中文摘要：

通常情况下,移动终端的运动速度是一个变量,它将影响异构网络之间的垂直切换性能。假如当前业务为语音业务,并且移动端高速运动时,移动端频繁的切换有可能导致较大的丢包率,严重时导致终端的掉话。考虑到了这种问题,文章将移动端的移动速度和业务类型相结合,引入移动终端的速度阈值作为限制条件。在改进效用函数基础上,提出一种匀加速预判决过程的垂直切换判决算法。采用MATLAB软件对该算法对比RSS（信号强度）、效用函数以及引入预判决的算法进行仿真分析,结果表明,切换次数分别降低了13次、3次和1次;切换呼叫掉线率分别降低了4.2%、2.1%和1.2%,新呼叫阻塞率分别降低了4.2%、2.7%和1.8%。3个性能指标的提升证实了该算法性能的优越性。

英文摘要：

Usually,the speed of mobile terminal is a variable,which will affect the vertical handover performance of heterogeneous networks.It is assumed that current service is voice service and the mobile terminal moves at a high speed.In such condition,frequent switch of mobile terminal may lead to a large packet loss rate or even stopping communication.In view of this problem,this paper combines the speed of mobile terminal with service type and introduces speed threshold of mobile terminal as the restriction.This paper presents a vertical handover decision algorithm of uniformly accelerated pre-j udgment process,based on the improved utility function.MATLAB software is used to comparatively analyze this algorithm with RSS （signal intensity）,the utility function and the algorithm with introduction of pre-judgment.The results show handover times reduces 13,3 and 2 respectively.Call drop rate decreases by 4.2%,2.1%and 1.2% respectively.New call blocking rate decreases by 4.2%,2.7% and 1.8 % respectively.The improvement of three property indicators verifies the superiority performance of the proposed algorithm.