Resource Allocation for Space Division Multiplexing: Optical White Box vs. Optical Black Box Networking

Elastic optical networking (EON) with space division multiplexing (SDM) is the only evident long-term solution to the capacity needs of the future networks. The introduction of space via spatial fibers, such as multi-core fibers (MCF) to EON provides an additional dimension as well as challenges to the network
planning and resource optimization problem. There are various types of technologies for SDM transmission medium, switching, and amplification; each of them induces different capabilities and constraints on the network. For example, employing MCF as the transmission medium for SDM mitigates the spectrum continuity constraint of the routing and spectrum allocation (RSA) problem for EON. In fact, cores can be switched freely on different links
during routing of the network traffic. On the other hand, intercore crosstalk should be taken into account while solving the resource allocation problem. In the framework of switching for elastic SDM network, the programmable architecture on demand (AoD) node (optical white box) can provide a more scalable solution with respect to the hard-wired reconfigurable optical
add/drop multiplexers (ROADMs) (optical black box). This study looks into the routing, modulation, spectrum and core allocation (RMSCA) problem for weakly-coupled MCF based elastic SDM networks implemented through AoDs and static ROADMs. The proposed RMSCA strategies integrate the spectrum resource
allocation, switching resource deployment, and physical layer impairment in terms of inter-core crosstalk through a multiobjective cost function. The presented strategies perform a crosslayer optimization between the network and physical layers to compute the actual inter-core crosstalk for the candidate resource solutions and are specifically tailored to fit the type of optical node deployed in the network. The aim of all these strategies is to jointly optimize the switching and spectrum resource efficiency when provisioning demands with diverse capacity requirements. Extensive simulation results demonstrate that 1) by exploiting the dense intra-nodal connectivity of the ROADM-based SDM
network, resource efficiency and provisioned traffic volume improve significantly related to AoD-based solution, 2) the inter-core crosstalk aware strategies improve substantially the provisioned traffic volume for AoD-based SDM network, and 3) the switching modules grows very gently for the network designed with AoD nodes related to the one with ROADMs as the traffic increases, qualifying AoD as a scalable and cost-efficient choice for future
SDM networks.