Study On Vertical Handover Algorithm With Handover Prediction Mechanism In Wireless Heterogonous Networks

Communication technology is developing rapidly. The transformation from analog communication system to digital communication system, and even to the third generation system which can carry multimedia services, only lasts for a few decades. Now various communication technologies and access technologies coexist. So the future wireless communication system must be a heterogeneous wireless network which has IP core network and multiple access technologies. Therefore, how to provide people with seamless roaming services in various networks becomes one of the hottest topics in the next generation networks.Through the summary of previous studies, we found that the current vertical handoff strategy of heterogeneous wireless network did not consider the influence on handoff time spot in complex handoff mechanism. Aiming at the problem, we add handover prediction mechanism into vertical handoff strategy in heterogeneous wireless network. First of all, we undertake beforehand according to user's movement speed and business of real-time to reduce the frequency of switching failure; secondly, the gray multiple attribute analysis makes the target cell list promptly and quickly find the right cell based on the data mobile station collected, such as network signal quality, load conditions, business types, user mobile speed, and user preferences on the network; finally we add a waiting queue in each unit switching area, and discuss the influence of the queue length.On the basis of adding handover prediction mechanism, the paper use fluid model to describe the user's mobile characteristics, and abstract the heterogeneous wireless network to gray space. Thus a vertical handoff question is abstracted to a multiple target selection question, using gray multiattribute judgment by comprehensive considering of factors such as the network load, network delay, network quality, business QoS, user preferences, etc. At last we set a queue in each unit handoff area, to make a difference between real-time service and non-real-time service, and strive to reasonable use network resources.By adding handover prediction mechanism into vertical handoff basal process in the heterogeneous wireless networks, and combining with fluid model and the gray multiattribute judgment, the paper propose a heterogeneous wireless networks vertical handoff algorithm with handover prediction mechanism. This model has two advantages: one is properly distributing network load and reducing handoff blocking possibility, second is that users can find the right target network more quickly on the basis of considering both the network side and users side information. Simulation results show that. handover prediction mechanism can effectively guarantee the handoff success rate of high-speed real-time business, at the same time, with queue mechanism in reasonable length can reduce the real-time business handoff failure.