Home EuropeEurope I 2007 The road towards convergence

The road towards convergence

by david.nunes
Lin Cheng
Frank Toupin
Issue:Europe I 2007
Article no.:19
Topic:The road towards convergence
Author:Lin Cheng and Frank Toupin
Title:(Lin Cheng) President of Western Europe, and (Frank Toupin) Director of WE Product Marketing
PDF size:548KB

About author

Lin Cheng is ZTE’s President of Western Europe. Prior to joining ZTE, Lin Cheng served as the CEO of Ferma China/Spheris Telecom – a developer of value-added service platforms for telecom operators – as the Director of North Asia Department and Managing Director of SAT Beijing as well as a Vice President and Member of the Board of SAT-Linkton and of SAT Guangzhou. He also worked for Satelcom International, a business communication system manufacturer, as Marketing Manager for Asia-Pacific. Lin Cheng began his career in China working for Thomson – CGR as a project manager. Lin Cheng graduated from the French National Telecom Engineering School (Paris) and earned a Master’s degree from Paris VI University on Artificial Intelligence.

Frank Toupin is the Director of WE Product Marketing Department for ZTE. Before joining ZTE, he worked on HSDPA/HSUPA as a Product Marketing Manager. Mr Toupin worked previously for Nortel as a Product Line Manager and for France Telecom as an International Corporate Program Manager. He began his career at the Technical Headquarter of Bouygues Telecom in charge of the GSM Radio Infrastructure. Mr Toupin has long been involved in conferences and publications in Europe and Asia. Frank Toupin graduated in Engineering from Ecole Nationale Supérieure des Télécommunications, France, and worked on the Erbium Doped Fibre Amplifier at Queen’s University, Canada.

Article abstract

IMS, the IP Multimedia Subsystem, is the key to fixed-mobile convergence for operators, especially those merging existing legacy networks. IMS, an open industry standard for voice and multimedia communications on IP networks, helps operators implement services like VoIP, video applications, etc. It facilitates billing and generally helps operators implement advanced IP-based systems. Notwithstanding its relative ease of use, migrating to IMS is still a complex process; despite the need, only 30 per cent of Europe’s operators have begun to use it.

