IEEE 802.11h


IEEE 802.11h is an amendment to the IEEE 802.11 standard for wireless local area networks (WLANs). It was introduced to address regulatory requirements, particularly in Europe, and improve spectrum and transmission power management. The 802.11h mainly enhances existing protocols by adding Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) features to support 5 GHz frequency bands used in Wi-Fi communications.


The phonetics of the keyword “IEEE 802.11h” are as follows:I – /aɪ/ (as in “eye”)E – /iː/ (as in “bee”)E – /iː/ (as in “bee”)E – /iː/ (as in “bee”)(space)8 – /eɪt/ (as in “eight”)0 – /ˈziːroʊ/ (as in “zero”)2 – /tuː/ (as in “two”)(dot)1 – /ˈwʌn/ (as in “one”)1 – /ˈwʌn/ (as in “one”)(letter “h”) – /eɪtʃ/ (as in “hotel”, using NATO Phonetic Alphabet)To say it fluently: “Eye-triple-E eight-zero-two point one-one-hotel”

Key Takeaways

  1. IEEE 802.11h, also known as Spectrum and Transmit Power Management Extensions, is a standard that enhances the operation of WLANs in the 5 GHz frequency band, addressing issues such as interference with radar and satellite communications.
  2. Two primary features of IEEE 802.11h are Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC). DFS helps avoid interference with other systems by dynamically detecting and selecting available frequency channels, while TPC manages the transmit power levels to reduce the potential for interference.
  3. As a result of these features, IEEE 802.11h provides better coexistence with other wireless systems, improved spectrum utilization, and increased overall network performance in 5 GHz bands, making it more suitable for use in densely populated and regulated environments.


IEEE 802.11h is an important technology term as it refers to the amendment made to the original IEEE 802.11 standard, which is known for establishing wireless local area network (WLAN) protocols.

This specific amendment, introduced in 2003, was designed to address the increased concerns over interference with existing radar and satellite communication systems, by incorporating Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) mechanisms into WLANs.

Enhanced by these mechanisms, wireless equipment can avoid interfering with other systems, thus improving the overall performance of wireless networks by identifying and utilizing unused frequency channels and minimizing transmission power while maintaining the required signal quality.

This amendment also contributed to the harmonization of the international regulations on WLAN frequencies and has enabled the successful deployment of wireless networks in the worldwide 5GHz frequency band.


IEEE 802.11h, also known as Spectrum and Transmit Power Management Extensions, is a wireless standard that was created to address certain limitations and regulatory requirements in wireless communication, particularly within the 5 GHz frequency range. One of the primary goals of this standard is to minimize the interference of wireless networks with other devices operating in the same frequency band, such as satellite communication systems and radar equipment.

By incorporating various features like Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC), 802.11h ensures efficient utilization of radio spectrum, particularly in countries where the 5 GHz band is subject to strict regulations. The Dynamic Frequency Selection (DFS) feature in IEEE 802.11h enables wireless access points and devices to automatically switch to a less congested frequency channel when encountering interference from other systems.

This improves overall network performance and decreases the risk of interrupting other devices operating within the same frequency range. Similarly, Transmit Power Control (TPC) aims to reduce interference by adjusting the transmit power levels of wireless devices to the minimum level necessary to maintain reliable communication.

By implementing TPC, networks can minimize the potential for interference with neighboring networks while still providing robust connectivity for users. Together, these features make IEEE 802.11h an essential wireless standard for maintaining efficient and compliant operations in the increasingly crowded 5 GHz frequency range.

Examples of IEEE 802.11h

IEEE11h, also known as Spectrum and Transmit Power Management Extensions, is an amendment to the IEEE11 standard for wireless communication. It was introduced to address regulatory requirements in the 5 GHz (Unlicensed National Information Infrastructure or U-NII) band, specifically to protect certain radar systems and satellite communication. Here are three real-world examples of the technology in action:

Airport Radar Systems: Airport radar systems operate in the same frequency range as IEEE11h networks. Using Dynamic Frequency Selection (DFS), IEEE11h radios can detect the radar signals and automatically switch to a different, non-interfering channel. This ensures uninterrupted and smooth wireless communication, while also preventing interference with mission-critical radar systems.

Satellite Earth Stations: Satellites are essential for maintaining global communication systems, and their ground stations have sensitive equipment that may be impacted by interference from Wi-Fi networks. IEEE11h allows Wi-Fi devices to automatically adjust their transmit power, avoiding interference with nearby satellite earth stations. This power control also helps reduce overall radio interference, providing a cleaner signal for users.Corporate and Educational Campuses: In large Wi-Fi deployments, such as on corporate or educational campuses, proper spectrum management is crucial to ensuring efficient use of available channels and guaranteeing optimal performance. IEEE

11h allows access points to communicate with each other to optimize channel usage and transmit power settings, reducing interference and providing a smooth, reliable wireless experience for users.

FAQ: IEEE 802.11h

What is IEEE 802.11h?

IEEE 802.11h is an amendment to the IEEE 802.11 standard for wireless networking. It introduces enhancements to support spectrum and transmit power management in the 5 GHz frequency band, which is useful for minimizing interference with satellite, radar, and other systems operating in the same band.

Why was IEEE 802.11h developed?

IEEE 802.11h was developed in response to the growing need for wireless communication systems operating in the 5 GHz frequency band. Regulatory agencies like the European Telecommunications Standards Institute (ETSI) required the inclusion of specific spectrum and transmit power management features to minimize system interference, which led to the development of IEEE 802.11h.

What are the key features of IEEE 802.11h?

IEEE 802.11h introduces two main features: Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC). DFS helps the wireless network to avoid interference by automatically selecting the best available radio channel, while TPC adjusts the transmit power of wireless devices to ensure efficient use of the available spectrum and reduce the potential for interference.

How does IEEE 802.11h differ from other IEEE 802.11 standards?

While the core functionality of wireless networking remains the same among various IEEE 802.11 standards, 802.11h specifically addresses the unique requirements of the 5 GHz frequency band, with features like DFS and TPC. Other IEEE 802.11 standards focus on different aspects, such as improving overall data rates, network performance, and range, or catering to specific use cases and frequency bands.

Is IEEE 802.11h compatible with other IEEE 802.11 standards?

IEEE 802.11h is compatible with other 802.11 standards operating in the 5 GHz frequency band, such as 802.11a, 802.11n, and 802.11ac. However, as it is not designed to operate in the 2.4 GHz band, 802.11h is not directly compatible with 802.11b or 802.11g networks. Dual-band devices can support both 2.4 GHz and 5 GHz networks, ensuring compatibility with multiple IEEE 802.11 standards.

Related Technology Terms

  • Spectrum Managed Protocol
  • Dynamic Frequency Selection (DFS)
  • Transmit Power Control (TPC)
  • Wireless Local Area Network (WLAN)
  • Radar Detection

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