A Fast Handoff Scheme of Ieee 802 . 11 Wireless Networks

The Handoff delay is one of the major problems in Wireless Network (WLN) that needs to be solved in order to allow time-critical and real-time applications run continuously during handoff. We have developed a fast handoff scheme called NodeScan (or MobileScan) to provide a novel use of channel scanning latency by employing open system authentication. This scheme comprises two steps: firstly a client device takes advantage of the WMN architecture to maintain a list of active mesh nodes. Secondly when handoff is required, a client transmits Authentication Request frames to all mobile nodes (MNs) from the list instead of broadcasting Probe Request frames as in an active scan to discover the available MNs. This fast handoff scheme is feasible by upgrading the software only on the client side. This paper compares the theoretical handoff latency of Mesh Scan with other approaches and we demonstrate the effectiveness of our through experiment.