Networking · Topic 3 of 10
Wi-Fi Standards and Frequencies
Compare 802.11 Wi-Fi standards, the 2.4 GHz, 5 GHz and 6 GHz bands, channels, range and interference so you can choose the right wireless setup.
- 4 min
- 802.11n is Wi-Fi 4, 802.11ac is Wi-Fi 5 and 802.11ax is Wi-Fi 6; 802.11be is Wi-Fi 7.
- 802.11a and 802.11ac use only 5 GHz; 802.11b and g use only 2.4 GHz; n and ax can use both (be adds 6 GHz).
- 2.4 GHz has better range and wall penetration but more interference and lower speed.
What it is
Wi-Fi is the common name for wireless local area networks built on the 802.11 family of standards from the Institute of Electrical and Electronics Engineers (IEEE). Each new standard letter brought more speed, more efficient use of the air or a new frequency band.
A technician needs to know which standard works on which band, how band choice affects range and speed, and what causes interference.
How it works
Wi-Fi sends data over radio frequencies. Higher frequencies carry more data but travel less far and pass through walls less well.
The 802.11 standards
| Standard | Marketing name | Band | Notes |
|---|---|---|---|
| 802.11a | none | 5 GHz | Early standard, up to 54 Mbps |
| 802.11b | none | 2.4 GHz | Early standard, up to 11 Mbps |
| 802.11g | none | 2.4 GHz | Up to 54 Mbps, works with b |
| 802.11n | Wi-Fi 4 | 2.4 and 5 GHz | Added multiple antennas, up to about 600 Mbps |
| 802.11ac | Wi-Fi 5 | 5 GHz | Much higher speed, works only on 5 GHz |
| 802.11ax | Wi-Fi 6 | 2.4 and 5 GHz | Better efficiency with many devices; Wi-Fi 6E adds 6 GHz |
| 802.11be | Wi-Fi 7 | 2.4, 5 and 6 GHz | Newer generation, higher speed again |
Speeds are theoretical maximums. Real speeds are lower and shared among all devices on the access point.
Newer standards work with older devices on the same band, but a slow old device can cost the whole network some capacity.
The three bands
| Band | Range and walls | Speed | Interference |
|---|---|---|---|
| 2.4 GHz | Longest range, passes through walls better | Lower | Crowded: many devices and neighbours use it |
| 5 GHz | Shorter range | Higher | Less crowded, more channels |
| 6 GHz | Shortest range | Highest | Very clean, only for newer devices (Wi-Fi 6E and 7) |
A dual band router offers 2.4 and 5 GHz at once, and a tri band router adds a third radio. Devices pick a band, or the router steers them.
Channels
Each band is split into channels, which are narrow slices of frequency. Two access points close to each other should use different channels to avoid interfering.
On 2.4 GHz the channels overlap, so channels 1, 6 and 11 are the three that do not overlap in the United States. 5 GHz has many more channels that do not overlap. Wider channels give more speed but use more space and are more easily disturbed.
A Wi-Fi analyzer, a tool covered in the tools page, shows which channels are busy, so you can pick a quiet one.
Sources of interference
- Other Wi-Fi networks on the same or nearby channels
- Microwave ovens and cordless phones, mostly on 2.4 GHz
- Bluetooth devices, also on 2.4 GHz
- Thick walls, metal, mirrors and water, which weaken the signal
- Distance from the access point
If a user far from the router needs better reach, choose 2.4 GHz. If the user is close and needs speed, choose 5 GHz or 6 GHz.
Rules and regions
Radio use is regulated, and each country sets which channels and power levels are allowed. A device set to the wrong region may not see some networks. The standard setting for the country is normally used.
What to remember for the exam
- 802.11n is Wi-Fi 4, 802.11ac is Wi-Fi 5 and 802.11ax is Wi-Fi 6; 802.11be is Wi-Fi 7.
- 802.11a and 802.11ac use only 5 GHz; 802.11b and g use only 2.4 GHz; n and ax can use both (be adds 6 GHz).
- 2.4 GHz has better range and wall penetration but more interference and lower speed.
- 5 GHz and 6 GHz give higher speed over shorter range.
- Channels 1, 6 and 11 are the non overlapping 2.4 GHz channels in the United States.
- Wi-Fi 6E extends Wi-Fi 6 into the 6 GHz band.
- Microwave ovens, cordless phones and Bluetooth can disturb 2.4 GHz.
- A Wi-Fi analyzer helps pick the least crowded channel.
Common mistakes
Thinking a higher band always works best. 5 GHz and 6 GHz are faster, but at a distance or behind walls a 2.4 GHz signal can be the stronger one.
Assuming theoretical speed is real speed. Speeds are shared among devices and drop with distance and interference.
Placing access points on the same channel. Two close access points on one channel share the airtime and slow each other.
Mixing up the standard letters and band. 802.11ac is a 5 GHz only standard, so a 2.4 GHz only device cannot use it.
Forgetting older devices. One slow legacy device on a network can reduce the overall performance.
Check yourself
Which common Wi-Fi standards can use both 2.4 GHz and 5 GHz?
802.11n (Wi-Fi 4) and 802.11ax (Wi-Fi 6). The newer 802.11be adds 6 GHz as well.
Which band gives the best range through walls?
The 2.4 GHz band, at the cost of speed and more interference.
Which three 2.4 GHz channels do not overlap in the United States?
Channels 1, 6 and 11.
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