Álvaro Fernández Fernández

Position: PhD student
Office: B-216
Email: alvarof@item.ntnu.no

Research Topic: Differentiated dependability in Passive Optical Networks

Passive Optical Networks (PONs) are regarded as the best suited technology to implement Fiber to the X (FTTX, with X meaning Curb/Cabinet, Building or Home) solutions. PONs are flexible, scalable, provide high bandwidth and present a low-cost deployment and low energy consumption. These features make PONs the best candidates for realizing broadband access networks. See the figure below for a possible PON architecture. Also, as new services emerge, business and residential users demand an increase in the dependability requirements of PONs, calling for protection. Yet, protection at the access part of a network may prohibitively increase the Capital Expenditures (CAPEX) due to the relatively low number of covered end-users.

The research work so far has been focused on providing a deep insight into the dependability-cost trade-off when protecting PONs. The effects of the physical PON layout, infrastructure sharing and design decisions in both dependability and CAPEX are pinpointed. The dependability is assessed by two main parameters: number of clients affected by a failure (i.e. failure impact, capturing operators' perspective) and asymptotic availability (closer to users' point of view). These two parameters are also used to derive the cost associated to failures, known to be part of the Operational Expenditures (OPEX) of a network. Besides, the CAPEX of deploying protection in PONs are also evaluated. This way, a cost-efficient way of providing differentiated dependability in PONs can be proposed.