Integrated broadband access

In recent years, the customer access network has witnessed a rapid development of new transport technologies. Especially, the development of Passive Optical Networks and High speed Digital Subscriber Loop technologies may have a large impact, as they provide cost effective means for gradual introduction of new services in the access network. At the same time, a series of new services and applications are maturing. Computer and consumer industry have discovered multimedia (eg. CD-1). Video distribution services are evolving to fully interactive Video On Demand (VOD, dial tone video) capabilities. These applications need a bandwidth of at least 1.5 Mbit/s. The precise bandwidth requirements are, however, yet unknown. Both multimedia terminals and VOD set-top units will be available and low cost in the short future. For the transport of these video related service, the operator has basically the choice between twisted pair, coax, fiber and radio based access networks, or any combination of the rn. Most access networks today are largely copper based, but fiber is gradually being introduced to cope with the increasing bandwidth demands. In this paper, an access network is described that is capable of mixing these different transport media at different bit rates, using a common multiplexing / concentration scheme. Therefore, it can easily adapt to the multitude of local access topologies cun-ently in use. At the same time, it provides the necessary bandwidth flexibility to support the new services in an efficient way. The system is called Integrated Broadband Access (IBA), as it provides a common access platform for all services, narrowband and broadband, and as it offers the possibility to combine the differrent transmission techniques in a common access architecture. The proposed solution is an extension of the APON system, an ATM based FITL system, as presented in Verbiest et al (1). In the first section, the generic functionality of today's access networks are discussed. Then the overall characteristics of the proposed (IBA are discussed, with the emphasis on the multiplexing functionality and the bandwidth flexibility. Single stage and multiple stage multiplexers are discussed. Finally, a number of applications are discussed, and conclusions are drawn.