Abstract
Future network environment is expected to have IPv4 and IPv6 coexisted in 3GPP, 3GPP2, and WLANs. This thesis presents a roaming mechanism to achieve intersystem roaming between IPv4 and IPv6 in heterogeneous wireless networks including 3GPP, 3GPP2, and WLANs. The proposed mechanism integrates Mobile IPv6, Network Address Translation - Protocol Translation (NAT-PT), and 6to4 automatic tunnel to achieve the objective of intersystem roaming in heterogeneous wireless networks. Mobile IPv6 is improved to be adaptive to IPv4 network. The 6to4 automatic tunnel simplifies the complexity of tunnel configuration. Moreover, the NAT-PT avoids the overhead of tunnel to have high bandwidth utilization. The proposed mechanism keeps the network architectures of heterogeneous wireless networks unchanged. Therefore, it is suitable for emerging wireless networks, for example, IEEE 802.16. A testbed is constructed. The proposed mechanism is implemented under Linux. It enables users to enjoy high data transmission rate and large service coverage. It also provides users with the ability of maintaining communicating sessions even after roaming.