Method and system for rerouting a registration request in a network

Abstract

The disclosure provides a system (108) and a method (500) for rerouting a registration request in a network A registration request from the UE (104) is received by the first network function (308). The first network function (308) extracts one or more parameters from the registration request. The first network function (308) determines a second network function (310) that is capable to serve the UE (104) based on the one or more extracted parameters. Upon determining, the first network function (308) reroutes the registration message towards the determined second network function (310). The method ensures improved service delivery by directing the UE registration to the second network function that is most suited to serve the UE (104).

Description

METHOD AND SYSTEM FOR REROUTING A REGISTRATION REQUEST IN A NETWORKRESERVATION OF RIGHTS

[0001] A portion of the disclosure of this patent document contains material, which is subject to intellectual property rights such as, but are not limited to, copyright, design, trademark, Integrated Circuit (IC) layout design, and / or trade dress protection, belonging to Jio Platforms Limited (JPL) or its affiliates (hereinafter referred as owner). The owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all rights whatsoever. All rights to such intellectual property are fully reserved by the owner.TECHNICAL FIELD

[0002] The present disclosure relates to a field of telecommunications network. In particular, the present disclosure relates to a method and a system for rerouting a registration request in a network.DEFINITION

[0003] As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used to indicate otherwise.

[0004] The term ‘gNodeB (gNB)’ as used herein in the specification refers to a component of telecommunications systems that connects user equipments (UEs) (like smartphones, tablets, Internet of Things (loT) devices) to a core network. The gNodeB primarily handles the wireless communication between the UEs and the network infrastructure, enabling data transmission and reception.

[0005] The term ‘Fifth Generation (5G) core network’ as used herein in the specification refers to a 5G telecommunications system that manages the control and data planes, providing connectivity, mobility management, and the delivery of services to the users. The 5G core network (5GC) is built on a cloud-native architecture, offering significant advancements over previous generations in terms of flexibility, scalability, and support for diverse applications such as loT, enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC).

[0006] The term ‘Access and Mobility Management Function (AMF)’ as used herein in the specification refers to a network function responsible for managing user registrations, mobility, and authentication within the network. For example,when a user moves between different network coverage areas, the AMF ensures seamless handover and session continuity while maintaining security protocols.

[0007] The term ‘Authentication Server Function (AUSF)’ as used herein in the specification refers to a network function responsible for user authentication in 5G networks. For example, when a user attempts to connect to the network, the AUSF verifies their identity by interacting with the Unified Data Management (UDM) and ensures secure access based on authentication protocols.

[0008] The term ‘Unified Data Management (UDM)’ as used herein in the specification refers to a network function that manages user subscription data, authentication, and access control. For example, when a user logs into the network, the UDM verifies their credentials and assigns appropriate service policies based on their subscription plan.

[0009] The term ‘Subscription Concealed Identifier (SUCI)’ as used herein in the specification refers to an encrypted version of a subscriber’s permanent identifier (SUPI), used to enhance privacy and security in network authentication. For example, when a user connects to the network, the SUCI is transmitted instead of the actual subscriber ID to prevent unauthorized interception of sensitive user information.

[0010] The term ‘Public Land Mobile Network (PLMN)’ as used herein in the specification refers to a mobile network operated by a telecommunications provider, identified by a unique combination of Mobile Country Code (MCC) and Mobile Network Code (MNC).

[0011] The term ‘Routing Indicator (RI)’ as used herein in the specification refers to a network parameter used to direct user requests to the appropriate network entity for processing. For example, in the 5G core network, the RI ensures that any request such as registration request from a user equipment (UE) are routed to the correct AUSF and UDM instance.

[0012] The term ‘Registration Request’ as used herein in the specification refers to a signaling message initiated by the UE to establish a connection with the network. The registration request is sent to a gNodeB (interchangeably referred to as RAN), which subsequently forwards it to the AMF. The registration request typically includes essential parameters such as the SUCI, PLMN identifier (ID), RI, and optionally, a Home Network Public Key identifier. These parameters enable the network to authenticate the UE, determine the appropriate network functions, and facilitate seamless integration of the UE into the network for accessing communication services.

[0013] The term ‘Non-Access Stratum (NAS)’ as used herein in the specification refers to a communication protocol between the UE and the AMF. NAS messages are responsible for authentication, registration, mobility management, and session management.

[0014] The term ‘N2 Interface’ as used herein in the specification refers to a reference interface between the AMF and the gNB in the 5G core network. The N2 is responsible for control plane signaling between the AMF and the gNB. The N2 interface supports UE registration, mobility management, and session establishment procedures.

[0015] The term ‘N8 Interface’ as used herein in the specification refers to a reference interface between the AMF and the AUSF and / or UDM instance in the 5G core network. The N8 interface is primarily used for authentication-related signaling, where the AUSF communicates with the UDM to retrieve and validate subscriber authentication data during the user authentication process.

[0016] The term ‘N12 Interface’ as used herein in the specification refers to a reference interface that connects the AMF and the AUSF. The N12 interface is used to facilitate the authentication procedure by allowing the AMF to request authentication services from the AUSF when the UE attempts to register in the network.

[0017] The term ‘AMF Set identifier (ID)’ as used herein in the specification refers to a unique identifier to group multiple AMFs into a logical set. The AMF set ID helps the gNodeB determine the appropriate AMF for handling the UE’s registration.

[0018] These definitions are in addition to those expressed in the art.BACKGROUND

[0019] The following description of related art is intended to provide background information pertaining to the field of the disclosure. This section may include certain aspects of the art that may be related to various features of the present disclosure. However, it should be appreciated that this section be used only to enhance the understanding of the reader with respect to the present disclosure, and not as admissions of prior art.

[0020] In telecommunications networks, the process of user registration is essential for establishing connectivity and enabling access to network services. When a user equipment (UE) attempts to register with the network, a registration request is initially sent by the UE to a Radio Access Network (RAN). Further, the RAN routes the registration request to an Access and Mobility Management Function (AMF).The AMF is responsible for selecting appropriate network functions, such as an Authentication Server Function (AUSF) and Unified Data Management (UDM), based on various parameters received in the registration request, such as a Subscription Concealed Identifier (SUCI), a Public Land Mobile Network (PLMN) identifier, a Routing Indicator (RI), and optionally, a Home Network Public Key identifier. The selected network functions ensure authentication and seamless integration of the UE into the network.

[0021] However, challenges arise in UE registration in scenarios where the PLMN consists of multiple segregated networks, where each network operates with its own set of network functions such as AMF, AUSF, and UDM. Due to the lack of interconnectivity between these segregated networks, if the UE initiates the registration request and it is routed to an incorrect AMF i.e., the AMF that does not correspond to the UE’s designated network, then authentication process cannot be completed. This occurs because the serving AMF lacks access to the appropriate AUSF and UDM instance that store and manage the UE’s subscriber profile, ultimately leading to registration failure.

[0022] Furthermore, when the UE attempts to retry the registration process, the registration request may again be routed to an incorrect AMF, leading to repeated registration failures. Since there is no interface between the segregated networks, the serving AMF cannot redirect the request to the appropriate or correct AUSF and UDM, instance thereby causing a service-impacting scenario.

[0023] At present, there are no established standards that provide a solution to address the issue of incorrect AMF selection in the network with multiple segregated infrastructures. As a result, repeated registration failures continue to be a service-impacting challenge, with no standardized approach available to mitigate this issue effectively.

[0024] There is, therefore, a need in the art to provide a method and a system that can mitigate the disadvantages of the prior art.SUMMARY OF THE DISCLOSURE

[0025] In an embodiment, a method for registration of at least one user equipment (UE) in a network is disclosed. The method comprises receiving, by a network function, at least one registration request from the at least one UE for registration. The at least one registration request comprises a routing indicator. The method further comprises determining, by the network function, a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE, based on the received routing indicator. Further, the method comprises rerouting, by the network function, the at least one registration request to a network node using a non-access stratum (NAS) message. The non-access stratum (NAS) messagecomprises the set identifier (Set ID) of the determined set of target network functions. Furthermore, the method comprises selecting, by the network node, a target network function instance from the determined set of target network functions based on the received set ID and rerouting, by the network node, the at least one registration request to the selected target network function instance for performing a registration procedure of the at least one UE in the network.

[0026] In an embodiment, the network function maintains a preconfigured mapping comprising a plurality of entries. In an embodiment, each entry comprises a mapping between a given routing indicator to a corresponding set of target network functions.

[0027] In one of the embodiments, determining the set of target network functions comprises retrieving, by the network function, the set ID of the determined set of target network functions from the pre-configured mapping.

[0028] In an embodiment, the selected target network function instance executes the registration procedure of the at least one UE with an authentication server function (AUSF), a unified data management function (UDM), and a policy control function (PCF).

