Configuration for user equipment intra-frequency measurement of sounding reference signals
Certain aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for a UE to measure sounding reference signal (SRS) transmission from another UE. The measurements results may be used, for example, by a serving cell for interference mitigation purposes. For example, the disclosed techniques may include a first UE receiving a configuration for measuring SRS transmitted by a second UE; determining a first bandwidth part (BWP) associated with the configuration; determining a frequency reference point for the SRS to be measured; determining SRS measurement resources, based on one or more parameters of the configuration and the frequency reference point; and measuring SRS transmitted by the second UE on the determined SRS measurement resources.
1. A method for wireless communications by a first user equipment (UE), comprising:
receiving a configuration for measuring sounding reference signals (SRS) transmitted by a second UE;
determining a first bandwidth part (BWP) associated with the configuration;
determining a frequency reference point for the SRS to be measured;
determining SRS measurement resources, based on one or more parameters of the configuration and the frequency reference point; and
measuring SRS transmitted by the second UE on the determined SRS measurement resources.
2. The method of claim 1 , wherein:
the configuration for measuring SRS is provided within a configuration of the first BWP;
the first BWP is identified via a BWP-ID included in the configuration for measuring SRS; or
a starting RB of the first BWP is included in the configuration for measuring SRS, and the first BWP is either:
a BWP configured to the first UE for wireless communications; or
a virtual BWP that is not configured to the first UE for wireless communications and one, multiple or all the other BWP configurations including BWP-ID and frequency bandwidth of the virtual BWP are not provided by network.
3. The method of claim 2 , wherein, the frequency reference point is determined as either:
a lowest subcarrier of the first BWP; or
a lowest subcarrier of a common resource block of a serving cell for the first UE, depending on a value of a parameter indicating a shift in terms of a number of resource blocks (RBs) relative to a starting RB of the first BWP.
4. The method of claim 1 , wherein, if the first BWP is not identified via a BWP-ID included in the configuration for measuring SRS or a starting RB of the first BWP is not included in the configuration for measuring SRS, the frequency reference point is determined as a lowest subcarrier of a common resource block of a serving cell for the first UE.
5. The method of claim 2 , wherein the first UE considers the configuration as invalid if a frequency range of the determined SRS measurement resources exceeds a frequency bandwidth of the first BWP that is configured for wireless communications and is not a virtual BWP.
6. The method of claim 2 , wherein the first UE considers the configuration as invalid if a subcarrier spacing (SCS) of the determined SRS measurement resources is different from an SCS of the first BWP that is configured for wireless communications and is not a virtual BWP.
7. The method of claim 1 , wherein the UE is configured to only measure SRS measurement resources within the first BWP if the first BWP is configured for wireless communications and is not a virtual BWP.
8. The method of claim 1 , wherein:
the UE is configured with at least a second BWP for wireless communications that is not a virtual BWP; and
the UE is configured to measure SRS measurement resources within a second BWP if one or more conditions are met.
9. The method of claim 8 , wherein the one or more conditions comprise:
frequency range of the SRS measurement resources is fully within the bandwidth of the second BWP; and
the SRS measurement resources and the second BWPs have a same subcarrier spacing (SCS).
10. The method of claim 9 , wherein the frequency reference point comprises:
a starting resource block (RB) of the first BWP; or
a lowest subcarrier of a common resource block of a serving cell for the first UE, depending on a value of a parameter indicating a shift in terms of a number of resource blocks (RBs) relative to a starting RB of the first BWP.
11. The method of claim 8 , wherein the first UE considers the configuration as invalid if a frequency range of the determined SRS measurement resources exceeds a frequency bandwidth of both the first BWP, if the first BWP is configured for wireless communications and is not a virtual BWP, and the second BWP.
12. The method of claim 8 , wherein the first UE considers the configuration as invalid if a subcarrier spacing (SCS) of the determined SRS measurement resources is different from an SCS of both the first BWP if the first BWP is configured for wireless communications and is not a virtual BWP and the second BWP.
13. A method for wireless communications by a first user equipment (UE), comprising:
receiving a configuration of sounding reference signals (SRS) measurement resources for measuring SRS transmitted by a second UE;
determining a maximum number of SRS measurement resources supported by the first UE based on a UE capability; and
measuring SRS transmitted by the second UE based on the configuration and the determined maximum number of SRS measurement resources supported by the first UE.
