Hi,
Four Wave Mixing crosstalk suppression can be achieved by using unequally spaced channel allocation methods such as integer linear programming (ILP), extended quadratic congruence (EQC) algorithm, search algorithm (SA), disjoint difference sets (DDS), and optimal Golomb ruler (OGR) sequences. The main contribution of this paper is to presents a brief survey on the ILP, EQC, SA and DDS and detailed survey on OGR sequences proposed in literature for FWM crosstalk suppression in WDM systems.
The use of proper unequal channel spacing keeps FWM signals from coherently interfering with the desired signals.
An optimumUSCA (O–USCA) technique ensures that no FWM signals will ever be generated at any of the channel frequencies if the frequency separation of any two channels is different from any other pair of channels in a minimum operating bandwidth.