| Mobile
Technology
A mobile phone, also known as a cellphone, mobile,
handphone or cellular phone, is a portable electronic device which
behaves as a normal telephone whilst being able to move over a wide
area (compare cordless phone which acts as a telephone only within
a limited range). Mobile phones allow connections to be made to
the telephone network, normally by directly dialing the other party's
number on an inbuilt keypad. Most current mobile phones use a combination
of radio wave transmission and conventional telephone circuit switching,
though packet switching is already in use for some parts of the
mobile phone network, especially for services such as Internet access
and WAP.
Some of the world's largest mobile phone manufacturers
include Alcatel, Audiovox, Kyocera (formerly the handset division
of Qualcomm), LG, Motorola, Nokia, Panasonic (Matsushita Electric),
Philips, Sagem, Samsung, Sanyo, Siemens, SK Teletech, and Sony Ericsson.
There are also specialist communication systems
related to, but distinct from mobile phones, such as satellite phones
and Professional Mobile Radio.
Technology
Though mobile phones vary significantly from provider
to provider, and even nation to nation (most noticeably in North
America), all mobile phones must generally accomplish the same tasks
regardless. Mobile phones must be connected to the system of land-line
phones. Mobile phones must also be able to connect with each other
just as easily, even if the two phones are not from the same mobile
service provider. Consequently, all mobile phone systems are comprised
of two components; the handset, and the tower. The handset is the
portable device, refered to as the mobile phone, cellphone or a
smartphone. The tower is a high-yield radio tower that the mobile
phones direct their radio communications to in order to connect
to the network of telecommunications. It could also be a network
of satellites.
Handsets feature a low power transceiver that is
typically designed to transmit voice and data, or analog audio only,
up to a few kilometers under ideal situations to where the tower
is located. The handset listens for an available tower. Once found,
the handset informs that tower of its own unique identifier, and
alerts the mobile phone network that it is ready and standing-by
to receive telephone calls. It then periodically repeats this information
to the tower, and seeks out new towers over the duration it is powered
on.
Towers are large structures that feature a series
of high power radio transmitters designed to broadcast their presence
and availability, and relay communications to the mobile handsets.
The tower features a much higher-powered radio transceiver array
that allows it to provide a radio communications dialog with handsets
dozens of kilometers away. The tower is connected to the landline
telephone infrastructure by a high-capacity phone line, and may
also be connected to a dedicated data line. The tower can then route
calls between the mobile handsets it's serving, and telephone calls
over the landline. Because the tower tracks and relays what mobile
handsets it is servicing, it can inform the mobile network provider
so that at any given time a call to a mobile phone can quickly be
traced to the tower that is servicing that handset.
Most mobile phones dialog between the handset and
the tower is comprised of a data stream of digitized audio. The
technology driving this process can vary, and in nations with no
standard or preference (such as the United States), many incompatible
technologies exist. Not only do transmission standards potentially
differ, but so do the radio frequencies. Some technologies include
AMPS for analog, and TDMA, CDMA and GSM for digital communications.
Though nations like the USA have generally avoided official standardization,
most nations of the world have agreed upon the GSM data transmission
protocol for cellphones, and a small range of possible frequencies
that mobile phones may operate on. Phones are classified based on
the technology they use and the features they have. See the table
on the right for a comprehensive listing.
List of Source Systems Mobile Applications
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