IEEE 802.11d is an amendment approved in 2001 to the 802.11 Wireless LAN specifications, which allows clients to automatically configure themselves to their local regulatory domain.
IEEE 802.11d is an amendment approved in 2001 to the 802.11 Wireless LAN specifications, which allows clients to automatically configure themselves to their local regulatory domain. The AP beacon includes the country code for the region it is operating in.
This was done to make it easier for smaller countries that are not part of a larger domain like North America or Europe to configure its clients to the correct operating bands/channels for that country. This is known as world or world-wide mode.
How does 802.11d work?
At initialization the client will passively scan or listen to channels 1 to 11 in the 2.4 GHz band. If a client detects and sees beacons from an AP, the client will switch to actively probe for SSID’s (Service Set Identifier). When the client finds the appropriate AP and receives the country information, it will configure itself with that regulatory domain, and transmit on channels in the frequency band available for that domain/country.
FCC disallowed 802.11d after January 01, 2015
After January 01, 2015, the FCC disallowed the use of 802.11d. The client cannot rely on the access point to ensure compliance to the FCC certified frequency bands. Previously, a non-U.S. AP could be used in the US, which will allow transmitting on channels 12 & 13 with unapproved power output in the 2.4 GHz band, or channels channels which are prohibited in the 5 GHz band. Today, if sold in the U.S. the client module must be configured for U.S. use only.