Method and system for managing stale sessions in a network

Abstract

A method (600) and a system (108) for managing stale sessions in a network (106). The method (600) includes a network function (212) receiving a registration request from a user equipment (UE) (104). The method (600) includes generating and transmitting a context request to a specific network node (304), receiving a context response message from the specific network node (304) and determining the presence of an information element (IE) in the received context response. Based on the determination of the IE, the network function (212), generates a context acknowledgment, which may be a positive context acknowledgment or a negative context acknowledgment, and transmitting the context acknowledgment to the specific network node (304). The method (600) includes the specific network node (304) managing at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgment from the network function (212).

Description

METHOD AND SYSTEM FOR MANAGING STALE SESSIONS IN A NETWORKRESERVATION OF RIGHTS

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

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

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

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

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

[0006] The term ‘4G User Equipment’ as used herein in the specification refers to a device that connects to and communicates with a Long-Term Evolution (LTE) 4G network. The 4G UE enables the user to access mobile data, make calls, send text messages, and utilize various services provided by the mobile network.

[0007] The term ‘Mobility Management Entity (MME)’ as used herein in the specification refers to a component of an Evolved Packet Core (EPC) in the 4G LTE network, responsible for managing user mobility and signalling between the user equipment (UE) and the core network. The MME handles various controlplane functions essential for the seamless operation of mobile networks, including mobility management, session management, and authentication.

[0008] The term ‘Home Subscriber Server (HSS)’ as used herein in the specification refers to a database in the core network of the LTE network (4G) and an Internet Protocol (IP) Multimedia Subsystem (IMS) architecture. Its functionality is closely related to a Unified Data Management (UDM) in 5G networks. The HSS is central in managing subscriber information and supporting mobility, authentication, and session management functions.

[0009] The term ‘Unified Data Management (UDM)’ as used herein in the specification refers to a component that is responsible for managing and storing subscription data and handling various network procedures related to user identification, authorization, and mobility. The UDM essentially serves as the central database and plays a similar role to the HSS used in 4G LTE, but with enhanced capabilities tailored for 5G networks.

[0010] The term ‘Subscriber Location Function (SLF)’ as used herein in the specification refers to a key component within the mobile network architectures,particularly in LTE and 5G systems. The SLF’s primary role is to map subscriber identities to a correct HSS or a UDM server, ensuring that subscriber-related queries are directed to the correct database in the multi -HSS or multi-UDM environments.

[0011] The term ‘Access and Mobility Management Function (AMF)’ as used herein in the specification refers to a component that is responsible for managing signalling and mobility for 5G devices. The AMF plays a similar role to the MME in 4G / LTE networks but is designed to handle the advanced requirements of 5G, including support for higher speeds, ultra-low latency, and a broader range of devices.

[0012] The term ‘Session Management Function (SMF)’ as used herein in the specification refers to a component that is responsible for managing user sessions, including the establishment, modification, and termination of the data sessions or Protocol Data Unit (PDU) sessions. The SMF works in conjunction with other core network components, such as a User Plane Function (UPF), to ensure seamless communication and data transfer across the 5G network.

[0013] The term ‘User Plane Function (UPF)’ as used herein in the specification refers to a component that handles data traffic between the UE and the external data networks (such as the internet). The UPF plays a crucial role in the user plane, which refers to the path that user data takes, as opposed to the control plane, which manages signalling and control messages between different network elements.

[0014] The term ‘Policy Control Function (PCF)’ as used herein in the specification plays a critical role in managing network policies, user session management, and ensuring quality of service (QoS). The PCF is responsible for controlling and enforcing policies that govern the behaviour of user sessions, including data usage, access controls, and service priorities. The PCF interacts with various 5G core components to enable efficient resource allocation, enforce servicelevel agreements (SLAs), and optimize network traffic.

[0015] The term ‘Charging Function (CHF)’ as used herein in the specification refers to a component that allows flexible and efficient service deployments. The CHF plays a crucial role in online and offline charging mechanisms to ensure that the users are billed correctly based on their service usage. The CHF helps the telecom operators in managing and monetizing their network services effectively.

[0016] The term ‘Online Charging System (OCS)’ as used herein in the specification refers to a component that handles real-time charging for services used by subscribers. The OCS manages charging transactions as they occur and ensures that users are charged accurately for data, voice, messaging, and other services based on their consumption in real-time.

[0017] The term ‘Policy and Charging Rules Function (PCRF)’ as used herein in the specification refers to a component that is responsible for managing and enforcing policies related to service quality, resource allocation, and charging for mobile network operators.

[0018] The term ‘Packet Data Network Gateway (PGW)’ as used herein in the specification refers to a component that is essential for managing user data connections in LTE networks, ensuring efficient routing, QoS management, and integration with other data networks.

[0019] The term ‘Evolved Packet Data Gateway (ePDG)’ as used herein in the specification refers to a component that facilitates the connection between the user equipment (like smartphones or tablets) and the LTE network, particularly when the user is accessing the network via a non-secure or untrusted connection, such as public Wi-Fi. The ePDG enhances the LTE network's capabilities, particularly in terms of security and seamless connectivity across different types of networks.

[0020] These definitions are in addition to those expressed in the art.BACKGROUND

[0021] The following description of related art is intended to provide background information pertaining to the field of the disclosure. This section may include certain aspects of the art that may be related to various features of the present disclosure. However, it should be appreciated that this section be used only to enhance the understanding of the reader with respect to the present disclosure, and not as admissions of prior art.

[0022] Wireless communication technology has rapidly evolved over the past few decades. The first generation of wireless communication technology was analog, offering only voice services. Further, text messaging and data services became possible when the second-generation (2G) technology 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 the wireless communication with faster data speeds, improved network coverage, and security. Currently, fifth generation (5G) technology is being deployed, offering significantly faster data speeds, lower latency, and the ability to connect many devices simultaneously. These advancements represent a significant leap forward from previous generations, enabling enhanced mobile broadband, improved Internet of Things (loT) connectivity, and more efficient use of network resources. The sixth generation (6G) technology promises to build upon these advancements, pushing the boundaries of wireless communication even further. While the 5G technology is still being rolled out globally, research and development into the 6G are rapidly progressing, with the aim of revolutionizing the way to connect and interact with technology.

[0023] In the 4G network, the user equipments (UEs) are connected to one or more Packet Data Network Gateways (PGW) through Packet Data Network (PDN) connections. The PDN connections are managed by a Mobility Management Entity (MME) in conjunction with a Home Subscriber Server (HSS). In 5Gnetworks, an Access and Mobility Management Function (AMF) controls session management for the UEs.

[0024] When the UE transitions from the 4G network to the 5G network, the 4G PDN connections are expected to be transferred seamlessly to the 5G architecture, allowing for uninterrupted service. During the transition from 4G to 5G, effective user session management is essential for maintaining service quality and network efficiency. Each user is associated with specific access capabilities defined by his subscription; for instance, some users may only be permitted to operate within the 4G network. When such a user attempts to switch to the 5G network through idle mode mobility, significant technical challenges emerge.

[0025] In this scenario, the AMF is unable to transfer the user’s Protocol Data Unit (PDU) sessions to the 5G network because the user is restricted to the 4G network. The failure to transfer these PDU sessions means that the user remains on the 4G network without proper session mapping in the 5G core. The MME operates under an incorrect assumption that the PDU sessions have been successfully migrated to the 5G environment, creating a disconnect in session management. As a result, when the Home Subscriber Server (HSS) issues a Cancel Location Request to the MME to clear these sessions from the PGW, the MME does not process this request correctly. It fails to terminate the stale sessions that should have been cleared, accumulating inactive sessions at the PGW. These stale sessions can have detrimental effects on network performance. These stale sessions consume valuable resources, including bandwidth and processing power, which could otherwise be allocated to active users. Moreover, the stale sessions can complicate network management and lead to inefficiencies in resource allocation, ultimately degrading the overall quality of service for all users on the network.

[0026] There is, therefore, a need in the art to provide a method and a system that mitigate the disadvantages of the prior art.OBJECTIVES OF THE PRESENT DISCLOSURE

[0027] Some of the objectives of the present disclosure, which at least one embodiment herein satisfies, are as follows:

[0028] An objective of the present disclosure is to provide a system and a method for managing stale sessions in a network.

[0029] An objective of the present disclosure is to provide a system and a method that prevents the creation of stale sessions at a Packet Data Network Gateway (PGW) when the users restricted to the 4G networks attempt idle mode mobility from the 4G network to the 5G network. In idle mode mobility, a user equipment (UE) transitions from a 4G network to a 5G network when the UE is not actively transmitting or receiving data.

[0030] Another objective of the present disclosure is to provide a system and a method for managing the Packet Data Network (PDN) connections during 4G to 5G mobility by ensuring that a Mobility Management Entity (MME) does not prematurely clear a session context associated with the PGW.

[0031] Another objective of the present disclosure is to provide a system and a method that enables an Access and Mobility Management Function (AMF) to correctly identify when the PDN connections cannot be transferred to 5G due to a lack of discovery of a Session Management Function (SMF) corresponding to a standalone PGW.

[0032] Another objective of the present disclosure is to provide a system and a method that employs a call flow in which the AMF sends a negative Context Acknowledgment to the MME if the PGW is not discoverable, preventing improper clearing of PDN connections.

[0033] Another objective of the present disclosure is to provide a system and a method that improves the efficiency of network resources by ensuring that sessions at the PGW are properly cleared when the users are restricted to 4G networks, thus preventing unnecessary session buildup.

[0034] Another objective of the present disclosure is to provide a system and a method that ensures that session contexts are maintained and cleared appropriately when PDN transfers to 5G are unsuccessful.

[0035] Another objective of the present disclosure is to provide a system and a method that enables mobility between 4G and 5G networks by handling the session management complexities that arise when users are restricted to 4G networks, thus ensuring smoother network transitions and resource cleanup.

[0036] Other objectives and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.SUMMARY

[0037] In an exemplary embodiment, a method for managing stale sessions in a network is described. The method includes receiving, by a network function, a registration request from a User Equipment (UE). The method includes generating, by the network function, a context request upon receiving the registration request. The method includes transmitting, by the network function, the generated context request to a specific network node. The method includes receiving, by the network function, a context response message from the specific network node corresponding to the context request. The method includes determining, by the network function, a presence of an Information Element (IE) in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE, where the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment. The method includes transmitting, by the network function, the context acknowledgement to the specific network node and managing, by the specific network node, at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.

