Fast and Scalable Wireless Handoffs in Support of Mobile Internet Audio

this paper, we propose a scalable mobility management scheme for wireless internetworks. We employ a hierarchy to exploit the geographic locality inherent in user mobility patterns. The lowest level of the hierarchy optimizes the common case of movement between adjacent cells in the same subnetwork. It operates in the area near the mobile node and handles such motion without involving the mobile node's home network. The higher levels of the hierarchy rely on a more general mechanism like Mobile IP to handle the less frequent movement between subnetworks or administrative domains. Our scheme restricts mobility management traffic to the immediate area surrounding the mobile node, and thus reduces handoff latency and the load on the internetwork. Our handoff scheme applies to the Internet. It is based on IP [26] and integrates seamlessly with Mobile IP. Our base stations are network-layer routers, in contrast to the link-layer bridges commonly used by existing local-area wireless networks. These base stations use the gratuitous and proxy features of the Address Resolution Protocol (ARP) [24] to maintain the illusion that wireless hosts reside on a wired link. An IP-based routing solution offers two advantages over the link-layer bridging approach. First, a base station can filter traffic based on IP multicast groups. It can participate in the Internet Group Management Protocol (IGMP) [8] and forward only that multicast traffic for which there is an interested receiver. Such filtering is especially important given the limited bandwidth of wireless links. Second, a base station can differentiate between packet types based on the Type of Service field in current IP headers, or the Flow ID field in next-generation IP headers [9]. Careful packet scheduling is especially importa..