Instructions
Ensure that all computers on the network are not in use, and are switched off, so that they are not accessing the network you will be using when you play "Call of Duty." By removing users from your network, you reduce strain on your network and increase the available bandwidth in your network. The additional bandwidth will allow you to transfer more data more quickly, allowing game performance to improve.
Connect your PS3 directly to your router using an ethernet cable. By connecting directly to your router instead of over a wireless connection, your connection will be rock-solid, eliminating data packet drops on your end. Overall, a direct wired connection will reduce latency and eliminate wireless related connection loss, helping reduce lag.
Observe the number of wireless networks available in your area by configuring your wireless network at the "System" column in the PlayStation 3's main menu or the XrossMediaBar (cross-media bar, or XMB). If there are many wireless networks in your area, ask your network administrator to change the channel on the router. There is a high possibility that all your local networks are operating on the same channel, slowing data transmission.