Elastic Spectrum Allocation for Variable Traffic in Flexible-Grid Optical Networks

The currently deployed Wavelength Division Multiplexing (WDM) optical networks operate within a rigid frequency grid and with single-line-rate transponders making use of single carrier modulation techniques. The evolution path of optical transport networks can be translated to the application of advanced single-carrier modulation formats (such as QPSK, 16-QAM) in mixed-line-rate networks, the introduction of multi carrier modulation techniques (such as O-OFDM), and the elastic access to spectral resources within flexible frequency grids. Thanks to these advances, future Elastic Optical Networks (EON) will utilize the spectral resources efficiently, according to the transmission path characteristics and bandwidth requirements; EON divide the spectrum into frequency slots which provides greater granularity than rigid networks based on WDM.