Research On Vertical Handoff Technology Based On Service Classification And Condition-Aware In Heterogeneous Wireless Networks

With the development of mobile communication systems,a variety of wireless access technologies with different characteristics have emerged,which are merged into heterogeneous wireless networks to meet the diverse service needs of users.Vertical handoff is one of the key technologies in heterogeneous wireless networks,which can guarantee the seamless roaming between different networks.In heterogeneous wireless networks,when the number of users is large,it is easy to cause congestion,which leads to the degradation of network performance.On the other hand,the high-speed users,such as vehicle terminals,will switch frequently when they move quickly,which will affect the user experience.Therefore,in heterogeneous wireless networks,how to design an effective vertical handoff algorithm,to ensure the end-users to get better quality of service,has an important research significance.In this paper,the two communication scenarios of user-intensive area and high-speed mobile in heterogeneous wireless networks are studied.The main work of this paper is as follows:A vertical handoff algorithm based on service classification is proposed to solve the problem of a large number of users switch to the same network at the same time,which result the network congestion and performance degradation in crowded areas.The algorithm consists of the following two parts: firstly,the users are graded according to the service type of the users,and the priority is adjusted dynamically,and the high priority users are selected each time.Then,in the handoff decision stage,according to the different demands of different types of services on the quality of service,the analytic hierarchy process is used to construct the different decision matrices,and the utility function is used to make the decision.The simulation results show that the proposed algorithm can reduce the blocking probability and dropping probability,improve the total throughput of the network,and can select the suitable network for the users.Although the algorithm improves the performance of the network,it ignores the problem caused by the high speed movement of the vehicle terminal and and the different preference of the terminal users.Therefore,a vertical handoff algorithm based on condition-aware is proposed.The algorithm is divided into two stages: handoff triggering and handoff decision.First of all,in the handoff triggering phase,a trigger manager is designed to judge whether to trigger the handoff according to the received signal strength,the terminal motion trend and the data transmission rate.Then,in the handoff decision stage,different handoff decision algorithms are designed for the two different triggering mechanisms,a condition-aware handoff decision algorithm is designed.The simulation results show that the proposed algorithm can reduce the average handoff numbers,reduce the handoff failure probability and blocking probability,improve the total throughput,and improve the user satisfaction.