Quasi co-location assumptions for aperiodic channel state information reference signal triggers
Certain aspects of the present disclosure relate to quasi co-location assumptions for aperiodic channel state information (CSI) reference signals (RS) in communications systems operating according to NR techniques. An exemplary method that may be performed by a UE includes determining a quasi-co-location (QCL) relationship of an aperiodic channel state information (CSI) reference signal (CSI-RS) to a physical channel and processing the aperiodic CSI-RS according to the determined QCL relationship.
1. A method for wireless communications by a user equipment (UE), comprising:
determining a quasi-co-location (QCL) relationship of an aperiodic channel state information (CSI) reference signal (CSI-RS) to a physical channel, wherein:
the determination of the QCL relationship is based on:
an offset parameter related to the aperiodic CSI-RS and a downlink control information (DCI) scheduling the aperiodic CSI-RS, and
a threshold value of a time for the UE to switch between receive beams, and
determining the QCL relationship comprises determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is lower than the threshold value; and
processing the aperiodic CSI-RS according to the determined QCL relationship.
2. The method of claim 1 , wherein determining the QCL relationship comprises determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is not yet determined by the UE.
3. The method of claim 1 , wherein determining the QCL relationship comprises determining to use a QCL relationship indicated in a grant of time and frequency resources of another transmission, wherein the granted time and frequency resources include time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined by the UE.
4. The method of claim 1 , wherein determining the QCL relationship comprises determining to use a QCL relationship of a unicast physical downlink shared channel (PDSCH) on a set of time and frequency resources including time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined by the UE.
5. A method for wireless communications by a base station (BS), comprising:
determining a quasi-co-location (QCL) relationship of an aperiodic channel state information (CSI) reference signal (CSI-RS) to a physical channel, wherein:
the determination of the QCL relationship is based on:
an offset parameter related to the aperiodic CSI-RS and a downlink control information (DCI) scheduling the aperiodic CSI-RS, and
a threshold value of a time for a user equipment (UE) to switch between receive beams, and
determining the QCL relationship comprises determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is lower than the threshold value; and
transmitting, to the UE, the aperiodic CSI-RS according to the determined QCL relationship.
6. The method of claim 5 , wherein determining the QCL relationship comprises determining to use a QCL relationship of a physical downlink control channel (PDCCH) of control resource set (CORESET) having a lowest identifier (CORESET ID), when the offset parameter is not yet determined.
7. The method of claim 5 , wherein determining the QCL relationship comprises determining to use a QCL relationship indicated in a grant of time and frequency resources of another transmission, wherein the granted time and frequency resources include time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined.
8. The method of claim 5 , wherein determining the QCL relationship comprises determining to use a QCL relationship of a unicast physical downlink shared channel (PDSCH) on a set of time and frequency resources including time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined.
9. An apparatus for wireless communications by a user equipment (UE), comprising:
a memory; and
at least one processor coupled to the memory, the memory and the at least one processor configured to:
determine a quasi-co-location (QCL) relationship of an aperiodic channel state information (CSI) reference signal (CSI-RS) to a physical channel, wherein:
the determination of the QCL relationship is based on:
an offset parameter related to the aperiodic CSI-RS and a downlink control information (DCI) scheduling the aperiodic CSI-RS, and
a threshold value of a time for the UE to switch between receive beams, and
the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is lower than the threshold value; and
process the aperiodic CSI-RS according to the determined QCL relationship.
10. The apparatus of claim 9 , wherein the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is not yet determined by the UE.
11. The apparatus of claim 9 , wherein the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship indicated in a grant of time and frequency resources of another transmission, and wherein the granted time and frequency resources include time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined by the UE.
12. The apparatus of claim 9 , wherein the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship of a unicast physical downlink shared channel (PDSCH) on a set of time and frequency resources including time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined by the UE.
13. An apparatus for wireless communications by a base station (BS), comprising:
a memory; and
at least one processor coupled to the memory, the memory and the at least one processor configured to:
determine a quasi-co-location (QCL) relationship of an aperiodic channel state information (CSI) reference signal (CSI-RS) to a physical channel, wherein:
the determination of the QCL relationship is based on:
an offset parameter related to the aperiodic CSI-RS and a downlink control information (DCI) scheduling the aperiodic CSI-RS, and
a threshold value of a time for a user equipment (UE) to switch between receive beams, and
the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship of a physical downlink control channel (PDCCH) of a control resource set (CORESET) having a lowest identifier (CORESET-ID), when the offset parameter is lower than the threshold value; and
transmit, to the UE, the aperiodic CSI-RS according to the determined QCL relationship.
14. The apparatus of claim 13 , wherein the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship of a physical downlink control channel (PDCCH) of control resource set (CORESET) having a lowest identifier (CORESET ID), when the offset parameter is not yet determined.
15. The apparatus of claim 13 , wherein the memory and the at least one processor are further configured to determine the QCL relationship by determining to use a QCL relationship indicated in a grant of time and frequency resources of another transmission, wherein the granted time and frequency resources include time and frequency resources of the aperiodic CSI-RS, when the offset parameter is not yet determined.