Wi-Fi frequency bands and link conditions
Wi-Fi frequency bands provide different spectrum and propagation contexts, while permitted channels, device capability and actual channel conditions determine the usable link.
“Use 5 GHz” is incomplete as an explanation of a media link. The band changes its spectrum and propagation context, but the devices, chosen channel and surrounding traffic still matter.
Frequency and wavelength are related
For these rounded teaching frequencies, use an approximate wave speed of three hundred million metres per second:
| Frequency | Approximate wavelength |
|---|---|
| 2.4 GHz | 12.5 cm |
| 5 GHz | 6 cm |
| 6 GHz | 5 cm |
These are representative frequency values rather than a list of legal Wi-Fi channels.
For the same distance and stated free-space link assumptions, changing 2.4 to 5 GHz adds approximately 6.375 dB of calculated free-space attenuation. Changing 2.4 to 6 GHz adds approximately 7.959 dB.
The comparison uses twenty times the logarithm of the frequency ratio. It holds the other declared terms constant.
Walls, multipath, antenna gain, permitted power and device behavior can change an indoor result. The free-space comparison should not be promoted into a universal rule about how many rooms a band covers.
Spectrum and permitted operation are separate inputs
Bands can offer different channel arrangements and width choices. Availability and power rules depend on the jurisdiction and operation type.
An app, access point and client also need compatible capability. A “Wi-Fi” label alone does not establish that a particular device can use 6 GHz.
Channel width and modulation/spatial-stream choices affect the PHY rate. The band name is not itself the throughput value.
Band and Wi-Fi generation are different dimensions
A generation/specification family can support operation in more than one band, with specific amendments and certified capability defining the actual options.
The IEEE 802.11 references identify the standards family and current base publication context. They do not supply a capability declaration for an unspecified TV.
Likewise, a newer access point cannot give an older client radio capabilities it does not have.
Compare the actual link at the viewing location
A less congested channel, different width or another propagation path can produce a useful change. That result needs to be evaluated through the actual client’s route and delivered rate.
See Also
- Wi-Fi signal quality, noise and useful airtime
- Wireless backhaul and repeated airtime
- Network throughput and useful delivery rate