802.11ax Channels
What are channels in 802.11ax?
Channels in 802.11ax refer to specific frequency ranges in both 2.4 GHz and 5 GHz bands (and optionally 6 GHz in Wi-Fi 6E) on which wireless devices communicate.
How many channels are available in 802.11ax?
The number of channels varies by frequency band: up to 14 non-overlapping 20 MHz channels in 2.4 GHz, and dozens in 5 GHz and 6 GHz bands depending on regulations.
What is a frequency band in wireless communication?
A frequency band is a specific range of frequencies within the radio spectrum used for wireless communication.
Which frequency band does 802.11ax operate in?
802.11ax operates primarily in 2.4 GHz and 5 GHz bands, with an extension to 6 GHz in Wi-Fi 6E devices.
What are UNII bands in 802.11ax?
UNII bands refer to regulatory-defined sections within the 5 GHz (and 6 GHz) spectrum used by 802.11ax for communication.
What are UNII-1, UNII-2, and UNII-3 bands?
They are subdivisions of the 5 GHz spectrum with specific channel allocations and usage restrictions, also extended into 6 GHz for newer UNII bands.
What is channel width in 802.11ax?
802.11ax supports multiple channel widths: 20 MHz, 40 MHz, 80 MHz, and 160 MHz, allowing greater data rates.
Why does 802.11ax use multiple channel widths?
To balance between throughput and coverage, allowing flexible use of spectrum depending on network demands and environment.
Are 802.11ax channels overlapping?
Channels can overlap if using wider bandwidths (e.g., 40, 80, or 160 MHz), but 20 MHz channels are generally non-overlapping.
What determines the number of usable channels?
Country regulations and permitted frequency bands (2.4 GHz, 5 GHz, 6 GHz) define the usable channels for 802.11ax.
What is Dynamic Frequency Selection (DFS)?
DFS allows devices to detect radar signals and automatically switch channels to avoid interference, important in certain 5 GHz and 6 GHz bands.
What is Transmit Power Control (TPC)?
TPC dynamically adjusts transmit power to minimize interference and conserve energy while maintaining performance.
Can 802.11ax use 40 MHz or 80 MHz channels?
Yes, 802.11ax supports 20, 40, 80, and 160 MHz channel widths for increased throughput.
Why is channel planning important in 802.11ax?
Proper channel planning reduces interference, optimizes spectrum use, and improves network efficiency and user experience.
Are all 5 GHz channels available globally?
No, availability varies by country based on local spectrum regulations.
Can devices auto-select 802.11ax channels?
Yes, modern 802.11ax devices often auto-select optimal channels based on interference and congestion.
How do clients know which channel to use?
Clients scan for access points and select channels based on beacon signals and network conditions.
What is the channel center frequency?
The center frequency is the midpoint frequency of the selected channel bandwidth, e.g., channel 36 center is 5.180 GHz.
How are 802.11ax channels numbered?
Channels are numbered similarly to 802.11ac/a: 36, 40, 44, etc., spaced based on 20 MHz increments.
What are the typical channel numbers for 802.11ax?
Channels include those in 2.4 GHz (1–14), 5 GHz (36, 40, 44, 48, 52, 56, 60, 64, etc.), and 6 GHz (varies by region).
How far apart are 802.11ax channels spaced?
20 MHz channels are spaced 20 MHz apart; wider channels combine adjacent 20 MHz channels.
What is co-channel interference?
Interference that occurs when multiple devices use the same frequency channel, causing contention and reduced throughput.
How can co-channel interference be avoided in 802.11ax?
Through careful channel allocation, channel width management, and using features like OFDMA and BSS Coloring to improve efficiency.
Does weather affect 5 GHz channel performance?
Similar to earlier Wi-Fi, weather has minimal impact indoors; rain and obstacles attenuate signals more at higher frequencies.
Why is 5 GHz considered less congested than 2.4 GHz?
