Bandwidth part configuration for reduced capability devices
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a message that indicates a first initial uplink bandwidth part for use by the UE in communications with a network entity, the message also indicating a plurality of random access occasions, at least one of the plurality of random access occasions being in frequency resources that are outside of the first initial uplink bandwidth part. The UE may select a random access occasion of the plurality of random access occasions for transmission of a random access preamble from the UE to the network entity. The UE may transmit, as part of a random access procedure, the random access preamble within the random access occasion.
1. An apparatus for wireless communications at a user equipment (UE), comprising:
at least one processor; and
memory coupled to the at least one processor, the memory storing instructions executable by the at least one processor to cause the UE to:
receive a message that indicates a first initial uplink bandwidth part for use by the UE in communications with a network entity, the message also indicating a plurality of random access occasions, at least one of the plurality of random access occasions being in frequency resources that are outside of the first initial uplink bandwidth part;
select a random access occasion of the plurality of random access occasions for transmission of a random access preamble from the UE to the network entity; and
transmit, as part of a random access procedure, the random access preamble within the random access occasion.
2. The apparatus of claim 1 , wherein the instructions to receive the message are further executable by the at least one processor to cause the UE to:
receive an indication of one or more additional initial uplink bandwidth parts for use by the UE in the communications with the network entity, each of the plurality of random access occasions being in a respective one of the first initial uplink bandwidth part or additional initial uplink bandwidth parts.
3. The apparatus of claim 2 , wherein the instructions are further executable by the at least one processor to cause the UE to:
communicate one or more additional random access messages that are associated with transmission of the random access preamble, the one or more additional random access messages being communicated in frequency resources that are within a same one of the first initial uplink bandwidth part or the one or more additional initial uplink bandwidth parts in which the random access preamble is transmitted.
4. The apparatus of claim 2 , wherein the instructions are further executable by the at least one processor to cause the UE to:
determine that transmission of the random access preamble failed, wherein the random access preamble was transmitted within a first attempted initial uplink bandwidth part selected from the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts;
increment a preamble power ramping parameter based at least in part on failure of the transmission of the random access preamble and on whether the first attempted initial uplink bandwidth part is to be reused for retransmission of the random access preamble; and
retransmit the random access preamble in accordance with the preamble power ramping parameter.
5. The apparatus of claim 2 , wherein the instructions are further executable by the at least one processor to cause the UE to:
determine that transmission of the random access preamble failed, wherein the random access preamble was transmitted within a first attempted initial uplink bandwidth part selected from the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts;
increment a preamble power ramping parameter based at least in part on failure of the transmission of the random access preamble, regardless of whether the first attempted initial uplink bandwidth part is to be reused for retransmission of the random access preamble; and
retransmit the random access preamble in accordance with the preamble power ramping parameter.
6. The apparatus of claim 2 , wherein the instructions are further executable by the at least one processor to cause the UE to:
determine that transmission of the random access preamble failed; and
retransmit the random access preamble via any of the first initial uplink bandwidth part or the one or more additional initial uplink bandwidth parts, wherein the retransmitting is in accordance with a maximum number of retransmissions parameter that applies to retransmissions across all of the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts, collectively.
7. The apparatus of claim 2 , wherein the instructions are further executable by the at least one processor to cause the UE to:
determine that transmission of the random access preamble failed, wherein the random access preamble was transmitted within a first attempted initial uplink bandwidth part selected from the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts; and
retransmit the random access preamble via the first attempted initial uplink bandwidth part, wherein the retransmitting is in accordance with a maximum number of retransmissions parameter that applies to retransmissions per initial uplink bandwidth part.
8. The apparatus of claim 2 , wherein the instructions to select the random access occasion are further executable by the at least one processor to cause the UE to:
monitor an initial downlink bandwidth part for paging occasions during the random access procedure;
identify, from the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts, a corresponding initial uplink bandwidth part that corresponds to the initial downlink bandwidth part; and
select the random access occasion that is within the corresponding initial uplink bandwidth part based at least in part on the corresponding initial uplink bandwidth part corresponding to the initial downlink bandwidth part.
9. The apparatus of claim 1 , wherein at most one of the plurality of the random access occasions is within the first initial uplink bandwidth part, a remainder of the plurality of the random access occasions being outside of the first initial uplink bandwidth part but still associated with the first initial uplink bandwidth part.
10. The apparatus of claim 9 , wherein the instructions are further executable by the at least one processor to cause the UE to:
receive information that is indicative of at least one of a random access occasion offset parameter or a random access occasion binary direction parameter, wherein the random access occasion binary direction parameter indicates a direction in which the random access occasion offset parameter is to be applied with respect to a baseline resource block; and
determine one or more of the frequency resources that are outside of the first initial uplink bandwidth part based at least in part on the information.
11. The apparatus of claim 10 , wherein the instructions to receive the information that is indicative of at least one of the random access occasion offset parameter or the random access occasion binary direction parameter are further executable by the at least one processor to cause the UE to:
receive indications of at least one of the random access occasion offset parameter or the random access occasion binary direction parameter on a per-random access occasion basis.
12. The apparatus of claim 10 , wherein the instructions to determine one or more of the frequency resources that are outside of the first initial uplink bandwidth part are further executable by the at least one processor to cause the UE to:
determine, based at least in part on the random access occasion offset parameter, the random access occasion binary direction parameter, the baseline resource block, and a first frequency resource associated with a first random access occasion of the plurality of random access occasions; and
determine additional frequency resources associated with other random access occasions of the plurality of random access occasions, the additional frequency resources determined in relation to the first frequency resource.
