SCell activation enhancement with assistance reference signal
A user equipment is configured to receive a reference signal when secondary cell (SCell is to be activated. The UE receives a secondary cell (SCell) activation indication for activating an SCell, receives a reference signal (RS) triggering indication for triggering an RS prior to an expected SCell activation period, performs measurements on the triggered RS and activates the SCell based on the RS measurements.
1 . An apparatus comprising processing circuitry coupled to memory, the processing circuitry configured to:
transmit a medium access control (MAC)-control element (CE) comprising at least five octets, wherein a first set of the at least five octets includes four octets comprising a reserved field and 31 secondary cell (SCell) activation fields each corresponding to an SCell index,
wherein a second set of the at least five octets include one or more octets each comprising a reference signal (RS) triggering field for triggering an aperiodic tracking reference signal (TRS) using a radio resource control (RRC) configured TRS index and
wherein a user equipment (UE) performs measurements on the triggered aperiodic TRS and activates one or more SCells based on the MAC-CE.
2 . The apparatus claim 1 , wherein the processing circuitry is further configured to:
transmit a RRC configuration for the aperiodic TRS, the RRC configuration comprising a resource allocation and slot offset for the aperiodic TRS.
3 . The apparatus of claim 1 , wherein the processing circuitry is further configured to:
transmit a further MAC-CE for channel state information (CSI) resource activation.
4 . The apparatus of claim 1 , wherein the processing circuitry is further configured to:
transmit a scheduling downlink control information (DCI) for the MAC-CE.
5 . The apparatus of claim 4 , wherein a slot offset between the scheduling DCI and transmission of the aperiodic TRS is indicated in the scheduling DCI or the MAC-CE.
6 . The apparatus of claim 1 , wherein SCell activation and the aperiodic TRS triggering are indicated in an uplink (UL) downlink control information (DCI).
7 . The apparatus of claim 1 , wherein the processing circuitry is further configured to:
determine a first scheduling offset between the MAC-CE comprising the RS triggering field to transmission of the aperiodic TRS and a second scheduling offset between transmission of the aperiodic TRS to an expected activation of the SCell.
8 . The apparatus of claim 1 , wherein a minimum scheduling offset is reported as a UE capability or hardcoded in the standard.
9 . The apparatus of claim 1 , wherein the aperiodic TRS is configured with a quasi co-location (QCL) relationship with a synchronization signal block (SSB) or a periodic tracking reference signal (P-TRS).
10 . The apparatus of claim 1 , wherein an expected SCell activation period is 3 ms after a hybrid automatic repeat request (HARQ) acknowledgement (HARQ-ACK) transmission for SCell activation.
11 . The apparatus of claim 1 , wherein the aperiodic TRS is one of an aperiodic (AP) tracking reference signal (TRS), a periodic (P) TRS, a semi-persistent (SP) TRS, an AP CSI-RS, a P CSI-RS or an SP CSI-RS.
12 . The apparatus of claim 1 , wherein the UE activating the SCell based on the measurements includes using the measurements for automatic gain control (AGC) adjustment, timing and frequency error tracking, beam refinement and control state information (CSI) measurements for the SCell.
13 . A base station, comprising:
a transceiver configured to communicate with a user equipment (UE); and
one or more processors communicatively coupled to the transceiver and configured to perform operations comprising:
transmitting a medium access control (MAC)-control element (CE) comprising at least five octets, wherein a first set of the at least five octets includes four octets comprising a reserved field and 31 secondary cell (SCell) activation fields each corresponding to an SCell index,
wherein a second set of the at least five octets include one or more octets each comprising a reference signal (RS) triggering field for triggering an aperiodic tracking reference signal (TRS) using a radio resource control (RRC) configured TRS index and
wherein the UE performs measurements on the triggered aperiodic TRS and activates one or more SCells based on the MAC-CE.
14 . The base station of claim 13 , wherein the operations further comprise:
transmitting a radio resource control (RRC) configuration for the aperiodic TRS, the configuration comprising a resource allocation and slot offset for the aperiodic TRS.
15 . The base station of claim 13 , wherein the operations further comprise transmitting a further MAC-CE for channel state information (CSI) resource activation.
16 . The base station of claim 13 , wherein the operations further comprise;
transmitting a scheduling downlink control information (DCI) for the MAC-CE, the scheduling DCI including a field to trigger the aperiodic TRS of the SCell, wherein a slot offset between the scheduling DCI and transmission of the aperiodic TRS is indicated in the scheduling DCI or the MAC-CE.
17 . The base station of claim 13 , wherein SCell activation and the aperiodic TRS triggering are indicated in an uplink (UL) downlink control information (DCI).
18 . The base station of claim 13 , wherein the operations further comprise:
determining a first scheduling offset between the MAC-CE comprising the RS triggering field to transmission of the aperiodic TRS and a second scheduling offset between transmission of the aperiodic TRS to an expected activation of the SCell.
19 . The base station of claim 13 , wherein a minimum scheduling offset is reported as a UE capability or hardcoded in the standard.
20 . The base station of claim 13 , wherein the aperiodic TRS is configured with a quasi co-location (QCL) relationship with a synchronization signal block (SSB) or a periodic tracking reference signal (P-TRS).