Optical technology pioneers


Sweden Focus

How has Sweden, with its compact population of nine million, managed to punch above its weight in the optical communications arena for so long?

By Bjorn Olsson General Manager of Transmission & Transport Networks, Ericsson

The number of successful fibre-optic companies in Sweden is disproportionally large compared to many European countries. This can be traced back to the early 1980s when proactive links between corporations and academic institutions - and the government's support of high-tech industries with a progressive funding policy - established Sweden as a hotbed of optical research.

Aided by funding from the Swedish Board of Technical Development, Ericsson opened its first optical labs, co-operating with universities in Gothenburg and Stockholm to develop fibre technology, new optical devices and materials, and high-speed transmission solutions.

Other achievements included Ericsson-led research into multi-wavelength transmission networks (MWTN) - part of the EU's RACE program - at Ericsson's Fibre Optics Research Centre, and the Stockholm Gigabit test-bed in the early 1990s. The peak came when MWTN was awarded the prize for the best EU research program in 1996.

A shifting axis
Although the focus of much optical research shifted to North America in the 1990s - driven by the Internet and data explosions, and the need to develop long-distance transmission solutions suited to the geography - Sweden is still home to many successful optical companies. But, today, business issues rather than technology drivers are at the forefront of innovation.

With the technology "bubble" largely deflated, the need for network operators to address cost issues is crucial. At Ericsson, we believe the long-term solution is a converged, multi-service network in which the distinction between fixed and mobile is gone - and which delivers the infrastructure synergies that operators need to survive. Optical techniques play a key role in this vision, as does IP.

To date, IP hasn't penetrated the optical domain, but this will change very soon. Our vision is an all-IP-over-glass network, integrating IP control functionality deep into the optical domain. Innovative network elements such as GMPLS technology, optical cross-connects and optical edge-multiplexers enable this vision of an intelligent optical network.

Currently taking centre stage is a new set of revised SDH standards. Aiming to enhance the data capabilities of networks largely built on SDH and ATM - with the addition of IP and later MPLS - a new set of ITU standards has emerged that takes the best of these ideas and standardises them as "Next Generation SDH". These give a level of data efficiency and dynamic bandwidth previously unavailable in the voice-oriented SDH hierarchy. Further, all the revenue-oriented voice services are still supported, giving SDH a multi-service, fast-provisioning voice and data capability.

The first mile "bottleneck"
Until the broadband capabilities of access networks can catch up with the DWDM-enabled capacity glut in transmission networks, the market demand needed to drive the next wave of development is unlikely to happen. As pilot projects in Sweden have shown, optical technologies are ideal for bridging this gap.

A good example is the joint venture between Ericsson and a local residential property company in Hudiksvall, Sweden (see LWE April, page 24). This is based on the concept of a "broadband island" - a localised access network delivering services from a limited number of providers with local presence. The aim has been to achieve a high-capacity broadband network offering fixed, symmetrical, high-speed multi-service access suitable for home entertainment, small businesses, home-based working, schools and hospitals.

The expense of building optical access networks has historically been a substantial hurdle. A basic requirement is to make the cost of fibre comparable to a traditional CAT5 copper network. In Hudiksvall this was achieved using Ribbonet, a complete air-blown system developed by Ericsson, which both reduces cost and speeds up installation.

But just as important as building the physical network is the choice of a transmission solution. We believe Ethernet - which offers a low-cost, ubiquitous and data-oriented solution for both residential and enterprise customers - is an ideal solution. Furthermore, being equally at home on copper or fibre, Ethernet enables a smooth migration from existing systems to an all-glass infrastructure.

Pragmatism is key to building for the future
The pendulum is swinging back from high-capacity optical transmission to low-cost electronics. Voice-over-IP has not significantly managed to penetrate into the classic telephony market, and voice and data systems are still largely separate. However, the multi-service network remains the best solution, with a pragmatic aggregation onto existing SDH networks. Many "boom" ideas are proving economically unfeasible, but next-generation SDH - incorporating standardised versions of many of these ideas - is emerging as the front-runner with its new data-oriented and dynamic-bandwidth features. Moreover, it also affords more opportunities for a smooth, cost-effective evolution from legacy networks, increasingly seen as a vital strategy to build a cost-effective next-generation network.

Bjorn Olsson

General Manager of Transmission & Transport Networks

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