Quasi co-location source selection and indication on sidelink

An apparatus for wireless communications performed by a scheduling node, comprising:

• a memory comprising instructions;
• and
• one or more processors configured, individually or in any combination, to execute the instructions and cause the scheduling node to:
• select, from multiple candidates based on one or more criteria, a signal for a first user equipment (UE) to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality;
• and
• signal the first UE an indication of the selection.

An apparatus for wireless communications performed by a first user equipment (UE), comprising:

• a memory comprising instructions;
• and
• one or more processors configured, individually or in any combination, to execute the instructions and cause the first UE to:
• receive signaling from a scheduling node indicating a selection, from multiple candidates based on one or more criteria, of a signal for the first UE to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality;
• and
• communicate with the second UE on the sidelink interface with a receive or transmit beam determined based on the indicated selection.