Method and system for service continuity in a communication network

Abstract

The present disclosure relates to a method and a system for service continuity in a communication network. The method [400] comprises transmitting a first re-discovery message and receiving a first re-discovery response. The method [400] further comprises maintaining a cache with profiles of discovered NFs, based on the first re-discovery response. Further, the method [400] comprises selecting a second NRF and transmitting to the second NRF, a second re-discovery message based on the first re-discovery response. Also, the method [400] comprises receiving a second re-discovery response from the second NRF, based on the second re-discovery message. The second re-discovery response is one of a successful response and an unsuccessful response. Thereafter, the method [400] comprises updating the cache with the second re-discovery response in an event the second re-discovery response is the successful response.

Description

METHOD AND SYSTEM FOR SERVICE CONTINUITY IN A COMMUNICATION NETWORKFIELD OF THE DISCLOSURE

[0001] Embodiment of the present disclosure may generally relate to the field of wireless communication systems. More particularly, the present disclosure relates to method and system for service continuity in a communication network.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. The third generation (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 centred around network function (NF) services. In the service-based architecture, a set of interconnected Network Functions (NFs) deliver the control plane functionality and common data repositories of the 5G network, where each NF is authorized to access services of other NFs. Particularly, each NF can register itself and its supported services to a Network RepositoryFunction (NRF), which is used by other NFs for the discovery of NF instances and their services. The NRF therefore supports functions related to 1) maintaining the profiles of the available network function (NF) instances and their supported services in the 5G core network, 2) allowing NF instances to discover other NF instances in the 5G core network, and 3) allowing the NF instances to track the status of other NF instances. The ‘NnrfJNFDiscovery’ service allows a NF service consumer to discover other NF Instances with the potential services they offer, by querying the NRF. The ‘NFDiscover’ operation of the ‘NnrfJNFDiscovery’ service provides to the NF service consumer the profiles (including IP address(es) or FQDN) of the NF Instance(s) or NF Service(s) matching certain input criteria. The ‘NFDiscover’ operation can be invoked by an NF Service Consumer (i.e., "source NF") requesting to discover NF instances (i.e., "target NFs") located in the same Public Land Mobile Network (PLMN), or in a different PLMN.

[0005] Currently, as soon as the NF is registered at the network repository function (NRF), various ways defined by the 3 GPP standard are followed that enable an immediate traffic flow at the NF. When an NF consumer sends the discovery request towards the NRF, the NRF responds back with a “Search Result”, the “validity period”, during which the search result can be cached by the NF Service Consumer, and an array of NF Profile objects, that satisfy the search filter criteria (e.g., all NF Instances offering a certain NF Service name). This validity period indicates the time in second for which discovery result is considered valid at the NF consumer and is cached locally by the NF consumer for reuse. The NF consumer will generally again execute the discovery procedure before the expiry of this validity time to refresh the cache if need be. If the NF consumer already has cached the discovery response, and if before validity expiry, the NF is trying the discovery procedure again, it may receive a response that the NRF is not available at that time. This unavailability of the NRF may cause the following issues:Post validity period expiry: The NF will remove the earlier discovered entries as the validity period have expired. This will essentially mean that the producer NFs that were being used by the consumer NF based on the discovery results will no longer be available at consumer NFsPotential impact on service: As the producer NFs are not discoverable by the consumer NF due to the NRF unavailability and expiry of the validity period, the service offered by the NFs will also get impacted.

[0006] Hence, in view of these and other existing limitations, there arises an imperative need to provide an efficient solution to overcome the above-mentioned and other limitations and to provide a method and a system for service continuity in a communication network.SUMMARY

[0007] 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.

[0008] An aspect of the present disclosure may relate to a method for service continuity in a communication network. The method comprises transmitting, by a transceiver unit from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message. Further, the method comprises receiving, by the transceiver unit at the NF, a first re-discovery response based on the first re-discovery message. The method further comprises maintaining, by a processing unit at the NF, a cache with profiles of discovered NF s, based on the first re-discovery response. Further, the method comprises selecting, by an identification unit at the NF, aa second NRF. Furthermore, the method comprises transmitting, by the transceiver unit at the NF, to the second NRF, a second re-discovery message based on the first re-discovery response. Also, the method comprises receiving, by the transceiver unit at the NF, a second re-discovery response from the second NRF, based on the second re-discovery message. The second re-discovery response is one of a successful response and an unsuccessful response. Thereafter, the method comprises updating, by the processing unit at the NF, the cache with the second re-discovery response in an event the second re-discovery response is the successful response.

[0009] In an exemplary aspect of the present disclosure, prior to transmitting the first re-discovery message from the NF to the NRF, the method comprises: 1) transmitting, by the transceiver unit at the NF, a discovery request to an NRF; 2) receiving, by the transceiver unit at the NF, a discovery response from the NRF; and 3) storing, by the processing unit at the NF, the discovery response in the cache.

[0010] In an exemplary aspect of the present disclosure, the discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period.

[0011] In an exemplary aspect of the present disclosure, the first re-discovery response is one of a negative response and a timeout response which is received at the NF from a Service Communication Proxy (SCP).

[0012] In an exemplary aspect of the present disclosure, the negative response and the timeout response received at the NF from the NRF indicates unavailability of the first NRF.

[0013] In an exemplary aspect of the present disclosure, the first discovery message and the second discovery message are transmitted by the NF based on an internal timer at the NF.

[0014] In an exemplary aspect of the present disclosure, the second NRF is selected by the NF from a list of one or more NRFs maintained at the NF.

[0015] In an exemplary aspect of the present disclosure, the second re-discovery response comprises profiles of discovered NF s, wherein each of the profile of discovered NFs is associated with a validity period.

[0016] In an exemplary aspect of the present disclosure, the cache is updated with the profiles of discovered NFs by overwriting the profiles of earlier discovered NFs.

[0017] In an exemplary aspect of the present disclosure, the NF raises an alert when the validity period associated with each of the profile of earlier discovered NFs expires.

[0018] In an exemplary aspect of the present disclosure, the alert is sent to notify one or more NF service consumers that NF is using the cached profiles of earlier discovered NFs for providing service.

