Method and apparatus for performing network selection in wireless communication

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure generally relates to wireless communications, in particular, a method and system for performing network selection in wireless communication.The method comprising, receiving, from a base station, steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity; identifying a PLMN identity included in a forbidden PLMN list from the at least one PLMN identity; deleting the PLMN identity from the forbidden PLMN list; resetting a PLMN-specific attempt counter associated with the PLMN identity; and performing network selection based on the at least one PLMN identity.

Description

METHOD AND APPARATUS FOR PERFORMING NETWORK SELECTION IN WIRELESS COMMUNICATION

[0001] The present disclosure generally relates to wireless communications, in particular, but not exclusively to a method and system for performing network selection in wireless communication.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] Mobile communication service have become essential service in daily life, promoting network operators to implement various strategies to prevent service interruption. However, in the event of a disaster such as floods or earthquake or similar emergencies, communication networks connected to the external systems via a individual wireless node may be entirely disrupted. To address such service interruptions, a temporary roaming mechanism is being considered, where user equipment of an affected operator may connect to the network of a nearby operator, ensuring continued access to communication services.

[0009] Further, in such disaster scenarios, efficient management of the Public Land Mobile Network (PLMN) list by the user equipment becomes critical. However, a Forbidden PLMNN (FPLMN) list is also maintained by the UE, ordinarily prevents connection to certain networks. However, in specific coverage areas, these FPLMNs may be capable of limiting services to PLMNs present in the FPLMN list and thereby providing quick registration to other available PLMNs (other than listed in FPLMN list) reducing time to connect to preferred available PLMN with accessibility. In some adverse scenarios, during disaster, there may be specific network area where the PLMNs listed in FPLMN list are able to provide normal services to the user equipment that was typically served by the preferred PLMN without disaster.

[0010] To address the issue, network operators may transmit Non-Access Stratum (NAS) signalling messages that include a list of PLMNs capable of providing connectivity within a specific coverage area under such adverse conditions. Despite this, the user equipment may be unable to select a PLMN from the provided list if it is already stored in the FPLMN list, resulting in continued lack of service. Additionally, the UE may attempt to register with non-preferred PLMNs (that may not be able to provide service in adverse conditions such as disasters), leading to limited or no network service.

[0011] While some existing solutions suggest that PLMN entries in the FPLMN list may be deleted when the UE is powered off or when the SIM card is removed from the user equipment, there is no known prior art that specifically addresses methods for removing specific PLMN entries from the extension of FPLMN list, even after receiving the NAS signalling message for those identified specific PLMN. These particular or specific PLMNs, that were previously part of extension of FPLMN list, may offer network services during disaster roaming conditions based on the network identity available in that specific area where the UE is attempting to connect. This gap highlights the need for a mechanism that allows dynamic management of the extension of the FPLMN list to ensure uninterrupted service during disaster or emergencies.

[0012] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

[0013] In an embodiment the present disclosure provides a method and system for performing network selection in wireless communication during disaster roaming condition.

[0014] In an embodiment, the method performed by a terminal comprising, receiving, from a base station, steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity; identifying a PLMN identity included in a forbidden PLMN list from the at least one PLMN identity; deleting the PLMN identity from the forbidden PLMN list; resetting a PLMN-specific attempt counter associated with the PLMN identity; and performing network selection based on the at least one PLMN identity. .

[0015] In an embodiment, the method performed by a network entity comprising,generating steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity; and transmitting, to a terminal, the SOR information to perform network selection based on the at least one PLMN identity, wherein a PLMN identity of the at least one PLMN identity that is included in a forbidden PLMN list is deleted from the forbidden PLMN list, and wherein a PLMN-specific attempt counter associated with the PLMN identity is reset. .

[0016] In an embodiment of the present disclosure includes a system comprises terminal for performing network selection in wireless communication system. The terminal comprising at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; and at least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the terminal to: receive steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity, identify a PLMN identity included in a forbidden PLMN list from the at least one PLMN identity, delete the PLMN identity from the forbidden PLMN list, reset a PLMN-specific attempt counter associated with the PLMN identity, and perform network selection based on the at least one PLMN identity. In an embodiment of the present disclosure includes a system comprises network entity for performing network selection in a wireless communication system. The network entity comprising at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; and at least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the network entity to: generate steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity, and transmit, to a terminal, the SOR information to perform network selection based on the at least one PLMN identity, wherein a PLMN identity of the at least one PLMN identity that is included in a forbidden PLMN list is deleted from the forbidden PLMN list, and wherein a PLMN-specific attempt counter associated with the PLMN identity is reset. .

[0017] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

[0018] According to embodiments of the present disclosure, efficient communication can be achieved.

[0019] The embodiments of the disclosure itself, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings in which:

[0020] FIG. 1 illustrates an exemplary environment 100 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0021] FIG. 2 illustrates a block diagram of the User Equipment (UE) entity 200 for performing the network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0022] FIG. 3 illustrates a block diagram of the network entity 300 for enabling to perform the network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0023] FIG. 4 illustrates a flow diagram illustrating a method for performing the network selection in wireless communication, in accordance with an embodiment of the present disclosure.

[0024] FIG. 5 illustrates a flowchart representation of a method 500 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0025] FIG. 6 illustrates a flowchart representation of a method 600 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0026] FIG. 7 illustrates a block diagram of an exemplary computer system 700, in accordance with some embodiments of the present disclosure.

[0027] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, sequence diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer-readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

[0028] A User Equipment (UE) and a network may support Minimization of service interruption (MINT). MINT aims to enable the UE to obtain service from a Public Land Mobile Network (PLMN) offering disaster roaming services when a disaster condition applies to the UE's determined PLMN with disaster condition. UEs can obtain service in the event of a disaster, if there are PLMN operators prepared to offer service. The minimization of service interruption is constrained to a particular time and place. To reduce the impact to the 5G System and Evolved Packet System (EPS) of supporting disaster roaming, the potential congestion resulting from an influx or outflux of disaster inbound roamers is taken into account. If the UE has no coverage of its Home Public Land Mobile Network (HPLMN), then obtains information that a disaster condition applies to the UE's HPLMN, the UE can register with a PLMN offering disaster roaming service.

[0029] A 3GPP system shall support means for a PLMN operator to be aware of the area where disaster condition applies. The 3GPP system shall be able to support provision of service to disaster inbound roamer only within the specific region where disaster condition applies. The 3GPP system shall be able to provide efficient means for a network to inform disaster inbound roamers that a disaster condition is no longer applicable. The 3GPP system shall be able to provide means to enable a UE to access PLMNs in a forbidden PLMN (FPLMN) list if a disaster condition applies and no other PLMN is available except for PLMNs in the forbidden PLMN list.

[0030] The 3GPP system supports disaster condition functionality, enabling UEs to obtain information about the disaster condition affecting a specific PLMN. The system informs PLMN operators of affected areas and allows disaster inbound roamers to receive services within those regions. It also provides mechanisms for informing UEs when the disaster condition ends and minimizes congestion from disaster roaming. Additionally, the system enables UEs to access PLMNs on their forbidden list during a disaster condition if no other PLMNs are available, charging information for disaster inbound roamers includes details about the applied disaster condition.

[0031] A Steering of Roaming (SOR) over the control plane in a PLMN: The purpose of the control plane solution for SOR in 5GS procedure in a PLMN is to allow the HPLMN to update one or more of the following via Non Access Stratum (NAS) signaling:

[0032] a) the "Operator Controlled PLMN Selector with Access Technology" list in the UE by providing the HPLMN protected list of preferred PLMN / access technology combinations or a secured packet;

[0033] b) the steering of roaming connected mode control information (SOR-CMCI);

[0034] c) the Steering of Roaming SNPN selection Information (SOR-SNPN-SI) associated with the selected PLMN subscription in the ME; and

[0035] d) the SOR-SNPN-SI-LS associated with the selected PLMN subscription in the ME.

