T Design , Implementation , and Evaluation of Cellular IP

development of commodity based palmtop devices with built-in high-speed packet radio access to the Internet will have a major impact on the way we communicate. Large numbers of mobile users equipped with wireless IP-enabled communicators will have access to a wide array of Web-based mobile multimedia services. Future wireless network infrastructure will have to support a wide variety of users, applications, and access needs. While access rates for traditional services such as mobile telephony are well understood , requiring small and fixed-size bandwidth allocation, wireless data rates may vary by a number of orders of magnitude. Regulatory and environmental factors influence access speed, service quality, and pricing policy. For example, outdoor wireless access will remain at lower speeds and premium rates compared to unlicensed indoor communications. High-speed access can be achieved by using smaller and smaller cell sizes, resulting in coverage areas with a larger number of base stations. One can imagine a scenario where each person's office has its own access point offering tens to hundreds of megabits per second of wireless access. These types of picocellular environments call for simple, low-cost wireless infrastructure that ultimately must compete with wireline LAN service quality, costs, security, and plug-and-play scalability. Mobile users will expect the same level of service quality as wireline users. That will translate to high-speed access with seamless mobility, which we define as the ability of the network to support fast handoff between base stations with low delay and minimum or zero packet loss. As base station density increases, however, so will handoff rates. This places significant demands on future mobile network architecture , protocols, and services to support seamless mobility. Recent initiatives to add mobility to the Internet have mostly focused on the issue of address translation [1] through the introduction of location directories and address translation agents. The problem of address translation is fundamental to global Internet mobility and comes from the hierarchical nature of IP addressing. In Mobile IP [2] packets addressed to a mobile host are delivered using regular IP routing to a temporary address assigned to a mobile host at its actual point of attachment. This approach results in a simple and scalable scheme that offers global mobility. Mobile IP is not appropriate, however, for seamless mobility because after each migration a local address must be obtained and communicated to a possibly distant location directory or home agent (HA). We believe that support …