[0019] Another aspect of the present disclosure may relate to a system for service continuity in a communication network. The system comprises a transceiver unit, configured to transmit, from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message. Further, the transceiver unit is configured to receive at the NF, a first re-discovery response based on the first re-discovery message. The system further comprises a processing unit connected to at least the transceiver unit, the processing unit is configured to maintain a cache with profiles of discovered NFs, based on the first re-discovery response. Further, the system comprises an identification unit connected to at least the processing unit at the NF, the identification unit is configured to select, a second NRF. Furthermore, the transceiver unit is configured transmit to the second NRF, a second re-discovery message based on the first re-discovery response. Also, the transceiver unit is configured to receive a second re-discovery response from the second NRF, based on the second re-discovery message. The second re-discovery response is one of a successful response and an unsuccessful response. Moreover, the processing unit is configured to update thecache with the second re-discovery response in an event the second re-discovery response is the successful response.

[0020] Yet another aspect of the present disclosure may relate to a non-transitory computer- readable storage medium storing one or more instructions for service continuity in a communication network the storage medium comprising executable code which, when executed by one or more units of a system, causes a transceiver unit, of the system, to transmit, from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message. The executable code when executed further causes the transceiver unit to receive at the NF, a first re-discovery response based on the first re-discovery message. Further, the executable code when executed causes a processing unit, of the system, to maintain a cache with profiles of discovered NFs, based on the first re-discovery response. Further, the executable code when executed causes an identification unit, of the system, to select, a second NRF. Furthermore, the executable code when executed causes the transceiver unit to transmit to the second NRF, a second re-discovery message based on the first re-discovery response. Also, the executable code when executed further causes the transceiver unit to receive a second re-discovery response from the second NRF, based on the second re-discovery message. The second re-discovery response is one of a successful response and an unsuccessful response. Moreover, the executable code when executed causes the processing unit to update the cache with the second re-discovery response in an event the second re-discovery response is the successful response.OBJECTS OF THE DISCLOSURE

[0021] Some of the objects of the present disclosure which at least one embodiment disclosed herein satisfies are listed herein below.

[0022] It is an object of the present disclosure to provide a method and a system for service continuity in a communication network.

[0023] It is another object of the present disclosure to provide a solution that even in case of discovery failure, network functions (NFs) will retry in configurable time towards network repository function (NRF) so that cached data can be refreshed as soon as possible.

[0024] It is yet another object of the present disclosure to provide a solution to support multiple alternate NRF configuration so that discovery can be tried with alternate NRF in case of failure of a primary NRF providing better chances of success.

[0025] It is yet another object of the present disclosure to provide a solution that even in case rediscovery is not successful, data from previous discovery will be kept in cache for indefinite time.

[0026] It is yet another object of the present disclosure to provide a solution that event after the validity period has expired NRF will keep service live even if re-discovery from NRF fails.BREIF DESCRIPTION OF DRAWINGS

[0027] 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.

[0028] FIG. 1 illustrates an exemplary block diagram representation of 5th generation core (5GC) network architecture.

[0029] 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 exemplary implementation of the present disclosure.

[0030] FIG. 3 illustrates an exemplary block diagram of a system for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure.

[0031] FIG. 4 illustrates an exemplary signalling flow diagram depicting a process for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure.

[0032] FIG. 5 illustrates an exemplary flow diagram of a method for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure.

[0033] The foregoing shall be more apparent from the following more detailed description of the disclosure.DETAILED DESCRIPTION

[0034] 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 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.

[0035] 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.

[0036] 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, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail.

[0037] 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 concurrently. In addition, the order of the operations may be re-arranged. A process may be terminated when its operations are completed but could also have additional steps that may not be included in the figures.

[0038] 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 in a manner similar to the term “comprising” as an open transition word without precluding any additional or other elements.

[0039] 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 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 the system according to the present disclosure. More specifically, the processor or processing unit is a hardware processor.

[0040] As used herein, “a user equipment”, “a user device”, “a smart-user-device”, “a smartdevice”, “an electronic device”, “a mobile device”, “a handheld device”, “a wireless communication device”, “a mobile communication device”, “a 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 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.

[0041] As used herein, “storage unit” or “memory unit” refers to a machine or 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 that may be required by one or more units of the system to perform their respective functions.

[0042] As used herein “interface” or “user interface refers to a shared boundary across which two or more separate components of a system exchange information 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.

[0043] All modules, units, components used herein, unless explicitly excluded herein, may be software modules or hardware processors, the processors being a 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 circuits (FPGA), any other type of integrated circuits, etc.

[0044] As used herein the transceiver unit includes 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 and / or connected with the system.

[0045] As discussed in the background section, the current known solutions have several shortcomings. The present disclosure aims to overcome the above-mentioned and other existing problems in this field of technology by providing method and system for service continuity in a communication network. More particularly, the present disclosure provides a solution that even in case of discovery failure, network functions (NFs) will retry in configurable time towards network repository function (NRF) so that cached data can be refreshed as soon as possible. Further, the present disclosure provides a solution to support multiple alternate NRF configuration so that discovery can be tried with alternate NRF in case of failure of the primary NRF providing better chances of success. Furthermore, the present disclosure provides a solution that even in case rediscovery is not successful, data from previous discovery will be kept in cache for indefinite time. Moreover, the present disclosure provides a solution that even after the validity period has expired NRF will keep service live even if re-discovery from NRF fails.

[0046] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0047] Referring to FIG. 1, an exemplary block diagram representation of 5th generation core (5GC) network architecture, in accordance with exemplary implementation of the present disclosure, is shown. As depicted in FIG. 1, the 5GC network architecture

[0100] includes a user equipment (UE)

[0102] , a radio access network (RAN)

[0104] , an access and mobility management function (AMF)

[0106] , a Session Management Function (SMF)

[0108] , a Service Communication Proxy (SCP)

[0110] , an Authentication Server Function (AUSF)

[0112] , a Network Slice Specific Authentication and Authorization Function (NSSAAF)

[0114] , a Network Slice Selection Function (NSSF)

[0116] , a Network Exposure Function (NEF)

[0118] , a Network Repository Function (NRF)

[0120] , a Policy Control Function (PCF)

[0122] , a Unified Data Management (UDM)

[0124] , an application function (AF)

[0126] , a User Plane Function (UPF)

[0128] , a data network (DN)

[0130] , wherein all the components are assumed to be connected to each other in a manner as obvious to the person skilled in the art for implementing features of the present disclosure.

