Many people believe its possible to overcome interference from other wifi networks and sources of interference, such as microwaves and remote controls, by having a high density of access points.
The inexpensive nature of 802.11 access points and routers makes it extremely tempting to set up many in a small area. For example, some networks set them up in every room of an office to combat wifi interference.
This type of deployment means you greatly increase the capacity of the network, allowing ‘spatial reuse’ of the spectrum. It seems obvious that by having more access points spread about, it’s more likely that clients will be able to operate successfully even when interference is present.
But, when you deploy a dense network of access points, it’s necessary to reduce the transmit signal power of each access point. If you don’t reduce the power, the access points generate wifi interference to each other, which is known as co-channel interference. Most cheap wireless routers don’t allow you to alter the transmit signal power though!
The reduction in the transmit power of the access point exactly offsets the potential benefit of interference immunity. This means the interference immunity of a network with dense deployment of access points is not significantly better than that of a less dense deployment.
Many people over-design their networks for capacity, but a high density of access points is not a simple solution for interference.