We present an extra processing added to conventional least square(LS) channel estimation to further improve its performance in coherent optical orthogonal frequency division multiplexing(CO-OFDM) system. The influence of noise, chromatic dispersion and polarization mode dispersion on the performance of the proposed algorithm is analyzed. The simulation results show that the improved algorithm has better performance and lower complexity.
In this paper,a wavelength division multiplexing (WDM) transmission system derived from the coherent optical orthogonal frequency division multiplexing (CO-OFDM) with polarization division multiplexing (PDM) and 16-order quadrature amplitude modulation (QAM) is studied. A simulation of 80-channel WDM transmission system with data rate of 200 Gbit/s is built, and the transmission performance of the system is analyzed. The simulation results show that the system Q value of the WDM channels at 16 Tbit/s with a spectral efficiency of 7.14 bit/s/Hz is potentially over 10.0 dB for a long haul transmission up to 1800 km in a standard single-mode fiber.
A novel architecture for the colorless optical network unit (ONU) is proposed and experimentally demonstrated with direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM). In this architecture, polarization-division multiplexing is used to reduce the cost at ONU. In optical line terminal (OLT), quadrature amplitude modulation (QAM) intensity-modulated OFDM signal with x-polarization at 10 Gbit/s is transmitted as downstream. At each ONU, the optical OFDM signal is demodulated with direct detection, and y-polarization signal is modulated for upstream on-off keying (OOK) data at 5 Gbit/s. Simulation results show that the power penalty is negligible for both optical OFDM downstream and the on-off keying upstream signals after over 50 km single-mode fiber (SMF) transmission.
