Wireless

The 802.11a/g wifi router is marked as 54Mbps, divided by 8, at least 6MB/s. Why is the actual speed only over 2M? Most of the explanations on the Internet are vague, so I had to take a stab at it myself, corrections are welcome.

Wifi communication takes place on a given carrier frequency band (channel), just like everyone talking in a hall, everyone’s speech interferes with others.

Why not create more channels? On the one hand, the ISM band that can be used without a license is very limited in the 2.4GHz area suitable for wireless communication; on the other hand, to ensure communication speed, the channel cannot be too narrow. In 802.11a/g (wifi protocol), the channel width is 22MHz, and 14 channels are divided (some of which are not in the ISM band in some countries). Each channel also interferes with the surrounding channels (see the figure below), which is why wireless routers have a dozen channels, but only the distant 1, 6, 11 channels can be used at the same time.