[0048] Radio Access Network (RAN)

[0104] is the part of a mobile telecommunications system that connects user equipment (UE)

[0102] to the core network (CN) and provides access to different types of networks (e.g., 5G network). It consists of radio base stations and the radio access technologies that enable wireless communication.

[0049] Access and Mobility Management Function (AMF)

[0106] is a 5G core network function responsible for managing access and mobility aspects, such as UE registration, connection, and reachability. It also handles mobility management procedures like handovers and paging.

[0050] Session Management Function (SMF)

[0108] is a 5G core network function responsible for managing session-related aspects, such as establishing, modifying, and releasing sessions. It coordinates with the User Plane Function (UPF) for data forwarding and handles IP address allocation and QoS enforcement.

[0051] Service Communication Proxy (SCP)

[0110] is a network function in the 5G core network that facilitates communication between other network functions by providing a secure and efficient messaging service. It acts as a mediator for service-based interfaces.

[0052] Authentication Server Function (AUSF)

[0112] is a network function in the 5G core responsible for authenticating UEs during registration and providing security services. It generates and verifies authentication vectors and tokens.

[0053] Network Slice Specific Authentication and Authorization Function (NSSAAF)

[0114] 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.

[0054] Network Slice Selection Function (NSSF)

[0116] 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.

[0055] Network Exposure Function (NEF)

[0118] is a network function that exposes capabilities and services of the 5G network to external applications, enabling integration with third-party services and applications.

[0056] Network Repository Function (NRF)

[0120] is a network function that acts as a central repository for information about available network functions and services. It facilitates the discovery and dynamic registration of network functions.

[0057] Policy Control Function (PCF)

[0122] is a network function responsible for policy control decisions, such as QoS, charging, and access control, based on subscriber information and network policies.

[0058] Unified Data Management (UDM)

[0124] is a network function that centralizes the management of subscriber data, including authentication, authorization, and subscription information.

[0059] Application Function (AF)

[0126] is a network function that represents external applications interfacing with the 5G core network to access network capabilities and services.

[0060] User Plane Function (UPF)

[0128] is a network function responsible for handling user data traffic, including packet routing, forwarding, and QoS enforcement.

[0061] Data Network (DN)

[0130] 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.

[0062] The 5GC network architecture also comprises a plurality of interfaces for connecting the network functions with a network entity for performing the network functions. The NSSF

[0116] is connected with the network entity via the interface denoted as (Nnssf) interface in FIG. 1. The NEF

[0118] is connected with the network entity via the interface denoted as (Nnef) interface in FIG. 1. The NRF

[0120] is connected with the network entity via the interface denoted as (Nnrf) interface in FIG. 1. The PCF

[0122] is connected with the network entity via the interface denoted as (Npcf) interface in FIG. 1. The UDM

[0124] is connected with the network entity via the interface denoted as (Nudm) interface in FIG. 1. The AF

[0126] is connected with the network entity via the interface denoted as (Naf) interface in FIG. 1. The NSSAAF

[0114] is connected with the network entity via the interface denoted as (Nnssaaf) interface in FIG. 1. The AUSF

[0112] is connected with the network entity via the interface denoted as (Nausf) interface in FIG. 1. The AMF

[0106] is connected with the network entity via the interface denoted as (Namf) interface in FIG. 1. The SMF

[0108] is connected with the network entity via the interface denoted as (Nsmf) interface in FIG. 1. The SMF

[0108] is connected with the UPF

[0128] via the interface denoted as (N4) interface in FIG. 1. The UPF

[0128] is connected with the RAN

[0104] via the interface denoted as (N3) interface in FIG. 1. The UPF

[0128] is connected with the DN

[0130] via the interface denoted as (N6) interface in FIG. 1. The RAN

[0104] is connected with the AMF

[0106] via the interface denoted as (N2). The AMF

[0106] is connected with the RAN

[0104] via the interface denoted as (Nl). The UPF

[0128] is connected with other UPF

[0128] via the interface denoted as (N9). The interfaces such as Nnssf, Nnef, Nnrf, Npcf, Nudm, Naf, Nnssaaf, Nausf, Namf, Nsmf, N9, N6, N4, N3, N2, and Nl can be referred to as a communication channel between one or more functions or modules for enabling exchange of data or information between such functions or modules, and network entities.

[0063] Referring to FIG. 2, an exemplary block diagram of a computing device

[0200] upon which the features of the present disclosure may be implemented, in accordance with exemplary implementation of the present disclosure, is shown. In an implementation, the computing device

[0200] may implement a method for handling an overload condition in a network by utilising a system. In another implementation, the computing device

[0200] itself implements the method for handling an overload condition in a network using one or more units configured within thecomputing device

[0200] , wherein said one or more units are capable of implementing the features as disclosed in the present disclosure.

[0064] The computing device

[0200] may include a bus

[0202] or other communication mechanism for communicating information, and a hardware processor

[0204] coupled with bus

[0202] for processing information. The hardware processor

[0204] may be, for example, a general -purpose microprocessor. The computing device

[0200] may also include a main memory

[0206] , such as a random-access memory (RAM), or other dynamic storage device, coupled to the bus

[0202] for storing information and instructions to be executed by the processor

[0204] , The main memory

[0206] also may be used for storing temporary variables or other intermediate information during execution of the instructions to be executed by the processor

[0204] , Such instructions, when stored in non-transitory storage media accessible to the processor

[0204] , render the computing device

[0200] into a special-purpose machine that is customized to perform the operations specified in the instructions. The computing device

[0200] further includes a read only memory (ROM)

[0208] or other static storage device coupled to the bus

[0202] for storing static information and instructions for the processor

[0204] ,

[0065] A storage device

[0210] , such as a magnetic disk, optical disk, or solid-state drive is provided and coupled to the bus

[0202] for storing information and instructions. The computing device

[0200] may be coupled via the bus

[0202] to a display

[0212] , such as a cathode ray tube (CRT), Liquid crystal Display (LCD), Light Emitting Diode (LED) display, Organic LED (OLED) display, etc. for displaying information to a computer user. An input device

[0214] , including alphanumeric and other keys, touch screen input means, etc. may be coupled to the bus

[0202] for communicating information and command selections to the processor

[0204] , Another type of user input device may be a cursor controller

[0216] , such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor

[0204] , and for controlling cursor movement on the display

[0212] , The input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allow the device to specify positions in a plane.