[0036] The UE supporting N1 mode shall support the control plane solution for steering of roaming in 5GS. If the HPLMN or subscribed SNPN supports and wants to use the control plane solution for steering of roaming in 5GS, then the HPLMN or subscribed SNPN shall provide the steering of roaming information to the UE using the control plane mechanism.

[0037] A Visited Public Land Mobile Network (VPLMN) shall transparently relay the steering of roaming (SOR) information received from the HPLMN to the UE. The UE shall be able to detect whether the VPLMN removed the steering of roaming information during the initial registration procedure in the VPLMN. The UE shall be able to detect whether the VPLMN altered the SOR information.

[0038] Extension of the "forbidden PLMNs" list :A Mobile Equipment (ME) may store in its memory (optionally), an extension of the "forbidden PLMNs" list. The contents of the extension of the list shall be deleted when the MS is switched off or a Subscriber Identity Module (SIM) is removed. The VPLMN may be stored in the extension of the "forbidden PLMNs" list if a message with cause value "PLMN not allowed" or "requested service option not authorized in this PLMN" or "Serving network not authorized" is received by an MS in response to an LR request from that VPLMN, and the following is valid: the MS is not configured to use timer T3245, the message is not integrity-protected, the MS maintains a list of PLMN-specific attempt counters and the value of the PLMN-specific attempt counter for that VPLMN is less than an MS implementation specific maximum value then UE perform below action on the timer T3247 expiry

[0039] - for each PLMN-specific attempt counter that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the extension of the "forbidden PLMNs" list;

[0040] - for each PLMN-specific attempt counter for non-3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of "forbidden PLMNs for non-3GPP access to 5GCN";

[0041] - re-enable the N1 mode capability for 3GPP access and, for each PLMN-specific N1 mode attempt counter for 3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of PLMNs where N1 mode is not allowed for 3GPP access (as specified in TS 3GPP　TS　23.122);

[0042] - re-enable the N1 mode capability for non-3GPP access and, for each PLMN-specific N1 mode attempt counter for non-3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of PLMNs where N1 mode is not allowed for non-3GPP access;

[0043] - if the UE maintains a list of PLMN-specific PS-attempt counters, for each PLMN-specific PS-attempt counter that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the "forbidden PLMNs for GPRS service" list. If the resulting "forbidden PLMNs for GPRS service" list is empty, the UE shall re-enable the E-UTRA capability.

[0044] ME shall start timer T3247 with a random value uniformly drawn from the range between 30 minutes and 60 minutes, if the timer is not running if the message is received without integrity protection (NAS message).

[0045] As per the current state of art, when the UE receive the EMM or 5GMM cause #13 (Roaming not allowed in this tracking area), the corresponding Tracking Area Identity (TAI) is added to the "5GS forbidden tracking areas for roaming". If this happens, Problem a) UE will move will not be able to use the same TAI where disaster happens for the same 12-24 hours until the 5GS forbidden tracking areas for roaming list is cleared.

[0046] The UE shall set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause　5.1.3.2.2). If the UE is not registering or has not registered to the same PLMN over both 3GPP access and non-3GPP access the UE shall delete the list of equivalent PLMNs (if available) or the list of equivalent SNPNs (if available). The UE shall reset the registration attempt counter. For 3GPP access the UE shall change to state 5GMM-REGISTERED.PLMN-SEARCH, and for non-3GPP access the UE shall change to state 5GMM-REGISTERED.LIMITED-SERVICE.

[0047] If the UE is registered in S1 mode and operating in dual-registration mode, the PLMN that the UE chooses to register in is specified in subclause　4.8.3. Otherwise, if:

[0048] 1) the UE is not operating in SNPN access operation mode and the Forbidden TAI(s) for the list of "5GS forbidden tracking areas for roaming" IE is not included in the REGISTRATION REJECT message, the UE shall store the current TAI in the list of "5GS forbidden tracking areas for roaming" and shall remove the current TAI from the stored TAI list if present. If the REGISTRATION REJECT message is not integrity protected, the UE shall memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message.

[0049] As per the current state of art, when the UE receive the cause #13, #11 (PLMN not allowed).

[0050] As per the current state of art, when the UE receive the cause #13, #11 (PLMN not allowed). This cause value received from a cell belonging to an SNPN is considered as an abnormal case and the behaviour of the UE is specified in subclause　5.5.1.2.7. The UE shall set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause　5.1.3.2.2) and shall delete any 5G-GUTI, last visited registered TAI, TAI list and ngKSI. The UE shall delete the list of equivalent PLMNs and reset the registration attempt counter and store the PLMN identity in the forbidden PLMN list as specified in subclause　5.3.13A and if the UE is configured to use timer T3245 then the UE shall start timer T3245 and proceed as described in subclause 5.3.19A.1. For 3GPP access the UE shall enter state 5GMM-DEREGISTERED.PLMN-SEARCH and perform a PLMN selection according to 3GPP　TS　23.122　[5], and for non-3GPP access the UE shall enter state 5GMM-DEREGISTERED.LIMITED-SERVICE and perform network selection as defined in 3GPP　TS　24.502

[0018] . If the message has been successfully integrity checked by the NAS and the UE maintains the PLMN-specific attempt counter and the PLMN-specific attempt counter for non-3GPP access for that PLMN, the UE shall set the PLMN-specific attempt counter and the PLMN-specific attempt counter for non-3GPP access for that PLMN to the UE implementation-specific maximum value.

[0051] If the message was received via 3GPP access and the UE is operating in single-registration mode, the UE shall in addition handle the EMM parameters EMM state, EPS update status, 4G-GUTI, last visited registered TAI, TAI list, eKSI and attach attempt counter as specified in 3GPP　TS　24.301

[0015] for the case when the EPS attach request procedure is rejected with the EMM cause with the same value.

[0052] If the message has been successfully integrity checked by the NAS and the UE also supports the registration procedure over the other access to the same PLMN, the UE shall in addition handle 5GMM parameters and 5GMM state for this access, as described for this 5GMM cause value.

[0053] In an embodiment, methods steps for handling the FPLMNs list during the disaster roaming, in accordance with the present disclosure is presented below:

[0054] At step-1: the UE detects that disaster happens and the PLMN-2 provide disaster roaming for the PLMN-1.

[0055] At step 2: the UE register on PLMN-2 for the disaster roaming services and the registration is successful.

[0056] At step 3: the UE uses the Disaster roaming services.

[0057] At step 4: the UE initiates registration procedure or service request procedure.

[0058] At step 5: the AMF is sending reject cause #13 without integrity protection.

[0059] In an aspect, when the UE receives 5GMM cause #11 or #13 in the downlink NAS message (e.g., registration reject) without integrity protected and the UE is registered for the disaster roaming services, then the UE may determine that disaster roaming is ended.

[0060] In an another aspect, when the UE receives 5GMM cause #11 or #13 in the downlink NAS message (e.g., registration reject) when registered for the Disaster roaming services, then the UE may determine that disaster condition is not ended. Additionally, for cause #13, the UE stores, current TAI in the list of "5GS forbidden tracking areas for roaming", the UE may memorize the current TAI (e.g., TAI-1) was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message. Upon expiry of timer T3247, the UE shall: remove all tracking areas from the list of "5GS forbidden tracking areas for regional provision of service" and the list of "5GS forbidden tracking areas for roaming", which were stored in these lists for non-integrity protected NAS reject message. Additionally, for cause #11

[0061] ■ The UE stores, current TAI in the list of "5GS forbidden tracking areas for roaming", the UE shall memorize the current TAI (e.g., TAI-1) was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message,

[0062] ■ Upon expiry of timer T3247, the UE shall: remove all tracking areas from the list of "5GS forbidden tracking areas for regional provision of service" and the list of "5GS forbidden tracking areas for roaming", which were stored in these lists for non-integrity protected NAS reject message.

