An optical transmission system exploits the reduced signal-to-noise (SNR)
requirements for low-bit rate channels to devise a new wavelength channel
allocation scheme which increases the number of channels that a WDM system
can support. Wavelengths of low-bit rate channels are assigned outside a
flat-gain window (i.e., flat-passband region) of the system. The channel
allocation scheme uses the high-bit rate channels located in the
flat-passband region of wavelengths and the lower-bit rate channels
located outside this passband region with progressively lower-bit rate
channels located farther outside this passband region. Low-bit rate
channels are also assigned to region(s) of the passband where the
non-linear threshold power level of the system may be exceeded.
