Research And Implementation Of Vertical Handover Algorithm In UMTS/WLAN Convergence Network

In the past few decades, the network system has undergone a transitional phase, and the nextgeneration network (NGN) will be a different network system consisting of different wirelessaccess technologies, which is called as heterogeneous network. With the increasing needs ofusers, service providers will offer different services to meet their customers having a better levelof service and quality of user experience (QoE). It will involve one of the key technologies in theheterogeneous network-vertical switching technology. In this paper, we first list the existingvertical handover decision mechanism, and by analyzing two representative fusion of UniversalMobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN), themobility management technology of the vertical handoff technology will be proposed.Firstly, we reviewe the development of wireless communication in the past few yeas andforecasted the development of heterogeneous networks in the future and descripted the wirelessheterogeneous networks feature briefly, and introducted the heterogeneous network convergenceprocess of the key technologies briefly. In addition, it makes a brief introduction applied in thepaper, and makes a detailed classification and summary related the vertical handovertechnologies.Secondly, we propose a vertical handoff algorithm which is based on the cost function andthe AHP algorithm was introduced in. In order to reduce unnecessary switching, the algorithmuses the received signal strength, bandwidth, user preferences and price as vertical handoverdecision factors. The simulation results show that the algorithm significantly reduces theswitching frequency, thereby improving system performance.Finally, this paper propose a vertical handover algorithm which is not only based on thespeed but also introduced of pre-judgment to finish the judgement of handover. The algorithm isbased on utility function, and makes improvements on bandwidth and signal strength values.That is used in their normalized values to determine the target network. Next, entering thevertical handover decision stage, we introduce a difference predictive algorithm to furtherconstraints on the switch, and the purpose is to reduce the impact of ping-pong effect andimprove the performance of handover. In addition, the mobile terminal speed is introduced asanother constraint of this algorithm that is due to when the mobile terminal is in the largermoving speed, the ongoing data transmission and other services may be affected, resulting in a higher loss rate. The method used in this paper is to preset a speed threshold, and then combinedtogether with the type of transmission business to decide whether the switch happens. This paperuses the MATLAB simulation software to compare the performance among the AHP, RSS andthe cost function switching algorithm. Simulation results show that the proposed algorithm caneffectively reduce the number of occurrences of the ping-pong effect, and can increase switchingefficiency and reduce call drop rate and switching blocking rate and improve systemperformance.