In this paper, we investigate the performance of Mobile IP regional registration and compare it with that of Mobile IP. The performance measures used are registration delay and the CPU processing overheads loaded on the agents to handle mobility of mobile nodes. Through the investigation, the effectiveness of adopting Mobile IP regional registration in the wide-area wireless network in terms of reducing the CPU processing overheads on the home agent and lowering the signaling delay is observed. We also compare the scalability of Mobile IP regional registration schemes when two and three levels of foreign agent hierarchy are considered. Based on the comparison, we propose a network design strategy for achieving optimized performance and cost.

Mobile IP can provide macro mobility for a mobile node (MN) instead of the original IP communication. Since the orignal Mobile IP does not consider micro mobility, it can not avoid handoff latency. The latency causes packets loss or large variations of the delivery times. To prevent it, several methods are proposed to improve the orignal Mobile IP handoff method. In our previous work, we proposed the fast registration method which enabled an MN to have two communication routes from the home agent (HA), and realized lower latency in the handoff procedures by the doublecasting on the two communication routes. But, the simulation results also show that the proposed method still has large overhead. This paper presents a seamless handoff method, which improves the fast registration method. In the method, the MN can know the first and second suitable base stations for the communications through information from the MAC media. The control helps for seamless handoff in case that the MN must frequently change its current base station (BS). The computer simulations for Constant Bit Rate (CBR) over real-time transport protocol (RTP) flow shows that the proposed method provides no handoff latency with low overhead even if the MN must occur frequent handoffs in a second.