM ones
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Posted: 2003-01-31 09:01:00
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The NEC phone looks almost exactly like the GD87. Too bad these phones are not readily available in the states. Lucky me, I have a GD87.
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Posted: 2003-01-31 18:39:00
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The advantage of quadband phones over triband ones will be their ability to offer roaming in rural USA and elsewhere in America where the old 850MHz TDMA networks will switch to GSM. 1900 GSM does not provide sufficient coverage plus 850 has more range.
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Posted: 2003-02-01 00:46:00
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A gait phone is tdma and gsm. Only Nokia has one on the market.currently. The motorola c331 is 850 mhz? Dont think so? Liken that V600 tho!
This message was posted from a T39
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Posted: 2003-02-01 05:02:00
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Quadband GSM IS an accurate term has very little to do with GAIT. There are active working 850MHz GSM networks today, as well as US operators selling 850/1900MHz NON GAIT phones.
That said theres three things at play:
1) GAIT:
This technology is used to facilitate the transition to GSM from TDMA. GAIT allows supported handsets and networks to roam between GSM 1900 and TDMA 800.
2) 850Mhz GSM:
This is NOT specific to North America. It does exist, and there will be quadband GSM-only phones available.
3) Mixed GSM and TDMA on the same band:
Remember that TDMA actually runs over AMPS analog frequencies. Mixed TDMA/GSM base stations do channel seperation in a way so that GSM and TDMA channels do not overlap eachother. They should really be considered tri-mode in the US as the FCC apparently requires the carriers to support analog till 2006 - but has no requirements for digital technologies.
The 850MHz GSM band is important in areas where there is a dense population base. Simply put, the 1900MHz GSM band is getting cluttered in those areas. The carriers area approaching the problem either by supporting GAIT or using base stations that support both GSM and TDMA over the 800mhz AMPS band.
But lets backup. TDMA is thrown around too often to refer to D-AMPS networks. Its actually a very generic term that refers to how the radio transmits. TDMA stands for Time Division Multiple Access. For D-AMPS networks this technology refers slicing up a frequency, 30khz in width, and sharing it between three handsets. This is where you get the "Time Division" part. You transmit your digital signal for a very small period of time, then two other phones transmit and it comes back to you. Its a little more complicaed than that - but you get the idea. It is important to understand this because technologies like D-AMPS, GSM, PDC (Japan), and iDen (Nextel) are ALL TDMA technologies. They simply go about the time division differently. GSM for example divides a frequency with a width of 200khz into 8 time slots but the transmit time per slot is much much shorter thus you get something like 217 cycles per second with GSM vs 50 with D-AMPS.
Traditional AMPS (analog, the D-Amps stands for Digital - and by the way AMPS stands for American Mobile Phone System) gives each handset 30khz with no time division (because its an analog signal, you can't do that). So you can see why an analog call is more expensive - you can fit three times the number of calls onto a single cell using TDMA technology (D-AMPS). You can also see how its possible to mix both GSM and D-AMPS onto the same band. You simply set aside a certain number of cells for GSM and a certain number for D-AMPS. This can be done on the fly so long as the GSM and D-AMPS do not overlap. This is tricky, and there is loss of spectrum because a GSM cell is 200Khz supporting 8divisions and D-AMPS is 30khz supporting 3 divisions. The problem here is that 200 does not divide bye 30 evenly.
In the US each provider gets about 20Mhz of spectrum that they divide into cells (no provider is allowed to have more than 1/3 of the available spectrum). To quote a good article on the subject:
"In an ideal cellular network, hexagonal cells are arranged in a honeycomb structure, each using a third of the available spectrum to prevent interference". This presents another problem for GSM and D-AMPS to coexist. The BTS is present on each panel (antenna) but in many cases the you don't have a 200mhz continous bandwidth per pannel (panels are designed to have limited verical bandwidth so that spectrum can be easily reused). In rural areas that use dipole antennas this won't be a problem.
Also note that non-tdma providers are eligible to use the 800mhz band so long as the provide AMPS (analog) coverage, and this requirement is only valid till 2006.
If you still didn't follow, read this article:
http://www.networkmagazine.com/article/NMG20000517S0169
I hope this helps dispel some of the inaccuracies posted in this thread.
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I should also note (since this thread is about quadband) that no there are not any phones available yet (that I know of) but the circuitry for such technologies IS available and its only a matter of time till the manufacturers start producing them.
[ This Message was edited by: highrez on 2003-02-01 09:16 ]
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Posted: 2003-02-01 10:11:00
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@highrez
Thanks for the info. I'm somewhat of a cellular amateur learner, it's always curious to learn new things. However, just a couple of quick remarks.
The FCC has mandated that AMPS technology be supported until 2008, not 2006 (visit
http://wireless.fcc.gov/services/cellular/operations/findingaserviceprovider.html#differences )
The only quad band phone in existence today is the NEC 515. Somoeone already posted something about it.
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Posted: 2003-02-01 22:45:00
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devis45
Interesting, thanks for the update.
With all of the changes going on in the wireless industry it'll be interesting to see what happens next. Sadly, this is the reason I won't be buying a P800 (no GSM 850 support) - well probbably not. I'll have to look into that NEC phone.
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Its also interesting to note the discrepancy between the explanation of the acronym AMPS. It looks like its sometimes also referred to as 'Advanced Mobile Phone Service'. I've seen some papers that use both expansions of the acronym on the same page. Quite confusing.
Can the 515 actually be bought anywhere yet? Everything I've found on it says "soon". The phone looks nice, though I'm not a big fan of clamshells - maybe I'll have to give one a try and see if I can't change my mind.
[ This Message was edited by: highrez on 2003-02-01 22:50 ]
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Posted: 2003-02-01 23:18:00
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The GAIT phones are designed to do tdma, analog, and gsm 850 and 1900. They are not, and will not, be world phones. Cingular is going to replace all their tdma towers with gsm 850, and eventually do away with tdma completely. Supposedly, we are also going to add gsm 850 modules to our existing towers that don't even have tdma at this time. There are 2 phones that we offer, the nokia 6340 and the ericsson 62u. The "i" version of the nokia and the t62u have the gsm 850 in it. Right now, gsm 850 is only operational in kentucky and indiana. Most of the other phones that Cingular is going to offer will be gsm 850 and 1900 only.
One reason for this is that it will allow Cingular to have nationwide compatibility for its phones. If you have a sim problem, you will be screwed for at least a couple days, since different markets will have diff sims.
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Posted: 2003-02-02 20:03:00
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@highrez
I'm not a big fan of clamshells too... but I do have a clamshell now
The Panasonic GD87. I guess after all the design is just one thing, whereas the functionalities are something entirely different.
@porterg
My understanding was that Cingular did CDMA not TDMA, or was I mistaken? I say this because with my old Verizon phone I've roamed in the Cingular CDMA network in New Orleans.
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Posted: 2003-02-03 02:02:00
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