Co-optimizing Allocation of Nyquist Superchannels and Physical Impairments Aware Placement of Regenerators in Elastic WDM Networks

Within the frame of the WDM networks, this paper articulates and validates the benefits of elastic spectral efficiency relying upon Nyquist superchannel, assuming static or incremental traffic and optimization of the superchannel filling ratio by means of electronic intermediate traffic grooming. This assessment is reported in terms of total accepted network capacity, average number of transponders per Gb/s transmitted, and mean number of regenerators traversed per Gb/s transported. This analysis points out why these two latter parameters differ when using adaptive bit rate interfaces. It also investigates how these outcomes depend on: (i) restriction about the regeneration, (ii) forward error correction coding, (iii) practical constraints on the spectral alignment of the subcarriers within the superchannels, and (iv) uncertain knowledge of the physical network parameters. This study highlights under which conditions the elasticity of the subcarrier modulation scheme effectively complements flexible subcarrier spacing. It proposes a particular placement of regenerators keeping substantial gain of network capacity even in the case of incremental traffic that may challenge profitable allocation of elastic superchannel.