Subsystem-Modular Optical Cross-Connect Architecture with Unidirectional Intra-Node Connections

To cope with the scalability limitations of conventional optical cross-connects (OXCs), previous studies have introduced a subsystem-modular OXC architecture, which comprises multiple low-port-count switch modules called OXC subsystems. This architecture typically employs a linear intra-node structure that connects OXC subsystems sequentially within a node. While this architecture allows for smaller OXC subsystems to be used, it includes redundant intra-node connections between OXC subsystems to ensure high intra-node routing flexibility, which can lead to an increased number of deployed OXC subsystems. This paper proposes a node architecture that adopts unidirectional intra-node connections, aiming to lower the port requirements for internal connections. In the proposed node architecture, OXC subsystems are connected in one direction, which can help to avoid redundant bidirectional connections and enable more ports to be used for internode connections. We formulate the network model with the proposed node architecture as an integer linear programming problem. For a large-size problem, we incorporate a routing and wavelength assignment algorithm for the architecture to address the restriction introduced by unidirectional intra-node connections. Numerical results demonstrate that the proposed node architecture reduces the total number of OXCsubsystems compared to the benchmark architecture.