Steering of roaming enhancement for reject message

Abstract

Systems, methods, apparatuses, and computer program products for enhancing steering of roaming rejection messages. One method may include detecting at least one public land mobile network currently available to the apparatus; generating a list comprising the detected at least one public land mobile network; and transmitting the  list comprising the detected at least one public land mobile network. The public land mobile network may be a visited public land mobile network VPLMN. The messages may be transmitted to a home public land mobile network. HPLMN.

Description

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[0001] Some example embodiments described herein may generally relate to mobile or wireless telecommunication systems, such as 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), 5th generation (5G) radio access technology (RAT), new radio (NR) access technology, 6th generation (6G), and / or other communications systems. For example, certain example embodiments may relate to systems and / or methods for enhancing steering of roaming rejection messages. BACKGROUND

[0002] Examples of mobile or wireless telecommunication technology and systems may include radio frequency (RF) 5G RAT, the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), LTE Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), LTE-A Pro, NR access technology, and / or MulteFire Alliance. 5G wireless systems refer to the next generation (NG) of radio systems and network architecture. A 5G system is typically built on a 5G NR, but a 5G (or NG) network may also be built on E-UTRA radio. It is expected that NR can support service categories, such as enhanced mobile broadband (eMBB), ultra-reliable low-latency-communication (URLLC), and massive machine-type communication (mMTC). NR is expected to deliver extreme broadband, ultra-robust, low-latency connectivity, and massive networking to support the Internet of Things (loT). The next generation radio access network (NG-RAN) represents the radio access network (RAN) for 5G, which may provide radio access for NR, LTE, and LTE-A. It is noted that the nodes in 5G providing radio access functionality to a user equipment (e.g., similar to the Node B in UTRAN or the Evolved Node B (eNB) in LTE) may be referred to as next-generation Node B (gNB) when built on NR radio, and may be referred to as nextgeneration eNB (NG-eNB) when built on E-UTRA radio. SUMMARY

[0003] In accordance with some example embodiments, a method may include detecting, by a UE, at least one PLMN currently available to the UE. The method may further include generating, by the UE, a list comprising the detected at least one PLMN. The method may further include transmitting, by the UE, the list comprising the detected at least one PLMN.

[0004] In accordance with certain example embodiments, an apparatus may include means for detecting at least one PLMN currently available to the apparatus. The apparatus may further include means for generating a list comprising the detected at least one PLMN. The apparatus may further include means for transmitting the list comprising the detected at least one PLMN.

[0005] In accordance with various example embodiments, a non-transitory computer readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least a method. The method may include detecting at least one PLMN currently available to the apparatus. The method may further include generating a list comprising the detected at least one PLMN. The method may further include transmitting the list comprising the detected at least one PLMN.

[0006] In accordance with some example embodiments, a computer program product may perform a method. The method may include detecting at least one PLMN currently available to a UE. The method may further include generating a list comprising the detected at least one PLMN. The method may further include transmitting the list comprising the detected at least one PLMN.

[0007] In accordance with certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to detect at least one PLMN currently available to the apparatus. The at least one memory and instructions, when executed by the at least one processor, may further cause the apparatus at least to generate a list comprising the detected at least one PLMN. The at least one memory and instructions, when executed by the at least one processor, may further cause the apparatus at least to transmit the list comprising the detected at least one PLMN.

[0008] In accordance with various example embodiments, an apparatus may include detecting circuitry configured to perform detecting at least one PLMN currently available to the apparatus. The apparatus may further include generating circuitry configured to perform generating a list comprising the detected at least one PLMN. The apparatus may further include transmitting circuitry configured to perform transmitting the list comprising the detected at least one PLMN.

[0009] In accordance with some example embodiments, a method may include receiving, by a network entity, a list comprising at least one detected PLMN. The method may further include determining, by the network entity, that a preferred VPLMN is currently available for a UE.

[0010] In accordance with certain example embodiments, an apparatus may include means for receiving a list comprising at least one detected PLMN. The apparatus may further include means for determining that a preferred VPLMN is currently available for a UE.

