Research Of Qo S For Heterogeneous Wireless Networks

With the rapid development of wireless technology,it's inevitable trend of the next generation communication system to integrate a variety of communication devices,communication networks,and communication protocols,so that users can enjoy the best communication services at anytime and anywhere.Heterogeneous wireless networks can provide higher speeds,larger bandwidths,and better links.However,the biggest challenge of heterogeneous wireless networks is how to achieve cross-cell communication without interrupted,and ensure the Qo S commands of users.In this paper,first,we introduce the characters of WLAN and UMTS and the their Qo S demands,and further descript the basic concepts and requirement of heterogeneous wireless networks by giving the development status,key technology research and Qo S assurance of heterogeneous wireless networks.Then according to the key technology of heterogeneous wireless networks,focusing on the methods of networks integration and users' equipments access and doing detailed research.Then simulate the heterogeneous wireless networks of WLAN and UMTS.These two different types of networks have different characteristics.The UMTS is stable and covers a wide range,but the data rate is low and requires infrastructure support.The WLAN data rate is high,however,it has the disadvantages of small coverage and it has unstable link.According to complementary characteristics of the two networks,we do some research on heterogeneous wireless networks.By using the simulation tool called OPNET,designing a heterogeneous network simulation of UMTS/WLAN,and designing a utility-based handover algorithm and a dual-mode station device designed to select the network automatically according to the handover decision.In OPNET,three scenarios of low speed,middle speed and high speed have been established to simulate FTP and Video traffics.Researching Qo S of he heterogeneous wireless networks by comparing the data rates,delay,response time and throughput.