[0029] In an embodiment, performing the registration procedure of the at least one UE includes retrieving, by the selected target network function instance, subscriber data associated with the at least one UE from the UDM, applying, by the selected target network function instance, policy control rules from the PCF for the at least one UE, updating, by the selected target network function instance, registration context information for the at least one UE in the network, and transmitting, by the selected target network function instance, a registration accept message to the at least one UE.

[0030] In an embodiment, the selected target network function instance performs an authentication and authorization procedure for the at least one UE. The authentication and authorization procedure comprises initiating, by the selected target network function instance, an authentication request to the at least one UE. The selected target network function instance receives an authentication response from the at least one UE, verifies the received authentication response from the AUSF, and authorizes the at least one UE upon successful authentication.

[0031] In one of the embodiments, the network node selects the target network function instance within the determined set of target network functions based on one or more selection criteria. The one or more selection criteria comprises load balancing across the one or more target network function instances, one or more priority rules defined for the one or more target network function instances, a geographical proximity of the one or more target network function instances to theat least one UE and the network node, and an availability status of the one or more target network function instances.

[0032] In an embodiment, another method for registering at least one user equipment (UE) in a network. The method comprises receiving, by an initial access and mobility management function (AMF), a registration request from the at least one UE. The registration request comprises a routing indicator. The method further comprises determining, by the initial AMF, whether the initial AMF is capable of serving the at least one UE based on the routing indicator. Further, the method comprises determining, by the initial AMF, a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE based on the received routing indicator, when the initial AMF determines that it is unable to serve the at least one UE. The initial AMF reroutes the registration request via a radio access network (RAN) to the target AMF set. The registration request includes a set identifier to the target AMF set. The method further includes selecting, by the RAN, a specific target AMF instance from the target AMF set based on the received set identifier and transmitting, by the RAN, the registration request to the selected target AMF instance. Furthermore, the method includes performing, by the selected target AMF instance, a registration procedure for the at least one UE.

[0033] In an embodiment, the method further comprises determining, by the initial AMF, based on local policy and subscription information of the at least one UE, whether to forward the registration message directly to the target AMF set. Based on the determination, the initial AMF performs one of, one or more additional registration operations, skipping the one or more additional registration operations, and forwarding the registration message directly to the target AMF set.

[0034] In an embodiment, the one or more additional registration operations comprise retrieving subscription information associated with the at least one UE from a unified data management (UDM), performing network slice selection via a network slice selection function (NSSF), querying a network repository function (NRF) to obtain addresses and capabilities of one or more candidate AMF instances within the target AMF set, and sending one or more registration status updates to an old AMF.

[0035] In one of the embodiments, the one or more additional registration operations are performed when a mobile network operator (MNO) offers a plurality of services within a single public land mobile network (PLMN) via one or more isolated core networks.

[0036] In an embodiment, a system for registration of at least one user equipment (UE) in a network is disclosed. The system comprises a processing engine configured to receive at least one registration request from the at least one UE forregistration. The at least one registration comprises a routing indicator. The processing engine determines a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE, based on the received routing indicator and reroutes the at least one registration request to a network node using a non-access stratum (NAS) message. The non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions. The network node selects a target network function instance from the determined set of target network functions based on the received set ID and reroutes the at least one registration request to the selected target network function instance for performing a registration procedure of the at least one UE in the network.

[0037] In an embodiment, the processing engine maintains a preconfigured mapping comprising a plurality of entries. In one of the embodiments, each entry comprises a mapping between a given routing indicator to a corresponding set of target network functions.

[0038] In an embodiment, the processing engine determines the set of target network functions by retrieving the set ID of the determined set of target network functions from the pre-configured mapping.

[0039] In an embodiment, the selected target network function instance is configured to retrieve subscriber data associated with the at least one UE from the UDM, apply policy control rules from the PCF for the at least one UE, update registration context information for the at least one UE in the network, and transmit a registration accept message to the at least one UE.

[0040] In another embodiment, a system for registering at least one user equipment (UE) in a network. The system comprises a processing engine configured to receive a registration request from the at least one UE. The registration request comprises a routing indicator. The processing engine is further configured to determine whether the initial AMF is capable of serving the at least one UE based on the routing indicator. The processing engine is further configured to determine a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE based on the received routing indicator, when the initial AMF determines that it is unable to serve the at least one UE. The processing engine is configured to reroute the registration request via a radio access network (RAN) to the target AMF set. The registration request includes a set identifier to the target AMF set. The RAN selects a specific target AMF instance from the target AMF set based on the received set identifier and transmits the registration request to the selected target AMF instance. The selected target AMF instance performs a registration procedure for the at least one UE.

[0041] In an embodiment, the processing engine is further configured to determine based on local policy and subscription information of the at least one UE, whether to forward the registration message directly to the target AMF set. Based on the determination, the processing engine is configured to perform one of one or more additional registration operations, skipping the one or more additional registration operations and forwarding the registration message directly to the target AMF set.

[0042] In an embodiment, to perform one or more additional registration operations, the processing engine is configured to retrieve subscription information associated with the at least one UE from a unified data management (UDM), perform network slice selection via a network slice selection function (NSSF), query a network repository function (NRF) to obtain addresses and capabilities of one or more candidate AMF instances within the target AMF set, and send one or more registration status updates to an old AMF.

[0043] In an embodiment, the processing engine performs one or more additional registration operations when a mobile network operator (MNO) offers a plurality of services within a single public land mobile network (PLMN) via one or more isolated core networks.

[0044] In an embodiment, a computer program product is disclosed which comprises a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (500) for rerouting the registration request in the network. The method receiving, by a network function, at least one registration request from the at least one UE for registration. The at least one registration request comprises a routing indicator. The method further comprising determining, by the network function, a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE, based on the received routing indicator. Further, the methos comprises rerouting, by the network function, the at least one registration request to a network node using a non-access stratum (NAS) message. The non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions. Furthermore, the method comprises selecting, by the network node, a target network function instance from the determined set of target network functions based on the received set ID and rerouting, by the network node, the at least one registration request to the selected target network function instance for performing a registration procedure of the at least one UE in the network.

[0045] In another embodiment, a computer program product is disclosed which comprises a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (500) for rerouting the registration request in the network.method for registering at least one user equipment (UE) in a network. The method comprises receiving, by an initial access and mobility management function (AMF), a registration request from the at least one UE. The registration request comprises a routing indicator. The method further comprises determining, by the initial AMF, whether the initial AMF is capable of serving the at least one UE based on the routing indicator. Further, the method comprises determining, by the initial AMF, a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE based on the received routing indicator, when the initial AMF determines that it is unable to serve the at least one UE. The initial AMF reroutes the registration request via a radio access network (RAN) to the target AMF set. The registration request includes a set identifier to the target AMF set. The method further includes selecting, by the RAN, a specific target AMF instance from the target AMF set based on the received set identifier and transmitting, by the RAN, the registration request to the selected target AMF instance. Furthermore, the method includes performing, by the selected target AMF instance, a registration procedure for the at least one UE.OBJECTIVES OF THE PRESENT DISCLOSURE

[0046] Some of the objectives of the present disclosure, which at least one embodiment herein satisfies, are as follows:

[0047] An objective of the present disclosure is to provide an efficient mechanism for rerouting a registration request to the appropriate network function, ensuring seamless authentication and service continuity for the User Equipment (UE).

[0048] Another objective of the present disclosure is to enhance network reliability by preventing registration failures caused by the selection of an incorrect Access and Mobility Management Function (AMF) that lacks access to the required user profile.

[0049] Another objective of the present disclosure is to ensure optimized selection of a target AMF by utilizing routing indicators or other network parameters to determine the most suitable AMF instance.

[0050] Yet another objective of the present disclosure is to minimize registration failures and unnecessary retries by dynamically rerouting registration requests to the appropriate AMF without requiring multiple attempts by the UE.

[0051] Another objective of the present disclosure is to enable a systematic and automated rerouting mechanism that does not rely on manual network intervention, thereby improving network efficiency and reducing latency.

[0052] Another objective of the present disclosure is to provide a mechanism for rerouting the registration request to the appropriate network function before initiating an authentication and subscriber profile retrieval procedure, thereby ensuring efficient registration handling, and reducing unnecessary authentication failures.

[0053] Another objective of the present disclosure is to enhance user experience by ensuring faster and more accurate registration request processing, leading to reduced connection delays and improved network accessibility.

[0054] Other objectives and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings, which are incorporated herein, and constitute a part of this disclosure, illustrate exemplary embodiments of the disclosed methods and systems in which like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Some drawings may indicate the components using block diagrams and may not represent the internal circuitry of each component. It will be appreciated by those skilled in the art that disclosure of such drawings includes the disclosure of electrical components, electronic components or circuitry commonly used to implement such components.

