UBC Theses and Dissertations
Handoff enhancement in mobile-ip environment Woo, William
Numerous efforts have been made in extending network connectivity to mobile computers using the Internet as a backbone. The Internet Engineering Task Force (IETF) has compiled a series of technical discussions into a basic IETF mobile-IP draft proposal. At the time of writing, the draft is in the process of becoming an Internet standard. In addition to this extension, there is a compatible route optimization scheme, Internet Mobile Host Protocol (IMHP), which can be employed to improve routing efficiency of the basic proposal. In a Wireless and Mobile Data Network (WMDN), handoffs are required whenever a mobile host crosses cell boundaries. These handoffs introduce momentary disruptions and could significantly reduce the throughput at the transport layer. In this research, a new Handoff Enhanced scheme is introduced to further extend IMHP to improve both the routing efficiency and the transport layer performance during handoffs. This new scheme uses finite size buffers to store inbound datagrams for mobile hosts during handoffs. As a result, datagram losses are eliminated. This is found to improve the transport layer performance by a significant extent. The transport layer performance of the three different schemes were evaluated using the OPNET simulation package. It is found that the IMHP yields very poor performance at high handoff rates. With the new enhanced scheme, the transport layer performance improves significantly. Besides, the new enhanced scheme employs route optimization and gives better performance than the basic IETF scheme.
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