iPhone 4 keeps dropping WIFI connection

I'm having this problem with my iPhone 4, it keeps dropping its WIFI connection. It doesn't matter what app its in or anything it'll just randomly lose connection and it'll automatically reconnect a few seconds later.

Its really frustrating because when I'm trying to play games I keep dropping connection and getting kicked out. And my two friends' connections on the same WIFI network are still perfectly fine and we're all sitting in the same room. My friends have an iPhone 4 and an iPhone 3GS. Everyone is on the latest software and etc.

Also when I was downloading an app over 20 MB it kept dropping connection and regaining.

I have tried resetting network settings, that didn't work.

I have tried resetting my iPhone 4, that didn't work.

I have tried switching my DNS # to one that I found on a google search, something like 204.68.222.222 or whatever, that didn't work.

Anyone have any ideas how I can fix this? I'm trying to avoid having to reformat the device.