Bahaa Moukadam is the Vice-President for IP Telephony at Spirent Communications. Mr Moukadam has more than 18 years’ experience in the communications test and measurement industry. He has held positions in design engineering, product marketing, marketing, business development, and executive management at Hewlett Packard (now Agilent), Wandel & Goltermann Technologies (now Acterna), and Telex Computer Products. Mr Moukadam has written industry articles for internal publications and has spoken at several industry events. He holds a Master’s Degree from the University of Kansas and a Bachelor’s Degree in Engineering from the University of Missouri.
IP Multimedia Subsystem, IMS, a standardised network architecture, facilitates convergence between all sorts of fixed and mobile, wired and wireless networks by providing seamless handovers between these dissimilar networks. VoIP/SIP, WiFi, WiMAX and cable all come within the scope of IMS. IMS offers carriers an easier evolutionary path to newer network technologies and easier adoption of new applications. Still, since all of the IMS protocols have yet to be standardised, its adoption may, at times, be somewhat troublesome.
IP Multimedia Subsystem, IMS, promises to become a standard architectural framework for the rollout and development of converged communications services. As the providers of these services face a global industry shakedown, IMS finds itself sitting squarely at the core of the next wave of technological network transformation. The industry faces declining revenues from traditional services, mergers and acquisitions, complexity driven by network convergence, and an increased focus on the commercial realities that go with it. The benefits that IMS promises are greatly needed. An Internet Protocol-based, IP-based, infrastructure will bring significant changes to the business models of service providers worldwide. In a market where service rollout, management and reliability are under increased scrutiny, IP technology can answer many questions. Against a backdrop of saturated customer bases and squeezed margins, convergence will permit cheaper access to services and an explosion in the variety of revenue-generating services. Nevertheless, the networks need to be ready. IMS can help ensure that IP can properly underpin the converged infrastructure. It guarantees - in theory at least - a seamless experience and handover between fixed-line, cable, mobile and wireless access. Created in early 2005, the goal of IMS was to enable telephone portability across fixed-line and mobile handsets. Since then, it has grown in scope to incorporate VoIP-based enterprise networks, WiFi/ WiMAX and cable. IMS is a series of protocols and interface specifications that facilitate standards-based fixed/mobile, voice/data and voice/video convergence. Dozens of specifications influence IMS architecture - not all of which are yet standards. IMS is in the midst of its own complex evolution, and the ambiguity caused by constantly changing protocols hampers the congruent development and implementation of communications services. Network innovation continues to create opportunities for carriers, and IMS equipment is moving up on the telecommunications shopping list. With US$21.6 billion in expected spending on next-generation voice and IMS equipment by 2009, the forecast is for phenomenal growth. The opportunities From the end user’s point of view, the advantages of IMS enabled services are clear. Identity portability across mobile and fixed-line networks, centralised voicemail and messaging, and converged services such as virus protection and file storage make up a compelling raft of new features and services. The ubiquitous availability of the user’s personal environment at the office, in the home and on the road allows for an enhanced user experience and higher productivity in our increasingly nomadic society. For service providers, network convergence via IMS provides a significant opportunity for increasing the average revenue per user, ARPU. At the same time, it allows them to reduce their operational expenses by having a single, converged, IP-based network. Not knowing which services will get significant traction with users, the ability to deploy chargeable services quickly gives service providers an environment of rapid market-based experimentation. Services that are embraced by users can be scaled quickly, maximising revenues. For network equipment and handset manufacturers, network convergence presents an unprecedented opportunity for a new wave of network and handset upgrade cycles. The transition to an all IP network will be characterised by a series of intermediate steps over many years. Manufacturers that are able to anticipate and execute in alignment with both the technical and business challenges of carriers are likely to reap significant rewards from these upcoming upgrade cycles. Due to the scale and complexity of this transformation, many manufacturers will be able to benefit only through partnering and consolidation. The challenges IMS introduces a host of challenges to equipment manufacturers and service providers. IMS is at the intersection of multiple, concurrently occurring convergence