10.6 Activation/Deactivation Mechanism

To enable reasonable UE battery consumption when CA is configured, an activation/deactivation mechanism of Cells is supported. When an SCell is deactivated, the UE does not need to receive the corresponding PDCCH or PDSCH, cannot transmit in the corresponding uplink, nor is it required to perform CQI measurements. Conversely, when an SCell is active, the UE shall receive PDSCH and PDCCH (if the UE is configured to monitor PDCCH from this SCell) and is expected to be able to perform CQI measurements. NG-RAN ensures that while PUCCH SCell (a Secondary Cell configured with PUCCH) is deactivated, SCells of secondary PUCCH group (a group of SCells whose PUCCH signalling is associated with the PUCCH on the PUCCH SCell) should not be activated. NG-RAN ensures that SCells mapped to PUCCH SCell are deactivated before the PUCCH SCell is changed or removed.

When reconfiguring the set of serving cells:

• SCells added to the set are initially activated or deactivated;
• SCells which remain in the set (either unchanged or reconfigured) do not change their activation status (activated or deactivated).

At handover, LTM cell switch execution or connection resume from RRC_INACTIVE:

• SCells are activated or deactivated.

To enable reasonable UE battery consumption when BA is configured, only one UL BWP for each uplink carrier and one DL BWP or only one DL/UL BWP pair can be active at a time in an active serving cell, all other BWPs that the UE is configured with being deactivated. On deactivated BWPs, the UE does not monitor the PDCCH, does not transmit on PUCCH, PRACH and UL-SCH.

To enable fast SCell activation when CA is configured, one dormant BWP can be configured for an SCell. If the active BWP of the activated SCell is a dormant BWP, the UE stops monitoring PDCCH and transmitting SRS/PUSCH/PUCCH on the SCell but continues performing CSI measurements, AGC and beam management, if configured. A DCI is used to control entering/leaving the dormant BWP for one or more SCell(s) or one or more SCell group(s).

The dormant BWP is one of the UE's dedicated BWPs configured by network via dedicated RRC signalling. The SpCell and PUCCH SCell cannot be configured with a dormant BWP.

To enable fast SCell activation when CA is configured, aperiodic CSI-RS for tracking for fast SCell activation can be configured for an SCell to assist AGC and time/frequency synchronization. A MAC CE is used to trigger activation of one or more SCell(s) and trigger the aperiodic CSI-RS for tracking for fast SCell activation for a (set of) deactivated SCell(s).

To reduce unknown SCell activation delay, the measurement reporting for fast unknown SCell activation can be configured. The RRC measurement report is initiated when UE receives SCell Activation MAC CE to activate, at least, one SCell which is unknown SCell and has the valid L3 measurement result according to the requirements specified in clause 6.3 of TS 38.133 [13]. In addition, the delay requirement of unknown SCell activation can be reduced by beam sweeping factor reduction or shorter measurement interval based on UE capability as specified in TS 38.133 [13].