[0063] The intention to add the TAI of the fake cell to the lists which does not allowed UE to reselect to the same cell.

[0064] In the embodiment, when the UE initiates registration procedure for mobility registration update or service request for the UE registered for the DR services then AMF shall not send registration reject or service reject with 5GMM cause #11 without integrity protected (For the DR (disaster roaming) service registered UE, AMF shall always send SERVICE REJECT, REGISTRATION REJECT with integrity protected).

[0065] In an embodiment, when the UE registered for disaster roaming services (on forbidden PLMN e.g. PLMN-1) and gets the downlink NAS message with 5GMM cause #11 (e.g. in registration reject message) then the UE shall: set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause　5.1.3.2.2) and shall delete, the 5G-GUTI, last visited registered TAI, TAI list, ng KSI for 3GPP access and the list of equivalent PLMNs. Additionally, if a registration procedure was performed, the UE shall reset the registration attempt counter and if a service request procedure was performed, reset the service request attempt counter.

[0066] In an embodiment, If the 5GMM cause value received is #11 and the UE is operating in single-registration mode, handle the EMM parameters EMM state, EPS update status, EPS attach attempt counter, tracking area updating attempt counter or service request attempt counter, 4G-GUTI, TAI list, eKSI as specified in 3GPP　TS　24.301

[0015] for the case when the EPS attach, tracking area updating procedure or service request procedure is rejected with the EMM cause of the same value in a NAS message without integrity protection.

[0067] In an embodiment, If the 5GMM cause value received is #73 and the UE is operating in single-registration mode, the UE shall in addition set the EPS update status to EU3 ROAMING NOT ALLOWED and shall delete any 4G-GUTI, last visited registered TAI, TAI list and eKSI. Additionally, the UE shall reset the attach attempt counter or tracking area updating attempt counter, and enter the state EMM-DEREGISTERED. store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE and search for a suitable cell in another tracking area according to 3GPP　TS　38.304

[0028] or 3GPP　TS　36.304　[25C]; and as the UE implementation option, the UE may perform registration attempt over the non-3GPP access, if non-3GPP access is available, the UE is not registered over non-3GPP access yet, and the USIM is not considered invalid for 5GS services over non-3GPP access.

[0068] Upon expiry of timer T3247, the UE shall: remove all tracking areas from the list of "5GS forbidden tracking areas for regional provision of service" and the list of "5GS forbidden tracking areas for roaming", which were stored in these lists for non-integrity protected NAS reject message, i.e., when the UE receive the 5GMM cause #11, 71 for the UE registered for the disaster roaming service (in any PLMN) then it UE treat the 5GMM cause is coming from the home PLMN and handle the 5GMM cause accordingly.

[0069] In this embodiment, the term forbidden lists, "5GS forbidden tracking areas for roaming" and "5GS forbidden tracking areas for regional provisioning of service" are used interchangeably. In general, this can be any list which will indicate to the UE that a stored TAI in that list is forbidden for it.

[0070] In an embodiment, when UE initiates registration for disaster roaming service: The UE and the network may support Minimization of service interruption (MINT). MINT aims to enable a UE to obtain service from a PLMN offering disaster roaming services when a disaster condition applies to the UE's determined PLMN with disaster condition. When the UE register for the DR service, it indicate 5GS registration type value as

[0071] ● disaster roaming mobility registration updating.

[0072] ● disaster roaming initial registration.

[0073] In the registration request. The UE is registered for the DR service if the UE receive registration accept without 5GS registration result or Disaster roaming registration result value of the 5GS registration result IE set to 0 (No additional information).

[0074] In an embodiment, the UE registered for disaster roaming service:

[0075] - Include 5GS registration type with the value set to disaster roaming mobility registration updating in the registration procedure for mobility registration update

[0076] - Include 5GS registration type with the value set to disaster roaming initial registration in the registration procedure for initial registration.

[0077] In an embodiment, PLMN in extension of the forbidden list shall be removed as a result of certain procedures for example as below :

[0078] a. After a subsequent manual selection of that PLMN (e.g., PLMN-1 which is in extension of the "forbidden PLMNs" list ), there is a successful LR not for disaster roaming services, then the PLMN (e.g., PLMN-1) is removed / delete from the extension of the "forbidden PLMNs" list;

[0079] b. The MS is configured to use timer T3245 and the timer T3245 expires, then the PLMN is removed from the extension of the "forbidden PLMNs" list or extension of the "forbidden PLMNs" list is deleted; or

[0080] c. The MS is not configured to use timer T3245 and:

[0081] d. The MS maintains a list of PLMN-specific attempt counters, the value of the PLMN-specific attempt counter for that PLMN is greater than zero and less than the MS implementation specific maximum value, and timer T3247 expires, then the PLMN is removed from the extension of the forbidden list.

[0082] e. The MS does not maintain a list of PLMN-specific attempt counters, the PLMN is stored in the "forbidden PLMNs" list in the SIM, and the timer T3247 expires, then the PLMN is removed from the extension of the forbidden list.

[0083] f. After a subsequent manual selection of that PLMN , there is a successful LR not for disaster roaming services, then the PLMN is removed from the extension of the forbidden list;

[0084] g. The MS is configured to use timer T3245 and the timer T3245 expires, then the PLMN is removed from the extension of the "forbidden PLMNs" list or extension of the "forbidden PLMNs" list is deleted / removed from the UE; or

[0085] h. The MS is not configured to use timer T3245 and:

[0086] i. The MS maintains a list of PLMN-specific attempt counters, the value of the PLMN-specific attempt counter for that PLMN is greater than zero and less than the MS implementation specific maximum value, and timer T3247 expires, then the PLMN is removed from the extension of the forbidden list

[0087] j. The MS does not maintain a list of PLMN-specific attempt counters, the PLMN is stored in the "forbidden PLMNs" list in the SIM, and the timer T3247 expires, then the PLMN is removed from the extension of the forbidden list.

[0088] In an embodiment, PLMN in extension of the "forbidden PLMNs" list shall be removed as a result of Steering of Roaming (SOR): If the steering of roaming information contains the list of preferred PLMN / access technology combinations, the ME shall replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the received list of preferred PLMN / access technology combinations, and delete the PLMNs identified by the list of preferred PLMN / access technology combinations from the extension of the "forbidden PLMNs" list, i.e., suppose extension of the "forbidden PLMNs" list contain PLMN-1. UE receive steering of roaming information contains the list of preferred PLMN / access technology combinations (including PLMN-1) then UE shall delete the PLMN-1 from the extension of the "forbidden PLMNs" list.

[0089] In this embodiment, if the steering of roaming information contains the list of preferred PLMN / access technology combinations, the ME shall replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the received list of preferred PLMN / access technology combinations, and delete the PLMNs identified by the list of preferred PLMN / access technology combinations from the Forbidden PLMN list and from the Forbidden PLMNs for GPRS service list and extension of the "forbidden PLMNs" list, if they are present in these lists. At step 0: UE stores an extension of forbidden PLMN list. At step 1: UE registers / registering on VPLMN / HPLMN. At step 2: NAS Signaling Message with SOR information containing list of preferred PLMN / access technology combinations. At step 3: UE delete the PLMNs identified by the list of preferred PLMN / access technology combinations / secure packet received in SOR information from the extension of the forbidden list.

[0090] In an embodiment, if the MS receives a USAT REFRESH command qualifier (3GPP　TS　31.111

[0041] ) of type "Steering of Roaming", the MS shall:

[0091] a) Replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the list provided in the REFRESH command, if any, or replace the SOR-CMCI in the ME with the SOR-CMCI provided in REFRESH command, if any, or both.

