.JPG
: JPEG (usually pronounced JAY-pehg) is a term
for any graphic image file produced by using a JPEG
standard. |
|
1G
: Also known as: First Generation 1G (First
Generation) is the name given to the first generation of mobile
telephone networks. These systems used analogue circuit-switched
technology, with FDMA (Frequency Division Multiple Access), and
worked mainly in the 800-900 MHz frequency bands. The networks had
a low traffic capacity, unreliable handover, poor voice quality,
and poor security. As the 1G networks became obsolete, their
frequencies were auctioned off for use in 2G and 3G networks.
Examples of these first generation mobile phone networks are AMPS
(Advanced Mobile Phone Service), TACS/ETACS (Total Access
Communications System / Extended Total Access Communications
System), NMT 450 (Nordic Mobile Telephone System) and NTT (Nippon
Telegraph and Telephone System). |
|
2.5G
: Also known as: Second Generation 2G (Second
Generation) is the generic term used to refer to the second
generation of wireless mobile telephone networks, which were the
first to feature purely digital technology. As demands for the
quality and quantity of mobile communication services increased, 2G
systems were the logical next stage in the evolution from the 1G
(first generation) analogue systems. Typical characteristics of 2G
include roaming, better high-bit-rate voice quality, improved
security with different levels of encryption, the ability to convey
some data (e.g. SMS) as well as speech, and a wider selection of
subscriber services. Examples of the major second generation
digital mobile telephony systems are: GSM (Global System for Mobile
Communications) in Europe, IS-95 (CDMAone) and IS-136 (D-AMPS /
TDMA) in the USA, and PDC (Personal Digital Cellular) in
Japan |
|
2G
: Also known as: Second Generation 2G (Second
Generation) is the generic term used to refer to the second
generation of wireless mobile telephone networks, which were the
first to feature purely digital technology. As demands for the
quality and quantity of mobile communication services increased, 2G
systems were the logical next stage in the evolution from the 1G
(first generation) analogue systems. Typical characteristics of 2G
include roaming, better high-bit-rate voice quality, improved
security with different levels of encryption, the ability to convey
some data (e.g. SMS) as well as speech, and a wider selection of
subscriber services. Examples of the major second generation
digital mobile telephony systems are: GSM (Global System for Mobile
Communications) in Europe, IS-95 (CDMAone) and IS-136 (D-AMPS /
TDMA) in the USA, and PDC (Personal Digital Cellular) in
Japan |
|
3-Way Calling
: Also known as: Conference Call 3-Way Calling
(Conference Call) is a network facility that enables three or more
parties to be connected together in a conference call, so that they
may all speak and listen simultaneously. This is often used as a
convenient substitute for a physical meeting, as the participants
can be located in different towns, or even in different countries.
This feature is very useful when two friends are having a
conversation and they need to ask questions of a third person
instead of hanging up and calling back, the third party can be
dialled during the course of the conversation to set up a
conference call |
|
3G
: Also known as: Third Generation 3G (Third
Generation) is a generic term used to refer to the latest standard
of wireless mobile telephone networks. Third Generation phones are
capable of the high data rates, wide bandwidth and increased
capacity needed to support the new range of digital services
available for mobile devices, such as Internet access, multimedia
applications, and support for global roaming. The major multiple
access transmission technique used in 3G is CDMA, a
packet-switching technology, which provides a more efficient use of
the available spectrum than did the earlier methods of FDMA and
TDMA. The two main 3G technologies used are UMTS with wideband CDMA
(W-CDMA) in Europe, and cdma2000™ with multi-carrier CDMA (MC-CDMA)
in the USA. Many 3G systems will operate in the 2 GHz frequency
band, and are designed to provide a range of data rates from 144
kbps to 2 Mbps, depending on the user's location and circumstances.
The 3G mobile communications standard was a programme led
originally by the ITU under the IMT-2000 project, and handsets and
networks are now generally defined as UMTS (Universal Mobile
Telecommunication Service). However, despite the intention that the
IMT-2000 specification would result in a single, unified 3G system,
several different versions of 3G have developed due to the leading
telecommunications companies choosing to take a more evolutionary
approach to upgrading their networks |
|