US 12,302,408 B2
UE, network node and methods for handling 2-step and 4-step random access procedures
Jan Christoffersson, Luleå (SE); and Min Wang, Luleå (SE)
Assigned to TELEFONAKTIEBOLAGET LM ERICSSON (PUBL), Stockholm (SE)
Appl. No. 17/430,099
Filed by Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
PCT Filed Dec. 3, 2019, PCT No. PCT/SE2019/051226
§ 371(c)(1), (2) Date Aug. 11, 2021,
PCT Pub. No. WO2020/167183, PCT Pub. Date Aug. 20, 2020.
Claims priority of provisional application 62/804,244, filed on Feb. 12, 2019.
Prior Publication US 2022/0150980 A1, May 12, 2022
Int. Cl. H04W 74/08 (2024.01); H04W 72/23 (2023.01); H04W 74/0833 (2024.01); H04W 80/02 (2009.01)
CPC H04W 74/0841 (2013.01) [H04W 72/23 (2023.01); H04W 74/0866 (2013.01); H04W 80/02 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method performed by a User Equipment, UE, for handling 2-step and 4-step Random Access, RA, procedures in a communications system, the method comprising:
transmitting a message A, msgA, comprising a preamble and a message 3, msg3, to a network node, wherein the UE applies a 2-step RA procedure when transmitting msgA;
detecting, after the msgA has been transmitted, that neither the maximum number of msgA transmissions is reached nor that an indicator is received, wherein the indicator indicates that the UE should fallback from the 2-step RA procedure to the 4-step RA procedure;
based on the detection, determining to retransmit msgA to the network node; and
based on a criterion, determining to fallback from the 2-step RA procedure to the 4-step RA procedure, wherein the criterion is that a maximum number of msgA transmissions has been exceeded or receipt of the indicator.