Radio link control (RLC) is a layer 2
Radio Link Protocol used in
UMTS
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the In ...
,
LTE and
5G on the
Air interface
The air interface, or access mode, is the communication link between the two stations in mobile or wireless communication. The air interface involves both the physical and data link layers (layer 1 and 2) of the OSI model for a connection.
Physi ...
. This protocol is specified by
3GPP in TS 25.322 for UMTS, TS 36.322 for LTE and TS 38.322
3GPP TS 38.322 NR; Radio Link Control (RLC) protocol specification
/ref> for 5G New Radio (NR).
RLC is located on top of the 3GPP MAC-layer and below the PDCP Packet Data Convergence Protocol (PDCP) is specified by 3GPP in TS 25.323 for UMTS, TS 36.323 for LTE and TS 38.323 for 5G. PDCP is located in the Radio Protocol Stack in the UMTS/LTE/5G air interface on top of the RLC layer.
PDCP provides its ...
-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
{{Reflist
Mobile telecommunications standards
3GPP standards
UMTS
5G (telecommunication)
Logical link control