[0038] In an embodiment, the method includes at least one of the registration request includes a Globally Unique Temporary Identifier (GUTI), the context request includes the GUTI and a target area update (TAU) request message, and the context response message includes at least one of a mobility management (MM) context, UE details, Packet Data Network (PDN) connection details, and a current connection status.

[0039] In an embodiment, the method includes identifying, by the network function, the specific network node based on the GUTI provided by the UE in the registration request.

[0040] In an embodiment, the method includes the network function is an Access and Mobility function (AMF) and the specific network node is a Mobility Management Entity (MME).

[0041] In an embodiment, the IE includes a Packet Data Network (PDN) gateway (PGW) Fully Qualified Domain Name (PGWFQDN) representing a complete domain name with a location of a PGW in the network.

[0042] In an embodiment, the management of the at least one stale session includes generating, by the network function, the negative context acknowledgment on determining at least one of an absence of the IE in at least one PDN connection and a presence of the IE in the at least one PDN connection, where the IE is not discovered at aNetwork Repository Function (NRF) and generating, by the network function, the positive context acknowledgment on determining a presence of the IE in the at least one PDN connection and a corresponding Session Management Function (SMF) discovered by the NRF using the IE.

[0043] In an embodiment, the management of the at least one stale session includes upon receiving the negative context acknowledgment, transmitting, by the specific network node, the at least one delete session request with an operation indicator (OI) towards a Serving Gateway (SGW), forwarding, by the SGW, the at least one delete session request to a Packet Data Network (PDN) gateway (PGW)to delete the at least one stale session, upon deleting the at least one stale session, transmitting, by the PGW, a delete session response to the SGW and forwarding, by the SGW, the delete session response to the specific network node.

[0044] In an embodiment, the management of the at least one stale session includes on receiving the positive context acknowledgement, triggering, by the specific network node, removal of the at least one stale session by transmitting the at least one delete session request without the 01 towards the SGW, and upon deleting the at least one stale session, transmitting, by the SGW, the delete session response to the specific network node.

[0045] In an exemplary embodiment, a system for managing stale sessions in a network, where the system includes a network function. The network function includes an input unit configured to receive a registration request from a User Equipment (UE). The network function includes a processing unit configured to cooperate with the input unit and is further configured to generate a context request on receiving the registration request from the input unit. The network function includes a transceiver unit configured to transmit the generated context request to a specific network node corresponding to the registration request and receive a context response message from the specific network node corresponding to the context request. The network function includes a determining unit configured to determine a presence of an Information Element (IE) in the received context response message. The network function includes an execution unit configured to generate a context acknowledgement based on the determination of the presence of the IE, where the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment. The network function includes the transceiver unit configured to transmit the context acknowledgement to the specific network node, where the specific network node is configured to manage at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.

[0046] In an exemplary embodiment, a user equipment (UE) communicatively coupled with a system, the user equipment is configured to: transmit a registration request to the system. The system is configured to manage stale sessions in a network, where the system includes a network function. The network function includes an input unit configured to receive a registration request from the UE. The network function includes a processing unit configured to cooperate with the input unit and is further configured to generate a context request on receiving the registration request from the input unit. The network function includes a transceiver unit configured to transmit the generated context request to a specific network node corresponding to the registration request and receive a context response message from the specific network node corresponding to the context request. The network function includes a determining unit configured to determine a presence of an Information Element (IE) in the received context response message. The network function includes an execution unit configured to generate a context acknowledgement based on the determination of the presence of the IE, where the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment. The network function includes the transceiver unit configured to transmit the context acknowledgement to the specific network node, where the specific network node is configured to manage at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.

[0047] In an embodiment, the registration request includes a Globally Unique Temporary Identifier (GUTI).

[0048] In an exemplary embodiment, a computer program product comprising a non-transitory computer-readable medium includes instructions that, when executed by one or more processors, cause the one or more processors to execute a method for managing stale sessions in a network. The method includes receiving, by a network function, a registration request from a User Equipment (UE), generating, by the network function, a context request upon receiving the registration request, transmitting, by the network function, the generated contextrequest to a specific network node, receiving, by the network function, a context response message from the specific network node corresponding to the context request, determining, by the network function, a presence of an Information Element (IE) in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE, where the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment, transmitting, by the network function, the context acknowledgement to the specific network node and managing, by the specific network node, at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings, which are incorporated herein, and constitute a part of this disclosure, illustrate exemplary embodiments of the disclosed methods and systems in which like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Some drawings may indicate the components using block diagrams and may not represent the internal circuitry of each component. It will be appreciated by those skilled in the art that disclosure of such drawings includes the disclosure of electrical components, electronic components or circuitry commonly used to implement such components.

[0050] FIG. 1 illustrates an exemplary network architecture of a system for managing stale sessions in a network, in accordance with an embodiment of the present disclosure.

[0051] FIG. 2 illustrates an exemplary block diagram of the system, in accordance with an embodiment of the present disclosure.

[0052] FIG. 3 illustrates an exemplary system architecture for managing the stale sessions in the network, in accordance with an embodiment of the present disclosure.

[0053] FIG. 4 illustrates an exemplary flow chart of a method for managing the stale sessions in the network, in accordance with an embodiment of the present disclosure.

[0054] FIG. 5 illustrates another exemplary flow chart of a method for managing the stale sessions in the network, in accordance with an embodiment of the present disclosure.

[0055] FIG. 6 illustrates an exemplary methodology flow chart of a method for managing the stale sessions in the network, in accordance with an embodiment of the present disclosure.

[0056] FIG. 7 illustrates an exemplary computer system in which or with which the embodiments of the present disclosure may be implemented.

[0057] The foregoing shall be more apparent from the following detailed description of the disclosure.LIST OF REFERENCE NUMERALS100 - Network architecture102 - User(s)104 -User Equipments (UEs)106 - Network108 - System200 - Block diagram- Processor(s)- Memory- Interface(s)- Processing Unit- Database- Network Function- Input Unit- Transceiver Unit- Determining unit- Execution unit- System Architecture- Mobility Management Entity (MME)- Home Subscriber Server (HSS)- HSS- Subscriber Location Function (SLF)- Authentication, Authorization, and Accounting (AAA)- Unified Data Management (UDM)- Access and Mobility Management Function (AMF)- Session Management Function (SMF) - User Plane Function (UPF)- Policy Control Function (PCF)- Charging Function (CHF)- Online Charging System (OCS)- Policy and Charging Rules Function (PCRF)- Packet Data Network Gateway (PGW)- Internet- S2a Mobility Over GTP (SaMOG)- Evolved Packet Data Gateway (ePDG)- Access Point (AP)- Binding Support Function (BSF)- Internet Protocol (IP) Multimedia System (IMS)- Flow chart- Serving Gateway (SGW)- New Radio (NR)- Flow chart- Methodology flow chart- A computer system- External Storage Device- Bus - Main Memory740 - Read Only Memory750 - Mass Storage Device760 - Communication Port770 - ProcessorDETAILED DESCRIPTION

[0058] In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent, however, that embodiments of the present disclosure may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address any of the problems discussed above or might address only some of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein. Example embodiments of the present disclosure are described below, as illustrated in various drawings in which like reference numerals refer to the same parts throughout the different drawings.

[0059] 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.

[0060] 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 thesespecific details. For example, circuits, systems, networks, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments.

[0061] Also, it is noted that individual embodiment may be described as a process that is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed but could have additional steps not included in a figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination can correspond to a return of the function to the calling function or the main function.

[0062] The word “exemplary” and / or “demonstrative” is used herein to mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by such examples. In addition, any aspect or design described herein as “exemplary” and / or “demonstrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to preclude equivalent exemplary structures and techniques known to those of ordinary skill in the art. Furthermore, to the extent that the terms “includes,” “has,” “contains,” and other similar words are used in either the detailed description or the claims, such terms are intended to be inclusive like the term “comprising” as an open transition word without precluding any additional or other elements.

[0063] Reference throughout this specification to “one embodiment” or “an embodiment” or “an instance” or “one instance” means that a particular feature, structure, or characteristic described in connection with the embodiment is includedin at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0064] The terminology used herein is to describe particular embodiments only and is not intended to be limiting the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any combinations of one or more of the associated listed items. It should be noted that the terms “mobile device”, “user equipment”, “user device”, “communication device”, “device” and similar terms are used interchangeably for the purpose of describing the invention. These terms are not intended to limit the scope of the invention or imply any specific functionality or limitations on the described embodiments. The use of these terms is solely for convenience and clarity of description. The invention is not limited to any particular type of device or equipment, and it should be understood that other equivalent terms or variations thereof may be used interchangeably without departing from the scope of the invention as defined herein.

[0065] As used herein, an “electronic device”, or “portable electronic device”, or “user device” or “communication device” or “user equipment” or “device” refers to any electrical, electronic, electromechanical, and computing device. The user device is capable of receiving and / or transmitting one or parameters, performing function / s, communicating with other user devices, and transmitting data to the other user devices. The user equipment may have a processor, a display, a memory, a battery, and an input-means such as a hard keypadand / or a soft keypad. The user equipment may be capable of operating on any radio access technology including but not limited to IP-enabled communication, Zig Bee, Bluetooth, Bluetooth Low Energy, Near Field Communication, Z-Wave, Wi-Fi, Wi-Fi direct, etc. For instance, the user equipment may include, but not limited to, a mobile phone, smartphone, virtual reality (VR) devices, augmented reality (AR) devices, laptop, a general-purpose computer, desktop, personal digital assistant, tablet computer, mainframe computer, or any other device as may be obvious to a person skilled in the art for implementation of the features of the present disclosure.

