Initial deployment of fibre in the local network for narrowband use in Spain: Technology, engineering and cost

This paper covers: (1) the field trials, with fibre in the local network systems, being conducted in Spain and intended for delivery telephone‐based services to residential customers; (2) the technical and functional requirements of these types of system intended for commercial (regular) deployment to be started around late 1993/early 1994, and (3) the most relevant initial deployment scenarios and persubscriber investment aspects. The field trials are located in Madrid and in Barcelona: their rationale, technical characteristics and the lessons learned so far are described. Such trials are providing insight into what requirements and objectives are anticipated to be needed should such new technology be an actual alternative to copper‐based subscriber loops. The requirement for such fibre in the local network systems intended for regular deployment in the near term are indicated, including technical and functional requirements of the optical line terminals (OLTs) (at local exchanges) and optical network units (ONUs) (located near customer premises); transmission requirements and optical distribution network (ODN) requirements and design aspects. For starting regular deployment, three preferred scenarios are identified. The chief parameters affecting persubscriber investments are illustrated including the number of fibres per ONU, and the number of users being served from each ONU. It is shown that in order to achieve cost parity with copper loop (which requires an initial investment of between $600 and $800) a capacity of some 60 narrowband (64 kb/s) channels per ONU should be required.