GFDM-OFDM Hybrid Modulation Scheme for IM-DD Optical Communication Systems

We propose and demonstrate a novel modulation scheme termed as generalized frequency division multiplexing - orthogonal frequency division multiplexing (GFDM-OFDM) for intensity-modulated direct-detection (IM-DD) optical communication systems. In our scheme, the low-frequency band is allocated to a GFDM signal to achieve a low peak-to-average power ratio (PAPR), while the high-frequency band is filled with an OFDM signal that is robust to frequency-domain variations. By this means, the PAPR of the whole signal can be reduced and the high-frequency fading effects induced by the electronic components can be mitigated, leading to an improved system performance. Simulation results show that our proposed GFDM-OFDM format outperforms OFDM and GFDM formats in terms of optical receiver sensitivity for both the back-to-back (BTB) and 10-km transmissions. The GFDM-OFDM signal achieves receiver sensitivity improvements of approximately 3.0 dB and 1.6 dB, compared to the OFDM and GFDM signals, respectively.