Methods and apparatuses for network slice management in a wireless communication system

Abstract

A method and device for network slice management at a User Equipment (UE) or network entity, in a wireless communication system is disclosed. The method comprises generating a request to access one or more services associated with at least one network slice, determining whether the at least one network slice associated with the one or more services is available in current Public Land Mobile Network (PLMN) and associated Radio Access Technology (RAT) based on a selection assistance information, selecting at least one of current PLMN, a new PLMN, the current PLMN with a different RAT, current PLMN with the associated RAT and a different Cell, and transmitting, to a network entity, a Non-Access Stratum (NAS) signalling message to access one or more services.

Description

METHODS AND APPARATUSES FOR NETWORK SLICE MANAGEMENT IN A WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure generally relates to network slicing and handling partial allowed Network Slice Selection Assistance Information (NSSAI) in wireless communication networks, and more particularly to methods and apparatuses for network slice management in a wireless communication system.

[0002] Network slicing is a transformative concept in Fifth Generation (5G) wireless communication that enables the creation of multiple virtual networks, called slices, on top of a shared physical infrastructure. The multiple virtual networks may be tailored to specific service requirements such as enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), or massive IoT (mIoT) for mission-critical applications, or massive machine-type communication (mMTC) for deployments. Unlike previous generations of mobile networks that followed a one-size-fits-all approach, 5G slicing may allow operators to allocate dedicated resources, network functions, and performance parameters to each slice independently. The network slicing may ensure that diverse applications can operate simultaneously without interfering with one another. The network slicing may offer unprecedented flexibility, scalability, and efficiency by leveraging technologies like software-defined networking (SDN) and network function virtualisation (NFV), making the network slicing a cornerstone of the 5G architecture and a key enabler for future digital ecosystems.

[0003] The Network Slice Access Stratum Group (NSAG) may manage the radio access layer (RAN) to ensure slice-specific Quality-of-Service (QoS) and resource allocation, enabling differentiated connectivity for UEs based on their subscribed slices.

[0004] Network Slice Admission Control (NSAC) may regulate slice access by dynamically admitting or rejecting UEs based on available resources and policies, preventing congestion and guaranteeing SLA compliance for critical services (e.g., URLLC or eMBB).

[0005] The Network Slice Area of Service (NS-AOS) may define the geographical or logical boundaries where a slice is operational, supporting localised private networks or broad public deployments. Together, NSAG may optimise access performance, NSAC may enforce slice reliability, and NS-AOS may ensure precise service coverage, collectively enabling efficient, scalable, and SLA-driven 5G network slicing.

[0006] A User Equipment (UE) may encounter situations where the requested network slices may be congested. When none of the available network slices currently support a new session establishment, the UE remains camped on a current Public Land Mobile Network (PLMN) and a Radio Access Technology (RAT) without any active service. This situation is governed by the congestion control mechanism, including the back-off timer T3584, which, if not stopped or reset after one or more slices become available again, leads to unnecessary service denial. Although network slices identified by S-NSSAI provide flexibility to serve different user needs simultaneously, the UE may not be able to access or utilize all available slices at the same time due to subscription restrictions, slice-specific admission control, simultaneous registration constraints, resource contention, or deployment limitations.

[0007] As a result, the maximum possible slice and service availability for the UE 101 is constrained by operational, policy, and architectural factors, adversely impacting service continuity and accessibility, especially in scenarios requiring concurrent access to diverse services such as real-time control and high-bandwidth streaming.

[0008] This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure nor is it intended to determine the scope of the disclosure.

[0009] According to an implementation, a method for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The method includes generating a request to access one or more services associated with at least one network slice. The method includes determining whether the at least one network slice associated with the one or more services is available in a current Public Land Mobile Network (PLMN) and an associated Radio Access Technology (RAT), based on a predefined PLMN / RAT / TAC / CELL selection assistance information is maintained by the UE. The method includes selecting at least one of the current PLMN, a new PLMN, the current PLMN with a different RAT, the current PLMN with the same RAT and a different cell in response to determining. Furthermore, the method includes transmitting, to a network entity, a Non-Access Stratum (NAS) signalling message to access the one or more services.

