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);