3. MAC layer

The MAC layer defines how a user obtains a transmission channel when it is needed. The MAC layer uses primitives provided by the PHY layer. It also provides a standard interface for the LLC (Logical Link Control) layer, which can use all data transmission functions without having to know the specifics.

The processes performed by the MAC layer depend in part on the underlying network architecture. Some functionalities supported by APs in architected networks are supported by the stations themselves in ad hoc configurations. Others are simply not supported in this type of architecture.