Comparison between GSM and TDMA cell phones?

[RedRooster]

AT&T is rumored to be converting to a GSM network up here in Canada in the near future. However I'm currently using their TDMA service right now.
I'm looking to renew my contract with them, but would it be smart to wait until they convert to GSM, or should I continue to use their TDMA service(which I'm sure they'll continue to support for a long time)??

The reason I ask is, I want a new phone, and don't mind renewing my contract for another year. As it is now, I'm paying from month-to-month and can quit whenever I want, but I don't mind a contract, as long as I know my phone won't be a piece of crap in a couple months when the GSM network rolls out.

Is GSM worth waiting for?

 

[Shantanu]

Unless I'm sorely mistaken (in which case I will seem like a fool, D'oh), GSM uses TDMA. The two digital phone technologies out there are CDMA and TDMA. In terms of technology, CDMA is superior. In terms of deployment, TDMA (GSM) has the advantage. GSM 800mhz is used all over Asia, and GSM 1800mhz is used all over Europe. GSM 1900mhz is available in most U.S. cities now as well. If you get a tri-band GSM phone, you can travel all over major world cities and use your cell phone.

The main CDMA carrier is Sprint. The main TDMA (GSM) provider here in the U.S. is Voicestream. I personally think Sprint PCS is a lot better, but I went with Voicestream because my area isn't covered by Sprint PCS, which is kind of wierd since Sprint has much better deployment overall in the U.S. Hope this helps.

 

[RedRooster]

Wow, great info!! Thanks for replying!
Our CDMA carrier up here is a crown corporation(government owned phone company) who likes to overcharge terribly, I think that's the original reason I didn't go with them, even though they have much better coverage away from the city.
So I guess I'll be going down to the store tomorrow to find a new phone then, other than worldwide coverage(I've never been overseas), there isn't a huge advantage to GSM over TDMA anyways, by the sounds of it.

 

[Eug]

TDMA is different from GSM.

 

[RedRooster]

In what ways Eug?

 

[Shantanu]

GSM uses TDMA technology. TDMA is a technology. GSM is a standard. GSM uses one of the more advanced and widely deployed TDMA standards. One of the notable aspects of GSM is the usage of a SIM chip. I would say that if you're phone is both: 1900mhz TDMA and has a SIM chip slot, it is probably compatible with the GSM that is being deployed in your area.

 

[Nemesis77]

<<
GSM 800mhz is used all over Asia, and GSM 1800mhz is used all over Europe. GSM 1900mhz is available in most U.S. cities now as well
>>



Actually the system in Europe in 900/1800mhz Dual-band GSM. First it was just 900Mhz GSM, but as airwaves got full, they added the second band. I believe it's the same in Asia, whereas in USA they use 1900Mhz GSM.

If I remember correctly, there's also a 450mhz GSM, but it's not widely used.

 

[phatcow]

GSM is based on a modified TDMS IS136 standard or somehting.



I think they reason they are overlaying is cause of the 3g enhancements.
CDMA is supposed to have something similar.

 

[urameatball]

Another useless fact:
the universe has very few natural objects that radiate at 1800 or 1900mhz level... which is why cellphone providers chose that frequency.
on a side note, astronomers use to have telescopes that scan at those bandwidths to look into the outer regions of space... but now that these frequencies are filled, lots of astronomers are EXTREMELY upset about it cuz all they see at this bandwidth now is interference.

which also leads to my point... if there are extra terrestrial entities with technology similar or better than ours, they would also know that 1800-1900mhz is very rare in the universe, which will lead them to search for spikes in that frequency range. and once they aim their detectors on earth, they'll see a MASSIVE spike in their readings because of our cellphone use. So technically, cellphones are kind of providing a homing beacon for extra terrestrials to find us....


this is the end of another useless fact

 

[CoffeeIsGod]

TDMA and CDMA are the air interfaces

GSM is an international standard which covers everything from SIM cards to cross-billing arangements between carriers.

Most of the world uses GSM 900/1800
US/Canada uses GSM 1900 (with GSM 800 standard agreed but not yet deployed)

AT&T is converting to GSM (and will deploy GSM 800 too once equipment is available). They already have a network in the Seattle area (in fact there are 3 different GSm networks in Seattle now - Cingular, Voicestream and At&T)

As for quality - CDMA as used by sprint is a very bad implementation of CDMA. One of the big problems with all CDMA networks is that the quality of the calls drops as utilization increases. TDMA limits this (you just won't get through).
As far as voice quality goes GSM has by far the best voice quality (when EFR is implemented which it is virtually everywhere these days)

Interestingly most of the 3G technology is based on a CDMA air interface - but is really an evolution of GSM (but with the amounts all the telcos have paid for licenses I really don't know when we are going to see anything from this)