Random access procedures for non-terrestrial networks

1. A method for wireless communication at a user equipment (UE), comprising:

transmitting, to a network entity, a random access request message associated with a random access procedure using a set of transport block sizes and a power control, the random access request message including a random access payload that comprises a buffer status report or uplink data, or both, wherein a first subset of transport block sizes of the set of transport block sizes is associated with a first size for a first portion of the random access payload and a second subset of transport block sizes of the set of transport block sizes is associated with a second size for a second portion of the random access payload;

monitoring a response window based at least in part on transmitting the random access request message; and

receiving, from the network entity, a response message during the response window.

2. The method of claim 1 , further comprising:

receiving, in a message, a configuration including an indication of the set of transport block sizes, the message comprising a radio resource control message, a medium access control-control element message, or a downlink control information message, wherein the transmitting of the random access request message comprises:

transmitting the random access payload on a physical uplink shared channel based at least in part on the set of transport block sizes.

3. The method of claim 1 , further comprising:

determining the set of transport block sizes based at least in part on a configuration, wherein the set of transport block sizes comprises:

the first subset of transport block sizes to use for the random access payload based at least in part on the first portion of the random access payload that comprises the buffer status report without the uplink data; and

the second subset of transport block sizes to use for the random access payload based at least in part on the second portion of the random access payload that comprises the uplink data without the buffer status report.

4. The method of claim 3 , further comprising:

selecting a transport block size from the set of transport block sizes based at least in part on the random access payload that comprises the buffer status report without the uplink data or the random access payload that comprises the buffer status report with the uplink data, wherein the transmitting of the random access request message comprises:

transmitting the random access payload on a physical uplink shared channel based at least in part on the selecting of the transport block size.

5. The method of claim 4 , wherein the selecting of the transport block size from the set of transport block sizes for the random access payload that comprises the buffer status report without the uplink data is based at least in part on the uplink data satisfying a transport block size threshold.

6. The method of claim 4 , wherein the selecting of the transport block size from the set of transport block sizes for the random access payload that comprises the buffer status report without the uplink data is based at least in part on a physical uplink shared channel resource configured for the random access procedure failing to satisfy a logical channel prioritization associated with a logical channel for the uplink data.

7. The method of claim 1 , wherein the first subset of transport block sizes is configured for a first physical uplink shared channel occasion associated with the random access procedure and the second subset of transport block sizes is configured for a second physical uplink shared channel occasion associated with the random access procedure, the first physical uplink shared channel occasion is different than the second physical uplink shared channel occasion.

8. The method of claim 1 , further comprising:

determining the set of transport block sizes for the random access payload that comprises the buffer status report based at least in part on a random access preamble included in the random access request message, wherein the transmitting of the random access request message comprises:

transmitting the random access payload on a physical uplink shared channel, based at least in part on the determining of the set of transport block sizes for the random access payload, during a first physical uplink shared channel occasion associated with the random access procedure or a second physical uplink shared channel occasion associated the random access procedure, or both.

9. The method of claim 1 , further comprising:

determining the set of transport block sizes for the random access payload that comprises the buffer status report based at least in part on a partitioning of a set of physical random access channel resources or a grouping of a set of random access preambles including a random access preamble of the random access request message associated with the random access procedure, wherein the transmitting of the random access request message comprises:

transmitting the random access payload on a physical uplink shared channel, based at least in part on the determining of the set of transport block sizes for the random access payload, during a first physical uplink shared channel occasion associated with the random access procedure or a second physical uplink shared channel occasion associated the random access procedure, or both.

10. The method of claim 1 , further comprising:

receiving, in a message, a configuration including an indication of a power ramping parameter,

wherein the transmitting of the random access request message associated with the random access procedure is based at least in part on the power ramping parameter.

11. The method of claim 10 , further comprising:

adjusting a transmit power level based at least in part on at least one of the power ramping parameter a reference signal configuration associated with a synchronization signal block, or a reference signal configuration associated with a channel state information reference signal, wherein the transmitting of the random access request message comprises:

transmitting a random access preamble of the random access request message on a physical random access channel or the random access payload on a physical uplink shared channel, or both, based at least in part on the adjusting of the transmit power level.

12. The method of claim 10 , further comprising:

adjusting a transmit power level based at least in part on the power ramping parameter, a reference signal configuration, or a serving cell configuration, or a combination thereof, wherein the reference signal configuration is different for a random access preamble of the random access request message and a previous random access preamble transmission, and the serving cell configuration is the same for the random access preamble and the previous random access preamble transmission, wherein the transmitting of the random access request message comprises:

transmitting the random access preamble on a physical random access channel or the random access payload on a physical uplink shared channel, or both, based at least in part on the adjusting of the transmit power level.

13. The method of claim 1 , further comprising:

receiving, from the network, a timing advance command; and

restarting a timing advance timer regardless of a status of the timing advance timer based at least in part on the receiving of the timing advance command.

14. The method of claim 13 , further comprising:

configuring the UE to determine the status of the timing advance timer after receiving the timing advance command, wherein restarting the timing advance timer is based at least in part on the configuring.

15. The method of claim 1 , wherein the power control is specified by a configuration for a power ramping parameter, a reference signal configuration, a serving cell configuration, or a combination thereof.

