Saturday, July 3, 2010
The Universal Mobile Telecommunications System (UMTS) is a third generation (3G) mobile communications system that provides a range of broadband services to the world of wireless and mobile communications. This chapter presents an overview of the UMTS
architecture specified by the Third Generation Partnership Project (3GPP), focusing on the
network elements relevant to the study presented here. The evolution towards an All-IP network, within the 3GPP, is occurring in several steps, known as releases [6, 7]. Earlier UMTS specifications, with a relatively strong retention of the current 2nd generation networks, were still switch centric. However, the introduction of a new IP platform, when fully specified, will provide the UMTS system with multiple wireless access options and full IP packet support.
The first version of the UMTS Specification, 3GPP Release 99, defines a system which
adopts much of the functionalities of the GSM/GPRS core network and introduces a new
wireless access technology, namely wideband code division multiple access (WCDMA).
This access technology increases the 2G systems capacity to higher data rates enabling the
support of advanced services. 3GPP Release 4, further optimizes the air interface, although
the major changes are targeted at the core network circuit switched domain, still present in
order to maintain full coverage for second-generation services. These changes result in the
separation of user data flows and their control systems into different physical entities, the
Mobile-services Switching Centre (MSC) and the Media Gateway (MGW) respectively.
Finally Release 5/6 provides a migration from conventional Circuit-Switched speech
services served by CS domain to enhanced IP-based services using a Packet-Switched domain.