[0011] In accordance with various example embodiments, a non-transitory computer readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least a method. The method may include receiving a list comprising at least one detected PLMN. The method may further include determining that a preferred VPLMN is currently available for a UE.

[0012] In accordance with some example embodiments, a computer program product may perform a method. The method may include receiving a list comprising at least one detected PLMN. The method may further include determining that a preferred VPLMN is currently available for a UE.

[0013] In accordance with certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to receive a list comprising at 1 east one detected PLMN. The at least one memory and instructions, when executed by the at least one processor, may further cause the apparatus at least to determine that a preferred VPLMN is currently available for a UE.

[0014] In accordance with various example embodiments, an apparatus may include receiving circuitry configured to perform receiving a list comprising at least one detected PLMN. The apparatus may further include determining circuitry configured to perform determining that a preferred VPLMN is currently available for a UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For a proper understanding of example embodiments described herein, reference should be made to the accompanying drawings, wherein:

[0016] FIG. 1 illustrates an example of a signaling diagram according to certain example embodiments;

[0017] FIG. 2 illustrates an example of another signaling diagram according to some example embodiments;

[0018] FIG. 3 illustrates an example of a flow diagram of a method according to various example embodiments.

[0019] FIG. 4 illustrates an example of another flow diagram of a method according to certain example embodiments;

[0020] FIG. 5 illustrates an example of various network devices according to some example embodiments; and

[0021] FIG. 6 illustrates an example of a 5G network and system architecture according to certain example embodiments. DETAILED DESCRIPTION

[0022] It will be readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of some example embodiments of systems, methods, apparatuses, and computer program products for enhancing steering of roaming rejection messages is not intended to limit the scope of certain example embodiments, but is instead representative of selected example embodiments.

[0023] In general, steering of roaming (SoR) allows, enables, and / or otherwise facilitates a home public land mobile network (HPLMN) to steer a UE which is currently roaming in a visited PL MN (VPLMN) to other VPLMNs that are preferred by the HPLMN. In certain cellular technologies (e.g., 2G, 3G, 4G), once a UE has registered with any VPLMN (z. e., when the UE has no information, randomly selected by the UE), SoR can be implemented by the HPLMN sending information indicating the preferred VPLMNs to the UE, and the UE would then if indicated by the HPLMN - de-register from the current (not-preferred) VPLMN and register with the preferred VPLMN. This may be done whenever possible, such as when no important session is running and only when the respective VPLMN is available. Under 3GPP 5G, the HPLMN may be able to support mechanisms allowing, enabling, and / or otherwise facilitating the HPLMN to receive a notification reply from the trusted application server indicating specific actions to the HPLMN (e.g., reject UE registration (with a specific cause)), thereby triggering a SoR command. Thus, with SoR, during the registration procedure, it may be possible that, when the UE tries to register with a not-preferred VPLMN, the HPLMN may reject (e.g., directly reject) the registration request during the registration procedure, and indicate the VPLMNs to the UE that the UE shall register with. Then, a UE may be prevented (e.g., steered away) from registering with a non-preferred VPLMN, and may instead register (e.g., directly register) with a preferred VPLMN.

[0024] Roaming services may include roaming value added services (RVAS) that may be included in various cellular technologies (e.g., Global System for Mobile Communications (GSMA), 3GPP). RVAS may be provided by a public land mobile network (PLMN) and / or outsourced to a fully trusted entity by the PLMN that can serve as an RVAS provider, internetwork packet exchange (IPX) provider, and / or roaming hubbing provider. RVAS may be consumed by roaming subscribers and / or by the home network of the roaming subscribers. As a result, the PLMN may allow, enable, and / or otherwise facilitate RVAS for 5GS roaming.

[0025] PLMN may allow, enable, and / or otherwise facilitate RVAS in 5GS for functions including welcome short message service (SMS), steering of roaming (SoR) during the registration procedure, and / or international mobile subscriber identity (IMSI)-based routing to a particular core network (e.g., in a different country). These services may be provided using various techniques in 2G / 3G / 4G networks, but may include some disadvantages in 5GS deployments that prevent external third-party providers to offer the same RVAS over 5G. In addition, existing 3GPP service requirements and functionalities (e.g., related to control plane (CP)-SoR, traffic routing) may not support some particular RVAS use cases.

