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> 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

> 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 ago
Voice 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 ago
Couple 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.

wmf 10y ago

Voice 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 ago

Couple 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.