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US-20260129546-A1 - METHOD AND DEVICES FOR MANAGING USER EQUIPMENT REGISTRATION DURING DISASTER ROAMING CONDITIONS

US20260129546A1US 20260129546 A1US20260129546 A1US 20260129546A1US-20260129546-A1

Abstract

A method and systems for managing registration of user equipment (UE) during disaster roaming conditions are provided. The method includes receiving, by a network node of a secondary public land mobile network (PLMN), an indication about a termination of a disaster condition, from a primary PLMN, wherein the secondary PLMN provides disaster roaming services to the UE in an evolved packet system (EPS) during the disaster condition in fifth generation system, and transmitting, by the network node to the UE, a non-access stratum (NAS) message that includes radio access technology (RAT) utilization control information and a predefined reject cause prompting the UE to re-attach to the primary PLMN over the 5GS, upon receipt of the indication.

Inventors

  • Danish Ehsan HASHMI
  • Lalith KUMAR
  • Arvind Ramamurthy
  • Jagadeesh GANDIKOTA
  • Pratibha Kattemane SATYAGANAPATI
  • Anurag MANDILWAR

Assignees

  • SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date
20260507
Application Date
20251223
Priority Date
20251008

Claims (20)

  1. 1 . A method of managing registration of a user equipment (UE) during disaster roaming conditions, the method comprising: receiving, by a network node associated with a secondary public land mobile network (PLMN), an indication about a termination of a disaster condition, from a primary PLMN, wherein the secondary PLMN provides disaster roaming services to the UE in an evolved packet system (EPS) during the disaster condition in fifth generation system (5GS); and transmitting, by the network node to the UE, a non-access stratum (NAS) message comprising radio access technology (RAT) utilization control information and a predefined reject cause indicating the UE to re-attach to the primary PLMN over the 5GS, upon receipt of the indication.
  2. 2 . The method of claim 1 , wherein the predefined reject cause is selected from one of: a dedicated cause indicating that a detach request is due to the termination of the disaster condition; and a set of causes comprising at least one of cause #11 (PLMN not allowed), cause #12 (tracking area not allowed), cause #13 (roaming not allowed in this tracking area), cause #14 (EPS services not allowed in this PLMN), cause #15 (no suitable cells in tracking area), cause #31 (redirection to fifth generation core network (5GCN) required), or cause #35 (requested service option not authorized in this PLMN).
  3. 3 . The method of claim 1 , wherein the RAT utilization control information is configured to prevent the UE from re-attaching to the secondary PLMN over EPS.
  4. 4 . The method of claim 1 , wherein the NAS message comprises one of, global unique temporary Identifier (GUTI) relocation command and network-initiated deregistration, when the UE is in connected mode.
  5. 5 . The method of claim 1 , wherein the NAS message comprises attach reject, tracking area update reject or service reject, when the UE is in idle mode.
  6. 6 . A method of restoring service to a user equipment (UE) during a disaster condition, the method comprising: receiving, by the UE, from a network node associated with a secondary public land mobile network (PLMN), a non-access stratum (NAS) message comprising radio access technology (RAT) utilization control information and a predefined reject cause indicating to re-attach to a primary PLMN, wherein the NAS message indicates a termination of a disaster condition; and transmitting, by the UE, a re-registration request to the primary PLMN, upon receipt of the NAS message.
  7. 7 . The method of claim 6 , wherein the predefined reject cause is selected from one of: a dedicated cause indicating that the NAS message is due to the termination of the disaster condition; and a set of causes comprising at least one of cause #11 (PLMN not allowed), cause #12 (tracking area not allowed), cause #13 (roaming not allowed in this tracking area), cause #14 (EPS services not allowed in this PLMN), cause #15 (no suitable cells in tracking area), cause #22 (congestion), cause #31 (redirection to fifth generation core network (5GCN) required), or cause #35 (requested service option not authorized in this PLMN).
  8. 8 . The method of claim 6 , wherein the RAT utilization control information is configured to prevent the UE from re-attaching to the secondary PLMN.
  9. 9 . The method of claim 6 , wherein the re-registration request comprises reapplying an existing RAT utilization control policy being used by the UE before an occurrence of the disaster condition.
  10. 10 . The method of claim 6 , wherein prior to receiving the NAS message, the method comprising pausing a timer when the UE switches from the primary PLMN to the secondary PLMN to obtain roaming services during the disaster condition.
  11. 11 . The method of claim 10 , further comprising restarting the timer with a remaining duration of the timer on detecting the termination of the disaster condition.
  12. 12 . A network node for managing registration of a user equipment (UE) during disaster roaming conditions, the network node being associated with a secondary public land mobile network (PLMN), the network node comprising: memory, comprising one or more storage media, storing instructions; and at least one processor communicatively coupled to the memory, wherein the at least one processor is configured to: receive an indication about a termination of a disaster condition, from a primary PLMN, wherein the secondary PLMN provides disaster roaming services to the UE in an evolved packet system (EPS) during the disaster condition in 5GS, and transmit a non-access stratum (NAS) message comprising radio access technology (RAT) utilization control information and a predefined reject cause indicating the UE to re-attach to the primary PLMN over fifth generation system (5GS), upon receipt of the indication.
  13. 13 . The network node of claim 12 , wherein the at least one processor is configured to: select the predefined reject cause from one of: a dedicated cause indicating that the NAS message is due to the termination of the disaster condition; and a set of causes comprising at least one of cause #11 (PLMN not allowed), cause #12 (tracking area not allowed), cause #13 (roaming not allowed in this tracking area), cause #14 (EPS services not allowed in this PLMN), cause #15 (no suitable cells in tracking area), cause #31 (redirection to fifth generation core network (5GCN) required), or cause #35 (requested service option not authorized in this PLMN).
  14. 14 . The network node of claim 12 , wherein the RAT utilization control information is configured to prevent the UE from re-attaching to the secondary PLMN.
