Next generation networks




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5Features of NGN


This section introduces key features of NGN based on ITU-T Recommendations including services, architectures and capabilities aspects of NGN.

5.1NGN definition and characteristics


ITU-T identified a definition of the NGN through ITU-T Recommendation Y.2001 as following: “A packet-based network able to provide telecommunication services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It enables unfettered access for users to networks and to competing service providers and/or services of their choice. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.”

NGN definition clearly indicated that the NGN should be a packet-based network over the broadband infrastructures (both over fixed and mobile) with separation between service and transport. Because of these given nature of the NGN, fundamental characteristics of the NGN are summarized as following by the ITU-T Recommendation Y.2001:



  • packet-based transfer;

  • separation of control functions among bearer capabilities, call/session, and application/ service;

  • decoupling of service provision from transport, and provision of open interfaces;

  • support for a wide range of services, applications and mechanisms based on service building blocks (including real time/ streaming/ non-real time and multimedia services);

  • broadband capabilities with end-to-end QoS;

  • interworking with legacy networks via open interfaces;

  • generalized mobility;

  • unfettered access by users to different service providers;

  • a variety of identification schemes;

  • unified service characteristics for the same service as perceived by the user;

  • converged services between fixed/mobile;

  • independence of service-related functions from underlying transport technologies;

  • support of multiple last mile technologies, and;

  • compliant with all regulatory requirements, for example concerning emergency communications, security, privacy, lawful interception, etc.

Looking at the definition and characteristics of the NGN, high level features of the NGN are summarized following and these should be a framework to use of the NGN:

  • Open architecture: open to support service creation, service updating, and incorporation of service logic provision by third parties and also support "Distributed control" as well as enhanced security and protection;

  • Independent provisioning: service provision process should be separated from network operation by using distributed, open control mechanism to promote competition, and;

  • Multiplicity: The NGN functional architecture shall offer the configuration flexibility needed to support multiple access technologies.

5.2NGN Requirements


Various aspects of requirements for the NGN have been identified following the characteristics of the NGN. Most significant points of characteristics having great impacts to the NGN requirements are followings:

  • “decoupling of service provision from transport” which means separation of service functions from the underline transport functions;

  • “packet-based transfer but support for a wide range of services, applications and mechanisms based on service building blocks (including real time/streaming/non-real time and multimedia services)” which means providing integrated services using packet based transport means;

  • “broadband capabilities with end-to-end QoS” which requires support of QoS from one end to other end;

  • “generalized mobility and converged services between fixed and mobile” which available services crossover the of fixed and/or mobile access environments in any directions.

To realize such key characteristics of the NGN as well as covering other aspects, ITU-T identified “Requirements of the NGN” and announced as a Recommendation Y.2201 (1st developed at 2007 and revised at 2009). This Recommendation Y.2201 identified many of views of requirements but summarized mainly in three areas such as transport related, capability related and service related, as followings:

  • Requirements for the NGN transport related:

    • ITU-T Recommendation Y.2201 specified to use of IP protocol as a mandatory transport technology for the NGN supporting for general, ubiquitous and global public connectivity. However Y.2201 recommends the IP protocol may be carried over various underlying transport technologies in the access and core portions of the transport stratum (e.g., xDSL, ATM, MPLS, frame relay, OTN) according to the operator's environment. Through this, NGN equipped with capabilities to support separation of service functions from the underline transport functions;

    • NGN transport provides various modes of connectivity and communication: use of IPv4 and IPv6, one-one/one-many/many-many/many-one, real-time/non-real time etc.

    • Especially Y.2201 identified “Network attachments” into the NGN transport as a mandatory to support registration at the access network level, initialization of end-user functions for accessing the NGN services and management of the access network IP address space, including a NAT (Network Address Translation) function. In this case, the user profile is required to keep user access authentication data and information related to the required network access configuration.

  • Requirements for the NGN capabilities related: various capabilities are required to support of the NGN and summarized their requirements as followings:

    • QoS: ITU-T Recommendation Y.2201 mandated of the NGN to support end-to-end QoS across different networks of varying infrastructure technologies provided by multiple operators to ensure the required service level for users or applications. ITU-T Recommendation Y.2201 identified the NGN also support multiple levels of QoS, which may be negotiable between the user and provider and/or between providers;

    • Security: NGN has been mandated to support the security features incorporated in existing networks and allow for secure interconnection with other NGNs or non-NGN networks based on the application of ITU-T Recommendation X.805 to the NGN and thus address the following dimensions of the NGN security: access control, authentication, non-repudiation, data confidentiality, communication security, data integrity, availability and privacy;

    • Mobility management: ITU-T Recommendation Y.2201 identified two distinct types of mobility are supported by the NGN:
      1) personal mobility exists where users can use registration mechanisms to associate themselves with a terminal that the NGN can associate with the user. NGN will be used interfaces where between users and terminals, and users and networks for user registration exist
      2) terminal mobility exists within and among networks where registration mechanisms are used to associate the terminal to the NGN. Where support for terminal mobility with service continuity exists, such support is expected to also be used for the NGN;

    • Management capabilities: ITU-T Recommendation Y.2201 identified the high-level goal of the NGN provide survivable and cost-effective networks supporting the planning, installation, operations, administration, maintenance, provisioning of networks and provisioning of services. Thus the NGN management capabilities support the monitoring and control of the NGN services and transport components via the communication of management information across interfaces between the NGN components and management systems, between the NGN supportive management systems, and between the NGN components and personnel of service and network providers;

    • Other capabilities: ITU-T recommendation Y.2201 identified other relevant capabilities of the NGN to support features and characteristics, covering “Routing”, “Identification”, “NNA(Naming, Numbering and Addressing)”, “Accounting and Charging”, “OAM (Operation, Administration and Maintenance) and others (see ITU-T Recommendation Y.2201 for details).

  • Requirements for the NGN services related:

    • Open Service Environment (OSE): NGN has been mandated to enable new capabilities and support a wide range of emerging services, including services with advanced and complex functionalities supporting third-party application and service providers to develop new applications and capabilities accessible via open and standard interfaces, furthermore, software reusability and portability, and use of commercial software, are recommended to be supported to facilitate cost effective development;

    • Media handling and content management: NGN has been mandated to support various media resources and media resource management capabilities to enable a wide range of applications, including media recording/down-loading/streaming/duplication/insertion, playing recorded media, speech recognition and others. NGN is recommended to provide content management capabilities to manage various and huge content resources, taking into account classifications of contents such as enterprise content (e.g., business documents), web services content (e.g., HTML files, images) and IPTV services content (e.g., relatively large-size stream data);

    • Service specific requirements: ITU-T Recommendation Y.2201 identified requirements by considering specific types of services such as PSTN/ISDN emulation, multimedia real-time conversational services, IPTV services, enterprise services, Tag-based identification services, managed delivery services, visual surveillance services, ubiquitous sensor network services, multimedia communication center services and VPNs (Virtual Private Networks);

    • Public interest aspects: Specific requirements for public interest aspects are also identified covering lawful interception, malicious communication identification, emergency telecommunication, network/service provider selection, user with disabilities, number portability, service unbundling and others.



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