Device-Transparent Network-Layer Handoff for Micro-Mobility

An emerging class of applications for enterprise Wireless LANs (WLAN) is Voice over IP (VoIP) applications, which impose a stringent requirement on end-to-end delay. Because access points on an enterprise WLAN tend to be associated with different IP subnets, support for network-layer handoff is indispensable. Moreover, the handoff frequency is expected to be much higher for WLANs than for cellular networks because the coverage of a WLAN access point is much smaller. Although mobile IP is a mature solution to the network-layer handoff problem, no known mobile IP implementation on IEEE 802.11 WLANs can reduce the handoff latency below 100 msec, a nominal requirement for VoIP applications.