SRS transmitted with Msg4 ACK
Certain aspects of the present disclosure provide techniques for transmitting sounding reference signals (SRS) with (e.g., before or after) a random access channel (RACH) acknowledgement (ACK) (e.g., after Msg4). An example method by a user equipment (UE) includes receiving a first downlink RACH message, receiving a second downlink RACH message after the first downlink RACH message, receiving signaling that indicates the UE is to transmit SRS after the second downlink RACH message, and transmitting the SRS after the second downlink RACH message, in accordance with the indication.
1. A method for wireless communications performed by a user equipment (UE), comprising:
receiving a first downlink random access channel (RACH) message;
receiving a second downlink RACH message after the first downlink RACH message;
receiving signaling that indicates the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
transmitting the SRS after the second downlink RACH message, in accordance with the indication, wherein:
the SRS is transmitted on frequency resources indicated in a physical downlink control channel (PDCCH) for the second downlink RACH message; and
the frequency resources comprise at least one of an SRS bandwidth or a frequency allocation within an SRS bandwidth.
2. The method of claim 1 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the first downlink RACH message.
3. The method of claim 1 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the second downlink RACH message or the PDCCH for the second downlink RACH message.
4. The method of claim 1 , wherein the SRS is transmitted in accordance with one or more predefined configuration parameters.
5. The method of claim 1 , wherein the SRS is transmitted on a set of resources based on one or more rules.
6. A method for wireless communications performed by a user equipment (UE), comprising:
receiving a first downlink random access channel (RACH) message;
receiving a second downlink RACH message after the first downlink RACH message;
receiving signaling that indicates the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
transmitting the SRS after the second downlink RACH message, in accordance with the indication, wherein at least one of:
the SRS is transmitted in accordance with one or more configuration parameters that are indicated in a medium access control (MAC) control element (CE) conveyed by the second downlink RACH message;
the SRS is transmitted on a first set of resources based on a second set of resources used by the UE for transmitting an acknowledgment of the second downlink RACH message;
the SRS is transmitted on a set of resources based on one or more parameters indicated in a MAC-CE conveyed by the second downlink RACH message;
the SRS is transmitted on frequency resources that are indicated in a MAC-CE conveyed by the second downlink RACH message; or
the SRS is transmitted on frequency resources that are indicated in a bit field in a physical downlink control channel (PDCCH) for the second downlink RACH message.
7. A method for wireless communications performed by a network entity, comprising:
transmitting a first downlink random access channel (RACH) message to a user equipment (UE);
transmitting a second downlink RACH message to the UE after the first downlink RACH message;
signaling the UE an indication that the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
monitoring for SRS transmissions from the UE after the second downlink RACH message, in accordance with the indication, wherein:
the monitoring comprises monitoring on frequency resources indicated in a physical downlink control channel (PDCCH) for the second downlink RACH message; and
the frequency resources comprise at least one of an SRS bandwidth or a frequency allocation within an SRS bandwidth.
8. The method of claim 7 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the first downlink RACH message.
9. The method of claim 7 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is signaled in the second downlink RACH message or the PDCCH for the second downlink RACH message.
10. The method of claim 7 , wherein the network entity monitors for the SRS in accordance with one or more predefined configuration parameters.
11. The method of claim 7 , wherein the network entity monitors for the SRS on a set of resources based on one or more rules.
12. A method for wireless communications performed by a network entity, comprising:
transmitting a first downlink random access channel (RACH) message to a user equipment (UE);
transmitting a second downlink RACH message to the UE after the first downlink RACH message;
signaling the UE an indication that the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
monitoring for SRS transmissions from the UE after the second downlink RACH message, in accordance with the indication, wherein at least one of:
the network entity monitors for the SRS in accordance with one or more configuration parameters that are indicated in a medium access control (MAC) control element (CE) conveyed by the second downlink RACH message;
the network entity monitors for the SRS on a first set of resources based on a second set of resources used by the UE for transmitting an acknowledgment of the second downlink RACH message;
the network entity monitors for the SRS on a set of resources based on one or more parameters indicated in a MAC-CE conveyed by the second downlink RACH message;
the network entity monitors for the SRS on frequency resources indicated in a MAC-CE conveyed by the second downlink RACH message; or
the network entity monitors for the SRS on frequency resources indicated in a bit field in a physical downlink control channel (PDCCH) for the second RACH message.