16. The method of claim 1 , further comprising:

transmitting feedback information associated with the response message,

wherein the response message is received on a physical downlink shared channel addressed to a cell-radio network temporary identifier, and the feedback information comprises a hybrid automatic repeat request acknowledgement or a hybrid automatic repeat request non-acknowledgement.

17. The method of claim 16 , further comprising:

adjusting a duration of the response window based at least in part on an offset value and the feedback information comprising the hybrid automatic repeat request non-acknowledgement;

monitoring the response window based at least in part on the adjusting of the duration of the response window; and

receiving a retransmission of the response message during the response window.

18. The method of claim 17 , further comprising:

receiving, in a message, a configuration including an indication of a value of a set of values for the duration of the response window, wherein each value of the set of values for the duration of the response window corresponds to a respective round-trip delay value associated with a communication link,

wherein the adjusting of the duration of the response window is based at least in part on the configuration.

19. The method of claim 16 , further comprising:

restarting the response window based at least in part on the feedback information comprising the hybrid automatic repeat request non-acknowledgement.

20. The method of claim 16 , further comprising:

enabling an offset timer to monitor for a retransmission of the response message based at least in part on the transmitting of the feedback information or the response window expiring, or both.

21. The method of claim 16 , further comprising:

determining that the random access procedure is successful based at least in part on the receiving of the response message; and

monitoring a physical downlink control channel addressed to the cell-radio network temporary identifier based at least in part on the determining that the random access procedure is successful.

22. A user equipment (UE), comprising:

a processor;

a transceiver;

memory coupled with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the UE to:

transmit, via the transceiver to a network entity, a random access request message associated with a random access procedure using a set of transport block sizes and a power control, the random access request message including a random access payload that comprises a buffer status report or uplink data, or both, wherein a first subset of transport block sizes of the set of transport block sizes is associated with a first size for a first portion of the random access payload and a second subset of transport block sizes of the set of transport block sizes is associated with a second size for a second portion of the random access payload;

monitor, via the processor, a response window based at least in part on transmitting the random access request message; and

receive, via the transceiver from the network entity, a response message during the response window.

23. The UE of claim 22 , wherein the instructions are further executable by the processor to cause the UE to:

receive, via the transceiver in a message, a configuration including an indication of the set of transport block sizes, the message comprising a radio resource control message, a medium access control-control element message, or a downlink control information message, wherein the instructions for transmitting of the random access request message are further executable by the processor to cause the UE to:

transmit, via the transceiver, the random access payload on a physical uplink shared channel based at least in part on the set of transport block sizes.

24. The UE of claim 22 , wherein the instructions are further executable by the processor to cause the UE apparatus to:

determine, via the processor, the set of transport block sizes based at least in part on a configuration, wherein the set of transport block sizes comprises:

the first subset of transport block sizes to use for the random access payload based at least in part on the first portion of the random access payload that comprises the buffer status report without the uplink data; and

the second subset of transport block sizes to use for the random access payload based at least in part on the second portion of the random access payload that comprises the uplink data without the buffer status report.

25. The UE of claim 24 , wherein the instructions are further executable by the processor to cause the UE to:

select, via the processor, a transport block size from the set of transport block sizes based at least in part on the random access payload that comprises the buffer status report without the uplink data or the random access payload that comprises the buffer status report with the uplink data, wherein the instructions for transmitting of the random access request message are further executable by the processor to cause the UE to:

transmit, via the transceiver, the random access payload on a physical uplink shared channel based at least in part on the selecting of the transport block size.

26. The UE of claim 25 , wherein the selecting of the transport block size from the set of transport block sizes for the random access payload that comprises the buffer status report without the uplink data is based at least in part on the uplink data satisfying a transport block size threshold.

27. The UE of claim 25 , wherein the selecting of the transport block size from the set of transport block sizes for the random access payload that comprises the buffer status report without the uplink data is based at least in part on a physical uplink shared channel resource configured for the random access procedure failing to satisfy a logical channel prioritization associated with a logical channel for the uplink data.

28. The UE of claim 22 , wherein the first subset of transport block sizes is configured for a first physical uplink shared channel occasion associated with the random access procedure and the second subset of transport block sizes is configured for a second physical uplink shared channel occasion associated with the random access procedure, the first physical uplink shared channel occasion is different than the second physical uplink shared channel occasion.

29. An apparatus for wireless communication at a user equipment (UE), comprising:

means for transmitting, to a network entity, a random access request message associated with a random access procedure using a set of transport block sizes and a power control, the random access request message including a random access payload that comprises a buffer status report or uplink data, or both, wherein a first subset of transport block sizes of the set of transport block sizes is associated with a first size for a first portion of the random access payload and a second subset of transport block sizes of the set of transport block sizes is associated with a second size for a second portion of the random access payload;

means for monitoring a response window based at least in part on transmitting the random access request message; and

means for receiving, from the network entity, a response message during the response window.

30. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to:

transmit, to a network entity, a random access request message associated with a random access procedure using a set of transport block sizes and a power control, the random access request message including and a random access payload that comprises a buffer status report or uplink data, or both, wherein a first subset of transport block sizes of the set of transport block sizes is associated with a first size for a first portion of the random access payload and a second subset of transport block sizes of the set of transport block sizes is associated with a second size for a second portion of the random access payload;

monitor a response window based at least in part on transmitting the random access request message; and

receive, from the network entity, a response message during the response window.