Why does Verizon and China Telecom still use CDMA?

the8thark · Jan 12, 2011

Why does Verizon and China Telecom still use CDMA? When most of the rest of the world and even some in the US use GSM. I'm just boggled why everyone just does not use GSM.

Well it's a question I'd like an answer to please.

rippingviper · Jan 12, 2011

up here in manitoba canada Manitoba telecoms still uses CDMA as well. Though they are supposed to be making the switch to 3g in the next few months. It would be nice since MTS up here has more coverage then Rogers does and 3g everywhere would be nice. CDMA is better then just having Edge up here so just for the fact it goes the distance could be why CDMA still exists. Not to mention it costs ALOT to upgrade networks.

Aptmunich · Jan 12, 2011

History I suppose: It would cost far too much to switch to GSM now, CDMA has a broader ranger per cell tower which is beneficial in large countries such as the US, as you can cover a larger area with fewer towers and perhaps there were other advantages (patents, license fees etc.).

Just wait for LTE to roll around: most european and american carriers have agreed on that standard going forward, so all of these compatibility issues will hopefully subside.

IvanLasston · Jan 12, 2011

For voice - GSM is pretty universal but it suffers from still being a TDMA (Time division Multiplex) type system. You'll hear about dropped calls from the GSM folks here in the US - you just run out of time slots in crowded areas.

CDMA is Code division multiplex - the spread spectrum seems to handle more people better. I've hardly ever had a dropped call when I had full signal CDMA. WIth ATT GSM sitting at my desk - with full bars - I've dropped when too many cars go by.

Here is a long article describing what I said
CDMA vs TDMA

That being said - most everyone is moving to some form of CDMA - the 3g standard adopted by most GSM providers HSDPA - is actually a CDMA technology. Qualcom owns the rights and it sued saying that HSDPA is actually a form of CDMA. They won that suit. Here is a little article on HSDPA.
What is HSDPA?

cwa107 · Jan 12, 2011

In my opinion, GSM was a step backwards in terms of call quality and reliability. My CDMA phones have always been very good - no echoes, no delays in the time the call recipient hears what I'm saying. Every GSM phone I've ever used has always suffered in these ways. Not to mention that they bleed noise onto nearby speakers when you have them too close.

baggss · Jan 12, 2011

cwa107 said:
Not to mention that they bleed noise onto nearby speakers when you have them too close.

That's actually stopped, at least with AT&T since they upgraded their networks. It was a frequency band issue IIRC.

IvanLasston said:
For voice - GSM is pretty universal but it suffers from still being a TDMA (Time division Multiplex) type system. You'll hear about dropped calls from the GSM folks here in the US - you just run out of time slots in crowded areas.

CDMA is Code division multiplex - the spread spectrum seems to handle more people better. I've hardly ever had a dropped call when I had full signal CDMA. WIth ATT GSM sitting at my desk - with full bars - I've dropped when too many cars go by.

Here is a long article describing what I said
CDMA vs TDMA

That being said - most everyone is moving to some form of CDMA - the 3g standard adopted by most GSM providers HSDPA - is actually a CDMA technology. Qualcom owns the rights and it sued saying that HSDPA is actually a form of CDMA. They won that suit. Here is a little article on HSDPA.
What is HSDPA?

Good set of articles although a bit dated.

If I'm reading this correctly it sounds like VZWs LTE isn't a CDMA based system either. IIRC AT&T is moving to the same system:

After more than 20 years, it appears that an almost universally-accepted standard for mobile radio may finally be implemented, bringing to an end the standards war between carriers that deployed TDMA/GSM for second generation and carriers that deployed CDMA for second generation. Those two factions continued the standards war for the third generation (UMTS and 1X respectively); but now carriers from both of the factions are supporting the GSM/UMTS faction’s Third Generation Partnership Project (3GPP) release 8, known as Universal Terrestrial Radio Access Network Long Term Evolution (LTE).

http://blog.teracomtraining.com/4g-cellular-ofdm-and-lte-the-gsm-vs-cdma-standards-war-ends

Then there is this which seems to support the above:

In recent years, LTE has been duking it out with WiMax to be crowned the upcoming broadband wireless standard. In one corner has been telecom giants like AT&T and Verizon, both of which have announced plans to deploy 4G wireless networks using LTE.

In the other corner has been Sprint, which is eyeing a rollout of its own 4G network using WiMax. Sprint owns a majority stake in WiMax provider Clearwire, a wholesale distributor of 4G services. Clearwire recently unveiled a huge WiMax testing sandbox in Silicon Valley where developers could play with the technology.

In short it sounds like both AT&T and VZW are abandoning both CDMA and GSM for LTE. Still sounds like there will be multiple standards out there though.

http://news.cnet.com/8301-1035_3-10391591-94.html

http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution

technologist · Jan 12, 2011

Both "CDMA" and "GSM" are pretty much legacy technologies. They both have a huge installed base of infrastructure and there's no reason to switch from one to the other. Both "CDMA" and "GSM" operators will be switching to LTE in the future.

[size=-2](Except for Sprint, which is going to WiMax. But they're the only one.)[/size]

rippingviper · Jan 12, 2011

technologist said:
Both "CDMA" and "GSM" are pretty much legacy technologies. They both have a huge installed base of infrastructure and there's no reason to switch from one to the other. Both "CDMA" and "GSM" operators will be switching to LTE in the future.

[size=-2](Except for Sprint, which is going to WiMax. But they're the only one.)[/size]

Maybe in the USA but up here in Canada we're still mostly CDMA still switching over to GSM/HSPA and some like alberta have hspa+ coming in.

baggss · Jan 12, 2011

rippingviper said:
Maybe in the USA but up here in Canada we're still mostly CDMA still switching over to GSM/HSPA and some like alberta have hspa+ coming in.

So is 3G not widespread in Canada then?

vansmith · Jan 12, 2011

It is on the major carriers. Rogers covers most of the population as does Bell, Telus and Fido as far as I know. It just doesn't look like there is widespread coverage if you look at a coverage map but the population is largely concentrated in select areas.

rippingviper said:
Maybe in the USA but up here in Canada we're still mostly CDMA still switching over to GSM/HSPA and some like alberta have hspa+ coming in.

Rogers and Fido are GSM and Bell and Telus are both HSPA+.

Audio.Trench · Jan 13, 2011

I run on 3G/HSPA+ with Fido..

Why does Verizon and China Telecom still use CDMA?

the8thark

rippingviper

Aptmunich

IvanLasston

cwa107

baggss

technologist

rippingviper

baggss

vansmith

Senior Member

Audio.Trench

Shop Amazon