Generic Advertisement Service (GAS) is an
IEEE 802.11u service that provides over-the-air transportation for frames of higher-layer advertisements between Wi-Fi stations (802.11 Stations) or between a server in an external network and a station. GAS may be used by stations prior to authentication, or association to a
wireless Access Point
In Computer networking device, computer networking, a wireless access point (WAP) (also just access point (AP)) is a networking hardware device that allows other Wi-Fi devices to connect to a wired network or wireless network. As a standalone ...
(AP) in a
Basic Service Set (BSS). GAS supports higher-layer protocols that employ a query/response mechanism.
In a BSS infrastructure, the purpose of Generic Advertisement Service (GAS) is to enable a station to identify the availability of information related to network services.
While the specification of network services information is out of scope of IEEE 802.11, there is a need for stations to query for information on network services provided by SSPNs or other external networks beyond an AP (Access Point) before they associate to the wireless LAN. GAS defines a generic container to advertise network services information over an IEEE 802.11 network. Public Action frames are used to transport this information.
There are a number of reasons why providing information pre-association is beneficial.
* It supports more informed decision making about an IEEE 802.11 infrastructure with which to associate. This is generally more efficient than requiring a non-AP STA to associate with an AP before discovering the information and then deciding whether or not to stay associated.
* It is possible to query multiple networks in parallel.
* The station can discover information about APs that are not part of the same administrative group as the AP with which it is associated, supporting the selection of an AP belonging to a different IEEE 802.11 infrastructure that has an appropriate SSP roaming agreement in place.
See also
*
Generic Access Network
Wi-Fi calling, also called VoWiFi, refers to mobile phone voice calls and data that are made over IP networks using Wi-Fi, instead of the cell towers provided by cellular networks. Using this feature, compatible handsets are able to route ...
*
GSM
The Global System for Mobile Communications (GSM) is a family of standards to describe the protocols for second-generation (2G) digital cellular networks, as used by mobile devices such as mobile phones and Mobile broadband modem, mobile broadba ...
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GPRS
General Packet Radio Service (GPRS), also called 2.5G, is a mobile data standard on the 2G cellular communication network's Global System for Mobile Communications, global system for mobile communications (GSM). Networks and mobile devices wit ...
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UMTS
The Universal Mobile Telecommunications System (UMTS) is a 3G mobile cellular system for networks based on the GSM standard. UMTS uses Wideband Code Division Multiple Access, wideband code-division multiple access (W-CDMA) radio access technolog ...
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CDMA
Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communicatio ...
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EV-DO
Evolution-Data Optimized (EV-DO, EVDO, etc.) is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. EV-DO is an evolution of the CDMA2000 ( IS-2000) standard which ...
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IEEE 802.21 Media Independent Handover
External links
{{IEEE standards
IEEE 802.11, U