|Topic:||Access for a converging world|
Eric Presworsky is Zhoneís CTO. Mr Presworsky served previously as Vice President of Advanced Technology and Product Management responsible for the development of Zhoneís Single Line Multi-Service, SLMS, architecture as well as next-generation Zhone product offering. Prior to Zhone, Mr Presworsky served as Assistant Vice President of Carrier Systems Development for Lucent Technologies Internetworking Systems Division – formerly Ascend Communications, Inc. Mr Presworsky also held numerous technical management positions prior to joining Lucent at several leading telecommunications companies, including BellCore and XCOM/Level 3. Mr Presworsky holds a BSc in Communications from SUNY Buffalo and an M.S. in Telecommunications from the University of Colorado at Boulder.
The bandwidth demands of today’s triple- and quad-play driven market far exceed anything imagined a few years ago. High-speed subscriber access networks are the focal point for convergence in the home. They must manage the differing demands of voice, data and video services to provide the quality of service subscribersí demand. Multi-Service Access Nodes, MSAN, classify subscriber traffic and dynamically enforce traffic rules to support serviceperformance demands and provide a path to accommodate new services as they emerge.
Broadband and IP technologies have driven communications, information and entertainment convergence across network and device boundaries. As a result, consumers are quickly gaining greater mobility, flexibility and service personalization. To keep pace with subscribers’ growing network demands, service providers must add – or more efficiently control – bandwidth, support new applications and manage more complex services. In todayís multimedia, high-speed network environment, then, the subscriber access network has become the focal point for service convergence to the home. Services originating on the Internet, from the video head-end and switched-voice network, all come together at the access node. Therefore, managing the access connection intelligently and efficiently plays a pivotal role in delivering the quality of experience, QoE, that todayís subscribers expect. Keeping pace with consumer demand The global availability of broadband powered by IP has ignited an ongoing service revolution. The two technologies have joined forces to enable a world of ondemand, personalized access to converged multimedia communications, information and entertainment services. When the telephone was first commercially introduced more than a century ago, it was meant as a device for emergency communications. Use by the average person to communicate with family, friends and business colleagues wasnít even a gleam in the industryís eye – yet that is where the telephone found its mainstream application. Today, lifestyle continues to drive how people communicate – they access information and entertainment – and has led to the development of new devices, new applications and new portals for services. The majority of communications and entertainment activity takes place in the home. Service providers today face greater challenges in designing and upgrading their subscriber access networks to keep pace with the demands of IP multimedia convergence. When Digital Subscriber Line, DSL, technology emerged a decade ago, broadband access was made universally available as part of the Internet explosion. Delivering up to 8Mbps over the phone line with ADSL was seen as a huge leap forward in high-speed communications. Today, demands for new IPTV and triple-play service are several times greater than this. The IP service revolution and convergence represent both a challenge and an opportunity for the global service provider communityís suppliers of broadband access infrastructure and subscriber products. They must deliver enabling technology that meets the needs of diverse subscriber populations with distinct service needs. In addition to enabling highspeed bandwidth, there is a need for access solutions to serve as a multi-service portal to the residence, one that allows network operators to intelligently and flexibly control subscriber bandwidth usage and service levels so that they can meet or exceed subscriber expectations, reduce churn and continually increase average revenue per user, ARPU. Access, then, is no longer a line concentrator but an intelligent, multi-service access node for broadband multimedia services. Service and lifestyle demands on access The service provider ëtriple-playí has been the big industry buzz for a number of years. Triple-play services are generally those that deliver Internet data, voice, television and movies (video) to the residential customer as a bundled service. Recently, triple play has expanded by operators to quadruple play, which adds a mobile component to the three application services described. Whether itís triple- or quadruple- play services, there are many sub-elements within voice, data or video. For example, voice embraces plain old telephone service, POTS, as well as voice over IP, VoIP. These two voice service types might offer feature options such as caller ID, call waiting, three-way conferencing and so forth. Within data, there is traditional email and file transfer as well as web hosting, music and video downloading, webcam services, peerto- peer gaming and many other innovative services. Within video there is standard and high definition broadcast television, video on demand, and digital video recording, DVR. These services are no longer specific to a TV, PC or phone, and all have unique service characteristics that need to be simultaneously supported by the service provider. The following scenario is not atypical today. One member of the family is