Radio Link Control (RLC)
Radio Link Control is the radio protocol layer that splits data into segments and, in some modes, resends lost packets so that delivery is reliable.
What is Radio Link Control (RLC)?
RLC sits between PDCP and MAC and works in different modes. Acknowledged mode (RLC-AM) resends missing data for reliability. Unacknowledged mode (RLC-UM) skips retransmission to keep delay down. Transparent mode is used for some control channels.
How it works
In acknowledged mode, the receiver reports which segments arrived and the sender resends any that are missing. Unacknowledged mode is used for delay-sensitive traffic, such as voice or broadcast, where late data is useless.