User-Adaptive Vertical Handover Scheme Based on MIH for Heterogeneous Wireless Networks

Mobile terminals have to accomplish vertical handovers among heterogeneous networks for the purpose of realizing seamless roaming and guaranteeing quality of service (QoS). Media Independent Handover (MIH) mechanism defined by IEEE 802.21 standard is a possible approach to this problem. In this paper, we propose a novel user-adaptive vertical handover scheme based on MIH in UMTS, Wi-Fi and WiMAX networks. It follows user-adaptive principles in which a user's QoS demand is taken into consideration in both handover initiation and decision making procedures. We define two kinds of handover triggers caused by unfulfilled QoS requirements or deteriorating wireless channel conditions. Compared with classical Multiple Attribute Decision Making (MADM) methods, a more flexible selection criterion to choose the network providing proper QoS according to a user's need is designed and discussed. The simulation results show that the proposed scheme provides smaller handover times and better QoS than the basic vertical handover scheme.