[0056] FIG. 1 illustrates an exemplary network architecture implementing a system configured for rerouting a registration request in a network, in accordance with an embodiment of the present disclosure.

[0057] FIG. 2 illustrates an exemplary block diagram of the system configured for rerouting the registration request in the network, in accordance with an embodiment of the present disclosure.

[0058] FIG. 3 illustrates an exemplary system architecture for rerouting the registration request in the network, in accordance with an embodiment of the present disclosure.

[0059] FIG. 4 illustrates an exemplary process flow for rerouting the registration request in the network, in accordance with an embodiment of the present disclosure.

[0060] FIG. 5 illustrates an exemplary flowchart for rerouting the registration request in the network, in accordance with an embodiment of the present disclosure.

[0061] FIG. 6 illustrates another exemplary flowchart for rerouting the registration request in the network, in accordance with an embodiment of the present disclosure.

[0062] FIG. 7 illustrates an exemplary computer system in which or with which the embodiments of the present disclosure may be implemented.

[0063] The foregoing shall be more apparent from the following detailed description of the disclosure.LIST OF REFERENCE NUMERALS100 - Network architecture102 -User(s)104 -User Equipments (UEs)106 - Network108 - System200 - Block diagram202 - Processor(s)204 - Memory206 - Interface(s)208 - Processing Engine210 - Database300 - System Architecture302 - Core Network- 1304 - Core Network-2306 - gNodeB308 - Access and Mobility Management Function (AMF) 1310 - Access and Mobility Management Function (AMF) 2312-Authenti cation Server Function (AUSF)1 / Unified Data Management (UDM)l 314 - Authentication Server Function (AUSF)2 / Unified Data Management (UDM) 2400 - Process Flow500-Exemplary Flowchart600-Another Exemplary Flowchart700 - A computer system710 - External Storage Device720 - Bus730 - Main Memory740 - Read Only Memory750 - Mass Storage Device760 - Communication Port(s)770 - ProcessorDETAILED DESCRIPTION

[0064] In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent, however, that embodiments of the present disclosure may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address any of the problems discussed above or might address only some of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein. Example embodiments of the present disclosure are described below, as illustrated in various drawings in which like reference numerals refer to the same parts throughout the different drawings.

[0065] The ensuing description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the ensuing description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the disclosure as set forth.

[0066] Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments.

[0067] Also, it is noted that individual embodiment may be described as a process that is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed but could have additional steps not included in a figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, itstermination can correspond to a return of the function to the calling function or the main function.

[0068] The word “exemplary” and / or “demonstrative” is used herein to mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by such examples. In addition, any aspect or design described herein as “exemplary” and / or “demonstrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to preclude equivalent exemplary structures and techniques known to those of ordinary skill in the art. Furthermore, to the extent that the terms “includes,” “has,” “contains,” and other similar words are used in either the detailed description or the claims, such terms are intended to be inclusive like the term “comprising” as an open transition word without precluding any additional or other elements.

[0069] Reference throughout this specification to “one embodiment” or “an embodiment” or “an instance” or “one instance” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0070] The terminology used herein is to describe particular embodiments only and is not intended to be limiting the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any combinations of one or more of the associated listed items. It should be noted that the terms “mobile device”, “user equipment”, “user device”, “communication device”, “device” and similar terms are used interchangeably for the purpose of describing the invention. These terms are not intended to limit the scope of the invention or imply any specific functionality or limitations on the described embodiments. The use of these terms is solely for convenience and clarity of description. The invention is not limited to any particular type of device or equipment, and it should be understood that other equivalent terms or variations thereof may be used interchangeably without departing from the scope of the invention as defined herein.

[0071] As used herein, an “electronic device”, or “portable electronic device”, or “user device” or “communication device” or “user equipment” or “device” refers to any electrical, electronic, electromechanical, and computing device. The user device is capable of receiving and / or transmitting one or parameters, performing function / s, communicating with other user devices, and transmitting data to the other user devices. The user equipment may have a processor, a display, a memory, a battery, and an input-means such as a hard keypad and / or a soft keypad. The user equipment may be capable of operating on any radio access technology including but not limited to IP-enabled communication, Zig Bee, Bluetooth, Bluetooth Low Energy, Near Field Communication, Z-Wave, Wi-Fi, Wi-Fi direct, etc. For instance, the user equipment may include, but not limited to, a mobile phone, smartphone, virtual reality (VR) devices, augmented reality (AR) devices, laptop, a general -purpose computer, desktop, personal digital assistant, tablet computer, mainframe computer, or any other device as may be obvious to a person skilled in the art for implementation of the features of the present disclosure.

[0072] Further, the user device may also comprise a “processor” or “processing unit” includes processing unit, wherein processor refers to any logic circuitry for processing instructions. The processor may be a general -purpose processor, a special purpose processor, a conventional processor, a digital signal processor, a plurality of microprocessors, one or more microprocessors in association with a Digital Signalling Processing (DSP) core, a controller, a microcontroller, Application Specific Integrated Circuits, Field Programmable Gate Array circuits, any other type of integrated circuits, etc. The processor may perform signal coding data processing, input / output processing, and / or any other functionality that enables the working of the system according to the present disclosure. More specifically, the processor is a hardware processor.

[0073] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment, as well as other embodiments of the disclosure, will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

[0074] In telecommunications networks, user registration is a crucial process for establishing connectivity and accessing network services. However, significant challenges arise when a Public Land Mobile Network (PLMN) comprises multiple segregated networks, each operating with its own independent set of network functions, including an Access and Mobility Management Function (AMF), an Authentication Server Function (AUSF), and a Unified Data Management (UDM).

[0075] A major issue occurs when a User Equipment (UE) initiates a registration request, and it is routed to an incorrect AMF, that does not belong to the UE’s designated network. Since the incorrect AMF does not have access to the corresponding UDM and AUSF, which store and manage the UE’s subscription details, the authentication process fails, leading to registration failure.

[0076] This problem is exacerbated when the UE repeatedly attempts to register, but its request continues to be routed to the wrong AMF, resulting in repeated registration failures. Due to the lack of interconnectivity between the segregated networks, the incorrect AMF cannot redirect the request to the correct AUSF and UDM instance, making it impossible to complete authentication.

[0077] The existing standards do not provide a formalized solution to address the issue of incorrect AMF selection in networks with multiple segregated infrastructures. Consequently, repeated registration failures remain a persistent service-impacting challenge, with no standardized mechanism available to mitigate the issue effectively.

[0078] To address this problem, the present disclosure provides a method and a system for rerouting the registration request in the network.

[0079] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0080] FIG. 1 illustrates an exemplary network architecture 100 implementing a system 108 configured for rerouting a registration request in a network 106, in accordance with an embodiment of the present disclosure.

[0081] As illustrated in FIG. 1, the network architecture 100 may include one or more User Equipments (UEs) 104-1, 104-2... 104-N associated with one or more users 102-1, 102-2... 102-N in an environment. A person of ordinary skill in the art will understand that one or more users 102-1, 102-2... 102-N may be collectively referred to as the users 102 or the user 102. Similarly, a person of ordinary skill in the art will understand that one or more UEs 104-1, 104-2... 104-N may be collectively referred to as the UE 104 or the UEs 104. Although only three UEs 104 are depicted in FIG. 1, however, any number of the UE 104 may be included without departing from the scope of the ongoing description.

[0082] In an embodiment, the UE 104 may include smart devices operating in a smart environment, for example, an Internet of Things (loT) system. In such an embodiment, the UE 104 may include, but is not limited to, smartphones, smart watches, smart sensors (e.g., a mechanical, a thermal, an electrical, a magnetic, etc.), networked appliances, networked peripheral devices, networked lighting system, communication devices, networked vehicle accessories, networkedvehicular devices, smart accessories, tablets, a smart television (TV), computers, a smart security system, a smart home system, other devices for monitoring or interacting with or for the users 102 and / or entities, or any combination thereof. A person of ordinary skill in the art will appreciate that the UE 104 may include, but is not limited to, intelligent, multi -sensing, network-connected devices, which may integrate seamlessly with each other and / or with a central server or a cloudcomputing system or any other device that is network-connected.

[0083] Additionally, in some embodiments, the UE 104 may include, but not limited to, a handheld wireless communication device (e.g., a mobile phone, a smartphone, a phablet device, and so on), a wearable computer device (e.g., a headmounted display computer device, a head-mounted camera device, a wristwatch computer device, and so on), a Global Positioning System (GPS) device, a laptop computer, a tablet computer, or another type of portable computer, a media playing device, a portable gaming system, and / or any other type of computer device with wireless communication capabilities, and the like. In an embodiment, the UE 104 may include, but are not limited to, any electrical, electronic, electromechanical, or equipment, or a combination of one or more of the above devices, such as virtual reality (VR) devices, augmented reality (AR) devices, a laptop, a general-purpose computer, a desktop, a personal digital assistant, a tablet computer, a mainframe computer, or any other computing device. Further, the UE 104 may include one or more in-built or externally coupled accessories including, but not limited to, a visual aid device such as a camera, an audio aid, a microphone, a keyboard, and input devices for receiving input from the user 102 or an entity such as a touchpad, a touch-enabled screen, an electronic pen, and the like. A person of ordinary skill in the art will appreciate that the UE 104 may not be restricted to the mentioned devices and various other devices may be used.

