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<h1>GSM network architecture</h1>

<p>The GSM network is functionally divided into three elements.
Base Station Subsystem (BSS) is one of the main functional elements of the
GSM network. The other elements in the GSM network are the network switching
subsystem (NSS), GPRS core network to SGSN and network service and management
subsystem (Nokia NetAct).</p>


<p>The main function of the BSS is to connect the mobile subscriber's
mobile station (MS) to the GSM network and through it to the mobile switching
centre (MSC), and to GPRS core network, serving GPRS support node (SGSN).
The BSS also takes care of the mobility management of the cellular network
including, for example, handover management and various measurements.</p>


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<img alt="urn:mars:dn9774393:5:en:global:cgm_fixed:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn9774393&amp;edition=5&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: Nokia Base Station Subsystem in the GSM network</p>
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<h2>Advantages of Nokia Base Station Subsystem</h2>

<p>The high capacity Nokia Base Station Subsystem is based
on a fully integrated system approach, offering a unique system solution with
built-in intelligence and flexibility. The use of advanced features with the
greatest potential for capacity, coverage and quality result in the maximum
performance of the GSM network.</p>


<p>Nokia BSS comprises a number of base stations (BTS), base
station controllers (BSC), transcoder submultiplexers (TCSM), power systems,
antenna line and cellular transmission (CT). Nokia BSC and TCSM have been
designed to allow a flexible locationing within the GSM network. For example,
the TCSM can be co-located on the same site with the BSC or MSC to economise
transmission costs.</p>


<p>The modular design of Nokia equipment has many advantages.
It facilitates the upgrading of hardware and software, causing minimal disturbance
to the network. The modularity also makes Nokia equipment easily expandable.
Due to the modularity, the size of Nokia BSC, Nokia TCSM and Nokia BTS is
relatively small and compact, which make it easy to place and thus enables
fast roll-out.</p>


<p>Nokia equipment conforms to the GSM specifications. For
more information on the subject, see <em>Nokia Statement of
Compliance.</em></p>


<p>The individual BSS network elements are linked together
with cellular transmission (CT) or leased line connection. The Nokia integrated
transmission solution provides an automatic path protection by the formation
of loops with secure radio links. The base station integrated cross-connection
functionality reduces the transmission costs between the BTSs and BSCs.</p>


<p>The provision of high quality services to end users is
also enabled by the capability of full mobile services availability, achieved
by protecting the BTS against mains voltage breaks and keeping services running.
The Nokia power systems have been specified, tested and optimised to secure
the Nokia BTS site element functions, ensuring safe DC distribution for BTSs
and LTEs.</p>


<p>Prerequisites for the availability of the BSS network elements
are simplicity and speed of the servicing procedures, such as fault repair
time. In Nokia BSS this is guaranteed in many ways. Built-in redundancy functionalities
and efficient supervision functionalities minimise the time spent in maintenance.
In addition, reliable network elements and automatic fault detection and recovery
procedures cause less need for site visits. As a result, the network maintenance
is more economical.</p>


<p>Nokia Network Planning System aids the operator to plan
the network to be as cost-effective as possible. The network
service and management system (Nokia NetAct) provides the means to implement
and modify the plans to the network.</p>


<p>Nokia Customer Operations provides planning, implementation,
training and technical support services as a part of the complete Nokia BSS
system solution.</p>
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