Context-Aware Vertical Handoff Decision Scheme in Heterogeneous Wireless Networks

Effective handoff scheme is an important issue in heterogeneous wireless networks. In this paper, we propose a context-aware-based vertical handoff decision scheme for heterogeneous wireless networks. A linear fuzzy membership function is employed to normalize dynamic environmental information, such as terminal´s position, speed and link quality. In this scheme, energy consumption is introduced to judge whether to handoff or not, and the candidate handoff networks are determined by the network speed threshold. We also present a comprehensive utility evaluation function to evaluate networks quality, and the weights of decision factors are calculated by analytic hierarchy process(AHP). Then, the target handoff network is selected adaptively according to the comprehensive utility of candidate networks. Specifically, we consider a knowledge base to match the environmental state with target handoff network. Simulation results show that the proposed handoff decision scheme could effectively avoid unnecessary handoff.