Wireless Communications Basics --- Types of wireless interferences

1) Co-channel interference
Co-channel interference exists when two WLAN devices use the same frequency (2.4/5 GHz). As shown in the figure below, the reare three non-overlapping channels 1, 6, and 11 in the 2.4 GHz band. In places with many routers deployed, a channel may be used by multiple routers. Co-channel interference exists in the areas where the signals of these routers overlap.

2) Adjacent-channel interference
As shown in the figure below, channels 1–5 overlap each other. Therefore, interference may exist in the areas where the signals of two routers overlap even if the routers do not use the same channel.

3) External interference
Some non-WLAN devices use the 2.4 GHz band as well, including microwave ovens, Bluetooth devices, wireless cameras, and wireless mouses, which also have interference in WLAN signals.
(2) Interference mitigation methods
1) Plan router locations appropriately
Do not deploy two routers near each other even if they use non-overlapping channels because the transmitting powers have interference as well. When setting channels, download the Wi-Fi Moho app to test the signals around and check the channel usage. Choose a less used channel if possible.
2) Use the 5 GHz band
Compared with the 2.4 GHz band, the 5 GHz band has a cleaner wireless environment. Therefore, use the 5 GHz band if possible.
3) Keep distance with or eliminate the interference sources
Do not place the router near microwave ovens, mobile phones, and hot spot devices to avoid strong interference.