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gsm vs cdma _ what;s the difference ?

Y

you2

Diamond Member
I'm currently on sprint (out of contract) and had intended to buy the rezound or razr (probably rezound) later this week on verizon. I suppose I could go with the skyfire on at&t but it is not clear to me if there is a huge difference between gsm and cdma. In case it matters i live in middle of boston which has very good lte coverage; wimax and at&t (though I don't think at&t lte is here yet).

My reason for switch from sprint to verizon (plan will be $5 less; and sprint's phone selection is a bit weak and their network has been questionable).

(Not that interested in nexus due to lack of sd slot and early indication of issues)
 
There's a lot of differences between GSM and CDMA from a political, and technological perspective but there are not a lot of real-world differences from a customer's perspective.

GSM is more popular worldwide and tends to get better phones sooner (but not always) and you can buy a GSM phone and stick in a small SIM card and it becomes yours without having to call anyone or register the device online. On the flip-side, older GSM phones used to have interference problems with other electronic equipment and CDMA from an engineering perspective is the better technological solution and so CDMA carriers have better bandwidth utilization.

But in this modern world of HSPDA, LTE, Wimax and the rest, everyone is running some form of WD-CDMA and the differences from a consumer even smaller than the previously small differences. So it's not really about the technology but which carrier offers which phones at a price with good service in your area at a price that you are willing to pay. For that, I would talk to people who live near you, check the coverage maps from the carriers, and check places like Consumer Reports that rate service providers per geographical location.

I'd add that my experience with Verizon's LTE is really good. It's seriously super fast. 🙂
 
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you2 said:
I'm currently on sprint (out of contract) and had intended to buy the rezound or razr (probably rezound) later this week on verizon. I suppose I could go with the skyfire on at&t but it is not clear to me if there is a huge difference between gsm and cdma. In case it matters i live in middle of boston which has very good lte coverage; wimax and at&t (though I don't think at&t lte is here yet).

My reason for switch from sprint to verizon (plan will be $5 less; and sprint's phone selection is a bit weak and their network has been questionable).

(Not that interested in nexus due to lack of sd slot and early indication of issues)
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Only thing you will notice is:
Can do voice and data on GSM (ATT/t-mobile) at the same time. Can only talk/text OR use data on CDMA, but not at the same time. Otherwise, ATT uses 3g bands that most of the rest of the world supports, so you can buy almost any phone from overseas and use it here without waiting for ATT to release it. Sprint and VZW have their phones on lockdown and only allow their phones.

I would go with the cheapest option, which you said is verizon, which I find surprising. Also, I find Sprint's phone lineup better than Verizon's. They have the SGS2, Photon, and Evo 3D. VZW has a bunch of single core phones, they just barely got the RAZR and Rezound.
 
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LTE is completly different from GSM and CDMA.

ATT has a GSM network and a 3G network that runs on W-CDMA. W-CDMA allows you to transfer data and talk on the phone at the same time. CDMA and GSM do not allow you to do that.

CDMA and W-CDMA do not cause the buzzing, pulsating noise that you get from GSM phones that are near speakers.

As everything moves to LTE these differences will be erased and we won't have much of a choice anymore.
 
Bateluer said:
But we will have ~12 frequency bands to choose from. Fun! 😛
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Not to hijack, but will any of the LTE bands used by ATT, VZW, or Sprint be compatible with overseas phones? Will we still be able to buy unlocked phones from overseas? We will still use SIM cards right?
 
ImDonly1 said:
Not to hijack, but will any of the LTE bands used by ATT, VZW, or Sprint be compatible with overseas phones? Will we still be able to buy unlocked phones from overseas? We will still use SIM cards right?
Click to expand...

Yes, LTE on Verizon and AT&T take sim cards. It was cool to see an LTE Verizon device with a SIM in it.

No, the LTE bands for the US carriers do not appear to be compatible with overseas phones. At least not yet. But so far, not looking good.

Yes, you should be able to theoretically buy overseas LTE phones that are unlocked and swap SIMs with a US carrier and use them in the US. Except for the problem that as of right now, there are 12 different bands worldwide and the US bands and the EU bands are not the same. There may be more convergence over time though - there's talk in the EU about using analog TV bands for LTE and if they did that, they could line up with the US bands for Verizon or AT&T or both.
 
Due to the way that CDMA carriers handle the near-far problem, phones on those networks are less power-efficient than those on GSM networks. This is especially noticeable in areas where the local cell towers are saturated due to large numbers of users, and in areas where signal reception is low or non-existent.

That being said, Verizon's 4GLTE is insanely fast. As a Verizon user, I'm very happy with the performance and coverage in Los Angeles is excellent.
 