[0010] According to another implementation, a method for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The method includes transmitting, to a network entity, a Non-Access Stratum (NAS) signalling message to access one or more services from at least one first network slice from a default or configured or allowed or partially allowed network slice list associated with a Public Land Mobile Network (PLMN), a Radio Access Technology (RAT), a Tracking Area Code (TAC), and a Cell. The method includes receiving, from the network entity, a NAS signalling reject message indicating a congestion at the at least one first network slice associated with the PLMN, the RAT, the TAC, and the Cell and initiating a congestion / back-off timer. Furthermore, the method includes updating a predefined PLMN / RAT / TAC / CELL selection assistance information table. The method further includes performing selection of the PLMN and the RAT combination based on the updated predefined PLMN / RAT / TAC / CELL / Tac / Cell selection assistance information table. The method further includes receiving, from the network entity, at least one of the NAS or an Access Stratum (AS) signalling message indicating a removal of the at least one network slice from at least one of a default, configured, allowed, or partially allowed network slice list associated with serving PLMN or Stand-alone Non-Public Network (SNPN) for which a first congestion timer is running. The method further includes stopping the first congestion timer associated with the at least one removed network slice in response to receiving the at least one of the NAS or the AS signalling message. The method further includes determining whether at least one second congestion timer is running for at least one PLMN or a corresponding SNPN. The method further includes stopping the at least one second congestion timer associated with the at least one PLMN or corresponding SNPN. The method further includes updating the predefined PLMN / RAT / TAC / CELL selection assistance information table based on the received at least one of NAS or AS signalling message.

[0011] According to an implementation, a method for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The method includes identifying a transition of the UE to a second Cell in the second Tracking Area (TA2), wherein the UE is initially registered for at least one network slice available in first Cell in a first TA (TA1). Further the method includes initiating at least one predefined timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA (TA2) in response to identifying the transition. The method includes triggering a Protocol Data Unit (PDU) session release request message, to de-register the at least one network slice based on an expiration of the initiated at least one predefined timer.

[0012] According to an implementation, a method for network slice management at a network entity in a wireless communication system. The method includes tracking a Tracking Area (TA) of a User Equipment (UE), wherein the UE is registered for at least one network slice available in a first Cell in a first TA (TA1) associated with the network entity. The method includes identifying a transition of the UE from the first TA (TA1) to a second cell in a second TA (TA2) based on the tracking. The method includes initiating at least one predefined timer, for tracking an inactivity usage corresponding to the at least one network slice not supported in the second TA (TA2). The method includes triggering a Protocol Data Unit (PDU) session release command message, to de-register the at least one network slice in response to detecting an expiration of the predefined timer.

[0013] According to an implementation, a device for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The device includes a memory and at least one processor, communicably coupled with the memory. The at least one processor may be configured to generate a request to access one or more services associated with at least one network slice. The at least one processor may be configured to determine whether the at least one network slice associated with the one or more services is available in a current Public Land Mobile Network (PLMN) and an associated Radio Access Technology (RAT) based on a predefined PLMN / RAT / TAC / CELL selection assistance information maintained by the UE. In response to determining, the at least one processor may be configured to select at least one of the current PLMN, a new PLMN, the current PLMN with a different RAT, the current PLMN with the same RAT and a different cell. The at least one processor may be configured to transmit, to a network entity, a Non-Access Stratum (NAS) signalling message to access the one or more services.

