Ingrid Van de Voorde

Evolution of the optical access network and the related technical issues

Currently, the developed bi-directional broadband Passive Optical Networks (PONs) have a maximum splitting factor around 32 and a range less than 20 km. Due to the expected switching node consolidation the access network will have to cover a wider range. An access network based on a cascade of PONs is proposed. Optical transmission is supported by the introduction of optical amplifiers, offering the advantage of transparency. In this paper, the technological issues to realize a high split, wide range PON are discussed. Main focus is on the realization of a node amplifying a burst mode signal, and the reliability and upgradeability of such networks.Currently, the developed bi-directional broadband Passive Optical Networks (PONs) have a maximum splitting factor around 32 and a range less than 20 km. Due to the expected switching node consolidation the access network will have to cover a wider range. An access network based on a cascade of PONs is proposed. Optical transmission is supported by the introduction of optical amplifiers, offering the advantage of transparency. In this paper, the technological issues to realize a high split, wide range PON are discussed. Main focus is on the realization of a node amplifying a burst mode signal, and the reliability and upgradeability of such networks.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Upgrading SuperPON: next step for future broadband access networks

An enhanced multistage optically amplified passive optical network (PON) known as SuperPON is presently being investigated by the ACTS-PLANET consortium as a possible future solution for broadband access networks. As it is extremely probable that user bandwidth requirements will continue to increase substantially in the short to medium term it is highly pertinent to consider the upgradeability of SuperPON topologies. In this paper capacity upgrades in the wavelength, space and time domains for both the downstream and upstream directions are discussed with reference to a particular basic SuperPON.

Efficient control of ATM traffic accessing broadband core networks via SuperPONs

Passive Optical Networks offer quite promising results in terms of cost, robustness, flexibility and traffic concentration. The addition of Optical Amplifiers, overcame the optical budget limitations of fully passive first generation technology, enabling the extension of the PONs to up to 15000 subscribers and a 100 km distance, creating the concept of SuperPONs currently at the development stage. The larger round trip delay, as well as the high number of subscribers, coupled with the strict traffic control dictates of ATM, create very complex traffic control and management problems but at the same time open the prospects of high multiplexing gain by aggregating many relatively small connections on a shared feeder. Novel solutions are required since the tree topology and the shared feeder create new problems not encountered in non-distributed multiplexers/concentrators. Methods to resolve the VPI/VCI conflicts on the shared medium, support OAM, ensure privacy and security, police the entry to the system, and the traffic engineering issues, are the focal points of this paper.

Control of upstream optical repeaters for SuperPON access networks

This paper reports on the control systems for upstream optical repeaters in a long range high-split ratio SuperPON access network. Optical amplification means of fast switching semiconductor optical amplifiers is used. Two methods to control the drive current of the optical amplifiers are described: a feed forward self-triggered scheme and a topology using a priori known talker identity information. Trade-offs between both systems will be discussed. The first alternative was used in a lab demonstrator set-up, while the second will be used in a small field trial.

Embedded real time control of optically amplified repeaters in broadband access networks

This paper presents the use of distributed, intelligent control and management in optically amplified repeaters. These optical repeater units (ORUs) are used in an optical access network. A semiconductor optical amplifier (SOA) has been used in the upstream direction because of the possibility of fast switching. The real time control platform consists of both a hard- and a software part. The software control is handled with the embedded control system FORTRESS developed by IMEC.

Evaluation of a superPON demonstrator

The paper presents evaluation results of the SuperPON demonstrator. It shows the feasibility of a passive optical network with increased bit rate (2.5 Gbit/s downstream and 311 Mbit/s upstream), extended range (100 km) and enlarged splitting factor (2048).

A lab demonstration of a SuperPON optical access network

This paper contains experimental results obtained from the ACTS PLANET (Photonic Local Access NETwork) Lab demonstrator, which confirm the technical feasibility of the SuperPON concept. The SuperPON is an optical fibre-based ATM access network which can support a large number of subscriber Optical Network Units (ONUs) up to 2048 and cover a long distance of 100 km.

Fast switching and gain control of optical repeater units for burst mode upstream transmission over super-PONs

This paper presents a fast switching and gain control technique of optical repeated units for burst mode upstream transmission over a Super-PON system by using semiconductor optical amplifiers (SOAs). Measurement results confirm that switching of the SOA can be accomplished within 3 bits at 155.52 Mbps and that the gain control range is more than 10 dB.