TakeNoPrisoners said:
ATT has a GSM network and a 3G network that runs on W-CDMA. W-CDMA allows you to transfer data and talk on the phone at the same time. CDMA and GSM do not allow you to do that.
Click to expand...

Simultaneous voice & data is possible on Verizon with several phones, such as the Droid Thunderbolt (both 3G and 4G mode).
 
gsaldivar said:
Due to the way that CDMA carriers handle the near-far problem, phones on those networks are less power-efficient than those on GSM networks. This is especially noticeable in areas where the local cell towers are saturated due to large numbers of users, and in areas where signal reception is low or non-existent.

That being said, Verizon's 4GLTE is insanely fast. As a Verizon user, I'm very happy with the performance and coverage in Los Angeles is excellent.
Click to expand...

That's under the IS-95 standards. CDMA2000 has much more robust power control. Although cell "breathing" exists, most places are covered well enough to not even notice.
 
From what I read news in the past GSM is the modern technology while CDMA is age old technology...right?
 
CDMA and GSM were both 2G standards that replaced analog cell systems. So no, GSM is not more modern.

To answer the op, GSM is a TDMA standard, each user gets assigned a time slot and sends or receives on that specific slot.

CDMA is a direct sequence spread spectrum DSSS technique. Each user is assigned a specific spreading code out of a set of orthogonal codes which smear the narrowband transmission across the entire bandwidth of the system, all users transmit at the same time on the same frequency and the receiver separates the signals using knowledge of the spreading codes. This is more technically demanding technique than TDMA, but provides superior use of the spectrum with a higher number of supported simultaneous users (256 or more for one base compared to 16 for GSM) with gracefully decreasing quality as load increases.

As a point of note, UMTS the 3G continuation of GSM turned to wideband CDMA (WCDMA).

Modern technology has moved to OFDMA which overlapping orthogonal frequency sub-carriers, this has similar spectral efficiency to CDMA but is far easier to extend to MIMO systems which allows for improved throughput. LTE, WiMax, the defunct UMB, and 802.11n all went OFDMA in some form.
 
What about building penetration and static ? Hum. As to why leave sprint (the fellow mentioned sprint's great phone in this thread). The photon is probably the only decent phone right now; the epic 4g has huge issue with LOS (lost of signal) that requires reboot to fix. Also I wished they had gone with the 4.3 model instead of 4.5 (rumor is they will fix the LOS issue in dec but two 1/2 months seems insane for a bug of this nature (rumor is samsung provided the fix 2 weeks ago).
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Anyways thanks for some of the details - it does seem that my sister gets a lot more static than myself (she's on at&t) but it is not really a fair compairson as she is in rural wisconsin and i'm in downtown boston.
 
I hate GSMS because it was designed by the stupid European commies to only allow 1 tower at once to listen to the call. In contrast, the AMERICANS designed CDMAS which allows multiple towers (as many as can hear) to listen in to the signal and pick up the connection if one tower loses it.
You don't hate America do you? Then buy CDMA. No really. It is superior. CDMA vs GSM is why AT&T has so many more dropped calls. I'm on fricking crappy MetroPCS and I have fewer dropped calls than my friend on AT&T on his iPhone.
 
soccerballtux said:
I hate GSMS because it was designed by the stupid European commies to only allow 1 tower at once to listen to the call. In contrast, the AMERICANS designed CDMAS which allows multiple towers (as many as can hear) to listen in to the signal and pick up the connection if one tower loses it.
You don't hate America do you? Then buy CDMA. No really. It is superior. CDMA vs GSM is why AT&T has so many more dropped calls. I'm on fricking crappy MetroPCS and I have fewer dropped calls than my friend on AT&T on his iPhone.
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AT&T drops calls on their 3G network... and their 3G network is not GSM, it's UMTS (which uses W-CDMA). AT&T's problem generally is that their towers are oversubscribed.

As far as the EU and the US - that's why I mentioned political reasons at the top. Fundamentally, CDMAOne - the CDMA-based wireless standard - was developed by Qualcomm (US company) while GSM was developed in the EU. As near as I can tell, the main reason that GSM used FDMA instead of CDMA for it's channel access method was to avoid paying royalties to Qualcomm.

There's a table of advantages and disadvantages to GSM vs. CDMA as technologies here:
http://en.wikipedia.org/wiki/Compar...engths_and_Weaknesses_of_IS-95_and_GSM.5B4.5D

Still AT&T's 2G GSM network tends to be more reliable than their 3G network for me - not as many people us it nowadays around where I live.
 
