It's a fallacy that routers using the same channel can interfere to the extent to cause total malfunction - wi-fi is a time-shared service, so several routers can share the same wireless channel. You will only see problems if a router is maxing out the channel with traffic, and that is rare. Also, there are only 3 channels that are exclusive on the channel plan (Channels 1, 5 and 11) - all the other channels overlap the adjacent one.
The majority of problems with drop-outs and disconnections are due to other factors. The main factor is that most USB devices attached to PC's and laptops still have the power-saving switched on - Go to Start >> Settings >> Control Panel >> Administrative Tools >> Computer Management >> Device Manager and find the Universal Bus Controllers and select the device(s) used for wi-fi. Right click on the device, and select Properties, and find the Power Management tab. Make sure that the box saying Allow The Computer To Switch Off This Device To Save Power is not ticked.
Other reasons for wi-fi problems are reflections of the signal caused by wall materials (lots of modern houses have foil-backed plasterboard which kills wi-fi), or attenuation of signals passing through dividing walls. Careful placement (with some trial and error) of the receiving and transmitting aerials can help with this.
Mobile and DECT phones do not interfere with wi-fi, but video senders can, although wi-fi affects video senders much more than video senders affect wi-fi.