Realization of the Next-Generation Network
Chae-Sub Lee, Chairman, FGNGN, ETRI Dick Knight, Vice Chairman, FGNGN, BT
This article provides some insight into the history, definition, requirements, and future trends of next-generation network standards. It concentrates on a high-level overview to provide a strategic direction of standards toward a complete NGNproviding fixed-mobile convergence, telebroadcasting, and all aspects of 21st century communications.
The last 10 years or more have seen an increasingly fast integration of computers and telephony, both equipment and networks. Traditional public network operators (PNOs) have seen a decrease in telephony traffic on their public switched telecommunications networks (PSTNs), due in partto the increasing popularity of mobile telephones and the movement of services from telephone networks to the public Internet. Telephone network customers’ demands have moved away from the all-embracing “one-stop shop” for communications provided by their network provider, preferring the unregulated but huge content and communications possibilities offered by the public Internet. The so-called“fixed” network operators’ response has been to meet that demand by deploying broadband. While this solution satisfies the customer demands, it has done little to ensure the continued development of global communications networks, as the network operator is left merely providing access to the public Internet (or worse, access to an Internet service provider, ISP) while content and services areprovided without any association with networking costs. Customers buy services and not technology, so it is the ability to offer services that can take advantage of broadband which is important from the network operators’ point of view. The concept of a new, integrated broadband network has developed over the last few years and has been labeled next-generation network (NGN). The basic characteristics ofan NGN can be determined from the problems faced by the network operators: the need to provide services
over broadband accesses (to increase revenue); the need to merge diverse network services, such as data (Web browsing), voice, telephony, multimedia, and emerging “popular” Internet services such as instant messaging and presence and broadcast type services; and the desire of customers to beable to access their services from anywhere (inherent mobility). Rather than a network to provide a specific solution (e.g., the PSTN), what was needed for the 21st century was a series of networks that could support a flexible platform for service delivery. One of the most important features of IP is the independence of protocol layers (upper or lower). This feature has greatly impacted globalconnectivity networks, which provide connections independent of any kind of sublayer networks such as PSTN, asynchronous transfer mode (ATM), and frame relay. Broadband access, such as asymmetrical digital subscriber line (ADSL), has enabled global connectivity coupled with various online applications, making a huge impact and creating a kind of online global village. An NGN therefore aims tocombine the best of both worlds from the PSTN and the Internet.
REQUIREMENTS FOR A NEXT-GENERATION NETWORK
An NGN has been discussed in standards since at least 2003, and the commonest question asked has been “What is an NGN?” The commercial needs, as outlined in the introduction of this article, provided the starting point in determining the requirements to answer the question. InternationalTelecommunication Union — Telecommunication Standardization Sector (ITU-T) Study Group 13 defined an NGN in Recommendation Y.2001  as “A packet-based network able to provide telecommunication services and able to make use of multiple broadband, QoS-enabled transport technologies, and in which service-related functions are independent from underlying transport-related technologies. It enables...