Reducing the Investment Uncertainty for Optical Access Networks
Stefan Carlsson Robert Johansson
Stokab Telia Company
Nexans Sweden AB
The Celtic Next project H-OPTO aimed at establishing best practices and creating new knowledge in the installation, operation and maintenance of optical access networks. Until recently, most of the research effort on optical networks has mainly focussed on increasing capacities and developing new optical components. Less research has gone into analysing the overall deployment costs and the operations and maintenance costs. H-OPTO has focused on these costs with the ambition to build up practical knowledge and stay ahead of industry needs when deploying and operating such networks. While optical access networks are currently still far from ubiquitous, deployments are rapidly increasing. As these networks grow and start to age, quality and operation issues become progressively important. It is this network rollout and operational holistic view that H-OPTO brings to the world of optical fibre access.
The project set out to answer some specific questions such as: “How do optical networks age?” and “How do we transform network maintenance into a data-driven business?” These questions have largely been answered by the project. Cost savings in network maintenance have been achieved both for the optical access network and for fibre-fed commercial indoor wireless networks. The combination of optics and wireless expertise within the project has led to some notable results, including a new business model for one of the project partners, which significantly reduces both costs and the environmental impact for in-building mobile distribution. The project also had two successful forward-looking innovation strands, one looking at the techno-economics of optical access deployment (eventually this model will add 5G transport cost analysis capability) and the other looking at methods to secure a disturbance-free Wi-fi in-door environment.
On the optics side, the project has brought together the main actors in Sweden, bringing with them their experience and expertise they have gained in deploying optical fibre networks throughout the country. Almost every home, even in rural areas, now has a fibre connection in Sweden. This expertise was combined with that from the Polish optics industry that maintains a global position in the production and testing of optical components. From the UK, BT added experts on optics, networks and techno-economics. And partners from Turkey and Sweden added further proficiency in the area of in-door wireless solutions including international standards experience. The success of this project is a direct result of the competence and engagement of all the participating partners. Figure 1 shows the deployment of fibre and fibre cable by Telia from 1985 until 2019 throughout Sweden.
Cables, connectors and ducts were extensively examined during the H-OPTO project, with the aim of identifying the significant reasons for network faults, which were extracted from fault logs using data mining techniques.
Summary of the estimated aging of optical component results
Cables used during the past 25 years have not undergone any significant degradation. Cable lifetime is mostly dependent upon cable size (i.e. fibre count) and if a cable has needed to be replaced due to under-capacity. Problems noted for old cables have been related to material compatibility, which is now prevented by implemented aging tests in the qualification test programme.
Connectors are generally a weak point and cause problems for customers when high quality components are not used. However, aging has not been found to be an issue. Problems are most likely to arise due to poor fibre cleaning methods used by technicians.
Ducts: cost-wise the ducts are the most important component in a network, as re-trenching should be avoided whenever possible. Internal friction increases over time after a cable has been installed inside a duct, which can make removing cables and installing further cables difficult. However, this friction has been found to be reversible with the correct cleaning and lubrication techniques.
Conclusion and outlook
H-OPTO has been a driver in creating a new forum for technical discussions involving several different network owners in Sweden. Telia and other partners in the project have shared experience, data and quality requirements. This Swedish cooperation is expected to continue in the future, which will be beneficial for everybody connected to a fibre network within the Swedish market. In addition, other parts of the project have developed analytical cost models, investigated future network architectures based upon white-box hardware and open source software, in-home wireless interference mitigation techniques and developed remote headend mobile distribution equipment. The H-OPTO project will be continuing under the Celtic-Next banner with additional partners under the name A5gard.
› Further information
› H-OPTO project page – www.celticnext.eu/project-h-opto/