[0092] b) Delete the PLMNs identified by the list in the REFRESH command from the Forbidden PLMN, from the Forbidden PLMNs for GPRS service list and extension of the "forbidden PLMNs" list, if they are present in these lists. This includes any information stored in the SIM and the ME internal memory.

[0093] c) Take the latest information into account in subsequent attempts to access a higher priority PLMN.

[0094] d) Attempt to obtain service on a higher priority PLMN as specified in clause　4.4.3.3 by acting as if timer T that controls periodic attempts has expired.

[0095] In an embodiment, for the manual selection of the PLMN, there is a successful LR (e.g., UE receive registration accept, attach accept or tracking area update accept) not for disaster roaming services, then the PLMN is removed from the extension of "forbidden PLMNs" list.

[0096] In an embodiment, if the steering of roaming information contains the list of preferred PLMN / access technology combinations, the ME shall replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the received list of preferred PLMN / access technology combinations, and delete the PLMNs identified by the list of preferred PLMN / access technology combinations from the Forbidden PLMN list and from the Forbidden PLMNs for GPRS service list and extension of the "forbidden PLMNs" list, if they are present in these lists.

[0097] In an embodiment, a VPLMN (e.g., PLMN-1) may be stored in the extension of the "forbidden PLMNs" list if a message with cause value "PLMN not allowed" or "Requested service option not authorized in this PLMN" or "Serving network not authorized" is received by an MS in response to an LR request from that VPLMN, and the following is valid:

[0098] ■ the MS is not configured to use timer T3245, the message is not integrity-protected, the MS maintains a list of PLMN-specific attempt counters and the value of the PLMN-specific attempt counter for that VPLMN is less than an MS implementation specific maximum value as defined in 3GPP　TS　24.008

[0023] , 3GPP　TS　24.301　[23A] and 3GPP　TS　24.501

[0064] .

[0099] The UE may delete the PLMN (e.g., PLMN-1) from extension of the forbidden PLMNs list or delete extension of the forbidden PLMN list only when PLMN (PLMN-1) in the extension of the forbidden PLMN list has the PLMN-specific attempt counters which is reset (i.e., 0). i.e., PLMN-specific attempt counters for PLMN-1 is zero. In yet another embodiment, the UE may delete PLMN (PLMN-1) from extension of "forbidden PLMN" list when PLMN-specific attempt counters is reset for the PLMN-1 is not set to zero (reset).

[0100] In yet another embodiment, when the UE delete PLMN (e.g., PLMN-1) from the extension of the "forbidden PLMN" list then PLMN-specific attempt counters is reset for the PLMN (e.g., PLMN-1) if not reset (zero) already. Additionally, timer T3247 shall be stopped (if PLMN-1 was the only PLMN in the extension of the forbidden PLMN list).

[0101] In yet another embodiment, when the UE delete PLMN (e.g. PLMN-1) from the extension of the "forbidden PLMN" list then PLMN-specific attempt counters is reset for the PLMN (e.g., PLMN-1) for the access where LR is successful (e.g. UE receive registration accept on PLMN-1 on 3GPP access then UE shall reset the PLMN-specific attempt counters for the PLMN-1 for the 3GPP access ) . Additionally, timer T3247 shall be stopped (if PLMN-1 was the only PLMN in the extension of the forbidden PLMN list). UE shall reset PLMN-specific attempt counters for each PLMN when USIM is changed / removed / replaced. PLMN-specific attempt counters is reset for all access.

[0102] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0103] While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

[0104] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a device or system or apparatus proceeded by "comprises...a" does not, without more constraints, preclude the existence of other elements or additional elements in the device or system or apparatus.

[0105] The term "disaster condition" may refer to a scenario where a PLMN that typically provides normal service in a region is currently out-of-operation (OoO). The types of events causing such an OoO "disaster condition" may vary, and any reference herein to a "disaster condition" is not limited to any particular type of outage, but more generally refers to the network / PLMN being unable to provide services to the UE to which it may normally provide such network services.

[0106] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0107] In an embodiment the present disclosure provides a method and system for performing network selection in wireless communication during disaster roaming condition.

[0108] In an embodiment, the method comprising, receiving, by a User Equipment (UE) entity, information including at least one available Public Land Mobile Network (PLMN) identity, and determining by the UE entity, whether at least one stored PLMN identity in one of a list maintained by the UE entity matches the at least one available PLMN identity included in the received information. Further in response to determining by the UE entity, that the at least one stored PLMN identity in one of the list matches the at least one available PLMN identity in the received information, deleting, by the UE entity, at least matched PLMN identity from one of the FPLMN list and resetting a PLMN-specific (PS) attempt counter associated with at least one deleted PLMN identity. Further in method steps include performing by the UE entity, network selection based on the at least one available PLMN identity.

[0109] In an embodiment, the method steps comprising, generating, by a network entity, information including at least one Public Land Mobile Network identity detected as available PLMN identity in a network coverage area of the user equipment entity and transmitting, to the UE entity by the network entity, the generated information to perform network selection based on at least one available PLMN identity.

[0110] In an embodiment of the present disclosure includes a system comprises User Equipment entity for performing network selection in wireless communication, the UE entity comprising a transceiver, at least one memory; and at least one processor coupled with the transceiver and at least one memory. Further at least one processor is configured to receive information including at least one available Public Land Mobile Network identity, determine whether at least one stored PLMN identity in one of a Forbidden Public Land Mobile Network list maintained by the UE entity matches the at least one available PLMN identity included in the received information. Further at least one processor is configured in response to determining that the at least one stored PLMN identity in one of the FPLMN list matches the at least one available PLMN identity in the received information, delete at least one matched PLMN identity from one of the FPLMN list and reset a PLMN-specific (PS) attempt counter associated with the at least one deleted PLMN identity, and perform network selection based on the at least one available PLMN identity.

[0111] In an embodiment of the present disclosure includes a system comprises network entity for performing network selection in wireless communication, the network entity comprising a transceiver, at least one memory and at least one processor coupled with the transceiver and the at least one memory. Furthher the at least one processor is configured to generate information including at least one Public Land Mobile Network (PLMN) identity detected as available PLMN identity in a network coverage area of the user equipment (UE) entity and transmit, to the UE entity, the generated information to perform network selection based on the at least one available PLMN identity.

[0112] FIG. 1 illustrates an exemplary environment 100 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0113] In an embodiment, the exemplary environment 100 may comprise a User Equipment (UE) entity 103, and a network entity 105. The UE entity 103 and network entity 105 are communicably coupled through a communication network 101. Further, the UE 103 may receive information, from the network entity 105, for performing network selection in wireless communication during disaster roaming condition. The exemplary environment 100 may include any number of UE Entity 103 being used by any number of users. Thus, the example of a single UE entity 103 may be merely provided for illustrative purposes. Further in the exemplary environment 100 may include plurality of network Entities 105 within which the UE entity 103 may attempt to perform network selection. Thus, the example of a single UE　103　is merely provided for illustrative purposes.

[0114] In an embodiment, the UE entity 103 may include, but not limited to, electronic component that is configured to communicate via a network, e.g., mobile phones, tablet computers, desktop computers, smartphones, phablets, embedded devices, wearables, Internet of Things (IoT) devices, a personal digital assistant, a navigation system, a tablet computer, a tablet computer, a wearable device, a computer, a laptop computer, Internet Of Things (IoT) device, a camera, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather / environment device, a device related to a 5G service or any other device, and the combination thereof. The UE entity 103 may be configured to communicate with one or more network entity 105 (not shown here).

[0115] In an embodiment, the network entity 105 may include, but not limited to, cell, mobility management entity, core network component or base station, a Next Generation Node B such as gNodeB (gNB), an Evolved Node B (eNB), a Distributed Unit (DU), HeNBs, macrocells, microcells and a Centralized Unit (CU). The network entity 105 may be configured to send and receive traffic from UE entity 103. In an embodiment, network entity 105 may be configured to send and receive data from one more other network entity 105.

