Survivable multipath routing and spectrum allocation in OFDM-based flexible optical networks

Compared with traditional WDM networks, orthogonal frequency-division multiplexing (OFDM)-based flexible optical networks are able to provide better spectral efficiency due to their flexible allocation of requests on fine granularity subcarriers. Survivability is a crucial issue in OFDM-based flexible optical networks. In this paper, we present a survivable multipath provisioning scheme that provides flexible protection levels in OFDM-based flexible optical networks. We define the Static Survivable Multipath Routing and Spectrum Allocation (SM-RSA) problem, which aims to accommodate a given set of demands with minimum utilized spectrum. We show that the static SMRSA problem is NP-hard and provide an integer linear programming formulation for it. Also, an efficient heuristic algorithm is given to solve the problem. Our simulation results show that the proposed multipath provisioning scheme achieves higher spectral efficiency than the traditional single-path provisioning scheme.