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Question of the Day: What's the most interesting small town you've visited in South Africa?
GSM Vs CDMA
- Thread starter Pynet
- Start date
DJNgoma
Expert Member
Just a quick copy, paste and edit.
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CDMA
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Advantages of CDMA include:
-Increased cellular communications security.
-Simultaneous conversations.
-Increased efficiency, meaning that the carrier can serve more subscribers.
-Smaller phones.
-Low power requirements and little cell-to-cell coordination needed by operators.
-Extended reach - beneficial to rural users situated far from cells.
Disadvantages of CDMA include:
-Due to its proprietary nature, all of CDMA's flaws are not known to the engineering community.
-CDMA is relatively new, and the network is not as mature as GSM.
-CDMA cannot offer international roaming, a large GSM advantage.
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GSM
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Advantages of GSM:
-GSM is already used worldwide with over 450 million subscribers.
-International roaming permits subscribers to use one phone throughout -Western Europe. CDMA will work in Asia, but not France, Germany, the U.K. and other popular European destinations.
-GSM is mature, having started in the mid-80s. This maturity means a more stable network with robust features. CDMA is still building its network.
-GSM's maturity means engineers cut their teeth on the technology, creating an unconscious preference.
-The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM m-commerce advantages.
Disadvantages of GSM:
-Lack of access to burgeoning American market.
Source: http://bit.ly/53hO5l
--------------------------
CDMA
--------------------------
Advantages of CDMA include:
-Increased cellular communications security.
-Simultaneous conversations.
-Increased efficiency, meaning that the carrier can serve more subscribers.
-Smaller phones.
-Low power requirements and little cell-to-cell coordination needed by operators.
-Extended reach - beneficial to rural users situated far from cells.
Disadvantages of CDMA include:
-Due to its proprietary nature, all of CDMA's flaws are not known to the engineering community.
-CDMA is relatively new, and the network is not as mature as GSM.
-CDMA cannot offer international roaming, a large GSM advantage.
--------------------------
GSM
--------------------------
Advantages of GSM:
-GSM is already used worldwide with over 450 million subscribers.
-International roaming permits subscribers to use one phone throughout -Western Europe. CDMA will work in Asia, but not France, Germany, the U.K. and other popular European destinations.
-GSM is mature, having started in the mid-80s. This maturity means a more stable network with robust features. CDMA is still building its network.
-GSM's maturity means engineers cut their teeth on the technology, creating an unconscious preference.
-The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM m-commerce advantages.
Disadvantages of GSM:
-Lack of access to burgeoning American market.
Source: http://bit.ly/53hO5l
Other Pineapple Smurf
Honorary Master
CDMA = Neotel
Silver-0-surfer
Well-Known Member
kronoSX
Honorary Master
don't mean to sound stupid, but wtf the Smaller phones mean?
It means that the circuitry for gsm phones is larger
DJNgoma
Expert Member
.Also, in some implementations (not all of them), CDMA phones are locked; i.e. no sim card. When you get a phone on contract or whatever, the service provider activates your new phone and at the same time de-activates your old phone. Weird
Ockie
Resident Lead Bender
If CDMA has a further reach cell wise, why so many people complaining about neotel coverage? Or are they complaining about speed and the two not related? With a CDMA phone, what happens when you loose it or gets stolen? You have to get a new number also as there is no sim card?
SteveO
Expert Member
as far as i know CDMA and WCDMA are closely related, WCDMA has poor coverage compared to GSM as GSM frequencies are able to propogate further without being affected by noise etc too badly.
Also due to CDMA networks having to control its power output, it is affected by "cell breathing" where the cell will grow/shrink depending on how much load it is under.
Also due to CDMA networks having to control its power output, it is affected by "cell breathing" where the cell will grow/shrink depending on how much load it is under.
Last edited:
ads
Senior Member
CDMA is a generic term for Code Division Multiple Access technologies (so you may often see confusion between different standards that use CDMA principles), but it's normally used to refer to a family of standards, starting with IS-95 (the original dominant 2G standard in North America), and leading to CDMA2000 (one of the two global 3G standards), with its base standard CDMA2000 1X, and enhancements 1xEV-DO, Rev A, and Rev B. Mostly, when people mention CDMA today, it's the 3G version, and the vast majority of CDMA subscribers today globally are 3G (CDMA2000). You can unravel the whole alphabet soup at http://www.cdg.org.
Since GSM is a 2G standard, it wouldn't be correct to compare it directly with 3G CDMA2000, since GSM does not support the high speeds and features of a 3G standard. Instead, you should be comparing CDMA2000 to UMTS (Universal Mobile Telecommunications Service), the most common European 3G standard. UMTS was developed by the same European standards body as GSM (ETSI), and is regarded as the 3G successor to GSM. The enhancements of UMTS are HSDPA (similar in most respects to EV-DO), HSUPA (similar to Rev A), and HSPA+ (similar to Rev B). (What sometimes causes confusion is that you will see UMTS also called W-CDMA, since the basic radio technology that it uses is also a form of CDMA.) Probably the best info source for GSM and its successors is http://www.gsmworld.com.
Globally, there are around 500 million CDMA2000 users, and slightly fewer UMTS subscribers, making up a bit under 1 billion 3G subscribers overall. By comparison, GSM (the 2G standard), has exceeded 3 billion subscribers (at least, SIM cards). There are very few IS-95 subscribers left in the world, since most have migrated to CDMA2000, since the standard allowed for very smooth migration (unlike GSM to 3G UMTS, which required changing frequencies, and entirely new radio networks for most operators).