14. The method of claim 13 , wherein the capability comprises at least one of:
a standalone max number for SRS measurement resources; or
a joint maximum number for SRS measurement resources together with at least one of channel state information reference signal (CSI-RS) or synchronization signal block (SSB) resources.
15. The method of claim 13 , wherein:
the UE counts a total number of ports across the configured resources against the maximum number of SRS measurement resources supported by the first UE; or
the UE counts a total number of the configured resources against the maximum number of SRS measurement resources supported by the first UE.
16. The method of claim 13 , further comprising, if an SRS measurement resource is configured but the UE is not required to measure the resource in a current active BWP, deciding whether or not to count that SRS measurement resource against the maximum number of SRS measurement resources supported by the first UE.
17. The method of claim 16 , wherein the UE does not count that SRS resource against the maximum number of SRS measurement resources supported by the first UE.
18. A method for wireless communications by a network entity, comprising:
sending, to a first user equipment (UE), a configuration for measuring sounding reference signals (SRS) transmitted by a second UE;
configuring the UE with at least a first bandwidth part (BWP) associated with the configuration; and
receiving, from the first UE, a report of SRS transmitted by the second UE on measurement resources determined based on a frequency reference point and one or more parameters of the configuration and the frequency reference point.
19. The method of claim 18 , wherein:
the configuration for measuring SRS is provided within a configuration of the first BWP;
the first BWP is identified via a BWP-ID included in the configuration for measuring SRS; or
a starting RB of the first BWP is included in the configuration for measuring SRS, and the first BWP is either:
a BWP configured to the first UE for wireless communications; or
a virtual BWP that is not configured to the first UE for wireless communications and one, multiple or all the other BWP configurations including BWP-ID and frequency bandwidth of the virtual BWP are not provided by the network entity.
20. The method of claim 19 , wherein, the frequency reference point is determined as either:
a lowest subcarrier of the first BWP; or
a lowest subcarrier of a common resource block of a serving cell for the first UE, depending on a value of a parameter indicating a shift in terms of a number of resource blocks (RBs) relative to a starting RB of the first BWP.
21. The method of claim 18 , wherein, if the first BWP is not identified via a BWP-ID included in the configuration for measuring SRS or a starting RB of the first BWP is not included in the configuration for measuring SRS, the frequency reference point is determined as a lowest subcarrier of a common resource block of a serving cell for the first UE.
22. The method of claim 18 , wherein the UE is configured to only measure SRS measurement resources within the first BWP if the first BWP is configured for wireless communications and is not a virtual BWP.
23. The method of claim 18 , wherein:
the UE is configured with at least a second BWP for wireless communications and is not a virtual BWP; and
the UE is configured to measure SRS measurement resources within a second BWP if one or more conditions are met.
24. The method of claim 23 , wherein the one or more conditions comprise:
frequency range of the SRS measurement resources is fully within the bandwidth of the second BWP; and
the SRS measurement resources and the second BWPs have a same subcarrier spacing (SCS).
25. The method of claim 24 , wherein the frequency reference point comprises:
a starting resource block (RB) of the first BWP; or
a lowest subcarrier of a common resource block of a serving cell for the first UE, depending on a value of a parameter indicating a shift in terms of a number of resource blocks (RBs) relative to a starting RB of the first BWP.
26. A method for wireless communications by a network entity, comprising:
sending, to a first user equipment (UE), a configuration for measuring sounding reference signals (SRS) transmitted by a second UE;
configuring the UE with at least a first bandwidth part (BWP) associated with the configuration; and
receiving, from the first UE, a report of SRS transmitted by the second UE, subject to a maximum number of SRS measurement resources supported by the first UE based on a UE capability.
27. The method of claim 26 , wherein the capability comprises at least one of:
a standalone max number for SRS measurement resources; or
a joint maximum number for SRS measurement resources together with at least one of channel state information reference signal (CSI-RS) or synchronization signal block (SSB) resources.
28. The method of claim 26 , wherein:
the UE counts a total number of ports across the configured resources against the maximum number of SRS measurement resources supported by the first UE; or
the UE counts a total number of the configured resources against the maximum number of SRS measurement resources supported by the first UE.
29. The method of claim 26 , further comprising, if an SRS measurement resource is configured but the UE is not required to measure the resource in a current active BWP, deciding whether or not the UE is to count that SRS measurement resource against the maximum number of SRS measurement resources supported by the first UE.
30. The method of claim 29 , wherein the UE is not to count that SRS resource against the maximum number of SRS measurement resources supported by the first UE.