SEMRSA: Spectrum Efficient Modulation-aware Dynamic Routing & Spectrum Allocation in Elastic Optical Network

Nowadays, Elastic optical network (EON) provides a long term solution to handle enormous volume of data traffic that arises out of recent developments in mobile technologies, cloud computing, video-on-demand etc. In dynamic environment, setting up and tearing down the spectrums in the optical path may generate spectral fragmentation thus presenting a major obstacle for the effectiveness of elastic spectral allocation. A routing and spectrum allocation (RSA) problem in EON is constrained by three factors: spectrum continuity, sub-carrier contiguity and guard band. With Orthogonal Frequency division Multiplexing (OFDM) technologies, EON is able to make efficient use of spectrum based on distance adaptive modulation format. This paper proposes a novel spectral efficient heuristic SEMRSA for dynamic RSA problem in EON by using modulation-aware concept and satisfying those three constraints. Routing in SEMRSA may take preferably single (if possible) / multiple paths for allocating a connection request to guarantee number of sub-carrier requirement for a connection request as low as possible. Simulation results show that SEMRSA results in lower blocking and higher spectral efficiency compared to a recent approach MMRSA which uses multipath routing associated with modulation awareness concept.