In the CDMA2000 standard, low-speed/voice services are carried on a separate carrier (1X) to high-speed (EV-DO / Rev A / Rev B), so you'll often see different coverage maps for these.
Similarly, most (but not all) UMTS are also GSM operators, and hence offer a mix of GSM and 3G services, and you'll see different coverage maps for these.
CDMA supports GSM-like SIM cards (technically, they are called RUIM cards in the standard), just like UMTS (where they're actually called U-SIM cards). However, they are not mandatory, like in GSM/UMTS, so quite a few operators don't use SIMs. However, the trend is towards CDMA operators using SIMs/RUIMs as well. Unlike GSM/UMTS, CDMA2000 is also very commonly used in limited-mobility / fixed wireless networks, as well as in mobile networks.
Things get interesting again as we look towards the migration to 4G (not really a defined term, but people are using it), where both CDMA2000 and UMTS converge to a new standard, LTE. However, the actual migration is likely to be relatively slow, as we've seen with GSM/3G UMTS around the world.
In South Africa, we have the following 3G networks:
Vodacom 2.1 GHz UMTS HSUPA
MTN 2.1 GHz UMTS HSUPA
Telkom 2.1 GHz UMTS HSUPA
Neotel 800 MHz CDMA2000 1xEV-DO Rev A
Since GSM is a 2G standard, it wouldn't be correct to compare it directly with 3G CDMA2000, since GSM does not support the high speeds and features of a 3G standard. Instead, you should be comparing CDMA2000 to UMTS (Universal Mobile Telecommunications Service), the most common European 3G standard. UMTS was developed by the same European standards body as GSM (ETSI), and is regarded as the 3G successor to GSM. The enhancements of UMTS are HSDPA (similar in most respects to EV-DO), HSUPA (similar to Rev A), and HSPA+ (similar to Rev B). (What sometimes causes confusion is that you will see UMTS also called W-CDMA, since the basic radio technology that it uses is also a form of CDMA.) Probably the best info source for GSM and its successors is http://www.gsmworld.com.
Globally, there are around 500 million CDMA2000 users, and slightly fewer UMTS subscribers, making up a bit under 1 billion 3G subscribers overall. By comparison, GSM (the 2G standard), has exceeded 3 billion subscribers (at least, SIM cards). There are very few IS-95 subscribers left in the world, since most have migrated to CDMA2000, since the standard allowed for very smooth migration (unlike GSM to 3G UMTS, which required changing frequencies, and entirely new radio networks for most operators).
In the CDMA2000 standard, low-speed/voice services are carried on a separate carrier (1X) to high-speed (EV-DO / Rev A / Rev B), so you'll often see different coverage maps for these.
Similarly, most (but not all) UMTS are also GSM operators, and hence offer a mix of GSM and 3G services, and you'll see different coverage maps for these.
CDMA supports GSM-like SIM cards (technically, they are called RUIM cards in the standard), just like UMTS (where they're actually called U-SIM cards). However, they are not mandatory, like in GSM/UMTS, so quite a few operators don't use SIMs. However, the trend is towards CDMA operators using SIMs/RUIMs as well. Unlike GSM/UMTS, CDMA2000 is also very commonly used in limited-mobility / fixed wireless networks, as well as in mobile networks.
Things get interesting again as we look towards the migration to 4G (not really a defined term, but people are using it), where both CDMA2000 and UMTS converge to a new standard, LTE. However, the actual migration is likely to be relatively slow, as we've seen with GSM/3G UMTS around the world.
In South Africa, we have the following 3G networks:
Vodacom 2.1 GHz UMTS HSUPA
MTN 2.1 GHz UMTS HSUPA
Telkom 2.1 GHz UMTS HSUPA
Neotel 800 MHz CDMA2000 1xEV-DO Rev A
ads
Senior Member
Propagation is inversely related to frequency. Hence, in South Africa, CDMA at 800 MHz has the largest reach (per cell), followed by GSM at 900 MHz. WCDMA/UMTS at 2.1 GHz has a far smaller reach, requiring many more sites to achieve the same coverage.
However, there is more to coverage and capacity than propagation. To compare actual performance, you have to compare the number of sites deployed, the number of carriers on a site, and, of course, the number of susbcribers sharing the site. What the propagation does tell you is that an operator using 800 MHz, for example, needs many fewer sites than an operator using 2.1 GHz, if they have similar technologies, and started at the same time.
Cell breathing, which happens on all CDMA-based networks (i.e. all 3G networks) is a consequence of how the technology works. It's not directly a result of adjusting power output, but is a consequence of the increase in co-channel interference as the number of transmitting subscriber units increases, since all users share the same spread spectrum channel - the Code Division in CDMA refers to the way in which multiple users share a channel based on orthogonal codes, in contrast to TDMA (e.g. GSM), and FDMA. In practice, operators design networks for load conditions, and ensure that there is sufficient cell overlap, or add cells to fill any gaps that may appear. Honest 3G operators publish these real coverage boundaries. Dishonest 3G operators (the most obvious example being Telkom, judging by their maps) publish the unshrunk cell boundaries, so coverage will disappear as the network becomes loaded.