13. The apparatus of claim 1 , wherein the instructions are further executable by the at least one processor to cause the UE to:
communicate one or more additional random access messages that are associated with transmission of the random access preamble, the one or more additional random access messages being communicated in frequency resources that are within a selected initial uplink bandwidth part that corresponds to the random access occasion.
14. The apparatus of claim 13 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the UE to:
receive a random access response message separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap.
15. The apparatus of claim 13 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the UE to:
transmit a connection request message separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap.
16. The apparatus of claim 13 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the UE to:
transmit a random access request payload separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap, the random access procedure being a two-step random access procedure.
17. The apparatus of claim 1 , wherein the message is received through a system information block, a synchronization signal block, downlink control information, a medium access control control element, radio resource control signaling, a handover command, or any combination thereof.
18. An apparatus for wireless communications at a network entity, comprising:
at least one processor; and
memory coupled to the at least one processor, the memory storing instructions executable by the at least one processor to cause the network entity to:
transmit a message that indicates a first initial uplink bandwidth part for use by a user equipment (UE) in communications with the network entity, the message also indicating a plurality of random access occasions, at least one of the plurality of random access occasions being in frequency resources that are outside of the first initial uplink bandwidth part; and
receive, as part of a random access procedure, a random access preamble within a random access occasion selected from the plurality of random access occasions.
19. The apparatus of claim 18 , wherein the instructions to transmit the message are further executable by the at least one processor to cause the network entity to:
transmit an indication of one or more additional initial uplink bandwidth parts for use by the UE in the communications with the network entity, each of the plurality of random access occasions being in a respective one of the first initial uplink bandwidth part or one or more additional initial uplink bandwidth parts.
20. The apparatus of claim 19 , wherein the instructions are further executable by the at least one processor to cause the network entity to:
communicate one or more additional random access messages that are associated with transmission of the random access preamble, the one or more random access messages being communicated in frequency resources that are within a same one of the first initial uplink bandwidth part or the one or more additional initial uplink bandwidth parts in which the random access preamble is transmitted.
21. The apparatus of claim 19 , wherein the instructions are further executable by the at least one processor to cause the network entity to:
determine that transmission of the random access preamble failed; and
receive a retransmission of the random access preamble via any of the first initial uplink bandwidth part or the one or more additional initial uplink bandwidth parts, wherein the retransmission is in accordance with a maximum number of retransmissions parameter that applies to retransmissions across all of the first initial uplink bandwidth part and the one or more additional initial uplink bandwidth parts, collectively.
22. The apparatus of claim 18 , wherein at most one of the plurality of the random access occasions is within the first initial uplink bandwidth part, a remainder of the plurality of the random access occasions being outside of the first initial uplink bandwidth part but still associated with the first initial uplink bandwidth part.
23. The apparatus of claim 22 , wherein the instructions are further executable by the at least one processor to cause the network entity to:
transmit information that is indicative of at least one of a random access occasion offset parameter or a random access occasion binary direction parameter, wherein the random access occasion binary direction parameter indicates a direction in which the random access occasion offset parameter is to be applied with respect to a baseline resource block; and
determine one or more of the frequency resources that are outside of the first initial uplink bandwidth part based at least in part on the information.
24. The apparatus of claim 23 , wherein the instructions to transmit the information that is indicative of at least one of the random access occasion offset parameter or the random access occasion binary direction parameter are further executable by the at least one processor to cause the network entity to:
transmit indications of at least one of the random access occasion offset parameter or the random access occasion binary direction parameter on a per-random access occasion basis.
25. The apparatus of claim 18 , wherein the instructions are further executable by the at least one processor to cause the network entity to:
communicate one or more additional random access messages that are associated with transmission of the random access preamble, the one or more additional random access messages being communicated in frequency resources that are within a selected initial uplink bandwidth part that corresponds to the random access occasion.
26. The apparatus of claim 25 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the network entity to:
transmit a random access response message separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap.
27. The apparatus of claim 25 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the network entity to:
receive a connection request message separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap.
28. The apparatus of claim 25 , wherein the instructions to communicate the one or more additional random access messages are further executable by the at least one processor to cause the network entity to:
receive a random access request payload separated in time from transmission of the random access preamble by a duration of time that includes a bandwidth part switching time gap, the random access procedure being a two-step random access procedure.
29. A method for wireless communications at a user equipment (UE), comprising:
receiving a message that indicates a first initial uplink bandwidth part for use by the UE in communications with a network entity, the message also indicating a plurality of random access occasions, at least one of the plurality of random access occasions being in frequency resources that are outside of the first initial uplink bandwidth part;
selecting a random access occasion of the plurality of random access occasions for transmission of a random access preamble from the UE to the network entity; and
transmitting, as part of a random access procedure, the random access preamble within the random access occasion.
30. A method for wireless communications at a network entity, comprising:
transmitting a message that indicates a first initial uplink bandwidth part for use by a user equipment (UE) in communications with the network entity, the message also indicating a plurality of random access occasions, at least one of the plurality of random access occasions being in frequency resources that are outside of the first initial uplink bandwidth part; and
receiving, as part of a random access procedure, a random access preamble within a random access occasion selected from the plurality of random access occasions.