6.1 Protocol data units

36.3223GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Radio Link Control (RLC) protocol specificationRelease 17TS

RLC PDUs can be categorized into RLC data PDUs and RLC control PDUs. RLC data PDUs in sub clause 6.1.1 are used by TM, UM and AM RLC entities to transfer upper layer PDUs (i.e. RLC SDUs). RLC control PDUs in sub clause 6.1.2 are used by AM RLC entity to perform ARQ procedures.

6.1.1 RLC data PDU

a) TMD PDU

TMD PDU is used to transfer upper layer PDUs by a TM RLC entity.

b) UMD PDU

UMD PDU is used to transfer upper layer PDUs by an UM RLC entity.

c) AMD PDU

AMD PDU is used to transfer upper layer PDUs by an AM RLC entity. It is used when the AM RLC entity transmits (part of) the RLC SDU for the first time, or when the AM RLC entity retransmits an AMD PDU without having to perform re-segmentation.

d) AMD PDU segment

AMD PDU segment is used to transfer upper layer PDUs by an AM RLC entity. It is used when the AM RLC entity needs to retransmit a portion of an AMD PDU.

6.1.2 RLC control PDU

a) STATUS PDU

STATUS PDU is used by the receiving side of an AM RLC entity to inform the peer AM RLC entity about RLC data PDUs that are received successfully, and RLC data PDUs that are detected to be lost by the receiving side of an AM RLC entity.