Section: 5.7 Discontinuous Reception (DRX)
Content: The MAC entity may be configured by RRC with a DRX functionality that controls the UE's PDCCH monitoring activity for the MAC entity's C-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, Semi-Persistent Scheduling C-RNTI (if configured), UL Semi-Persistent Scheduling V-RNTI (if configured), eIMTA-RNTI (if configured), SL-RNTI (if configured), SL-V-RNTI (if configured), CC-RNTI (if configured), SRS-TPC-RNTI (if configured), and AUL C-RNTI (if configured). When in RRC_CONNECTED, if DRX is configured, the MAC entity is allowed to monitor the PDCCH discontinuously using the DRX operation specified in this clause; otherwise the MAC entity monitors the PDCCH continuously. When using DRX operation, the MAC entity shall also monitor PDCCH according to requirements found in other clauses of this specification. RRC controls DRX operation by configuring the timers onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer (for HARQ processes scheduled using 1ms TTI, one per DL HARQ process except for the broadcast process), drx-RetransmissionTimerShortTTI (for HARQ processes scheduled using short TTI, one per DL HARQ process), drx-ULRetransmissionTimer (for HARQ processes scheduled using 1ms TTI, one per asynchronous UL HARQ process), drx-ULRetransmissionTimerShortTTI (for HARQ processes scheduled using short TTI, one per asynchronous UL HARQ process), the longDRX-Cycle, the value of the drxStartOffset and optionally the drxShortCycleTimer and shortDRX-Cycle. A HARQ RTT timer per DL HARQ process (except for the broadcast process) and UL HARQ RTT Timer per asynchronous UL HARQ process is also defined (see clause 7.7). The HARQ mode per HARQ process can be configured in uplinkHARQ-Mode. When a DRX cycle is configured, the Active Time includes the time while: - onDurationTimer or drx-InactivityTimer or drx-RetransmissionTimer or drx-RetransmissionTimerShortTTI or drx-ULRetransmissionTimer or drx-ULRetransmissionTimerShortTTI or mac-ContentionResolutionTimer (as described in clause 5.1.5) is running; or - a Scheduling Request is sent on PUCCH/SPUCCH and is pending (as described in clause 5.4.4). If this Serving Cell is part of a non-terrestrial network, the Active Time is started after the Scheduling Request transmission that is performed when the SR_COUNTER is 0 for all the SR configurations with pending SR(s) plus the UE-eNB RTT; or - an uplink grant for a pending HARQ retransmission can occur and there is data in the corresponding HARQ buffer for synchronous HARQ process; or - a PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has not been received after successful reception of a Random Access Response for the preamble not selected by the MAC entity (as described in clause 5.1.4) ; or - mpdcch-UL-HARQ-ACK-FeedbackConfig is configured and repetitions within a bundle are being transmitted according to UL_REPETITION_NUMBER. If this Serving Cell is part of a non-terrestrial network, the Active Time starts after the first repetition within the bundle plus the UE-eNB RTT when repetitions within the bundle are being transmitted. When DRX is configured, the MAC entity shall for each subframe: - if a HARQ RTT Timer expires in this subframe: - if the data of the corresponding HARQ process was not successfully decoded: - start the drx-RetransmissionTimer or drx-RetransmissionTimerShortTTI for the corresponding HARQ process; - if NB-IoT: - if lower layers had indicated multiple TBs were scheduled for the associated expired HARQ RTT Timer: - start or restart drx-InactivityTimer when all HARQ RTT Timers have expired; - else: - start or restart the drx-InactivityTimer. - if an UL HARQ RTT Timer expires in this subframe: - start the drx-ULRetransmissionTimer or drx-ULRetransmissionTimerShortTTI for the corresponding HARQ process. - if NB-IoT: - if lower layers had indicated multiple TBs were scheduled for the associated expired HARQ RTT Timer: - start or restart drx-InactivityTimer when all HARQ RTT Timers have expired; - else: - start or restart the drx-InactivityTimer. - if a DRX Command MAC control element or a Long DRX Command MAC control element is received: - stop onDurationTimer; - stop drx-InactivityTimer. - if drx-InactivityTimer expires or a DRX Command MAC control element is received in this subframe: - if the Short DRX cycle is configured: - start or restart drxShortCycleTimer; - use the Short DRX Cycle. - else: - use the Long DRX cycle. - if drxShortCycleTimer expires in this subframe: - use the Long DRX cycle. - if a Long DRX Command MAC control element is received: - stop drxShortCycleTimer; - use the Long DRX cycle. - If the Short DRX Cycle is used and [(SFN * 10) + subframe number] modulo (shortDRX-Cycle) = (drxStartOffset) modulo (shortDRX-Cycle); or - if the Long DRX Cycle is used and [(SFN * 10) + subframe number] modulo (longDRX-Cycle) = drxStartOffset: - if NB-IoT: - if there is at least one HARQ process for which neither HARQ RTT Timer nor UL HARQ RTT Timer