My wifi is ridiculously annoying - I live in an apartment block where there are literally 30 other wifi routers interfering with my own router. I pay through the nose for superfast broadband but it's completely redundant!
I've had this problem before. Try changing the "channel" for your wifi signal. You can do this via the admin interface for your router. If that doesn't help, the cause might be EM interference from other electronic devices physically near the router. Try moving other electronics (power supplies, cable modem, etc.) away from the router (at least 1 or 2 feet distance should do it).
I had this exact problem so I empathize with you. It was really painful, because my internet would go out sporadically for at least a minute every once in a while. My problem was also too much noise coming from a crowded apartment complex.
The solution I found was to upgrade to a 5 GHz router. The one I bought can transmit on both 2.4 GHz and 5 GHz, but I configured it to only transmit on 5 GHz. This forces my computer to always use the 5 GHz connection, which has less noise. The 5 GHz signal decays faster when it goes through walls, so the signal will not be as strong as a 2.4 GHz would, but the signal-to-noise ratio will be much better because 5 GHz is significantly less crowded.