[0014] According to an implementation, a device for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The device includes a memory and at least one processor, communicably coupled with the memory. The at least one processor may be configured to transmit, to a network entity, a Non-Access Stratum (NAS) signalling message to access one or more services from at least one first network slice from a default or configured or allowed or partially allowed network slice list associated with a Public Land Mobile Network (PLMN), a Radio Access Technology (RAT), a Tracking Area Code (TAC), and a Cell. The at least one processor may be further configured to receive, from the network entity, a NAS signalling reject message indicating a congestion at the at least one first network slice associated with the PLMN, the RAT, the TAC, and the Cell and initiating a congestion / back-off timer. The at least one processor may be configured to update a predefined PLMN / RAT / TAC / CELL selection assistance information table. The at least one processor may be configured to perform selection of the PLMN and the RAT combination based on the updated predefined PLMN / RAT / TAC / CELL selection assistance information table. The at least one processor may be configured to receive, from the network entity, at least one of the NAS or an Access Stratum (AS) signalling message indicating a removal of the at least one network slice from at least one of a default, configured, allowed, or partially allowed network slice list for which a congestion timer is running. The at least one processor may be configured to stop the congestion timer associated with the at least one removed network slice in response to receiving the at least one of the NAS or the AS signalling message. The at least one processor may be configured to determine whether at least one second congestion timer is running for at least one PLMN or a corresponding SNPN. The at least one processor may be configured to stop the at least one second congestion timer associated with the at least one PLMN or corresponding SNPN. The at least one processor may be configured to update the predefined PLMN / RAT / TAC / CELL selection assistance information table based on the received at least one of NAS or AS signalling message.

[0015] According to an implementation, a device for network slice management at a User Equipment (UE) in a wireless communication system is disclosed. The device includes a memory and at least one processor, communicably coupled with the memory. The at least one processor may be configured to identify a transition of the UE to a second Cell in the second Tracking Area (TA2), wherein the UE is initially registered for at least one network slice available in first Cell in a first TA (TA1). The at least one processor may be configured to in response to identifying the transition, initiate at least one predefined timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA (TA2). The at least one processor may be configured to trigger a Protocol Data Unit (PDU) session release request message, to de-register the at least one network slice based on an expiration of the initiated at least one predefined timer.

[0016] According to an implementation, a device for network slice management at a network entity in a wireless communication system is disclosed. The device includes a memory and at least one processor, communicably coupled with the memory. The at least one processor may be configured to track a Tracking Area (TA) of a User Equipment (UE), wherein the UE is registered for at least one network slice available in a first Cell in a first TA (TA1) associated with the network entity. The at least one processor may be configured to identify a transition of the UE from the first TA (TA1) to a second cell in a second TA (TA2) based on the tracking. The at least one processor may be configured to initiate at least one predefined timer, to track an inactivity usage corresponding to the at least one network slice not supported in the second TA (TA2). The at least one processor may be configured to trigger a Protocol Data Unit (PDU) session release command message, to de-register the at least one network slice in response to detecting an expiration of the predefined timer.

[0017] To further clarify the advantages and features of the inventive concepts, a more particular description will be rendered by reference to specific examples thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical examples and are therefore not to be considered as limiting the scope of the inventive concepts. The inventive concepts will be described and explained with additional specificity and detail with the accompanying drawings.

[0018] These and other features, aspects, and advantages of the inventive concepts will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0019] Fig. 1A and Fig. 1B illustrate different environments depicting challenges during a network slice management at a User Equipment (UE), according to the related art;

[0020] Fig. 1C illustrates a sequence of operations depicting a challenge encountered during network slice management at a User Equipment (UE), as shown in Figs. 1A and 1B, according to the related art;

[0021] Fig. 2A and 2B illustrates a network slicing and mobility scenario across different Radio Access Technology (RATs), Long Term Evolution (LTE), and Wi-Fi, within multiple TAs and network slices, according to implementations of the present disclosure;

[0022] Fig. 2C (which includes Fig. 2C1 and Fig. 2C2) illustrates a sequence of operations depicting a method for network slice management (as explained in Fig. 2A also) for accessing one or more services, according to implementations of the present disclosure;

[0023] Fig. 3A illustrates another environment depicting challenges encountered during the network slice management at the UE, according to the related art;

[0024] Fig. 3B illustrates a sequence of operations depicting a challenge encountered during the network slice management at the UE, as shown in Fig. 3A, according to the related art;

[0025] Fig. 4A illustrates the network slice management by re-selecting the LTE to maintain the network connectivity, according to implementations of the present disclosure;

[0026] Fig. 4B illustrates a sequence of operations depicting a method for the network slice management for accessing one or more services (as explained in Fig. 4A), according to implementations of the present disclosure;

[0027] Fig. 5A illustrates another environment depicting challenges during the network slice management at the UE, according to the related art;

[0028] Fig. 5B illustrates a sequence of operations depicting a challenge encountered during the network slice management at the UE due to the congestion timer issue, as shown in Fig. 5A, according to the related art;

[0029] Fig. 5C illustrates a sequence of operations depicting another challenge encountered during the network slice management, as the UE may not support a Network Slice Area of Service (NS-AoS) feature, as shown in Fig. 5A, according to the related art.

