Indication to update uplink and downlink beams
Apparatus, methods, processing systems, and computer readable mediums enable L 1 (physical layer) and L 2 (medium access control (MAC) layer) inter-cell mobility. More specifically, rules and operations performed during L 1 /L 2 based cell handover operations. A user equipment (UE) is configured to receive, from a network entity of a source cell via at least one of L 1 or L 2 signaling, a handover command for the UE to handover from the source cell to a target cell. The UE determines at least one transient period during which the UE is served by both the source cell and the target cell, and performs the handover while communicating with the source cell and target cell during the transient period.
1. A method for wireless communications performed by a user equipment (UE), comprising:
receiving, from a network entity, signaling indicating a simultaneous update having a first update to a transmit beam used by the UE for an uplink transmission and a second update to a receive beam used by the UE for a downlink transmission, wherein:
the signaling comprises downlink control information (DCI) and a media access control (MAC) control element (CE);
the signaling updates a common beam for a set of downlink and uplink resources; and
the signaling further indicates:
the first update to the transmit beam via an uplink spatial relation ID of one or more target uplink signals; and
the second update to the receive beam via a downlink transmission configuration indicator (TCI) ID of one or more target downlink signals; and
performing the simultaneous update by applying the first update to the uplink transmission and applying the second update to the downlink transmission.
2. The method of claim 1 , wherein:
the target downlink signals comprise at least one of a physical downlink shared channel (PDSCH), a physical downlink control channel (PDCCH), or a channel state information (CSI) reference signal (CSI-RS); and
the target uplink signals comprise at least one of a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), a sounding reference signal (SRS), or a physical random access channel (PRACH).
3. The method of claim 1 , wherein the signaling further indicates both an ID of the receive beam and an ID of the transmit beam.
4. The method of claim 1 , further comprising receiving a grouping indication indicating the downlink TCI ID and a UL beam ID are grouped together and assigned a group ID, wherein the signaling further indicates the group ID.
5. The method of claim 1 , wherein the signaling updates a downlink transmission configuration indicator (TCI) of at least one reference signal (RS) resource, wherein:
the at least one RS resource serves as a quasi co-location (QCL) source RS in both a second downlink TCI associated with the one or more target downlink signals, and an uplink spatial relation; or
the at least one RS resource serves as a QCL source RS in an uplink TCI associated with the one or more target uplink signals.
6. The method of claim 5 , wherein;
the at least one RS resource serves as the QCL RS in both the second downlink TCI associated with the one or more target downlink signals, and the uplink spatial relation; and
the target downlink signals are linked to a TCI state which indicates a beam the network entity will use to transmit the target downlink signals and comprise at least one of a physical downlink shared channel (PDSCH), a physical downlink control channel (PDCCH), or a channel state information (CSI) reference signal (CSI-RS).
7. The method of claim 6 , wherein the TCI state is linked to at least one of a CSI-RS, synchronization signal block (SSB), or sounding reference signal, wherein the at least one of the CSI-RS, the SSB, or the sounding reference signal serves as a source RS of the TCI.
8. The method of claim 5 , wherein:
the at least one RS resource serves as the QCL source RS in the uplink TCI associated with the one or more target uplink signals; and
the target uplink signals comprise at least one of a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH) linked to a TCI state which indicates a beam the network entity will use to transmit one or more source reference signals.
9. The method of claim 8 , wherein the TCI state is linked to at least one of a CSI-RS, synchronization signal block (SSB), or sounding reference signal, wherein the at least one of the CSI-RS, the SSB, or the sounding reference signal serves as a source RS of the TCI.
10. The method of claim 1 , wherein:
the signaling is provided via a wake up signal (WUS); and
the UE is configured to apply the simultaneous update in one or more ON durations after the WUS.
11. The method of claim 1 , further comprising:
sending a capability indication, to the network entity, indicating capability of the UE to support, according to one or more options, the first update to the transmit beam and the second update to the receive beam; and
receiving an enablement indication, from the network entity, indicating enablement of one or more of the options.
12. A method for wireless communications performed by a network entity, comprising:
sending, to a user equipment (UE), signaling indicating a simultaneous update having a first update to a transmit beam used by the UE for an uplink transmission and a second update to a receive beam used by the UE for downlink transmission, wherein:
the signaling comprises downlink control information (DCI) and a media access control (MAC) control element (CE);
the signaling updates a common beam for a set of downlink and uplink resources; and
the signaling further indicates:
the first update to the transmit beam via an uplink spatial relation ID of one or more target uplink signals; and
the second update to the receive beam via a downlink transmission configuration indicator (TCI) ID of one or more target downlink signals; and
performing the simultaneous update by applying the first update to the uplink transmission and applying the second update to the downlink transmission.
