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As cellular standards develop, the mobile telephony technology that carriers choose to adopt does not matter to consumers as much as other factors.
In the early days of cellular, enormous vendor- and carrier-sponsored battles over underlying wireless technologies were common. There were eight different -- and incompatible -- analog 1G cellular technologies operating in Europe in the 1980s. A narrowband digital cellular standard, 2G, was spread among four different technologies (i.e., GSM, IS-95 CDMA, IS-136 TDMA and iDEN, which was used by Nextel) in the U.S. in the mid-1990s.
Additional confusion complicated the picture as digital, packet-based wireless services began to appear. GPRS, one of the first of these, was often called 2.5G. EDGE, which was popularized in the original iPhone, was occasionally referred to as 2.75G, even though it officially qualified as 3G. Subsequent 3G deployments have been dominated globally by UMTS, a direct descendent of the global system for mobile communication (GSM), globally the most popular 2G technology. Add CDMA2000 to the mix, which is primarily in operation in North America, and there are six different technologies -- including EDGE -- approved by the International Telecommunication Union (ITU) as qualifying for the 3G name under their IMT-2000 program. 3G, motivated by digital, packet and especially broadband requirements, contributed to the diversity of and debate over cellular standards.
With each generation, complex arguments as to why a specific technology needed to be the choice were common. Consumers were ultimately exposed to these, despite few being able to comprehend the basics. Some vendors consequently bumped these code division multiple access (CDMA) vs. GSM debates to the back burner. Verizon Wireless, for example, switched to a conversation regarding coverage and throughput, and became the U.S. carrier with the largest subscriber base as a result.
GSM and CDMA: A brief overview
GSM services first launched in Finland in 1991. Nowadays, there are nearly 700 mobile networks in over 200 countries. According to GSM World, there are now more than 2 billion GSM mobile phone users worldwide, with China, Russia, India and the United States -- in that order -- having the most.
GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephony technologies -- TDMA, GSM, and CDMA. GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency band.
CDMA, along with GSM and TDMA, refers to any of several protocols used in second-generation (2G) and third-generation (3G) wireless communications. As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellphone systems in the 800-MHz and 1.9-GHz bands.
LTE vs. CDMA in the 4G mobile marketplace
With the advent of 4G, however, technology options have converged to LTE alone. Other candidates, including the vastly overhyped Mobile WiMAX, exited the 4G scene fairly quickly. LTE also had a built-in advantage from the start, being a direct descendent of GSM. The 4G moniker here is purely for marketing purposes -- the ITU has stated that 4G only officially applies to LTE-Advanced (LTE-A), which is largely defined by 100+ Mbps throughput, an all-IP architecture and more sophisticated management capabilities. LTE-A is just beginning to see production deployments, and it will be more than five years before such services become common.
Quiz: Wireless standards and protocols
CDMA vs. GSM is only one aspect of mobile telephony technology. Take the following quiz to prove just how much you know about the industry's standards and protocols.
What does CDMA vs. GSM mean to users?
Users today are often surprised to find the 3G indicator lit on their otherwise 4G handsets, but 3G technologies remain important even as 4G buildouts continue. As is also the case with 2G, we expect that many 3G systems will remain in operation for quite some time. In some parts of the world, technological choice is very limited, with some operators stuck at 2G or 3G deployments -- we're unaware of any analog systems still in operation. In industrialized economies, carriers are rapidly evolving toward LTE and ultimately LTE-A.
Users with contemporary handsets -- those less than two years old -- have little to worry about; backward compatibility from LTE-A to LTE to UMTS -- and often CDMA2000 -- to GSM is a key feature of these modern devices. While everyone would like to have access to the higher throughput and greater capacity of newer technologies, some connectivity is always better than none. Users of older handsets will have to upgrade, but they'll get the benefits of enhanced feature sets (i.e., improved power consumption, better screens, more storage, faster processors and more) that extend well beyond carrier technology alone.
Users aren't alone, as carriers are also incentivized to upgrade their networks. The management features noted above, more formally known as operational support systems, improve carrier staff productivity. New base stations are far less expensive to purchase and operate than older models, and the advent of viable small-cell implementations further encourages carriers to upgrade. While the associated economics can be as complex as the underlying technologies, 4G is becoming common in industrialized economies. As handset turnover continues, carriers can phase out older technologies and reallocate the spectrum used by these exclusively to 4G. We'll leave speculation regarding 5G to another day, but there's little doubt that backward compatibility will play a major role.
What this means is that carrier technology and the CDMA vs. GSM debate -- or, for that matter, LTE vs. CDMA -- is less consequential with each passing day. Almost everywhere, carriers are going with LTE and those that are sticking with 2G and 3G technologies will benefit from the backward compatibility in modern subscriber devices. Of far greater importance to end users today is a given carrier's footprint (coverage), capacity (a function of the amount of spectrum they have access to, plus the number of base stations), policies, pricing and support. While it's always a good idea to ask about LTE before signing the contract, technology alone really isn't much of an issue anymore.
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