Network selection and discovery of service information in public WLAN hotspots

Abstract

In a public WLAN hotspot, a roaming mobile terminal (MT) may be within radio range of more than one access point (AP), each of which may or may not have roaming agreements with the service provider of the user of the MT. In this case, the MT may need to discover some service information before it can make an intelligent network-selection decision. The most critical is roaming information; while other information such as security policies, price, AP workload may also be useful. Currently, roaming information is typically provisioned on the MTs as static roaming tables or roaming lists. However, this approach may not scale well when there are millions of hotspots globally. Addressing this shortcoming, recently several solutions have been proposed by different groups. In this paper, we contrast these solutions, and propose our own solution called Roaming Information Code (RIC), which can be transported as SSID or a new Information Element of the 802.11 standard. RIC is scalable and can be fully backward compatible with existing APs (if transported as SSID). Furthermore, it does not hinder fast handoffs. In the second half of the paper, we will also discuss two other schemes addressing the other service information: a scheme called RIC-VAP for provider-specific security information; and a scheme that allows an AP to announce price and workload information.