If you live in a building, there are probably dozens of Wi-Fi networks around you. They all operate in 2.4GHz band, while some others also do it in the 5 GHz, and it may even be that one of your devices is already compatible with the new 6 GHz. However, the 2.4 GHz, being the most used, is the that more tends to saturate and generate interference.
The 2.4 GHz band in Europe operates between the 2401 and 2472MHz. Among those 71 MHz we find a total of 13 channels of 22 MHz each, which overlap each other. Each channel concentrates its maximum frequency in steps of 5 MHz, placing, for example, channel 1 at 2,412 MHz, channel 2 at 2,417 MHz, and so on until reaching 2,472 MHz of channel 13.
Why does interference occur?
As happens to any wireless signal, WiFi is likely to have interference with other WiFi signals nearby overlapping frequencies, or even from other devices that also operate on those frequencies. For example, Bluetooth devices or microwaves in the kitchen emit signals at 2.4 GHz, and a microwave can, while it is turned on, create interference in the signal of our WiFi network.
The WiFi channels overlap each other, but normally wireless networks use, by default, the channels 1, 6 or 11. We see the reason in the previous graph, where we can see that these three channels do not overlap each other. In other words, it is the number maximum channels that may be available without any overlap, since there are only 71MHz to use spectrum, and each channel occupies 22MHz.
So why don’t all routers use just those three channels in the 2.4 GHz band? Well, because there would be even more interference within the channel. There are applications for mobile phones and computers that allow you to know how saturated your environment is. For example, with Wi-Fi Analyzer for Windows 10, you can see which channels are being used by adjacent networks on 2.4 GHz in the graph, as well as which channels are using 5 GHz. Looking at the graph, in my case it would not be a bad idea to use channel 1 , which is also the one that offers the most range (no matter how small the difference).
Other programs like inSSIDer They even have recommendations on which channels to use. In fact, as soon as you open it, it effectively detects that the canal 1 is the least saturated around me, and that the performance could improve if I change it in the router. Some modern routers automatically choose the least crowded WiFi channel, but unfortunately most don’t. In addition, the program also measures WiFi usage on each channel, including nearby networks.
Therefore, it is best to always use the channels 1, 6 or 11, since they are the ones further away from each other and do not overlap. Of them, it is best to choose the one that uses fewer networks around us, and, above all, the networks that are farthest from ours, which we can see in data such as the attenuation. The closer the value is to -90dBm, the less powerful the WiFi signal that reaches our receiver will be.
In the 5 GHz there are hardly any interference problems
How much the higher the frequency than a channel is available, the more speed we can achieve. That is why it was launched 5 GHz band, with a smaller range, and with a greater number of channels, which are also broader. Thus, most people who use WiFi do so near the router, and thus do not have to overload the surroundings.
Thus, as there are more and more routers and devices using 5 GHz thanks to the higher speed they offer, these frequencies can also interfere with each other. with the band of 6GHz will help further reduce the load at the frequencies of 2.4 and 5GHz, in addition to obtaining greater speed. With 6 GHz there will be in Europe up to 3 channels of 160 MHz bandwidth, which do not overlap each other. With the 5 GHz, the channels are up to 80 MHz.