5.2a Maintenance of UL Synchronization

38.3213GPPMedium Access Control (MAC) protocol specificationNRRelease 17TS

The MAC entity shall for each Serving Cell:

1> if an indication of uplink synchronization has been received from upper layers (see clause 5.2.2.6 of TS 38.331 [5]):

2> allow uplink transmission on the Serving Cell.

1> if an indication of uplink synchronization loss is received from upper layers:

2> flush all HARQ buffers;

2> not perform any uplink transmission on the Serving Cell.