Tolerance to Access-Point Failures in Dependable Wireless Local-Area Networks

In one of the modes of operation defined by the IEEE 802.11 standard, mobile stations are connected to a wired network via an access-point that serves as a bridge between the wireless and the wired networks. If an access-point fails, then, all of the mobile stations connected to a wired network via the access-point can lose connectivity. In this paper, we address the problem of enhancing the dependability of wireless networks by focusing on tolerating access-point failures. We develop and evaluate a new fault-detection approach, based on signal-to-noise ratio, that promises to be more effective than heartbeats. We also describe and compare three techniques to recover from access-point failures in 802.11 wireless networks.