US 12,218,985 B2
Method for moving IMS voice session on non-3GPP to 3GPP access
Myungjune Youn, Seoul (KR); Sehee Lee, Seoul (KR); Sungduck Chun, Seoul (KR); Hyunsook Kim, Seoul (KR); Laeyoung Kim, Seoul (KR); and Sangmin Park, Seoul (KR)
Assigned to LG ELECTRONICS INC., Seoul (KR)
Appl. No. 17/753,378
Filed by LG ELECTRONICS INC., Seoul (KR)
PCT Filed Sep. 8, 2020, PCT No. PCT/KR2020/012081
§ 371(c)(1), (2) Date Mar. 1, 2022,
PCT Pub. No. WO2021/049841, PCT Pub. Date Mar. 18, 2021.
Claims priority of application No. 10-2019-0111686 (KR), filed on Sep. 9, 2019; application No. 10-2019-0115632 (KR), filed on Sep. 19, 2019; application No. 10-2019-0127408 (KR), filed on Oct. 15, 2019; and application No. 10-2019-0138390 (KR), filed on Nov. 1, 2019.
Prior Publication US 2022/0345949 A1, Oct. 27, 2022
Int. Cl. H04W 36/00 (2009.01); H04L 65/1016 (2022.01); H04L 65/1069 (2022.01); H04W 36/32 (2009.01); H04W 36/14 (2009.01)
CPC H04L 65/1016 (2013.01) [H04L 65/1069 (2013.01); H04W 36/00226 (2023.05); H04W 36/322 (2023.05); H04W 36/00695 (2023.05); H04W 36/144 (2023.05)] 10 Claims
OG exemplary drawing
 
6. A Next Generation Radio Access Network (NG-RAN) device comprising:
a transceiver;
at least one processor; and
at least one memory for storing instructions and electrically connected to the at least one processor,
wherein the instructions cause the at least one processor to perform operations comprising:
receiving a NAS (Non-Access-Stratum) message including a Protocol Data Unit (PDU) session establishment request for establishment of a PDU session for an Internet protocol Multimedia Subsystem (IMS) voice service via a 3rd Generation Partnership Project (3GPP) access from a User Equipment (UE),
wherein the PDU session establishment request indicates an existing PDU session, based on a handover from a non-3GPP access to the 3GPP access for the UE,
wherein the UE had the existing PDU session for the IMS voice service via the non-3GPP access before the handover;
transmitting the NAS message including the PDU session establishment request to an Access and Mobility Management Function (AMF);
receiving a PDU session resource setup request for the PDU session for the IMS voice service from the AMF;
determining to trigger an Evolved Packet System (EPS) Fallback, or a radio access technology (RAT) Fallback, for the IMS voice session based on the NG-RAN not supporting the IMS voice service; and
transmitting a rejection of the establishment of the PDU session to the AMF, based on the determination to trigger the EPS Fallback or the RAT Fallback.