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Figure 1.1 GSM evolution to UMTS

global cellular subscriber ¬gures. The emphasis is on enabling as much of the GSM
network as possible to continue to operate with the new system.
The goal of 3G is to provide a network infrastructure that can support a much broader
range of services than existing systems so the changes to the network should re¬‚ect
this. However, many of the mechanisms in the existing networks are equally applicable
to supporting new service models, for example mobility management. For a successful
migration, the manufacturers and suppliers of new 3G equipment understand that most
licences granted for 3G network operation will be to existing 2G operators and thus
the next step must be an evolution rather than a revolution. Operators in the main are
expected to introduce GPRS functionality before taking the step to 3G. This will allow
them to educate and develop the consumer market for these new services prior to major
investment in new technology. This means that the Core Network will comprise the GSM
circuit switched core and the GPRS packet switched core. The ¬rst release (Release 99)
speci¬cation for UMTS networks is focused on changes to the Radio Access Network
rather than the Core Network. This allows the Core Network to continue in functionality
although changes will be made in areas of performance due to the higher data rates
required by subscribers in the future networks. Maintaining this functionality allows the
mobile network operators to continue using their existing infrastructure and progress to
3G in steps. The handover between UMTS and GSM offering worldwide coverage has
been one of the main design criteria for the 3G system.

The IMT2000 is a global process, coordinated by the ITU-T to develop next generation
mobile networks, and covers both the technical speci¬cations and the frequency alloca-
tions. It was started in 1995 under the original heading of Future Plans for Land Mobile
Telecommunications System (FPLMTS). IMT2000 is not a particular technology, but
rather a system which should allow seamless, ubiquitous user access to services. The
task is to develop a next generation network ful¬lling criteria of ubiquitous support for
broadband real-time and non-real-time services. The key criteria are

• high transmission rates for both indoor and outdoor operational environments;
• symmetric and asymmetric transmission of data;
1.4 IMT2000 PROCESS 5

• support for circuit and packet switched services;
• increased capacity and spectral ef¬ciency;
• voice quality comparable to the ¬xed line network;
• global, providing roaming between different operational environments;
• support for multiple simultaneous services to end users.

The process is intended to integrate many technologies under one roof. Therefore, it should
not be seen that wireless technologies from different regional standardization bodies, or
supported by different manufacturers, are competing with each other, but rather that they
can be included in the IMT2000 family. This is evident with the development of such
interworking models as wireless LAN and 3G. A major enabler of the ITU-T vision is
the emergence of software de¬ned radio (SDR). With SDR, the air interface becomes an
application, which enables a single mobile device to be able to operate with a variety of
radio technologies, dynamically searching for the strongest signal, or the most appropriate
network to connect to.
Thus far, the ITU-T has given the imprimatur of 3G to ¬ve different radio access
technologies, as shown in Figure 1.2.
ITU-DS is the UMTS frequency division duplex (FDD) standard, ITU-MC is CDMA-
2000, and ITU-TC covers both UMTS time division duplex (TDD) and time division
synchronous CDMA. All these technologies are explained in Chapter 6. The IMT-SC sys-
tem, UWC-136, is the EDGE standard (Chapter 4). The ITU-FT incorporates the European
standard for cordless telephones, digital enhanced cordless telecommunications (DECT).
DECT provides a local access solution which may be used, for example, in a home
environment. The handset can automatically handover to a subscriber™s domestic access
point, providing dedicated resources. While the integration of DECT with GSM has been
standardized, it has yet to see any exposure.
The development of these standards is under the control of two partnership organi-
zations formed from a number of regional standardization bodies. The Third Generation
Partnership Project (3GPP, www.3gpp.org) is responsible for UMTS and EDGE, while the
Third Generation Partnership Project 2 (3GPP2, www.3gpp2.org) deals with CDMA2000
(Figure 1.3). DECT is the exception to this, with its standards developed solely by ETSI.
As can be seen, there is considerable overlap in terms of the bodies involved in the
two organizations. The various bodies are described in Table 1.1.


direct multi time single frequency
sequence carrier code carrier time


Figure 1.2 IMT2000 technologies

Europe USA China Japan Japan Korea USA


Figure 1.3 3G partnerships

Table 1.1 Standardization bodies
Body Description

ETSI The European Telecommunications Standards Institute is responsible for the
production of standards for use principally throughout Europe, but standards may
be used worldwide
T1 Committee T1 develops technical standards and reports in the US with regard to
the interconnection and interoperability of telecommunications networks at
interfaces with end user systems
CWTS The China Wireless Telecommunication Standard group has the responsibility to
de¬ne, produce and maintain wireless telecommunication standards in China
TTC The Telecommunication Technology Committee is a Japanese organization whose
role is to contribute to the standardization and dissemination of standards in the
¬eld of telecommunications
ARIB The Association of Radio Industries and Businesses conducts investigations into
new uses of the radio spectrum for telecommunications and broadcasting in Japan
TTA The Telecommunications Technology Association is an IT standards organization
that develops new standards and provides testing and certi¬cation for IT products
in Korea
TIA The Telecommunications Industry Association is the leading US trade association
serving the communications and information technology industries

One of the tasks was to allocate a band of the frequency spectrum for this new system.
Figure 1.4 shows the bands allocated, and compares this to the bands being used in both
the US and Europe/Asia-Paci¬c regions, with the exception of Japan and Korea.
As can be seen, the allocated frequency is already extensively used in North America,
and this presents deployment issues for 3G technologies. This is expanded in more depth
in Chapter 6. In this frequency use chart, MSS is the mobile satellite system, which
is the satellite component of 3G. Europe/Asia-Paci¬c has allocated all of the IMT2000
frequency to UMTS, with the exception of 15 MHz, which is already being used for
DECT. The UMTS allocation is as follows:

• UMTS FDD: uplink: 1920“1980 MHz; downlink: 2110“2170 MHz
• UMTS TDD: uplink: 1900“1920 MHz; downlink: 2010“2025 MHz.

