Use the below calculator for understanding the timing of several actions upon SCell Activation or Deactivation
SFN
If the UE receives an Activation/Deactivation MAC CE in subframe #n activating the SCell, the UE shall apply the below defined actions no earlier than subframe #n+8 and no later than subframe #n+24 or subframe #n+34 (as defined in section 7.7.2 of 36.133)
― Transmit SRS
on the SCell in case if UL CA and SRS on the SCell is configured;
― PDCCH
monitoring on the SCell;
― PDCCH
monitoring for the SCell (Cross
Carrier Scheduling);
― Start or
restart the sCellDeactivationTimer associated with the SCell;
― Trigger PHR
― CSI reporting
for the SCell: The UE should start transmitting valid CSI report no later than subframe #n+24 or #n+34 (as defined in
section 7.7.2 of 36.133) but it can report out of range (CQI index = 0) values
from subframe #n+8, otherwise the
eNodeB has to do blind decoding of PUSCH (if scheduled) from subframe #n+8 till subframe #n+24 or #n+34
If the UE receives an Activation/Deactivation MAC CE in subframe #n deactivating the SCell or if the sCellDeactivationTimer associated with the activated SCell expires in subframe #n, the UE shall deactivate the SCell no later than subframe #n+8.
If the SCell is
deactivated, the UE shall apply the following actions:
― SRS shall not
be transmitted in case if UL CA and SRS on the SCell is configured
― The UE shall
not transmit UL-SCH on the SCell (UL CA)
― PDCCH on/for
the SCell shall not be monitored.
― The UE shall flush
all HARQ buffers associated with the SCell.
― The UE shall
not transmit RACH on the SCell
― Stop the sCellDeactivationTimer associated with
the SCell (if running);
― The UE shall
stop reporting CSI from subframe #n+8 if
the sCellDeactivationTimer associated
with the SCell expires in subframe #n or
if the UE receives an Activation/Deactivation MAC CE in subframe #n deactivating the SCell
Reference:
3GPP TS 36.321, 36.213, 36.331, 36.133, and 36.300