On-demand measurement gap for inter-frequency RRM measurements

1. A method for wireless communications by a user equipment (UE), the method comprising:

providing capability information to a serving cell indicating a first duration for the UE to retune to a target cell frequency of one or more target cells and a second duration for the UE to retune back to a serving frequency of the serving cell or receiving an indication from the serving cell of a fixed retuning latency;

receiving an on-demand measurement gap configuration from the serving cell configuring a semi-persistent or aperiodic measurement gap for measurement of the one or more target cells; and

measuring the one or more target cells during the semi-persistent or aperiodic measurement gap.

2. The method of claim 1 , wherein:

the serving cell and the one or more target cells are asynchronous; and

different target cells, of the one or more target cells, in a same frequency are asynchronous.

3. The method of claim 1 , wherein the UE is configured to perform inter-frequency radio resource measurement (RRM) of a synchronization signal block (SSB) or a UE-specific channel state information reference signal (CSI-RS) of the one or more target cells.

4. The method of claim 1 , wherein receiving the on-demand measurement gap configuration comprises receiving a first indication of a latency duration between reception of an on-demand indicator from the serving cell and the UE retuning to the target cell frequency of the one or more target cells and a second indication of a duration of the measurement gap until the UE retunes to the serving frequency of the serving cell.

5. The method of claim 4 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap; and

receiving the on-demand measurement gap configuration further comprises receiving a third indication of a periodicity of the semi-persistent measurement gap and a duration for the UE to use the on-demand measurement gap configuration.

6. The method of claim 4 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap; and

receiving the on-demand measurement gap configuration further comprises receiving a third indication of a periodicity of the semi-persistent measurement gap and a number of periods to use the on-demand measurement gap configuration.

7. The method of claim 4 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap;

receiving the on-demand measurement gap configuration further comprises receiving a third indication of a periodicity of the semi-persistent measurement gap; and

the method further comprises receiving a fourth indication from the serving cell to deactivate the on-demand measurement gap configuration.

8. The method of claim 7 , wherein the fourth indication to deactivate the on-demand measurement gap configuration comprises a medium access control (MAC) control element (CE) or downlink control information (DCI).

9. The method of claim 1 , wherein the on-demand measurement gap configuration is received via a medium access control (MAC) control element (CE) or downlink control information (DCI).

10. The method of claim 1 , wherein:

the on-demand measurement gap configuration is received via radio resource control (RRC) signaling; and

the on-demand measurement gap is activated via a medium access control (MAC) control element (CE) or downlink control information (DCI).

11. The method of claim 1 , further comprising sending a request to the serving cell for a measurement gap, wherein the on-demand measurement gap configuration is received in response to the request.

12. The method of claim 11 , wherein the request is sent via a random access channel (RACH) message or a physical uplink control channel (PUCCH) transmission.

13. A method for wireless communications by a base station (BS) in a serving cell, the method comprising:

configuring at least one user equipment (UE) in the serving cell for measurement of one or more target cells;

determining a duration of a semi-persistent or aperiodic measurement gap for the at least one UE based on a first duration for the at least one UE to retune to a target frequency of the one or more target cells, a second duration for the at least one UE to perform measurements of the one or more target cells, and a third duration for the at least one UE to tune back to a serving frequency of the serving cell; and

configuring the at least one UE with an on-demand measurement gap configuration configuring the semi-persistent or aperiodic measurement gap for measuring the one or more target cells.

14. The method of claim 13 , wherein:

the serving cell and the one or more target cells are asynchronous; and

different target cells, of the one or more target cells, in a same frequency are asynchronous.

15. The method of claim 13 , wherein the configuring the at least one UE for measurement of the one or more target cells comprises configuring the at least one UE to measure a synchronization signal block (SSB) or a UE-specific channel state information reference signal (CSI-RS) of the one or more target cells.

16. The method of claim 13 , wherein the configuring the on-demand measurement gap configuration comprises:

providing the at least one UE with a first indication of a latency duration between reception of an on-demand indicator from the serving cell and the at least one UE retuning to the target frequency of the one or more target cells; and

a second indication of a duration of the semi-persistent or aperiodic measurement gap until the at least one UE retunes to the serving frequency of the serving cell.

17. The method of claim 16 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap; and

the configuring the on-demand measurement gap configuration further comprises providing third indication of a periodicity of the semi-persistent measurement gap and a duration for the at least one UE to use the on-demand measurement gap configuration.

18. The method of claim 16 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap; and

the configuring the on-demand measurement gap configuration further comprises providing a third indication of a periodicity of the semi-persistent measurement gap and a number of periods to use the on-demand measurement gap configuration.

19. The method of claim 16 , wherein:

the on-demand measurement gap configuration configures the semi-persistent measurement gap;

configuring the on-demand measurement gap configuration further comprises providing a third indication of a periodicity of the semi-persistent measurement gap; and

the method further comprises providing a fourth indication to deactivate the on-demand measurement gap configuration.

20. The method of claim 13 , wherein:

the method further comprises receiving capability information from the UE indicating the first duration and the third duration; or

determining the first duration and the third duration based on a fixed retuning latency.

21. The method of claim 13 , wherein:

the method further comprises receiving an indication from the one or more target cells of the second duration; and

the second duration comprises a duration of synchronization signal block (SSB) transmissions by the one or more target cells or a duration associated with a channel state information reference signal (CSI-RS) configuration and a numerology of the one or more target cells.

22. The method of claim 13 , wherein the on-demand measurement gap configuration is configured via at least one of: radio resource control (RRC) signaling, medium access control (MAC) control element (CE), or downlink control information (DCI).

23. An apparatus for wireless communications, the apparatus comprising:

means for providing capability information to a serving cell indicating a first duration for the apparatus to retune to a target cell frequency of one or more target cells and a second duration for the apparatus to retune back to a serving frequency of the serving cell or receiving an indication from the serving cell of a fixed retuning latency;

means for receiving an on-demand measurement gap configuration from the serving cell configuring a semi-persistent or aperiodic measurement gap for measurement of the one or more target cells; and

means for measuring the one or more target cells during the semi-persistent or aperiodic measurement gap.