[0066] Further, the user device may also comprise a “processor” or “processing unit” includes processing unit, wherein processor refers to any logic circuitry for processing instructions. The processor may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor, a plurality of microprocessors, one or more microprocessors in association with a Digital Signalling Processing (DSP) core, a controller, a microcontroller, Application Specific Integrated Circuits, Field Programmable Gate Array circuits, any other type of integrated circuits, etc. The processor may perform signal coding data processing, input / output processing, and / or any other functionality that enables the working of the system according to the present disclosure. More specifically, the processor is a hardware processor.

[0067] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment, as well as other embodiments of the disclosure, will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

[0068] In the evolving landscape of mobile networks, efficient handling of mobility between generations like Fourth Generation (4G) network and Fifth Generation (5G) network has become crucial. The handovers often introduce complexities in maintaining session continuity, especially with legacy components that lack compatibility with new standards. One specific challenge involves when the users are restricted to 4G networks, whose one or more Packet Data Network (PDN) connections are routed through one or more Packet Data Network Gateways (PGWs). When the users restricted to the 4G network attempt to switch to the 5G network during idle mode mobility, problems can arise in how their sessions are managed. The idle mode mobility refers to the ability of a mobile device to move between different network cells or between different network technologies (such as 4G and 5G) while the mobile device is not actively engaged in data transmission. In the idle mode mobility, the mobile device is not sending or receiving data, but it still maintains a connection to the network to receive notifications or manage ongoing sessions. Specifically, the protocols that handle the transfer of their active sessions may not align properly between the two networks (4G and 5G). As a result, the sessions that should have been cleared or updated at the PGW may remain inactive but still registered in the system. These inactive sessions are known as stale sessions, and they can consume network resources unnecessarily, leading to inefficiencies and potentially affecting the overall performance of the network for all users.

[0069] During idle mode mobility from the 4G network to the 5G network, complications arise when the PDN connections are routed through a standalone PGW (a PGW without Session Management Function (SMF) capability). The MME, responsible for managing PDN sessions in the 4G network, assumes that the PDN connections have successfully transferred to the 5G network after a session handover. However, the AMF fails to recognize or authenticate these PDN connections (PDN sessions) due to the absence or misidentification of the PGW Fully Qualified Domain Name (PGWFQDN) and cannot establish a session on the 5G network. The PGWFQDN is a globally unique identifier of a correspondingPGW in the network. A network function (NF) may identify the PDN connections with the PGW based on the PGWFQDN. In an example, in order to support EPC and 5GC interworking, the network function first registers its associated “PGWFQDN” as part of the “profile” to a Network Repository Function (NRF). Despite the failure, the MME does not receive the necessary signalling to terminate the session at the PGW. Consequently, the session remains active on the PGW, consuming resources and creating a stale session.

[0070] In some embodiments, the PGW operates without SMF capability, and therefore, an absence of proper integration with the NRF prevents session migration to the 5G core network (5GC). The existing systems fail to disclose mechanisms to notify the MME of such transfer failures, leading to scenarios where the MME clears sessions from the Serving Gateway (SGW) but leaves them lingering on the PGW. These stale sessions accumulate over time, negatively impacting network performance and administrative processes.

[0071] The present disclosure offers an enhancement to the call flow between the AMF and the MME to address the problem of stale session buildup at the PGW during 4G to 5G idle mode mobility. The solution involves the introduction of conditional acknowledgments and changes in session deletion protocols based on the availability and validity of the PGWFQDN provided by the MME.

[0072] In an embodiment, when the user initiates a mobility registration request, the AMF sends a context request to the MME. Upon receiving the context response from the MME, the AMF checks forthe presence ofthe PGWFQDN under the PDN connections. If the PGWFQDN is missing or the SMF corresponding to the PGWFQDN cannot be discovered in the NRF, indicating that the PGW lacks SMF capability, the AMF sends a negative context acknowledgment to the MME. The negative acknowledgment ensures that the MME retains control over the PDN session, preventing premature deletion at the SGW and enabling a subsequent Delete Session Request with an Operation Indicator (OI) indication to clear the1 session from the SGW and the PGW. The 01 indication may be configured to forward the delete session request to the PGW from the SGW. The 01 indication indicates that the delete session request needs to be forwarded to the PGW to clear the stale PDN session.

[0073] Further, the present solution introduces an essential modification to the call flow by altering the decision-making process at the AMF based on the presence and discoverability of the PGWFQDN. This allows the network to detect scenarios where session transfer is not feasible proactively. The MME may maintain session control and trigger end-to-end session deletion when required, effectively preventing the buildup of stale sessions at the PGW.

[0074] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0075] FIG. 1 illustrates an exemplary network architecture 100 of a system 108 for managing stale sessions in a network 106, in accordance with an embodiment of the present disclosure.

[0076] As illustrated in FIG. 1, the network architecture 100 may include one or more User Equipments (UEs) 104-1, 104-2... 104-N associated with one or more users 102-1, 102-2... 102-N in an environment. A person of ordinary skill in the art will understand that one or more users 102-1, 102-2... 102-N may be collectively referred to as the users 102. Similarly, a person of ordinary skill in the art will understand that one or more UEs 104-1, 104-2. . . 104-N may be collectively referred to as the UE 104 or the UEs 104. Although only three UEs 104 are depicted in FIG. 1, however, any number of the UE 104 may be included without departing from the scope of the ongoing description.

[0077] In an embodiment, the UE 104 may include smart devices operating in a smart environment, for example, an Internet of Things (loT) system. In such an embodiment, the UE 104 may include, but are not limited to, smartphones, smart watches, smart sensors (e.g., a mechanical, a thermal, an electrical, a magnetic,etc.), networked appliances, networked peripheral devices, networked lighting system, communication devices, networked vehicle accessories, networked vehicular devices, smart accessories, tablets, a smart television (TV), computers, a smart security system, a smart home system, other devices for monitoring or interacting with or for the users 102 and / or entities, or any combination thereof. A person of ordinary skill in the art will appreciate that the UE 104 may include, but is not limited to, intelligent, multi-sensing, network-connected devices, which may integrate seamlessly with each other and / or with a central server or a cloudcomputing system or any other device that is network-connected.

[0078] Additionally, in some embodiments, the UE 104 may include, but not limited to, a handheld wireless communication device (e.g., a mobile phone, a smartphone, a phablet device, and so on), awearable computer device (e.g., aheadmounted display computer device, a head-mounted camera device, a wristwatch computer device, and so on), a Global Positioning System (GPS) device, a laptop computer, a tablet computer, or another type of portable computer, a media playing device, a portable gaming system, and / or any other type of computer device with wireless communication capabilities, and the like. In an embodiment, the UE 104 may include, but are not limited to, any electrical, electronic, electromechanical, or equipment, or a combination of one or more of the above devices, such as virtual reality (VR) devices, augmented reality (AR) devices, a laptop, a general-purpose computer, a desktop, a personal digital assistant, a tablet computer, a mainframe computer, or any other computing device. Further, the UE 104 may include one or more in-built or externally coupled accessories including, but not limited to, a visual aid device such as a camera, an audio aid, a microphone, a keyboard, and input devices for receiving input from the user 102 or an entity such as a touchpad, a touch-enabled screen, an electronic pen, and the like. A person of ordinary skill in the art will appreciate that the UE 104 may not be restricted to the mentioned devices and various other devices may be used.

[0079] In FIG. 1, the UE 104 may communicate with the system 108 through the network 106 for sending or receiving various types of data. In anembodiment, the network 106 may include at least one of a 4G network, a 5G network, a 6G network, or the like. The network 106 may enable the UE 104 to communicate with other devices in the network architecture 100 and / or with the system 108. The network 106 may include a wireless card or some other transceiver connection to facilitate this communication. In another embodiment, the network 106 may be implemented as, or include any of a variety of different communication technologies such as a wide area network (WAN), a local area network (LAN), a wireless network, a mobile network, a Virtual Private Network (VPN), the Internet, a Public Switched Telephone Network (PSTN), or the like.

[0080] In an embodiment, the network 106 may include, by way of example but not limited to, at least a portion of one or more networks having one or more nodes that transmit, receive, forward, generate, buffer, store, route, switch, process, or a combination thereof, etc. one or more messages, packets, signals, waves, voltage or current levels, some combination thereof, or so forth. The network 106 may also include, by way of example but not limitation, one or more of, a wireless network, a wired network, an internet, an intranet, a public network, a private network, a packet-switched network, a circuit-switched network, an ad hoc network, an infrastructure network, the PSTN, a cable network, a cellular network, a satellite network, a fiber optic network, or some combination thereof.

[0081] In an embodiment, the UE 104 is communicatively coupled with the system 108 in the network 106. The system 108 may receive a connection request from the UE 104. The system 108 may send an acknowledgment of the connection request to the UE 104. The UE 104 may transmit a plurality of signals in response to the connection request. The system 108 is configured to manage stale sessions in the network 106.

[0082] Although FIG. 1 shows exemplary components of the network architecture 100, in other embodiments, the network architecture 100 may include fewer components, different components, differently arranged components, or additional functional components than depicted in FIG. 1. Additionally, oralternatively, one or more components of the network architecture 100 may perform functions described as being performed by one or more other components of the network architecture 100.

[0083] FIG. 2 illustrates an exemplary block diagram 200 of the system 108, in accordance with an embodiment of the disclosure. FIG. 2 is explained in conjunction with FIG. 1.

[0084]

[0085] In an embodiment, the system 108 may include one or more processor(s) 202. The one or more processor(s) 202 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and / or any devices that process data based on operational instructions. Among other capabilities, the one or more processor(s) 202 may be configured to fetch and execute computer-readable instructions stored in a memory 204 of the system 108. The memory 204 may be configured to store one or more computer-readable instructions or routines in a non-transitory computer readable storage medium, which may be fetched and executed to create or share data packets over a network service. The memory 204 may include any non-transitory storage device including, for example, volatile memory such as a Random-Access Memory (RAM), or a non-volatile memory such as an Erasable Programmable Read Only Memory (EPROM), a flash memory, and the like.

[0086] In an embodiment, the system 108 may include an interface(s) 206. The interface(s) 206 may include a variety of interfaces, for example, interfaces for data input and output devices (RO), storage devices, and the like. The interface(s) 206 may facilitate communication through the system 108. The interface(s) 206 may also provide a communication pathway for one or more components of the system 108. Examples of such components include, but are not limited to, a network function 212, an input unit 214, a processing unit 208, a transceiver unit 216, a determining unit 218, an execution unit 220 and a database 210.

