Fibre Access Networks

Written on 2:29 PM by ooe

Demand for bandwidth is the key driver for fibre in the access network. Fibre has served the large bandwidth needs of long-haul networks for 20 years. Businesses or buildings, which can concentrate many users' traffic onto a fibre, have also been directly connected. The fibre access systems used have much in common with core transmission techniques such as PDH or SDH and are configured as point-to-point or ring networks. Corporate access customers have traffic concentrations, security and reliability requirements similar to core networks.

The big challenge is to solve the problem of the mass-market with the ultimate goal of fibre to the home (FTTH). Much of the technology needed has been around since the mid-1980s, but until now FTTH has been achieved only in technology trials or small-scale deployments. For FTTH to become ubiquitous, costs need to fall to be comparable with alternatives such as twisted pair or hybrid fibre-coax. Three important costs are the technology, installation and ownership. For FTTH to succeed these costs must be lower than the expected income from services over the life of the system.

Green field (new-build) is a key problem area, which gives a focus to the problem of FTTH. The cost of providing any fixed access network is very high when the civil works are included. New homes will incur these costs anyway so the issue is whether to deploy twisted pair, coaxial cable or fibre, or a mixture of all three.

Fibre promises capacity far in excess of the alternatives and offers future-proofing as demand for broadband services grows. What is needed is an entry-level system, which is cost-effective to justify the investment in a fibre infrastructure, rather than an alternative. To do this it must be comparable in cost and carry a richer set of services than the alternatives. Once installed the return on investment of the fibre network over its whole life could be higher than the alternatives, which would not compete so well as the demand for bandwidth increases.

This chapter sets the scene for a mass-market product by focusing on fibre access technology choices that influence cost and/or service capability.