802.11d Channels ====================== .. 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 **1. What is IEEE 802.11d?** IEEE 802.11d is an amendment to the 802.11 standard that enables Wi-Fi operation in additional regulatory domains by defining country-specific frequency and channel usage. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **2. Why was 802.11d introduced?** It was introduced to support international roaming and to comply with regulatory domain restrictions specific to each country or region. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **3. How does 802.11d affect channel usage?** 802.11d specifies which channels can be used legally in different countries, based on local regulations. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **4. What is a regulatory domain in Wi-Fi?** A regulatory domain refers to a region or country that has its own laws regarding frequency usage, power levels, and permissible channels for wireless communication. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **5. How does 802.11d work with 2.4 GHz channels?** It helps ensure that only the channels allowed in the local regulatory domain are used, such as 1–11 in the US, 1–13 in Europe, and 1–14 in Japan. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **6. What is the significance of channel 14 in 802.11d?** Channel 14 is only allowed in Japan, and 802.11d ensures that devices only use it when operating in Japan. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **7. Can a Wi-Fi device automatically switch channels based on country?** Yes, with 802.11d support, devices can adjust to the appropriate channel set upon receiving country information from access points. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **8. How is country information communicated in 802.11d?** It is communicated via the Country Information Element in beacon and probe response frames from access points. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **9. Is 802.11d mandatory for all Wi-Fi devices?** While not strictly mandatory, it is essential for devices intended for global use or that support international roaming. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **10. Does 802.11d apply only to 2.4 GHz?** No, it applies to both 2.4 GHz and 5 GHz bands, helping to enforce legal usage across all supported frequencies. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **11. How does 802.11d improve safety and compliance?** It prevents interference with restricted frequencies, radar systems, or emergency bands by adhering to local laws. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **12. Can 802.11d restrict available Wi-Fi channels?** Yes, based on the country code, the device will disable channels that are not allowed in that region. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **13. What is a country code in 802.11d?** It is a two-letter code (like "US" or "JP") used to define legal Wi-Fi operation parameters in that country. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **14. Is 802.11d the same as DFS (Dynamic Frequency Selection)?** No. DFS is related to radar detection and dynamic frequency adjustment, while 802.11d focuses on regional compliance and legal channel selection. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **15. Does enabling 802.11d affect performance?** Not directly. It ensures legal operation but does not inherently boost or reduce performance. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **16. What happens if a device ignores 802.11d settings?** It may operate illegally, risk interference with protected services, or fail certification in some countries. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **17. Do all access points support 802.11d?** Most modern access points support it, especially those designed for global markets or enterprise use. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **18. Can 802.11d be disabled?** Yes, some devices allow it to be disabled, but this may violate regulations in some regions and prevent proper operation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **19. How is 802.11d related to 802.11h?** 802.11d focuses on regulatory domain support; 802.11h adds dynamic frequency selection (DFS) and transmit power control (TPC), especially in 5 GHz. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **20. Is 802.11d still relevant in modern Wi-Fi?** Yes, especially for international products and in multi-country deployments where regulatory compliance is essential. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`List of channels <802_11d_channels_step4>` * :ref:`List of channel widths <802_11d_channels_step5>` * :ref:`List of Bands <802_11d_channels_step6>` * :ref:`Reference links <802_11d_channels_step17>` .. _802_11d_channels_step4: .. tab-set:: .. tab-item:: List of channels (802.11d - Country-Specific) ===================== ======================= ================================ Channel Number (MHz) Center Frequency (MHz) Frequency Range (MHz) ===================== ======================= ================================ 1 2412 2401 – 2423 2 2417 2406 – 2428 3 2422 2411 – 2433 4 2427 2416 – 2438 5 2432 2421 – 2443 6 2437 2426 – 2448 7 2442 2431 – 2453 8 2447 2436 – 2458 9 2452 2441 – 2463 10 2457 2446 – 2468 11 2462 2451 – 2473 12 2467 2456 – 2478 (Europe/Asia) 13 2472 2461 – 2483 (Europe/Asia) 14 2484 2473 – 2495 (Japan only) 36 5180 5170 – 5190 (5 GHz, US/Canada) 40 5200 5190 – 5210 (5 GHz, US/Canada) 44 5220 5210 – 5230 (5 GHz, Europe) 48 5240 5230 – 5250 (5 GHz, Europe) 149 5745 5735 – 5755 (5 GHz, US) 153 5765 5755 – 5775 (5 GHz, US) 157 5785 5775 – 5795 (5 GHz, US) 161 5805 5795 – 5815 (5 GHz, US) 165 5825 5815 – 5835 (5 GHz, US) ===================== ======================= ================================ .. _802_11d_channels_step5: .. tab-set:: .. tab-item:: List of channel widths * channel widths .. _802_11d_channels_step6: .. tab-set:: .. tab-item:: List of Bands (802.11d) ============================== ====================== ======================= =============================== Band Name Frequency Range (GHz) Frequency Range (MHz) Channels (Region-Specific) ============================== ====================== ======================= =============================== 2.4 GHz ISM Band 2.400 – 2.4835 2400 – 2483.5 1 – 14 (varies by region) 5 GHz U-NII Band (Lower) 5.150 – 5.250 5150 – 5250 36, 40, 44, 48 (US, EU, Asia) 5 GHz U-NII Band (Middle) 5.250 – 5.350 5250 – 5350 52, 56, 60, 64 (DFS required) 5 GHz U-NII Band (Upper) 5.470 – 5.725 5470 – 5725 100 – 140 (DFS, TPC in EU) 5 GHz U-NII Band (Extended) 5.725 – 5.825 5725 – 5825 149, 153, 157, 161, 165 (US) 5 GHz ISM Band (Some regions) 5.825 – 5.875 5825 – 5875 Region-specific (e.g., China) ============================== ====================== ======================= =============================== .. _802_11d_channels_step17: .. tab-set:: .. tab-item:: Reference links * Reference links