13. A user equipment (UE) configured for wireless communication, comprising:
a memory comprising computer-executable instructions; and
a processor configured to execute the computer-executable instructions and cause the UE to:
receive a first downlink random access channel (RACH) message;
receive a second downlink RACH message after the first downlink RACH message;
receive signaling that indicates the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
transmit the SRS after the second downlink RACH message, in accordance with the indication, wherein:
the SRS is transmitted on frequency resources indicated in a physical downlink control channel (PDCCH) for the second downlink RACH message; and
the frequency resources comprise at least one of an SRS bandwidth or a frequency allocation within an SRS bandwidth.
14. The UE of claim 13 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the first downlink RACH message.
15. The UE of claim 13 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the second downlink RACH message or the PDCCH for the second downlink RACH message.
16. A network entity configured for wireless communication, comprising:
a memory comprising computer-executable instructions; and
a processor configured to execute the computer-executable instructions and cause the network entity to:
transmit a first downlink random access channel (RACH) message to a user equipment (UE);
transmit a second downlink RACH message to the UE after the first downlink RACH message;
signal the UE an indication that the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
monitor for SRS transmissions from the UE after the second downlink RACH message, in accordance with the indication, wherein:
the monitoring comprises monitoring on frequency resources indicated in a physical downlink control channel (PDCCH) for the second downlink RACH message; and
the frequency resources comprise at least one of an SRS bandwidth or a frequency allocation within an SRS bandwidth.
17. The network entity of claim 16 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is provided in the first downlink RACH message.
18. The network entity of claim 16 , wherein the indication the UE is to transmit SRS after the second downlink RACH message is signaled in the second downlink RACH message or the PDCCH for the second downlink RACH message.
19. A user equipment (UE) configured for wireless communication, comprising:
a memory comprising computer-executable instructions; and
a processor configured to execute the computer-executable instructions and cause the UE to:
receive a first downlink random access channel (RACH) message;
receive a second downlink RACH message after the first downlink RACH message;
receive signaling that indicates the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
transmit the SRS after the second downlink RACH message, in accordance with the indication, wherein at least one of:
the SRS is transmitted in accordance with one or more configuration parameters that are indicated in a medium access control (MAC) control element (CE) conveyed by the second downlink RACH message;
the SRS is transmitted on a first set of resources based on a second set of resources used by the UE for transmitting an acknowledgment of the second downlink RACH message;
the SRS is transmitted on a set of resources based on one or more parameters indicated in a MAC-CE conveyed by the second downlink RACH message;
the SRS is transmitted on frequency resources that are indicated in a MAC-CE conveyed by the second downlink RACH message; or
the SRS is transmitted on frequency resources that are indicated in a bit field in a physical downlink control channel (PDCCH) for the second downlink RACH message.
20. A network entity configured for wireless communication, comprising:
a memory comprising computer-executable instructions; and
a processor configured to execute the computer-executable instructions and cause the network entity to:
transmit a first downlink random access channel (RACH) message to a user equipment (UE);
transmit a second downlink RACH message to the UE after the first downlink RACH message;
signal the UE an indication that the UE is to transmit sounding reference signals (SRS) after the second downlink RACH message; and
monitor for SRS transmissions from the UE after the second downlink RACH message, in accordance with the indication, wherein at least one of:
the network entity monitors for the SRS in accordance with one or more configuration parameters that are indicated in a medium access control (MAC) control element (CE) conveyed by the second downlink RACH message;
the network entity monitors for the SRS on a first set of resources based on a second set of resources used by the UE for transmitting an acknowledgment of the second downlink RACH message;
the network entity monitors for the SRS on a set of resources based on one or more parameters indicated in a MAC-CE conveyed by the second downlink RACH message;
the network entity monitors for the SRS on frequency resources indicated in a MAC-CE conveyed by the second downlink RACH message; or
the network entity monitors for the SRS on frequency resources indicated in a bit field in a physical downlink control channel (PDCCH) for the second RACH message.