Radio Link Control
Radio Link Control (RLC) is a layer 2 Radio Link Protocol used in GSM (GPRS), UMTS, LTE and 5G on the Air interface. This protocol is specified by 3GPP in TS 44.060[1] for GPRS, TS 25.322[2] for UMTS, TS 36.322[3] for LTE and TS 38.322[4] for 5G New Radio (NR). RLC is located on top of the 3GPP MAC-layer and below the PDCP-layer. The main tasks of the RLC protocol are:
- Transfer of upper layer Protocol Data Units (PDUs) in one of three modes: Acknowledged Mode (AM), Unacknowledged Mode (UM) and Transparent Mode (TM)
- Error correction through ARQ (only for AM data transfer)
- Concatenation, segmentation and reassembly of RLC SDUs (UM and AM)
- Re-segmentation of RLC data PDUs (AM)
- Reordering of RLC data PDUs (UM and AM);
- Duplicate detection (UM and AM);
- RLC SDU discard (UM and AM)
- RLC re-establishment
- Protocol error detection and recovery
RLC features specific to LTE only - 1) Re-segmentation. 2) RLC SDU discard is notified by upper layer.
References
[edit]- ^ "General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Medium Access Control (RLC/MAC) protocol".
- ^ 3GPP TS 25.322 Radio Link Control (RLC) protocol specification
- ^ 3GPP TS 36.322 Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control (RLC) protocol specification
- ^ 3GPP TS 38.322 NR; Radio Link Control (RLC) protocol specification