16.15.4.2.4 RLC Retransmissions

For operation of RLC AM, the following improvements are introduced:

• To avoid unnecessary RLC retransmissions:
• On the transmitter side, when the RLC entity receives a discard indication for an SDU from PDCP, it stops any further transmission or retransmission of that SDU and its corresponding segment(s) if any;
• On the receiver side, a complete PDU detected as missing can be discarded after a configured duration, and positively acknowledged through a status report.
• To ensure timely RLC retransmissions, on the transmitter side, when the remaining time before discard of an RLC SDU:
• Falls below a configured retransmission threshold, a retransmission of this RLC SDU may be triggered; and/or
• Falls below a configured polling threshold, polling is triggered.