Hi @spaarks11
For most people, the explanation that the 5GHz band handles Wi-Fi interference much better than the 2.4GHz band is all that I would normally say. However, you requested to understand exactly how this is. The only way to do that is via a long and complex post. Therefore, I make no apologies for the length.
Before starting to do this, it might help to understand some of the basics.
The basic 802.11 Wi-Fi specification dictates that 5MHz of the allocated frequency spectrum is used for each Wi-Fi channel. In the 2.4GHz band, channel 1 is 5MHz wide, as are each of the channels 2 to 11 or possibly 13 (depending on router chipset/country regulations allow). However, 5MHz is not practical and with the introduction of 802.11n, the Channel Bandwidth parameter was introduced for both the 2.4 and 5GHz bands. In the 2.4GHz band, four 5MHz channels are typically combined to make a 20MHz channel. This is why there is the recommendation to only use channels 1, 6 or 11 within this band, as they are the only non-overlapping channels. Using a 40MHz wide channel in the 2.4GHz band will typically take up 9 out of the normal 11 channels! To prevent such usage, the 5GHz band only allows the use of groups of four 5MHz channels that do not overlap, typically 36, 40, 44 or 48 within that channel range.
When selecting a channel in the 5GHz band, a single channel has not really been selected at all. This is effectively telling the router/AP/Mesh node to use the least used channel within that range. If a router/AP/Mesh node is configured to use channel 36, for example, it could actually be using any channel from 36 to 48. Using the default of 80MHz as an example, this will use all four channels to achieve this requirement.
However, this is one of several ways that the 5GHz band is much improved over the 2.4Ghz band. It handles Wi-Fi interference much better. When the bandwidth is set to 80MHz, you do not actually use all four channels 36 to 48 until you are transferring enough data to benefit from it. In reality, this means that at any time, you are only using one or possibly two of these channels. Let's say this was channels 36 and 40; it then leaves 44 and 48 for other networks to use. Therefore, the configured channel in the router/AP/Mesh node is in use within this band, a Wi-Fi analyser will display the actual channel currently in use. The high Wi-Fi theoretical data link speeds that are offered via the various specifications of both 802.11ac (Wi-Fi 5) and 802.11ax (Wi-Fi 6), the actual throughput used is drastically cut down by the fibre speed (even with the 900M Full Fibre package).
I have purposely omitted mentioning the channels in the range of 52 to 140 as these are DFS channels, which will complicate matters much further due to the technical operation of this band of the frequency spectrum.
What further complicates this (or possibly simplifies this depending on opinion) is the introduction with Wi-Fi 5 (802.11ac) of a new channel naming convention. However, this is as it sounds: just a new method of naming these channels; it has no impact on Wi-Fi performance at all.
This new channel naming convention makes referencing these extra-wide (up to 160Mz) channels easier. Instead of listing all channel numbers, channels are numbered by their centre channel number of the group of channels.
Take the example of the channel range 36 – 48, the centre channel number is 42, which is not selectable in routers not using this new convention, as the actual channels they allow to be configured are 36, 40, 44 and 48. It was seen earlier that selecting, say, channel 40, simply means using any channel from 36 to 48. Therefore, the new naming convention just allows the selection of channel 42 to represent this group of channels.
With this naming convention, the next term to understand is the Control Channel. This is the actual 20MHz channel that is currently in use for 802.11 control and management frames (e.g. Beacons), along with customer data.
Not all router/AP/Mesh nodes comply with this new naming convention. Certainly, the eero range of products does conform, which is why, in the eero app under WiFi Radio Analytics, this might be seen:-
Channel: 155
Control channel: 149
Channel bandwidth: 80MHz.
