Techniques and apparatuses for configuring an uplink bandwidth part for a random access channel (RACH) procedure
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive remaining minimum system information (RMSI) from a base station (BS); determine an initial active uplink bandwidth part based at least in part on the RMSI; and use the initial active uplink bandwidth part for a random access channel (RACH) procedure between the UE and the BS. Numerous other aspects are provided.
1. A method of wireless communication performed by a user equipment (UE), comprising:
receiving remaining minimum system information (RMSI) from a base station (BS);
identifying a plurality of reference uplink frequency locations in a random access channel (RACH) configuration, of a RACH procedure, included within the RMSI;
selecting a reference uplink frequency location from the plurality of reference uplink frequency locations as a physical resource block (PRB) frequency location;
determining an initial active uplink bandwidth part based at least in part on the PRB frequency location; and
using the initial active uplink bandwidth part for the RACH procedure between the UE and the BS.
2. The method of claim 1 , wherein selecting the reference uplink frequency location from the plurality of reference uplink frequency locations comprises:
selecting the reference uplink frequency location based at least in part on a setting of the UE associated with the RACH procedure.
3. The method of claim 2 , wherein the setting comprises at least one of:
a mapping or hash function based at least in part on a parameter of the UE,
a synchronization signal block (SSB) index of a physical random access channel (PRACH) transmission of the RACH procedure, or
a slot index of the PRACH transmission of the RACH procedure.
4. The method of claim 1 , wherein the RMSI includes a numerology of the initial active uplink bandwidth part,
wherein the numerology comprises at least one of:
a subcarrier spacing for the RACH procedure,
a cyclic prefix for the RACH procedure, or
a number of symbols per slot for the RACH procedure.
5. The method of claim 4 , wherein the numerology is based at least in part on at least one of:
a numerology of a physical uplink shared channel (PUSCH) for a Message 3 (Msg.3) transmission of the RACH procedure, or
a numerology of a physical uplink control channel (PUCCH) for an acknowledgment (ACK) of a Message 4 (Msg.4) transmission of the RACH procedure.
6. The method of claim 1 , wherein the RMSI includes at least one of:
a bandwidth of the initial active uplink bandwidth part,
a reference frequency of the initial active uplink bandwidth part,
an offset from the reference frequency of the initial active uplink bandwidth part, or
a numerology of the initial active uplink bandwidth part.
7. The method of claim 1 , wherein the initial active uplink bandwidth part for the RACH procedure is used for at least one of:
a physical random access channel (PRACH) of the RACH procedure,
a physical uplink control channel (PUCCH) of the RACH procedure, or
a physical uplink shared channel (PUSCH) of the RACH procedure.
8. A user equipment comprising:
memory; and
one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:
receive remaining minimum system information (RMSI) from a base station (BS);
identify a plurality of reference uplink frequency locations in random access channel (RACH) configuration, of a RACH procedure, included within the RMSI;
select a reference uplink frequency location from the plurality of reference uplink frequency locations as a physical resource block (PRB) frequency location;
determine an initial active uplink bandwidth part based at least in part on the PRB frequency location of the initial active uplink bandwidth part; and
use the initial active uplink bandwidth part for the RACH procedure between the user equipment and the BS.
9. The user equipment of claim 8 , wherein the one or more processors, when selecting the reference uplink frequency location from the plurality of reference uplink frequency locations, are configured to:
select the reference uplink frequency location based at least in part on a setting of the user equipment associated with the RACH procedure.
10. The user equipment of claim 9 , wherein the setting comprises at least one of:
a mapping or hash function based at least in part on a parameter of the user equipment,
a synchronization signal block (SSB) index of a physical random access channel (PRACH) transmission of the RACH procedure, or
a slot index of the PRACH transmission of the RACH procedure.
11. The user equipment of claim 8 , wherein the RMSI includes a numerology of the initial active uplink bandwidth part,
wherein the numerology comprises at least one of:
a subcarrier spacing for the RACH procedure,
a cyclic prefix for the RACH procedure, or
a number of symbols per slot for the RACH procedure.
12. The user equipment of claim 11 , wherein the numerology is based at least in part on at least one of:
a numerology of a physical uplink shared channel (PUSCH) for a Message 3 (Msg.3) transmission of the RACH procedure, or
a numerology of a physical uplink control channel (PUCCH) for an acknowledgment (ACK) of a Message 4 (Msg.4) transmission of the RACH procedure.
13. The user equipment of claim 8 , wherein the RMSI includes at least one of:
a bandwidth of the initial active uplink bandwidth part,
a reference frequency of the initial active uplink bandwidth part,
an offset from the reference frequency of the initial active uplink bandwidth part, or
a numerology of the initial active uplink bandwidth part.
14. The user equipment of claim 8 , wherein the initial active uplink bandwidth part for the RACH procedure is used for at least one of:
a physical random access channel (PRACH) of the RACH procedure,
a physical uplink control channel (PUCCH) of the RACH procedure, or
a physical uplink shared channel (PUSCH) of the RACH procedure.
