FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“METHOD AND SYSTEM FOR MANAGING SUBSCRIPTION OF NETWORK FUNCTIONS”
We, Jio Platforms Limited, an Indian National, of Office - 101, Saffron, Nr. Centre Point, Panchwati 5 Rasta, Ambawadi, Ahmedabad - 380006, Gujarat, India.
The following specification particularly describes the invention and the manner in which it is to be performed.

METHOD AND SYSTEM FOR MANAGING SUBSCRIPTION OF NETWORK FUNCTIONS
FIELD OF DISCLOSURE
[0001] Embodiments of the present disclosure generally relate to network performance management systems. More particularly, embodiments of the present disclosure relate to methods and systems for managing subscription of network functions.
BACKGROUND
[0002] The following description of the 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 is used only to enhance the understanding of the reader with respect to the present disclosure, and not as admissions of the prior art.
[0003] Wireless communication technology has rapidly evolved over the past few decades, with each generation bringing significant improvements and advancements. The first generation of wireless communication technology was based on analog technology and offered only voice services. However, with the advent of the second-generation (2G) technology, digital communication and data services became possible, and text messaging was introduced. 3G technology marked the introduction of high-speed internet access, mobile video calling, and location-based services. The fourth generation (4G) technology revolutionized wireless communication with faster data speeds, better network coverage, and improved security. Currently, the fifth generation (5G) technology is being deployed, promising even faster data speeds, low latency, and the ability to connect multiple devices simultaneously. With each generation, wireless communication

technology has become more advanced, sophisticated, and capable of delivering more services to its users.
[0004] Moreover, the 5G core networks are based on service-based architecture (SBA) that is centered around network function (NF) services. In said Service-Based Architecture (SBA), a set of interconnected Network Functions (NFs) delivers the control plane functionality and common data repositories of the 5G network, where each NF is authorized to access services of other NFs. Also, in the 5G core networks, a Network Slice Selection Function (NSSF) selects the network slicing instance (NSI), determines the allowed network slice selection assistance information (NSSAI), and sets a network function (NF) service consumer (such as an access and mobility management function (AMF)) to serve a user equipment (UE). The NF service consumer (such as the AMF) subscribes to the NSSF for any change in slice authorized data.
[0005] There are many instances of stale subscriptions in the communication networks. In the existing systems, many notifications related to stale subscription may be received at the network functions service (e.g., AMF) from the NSSF. Currently, there exists no solution that deals with the technical challenges of detection of notifications for stale subscriptions originating from the NSSF. The existing solutions fail to remove stale subscriptions from the NSSF. The stale subscriptions can accumulate overtime, leading to an overwhelming number of notifications being sent to the NSSF and processed by NF service consumers (e.g., AMF).
[0006] Thus, there exists an imperative need in the art to provide an efficient and effective system and method to perform efficient and effective management of stale subscriptions and overcome the limitations of the existing technologies, which the present disclosure aims to address.
OBJECTS OF THE DISCLOSURE

[0007] Some of the objects of the present disclosure, which at least one embodiment disclosed herein satisfies are listed herein below.
[0008] It is an object of the present disclosure to provide a system and a method for managing subscription of network functions, that may efficiently and effectively manage stale subscriptions in a wireless communication network.
[0009] It is another object of the present disclosure to provide a solution to process multiple subscription-condition based notifications for network function (NF) service consumer.
[0010] It is yet another object of the present disclosure to provide a solution to remove overhead during processing multiple notifications at the NSSF and the AMF
[0011] It is yet another object of the present disclosure to increase overall network efficiency.
[0012] It is yet another object of the present disclosure to provide a solution to provide management of stale subscriptions based on detection of a subscription response at the NF service consumer from the NSSF and a detection of a notification request from NSSF at the NF service consumer.
SUMMARY
[0013] This section is provided to introduce certain aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.

[0014] An aspect of the present disclosure may relate to a method for managing subscription of network functions. The method comprises receiving, by a transceiver unit connected to at least one network function (NF), from a target service function, a notification request. The notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function. Further, the method comprises determining, by a determination unit connected to at least the one NF, a match between the received unique SID, and a set of subscription IDs associated with the NF. The set of subscription IDs are stored in a database connected to at least the one NF. Furthermore, in response to a negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, the method comprises generating, by a subscription unit connected to at least the one NF, an error message indicative of the negative match between the received unique SID and the stored set of subscription IDs. Moreover, the method comprises transmitting, by the subscription unit, an unsubscribing request to the target service function. The unsubscribing request is transmitted for revocation of the subscription of the at least one NF with the target service function.
[0015] In an exemplary aspect of the present disclosure, prior to receiving, from the target service function, the notification request, the method comprises transmitting, by the transceiver unit, from the at least one NF, a subscription request to the target service function. Thereafter, the method comprises receiving, by the transceiver unit, at the at least one NF, from the target service function, in response to the subscription request, the unique SID. Next, the method comprises storing, by a storing unit connected at least to the transceiver unit, in the database, the received unique SID.
[0016] In an exemplary aspect of the present disclosure, the method comprises transmitting, by the transceiver unit, to the target service function, a notification comprising the error message.

