Research On Vertical Handoff Algorithm Based On Utility Function In Heterogeneous Wireless Networks

Vertical handoff can effectively ensure the continuity of communication and the quality of service(QoS)demands when end users moving or roaming in heterogeneous wireless networks.On the one hand,the diversification of network's status and users' personalized demands will both affect the vertical handoff performance.On the other hand,if the handoff decision is only based on user centric or network centric without giving due consideration to the influence of both sides,the vertical handoff performance will also turn out to be poor.Therefore,it is important to conduct a vertical handoff research from the aspects of dynamic weight optimization and two-sided matching model in heterogeneous wireless networks.Existing vertical handoff algorithms in heterogeneous wireless networks do not consider the status transformation of the available network and the QoS of the terminal's communication service,so a dynamic weight optimization based vertical handoff decision algorithm is proposed to overcome the shortages.First,the Analytic Hierarchy Process and Entropy are used to calculate subjective weight and objective weight respectively.The combination weight can be obtained by Single-objective Optimization Problem theory.Then,to accommodate the status transformation of the available network,the algorithm further introduces a weight adjustment factor to adaptively adjust the combination weight.Finally,according to the terminal's QoS demands,the utility function with adjustable handoff thresholds is designed to select the optimal network.Simulation results show that the proposed algorithm effectively reduces the blocking rate and drop call rate,and improves the system throughput without much increase in computational complexity.Most of the existing vertical handoff algorithms are only based on user centric or network centric,which do not fully consider the common impact of the two sides on the handoff performance.In order to solve this problem,a two-sided matching model based vertical handoff algorithm in heterogeneous wireless networks is proposed.First,two evaluation models,which are respectively based on user centered and network centered,are designed to evaluate their preference order for each other,and the corresponding ranking value matrices are established.Then,based on the ranking value information,a two-sided matching model is used to analyze the two-sided matching behavior of users and networks,and the optimal matching solution is obtained.Finally,the vertical handoff is completed according to the optimal matching result.Simulation results show that the proposed evaluation models are reasonable,and the proposed algorithm can better balance the demands of users and networks.