[0026] The 5G system may support mechanisms allowing, enabling, and / or otherwise facilitating the HPLMN to provide a notification, including subscription and equipment identifiers, to a trusted application server when a UE attempts to register in a VPLMN, and / or receive a notification reply from the trusted application server indicating specific actions to the HPLMN (e.g., reject UE registration (with a specific cause), trigger a SoR command).

[0027] Some challenges may persist with certain techniques. For example, a UE may operate in a country with multiple VPLMNs, such as VPLMN 1, VPLMN2, and VPLMN3. The SoR policy configured in the SoR AF of HPLMN may define VPLMN2 as the preferred VPLMN. While operating in a UE remote location with limited coverage, the UE may only be covered by one operator in that country (e.g., VPLMN 1). When the UE connects to VPLMN 1, the UDM / SoR may determine that VPLMN 1 is not a preferred VPLMN. Therefore, the UDM may reject the registration request via NAS REJECT, which may be based on an indication from an application / SoR server. However, since there is only one VPLMN available (e.g., VPLMN 1), the UE may have no alternative VPLMN available, causing the UE to not connect to VPLMN 1 for a period of time (e.g,, auto connect); otherwise, the UE may be forced to connect to the same VPLMN 1. Since the HPLMN is unaware of the radio condition and available VPLMNs in that area, this process may continue to be repeated, wherein the UE request is rejected, and UE services are affected.

[0028] Certain example embodiments described herein may have various benefits and / or advantages to at least in part address disadvantages described above and / or those otherwise recognized by the skilled person in the relevant art(s). For example, certain example embodiments may improve steering of roaming rejection messages. This may be accomplished by preventing a visiting PLMN (e.g., SN) from modifying secured packet contents since it is integrity protected. In addition, the UE may be barred from attaching to a non-preferred VPLMN since SoR data may be received in a registration rejection message; thus, the UE may be attached (e.g., directly attached) to a preferred VPLMN. Otherwise, SoR data would be transmitted only upon successful registration when the UE attaches to a first VPLMN, followed by the network determining that a second VPLMN is actually preferred and directing (e.g., requiring) the UE to change to the second VPLMN via SoR data; thus, various example embodiments avoid such a significant waste of limited network resources. Acordingly, certain example embodiments discussed herein are directed to improvements in computer-related technology.

[0029] In certain example embodiments, as part of an initial registration request, the UE may include a list of VPLMNs that may be available to the UE in that area. The SoR AF may determine the SOR based on the initial registration request (e.g., it may not reject the registration). The available VPLMN list may be encrypted and / or integrity protected. In case only one VPLMN is currently available to the UE, the UE may, instead or additionally, include an indication that only one VPLMN is available to the UE.

[0030] In some example embodiments, once the UE is rejected by the HPLMN, the UE may connect to the same VPLMN again since no other VPLMNs are available. The UE may include a protected indication to the core network that only VPLMN 1 is available. The UDM and / or SoR-AF may use this indication to allow, enable, and / or otherwise facililtate the registration in VPLMN 1. If the AMF drops the encrypted packet, and the UE does not receive an acknowledgement (ACK), the UE may deregister and add the VPLMN into a blacklist.

[0031] FIG. 1 illustrates an example of a signaling diagram 100. UE 120 may be similar to UE 520, and AMF 130, AUSF 140, UDM 150, and SoR AF 160 may be similar to NE 510, as illustrated in FIG. 5, according to certain example embodiments.

[0032] At operation 101, UE 120 may be configured with policy parameters that may indicate that UE 120 is to (e.g., needs to) transmit an encrypted available VPLMN list and / or indicate when UE 120 attached to the VPLMNs. UE 120, in some example embodiments, may be statically configured with these policy parameters. Alternatively, an HPLMN (not shown) may dynamically update UE 120, such as when UE 120 attaches to the HPLMN; following attachment, the HPLMN may transmit the policy parameters to UE 120.

