Comparison of Transceiver and C+L Band Upgrades: Network Traffic and Energy Assessment

Being as power-efficient as possible is becoming an issue of increasing importance in optical networks due to the continuous increase of requested capacity resulting from the exponential growth of IP traffic. In this work, we investigate the trade-off between network capacity and energy consumption in optical transport networks when considering (i) three coherent transceiver implementations; (ii) two capacity upgrade strategies, and (iii) uniform and nonuniform traffic distributions. We show that, in Deutsche Telekom (DT) reference network, a nonuniform traffic distribution leads to an increase in network capacity of about 100 Tbps with respect to the uniform case. Interestingly, the nonuniform traffic distribution showed that, in the DT reference network, more traffic could be transmitted with less energy consumption than when considering the uniform traffic distribution. Additionally, it is also shown that C+L systems lead to an only negligible increase in energy consumption while attaining comparable network capacity as adding a second optical fiber and using C-band only for the three considered coherent transceiver implementations. Newer transceivers are found to be very power efficient when compared with older ones. This is a consequence of technological advances enabling to increase capacity via using higher-order modulation formats and baud rates. In the case of the ZR implementation, a compromise between lower power consumption and capacity was reached to address shorter links.