[0017] In an exemplary aspect of the present disclosure, the method comprises removing, by a processing unit connected at least to the target service function, in response to the received unsubscribing request at the target service function, the subscription of the at least one NF from the target service function.
[0018] In an exemplary aspect of the present disclosure, at least the one NF is an Access and Mobility Management Function (AMF). The target service function is a network slice service function (NSSF). The subscription request relates to a requirement, by the AMF, of a change in slice authorized data from the NSSF.
[0019] Another aspect of the present disclosure may relate to a system to manage subscription of network functions. The system comprises a transceiver unit connected to at least one network function (NF). The transceiver unit is configured to receive, from a target service function, a notification request. The notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function. Further, the system comprises a determination unit connected to the at least one NF. The determination unit is configured to determine a match between the received unique SID, and a set of subscription IDs associated with the NF. The set of subscription IDs are stored in a database connected to at least the one NF. Furthermore, the system comprises a subscription unit connected to the at least one NF. In response to a negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, the subscription unit is configured to generate an error message indicative of the negative match between the received unique SID and the stored set of subscription IDs. Moreover, the subscription unit is configured to transmit an unsubscribing request to the target service function. The unsubscribing request is transmitted for revocation of the subscription of the at least one NF with the target service function.
[0020] Yet another aspect of the present disclosure relates to a non-transitory computer readable storage medium storing instructions for managing subscription

of network functions, the instructions include executable code which, when executed by one or more units of a system, causes: a transceiver unit connected to at least one network function (NF), to receive, from a target service function, a notification request; wherein the notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function; a determination unit connected to the at least the one NF to determine a match between the received unique SID, and a set of subscription IDs associated with the NF, wherein the set of subscription IDs are stored in a database connected to at least the one NF. In response to a negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, the instructions include executable code which, when executed by one or more units of the system, causes: the subscription unit connected to at least the one NF to generate an error message indicative of the negative match between the received unique SID and the stored set of subscription IDs. The instructions include executable code which, when executed by one or more units of the system, causes: the transceiver unit to transmit an unsubscribing request to the target service function. The unsubscribing request is transmitted for revocation of the subscription of the at least one NF with the target service function.
DESCRIPTION OF THE DRAWINGS
[0021] 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. Also, the embodiments shown in the figures are not to be construed as limiting the disclosure, but the possible variants of the method and system according to the disclosure are illustrated herein to highlight the advantages of the disclosure. It will be appreciated by those skilled in the art that disclosure of such

drawings includes disclosure of electrical components or circuitry commonly used to implement such components.
[0022] FIG.1 illustrates an exemplary block diagram representation of 5th
5 generation core (5GC) network architecture, in accordance with exemplary
implementation of the present disclosure.
[0023] FIG. 2 illustrates an exemplary block diagram of a computing device upon
which the features of the present disclosure may be implemented in accordance with
10 exemplary implementation of the present disclosure.
[0024] FIG. 3 illustrates an exemplary block diagram of a system for managing subscription of network functions, in accordance with exemplary implementations of the present disclosure. 15
[0025] FIG. 4 illustrates a method flow diagram for managing subscription of network functions, in accordance with exemplary implementations of the present disclosure.
20 [0026] FIG. 5 illustrates an exemplary process flow depicting receiving a
subscription response at the NF service consumer to enable management of stale subscription, in accordance with exemplary implementations of the present disclosure.
25 [0027] FIG. 6 illustrates an exemplary process flow depicting receiving a
notification response at the NSSF to enable management of stale subscription, in accordance with exemplary implementations of the present disclosure.
[0028] FIG. 7 illustrates an exemplary process flow depicting sending an
30 unsubscribing request to NSSF from AMF to enable deletion of stale subscription,
in accordance with exemplary implementations of the present disclosure.
8

[0029] The foregoing shall be more apparent from the following more detailed description of the disclosure.
5 DETAILED DESCRIPTION
[0030] 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
10 embodiments of the present disclosure may be practiced without these specific
details. Several features described hereafter may 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.
15
[0031] 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.
20 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.
[0032] Specific details are given in the following description to provide a thorough
25 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, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. 30
9

[0033] Also, it is noted that individual embodiments may be described as a process
which 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 may be performed in parallel or
5 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.
[0034] The word “exemplary” and/or “demonstrative” is used herein to mean
10 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
15 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—in a manner similar to the term “comprising” as an open transition word—without precluding any additional or other elements.
20
[0035] As used herein, a “processing unit” or “processor” or “operating processor” includes one or more processors, wherein processor refers to any logic circuitry for processing instructions. A processor may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor, a plurality
25 of microprocessors, one or more microprocessors in association with a Digital
Signal 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
30 the system according to the present disclosure. More specifically, the processor or
processing unit is a hardware processor.
10