[0033] Alternatively to operation 101, at operation 102, UE 120 may operate in an area covered only by a first VPLMN (e.g., VPLMN1).

[0034] At operation 103, UE 120 may generate an integrity protect (e.g., message authentication code - integrity ((MAC-I)), for example, a secure packet including an available VPLMN list or an indication of only one available VPLMN.

[0035] In certain example embodiments, if UE 120 supports VPLMNs and / or is configured to report available VPLMN information at registration, UE 120 may encrypt the available VPLMNs (e.g, VPLMN 1, VPLMN2, ...). Alternatively, if only one VPLMN is available, UE 120 may transmit an indication of the single VPLMN available to AMF 130 as part of a NAS registration.

[0036] At operation 104, UE 120 may transmit a registration request (e.g., Nudm UECM Registration request) to AMF 130, which may forward the request to UDM 150 at operation 105. The registration request may include the secure packet received from UE 120. Alternatively, AMF 130 may transmit the secure packet in an authentication message.

[0037] At operation 106, if UDM 150 validates the secure packet, UDM 150 may determine whether to transmit the SoR AF 160 packet or not based on available VPLMNs in the location / coverage of UE 120. For example, if only one VPLMN is available at the current location of UE 120, UDM 150 may not transmit the SoR AF 160 packet with other priority VPLMNs.

[0038] Additionally or alternatively to operation 106, at operation 107, UDM 150 may provide the available VPLMN information or an indication of a single VPLMN available to SoR AF 160. SoR AF 160 may determine to instruct UDM 150 to allow or reject the registration based on the provided information.

[0039] At operation 108, UDM 150 may transmit an encrypted ACK to AMF 130, which may forward the encrypted ACK to UE 120 at operation 109.

[0040] At operation 110, based upon the ACK received from AMF 130, UE 120 may determine that UDM 150 and / or SOR AF 160 has not received the message from UE 120. If AMF 130 has tempered the UE 120 packet at operations 104-105, or if UDM 150 has not received the packet of UE 120, UE 120 may not receive this ACK. UE 120 may then mark the current PLMN as untrusted and may deregister. Alternatively, UE 120 may designate the current PLMN as low priority.

[0041] Once more VPLMNs are available, UE 120 may transmit the encrypted updated available VPLMN list to UDM 150 and / or SoR AF 160.

[0042] FIG. 2 illustrates an example of a signaling diagram 200. UE 210 may be similar to UE 520, and AMF 220, AUSF 230, UDM 240, and SoR 250 may be similar to NE 510, as illustrated in FIG. 5, according to certain example embodiments.

[0043] Upon UE 210 being rejected by the network, and there being only one available VPLMN. UE 210 may perform the procedures described above in FIG. 1. In this case, since only one VPLMN is available, UE 210 may not send the available VPLMN list; rather, UE 210 may transmit an indication that only one VPLMN is available in the area.

[0044] At operation 201, UE 210 may operate in a remote area that is covered by a single VPLMN (e.g., VPLMN 1).

[0045] At operation 202, UE 210 may transmit a registration request indicating the single VPLMN (e.g., VPLMN 1) to AMF 220, which may forward the registration request to UDM 240 at operation 203.

[0046] At operation 204, SoR AF 250 may determine that the single VPLMN (e.g., VPLMN 1) is not a preferred VPLMN, and request UDM 240 to reject the request.

[0047] At operation 205, UDM 204 may transmit a rejection indication to AMF 220, which may forward the rejection indication to UE 210 at operation 206, indicating that the single VPLMN (e.g., VPLMN 1) is not a preferred VPLMN.

[0048] At operation 207, UE 210 may repeat the registration with an available VLPLMN, as discussed above in FIG. 1.

[0049] FIG. 3 illustrates an example of a flow diagram of a method 300 that may be performed by a UE, such as UE 520 illustrated in FIG. 5, according to various example embodiments.

[0050] At step 301, the method may include detecting at least one PLMN currently available to the UE. The at least one PLMN may include at least one VPLMN.

