What next generation optical network means?

2017 edition

Laura Martín González

The traffic demand has been increasing exponentially last decade. It is expected that it continues growing due to the expansion of technologies such as HDTV, 5G or Internet of things. In optical communications, innovative approaches are being extensively investigated in order to cope with this requirements. One of them is Orthogonal Frequency Division Multiplexing (OFDM) systems [1]. Its main advantage is that allows to carry the data information over many parallel frequencies or subcarriers. This enables the possibility to handle the individual subcarriers in order to improve the system performance. OFDM has been studied for years in RF domain but the uniqueness of optical channels and systems make it particularly interesting. In one hand OFDM is robust against optical channel dispersion and the phase and channel are easy to estimate in a time-varying environment. In the other hand OFDM also has some disadvantages such as its sensitivity to phase or frequency noise.

In order to support the evolutionary approach of future networks, the advance of transmission techniques need flexible, robust and adaptive networks equipped with flexible and adaptive transmitters and receivers that can adapt to the actual traffic needs [2]. In our work we examine different possible multi-adaptive techniques. The implementation of them is done by means of multiplexing techniques based on physical dimensions [3]. Depending on the application requirements, one has to choose the best suited combination of multiplexing technique. Traditionally, these techniques were studied with the objective of using deployed optical infrastructure. This makes the adaptive modulation, and the division multiplexing in time, frequency and polarization the first options to exploit. The problem arises mainly due to the fact that the achievable capacity per fiber may become a bottleneck [2]. In order to overcome this problem the spatial dimension can be also exploited [3].

References:

[1] Shieh and I. Djordjevic, OFDM for Optical Communications. USA: Elsevier, 2010.

[2] Napoli, M. Bohn, D. Ra_que, A. Stavdas, N. Sambo, L. Poti, M. Nolle, J. Fischer, E. Riccardi, A. Pagano, A. Di Giglio, M. Svaluto Moreolo, J. M. Fabrega, E. Hugues- Salas, G. Zervas, D. Simeonidou, P. Layec, A. D’Errico, T. Rahman, and J. Gimenez, “Next generation elastic optical networks: The vision of the European research project IDEALIST”, IEEE Communications Magazine, vol. 53, no. 2, pp. 152, Feb 2015.

[3] Ryf, S. Randel, A. Gnauck, C. Bolle, R. Essiambre, P. Winzer, D. Peckham, A. Mc Curdy,and R. Lingle, ”Space-division multiplexing over 10 km of three-mode fiber using coherent MIMO processing,” Optical Fiber Communication Conference and Exhibition/National Fiber Optic Engineers Conference, (OFC/NFOEC), pp. 1-3, March 2011.