Tuesday, September 02, 2008

Wi-Fi Gets Roaming

A long awaited (at least from UMA Today’s perspective) Wi-Fi specification was finally ratified by the IEEE last week. The 802.11r specification lets Wi-Fi devices roam quickly between Wi-Fi access points within a network.

Officially known as ‘fast basic service set transition’, the concept behind 802.11r is to enable a device to establish access to and qualifications of a neighbor Wi-Fi access point before transitioning from the current AP.

For a dual-mode handset call, this capability is critical. Because UMA relies on an IPSec tunnel anchored on the handset, the phone must receive the same IP address from the new AP as it currently has from the current AP before it can roam. Without a constant IP address, the IPSec tunnel fails and the call transitions back to the macro RAN (not a tragedy, but a hassle).

The 802.11r spec has been in the works since 2005 and finally crossed the finish line. Look for it in devices and APs shortly.

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