  In order to deal with the recent rapid increase in Internet traffic, a
transmission technology is required to enable the efficient use of the optical
fiber spectrum while offering flexibility in network bandwidth. To meet these
challenges, the emergence of Elastic Optical Networks (EON) has brought new
conceptions in the operation of optical networks, improving flexibility and
efficiency for the next generation core networks. In EON, traffic demands are
typically supported by allocating bandwidth-variable optical channels with
heterogeneous modulation formats in a spectral-efficient manner. Elastic
optical path networks require the routing, modulation level, and spectrum
allocation (RMLSA) to efficiently allocate optical spectrum resources to
optical paths. To address the RMLSA problem, Modulation Scheme approaches have
recently been proposed to allow the use of any routing and spectrum assignment
(RSA) algorithm to solve the RMLSA problem. In this paper, we propose a new
Modulation Scheme that enables the routing of traffic through dynamic
multi-modulation allocation in multiple hops to achieve blocking performance
improvement. Numerical results demonstrate that the proposed adaptive
modulation scheme achieves a reduction in bandwidth blocking of up to two
orders of magnitude in an underloaded network scenario, and 86% with higher
loads, playing an important role in spectrum savings compared with the
literature schemes.
