Abstract: Based upon post-registration handoff mechanism in low latency mobile IPv4 and mobile agent buffer technology, a smooth handoff mechanism with bi-directional edge tunnel is presented for IEEE 802.11 wireless LAN. Combined with the proposed methods for reducing handoff latency at link layer and network layer, this mechanism reduces link layer triggers. This is not feasible in 802.11 wireless LAN. By realizing smooth handoff, handoff latency is reduced, and seamless handoff is more closely approached. Simulation experiments indicate that the mechanism not only reduces the possibility of packet loss in the process of handoff, but also lowers handoff latency by more than 500ms in average. The throughput of TCP is increased approximately by 70%. Therefore the handoff performance of wireless LAN is considerably improved.

Key words:

mobile IP, smooth handoff, post registration, IEEE 802.11, link-layer trigger