[0084] In an embodiment, the UE 104 may communicate with the system 108 through the network 106 for sending or receiving various types of data.

[0085] In an embodiment, the network 106 may include at least one of a 4G network, a 5G network, a 6G network, or the like. The network 106 may enable the UE 104 to communicate with other devices in the network architecture 100 and / or with the system 108. The network 106 may include a wireless card or some other transceiver connection to facilitate this communication. In another embodiment, the network 106 may be implemented as, or include any of a variety of different communication technologies such as a wide area network (WAN), a local area network (LAN), a wireless network, a mobile network, a Virtual Private Network (VPN), the Internet, a Public Switched Telephone Network (PSTN), or the like.

[0086] In an embodiment, the network 106 may include, by way of example but not limited to, at least a portion of one or more networks having one or more nodesthat transmit, receive, forward, generate, buffer, store, route, switch, process, or a combination thereof, etc. one or more messages, packets, signals, waves, voltage or current levels, some combination thereof, or so forth. The network 106 may also include, by way of example but not limitation, one or more of, a wireless network, a wired network, an internet, an intranet, a public network, a private network, a packet-switched network, a circuit-switched network, an ad hoc network, an infrastructure network, the PSTN, a cable network, a cellular network, a satellite network, a fiber optic network, or some combination thereof.

[0087] In an embodiment, a registration request from the UE (104) is received by the system (108). The system is implemented in a first network function such as an initial AMF which extracts one or more parameters from the registration request. The first network function determines a second network function i.e. a second AMF that is capable to serve the UE (104) based on the one or more extracted parameters. Upon determining, the first network function reroutes the registration message towards the determined second network function. The method ensures improved service delivery by directing the UE registration to the second network function that is most suited to serve the UE (104).

[0088] Although FIG. 1 shows exemplary components of the network architecture 100, in other embodiments, the network architecture 100 may include fewer components, different components, differently arranged components, or additional functional components than depicted in FIG. 1. Additionally, or alternatively, one or more components of the network architecture 100 may perform functions described as being performed by one or more other components of the network architecture 100.

[0089] FIG. 2 illustrates an exemplary block diagram 200 of the system 108 for rerouting the registration request in the network 106, in accordance with an embodiment of the disclosure.

[0090] In an embodiment, the system 108 may include one or more processor(s) 202. The one or more processor(s) 202 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and / or any devices that process data based on operational instructions. Among other capabilities, the one or more processor(s) 202 may be configured to fetch and execute computer-readable instructions stored in a memory 204 of the system 108. The memory 204 may be configured to store one or more computer-readable instructions or routines in a non-transitory computer readable storage medium, which may be fetched and executed to create or share data packets over a network service. The memory 204 may include any non-transitory storage device including, for example, volatile memory such as aRandom-Access Memory (RAM), or a non-volatile memory such as an Erasable Programmable Read Only Memory (EPROM), a flash memory, and the like.

[0091] In an embodiment, the system 108 may include an interface(s) 206. The interface(s) 206 may include a variety of interfaces, for example, interfaces for data input and output devices (VO), storage devices, and the like. The interface(s) 206 may facilitate communication through the system 108. The interface(s) 206 may also provide a communication pathway for one or more components of the system 108. Examples of such components include, but are not limited to, a processing engine 208 and a database 210.

[0092] In an embodiment, the system 108 may include a processing engine 208 that may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing engine 208. In the examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing engine 208 may be processorexecutable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing engine 208 may comprise a processing resource (for example, one or more processors) to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the processing engine 208. In such examples, the system 108 may comprise the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to the system 108 and the processing resource. In other examples, the processing engine 208 may be implemented by electronic circuitry. In yet another examples, the processing engine 208 may be implemented or embedded in a first network function. In an example, the first network function may be an Access and Mobility Management Function (AMF).

[0093] In an embodiment, the processing engine 208 (i.e., the first network function) is configured to receive the registration request (interchangeably referred to as NAS message) from the UE 104. In an aspect, the UE 104 may transmit the registration request to the first network function via a network entity. In an example, the network entity may be a gNodeB (interchangeably referred to as a gNB or aNodeB (6G)) The registration request is a signaling message sent by the UE 104 to initiate a connection with the network 106. In other words, when the UE 104 needs to register with the network 106 to get authorized, to receive services, to enable mobility tracking and to enable reachability, the UE 106 initiates the registration request towards the AMF via the gNB. Additionally, the registration request is typically used for initial access, mobility registration, and periodic updates to maintain network connectivity.

[0094] In an aspect, the first network function (i.e., AMF) may extract the one or more parameters (such as routing parameters) associated with the received registration request. The one or more parameters may include but are not limited to Subscription Concealed Identifier (SUCI), Routing Indicator (RI).

[0095] The SUCI is a privacy-preserving identifier derived from a Subscription Permanent Identifier (SUPI). The SUCI helps in protecting the user's identity during initial network registration and assists in determining the home network of the UE 104. The RI may be a numeric identifier embedded within the SUCI. For example, the RI may be a fixed-length numeric value, which may contain a specific number of digits (e.g., 0 to 16 digits), each digit representing a unique identifier that is assigned and mapped to a specific AMF in an AMF set. In an aspect, the RI may be embedded within the SUCI. The RI may be incorporated as a specific field within the SUCI. By embedding the RI in the SUCI, the first network function (the AMF) can extract routing information early in the registration process. For example, when the UE 104 sends the registration request via the gNB, the AMF extracts the RI embedded in the SUCI.

[0096] In an aspect, the first network function (i.e., AMF) maintains a mapping of RI corresponding to different AMF sets. The first network function (i.e., AMF) may be configured with built-in logic where it keeps mapping of the RI against different set of second network functions.

[0097] In an embodiment, the processing engine 208 (i.e., the first network function) is configured to identify whether it is capable of serving the UE 104 based on the one or more routing parameters. In an aspect, the serving capability of the first network function refers to the ability of the AMF to process the registration request successfully and facilitate further interactions between the UE 104 and the network. This includes tasks such as authenticating the UE, retrieving the UE's subscription data from a Unified Data Management (UDM), interacting with an Authentication Server Function (AUSF), and establishing necessary connections with other network functions to enable communication and mobility management.

[0098] In an aspect, the processing engine 208 (i.e., the first network function) may compare the received RI with its internally configured parameters. If the RI corresponds to a group of network functions to which the first network function does not belong, the first network function determines that it is not authorized or capable of serving the UE 104. For example, consider a scenario where a telecom operator has deployed two distinct AMF sets: AMF1 and AMF2, each designated to handle different categories of users. AMF1 is specifically assigned to manage enterprise users, while AMF2 is responsible for handling regular consumer traffic. When the AMF1 receives a registration request from the UE 104, it examines the RI included in the registration request. The AMF then cross-references the receivedRI with its internal mapping of AMF sets. If the RI corresponds to AMF2, which is designated for regular consumer traffic, the AMF1 determines that it cannot process the UE's request, as it is exclusively responsible for enterprise users.

[0099] In an embodiment, the processing engine 208 (i.e., the first network function) is configured to determine a second network function that is capable of serving the UE 104 based on the one or more parameters. In an example, the second network function may be another AMF. In other example, the first network function may determine a set of second network function (i.e., a set of AMFs) based on the received RI. The first network function may check its built-in mapping and determine which second network function in a set of second network functions (i.e., the AMF set) corresponds to the RI. Based on the built-in logic, the first network function AMF derives the specific AMF in the set of AMF set pertaining to the RI received.

[0100] In an embodiment, the processing engine 208 (i.e., the first network function) is configured to reroute the registration message to the determined second network function. Once the appropriate second network function is determined, the first network function reroutes the registration message (NAS message) to a network entity, such as the gNodeB, which the selects a specific second network instance (AMF instance) (e.g. AMF -2) within the identified set of second network functions. Further, the network entity forwards the registration request to the selected second network function. For example, a AMF1 receives a registration request from the UE 104, it analyzes the RI and determines that the UE 104 should be handled by AMF2 (e.g., AMF2 specializes in handling loT devices while AMF1 is for eMBB users). AMF1 then reroutes NAS message containing the UE's registration request, along with an identifier of the correct AMF set or instance. This rerouted NAS message is sent to the gNodeB, which then selects the correct AMF instance (AMF2) and forwards the registration request to it, ensuring that the UE 104 is served by the appropriate network function.

