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How does CDMA work
- Thread starter SilentLoner
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A lot has changed since you last tried in 2007. Verizon's personal user web functions are a lot better, for one thing, although personally I think it's slowed down a bit due to extra fancy layouts.
In any case, you can also just dial *228 on the desired Verizon phone, enter the desired phone number of yours and your PIN, and within a minute or so, that new phone is provisioned for you.
I do it all the time, especially when doing development.
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It also saved me more than a few times when my wife temporarily lost her phone and didn't realize it until early the next morning. One time she was scheduled to leave on a trip at 5am and needed her phone number with her.
No problem: I just grabbed a spare Verizon phone, did the dialing mentioned above, and she was on her way. That ability was priceless.
You couldn't be more wrong.
http://thecellphonejunkie.com/2011/...-data-over-cdma1x-advanced-svdo-network-soon/
LTE is technically a GSM technology which is why they're switching to SIM cards.
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That post is more than a year old. As far as I know, Verizon has yet to roll out SVDO, and I doubt they will now that they're pushing LTE. I don't think any carriers in the world have SVDO, so the statements regardling lack of simultanous voice and data are accurate
Most new Verizon smartphones (World or non-world, 4G LTE or non-4G) now come with removable CDMA SIM cards. The basic feature phone SIM cards however are buried within the phone.
All LTE smartphones have a SIM card.
CDMA (generally) provided better data than GSM. GSM had more benefits than using CDMA but there are some drawbacks to GSM just like their are to CDMA. I prefer CDMA networks because of the better data reliability and I don't really need to do Voice + Data at the same time...kinda stupid.
Even technically speaking, LTE isn't even real 4G. LTE Advanced is full on compliant 4G.
But hey, at least they aren't T-Mobile and false advertise.
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SIM cards have always been in CDMA phones, just not accessible.
Sure it can. Let's differentiate between CDMA2000 networks in general, and what Verizon has done.
One way that CDMA2000 networks can do voice and data over 3G is if they implement Voice over Rev A (VoRA). Verizon did not implement that, because they prefer to keep voice and data separate in order to avoid dropped calls similar to what AT&T can get when a call moves from GPRS-2G to UMTS-3G.
Another way that CDMA2000 networks can do voice and data simultaneously is if they allow Simultaneous Voice and EVDO (SVDO). Verizon DOES allow that because it still keeps voice and data separate by using two radios, and thus avoids the above voice drop potential caused by sharing a single 3G connection.
Verizon has sold several SVDO capable phones. The Thunderbolt and Rezound come to mind right away.
Anandtech had a Thunderbolt review talking about the dual chips that allow it.
LTE is a new addon to either GSM or CDMA2000 or whatever systems. It is not technically related to any previous GSM system.
(UMTS-3G was also an add-on system. In Korea, for example, they added UMTS-3G to a CDMA2000/EVDO capable network. UMTS could use more of a GSM carrier's background infrastructure, though, than LTE can.)
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SVDO is a phone function not a network function. If the carrier's implemented REV. B it would have faster data speeds and voice and data. Sadly U.S CDMA carrier never implemented. At least LTE is getting rolled out aggressively.
Not true.
CDMA does allow for a SIM-like card (RUIM), but those are only used on Asian carriers so far.
Yeah I do like that aspect of it, I know there will be a time where I will have forgot my phone and I will say to my friend can I use his verizon phone (as I have international minutes) register my phone on his and then away I go and he can reregister asap.
When you're on 3G, the phone will use the WCDMA radio for everything, so you don't get the "GSM buzzing". If you turn 3G off or go out of coverage then it'll drop back to the GSM radio and you'll get the buzzing.
I have experienced a similar buzzing sound but with an old 3G dongle. When it used to fall back onto 2G it always used to make a really high pitched noise, which gave me a bad headache lol
With Verizon's 4G LTE, you can talk and have data at the same time. I do it all the time with my GNEX..
I am intrigued by the gnex but I cant shake the annoyance of g+ (and I have an account but it sucks!)
Maybe I am misunderstanding you, but you aren't forced to use G+ if you don't want to.
Yes true, there's a card inside the phone (newer ones anyways) and the new smartphones wether it be World, 4G, or just plain 3G, they now have removable CDMA SIMs
LTE is based off of the GSM/UMTS system. It's the correct natural upgrade for GSM carriers. The original successor for CDMA carriers was Ultra Mobile Broadband (EV-DO Rev. C) until Quallcom went for LTE instead and all the other sponsors followed suit.
