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3

Universal Mobile Telecommunications System (UMTS)
and High‐Speed Packet Access (HSPA)

The Universal Mobile Telecommunications System (UMTS) is a third‐generation wireless
telecommunication system and followed in the footsteps of the Global System for
Mobile Communications (GSM) and General Packet Radio Service (GPRS). Since GSM
was standardized in the 1980s, huge progress had been made in many areas of telecom-
munications. This allowed system designers at the end of the 1990s to design a new
system that went far beyond the capabilities of GSM and GPRS. UMTS combines the
properties of the circuit‐switched voice network with the properties of the packet‐
switched data network and offers a multitude of new possibilities compared to the
earlier systems. UMTS was not defined from scratch and reuses a lot of GSM and GPRS.
Therefore, this chapter first gives an overview of the advantages and enhancements of
UMTS compared to its predecessors, which have been described in the previous chap-
ters. After an end‐to‐end system overview, the focus of the chapter moves to the func-
tionality of the UMTS radio access network. New concepts like the Radio Resource
Control (RRC) mechanisms as well as changes in mobility, call control and session
management are also described in detail.
Over the years, the UMTS radio network system has been significantly enhanced and
now offers broadband speeds far beyond the original design. These high‐speed enhance-
ments are referred to as High‐Speed Packet Access (HSPA). An overview of the various
enhancements over time is given in Section 3.1 and a more detailed look at the key
features for broadband Internet access follows in the second part of this chapter. At the
end of the chapter, an analysis is made of the performance of HSPA in deployed net-
works today and of how the functionalities described in this chapter are used in practice.

3.1 Overview, History and Future

The trends and developments seen in fixed‐line networks are also appearing in mobile
networks albeit with a delay of about five years. In fixed networks, the number of people
using the network not only for voice telephony but also to connect to the Internet is
increasing as steadily as the transmission speeds. When the Internet first became popular,
circuit‐switched modems were used to establish a dial‐up connection to the network.
While the first modems that were used in the middle of the 1990s featured speeds of
around 14.4 kbit/s, later models achieved around 50 kbit/s in the downlink (network to
user) direction. Another incredible step forward was made around the year 2002 when

From GSM to LTE-Advanced Pro and 5G: An Introduction to Mobile Networks and Mobile Broadband,
Third Edition. Martin Sauter.
© 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.