Joint Vertical Handoff and Resource Allocation in OFDMA/TDD Systems based on Software-Defined Wireless Network

One considerable challenge in future heterogeneous wireless networks (HetNet) is vertical handover. Current vertical handover approaches almost focus on resolving two questions: (1) when a Mobile Station (MS) needs to carry out a vertical handover (VHO) procedure; and (2) how a proper handover decision can be made in a HetNet environment. Actually, some approaches do not guarantee that MS can avoid handover flapping due to continuous changes in AP/BTS association. In addition, after MS joins in a new environment, many solutions do not care if VHO candidates meet requirements on QoS, such as fairness and throughput due to channel dynamicity. In this paper, we propose two algorithms: the VHO decision-making algorithm and proportional fair over HetNets (PFoHN) algorithm. VHO decision-making algorithm determines the network selection based on the availability of the target network. After VHO process is finished, resource allocation is performed by the PFoHN algorithm. In our study, the proposed approaches are developed with the support of Software-Defined Wireless Network technologies. Performance results show that PFoHN outperforms the Proportional Fair (PF) in terms of bandwidth and resource fairness, it also remarkably improves the overall system spectral efficiency.