[0066] The computing device

[0200] 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

[0200] causes or programs the computing device

[0200] to be a special-purpose machine. According to one implementation, the techniques herein are performed by the computing device

[0200] in response to the processor

[0204] executing one or moresequences of one or more instructions contained in the main memory

[0206] , Such instructions may be read into the main memory

[0206] from another storage medium, such as the storage device

[0210] , Execution of the sequences of instructions contained in the main memory

[0206] causes the processor

[0204] 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.

[0067] The computing device

[0200] also may include a communication interface

[0218] coupled to the bus

[0202] , The communication interface

[0218] provides a two-way data communication coupling to a network link

[0220] that is connected to a local network

[0222] , For example, the communication interface

[0218] may be an integrated services digital network (ISDN) card, cable modem, satellite modem, or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, the communication interface

[0218] 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 such implementation, the communication interface

[0218] sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0068] The computing device

[0200] can send messages and receive data, including program code, through the network(s), the network link

[0220] and the communication interface

[0218] , In the Internet example, a server

[0230] might transmit a requested code for an application program through the Internet

[0228] , the ISP

[0226] , a host

[0224] , the local network

[0222] and the communication interface

[0218] , The received code may be executed by the processor

[0204] as it is received, and / or stored in the storage device

[0210] , or other non-volatile storage for later execution.

[0069] Referring to FIG. 3, an exemplary block diagram of a system

[0300] for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure is illustrated. In one example, the system

[0300] may be in communication with other network entities / components known to a person skilled in the art. Such network entities / components have not been depicted in FIG. 3 and have not been explained here for the sake of brevity.

[0070] Referring to FIG. 4, an exemplary signalling flow diagram

[0400] depicting a process for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure is illustrated.

[0071] It may be noted that FIG. 3 and FIG. 4 have been explained simultaneously and may be read in conjunction with each other.

[0072] As depicted in FIG. 3, the system

[0300] comprises at least one transceiver unit

[0302] , at least one processing unit

[0304] and at least one identification unit

[0306] , Also, all of the components / units of the system

[0300] are assumed to be connected to each other unless otherwise indicated below. As shown in the FIG. 3, all units shown within the system

[0300] should also be assumed to be connected to each other. Also, in FIG. 3 only a few units are shown, however, the system

[0300] may comprise multiple such units or the system

[0300] may comprise any such numbers of said units, as required to implement the features of the present disclosure. Further, in an implementation, the system

[0300] may reside in a server or the network entity or the system

[0300] may be in communication with the network entity to implement the features as disclosed in the present disclosure.

[0073] The system

[0300] is configured for providing service continuity in a communication network with the help of the interconnection between the components / units of the system

[0300] , In the context of the present disclosure, it may be understood and noted that the Network Functions (NFs) in the network may be registered at a Network Repository Function (NRF). Such an NRF, among other functionalities, may maintain information about NFs in the network and the services that they provide. Further, it is to be noted that the NRF as used in the present disclosure herewith, performs the same function as the NRF

[0120] as described with respect to FIG. 1.

[0074] Further, examples of the network functions include, but are not limited to, an Access and Mobility Management Function (AMF) and a Session Management Function (SMF). Such AMF and SMF have been explained in conjunction with FIG. 1, as AMF

[0106] and SMF

[0108] respectively. The same explanation has not been repeated here for the sake of brevity.

[0075] In an exemplary aspect of the present disclosure, the transceiver unit

[0302] at the NF may transmit a discovery request to the NRF. The discovery request allows the NF to discover and communicate with other NFs registered with the NRF. The discovery request allows the NF to receive information related to the other NFs registered with the NRF. As described previously and would be understood, the NRF may include the data corresponding to all the NFs registered in the network. In one example, the discovery request may also include filter criteria such as, but not limited to, type of the network function, services offered by the network function, etc. In another example, the discovery request may be a HTTP GET request. Th NFDiscover service operationdiscovers the set of NF Instances (and their associated NF Service Instances), represented by their NF Profile, that are currently registered in NRF and satisfy a number of input query parameters. Before a service consumer invokes this service operation, it shall consider if it is possible to reuse the results from a previous searching (service discovery). The service consumer should reuse the previous result if input query parameters in the new service discovery request are the same as used for the previous search and the validity period of the result is not expired. The service consumer may consider reusing the previous result if the attributes as required for the new query is also part of NF profile of the candidates NFs from a previous query. In such case, when the results of a previous query are reused, the service consumer need consider that the results, e.g. in terms of the number of discovered NFs, can be different than the potential results obtained after performing a new query.

[0076] Continuing further, the transceiver unit

[0302] may receive a discovery response from the NRF. Since, the NRF stores one or more profiles of the registered NFs, the NRF responds with the profiles of the available NFs based on the discovery request and the criteria mentioned in the discovery request. Furthermore, in the discovery response the NF may also receive validity period associated with each profile of the discovered NFs. The validity period may determine the duration during which the discovered results, or the discovery response may be cached by the NF requesting the discovery.

[0077] In one example, the discovery response is a HTTP 200 OK response. In another example, the discovery response may include the URI (conforming to the resource URI structure) of each registered NF in the NRF that satisfies the retrieval filter criteria.