[0087] In an embodiment, the system 108 may include the network function 212. The network function 212 includes the input unit 214, the processing unit 208, the transceiver unit 216, the determining unit 218 and the execution unit 220.

[0088] In an aspect, the system may be embedded in or associated with the network function (i.e., Access and Mobility Management Function (AMF)).

[0089] The input unit 214 is configured to receive a registration request from the UE 104. The registration request includes a Globally Unique Temporary Identifier (GUTI).

[0090] The processing unit 208 is configured to cooperate with the input unit 214. The processing unit 208 is further configured to generate a context request on receiving the registration request from the input unit 214. The context request includes the GUTI and a target area update (TAU) request message.

[0091] The processing unit 208 is configured to identify the specific network node based on the GUTI provided by the UE 104 in the registration request.

[0092] In an embodiment, the system 108 may include the processing unit 208 that may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing unit 208. In the examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing unit 208 may be processor-executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing unit 208 may comprise a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the processing unit 208. In such examples, the system 108 may comprise the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to the system108 and the processing resource. In other examples, the processing unit 208 may be implemented by electronic circuitry.

[0093] In an embodiment, the processing unit 208 is configured for managing stale sessions in the network 106. The processing unit 208 may be configured to receive a registration request from the UE 104. In an aspect, the registration request may include the GUTI and a TAU request message. The TAU request message is integrity protected using the EPS security context (for further security verification by the specific node network) in the registration request. The GUTI is a temporary identifier used in mobile networks, particularly in LTE (Long- Term Evolution) systems. The GUTI helps maintain user privacy and security by allowing mobile devices to communicate with the network without revealing their permanent identifiers, such as the International Mobile Subscriber Identity (IMSI). The GUTI is assigned to the UE 104 by the specific node network (i.e., MME) for identification in a Long-Term Evolution (LTE) network. The processing unit 208 may be embedded in the network function 212, such as the AMF that is configured to manage user access and mobility within the network 106. The registration request may be a request to switch the network 106, such as moving to the 5G network from the 4G network.

[0094] On receiving the registration request from the UE 104 the processing unit 208 may be configured to generate a context request. Further, the processing unit 208 may be configured to transmit the context request to the specific node network corresponding to the registration request received by the AMF. In an example, the processing unit 208 may be configured to identify an appropriate specific node network by the GUTI provided by the UE 104 in the registration request. In an aspect, the AMF derives the specific node network address and sends the context request to the specific node network. In an aspect, the context request may include GUTI (EPS GUTI) and the TAU request message. In an aspect, the specific node network validates the TAU message. The context request may request the Mobility Management (MM) context, current connection details, UE details, etc., from the specific node network. The MM context provides details about theUE's current location, routing area, and active connections. The current connection details include bearer contexts that define data transmission parameters and information on the allocated radio resources. The security context is also integral to the context request, encompassing the security keys and algorithms necessary for maintaining secure communications. In an example, the context request is meant to retrieve the context of the UE 104, which includes information such as its current state, security keys, and mobility information. The processing unit 208 is further configured to receive a context response message from the specific node network corresponding to the context request transmitted by the AMF. The context response message may include the MM context, current connection details, UE details, PDU connection details, etc.

[0095] Further, the determining unit 218 may be configured to determine a presence of an Information Element (IE) in the received context response message. The IE corresponds to a PDU Gateway Fully Qualified Domain Name (PGWFQDN) IE present under the PDN connection details. The PGWFQDN corresponds to a complete domain name specifying location of the PGW in the network 106.

[0096] In an aspect, the processing unit 208 may be configured to authenticate the UE corresponding to the PGWFQDN IE in the context response. This verification utilizes the Advanced Encryption Standard (AES), specific cipher keys, and encryption techniques. The network ensures secure communication and data integrity by employing AES, a widely recognized and robust encryption algorithm.

[0097] Further, the execution unit 220 is configured to transmit a context acknowledgement to the specific node network based on the determination of the presence of the PGWFQDN IE, upon authentication of the context response by the AMF.

[0098] In an aspect, the execution unit 220 is configured to generate the positive context acknowledgment on determining the presence of the IE in the atleast one PDN connection and a corresponding Session Management Function (SMF) discovered by the NRF using the IE.

[0099] In an example, the context acknowledgement may be a positive context acknowledgement corresponding to the presence of the PGWFQDN in the PDU connection and if corresponding SMF is discoverable via the NRF using PGWFQDN. In another example, the context acknowledgement may be a negative context acknowledgement corresponding to the absence of the PGWFQDN in the PDU connection, or a presence of the PGWFQDN in PDU connection and the PGWFQDN is not discoverable at the NRF.

[0100] The transceiver unit 216 further configured to trigger removal of stale sessions by transmitting at least one delete session request with an Operation Indicator (OI) indication towards one or more gateways based on the context acknowledgement. The OI is a control flag which indicates whether a receiving serving gateway is required to immediately perform an operation, such as sending a modify bearer request or forwarding a delete session request to a packet data network gateway.

[0101] In an embodiment, on receiving the positive context acknowledgement, the specific network node is configured to trigger removal of the at least one stale session by transmitting the at least one delete session request without the OI towards the SGW 402. Upon deleting the at least one stale session, the SGW 402 is configured to transmit the delete session response to the specific network node. The SGW 402 handles user data traffic and manage mobility as the UE 104 moves between different eNodeB (base stations). The SGW is responsible for routing and forwarding data packets between the UE 104 and external networks, as well as managing some of the mobility-related functions of the network 106. Further, the SGW 402 transmits a delete session request towards the PDN gateway PGW. The delete session response may correspond to a successful ending of the session at the SGW or an unsuccessful ending of the session at the SGW.

[0102] For the negative context acknowledgement, the MME transmits a delete session request with 01 indication to the SGW for ending the stale session corresponding to the registration request. The SGW may further send a delete session request to the PGW to end the stale session corresponding to the PDN session. The PGW may respond with a delete session response to the SGW. Finally, the SGW transmits the delete session response to the MME. The delete session response may correspond to a successful ending of PDN session at the SGW and the PGW or an unsuccessful ending of session at the SGW and the PGW.

[0103] In the system 108, the management of the at least one stale session includes the execution configured to generate the negative context acknowledgment on determining at least one of an absence of the IE in at least one PDN connection, the management of the at least one stale session includes the presence of the IE in the at least one PDN connection, where the IE is not discovered at a Network Repository Function (NRF).

[0104] In the system 108, the management of the at least one stale session includes upon receiving the negative context acknowledgment, the specific network node is configured to transmit the at least one delete session request with the OI towards the SGW. The SGW configured to forward the at least one delete session request to the PDN gateway PGW to delete the at least one stale session. Upon deleting the at least one stale session, the PGW is configured to transmit a delete session response to the SGW. The SGW configured to forward the delete session response to the specific network node.

[0105] In an embodiment, the system 108 may include a database 210 that includes data (e.g., the connection combinations, flags, binding session, Information Element (IE), etc.) that may be either stored or generated as a result of functionalities implemented by any of the components of the processor 202 or the processing unit 208.

[0106] In an overall aspect, if the PDN connectivity in the 4G network is performed using the PGW without SMF capability, then the PGWFQDN IE maybe absent from the Context Response message from the MME. Additionally, the AMF may not transfer the PDU session to the 5G network, if the PGWFQDN is absent, as SMF discovery is performed using the PGWFQDN. Further, even if the PGWFQDN is present, the AMF may not be able to discover the SMF corresponding to the PGWFQDN since the PGWFQDN is of the PGW without SMF capability, which is not registered to the NRF. So, when the AMF receives the Context Response without PGWFQDN, or with PGWFQDN of PGW that is not registered at NRF, the AMF sends the negative Context Acknowledgement message to the MME. On receiving the negative Context Acknowledgement, the MME maintains the PDN connection and does not send the Delete Session Request. Further, when the MME receives a Cancel Location Request (from a UDM or HSS), the MME may initiate the Delete Session Request with the 01 indication and clear the PDN sessions at the SGW. If the MME receives the positive Context Acknowledgement, the MME 304 may send the Delete Session Request without the 01 indication and the PDN session may be cleared only from the SGW, resulting in a stale session at PGW.

[0107] FIG. 3 illustrates an exemplary system architecture 300 for managing the stale sessions in the network 106, in accordance with an embodiment of the present disclosure. FIG. 3 is explained in conjunction with FIGS. 1 and 2.

[0108] FIG. 3 depicts a communication flow between the 4G network architecture and the 5G network architecture. A 4G UE 104-1 is connected to the 4G network through an eNodeB and interacts with the MME 304 for session management and mobility. The 4G UE 104-1 may be a device that supports the 4G network but may not support the 5G network. Further, the MME 304 manages mobility, authentication, and session setup in 4G. The MME 304 communicates with one or more Home Subscriber Servers (HSS) 308, 306 for authenticating the 4G UEs 104 via a S6a interface. The HSS ensures secure and efficient subscriber management in mobile networks. By centralizing subscriber data and authentication processes, the HSS enhances the network's ability to provide reliable services while maintaining user privacy and security. The S6a interface plays a crucial role inenabling the MME 304 to access subscriber data, authenticate users, manage sessions, and track the mobility of users across the 4G network. Further, the HSS manages user subscription information and provides the data to the MME 304 over the S6a interface. The S6a interface is based on the Diameter protocol, which is used for Authentication, Authorization, and Accounting (AAA) services in 4G networks. For example, the HSS 306 may manage users allowed in the 5G network, and the HSS 308 may handle 4G-specific user data.

