Experimental Performance of the Handover Procedure in a WiFi Network

An experimental evaluation of the handover performance in a 802.11b (WiFi) network has been obtained in terms of available bandwidth and handover latency. The network consists of two access points connected to a wired LAN and a measurement setup composed by laptop PCs, equipped with WiFi cards, on which a sniffer is used to capture all the packets transmitted on the radio link. Applications considered are streaming and ftp-like applications. The analysis of the handover delay is performed, showing the dependence on the network configuration parameters and results, both at the MAC and UDP/TCP layer are presented, to show how applications can suffer the handover latencies. It will be shown that these latencies can vary significantly for the same configuration of mobile stations and APs and that the primary source of delay is the scan procedure used to discover the new access point. Keywords— Wi-Fi, 802.11b, handover.