Telektronikk 2/3.2001
1 Introduction
The scope of this article is to give a brief over-
view of the QoS framework of the 3rdgeneration
mobile network UMTS (Universal Mobile
Telecommunication System). UMTS is devel-
oped by the 3GPP (Third Generation Partnership
Project), which is an interest organisation put
together of many global standardisation bodies
such as ETSI, ARIB, T1, TTC, CWTS and oth-
ers. The vision of UMTS is to support both tradi-
tional circuit switched and packet based services
as well as multimedia. All services shall be car-
ried over the W-CDMA (Wideband Code Divi-
sion Multiple Access) radio system, which is
specially suited to support variable bit rates and
traffic with different characteristics. With the
tremendous growth of the Internet the past few
years, and the wide variety of new IP based
applications that have appeared, it is recognised
that the new mobile network also has to be
equipped to support the application require-
ments. People would like to be able to access the
same services from a mobile terminal as from
their stationary terminal, with the same or only
minor degradation in quality. Major effort has
therefore been put on developing a future proof
QoS framework capable of supporting a wide
spectrum of applications, taking into account the
special characteristics of radio transmission.
Admission control with good resource manage-
ment is vital to achieve acceptable quality for the
users connected to the system. When users move
between radio cells (handovers) functionality
has to be deployed which quickly manages to
switch the connecting point of the user to the
network without noticeable degradation of qual-
ity. The radio interface puts major challenges on
the development of a QoS control system to
cope with the scarce resources, unpredictable
traffic picture, vulnerability to air disturbances,
etc. The work is therefore tedious with very
many aspects to consider. Since the UMTS sys-
tems evolve through releases the QoS frame-
work is updated accordingly.
The first release of UMTS was Release 99. That
release was finalised in June 2000. Rel-4 was the
next release, which was completed in March
- 3GPP is now working on Rel-5. Rel-5 is
expected Q 1 of 2002. The UMTS architecture
has developed through these releases, becoming
gradually more IP focused both regarding trans-
port and signalling. The circuit switched domain
comprising much of the legacy GSM core net-
work infrastructure has gradually been replace
by an optionally IP based transport infrastruc-
ture. Hence, the major impact of IP based appli-
cations and the importance of real time support
on an IP infrastructure have been recognised.
A targeted goal has been to support VoIP and
packet based multimedia applications on the
packet switched domain with the same or better
quality than experienced in the circuit switched
GSM network.
The article starts by giving a brief overview of
the different UMTS releases. The different
releases impact the QoS developments by gradu-
ally extending the QoS functionality. The differ-
ent releases cover the UMTS QoS bearers, QoS
management entities, end-to-end aspects, QoS
for multimedia handling, policy framework etc.,
making up a total QoS framework. Chapter 3
looks specifically into the QoS framework and
explains the QoS architecture of UMTS both
related to the control and user plane functional-
ity. The mechanisms used in UMTS to support
differentiated services with separate service
Quality of Service in UMTS
THOR GUNNAR ESKEDAL AND FRÉDÉRIC PAINT
The third generation cellular network, UMTS (Universal Mobile Telecommunication System), is a
standard specified by the Third Generation Partnership Project (3GPP). It deploys the 3rdgeneration
W-CDMA air interface which will be deployed in Europe and Asia, including Japan and Korea in the
frequency band around 2 GHz. With this frequency it is capable of a peak bandwidth of 2 Mb/s which
may support simultaneous low bit rate voice services and high bit rate multimedia and video applica-
tions. To ensure reusability of platforms, it was decided to reuse the GPRS architecture. With the advent
of real time Internet multimedia services it was felt necessary to ensure the provisioning of QoS. This
was not trivial given the deficiencies of GPRS in supporting QoS. Considerable work was made to
provide the necessary enhancements in the specifications to ensure adequate QoS support.
In this paper we provide an overview of the UMTS Quality of Service concept and give some insight into
the mechanisms used to provide Quality of Service to upper layers. Additionally we discuss the latest
enhancements being included in UMTS specifications to provide end-to-end Quality of Service.
Frédéric Paint (28) has been
working for Telenor R&D since
his graduation from ENST Paris
(telecom engineering school) in
- His work has focused on
3G core networks and their evo-
lution. This effort included par-
ticipation in research projects
(e.g. Eurescom P920 and
Eurescom P1013) and standard-
isation activities (3GPP). More
recently he has been involved in
the field of mobility in IP net-
works specifically on micro-
mobility support and inter-
access mobility.
[email protected]
Thor Gunnar Eskedal (36)
obtained his Masters degree in
physics in 1990 from the Univer-
sity of Oslo. After working one
year as a senior research assis-
tant in the Department of Tele-
matics at the Norwegian Univer-
sity of Science and Technology
(NTNU), he joined the broad-
band networks group at Telenor
R&D in 1991. In the last couple
of years he has been involved in
the UMTS standardisation effort
mainly concentrating on IP-
based QoS mechanisms, IP
mobility and systems architec-
ture.
thor-gunnar.eskedal
@telenor.com
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