[0101] In an aspect, upon receiving the registration request, the second network function, initiates the general registration procedure by interacting with the necessary network functions, such as the AUSF, the UDM, and Policy Control Function (PCF) to authenticate and register the UE 104. Upon successful registration, the second network function transmits a registration acceptance message back to the UE 104, confirming the completion of the registration process. This rerouting mechanism ensures that the registration request reaches the correct network function, thereby preventing registration failures and optimizing network efficiency.

[0102] FIG. 3 illustrates an exemplary system architecture 300 configured for rerouting the registration request in the network 106, in accordance with anembodiment of the present disclosure. FIG. 3 is explained in conjunction with the FIGs 1 and 2.

[0103] In an aspect, the system architecture 300 includes various network components or entities.

[0104] In an aspect, the system architecture 300 includes a single PLMN and within the single PLMN, there exist two core networks (for e.g. 5G core networks): Core Network-1 302 and Core Network-2 304. Within the single PLMN, there is a gNodeB 306, (interchangeably referred to as the gNB 306). The gNodeB 306 communicates with Core Network- 1 (302) over an N2 interface.

[0105] The Core Network-1 302, includes an AMF1 308 and the Core Network-2 304 includes an AMF2 310. The AMF1 308 is connected to an AUSF1 and / or a UDM1 312 via an N8 or N12 interface. Similarly, the AMF2 310 is connected to an AUSF2 and / or a UDM2314 via the N8 or N12 interface.

[0106] In an aspect, the UE 104 sends the registration request (NAS message) to the AMF1 308 via the gNodeB 306.

[0107] In an aspect, upon receiving the registration request, the AMF1 308 may extract the one or more parameters such as SUCI and RI present in the SUCI.

[0108] In an aspect, the AMF1 308 may compare mapping present in the received RI with its internally configured parameters. If the mapping of the received RI does not correspond to the AMF 1 308, the AMF 1 308 determines that it is not authorized or capable of serving the UE 104.

[0109] Based on the RI and the built-in logic, the AMF1 308 derives that the AMF2 310 is the appropriate network function for serving the UE 104. In other words, the AMF-2310 is determined based on the RI mapping as the network function capable of processing the registration request for the UE 104.

[0110] In an aspect, the AMF1 308 reroutes the registration request to the AMF2 310 via the gNodeB 306 using the NAS reroute procedure. The AMF1 308 and AMF2 310 communicate over an N2 interface. In the NAS reroute procedure the AMF1 generates an N2 message and reroutes the registration request (NAS message) along with an identifier of the correct AMF set, such as the AMF2 310. This rerouted NAS message is sent to the gNodeB 306, which then selects the AMF2 310 and forwards the registration request (NAS message) to it, ensuring that the UE 104 is served by the appropriate network function. The AMF2 310, which then carries out the general registration procedure by interacting with the required network functions such as AUSF2 and UDM2314. Upon successful completion ofthe registration process, the AMF2 310 sends the registration acceptance message to the UE 104, confirming successful registration.[OHl] FIG. 4 illustrates an exemplary process flow 400 for rerouting the registration request in the network 106, in accordance with an embodiment of the present disclosure. FIG. 4 is explained in conjunction with FIGS. 1, 2 and 3.

[0112] In an aspect, the process flow 400 describes the communication flow between the UE 104, the gNodeB 306, the AMF1 308, the AUSF1 and / or UDM1 312, the AMF2310, and the AUSF2 and / or UDM2314.

[0113] At step 402, the UE 104 sends the registration request to the gNodeB 306. The registration request comprises the SUCI and the RI, which are embedded in the registration request. The RI may be incorporated as a specific field within the SUCI. By embedding the RI in the SUCI, the AMF 1 308 can extract routing information early in the registration process.

[0114] At step 404, the gNodeB 306 forwards the initial UE message (registration request), including the SUCI and RI, to the AMF1 308.

[0115] In an aspect, the AMF1 308 may be configured with a built-in logic where it keeps mapping of the RI (may be specific number) against different sets of second network functions (for e.g. AMF2310).

[0116] At step 406, the AMF1 308 determines that the registration request must be rerouted, as it is not capable of serving the UE 104. This determination is made by the AMF1 308 by evaluating the RI mapping received in the registration request and comparing it with s predefined RI mapping configuration. If the RI mapping does not match, AMF1 308 identifies that it is not the correct AMF assigned to handle the UE’s registration. In such a case, AMF1 determines that the registration request has been incorrectly routed and must be forwarded to the appropriate AMF to ensure successful authentication and registration. Thus, the AMF1 308 identifies that the AUSF1 and / or UDM-1 312 associated with it are not the appropriate network functions to handle the registration request for the UE 104. Consequently, the AMF1 308 triggers the rerouting process to direct the registration request towards a more suitable set of second network functions, i.e., a set of AMF (for e.g. the AMF2 310), which is mapped in the received RI. The AMF1 308 executes its built-in logic based on the RI to determine the suitable second network function (AMF2 310) that is capable of serving the UE 104.

[0117] At step 408, the AMF1 308 sends the NAS reroute message to the gNodeB 306. The NAS reroute message includes the identifier of the determined set of second network function i.e., the target AMF set ID (AMF Set ID). The AMF Set ID is a unique identifier to group multiple AMFs into a logical set. The AMF set IDhelps the gNodeB 306 determine the appropriate AMF for handling a UE’s registration.

[0118] At step 410, the gNodeB 306 performs the selection of the appropriate AMF i.e. the AMF2310 based on the received AMF Set ID. The gNodeB 306 may extract the identifier included in the NAS message sent by the AMF1 308 and select the AMF2 310.

[0119] At step 412, the gNodeB 306 reroutes the initial UE message (registration request) to the AMF2310. The gNodeB 306 may modify routing information such as AMF selection details and forwards the UE’s initial registration request to the AMF2 310 via the N2 interface.

[0120] At step 414, the authentication and authorization procedures are performed between the AUSF2 and / or UDM2 314. After receiving the rerouted registration request from the gNodeB 306, AMF2 310 extracts the SUCI. Further, the AMF2 sends an authentication request to the appropriate AUSF2314 which is responsible for handling security and authentication. The AUSF2314 interacts with the UDM2 314 to retrieve the UE’s subscriber profile and authentication credentials (e.g., authentication vectors, security keys). Additionally, the AUSF2 314 may generate authentication challenges and sent back to AMF2 310. The AMF2 310 then forwards the generate authentication challenges to the UE 104. The UE 104 computes and returns an authentication response, which is then validated by AUSF2 314.

[0121] If authentication is successful, AUSF2 314 confirms the legitimacy of the UE 104 and provides security key material to AMF2 310. The AMF2 314 then authorizes the UE 104 for network access and generates security contexts for encrypted communication.

[0122] Once authentication and authorization are complete, AMF2 proceeds with the registration process, allowing the UE to access network services and at step 416, the AMF2310 completes the registration process for the UE 104.

[0123] At step 418, the AMF2310 sends the registration acceptance message to the gNodeB 306.

[0124] At step 420, the gNodeB 306 forwards the registration acceptance message to the UE 104, indicating successful registration.

[0125] In an embodiment, AMF 308 checks Routing Indicator (RI) present in the SUCI and locally checks the mapping of RI against different AMF Sets if it can serve the UE 104. If not, then the AMF 304 NAS Reroute procedure by sending a REROUTE NAS REQUEST message containing target AMF Set ID to the NG-RAN node 306. The NG-RAN node shall, if supported, reroute the INITIAL UE MESSAGE to an AMF 310 indicated by the AMF Set ID IE.

[0126] FIG. 5 illustrates an exemplary flowchart of a method 500 for rerouting the registration request in the network 106, in accordance with an embodiment of the present disclosure. FIG. 5 is explained in conjunction with FIGS. 1, 2, 3 and 4.

[0127] At step 502, a network function (308) receives at least one registration request from the at least one UE (104) for registration. The at least one registration comprises a routing indicator. In an embodiment, the routing indicator specifies information such as desired service type, network slice, or intended target function set to help guide the handling of the request.

[0128] At step 504, the network function (308) determines a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE (104) based on the received routing indicator. The Set ID uniquely represents a set of target network functions configured to serve the UE (104), utilizing a preconfigured mapping or table maintained in the network function (308).

[0129] At step 506, the network function (308) reroutes the at least one registration request to a network node (306) using a non-access stratum (NAS) message. The non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions.

[0130] At step 508, the network function (308) selects a target network function instance (310) from the determined set of target network functions based on the received set ID. In an embodiment, the selection criteria may include resource availability, geographical proximity, load balancing, or policy rules.

