20-Gb/s OFDM Transmission over 4,160-km SSMF Enabled by RF-Pilot Tone Phase Noise Compensation

We introduce a novel method to compensate for local oscillator offset and phase-noise in coherent-OFDM systems and report continuously detectable transmission at 20-Gb/s data rate (25.8 Gb/s before coding) over 4,160-km SSMF without dispersion compensation.