Variable payload size for two-step random access
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive configuration information for a two-step random access channel (RACH) procedure, wherein the configuration information identifies a plurality of physical uplink shared channel (PUSCH) configurations for a PUSCH of the two-step RACH procedure; and transmit the PUSCH in accordance with a PUSCH configuration, of the plurality of PUSCH configurations, wherein the PUSCH configuration is selected based at least in part on a size of a payload of the PUSCH, and wherein a preamble of the PUSCH is used to indicate the selected PUSCH configuration. Numerous other aspects are provided.
1. A method of wireless communication performed by a user equipment (UE), comprising:
receiving configuration information for a two-step random access channel (RACH) procedure,
wherein the configuration information identifies a plurality of physical uplink shared channel (PUSCH) configurations for a PUSCH of the two-step RACH procedure; and
transmitting the PUSCH in accordance with a PUSCH configuration, of the plurality of PUSCH configurations, wherein the PUSCH configuration is selected based at least in part on a payload size of an uplink RACH message, and wherein a preamble of the PUSCH is used to indicate the selected PUSCH configuration.
2. The method of claim 1 , wherein the preamble of the PUSCH indicates the payload size of the uplink RACH message.
3. The method of claim 1 , wherein transmitting the PUSCH in accordance with the PUSCH configuration comprises:
transmitting the PUSCH using a particular RACH occasion for the preamble of the PUSCH, wherein the particular RACH occasion indicates the payload size of the uplink RACH message or a PUSCH configuration of a payload of the uplink RACH message.
4. The method of claim 1 , wherein the preamble is associated with a first preamble group of a RACH occasion, and wherein a second preamble group of the RACH occasion is configured to indicate a different payload size of the uplink RACH message or a different PUSCH configuration than the first preamble group of the RACH occasion.
5. The method of claim 1 , wherein the preamble of the PUSCH indicates a set of blind decoding hypotheses for a payload of the uplink RACH message.
6. The method of claim 5 , wherein multiple blind decoding hypotheses are mapped to respective resource allocations in connection with the preamble.
7. The method of claim 6 , wherein at least two resource allocations, of the respective resource allocations, have different sizes.
8. The method of claim 5 , wherein multiple blind decoding hypotheses are mapped to a same resource allocation in connection with the preamble.
9. A method of wireless communication performed by a base station, comprising:
transmitting configuration information for a two-step random access channel (RACH) procedure for a user equipment (UE),
wherein the configuration information identifies a plurality of physical uplink shared channel (PUSCH) configurations for an uplink RACH message of the two-step RACH procedure;
receiving the PUSCH in accordance with a PUSCH configuration, of the plurality of PUSCH configurations, wherein the PUSCH comprises a preamble that indicates the PUSCH configuration of the plurality of PUSCH configurations used for communicating the PUSCH; and
determining the PUSCH configuration based at least in part on the preamble and a payload size of the uplink RACH message.
10. The method of claim 9 , wherein the preamble of the PUSCH indicates the payload size of the uplink RACH message.
11. The method of claim 9 , wherein receiving the PUSCH in accordance with the PUSCH configuration comprises:
receiving the PUSCH in a particular RACH occasion, wherein the particular RACH occasion indicates the payload size of the uplink RACH message or the PUSCH configuration of a payload of the uplink RACH message.
12. The method of claim 9 , wherein the preamble is associated with a first preamble group of a RACH occasion, and wherein a second preamble group of the RACH occasion is configured to indicate a different payload size of the uplink RACH message or PUSCH configuration of a payload of the uplink RACH message than the first preamble group of the RACH occasion.
13. The method of claim 9 , wherein the preamble of the PUSCH indicates a set of blind decoding hypotheses for receiving a payload of the uplink RACH message.
14. The method of claim 13 , wherein multiple blind decoding hypotheses are mapped to respective resource allocations in connection with the preamble.
15. The method of claim 14 , wherein at least two resource allocations, of the respective resource allocations, have different sizes.
16. The method of claim 13 , wherein multiple blind decoding hypotheses are mapped to a same resource allocation in connection with the preamble.
17. The method of claim 13 , further comprising:
performing blind decoding in accordance with the set of blind decoding hypotheses to receive a payload of the uplink RACH message.
18. A user equipment (UE) for wireless communication, comprising:
a memory; and
one or more processors coupled to the memory, the memory and the one or more processors configured to:
receive configuration information for a two-step random access channel (RACH) procedure,
wherein the configuration information identifies a plurality of physical uplink shared channel (PUSCH) configurations for a PUSCH of the two-step RACH procedure; and
transmit the PUSCH in accordance with a PUSCH configuration, of the plurality of PUSCH configurations, wherein the PUSCH configuration is selected based at least in part on a payload size of an uplink RACH message, and wherein a preamble of the PUSCH is used to indicate the selected PUSCH configuration.
19. The UE of claim 18 , wherein the preamble of the PUSCH indicates the payload size of the uplink RACH message.
20. The UE of claim 18 , wherein the one or more processors, when transmitting the PUSCH in accordance with the PUSCH configuration, are further configured to:
transmit the PUSCH using a particular RACH occasion for the preamble of the PUSCH, wherein the particular RACH occasion indicates the payload size of the uplink RACH message or a PUSCH configuration of a payload of the uplink RACH message.
21. The UE of claim 18 , wherein the preamble is associated with a first preamble group of a RACH occasion, and wherein a second preamble group of the RACH occasion is configured to indicate a different payload size of the uplink RACH message or a different PUSCH configuration than the first preamble group of the RACH occasion.
22. The UE of claim 18 , wherein the preamble of the PUSCH indicates a set of blind decoding hypotheses for a payload of the uplink RACH message.
23. The UE of claim 22 , wherein multiple blind decoding hypotheses are mapped to respective resource allocations in connection with the preamble.
24. The UE of claim 23 , wherein at least two resource allocations, of the respective resource allocations, have different sizes.
25. The UE of claim 22 , wherein multiple blind decoding hypotheses are mapped to a same resource allocation in connection with the preamble.
26. A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:
one or more instructions that, when executed by one or more processors of a base station, cause the one or more processors to:
transmit configuration information for a two-step random access channel (RACH) procedure for a user equipment (UE),
wherein the configuration information identifies a plurality of physical uplink shared channel (PUSCH) configurations for an uplink RACH message of the two-step RACH procedure;
receive the PUSCH in accordance with a PUSCH configuration, of the plurality of PUSCH configurations, wherein the PUSCH comprises a preamble that indicates the PUSCH configuration of the plurality of PUSCH configurations used for communicating the PUSCH; and
determine the PUSCH configuration based at least in part on the preamble and a payload size of the uplink RACH message.
27. The non-transitory computer-readable medium of claim 26 , wherein the preamble of the PUSCH indicates the payload size of the uplink RACH message.
28. The non-transitory computer-readable medium of claim 26 , wherein the one or more processors, when receiving the PUSCH in accordance with the PUSCH configuration, are configured to:
receive the PUSCH in a particular RACH occasion, wherein the particular RACH occasion indicates the payload size of the uplink RACH message or the PUSCH configuration of a payload of the RACH message.
29. The non-transitory computer-readable medium of claim 26 , wherein the preamble is associated with a first preamble group of a RACH occasion, and wherein a second preamble group of the RACH occasion is configured to indicate a different payload size of the uplink RACH message or PUSCH configuration of a payload of the uplink RACH message than the first preamble group of the RACH occasion.
30. The non-transitory computer-readable medium of claim 26 , wherein the preamble of the PUSCH indicates a set of blind decoding hypotheses for receiving a payload of the uplink RACH message.