Channels 1, 6 and 11

One of the best things you can do to improve your 2.4 GHz Wi-Fi network coverage is choosing the proper channel for your wireless router to operate on. But how do you know which channel to choose?

Before we get to the selection process, let’s do a little bit of math (don’t worry- it’s easy!). 802.11g/n channels are 20 MHz-wide. When multiplying 20 times 11 (for the total number of channels), the total comes to 220 MHz. The problem, though, is that the the total space available is only 100 MHz.

Wi-Fi Channels as they appear in the 2.4 GHz

Representation of Wi-Fi’s overlapping channels

What this means is that the channels have to overlap in order to squeeze into this space. As the diagram above shows, only channels 1, 6, and 11 don’t overlap. Overlap is bad because Wi-Fi works like a conversation– if your device hears others talking on the same channel, it’s going to wait for its turn to talk. If there are a lot of devices talking, there’s going to be a lot of waiting time. There are two main types of Wi-Fi congestion: Adjacent and Co-Channel. We’ll talk about them both in-depth in our next Wi-Fi Tips and Tricks email.

Armed with the above information, you’ve narrowed your selection down to three channel choices ( 1, 6 and 11) without using any software! Using inSSIDer will help you to finalize your decision.

A screenshot from inSSIDer showing channel overlap and congestion in the channels graph

Launch inSSIDer and then count how many networks are active on each channel. This will probably be easier to do if you click the “Channel” header to sort the channels in order. What you are looking for is the channel (out of 1, 6, and 11) that has the least amount of networks present. If there are several networks on each of these channels, you will want to choose the network whose average RSSI (signal strength) is -75dBm or lower. An RSSI at this level or below indicates that the conversations being held by the access point(s) aren’t very loud. A good rule of thumb to remember is that the closer to -20dBm a signal is, the stronger it is.

Notice in the above screenshot that the network called “dmg” is running on channel 3, which is overlapping channels 1 and 6. Meanwhile, on channel 11, there are only three active networks, and the only non-MetaGeekGN network has an RSSI of around -80dBm. Since channel 11 has the fewest amount of networks and there aren’t any networks overlapping with it, this makes it the best channel to choose.

Using inSSIDer to help you choose which channel to run your wireless network on is one of the best things you can do to improve Wi-Fi performance, and there are also more advanced techniques for combating wireless issues. Stay tuned to our Tips & Tricks series to learn more about spectrum analysis with Wi-Spy, packet analysis with Eye P.A., and other topics that will help you get the most out of your Wi-Fi.

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