Overlapping in our WIFI

What are the best practices in order to avoid overlapping in our WIFI

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Overlapping basic service sets (the area of coverage from a single AP) isn't always a problem and in fact the CWNP recommends a overlap of 20-25% for VoIP networks.

The problem arises when overlapping basic service sets are using the same channel (or an overlapping channel) and this causes unwanted interference.

In my opinion you need to careful planning your WLAN from the beginning. Plan where your APs are going to be placed and make sure they are not unnecessary close to each other (but do ensure they are providing sufficient coverage and capacity). It's also important to survey the site so that existing interference can be located and accounted for in your design. Once you have this information you can begin the design your network and select channels accordingly.

It is also important to note that channel width should be taken into consideration. On the 2.4GHz band we're always going to use 20MHz wide channels as there are only 3 non-overlapping channels (channels 1, 6 & 11 are most often used). On 5GHz we can go up to 160MHz wide channels but this is not a good practice as it uses up so much of the available frequency space. In reality 20MHz and 40MHz channels are more commonly used in the 5GHz band, the number of channels varies per region but as an example on a 40MHz channel it common to have 9 or more non-overlapping channels.

Avoiding interference on the 2.4GHz band is much harder, other non-Wi-Fi devices use this space, there are less channels to use and signals travel further. You can turn down the power on the 2.4GHz radios to help manage this (and you can also do this on the 5GHz raidos as well). In some high density deployments you may with to turn some 2.4GHz radios off completely.

Lastly I wanted to mention a few tools Cambium have that make our life easier, Auto RF is a feature that will automatically choose an channel and power output (NOTE: it does not choose the channel width). One good thing about this feature is that if you environment changes (someone next door installs a new access point) your network will react accordingly. Another useful tool is Wi-Fi Analyzer (under APs > Tools in cnMaestro) this allows you to see what interference the AP can see. This is a great way of confirming that you are on the best channel.

Once everything is setup to verify your results, tools like Wi-Fi Analyzer are a great way of confirming if your design is meeting your requirements.