[0078] Continuing further, the processing unit

[0304] may store the discovery response in a cache or a storage

[0308] , The discovery response may be temporarily stored in the cache at the NF requesting the discovery. Also, the discovery response may be stored in the cache for the validity period received along with the discovery response.

[0079] In an exemplary implementation, the NF will generally again execute the discovery procedure before the expiry of this validity period to refresh the cache if need be. If the NF has already cached the discovery response, and if before validity period expiry is trying the discovery procedure again, it may receive a response that the NRF is not available at that time.

[0080] Further, each NF maintains a list of one or more NRFs in the cache. If a discovery response is not received from an NRF, the NF retries to send the re-discovery message to an alternate NRF.

[0081] Continuing further, based on the above cited exemplary implementation, the transceiver unit

[0302] may transmit, from the Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message. This has been depicted as step 402 of the FIG. 4.

[0082] In an exemplary implementation, the NF may re-initiate the process of discovery of another NRF, by transmitting the first re-discovery message to the first NRF. The first NRF may be the NRF where the NF may be registered. The first re-discovery message may be related to the discovery of the NFs registered in the first NRF. Also, the first re-discovery message may be transmitted before the expiry of the validity period of the cached NF.

[0083] In another implementation, the NF may re-initiate the process of discovery of other NFs, by transmitting the first re-discovery message to the first NRF when the validity period related to the cached NF may have expired. In an exemplary aspect of the present disclosure, the NF requesting the discovery retains the previously cached discovered NFs. That is to say that the NF keeps the cache with the previously discovered NFs intact and does not delete the cache based on the validity period of the profiles of the discovered NFs. This is done by the NF to maintain continuity of service to the NF service consumers. Further, the NF raises an alert when the validity period associated with each of the profile of earlier discovered NFs expires. The alert is sent to notify one or more service consumers of the NF that NF is using the cached profiles of earlier discovered NFs for providing service.

[0084] In an alternate implementation, the NF may also use the service responses from the discovered NFs which are also the NF producers, and which were connected using the cached entries of the discovered NF profiles, to determine if those entries should be kept in the cache (which is old and unreliable post the validity period expiry). For example, if in the cache there are 2 discovered NFs which can provide the service but one of those discovered NFs is continuously sending the negative response to consumers of the NF then NF may decide to take that discovered NF out of cache and continue service with other available discovered NF in cache. Once the rediscovery procedure is successful, cache entries can be updated as per the latest provided discovery response.

[0085] Continuing further, the transceiver unit

[0302] may receive at the NF, a first re-discovery response based on the first re-discovery message. Also, the first re-discovery response may be one of a negative response and a timeout response which is received at the NF from a Service Communication Proxy (SCP). The negative response and the timeout response received at the NFfrom the SCP indicates unavailability of the first NRF. Also, as would be understood the SCP may act as an intermediary between the one or more NFs and the NRF. Further, the SCP is deployed along side of 5G Network Functions (NFs) for providing routing control, resiliency, and observability to the core network. Further, the unavailability of the first NRF may be due to several reasons such as, but not limited to, system failure, network connectivity issue, overload, etc.

[0086] Continuing further, since the processing unit

[0304] maintains the cache with profiles of discovered NFs, so if the first re-discovery response is negative or a timeout response, the NF still has the discovered NF profiles to provide service to NF service consumers. As described earlier, the NF keeps the cache intact with the discovered NF profiles based on the discovery request sent to the NRF. This is done to ensure service continuity to the NF service consumers, when subsequent re-discovery messages are unsuccessful even with alternate NRFs, NF will keep the previous successful discovery response valid in cache without validating the validity period expiry. The NF may reuse the NF previously discovered from the NRF and stored in the cache at the NF requesting the discovery.

[0087] Further, the identification unit

[0306] may select, a second NRF based on the first rediscovery response. So, if the first re-discovery response is a negative or a timeout response, which indicates unavailability of the first NRF, the identification unit

[0306] selects the second NRF. The second NRF may be an alternate NRF that may be used for the discovery of the NFs based on the filter criteria. The alternate NRF is selected by the NF from a list of one or more alternate NRFs maintained at the NF.

[0088] In an implementation, the time out response may be received by the NF from the NRF, in case, the NF may not receive the discovery response within the expected time frame. The expected time frame may be user configurable and may be specific to each network operator. The time out response may be received due to unavailability of the first NRF which may be because of several reasons such as, but not limited to, the system failure, network failure, overload on the NRF, etc.

[0089] In another implementation, the negative response may be received when the NRF was unable to provide the profile and / or information related to the NFs requested in the discovery request. This may be due to several reasons such as, but not limited to, the requesting NF may not have subscribed to discovery requests in the first NRF, the discovery request may include incorrect and / or invalid parameter / filter criteria etc. In this case the NRF may reject the discovery request of the NF and may transmit the negative response.

[0090] Continuing further, the transceiver unit

[0302] may transmit to a second NRF, a second rediscovery message based on the first re-discovery response. This has been depicted as step 406 of the FIG. 4.

[0091] In an embodiment, after receiving one of the negative response and the time out response, the NF may transmit the re-discovery request i.e., the second re-discovery message to the second NRF i.e., the alternate NRF. The second re-discovery request also comprises the filter criteria such as, but not limited to, type of the network function, services offered by the network function, etc. Also, the first discovery message and the second discovery message are transmitted by the NF based on an internal timer at the NF. The internal timer at the NF may refer to a predefined period that may determine when the NF may re-transmit the NF discovery request to the NRF. Furthermore, the internal timer may ensure that the NF, based on the predefined period keeps checking for the availability of the other NRFs until the NF may receive a successful response. This has been depicted as step 402, step 404 and step 406 of the FIG. 4.

[0092] Continuing further, the transceiver unit may receive a second re-discovery response from the second NRF, based on the second re-discovery message. Also, the second re-discovery response is one of a successful response and an unsuccessful response. Further, the successful response may comprise the discovery of the NFs requested in the second re-discovery message and the NFs that may fulfil the filter criteria received along with the second re-discovery response. Further, the second re-discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period. Furthermore, the discovered NFs may include the NFs registered in the second NRF i.e., the alternate NRF. Moreover, an unsuccessful response is received from the second NRF, when the second NRF was unable to provide the profile and / or information related to the NFs requested in the discovery request. This may be due to several reasons such as, but not limited to, the requesting NF may not have subscribed to discovery requests in the second NRF, the discovery request may include incorrect and / or invalid parameter / filter criteria etc. In this case the second NRF may reject the discovery request of the NF and may transmit the negative response.