[0036] As used herein, “a user equipment”, “a user device”, “a smart-user-device”,
“a smart-device”, “an electronic device”, “a mobile device”, “a handheld device”,
“a wireless communication device”, “a mobile communication device”, “a
5 communication device” may be any electrical, electronic and/or computing device
or equipment, capable of implementing the features of the present disclosure. The
user equipment/device may include, but is not limited to, a mobile phone, smart
phone, laptop, a general-purpose computer, desktop, personal digital assistant,
tablet computer, wearable device or any other computing device which is capable
10 of implementing the features of the present disclosure. Also, the user device may
contain at least one input means configured to receive an input from unit(s) which are required to implement the features of the present disclosure.
[0037] As used herein, “storage unit” or “memory unit” refers to a machine or
15 computer-readable medium including any mechanism for storing information in a
form readable by a computer or similar machine. For example, a computer-readable
medium includes read-only memory (“ROM”), random access memory (“RAM”),
magnetic disk storage media, optical storage media, flash memory devices or other
types of machine-accessible storage media. The storage unit stores at least the data
20 that may be required by one or more units of the system to perform their respective
functions.
[0038] As used herein “interface” or “user interface refers to a shared boundary
across which two or more separate components of a system exchange information
25 or data. The interface may also be referred to a set of rules or protocols that define
communication or interaction of one or more modules or one or more units with each other, which also includes the methods, functions, or procedures that may be called.
30 [0039] All modules, units, components used herein, unless explicitly excluded
herein, may be software modules or hardware processors, the processors being a
11

general-purpose processor, a special purpose processor, a conventional processor,
a digital signal processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a microcontroller,
Application Specific Integrated Circuits (ASIC), Field Programmable Gate Array
5 circuits (FPGA), any other type of integrated circuits, etc.
[0040] As used herein the transceiver unit include at least one receiver and at least
one transmitter configured respectively for receiving and transmitting data, signals,
information or a combination thereof between units/components within the system
10 and/or connected with the system.
[0041] As discussed in the background section, existing solutions have failed to effectively remove stale subscriptions from the Network Slice Selection Function (NSSF). These stale subscriptions can accumulate over time, leading to an
15 excessive number of notifications being sent to the NSSF and processed by network
function (NF) service consumers like the AMF, thereby exposing limitations in the current approach. The present disclosure seeks to address such challenges by providing a method and system for managing network function subscriptions. The proposed solution manages stale subscriptions by detecting a subscription response
20 at the NF service consumer from the NSSF and identifying a notification request
from the NSSF for a stale subscription ID at the NF service consumer.
[0042] FIG. 1 illustrates an exemplary block diagram representation of 5th generation core (5GC) network architecture [100], in accordance with exemplary
25 implementation of the present disclosure. As shown in FIG. 1, the 5GC network
architecture [100] includes a user equipment (UE) [102], a radio access network (RAN) [104], an access and mobility management function (AMF) [106], a Session Management Function (SMF) [108], a Service Communication Proxy (SCP) [110], an Authentication Server Function (AUSF) [112], a Network Slice Specific
30 Authentication and Authorization Function (NSSAAF) [114], a Network Slice
Selection Function (NSSF) [116], a Network Exposure Function (NEF) [118], a
12

Network Repository Function (NRF) [120], a Policy Control Function (PCF) [122],
a Unified Data Management (UDM) [124], an Application Function (AF) [126], a
User Plane Function (UPF) [128], and a Data Network (DN) [130], wherein all the
components are assumed to be connected to each other in a manner as obvious to
5 the person skilled in the art for implementing features of the present disclosure.
[0043] Radio Access Network (RAN) [104] is the part of a mobile
telecommunications system that connects user equipment (UE) [102] to the core
network and provides access to different types of networks (e.g., 5G network). It
10 consists of radio base stations and the radio access technologies that enable wireless
communication.
[0044] Access and Mobility Management Function (AMF) [106] is a 5G core
network function responsible for managing access and mobility aspects, such as UE
15 registration, connection, and reachability. It also handles mobility management
procedures like handovers and paging.
[0045] Session Management Function (SMF) [108] is a 5G core network function
responsible for managing session-related aspects, such as establishing, modifying,
20 and releasing sessions. It coordinates with the User Plane Function (UPF) for data
forwarding and handles IP address allocation and QoS enforcement.
[0046] Service Communication Proxy (SCP) [110] is a network function in the 5G
core network that facilitates communication between other network functions by
25 providing a secure and efficient messaging service. It acts as a mediator for service-
based interfaces.
[0047] Authentication Server Function (AUSF) [112] is a network function in the
5G core responsible for authenticating UEs during registration and providing
30 security services. It generates and verifies authentication vectors and tokens.
13

[0048] Network Slice Specific Authentication and Authorization Function (NSSAAF) [114] is a network function that provides authentication and authorization services specific to network slices. It ensures that UEs can access only the slices for which they are authorized. 5
[0049] Network Slice Selection Function (NSSF) [116] is a network function responsible for selecting the appropriate network slice for a UE based on factors such as subscription, requested services, and network policies.
10 [0050] Network Exposure Function (NEF) [118] is a network function that exposes
capabilities and services of the 5G network to external applications, enabling integration with third-party services and applications.
[0051] Network Repository Function (NRF) [120] is a network function that acts
15 as a central repository for information about available network functions and
services. It facilitates the discovery and dynamic registration of network functions.
[0052] Policy Control Function (PCF) [122] is a network function responsible for
policy control decisions, such as QoS, charging, and access control, based on
20 subscriber information and network policies.
[0053] Unified Data Management (UDM) [124] is a network function that centralizes the management of subscriber data, including authentication, authorization, and subscription information. 25
[0054] Application Function (AF) [126] is a network function that represents external applications interfacing with the 5G core network to access network capabilities and services.
14

