461h International Symposium Electronics in Marine, ELMAR-2004, 1818 June zyxwvu 2004. Zadar. Croatia zyxw MIGRATION SCENARIOS AND CONVERGENCE PROCESSES TOWARDS NGN (PRESENT STATE AND FUTURE TRENDS) zyxw Pavol Podhradsky Slovak University of Technology, Department of Telecommunications IlkoviEova 3, 812 19 Bratislava, podhrad@ktl.elf.stuba.sk Abstract: zyxwvutsrq The conception of the converged networks and NGN from the dqferent points of view is presented zyxwvut in the paper. The possible migration scenarios of telecommunication networks (PSEWN) and data networks are shortly described. Using the Functional NGN model the distributed conception and physical architecture (including the individual physical entities) of the NGN is described. There are several problems they have to be solve to support the processes of the development and implementation of the converged networks and NGN in the ICT infrastructure. Some of these problems @rotocol platforms, standardization activities) are specified and shortly described. The process of the development and iniplementation of the converged networks and NGN services is the specific problem. The future evolution trends of the NGN are also delineated. Key words: converged networks, next generation networks, NGN architecture, protocols, multimedia services. 1. INTRODUCTION The process of convergence has to be seen from various points of views. The convergence trends are concerned with various levels on which convergence could be realized in the fiame of communication networks. At the beginning it is necessary to define the following expressions: convergence, integration and intenvorking of networks. No doubt that these expressions have a lot in common but still are not the same. Convergence is a process of approaching of two functionally different networks on several reference model layers in order to create one reference architecture. The process of integration is when one network overtakes a part of processes based on the reference model and provides them also over the second network. In this way the second network is integrated in the reference architecture of the first network. The intenvorking is the cooperation of the different types of networks without changing the existing network infrastructure and network components of the given networks. Converged networks should enable interconnection and cooperation of various types of ICT networks while keeping the features necessary for the transmission of various types of media. Two views on the convergence process result from this definition [l]: 1. Convergence of various types of data which are transmitted (voice, audio, video, text or multimedia. Each type of media has different requirements on the transmission channel: (transmission rate, delay, error rate, etc.). That is why there are several categories of services for which defined parameters of the network have to be kept (e.g. QoS) 39