Physical random access channel enhancements in new radio
A UE may transmit a message comprising information regarding one or more physical random access channel (PRACH) capabilities of the UE to a base station (BS). The UE may then receive, from the BS, signaling comprising an indication of one or more configured PRACH formats supporting the one or more PRACH capabilities. Next, the UE may transmit, using the one or more configured PRACH formats, one or more preambles to the BS in a random access (RACH) procedure. Accordingly, the UE may receive a random access response (RAR) from the base station and further, in response to receiving the RAR, establish a connection with the BS.
1. A method, comprising:
transmitting, to a base station (BS), a message comprising information regarding one or more physical random access channel (PRACH) repetition capabilities of a user equipment (UE);
receiving, from the BS, signaling comprising PRACH configuration information configuring one or more reference signal received power (RSRP) thresholds;
selecting, based at least in part on the one or more RSRP thresholds, one or more PRACH resources for one or more PRACH repetitions;
transmitting, using the one or more PRACH resources and as part of the one or more PRACH repetitions, one or more preambles to the BS in a random access (RACH) procedure;
receiving, from the BS, a random access response (RAR); and
establishing, in response to receiving the RAR, a connection with the BS.
2. The method of claim 1 , wherein the information is further regarding one or more other PRACH capabilities comprising at least one of:
PRACH frequency hopping; or
PRACH beam sweeping.
3. The method of claim 1 , further comprising:
configuring the one or more preambles in a RACH occasion (RO) or a dedicated RO for PRACH repetition or PRACH beam sweeping.
4. The method of claim 1 , wherein there is a one to multiple or multiple to one mapping between synchronization signal blocks (SSBs) and RACH occasions (ROs).
5. The method of claim 1 , wherein the one or more preambles are transmitted at a maximum power level or at increasing power levels.
6. The method of claim 1 , wherein a starting subframe periodicity of the one or more preambles is greater than or equal to a number of the one or more preambles.
7. The method of claim 1 , wherein a frequency hopping offset corresponding to at least one of a configured frequency region and configured bandwidth part (BWP) is indicated in the one or more preambles.
8. The method of claim 1 , further comprising:
determining a RAR window using one or more random access-radio network temporary identifiers (RA-RNTIs).
9. The method of claim 1 , further comprising:
determining a number of beams to be swept based on one or more synchronization signal block (SSB) RSRP measurements.
10. The method of claim 1 , wherein there is a multiple to one mapping between synchronization signal blocks (SSBs) and RACH occasions (ROs), and wherein one or more beams are swept in an associated period or an associated pattern period.
11. The method of claim 1 , wherein a first message (MsgA) comprises the one or more preambles and one or more physical uplink shared channel (PUSCH) transmissions which are configured separately for the one or more PRACH repetition capabilities.
12. A method, comprising:
receiving, from a user equipment (UE), a message comprising information regarding one or more physical random access channel (PRACH) repetition capabilities of the UE;
transmitting, to the UE, signaling comprising PRACH configuration information configuring one or more reference signal received power (RSRP) thresholds;
receiving, from the UE, one or more preambles in a random access (RACH) procedure, wherein the one or more preambles are transmitted by the UE using one or more PRACH resources and as part of one or more PRACH repetitions, and wherein the one or more PRACH resources for the one or more PRACH repetitions are selected by the UE based at least in part on the one or more RSRP thresholds;
transmitting, to the UE, a random access response (RAR); and
establishing a connection with the UE.
13. The method of claim 12 , wherein a frequency hopping time interval or pattern is configured based on at least one of:
a per-slot basis;
a per-subframe basis;
a per-radio frame basis; or
a per-half PRACH repetition basis.
14. The method of claim 12 , wherein the signaling comprises an indication of one or more configured PRACH formats comprising PRACH format B 4 .
15. The method of claim 12 , wherein a predefined number of PRACH repetitions is indicated by a system information block (SIB).
16. The method of claim 12 , wherein a first message (MsgA) comprises the one or more preambles and one or more physical uplink shared channel (PUSCH) transmissions, and wherein an offset between a first MsgA PUSCH of the one or more PUSCH transmissions and a last MsgA preamble of the one or more preambles is configured by a base station.
17. The method of claim 12 , wherein a first message (MsgA) comprises the one or more preambles and one or more physical uplink shared channel (PUSCH) transmissions, and wherein the first MsgA is transmitted as a whole channel structure.
18. An apparatus, comprising:
at least one processor configured to cause a user equipment (UE) to:
transmit, to a base station (BS), a message comprising information regarding one or more physical random access channel (PRACH) repetition capabilities of the UE;
receive, from the BS, signaling comprising PRACH configuration information configuring one or more reference signal received power (RSRP) thresholds;
select, based at least in part on the one or more RSRP thresholds, one or more PRACH resources for one or more PRACH repetitions;
transmit, using the one or more PRACH resources and as part of the one or more PRACH repetitions, one or more preambles to the BS in a random access (RACH) procedure;
receive, from the BS, a random access response (RAR); and
establish, in response to receiving the RAR, a connection with the BS.
19. The apparatus of claim 18 , further comprising a radio operably coupled to the at least one processor.
20. The apparatus of claim 18 , wherein the information is further regarding one or more other PRACH capabilities comprising at least one of:
PRACH frequency hopping; or
PRACH beam sweeping.