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pm said:
AT&T drops calls on their 3G network... and their 3G network is not GSM, it's UMTS (which uses W-CDMA). AT&T's problem generally is that their towers are oversubscribed.
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shh you're not helping my anti-euro agenda!!!!

regarding the towers, how do we know this; is there any publicly available information that we can compare population density to tower density with and determine "yes, AT&T populates their towers 50% higher on average than Verizon"? Otherwise it feels like handwaving.
 
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soccerballtux said:
shh you're not helping my anti-euro agenda!!!!

regarding the towers, how do we know this; is there any publicly available information that we can compare population density to tower density with and determine "yes, AT&T populates their towers 50% higher on average than Verizon"? Otherwise it feels like handwaving.
Click to expand...

In my particular case, several AT&T CSR's have told me. Whenever I call with any kind of phone problem at all, they keep offering me a free microcell. I've received two offer letters by mail, and I've had two reps tell me "we are having capacity problem on the two towers closest your house, we would like to offer you a microcell free of charge to alleviate the problem" or words to that effect.

In other areas, it's hard to say. A year or so ago the CEO of AT&T admitted at one of their quarterly earnings conference calls that they had a capacity problem on their 3G network in certain areas of the country and he discussed their plans to resolve it. I can find the link if you are curious... I know in more recent conference calls the AT&T executives say that the issue has been resolved and the dropped call rate on AT&T is "better than our competition".
 
i think its a great thing that we all will be using the same lte phones, on any carrier. sure, you might have to root a verizon phone to work on sprint, but whatever. at least it will. best part is carriers can continue to revenue share through roaming agreements. that way all the cell towers can be used by anyone, and roaming fees stay low or free. this has not been as easy to do when you have two different types of networks out there.
 
Ah yes, well, except that not all LTE is the same. LTE can use anywhere from one 1.4Mhz channel to up to 2 20Mhz channels, and these can be centered at widely varying frequency points depending on available spectrum.

The up link UL and down link DL can either be on separate frequency channels in FDD mode or time interleaved on the same channel in TDD mode. My understanding is that Sprint and ATT are likely to use TDD for wide coverage to make up for a lack of spectrum, while Verizon has gone FDD.

So, there may exist world phones with flexible analog front ends and high quality full support modems, there will like be just as many with carrier specific RF and cheaper modems that drop support for modes the carrier doesn't support.

Further the current state of voice over LTE is abysmal.
 
pm said:
In my particular case, several AT&T CSR's have told me. Whenever I call with any kind of phone problem at all, they keep offering me a free microcell. I've received two offer letters by mail, and I've had two reps tell me "we are having capacity problem on the two towers closest your house, we would like to offer you a microcell free of charge to alleviate the problem" or words to that effect.
Click to expand...
hm that's very interesting...

In other areas, it's hard to say. A year or so ago the CEO of AT&T admitted at one of their quarterly earnings conference calls that they had a capacity problem on their 3G network in certain areas of the country and he discussed their plans to resolve it. I can find the link if you are curious... I know in more recent conference calls the AT&T executives say that the issue has been resolved and the dropped call rate on AT&T is "better than our competition".
Click to expand...

also interesting...
 
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ImDonly1 said:
Not to hijack, but will any of the LTE bands used by ATT, VZW, or Sprint be compatible with overseas phones? Will we still be able to buy unlocked phones from overseas? We will still use SIM cards right?
Click to expand...

sprint's LTE band and version appears to be compatible with the one china will be using.

att, vzw, and most european carriers are using different version of LTE on a different band. att's and vzw's bands barely overlap so the phones may not be very compatible.

i wonder if that will make sprint an attractive buyout target for china mobile?



soccerballtux said:
shh you're not helping my anti-euro agenda!!!!
Click to expand...

w-cdma is the current underlying radio technology behind what is commonly referred to as GSM. GSM itself is time division and isn't in use much anymore. if you're using a 'GSM' phone on '3G' you're using cdma. which just means code division, multiple access. the acronym in that usage isn't a qualcomm trademark. and it's still developed by a bunch of euro commies.
 
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ElFenix said:
sprint's LTE band and version appears to be compatible with the one china will be using.

att, vzw, and most european carriers are using different version of LTE on a different band. att's and vzw's bands barely overlap so the phones may not be very compatible.

i wonder if that will make sprint an attractive buyout target for china mobile?





w-cdma is the current underlying radio technology behind what is commonly referred to as GSM. GSM itself is time division and isn't in use much anymore. if you're using a 'GSM' phone on '3G' you're using cdma. which just means code division, multiple access. the acronym in that usage isn't a qualcomm trademark. and it's still developed by a bunch of euro commies.
Click to expand...

hm. I guess that leaves us with the oversubscribed towers as the culprit...
 
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