Research On Fast Handoff In Secure Ieee802.11s Wireless Mesh Networks

802.11Wireless Mesh Network has been widely studied in recent years due to its combination of high speed access ability of WLAN and self-organization of ad hoc network. This paper takes802.11s Wireless Mesh Network for the study and focuses on fast handoff technology when terminal roams in the Wireless Mesh Network. When STA roams within the Wireless Mesh network, due to the limited coverage of an MAP, STA will move from the current AP’s coverage to another’s. Fast handoff will occur to ensure the QoS of services. However, the delay of handoff process defined by current IEEE802.11standard is too large to meet real-time application’s requirements (typically real-time application needs handoff latency less than50ms). This paper strives to introduce new switching scheme as much as possible to reduce handover delay and packet loss rate based on in-depth research on current fast handoff technologies.This paper analyzes the fast handoff procedure defined by IEEE802.11standard and relevant research works about fast handoff firstly. On this basis, this paper starts work in the following area:(1) Based on full channel scanning scheme and selective channel scanning scheme which has poor efficiency on improving handoff latency, this paper proposes an new channel scanning scheme named channel grouping channel scanning. It is proved by simulation that the proposed scheme has high efficiency on decreasing handoff delay and packet loss rate.(2) This paper designs a unified security domain in which MPP replaces MAP for STA certification. It avoids re-authentication phase when STA roams in the Mesh network. Proved by simulation using NS-2, the new security scheme can not only ensure the security of802.11i, but also has a lower handoff delay compared with standard802.11i security protocol.(3) For heterogeneous wireless mesh network inter-domain handoff, this paper presents the best network selection algorithm based on fuzzy analytic hierarchy process with capable of considering the terminal characteristics, service type and network QoS performance.