An Improved Adaptive Decision Scheme for Vertical Handoff in Heterogeneous Wireless Networks

Vertical handoff is the switching process of a multi-interface mobile host between heterogeneous wireless networks. There have been many researches focusing on policy-enabled vertical handoff decision schemes, but no technical details on handoff metric acquisition are provided in most of them. In this paper, we introduce the MAC layer sensing technique, which is designed to estimate the handoff metrics in IEEE 802.11 WLAN (wireless local area network), into the policy-enabled decision schemes. Furthermore, we improve the existing adaptive schemes for stability period prediction, making use of the handoff metrics obtained from MAC layer sensing. Simulation results show that the proposed adaptive decision scheme outperforms the previous schemes in terms of sensitivity of stability period adjusting and ability to avoid unnecessary handoffs