Controlling Next-Generation Software-Defined RANs

Compared to previous mobile generations, the 5G system architecture offers more flexibility to fulfill a richer set of diverse requirements. Three system aspects play a major role here: support of network slicing, a split between the user plane and the control plane, and a service oriented control architecture. Emerging techniques of network softwarization such as software-defined networking are leveraged to provide this notion of flexibility manifested in a software-defined core network. However, in addition to the 5G core (5GC), analogous concepts could be applied to the next generation radio access network to sustain the required system performance. Driven by the increased attention that is currently paid to a software-defined radio access network, in this article, we propose the radio access network control function (RANCF) as an additional 5G control function. We define the main functionalities of RANCF, and propose interfaces and protocols for the interaction with 5GC functions. Exploiting network slicing as an example, we demonstrate how RANCF facilitates the slice selection and slice management procedure.