Research On Vertical Handoff Among Heterogeneous Networks WLAN And TD-SCDMA

Along with the mobile data users of wireless broadband business demand increases sharply,the 3G mobile communication system network and WLAN wireless LAN fusion has become the operators need to solve the problem.Fusion of 3G mobile network and WLAN wireless LAN is also under development technology generation mobile communication system trend.Switching between the two different heterogeneous network called vertical handoff,in order to maintain the mobile data service is not interrupted,is a key technique to solve the 3G mobile network and WLAN wireless LAN fusion problem.3G mobile network and wireless local area network convergence to play different wireless network advantage,make up for the deficiency of each network,so as to optimize the network performance.This paper first discusses the TD-SCDMA network and WLAN wireless local area network of two kinds of heterogeneous wireless network are fixed between the vertical handoff based on hysteresis and hysteresis based on adaptive vertical handoff two switching mechanism and performance,through simulation comparison:adaptive hysteresis vertical switching can be fixed hysteresis vertical handoff can be obtained with low switching switch the rate,low rate,average flow rate is higher;and then discusses the fixed hysteresis bandwidth partitions the values of vertical handoff and adaptive hysteresis value principle and performance of vertical handoff based on WLAN network,finally discusses the distribution of QoS bandwidth fixed hysteresis vertical handoff and adaptive vertical handoff hysteresis value principle and performance based on.Through MATLAB simulation software simulation shows:single AP switch mobile transmission station obtained rate is higher than before the switch,the adaptive hysteresis values in each mobile station vertical handoff average transmission of the assigned to after switching rate of vertical handoff is about 5%higher than the use of fixed hysteresis.When the mobile station is in the different motion rate,QoS bandwidth allocation based on adaptive vertical handoff hysteresis value both in speech,surfing the Internet or multimedia video and other aspects of the average data rate,switch rate are better than the fixed hysteresis vertical handoff,average data rate is increased by 7%,the switching rate lower than 0.9%.Therefore,adaptive hysteresis QoS bandwidth allocation based on the value of the vertical handoff is best,can improve the overall system flow,reduce the switching rate.