[0109] Further, the HSS 306 and the HSS 308 may be connected to a Subscriber Location Function (SLF) 310. The SLF 310 is used to locate the HSS 306 and the HSS 308 to ensure user data is retrieved from a correct HSS instance, which is crucial for session management and mobility handling. The SLF 310 communicates with an Authentication, Authorization, and Accounting (AAA) server 312 to authenticate users, authorize network access, and manage accounting data. To ensure secure access, the AAA server 312 communicates with the 4G and 5G networks. In an embodiment, the HSS 306 is connected with a Unified Data Management (UDM) 314 that stores subscription data and manages user authentication and session management in the 5G network, similar to the HSS 308 in the 4G network. The UDM 314 is further connected to an AMF 316 via an N8 interface and the SMF 318 via an N10 interface. The N10 interface is used during authentication when the UE attempts to connect to the network. The UDM 314 provides subscription and authentication credentials to the Authentication Server Function (AUSF) over the N10 interface. The AUSF handles authentication requests for UE 104-1 in the 5G network. The AUSF works closely with other network functions, such as the UDM 314 and the AMF 316, to ensure that users are properly authenticated before accessing network services. The AMF 316 manages access and mobility in the 5G network for a 5G UE 104-2. The AMF 316 interfaces with the SMF 318 and UDM 314 to handle session establishment and mobility tracking via interfaces such as N11 and N10. The Ni l interface is responsible for exchanging signalling messages related to session management, including establishing, modifying, and releasing PDU sessions. Further, the SMF 318establishes and manages user sessions in the 5G network. The SMF 318 also coordinates with a User Plane Function (UPF) 320 for efficient data routing and network resource management via N4 interface. The N4 interface is used for communications between the Security Edge Protection Proxy (SEPP) functions of two different Public Land Mobile Networks (PLMNs), enabling secure interconnection between networks in roaming scenarios.

[0110] In an embodiment, the AMF 316 is also connected to the MME 304 via the N26 interface. The N26 interface facilitates communication between the 4G MME 304 and the 5G AMF 316, ensuring that 4G users may hand over to the 5G network without service interruption.

[0111] Further, the AMF 316 and the SMF 318 are connected to a Policy Control Function (PCF) 322 and a Charging Function (CHF) 324 via various interfaces such as N15, N7, N40 and N28. The N15 interface facilitates the synchronization between AMF 316 and PCF 322 to maintain consistency in the data used for authentication, authorization, and mobility management. The N7 interface allows the PCF 322 to communicate with the SMF 318 to provide session-level policies for managing user data sessions. The policies may include Quality of Service (QoS) rules, charging policies, and access control. The N40 interface allows the SMF 318 to access subscription and policy data stored in the CHF 324. Further, the N28 interface enables the CHF 324 to interact with the PCF 322 to handle user- related data and subscription information. The PCF 322 manages policy control and enforces network rules across various services and applications. The PCF 322 primary function governs network resources allocated to users and applications, ensuring efficient and fair network usage. The PCF 322 is further connected to a Binding Support Function (BSF) 346. The BSF 346 manages authentication, authorization, and policy-related functions, specifically binding user sessions to specific resources via IP Multimedia System (IMS) 348. The IMS 348 delivers IPbased multimedia services, such as voice, video, messaging, and data, over LTE, 4G, and 5G networks. In an aspect, when the users access multimedia services via the IMS 348, the BSF 346 binds the session’s IP address to the correct usercredentials and policies, ensuring that services are authenticated and that policies such the QoS are enforced. Further, the CHF 324 handles charging mechanisms in the 5G network, interfacing with the PCF 322 and other components for real-time charging of services. The CHF 324 is further connected to an Online Charging System (OCS) 326 that manages real-time charging for services and usage for 4G and 5G networks. The OCS 326 determines how users are billed for their data, voice, SMS, or other services in real-time, based on their usage. The OCS 326 is further connected to a Policy and Charging Rules Function (PCRF) 330 and a Packet Gateway (PGW) 332. The PCRF 330 manages policy control and charging rules for 4G and 5G traffic. The PCRF 330 interfaces with the OCS 326 and the PGW 332 to apply data usage policies.

[0112] The PGW 332 routes traffic between the mobile network and external data networks, such as an Internet 334. The PGW 332 communicates with the UPF 320 via an SGi interface in the 5G network for seamless handover and data flow management. The SGi interface is responsible for routing user traffic from the mobile core network to external IP networks. During idle mode mobility from 4G to 5G, the MME 304 tries to transfer the user’s session, such as the PDN connection to the 5G network. However, if the UE 104-1 is not allowed in the 5G network, the MME 304 incorrectly assumes the session is transferred, which leads to stale sessions at the PGW 332. When the HSS 306 sends the Cancel Location Request after the UE 104-1 moves from the 4G network, the PGW 332 is not notified properly and may not clear the session, leading to stale entries.

[0113] Further, the PGW 332 is connected to an S2a Mobility over General Packet Radio Service Tunnelling Protocol (GTP) (SAMOG) 336 that facilitates mobility management for UE 104-3 connecting via trusted Wireless Local Area (WLAN) networks, enhancing the flexibility of user connectivity options. The trusted WLAN network may be an Access Point (AP) 344 connecting the UE 104- 3 to the SAMOG 336 via a SWw interface. The AP 344 refers to a device or a network interface that allows the UE 104-3 such as mobile phones or other wireless devices, to connect to a telecommunications network, typically for data services.The SWw interface enables communication between the Trusted WLAN Access Gateway (TWAG) and the AAA Server 312 for managing authentication and authorization, when a user connects to the 4G LTE or the 5G core network over a Wi-Fi connection. Further, the architecture 300 includes an Evolved Packet Data Gateway (ePDG) 338 that manages secure access for UE 104-4 connecting through untrusted non-3GPP access, such as Wi-Fi. The ePDG 338 ensures secure tunnelling to the core network. The ePDG 338 may be connected to AAA server 312 via a SWm interface for authentication, authorization, and accounting purposes. The SWm interface is primarily used when the UE 104-3 connects to the LTE network through trusted networks like Wi-Fi.

[0114] In simpler words, the 4G UE 104-1 establishes a connection via the MME 304 and PDN connections are set up with the PGW 332. During idle mode mobility of the 4G UE 104-1 from the 4G network to the 5G network, the MME 304 attempts to transfer the PDN connections to the 5G network, but the AMF 316 may not handle the transfer if the 4G 104-1 is not authorized for the 5G network access. Further, the AMF 316 sends a negative acknowledgment to the MME 304 over the N26 interface, indicating that the transfer is unsuccessful. However, the MME 304 incorrectly assumes that the session has been successfully transferred to the 5G network and fails to properly clear the session from the PGW 332, resulting in stale sessions. Further, the PGW 332 maintains the session even after the HSS 306 sends a Cancel Location Request, as the MME 304 failed to inform the PGW 332 about the session termination.

[0115] FIG. 4 illustrates an exemplary flow chart 400 of a method for managing stale sessions in the network, in accordance with an embodiment of the present disclosure. FIG. 4 is explained in conjunction with FIGS. 1 and 3.

[0116] The flow chart 400 is depicted between the UE 104, the AMF 316, the MME 304, and a Servicing Gateway (SGW) 402. A new radio (NR) 434 may be utilized for communication between the UE 104 and the AMF 316. For example, the NR 434 may correspond to 5G network.

[0117] At step 404, the AMF 316 receives a mobility registration request from the UE 104. The request concerns registering the UE 104 with the 5G network. Further, the AMF 316 generates a context request corresponding to the mobility registration request.

[0118] At step 406, a context request is received by the MME 304 communicated from the AMF 316. The context request is the message sent by the AMF 316 to the MME 304 to retrieve the context related to the UE, including session information, authentication state, and Packet Data Network (PDN) connection details. The context request is triggered based on the GUTI provided by the UE 104. The AMF 316 derives the MME 304 address and 4G GUTI from an old 5G-GUTI and sends the context request to the MME 304, including GUTI mapped from 5G-GUTI. Further, the MME 304 generates a context response related to the context request.

[0119] At step 408, the context response along with the PDN connection IE is received by the AMF 316 from the MME 304. The MME 304 responds with the context response, including session information, PDN connection details, connection status in the 4G network, etc. The AMF 316 converts the received context response into the 5G Mobility Management (MM) Context. The received UE context includes IMSI, Mobile Equipment (ME) Identity, UE evolved Packet System (EPS) security context, UE Network Capability and EPS Bearer context(s) and may also include Long-Term Evolution for Machines (LTE-M) Indication.

[0120] At step 410, the AMF 316 may authenticate the UE 104 by an Authentication Server Function (AUSF) to ensure secure communication between the UE 104 and the network 106.

[0121] At step 412, the MME 304 receives the positive context acknowledgement from the AMF 316. The positive context acknowledgement may correspond to the presence of the PGWFQDN in the PDN connection, and the SMF 318 is discoverable via the NRF using the PGWFQDN.31

[0122] At step 414, the AMF 316 may perform the UDM 314 selection. TheAMF 316, based on the SUPI, selects a UDM 314, then UDM 314 may select a UDR instance.

[0123] At step 416-1, the AMF 316 may send the UE 104 context management (UECM) registration request (i.e., NUDM_UECM_Registration) to the selected UDM 314. In response, the selected UDM 314 may send the UECM registration response. In an aspect, if the AMF 316 has changed since the last registration procedure, if the UE 104 registration type is initial registration or emergency registration, or if the UE 104 provides the SUPI which does not refer to a valid context in the AMF 316, or if the UE 104 registers to the same AMF 316 it has already registered to a non-3GPP access (i.e. the UE 104 is registered over a non-3GPP access and initiates this registration procedure to add a 3GPP access), the AMF 316 registers with the UDM 314 using NUDM_UECM_Registration for the access to be registered (and subscribes to be notified when the UDM 314 deregisters the AMF 316). The UDM 314, based on the registration type in the NUDM_UECM_Registration request, can act on steering of roaming (SoR) information. In an aspect, the UECM registration is a process where the UE 104 establishes a connection with the network 106 and registers its presence. This involves sending registration requests, securing the connection, and updating the network about the UE's 104 capabilities and preferences. The process ensures that the UE 104 can receive services and that the network 106 knows its location and status.

[0124] At step 416-2, the AMF 316 may send a subscriber data management (SDM) get request (i.e., NUDM_SDM_Get) to the selected UDM 314. In an aspect, the SDM get request is sent to retrieve UE 104 subscription data relevant to their operation from the UDM 314. In response to the SDM get request, the selected UDM 314 may send the SDM response comprising the UE 104 subscription data to the AMF 316. In an aspect, After AMF 316 has successfully completed the NUDM_UECM_Registration operation and if the AMF 316 does not have subscription data for the UE, the AMF 316 retrieves the Access and MobilitySubscription data, SMF Selection Subscription data, the UE 104 context in the SMF 318 data and LCS mobile origination using the NUDM_SDM_Get.

