基于AP预先转发的802.11无线局域网切换机制研究

IEEE802．11无线局域网(WLAN)规范包括MAC子层和物理层(PHY)两个协议层，支持结点的移动通信，但它并没有提供移动主机(MH)的无缝切换算法．当MH从当前的接入点(AP)覆盖小区移动到另一个AP小区时，由于通信的暂时中断会对系统的性能造成一定的影响．目前的切换算法包括硬切换(hard-handoff)和平滑切换(smooth-handoff)等，这些算法要么丢包率大，要么切换延迟长，对切换的性能改善程度并不是很高．从切换延迟和丢包率两方面人手，提出了一种AP预先转发的WLAN切换算法，并对其进行了仿真实验研究，实验结果表明，该切换算法的整体性能优于其他算法．

Research on the Handoff Mechanism of 802.11 WLAN Based on AP Pre-Forward

The IEEE 802.11 wireless LAN protocol includes sub-MAC layer and PHY layer. It supports mobile communication of a host, but a handoff algorithm is not supplied. When a mobile host (MH) moves from one AP coverage to another, the performance will be effected by the connection disruption. Some handoff methods are supplied by literatures, such as hard-handoff and smooth-handoff. But the performance of them are not high. From the aspects of handoff latency and loss rate, a novel handoff scheme based on AP pre-forward is proposed and its simulation is carried out. The simulation result shows that the whole performance of the proposed algorithm is higher than others.