Full Article

Reshaping the industry with IP Despite the number of conferences, forums and articles dealing with convergence, we sometimes feel lost by the different drivers and meanings of convergence. Converging towards what? Is it so good to converge in a world relying on diversity? We should remember that nature, which follows the entropic rule, ‘every system will naturally evolve to a state with the higher amount of disorder…’, dislikes the convergence trend. Basically, convergence is the key to the unavoidable evolution of telecommunication networks towards a unified, all IP, network offering personalized and converging services. This evolution will happen – is happening. There is no doubt about this because the ubiquity of broadband and IP is radically changing the business model for operators. Indeed the all-IP trend is pushing intelligence to the edge of the network and the wide use of Voice over IP, VoIP, is cannibalizing telephony revenues, at a time when the incredible increase of the mobile penetration is slowing down in the heavily saturated market. Consequently, operators have to reduce significantly their operational costs, struggle to retain their customer database and look for new ways to generate revenues. Of course, depending on the operators, each of these tactics has a different priority! In addition, if we need proof that the worlds of IT and telecom are becoming ever more intimate, the migration towards IMS is all the evidence we need. IMS/FMC (IP Multimedia Subsystem/fixed-mobile convergence) is about rethinking the network and IMS/FMC is everywhere. Consumers, corporations, network operators, service providers all look to IMS/FMC as the response to their needs. IMS is an open industry standard for voice and multimedia communications on IP networks. It helps operators implement new services on their networks like Voice over IP, VoIP, Push-To-Talk, PTT, Push-To-View, among others, facilitates billing and helps operators develop systems that take full advantage of the functionality of today’s advanced terminals. Each operator has different needs with IMS. Fixed operators need to change their business model quickly; access providers must now become service providers. For those operators, IMS brings more intelligence to the network, enables greater control of enhanced services by blending voice, data, video, TV, etc. For mobile operators, IMS is particularly advantageous given the number of new services – especially converged services – it facilitates. If the operator is only planning to offer a few new services, IMS is unlikely to be more cost effective, given the investment involved, than a proprietary solution. Note that out of 59 mobile operators in Europe, only 18 have announced contracts or trials with IMS. The best candidates for IMS are the integrated operators having both fixed and mobile networks since the standardized architecture for FMC uses IMS. For those operators, the equation is simple – IMS brings cost reduction and generates new revenue. Convergence of services will develop the usage thanks to seamless access (SMS, MMS, video) and convergence of network will reduce OPEX, Operational Expenditure. IMS – the path to convergence IMS, the IP Multimedia Subsystem, is basically a signalling network based on SIP and Diameter technologies. IMS simplifies the way the network is seen and dealt with; it uses only three network layers – transport, core and services. Basically, IMS was designed to provide robust multimedia services across network boundaries using diverse access technologies. IMS technology provides ways to merge fixed and mobile networks. IMS provides powerful tools to deal with service control, quality of service, QoS, charging for multimedia sessions and the integration of diverse services. IMS also provides a way to add ‘personalisation’ to communications. For instance, although a terminal might be ‘always on’, with IMS users can be given the means to manage – depending on their device and access – how they can be reached, or not, and by whom. IMS frees up the application layer from the network and makes it easy to develop new services and applications. Today, services are typically developed ‘vertically’ – each service is a self-contained system. Thanks to IMS, the traditional vertical, silo-like service delivery mechanism can make use of a horizontal, shared-service delivery platform. As far as customer access is concerned, IMS allows for pragmatic fixed mobile convergence by enabling centralized service control and management. IMS provides a standardised, open, architectural framework for development. It has evolved into a stable and easy to implement tool. International standardisation groups – ETSI TISPAN and the ITU-T – are using the same IMS core for different access technologies, which makes the IMS core a real convergent architecture suitable for use with different access networks. IMS-based convergent networks The following figure shows the functional entities in the IMS-based convergence architecture, as well as the convergent function entities that can be used in different access networks, such as the P/I/S-CSCF and HSS application servers. Basically, the IMS nervous system is a signalling network using SIP and Diameter protocols. SIP is used for multimedia session setup and maintenance, while Diameter is used for the authentication, authorization, and accounting, AAA, of user services. A full description of this complex functional architecture might discourage readers, so we will only detail some of the key elements of the IMS-based Fixed Mobile Convergence Architecture. These functions are paving the road towards convergence. – For signalling, the P-CSCF, Proxy Call State Control Function, is the first contact point in the IMS Core. S-CSCF is the heart of the IMS Network; it performs session control and registration services for home subscribers. – AGCF, Access Gateway Control Function, supports legacy fixed analogical terminals through a PSTN (public switched telephone network) Emulation Subsystem via an access media gateway complementing P-CSCF support of IP Multimedia terminals. AGCF has the same functionality as P-CSCF in IMS. – HSS, Home Subscriber Subsystem, is a Diameter server, which stores subscribers’ profiles, registration and service logic information. Subscriber data stored in the HSS is the key enabler for service mobility across different types of access networks and controls user roaming between different network operators. – MGCF, Media Gateway Control Function, is used for inter-working with legacy telecommunication networks, such as PSTN, PLMN, etc. – IM-MGW, IP Multimedia Gateway, handles both switched circuit network channels and media streams from a packet network (e.g. RTP streams in an IP network). – RACS, Resource and Admission Control Subsystem, focuses on access networks and the interconnection point between the access network and the core network. The major functions of RACS consist of policy control, resource reservation, admission control and border service control, such as NAT control. – NASS, Network Attachment Subsystem, provides registration at the access level, and initialization of user equipment for accessing NGN, next generation network, services. It handles dynamic provision of IP addresses and other user equipment configuration parameters, user authentication, access authorization, access network configuration based upon user profiles and location management. – PDF, Policy Decision Function, provides policy control and resource control; it has evolved into PCRF to support charging policy. Regarding the service architecture, IMS standard defines three types of application servers: SIP AS, OSA/Parlay AS, and traditional mobile intelligent network. The OSA/Parlay service platform is an open service architecture, providing Parlay API/Parlay X API interfaces. Third parties create service applications by invoking an API, an application program interface. SIP AS refers to an interactive application server that interacts with the core network via SIP, the Session Initiation Protocol. One or more service logics run in this application server, also called a service engine. Traditional mobile intelligent network is an architectural solution that makes IMS networks compatible with legacy intelligent services. Flexible and diversified open interfaces allow third party application access to a variety of content and services. Integrated service management platforms not only manage value-added services, but also manage the charging of third-party services and helps operators improve their service maintenance and management capabilities. One of the key advantages of IMS is its ability to charge multimedia sessions appropriately. IMS does not mandate any particular business model; it lets operators charge whatever they think appropriate. IMS provides information about the service invoked by the user, applies traditional time-based charging, and can apply QoS-based charges, or handle any new type of charging. – Online charging in an IMS-based network is performed by the Online Charging System; it interacts with IMS network functions such as the Application Server, MRFC and, in some cases, S-CSCF. – Offline charging in IMS-based network is done by the Billing System. China – the coming IMS market A seamless migration of existing services to IMS and NGN is vital. Despite the substantial business and technological benefits, migration to IMS has been a challenge for European operators. Indeed, there is a huge gap between the ideal IMS-based fixed-mobile network convergence and the state of European networks with their mix of several different generations of platforms. In China, operators are facing fewer constraints than European operators, since they do not have such a long history and so many legacy platforms to deal with. That is why China is the region to watch when dealing with IMS. IM-based fixed-mobile convergence systems have already been deployed in several Chinese provinces. Focusing on fixed-mobile convergence, IMS provides a graceful solution by aligning the fixed and mobile road maps. Leading pan-European operators have started testing activity, working with their suppliers, planning for fixed mobile convergence over the next two years. There are two strategies for the migration from the traditional legacy network to the all-IP network. One is a rapid replacement where changeover to the new IP network is implemented as quickly as the operator can manage. The other is called the ‘cap & grow’ strategy. The cap & grow strategy calls for a step-by-step migration to a full IMS architecture. No matter which strategy is chosen, there are secure and competitive solutions that will enable migration to a converged network via IMS.

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