Multi-Granular Waveband Assignment and Protection in WDM Networks

Waveband switching (WBS) is introduced to group multiple wavelengths together as a band or fiber and switch the group using a single port whenever possible. Instead of using the traditional optical cross-connects (T-OXCs), WBS networks employ multi-granular optical cross-connects (MG-OXCs) to switch the traffic at different granularities. In this work, we first briefly review and discuss the development in MG-OXC architecture design, routing and wavelength assignment algorithms, and protection schemes in WBS networks. Then two new schemes are proposed to solve the waveband assignment problem and waveband protection problem. In the first scheme, we demonstrate that factors such as bypass traffic and node degree can affect the waveband switching efficiency. A new hierarchical waveband assignment (HWA) algorithm is then proposed to effectively take these wavebanding factors into consideration for saving ports. In the second scheme, we introduce the concept of band-segment and explore band-segment based protection schemes to achieve the goal of port reduction, the sharing of resources and survivability in WBS networks. Our simulations show that the proposed HWA scheme outperforms a representative approach, namely balanced path routing with heavy-traffic first waveband assignment (BPHT), by up to 18% in terms of port reduction. For the first time, our study demonstrates that protection and the sharing of resources can be achieved without sacrificing port saving when the proposed concept of band-segment is efficiently adopted in WBS networks.