[0131] At step 510, the network function (308) reroutes the at least one registration request to the selected target network function instance (310) for performing a registration procedure of the at least one UE (104) in the network (106).

[0132] In an embodiment, the network function (308) maintains a preconfigured mapping table containing multiple entries. Each entry provides a correspondence between a specific routing indicator and a set of target network functions. The mapping enables the network function (308) to systematically and efficiently associate incoming requests bearing distinct routing indicators with appropriate network function sets, facilitating precise and flexible routing of registration or service access requests in a dynamic network environment.

[0133] In another embodiment, when determining which set of target network functions should handle the request, the network function (308) retrieves the set identifier (Set ID) of the appropriate network function set directly from thepreconfigured mapping. By using the mapping, the network function (308) identifies the correct Set ID based on the routing indicator present in the request, ensuring reliable and consistent selection of target network functions for further processing and registration operations.

[0134] In an embodiment, the selected target network function instance (310) carries out the registration procedure for the user equipment (UE) (104) by interacting with an authentication server function (AUSF / UDM) (314) to authenticate the UE (104), retrieve relevant subscriber data, and a policy control function (PCF) to obtain and apply policy rules. The coordinated process ensures that the UE (104) is securely authenticated, its subscription information is correctly accessed, and appropriate service and network policies are enforced during registration.

[0135] In an embodiment, the selected target network function instance (310), after being chosen through the selection process, performs a registration procedure for a user equipment (UE) (104). This procedure involves retrieving subscriber data for the UE (104) from the Unified Data Management (UDM) (314), ensuring access to authentication and service information. It further includes applying relevant policy control rules obtained from the Policy Control Function (PCF) to govern service access and network behavior for the UE (104). The selected network function instance (310) then updates the registration context information, maintaining current status and parameters for the UE (104) within the selected network function (310). Finally, it transmits a registration accept message to the UE (104), confirming successful registration and enabling access to network services. This sequence ensures secure, policy-driven, and efficient onboarding of the UE (104) within the network (106).

[0136] In an embodiment, the selected target network function instance (310) performs an authentication and authorization procedure for the at least one UE (104). The authentication and authorization procedure includes initiating, by the selected target network function instance (310), an authentication request to the at least one UE (104) which provides an authentication response to the selected target network function instance (310). The selected target network function instance (310) verifies the received authentication response from the AUSF (314) and authorizes the at least one UE (104) upon successful authentication.

[0137] In an embodiment, the network node (306) selects the target network function instance (310) within the determined set of target network functions based on one or more selection criteria. The one or more selection criteria comprises load balancing across the one or more target network function instances, one or more priority rules defined for the one or more target network function instances, a geographical proximity of the one or more target network function instances to theat least one UE (104) and the network node (306), and an availability status of the one or more target network function instances.

[0138] In an exemplary embodiment, a 5G core network, a network node (gNodeb) (306) receives a request from a user equipment (UE) (104) to access a specific service. The network node (306) determines a set of target network function instances (such as AMF instances) capable of serving the request. The network node (306) evaluates several selection criteria: current processing load on each instance, priority rules defined by the operator (e.g., some instances prioritized for emergency services), geographical proximity of instances to both the UE (104) and the node itself (306), and each instance's real-time availability status. The network node (306) then selects the target network function instance (310) that best satisfies the criteria, for example, choosing an instance with low load, high priority, located nearest to the UE (104) and network node (306), and marked as available, to optimize network performance and user experience.

[0139] In an embodiment, the gNB (306) determines a subset of geographically proximate NF instances based on latency estimates, distance metrics, or region identifiers. In another embodiment, the gNB (306) evaluates load conditions of the geographically proximate NF instances and assigns a selection score to each candidate NF instance. The selection score may be computed as a weighted function of load metric (inversely proportional), priority metric, distance or latency metric, and availability confidence level. The gNB (306) selects a target NF instance (310) having an optimal (e.g., highest or lowest) selection score. In another embodiment, the gNB (306) identifies one or more NF instances that satisfy a priority criterion. The priority criterion may be based on Subscription profile of the UE, Service type (e.g., URLLC, eMBB, mMTC), Operator-defined policies.

[0140] FIG. 6 illustrates an exemplary flowchart of a method 600 for rerouting the registration request in the network 106, in accordance with an embodiment of the present disclosure. FIG. 6 is explained in conjunction with FIGS. 1, 2, 3, 4 and 5.

[0141] At step 602, an initial access and mobility management function (AMF) (308) receives a registration request from the at least one UE (104). The registration request comprises a routing indicator. The routing indicator is a parameter that encapsulates information about network slicing, service requirements, or preferred AMF set. The routing indicator helps guide the registration process to the appropriate network entity

[0142] At step 604, the initial AMF (308) determines whether the initial AMF (308) is capable of serving the at least one UE (104) based on the routing indicator. In an embodiment, this determination involves matching supported network slices,service profiles, or AMF instance attributes with those indicated in the routing indicator.

[0143] At step 606, the initial AMF (308) determines a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE (104) based on the received routing indicator when the initial AMF (308) determines that it is unable to serve the at least one UE (104).

[0144] At step 608, the initial AMF (308) reroutes the registration request via a radio access network (RAN) (306) to the target AMF set. The registration request includes a set identifier to the target AMF set. The purpose is to direct the RAN (306) to guide the request to the appropriate AMF within the identified set.

[0145] At step 610, the RAN (306) selects a specific target AMF instance (310) from the target AMF set based on the received set identifier. In an embodiment, this selection may consider factors like load, proximity, or availability.

[0146] At step 612, the RAN (306) transmits the registration request to the selected target AMF instance (310).

[0147] At step 614, the selected target AMF instance (310) performs a registration procedure for the at least one UE. The selected target AMF instance (310) is presumed to possess the proper capabilities and configuration to serve the UE (104) as specified by the routing indicator.

[0148] In an embodiment, the initial AMF (308) determines based on local policy and subscription information of the at least one UE (104), whether to forward the registration message directly to the target AMF set. Upon receiving a registration message from a UE (104), the initial AMF (308) accesses local policy rules stored in its configuration and retrieves the UE's subscription information from the relevant network database (e.g., UDM). It evaluates criteria such as UE subscription type, permitted service access, roaming status, and supported AMF features. If the local policy and subscription information indicate that the UE qualifies for registration with a specific set of target AMFs (e.g., to access a specialized service or network slice), the initial AMF (308) forwards the registration request directly to the target AMF set. In another embodiment, the initial AMF (308) performs one or more additional registration operations such as registration for specific services such a voice, data, or IMS services, performing registration for different network slices or service types provided by the operator. In one of the embodiments, the initial AMF (308) skips the one or more additional registration operations.

[0149] In an embodiment, one or more additional registration operations comprise retrieving subscription information associated with the at least one UE from a unified data management (UDM) and performing network slice selection via anetwork slice selection function (NSSF). A network repository function (NRF) is queried to obtain addresses and capabilities of one or more candidate AMF instances within the target AMF set. One or more registration status updates are to an old AMF.

[0150] In an embodiment, the one or more additional registration operations are performed when a mobile network operator (MNO) offers a plurality of services within a single public land mobile network (PLMN) via one or more isolated core networks.

[0151] In an exemplary embodiment, in a mobile communication system, a user device (UE) (104) initiates registration with a public land mobile network (PLMN) operated by a mobile network operator (MNO). The MNO offers both voice and data services, which are provided via separate isolated core networks for each service within the same PLMN. Upon registering with the PLMN, the UE (104) detects the availability of multiple services and proceeds to perform additional registration operations with each isolated core network. For instance, after initial registration for data services, the UE subsequently performs separate registration procedures for voice services, ensuring service-specific authentication and connectivity for both isolated core networks within the same PLMN.

[0152] FIG. 7 illustrates an exemplary computer system 700 in which or with which embodiments of the present disclosure may be implemented.

[0153] As shown in FIG. 7, the computer system 700 may include an external storage device 710, a bus 720, a main memory 730, a read-only memory 740, a mass storage device 770, communication port(s) 760, and a processor 770. A person skilled in the art will appreciate that the computer system 700 may include more than one processor and communication ports. The processor 770 may include various modules associated with embodiments of the present disclosure. The communication port(s) 760 may be any of an RS-232 port for use with a modembased dialup connection, a 10 / 100 Ethernet port, a Gigabit or 10 Gigabit port using copper or fiber, a serial port, a parallel port, or other existing or future ports. The communication port(s) 760 may be chosen depending on a network, such a Local Area Network (LAN), Wide Area Network (WAN), or any network to which the computer system 700 connects.

