802.11d PHYs ============== .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is IEEE 802.11d?** IEEE 802.11d is an amendment that adds support for additional regulatory domains to the 802.11 standard, enabling devices to operate in different countries with country-specific parameters. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11d define a new PHY?** No, 802.11d does not introduce a new PHY; it enhances existing PHY layers by providing mechanisms to support new frequency bands and channels based on regulatory requirements. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the purpose of the country information element in 802.11d?** It allows access points to broadcast regulatory information such as allowed channels and transmit power limits to clients. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11d affect channel selection?** Devices dynamically adjust the set of available channels according to country-specific regulations communicated via 802.11d. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What MAC layer changes does 802.11d introduce?** It adds support for transmitting and processing the country information element in beacon and probe response frames. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11d improve interoperability?** By ensuring devices comply with local regulations automatically, 802.11d enables seamless roaming across different regulatory domains. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What frequency bands are supported by 802.11d?** 802.11d supports operation on both 2.4 GHz and 5 GHz bands, with region-specific channels as allowed by local regulations. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11d modify timing parameters at MAC?** It can modify timing parameters indirectly by adjusting allowed channel usage and regulatory restrictions but does not change core MAC timing functions. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does a client device learn about country regulations?** Through the country information element broadcasted in beacon frames by the access point or infrastructure network. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What happens if a device does not support 802.11d?** It may not operate legally or efficiently in certain countries as it cannot adjust to region-specific parameters dynamically. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11d impact channel availability?** It restricts or enables channels according to local regulations, preventing illegal transmission on forbidden frequencies. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11d affect transmit power?** Yes, 802.11d enables devices to adjust their transmit power to comply with country-specific limits. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11d mandatory for all 802.11 devices?** No, but many devices implement it to meet global regulatory compliance and enable international roaming. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11d handle multi-domain roaming?** Devices switch regulatory settings on the fly by reading updated country info elements as they roam between regions. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What frame types carry the 802.11d country information element?** Primarily beacon frames, probe responses, and sometimes association request frames. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11d specify changes to security?** No, 802.11d focuses on regulatory compliance and does not affect security protocols. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is 802.11d related to 802.11h?** Both address regulatory issues, but 802.11h focuses on dynamic frequency selection and transmit power control in 5 GHz, while 802.11d adds regulatory domain info for all bands. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Can 802.11d support new countries after deployment?** Yes, by updating the country information elements broadcast by APs, new regions can be supported without firmware upgrades to clients. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11d impact throughput?** Indirectly—by limiting channels or power levels, it can affect available bandwidth and performance. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What must firmware developers do to implement 802.11d?** They need to implement parsing and adherence to country information elements and adjust radio parameters dynamically. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links <802_11d_phy_step17>` .. _802_11d_phy_step17: .. tab-set:: .. tab-item:: Reference links * Reference links