[0055] User Plane Function (UPF) [128] is a network function responsible for handling user data traffic, including packet routing, forwarding, and QoS enforcement.
5 [0056] Data Network (DN) [130] refers to a network that provides data services to
user equipment (UE) in a telecommunications system. The data services may include but are not limited to Internet services, private data network related services.
[0057] The 5GC network architecture [100] also comprises a plurality of interfaces
10 for connecting the network functions with a network entity for performing the
network functions. The NSSF [116] is connected with the network entity via the interface denoted as (Nnssf) interface. The NEF [118] is connected with the network entity via the interface denoted as (Nnef) interface. The NRF [120] is connected with the network entity via the interface denoted as (Nnrf) interface. The PCF [122] is
15 connected with the network entity via the interface denoted as (Npcf) interface. The
UDM [124] is connected with the network entity via the interface denoted as (Nudm) interface. The AF [126] is connected with the network entity via the interface denoted as (Naf) interface. The NSSAAF [114] is connected with the network entity via the interface denoted as (Nnssaaf) interface. The AUSF [112] is connected with
20 the network entity via the interface denoted as (Nausf) interface. The AMF [106] is
connected with the network entity via the interface denoted as (Namf) interface. The SMF [108] is connected with the network entity via the interface denoted as (Nsmf) interface. The SMF [108] is connected with the UPF [128] via the interface denoted as (N4) interface. The UPF [128] is connected with the RAN [104] via the interface
25 denoted as (N3) interface. The UPF [128] is connected with the DN [130] via the
interface denoted as (N6) interface. The RAN [104] is connected with the AMF [106] via the interface denoted as (N2). The AMF [106] is connected with the RAN [104] via the interface denoted as (N1). The UPF [128] is connected with other UPF [128] via the interface denoted as (N9). The interfaces such as Nnssf, Nnef, Nnrf, Npcf,
30 Nudm, Naf, Nnssaaf, Nausf, Namf, Nsmf, N9, N6, N4, N3, N2, and N1 can be referred to
as a communication channel between one or more functions or modules for
15

enabling exchange of data or information between such functions or modules, and network entities.
[0058] FIG. 2 illustrates an exemplary block diagram of a computing device [200]
5 (hereinafter also referred to as a computer system [200]) upon which one or more
features of the present disclosure may be implemented, in accordance with an
exemplary implementation of the present disclosure. The computing device [200]
may implement a method for managing subscription of network functions, utilising
a system, or one or more sub-systems, provided in the network. In another
10 implementation, the computing device [200] itself implements the method for
managing subscription of network functions, using one or more units configured within the computing device [200], wherein said one or more units are capable of implementing the features as disclosed in the present disclosure.
15 [0059] The computing device [200] may include a bus [202] or other
communication mechanism(s) for communicating information, and a hardware processor [204] coupled with bus [202] for processing said information. The hardware processor [204] may be, for example, a general-purpose microprocessor. The computing device [200] may also include a main memory [206], such as a
20 random-access memory (RAM), or other dynamic storage device, coupled to the
bus [202], for storing information and instructions to be executed by the processor [204]. The main memory [206] also may be used for storing temporary variables or other intermediate information during execution of the instructions to be executed by the processor [204]. Such instructions, when stored in a non-transitory storage
25 media accessible to the processor [204], render the computing device [200] into a
special purpose device that is customized to perform operations according to the instructions. The computing device [200] further includes a read only memory (ROM) [208] or other static storage device coupled to the bus [202] for storing static information and instructions for the processor [204].
30
16

[0060] A storage device [210], such as a magnetic disk, optical disk, or solid-state
drive is provided and coupled to the bus [202] for storing information and
instructions. The computing device [200] may be coupled via the bus [202] to a
display [212], such as a cathode ray tube (CRT), Liquid crystal Display (LCD),
5 Light Emitting Diode (LED) display, Organic LED (OLED) display, etc., for
displaying information to a user of the computing device [200]. An input device [214], including alphanumeric and other keys, touch screen input means, etc. may be coupled to the bus [202] for communicating information and command selections to the processor [204]. Another type of user input device may be a cursor
10 controller [216], such as a mouse, a trackball, or cursor direction keys, for
communicating direction information and command selections to the processor [204], and for controlling cursor movement on the display [212]. The cursor controller [216] typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the cursor controller [216] to specify
15 positions in a plane.
[0061] The computing device [200] may implement the techniques described herein using customized hard-wired logic, one or more ASICs or FPGAs, firmware and/or program logic which, in combination with the computing device [200],
20 causes or programs the computing device [200] to be a special-purpose device.
According to one implementation, the techniques herein are performed by the computing device [200] in response to the processor [204] executing one or more sequences of one or more instructions contained in the main memory [206]. The one or more instructions may be read into the main memory [206] from another
25 storage medium, such as the storage device [210]. Execution of the one or more
sequences of the one or more instructions contained in the main memory [206] causes the processor [204] to perform the process steps described herein. In alternative implementations of the present disclosure, hard-wired circuitry may be used in place of, or in combination with, software instructions.
30
17

