802.11h is an amendment to the 802.11 standard that addresses the regulatory requirements and coexistence issues associated with 802.11a operation in the 5 GHz band, particularly in Europe.
In Europe, there are strict regulations regarding the use of the 5 GHz band, particularly to protect radar systems from interference. 802.11h was introduced to ensure compliance with these regulations.
802.11h was introduced to address challenges related to radar interference by implementing regulatory compliance mechanisms such as DFS and TPC, ensuring the coexistence of wireless networks and radar systems in the 5 GHz band.
802.11h introduced the concept of Dynamic Frequency Selection (DFS), where wireless devices continuously monitor the spectrum for radar signals. If radar signals are detected, the devices must vacate the channel or reduce their transmit power to avoid interference.
Similar to Dynamic Frequency Selection (DFS), Transmit Power Control (TPC) is used to adjust the transmit power of wireless devices dynamically. If radar signals are detected, devices reduce their transmit power to minimize the potential for interference.
802.11h’s mechanisms for radar detection and avoidance improve the coexistence of Wi-Fi networks with radar systems in the 5 GHz band, ensuring regulatory compliance.
802.11h enables the use of 802.11a in regions with strict regulatory requirements, making it possible for Wi-Fi networks to operate in the 5 GHz band while avoiding interference with radar systems.