Internet connection for ps3

i am having problems with my connection to my ps3. the problem is that whenever i play my ps3 i am able to sign in to my account and speak 2 my friends but for some reason when i play games such as call of duty 4 i cant seem to play that game. But once i did manage to play cod 4 after i was invited to a game but when i did play it eventually the screen started to go fuzzy and when i walked forward it would put me back to the position i started and the person that i was playing on cod 4 kept shaking. I have been told that the problem is my wireless router is far away form my ps3 and i have been told that the connection is poor possibly because of my internet but I can play other games such as resident evil 5. Can u please help me thanx :)