Lanny Starkes Smoot

A passive photonic loop architecture employing wavelength-division multiplexing

The authors present a fiber subscriber-loop architecture that uses multichannel wavelength-division multiplexing (WDM) to eliminate outside-plant electronics while providing each subscriber with dedicated channels to and from the central office. The approach has a number of attractive features, such as reduced maintenance requirements at remote sites in the loop plant and enhanced flexibility in the provisioning of services. The authors report an experimental demonstration of the architecture utilizing LEDs (light-emitting diodes) and low-cost receivers for narrowband ISDN (integrated services digital network) transmission and DFB (distributed feedback) laser for broadband transmission (up to 1.2 Gb/s).<<ETX>>

A packet video/audio system using the asynchronous transfer mode technique

A description is given of a prototype point-to-point packet transmission system which integrates a fixed-bit-rate PCM coded NTS quality video signal and two multiplexed audio channels for broadband integrated services digital network (B-ISDN) service. The system contains an assembler interface card at the transmit end and a disassembler interface card at the receive end. At the assembler interface card, service equipment is connected in a daisy-chained architecture. Information is integrated into a SONET-like asynchronous transfer mode (ATM) data stream. At the disassembler interface card incoming information is broadcast to each piece of receive service equipment. Only information addressed to the equipment is filtered out. Service clock information which is not carried by the network is recovered by the receive equipment using a digital phase-locked loop. The framing, deframing and multiplexing of services were facilitated by using Bellcores custom-designed CMOS Framer chips. This system provides a broadband service multiplexer and demultiplexer capable of integrating high-bandwidth services such as full motion video, and lower bit-rate services (e.g. audio) using a uniform system structure. The ATM technique as well as the cell headers used in this prototype are also discussed. >

Design of a SONET/ATM-based optical customer premises network

A novel optical customer premises network (CPN), H-Bus, has been designed to interface future B-ISDN (broadband integrated services digital network) signals and distribute available bandwidth to terminal equipment connected to the CPN. Key features of this network are the use of optical fiber as transmission medium, and a hybrid architecture, namely a broadcast bus for the downstream traffic (network interface to subscriber terminal to network interface). The physical layer of the network makes use of the synchronous optical network (SONET) transmission format. The user information is carried using the asynchronous transfer mode (ATM) technique. The reliability of H-Bus is improved through the use of a new optical element to protect the CPN in the case of terminal failures. To resolve any access contention on the upstream bus, a new media-access control protocol has been designed to effectively achieve fairness.<<ETX>>