Study And Implementation Of Handoff Technology In 3G-WLAN Interworked Networks

WLANs provide high data rates with small network coverage and limited mobility. On the contrary,3G cellular networks provide lower data rates with higher mobility. The integration of the two kinds of networks for advantages complement may enhance the efficiency and flexibility of wireless transmission services, which becomes the trend of next generation telecommunication network. How to ensure that mobile terminal can access heterogeneous networks adaptively and safely, how to guarantee QoS when mobile terminal handoffs in heterogeneous networks are hot issues in the research field. This paper focuses on the secure integration architectures of 3G-WLAN and seamless handoff as follows:(1) The available integration architecture of 3G and WLAN supports mobility poorly. This paper proposes an integration model based on Mobile IP to achieve adaptive handoff control.(2) In order to minimize ping-pong effect in available handoff decision algorithm, a vertical handoff decision algorithm is proposed, which is based on grey prediction and fuzzy logic theory with higher accuracy.(3) Based on the new integration architecture, this paper designs a handoff scheme which can implement vertical handoff rapidly and smoothly in order to obtain lower packet loss rate and lower latency (small time delay).(4) To verify the proposed handoff scheme, this paper combines it with the integrated authentication to construct a secure access platform for integration network. The implementation of the platform verifies the proposed network architecture and handoff algorithm.The results demonstrate that the proposed integration network architecture, handoff algorithm and handoff scheme have strong compatibility, low latency as well as minimal packet loss. Meanwhile, by reducing the ping-pong effect, the mobile terminals can move freely in the 3G-WLAN integrated networks with higher communication quality.