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Building an end-to-end architecture that supports fixed mobile convergence

Posted: 08 Sep 2005 ?? ?Print Version ?Bookmark and Share

Keywords:fixed mobile convergence? fmc? agere systems? ericsson?

In addition to making converged user services faster and easier to introduce, common shared resources increase operational network efficiency. The network evolution path is unique for each operator and depends on many factors, including the business environment, cultural heritage, regulations, end-user behavior and PC and mobile penetration rates. The transformation is usually done step-by-step towards the target network with an all-IP solution based on IMS.

Next-gen networks

The term next generation network (NGN) has been used by the telecom industry to denote networks that will offer telecom-grade voice services using packet-switching transport technology such as ATM or IP. Furthermore, the call control function is separated from the switching function. The packet switching transport can be present in either the core network or both the core and access network, i.e., the user will receive VoATM or VoIP service.

For this reason, TISPAN was formed to define the NGN framework, and, in particular, to provide a multi-service, multi-protocol, multi-access, IP-based network. This network is designed to be secure, reliable and trusted. It is also designed to be enable service providers to offer real-time and non-real time communication services between peers or in client-server mode. These services include mobility/portablity/nomadic use of devices users' personalized communication services at any place and using any type of terminal.

The standard is being planned with three releases:

- Release 1 addresses nomadicity and user-controlled roaming based on use of an access network attachment subsystem and DSL/WLAN access methods.

- Release 2 optimizes resource usage according to user subscription profile and service use.

- Release 3 introduces full nomadicity and high-bandwidth access methods such as VDSL, FTTH and WiMAX.

End-to-end network architecture

The end-to-end network architecture shown in Figure 2 shows various access networks, both radio-based (GSM, CDMA, WLAN and WCDMA) and DSL-based. The connectivity layer contains nodes such as:

- SGSN and GGSN for the UMTS network

- PDSN for the CDMA network

- Media Gateways (MGW) for PSTN interconnection

- Session Border Gateways (SBGs) for NAT

- Firewall traversal of SIP flows for:

a) the DSL-based network (A-SBG)

b) mobile networks (M-SBG)

c) other network peering (N-SBG)

As far as the control layer is concerned, IMS control is shown with associated elements as well as with interworking to a softswitch solution. Finally, a policy control engine for the fixed DSL-based broadband is shown.

Figure 2: End-to-end network architecture

A fundamental issue for the end-to-end network architecture is traffic management and, in particular, how QoS is supported on a end-to-end basis and across different access networks. IP core network mechanisms such as Diffserv/Intserv, MPLS and policy-based networking need to interwork with QoS mechanisms specified in a 3GPP/3GPP2 radio access network (RAN), a WLAN or a WiMAX network.

Network processors play a vital role in accomplishing this interworking function in a flexible and future-proof way, as opposed to customized ASIC design, which is often expensive in a world of continuously evolving standards.

Services convergence

Convergence of services and applications implies that the same service can be accessed from different types of terminals, for example sending messages from a mobile user to a PC, or browsing the Internet from a handheld mobile phone, or different types of networks, including cable TV, mobile or fixed.

As mentioned earlier, IMS, the standardized solution for SIP-based applications for multiple access network types, is a key component for delivering converged services with telecom-grade quality of service. IMS makes it possible to increase network efficiency and catalyzes the faster and simpler introduction of new services. The common service execution environment of IMS supports user applications available over multiple access types (access-aware service platforms). There will be one common user- and services-management function, a common charging system, and a common identification/ authorization system.

Presence enables a paradigm shift in person-to-person communication, and is a key component for many IMS-based services. Presence-aware communication allows users to see recipients' information before connecting with them (e.g. availability, geographical position). Presence enables the user to see possible communication alternatives based on device and network capabilities. Presence information will be available from any device (mobile, PC etc.).

The majority of communication sessions using converged services, such as voice calls, video calls, chat sessions, file transfers, on-line games and white board sessions, are typically initiated via the active phonebook. The active phone book is one application that uses the presence information from IMS.

Device convergence

Device evolution can be seen as a mirror of the core and access network evolution. It is in the device that new applications are made available and where identification and security mechanisms are implemented. Therefore, it is also where access capabilities need to exist. Another possible functionality for mobile device convergence, in the short/medium term, is adding support for UMA.

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