IEEE 802.11u standard | Hotspot 2.0 standard

This page describes IEEE 802.11u version of WLAN standard.This 802.11u standard is used for Hotspot 2.0.

There are two techniques for mobile data offloading. They are femtocell and wifi. Mobile data offloading means use of other network technologies which helps deliver data originally targeted for the cellular users. It is alternative to cellular wireless data communication with best performance.

Femtocell is a small base station which connects with service provider's network via broadband connectivity. Refer femtocell tutorial for more.
The other mobile data offloading technology is wifi which uses unlicensed spectrum. The standard 802.11u provides capabilities for better interworking with external networks such as 3G, 4G etc. Before 11u, 3G subscribers were using wifi network to satisfy their need for internet services. After enhancement of features in IEEE 802.11u, usage of wifi network has increased. This is due to provision of interworking information in the beacon frame. Hence mobile device will decide for the network before initiating association request. Due to this roaming between wifi service providers and cellular service provides have become available. The roaming can be established easily and the information for the same can be transmitted or advertised in beacon frame itself. This 3G-WLAN interworking is specified in 802.11u standard.

How Hotspot2.0 Works as per IEEE 802.11u?

IEEE 802.11u Hotspot2.0 network

IEEE 802.11u compliant network having 11u compliant radio signal is known as Hotspot2.0. The devices used in Hotspot2.0 network are known as HS2.0 capable device(i.e. client) and HS2.0 capable AP. This standard is based on IEEE 802.11-2007 standard and it defines PHY and MAC layer specifications. 802.11u mentions adds amendment for inter-working with the external networks(e.g. cellular).

Figure depicts Hotspot2.0 network as defined in IEEE 802.11u standard. Let us see how Hotspot2.0 works:
   AP beacons with HS2.0 capabilities. The device(STATION) probes with HS2.0 support.
  The device selects the AP performs ANQP Request and determines capabilities of the AP and also which service providers are available.
  The AP responds to ANQP query and provides the information to the device as requested.
  The device compares the information received(provisioned profile) with available and associates with the best BSSID.


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