Phys.org February 24, 2020
Researchers in South Korea have designed real-time pulse amplitude modulation-4 (PAM-4) digital signal processing including forward error correction for a C-band inter-datacenter network. The PAM-4 DSP is intended to compensate for chromatic dispersion and provide dispersion tolerance. A decision feedback equalizer and maximum likelihood sequence equalizer were employed for the dispersion compensation. A low-density parity check code was used to increase coding gain. They have empirically proved the feasibility of 25 km transmission without error-floor sign, corresponding to a dispersion compensation capacity of 425 ps/nm and confirmed 35 km ∼ 85 km error-free transmission for inter-datacenter network…read more.  TECHNICAL ARTICLEÂ
Schematics of conventional PAM-4 system. Credit: Optics Express Vol. 28, Issue 2, pp. 1269-1278 (2020)