Real-Time Adaptive Link Layer Trigger Based Cross Layer Fast Handoff Mechanism in IEEE 802.11 WLANs

The Fast handoff for Mobile IPv6 (FMIPv6) and the Synchronized Scan are the most popular solutions to reduce the handoff latency in link layer and network layer respectively. However, like most previous work on reducing the handoff, they do not consider the affection of fluctuation in wireless networks. And as we know, most existing works concentrate on either the link layer handoff or the network layer handoff. However, when using FMIPv6 in the real IEEE 802.11, the link layer trigger is hard to control, so it is difficult to make sure that the MN goes into the predictive mode with the correct prediction with the predefined parameters. In this paper, we proposed the real-time adaptive link layer triggering (RALT) scheme utilizing FFT. It is unveiled that, the FFT-based signal strength decay detection is a feasible method to detect the signal variations of the current AP. Considering both the link layer handoff latency and the network layer handoff latency, the extended FMIPv6 and SynScan integration mechanism based on RALT (FSIR) is proposed to achieve fast handoff in the real IEEE 802.11 WLANs. And we validated the FSIR proposed here through simulation, simulation results show that fast handoff can be achieved under different situations when FSIR is used.