Multiple sounding reference signal transmissions triggered by downlink control information
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may use the techniques described herein to identify slots in which to transmit multiple sounding reference signal (SRS) resource sets triggered by one or more downlink control information (DCI) messages. In one aspect, the UE may determine a next available slot for transmitting an SRS resource set based on the available information at a timestamp and on a reference slot (e.g., the slot in which the latest DCI message is received or a slot that is offset from the slot in which the latest DCI message is received). In yet another aspect, the UE may receive one or more indications of slots in which to transmit the multiple SRS resource sets. In yet another aspect, the UE may follow one or more rules to identify slots in which to transmit the multiple SRS resource sets.
1. A method for wireless communication at a user equipment (UE), comprising:
receiving, at a first time, a first downlink control information message from a first transmission and reception point, the first downlink control information message triggering transmission of a first set of sounding reference signals via a first sounding reference signal resource set;
receiving, at a second time, a second downlink control information message from a second transmission and reception point, the second downlink control information message triggering transmission of a second set of sounding reference signals via a second sounding reference signal resource set, wherein the first time occurs before the second time;
identifying a same reference slot for the first sounding reference signal resource set and the second sounding reference signal resource set;
identifying a timestamp as a last symbol of a control channel that includes the second downlink control information message or a last symbol of a search space associated with the control channel that includes the second downlink control information message;
identifying each of a first available slot for the first sounding reference signal resource set and a second available slot for the second sounding reference signal resource set based at least in part on a processing time after the timestamp, wherein the first available slot is offset from the same reference slot by a first available slot offset and the second available slot is offset from the same reference slot by a second available slot offset; and
transmitting the first set of sounding reference signals via the first sounding reference signal resource set in the first available slot and the second set of sounding reference signals via the second sounding reference signal resource set in the second available slot.
2. The method of claim 1 , further comprising:
determining the same reference slot to be a slot in which the second downlink control information message is received.
3. The method of claim 1 , further comprising:
receiving an indication of an offset in the second downlink control information message; and
determining the same reference slot based at least in part on the offset and a slot in which the second downlink control information message is received.
4. A method for wireless communication at a user equipment (UE), comprising:
receiving a configuration message indicating a first list of multiple offsets for a first sounding reference signal resource set and a second list of multiple offsets for a second sounding reference signal resource set;
receiving a single downlink control information message triggering transmission of a first set of sounding reference signals via the first sounding reference signal resource set and a second set of sounding reference signals via the second sounding reference signal resource set and indicating a first available slot offset from the first list of multiple offsets corresponding to a first available slot for the first sounding reference signal resource set and a second available slot offset from the second list of multiple offsets corresponding to a second available slot for the second sounding reference signal resource set; and
transmitting the first set of sounding reference signals via the first sounding reference signal resource set in the first available slot, the second set of sounding reference signals via the second sounding reference signal resource set in the second available slot, or both.
5. The method of claim 4 , further comprising:
receiving, in the single downlink control information message, a bit field indicating the first available slot offset and the second available slot offset.
6. The method of claim 4 , further comprising:
receiving, in the configuration message, a first list of triggering codes for triggering transmission of the first set of sounding reference signals via the first sounding reference signal resource set, wherein each triggering code in the first list of triggering codes corresponds to an offset for the first sounding reference signal resource set; and
receiving, in the single downlink control information message, a triggering code from the first list of triggering codes triggering transmission of the first set of sounding reference signals via the first sounding reference signal resource set and indicating the first available slot offset.
7. The method of claim 4 , further comprising:
receiving, in the single downlink control information message, a first bit field indicating the first available slot offset and a second bit field indicating the second available slot offset.
8. The method of claim 7 , further comprising:
determining that the first bit field indicates the first available slot offset and the second bit field indicates the second available slot offset based at least in part on an order of the first bit field and the second bit field in the single downlink control information message.
9. The method of claim 4 , further comprising:
identifying the first available slot for the first sounding reference signal resource set before the second available slot for the second sounding reference signal resource set; and
identifying the second available slot for the second sounding reference signal resource set based at least in part on the first available slot being unavailable for the second sounding reference signal resource set.
