Performance comparison between 160 Gb/s WDM and TDM systems

The performances of 160 Gb/s time-division multiplexing (TDM) and 4 × 40 Gb/s wavelength-division multiplexing (WDM) signals are comparatively studied in the nonzero-dispersion shifted fibers (NZDSFs). TDM format is superior to WDM, and with the increase of distance, this advantage is enhanced. In the case of adopting the dispersion managed soliton transmission and dispersion flattened fibers (DFFs) technique, the Q values of both formats change little when the channel space varies. So, TDM technique is applicable to the dense and very long haul transmissions. Only by utilizing the conventional loss and dispersion compensation schemes (NZDSFs + DCFs + EDFAs), the available transmission distance of dense WDM signals reaches 1000 km, and for TDM format, it even extends to 2000 km. Both systems have the analogue characteristics: a higher pulse power benefits system's working; ASE noise is the dominant impact factor of system performance; both format's system performances are improved for the case of less channel number; the channel space and duty cycle of return zero pulse have little effect on Q; the impact of duty cycle relates to the filter bandwidths, XPM induced sidebands and pulse broadening effect; the influence of channel space is determined by the walk-off effect.