is running, start onDurationTimer. - else: - start onDurationTimer. - during the Active Time, for a PDCCH-subframe, if the subframe is not required for uplink transmission for half-duplex FDD UE operation, and if the subframe is not a half-duplex guard subframe, as specified in TS 36.211[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation ]  [7], and if the subframe is not part of a configured measurement gap and if the subframe is not part of a configured Sidelink Discovery Gap for Reception, and for NB-IoT if the subframe is not required for uplink transmission or downlink reception other than on PDCCH; or - during the Active Time, for a subframe other than a PDCCH-subframe and for a UE capable of simultaneous reception and transmission in the aggregated cells, if the subframe is a downlink subframe indicated by a valid eIMTA L1 signalling for at least one serving cell not configured with schedulingCellId, as specified in TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [8] and if the subframe is not part of a configured measurement gap and if the subframe is not part of a configured Sidelink Discovery Gap for Reception; or - during the Active Time, for a subframe other than a PDCCH-subframe and for a UE not capable of simultaneous reception and transmission in the aggregated cells, if the subframe is a downlink subframe indicated by a valid eIMTA L1 signalling for the SpCell and if the subframe is not part of a configured measurement gap and if the subframe is not part of a configured Sidelink Discovery Gap for Reception: - monitor the PDCCH; - if the PDCCH indicates a DL transmission or if a DL assignment has been configured for this subframe: - if the UE is an NB-IoT UE, a BL UE or a UE in enhanced coverage: - if the HARQ feedback is disabled by lower layers when downlinkHARQ-FeedbackDisabled is not configured; or - if the HARQ feedback is disabled by downlinkHARQ-FeedbackDisabled for the corresponding HARQ process; or - if the HARQ feedback is enabled by downlinkHARQ-FeedbackDisabled for the corresponding HARQ process and further reversed to disabled by lower layers: - if NB-IoT: - if the UE is configured with a single DL and UL HARQ process; or - if lower layers have indicated scheduling of transmission of multiple TBs and both associated HARQ processes are with disabled HARQ feedback: - start or restart drx-InactivityTimer in the subframe containing the last repetition of the corresponding PDSCH reception + 12 subframes + deltaPDCCH, where deltaPDCCH is the interval starting from the subframe containing the last repetition of the corresponding PDSCH reception plus 12 subframes to the first subframe of the next PDCCH occasion. - else if the HARQ feedback is enabled for the corresponding HARQ process: - if lower layers have indicated scheduling of transmission of multiple TBs: - start the HARQ RTT Timers for all HARQ processes which the HARQ feedback are enabled corresponding to the scheduled TBs in the subframe containing the last repetition of the PDSCH corresponding to the last scheduled TB; - else: - start the HARQ RTT Timer for the corresponding HARQ process in the subframe containing the last repetition of the corresponding PDSCH reception; - else: - start the HARQ RTT Timer for the corresponding HARQ process; - stop the drx-RetransmissionTimer or drx-RetransmissionTimerShortTTI for the corresponding HARQ process. - if NB-IoT, stop drx-ULRetransmissionTimer for all UL HARQ processes. - if the PDCCH indicates an UL transmission for an asynchronous HARQ process or if an UL grant has been configured for an asynchronous HARQ process for this subframe, or if the PDCCH indicates an UL transmission for an autonomous HARQ process or; - if the uplink grant is a configured grant for the MAC entity's AUL C-RNTI and if the corresponding PUSCH transmission has been performed in this subframe: - if mpdcch-UL-HARQ-ACK-FeedbackConfig is not configured; and - if the corresponding HARQ process is not configured with HARQ mode B: - if lower layers have indicated scheduling of transmission of multiple TBs: - start the UL HARQ RTT Timers for all scheduled HARQ processes which are not configured with HARQ mode B in the subframe containing the last repetition of the PUSCH corresponding to the last scheduled TB; - else: - start the UL HARQ RTT Timer for the corresponding HARQ process in the subframe containing the last repetition of the corresponding PUSCH transmission; - stop the drx-ULRetransmissionTimer or drx-ULRetransmissionTimerShortTTI for the corresponding HARQ process; - if mpdcch-UL-HARQ-ACK-FeedbackConfig is configured and an UL HARQ-ACK feedback has not been received on PDCCH until the last repetition of the corresponding PUSCH transmission: - if the corresponding HARQ process is not configured with HARQ mode B: - start or restart the drx-ULRetransmissionTimer for the corresponding HARQ process in the subframe containing the last repetition of the corresponding PUSCH transmission; - if NB-IoT: - if