[0125] At step 416-3, the AMF 316 may send the SDM subscribe request (i.e., NUDM_SDM_Subscribe) to the selected UDM 314. In an aspect, the AMF 316 subscribes for updates to subscription data indicated by the 'subscription data type' input. The UDM 314 may check whether the requested AMF 316 is authorized to subscribe to the requested updates. In an aspect, the SDM subscriber request is sent to get UE 104 subscription data changes. In response to the SDM subscribe request, the selected UDM 314 may send the subscription data changes to the AMF 316.

[0126] At step 418, the AMF 316 may perform the PCF selection. In an aspect, if the AMF 316 decides to initiate PCF communication, the AMF 316 performs PCF selection. If the AMF 316 decides to use a visited (V-)PCF identified by the (V-)PCF ID included in UE 104 context from the AMF 316, the AMF 316 contacts the (V-)PCF identified by the (V-)PCF ID to obtain policy. If the AMF 316 decides to perform PCF discovery and selection, and the AMF 316 selects a (V)-PCF, it may select a home-PCF (H-PCF) (for roaming scenario).

[0127] At step 420, a process of an AM policy association establishment / modification is performed between the AMF 316 and the selected PCF (403). In an aspect, the AMF 316 performs the AM policy association establishment / modification. The AM policy association establishment / modification is skipped for the emergency registration. If the AMF 316 selects a new (V-)PCF, it performs the AM policy association establishment with the selected (V-)PCF. If the (V-)PCF identified by the (V-)PCF ID included in the UE 104 context from the AMF 316 is used, the AMF 316 performs the AM policy association modification with the (V-)PCF.

[0128] At step 422, the MME 304 sends the cancel location when the UE 104 transitions from the 4G to the 5G while in idle mode. A series of signaling interactions is initiated to ensure proper deregistration from the 4G network andregistration in the 5G core. The process begins when the AMF 316 receives a registration request from the UE 104 and subsequently transmits a Nudm_UECM_Registration message to the UDM 314 function, allowing the UDM 314 to update the UE 104 registration context. Upon receiving this message, the UDM 314 determines whether the UE 104 was previously registered in the 4G domain, typically with the MME 304. If such a registration is detected, the UDM 314 initiates a deregistration procedure by sending a Nhss_UECM_SNDeregistration request to the HSS, specifying the deregistration reason as either “4G to 5 G mobility” or “Initial and Single Registration,” depending on the flags set in the registration request.

[0129] The HSS proceeds to send a Cancel Location Request (CLR) to the MME 304 via the S6a interface. The MME 304 send the CLR message to the UDM 314. The CLR message includes a cancellation type field, which is set to “MME Update Procedure,” indicating that the cancellation is due to a mobility-triggered update rather than a subscription termination. Upon receiving the CLR, the MME 304 processes the request and releases the UE 104 4G registration context.

[0130] At step 424, the UDM 314 sends a Cancel Location Acknowledge (CLA) to the MME 304. It then responds to the HSS with the CLA message, confirming the successful deregistration of the UE 104 from the 4G network. This sequence ensures that the UE 104 maintains a single active registration in the 5G domain, thereby preventing dual registration and enabling seamless mobility between network generations.

[0131] At step 426, the MME 304 forwards a delete session request (without OI indication) to the SGW 402. The SGW 402 is responsible for managing and routing user data between the UE 104 and external PDNs, such as the Internet. The delete session request corresponds to initiating a PDN connection release at the SGW 402.

[0132] At step 428, the SGW 402 sends a delete session response to the MME 304. The response may correspond to the successful deletion of PDN sessions at the SGW 402.

[0133] At step 430, the AMF 316 may send a registration accept response to the UE 104. Upon successful registration, the AMF 316 sends the registration accept response to the UE 104.

[0134] At step 432, the UE 104 may send a response indicating the registration is complete to the AMF 316. In an aspect, the UE 104 sends a registration complete message to the AMF 316 when it has successfully updated itself after receiving any of the configured network slice selection assistance information (NSSAI) for the serving PLMN, mapping of configured NSSAI, network slice simultaneous usage group (NSSRG) information, network slice access group (NSAG) information and a network slicing subscription change indication, or closed access group (CAG) information.

[0135] FIG. 5 illustrates another exemplary flow chart 500 of a method for managing stale sessions in the network, in accordance with an embodiment of the present disclosure. FIG. 5 is explained in conjunction with FIGS. 1 and 4.

[0136] The flow chart 500 is depicted between the UE 104, the AMF 316, the MME 304, the SGW 402, and the PGW 332.

[0137] At step 502, the AMF 316 receives the mobility registration request from the UE 104. The mobility registration request concerns registering the UE 104 with the 5G network. Further, the AMF 316 generates the context request corresponding to the mobility registration request.

[0138] At step 504, the context request is received by the MME 304 from the AMF 316. The context request is the message sent by the AMF 316 to the MME 304 to retrieve the UE context, including session information, authentication state, and Packet Data Network (PDN) connection details. The context request istriggered based on the GUTI provided by the UE 104. The AMF 316 derives the MME address and 4G GUTI from an old 5G-GUTI (may be included in the registration request) and sends the Context Request to the MME 304. Further, the MME 304 generates the context response related to the context request.

[0139] At step 506, the AMF 316 receives the context response, along with the PDN connection, from the MME 304. The MME 304 responds with the context response, including session information, PDN connection details, connection status in the 4G network, etc. The PDN connection details are embedded as the IE in the context response. The AMF 316 converts the received context response into the MM Context.

[0140] At step 508, the AMF 316 may authenticate the UE 104 by an Authentication Server Function (AUSF) to ensure secure communication between the UE 104 and the network 106.

[0141] At step 510, the negative context acknowledgement is received by the MME 304 from the AMF 316. The negative context acknowledgement may correspond to an absence of PGWFQDN in the PDN connection. In another embodiment, the negative context acknowledgement may correspond to a presence of PGWFQDN in the PDN connection. Still, the PGWFQDN may not be discovered at the NRF, as the PGWFQDN is of the PGW 332 without SMF 318 capability.

[0142] At step 512, the AMF 316 may perform the UDM 314 selection. The AMF 316, based on the SUPI, selects a UDM 314, then UDM 314 may select a UDR instance.

[0143] At step 514-1, the AMF 316 may send the UECM registration request (i.e., NUDM_UECM_Registration) to the selected UDM 314. In response, the selected UDM 314 may send the UECM registration response. In an aspect, if the AMF 316 has changed since the last registration procedure, if the UE 104 registration type is initial registration or emergency registration, or if the UE 104 provides the SUPI which does not refer to a valid context in the AMF 316, or if theUE 104 registers to the same AMF 316 it has already registered to a non-3GPP access (i.e. the UE 104 is registered over a non-3GPP access and initiates this registration procedure to add a 3GPP access), the AMF 316 registers with the UDM 314 using NUDM_UECM_Registration for the access to be registered (and subscribes to be notified when the UDM 314 deregisters the AMF 316). The UDM 314, based on the registration type in the NUDM_UECM_Registration request, can act on steering of roaming (SoR) information. In an aspect, the UECM registration is a process where the UE 104 establishes a connection with the network 106 and registers its presence. This involves sending registration requests, securing the connection, and updating the network about the UE's 104 capabilities and preferences. The process ensures that the UE 104 can receive services and that the network 106 knows its location and status.

[0144] At step 514-2, the AMF 316 may send the SDM get request (i.e., NUDM_SDM_Get) to the selected UDM 314. In an aspect, the SDM get request is sent to retrieve UE 104 subscription data relevant to their operation from the UDM 314. In response to the SDM get request, the selected UDM 314 may send the SDM response comprising the UE 104 subscription data to the AMF 316. In an aspect, After AMF 316 has successfully completed the NUDM_UECM_Registration operation and if the AMF 316 does not have subscription data for the UE, the AMF 316 retrieves the Access and Mobility Subscription data, SMF Selection Subscription data, the UE 104 context in the SMF 318 data and LCS mobile origination using the NUDM_SDM_Get.

[0145] At step 514-3, the AMF 316 may send the SDM subscribe request (i.e., NUDM_SDM_Subscribe) to the selected UDM 314. In an aspect, the AMF 316 subscribes for updates to subscription data indicated by the 'subscription data type' input. The UDM 314 may check whether the requested AMF 316 is authorized to subscribe to the requested updates. In an aspect, the SDM subscriber request is sent to get UE 104 subscription data changes. In response to the SDM subscribe request, the selected UDM 314 may send the subscription data changes to the AMF 316.

[0146] At step 516, the AMF 316 may perform the PCF selection. In an aspect, if the AMF 316 decides to initiate PCF communication, the AMF 316 performs PCF selection. If the AMF 316 decides to use a visited (V-)PCF identified by the (V-)PCF ID included in UE 104 context from the AMF 316, the AMF 316 contacts the (V-)PCF identified by the (V-)PCF ID to obtain policy. If the AMF 316 decides to perform PCF discovery and selection, and the AMF 316 selects a (V)-PCF, it may select the H-PCF (for roaming scenario).

[0147] At step 518, a process of an AM policy association establishment / modification is performed between the AMF 316 and the selected PCF 322. In an aspect, the AMF 316 performs the AM policy association establishment / modification. The AM policy association establishment / modification is skipped for the emergency registration. If the AMF 316 selects a new (V-)PCF, it performs the AM policy association establishment with the selected (V-)PCF. If the (V-)PCF identified by the (V-)PCF ID included in the UE 104 context from the AMF 316 is used, the AMF 316 performs the AM policy association modification with the (V-)PCF.

