Control elements to configure and trigger sounding reference signals
Methods, systems, and devices providing for media access control (MAC) control element (CE) configuration and triggering of sounding reference signal (SRS) are described. For example, a MAC packet data unit (PDU) may include MAC CEs and may indicate (e.g., via one or more bits in fields included in the MAC PDU, such as a MAC subheader) that one or more MAC CEs include one or more SRS configuration parameters. Such SRS configuration parameters may be used by a wireless device to determine an SRS configuration, or to update or reconfigure SRS configuration parameters of an existing or previously defined SRS configuration. In some cases, downlink control information (DCI) may be coupled to a MAC CE, such that the coupled DCI may provide additional SRS configuration parameters to be used in conjunction with SRS parameters indicated by the MAC CE. In such cases, the MAC PDU may indicate a coupling configuration.
1. A method for wireless communication at a user equipment (UE), comprising:
identifying a configuration to use to receive media access control (MAC) control elements (CEs) that include a set of sounding reference signal (SRS) configuration parameters, wherein the set of SRS configuration parameters indicate one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control related parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, or a time offset, or a combination thereof;
receiving, according to the identified configuration, a MAC CE that includes at least one SRS configuration parameter of the set of SRS configuration parameters; and
transmitting an SRS based at least in part on the SRS configuration parameter.
2. The method of claim 1 , further comprising:
receiving a MAC packet data unit (PDU) that comprises the MAC CE and an indication of a presence of the MAC CE in the MAC PDU.
3. The method of claim 1 , further comprising:
identifying a downlink control information (DCI) coupling configuration that indicates a DCI coupled to the MAC CE; and
receiving the indicated DCI coupled to the MAC CE, the DCI comprising at least one additional SRS configuration parameter for SRS transmissions.
4. The method of claim 3 , wherein the DCI coupling configuration indicates the DCI last received before the MAC CE, or the DCI next received after the MAC CE, or a time window to receive the DCI.
5. The method of claim 3 , wherein receiving the MAC CE comprises:
receiving a MAC packet data unit (PDU) that comprises a header and the MAC CE, the header indicating the DCI coupling configuration.
6. The method of claim 3 , wherein the received MAC CE indicates the DCI coupling configuration.
7. The method of claim 3 , wherein transmitting the SRS comprises:
transmitting the SRS based at least in part on the SRS configuration parameter and the at least one additional SRS configuration parameter.
8. The method of claim 3 , wherein the time offset indicates a delay for updating an SRS configuration from a time of reception of the DCI coupled to the MAC CE, or from a time of reception of the MAC CE, or a combination thereof.
9. The method of claim 3 , wherein the at least one additional SRS configuration parameter indicates one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, a time offset for updating an SRS configuration from a time a DCI coupled to the MAC CE is received, or a time offset for updating an SRS configuration for SRS transmission from a time the MAC CE is received, or a combination thereof.
10. The method of claim 1 , further comprising:
updating an SRS configuration based at least in part on the SRS configuration parameter indicated by the MAC CE; and
transmitting the SRS based at least in part on the updated SRS configuration.
11. The method of claim 1 , further comprising:
receiving the configuration to use to receive MAC CEs in downlink control information (DCI), or radio resource control (RRC) signaling, a different MAC CE, or a non-access stratum (NAS) message, or a combination thereof.
12. The method of claim 1 , further comprising:
transmitting a UE capability indication; and
receiving the configuration to use to receive MAC CEs based at least in part on the transmitted UE capability indication.
13. The method of claim 1 , further comprising:
receiving radio resource control (RRC) signaling that comprises at least one additional SRS configuration parameter.
14. The method of claim 13 , wherein the at least one additional SRS configuration parameter comprises a set of SRS configuration parameters and a corresponding SRS resource identifier, and the SRS configuration parameter of the MAC CE comprises an indication of the SRS resource identifier.
