Radio Access Technology Selection and Vertical Handover Decision Algorithms for Heterogeneous Mobile and Wireless Networks
Kire Jakimoski and Toni Janevski
Heterogeneous mobile and wireless networks are major challenge of the future concept of all-IP based mobile and wireless networks. Modern wireless information terminals may comprise interfaces for access to different kinds of mobile and wireless communication technologies. The most important part of this kind of networks is how to allocate the mobile users to the most adequate radio access technology for them. In this paper we develop an analytical framework using the Markov chain to determine the all possible states of the mobile terminals equipped with three interfaces for WLAN, WMAN and WWAN networks. The heterogeneous system of WLAN, WMAN and WWAN networks is modeled as a Markov chain with the appropriate transitions among the all possible states of the mobile terminals. Furthermore, we propose radio access technology selection and vertical handover decision algorithms for the three access technologies in order to optimize the performances of the heterogeneous mobile and wireless networks. We vary the offered traffic conditions to evaluate the performances of the proposed radio access technology selection and vertical handover decision algorithms, calculating the session arrival rates of the new sessions and vertical handover sessions, and new session and vertical handover session blocking probabilities. We also use the IEEE 802.21 standard as a layout for testing some of the algorithms in ns-2 simulation environment. The results from the simulations show that the proposed algorithms reduce unnecessary vertical handovers and optimize the load of the given heterogeneous networks.
Keywords: Blocking probability, session arrival rate, heterogeneous mobile and wireless networks, Markov model, radio access technology selection algorithm, vertical handover decision algorithm.