[0148] At step 520, the MME 304 sends the cancel location when the UE 104 transitions from the 4G to the 5G while in idle mode, a series of signaling interactions are initiated to ensure proper deregistration from the 4G network and registration in the 5G core. The process begins when the AMF 316 receives a registration request from the UE 104 and subsequently transmits a Nudm_UECM_Registration message to the UDM 314 function, allowing the UDM 314 to update the UE 104 registration context. Upon receiving this message, the UDM 314 determines whether the UE 104 was previously registered in the 4G domain, typically with the MME 304. If such a registration is detected, the UDM 314 initiates a deregistration procedure by sending a Nhss_UECM_SNDeregistration request to the HSS, specifying the deregistration reason as either “4G to 5 G mobility” or “Initial and Single Registration,” depending on the flags set in the registration request.

[0149] The HSS proceeds to send the CLR to the MME 304 via the S6a interface. The MME 304 send the CLR message to the UDM 314. The CLR message includes a cancellation type field, which is set to “MME Update Procedure,” indicating that the cancellation is due to a mobility-triggered update rather than a subscription termination. Upon receiving the CLR, the MME 304 processes the request and releases the UE 104 4G registration context.

[0150] At step 522, the UDM 314 sends the CLA to the MME 304. It then responds to the HSS with the CLA message, confirming the successful deregistration of the UE 104 from the 4G network. This sequence ensures that the UE 104 maintains a single active registration in the 5G domain, thereby preventing dual registration and enabling seamless mobility between network generations.

[0151] At step 524, the MME 304 forwards the delete session request to the SGW 402. The SGW 402 manages and routes user data between the UE 104 and the external PDNs, such as the Internet. The delete session request may include the OI indication that is used to terminate the UE 104 session and release network resources allocated for the UE 104. The delete session request may also initiate the deletion of PDN sessions at the SGW 402.

[0152] At step 526, the SGW 402 forwards the delete session request to the PGW 332 The delete session request may correspond to deleting stale PDN sessions at the PGW 332.

[0153] At step 528, the PGW 332 sends a delete session response to the SGW 402. The delete session response may correspond to the successful deletion of sessions at the PGW 332.

[0154] At step 530, a delete session response is sent to the MME 304 by the SGW 402. The delete session response may correspond to the successful deletion of PDN sessions at the SGW 402.

[0155] At step 532, the AMF 316 may send a registration accept response to the UE 104. Upon successful registration, the AMF 316 sends the registration accept response to the UE 104.

[0156] At step 534, the UE 104 may send a response indicating the registration is complete to the AMF 316. In an aspect, the UE 104 sends a registration complete message to the AMF 316 when it has successfully updated itself after receiving any of the configured the NSSAI for the serving PLMN, mapping of configured NSSAI, the NSSRG information, the NSAG information and a network slicing subscription change indication, or the CAG information.

[0157] In summary, the present disclosure may be configured to perform the following steps:1. The UE 104 sends the Mobility Registration Request as part of the 4G to the 5G idle mode mobility.2. The AMF 316 sends the Context Request to the MME 304 identified by the GUTI provided by the UE 104.3. The MME 304 responds with the Context Response message, including the MM Context, PDN Connections and other details.4. The AMF 316 checks for the presence of PGWFQDN IE under PDN Connections in Context Response.5. The AMF 316 may send the positive Context Acknowledgement to the MME 304 after successful authentication. After successful authentication / security, the AMF 304 sends a. Positive Context Acknowledgement, if PGWFQDN is present under PDN Connections IE and corresponding SMF can be discovered via NRF using the PGWFQDN. b. Negative Context Acknowledgement, if PGWFQDN is not present under PDN Connections IE. c. Negative Context Acknowledgement, if the PGWFQDN is present under PDN Connections IE cannot be discovered atNRF since the PGWFQDN is of a standalone PGW 332 (without SMF capability).6. Further the MME 304 sends Delete Session Request with 01 indication when Context Acknowledgement is negative. This further trigger the Delete Session Request to the PGW 332 from the SGW 402.

[0158] FIG. 6 illustrates a flowchart of a method 600 for managing the stale sessions in the network (106), according to certain embodiments. FIG. 6 is explained in conjunction with FIGS. 1-5.

[0159] The method 600 includes a series of steps. These steps are only illustrative, and other alternatives may be considered where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the present disclosure.

[0160] At step 602, the method 600 includes receiving, by the network function 212, a registration request from the UE 104.

[0161] In an embodiment, the registration request includes the GUTI,

[0162] At step 604, the method 600 includes generating, by the network function 212, a context request upon receiving the registration request.

[0163] In an embodiment, the context request includes the GUTI and a target area update (TAU) request message.

[0164] For example, when the UE 104 submits the registration request to the mobile network, the network function 212 detects this request and subsequently generates a context request. The context request may facilitate retrieval or update of relevant context information necessary for processing the registration request, such as subscriber data, session parameters, or mobility management information.

[0165] At step 606, the method 600 includes transmitting, by the network function 212, the generated context request to a specific network node 304.

[0166] In an embodiment, the network function 212, is the AMF 316 and the specific network node 304 is the MME 304.

[0167] At step 608, the method 600 includes receiving, by the network function 212, a context response message from the specific network node 304 corresponding to the context request.

[0168] In an embodiment, the context response message includes at least one of the MM context, UE 104 details, PDN connection details, and the current connection status.

[0169] For example, consider a mobile communication system wherein the UE 104 initiates the registration request. The registration request transmitted from the UE 104 includes GUTI. Subsequently, the network entity sends a context request containing the same GUTI and the TAU request message to update the MM context. In response, the network 106 returns a context response message, which includes at least one of the following: the MM context (such as authentication and security parameters), specific details of the UE 104 (such as device capabilities or identifiers), PDN connection details (such as IP address assignments and session information), and the current connection status (indicating active or idle state).At step 610, the method 600 includes determining, by the network function 212, a presence of an IE in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE. The context acknowledgment is a positive context acknowledgment or a negative context acknowledgment.

[0170] In an embodiment, after receiving the context response message, the network function 212 evaluates whether a specific IE, such as a PGWFQDN, is present. If the IE is detected, the positive context acknowledgment is sent to the originating node, otherwise, the negative context acknowledgment is issued, which may indicate missing expected context information and that corrective action might be necessary.

[0171] In an embodiment, the IE includes the PDN gateway PGWFQDN representing a complete domain name with a location of the PGW in the network.

[0172] At step 612, the method 600 includes transmitting, by the network function, the context acknowledgement to the specific network node.

[0173] In an embodiment, in managing at least one stale session during context response evaluation, the network function 212 may examine each PDN connection. If the required IE, such as PGWFQDN, is absent in any PDN connection, or present but cannot be matched to a registered entity in the NRF, the network function generates the negative context acknowledgment, indicating ineffective session management for the given PDN connection. If the IE is present in a PDN connection and the NRF can locate a corresponding SMF 318 using that IE, the positive context acknowledgment is generated, confirming proper management of the stale session with valid session resources.

[0174] At step 614, the method 600 includes managing, by the specific network node 304, at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.

[0175] In an embodiment, when managing at least one stale session, if a negative context acknowledgment is received at the specific network node (e.g., MME 304). The MME 304 transmits a delete session request with the OI to the SGW 402. The SGW 402 then forwards the at least one delete session request to the PDN gateway PGW 332, instructing deletion of the identified stale session. After successful deletion, the PGW 332 transmits a delete session response to the SGW 402, which subsequently forwards the delete session response to the specific network node 304, confirming the stale session has been removed.

[0176] In an embodiment, when the positive context acknowledgment is received, the specific network node (such as MME 304) triggers removal of the stale session by sending a delete session request lacking the OI to the SGW 402.After the SGW 402 deletes the stale session, it transmits a corresponding delete session response to the specific network node 304, confirming successful session removal.

[0177] FIG. 7 illustrates an exemplary computer system 700 in which or with which embodiments of the present disclosure may be implemented. As shown in FIG. 7, the computer system 700 may include an external storage device 710, a bus 720, a main memory 730, a read-only memory 740, a mass storage device 750, communication port(s) 760, and a processor 770. A person skilled in the art will appreciate that the computer system 700 may include more than one processor and communication ports. The processor 770 may include various modules associated with embodiments of the present disclosure. The communication port(s) 760 may be any of an RS-232 port for use with a modem-based dialup connection, a 10 / 100 Ethernet port, a Gigabit or 10 Gigabit port using copper or fiber, a serial port, a parallel port, or other existing or future ports. The communication port(s) 760 may be chosen depending on a network, such a Local Area Network (LAN), Wide Area Network (WAN), or any network to which the computer system 700 connects.

[0178] The main memory 730 may be a Random Access Memory (RAM), or any other dynamic storage device commonly known in the art. The read-only memory 740 may be any static storage device(s) e.g., but not limited to, a Programmable Read Only Memory (PROM) chips for storing static information e.g., start-up or Basic Input / Output System (BIOS) instructions for the processor 770. The mass storage device 750 may be any current or future mass storage solution, which can be used to store information and / or instructions. Exemplary mass storage device 750 includes, but is not limited to, Parallel Advanced Technology Attachment (PATA) or Serial Advanced Technology Attachment (SATA) hard disk drives or solid-state drives (internal or external, e.g., having Universal Serial Bus (USB) and / or Firewire interfaces), one or more optical discs, Redundant Array of Independent Disks (RAID) storage, e.g. an array of disks.

[0179] The bus 720 communicatively couples the processor 770 with the other memory, storage, and communication blocks. The bus 720 may be, e.g. a Peripheral Component Interconnect (PCI) / PCI Extended (PCI-X) bus, Small Computer System Interface (SCSI), Universal Serial Bus (USB), or the like, for connecting expansion cards, drives, and other subsystems as well as other buses, such a front side bus (FSB), which connects the processor 770 to the computer system 700.

[0180] Optionally, operator and administrative interfaces, e.g. a display, keyboardjoystick, and a cursor control device, may also be coupled to the bus 720 to support direct operator interaction with the computer system. Other operator and administrative interfaces can be provided through network connections connected through the communication port(s) 760. Components described above are meant only to exemplify various possibilities. In no way should the aforementioned exemplary computer system 700 limit the scope of the present disclosure.