[0093] In an exemplary implementation, if the response is a successful response, the NF may receive 200 OK (e.g. successful search result) response from the second NRF i.e., the alternate NRF. This has been depicted as step 408 of the FIG. 4.

[0094] Furthermore, in another implementation, if the response is an unsuccessful response, the NF may receive bad request or unauthorized (e.g. unsuccessful search result) response from the second NRF i.e., the alternate NRF.

[0095] Thereafter, the processing unit

[0304] may update the cache with the second re-discovery response in an event the second re-discovery response is the successful response. Also, the cache is updated with the profiles of discovered NFs by overwriting the profiles of earlier discovered NFs. The processing unit

[0304] may remove the previously stored profiles of the NFs from the cache and update the cache with the new discovered NFs.

[0096] Further, it is to be noted that the current implementation of the present disclosure can also be used for other NRF related procedures such as Subscribe, AccessToken etc. using similar steps. Further the above-described aspects and steps do not limit the applications of the present disclosure in any way. The above-described aspects and steps are not mandatory and should be supported at NFs for handling a negative scenario, related to the above listed exemplary procedures.

[0097] Referring to FIG. 5 an exemplary flow diagram of a method

[0500] for service continuity in a communication network, in accordance with exemplary implementation of the present disclosure is illustrated. In an implementation the method

[0500] is performed by the system

[0300] , Also, as shown in FIG. 5, the method

[0500] initiates at step

[0502] ,

[0098] After the method initiates, a transceiver unit

[0302] at the NF may transmit a discovery request to an NRF. The discovery request allows the NF to discover and communicate with other NFs registered in the NRF. The discovery request allows the NF to receive information related to the other NFs registered in the NRF. As described previously and would be understood, the NRF may include the data corresponding to all the NFs registered in the network. In one example, the discovery request may also include filter criteria such as, but not limited to, type of the network function, services offered by the network function, etc. In another example, the discovery request may be a HTTP GET request.

[0099] Continuing further, the transceiver unit

[0302] may receive a discovery response from the NRF. The NRF may store one or more profiles of the registered NFs. Further the NRF may respond with the profiles of the available NFs based on the discovery request and the criteria mentioned in the discovery request. Furthermore, in discovery response the NF may also receive validity period associated with each profile of the discovered NFs. The validity period may determine the durationduring which the discovered results, or the discovery response may be cached by the NF requesting the discovery.

[0100] In one example, the discovery response is a HTTP 200 OK response. In another example, the discovery response may include the URI (conforming to the resource URI structure) of each registered NF in the NRF that satisfy the retrieval filter criteria.

[0101] Continuing further, the processing unit

[0304] may store the discovery response in the cache. The discovery response may be temporarily stored in the cache at the NF requesting the discovery. Also, the discovery response may be stored in the cache for the validity period received along with the discovery response.

[0102] In an exemplary implementation, the NF will generally again execute the discovery procedure before the expiry of this validity period to refresh the cache if need be. If the NF has already cached the discovery response, and if before validity period expiry is trying the discovery procedure again, it may receive a response that the NRF is not available at that time. Further, each NF maintains a list of one or more NRFs in the cache. If a discovery response is not received from an NRF, the NF retries to send the re-discovery message to an alternate NRF.

[0103] Next, at step

[0504] , the method comprises transmitting, by a transceiver unit

[0302] from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message.

[0104] In an exemplary implementation, the NF may re-initiate the process of discovery of another NRF, by transmitting the first re-discovery message to the first NRF. The first NRF may be the NRF where the NF may be registered and has subscribed to discovery service. The first rediscovery message may be related to the discovery of the NFs registered in the first NRF. Also, the first re-discovery message may be transmitted before the expiry of the validity period of the cached NF.

[0105] In another implementation, the NF may re-initiate the process of discovery of other NFs, by transmitting the first re-discovery message to the first NRF when the validity period related to the cached NF may have expired. In an exemplary aspect of the present disclosure, the NF requesting the discovery retains the previously cached discovered NFs. That is to say that the NF keeps the cache with the previously discovered NFs intact and does not delete the cache based onthe validity period of the profiles of the discovered NFs. This is done by the NF to maintain continuity of service to the NF service consumers. Further, the NF raises an alert when the validity period associated with each of the profile of earlier discovered NFs expires. The alert is sent to notify one or more NF service consumers that NF is using the cached profiles of earlier discovered NFs for providing service.

[0106] Further, at step

[0506] , the method

[0500] comprises receiving, by the transceiver unit

[0302] at the NF, a first re-discovery response based on the first re-discovery message. Also, the first rediscovery response is one of a negative response and a timeout response which is received at the NF from a Service Communication Proxy (SCP). The negative response and the timeout response received at the NF from the SCP indicates unavailability of the first NRF. Also, as would be understood the SCP may act as an intermediary between the one or more NFs and the NRF. Further, the unavailability of the first NRF may be due several reasons such as, but not limited to, system failure, network connectivity issue, overload, etc.

[0107] Further, at step

[0508] , the method

[0500] comprises maintaining, by a processing unit

[0304] at the NF, a cache with profiles of earlier discovered NFs. Since the processing unit

[0304] maintains the cache with profiles of discovered NFs, so if the first re-discovery response is negative or a timeout response, the NF still has the discovered NF profiles to provide service to NF service consumers. As described earlier, the NF keeps the cache intact with the discovered NF profiles based on the discovery request sent to the NRF. This is done to ensure service continuity to the NF service consumers, when subsequent re-discovery messages are unsuccessful even with alternate NRFs, NF will keep the previous successful discovery response valid in cache without validating the validity period expiry. The NF may reuse the NF previously discovered from the NRF and stored in the cache at the NF requesting the discovery.

