802.11d Channels

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.

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.

3. How does 802.11d affect channel usage?

802.11d specifies which channels can be used legally in different countries, based on local regulations.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

15. Does enabling 802.11d affect performance?

Not directly. It ensures legal operation but does not inherently boost or reduce performance.

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.

17. Do all access points support 802.11d?

Most modern access points support it, especially those designed for global markets or enterprise use.

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.

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.

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.

Topics in this section,

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)

  • channel widths

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)

  • Reference links