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This paper describes how an experimental full services access network has been constructed at BT Labs and presents views on how its performance could be improved to meet the reliability and traffic loading requirements expected in real applications such as fiber to the business and fiber to the cabinet. The experimental network included: asynchronous transfer mode (ATM) switch, an ATM passive optical network (PON), very high speed digital subscriber loop (VDSL) customer drop and ATM forum 25 Mbit/s customer network. The design and realization of the VDSL customer drop, the signaling system and the interfaces between the system elements formed a major part of the design and construction work at BT Labs. The ability to cope with varying service demand and achieving the necessary quality of service are important requirements for roll-out systems. This paper describes how these requirements could be met in the design of future proprietary equipment.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In upgrading the access network to be broadband capable, re- use of existing infrastructure is essential to manage the risk associated with this development. FTTCab (fiber to the cabinet) has been proposed as an architecture that can make this development economic to provide 12 Mbit/s to the customer and 2 Mbit/s back into the network. The FTTCab architecture uses an optical fiber overlay to an active node sited at the primary cross-connect point (PCP) in the copper access network. Frequency multiplexing allows the copper pair infrastructure to be re-used without changing the existing narrowband services. FTTCab is at the mid-point of a range of access topologies with respect to the siting of the DSL (digital subscriber loop) technology. The DSL modem can be sited at the home, curb, cabinet, or in the exchange to suit a range of distance/capacity requirements. This enables a simple revolution of the current network to FTTCab, and allows the architecture to be flexed to satisfy particular business needs.

The future widescale deployment of broadband multiservice networks is dependent on an acceptable commercial relationship being achieved between new service revenues, operating cost savings and the network capital investment required. A new generation of broadband access networks is envisaged which is capable of both broadband and narrowband transmission, and can provide both broadcast and interactive services over a much larger coverage area than copper pair yet makes good use of existing copper pair infrastructure. To ensure that such networks emerge practically and are economically viable, requirements must be agreed and a wide market established. The aims of this paper are to draw attention to the benefits of networks with broadband and narrowband capability, to discuss the benefits of co- operation on requirements and to describe what has so far been achieved in the standards bodies.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper reports on the investigation of the traffic throughput performance of passive optical networks using both time division multiplexing (TDM) and asynchronous transfer mode (ATM) transmission techniques. In particular discrete event computer simulation techniques are utilized to study the performance of these networks under asymmetric traffic loading conditions. The performance characteristics obtained demonstrate the degradation of the network traffic throughput using TDM, whereas ATM transmission proves resilient to even high levels of asymmetric traffic loading on the passive optical network.

An investigation is made into the options for digital video distribution in the LAN or local network environment with a view to providing two-way interactive video services for each customer on the network. Limitations of present access protocols and topologies are discussed and possible ways around these limitations are presented.© (1987) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.