What are WiFi Channels

In Networking by Danny SmithLeave a Comment

A few years ago there were hardly any wireless access points and almost everyone used twisted pair cable to go online. Nowadays that does not happen anymore. The operators themselves offer Wi-Fi solutions to their customers without much difficulty. The problem is that the more networks of this type exist, the greater the chances of interference.

One of the most common solutions you will hear out there is to resort to the channel change. For the most expert in the field, this can be done in just two minutes, but there are many people who do not know what are WiFi channels and how this influences our wireless networks. Precisely this is what we are going to explain today.

What are WiFi channels?

When the IEEE 802.11 standard (the one that regulates local wireless networks) was defined, it also specified the three frequency ranges available for the devices that wish to emit in this way: 2.4 GHz, 3.6 GHz, and 5 GHz. Most current devices they operate, by default, in the frequency band near 2.4 GHz, which is why we are going to focus today. Each frequency range was subdivided, in turn, into a multitude of channels.

For 2.4 GHz, we are talking about 14 channels, separated by 5 MHz. However, each country and geographical area applies its own restrictions to the number of available channels. For example, in North America, only the first 11 are used, while in Europe we have 13. The problem with this distribution is that each channel needs 22MHz of bandwidth to operate, and as you can see in the figure this produces an Overlapping of several contiguous channels.

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Here is an important concept to keep in mind: the overlap. As can be seen in the graphic that heads this post, channel 1 overlaps with channels 2, 3, 4 and 5, and therefore the devices that emit in that frequency range can generate interferences. The same happens with channel 6 and channels 7, 8, 9 and 10. It seems logical to think then that, if our Wi-Fi connection is not going as well as it should, we could try to improve the network by changing the channel to another less used between nearby access points and that does not overlap with them.

How do we do this?

Locating access points and their channel

When from a computer we want to access a Wi-Fi network, the operating system itself offers information about that network: normally the name (also known as SSID ), the level of signal that reaches us and security, but what does not appear at a glance is the channel they are using.

To know the channels of the nearby networks, and if we are using Windows Vista or Windows 7, it is as simple as opening the command console (clicking on Start and typing cmd in “Search programs and files”). Once inside, we write the command netsh WLAN show all and press enter. If everything went well, in the window with a black background we will see all the networks we saw before, but with more data.

What you will surely see then are many networks that use channel 6, since it is one that companies use by default. Then, the ideal would be to change our channel to 1 or 11, since they do not overlap. If, on the other hand, you see that a very powerful signal arrives on another channel and you think that it may be the cause of the interference, you can change to a different channel that, looking at the graph we were talking about earlier, do not overlap with the interfering channel.

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Another interesting alternative to the command console, for those who prefer something with more graphic content, could be using any of the multitudes of tools that exist on the Internet to do this. insider is perhaps one of the most famous and also one of the most complete. In addition to listing all the wireless networks within the scope of our computer, it also shows its power, its channel and the channels with which each one overlaps. It is free and you can download the application from here.

Once we have chosen the channel we want to use, we must access our router and specify which one we want to use. On this point, I am not going to stop too much, since it depends on the model and we have also dedicated a lot of time and space here in Engadget ON to the configuration of routers.

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