A full-duplex pilot-assisted DP-16-QAM CO-OFDM system for high-speed long-haul communication

A full-duplex coherent transceiver system is presented for high-speed long-haul communication. Coherent optical orthogonal frequency division multiplexing (CO-OFDM) along with dual-polarization 16 quadrature amplitude modulation (DP-16-QAM) scheme has been implemented to achieve a data rate of 320 Gbps for both the downlink and uplink. Training symbols are used for channel estimation and a maximum transmission distance of 600 km of single-mode fiber (SMF) is achieved with comb-type pilot carriers for carrier phase estimation (CPE). The OFDM and inphase-quadrature modulator (IQM) structure can be fabricated in the form of low-cost integrated circuits (ICs) and the system possesses high reliability towards spectrally-efficient broadband communication. The overall system performance is evaluated considering bit error rate (BER) for maximum data rate, transmission distance and receiver sensitivity.