[0062] The computing device [200] also may include a communication interface
[218] coupled to the bus [202]. The communication interface [218] provides two-
way data communication coupling to a network link [220] that is connected to a
local network [222]. For example, the communication interface [218] may be an
5 integrated services digital network (ISDN) card, cable modem, satellite modem, or
a modem to provide a data communication connection to a corresponding type of
telecommunication line. In another example, the communication interface [218]
may be a local area network (LAN) card to provide a data communication
connection to a compatible LAN. Wireless links may also be implemented. In any
10 such implementation, the communication interface [218] sends and receives
electrical, electromagnetic or optical signals that carry digital data streams representing different types of information.
[0063] The computing device [200] can send and receive data, including program
15 code, messages, etc. through the network(s), the network link [220] and the
communication interface [218]. In an example, a server [230] might transmit a
requested code for an application program through the Internet [228], the ISP [226],
the local network [222], the host [224] and the communication interface [218]. The
received code may be executed by the processor [204] as it is received, and/or stored
20 in the storage device [210], or other non-volatile storage for later execution.
[0064] Referring to FIG. 3, an exemplary block diagram of a system [300] for managing subscription of network functions is shown, in accordance with exemplary implementations of the present disclosure. The system [300] comprises
25 at least one transceiver unit [302], at least one determination unit [304], at least one
subscription unit [306], at least one storage unit [308], and at least one processing unit [310]. Also, all of the components/ units of the system [300] are assumed to be connected to each other unless otherwise indicated below. As shown in FIG. 3, all units shown within the system [300] should also be assumed to be connected to
30 each other. Also, in FIG. 3, only a few units are shown, however, the system [300]
may comprise multiple such units or the system [300] may comprise any such
18

number of said units, as required to implement the features of the present disclosure.
Further, in an implementation, the system [300] may be present in a user device/
user equipment [102] to implement the features of the present disclosure. The
system [300] may be a part of the user device [102]/ or may be independent of but
5 in communication with the user device [102] (may also referred herein as a UE). In
another implementation, the system [300] may reside in a server or a network entity. In yet another implementation, the system [300] may reside partly in the server/ network entity and partly in the user device.
10 [0065] The system [300] is configured to manage subscription of network
functions, with the help of the interconnection between the components/units of the system [300].
[0066] Further, in accordance with the present disclosure, it is to be acknowledged
15 that the functionality described for the various components/units can be
implemented interchangeably. While specific embodiments may disclose a
particular functionality of these units for clarity, it is recognized that various
configurations and combinations thereof are within the scope of the present
disclosure. The functionality of specific units as disclosed in the present disclosure
20 should not be construed as limiting the scope of the present disclosure.
Consequently, alternative arrangements and substitutions of units, provided they achieve the intended functionality described herein, are considered to be encompassed within the scope of the present disclosure.
25 [0067] The system [300] comprises a transceiver unit [302] connected to at least
one network function (NF). The transceiver unit [302] is configured to receive, from a target service function, a notification request. In an implementation, the notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function. The term “SID”
30 herein may represent a unique identifier associated with a subscription of a
particular NF at the target service function. In one implementation, the at least the
19

one NF is an Access and Mobility Management Function (AMF) [106]. Further, the
target service function is a network slice service function (NSSF) [116]. The NSSF
[116] is a network function responsible for selecting the appropriate network slice
for a user equipment (UE) based on factors such as subscription, requested services,
5 network policies, and the like. Furthermore, the AMF [106] is responsible for
managing access and mobility aspects, such as UE registration, connection, reachability, and the like.
[0068] The term “unique SID” herein may refer to a unique identifier that is
10 associated with the subscription of a particular NF (such as, the AMF [106]) to a
specific network slice which is managed by the NSSF [116].
[0069] In an implementation, in case of an event, the target network service function (such as the NSSF [116]) may send a notification request to the at least
15 one NF (such as the AMF [106]) to inform the AMF [106], regarding any changes
or updates in a slice authorized data (from the NSSF [116]) which is allocated to the AMF [106]. Further, the notification request may include information such as a modification in the network slice configuration, deactivation of the network slice configuration, issue within the network slice configuration, and the like.
20
[0070] In one implementation, prior to receiving, from the target service function (such as the NSSF [116]), the notification request, the transceiver unit [302] is configured to transmit from the at least one NF (such as the AMF [106]), a subscription request to the target service function. Herein, the AMF [106], via the
25 transceiver unit [302], may send the subscription request to the NSSF [116], to
receive the notification request from the NSSF [116] in future. The subscription request may include information that the NSSF [116] may allocate an appropriate network slice to the AMF [106]. The allocation of the appropriate network slice is based on the requirement of the AMF [106] for one or more services.
30
20

[0071] In an example, the one or more services required by the AMF [106] may
include a network slice selection function - network slice (Nnssf_NS) selection
service which may allow the at least one NF (such as the AMF [106]) to retrieve
the information related to network slice in non-roaming and roaming case. The
5 Nnssf_NS selection service may further enable the NSSF to provide an allowed
network slice selection assistance information (NSSAI) and configured NSSAI for a serving public land mobile network (PLMN) to the AMF. The Nnssf_NS selection service also enables the NSSF to provide a network slice as group (NSAG) information associated with the configured NSSAI for the serving PLMN to the
10 AMF. The NSAG information is used to identify a specific network slice or a
collection of slices within a particular Tracking Area (TA). The NSAG information is further utilized in managing the Quality of Service (QoS) and resource allocation based on the characteristics of the slices being utilized. Further, the term “tracking area (TA)” mentioned herein is referred to as a grouping of cells over a particular
15 area.
[0072] In another example, the one or more services required by the AMF [106] may include a Nnssf_NSSAI availability service which is used by the at least one NF (such as the AMF [106]) to update single network slice selection assistance
20 information (S-NSSAIs) on a per tracking area (TA) based on the NSSF. The
updated S-NSSAI information per TA assists the NSSF to determine the appropriate network slices for UEs in each TA. The Nnssf_NSSAI availability service may further offer the AMF [106] to subscribe and unsubscribe the notification of any changes to the NSSAI availability information on a per Tracking Area (TA) basis,
25 of the S-NSSAIs available per TA (unrestricted) and the restricted S-NSSAI(s) per
PLMN in that TA in the serving PLMN of the UE [102].
[0073] In an implementation, post processing the subscription request, a response labelling “201 Created” is returned to the at least one NF. Further, the response may
21