[0116] In an embodiment, the UE entity 103 and the network entity 105 may communicate each other using the communication network 101.The　communication network 101 also manages the traffic that flows between the cellular network, for example communication network 101 may install a plurality of core network nodes, such as AMF, so that even if a problem occurs in one core network node, other core network nodes perform backup to prevent communication services from being disconnected. The communication network may be basically a 5G network or beyond and utilizes various and essential network functions operating at normal and as well as at disaster condition, for example, minimization of service interruption (MINT) described in S3.1 and S6.31 of 3GPP TS 22.261 V17.2.0 may be referred for network function operability and omitted here for the sake of brevity.

[0117] FIG. 2 illustrates a block diagram of the User Equipment (UE) entity 200 (similar to UE Entity 103) for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0118] As shown in FIG. 2, in an embodiment, the UE entity 200 may include a transceiver 201 enabled to receive and / or transmit information, at least one memory 205 storing instructions, executable by at least one processor 203, which, on execution, may cause the UE entity 200 to perform network selection in wireless communication during disaster roaming condition. Additional and / or alternatively, in another embodiment the　memory　205 may be placed inside of the　processor 203. In an embodiment, the processor 203 may include a roaming unit 203.1 and a counter unit 203.2. In an embodiment, each of the one or more modules of the UE entity 200 may be implemented as a hardware unit, configured to communicate with one another to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts, sequence diagrams described in the present disclosure.

[0119] In an embodiment, the transceiver 201 may include a capability of transmitting and receiving radio signals through the antennas. The transceiver 201 may also be considered a RF unit. The information transmitted and received though the transceiver 201 may be user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, methods and / or operational flowcharts, sequence diagram disclosed in the present disclosure, through the one or　more antennas employed by the transceiver 201. In the UE entity 200, the transceiver 201 may be employed to communicate with one or more network entity 300 or with one or more UE entity 200 and the processor 203 that are further communicatively coupled to each other to perform operations of the present disclosure. The　transceiver　201　may operate on a variety of different frequencies or channels is an aspect.

[0120] In an embodiment, the processor 203 is embodied as an executor of software instructions. As such, the processor 203 is capable of executing the instructions stored in the memory 205 to perform one or more operations described herein. The processor 203 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the processor 203 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a Digital Signal Processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including, a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0121] Further in an exemplary embodiment the processor 203 may be split among two or more processor units such the roaming unit 203.1 and the counter unit 203.2. The exemplary embodiment may be implemented in any of these or other configuration of the UE entity 200.

[0122] Further in an embodiment, the roaming unit 203.1 of the processor 203 may provide hardware and software configuration to UE entity 200 to perform operations such as transmitting a registration request in a network coverage area. The functional aspect is covered in upcoming paragraphs of FIG. 4 description.

[0123] Further in an embodiment, the counter unit 203.2 of the processor 203 may be configured to provide both hardware and software support to the UE entity 200, enabling it to perform operations such as dynamically updating specific attempt counters associated with each PLMN identity with which the UE entity 200 is configured or processed to attempt registration. In an exemplary embodiment, the attempts counters may include timers T3245 and timer T3247. Further the updating process of counter is discussed in detail in upcoming paragraphs of the present disclosure.

[0124] Further in an embodiment, the processor 203 may be configured to perform various operations as elaborated in detail in the upcoming paragraphs of FIG. 4 and FIG.5.

[0125] Further in an embodiment, the memory 205 may be a hardware component configured to store data related to operations, information or instructions performed by the UE　entity 200. The memory may store software codes which implements instructions that, when executed by the　processor　203, perform the descriptions, functions, procedures, methods and / or operational flowcharts, sequence diagrams disclosed in the present disclosure. In an exemplary embodiment, the memory 205 may be a RAM, a dynamic RAM (DRAM), a ROM, a flash memory, a volatile memory, a non-volatile memory, a memory card, a storage medium and / or other storage device and / or a combination thereof.

[0126] FIG. 3 illustrates a block diagram of the network entity 300 (same as network entity 105) for enabling to perform the network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0127] As shown in FIG. 3, in an embodiment, the network entity 300 may include a transceiver 301 enabled to receive and / or transmit information, at least one memory 305 storing instructions, executable by at least one processor 303, which, on execution, may cause the network entity 300 to perform generation and transmission of information in wireless communication during disaster roaming condition. Additional and / or alternatively, the　memory　305 may be placed inside of the　processor 303. In an embodiment, the processor 303 may include a roaming unit 303.1 and a generation unit 303.2. In an embodiment, each of the one or more modules of system 300 may be implemented as a hardware unit, configured to communicate with one another to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts, sequence diagrams described in the present disclosure.

[0128] In an embodiment, the transceiver 301 may be include a capability of transmitting and receiving radio signals through the antennas. The transceiver 301 may also be considered a RF unit. The information transmitted and received though the transceiver 301 may be user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, methods and / or operational flowcharts, sequence diagram disclosed in the present disclosure, through the one or　more antennas employed by the transceiver 301. In the network entity 300, the transceiver 301 may be employed to communicate with one or more UE entity 200. In the network entity 300, transceiver 301 is communicatively coupled to the and configured to the processor 303 to perform operations of the present disclosure. The　transceiver　301　may operate on a variety of different frequencies or channels is an aspect.

[0129] In an embodiment, the processor 303 is embodied as an executor of software instructions. As such, the processor 303 is capable of executing the instructions stored in the memory 305 to perform one or more operations described herein. The processor 303 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the processor 203 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a Digital Signal Processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including, a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0130] Further in an exemplary embodiment the processor 303 may be split among two or more processor units such a roaming unit 303.1 and a generation unit 303.2. In an exemplary embodiment, the processor 303 may be implemented in any of these or other configuration of the network entity 300.

[0131] Further, in one embodiment, the roaming unit 303.1 of the processor 303 may be configured to provide both hardware and software support to the network entity 300, enabling it to perform operations such as detecting the network coverage area of the UE entity 200. The functional aspect is covered in upcoming paragraphs of FIG. 4 description.

[0132] Further in an embodiment, the generation unit 303.2 of the processor 303 may be configured to provide both hardware and software support to the UE entity 300, enabling it to generate an information such as NAS signalling message that may be transmitted to the UE entity 200. Further the generation process is discussed in detail in upcoming paragraphs of the present disclosure.

[0133] Further in an embodiment, the processor 303 is configured to perform various operations as elaborated in detail in the upcoming paragraphs of FIG. 4 and FIG.6.

[0134] FIG. 4 illustrates a flow diagram illustrating a method for performing the network selection in wireless communication (similar to environment 100), in accordance with an embodiment of the present disclosure.

[0135] In an embodiment, the system 400 may include UE entity 401 (similar to UE entity 200) and network entity 403 (similar to network entity 300). Both the entities discussed above are communicably coupled via the communication network 101 (not explicitly shown, but implicitly understood to be present) to perform the steps discussed in foregoing paragraphs.

[0136] Further the steps appearing with similar step numbers may or may not be implemented as simultaneous process step at various entities shown in the figure. Further the entities (user / network) are discussed in detail, taking reference from FIG. 2 and FIG. 3, therefore omitted here for the sake of brevity.

[0137] Further the processor 203 and the processor 303 are configured to execute the method steps discussed below. For example, the roaming unit 203.1 and roaming unit 303.1 are　configured to perform operations such as determining an preferred PLMN for the UE entity 401 that is currently under disaster and attempting to register with a forbidden PLMN (FPLMN) offering disaster roaming services using the allowable PLMN as the "available PLMN."