[0030] Fig. 6A illustrates an environment depicting a solution to overcome the congestion timer issue as depicted in Figs. 5A-5B, according to implementations of the present disclosure;

[0031] Fig. 6B illustrates a sequence of operations depicting a method for the network slice management to overcome the congestion timer issue (as explained in Fig. 6A), according to implementations of the present disclosure;

[0032] Fig. 6C a sequence of operations depicting a method for network slice management as the UE may not support the NS-AoS feature, according to implementations of the present disclosure;

[0033] Fig. 7A illustrates another environment depicting challenges encountered during the network slice management during the UE mobility, according to the related art;

[0034] Fig. 7B illustrates a sequence of operations depicting a challenge of resource blocking associated with network slice management during the UE mobility, as shown in Fig. 7A, according to the related art;

[0035] Fig. 8A illustrates an environment depicting a solution to overcome the problem of resource blocking during the UE mobility as depicted in Fig. 7B, according to implementations of the present disclosure;

[0036] Fig. 8B illustrates a sequence of operations depicting a method for overcoming the challenge of resource blocking associated with network slice management at the UE (as explained in Fig. 8A), according to implementations of the present disclosure;

[0037] Fig. 8C illustrates a sequence of operations depicting another implementation of a method 800c for overcoming the challenge of resource blocking associated with network slice management at the UE (as explained in Fig. 8A), according to implementations of the present disclosure;

[0038] Fig. 9A illustrates an environment depicting challenges encountered during the network slice management when the UE get stuck in first Tracking Area (TA1), according to the related art;

[0039] Fig. 9B illustrates a sequence of operations depicting a challenge of resource blocking associated with network slice management during the UE mobility, as shown in Fig. 9A, according to the related art;

[0040] Fig. 10A illustrates an environment depicting a solution to overcome the challenges encountered during the network slice management when the UE gets stuck in the first Tracking Area (TA1) as depicted in Figs. 9A-9B, according to implementations of the present disclosure;

[0041] Fig. 10B(which includes Fig. 10B1 and Fig. 10B2) illustrates a sequence of operations depicting a method for overcoming the challenge (as explained in Fig. 10A) encountered during the network slice management when the UE get stuck in the first Tracking Area (TA1), according to implementations of the present disclosure;

[0042] Fig. 11A illustrates another environment depicting challenges encountered during the network slice management at the UE, according to the related art;

[0043] Fig. 11B illustrates a sequence of operations depicting a challenge encountered during network slice management at the UE due to a Network Slice Admission Group (NSAG) prioritisation constraints, as shown in Fig. 11A, according to the related art;

[0044] Fig. 12A illustrates an environment depicting a solution to overcome the slice accessibility issue as depicted in Figs. 11A-11B, according to implementations of the present disclosure;

[0045] Fig. 12B illustrates a sequence of operations depicting a method depicting the solution (as explained in Fig. 12A) to overcome the slice accessibility issue as depicted in Figs. 11A-11B, according to implementations of the present disclosure;

[0046] Fig. 13A illustrates an environment depicting challenges during the network slice management due to mobility registration, according to the related art;

[0047] Fig. 13B illustrates a sequence of operations depicting a challenge encountered during network slice management due to mobility registration, as shown in Fig. 13A, according to the related art;

[0048] Fig. 14A illustrates an environment depicting a solution to overcome the challenges during the network slice management due to mobility registration as depicted in Fig. 13A-13B, according to implementations of the present disclosure;

[0049] Fig. 14B illustrates a sequence of operations depicting a method depicting the solution (as explained in Fig. 14A) to overcome the challenges during the network slice management due to mobility registration, as depicted in Fig. 13A-13B, according to implementations of the present disclosure;

