Norway`s Telenor approves wdm system
By EDWARD HARROFF
Telenor AS, Norway`s public telecommunications operator, has approved wavelength-division multiplexing (wdm) equipment from dsc Communications, Plano, TX, following extensive testing of the system in a 520-km (323-mi) link. The system includes 4-channel operation, common spare-channel functionality, and a network-management system.
The pilot program involved a 1-channel wdm link operating between Oslo and Bergen, one of the major Norwegian oil cities and the country`s former capital. The network included six inline amplifiers designed for a nominal repeater span of 22 dB as well as integrated management of the wdm and Synchronous Digital Hierarchy (sdh) equipment. This link was installed in July 1997 and was tested extensively in August.
dsc has been one of the key suppliers of sdh transmission equipment to Telenor since 1994. That contract included adm-1, adm-4, and adm-16 equipment, digital crossconnects, and an integrated nationwide network management system. With the rapid evolution of wdm technology, it became clear that wdm could become a very attractive enhancement to traditional sdh long-distance capacity in Telenor`s network. However, for historical and demographic reasons, this wdm system had to fulfill a number of strict requirements.
Telenor`s service challenge is to provide geographic coverage to a country that is at the same time one of Europe`s longest (1243 mi) and the continent`s least-populated (4.4 million people). Norway`s population density is 35 people per sq mi; this contrasts with Europe`s most populated country, the Netherlands, which has 968 people per sq mi. Hence, one of Telenor`s key network planning criteria is to manage initial wdm investment carefully, as Norway`s future long-distance traffic growth pattern is difficult to project in a newly deregulated market.
Telenor`s wdm system had to be cost-effective while operating over very long transmission spans (up to 800 km, or 500 mi) and initially carrying a relatively low capacity (one to four wdm channels). Low-capacity wdm systems may seem somewhat contradictory. However, if low-capacity wdm solutions can be implemented at a cost more or less equivalent to the cost of traditional sdh solutions, the low-capacity wdm infrastructure will provide a very attractive foundation on which to build capacity to meet the anticipated ever-increasing bandwidth demands.
Telenor`s wdm project was supported by dsc`s center of excellence for sdh optical transmission systems, based in Copenhagen. According to Peter Vierick, dsc technical director, to fit cost-effectively into Telenor`s sdh infra-structure, the wdm systems had to be integrated with the existing repeater hut infrastructure, the existing sdh terminals, and Telenor`s existing nationwide network-management system.
"Telenor AS is always aiming to utilize the latest available technology in order to be the most competitive operator in the market," according to Sverre Bjoennes, project manager at Telenor Nett AS, the planning and installation subsidiary of Telenor. "We expect to install [additional] wdm equipment in our network very soon."
The wdm system is part of a general infrastructure upgrade for Telenor, which is probably better known internationally for its extensive satellite network. The company has been preparing for telecommunications deregulation this year and has fully digitized the Norwegian telephone network--one of the first countries in the world to do so. As Telenor deputy chief executive Ole Petter Hakonsen points out, these infra-structure investments permitted the company`s business and private customers to reduce phone bills by nok 9 billion (US$1.4 billion) from 1990 to 1997. This represents a price reduction of approximately 50%, making Norway`s telephone service one of the least expensive in Europe.
"The digitalization of all Norwegian telephone exchanges offers users an array of new services. The most common services are call transfers, call waiting, voice mail, paging, and wake-up calls. The digital exchanges have also enabled the launching of the Integrated Services Digital Network (isdn), an all-in-one network tailor-made for multimedia services. isdn-services are now available to 90% of private customers, and there are about 60,000 private subscribers to isdn services," explains Hakonsen.
wdm in Europe
According to John Ryan, a principal at the market research and consulting firm of Ryan, Hankin, Kent Inc., San Francisco, CA, wdm technology has been around for seven years, but has started to catch fire with the arrival of dense wdm (four channels or more). At the beginning of 1997, all of the four largest U.S. long-distance companies were using dense wdm in their networks. In Europe, Telefonica de Espana and BT are now trialing wdm systems, and France Telecom is accelerating its experiments on optical networks. Despite wdm`s obvious strengths in boosting network capacity, carriers must manage potential technology problems such as the limitations of currently installed fiber, transponder upgrade cost, and network management issues. q
Edward Harroff writes from Bellevue, Switzerland.