Performance characterization of optical offset-QAM OFDM for fiber transmission

Offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) can greatly relax the needs of guard interval (GI) for longdistance optical transmission. In this paper, we show that 40-Gbit/s offset-16QAM OFDM can support 840-km transmission with negligible performance penalty when GI is not applied. In contrast, a GI length of 12 samples is required in conventional OFDM to realize the same transmission reach. We investigate performance sensitivity to various parameters in the offset-QAM OFDM system and show that the system only introduces slight complexity increment over conventional OFDM while offering significant net data rate improvement for fiber transmission.