Band division multiplexing is proposed in this work as a cost-effective strategy to cope with the always increasing demand for capacity in optical networks. The potential of the proposed strategy is investigated considering two reference
network topologies from Germany and the USA. We evaluate the impact of using C+L+S-band in terms of capacity and energy consumption. The use of signal regeneration to improve optical performance is also evaluated. We showed that, due to the worse Quality of Transmission (QoT) in the S-band, it provides the smallest capacity increase among the considered transmission
bands. Nevertheless, placing some optical signal regenerators in this band enables increasing significantly its capacity. However, this enhancement of capacity is achieved at the cost of increased energy consumption (besides capital expenditures).