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Google+ is optional. You aren't required to use Google+ to use the phone. It's simply an integrated social network within the OS.
So its not like twitter and facebook on the ms phone? I hate having icons I dont use on my phone lol
Only lte and world phone devices have SIMs inside. The CDMA-only ones don't. I've taken apart countless CDMA devices from various providers. None had sim cards; most didn't have the solder points for one (one Nokia did iirc). I don't know what you're basing your assertion on, but it's plain wrong.
My old Nokia had a slot for one, along with the message "do not put anything in this slot!"
So much misinformation it's not even funny.
CDMA phones do NOT have build-in SIM cards. No, no, no, no, no!
SIM is optional in CDMA (CSIM, originally called R-UIM). American CDMA carriers do not generally use it. Verizon uses it in their LTE phones. Verizon and Sprint GLOBAL phones do NOT use CDMA SIM. To prove this, try swapping your iPhone SIM (but don't keep it swapped, that SIM *is* billable to your account when roaming internationally!). The SIM card in a Verizon iPhone is a Vodafone Netherlands SIM card not in any way tied to your CDMA account. I don't remember what SIM is in a Sprint iPhone (Nextel maybe?) but it's not a Sprint CSIM card.
Some countries, like China, mandate removable security so SIM cards have long been used in CDMA there. This is why some (mostly Nokia) CDMA phones have non-functional SIM card slots. The same phone is sold in other countries with firmware that uses CSIM.
Finally the GSM "buzzing" is a purely physical process occurring. GSM uses a TDMA air interface. This means that there is a relatively narrow timeslot shared by many users. Your phone is allowed to broadcast 217 times a second, and this is a very unfortunate rate. It means the radio transmitter is cycling 217 times a second and when it does so the tiny amount of electricity from nearby speaker wires acting as an antenna causes a faint 217Hz audible buzz on the line. 850MHz is worse than 1900MHz for this since most equipment is better shielded at 1900MHz. 217Hz is a very audible, and annoying, frequency. UMTS is not time divided, CDMA voice isn't. CDMA data (EVDO), oddly *is* but over a wider channel (it's both time and code divided) at a less audible and distinct pulse rate. TDMA (IS-136) and Nextel have much less audibly annoying cycle rates. It's one MAJOR flaw that was overlooked in the design of GSM. Slight modifications to the air interface could have dramatically reduced the "GSM buzz"
CDMA phones do NOT have build-in SIM cards. No, no, no, no, no!
SIM is optional in CDMA (CSIM, originally called R-UIM). American CDMA carriers do not generally use it. Verizon uses it in their LTE phones. Verizon and Sprint GLOBAL phones do NOT use CDMA SIM. To prove this, try swapping your iPhone SIM (but don't keep it swapped, that SIM *is* billable to your account when roaming internationally!). The SIM card in a Verizon iPhone is a Vodafone Netherlands SIM card not in any way tied to your CDMA account. I don't remember what SIM is in a Sprint iPhone (Nextel maybe?) but it's not a Sprint CSIM card.
Some countries, like China, mandate removable security so SIM cards have long been used in CDMA there. This is why some (mostly Nokia) CDMA phones have non-functional SIM card slots. The same phone is sold in other countries with firmware that uses CSIM.
Finally the GSM "buzzing" is a purely physical process occurring. GSM uses a TDMA air interface. This means that there is a relatively narrow timeslot shared by many users. Your phone is allowed to broadcast 217 times a second, and this is a very unfortunate rate. It means the radio transmitter is cycling 217 times a second and when it does so the tiny amount of electricity from nearby speaker wires acting as an antenna causes a faint 217Hz audible buzz on the line. 850MHz is worse than 1900MHz for this since most equipment is better shielded at 1900MHz. 217Hz is a very audible, and annoying, frequency. UMTS is not time divided, CDMA voice isn't. CDMA data (EVDO), oddly *is* but over a wider channel (it's both time and code divided) at a less audible and distinct pulse rate. TDMA (IS-136) and Nextel have much less audibly annoying cycle rates. It's one MAJOR flaw that was overlooked in the design of GSM. Slight modifications to the air interface could have dramatically reduced the "GSM buzz"
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Thanks for the clarification. I didn't want to spit something out like that and be wrong.
No such thing except according to the fanboys on either side. Each has its pros and cons.