relaxing while watching HDTV in the living room. Another is in the family room on the phone placing an order with a TV home shopping network. Their daughter is in her room chatting with friends using the webcam on her PC. Their son is in his room downloading his favourite music video on-line while watching VOD on his TV. This is a picture of true triple- play today – multiple TVs with different programming, multiple online PC activities taking place, and phones all in use simultaneously in a single household. Each family member is using a different service according to their tastes or needs at the moment – the big difference today, is that all their services are from a single supplier over a single network rather than from a cable operator, telephone company and ISP. For the service provider, it means delivering upwards of 25Mbps of bandwidth over its access network and simultaneously handling a dozen or more IP routes and connections. What, then, does this scenario mean to an access vendor? First, and most obvious, is the need for speed, or bandwidth. This family is consuming bandwidth in the range of 25Mbps at once. The access system must support copper-based DSL or fibre connectivity capable of delivering at least this capacity to the residence. Meanwhile, a single access node must serve a number of subscribing households. So the access system must have the bandwidth to meet the cumulative capacity requirements of all the households it serves. Second, the family is concurrently using POTS, VoIP, multicast video, uni-cast video on demand, streaming Internet video, and high-speed data services. The access system must have the IP functionality to support each of these services. For multicast, this means having an Internet Group Management Protocol, IGMP, engine to process channel changes and support the data flows between middleware and set-top boxes. For VoIP, the access system requires calling features specific to the soft switch used by the service provider. On-line data services require Dynamic Host Control Protocol, DHCP, and Point-to-Point Protocol, PPP, functions for each connection. Third, the access system must support not only quality of service, QoS, prioritization and bandwidth management features, it must also be intelligent in order to consistently provide the quality of experience, QoE, – the service experience – subscribers pay for and expect. This requires the system to be not only packetaware but service-aware as well. QoS extends to embrace QoE with Layer 3 and 4 functions that allow each service to be dynamically classified and assigned its own level of priority and queuing. Based on classification, appropriate traffic control and flow control, functions are applied on a per-service or per-subscriber-line basis. For example, service providers can guarantee a specified bandwidth to a particular application or limit bandwidth use of a certain protocol to a certain percentage of overall bandwidth. In this way, each subscriber service reliably performs as promised without intruding on other subscribersí bandwidth. This setting of ërulesí based on service awareness assures the predictable availability and quality of the aggregated service bundle. Some services such as broadcast and ondemand video, require high-bandwidth, constant bit rate packet delivery. Others, such as voice, are buffer-sensitive. Then, too, data can comprise short and bursty traffic flows. As such, each service requires service awareness and rules to reliably enforce each serviceís performance requirements for bandwidth, latency, jitter and so forth. Subscribers expect constant, fair and high-quality service without compromise. It is a newsworthy phenomenon that consumers will stand in line overnight to get the new Vista operating system or to purchase a US$600 iPhone. This behaviour reflects how much technology has shaped lifestyles and how dependent the general population has become on communications, information and entertainment services. With IP driving service convergence, as well as the convergence of fixed and wireless networks, the general population is gaining the ability to communicate, access information and tap entertainment services from nearly anywhere. Nearly all homes in the world are wired. The supporting infrastructure represents a huge long-term investment by service providers. Likewise, the home is still the primary place families enjoy their entertainment, go online, and use the phone. The subscriber access network, then, is the platform that connects subscribers to a mix of high-bandwidth services. The volume and complexity of multimedia triple and quadruple-play services require intelligent IP service control at the subscriberís first point of access, where bandwidth is delivered and where services from the PSTN, Internet and provider networkís head end all converge. Access vendors supply this control to service providers through Multi-Service Access Nodes, MSAN, which classifies subscriber traffic and dynamically enforces traffic rules to support todayís service-performance demands and to provide a scalable path to accommodate new services as they emerge. Access vendors therefore need to create an intelligent MSAN IP access system that lets network operators offer access to a mix of converged services with all the corresponding network parameters required for a solid subscriber QoE. Because network requirements and services vary from country to country, access platforms should be designed with the flexibility to adapt to the individual needs of each service provider. Cultural, lifestyle and service diversity means there is no such thing as one-platform-fits-all. A service provider in Egypt or Norway can deliver the same high QoE as a rural telco in the US across a range of services.