T-Mobile Exec: Sprint Merger 'Logical Ultimate Combination' → Re: GSM

GSM is to CDMA what VHS was to Betamax.

Betamax was the superior technology at the time. VHS just won the war for other reasons.

CDMA is hardly useless. At a fundamental level, CDMA is the superior technology. However, GSM rules the world, thus GSM is and will continue to be the standard going forward.

On CDMA you cannot use voice and data at the same time ... how is that for superior? GSM also allows you to buy an unlocked phone and use it with whatever GSM service you would like throughout the WORLD. Try buying a new phone somewhere else and bringing it to Verizon.

except for range how is it better? being limited to 3mbps is a HUGE setback in my opinion

That's not actually true, it's just true of the implementations we see here. SVDO exists (even on phones such as the Sprint HTC Evo 4G LTE).

Good point, but in reality it does not change anything.

When most people say CDMA they talk about CDMA2000. Sprint and Verizon both use CDMA2000. EVDO which both Verizon and Sprint use, is just a later evolution of the CDMA2000-based 3G 1xRTT technology that came before it.

T-Mobile and AT&T both use a technology called UMTS which stands for Universal Mobile Telecommunications System which if you look at the underlining signal encoding scheme you would find (surprise!) CDMA, just a different version of CDMA that CDMA2000 uses.

UMTS is completely different from what was once known as GSM. UMTS may have its roots in GSM but most if not all of what was once known as GSM was dropped from the UMTS standard to be replaced with CDMA as the base signal encoding scheme. UMTS was simply a natural next step in terms of network evolution when it came to legacy GSM-based networks due to the fact that both UMTS and GSM networks could easily co-exist with the same back-end provisioning and network management hardware.

Things get dicey when you start mixing CDMA2000 with LTE because the two network types use completely different network management and provisioning techniques. Verizon and Sprint had to implement something called eHRPD or Evolved High-Rate Packet Data.

Think of eHRPD has a "bridge" that "bridges" the two network types together so that those providers that are still running older incompatible CDMA2000-based networks alongside LTE can continue using their older network infrastructure. The problem is that eHRPD is a very fugly hack that has proven to be a very fragile system.

The reason why this is so is because an LTE-based network expects a GSM-like or UMTS-based back-end provisioning network. eHRPD implements enough pieces and parts of a UMTS-like provisioning system, enough to be able to fake a UMTS network to the LTE network for LTE to coexist with it.

Sounds like a poor solution to the problem. More like a Band-Aid if anything. They should have just gone UMTS instead of EVDO.

Honestly, I'm not sure why anyone would want to deal with CDMA in America. With all the limitations CDMA carriers have, it's simply not worth it to me.

The problem is that at the time the modern cell networks were being built in the USA, two competing digital network technologies were vying for control of the digital cell phone network market; GMS and CDMA2000.

Technically speaking, CDMA2000 was in fact the better network technology at the time when it was competing with GSM.

Now, we have to go back in time a bit for this story so let's take a trip down memory lane.

Back when the modern cell networks in the USA were being build, what was once known as GTE (which later became what we know as Verizon Wireless today) was building the networks. CDMA2000 proved to be a better standard to use at the time because it required less capital expenditures to deploy a network to sufficiently cover an area due to the fact that CDMA2000 networks didn't require as dense a network build-out as GSM required. So from a capex standard, CDMA2000 was a win for the then GTE.

GSM requires a much more densely deployed network than CDMA2000 thus required more capex to handle the same amount of traffic that a CDMA2000 network could handle.

So now you have the reason why carriers such as Sprint and Verizon Wireless have CDMA2000-based networks.

Fast-forward to today and now UMTS which has its roots in GSM which was the standard from which LTE borrows much from now rules the cell phone network market.

I still can't take that Sprint phone and use it on Orange or on AT&T like I could an Orange phone or TMO phone. The point is GSM allows the ability to do more. CDMA does not.

GSM does not allow one to use voice and data at the same time. UMTS does allow for that, and the GSM carriers are using UMTS as their upgrade path. However, the two networks/technologies are completely separate.

GSM does allow it, but it's optional and both the device and the network have to support it.

Dual Transfer Mode.

I do it all the time on my AT&T MVNO GSM line. Verizon and Sprint on the other side cannot.

You aren't doing it on GSM. You're doing it on UMTS. While the GSM standards allow for Dual Transfer Mode, which does allow for simultaneous voice and data, I don't know of any US carriers who have enabled the feature.