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GSM (Global System for Mobile
Communications)
The concept for GSM started in 1982 when CEPT (Conference for
European Post and Telecommunications Administration) formed a
committee known as Groupe Speciale Mobile. The main reason for
the formation of this committee, was to create a standard for
mobile communications within Europe. This would have several distinct
advantages, such as the user would be able to use their phone
anywhere within Europe, and any manufacturer would be able to
produce any part of the overall system. When conceived GSM was
not envisaged as being a global standard.
In 1990 the design development of GSM was frozen into a set of
standards known as the "GSM Specifications".
GSM Phase 1
The standardisation of GSM900 was completed in 1990 and of DCS1800
in 1991. These standards are designated as GSM Phase 1, they include
all the central requirements for a digital cellular network. Speech
transmission (Full Rate Speech) is of central importance. Data
transfer is defined with rates of 0.3 up to 9.6 kbit/s. only a
few basic Supplementary Services (call forwarding and call baring)
are included.
GSM Phase 2
The standardisation of Phase 2 was completed in 1995, the main
topics were Supplementary Services comparable with those of a
fixed network ISDN (Integrated Services Digital Network). Furthermore,
technical enhancements, e.g. Half Rate Speech, were defined. Of
great importance was the decision to enable downward compatibility
to the previous phases for all future GSM phases.
GSM Phase 2.5
GSM Phase 2.5 is characterised by a smoother transition as opposed
to the previous phase changes. No complete revision of the GSM
standard will be carried out but single topics will be handled
separately. The standard is being updated in Annual Releases since
1996. The current topics concern new Supplementary Services, IN
applications, services for specific user groups and enabling data
transmission with high data rates.
GSM Evolutionary Concepts
Diagram
Figure 1 GSM Evolutionary Concepts
(Adapted from Ericsson LZU 108 879)
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