describe the status of the created status of the created subscription and may contain other necessary information.
[0074] Further, the transceiver unit [302] may receive at least one NF (such as the
5 AMF [106]), from the target service function (such as the NSSF [116]), in response
to the subscription request, the unique SID. Post receiving the subscription request,
the NSSF [116] may further process the subscription request and assign the unique
SID to the AMF [106]. The transceiver unit [302] may further receive the unique
SID assigned by the NSSF [116]. The unique SID may act as the identifier that
10 identifies a subscription between the NSSF [116] and the AMF [106].
[0075] Further, the system [300] comprises the storage unit [308]. The storage unit
[308] is connected at least to the transceiver unit [302]. In addition, the storage unit
[308] is configured to store the received unique SID in a database [312]. Post
15 receiving the unique SID from the NSSF [116], the storage unit [308] may further
store the received unique SID in the database [312] associated with the AMF [106].
[0076] Furthermore, the system [300] comprises the determination unit [304]. The determination unit [304] is connected to the at least one NF (such as the AMF
20 [106]). The determination unit [304] is configured to determine a match between
the received unique SID and a set of subscription IDs associated with the NF. In particular, the determination unit [304] is configured to verify validity of subscription information associated with the network slice allocated to the AMF [106]. Further, the stored set of subscription IDs are stored in the database [312]
25 connected to at least the one NF. The determination unit [304] may compare the
unique SID from the target service function (such as the NSSF [116]), with the one or more subscription IDs stored in the database [312].
[0077] In case the determination unit [304] finds a subscriber ID in the database
30 [312], which is same as the unique SID, the determination unit [304] is configured
to confirm that the received unique SID is valid and corresponds to an existing
22

subscription of the AMF [106]. Thereafter, the AMF [106] is configured to proceed with one or more subsequent actions. The one or more subsequent actions include, but may not be limited to, updating the network slice configuration, handling notifications, and the like. 5
[0078] In such cases, the subscription unit [306] is configured to generate a response such as “204 No Content” which may represent a successful update of the at least NF (such as the AMF [106]) with NSSAI availability information.
10 [0079] The system [300] further comprises the subscription unit [306]. The
subscription unit [306] is connected to the at least one NF (such as the AMF [106]). In case the determination unit [304] is unable to find any subscription ID in the database [312], which is same as the unique SID, the determination unit [304] is configured to confirm that the received unique SID is invalid and does not
15 correspond to an existing subscription of the AMF [106].
[0080] In this case, the subscription unit [306] is configured to generate an error
message indicative of the negative match between the received unique SID and the
stored set of subscription IDs. Examples of the error message may include error 404
20 (i.e., SID not found), error 403 (i.e., invalid SID), error 410 (i.e., SID expired), error
400 (i.e., bad request) and the like. It is to be noted that the error message may vary depending on the specific implementation and requirements set forth by a network operator.
25 [0081] Further, the transceiver unit [302] is configured to transmit, to the target
service function, a notification comprising the error message. After generation of the error message, the transceiver unit [302] is configured to transmit the error message to the target service function (such as the NSSF [116]). The purpose of transmitting the error message to the NSSF [116] is to notify the NSSF [116] that
30 the notification request is not completed along with the reason mentioned in the
23

error message. Upon receiving the error message, the NSSF [116] may perform one or more corrective actions based on the reason of the error message.
[0082] Further, the transceiver unit [302] is configured to transmit an unsubscribing
5 request to the target service function (such as the NSSF [116]). The unsubscribing
request is transmitted for revocation of the subscription of the at least one NF (such as the AMF [106]) with the target service function. The unsubscribing request may include data (such as SID or other details) which may assist in identifying the specific subscription that is to be revoked by the NSSF [116].
10
[0083] In an implementation, in cases where the error message may correspond to the error 404 (i.e., SID not found), the NSSF [116] via the processing unit [310] may automatically delete subscriptions associated with the at least one NF (such as the AMF [106]).
15
[0084] Moreover, the system [300] comprises a processing unit [310] connected at least to the target service function (such as the NSSF [116]). Upon receiving the unsubscribing request at the target service function, the processing unit [310] is configured to remove the subscription of the at least one NF from the target service
20 function. Upon receiving the unsubscribing request, the NSSF [116] may further
process the request and then revoke the subscription. The revoke of the subscription may refer to removing or disabling the subscription in such a way that the AMF [106] may no longer access the network slice or services associated with the revoked subscription.
25
[0085] Post removing of any unnecessary subscription, the at least one NF (such as the AMF [106]) may not receive any unnecessary requests from the target service function (such as the NSSF [116]) and vice versa. Thus, any unnecessary processing and verification of stale subscriptions is eliminated. Therefore, the operational
30 efficiency of the at least one NF (such as the AMF [106]) and the target service
functions (such as the NSSF [116]) is significantly improved.
24

