| Nowadays, with the flourish of wireless technology, many new network systems are newly born such as the local area network (WLAN), WIMAX, Ad hoc, wireless sensor network (WSN),3G and4G, etc. They adopt different network technology and each network has a respective characteristic and the using range. However, any one of them can’t assume all the business development needs independently. In the future, it is inevitable that the heterogeneous network will integrate with each other. That the complementary of each kind of network development absorbs all advantages may provide people a more high-quality and comprehensive service.WLAN is a wireless LAN technology which covers LAN hotspots and provides a54MBPS transmission rate mainly providing voice service. WIMAX is the bandwidth of wireless access technology covering a wider range and the data transfer rate is higher than the3G network, but it’s mainly limited to mobility. It basically provides high rate of data services which their terminals are moving in low speed. In contrast,3G network is a continuous cover, supporting high-speed mobile terminal and can realize seamless roaming. So it can provide data and voice services of which terminals are in high-speed moving while the rate is low.This article is principally a switch research and analysis of either two of the three kinds of network systems. Firstly, for WLAN, WIMAX and UMTS networks, it’s an introduction in detail of the three internet systems including the network protocol standard, the network structure and key technology, know the use scope understand their respective advantages and disadvantages, prove the feasibility of integration of three kinds of network integration. Then it is a preparation for the subsequent heterogeneous network switching algorithm research. Secondly, as for the WLAN and WIMAX switching between heterogeneous networks, by combining the technology of MIH and building MIH network model of WLAN and WIMAX and offering the system model and the switching algorithm, the number of packet loss in which the two systems are switching can be obtained by simulation and following analyzes of the causes of this phenomenon. Thirdly, in view of the switching between heterogeneous networks for WLAN and UMTS, by making full use of the advantages of two kinds of networks, an improved cost function of the vertical switching algorithm is raised and it uses OPNET simulation software to build network integration model. For two kinds of networks, setting up two kinds of WIFI, receiving signal strength threshold method and concerning the signal of three aspects on strength, network bandwidth and user preferences and using a receiving signal strength based on distance vector and accumulative total joint optimization decision method make the heterogeneous network under the adaptive switching judgment. Finally, the UMTS and WIMAX heterogeneous network switch can be analyzed by the adoption of the fuzzy control algorithm in the process of the decision mechanism of the simulation system. The method can save system cost and improve the efficiency of switching decisions. In addition, considering the system throughput, packet loss rate and time delay to analyze three aspects of system, by using this algorithm can reduce the occurrence of unnecessary switch. At the same time, it can reduce the ping-pong effect effectively. |
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