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Next Generation Networks NGN
BACKGROUND OF NGN
Over the last years, developments in telecommunication technologies, bringing possibilities for rich context communications with multimedia content, has satisfied most of users' demands about always on, rich-content communication ways with high degree of versatility (conferencing, application interactivity). On commercial level, all these new features have been integrated within the 3G UMTS, a technology which only recently has started being gradually adopted. 3GPP, the standardization body working on UMTS technology definition has so far not only described services categories, but defined consistently ways for delivering them with appropriate Quality of Service (QoS).
Despite the emergence of new fixed and wireless communication technologies, like the WiFi, WiMAX and xDSL, with high bandwidth rates and seamless conformity to the IP, the capability of the new UMTS technology to delivery its services in a “measurable” way and with user-defined QoS has been identified as the main reason for the success of the new multimedia applications on the market. Wishing to further exploit users arisen awareness about new multimedia communication services and expand possibilities for new profits in the new fixed and wireless network domains, the industry of communications has set a new target, that of creating “ubiquity” in service delivery along with “seamlessness” in keeping steady the “user experience” in terms of service tariffing and QoS satisfaction. Answers to these problems has come to give the Next Generation Networks (NGN) technology, a new initiative created collectively by ITU, ETSI and 3GPP that aims at delivering all these new communication features on a “network agnostic” or otherwise called “heterogeneous networks” communication environment, where the only discriminating factors for service provisioning will be the user himself, his selected service types and the desired QoS. In this respect, the NGN technology shall not only provide a single solution for various network types integration, but must answer globally, on behalf of all communication technologies it embraces (fixed, mobile, wireless), the problems expressed earlier about providing service “ubiquity” and “seamlessness”, dealing with issues such as, zero service disruption for moving, roaming, handover users and QoS guarantee among different technology networks with diverse QoS capabilities. Over the past few years, evolution of the NGN concept along these lines has led to the definition of the first version of a “network agnostic” communication technology, the IP Multimedia Subsystem (IMS). IMS has become today the main focal point of research efforts and is considered today as the enabler of the future 4G, converged communication technology.
the Next Generation Network (NGN) is defined as a packet-based
network, able to provide telecommunication services over a multitude of broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. Main driver of this concept is the requirement for enabling unfettered access for users to networks and to enable competition of service providers, which must offer their services with generalized mobility, allowing consistent and ubiquitous provision to users.
The final aim of NGN is to render service providers of any type, including those providing Internet services, voice and multimedia content providers to deliver their services to end users in a network and terminal agnostic way, using any device connected to any access network. In other words, service providers have now the chance of becoming decoupled from the network infrastructure, which is now conceived as a “homogenized” heterogeneous platform and thus make use of access and core transport network infrastructure in a liberated way with the only aim to deliver their services to end users with the desirable QoS. Combining all these principles, Next generation networks have finally identified as network collection
emerging the following common characteristics (Figure 1):
· convergence of various data communication types over the IP, i.e. data,
· fixed, wireless and mobile network convergence,
· access to a common set of services that can be provided over multiple access
network types (ADSL, UTRAN, WiFi, WiMAX, etc) with features like user
handover and roaming.
· IP-based core transport networks,
· possibility for using any terminal type (PC, PDA, mobile telephone, set-top
· seamless terminal, user and personal mobility,
· user-driven service creation environments,
· common set of services, admission policies, authentication type, always possible network accessibility regardless of the user connection type to the network.
(Introduction to four Layers of NGN)
Architecture of NGN
− NGN adopts the hierarchical architecture
− Divided into four layers
§ Edge Access Layer
§ Core Switch Layer
§ Network Control Layer
§ Service Management Layer.
− Based on standard protocols and packet switching network.
NGN Edge Access Layer (First layer )
Bottom most layer of the NGN solution and consists of
− Multiservices Access Network(MSAN)
- POTS telephones
− Universal Media Gateway (UMG)
§ Trunk media gateway
§ Mobile network gateway etc.
− Signaling Gateway (SG)
− Multiservices Access Network (MSAN)
§ The end terminals attached are
- POTS telephones
- xDSL modems for high speed internet services
- PABX's connected to MSAN network on PRI/R2
− Universal Media Gateway (UMG)
§ Supports both narrowband and packet switching functions with multiple access interfaces.