[0108] Next, at step

[0510] , the method

[0500] comprises selecting, by an identification unit at the NF, a second NRF. The second NRF may be an alternate NRF that may be used for the discovery of the NFs requested based on the filter criteria. Further, the second NRF may be used in case one of the negative response and the time out response is received from the first NRF. The alternate NRF is selected by the NF from a list of one or more alternate NRFs maintained at the NF.

[0109] In an implementation, the time out response may be received by the NF from the NRF in case, when the NF may not receive the discovery response within the expected time frame. Thetime out response may be received due to unavailability of the first NRF because of several reasons such as, but not limited to, the system failure, network failure, overload on the NRF, etc.

[0110] In another implementation, the negative response may be received when the NRF was unable to provide the profile and / or information related to the NFs requested in the discovery request. This may be due to several reasons such as, but not limited to, the requesting NF may not have subscribed to discovery requests in the first NRF, the discovery request may include incorrect and / or invalid parameter / filter criteria etc. In this case the NRF may reject the discovery request of the NF and may transmit the negative response.[OHl] In an alternate implementation, the NF may also use the service responses from the discovered NFs which are also the NF producers, and which were connected using the cached entries of the discovered NF profiles, to determine if those entries should be kept in the cache (which is old and unreliable post the validity period expiry). For example, if in the cache there are 2 discovered NFs which can provide the service but one of those discovered NFs is continuously sending the negative response to consumers of the NF then NF may decide to take that discovered NF out of cache and continue service with other available discovered NF in cache. Once the rediscovery procedure is successful, cache entries can be updated as per the latest provided discovery response.

[0112] Further, at step

[0512] , the method

[0500] comprises transmitting, by the transceiver unit at the NF, to the second NRF, a second re-discovery message based on the first re-discovery response. In an embodiment, after receiving one of the negative response and the time out response, the NF may transmit the discovery request i.e., the second re-discovery message to the second NRF i.e., an alternate NRF. The second re-discovery request also comprises the filter criteria such as, but not limited to, type of the network function, services offered by the network function, etc. Also, the first discovery message and the second discovery message are transmitted by the NF based on an internal timer at the NF. The internal timer at the NF may refer to a predefined period that may determine when the NF may transmit the NF discovery request to the NRF. Furthermore, the internal timer may ensure that the NF may on the predetermined time check for the availability of the other NFs until the NF may receive a successful response.

[0113] Furthermore, at step

[0514] , the method

[0500] comprises receiving, by the transceiver unit at the NF, a second re-discovery response from the alternate second NRF, based on the second rediscovery message. The second re-discovery response is one of a successful response and anunsuccessful response. Further, a successful response may comprise the discovery of the NFs requested in the second re-discovery message and the NFs that may fulfil the filter criteria received along with the second re-discovery message. Further, the second re-discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period. Furthermore, the discovered NFs may include the NFs registered in the second NRF i.e., the alternate NRF. Moreover, when the NF requested in the second re-discovery message is not registered in the second NRF i.e., the alternate NRF and / or the NFs not fulfilling the filter criteria, the transceiver unit

[0302] at the NF may receive the unsuccessful response from the second NRF i.e., the alternate NRF. In an exemplary implementation, if the response is the successful response, the NF may receive 200 OK (e.g. successful search result) response from the second NRF i.e., the alternate NRF.

[0114] Furthermore, in another implementation, if the response is an unsuccessful response, the NF may receive bad request or unauthorized (e.g. unsuccessful search result) response from the second NRF i.e., the alternate NRF.

[0115] Thereafter, at step

[0516] , the method

[0500] comprises updating, by the processing unit at the NF, the cache with the second re-discovery response in an event the second re-discovery response is a successful response. Also, the cache is updated with the profiles of discovered NFs by overwriting the profiles of earlier discovered NFs. The processing unit

[0304] may remove the previously stored profiles of the NFs from the cache and update the cache with the new discovered NFs.

[0116] Moreover, at step

[0518] , the method

[0500] terminates.

[0117] Further, it is to be noted that the current implementation of the present disclosure can also be used for other NRF related procedures such as Subscribe, AccessToken etc. using similar steps. Further the above-described aspects and steps do not limit the applications of the present disclosure in any way. The above-described aspects and steps are not mandatory and should be supported at NFs for handling a negative scenario, related to the above listed exemplary procedures.

[0118] The present disclosure may further relate to a non-transitory computer-readable storage medium storing one or more instructions for service continuity in a communication network the storage medium comprising executable code which, when executed by one or more units of a system

[0300] , causes a transceiver unit

[0302] , of the system

[0300] , to transmit, from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message. Theexecutable code when executed further causes the transceiver unit

[0302] to receive at the NF, a first re-discovery response based on the first re-discovery message. Further, the executable code when executed causes a processing unit

[0304] , of the system

[0300] , to maintain a cache with profiles of discovered NFs, based on the first re-discovery response. Further, the executable code when executed causes an identification unit

[0306] , of the system

[0300] , to select, a second NRF. Furthermore, the executable code when executed causes the transceiver unit

[0302] to transmit to the second NRF, a second re-discovery message based on the first re-discovery response. Also, the executable code when executed further causes the transceiver unit

[0302] to receive a second rediscovery response from the second NRF, based on the second re-discovery message. The second re-discovery response is one of a successful response and an unsuccessful response. Moreover, the executable code when executed causes the processing unit

[0304] to update the cache with the second re-discovery response in an event the second re-discovery response is the successful response.

[0119] As is evident from the above, the present disclosure provides a technically advanced solution for service continuity in a communication network. More particularly, the present solution provides that even in case of Discovery Failure, network functions (NFs) will retry in configurable time towards network repository function (NRF) so that cached data can be refreshed as soon as possible. Further, the present solution supports multiple alternate NRF configuration so that discovery can be tried with alternate NRF in case of failure of the first NRF providing better chances of success. Furthermore, the present solution provides that even in case re-discovery is not successful, data from previous discovery will be kept in cache for indefinite time. Moreover, the present solution provides that event after the validity period has expired NRF will keep service live even if re-Discovery from NRF fails.

