The future of modern mobile communications

UMTS - Introduction

This chapter provides an overview of the GSM/UMTS core network, as specified by the 3GPP release 99 standards. There is still no strict formal definition of the core network, but the position of the core network for the purpose of this chapter and how it relates to other parts of the PLMN (Public Land Mobile Network) and co-operating networks.

Originally decided by the ETSI SMG, the 3GPP release 99, the UMTS core network standard is evolved from the earlier GSM standards releases. The core network forms the central part of a PLMN and accommodates important functions for intra and inter PLMN roaming, the provision of IP-connectivity and internet access, ISDN services and interworking with other networks.

The core network may be looked upon as consisting of two different parts :

• Managing Circuit Switched mode communication services. (ISDN type services)
• Managing Packet Switched mode communication services. (GPRS type services)

Although logically very different the two parts share certain core network functionality, such as the HLR, Auc, EIR etc, and may also run over a common transport infrastructure.