A software-defined network based vertical handoff scheme for heterogeneous wireless networks

We propose a novel Quality of Service (QoS) vertical handoff scheme with the support of the Software-Defined Network (SDN) technique for the heterogeneous wireless networks. The proposed scheme solves two important issues of the vertical handoff: network selection and handoff timing. In this paper, the network selection is formulated as an 0-1 integer programming problem, which maximizes the overall QoS and avoids the network congestion. After the network selection process is finished, a mobile will wait for a time period for implementing the vertical handoff. The selected network should be consistently more appropriate than the current network during the time period, the mobile will transfer its inter-network connection to the selected network. Our proposed scheme ensures that, a mobile will transfer to the most appropriate network at the most appropriate time. Comprehensive simulation has been conducted. It is shown that the proposed scheme reduces the number of vertical handoffs, and maximizes the overall QoS significantly comparing with existing schemes.