Evaluation of authentication interworking methods among multiple WLAN service providers

The interworking technologies to combine multiple WLANs into a single virtual system have not been studied extensively, particularly for legacy wireless networks. In this paper, we study how to provide the inter-domain authentication among multiple WLAN service providers with minimum overhead. We introduce five inter-domain authentication methods, referred to as Info-Sharing, AP-Seq, AP-Con, AS-Seq and AS-Con, which are designed in the form of an extension to the standard IEEE 802.1x and EAP protocols. In order to evaluate these methods, we compare their authentication time, implementation cost, confidentiality, flexibility and increment of messages. From the evaluation with analysis and experiments, we show that the AS-Con method can provide the authentication interworking function with minimal overhead on legacy network equipments. Also it is shown that, even though the authentication of AS-Con takes longer than the previous method, their difference is under one second and insensitive to users.