Micro-mobility management and Freeze-TCP implementation in a wireless network.

摘要

With wireless products becoming cheaper, there has been an increased number of mobile users accessing to the Internet wirelessly. With the growing desire to be always on-line, there is a requirement for mobility management of mobile terminals between homogeneous systems, such as access to the wireless LAN in the office or during meeting. Two main issues of research reported in this thesis are related with building a working micro-mobility testbed and an enhancement to the current standard TCP to improve its performance over a micro-mobile wireless network. A survey of recently proposed micro-mobility protocols is presented, highlighting the protocol features that providing mobility management support to mobile nodes across the Internet. Also a detailed procedure is presented of how a successful micromobility testbed can be built, based on the Cellular IP protocol. The results show that the Cellular IP mobile host successfully performs seamless handoffs with no packet loss and maintains connectivity while running a video session over wireless interfaces. Lastly, the thesis presents an investigation of the current problems faced by standard TCP in the wireless environment and describes recently proposed TCP enhancement schemes for wired-wireless networks. Freeze-TCP has been chosen to be implemented into the micro-mobility testbed to interwork with Cellular IP that replaces standard TCP to enhance TCP performance during handoffs. The results show that Freeze-TCP provides up to 41% improvement in TCP throughput compared to standard TCP.