Investigation of launch power and regenerator placement effect on the design of mixed-line-rate (MLR) optical WDM networks

In recent years, owing to the consistent increase in volume and heterogeneity of the traffic, telecommunication networks have undergone significant innovations. Existing studies have shown that, by adopting a mixed-line-rate (MLR) strategy, wavelength division multiplexed (WDM) optical networks can cost-effectively respond to the diverse variety of traffic requirements which have heterogeneous service demands. However, due to the existence of physical layer impairments [specifically cross-phase modulation (XPM)], adjacent channels on different line rates may exhibit serious degradation of signal quality and optical reach. In such cases, launch power governs the bit-error rate as it affects both the signal and the noise power due to XPM. Therefore, an intelligent choice of launch power on different line rates can significantly reduce the network cost. Further, in MLR optical networks, trade-off between regenerator placement and the launch power attains importance and needs to be addressed. In this work, we investigate the launch power and regenerator placement effect on the design of a MLR WDM optical network. The obtained simulation results show that the network cost is (i) mainly controlled by power values of the 10/100/400 Gbps channels, and (ii) decreases for a cost model in which, compared to 10 G transponders, high-bit-rate transponders have higher cost decay. Further, with a lower cost model, it is found that more numbers of regenerators can be deployed, simultaneously minimizing the network cost.