Next generation networks




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Дата канвертавання25.04.2016
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Summary


Many of developing countries faced to improve their telecommunication infrastructures which are based on telephone service oriented, that is, PSTN/ISDN. Providing enhanced services such as Internet is one of the reasons but already passed life cycle of systems used in legacy networks, especially circuit switching systems is being critical issue for all countries who used.

NGN is being developed to provide various advanced services including convergence which available over fixed and/or mobile broadband environments. But NGN should cover, at least, essential services which are provided in the legacy networks, typical example should be “Voice” service. Because of this, NGN is being considered as a new telecommunication infrastructure to be considered as a replacement for (or migration of) legacy networks, especially for PSTN/ISDN.

The most fundamental change driven by the NGN should be the simplification of the telecommunications architecture with two strata “Transport strata and Service strata” which allow services available independently with underline transport technologies. This is the most important point what NGN is different with legacy but public telecommunications networks. In addition, this simple architecture of NGN extends its capability to support various multimedia services over both fixed and mobile accesses which are crucial for Fixed-Mobile Convergence (FMC).

Migration from legacy networks to NGN is not a simple task because it has a lot of impacts. Especially it deals with infrastructures so impacts are really huge and serious. Thus it is required enough understanding the features of NGN and careful considerations on differences with legacy networks. Such differences of architectures, key technologies and services which are used to implement for legacy networks and NGN raised various important issues for migration.

This Technical Paper provides comprehensive knowledge about the legacy networks and NGN including analysis of differences between them. This Technical Paper introduces key features of legacy networks and NGN based on ITU-T Recommendations. Based on this, this hand book analyzes “Gaps” between legacy networks and NGN in terms of services, architectures and technologies used in each networks. Those “Gaps” would be used for identify different migration scenarios from legacy networks to NGN. In addition, this Technical Paper addresses various issues to be considered for the developing countries when initiate migration project and also for choosing specific types of scenarios.

Introduction


Next generation networks (NGNs) is the 1st full IP-based public telecommunications networks developed by ITU-T coordinated with various SDOs (standards development organizations) such as ATIS, ETSI, TIA and 3GPP/3GPP2. NGN provides various changes to the telecommunications as consequences by technical features and characteristics of IP.

The most fundamental change driven by the NGN should be the simplification of the legacy telecommunications architecture which has been based on OSI (Open System Interconnection) seven layered model in general. NGN simplifies architecture with two strata “Transport strata and Service strata” which allow services available independently with underline transport technologies. This is the most important point what NGN is different with legacy but public telecommunications networks such as PSTN (Public Switched Telephone Network), PSDN (Packet Switched Data Network) and ISDN (Integrated Services Digital Network). In addition, this simple architecture of NGN extends its capability to support various multimedia services over both fixed and mobile accesses which are crucial for Fixed-Mobile Convergence (FMC). Therefore NGN has many capabilities to support of various services which are available over different legacy networks. NGN provides such services over single NGN platform while each different legacy network only supports specific services (e.g., voice over PSTN and data over PSDN).

NGN is being developed to provide various advanced services including convergence which available over fixed and/or mobile broadband environments. But NGN should cover, at least, essential services which are provided in the legacy networks, typical example should be “Voice” service. Because of this, NGN is being considered as a new telecommunication infrastructure to be considered as a replacement for (or migration of) legacy networks.

Migration from legacy networks to NGN is not a simple task because it has a lot of impacts. Especially it deals with infrastructures so impacts are really huge and serious. Thus it is required enough understanding the features of NGN and careful considerations on differences with legacy networks. For this purpose, this Technical Paper starts with analysis of features about legacy networks (e.g., PSTN, PSDN and ISDN) and NGN in terms of services, architectures and technologies identified by various ITU-T recommendations. Then this Technical Paper identifies gaps between legacy networks and NGN based on such study about those differences. Afterwards, NGN capabilities for supporting migration of legacy networks have been introduced following the relevant scenarios. Many of issues to be considered when design migration of networks such as user needs, policy and regulation including business environments are also explained. Finally this Technical Paper provides recommendation of using different scenarios.


1Scope


This Technical Paper introduces key features of legacy networks and NGN based on ITU-T Recommendations. Based on this, this Technical Paper analyses “Gaps” between legacy networks and NGN in terms of services, architectures and technologies used in each networks. Those “Gaps” would be used for identifying different types of migration scenarios from legacy networks to NGN. This Technical Paper covers analysis of various NGN capabilities helping for migration of legacy networks into NGN. In addition, this Technical Paper addresses various issues to be considered for the developing countries when initiate migration project and also for choosing specific types of scenarios, for example, status of legacy networks and their business environments including relevant systems. Further considerations impacts for choosing migration scenarios such as user needs, policy and regulation environments of the country are also introduced.
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