15. A method of wireless communication performed by a base station (BS), comprising:
transmitting, to a user equipment (UE), a random access channel (RACH) configuration within remaining minimum system information (RMSI),
the RACH configuration to be used to establish an initial active uplink bandwidth part for the UE,
the RACH configuration including information regarding a plurality of reference uplink frequency locations,
the initial active uplink bandwidth part being determined based at least in part on a reference uplink frequency location selected from the plurality of reference uplink frequency locations as a physical resource block (PRB) frequency location, and
the initial active uplink bandwidth part to be used for a RACH procedure between the BS and the UE; and
establishing an uplink PRB grid for the RACH procedure based at least in part on the initial active uplink bandwidth part.
16. The method of claim 15 , wherein the uplink PRB grid is established based at least in part on a numerology of the initial active uplink bandwidth part.
17. The method of claim 16 , wherein the numerology indicates at least one of:
a subcarrier spacing for the RACH procedure,
a cyclic prefix for the RACH procedure, or
a number of symbols per slot for the RACH procedure.
18. The method of claim 16 , wherein the numerology is based at least in part on at least one of:
a numerology of a physical uplink shared channel (PUSCH) for a Message 3 (Msg.3) transmission of the RACH procedure, or
a numerology of a physical uplink control channel (PUCCH) for an acknowledgment (ACK) of a Message 4 (Msg.4) transmission of the RACH procedure.
19. The method of claim 15 , wherein the reference uplink frequency location is selected based at least in part on a setting of the UE.
20. The method of claim 15 , wherein the setting comprises at least one of:
a mapping or hash function based at least in part on a parameter of the UE,
a synchronization signal block (SSB) index of a physical random access channel (PRACH) transmission of the RACH procedure, or
a slot index of the PRACH transmission of the RACH procedure.
21. The method of claim 15 , wherein the RMSI includes at least one of:
a bandwidth of the initial active uplink bandwidth part,
a reference frequency of the initial active uplink bandwidth part,
an offset from the reference frequency of the initial active uplink bandwidth part, or
a numerology of the initial active uplink bandwidth part.
22. The method of claim 15 , wherein the initial active uplink bandwidth part is to be used for a physical random access channel (PRACH) of the RACH procedure.
23. The method of claim 15 , wherein the initial active uplink bandwidth part is to be used for at least one of:
a physical uplink control channel (PUCCH) of the RACH procedure, or
a physical uplink shared channel (PUSCH) of the RACH procedure.
24. A base station (BS) comprising:
memory; and
one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:
transmit, to a user equipment (UE), a random access channel (RACH) configuration within remaining minimum system information (RMSI),
wherein the RACH configuration is to be used to establish an initial active uplink bandwidth part for the UE,
the RACH configuration including information regarding a plurality of reference uplink frequency locations,
the initial active uplink bandwidth part being determined based at least in part on a reference uplink frequency location selected from the plurality of reference uplink frequency locations as a physical resource block (PRB) frequency location, and
the initial active uplink bandwidth part to be used for a RACH procedure between the base station and the UE; and
establish an uplink PRB grid for the RACH procedure based at least in part on the initial active uplink bandwidth part.
25. The base station of claim 24 , wherein the uplink PRB grid is established based at least in part on a numerology of the initial active uplink bandwidth part,
wherein the numerology indicates at least one of:
a subcarrier spacing for the RACH procedure,
a cyclic prefix for the RACH procedure, or
a number of symbols per slot for the RACH procedure.
26. The base station of claim 25 , wherein the numerology is based at least in part on at least one of:
a numerology of a physical uplink shared channel (PUSCH) for a Message 3 (Msg.3) transmission of the RACH procedure, or
a numerology of a physical uplink control channel (PUCCH) for an acknowledgment (ACK) of a Message 4 (Msg.4) transmission of the RACH procedure.
27. The base station of claim 24 , wherein the reference uplink frequency location is selected based at least in part on a setting of the UE.
28. The base station of claim 27 , wherein the setting comprises at least one of:
a mapping or hash function based at least in part on a parameter of the UE,
a synchronization signal block (SSB) index of a physical random access channel (PRACH) transmission of the RACH procedure, or
a slot index of the PRACH transmission of the RACH procedure.
29. The base station of claim 24 , wherein the RMSI includes at least one of:
a bandwidth of the initial active uplink bandwidth part,
a reference frequency of the initial active uplink bandwidth part,
an offset from the reference frequency of the initial active uplink bandwidth part, or
a numerology of the initial active uplink bandwidth part.
30. The base station of claim 24 , wherein the initial active uplink bandwidth part is to be used for at least one of:
a physical random access channel (PRACH) of the RACH procedure,
a physical uplink control channel (PUCCH) of the RACH procedure, or
a physical uplink shared channel (PUSCH) of the RACH procedure.