TACS/ETACS
The original analog version of this wireless system was brought to
commercial deployment by AT&T in 1983, prior to divestiture, based on the
concept that higher capacity could be achieved by small (i.e. low power)
cells, allowing frequencies to be reused. Other advantages, not known
at the time, included the possibility of handheld phones and low terminal
prices due to advances in electronics technology and the economies of scale
of the mass market. Consequently, an industry that was estimated by
optimists when the first systems in Chicago and Washington/Baltimore came
online in 1983 as likely to serve 1 million subscribers in the US by the year
2000, actually was serving well over 50 million subscribers by 1998!
AMPS originally operated as an analog system in the 800 MHz frequency
band. However, it has since expanded to TDMA and CDMA digital operation
and, more recently into the 1800 MHz - 2200 MHz PCS frequency band. The
best known AMPS systems are in the US and Canada, but AMPS is also a de facto
standard throughout Mexico, Central and South America, very common in the
Pacific Rim and also found in Africa and the remains of the USSR. In
summary, AMPS is on every continent except Europe and Antarctica. AMPS
is defined not by a single standard, but by many standards. All the
standards are developed by the TR-45 committee within the TIA
(Telecommunications Industry Association). Even the radio interfaces
are defined by several families of standards, one for each technology
(Analog, NAMPS, TDMA and CDMA). Automatic roaming with a cellular phone
is made possible by the TIA/EIA-41 standard that provides intersystem
handoff, call delivery, remote feature control, short message delivery,
validation and authentication through an intersystem messaging protocol.
TIA/EIA-41, developed by the TIA TR-45.2 subcommittee, is often
discussed in Cellular Networking Perspectives. There are other forms of
cellular and PCS in the world:
The European 900 MHz digital cellular system, which has also expanded to
many parts of the world and into the PCS band (where it is known as DCS1800
or PCS1900). GSM provides intersystem operations through its own MAP
(Mobile Application Part) protocol, making its operation relatively
incompatible with the AMPS family that shares the common TIA/EIA-41
intersystem operations protocol. GSM is the biggest challenger to the
AMPS family of technologies.
A Scandinavian 450/900 MHz analog cellular system, the closest thing in
Europe to a standard prior to GSM. NMT systems have been installed in
many countries outside Europe. Most NMT systems will eventually be
displaced by GSM.
AMPS with a few minor changes, operating in the 900 MHz frequency band.
The largest TACS networks are in the UK, but it has also been
installed in many other countries around the world.
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