Thisismobile.net is a resource site dedicated to providing
cell phone reviews and information on all things mobile.
Types of technology your
cell phone uses:
GSM - Global System for Mobile Communication.
GSM is currently the dominant 2G digital mobile phone standard
for most of the world. It determines the way in which mobile
phones communicate with the land-based network of towers.
GSM has not been the most popular standard in the United States
in the past. CDMA and TDMA, competing standards, together shared
most of the market.
However, AT&T Wireless and Cingular, who both used TDMA
technology, recently switched to GSM technology. This will narrow
the major technologies in the US to two - GSM and CDMA.
The most visible feature of GSM are SIM cards. SIM cards are
removable, thumbnail-sized smart cards which identify the user
on the network, and can also store information such as phone
book entries. SIM cards allows users to switch phones by simply
moving their SIM card from one phone to the other.
GAIT - GSM/ANSI-136 Interoperability Team.
GAIT, the GSM/ANSI-136 Interoperability Team, was a group composed
of North American TDMA and GSM operators, and the Universal
Wireless Communications Consortium (UWCC). They developed a
standard (also referred to as "GAIT"), which allows seamless
roaming between TDMA and GSM networks.
TDMA (ANSI-136) and GSM are two of the three main digital technologies
for mobile phones and networks. (CDMA is the other.)
The driving force behind this standard is the fact that two
major US carriers - AT&T Wireless and Cingular - are both
transitioning their networks from TDMA to GSM technology. During
the transition period, they have been operating both types of
networks at the same time. Therefore, it is beneficial to have
phones that work seamlessly on both types of networks.
The GAIT standard consists of upgrades to the networks, and
also new "GAIT" phones. With both in place, roaming and features
like SMS text messaging and voice mail are seamless across both
types of networks, making the transition smoother for users.
GAIT technology does NOT provide seamless handoffs between TDMA
and GSM. For example, when moving from a TDMA area to a GSM
area (such as on a highway) a call in progress will drop. GAIT
only allows certain features to work similarly on both types
of networks. Without GAIT, TDMA users would not be able to access
SMS while on a GSM network, and vice-versa.
TDMA - Time-Division Multiple Access.
TDMA is a digital mobile phone technology. In TDMA, the frequency
band is split into a number of channels, which are stacked into
short time units, so that several calls can share a single channel
without interfering with one another.
Put another way, TDMA allows several devices to share the same
frequency band at the same time, by letting each device "take
turns" sending digital data. Each "turn" is called a "time slot".
TDMA, as a basic method of transmitting digital signals over
radio waves, is the basis for several major wireless standards,
including GSM, iDEN, and IS-136. IS-136 is commonly referred
to as simply "TDMA".
CDMA - Code-Division Multiple Access.
CDMA is a digital wireless technology. It is a general type
of technology, implemented in many specific technologies. But
the term "CDMA" is also commonly used to refer to one specific
implementation: IS-95 - a mobile-phone technology that competes
with technologies such as GSM.
CDMA is a "spread spectrum" technology, which means that it
spreads the information contained in a particular signal of
interest over a much greater bandwidth than the original signal.
Unlike many competing technologies, CDMA has no hard limit for
the number of users who may share one base station (tower).
Instead, with CDMA, additional users can connect until the base
station determines that call quality would suffer behind a set
limit.
CDMA systems have been in commercial operation since 1995. CDMA
networks operate in the 800 and 1900 MHz frequency bands with
primary markets in the Americas and Asia. IS-95 CDMA systems
are sometimes referred to as cdmaOne. The next evolutionary
step for CDMA to 3G services is cdma2000.