§ The packet switching provides IP interface to implement service traffic process and conversion between IP/TDM networks, which implements efficiently the inter-working between different networks.
§ Performs the functions of
- large-scale Trunk Media Gateway (TMG)
- Mobile network gateway etc.
− Signaling Gateway
§ Independent signaling gateway to fulfill the inter-working between PSTN network and NGN
§ Provides built-in STP function.
NGN Core Switching Layer (Second Layer)
− Above Access layer lies the IP core metro layer and IP Core Network layer.
− UMGs , AMGs or AGs etc. from multiple sites will be terminating and converging to their respective IP Metro Core Network Layer
− IP Metro Core Network Layer connected to its respective point of convergence with IP Core Network layer to interconnect various Class 5 /Class 4 and other NGN elements
NGN Network Control Layer (Third Layer)
− The control layer is the main switching layer of the network where all the Class 5/ Class 4 Soft switches lies
− It provide switching and signaling facility between different elements of the network like MSAN's , UMGs , SHLR , IN etc.
− Soft switch
§ Soft switch is deployed in the control layer of NGN.
§ Offers an integrated solution for both fixed and mobile network
§ Soft switch ensures the 6H features of the equipment
- High availability
- High reliability
- High real-time
- High scalability
- High load balance
- High compliance to open system.
§ Huawei Soft switch Softx3000 supports upto 2 million subscribers (at maximum ) , with the processing capability up to16M BHCA.
§ Soft switch
§ It acts as a generic Call Controller in the packet-switched network, supports the interworking between PSTN, H.323, SIP, and MGCP domains.
§ Soft Switch normally provides H.248 and MGCP based bearer control.
§ Interworks with other NGN components through the open network adopting distributed standard protocols.
NGN Service Management Layer (Fourth Layer)
− It is the top most layer
− This layer is responsible for all service elements and different elements of the network like SHLR, IN Platform etc.
− The NMS also lies at this layer and provide complete
§ Monitoring of the network.
− iManager (integrated Network Management System) - NMS
§ It uses standard protocol to manage all devices in NGN
§ Supports end-to-end service management
§ Provides detailed device operation information.
§ Service configuration (IAD dispatching and trunk configuration ) is performed
§ Supports network fault relativity analysis through alarms.
§ Used to get real-time network performance information.
− Multimedia Resources Server (MRS)
§ MRS provides medium resource to packet network.
− Smart Home Location Register (SHLR)
§ The SHLR is used in the public switched telephone network (PSTN) and NGN.
§ The SHLR provides the following functions:
− Managing the subscriber data.
− In SHLR, it can translate the Logical number into the Physical number to implement the NP service.
§ In the NGN, the SHLR communicates with the Softswitch through the extended MAP protocol
NGN technology internals
Multimedia over Internet protocol services are available over the Internet today. These services aretypically offered by deploying a server that manages the session establishment between two end-points. The media flows are routed directly between the end user terminals with protocols like RTP/RTCP, RSVP and IGMP used for routing and synchronizing the media streams.
In NGN networks, real-time conversational (e.g. video-telephony/conferencing) and non-conversational (e.g. video-on demand, instant messaging) multimedia services will play a prominent role in their success on the market. Therefore it is important that the security, customer experience and QoS perceived by paying users is much greater than that of free Internet services.
To satisfy those requirements NGN funding members have devised two main mechanisms, one for providing control over the user sessions and a second one for enforcing the QoS settings of the user across the end-to-end communication path.
The first mechanism (Figure 2) has been realized using the SIP protocol, through which the user can be identified, authenticated and charged by the network on the basis of a single user identity (IMS Personal Identity-IMPI). Using the SIP protocol, the user may communicate to the network information about the user he wishes to connect (called party), the service-of-choice as well as the quality settings.
On the other side, the NGN network exploits the information of the calling party in order to implement a) registration/ authentication of the user on the network, b) find the path to the called party and c) enforce the QoS settings across the established path. Particularly for the latter procedure, the NGN network foresees a set of mechanisms dedicated to translating the user-requested QoS settings to values compatible with the capabilities of the various network technologies being involved in the establishment of the end-to-end path.