Most countries have now completed the licensing of these new bands for 3G services,
many of them opting for an auction process. For UMTS, the basic carrier frequency is
5 MHz, and since it is a CDMA system it is possible to use only one frequency throughout
1.4 IMT2000 PROCESS 7

MHz 1850 1900 1950 2000 2050 2100 2150 2200

1885 1980 2010 2025 2110 2170

IMT-2000 MSS IMT-2000 MSS



Asia Pac

PCS MSS Reserved MSS

Figure 1.4 Cellular frequency usage

the system (see Chapter 2). For UMTS FDD, since there is 60 MHz of bandwidth available
in UL/DL, this equates to 12 carriers. However, it is recommended that an operator be
allocated three carrier frequencies. This is to tie in with the ITU-T principle of cell
hierarchies, which provides for the following cell types:

• Macro cell: large area, outdoor general coverage
• Micro cell: small area, densely populated urban coverage
• Pico cell: indoor coverage.

Each cell type could be allocated a different carrier frequency, allowing for an overlay
model. However, the decision of how to allocate frequencies is the remit of the national
regulatory authority in a country. As an extreme example, consider the situation in the
United Kingdom, which opted for the auction method. Five licences were allocated, as
shown in Figure 1.5.
Licence A is allocated 15 MHz of FDD plus 5 MHz of TDD, and was reserved for a
green¬eld operator. Licence B consists of 15 MHz of FDD spectrum, and licences C“E
10 MHz of FDD plus 5 MHz of TDD each. After a controversial auction which concluded
on 27 April 2000, the licences were sold as shown in Table 1.2.
Green¬eld operator TIW UMTS (UK) Ltd is owned by the Canadian operator Telesys-
tem International Wireless Inc. and is deploying UMTS in the UK as a joint venture
with Hong Kong™s Hutchison Whampoa, under the brand name 3. Commercial opera-
tion commenced at the end of December 2002. This rather cynical auctioning process
worldwide has done little to aid the development of 3G, and has been widely criticized


1900 MHz 1920 MHz 1980 MHz 2110 MHz 2170 MHz

Figure 1.5 UK 3G spectrum licences

Table 1.2 UK 3G auction results
Licence Operator Fee (£ bn)
A TIW UMTS (UK) Ltd 4.38
B Vodaphone Ltd 5.96
C BT (3G) Ltd 4.03
D One2One Ltd 4.00
E Orange 3G Ltd 4.10
Total 22.47

by many sources for the amount of capital it has taken out of the market. However,
the various regulatory authorities have argued that the fees re¬‚ect the potential that the
applicants expect from 3G in the long term.

This book is intended to provide detailed and relevant information on the technologies
related to the deployment of 3G systems, and focuses on UMTS. It is designed to cover the
requisite knowledge to a reader coming from either a telecommunications or a computer
networking background, examining how the different technologies are implemented in a
UMTS context, and how the system evolves to deliver the service model. Throughout
the text, examples of procedures are illustrated using trace ¬les captured from UMTS
networks to demonstrate their operation in practice.
Chapter 2 discusses the general principles on which packet-based networks are built,
highlighting their use for the transport of real-time traf¬c. Added to this is the complication
of a wireless interface to the network, and the mechanisms for providing multiple access
are also explored. In particular, an overview of the principles and operation of the CDMA
technique is presented, as this forms the central basis of the wireless physical layer of
most 3G technologies.
Chapter 3 begins the description of cellular systems with a detailed explanation of the
operation of the GSM. Aside from the access network, much of the existing GSM network
is reused in UMTS, particularly at the higher layers such as connection and mobility
management. In particular, the model for support of roaming within GSM and the basic
security architecture are important components carried forward and expanded upon in
UMTS. GSM is built around the signalling system 7 (SS7) protocol suite as used in the
¬xed-line PSTN, with extensions to support users accessing through a wireless interface.
Chapter 4 introduces the ¬rst major evolutionary step of GSM, the general packet
radio service (GPRS). The GSM network has been designed and optimized for the deliv-
ery of one application, voice calls. Other services offered are considered supplementary.
Chapter 2 explains why this type of network is not well suited for data transport, due to
the vastly different requirements of the traf¬c. GPRS adds a network infrastructure based
around the IP protocol which is designed with the needs of this data traf¬c is mind. It
is also an essential building block of the UMTS network. Also described here is EDGE,
which builds on GSM/GPRS to create a relatively high-speed network, without the major

capital expenditure of UMTS. EDGE can be seen as a 3G solution in itself, or as a
technology to complement a UMTS roll-out.
Chapter 5 describes the IP protocol suite and, in particular, its application to both the
GPRS and UMTS Release 99 networks. Central to this is the ability of IP to provide
mechanisms for quality of service (QoS), reliability and secure communication. The basic
operation of IPv6 is discussed as it may be used as an application data bearer in UMTS.
Also addressed are the related IP protocols for support of CDMA2000 networks.
Chapter 6 explores the architecture and operation of the UMTS network. It links what
has gone before in GSM and GPRS with the new radio access network that forms the


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