[0120] 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.

[0121] Further, in accordance with the present disclosure, it is to be acknowledged 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 isrecognized that various configurations and combinations thereof are within the scope of the disclosure. The functionality of specific units as disclosed in the disclosure 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.

Claims

We Claim:

1. A method [400] for providing service continuity in a communication network, the method comprising: transmitting, by a transceiver unit [302] from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message; receiving, by the transceiver unit [302] at the NF, a first re-discovery response based on the first re-discovery message; maintaining, by a processing unit [304] at the NF, a cache with profiles of discovered NF s, based on the first re-discovery response; selecting, by an identification unit [306] at the NF, a second NRF; transmitting, by the transceiver unit [302] at the NF, to the second NRF, a second re-discovery message based on the first re-discovery response; receiving, by the transceiver unit [302] at the NF, a second re-discovery response from the second NRF, based on the second re-discovery message, wherein the second re-discovery response is one of a successful response and an unsuccessful response; and updating, by the processing unit [304] at the NF, the cache with the second rediscovery response in an event the second re-discovery response is the successful response.

2. The method [400] as claimed in claim 1, wherein prior to transmitting the first re-discovery message from the NF to the NRF, the method comprises: transmitting, by the transceiver unit [302] at the NF, a discovery request to an NRF; receiving, by the transceiver unit [302] at the NF, a discovery response from the NRF; storing, by the processing unit [304] at the NF, the discovery response in the cache.

3. The method [400] as claimed in claim 2, wherein the discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period.

4. The method [400] as claimed in claim 1, wherein the first re-discovery response is one of a negative response and a timeout response which is received at the NF from a Service Communication Proxy (SCP).

5. The method [400] as claimed in claim 1, wherein the negative response and the timeout response received at the NF from the NRF indicates unavailability of the first NRF.

6. The method [400] as claimed in claim 1, wherein the first discovery message and the second discovery message are transmitted by the NF based on an internal timer at the NF.

7. The method [400] as claimed in claim 1, wherein the second NRF is selected by the NF from a list of one or more NRFs maintained at the NF.

8. The method [400] as claimed in claim 1, wherein the second re-discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period.

9. The method [400] as claimed in claim 8, wherein the cache is updated with the profiles of discovered NFs by overwriting the profiles of earlier discovered NFs.

10. The method [400] as claimed in claim 3, wherein, the NF raises an alert when the validity period associated with each of the profile of earlier discovered NFs expires.

11. The method [400] as claimed in claim 10, wherein the alert is sent to notify one or more NF service consumers that NF is using the cached profiles of earlier discovered NFs for providing service.

12. A system [300] for providing service continuity in a communication network, the system comprising: a transceiver unit [302], configured to transmit, from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message; the transceiver unit [302] further configured to receive at the NF, a first re-di scovery response based on the first re-discovery message; a processing unit [304] connected to at least the transceiver unit [302] at the NF, the processing unit [304] is configured to maintain a cache with profiles of discovered NFs, based on the first re-discovery response; an identification unit [306] connected to at least the processing unit [304] at the NF, the identification unit [306] is configured to select, a second NRF;the transceiver unit [302] at the NF, further configured to transmit to the second NRF, a second re-discovery message based on the first re-discovery response; the transceiver unit [302] at the NF, is further configured to receive a second rediscovery response from the second NRF, based on the second re-discovery message, wherein the second re-discovery response is one of a successful response and an unsuccessful response; and the processing unit [304] at the NF, further configured to update the cache with the second re-discovery response in an event the second re-discovery response is the successful response.

13. The system [300] as claimed in claim 12, wherein prior to transmitting the first rediscovery message from the NF to the NRF, the system comprises: the transceiver unit [302] at the NF, configured to transmit a discovery request to an NRF; the transceiver unit [302] at the NF, further configured to receive a discovery response from the NRF; the processing unit [302] at the NF, configured to store the discovery response in the cache.

14. The system [300] as claimed in claim 13, wherein the discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period.

15. The system [300] as claimed in claim 12, wherein the first re-discovery response is one of a negative response and a timeout response which is received at the NF from a Service Communication Proxy (SCP).

16. The system [300] as claimed in claim 12, wherein the negative response and the timeout response received at the NF from the SCP indicates unavailability of the first NRF.

17. The system [300] as system in claim 12, wherein the first discovery message and the second discovery message are transmitted by the NF based on an internal timer at the NF.

18. The system [300] as claimed in claim 12, wherein the NRF is selected by the NF from a list of one or more NRFs maintained at the NF.

19. The system [300] as claimed in claim 12, wherein the second re-discovery response comprises profiles of discovered NFs, wherein each of the profile of discovered NFs is associated with a validity period.

20. The system [300] as claimed in claim 19, wherein the cache is updated with the profiles of discovered NFs by overwriting the profiles of earlier discovered NFs.

21. The system [300] as claimed in claim 14, wherein, the NF raises an alert when the validity period associated with each of the profile of earlier discovered NFs expires.

22. The system [300] as claimed in claim 21, wherein the alert is sent to notify one or more NF service consumers that NF is using the cached profiles of earlier discovered NFs for providing service.

23. A non-transitory computer-readable storage medium storing instructions for providing service continuity in a communication network, the storage medium comprising executable code which, when executed by one or more units of a system [300], causes: a transceiver unit [302], to transmit, from a Network Function (NF) to a first Network Repository Function (NRF), a first re-discovery message; the transceiver unit [302] to receive at the NF, a first re-discovery response based on the first re-discovery message; a processing unit [304] to maintain at the NF, a cache with profiles of discovered NFs, based on the first re-discovery response; an identification unit [306] at the NF, to select, a second NRF; the transceiver unit [302] at the NF, to transmit to the second NRF, a second rediscovery message based on the first re-discovery response; the transceiver unit [302] at the NF, to receive a second re-discovery response from the second NRF, based on the second re-discovery message, wherein the second rediscovery response is one of a successful response and an unsuccessful response; and the processing unit [304] at the NF, to update the cache with the second re-discovery response in an event the second re-discovery response is the successful response.

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