[0051] At step 302, the method may include generating a list including the detected at least one PLMN. In certain example embodiments, the method may also include adding the list to a registration request message.

[0052] At step 303, the method may further include transmitting the list including the detected at least one PLMN, such as to at least one HPLMN. For example, the method may include transmitting the registration request message containing the list.

[0053] In some example embodiments, the method may include selecting a PLMN from the detected at least one PLMN, and transmitting the list via the selected PLMN.

[0054] In various example embodiments, the method may include encrypting the list and / or integrity protecting the list.

[0055] In certain example embodiments, the method may also include receiving an ACK, and validating the ACK. The ACK may be at least one of encrypted and integrity protected. The ACK may be validated by at least one of checking integrity protection or decrypting the ACK.

[0056] In some example embodiments, the method may further include marking the selected PLMN as low priority upon unsuccessful validation or failing to receive the ACK, and deregistering from the selected PLMN upon unsuccessful validation or failing to receiving the ACK.

[0057] FIG. 4 illustrates an example of a flow diagram of a method 400 that may be performed by a NE, such as NE 510 illustrated in FIG. 5, according to various example embodiments.

[0058] At step 401, the method may include receiving a list including at least one detected PLMN. The method may further include receiving a registration request message including the list. In certain example embodiments, the method may further include validating the list by checking integrity protection and decrypting the list.

[0059] At step 402, the method may further include determining that a preferred VPLMN is currently available for a UE.

[0060] In certain example embodiments, the method may further include determining whether to allow or reject the registration request message, and transmitting a registration accept or reject message based upon the determination. In response to determining to allow the registration request message, the method may include transmitting a registration accept message. However, in response to determining to reject the registration request message, the method may include determining at least one preferred VPLMN from the indication of PLMNs, determining whether any of the VPLMNs of a list of VPLMNs currently available to the UE are on a list of VPLMNs preferred for the UE, and transmitting a registration reject message to the UE indicating one or more VPLMNs that are on the list of VPLMNs preferred for the UE and on the list of VPLMNs currently available to the UE.

[0061] In some example embodiments, the method may further include transmitting an encrypted and integrity protected ACK to the UE via an AMF.

[0062] FIG. 5 illustrates an example of a system according to certain example embodiments. In one example embodiment, a system may include multiple devices, such as, for example, NE 510 and / or UE 520.

[0063] NE 510 may be include one or more of a base station (c.^., 3G UNITS NodeB, 4G LTE Evolved NodeB, or 5G NR Next Generation NodeB), a serving gateway, a server, and / or any other access node or combination thereof.

[0064] NE 510 may further include at least one gNB-centralized unit (CU), which may be associated with at least one gNB-distributed unit (DU). The at least one gNB-CU and the at least one gNB-DU may be in communication via at least one Fl interface, at least one Xn-C interface, and / or at least one NG interface via a 5th generation core (5GC).

[0065] UE 520 may include one or more of a mobile device, such as a mobile phone, smart phone, personal digital assistant (PDA), tablet, or portable media player, digital camera, pocket video camera, video game console, navigation unit, such as a global positioning system (GPS) device, desktop or laptop computer, single-location device, such as a sensor or smart meter, or any combination thereof. Furthermore, NE 510 and / or UE 520 may be one or more of a citizens broadband radio service device (CBSD).

[0066] NE 510 and / or UE 520 may include at least one processor, respectively indicated as 511 and 521. Processors 511 and 521 may include any computational or data processing device, such as a central processing unit (CPU), application specific integrated circuit (ASIC), or comparable device. The processors may be implemented as a single controller, or a plurality of controllers or processors.

[0067] At least one memory may be provided in one or more of the devices, as indicated at 512 and 522. The memory may be fixed or removable. The memory may include computer program instructions or computer code contained therein. Memories 512 and 522 may independently be any suitable storage device, such as a non-transitory computer-readable medium. The term “non-transitory,” as used herein, may correspond to a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g, random access memory (RAM) vs. read-only memory (ROM)). A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memories may be combined on a single integrated circuit as the processor, or may be separate from the one or more processors. Furthermore, the computer program instructions stored in the memory, and which may be processed by the processors, may be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language.

