5.7a Discontinuous Reception (DRX) for MBS Broadcast

38.3213GPPMedium Access Control (MAC) protocol specificationNRRelease 17TS

For MBS broadcast, the MAC entity may be configured by RRC with a DRX functionality per G-RNTI that controls the UE’s PDCCH monitoring activity for the MAC entity’s G-RNTI(s) as specified in TS 38.331 [5]. When in RRC_IDLE or RRC_INACTIVE or RRC_CONNECTED, if broadcast DRX is configured for a G-RNTI, the MAC entity is allowed to monitor the PDCCH for this G-RNTI discontinuously using the broadcast DRX operation specified in this clause; otherwise the MAC entity monitors each PDCCH for this G-RNTI as specified in TS 38.213 [6]. The broadcast DRX operation specified in this clause is performed independently for each G-RNTI and independently from the DRX operation specified in clauses 5.7 and 5.7b.

RRC controls broadcast DRX operation by configuring the following parameters:

– drx-onDurationTimerPTM: the duration at the beginning of a DRX cycle;

– drx-SlotOffsetPTM: the delay before starting the drx-onDurationTimerPTM;

– drx-InactivityTimerPTM: the duration after the PDCCH occasion in which a PDCCH indicates a new DL broadcast transmission for the MAC entity;

– drx-LongCycleStartOffsetPTM: the long DRX cycle drx-LongCycle-PTM and drx-StartOffset-PTM which defines the subframe where the DRX cycle starts.

When broadcast DRX is configured for a G-RNTI, the Active Time includes the time while:

– drx-onDurationTimerPTM or drx-InactivityTimerPTM for this G-RNTI is running.

When broadcast DRX is configured for a G-RNTI, the MAC entity shall for this G-RNTI:

1> if [(SFN × 10) + subframe number] modulo (drx-LongCycle-PTM) = drx-StartOffset-PTM:

2> start drx-onDurationTimerPTM after drx-SlotOffsetPTM from the beginning of the subframe.

1> if the MAC entity is in Active Time for this G-RNTI:

2> monitor the PDCCH for this G-RNTI as specified in TS 38.213 [6];

2> if the PDCCH indicates a DL transmission for MBS broadcast:

3> start or restart drx-InactivityTimerPTM in the first symbol after the end of the PDCCH reception.

NOTE: If a cell is configured for MBS broadcast reception, the SFN of this cell is used to calculate the DRX duration of MBS broadcast on this cell.