US 12,262,422 B2
HARQ procedure for RACH response message in two-step RACH
Jing Lei, San Diego, CA (US); Yi Huang, San Diego, CA (US); Wanshi Chen, San Diego, CA (US); Linhai He, San Diego, CA (US); Ruiming Zheng, Beijing (CN); Peter Gaal, San Diego, CA (US); and Joseph Binamira Soriaga, San Diego, CA (US)
Assigned to QUALCOMM Incorporated, San Diego, CA (US)
Appl. No. 17/635,453
Filed by QUALCOMM Incorporated, San Diego, CA (US)
PCT Filed Aug. 13, 2020, PCT No. PCT/CN2020/108803
§ 371(c)(1), (2) Date Feb. 15, 2022,
PCT Pub. No. WO2021/031966, PCT Pub. Date Feb. 25, 2021.
Claims priority of application No. PCT/CN2019/101168 (WO), filed on Aug. 16, 2019.
Prior Publication US 2022/0272769 A1, Aug. 25, 2022
Int. Cl. H04W 74/0833 (2024.01); H04L 1/1812 (2023.01); H04L 5/00 (2006.01); H04W 72/1263 (2023.01); H04W 72/23 (2023.01); H04W 74/08 (2009.01)
CPC H04W 74/0841 (2013.01) [H04L 1/1812 (2013.01); H04L 5/0053 (2013.01); H04W 72/1263 (2013.01); H04W 72/23 (2023.01); H04W 74/0866 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A method for wireless communications by a user equipment (UE), the method comprising:
sending a random access channel (RACH) message during a two-step RACH procedure, the RACH message including a RACH preamble and a RACH payload;
monitoring for a RACH response message during a random access response (RAR) window;
receiving a physical downlink control channel (PDCCH) of the RACH response message, wherein the PDCCH of the RACH response message includes a field indicating whether hybrid automatic repeat request (HARQ) feedback is requested for a physical downlink shared channel (PDSCH) of the RACH response message; and one of:
if the UE successfully decodes the PDSCH of the RACH response message during the RAR window:
transmitting an acknowledgement (ACK) to the RACH response message if the PDSCH of the RACH response message is carrying a success RAR during the RAR window and the field in the PDCCH of the RACH response message indicates that HARQ feedback is requested for the PDSCH of the RACH response message; or
transmitting a retransmission of the RACH payload of the RACH message on a physical uplink shared channel (PUSCH) if the PDSCH of the RACH response message is carrying a fallback RAR; and
if the UE does not successfully decode the PDSCH of the RACH response message during the RAR window:
transmitting a negative acknowledgment (NACK) to the RACH response message if the field in the PDCCH of the RACH response message indicates that HARQ feedback is requested for the PDSCH of the RACH response message; or
performing a discontinuous transmission (DTX) if the field in the PDCCH of the RACH response message indicates that HARQ feedback is not requested for the PDSCH of the RACH response message.