Research Of UMTS Core Network Structure And Solution For PSCN

3G Systems are intended to provide a global mobility with wide range of services including telephony, paging, messaging, Internet and broadband data. International Telecommunication Union (ITU) started the process of defining the standard for third generation systems, referred to as International Mobile Telecommunications 2000 (IMT-2000). In Europe European Telecommunications Standards Institute (ETSI) was responsible of UMTS standardisation process. In 1998 Third Generation Partnership Project (3GPP) was formed to continue the technical specification work. 3GPP has five main UMTS standardisation areas: Radio Access Network, Core Network, Terminals, Services and System Aspects and GERAN. The Core Network is divided in circuit switched and packet switched domains. Packet switched domains is mainly beared by IP, which provides access and transmit for Internet, video and multi-media service.The whole paper introduces UMTS packet switching core network system structure, analyses and compares the interface protocols and signaling procedures in the core network. At the end of paper, author provided a PSCN final solution for a certain operator after field trial analysis.The paper begins from the general structure of UMTS network. A UMTS network consists of three interacting domains: Core Network (CN), UMTS Terrestrial Radio Access Network (UTRAN) and User Equipment (UE). The main function of the core network is to provide switching, routing and transit for user traffic. Core network also contains the databases and network control functions. Nowadays the bearer of Core Network trends to IP.The paper introduces the structure, network elements and interface protocol stacks of PS Core Network. There are three kinds of interfaces in PS Core Network: Iu-PS over ATM, Gn and Gi over IP, and SS7 interfaces over TDM. The paper analyses the features of these interfaces.The paper also analyses PSCN and related signaling. The core network provides radio part mobility and session management by RANAP, encapsulates user data and control messages between GSNs by GTP, and exchange MAP&CAP messages with SS7 signaling network. All of these analysis and comparation will provide basis for the network design.The paper mainly emphasizes a PSCN solution which we provided for a certain CNC operator. The paper analyse the ISP's existing network. According to the commands and expection of operator, we provide a 3 steps' solution after the related criterions were complied with, and experience was refered. At the same time, the paper includes the methods of network elements configuration, service model analysis and interface bandwidth calculation. Accouding to long-term's experience, author brought forward the emphases and difficulties of PSCN building, and presented relevant solution. All of these methods could be applied in real business environment.The end part is the conclusion of the whole paper and finally describes the expectation of UMTS PSCN future developing.