13. The method of claim 12 , wherein:
the target downlink signals comprise at least one of a physical downlink shared channel (PDSCH), a physical downlink control channel (PDCCH), or a channel state information (CSI) reference signal (CSI-RS); and
the target uplink signals comprise at least one of a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), a sounding reference signal (SRS), or a physical random access channel (PRACH).
14. The method of claim 12 , wherein the signaling further indicates both an ID of the receive beam and an ID of the transmit beam.
15. The method of claim 12 , further comprising transmitting a grouping indication, to the UE, indicating the downlink TCI ID and a UL beam ID are grouped together and assigned a group ID, wherein the signaling further indicates the group ID.
16. The method of claim 12 , wherein the signaling updates a downlink transmission configuration indicator (TCI) of at least one reference signal (RS) resource, wherein:
the at least one RS resource serves as a quasi co-location (QCL) source RS in both a second downlink TCI associated with the one or more target downlink signals, and an uplink spatial relation; or
the at least one RS resource serves as a QCL source RS in an uplink TCI associated with the one or more target uplink signals.
17. The method of claim 16 , wherein:
the at least one RS resource serves as the QCL RS in both the second downlink TCI associated with the one or more target downlink signals, and the uplink spatial relation; and
the target downlink signals are linked to a TCI state which indicates a beam the network entity will use to transmit the target downlink signals and comprise at least one of a physical downlink shared channel (PDSCH), a physical downlink control channel (PDCCH), or a channel state information (CSI) reference signal (CSI-RS).
18. The method of claim 17 , wherein the TCI state is linked to at least one of a CSI-RS, synchronization signal block (SSB), or sounding reference signal, wherein the at least one of the CSI-RS, the SSB, or the sounding reference signal serves as a source RS of the TCI.
19. The method of claim 16 , wherein:
the at least one RS resource serves as the QCL source RS in the uplink TCI associated with the one or more target uplink signals; and
the target uplink signals comprise at least one of a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH) linked to a TCI state which indicates a beam the network entity will use to transmit one or more source reference signals.
20. The method of claim 19 , wherein the TCI state is linked to at least one of a CSI-RS, synchronization signal block (SSB), or sounding reference signal, wherein the at least one of the CSI-RS, the SSB, or the sounding reference signal serves as a source RS of the TCI.
21. The method of claim 12 , wherein:
the signaling is provided via a wake up signal (WUS); and
the UE is configured to apply the simultaneous update in one or more ON durations after the WUS.
22. The method of claim 12 , further comprising:
receiving a capability indication, from the UE, indicating capability of the UE to support, according to one or more options, the first update to the transmit and the second update to the receive beam; and
sending an enablement indication, to the UE, indicating enablement of one or more of the options.
23. A processing system for wireless communication by a relay node, comprising:
one or more processors individually or collectively configured to execute instructions stored on one or more memories and to cause the relay node to:
receive, from a network entity, signaling indicating a simultaneous update having a first update to a transmit beam used by a user equipment (UE) for an uplink transmission and a second update to a receive beam used by the UE for downlink transmission, wherein:
the signaling comprises downlink control information (DCI) and a media access control (MAC) control element (CE);
the signaling updates a common beam for a set of downlink and uplink resources; and
the signaling further indicates:
the first update to the transmit beam via an uplink spatial relation ID of one or more target uplink signals; and
the second update to the receive beam via a downlink transmission configuration indicator (TCI) ID of one or more target downlink signals; and
perform the simultaneous update by applying the first update to the uplink transmission and applying the second update to the downlink transmission.
24. A processing system for wireless communication by a relay node, comprising:
one or more processors individually or collectively configured to execute instructions stored on one or more memories and to cause the relay node to:
send, to a user equipment (UE), signaling indicating a simultaneous update having a first update to a transmit beam used by the UE for an uplink transmission and a second update to a receive beam used by the UE for a downlink transmission, wherein:
the signaling comprises downlink control information (DCI) and a media access control (MAC) control element (CE);
the signaling updates a common beam for a set of downlink and uplink resources; and
the signaling further indicates:
the first update to the transmit beam via an uplink spatial relation ID of one or more target uplink signals; and
the second update to the receive beam via a downlink transmission configuration indicator (TCI) ID of one or more target downlink signals; and
perform the simultaneous update by applying the first update to the uplink and applying the second update to the downlink transmission.