The expectations imposed on presently used optical access networks are becoming higher and higher, therefore such network topology is needed, that satisfies all of these demands. Today application of optical networks is the most promising solution for this problem. There are many possibilities to implement these kinds of networks, however they have a common feature, that is their investment costs are very high. For that reason it is important to get sufficient information about the technology and the target area before making investment decisions. My task was connected to this issue; with the help of the results I got as the output of the network topology designer framework, I compared the optical access networks used nowadays, based on their investment needs, using several case studies.
In the course of my work I got familiar with the most important design and technical parameters of these networks. Three representative types of settlements were chosen and presented for comparison. Among them there are significant differences in design parameters. For the reproducibility of results I disclose the framework that was used for designing and the planning processes belonging to the technologies.
The program after finishing the executions saved the results in Excel worksheets. Modifying and extending these worksheets, and the ones used for investment efficiency calculations was one of my tasks. I tried to modify the results I received by taking account of the parameters changing with time, therefore I applied Tonic parameters on the cost elements, and I’ve calculated their changes in a ten year time period. During the investment efficiency calculations I used the results reached by this method.
The three territories of service were Solymár, Sas-hegy and a part of Zugló. Solymár is a small settlement resembling a suburb where in approximately 2000 buildings there are merely 3000 subscribers. In such small and sparsely populated areas P2P networks are a good alternative, because with a small number of subscribers the extra costs of building a cable network are less pronounced.
Sas-hegy contains parts of the XI.th and the XII.th district of Budapest, this part of the city is three times bigger than Solymár, but there’s no huge difference in the number of buildings. The distribution of subscribers is different thought, because here one has to calculate with subscription numbers attainable to bigger residential buildings, instead of the ones typical of detached family houses. The 10G GPON provides a better solution than P2P systems considering both bandwidth and investment costs, when the number of subscribers grow. Using FTTB architecture can mean notable savings considering central costs, but these are rebalanced by the high cost of MDU units, and higher operation costs. The WDM PON technology couldn’t achieve a payback period shorter than 10 years in any of the investing territories. For the reasons mentioned the 10G GPON FTTH architecture seems to be the most adequate choice.
In spite of that Zugló is a densely populated urban area of Budapest, I received similar results for these two areas of service, which comes from the matching of the density of buildings, due to territorial capabilities.
Summarizing the results, we can state that present optical access networks are a good alternative only on mid or long term because of their high investment costs. Point-to-point systems can be attractive because of their lower price tag, transparency and low operating costs, while GPON and 10G PON systems are attractive because of their compatibility with each other, and the possibilities in development. In the case of WDM PON system one has to think in the long term, but inspecting the costs on one bit/s it promises to be a truly competitive alternative in the future.