[0068] Processors 511 and 521, memories 512 and 522, and any subset thereof, may be configured to provide means corresponding to the various blocks of FIGs. 1-4. Although not shown, the devices may also include positioning hardware, such as GPS or micro electrical mechanical system (MEMS) hardware, which may be used to determine a location of the device. Other sensors are also permitted, and may be configured to determine location, elevation, velocity, orientation, and so forth, such as barometers, compasses, and the like.

[0069] As shown in FIG. 5, transceivers 513 and 523 may be included, and one or more devices may also include at least one antenna, respectively illustrated as 514 and 524. The device may have many antennas, such as an array of antennas configured for multiple input multiple output (MIMO) communications, or multiple antennas for multiple RATs. Other configurations of these devices, for example, may be implemented. Transceivers 513 and 523 may be a transmitter, a receiver, both a transmitter and a receiver, or a unit or device that may be configured both for transmission and reception.

[0070] The memory and the computer program instructions may be configured, with the processor for the particular device, to cause a hardware apparatus, such as UE, to perform any of the processes (or operations thereof) described above (i.e., FIGs. 1-4). Therefore, in certain example embodiments, a non-transitory computer-readable medium may be encoded with computer instructions that, when executed in hardware, perform a process such as one of the processes described herein. Alternatively, certain example embodiments may be performed entirely in hardware.

[0071] In certain example embodiments, an apparatus may include circuitry configured to perform any of the processes or functions illustrated in FIGs. 1-4. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry), (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions), and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not utilized for operation. This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0072] FIG. 6 illustrates an example of a 5G network and system architecture according to certain example embodiments. Shown are multiple network functions that may be implemented as software operating as part of a network device or dedicated hardware, as a network device itself or dedicated hardware, or as a virtual function operating as a network device or dedicated hardware. The NE and UE illustrated in FIG. 6 may be similar to NE 510 and UE 520, respectively. The user plane function (UPF) may provide services such as intra-RAT and inter-RAT mobility, routing and forwarding of data packets, inspection of packets, user plane quality of service (QoS) processing, buffering of downlink packets, and / or triggering of downlink data notifications. The application function (AF) may primarily interface with the core network to facilitate application usage of traffic routing and interact with the policy framework.

[0073] According to certain example embodiments, processors 511 and 521, and memories 512 and 522, may be included in or may form a part of processing circuitry or control circuitry. In addition, in some example embodiments, transceivers 513 and 523 may be included in or may form a part of transceiving circuitry.

[0074] In some example embodiments, an apparatus (e.g, NE 510 and / or UE 520) may include means for performing a method, a process, or any of the variants discussed herein. Examples of the means may include one or more processors, memory, controllers, transmitters, receivers, and / or computer program code for causing the performance of the operations.

[0075] In various example embodiments, apparatus 510 may be controlled by memory 512 and processor 511 to detect at least one PLMN currently available to the apparatus; generate a list comprising the detected at least one PLMN; and transmit the list comprising the detected at least one PLMN.

[0076] Certain example embodiments may be directed to an apparatus that includes means for performing any of the methods described herein including, for example, means for detecting at least one PLMN currently available to the apparatus; means for generating a list comprising the detected at least one PLMN; and means for transmitting the list comprising the detected at least one PLMN.

[0077] In various example embodiments, apparatus 510 may be controlled by memory 512 and processor 511 to receive a list comprising at least one detected PLMN; and determine that a preferred VPLMN is currently available for a UE.

[0078] Certain example embodiments may be directed to an apparatus that includes means for performing any of the methods described herein including, for example, means for receiving a list comprising at least one detected PLMN; and means for determining that a preferred VPLMN is currently available for a user equipment.

