Secondary cell activation / deactivationV15.11.0

Scell Activation

When a UE receives in a PDSCH (MAC Control Element, see TS 38.321) an activation command for a secondary cell ending in slot n, the UE applies the corresponding actions in TS 38.321 no later than the minimum requirement defined in TS 38.133 and no earlier than slot n + k , except for the following:

  • the actions related to CSI reporting on a serving cell that is active in slot n + k
  • the actions related to the sCellDeactivationTimer associated with the secondary cell (TS 38.321) that the UE applies in slot n + k
  • the actions related to CSI reporting on a serving cell which is not active in slot n + k that the UE applies in the earliest slot after n + k in which the serving cell is active.
TasksSCell status before activation commandEffective time
no earlier thanno later than
SRS transmissions on the SCell-n+k
PDCCH monitoring on the SCell
PDCCH monitoring for the SCell
PUCCH transmissions on the SCell, if configured
activate the DL BWP and UL BWP indicated by firstActiveDownlinkBWP-Id and firstActiveUplinkBWP-Id respectivelydeactivated
(re-)initialize any suspended configured uplink grants of configured grant Type 1 associated with this SCell according to the stored configuration, if any, and to start in the symbol according to rules in TS 38.321 clause 5.8.2deactivated
trigger PHR according to TS 38.321 clause 5.4.6deactivated
start or restart the sCellDeactivationTimer associated with the SCell-n+k
CSI reporting on a serving cellactive
deactivatedearliest slot after n+k in which the serving cell is active
  • The value of k is where k1 is a number of slots for a PUCCH transmission with HARQ-ACK information for the PDSCH reception and is indicated by the PDSCH-to-HARQ_feedback timing indicator field in the DCI format scheduling the PDSCH reception as described in Clause 9.2.3, and is a number of slots per subframe for the SCS configuration μ of the PUCCH transmission.
  • THARQ (in ms) is the timing between DL data transmission and acknowledgement
  • Tactivation_time is the SCell activation delay in millisecond, see TS 38.133 clause 8.3.2 for details.
  • TCSI_Reporting is the delay (in ms) including uncertainty in acquiring the first available downlink CSI reference resource, UE processing time for CSI reporting and uncertainty in acquiring the first available CSI reporting resources

SCell Deactivation

If a UE receives a deactivation command for a secondary cell ending in slot n, the UE applies the corresponding actions in TS 38.321 no later than the minimum requirement defined in TS 38.133, except for the actions related to CSI reporting on an activated serving cell, which the UE applies in slot n+k.

If the sCellDeactivationTimer associated with the secondary cell expires in slot n, the UE applies the corresponding actions in TS 38.321 no later than the minimum requirement defined in TS 38.133, except for the actions related to CSI reporting on an activated serving cell which the UE applies in the first slot that is after slot , where μ is the SCS configuration for PDSCH reception on the secondary cell.

TasksDeactivation triggerEffective time
deactivate the SCell-no latter than:

stop the sCellDeactivationTimer associated with the SCell
stop the bwp-InactivityTimer associated with the SCell
deactivate any active BWP associated with the SCell
clear any configured downlink assignment and any configured uplink grant Type 2 associated with the SCell respectively
suspend any configured uplink grant Type 1 associated with the SCell
flush all HARQ buffers associated with the SCell
clear any PUSCH resource for semi-persistent CSI reporting associated with the SCellMAC CEn+k
sCellDeactivationTimer expiryfirst slot after

if the SCell is deactivated, UE shall:

  • not transmit SRS on the SCell
  • not report CSI for the SCell
  • not transmit on UL-SCH on the SCell
  • not transmit on RACH on the SCell
  • not monitor the PDCCH on the SCell
  • not monitor the PDCCH for the SCell
  • not transmit PUCCH on the SCell
  • abort ongoing Random Access procedure on the SCell, if any