Implementation of NGN/IMS Technologies into Legacy Network Infrastructures

Issues concerning implementation of Next Generation Network/IP Multimedia Subsystem (NGN/IMS) technologies into existing networks to develop a unified network infrastructure to support new services and applications are considered in this paper. In fact, legacy circuit-switched (CS) networks like Public Switched Telephone Network (PSTN) or Public Land Mobile Networks (PLMN) are oriented mainly to support narrowband voice services and have to be modernized using innovative technologies to extend a set of offered services. NGN/IMS-based technologies can enable operators of such networks to modify network infrastructures to provide an access for users to a large diversity of services to keep their market share. It will allow also reducing CapEx and OpEx using a unified IP backbone and the open IMS platform. Since implementation of the NGN/IMS technologies in the existing infrastructures represents an extremely complex process, a decomposition of the whole process into some parallel subprocesses (innovation lines) is proposed for incremental deployment of the unified full IP integrated multi-service network infrastructure on a basis of yet existing ones. The milestones of the decomposition are described in detail in the paper.