trends and is much more challenging than previous network evolutions. These trends include convergence from VoIP and PSTN, public switched telephone network, to IP Telephony, Triple Play services convergence and fixed/mobile convergence. The inherent complexity of IMS - its maze of standards, interfaces and protocols - could be a stumbling block for many service providers and carriers migrating to an IMS-based network. The draft standards from numerous independent organisations could result in a level of uncertainty and hesitation for some service providers until the standardisation process is clarified. Implementing IMS is far from simple. Prototyping and predicting the effects of IMS traffic on production networks will be difficult to manage. The complex interoperability requirements, such as handshaking, media conversion and synchronisation will all have to be resolved whilst guaranteeing quality of service. As a result, it is essential for operators to develop a deep technical understanding of the underlying technologies. It will become obvious that interoperability testing, performance and scalability assessment, quality of experience, QoE, and service management are necessary for successful deployment of IMS-based networks. Carriers are likely to struggle with organisational and domain expertise issues in the short term. Since IMS by definition crosses both the wireline and the wireless domains, carriers will have to figure out how to make cross-domain and cross-organisational decisions. Once compartmentalised by technology, equipment and vendor selection, network architecture, service offerings, rollout strategies and service management approaches will all be inter-related by IMS. Some carriers will find it necessary to re-draw organisational lines while keeping their current wireline and wireless networks and businesses operating smoothly - a big challenge, to say the least. Simulation and testing Faced with upgrading network equipment to IMS standards, carriers and service providers will face a new challenge - developing testing processes and methodologies to ensure interoperability, scalability, security and fault tolerance. While network equipment manufacturers begin to create systems to handle IMS protocols correctly, carriers will need to ensure the systems themselves are configured properly and provide consistent, integrated, services. Carriers and service providers - and their systems integrators - will not be able to simply plug IMS compatible equipment into their networks. Ambiguity in the IMS specifications will almost certainly guarantee that the equipment will need considerable testing and tuning before deployment, during early trials and ongoing service management. New equipment being developed by network equipment manufacturers will support a number of different fixed and wireless protocols such as SIP, DIAMETER, H.248, IPv6, and the like. Network equipment, too - including routers/switches, cable head ends, gateways, session border controllers, softswitches, DSLAMs, PBXs and end points - will all need to accommodate these protocols. Add to these the protocols necessary for 3G networks, the IMS-specific XML Configuration Access Protocol, the Message Session Relay Protocol, plus the payload protocols for VoIP, Internet and multimedia traffic, and you have a serious testing challenge. For example, with an edge router that handles session management for Flash movies, comprehensive testing is required to maintain proper throughput and quality. Service prototyping helps discover where network problems could occur and how each affects the total service delivery. Simply testing for proper infrastructure operation, while mandatory, is not sufficient. Rigorous testing is essential to ensure that multimedia applications, including voice and video, provide the QoE expected by users. During the initial phase of an IMS implementation, test equipment placed at selected end-points, in the field, across the network, provide ongoing fault reports. Because IMS is intended to be access-independent, the work of data conversion often falls to the carrier’s infrastructure. Testing ensures the delivery of correctly formatted data to the end point. Working towards return Successful IMS deployments are dependent on rigorous testing of all parts of the network infrastructure and the QoE. The pressure will be on service providers to keep up with the pace of change. The set of protocols and interfaces that define IMS are still evolving. The IMS set of standards is far more complex than anything the communications sector has had to adopt before, so it brings with it new challenges in network management. With the lucrative enhanced services it makes possible, however, IMS is moving into the spotlight as a new way to boost ARPU and ensure carriers get the most from their investments in IP. As customers begin to expect better quality and more exciting services - such as video on mobile phones - IMS will allow service providers to ensure that the investment they are making now is fully future-proofed. With the right testing during deployment and ongoing monitoring and service management, IMS is set to revolutionise IP services from within.