An enhanced inter-access point protocol for uniform intra and intersubnet handoffs

An enhanced IEEE 802.11 inter-access point protocol (IAPP) is proposed to provide a unified solution for both intra and intersubnet handoff processes. The proposed enhancement relies on the access point's (AP's) interoperability with other APs, provided by the IP-based IAPP, so as to enable the intra and intersubnet link-layer frame buffering-and-forwarding. This enhancement not only eliminates frame losses during an intrasubnet handoff but, more importantly, realizes loss-free, fast intersubnet handoffs without modifying the IP-mobility protocols such as mobile IP. Our ns-2-based simulation results show that the intersubnet handoff process is transparent to the mobile host's TCP session. Moreover, the enhanced IAPP supports higher user mobility and achieves a higher TCP throughput - up to 50 percent improvement over the original IAPP.