The standardization of passive optical networks capable of transporting Ethernet frames at gigabit-per-second speeds, currently in progress in both ITU-T and IEEE, constitutes a major milestone toward cost-effective photonization of the last (aka first) mile. The article presents an Ethernet gigabit PON (GPON) system aligned with the philosophy of the evolving FSAN (full service access network) ITU-T specification, which focuses on the efficient support of any level of quality of service. The intelligence of this system, in terms of traffic quality guarantees, lies in the MAC protocol, which controls the distributed multiplexing/concentration function by allocating variable length slots to every user of the shared upstream (toward the network) medium. The way transport of information is organized in an ITU-T GPON system and the operation of a MAC protocol that preserves all QoS guarantees are presented and evaluated.

Efficient transport of packets with QoS in an FSAN-aligned GPON

Both broadcast CATV and switched telephony access networks have evolved, over decades, to deliver their respective services efficiently. But these networks are not necessarily optimal for services that are rapidly emerging. This suggests that the access infrastructure will likely change in the future, driven by demands for new services and the costs of providing them. Will fiber optic networks play an important role? Trade-offs in desirable network properties (low initial costs, high capacity, flexible provisioning, enhanced maintenance and operations, etc.) are strongly influenced by the network architecture. We classify architectures on two characteristics: delivery mode (i.e., broadcast vs. switched) and carrier utilization (i.e., shared vs. dedicated), examining the trade-offs these imply with several examples of existing and proposed architectures. We show that optical networks can, by virtue of recent component development, be reconfigured to change their characteristics without changing the outside plant.

Local access optical networks

The arrival of asynchronous transfer mode (ATM) networks has enabled a wide range of new interactive multimedia applications for the residential market. The article presents a vision for supporting universal residential broadband services based on an ATM-to-the-home (ATTH) network architecture. This network architecture applies to the various residential access network (RAN) architectures being deployed today, such as hybrid fiber/coax (HFC), fiber-to-the-curb (FTTC), fiber-to-the-home (FTTH), and asymmetric digital subscriber loop (ADSL) technologies. The article addresses today's residential networks and applications, to understand why a switched broadband residential network is required to support residential broadband services. After exploring residential broadband application requirements, a new class of service is proposed to support a very important class of residential broadband applications that has been not addressed. Then, the technical and strategic motivations for using the ATTH architecture are discussed in detail. A universal model for residential broadband network architecture based on ATTH is described, which is shown to apply to various RAN architectures. Finally, it discusses the signaling requirements of residential broadband services and explain why the ATM multiconnection per-call model is much more efficient than the digital stored media command and control (DSM-CC) session control protocol approach for the ATTH architecture. >

A vision for residential broadband services: ATM-to-the-home

Chapter 13 – A Survey of Fiber Optics in Local Access Architectures

Time division multiple access (TDMA) multiplexing of ATM cells from thousands of residential customers toward the common feeder of a passive optical network (SuperPON) tree obviates the need for an equal number of optical line terminations (OLTs). All upstream transmissions converge by means of the passive splitters/combiners to just one OLT unit which serves all by time sharing. The ability to reach such a high splitting ratio became possible by the development of bursty mode optical amplifiers (OAs). In addition, OAs make possible a 100-km-long feeder which can bypass the local exchange into the first core switch, bringing further savings to both initial and running costs. These techniques allow SuperPONs to lower the access cost per customer, holding for the promise of ushering into domestic local loops the photonics revolution which has already transformed the transmission plant. These savings, however, can only be realized under the assumption that the system can accept high loading before exceeding the limits of quality of service (QoS) requirements and without distorting the egress traffic in a way that jeopardizes the statistical estimates on which ATM connection acceptance was based. Solutions to the problem of traffic arbitration, respecting the idiosyncrasies of each traffic class and suitable for fast implementation, are offered.

TDMA multiplexing of ATM cells in a residential access SuperPON

The unification of eastern and western Germany confronted Deutsche Telekom (DT) virtually overnight with what is probably the greatest challenge in the history of telecommunications in Germany: to bring the telecommunications networks in eastern Germany out of the technological stone age and up to the standard of a western industrialized country with state-of-the-art technology and services as quickly as possible. DT must optimize the integration of the various generations of technical systems into all areas of the telecommunications network and develop strategies for launching products and services to rapidly achieve advantages in productivity. Because of the interaction of growing process and product innovation and the resulting synergy, this will rapidly improve the performance of the network and lead to reduced costs in years to come. This article gives an overview of the general conditions under which DT is implementing fiber-in-the-loop (FITL) and describes the technology used. It also presents DT's complementary strategy for the use of SDH technology in the access area. >

W. Weippert

Papers

The evolution of the access network in Germany