the UE is configured with single UL and DL HARQ process and if the corresponding HARQ process is configured with HARQ mode B; or - if lower layers have indicated scheduling of transmission of multiple TBs and both associated HARQ processes are configured with HARQ mode B: - start or restart drx-InactivityTimer in the subframe containing the last repetition of the corresponding PUSCH transmission + 1 subframe + deltaPDCCH, where deltaPDCCH is the interval starting from the subframe containing the last repetition of the corresponding PUSCH transmission plus 1 subframes to the first subframe of the next PDCCH occasion. - if NB-IoT, stop drx-RetransmissionTimer for all DL HARQ processes. - if the PDCCH indicates a new transmission (DL, UL or SL): - if the UE is an NB-IoT UE: - if the UE is configured with more than one HARQ process and PDCCH indicate the transmission is for a single TB: - start or restart drx-InactivityTimer. - else: - start or restart drx-InactivityTimer. - if the PDCCH indicates a transmission (DL, UL) for an NB-IoT UE: - if the NB-IoT UE is configured with a single DL and UL HARQ process; or - if the PDCCH indicates the transmission is for multiple TBs: - stop drx-InactivityTimer. - stop onDurationTimer. - if the PDCCH indicates an UL HARQ-ACK feedback for an asynchronous UL HARQ process for a UE configured with mpdcch-UL-HARQ-ACK-FeedbackConfig: - if the lower layer had indicated scheduling of transmission of multiple TBs: - stop drx-ULRetransmissionTimer for the corresponding UL HARQ process(es). - else if the PUSCH transmission is completed: - stop drx-ULRetransmissionTimer for all UL HARQ processes. - if the PDCCH indicates HARQ feedback for one or more HARQ processes for which UL HARQ operation is autonomous: - stop the drx-ULRetransmissionTimer for the corresponding HARQ process(es). - in current subframe n, if the MAC entity would not be in Active Time considering grants/assignments/DRX Command MAC control elements/Long DRX Command MAC control elements received and Scheduling Request sent until and including subframe n-5 when evaluating all DRX Active Time conditions as specified in this clause, type-0-triggered SRS, as specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2], shall not be reported. - if CQI masking (cqi-Mask) is setup by upper layers: - in current TTI n, if onDurationTimer would not be running considering grants/assignments/DRX Command MAC control elements/Long DRX Command MAC control elements received until and including TTI n-5 when evaluating all DRX Active Time conditions as specified in this clause, CQI/PMI/RI/PTI/CRI on PUCCH shall not be reported. - else: - in current TTI n, if the MAC entity would not be in Active Time considering grants/assignments/DRX Command MAC control elements/Long DRX Command MAC control elements received and Scheduling Request sent until and including TTI n-5 when evaluating all DRX Active Time conditions as specified in this clause, CQI/PMI/RI/PTI/CRI on PUCCH shall not be reported. For NB-IoT, onDurationTimer may start within a PDCCH period and end within a PDCCH period. The UE shall monitor NPDCCH during these partial PDCCH periods while onDurationTimer is running. Regardless of whether the MAC entity is monitoring PDCCH or not, the MAC entity receives and transmits HARQ feedback and transmits type-1-triggered SRS, as specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2], when such is expected. The MAC entity monitors PDCCH addressed to CC-RNTI for a PUSCH trigger B, as specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2], on the corresponding SCell even if the MAC entity is not in Active Time. when such is expected. When the BL UE or the UE in enhanced coverage or NB-IoT UE receives PDCCH, the UE executes the corresponding action specified in this clause in the subframe following the subframe containing the last repetition of the PDCCH reception where such subframe is determined by the starting subframe and the DCI subframe repetition number field in the PDCCH specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2], unless explicitly stated otherwise. NOTE 1: The same Active Time applies to all activated serving cell(s). NOTE 2: In case of downlink spatial multiplexing, if a TB is received while the HARQ RTT Timer is running and the previous transmission of the same TB was received at least N subframes before the current subframe (where N corresponds to the HARQ RTT Timer), the MAC entity should process it and restart the HARQ RTT Timer. NOTE 3: The MAC entity does not consider PUSCH trigger B, as specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2], to be an indication of a new transmission. NOTE 4: For NB-IoT, for operation in FDD mode, and for operation in TDD mode with a single HARQ process, DL and UL transmissions will not be scheduled in parallel, i.e. if a DL transmission has been scheduled an UL transmission will not be scheduled until HARQ RTT Timer of the DL HARQ process has expired (and vice versa).