10. The method of claim 9 , wherein identifying the first available slot before the second available slot comprises:
identifying the first available slot before the second available slot based at least in part on the first available slot offset being different than the second available slot offset, a first index of the first sounding reference signal resource set, a second index of the second sounding reference signal resource set, the first set of sounding reference signals via the first sounding reference signal resource set being scheduled for transmission on partial frequency resources, a first configuration of the first sounding reference signal resource set, a second configuration of the second sounding reference signal resource set, or any combination thereof, wherein the first configuration and the second configuration each comprise a number of sounding reference signal resources, a transmit power, a frequency hopping configuration, a number of repetitions, or any combination thereof.
11. The method of claim 9 , wherein identifying the first available slot before the second available slot comprises:
identifying the first available slot before the second available slot based at least in part on a first usage of the first sounding reference signal resource set and a second usage of the second sounding reference signal resource set.
12. The method of claim 4 , wherein the first available slot indicated for the first sounding reference signal resource set and the second available slot indicated for the second sounding reference signal resource set are a same slot.
13. The method of claim 12 , wherein transmitting the first set of sounding reference signals via the first sounding reference signal resource set, the second set of sounding reference signals via the second sounding reference signal resource set, or both comprises:
transmitting the first set of sounding reference signals via the first sounding reference signal resource set on a first subset of symbols in the same slot; and
transmitting the second set of sounding reference signals via the second sounding reference signal resource set on a second subset of symbols in the same slot.
14. The method of claim 12 , wherein transmitting the first sounding reference signal resource set, the second sounding reference signal resource set, or both comprises:
transmitting either the first set of sounding reference signals via the first sounding reference signal resource set or the second set of sounding reference signals via the second sounding reference signal resource set.
15. The method of claim 14 , further comprising:
determining whether to transmit the first set of sounding reference signals via the first sounding reference signal resource set or the second set of sounding reference signals via the second sounding reference signal resource set based at least in part on a first usage, index, or configuration of the first sounding reference signal resource set and a second usage, index, or configuration of the second sounding reference signal resource set.
16. An apparatus for wireless communication at a user equipment (UE), comprising:
one or more processors;
memory coupled with the one or more processors; and
instructions stored in the memory and executable by the one or more processors to cause the apparatus to:
receive, at a first time, a first downlink control information message from a first transmission and reception point, the first downlink control information message triggering transmission of a first set of sounding reference signals via a first sounding reference signal resource set;
receive, at a second time, a second downlink control information message from a second transmission and reception point, the second downlink control information message triggering transmission of a second set of sounding reference signals via a second sounding reference signal resource set, wherein the first time occurs before the second time;
identify a same reference slot for the first sounding reference signal resource set and the second sounding reference signal resource set;
identify a timestamp as a last symbol of a control channel that includes the second downlink control information message or a last symbol of a search space associated with the control channel that includes the second downlink control information message;
identify each of a first available slot for the first sounding reference signal resource set and a second available slot for the second sounding reference signal resource set based at least in part on a processing time after the timestamp, wherein the first available slot is offset from the same reference slot by a first available slot offset and the second available slot is offset from the same reference slot by a second available slot offset; and
transmit the first set of sounding reference signals via the first sounding reference signal resource set in the first available slot and the second set of sounding reference signals via the second sounding reference signal resource set in the second available slot.
17. The apparatus of claim 16 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
determine the same reference slot to be a slot in which the second downlink control information message is received.
18. The apparatus of claim 16 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive an indication of an offset in the second downlink control information message; and
determine the same reference slot based at least in part on the offset and a slot in which the second downlink control information message is received.
