  Software-defined networking (SDN), which has been successfully deployed in
the management of complex data centers, has recently been incorporated into a
myriad of 5G networks to intelligently manage a wide range of heterogeneous
wireless devices, software systems, and wireless access technologies. Thus, the
SDN control plane needs to communicate wirelessly with the wireless data plane
either directly or indirectly. The uncertainties in the wireless SDN control
plane (WCP) make its design challenging. Both WCP schemes (direct WCP, D-WCP,
and indirect WCP, I-WCP) have been incorporated into recent 5G networks;
however, a discussion of their design principles and their design limitations
is missing. This paper introduces an overview of the WCP design (I-WCP and
D-WCP) and discusses its intricacies by reviewing its deployment in recent 5G
networks. Furthermore, to facilitate synthesizing a robust WCP, this paper
proposes a generic WCP framework using deep reinforcement learning (DRL)
principles and presents a roadmap for future research.
