  Dual Connectivity (DC) is one of the key techniques to harness the potential
of heterogeneous cellular networks. However, 3rd Generation Partnership Project
(3GPP) has introduced disparate mechanisms for DC support in different Radio
Access Technologies (RATs), bringing complexity to the network nodes in a
Multi-RAT Radio Access Network (RAN). Moreover, DC support requires an exchange
of high volume of control information between these network nodes. To address
these issues, in this paper an SDN based architecture for Multi-RAT RAN is
proposed. The proposed architecture brings simplicity to the network
interactions, allows flexibility in the network and helps the network in
performing load balancing and mobility management functions effectively. We
also demonstrate a reduction in the control signaling and an improvement in
system performance compared to legacy architecture.