[0079] The features, structures, or characteristics of the various example embodiments described throughout this specification may be combined in any suitable manner in one or more example embodiments. For example, the usage of the phrases “various embodiments,” “various example embodiment,” “certain embodiments,” “certain example embodiments,” “some embodiments,” “some example embodiments” or other similar language throughout this specification refers to the fact that particular feature(s), structure(s), or characteristic(s) described in connection with an embodiment or an example embodiment may be included in at least one example embodiment. Thus, appearances of the phrases “in various embodiments,” “in various example embodiments,” “in certain embodiments,” “in certain example embodiments,” “in some embodiments,” “in some example embodiments” or other similar language throughout this specification does not necessarily all refer to the same group of embodiments or example embodiments, and the described feature(s), structure(s), or characteristic(s) may be combined in any suitable manner in one or more example embodiments, whether or not such combination(s) are explicitly described.

[0080] Although certain example embodiments are described herein, by way of nonlimiting and illustrative example, and with reference to certain example architectures for communication systems operated by mobile network operators, technologies and standards, further example embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. For example, some example embodiments have been described in relation to a 5G communication system (5GS). It should be appreciated that other example embodiments may be provided in any other suitable communication system(s) (e.g., 6GS) or in any suitable combination with a 5GS.

[0081] It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments.

[0082] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0083] As used herein, the expression “and / or” also includes any and all combinations of the listed terms, including at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0084] As used herein, the term “or” refers to a non-exclusive “or” unless otherwise indicated (e.g., use of “or else” or “or in the alternative”).

[0085] As used herein, unless stated explicitly, performing a respective feature, step, or functionality “in response to A” does not indicate that the respective feature, step, or functionality is performed immediately after “A” occurs as one or more unstated and intervening features, steps, or functionalities may be performed (at least in part) between an occurrence of the respective feature, step, or function and “A”. Analogously, performing a respective feature, step, or functionality “based on A” does not indicate that the respective feature, step, or functionality is performed solely based on “A” as the respective feature, step, or functionality may be further based on one or more unstated features, steps, or functionalities in addition to “A”.

[0086] Additionally, if desired, the different functions or procedures discussed above may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the described functions or procedures may be optional or may be combined. As such, the description above should be considered as illustrative of the principles and teachings of certain example embodiments, and not in limitation thereof.

[0087] One having ordinary skill in the art will readily understand that the example embodiments described herein may be practiced with procedures in a different order, and / or with hardware elements in configurations which are different than those which are disclosed. Therefore, although some embodiments have been described based upon these example embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the example embodiments.

[0088] Partial Glossary

[0089] 3GPP 3rd Generation Partnership Project

[0090] 5G 5th Generation

[0091] 5GC 5th Generation Core 5

[0092] 5GS 5th Generation System

[0093] 6G 6th Generation

[0094] ACK Acknowledgement

[0095] AF Application Function

[0096] AKA Authentication and Key Agreement io

[0097] AMF Access and Mobility Management Function

[0098] API Application Programming Interface

[0099] ASIC Application Specific Integrated Circuit

[0100] AUSF Authentication Server Function

[0101] CBSD Citizens Broadband Radio Service Device 15

[0102] CN Core Network

[0103] CP Control Plane

[0104] CPU Central Processing Unit

[0105] CU Centralized Unit

[0106] DU Distributed Unit 20

[0107] eMBB Enhanced Mobile Broadband

[0108] eNB Evolved Node B

[0109] gNB Next Generation Node B

[0110] GPS Global Positioning System

[0111] GSMA Global System for Mobile Communications 25

[0112] HDD Hard Disk Drive

[0113] HPLMN Home Public Land Mobile Network

[0114] IMSI International Mobile Subscriber Identity

[0115] loT Internet of Things

[0116] IPX Internetwork Packet Exchange

[0117] LTE

[0118] LTE-A Long-Term Evolution Long-Term Evolution Advanced

[0119] ME

[0120] MEMS Mobile Equipment Micro Electrical Mechanical System 5

[0121] MIMO

[0122] mMTC Multiple Input Multiple Output Massive Machine Type Communication

[0123] NE Network Entity

[0124] NG

[0125] NG-eNB Next Generation Next Generation Evolved Node B io

[0126] NG-RAN Next Generation Radio Access Network

[0127] NR New Radio

[0128] PDA Personal Digital Assistance

[0129] PLMN

[0130] QoS Public Land Mobile Network Quality of Service 15

[0131] RAM

[0132] RAN Random Access Memory Radio Access Network

[0133] RAT Radio Access Technology

[0134] RF

[0135] ROM 20

[0136] RVAS

[0137] SEAF Radio Frequency Read-Only Memory Roaming Value Added Services Security Anchor Functionality

