You might want to try to move the ps3 closer to the wifi router.
Downloading stuff from the living room takes at least 4 times longer then when I move the ps3 downstairs.
(At least it still works. Our WiiU in the living room fails to stay connected 90% of the time, unless I bridge internet connection through my wife's wireless N laptop)
My old laptop (b/g) in the living room gets 4 to 6 mbps down, 2mbps up, 14ms ping according to speedtest.
My wife's wireless N laptop same spot, 22 mbps down, 2mbps up 13ms ping.
My wired desktop gets 40 mbps down, 2mbps up 13ms ping.
The PS4 gets wireless N if I'm not mistaken, should work better.