[0181] In an exemplary embodiment, a computer programproduct comprising a non-transitory computer-readable medium includes instructions that, when executed by one or more processors, cause the one or more processors to execute a method for managing stale sessions in a network. The method includes receiving, by a network function, a registration request from the UE, generating, by the network function, a context request upon receiving the registration request, transmitting, by the network function, the generated context request to a specific network node, receiving, by the network function, a context response message from the specific network node corresponding to the context request, determining, by the network function, a presence of the IE in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE, where the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment, transmitting, by the network function, the context acknowledgement to the specific network node and managing, by the specific network node, at least one stale session by transmittingat least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function.

[0182] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

[0183] The method and system of the present disclosure may be implemented in a number of ways. For example, the methods and systems of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order for the steps of the method is for illustration only, and the steps of the method of the present disclosure are not limited to the order specifically described above unless specifically stated otherwise. Further, in some embodiments, the present disclosure may also be embodied as programs recorded in a recording medium, the programs including machine-readable instructions for implementing the methods according to the present disclosure. Thus, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0184] The present disclosure provides a technical advancement related to a system and method for managing stale sessions at the PGWs during the 4G to the 5G idle mode mobility, the UE is restricted to the 4G networks. The advancement addresses the challenges of the MME failing to clear the PDN session context at the PGW when session transfer to the 5G is not possible, resulting in stale sessions. The present disclosure enables the AMF to detect absence or non-discoverability of the PGWFQDN IE in a context response. In such cases, the AMF transmits a negative context acknowledgment to the MME , which retains the session contextand subsequently sends the delete session request with the 01 to ensure effective deletion of stale sessions at both the SGW and PGW. This present disclosure may improve existing call flow procedures by preventing stale sessions and enhancing network resource management.

[0185] While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be implemented merely as illustrative of the disclosure and not as a limitation.ADVANTAGES OF THE PRESENT DISCLOSURE

[0186] The present disclosure described herein above has several technical advantages as follows:

[0187] Prevention of stale sessions: The present disclosure introduces a system that prevents the creation of stale sessions at the Packet Data Network Gateway (PGW) when users restricted to the 4G network attempt idle mode mobility from 4G to 5G, ensures that unnecessary sessions do not persist, and improves the efficiency of network resources.

[0188] Improved Session Management: The present disclosure ensures that a Mobility Management Entity (MME) maintains the Packet Data Network (PDN) connection and sends a Delete Session Request with an Operation Indicator (OI). The present disclosure provides a reliable mechanism to clear sessions from both Serving Gateway (SGW) and the PGW, ensuring complete session cleanup.

[0189] Accurate Handling of PDN Connection Transfer: The present disclosure enables an Access and Mobility Management Function (AMF) toproperly handle cases where PDN connections cannot be transferred to 5G due to the absence or unreachability of a PGW Fully Qualified Domain Name (FQDN), avoiding false assumptions about session transfers and ensuring that the MME takes corrective actions.

[0190] Enhanced Call Flow Control: The present disclosure ensures that negative Context Acknowledgment is sent by the AMF in situations where PDN connection transfer is not possible, preventing the MME from prematurely clearing session context and adding robustness to the handover process during 4G to 5G mobility.

[0191] Resource Efficiency: By clearing sessions properly from the PGW and preventing stale sessions, the present disclosure contributes to better resource management within the network, minimizing unnecessary usage of network capacity.

Claims

We claim:

1. A method (600) for managing stale sessions in a network (106), the method (600) comprising: receiving (602), by a network function (212), a registration request from a User Equipment (UE) (104); generating (604), by the network function (212), a context request upon receiving the registration request; transmitting (606), by the network function (212), the generated context request to a specific network node (304); receiving (608), by the network function (212), a context response message from the specific network node (304) corresponding to the context request; determining (610), by the network function (212), a presence of an Information Element (IE) in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE, wherein the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment; transmitting (612), by the network function (212), the context acknowledgement to the specific network node (304); and managing (616), by the specific network node (304), at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function (212).

2. The method (600) as claimed in claim 1, wherein at least one of: the registration request comprises a Globally Unique Temporary Identifier (GUTI), the context request comprises the GUTI and a target area update (TAU) request message, andthe context response message comprises at least one of a mobility management (MM) context, UE (104) details, Packet Data Network (PDN) connection details, and a current connection status.

3. The method (600) as claimed in claim 2, further comprising: identifying, by the network function (212), the specific network node (304) based on the GUTI provided by the UE (104) in the registration request.

4. The method (600) as claimed in claim 1, wherein the network function (212) is an Access and Mobility function (AMF) (316) and the specific network node (304) is a Mobility Management Entity (MME) (304).

5. The method (600) as claimed in claim 1 , wherein the IE comprises a Packet Data Network (PDN) gateway (PGW) Fully Qualified Domain Name (PGWFQDN) representing a complete domain name with a location of a PGW (332) in the network (106).

6. The method (600) as claimed in claim 1, wherein the management of the at least one stale session comprises: generating, by the network function (212), the negative context acknowledgment on determining at least one of: an absence of the IE in at least one PDN connection; and a presence of the IE in the at least one PDN connection, wherein the IE is not discovered at a Network Repository Function (NRF); and generating, by the network function (212), the positive context acknowledgment on determining a presence of the IE in the at least one PDN connection and a corresponding Session Management Function (SMF) discovered by the NRF using the IE.

7. The method (600) as claimed in claim 1, wherein the management of the at least one stale session comprises: upon receiving the negative context acknowledgment, transmitting, by the specific network node (304), the at least one delete session request with an operation indicator (01) towards a Serving Gateway (SGW) (402); forwarding, by the SGW (402), the at least one delete session request to a Packet Data Network (PDN) gateway (PGW) (332) to delete the at least one stale session; upon deleting the at least one stale session, transmitting, by the PGW (332), a delete session response to the SGW (402); and forwarding, by the SGW (402), the delete session response to the specific network node (304).

8. The method (600) as claimed in claim 1, wherein the management of the at least one stale session comprises: on receiving the positive context acknowledgement, triggering, by the specific network node (304), removal of the at least one stale session by transmitting the at least one delete session request without the OI towards the SGW (402); and upon deleting the at least one stale session, transmitting, by the SGW (402), the delete session response to the specific network node (304).

9. A system (108) for managing stale sessions in a network, wherein the system (108) comprising a network function (212), the network function (212) comprising: an input unit (214) configured to receive a registration request from a User Equipment (UE) (104); a processing unit (208) configured to cooperate with the input unit and is further configured to generate a context request on receiving the registration request from the input unit (214); a transceiver unit (216) configured to:transmit the generated context request to a specific network node (304) corresponding to the registration request; and receive a context response message from the specific network node (304) corresponding to the context request; a determining unit (218) configured to determine a presence of an Information Element (IE) in the received context response message; an execution unit (220) configured to generate a context acknowledgement based on the determination of the presence of the IE, wherein the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment; and the transceiver unit (216) configured to transmit the context acknowledgement to the specific network node (304), wherein the specific network node (304) is configured to manage at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function (212).

10. The system (108) as claimed in claim 9, wherein: the registration request comprises a Globally Unique Temporary Identifier (GUTI), the context request comprises the GUTI and a target area update (TAU) request message, and the context response message comprises at least one of a mobility management (MM) context, UE details, Packet Data Network (PDN) connection details, and a current connection status.

11. The system (108) as claimed in claim 10, wherein the processing unit (208) configured to identify the specific network node (304) based on the GUTI provided by the UE (104) in the registration request.

12. The system (108) as claimed in claim 9, wherein the network function (212) is an Access and Mobility function (AMF) (316), and wherein the specific network node (304) is a Mobility Management Entity (MME) (304).

13. The system (108) as claimed in claim 9, wherein the IE comprises a Packet Data Network (PDN) gateway (PGW) Fully Qualified Domain Name (PGWFQDN) representing a complete domain name with a location of a PGW (332) in the network.

14. The system (108) as claimed in claim 9, wherein the management of the at least one stale session comprises: the execution unit (220) configured to generate the negative context acknowledgment on determining at least one of: an absence of the IE in at least one PDN connection; and a presence of the IE in the at least one PDN connection, wherein the IE is not discovered at a Network Repository Function (NRF); and the execution unit (220) configured to generate the positive context acknowledgment on determining the presence of the IE in the at least one PDN connection and a corresponding Session Management Function (SMF) discovered by the NRF using the IE.

15. The system (108) as claimed in claim 9, wherein the management of the at least one stale session comprises: upon receiving the negative context acknowledgment, the specific network node (304) is configured to transmit the at least one delete session request with an operation indicator (OI) towards a Serving Gateway (SGW) (402);the SGW (402) configured to forward the at least one delete session request to a Packet Data Network (PDN) gateway (PGW) (332) to delete the at least one stale session; upon deleting the at least one stale session, the PGW (332) is configured to transmit a delete session response to the SGW (402); and the SGW (402) configured to forward the delete session response to the specific network node (304).

16. The system (108) as claimed in claim 9, wherein the management of the at least one stale session comprises: on receiving the positive context acknowledgement, the specific network node (304) is configured to trigger removal of the at least one stale session by transmitting the at least one delete session request without the OI towards the SGW (402); and upon deleting the at least one stale session, the SGW (402) is configured to transmit the delete session response to the specific network node (304).

17. A user equipment (UE) communicatively coupled with a system (108), the UE (104) is configured to: transmit a registration request to the system (108), wherein the system (108) is configured to manage stale sessions in a network (106), as claimed in claim 9.

18. The UE as claimed in claim 17, wherein the registration request comprises a Globally Unique Temporary Identifier (GUTI).

19. A computer program product comprising a non-transitory computer- readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to execute a method (600) for managing stale sessions in a network (106), the method (600) comprising:receiving, by a network function (212), a registration request from a User Equipment (UE); generating, by the network function (212), a context request upon receiving the registration request; transmitting, by the network function (212), the generated context request to a specific network node (304); receiving, by the network function (212), a context response message from the specific network node (304) corresponding to the context request; determining, by the network function (212), a presence of an Information Element (IE) in the received context response message and generating a context acknowledgement based on the determination of the presence of the IE, wherein the context acknowledgment is a positive context acknowledgement or a negative context acknowledgment; transmitting, by the network function (212), the context acknowledgement to the specific network node (304); and managing, by the specific network node (304), at least one stale session by transmitting at least one delete session request towards at least one gateway on receiving the context acknowledgement from the network function (212).

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