Study of WDM channel allocation on C and L bands in high-bitrate demand scenarios

Wavelength Division Multiplexing (WDM) leads to the usage of available frequency bands that generate lower losses when transmitting data through long distances, as C and L bands. This paper analyzes WDM usage to allow high density channel assignation improving fiber optics media usage for WAN communications, including the analysis of how transmission variables, such as traffic speed and channel-to-channel spacing, affect the quality of the transmitted data. It was performed a comparison of different wavelength-allocation scenarios, leading to state the best data transmission setups that support actual and potentially future high-bandwidth demands throughout long distance optical networks, optimizing physical media usage and keeping a low bit error rate in the data transmission. Results show that it is possible to transmit at high bit rates in WDM optical fiber systems with a simple intensity modulation technique, up to the limit when the increase of bitrate causes a significant overlapping in the channels' spectrum. For a 10 Gb / s perchannel WDM system, when the inter-channel spacing is 100 GHz, the penalty of increasing from 5 to 25 channels is negligible but for a 50 GHz and 25 GHz separation, the penalty increases to 0.25 dB and 2 dB. For a 25 Gb / s perchannel WDM system, there is a floor BER of 10 -5 when the channels separation is 50 GHz, and for a 40 Gb / s perchannel system it is feasible to achieve results only with a spacing of 100GHz.