The Radio Link Control (RLC) protocol provides the following services:
- Segmentation of SDU according to the size
- Re-Segmentation of PDU
- Radio Bearer to logical channel mapping
Transfer of data in 3 modes:
- TM Transparent Mode
Without retransmission. For real-time service.
- UM Unacknowledged Mode
Without retransmission, but error statistics (BLER)
It can be used for the signaling.
- AM Acknowledged Mode
With retransmission. For non real-time services, like internet.
The main services and functions of the RLC sublayer include:
- Transfer of upper layer PDUs;
- Error Correction through ARQ (only for AM data transfer);
- Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer);
- Re-segmentation of RLC data PDUs (only for AM data transfer);
- In sequence delivery of upper layer PDUs (only for UM and AM data transfer);
- Protocol error detection and recovery;
- RLC SDU discard (only for UM and AM data transfer);