[0050] Fig. 15A illustrates an environment depicting challenges during the network slice management when the partially allowed NSSAI is not considered, according to the related art;

[0051] Fig. 15B illustrates a sequence of operations depicting a challenge of resource blocking associated with network slice management when the partially allowed NSSAI is not considered, as shown in Fig. 15A, according to the related art;

[0052] Fig. 16A illustrates an environment depicting a solution to overcome the challenges during the network slice management when the partially allowed NSSAI is not considered, as shown in Figs. 15A-15B, according to implementations of the present disclosure;

[0053] Fig. 16B illustrate sequence of operations depicting a method 1600b depicting the solution (as explained in Fig. 16A) to overcome the challenges during the network slice management when the partially allowed NSSAI is not considered, as shown in Figs. 15A-15B, according to implementations of the present disclosure;

[0054] Fig. 17 illustrates an example process flow depicting a method for network slice management at the UE, in the wireless communication system, according to implementations of the present disclosure;

[0055] Fig. 18 illustrates another example process flow depicting a method for network slice management at the UE, in the wireless communication system, according to implementations of the present disclosure;

[0056] Fig. 19 illustrates another example process flow depicting a method for network slice management at the UE, in the wireless communication system, according to implementations of the present disclosure;

[0057] Fig. 20 illustrates another example process flow depicting a method for network slice management at the network entity, in the wireless communication system, according to implementations of the present disclosure;

[0058] Fig. 21 illustrates an example diagram of a device implemented in the UE, according to implementations of the present disclosure; and

[0059] Fig. 22 illustrates an example diagram of a device implemented in a network entity, according to implementations of the present disclosure.

[0060] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not necessarily have been drawn to scale. The flow charts illustrate the method in terms of operations involved to help improve understanding of aspects of the inventive concepts. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding implementations of the inventive concepts so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0061] It should be understood at the outset that although illustrative implementations of implementations of the present disclosure are illustrated below, the inventive concepts may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the example design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0062] The term "some" as used herein is defined as "one, or more than one, or all." Accordingly, the terms "one," "more than one," "more than one, but not all" or "all" would all fall under the definition of "some." The term "implementations" may refer to one implementation or to several implementations or to all implementations.

[0063] The terminology and structure employed herein is for describing, teaching, and illuminating implementations and their specific features and elements and does not limit, restrict, or reduce the spirit and scope of the claims or their equivalents.

[0064] More specifically, any terms used herein such as but not limited to "includes," "comprises," "has," "consists," and grammatical variants thereof do NOT specify an exact limitation or restriction and certainly do NOT exclude the possible addition of one or more features or elements, unless otherwise stated, and furthermore must NOT be taken to exclude the possible removal of one or more of the listed features and elements, unless otherwise stated with the limiting language "MUST comprise" or "NEEDS TO include."

[0065] Whether or not a certain feature or element was limited to being used only once, either way, it may still be referred to as "one or more features" or "one or more elements" or "at least one feature" or "at least one element."

[0066] Unless otherwise defined, all terms, and especially any technical and / or scientific terms, used herein may be taken to have the same meaning as, or a similar meaning to, that commonly understood by one having ordinary skill in the art.

[0067] Implementations of the inventive concepts will be described below in detail with reference to the accompanying drawings.

[0068] Fig. 1A and Fig. 1B illustrate environments depicting challenges during a network slice management at an User Equipment (UE), according to the related art.

[0069] Fig. 1C illustrates a sequence of operations 100c depicting a challenge network slice management at the UE as shown in Figs. 1A and 1B, according to the related art.

