Communications deck

Communications Deck is a generic United Nations Space Command term for the part of an Orbital Defense Platform that presumably handles the station's communication systems.

Cairo Station Communications Deck
During the Battle of Earth, Covenant boarders invaded Cairo Station's Communications Deck. In response, several quick-response teams of Marines were sent to repel them. The actual Communications Deck is never visited during the course of the level, and is only mentioned over the loudspeaker.