Heuristic approach to forecast the number of wavelength services in future OTN networks

The continuous evolution of photonic technologies and the first experience with photonic switches deployed in the field motivate operators to consider photonic networking in their next generation networks. For the strategic planning of multi-layer networks a realistic traffic estimate of customer services is essential in order to achieve an optimized network design meeting the operational and economical requirements. Some types of customer services like e.g. “digital leased lines” and “broadband” have a history of several years, sufficient experience and analysts’ data is available to allow a plausible forecast. The situation is different with customer lambda services. There has been a relatively small market of customer and carrier lambda leased lines served by DWDM transport. Since 2005 there are indicators that this market started growing strongly and that lambda services will be a significant part of the next generation OTN traffic, but the currently available data hardly enables a reliable estimate in particular for 40G and 100G services. This paper proposes a method to forecast the number of lambda services considering the growth of existing services as well as the emergence of future higher capacity services based on very few input parameters: the number of services and the share of the different capacity classes in the reference year, the expected annual total traffic growth, and optionally the expected annual total growth of the number of services. The calculation model is based on the distribution function of node and link capacities empirically detected during several transport network studies, which coarsely follows a negative exponential curve. Growing the traffic according to this distribution and mapping it to the lambda capacity classes’ grid provides the evolution of the different services over time. Some forecast examples are shown regarding the German optical leased lines market considering different start and growth assumptions.