If your WiFi signal is not smooth or if you playing online game and its lagging then it might be due to the channel that your WiFi router using. The best channel for WiFi depends on your location, means the best channel would be the channel doesn’t used by any WiFi router around you.
To find the best WiFi channel, easiest way is to find the app that scan WiFi channel around you and will give recommended channel to use for your WiFi. Here are some WiFi channel for different OS below.
vistumbler is the open source app for windows that is free and have some other functions that might help you more to modify your WiFi strength and speed. It work for windows 7, Vista and 8. You could use your Laptop to setup it. If you want it with smartphone then check the app that I suggested below.
This app could help you to find best channel plus will analyze different WiFi around you. You could use to setup your router or could choose best router around you.