Access Selection Strategies And Algorithms In Heterogeneous Wireless Networks

Various radio access technologies coexist in the next generation of communication system. However, there is no single radio access technology which satisfies all of the users’requirements in terms of bandwidth, delay, coverage and mobility. The integration of heterogeneous wireless networks is becoming a trend. In order to fully utilize network resources and make seamless connectivity possible, efficient vertical handoff schemes are needed. During the vertical handoff process, network selection is of great importance.In this article, we discuss some basic theories about mobility and vertical handoff technologies and summarize several popular algorithms used in network selection. As traditional fuzzy logic control (FLC) based network selection algorithm endures an extremely high delay for vertical handoff process, a low complexity FLC-based algorithm is proposed. By using rough set theory to reduce the scale of fuzzy inference rules, we can sharply decrease the elapsed time for vertical handover process while assure the accuracy of network selection.In regard to muti-user and muti-network scenario, we put forward a matching game based network selection strategy. The conceptions of user’s and network’s utility function and match windows are proposed. In this scheme, both of the user’s and the network’s utilities are considered. Simulation results demonstrate that the blocking rate is relatively low and the algorithm turns out to be efficient.