Radio Link Control
From HandWiki
Radio Link Control (RLC) is a layer 2 Radio Link Protocol used in UMTS, LTE and 5G on the Air interface. This protocol is specified by 3GPP in TS 25.322[1] for UMTS, TS 36.322[2] for LTE and TS 38.322[3] 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.
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