It really depends on the frequency used. 850 (used for EDGE in a lot of at&t markets) does tend to cause this much more than other bands. We used to have both 850 and 1900 EDGE devices. The 850 devices caused horrible interference at distance. The 1900 devices did not.
Be careful with simple, broad statements like that. GSM itself doesn't handle data and older GSM-related data tech such as GPRS and EDGE do not allow for simultaneous voice and data.
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In the beginning, there was FM mobile telephony for vehicle users started by AT&T in 1946 using analog communication techniques. By the 70s, Bell labs provided a better solution, AMPS but it was still not fully digital.
Then IS-54 and IS-95 (CDMA) evolved in the US which were able to co-exist with the existing analog network, giving them an easy one standard with a next gen network. CDMA's biggest advantage was frequency re-use in cells without worrying about interference. The coverage areas are typically divided into cells, and they use specific frequencies to carry the signal, but you only have finite frequencies so you need to re-use. CDMA had the advantage over other multiplexing forms due to spread spectrum technique. I would explain it but it will make this into a 5 page reply lol.
And no CDMA doesn't use SIM. SIM was introduced by GSM.
GSM was developed in Europe for one reason, each region had their own standard. GSM gave EUrope one single standard and was pushed to be adopted by the entire region. It uses a slightly slower bitrate for sound compared to the original CDMA. Then GPRS and EVDO came as the evolution to provide data acess to GSM.
In the 90s Europe developed 3G UMTS/HSPA as an evolution from GSM (note: UMTS is not GSM extended, it needs new handsets and new tower upgrades). While elsewhere CDMA was evolved as CDMA 2000 and later EVDO.
In the 2000s and later, the push for 4G started and LTE has arrived to be a common standard worldwide, pushing WiMax aside. LTE needs new handsets and tower upgrades, meaning it is not a direct upgrade to CDMA or GSM. In fact the underlying communication techniques are different but again, consult a communications book.
GSM refers to only voice. The reason you have data and voice simultaneously on a GSM enabled handset is because of EDGE or 3G UMTS which are not GSM, but evolution of that standard. Same with CDMA, however EVDO does not work the way UMTS does.
As for what is better, they all have their strengths which can be better understood under more research. Traditionally CDMA has been shown to provide better interference avoidance but it has fading issues. GSM suffers with interference but wider frequency re-use can help. However that also means a congested network will get slower as more users are tacked onto a carrier frequency and multiplexed in the same amount of time. The data slot allotted grows smaller which leads to slower speeds.
Then IS-54 and IS-95 (CDMA) evolved in the US which were able to co-exist with the existing analog network, giving them an easy one standard with a next gen network. CDMA's biggest advantage was frequency re-use in cells without worrying about interference. The coverage areas are typically divided into cells, and they use specific frequencies to carry the signal, but you only have finite frequencies so you need to re-use. CDMA had the advantage over other multiplexing forms due to spread spectrum technique. I would explain it but it will make this into a 5 page reply lol.
And no CDMA doesn't use SIM. SIM was introduced by GSM.
GSM was developed in Europe for one reason, each region had their own standard. GSM gave EUrope one single standard and was pushed to be adopted by the entire region. It uses a slightly slower bitrate for sound compared to the original CDMA. Then GPRS and EVDO came as the evolution to provide data acess to GSM.
In the 90s Europe developed 3G UMTS/HSPA as an evolution from GSM (note: UMTS is not GSM extended, it needs new handsets and new tower upgrades). While elsewhere CDMA was evolved as CDMA 2000 and later EVDO.
In the 2000s and later, the push for 4G started and LTE has arrived to be a common standard worldwide, pushing WiMax aside. LTE needs new handsets and tower upgrades, meaning it is not a direct upgrade to CDMA or GSM. In fact the underlying communication techniques are different but again, consult a communications book.
GSM refers to only voice. The reason you have data and voice simultaneously on a GSM enabled handset is because of EDGE or 3G UMTS which are not GSM, but evolution of that standard. Same with CDMA, however EVDO does not work the way UMTS does.
As for what is better, they all have their strengths which can be better understood under more research. Traditionally CDMA has been shown to provide better interference avoidance but it has fading issues. GSM suffers with interference but wider frequency re-use can help. However that also means a congested network will get slower as more users are tacked onto a carrier frequency and multiplexed in the same amount of time. The data slot allotted grows smaller which leads to slower speeds.