[0138] In an aspect. if a PLMN from the extended "forbidden PLMNs" list is manually selected and the UE entity 200 successfully registers on it, the UE still won't be able to access normal services because that PLMN is marked as forbidden. And when the UE　entity 200　attempts to register it may receive a rejection for the registration attempt including a new cause value indicating "Disaster roaming for the determined PLMN with disaster condition not allowed in this tracking area" as discussed earlier. And in another aspect, for example a PLMN-1 is part of the extended "forbidden PLMNs" (FPLMN) list. If the user UE entity 200 may receive SOR (Steering of Roaming) information through NAS messages―such as "Registration Accept" or Downlink NAS Transport message that includes PLMN-1 as a preferred PLMN / access technology combination, it may indicates a new roaming agreement between the home PLMN (HPLMN) and PLMN-1. UE entity 200 attempt to select PLMN-1 to access services. However, since PLMN-1 is still listed in the extended FPLMN list, the UE is unable to select it and may remain in limited service or no service at all.

[0139] In an embodiment, the methods steps discussed below may enable UE entity 200 to update the extension of forbidden list, when a PLMN-1 for example that is part of the extension of FPLMN list becomes a preferred network due to updated Steering of Roaming (SOR) information received via NAS signaling messages.

[0140] Now getting in details of method steps explaining the functional aspect of the present disclosure, starting a At step 0, may present that the memory 205 or the processor 203 of UE entity 401 may be storing a FPLMN list.

[0141] For example, the standard FPLMN list includes PLMN identities that the UE entity 401 is explicitly restricted from registering with, typically based on failed registration attempts or network operator-defined policies. In an aspect, the extension of the forbidden PLMN list serves as a dynamic and context-aware enhancement, allowing temporary or conditional restrictions to be applied based on real-time network conditions, such as during disaster recovery or roaming scenarios. This extended list may be updated or modified based on signalling messages received from the network, enabling the UE entity 401 to adapt its network selection behaviour accordingly. Further, the FPLMN list for GPRS services specifically governs access to packet-switched data services, ensuring that the UE entity 401 does not attempt GPRS registration with networks that may be restricted for data connectivity, even if voice services may be permitted. Together, these components enable the UE entity 401 to perform intelligent and policy-driven network selection, ensuring compliance with operator preferences, regulatory requirements, and service continuity strategies. A forbidden PLMN (FPLMN) includes PLMN identities that are typically restricted from registration attempts. This extended list may be maintained in the UE entity's memory 205 and may be used during network selection procedures to avoid connection attempts to non-preferred or restricted networks. Further the details to the list discussed above in exemplary embodiment above and are also discussed in detail in overview section of the present disclosure.

[0142] In an aspect, a list of FPLMNs is maintained by the UE entity 401, and a new PLMN identity entry may also be added to the list of FPLMNs when the UE entity 401 attempts to access the new PLMN identity (e.g., transmits an attach request) and the new PLMN identity rejects the request using a cause code of "PLMN not allowed" or the like. These aspects along with other scenarios (discussed in overview section above) are omitted here for the sake of brevity as the person skill in art can relate and derive the terms and scenarios well known in this specific art.

[0143] In an exemplary embodiment, under the disaster conditions, one of the PLMN identity, which may be normally a forbidden PLMN (FPLMN) for the UE entity 401 and being present in one of the FPLMN list maintained by the UE entity 401, may enable disaster roaming for the UE entity 401. For example, the network entity 403 can check whether a disaster roaming agreement (DRA) exists between the FPLMN and the HPLMN for the UE entity 401. The network entity 403 may also get configured to maintain the latest terms and agreements as such to get non hindered services under disaster conditions.

[0144] In an embodiment, at step 0 the UE entity 401 may store FPLMN lists also referred to forbidden lists. The FPLMN list may include a standard FPLMN list, an extension of the forbidden PLMN list, and, a FPLMNs list for GPRS service. The forbidden lists are updated at step 6 for different scenarios discussed above in preceding paragraphs.

[0145] Now coming at Step 1, where the roaming unit 203.1 of the UE entity 401 attempts to register with either a Visited PLMN (VPLMN) or its Home PLMN (HPLMN), depending on availability and network available. This registration process may include several steps defined by the 3GPP roaming standards. For example, UE entity 401 begins by scanning and selecting a suitable PLMN based on priority and availability list stored in the UE entity 401. UE entity 401 may then sends a NAS Registration Request to initiate the registration process. The network entity 403 may authenticate the UE entity 401 using secure credentials. Upon successful authentication, a Security Mode Command is issued to establish encryption and integrity protection. The network entity 403 may respond with a Registration Accept message, which may include service details and SOR information. The UE entity 401 confirms registration with a Registration Complete message. Finally, the UE entity 401 gains access to network services as permitted by its subscription and the selected PLMN. But if the UE entity 401gets any cause value for restricted message or "no roaming" message then the HPLMN may be configured to access the geographically location or network coverage area of the UE entity 401 by the HPLMN to further proceed to method steps as discussed below.

[0146] Further at step 1, where the roaming unit 303.1 of the network entity 403 may be configured to detect the network coverage area of a UE entity 401 through a combination of signalling exchanges between the UE entity 401 and neighbouring cell information. For example, the network entity 403 may be considered as HPLMN. In an aspect, the signalling messages are further measured are analysed by the network entity 403 to assess the radio conditions surrounding the UE entity 401. In addition, location estimation techniques such as triangulation, time-of-arrival, or GPS-based methods may be employed to determine the UE entity's 401 geographical position. Further by determining anlyzed data with predefined coverage maps, the network entity 403 identifies the specific network coverage area in which the UE entity 401 wants to operate. After the identification, the network entity 403 may facilitates adaptive decision-making for network optimization, handover, or activation of disaster roaming protocols based on the renewed or active DRAs between various network providers in the determined network coverage area of the UE entity 401.

[0147] At step 2, based on the determined network coverage area the network entity 403 may be configured to detect available networks. The generation unit 303.2 of the network entity 403 may then configured to generate information including the at least one available PLMN identity based on the detection of the available PLMN. The information may be included in one of the signals such as Non-Access Stratum (NAS) signaling message (e.g REGISTRATION ACCEPT or UE CONFIGURATION COMMAND message) or Steering of Roaming (SOR) information. The information may also include meassage to update the USIM. The updation at USIM may be for example initaited by Universal Subscriber Identity Module (USIM) refresh command.For example, SOR in 5GS procedure in a PLMN is to allow the HPLMN to update one or more of the following via Non Access Stratum (NAS) signalling such as the "Operator Controlled PLMN Selector with Access Technology" list in the UE by providing the HPLMN protected list of preferred PLMN / access technology combinations or a secured packet, the steering of roaming connected mode control information (SOR-CMCI), the Steering of Roaming SNPN selection Information (SOR-SNPN-SI) associated with the selected PLMN subscription in the ME and the SOR-SNPN-SI-LS associated with the selected PLMN subscription in the ME.

[0148] If the HPLMN or subscribed SNPN supports and wants to use the control plane solution for steering of roaming in 5GS, then the HPLMN or subscribed SNPN shall provide the steering of roaming information to the UE entity 401 using the control plane mechanism. Further A Visited Public Land Mobile Network (VPLMN) shall transparently relay the steering of roaming (SOR) information received from the HPLMN to the UE entity 401. The UE may detect whether the VPLMN removed the steering of roaming information during the initial registration procedure in the VPLMN. The UE entity 401 may detect whether the VPLMN altered the SOR information.

[0149] At step 3, the downlink conrol or transport signal including the information may be then tranmitted by the transceiver 301 of the network entity 403 to the transceiver 201 of the UE entity 401. The information including all determined PLMN that are available to provide services in the specific network coverage area identified for the UE entity 401, seeking for network services.

