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About
GSM
GSM stands for Global System for Mobile
Communications and is Europe’s leading digital
wireless technology. There are over 400 million
customers on GSM to-date, in over 150 countries,
with service provided by over 400 operators.
On today’s
current TDMA network system, each voice channel on
a site is 30 kHz wide and carries 3 calls. In the old
days of analog technology, each voice channel was able to
carry only one call. Therefore, with the initial switch
to Digital PCS, we were able to carry three times as many
calls on each digital voice channel on our network.
This
all changes with GSM. With GSM, we will be able to take
a much wider voice channel – 200 kHz wide - and split
it into 8 time slots. A channel can be designated as voice
or data carrying. Thus the result is greater capacity
to carry information over our network and also the
ability to carry more data than ever before
About GPRS
GPRS stands for General Packet Radio Service. It is part of the GSM standard and delivers
“always on” wireless packet data services to GSM
customers. GPRS can provide theoretical packet data
speeds of up to 84kb/s.
A “packet”
service refers to how information is first broken
up into smaller pieces, called packets. Its place
of origin, destination and place in the original data
identify each packet. The packets are then sent into the
network where they are routed by various paths to the final
destination. The packets are reassembled in the correct
order at the final destination.
About
TDMA
Time Division Multiple Access (TDMA)
is digital transmission technology that allows a
number of users to access a single radio-frequency
(RF) channel without interference by allocating
unique time slots to each user within each channel.
The TDMA digital transmission scheme multiplexes
three signals over a single channel. The current
TDMA standard for cellular divides a single channel
into six time slots, with each signal using two
slots, providing a 3 to 1 gain in capacity over advanced
mobile-phone service (AMPS). Each caller is assigned a
specific time slot for transmission.
TDMA
Overview
The
wireless industry began to explore converting the
existing analog network to digital as a means of
improving capacity back in the late 1980s. In 1989,
the Cellular Telecommunications Industry Association
(CTIA) chose TDMA over Motorola’s frequency division
multiple access (FDMA) (today known as narrowband
analog mobile-phone service [NAMPS]) narrowband
standard as the technology of choice for existing 800
MHz cellular markets and for emerging 1.9-GHz markets.
With the growing technology competition applied by Qualcomm
in favor of code division multiple access (CDMA)
and the realities of the European global system
for mobile communications (GSM) standard, the CTIA
decided to let carriers make their own technology
selection.
The two
major (competing) systems that split the RF are TDMA and CDMA.
CDMA is a spread-spectrum technology that allows multiple
frequencies to be used simultaneously. CDMA codes every
digital packet it sends with a unique key. A CDMA receiver
responds only to that key and can pick out and demodulate the
associated signal.
Because
of its adoption by the European standard GSM, the
Japanese Digital Cellular (JDC), and North American
Digital Cellular (NADC), TDMA and its variants are
currently the technology of choice throughout the
world. However, over the last few years, a debate
has convulsed the wireless community over the respective
merits of TDMA and CDMA.
The
TDMA system is designed for use in a range of environments
and situations, from hand portable use in a downtown
office to a mobile user traveling at high speed
on the freeway. The system also supports a variety
of services for the end user, such as voice, data,
fax, short message services, and broadcast messages.
TDMA offers a flexible air interface, providing
high performance with respect to capacity, coverage,
and unlimited support of mobility and capability to handle
different types of user needs.
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