15. A method for wireless communication at a base station, comprising:
transmitting a configuration for a user equipment (UE) to use to receive media access control (MAC) control elements (CEs) that include a set of sounding reference signal (SRS) configuration parameters, wherein the set of SRS configuration parameters indicate one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control related parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, or a time offset, or a combination thereof;
transmitting, to the UE according to the transmitted configuration, a MAC CE that includes at least one SRS configuration parameter of the set of SRS configuration parameters; and
receiving an SRS transmitted by the UE according to the SRS configuration parameter.
16. The method of claim 15 , further comprising:
transmitting a MAC packet data unit (PDU) that comprises the MAC CE and an indication of a presence of the MAC CE in the MAC PDU.
17. The method of claim 15 , further comprising:
identifying a downlink control information (DCI) coupling configuration that indicates a DCI coupled to the MAC CE; and
transmitting the indicated DCI coupled to the MAC CE, the DCI comprising at least one additional SRS configuration parameter for SRS transmissions by the UE.
18. The method of claim 17 , wherein the DCI coupling configuration indicates the DCI last transmitted before the MAC CE, or the DCI next transmitted after the MAC CE, or a time window the DCI was transmitted in, or a time window the DCI will be transmitted in.
19. The method of claim 17 , wherein transmitting the MAC CE comprises:
transmitting a MAC packet data unit (PDU) that comprises a header and the MAC CE, the header indicating the DCI coupling configuration.
20. The method of claim 17 , wherein the transmitted MAC CE indicates the DCI coupling configuration.
21. The method of claim 17 , wherein receiving the SRS comprises:
receiving the SRS transmitted by the UE according to the SRS configuration parameter and the at least one additional SRS configuration parameter.
22. The method of claim 17 , wherein the time offset indicates a delay for updating an SRS configuration from a time of reception of the DCI coupled to the MAC CE.
23. The method of claim 17 , wherein the at least one additional SRS configuration parameter indicates one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, or a time offset for updating an SRS configuration from a time a DCI coupled to the MAC CE is received, or a time offset for updating an SRS configuration for SRS transmission from a time the MAC CE is received, or a combination thereof.
24. The method of claim 23 , wherein the time offset indicates a delay for updating the SRS configuration from a time of reception of the MAC CE.
25. The method of claim 15 , wherein the configuration for the UE to use to receive MAC CEs is transmitted in downlink control information (DCI), or radio resource control (RRC) signaling, a different MAC CE, or a non-access stratum (NAS) message, or a combination thereof.
26. The method of claim 15 , further comprising:
receiving a UE capability indication; and
transmitting the configuration for the UE to use to receive MAC CEs based at least in part on the received UE capability indication.
27. The method of claim 15 , further comprising:
transmitting radio resource control (RRC) signaling that comprises at least one additional SRS configuration parameter.
28. The method of claim 27 , wherein the at least one additional SRS configuration parameter comprises a set of SRS configuration parameters and a corresponding SRS resource identifier, and the SRS configuration parameter of the MAC CE comprises an indication of the SRS resource identifier.
29. An apparatus for wireless communication at a user equipment (UE), comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
identify a configuration to use to receive media access control (MAC) control elements (CEs) that include a set of sounding reference signal (SRS) configuration parameters, wherein the set of SRS configuration parameters indicate one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control related parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, or a time offset, or a combination thereof;
receive, according to the identified configuration, a MAC CE that includes at least one SRS configuration parameter of the set of SRS configuration parameters; and
transmit an SRS based at least in part on the SRS configuration parameter.
30. An apparatus for wireless communication at a base station, comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
transmit a configuration for a user equipment (UE) to use to receive media access control (MAC) control elements (CEs) that include a set of sounding reference signal (SRS) configuration parameters, wherein the set of SRS configuration parameters indicate one or more resource blocks (RBs), or one or more symbols, or a periodicity, or a cyclic shift, or a hopping configuration, or a sequence configuration, or a sequence hopping configuration, or one or more power control related parameters, or a repetition configuration, or an SRS density, or a resource element (RE) offset, or a time offset, or a combination thereof;
transmit, to the UE according to the transmitted configuration, a MAC CE that includes at least one SRS configuration parameter of the set of SRS configuration parameters; and
receive an SRS transmitted by the UE according to the SRS configuration parameter.