[0150] At step 4, the information is received by the UE entity 401. Based on the information received by the UE entity 401, one of the processor 203 may match, each of the available PLMN identity received in the information with each of the PLMN identities stored in each of the FPLMN lists stored in the memory 205 of the UE entity 401.The list stored in the memory 205 of the UE entity 401 is discussed in the step 0 above. Further in step 4, at least one of the processor 203 may determine or analyze the PLMN identities in received information with the PLMN identities or entries of the FPLMN list stored at UE entity 401. In an embodiment, at least one of the processor 203 may determine or analyze the PLMN identities in received information with the PLMN identities or entries of the extension of FPLMN list stored at UE entity 401. In an embodiment, at least one of the processor 203 may determine or analyze the PLMN identities in received information with the PLMN identities or entries of forbidden PLMNs for GPRS service stored at UE entity 401.

[0151] If there is a match of PLMN identity between the available PLMN identity and PLMN identity in the any of the FPLMN List, then the system 400 is configured to perform step 5 and step 6.In an embodiment, in an non limiting example the processor 203 is configured to produce a list of matched PLMN identities based on the above determination discussed in preceding paragraphs. The matched list, may for example include the matched PLMN identities that are determined or identified to be the same with the PLMN identities in received information with corresponding FPLMN lists. For example, a matched list for extension of FPLMN list may be produced, reflecting the PLMN identities that appear to be similar in both the compared list (here, PLMNs in received information and PLMNs in extension of FPLMN list). In an embodiment, similar matched list may be produced with the FPLMN list and the list of forbidden PLMNs for GPRS service.

[0152] At step 5, one of the processor 203 of the UE entity 401 may be configured to delete at least one matched PLMN identity from one of the FPLMN list stored in the memory 205 of the UE entity 401. In an embodiment, FPLMN list is at least one of the following forbidden PLMN list, extension of forbidden PLMN list, list of forbidden PLMNs for GPRS service.

[0153] At step 6, the counter unit 303.2 of the UE entity 401 may be configured to reset a PLMN-specific (PS) attempt counter associated with the at least one deleted PLMN identity as discussed in the above step 5.

[0154] In an embodiment, UE may maintain different PLMN-specific (PS) attempt counter for PLMN associated with forbidden PLMN list, extension of forbidden PLMN list, forbidden PLMNs for GPRS service. For an example, PLMN-specific attempt counter may be associated with forbidden PLMN list, extension of forbidden PLMN list and PLMN-specific PS-attempt counters may be associated with list of forbidden PLMNs for GPRS service.

[0155] In an embodiment, when the PLMN (e.g PLMN-1) is removed / deleted from the list of "forbidden PLMNs" including extension of the "forbidden PLMNs" list due to :

[0156] 1) The MS receive USAT REFRESH command qualifier (as specified in 3GPP　TS　31.111

[0041] ) of type "Steering of Roaming" and delete the PLMNs (e.g PLMN-1) identified by the list in the REFRESH command from the Forbidden PLMN list including extension of the "forbidden PLMNs" list, if they are present in these lists.

[0157] 2) UE receive steering of roaming information over the control plane and the steering of roaming information contains the list of preferred PLMN / access technology combinations , the ME shall replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the received list of preferred PLMN / access technology combinations, and delete the PLMNs (e.g PLMN-1) identified by the list of preferred PLMN / access technology combinations from the Forbidden PLMN list including extension of the "forbidden PLMNs", if they are present in these lists.

[0158] Then the UE reset PLMN-specific attempt counter for that PLMN (e.g for PLMN-1)

[0159] In an embodiment, when the PLMN (e.g PLMN-1) is removed / deleted from the list of " Forbidden PLMNs for GPRS service" due to:

[0160] 1) The MS receive USAT REFRESH command qualifier (as specified in 3GPP　TS　31.111

[0041] ) of type "Steering of Roaming" and delete the PLMNs (e.g PLMN-1) identified by the list in the REFRESH command from the " Forbidden PLMNs for GPRS service "list, if they are present in these lists.

[0161] 2) UE receive steering of roaming information over the control plane and the steering of roaming information contains the list of preferred PLMN / access technology combinations, the ME shall replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the received list of preferred PLMN / access technology combinations, and delete the PLMNs (e.g PLMN-1) identified by the list of preferred PLMN / access technology combinations from the " Forbidden PLMNs for GPRS service "list, if they are present in these lists.

[0162] Then the UE reset PLMN-specific PS-attempt counter for that PLMN (e.g PLMN-1). If the resulting "forbidden PLMNs for GPRS service" list is empty, the UE shall re-enable the E-UTRA capability.

[0163] Finally at step 7 (not shown in the figure), now the UE entity 401 may be configured to establish network connection with at least one of the PLMN identity received from the information received from the network entity 403 in the disaster roaming condition. The procedural steps for performing the network selection is known in prior art and description of this is omitted here for the sake of brevity.

[0164] FIG. 5 illustrates a flowchart representation of a method 500 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0165] The method 500 may comprise one or more steps. The method 500 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.

[0166] Further, the order in which the method 500 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0167] The steps discussed below are performed by the UE entity 200. All the modules of the UE entity 200 are configured to perform the following steps:

[0168] At step 501, the method 500 includes receiving, by the User Equipment (UE) entity 200, by the network entity 300, information including at least one available Public Land Mobile Network (PLMN) identity.

[0169] At step 503, the method 500 includes determining, by the UE entity 200, whether at least one stored PLMN identity in one of a (FPLMN) list maintained by the UE entity 200 matches the at least one available PLMN identity included in the received information.

[0170] At step 505, the method 500 includes performing deletion, by the UE entity 200, at least matched PLMN identity from one of the FPLMN list.

[0171] At step 507, the method 500 includes performing resetting, by the UE entity 200, a PLMN-specific (PS) attempt counter associated with at least one deleted PLMN identity.

[0172] At step 509, the method 500 includes performing network selection, by the UE entity 200, network selection based on the at least one available PLMN identity.

[0173] FIG. 6 illustrates a flowchart representation of a method 600 for performing network selection in wireless communication, in accordance with some embodiments of the present disclosure.

[0174] The method 600 may comprise one or more steps. The method 600 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.

[0175] Further, the order in which the method 600 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0176] The steps discussed below are performed by the network entity 300. All the modules of the network entity 300 are configured to perform the following steps:

[0177] At step 601, the method 600 includes generating by the network entity 300, from the UE 103, information including at least one Public Land Mobile Network (PLMN) identity detected as available PLMN identity in a network coverage area of the user equipment (UE) entity 200.

[0178] At step 603, the method 600 includes transmitting, by the network entity 300, to the UE entity 200, the generated information to perform network selection based on at least one available PLMN identity.

[0179] Fig. 7 illustrates a block diagram of an exemplary computer system 700 for implementing embodiments consistent with the present disclosure. The computer system 700 may be, without limitation implemented to, UE entity 103 and network entity 105. The computer system 700 may include a central processing unit ("CPU" or "processor") 701. The processor 701 may include at least one data processor for executing processes. The processor 701 may include specialized processing units such as, integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc.

[0180] The processor 701 may be disposed in communication with one or more input / output (I / O) devices 708 and 709 via I / O interface 707. The I / O interface 707 may employ communication protocols / methods such as, without limitation, audio, analog, digital, monaural, RCA, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS / 2, BNC, coaxial, component, composite, digital visual interface (DVI), high-definition multimedia interface (HDMI), RF antennas, S-Video, VGA, IEEE 802.n / b / g / n / x, Bluetooth, cellular (e.g., code-division multiple access (CDMA), high-speed packet access (HSPA+), global system for mobile communications (GSM), long-term evolution (LTE), WiMax, or the like), etc.

[0181] Using the I / O interface 707, the computer system 700 may communicate with one or more I / O devices 708 and 709. For example, the input devices 708 may be an camera device, antenna, keyboard, mouse, joystick, (infrared) remote control, card reader, fax machine, dongle, biometric reader, microphone, touch screen, touchpad, trackball, stylus, scanner, storage device, transceiver, video device / source, etc. The output devices 709 may be a printer, fax machine, video display (e.g., cathode ray tube (CRT), liquid crystal display (LCD), light-emitting diode (LED), plasma, Plasma display panel (PDP), Organic light-emitting diode display (OLED) or the like), audio speaker, etc.

