Enabling Vertical Handover Decisions in Heterogeneous Wireless Networks: A State-of-the-Art and A Classification
Handover solutions ensuring seamless connectivity and high user-perceived quality of service for a given application context are essential for multi-mode wireless devices in heterogeneous wireless network environments. A critical handover step, the network selection decision, is automatically and transparently made in the user's terminal, aiming to keep the user “always best connected”. We propose Quantified Adaptive Delay Selection (QADS), a novel multi-user-aware handover algorithm that maintains high quality of service levels for mobile users performing handover in heterogeneous wireless network environments. QADS is a user-centric solution buildt on the IEEE 802.21 Media Independent Handover standard. It addresses the problem of multiple mobile nodes performing network selection independently, using the same selection algorithm. With innovative mechanisms based on adaptive contention and randomization, the algorithm increases overall user-perceived quality of service.