Chromatic Dispersion Robust Delta-Sigma Modulation for High-Order QAM Mobile Fronthaul

We experimentally demonstrated Chromatic Dispersion (CD) robust Delta-Sigma Modulation (DSM) for high-order QAM mobile fronthaul. By using Duobinary (DB) encoding technology, the anti-dispersion ability of the DSM signal is effectively enhanced. At the same time, the DB coding technology can compress the signal bandwidth to a certain extent, thereby further improving the spectral efficiency of the digital mobile fronthaul based on the DSM technology. Through the joint coding scheme of DB and DSM, we successfully realized the 30 km fiber transmission of 30G baud DB-DSM signal in the C-band intensity modulation direct detection (IM/DD) link. Compared with the conventional NRZ-DSM scheme, the DB-DSM scheme shows better receiver sensitivity and can support the transmission of larger bandwidth signals.