Virtual Carrier-Assisted DD-MB-OFDM Schemes for UDWDM Metro-Access Networks With Improved Tolerance to Four-Wave Mixing

Virtual carrier (VC)-assisted multiband orthogonal frequency division multiplexing (MB-OFDM) schemes with improved tolerance to the four-wave mixing (FWM) effect in direct-direction ultradense wavelength division multiplexing metro-access networks are proposed and discussed. The best scheme is identified from a set of alternative schemes chosen with potential to increase the tolerance to the FWM effect in VC-assisted MB-OFDM systems. A data rate per band and per user of the metro-access network of 10 and 25 Gb/s is considered for band spacings of 3.125 and 6.25 GHz, respectively. With the proposed MB-OFDM schemes, increase of the maximum acceptable power launched into the fiber can be achieved. This increase translates into a similar power budget (PB) improvement. With band spacings of 3.125 GHz, a PB improvement of 3 dB is achieved, which enables to double the number of users served by the metro-access network or to extend the reach of the optical distribution network (ODN) by about 12 km. For a 6.25-GHz band spacing, a PB improvement exceeding 4 dB is achieved, enabling to double the number of users and simultaneously extend the ODN coverage by about 5 km.