无线局域网中基于隧道的平滑切换机制

在低切换延迟移动IPv4的延迟注册切换和代理缓存技术的基础上,提出了IEEE 802.11无线局域网中使用双向边隧道的一种平滑切换机制.该机制缩减了不适用于无线局域网的链路层触发,结合提出的减少链路层和网络层切换时延的手段,在实现平滑切换的基础上,进一步减少了切换时延,更好地接近无缝切换的要求.仿真实验表明,该机制不仅有效降低了切换过程中丢包的发生,同时也减少了平均500 ms以上的切换时延,使TCP的有效吞吐量提高了70%左右,极大地改善了无线局域网中站点的切换性能.

A New Smooth Handoff Mechanism with Tunnel for Wireless Local Area Network

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 500 ms in average.The throughput of TCP is increased approximately by 70%.Therefore the handoff performance of wireless LAN is considerably improved.