Wi-Fi service discovery over 802.11u using non-native generic advertising services (GAS-SD)

Croft, John Michael
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Public and private Wi-Fi hotspot providers have a strong interest in serving targeted, localized network applications to their users. A variety of functions that currently require personal attention (such as ordering coffee, table availability notifications, store inventory searches, access to the local newspaper, and more) can be provided to mobile devices without requiring the customer to wait for someone to help them. Many of these services are available today on smartphones and web apps, if users work hard enough to find them. Providing tailored offerings to local clients without forcing them to find and download a custom application requires both a way to notify users who are in a venue and an agreed-upon format for service announcements. While the IEEE's 802.11 Task Group U has broadly defined "Generic Advertising Services" (GAS) that an AP can use to inform clients of available resources, in practical terms this capability is not commonly used for anything except "Native GAS" advertisements of Internet connectivity providers. "Non-Native" service advertisements use the same transport but have no agreed-upon, non-proprietary standard for sending information between devices and service providers. With a common service description format, "Non-native GAS" frames in IEEE 802.11u beacons enable Wi-Fi Access Points (APs) to advertise discoverable services to client devices, providing the underlying support needed to enable a wide variety of applications without a difficult discovery process for the user. This report defines Generic Advertising Services-Service Discovery (GAS-SD) as a common, freely-available service description format to be used between device software, 802.11u capable APs, and backend services to enable service discovery. It demonstrates such a service in use, provides sample data and a Document Type Definition (DTD) that can be used to define additional services, and describes a number of use cases for GAS-SD in public hotspot locations.