Medium Access Control (MAC)
Medium Access Control is the protocol layer that controls how devices share the radio channel, including scheduling and fast error recovery.
What is Medium Access Control (MAC)?
In LTE and 5G, the MAC layer sits just above the physical layer. It combines data from different logical channels, schedules who transmits when, and runs HARQ, a fast retransmission process. Elsewhere the same layer is often called Media Access Control, which is where the term "MAC address" comes from.