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GSM basic（英文版）-49页-英文

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0楼发表于: 2008-11-07 00:30:30

Welcome to RFTD 101 on GSM basics.  In this module, we will introduce the architecture and working of the world’s most
popular cellular standard.
At the end of this module you should have a broad understanding of the GSM system, it’s air interface and how a call is
connected on a GSM network.
So let’s go straight in.  But first, a little history.
In 1981 analogue cellular was introduced and was a very successful communications technology.  At about the same time there
was a joint Franco-German study looking at digital cellular technology and the possibility of making a pan-European system.
In 1982 a special working committee, GroupeSpécialMobile (GSM), was formed within the CEPT to look at and continue the
Franco-German study. In 1986 the working committee was taken a step further by the establishment of a permanent nucleus of
people to continue the work and create standards for a digital system of the future. About a year later, the memorandum of
understanding, or MoU, as it is referred to, was signed by over 18 countries. It stated that they would participate in the GSM
system and get it into operation by 1991.
In 1989 GSM was moved into the ETSI (European TelecommunicationsStandards Institute) organization. Once under the
control of ETSI, the GSM system had it's name changed to Global System for Mobile communications.  The committees
working on the system changed from GSM to SMG (Special Mobile Group).  These changes avoided confusion between the
system name (GSM), and the people working on the specification (SMG).  It also brought the naming in line with the official
working language of ETSI (English).
In 1990 the GSM specification developed an offshoot -DCS1800.  The Original DCS1800 specifications were developed simply as edited
versions of the GSM900 documents.  Interest in GSM quickly spread outside Europe. In 1992 Australia became the first non-European
country to join the MoU. Since then, most Asian countries have adopted GSM.  The Phase II specification for GSM has now been defined,
merging GSM900 and DCS1800 documents, a number of new features are added to the system, along with many minor adjustments.  Phase
II+ defines the addition of specific new services such as data and fax to GSM and DCS1800.
Today, GSM is by far the most popular cellular format. &nb ..

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