[0086] Referring to FIG. 4, an exemplary method flow diagram [400] for managing
subscription of network functions, in accordance with exemplary implementations
of the present disclosure is shown. In an implementation, the method [400] is
5 performed by the system [300]. In an implementation, the system [300] may be
present in a server device to implement the features of the present disclosure.
[0087] The method [400] initiates at step [402].
10 [0088] At step [404], the method [400] comprises receiving, by the transceiver unit
[302] connected to at least one network function (NF), from the target service function, the notification request. In an implementation, the notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function.
15
[0089] In one implementation, at least the one NF is an Access and Mobility Management Function (AMF) [106]. In addition, the target service function is a network slice service function (NSSF) [116]. Further, the subscription request relates to a requirement, by the AMF [106], of a change in slice authorized data
20 from the NSSF [116].
[0090] Prior to receiving the notification request from the target service function, the method [400] comprises transmitting, by the transceiver unit [302], from the at least one NF, a subscription request to the target service function. In response to the
25 subscription request, the method [400] comprises receiving, by the transceiver unit
[302], the unique SID at the at least one NF. In addition, the unique SID is received from the target service function. Further, the method [400] comprises storing, by the storage unit [308] connected at least to the transceiver unit [302], the received unique SID in the database [312].
30
25

[0091] At step [406], the method [400] comprises determining, by the
determination unit [304] connected to at least the one NF, a match between the
received unique SID and a set of subscription IDs associated with the NF. In
particular, the set of subscription IDs are stored in the database [312] connected to
5 at least the one NF.
[0092] At step [408], in response to a negative match between the received unique
SID and any subscription ID from the stored set of subscription IDs, the method
[400] comprises generating, by the subscription unit [306] connected to at least the
10 one NF, an error message indicative of the negative match between the received
unique SID and the stored set of subscription IDs.
[0093] The method [400] further comprises transmitting, by the transceiver unit [302], a notification comprising the error message to the target service function.
15
[0094] In response to the negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, at step [410], the method [400] comprises transmitting, by the transceiver unit [302], an unsubscribing request to the target service function. The unsubscribing request is transmitted for
20 revocation of the subscription of the at least one NF with the target service function.
[0095] In response to the received unsubscribing request at the target service
function, the method [400] comprises removing, by the processing unit [310]
connected at least to the target service function, the subscription of the at least one
25 NF from the target service function.
[0096] The method [400] terminates at step [412].
[0097] Referring to FIG. 5, an exemplary process flow diagram [500] depicting
30 receiving the subscription response at the network function (NF) service consumer
to enable management of stale subscription, in accordance with exemplary
26

implementations of the present disclosure is shown. In an implementation, the process flow diagram [500] is performed by one or more units of the system [300].
[0098] The process flow diagram [500] depicts the interaction between the NF
5 service consumer (such as the Access and Mobility Management Function (AMF)
[106]), and a target service function (such as the Network Slice Selection Function (NSSF) [116]), during subscription process.
[0099] At step [502], the NF service consumer (such as the AMF [106]) sends a
10 subscription request to the NSSF [116].
[0100] At step [504], the NSSF [116] processes the subscription request. In one
implementation, the NSSF [116] validates the subscription request. Further, the
NSSF [116] sends a subscription response to the NF service consumer in response
15 to the subscription request.
[0101] Referring to FIG. 6, an exemplary process flow diagram [600] depicting
receiving a subscription response at the NF service consumer to enable management
of stale subscription, in accordance with exemplary implementations of the present
20 disclosure is shown. In an implementation, the process flow diagram [600] is
performed by one or more units of the system [300]. FIG. 6 can be used in conjunction with the FIG. 5.
[0102] At step [602], the NSSF [116] sends a notification request to the NF service
25 consumer (e.g., the AMF [106]). The notification request may include a request to
perform any updates or changes that needs to be communicated to the NSSF [116].
[0103] At step [604], the NF service consumer (e.g., the AMF [106]) processes the
notification request. Upon processing the notification request, the NF service
30 consumer (e.g., AMF [106]) may then transmit a notification response back to the
NSSF [116].
27

