Research On Handover Technologies Of Wireless Heterogeneous Networks

Future wireless communication system will contain all kinds of wireless access networks that may have different transmition rates, different coverages, different system capacities and different service levels. In order to take good advantage of these different access networks to provide the subscribers ubiquitous services, people are focusing on interworking and convergence of heterogeneous networks. Handover technology of wireless heterogeneous networks is one of the most key technologies in the convergence of heterogeneous wireless networks.The researches on handover technologies in the past were almost concentrated in a single telecommunication system. They mainly insure the quality of voice and low rate data services in perspective of the users. In the environment of heterogeneous networks, we must design new handover management solutions to implement the service load balance in and out of the networks and to take good use of nework resource to meet the requirements of multiple services of the users. So the emphasis and difficulty of the research is to design a network architechture with high flexibility and low complexity and a handover method which considering the characteristic of most networks. Now, 3GPP, 3GPP2 and European WINNER project are all taking part in this research work. They have proposed lots of new ideas, but the results still need to be improved and the final results will be the main candidate technologies of handover technologies of future wireless heterogeneous networks.The main research work of this paper is based on a cooperation project of European WINNER II wireless network convergence team. Research background is analyzed at first and then this paper tracks the research status of handover technologies of wireless heterogeneous networks.Then an UMTS-WLAN interconnection model is designed and developed using OPNET simulation software.At last, handover technologies of future wireless heterogeneous networks are researched in the perspectives of network architechture and handover schemes. Distributed control and centralized control approaches in the perspective of network architechture are analysised and a new hybrid control scheme is proposed. The performance of link and IP handover are analysised and compared through the simulation results. Then a new link and IP hybrid handover method is proposed. Finally the paper summarizes that the integration of the two hybrid schemes will be a good solution of handover problem in the convergence of heterogeneous wireless networks.