[0154] The main memory 730 may be a Random Access Memory (RAM), or any other dynamic storage device commonly known in the art. The read-only memory 740 may be any static storage device(s) e.g., but not limited to, a Programmable Read Only Memory (PROM) chips for storing static information e.g., start-up or Basic Input / Output System (BIOS) instructions for the processor 770. The mass storage device 770 may be any current or future mass storage solution, which canbe used to store information and / or instructions. Exemplary mass storage device 770 includes, but is not limited to, Parallel Advanced Technology Attachment (PATA) or Serial Advanced Technology Attachment (SATA) hard disk drives or solid-state drives (internal or external, e.g., having Universal Serial Bus (USB) and / or Firewire interfaces), one or more optical discs, Redundant Array of Independent Disks (RAID) storage, e.g. an array of disks.

[0155] The bus 720 communicatively couples the processor 770 with the other memory, storage, and communication blocks. The bus 720 may be, e.g. a Peripheral Component Interconnect (PCI) / PCI Extended (PCI-X) bus, Small Computer System Interface (SCSI), Universal Serial Bus (USB), or the like, for connecting expansion cards, drives, and other subsystems as well as other buses, such a front side bus (FSB), which connects the processor 770 to the computer system 700.

[0156] Optionally, operator and administrative interfaces, e.g. a display, keyboard, joystick, and a cursor control device, may also be coupled to the bus 720 to support direct operator interaction with the computer system. Other operator and administrative interfaces can be provided through network connections connected through the communication port(s) 760. Components described above are meant only to exemplify various possibilities. In no way should the aforementioned exemplary computer system 700 limit the scope of the present disclosure.

[0157] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

[0158] The present disclosure provides a method for rerouting the NAS registration request to the desired AMF based on the Routing Indicator (RI) in a user SUCI. The registration request from the UE is sent via gNodeB to AMF1 in an AMF set. The AMF1 receives the RI present in SUCI, and based on the built-in logic, the AMF-1 derives the specific AMF in another AMF set (i.e., AMF-2), which can serve this UE based on the RI received. The AMF-1 sends the reroute NAS message containing the target AMF set ID to the gNodeB. The gNodeB based on the target AMF set ID selects an AMF instance (e.g., AMF-2) within the AMF set and sends the registration request to AMF-2. The AMF-2 carries out the general registration procedure with desired AUSF, UDM, PCF etc., and the registration result is sent to UE.

[0159] In an embodiment, the initial AMF 308 receives a Registration Request containing a Routing Indicator from the UE. It checks the Routing Indicator against a locally maintained mapping of AMF Sets. If it cannot serve the UE, the initial AMF initiates a NAS reroute by sending a REROUTE NAS REQUEST to the NG-RAN node, containing the target AMF Set ID. The NG-RAN node reroutes the INITIAL UE MESSAGE to an AMF indicated by the AMF Set ID.

[0160] In an embodiment, if the initial AMF 308 needs subscription or slice selection data (not available from the old AMF), it queries UDM for the UE’s Slice Selection Subscription using Nudm SDM Get. The UDM may further query UDR for this information. This enables the initial AMF to obtain Subscribed S-NSSAIs for proper slice selection and registration flow.

[0161] In another embodiment, upon receiving slice selection subscription information, the initial AMF 308 may invoke Nnssf_NSSelection_Get on the NSSF, sending parameters such as Requested NSSAI, Mapping, Subscribed S-NSSAI, TAI, and PLMN ID to determine valid Allowed NSSAI and target AMF Set. The NSSF responds with network slice information and either a target AMF Set or candidate list of AMFs, along with associated NSSAI and rejection details.

[0162] In an embodiment, if a new AMF is selected, the initial AMF informs the old AMF of registration failure via a Namf Communication RegistrationStatusUpdate message, allowing the old AMF to revert to its prior context and state management.

[0163] In an embodiment, when the initial AMF 308 needs to determine a target AMF address, it queries the NRF using Nnrf_NFDiscovery_Request, including NF type and AMF Set. The NRF replies with a list of candidate AMFs and their capabilities, enabling the initial AMF to select a target AMF based on required NF profiles and deployment rules.

[0164] In another embodiment, the initial AMF 308, based on policy and subscription data, may forward the NAS message directly to the target AMF 310 via Namf_Communication_NlMessageNotify, including the Registration Request, access information, SUPI, and MM Context. Alternatively, it can forward the NAS message indirectly via (R)AN 306 using the Reroute NAS message, which contains target AMF and slice selection info. The RAN then sends the Initial UE message to the selected target AMF 310.

[0165] In an embodiment, after the target AMF 310 receives the Registration Request, it proceeds with standard registration from, including retrieval of UE context from the old AMF and usage of 5G security context if available. The target AMF 310 communicates the initial AMF 308 and NGAP ID updates to the RAN 306 as required for session setup.

[0166] In one application embodiment, the disclosed system and method are applied in a communication system supporting multiple network slices, wherein a user equipment initiates registration with an access network without prior knowledge of slice-specific serving nodes. The initial mobility management function evaluates routing and subscription information and dynamically reroutes the registration request to a target mobility management function capable of supporting the subscribed or requested network slice, thereby enabling efficient slice-aware access without requiring pre-configuration at the UE.

[0167] In another application embodiment, the described rerouting mechanism is employed to distribute registration traffic among multiple mobility management functions based on availability, capability, or policy. When an initial mobility management function determines that serving a particular user equipment would exceed resource thresholds or violate operational policies, the registration request is rerouted to a target mobility management function, enabling dynamic load balancing within the core network while maintaining continuity of the registration procedure.

[0168] In one application embodiment, the disclosed method is applied in a system supporting multiple access technologies, including radio access networks of different types. During registration over a first access type, the initial mobility management function considers allowed network slice information for an alternative access type and reroutes the registration request accordingly, thereby enabling consistent mobility management and slice enforcement across heterogeneous access networks.

[0169] In another application embodiment, the method and system are used to ensure secure handling of registration requests when integrity protection is missing or has failed. The initial mobility management function retrieves subscriber and slice selection information from centralized data management entities before deciding whether to reroute the request, thereby preventing unauthorized or misrouted registrations and improving robustness of access control in the core network.

[0170] In one application embodiment, the system applies the disclosed procedures in environments where mobility management function addresses are not statically configured. The initial mobility management function dynamically discovers candidate target mobility management functions through a repository or discovery function based on required capabilities, enabling flexible deployment models, including cloud-native or distributed core networks.

[0171] In another application embodiment, the rerouting and forwarding mechanisms are applied to preserve user equipment context during registrationreallocation events. When a registration request is forwarded directly or indirectly to a target mobility management function, context information and security parameters are selectively reused, reducing signaling overhead and minimizing registration failures during mobility or re-selection scenarios.

[0172] In one application embodiment, the disclosed method and system is used to enforce operator-defined policies or regulatory constraints associated with subscriber identity, location, or service entitlement. The initial mobility management function evaluates routing indicators and subscription attributes and reroutes the registration request to a target function authorized to serve the user equipment within a specific jurisdiction, public land mobile network, or regulated service domain.

[0173] In another application embodiment, the techniques are applied in a virtualized or cloud-native core network environment where mobility management functions are instantiated dynamically. Registration requests are rerouted to mobility management function instances selected based on slice affinity, geographic proximity, or service capability, thereby improving scalability and resilience in elastic network deployments

[0174] In an embodiment, a computer program product is disclosed which comprises a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (500) for optimizing slice selection in a network (106). The method (500) comprises receiving, by a network function (308), at least one registration request from the at least one UE (104) for registration. The at least one registration comprises a routing indicator. The network function (308) determines a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE, based on the received routing indicator and reroutes the at least one registration request to a network node (306) using a non-access stratum (NAS) message. The non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions. The network node (306) selects a target network function instance (310) from the determined set of target network functions based on the received set ID. The network node (306) reroutes the at least one registration request to the selected target network function instance (310) for performing a registration procedure of the at least one UE (104) in the network (106).

[0175] In another embodiment, a computer program product is disclosed which comprises a non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (600) for rerouting the registration request in the network. The method (600) comprises receiving, by an initial access and mobility managementfunction (AMF) (308), a registration request from the at least one UE. The registration request comprises a routing indicator. The initial AMF (308) determines whether the initial AMF (308) is capable of serving the at least one UE (104) based on the routing indicator and a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE (104) based on the received routing indicator, when the initial AMF (308) determines that it is unable to serve the at least one UE (104). The initial AMF (308) reroutes the registration request via a radio access network (RAN) (306) to the target AMF set. The registration request includes a set identifier to the target AMF set. The RAN (306) selects a specific target AMF instance (310) from the target AMF set based on the received set identifier and transmits the registration request to the selected target AMF instance (310) which then performs a registration procedure for the at least one UE (104).