It has more available channels and fewer legacy devices, reducing interference.
What is the typical range of 802.11ax channels?
Range depends on frequency band and environment: 2.4 GHz offers longer range (~50-70m indoors), 5 GHz and 6 GHz shorter (~30-50m indoors).
Can 802.11ax channels be used outdoors?
Yes, depending on local regulations and device capabilities, including DFS and TPC compliance.
What happens if two APs use the same channel?
They share the medium, causing contention and potentially lowering throughput.
What tools help with 802.11ax channel planning?
Spectrum analyzers, Wi-Fi 6-compatible scanners, network controllers with AI-driven planning, and site survey tools.
Topics in this section,
Channel Number (MHz) |
Center Frequency (MHz) |
Frequency Range |
DFS Required |
|---|---|---|---|
1 |
2412 |
2401 – 2423 |
No |
2 |
2417 |
2406 – 2428 |
No |
3 |
2422 |
2411 – 2433 |
No |
4 |
2427 |
2416 – 2438 |
No |
5 |
2432 |
2421 – 2443 |
No |
6 |
2437 |
2426 – 2448 |
No |
7 |
2442 |
2431 – 2453 |
No |
8 |
2447 |
2436 – 2458 |
No |
9 |
2452 |
2441 – 2463 |
No |
10 |
2457 |
2446 – 2468 |
No |
11 |
2462 |
2451 – 2473 |
No |
12 |
2467 |
2456 – 2478 |
No (region dependent) |
13 |
2472 |
2461 – 2483 |
No (region dependent) |
14 |
2484 |
2473 – 2495 |
No (Japan only) |
Channel Number (MHz) |
Center Frequency (MHz) |
Frequency Range |
DFS Required |
|---|---|---|---|
36 |
5180 |
5170 – 5190 |
No |
40 |
5200 |
5190 – 5210 |
No |
44 |
5220 |
5210 – 5230 |
No |
48 |
5240 |
5230 – 5250 |
No |
52 |
5260 |
5250 – 5270 |
Yes |
56 |
5280 |
5270 – 5290 |
Yes |
60 |
5300 |
5290 – 5310 |
Yes |
64 |
5320 |
5310 – 5330 |
Yes |
100 |
5500 |
5490 – 5510 |
Yes |
104 |
5520 |
5510 – 5530 |
Yes |
108 |
5540 |
5530 – 5550 |
Yes |
112 |
5560 |
5550 – 5570 |
Yes |
116 |
5580 |
5570 – 5590 |
Yes |
120 |
5600 |
5590 – 5610 |
Yes |
124 |
5620 |
5610 – 5630 |
Yes |
128 |
5640 |
5630 – 5650 |
Yes |
132 |
5660 |
5650 – 5670 |
Yes |
136 |
5680 |
5670 – 5690 |
Yes |
140 |
5700 |
5690 – 5710 |
Yes |
144 |
5720 |
5710 – 5730 |
Yes |
149 |
5745 |
5735 – 5755 |
No |
153 |
5765 |
5755 – 5775 |
No |
157 |
5785 |
5775 – 5795 |
No |
161 |
5805 |
5795 – 5815 |
No |
165 |
5825 |
5815 – 5835 |
No |
channel widths
Band Name |
Frequency Range (GHz) |
Frequency Range (MHz) |
Channels |
|---|---|---|---|
2.4 GHz Band |
2.400 – 2.485 |
2400 – 2485 |
1 – 14 (region dependent) |
UNII-1 |
5.150 – 5.250 |
5150 – 5250 |
36, 40, 44, 48 |
UNII-2 (DFS) |
5.250 – 5.350 |
5250 – 5350 |
52, 56, 60, 64 |
UNII-2 Extended (DFS) |
5.470 – 5.725 |
5470 – 5725 |
100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144 |
UNII-3 |
5.725 – 5.825 |
5725 – 5825 |
149, 153, 157, 161, 165 |
Reference links