Optimal design of cost-effective OXC and ROADM nodes to maximize the throughput of mesh-based u-DWDM metro-access networks

Metro-access networks will play a primary role in future network fabrics, enabling connectivity among different actors such as 5G-based radio stations, edge datacenters, businesses, and home users. To provide such heterogeneous connectivity, changes to the current metro-access networks to provide them with greater scalability, higher levels of dynamic connectivity and flexibility, reduced end-to-end latency, and increased energy efficiency are required. In this context, mesh-based ultra-dense wavelength division multiplexing (u-DWDM) metro-access networks using reconfigurable optical switching nodes constitute a promising solution. However, the designs of traditional optical switching nodes are based on wavelength selective switches (WSSs), which provide high network reconfigurability only at a high cost, making them prohibitive for metro-access networks. Moving away from this design approach, a novel cost-effective and energy-efficient reconfigurable optical add-drop multiplexer (ROADM) node design built using a modular DWDM structure was recently proposed for ring-based u-DWDM metro-access networks, showing promising performance. This paper presents an optical node design for optical cross-connects (OXCs) utilizing a modular DWDM structure, with the objective of providing performance close to that of WSS-based OXCs but at a lower cost. With this target in mind, the optimal design of mesh-based u-DWDM metro-access networks was also studied using DWDM OXCs and ROADMs, with the aim of maximizing the network throughput while minimizing the hardware required to implement the switching nodes. To this end, both exact and heuristic mechanisms are presented to address the optimal network design. The results show a maximum network performance reduction of just 10% in the DWDM case compared to the WSS-based case with a switching node cost reduction in one order magnitude.