Transport SDN at the dawn of the 5G era

This editorial introduces the topic area of this special issue, namely the area of Software Defined Networking (SDN) controlled optical transport networks, i.e., so-called transport SDN (T-SDN) networks, that support emerging fifth generation (5G) wireless networks. We first outline the SDN concept and the main challenges and potential benefits of SDN control in optical transport networks. We then introduce the articles of this special issue, which we have categorized into articles addressing: (i) T-SDN control plane architectures, (ii) T-SDN provisioning and restoration, and (iii) control of specific transport technologies in T-SDNs. We conclude this editorial with a broad outline of future research directions related to T-SDNs supporting 5G networks.