Wcdma And Wlan Roaming Access

WCDMA has the characters of large covering area, supporting the users' global roaming and fast mobility. WCDMA employ the CDMA technology in the wireless environment, and it improves the transmitting rate, but the theoretic highest rate is 2Mbit/s. It is unfeasible to reach the ideal rate because the cost of lying out is very high. However, the short distance wireless technology, represented by WLAN, can reach quite high transmitting rate. WLAN has the virtual of flexible networking, using the open bandwidth, and cheap network equipment and so on, which are gaining more and more attention of the suppliers. The defect of WLAN is that the covering area is small and it lack of the supporting of roaming and mobility. Therefore it suits for the thickly populated area. We can know from the description above that the two wireless technologies complement each other. WLAN, used as the complementation of the UMTS, is a good way for suppliers to offer the multi-layer mobile service. The uniting of UMTS and WLAN can get the both advantages. The seamless roaming access of WCDMA and WLAN is one of the key technologies of the uniting of WCDMA and WLAN.In the paper, I firstly introduce the developing background and the trends promoted by the suppliers of WCDMA and WLAN; then descript the key technologies and the basic theory about the seamless roaming access of WCDMA and WLAN, which include the basic architect structure of the WCDMA R99 and R4, several technology mechanism of WLAN based on 802.1 land the conception, operation and main advantages of IPV6.1 descript six scenes of the roaming access of WCDMA and WLAN in detail, and explain the system requirements of each scene, which include main characters of services, access control, security management, roaming feature and terminal feature and so on. I then fatherly analyze the roaming access scene of WCDMA and WLAN, and discuss the reality model of the roaming access, network unit and its function in the model, correlative reference nodes, the basic discipline of multi-layer roaming and roaming charge.Having the work above, I emphasis on the utility of IPV6 in the roaming accessand the IP security technologies based on the roaming access of WCDMA and WLAN. Because the wireless interface of WLAN is not appointed as a part of the WCDMA network, there is not a uniform wireless interface management or mobility management technology between these two different access technologies. Thus, the difficulty is roaming and handoff between them. Mobile IPv6 can just support good mobility for the access of WCDMA and WLAN, therefore, the problems of seamless roaming access of WCDMA and WLAN can be solved effectively.