Page 61 - Reference framework for integrated management of an SSC - A U4SSC deliverable on city platforms

This ecosystem is dynamic and highly unpredictable as the needs for quality, bandwidth and
availability grow and vary spatially and temporally. Different areas in the city, financial as well as
residential, show very different patterns of behaviour and great variability throughout the day.
In addition, critical information must be available and must take precedence over less relevant
information. Ensuring that the network is able to adapt to the – in many cases abrupt – increases
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in traffic while maintaining the efficiency and quality of the underlying services is a complex task
and one that entails a significant impact on costs.

The Next Generation Network (NGN) has been defined to respond to these demands. Unlike
classic telecommunications networks, services and applications of a very different nature share
resources of a common infrastructure. In NGN, different levels have been defined in turn, and these
are described briefly below: 27,28

• The access network allows connectivity between devices/capillary networks to a node of the
transport network. It is the most onerous component of the architecture, given the huge number
of users and the underlying hedging/cost difficulties.

• Transport networks provide connectivity between different access networks and are characterized
by offering high transmission capacities over long distances.
• The media layer is the common core of information routing and is specialized in the dynamic
management of the capabilities of the transport network, in order to differentiate traffic of
different natures, adapt speeds and maintain the quality of service.

• The telecommunication services layer provides advanced communication services such as
unified communications, virtual private network (VPN) services and software-defined networks
(SDN).

One of the implications of a unified architecture is that the availability of network resources can
change dynamically over time, and congestion occurs degrading the quality of service (QoS)
compromised in international recommendations. Networks with opportunistic connections such
as mobile networks or ad hoc networks are especially vulnerable to these changes. 29,30

The categorisation and standardisation of this type of traffic is an area in constant development.
3GPP in TS 22.368 defines categories and functionalities of Machine-Type Communications (MTC)
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fonts, but not their behaviour pattern. ITU-T, in its Recommendation Q.3925, defines different types
of sources for the verification of quality-of-service parameters in NGN, but of the seven types of
MTC sources described, it leaves three for further studies. 32

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