Most A/V receivers use IR systems for their remote controls. Because IR can't penetrate walls, you need a wired system that can carry IR signals from remote locations in a whole-home entertainment network back to your home theater.
You need this wired system as a way to control remote devices when you're watching (or listening to) them in a different part of the house. If the phone rings, for example, you want to be able to turn down the music or pause the movie.
You can set up an infrared system in your home theater in four ways:
IR cabling: Many home networking vendors sell cables designed for carrying IR signals from remote locations back to the home theater.
CAT-5e cabling: If you’re using CAT-5e cabling for audio and video distribution, you’ll find that these systems have a built-in capability to carry IR signals for remote controls. If you’re not using one of these systems, but have put CAT-5e cabling in your walls when building your home, you can use extra (unused) CAT-5e cables in place of the IR cabling.
RG6 coaxial cabling: Using special devices called IR injectors, you can carry IR signals over the RG6 coax that you use for distributing cable or broadcast antenna TV signals.
You can’t use an IR injector on the RG6 cables used to connect a DSS dish to DSS receivers.
Proprietary systems: If you opt to install a high-end automation system, such as those from Crestron Electronics, you need to use special proprietary cables from the manufacturer. For example, Crestron uses its own special cable called CrestNet.