  15. 15 . A user equipment (UE) for restoring service during a disaster condition, the UE comprising: memory, comprising one or more storage media, storing instructions; and at least one processor communicatively coupled to the memory, wherein the at least one processor is configured to: receive from a network node associated with a secondary public land mobile network (PLMN), a non-access stratum (NAS) message comprising radio access technology (RAT) utilization control information and a predefined reject cause indicating to re-attach to a primary PLMN, wherein the NAS message indicates a termination of a disaster condition; and transmit a re-registration request to the primary PLMN, upon receipt of the NAS message.
  16. 16 . The UE of claim 15 , wherein the predefined reject cause is selected from one of: a dedicated cause indicating that a detach request is due to the termination of the disaster condition, and a set of causes comprising at least one of cause #11 (PLMN not allowed), cause #12 (tracking area not allowed), cause #13 (roaming not allowed in this tracking area), cause #14 (EPS services not allowed in this PLMN), cause #15 (no suitable cells in tracking area), cause #31 (redirection to 5GCN required), or cause #35 (requested service option not authorized in this PLMN).
  17. 17 . The UE of claim 15 , wherein RAT utilization control information is configured to prevent the UE from re-attaching to the secondary PLMN.
  18. 18 . The UE of claim 15 , wherein for transmitting the re-registration request, the at least one processor is configured to: reapply an existing RAT utilization control policy being used by the UE before an occurrence of the disaster condition.
  19. 19 . The UE of claim 15 , wherein prior to receiving a detach request, the at least one processor is configured to: pause a timer when the UE switches from the primary PLMN to the secondary PLMN to obtain roaming services during the disaster condition.
  20. 20 . The UE of claim 19 , wherein the at least one processor is further configured to: restart the timer with a remaining duration of the timer on detecting a termination of the disaster condition.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a continuation application, claiming priority under 35 U.S.C. § 365 (c), of an International application No. PCT/KR2025/017715, filed on Oct. 31, 2025, which is based on and claims the benefit of an Indian Provisional patent application number 202441085220, filed on Nov. 6, 2024, in the Indian Intellectual Property Office, of an Indian Provisional patent application number 202411085372, filed on Nov. 7, 2024, in the Indian Intellectual Property Office, and of an Indian Complete patent application No. 202441085220, filed on Oct. 8, 2025, in the Indian Intellectual Property Office, the disclosure of each of which is incorporated by reference herein in its entirety. TECHNICAL FIELD The disclosure relates to a technical field of wireless communication networks. More particularly, the disclosure relates to managing Radio Access Technology (RAT) restrictions and user equipment registration during disaster conditions. BACKGROUND 3rd generation partnership project (3GPP) is a collaborative project aimed at developing globally acceptable specifications for third generation (3G) mobile systems. The need to support different kinds of user equipment (UE), services, and technologies is driving the technological revolution to a high-performance and highly efficient 3GPP system. The 3GPP drivers include Internet of Things (IoT), Virtual Reality (VR), industrial control, ubiquitous on-demand coverage, as well as the opportunity to meet customized market needs. These drivers require enhancements to the devices, services, and technologies well established by 3GPP. Third Generation Partnership Project (3GPP) standards are integral for ensuring that user equipment (UE) can effectively access Public Land Mobile Networks (PLMNs). The current technological landscape facilitates various functionalities for UEs, particularly under adverse conditions such as disasters, enabling them to switch between different network types to maintain connectivity. The provisions outlined in documents such as 3GPP TS 22.261 highlight the ability of UEs to access forbidden PLMNs in emergency scenarios when other networks are unavailable. Subject to regulatory requirements, operator's policy or UE capabilities, 3GPP system shall be able to support a UE, with fifth generation (5G)-only national roaming access to a visited public land mobile network (VPLMN), to obtain fourth generation (4G) connectivity service (for example, voice call, mobile data service, and so on) from that VPLMN in the area where a disaster condition applies. This key issue will address the network selection for the 5G-only national roaming UE in the scenario either where there is no available PLMN except for the 4G PLMN in the “Forbidden PLMN lists” data field in the subscriber identification module (SIM)/universal subscriber identification module (USIM), and the available 5G VPLMN indicates that disaster condition applies, or where there is available 4G VPLMN which is not in the “Forbidden PLMN lists” data field in the SIM/USIM. When a disaster condition is no longer applicable, all the UEs (which are currently being served by the VPLMN providing disaster roaming services in Evolved Packet System (EPS) and are currently in EMM-IDLE mode) may perform PLMN reselection and return to the VPLMN providing 5G-only national roaming access that was previously with disaster condition. When a disaster condition is no longer applicable, the UEs (that are currently in EMM-CONNECTED mode) need to perform EPS to 5G interworking procedures in a way that does not lead to signalling overload in the VPLMN providing 5G-only national roaming access. In the above key issue description and in existing arts, there is no description of how a UE that is currently in EPS (to obtain disaster roaming service) will know that a disaster condition is no longer applicable. Current methods lack clear protocols for signalling the resolution of disaster conditions, leaving UEs without definitive guidance on when they can return to their preferred networks such as, 5G, after being registered on alternate networks for disaster roaming services. Currently, there is no mechanism in existing arts where after an end of the disaster condition, a network can push 5G only roaming UEs that were registered on 5G, but moved to 4G due to disaster condition in 5G, back to 5G. This results in inefficiencies such as service interruptions, difficulties in network reselection, and potential signalling overload, leading to diminished user experience and inefficient network management during critical situations. The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure. SUMMARY Aspects of the disclosure are to address at least the above-mentioned problems and/or dis