[0176] The method and system of the present disclosure may be implemented in a number of ways. For example, the methods and systems of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order for the steps of the method is for illustration only, and the steps of the method of the present disclosure are not limited to the order specifically described above unless specifically stated otherwise. Further, in some embodiments, the present disclosure may also be embodied as programs recorded in a recording medium, the programs including machine-readable instructions for implementing the methods according to the present disclosure. Thus, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0177] While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be implemented merely as illustrative of the disclosure and not as a limitation.TECHNICAL ADVANTAGES

[0178] The present disclosure enables a shared Radio Access Network (RAN) while maintaining isolated Core Networks within a single radiated Public Land Mobile Network (PLMN), ensuring network flexibility and resource optimization.

[0179] The present disclosure provides a mechanism to reroute a user to the correct Access and Mobility Management Function (AMF) even before the authentication procedure, reducing authentication failures and improving registration efficiency.

[0180] The present disclosure facilitates seamless user registration by dynamically identifying and selecting the appropriate AMF based on routing parameters, thereby improving service continuity and user experience.

[0181] The present disclosure optimizes signaling efficiency by eliminating unnecessary authentication attempts at an incorrect AMF, reducing network resource consumption and improving overall system reliability.

Claims

1. CLAIMSWe Claim:

1. A method (500) for registration of at least one user equipment (UE) (104) in a network (106), the method comprising:receiving, by a network function (308), at least one registration request from the at least one UE (104) for registration, wherein the at least one registration comprises a routing indicator;determining, by the network function (308), a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE (104), based on the received routing indicator;rerouting, by the network function (308), the at least one registration request to a network node (306) using a non-access stratum (NAS) message, wherein the non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions;selecting, by the network node (306), a target network function instance (310) from the determined set of target network functions based on the received set ID; andrerouting, by the network node (306), the at least one registration request to the selected target network function instance (310) for performing a registration procedure of the at least one UE (104) in the network.

2. The method (500) as claimed in claim 1, wherein the network function (308) maintains a preconfigured mapping comprising a plurality of entries, and wherein each entry comprises a mapping between a given routing indicator to a corresponding set of target network functions.

3. The method (500) as claimed in claim 1, wherein determining the set of target network functions comprises:retrieving, by the network function (308), the set ID of the determined set of target network functions from the pre-configured mapping.

4. The method (500) as claimed in claim 1, comprising:executing, by the selected target network function instance (310), the registration procedure of the at least one UE (104) with an authentication server function (AUSF), a unified data management function (UDM), and a policy control function (PCF) (312).

5. The method (500) as claimed in claim 4, wherein performing the registration procedure of the at least one UE (104) comprises:retrieving, by the selected target network function instance (310), subscriber data associated with the at least one UE (104) from the UDM (312);applying, by the selected target network function instance (310), policy control rules from the PCF for the at least one UE (104);updating, by the selected target network function instance (310), registration context information for the at least one UE (104) in the network (106); andtransmitting, by the selected target network function instance (310), a registration accept message to the at least one UE (104).

6. The method (500) as claimed in claim 4, wherein the selected target network function instance (310) performs an authentication and authorization procedure for the at least one UE (104), and wherein the authentication and authorization procedure comprises:initiating, by the selected target network function instance (310), an authentication request to the at least one UE (104);receiving, by the selected target network function instance (310), an authentication response from the at least one UE (104);verifying, by the selected target network function instance (310), the received authentication response from the AUSF; andauthorizing, by the selected target network function instance (310), the at least one UE (104) upon successful authentication.

7. The method (500) as claimed in claim 1, wherein the network node (306) selects the target network function instance (310) within the determined set of target network functions based on one or more selection criteria, wherein the one or more selection criteria comprises load balancing across the one or more target network function instances, one or more priority rules defined for the one or more target network function instances, a geographical proximity of the one or more target network function instances to the at least one UE (104) and the network node (306), and an availability status of the one or more target network function instances.

8. A method (600) for registering at least one user equipment (UE) (104) in a network (106), the method (600) comprising:receiving, by an initial access and mobility management function (AMF) (308), a registration request from the at least one UE, wherein the registration request comprises a routing indicator;determining, by the initial AMF (308), whether the initial AMF (308) is capable of serving the at least one UE (104) based on the routing indicator;determining, by the initial AMF (308), a set identifier (Set ID) of a target AMF set that is capable to serve the at least one UE (104) based on the received routing indicator, when the initial AMF (308) determines that it is unable to serve the at least one UE (104);rerouting, by the initial AMF (308), the registration request via a radio access network (RAN) (306) to the target AMF set, wherein the registration request includes a set identifier to the target AMF set;selecting, by the RAN (306), a specific target AMF instance (310) from the target AMF set based on the received set identifier;transmitting, by the RAN (306), the registration request to the selected target AMF instance (310); andperforming, by the selected target AMF instance (310), a registration procedure for the at least one UE.

9. The method (600) as claimed in claim 8, comprising:determining, by the initial AMF (308), based on local policy and subscription information of the at least one UE (104), whether to forward the registration message directly to the target AMF set;based on the determination, performing, by the initial AMF (308), one ofperforming one or more additional registration operations; or skipping the one or more additional registration operations; and forwarding the registration message directly to the target AMF set.

10. The method (600) as claimed in claim 8, wherein the one or more additional registration operations comprise:retrieving subscription information associated with the at least one UE (104) from a unified data management (UDM) (312);performing network slice selection via a network slice selection function (NSSF);querying a network repository function (NRF) to obtain addresses and capabilities of one or more candidate AMF instances within the target AMF set; andsending one or more registration status updates to an old AMF.

11. The method (600) as claimed in claim 8, wherein the one or more additional registration operations are performed when a mobile network operator (MNO) offers a plurality of services within a single public land mobile network (PLMN) via one or more isolated core networks.

12. A system (108) for registration of at least one user equipment (UE) (104) in a network (106), the system (108) comprising a processing engine (208) configured to:receive at least one registration request from the at least one UE (104) for registration, wherein the at least one registration comprises a routing indicator;determine a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE (104), based on the received routing indicator;reroute the at least one registration request to a network node (306) using a non-access stratum (NAS) message, wherein the non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions, wherein the network node (306) selects a target network function instance (310) from the determined set of target network functions based on the received set ID and reroutes the at least one registration request to the selected target network function instance (310) for performing a registration procedure of the at least one UE (104) in the network.

13. The system (108) as claimed in claim 12, wherein the processing engine (208) maintains a preconfigured mapping comprising a plurality of entries, and wherein each entry comprises a mapping between a given routing indicator to a corresponding set of target network functions.

14. The system (108) as claimed in claim 12, wherein the processing engine (208) determines the set of target network functions by retrieving the set ID of the determined set of target network functions from the pre-configured mapping.

15. The system (108) as claimed in claim 12, wherein the selected target network function instance (310) executes the registration procedure of the at least one UE (104) with an authentication server function (AUSF), a unified data management function (UDM), and a policy control function (PCF).

16. The system (108) as claimed in claim 15, wherein the selected target network function instance (310) is configured to:retrieve subscriber data associated with the at least one UE (104) from the UDM;apply policy control rules from the PCF for the at least one UE (104);update registration context information for the at least one UE (104)in the network; andtransmit a registration accept message to the at least one UE (104).

17. The system (108) as claimed in claim 15, wherein the selected target network function instance (310) performs an authentication and authorization procedure for the at least one UE (104), and wherein the authentication and authorization procedure comprises:initiating, by the selected target network function instance (310), an authentication request to the at least one UE (104);receiving, by the selected target network function instance (310), an authentication response from the at least one UE (104);verifying, by the selected target network function instance (310), the received authentication response from the AUSF; andauthorizing, by the selected target network function instance (310), the at least one UE (104) upon successful authentication.

18. The system (108) as claimed in claim 12, wherein the network node (306) is configured to select the target network function instance (310) within the determined set of target network functions based on one or more selection criteria, wherein the one or more selection criteria comprises load balancing across the one or more target network function instances, one or more priority rules defined for the one or more target network function instances, a geographical proximity of the one or more target network function instances to the at least one UE (104) and the network node (306), and an availability status of the one or more target network function instances.

19. A computer program product comprising a non-transitory computer- readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (500) for optimizing slice selection in a network (106), the method (500) comprising:receiving, by a network function (308), at least one registration request from the at least one UE (104) for registration, wherein the at least one registration comprises a routing indicator;determining, by the network function (308), a set identifier (Set ID) of a set of target network functions that is configured to serve the at least one UE, based on the received routing indicator;rerouting, by the network function (308), the at least one registration request to a network node (306) using a non-access stratum (NAS) message,wherein the non-access stratum (NAS) message comprises the set identifier (Set ID) of the determined set of target network functions;selecting, by the network node (306), a target network function instance (310) from the determined set of target network functions based on the received set ID; andrerouting, by the network node (306), the at least one registration request to the selected target network function instance (310) for performing a registration procedure of the at least one UE (104) in the network (106).

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