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It's a way more complicated story, and it's important to disambiguate between "CDMA" the standard and "CDMA" the channel access method. The core issue was that
by gok 10y ago
It's a way more complicated story, and it's important to disambiguate between "CDMA" the standard and "CDMA" the channel access method.
The core issue was that in the 2G era, "CDMA" (the Qualcomm name for IS-95/IS-2000) was built on CDMA (code division multiple access), while GSM was built on TSMA (time division multiple access). CDMA (the channel access method) is more spectrum efficient than TDMA, and has some other nice properties. When the time came for carriers in many countries to deploy their 2G networks, it seemed like a win to use CDMA (the standard) because they could support more subscribers with the same amount of spectrum. Companies other than Qualcomm did make CDMA chips in this era.
In the 3G era, the GSM standard also moved onto CDMA ("UMTS"). But this was a pretty serious migration effort, so carriers that had already deployed IS-95/CDMA typically moved along to the 3G variant of CDMA (IS-2000), which required buying less new equipment.
As the 4G networks starting showing up, Qualcomm saw the writing on the wall so they (a) got on the GSM/LTE bandwagon and (b) started investing heavily in their SoCs, which could be bundled with their basebands for smartphones. Since they happened to also be the only remaining baseband manufacturer that was making CDMA support, they also had a tremendous selling point: use our chips in your smartphones and you can still support 2G/3G CDMA networks, which at this point were widely deployed. Plus Qualcomm has so many patents on LTE that you're probably going to end up paying them quite a bit of money even if you don't buy their chips. So today even companies like Samsung which make their own SoCs make variants of their phones with Qualcomm chips to support CDMA carriers.
Qualcomm fans/employees will often mention that this really all goes back to the 80s/90s, when Europe forced everyone to use GSM (which just so happened to be hugely reliant on Europe-owned patents). CDMA never really got a fair shake at world domination. Perhaps if the FCC had just picked one cell phone standard (perhaps CDMA) like they did for TV and radio things would have worked out differently. China briefly tried coming up with their own cell standard (TD-SCDMA) for similarly protectionist reasons and it didn't really work out.
As it is...well, the world finally ended up settling on LTE.
- kogepathic 10y ago> The core issue was that in the 2G era, "CDMA" (the Qualcomm name for IS-95/IS-2000) was built on CDMA (code division multiple access), while GSM was built on TSMA (time division multiple access). CDMA (the channel access method) is more spectrum efficient than TDMA, and has some other nice properties. When the time came for carriers in many countries to deploy their 2G networks, it seemed like a win to use CDMA (the standard) because they could support more subscribers with the same amount of spectrum. Okay, so I have a stupid follow up question. The company I work for does a lot of work in developing countries (sub-saharan Africa) and outside of major cities 2G is the only thing you're gonna find. But to my knowledge, there is no CDMA to be found anywhere in these countries, despite what you've said about spectrum efficiency. So, why is it that CDMA (meaning IS-95/IS-2000) was only ever successful in North America? Or am I being dense? Could it be that carriers in sub-saharan Africa are actually installing 3G/LTE base stations but limiting the connectivity to handsets to 2G because of tower-tower throughput? > use our chips in your smartphones and you can still support 2G/3G CDMA networks, which at this point were widely deployed. So I've heard that a number of US providers (AT&T at least) have already shut off their 2G networks. Does this mean that Apple no longer requires CDMA modems in iPhones because the number of CDMA networks is declining? You mention that Sprint and Verizon have significant CDMA networks. What is their migration strategy for 4G? To my knowledge the only 4G standard in use is from GSM.
- wmf 10y agoVoice is another wrinkle here. On Sprint/Verizon, LTE is used for data but voice calls are over the old 3G CDMA network. They're migrating to VoLTE but it's taking time. Also, there are still some places that have CDMA coverage but not LTE. LTE-only phones are coming but it will be a while before phones can drop CDMA support.
- gok 10y agoCouple things. GSM phones are cheaper because they have many manufacturers and require less powerful processing. But moreover, the developing world has a lot more spectrum availability. Rich countries have 100 years of legacy, spectrum-inefficient radio technology they need to support. Indeed, the latest iPhone 7 actually comes in two models, one with CDMA support and one without. Sprint and Verizon (and other CDMA carriers) ultimately are going to shut their CDMA networks down and be LTE only. Same is true of GSM carriers; they'll be shutting down their 3G/UMTS/WCDMA support as LTE devices become available everywhere.
- anthonybsd 10y ago>You mention that Sprint and Verizon have significant CDMA networks. What is their migration strategy for 4G? To my knowledge the only 4G standard in use is from GSM. I think you are confusing the terms. GSM is a family of standards some of which are based on CDMA, like aforementioned UMTS which is the most widely deployed network standard in the world right now. Because UMTS was not based on TDMA it was a very costly upgrade for most operators since it required entirely new equipment. LTE on the other hand is yet another completely different beast (OFDMA) not compatible with any existing infrastructure so everyone has exactly the same migration strategy to LTE regardless if they are CDMA or TDMA based.