[0104] Referring to FIG. 7, an exemplary process flow [700] depicting receiving a
notification response at the NSSF [116] to enable management of stale subscription,
in accordance with exemplary implementations of the present disclosure is shown.
5 In an implementation, the process flow diagram [700] is performed by one or more
units of the system [300]. FIG. 7 is used in conjunction with FIG. 5 and FIG. 6.
[0105] At step [702], the NF service consumer (e.g., the AMF [106]) sends an unsubscribing request to the NSSF [116]. The unsubscribing request indicates that
10 the NF service consumer (e.g., the AMF [106]) wants to unsubscribe from a
particular service. The NF service consumer (e.g., the AMF [106]), based on processing of the notification request, may acknowledge that the NF service consumer (e.g., AMF [106]) may encounter one or more situations such as a unique subscriber’s identification (ID) present in the notification request is either expired,
15 or is revoked already, or belongs to an unauthorized subscription.
[0106] At step [704], the NSSF [116] processes the unsubscribing request. Upon revoking the subscription, the NSSF [116] sends back an unsubscribing response to the NF service consumer (e.g., the AMF [106]).
20
[0107] As is evident from the above, the present disclosure provides a technically advanced solution for managing subscription of network function subscriptions. The present disclosure addresses management of stale subscriptions by detecting subscription responses and consumer from the NSSF [116] and a detection of a
25 notification request from the NSSF [116], for a stale subscription ID at the NF
service consumer. Also, the solution as disclosed in the present disclosure overcomes the technical limitations of removal of stale subscriptions from the NSSF [116] which may grow overtime and create a problem for sending so many notifications to the NSSF [116], and the solution as disclosed in the present
30 disclosure may further overcome the technical limitations related to processing of
28

multiple subscription-condition based notifications for network function (NF) service consumer such as AMF [106].
[0108] While considerable emphasis has been placed herein on the disclosed implementations, it will be appreciated that many implementations can be made and that many changes can be made to the implementations without departing from the principles of the present disclosure. These and other changes in the implementations of the present disclosure will be apparent to those skilled in the art, whereby it is to be understood that the foregoing descriptive matter to be implemented is illustrative and non-limiting.

We Claim:
1. A method [400] for managing subscription of network functions, the method
[400] comprising:
- receiving, by a transceiver unit [302] connected to at least one network function (NF), from a target service function, a notification request, wherein the notification request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function;
- determining, by a determination unit [304] connected to at least the one NF, a match between the received unique SID, and a stored set of subscription IDs associated with the NF, wherein the set of subscription IDs are stored in a database [312] connected to at least the one NF,
wherein, in response to a negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, the method [400] comprises:
- generating, by a subscription unit [306] connected to at least the one NF, an error message indicative of the negative match between the received unique SID and the stored set of subscription IDs; and
- transmitting, by the transceiver unit [302], an unsubscribing request to the target service function, the unsubscribing request related to a revocation of the subscription of the at least one NF with the target service function.
2. The method [400] as claimed in claim 1, wherein, prior to receiving, from
the target service function, the notification request, the method [400]
comprises:

- transmitting, by the transceiver unit [302], from the at least one NF, a subscription request to the target service function;
- receiving, by the transceiver unit [302], at the at least one NF, from the target service function, in response to the subscription request, the unique SID; and
- storing, by a storing unit [308] connected at least to the transceiver unit [302], in the database [312], the received unique SID.

3. The method [400] as claimed in claim 1, wherein the method [400] comprises transmitting, by the transceiver unit [302], to the target service function, a notification comprising the error message.
4. The method [400] as claimed in claim 1, wherein the method [400] comprises removing, by a processing unit [310] connected at least to the target service function, in response to the received unsubscribing request at the target service function, the subscription of the at least one NF from the target service function.
5. The method [400] as claimed in claim 1, wherein at least one of the NF is an Access and Mobility Management Function (AMF) [106], wherein the target service function is a network slice service function (NSSF) [116], and wherein the subscription request relates to a requirement, by the AMF [106], of a change in slice authorized data from the NSSF [116].
6. A system [300] for managing subscription of network functions, the system [300] comprising:
- a transceiver unit [302] connected to at least one network function
(NF), the transceiver unit [302] configured to receive, from a target
service function, a notification request, wherein the notification

request comprises a unique subscriber identifier (SID) associated with subscription of the at least one NF at the target service function;
- a determination unit [304] connected to the at least one NF, the determination unit [304] configured to determine a match between the received unique SID, and a set of subscription IDs associated with the NF, wherein the set of subscription IDs are stored in a database [312] connected to at least the one NF;
- a subscription unit [306] connected to the at least one NF, wherein, in response to a negative match between the received unique SID, and any subscription ID from the stored set of subscription IDs, the subscription unit [306] is configured to generate an error message indicative of the negative match between the received unique SID and the stored set of subscription IDs; and
- the transceiver unit [302] configured to transmit an unsubscribing request to the target service function, wherein the unsubscribing request is transmitted for revocation of the subscription of the at least one NF with the target service function.
7. The system [300] as claimed in claim 6, wherein, prior to receiving, from the target service function, the notification request:
- the transceiver unit [302] is configured to:
- transmit, from the at least one NF, a subscription request to the target service function; and
- receive, at the at least one NF, from the target service function, in response to the subscription request, the unique SID; and
- a storing unit [308], connected at least to the transceiver unit [302],
is configured to store, in the database [312], the received unique SID.

8. The system [300] as claimed in claim 6, wherein the transceiver unit [302] is configured to transmit, to the target service function, a notification comprising the error message.
9. The system [300] as claimed in claim 6, wherein the system [300] comprises a processing unit [310] connected at least to the target service function, wherein the processing unit [310] configured to remove, in response to the received unsubscribing request at the target service function, the subscription of the at least one NF from the target service function.
10. The system [300] as claimed in claim 6, wherein at least the one NF is an Access and Mobility Management Function (AMF) [106], wherein the target service function is a network slice service function (NSSF) [116], and wherein the subscription request relates to a requirement, by the AMF [106], of a change in slice authorized data from the NSSF [116].