Ever Higher Bit Rate per Wavelength, Ultra Long Haul DWDM Systems, Optical Transparency, and Sub Rate Grooming: A Complex Multi-Dimensional Puzzle

Telecommunication carriers are faced with a multidimensional puzzle in selecting the appropriate technologies for their transport network. On the one hand, future traffic projections show a high degree of uncertainty in magnitude as well as in geographical distribution which increases the need for the selected technology to be robust against traffic volume and distribution variations, while on the other hand, technology choices have grown significantly and even more innovations are in the pipeline. In particular, we have an ever-increasing bit rate available per wavelength with consequent size economies and greater spectral efficiency. We are also witnessing a continual increase in the number of wavelengths per fiber... In this paper, we discuss the relationships and the trade-offs among these factors, both qualitatively and quantitatively. The quantitative results are based on national scale backbone networks that represent a large number of real networks we have studied.