19. An apparatus for wireless communication at a user equipment (UE), comprising:
one or more processors;
memory coupled with the one or more processors; and
instructions stored in the memory and executable by the one or more processors to cause the apparatus to:
receive a configuration message indicating a first list of multiple offsets for a first sounding reference signal resource set and a second list of multiple offsets for a second sounding reference signal resource set;
receive a single downlink control information message triggering transmission of a first set of sounding reference signals via the first sounding reference signal resource set and a second set of sounding reference signals via the second sounding reference signal resource set and indicating a first available slot offset from the first list of multiple offsets corresponding to a first available slot for the first sounding reference signal resource set and a second available slot offset from the second list of multiple offsets corresponding to a second available slot for the second sounding reference signal resource set; and
transmit transmitting the first set of sounding reference signals via the first sounding reference signal resource set in the first available slot, the second set of sounding reference signals via the second sounding reference signal resource set in the second available slot, or both.
20. The apparatus of claim 19 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, in the single downlink control information message, a bit field indicating the first available slot offset and the second available slot offset.
21. The apparatus of claim 19 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, in the configuration message, first list of triggering codes for triggering transmission of the first set of sounding reference signals via the first sounding reference signal resource set, wherein each triggering code in the first list of triggering codes corresponds to an offset for the first sounding reference signal resource set; and
receive, in the single downlink control information message, a triggering code from the first list of triggering codes triggering transmission of the first set of sounding reference signals via the first sounding reference signal resource set and indicating the first available slot offset.
22. The apparatus of claim 19 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, in the single downlink control information message, a first bit field indicating the first available slot offset and a second bit field indicating the second available slot offset.
23. The apparatus of claim 22 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
determine that the first bit field indicates the first available slot offset and the second bit field indicates the second available slot offset based at least in part on an order of the first bit field and the second bit field in the single downlink control information message.
24. The apparatus of claim 19 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
identify the first available slot for the first sounding reference signal resource set before the second available slot for the second sounding reference signal resource set; and
identify the second available slot for the second sounding reference signal resource set based at least in part on the first available slot being unavailable for the second sounding reference signal resource set.
25. The apparatus of claim 24 , wherein the instructions to identify the first available slot before the second available slot are executable by the one or more processors to cause the apparatus to:
identify the first available slot before the second available slot based at least in part on the first available slot offset being different than the second available slot offset, a first index of the first sounding reference signal resource set, a second index of the second sounding reference signal resource set, the first set of sounding reference signals via the first sounding reference signal resource set being scheduled for transmission on partial frequency resources, a first configuration of the first sounding reference signal resource set, a second configuration of the second sounding reference signal resource set, or any combination thereof, wherein the first configuration and the second configuration each comprise a number of sounding reference signal resources, a transmit power, a frequency hopping configuration, a number of repetitions, or any combination thereof.
26. The apparatus of claim 24 , wherein the instructions to identify the first available slot before the second available slot are executable by the one or more processors to cause the apparatus to:
identify the first available slot before the second available slot based at least in part on a first usage of the first sounding reference signal resource set and a second usage of the second sounding reference signal resource set.
27. The apparatus of claim 19 , wherein the first available slot indicated for the first sounding reference signal resource set and the second available slot indicated for the second sounding reference signal resource set are a same slot.
28. The apparatus of claim 27 , wherein the instructions to transmit the first set of sounding reference signals via the first sounding reference signal resource set, the second set of sounding reference signals via the second sounding reference signal resource set, or both are executable by the one or more processors to cause the apparatus to:
transmit the first set of sounding reference signals via the first sounding reference signal resource set on a first subset of symbols in the same slot; and
transmit the second set of sounding reference signals via the second sounding reference signal resource set on a second subset of symbols in the same slot.
29. The apparatus of claim 19 , wherein the instructions to transmit the first sounding reference signal resource set, the second sounding reference signal resource set, or both are executable by the one or more processors to cause the apparatus to:
transmit either the first set of sounding reference signals via the first sounding reference signal resource set or the second set of sounding reference signals via the second sounding reference signal resource set.
30. The apparatus of claim 29 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
determine whether to transmit the first set of sounding reference signals via the first sounding reference signal resource set or the second set of sounding reference signals via the second sounding reference signal resource set based at least in part on a first usage, index, or configuration of the first sounding reference signal resource set and a second usage, index, or configuration of the second sounding reference signal resource set.