Improvement of optical access M-QAM transmission capacity using DSP based non-orthogonal frequency shift keying

Non-orthogonal frequency quadrature amplitude modulation (NOFQAM) is proposed to improve the transmission capacity of optical access link. In case of 64-NOFQAM, both no increase of channel bandwidth and no reduction of SNR were observed despite the increase of two more bits/symbol compared with 16-QAM.