  In this paper, the problem of vertical handover in software-defined network
(SDN) based heterogeneous networks (HetNets) is studied. In the studied model,
HetNets are required to offer diverse services for mobile users. Using an SDN
controller, HetNets have the capability of managing users' access and mobility
issues but still have the problems of ping-pong effect and service interruption
during vertical handover. To solve these problems, a mobility-aware seamless
handover method based on multipath transmission control protocol (MPTCP) is
proposed. The proposed handover method is executed in the controller of the
software-defined HetNets (SDHetNets) and consists of three steps: location
prediction, network selection, and handover execution. In particular, the
method first predicts the user's location in the next moment with an echo state
network (ESN). Given the predicted location, the SDHetNet controller can
determine the candidate network set for the handover to pre-allocate network
wireless resources. Second, the target network is selected through fuzzy
analytic hierarchical process (FAHP) algorithm, jointly considering user
preferences, service requirements, network attributes, and user mobility
patterns. Then, seamless handover is realized through the proposed MPTCP-based
handover mechanism. Simulations using real-world user trajectory data from
Korea Advanced Institute of Science & Technology show that the proposed method
can reduce the handover times by 10.85% to 29.12% compared with traditional
methods. The proposed method also maintains at least one MPTCP subflow
connected during the handover process and achieves a seamless handover.
