Design cost and spectrum efficiency comparison of fixed-grid and flex-grid optical networks with grooming

This paper deals with the design of optical networks aiming to minimize the design cost and the spectrum usage. We present an optimization method that is able to find the optimal solutions of relevant sized instances. We apply the method to realistic case studies. With the obtained solutions, we make a cost and spectrum efficiency comparison analysis between fixed-grid and flex-grid optical networks. The results show that flex-grid gains are significant over the fixed-grid alternatives only after the introduction of 400 Gbps line rates and marginal gains are obtained without this line rate.