[0138] SMS

[0139] SOR Short Message Service Steering of Roaming

[0140] UDM 25

[0141] UE Unified Data Management User Equipment

[0142] UMTS Universal Mobile Telecommunications System

[0143] UPF

[0144] URLLC

[0145] USIM User Plane Function Ultra-Reliable and Low-Latency Communication Universal Subscriber Identity Module [0146JUTRAN Universal Mobile Telecommunications System Terrestrial Radio Access Network

[0147] VPLMN Visited Public Land Mobile Network

Claims

1. An apparatus comprising:means for detecting at least one public land mobile network currently available to the appar atus;means for generating a list comprising the detected at least one public land mobile network; andmeans for transmitting the list comprising the detected at least one public land mobile network.

2. The apparatus of claim 1, further comprising:means for adding the list to a registration request message, whereinthe means for transmitting the list further comprises means for transmitting the registration request message containing the list.

3. The apparatus of claim 1 or 2, wherein the means for transmitting the list further comprises means for transmitting the list to at least one home public land mobile network.

4. The apparatus of any of claims 1 to 3, further comprising:means for selecting a public land mobile network from the detected at least one public land mobile network, whereinthe means for transmitting the list further comprises means for transmitting the list via the selected public land mobile network.

5. The apparatus of any of claims 1 to 4, wherein the at least one public land mobile network comprises at least one visited public land mobile network.

6. The apparatus of any of claims 1 to 5, further comprising at least one of:means for encrypting the list; ormeans for integrity protecting the list.

7. The apparatus of any of claims 1 to 6, further comprising:means for receiving an acknowledgement; andmeans for validating the acknowledgement.

8. The apparatus of claim 7, wherein the acknowledgement is at least one of encrypted and integrity protected.

9. The apparatus of claim 8, wherein the means for validating the acknowledgement further comprises means for validating the acknowledgement by at least one of checking integrity protection or decrypting the acknowledgement.

10. The apparatus of any of claims 7 to 9, further comprising at least one of:means for marking the selected public land mobile network as low priority upon unsuccessful validation or failing to receive the acknowledgement; ormeans for deregistering from the selected public land mobile network upon unsuccessful validation or failing to receiving the acknowledgement.

11. An apparatus comprising:means for receiving a list comprising at least one detected public land mobile network; andmeans for determining that a preferred visited public land mobile network is currently available for a user equipment.

12. The apparatus of claim 11, wherein the means for receiving further comprises:means for receiving a registration request message containing the list.

13. The apparatus of claim 11 or 12, further comprising:means for validating the list by checking integrity protection and decrypting the list.

14. The apparatus of any of claims 11 to 13, further comprising:means for determining whether to allow or reject the registration request message.

15. The apparatus of any of claims 11 to 14, further comprising:means for transmitting a registration accept or reject message based upon the determination.

16. The apparatus of any of claims 11 to 15, further comprising:means for, in response to determining to allow the registration request message, transmitting a registration accept message.

17. The apparatus of claim 14 or 15, further comprising, in response to determining to reject the registration request message:means for determining at least one preferred visited public land mobile network from the indication of public land mobile networks;means for determining whether any of the visited public land mobile networks of a list of visited public land mobile networks currently available to the user equipment are on a list of visited public land mobile networks preferred for the user equipment; andmeans for transmitting a registration reject message to the user equipment indicating one or more visited public land mobile networks that are on the list of visited public land mobile networks preferred for the user equipment and on the list of visited public land mobile networks currently available to the user equipment.

18. The apparatus of any of claim 11 or 17, further comprising:means for transmitting an acknowledgement to user equipment via an access and mobility management function, wherein the acknowledgement is at least one of5 encrypted or integrity protected.

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