[0182] In some embodiments, the processor 501 may be disposed in communication with external elements such as external computer systems, servers, network elements. The network interface 710 may employ connection protocols including, without limitation, direct connect, Ethernet (e.g., twisted pair 10 / 100 / 1000 Base T), transmission control protocol / internet protocol (TCP / IP), token ring, IEEE 802.11a / b / g / n / x, etc.

[0183] In some embodiments, the processor 701 may be disposed in communication with a memory 503 (e.g., RAM, ROM, etc.) via a storage interface 702. The storage interface 702 may connect to memory 703 including, without limitation, memory drives, removable disc drives, etc., employing connection protocols such as, serial advanced technology attachment (SATA), Integrated Drive Electronics (IDE), IEEE-1394, Universal Serial Bus (USB), fibre channel, Small Computer Systems Interface (SCSI), etc. The memory drives may further include a drum, magnetic disc drive, magneto-optical drive, optical drive, Redundant Array of Independent Discs (RAID), solid-state memory devices, solid-state drives, etc.

[0184] The memory 703 may store a collection of program or database components, including, without limitation, user interface 704, an operating system 705, a web browser 706 etc. In some embodiments, the computer system 700 may store user / application data, such as, the data, variables, records, etc., as described in this disclosure. Such databases may be implemented as fault-tolerant, relational, scalable, secure databases such as Oracle ® or Sybase®.

[0185] The operating system 705 may facilitate resource management and operation of the computer system 700. Examples of operating systems include, without limitation, APPLE MACINTOSH® OS X, UNIX®, UNIX-like system distributions (E.G., BERKELEY SOFTWARE DISTRIBUTIONTM(BSD), FREEBSDTM, NETBSDTM, OPENBSDTM, etc.), LINUX DISTRIBUTIONSTM(E.G., RED HATTM, UBUNTUTM, KUBUNTUTM, etc.), IBMTMOS / 2, MICROSOFTTMWINDOWSTM(XPTM, VISTATM / 7 / 8, 10 etc.), APPLE® IOSTM, GOOGLE® ANDROIDTM, BLACKBERRY® OS, or the like.

[0186] In some embodiments, the computer system 700 may implement the web browser 506 stored program components. The web browser 706 may be a hypertext viewing application, such as MICROSOFT®INTERNET EXPLORER®, GOOGLETMCHROMETM, MOZILLA®FIREFOX®, APPLE®SAFARI®, etc. Secure web browsing may be provided using Secure Hypertext Transport Protocol (HTTPS), Secure Sockets Layer (SSL), Transport Layer Security (TLS), etc. Web browsers 506 may utilize facilities such as AJAX, DHTML, ADOBE®FLASH®, JAVASCRIPT®, JAVA®, Application Programming Interfaces (APIs), etc. In some embodiments, the computer system 700 may implement a mail server stored program component. The mail server may be an Internet mail server such as Microsoft Exchange, or the like. The mail server may utilize facilities such as Active Server Pages (ASP), ACTIVEX®, ANSI®C++ / C#, MICROSOFT®, .NET, CGI SCRIPTS, JAVA®, JAVASCRIPT®, PERL®, PHP, PYTHON®, WEBOBJECTS®, etc. The mail server may utilize communication protocols such as Internet Message Access Protocol (IMAP), Messaging Application Programming Interface (MAPI), MICROSOFT®exchange, Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), or the like. In some embodiments, the computer system 700 may implement a mail client stored program component. The mail client may be a mail viewing application, such as APPLE®MAIL, MICROSOFT®ENTOURAGE®, MICROSOFT®OUTLOOK®, MOZILLA®THUNDERBIRD®, etc.

[0187] While various aspects and embodiments have been disclosed herein, other aspects and embodiments may be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

1.A method performed by a terminal in a wireless communication system, the method comprising:receiving, from a base station, steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity;identifying a PLMN identity included in a forbidden PLMN list from the at least one PLMN identity;deleting the PLMN identity from the forbidden PLMN list;resetting a PLMN-specific attempt counter associated with the PLMN identity; andperforming network selection based on the at least one PLMN identity.2.The method of claim 1, wherein the forbidden PLMN list includes at least one of a forbidden PLMN list, an extension of the forbidden PLMN list, or a forbidden PLMN list for general packet radio service (GPRS) service list.3.The method of claim 1, wherein the SOR information is included in a non access stratum (NAS) message or a refresh command.4.The method of claim 1, wherein deleting the PLMN identity from the forbidden PLMN list further comprises:replacing highest-priority PLMN identities present in an operator controlled PLMN selector list stored in the terminal with the at least one PLMN identity,wherein in case that a message with cause value "PLMN not allowed" or "requested service option not authorized in this PLMN" or "serving network not authorized" is received, the terminal is not configured to use timer T3245, and the message is not integrity-protected, the PLMN-specific attempt counter is maintained.5.A method performed by a network entity in a wireless communication system, the method comprising:generating steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity; andtransmitting, to a terminal, the SOR information to perform network selection based on the at least one PLMN identity,wherein a PLMN identity of the at least one PLMN identity that is included in a forbidden PLMN list is deleted from the forbidden PLMN list, andwherein a PLMN-specific attempt counter associated with the PLMN identity is reset.6.The method of claim 5, wherein the SOR information is included in a non access stratum (NAS) message or a refresh command.7.The method of claim 5, wherein in case that a message with cause value "PLMN not allowed" or "requested service option not authorized in this PLMN" or "serving network not authorized" is transmitted, the terminal is not configured to use timer T3245, and the message is not integrity-protected, the PLMN-specific attempt counter is maintained.8.A terminal in a wireless communication system, the terminal comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the terminal to:receive steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity,identify a PLMN identity included in a forbidden PLMN list from the at least one PLMN identity,delete the PLMN identity from the forbidden PLMN list,reset a PLMN-specific attempt counter associated with the PLMN identity, andperform network selection based on the at least one PLMN identity.9.The terminal of claim 8, wherein the forbidden PLMN list includes at least one of a forbidden PLMN list, an extension of the forbidden PLMN list, or a forbidden PLMN list for general packet radio service (GPRS) service list.10.The terminal of claim 8, wherein the SOR information is included in a non access stratum (NAS) message or a refresh command.11.The terminal of claim 8, wherein the instructions executable by the at least one processor individually or in any combination further cause the terminal to replace highest-priority PLMN identities present in an operator controlled PLMN selector list stored in the terminal with the at least one PLMN identity.12.The terminal of claim 8, wherein in case that a message with cause value "PLMN not allowed" or "requested service option not authorized in this PLMN" or "serving network not authorized" is received, the terminal is not configured to use timer T3245, and the message is not integrity-protected, the PLMN-specific attempt counter is maintained.13.A network entity in a wireless communication system, the network entity comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the network entity to:generate steering of roaming (SOR) information including at least one public land mobile network (PLMN) identity, andtransmit, to a terminal, the SOR information to perform network selection based on the at least one PLMN identity,wherein a PLMN identity of the at least one PLMN identity that is included in a forbidden PLMN list is deleted from the forbidden PLMN list, andwherein a PLMN-specific attempt counter associated with the PLMN identity is reset.14.The network entity of claim 13, wherein the SOR information is included in a non access stratum (NAS) message or a refresh command.15.The network entity of claim 13, wherein in case that a message with cause value "PLMN not allowed" or "requested service option not authorized in this PLMN" or "serving network not authorized" is transmitted, the terminal is not configured to use timer T3245, and the message is not integrity-protected, the PLMN-specific attempt counter is maintained.

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