CDMA vs. GSM: What's the difference between these cellular standards?
By Brendan Hesse - Posted on January 30, 2018 9:04 am 
 
If you're in the market for a new smartphone or carrier - or you're simply
interested in cell phone networks - you've likely encountered the acronyms
CDMA and GSM before. But what are they, and how do they affect your phone?

The two cellular standards function in different regions and allow for
global communication between individuals, and each converts incoming and
outgoing data into radio waves differently. Neither should be a huge factor
when buying a cell phone (unlike 4G and LTE), but it's definitely worth
knowing your stuff, since not all cell phones are guaranteed to work on both
standard. It depends on where you are, what you're looking for, and who
you're with.

GSM explained

The iPhone 7 is a smartphone that typically functions on a GSM network.
GSM stands for Global System for Mobile Communication, and unless you live
in the United States or Russia, this is probably the technology your phone
network uses, given it's the standard system for most of the world. GSM
networks use TDMA, which stands for Time Division Multiple Access. TDMA
works by assigning time slots to multiple conversation streams, alternating
them in sequence and switching between each conversation in very short
intervals. During these intervals, phones can transmit their information. In
order for the network to know which users are connected to the network, each
phone uses a subscriber identification module card, or SIM card.
SIM cards are one of the key features of GSM networks. They house your
service subscription, network identification, and address book information.
The cards are also used to assign time slots to the phone conversation, and
moreover, they tell the network what services you have access to. They store
your address book, too, along with relative contact information. They can
even be used to pass information between phones, if a carrier allows it.

CDMA explained
 
The Google Pixel XL is a smartphone that runs on a CDMA network.
CDMA - or Code Division Multiple Access - is often found in the U.S and
Russia, though GSM is also present in those countries. The Allied Forces
developed the technology during World War II, primarily as a method to
prevent Nazi forces from jamming radio signals. Unlike GSM, CDMA grants
users full access to the entire spectrum of bands, thus allowing more users
to connect at any given time. It also encodes each user's individual
conversation via a pseudo-randomized digital sequence, meaning the voice
data remains protected and filtered so that only those participating in the
phone call receive the data.
Phones on CDMA networks do not use SIM cards. Instead, each phone is built
specifically to work on that carrier's network. What does this mean for
consumers? For starters, it means that phones are tied to a carrier and
their bands, so if you decide to change providers, you'll have to buy a new
phone.

Is one better than the other?
 
Huawei's phones very rarely support CDMA
Not necessarily. Both are the global standards for cell communication. The
major factor affecting call quality is the network itself, not the method it
uses to transmit information. Of course, there are some things to keep in
mind when it comes time to choose between CDMA and GSM phones. For starters,
CDMA phones without SIM slots are tied to their carriers, and cannot be
transferred to other networks. A Verizon phone could not be transferred to
Sprint's network, for instance, or vice versa. But sometimes it's not as cut
and dried as all that - although some Verizon devices do use CDMA, they also
have an unlocked SIM slot, so could be unlocked for use on other networks.
Sprint is less forthcoming with unlocked SIM slots when its devices do
contain one, but you can usually find ways get your carrier to unlock your
phone when you're done with them.
In contrast, GSM phones are fairly easy to unlock and transfer to other
networks. Additionally, third-party manufacturers often sell phones designed
for GSM networks, since they don't require access to a specific carrier's
bands. GSM phones will even work in countries with compatible GSM networks.
CDMA networks allow for a greater number of users, meaning their capacity
for communication is greater than that of GSM networks. Moreover, CDMA is
the infrastructure on which all 3G networks are based - for both GSM and
CDMA carriers. However, there's now a third type of network that is quickly
becoming the frontrunner in terms of quality, with many major cell phone
companies quickly adopting it. Dubbed LTE for Long-Term Evolution, the
technology represents an evolved form of GSM, and uses a similar technology
as GSM networks. The new standard boasts enhanced voice quality and
functions as the base of high-speed, 4G data networks. In this case, LTE
does have an edge over the competition in terms of overall speed and
quality.
If you're a U.S. customer and wondering what companies use which type of
network, the split is right down the middle: AT&T and T-Mobile are GSM
carriers, while Verizon and Sprint are CDMA. In truth, picking a new phone
or carrier solely based on what standard it adheres to doesn't necessarily
matter because the services, features, phones, and service quality a network
offers aren't solely dependent on their network infrastructure. So unless
you have a particular need for choosing one over the other, go with the
carrier that best fits your tastes, needs, and budget.

Original Article at:
https://www.digitaltrends.com/mobile/cdma-vs-gsm-differences-explained/

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