IEEE 802.11h-2003, or just 802.11h, refers to the amendment added to the IEEE 802.11 standard for Spectrum and Transmit Power Management Extensions. It solves problems like interference with satellites and radar using the same 5 GHz frequency band. It was originally designed to address European regulations but is now applicable in many other countries. The standard provides Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to the 802.11a PHY. It has been integrated into the full IEEE 802.11-2007 standard.
IEEE 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, 802.11g, and 802.11n versions to provide wireless connectivity in the home, office, and some commercial establishments.
Wireless technology has been more and more popular and a lot of standards have been finalized over the past decade. This holds especially for ISM bands (Industrial, Scientific and Medical) which are unlicensed and free to use. The problem, however, is the coexistence between these heterogeneous wireless networks. To address the coexistence problems in those bands, the IEEE has started the 802.11h Working Group to make recommendations for better future coexistence. It solves problems like interference with satellites and radar using the same 5 GHz frequency band.
DFS ensures that channels containing radar are avoided by an Access Point (AP) and energy is spread across the band to reduce interference to satellites. TPC ensures that the average power is less than the regulatory maximum to reduce interference to satellites.
The IEEE 802.11h standard provides an additional 11 channels to the 802.11a standard’s 12 non-overlapping channels for a total of 23 non-overlapping channels.