802.11h - Basics
What is IEEE 802.11h?
IEEE 802.11h is an amendment to the IEEE 802.11 standard aimed at improving spectrum and transmit power management in the 5 GHz band to avoid interference with radar systems.
Why was IEEE 802.11h developed?
It was developed to meet regulatory requirements in Europe and other regions, primarily to avoid interference with radar systems operating in the 5 GHz band.
What key features does 802.11h introduce?
It introduces Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to minimize interference with other users of the spectrum.
What is Dynamic Frequency Selection (DFS)?
DFS is a mechanism that detects radar signals and switches the Wi-Fi device to a different channel to avoid interference.
What is Transmit Power Control (TPC)?
TPC adjusts the transmit power of Wi-Fi devices to the minimum necessary to maintain communication, reducing interference with other systems.
In which frequency band does 802.11h operate?
802.11h operates primarily in the 5 GHz frequency band.
What regulatory issue does 802.11h address?
It addresses regulatory requirements for coexistence with radar and satellite systems in the 5 GHz spectrum.
How does DFS improve Wi-Fi performance?
By avoiding channels used by radar, DFS reduces interference, improving overall Wi-Fi network stability and throughput.
Is 802.11h mandatory in all countries?
No, it is mandatory in regions where regulatory bodies require radar detection and avoidance, such as Europe.
How does 802.11h affect channel selection?
It forces Wi-Fi devices to scan for radar signals before using a channel and to switch channels if radar is detected.
What is the difference between DFS and TPC?
DFS handles channel switching to avoid radar, while TPC manages the transmit power level to reduce interference.
Does 802.11h improve security?
No, 802.11h is focused on spectrum management and interference mitigation, not on security enhancements.
How does 802.11h impact Wi-Fi deployment?
It requires compliant devices to support DFS and TPC to operate legally in certain bands, influencing device design and network planning.
Can 802.11h be used with other Wi-Fi amendments?
Yes, 802.11h can be combined with other amendments like 802.11a, 802.11g, and 802.11n to provide enhanced features.
What happens if radar is detected on a channel?
Devices must stop transmissions on that channel and switch to a different channel where no radar is detected.
Does 802.11h increase network latency?
It can cause slight delays during channel switching, but generally, the impact on latency is minimal.
What types of devices benefit most from 802.11h?
Devices operating in the 5 GHz band, especially in regulatory domains that require radar coexistence, benefit most.
Is user intervention needed for DFS and TPC?
No, these functions operate automatically within compliant devices.
When was IEEE 802.11h ratified?
It was ratified in 2003 as an amendment to the original 802.11 standard.
How does 802.11h contribute to overall Wi-Fi ecosystem?
By ensuring regulatory compliance and reducing interference, it enables more reliable and wider deployment of 5 GHz Wi-Fi networks.
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