[0070] In a general scenario of a Fifth Generation (5G) network-based wireless communication system, as referred to in Fig. 1A, the UE 101, operating in a first Cell (interchangeably referred to herein and after as Cell 1) may initiate a connection request to access one or more services. Initially, the UE 101 may connect to an evolved Node B (eNB) 105. In an implementation, the UE 101 may support dual connectivity, that is, the UE 101 may simultaneously connect to a 5G base station, such as gNB1 operating in a Tracking Area (TA), such as Tracking Area 1 (TA1) 103. The UE 101 may request access to specific network slices by sending a registration request containing multiple Single Network Slice Selection Assistance Information (S-NSSAI) values, such as, but not limited to, S-NSSAI-1 (denoted in Fig. 1A as NS-1) and S-NSSAI-2 (denoted in Fig. 1A as NS-2). Each S-NSSAI corresponds to a specific type of service, such as enhanced mobile broadband or ultra-reliable low latency communication. A registration message may be forwarded by the gNB1 103 to a 5G Core Network (5G network) 107, specifically to the Access and Mobility Management Function (AMF / SMF). The AMF / SMF may handle the various operations, including registration, authenticating the UE, checking the availability and authorising the requested slices. The AMF / SMF may consult a Network Slice Selection Function (NSSF) to determine which slices are allowed based on the UE's 101 subscription and location. Once the UE is registered and the network slices are authorised, the UE may initiate a Packet Data Unit (PDU) Session Establishment Request for services mapped to the S-NSSAI-1 or the S-NSSAI-2, with the AMF / SMF managing mobility and session signalling across the 5G network.

[0071] The PDU Session Establishment Request is a message sent by the UE 101 to initiate a data session with a Data Network (DN) in the 5G network. The PDU Session Establishment Request is used for enabling data communication between the UE 101 and the network entity 111. The UE 101 may transmit the PDU Session Establishment Request to the AMF, which then interacts with other network functions. Furthermore, if the UE 101 is authorised for both the slices, that is, the S-NSSAI-1 and the S-NSSAI-2 in the TA1, the AMF may allow access, and the session establishment may proceed via appropriate network functions, enabling the UE 101 to use 5G services tailored to each network slice.

[0072] Referring to Fig. 1A, an environment 100a may include the UE 101 may encounter situations where the requested network slices may be congested. For instance, the UE 101 may encounter such situations when none of the available network slices currently support a new session establishment. In such cases, the UE 101 may remain camped on a current Public Land Mobile Network (PLMN) and a Radio Access Technology (RAT), such as 5G New Radio (NR) or LTE, without any active service. The UE 101 may remain camped on the current PLMN and the RAT, since the UE 101 may not access any slice, that is, the S-NSSAI-1 or the S-NSSAI-2, to initiate the PDU session. Such behaviour of the UE 101 may be governed by a congestion control mechanism, including a back-off timer T3584. The back-off timer T3584 is generally designed to prevent the UE 101 from repeatedly attempting to access congested slices. However, a critical issue arises when the back-off timer T3584 is not stopped or reset even after one or more slices previously removed and become available again.

[0073] Referring to Fig. 1B, an environment 100a of the wireless communication system is depicted, in which the network slices are generally identified by the S-NSSAI to serve different user needs simultaneously. However, despite the flexibility of serving the different user needs simultaneously, the UE 101 may not always be able to access or utilise all available network slices or services at the same time, even if the network slices or services are technically supported by the 5G network. Such limitations may arise due to several factors, such as but not limited to subscription restrictions, slice-specific admission control, simultaneous registration constraints, resource contention, or deployment limitations. As a result, even though the 5G network supports multi-network slice connectivity, the maximum possible slice / service availability for the UE 101 may often be constrained by operational, policy, and architectural factors. Such constraints may impact service continuity / accessibility, especially in scenarios requiring concurrent access to diverse services like real-time control and high-bandwidth streaming.

[0074] Referring to Fig. 1C, the sequence of operation 100c corresponds to a communication between the UE 101 and a network entity 111 (e.g., a 5G network Access and Mobility Management Function). The network 111 may implement a Public Land Mobile Network (PLMN) (for example, PLMN 1) within a specific geographic area. In a non-limiting example, the network 111 may include gNodeB (gNB1) 103 supporting NSSAI-1 and NSSAI-2, eNodeB (eNB) 105 in TA1, 5G network 107, and the MME 109. The gNB1 103 may correspond to a radio access node (RAN) for the 5G NR, and the eNB 105 may be the RAN in the 4G LTE networks. At operation 102, the UE 101 may be configured with multiple S-NSSAI entries, such as S-NSSAI-1 and S-NSSAI-2, along with a default slice S-NSSAI-3. The multiple S-NSSAI entries represent different service types or applications, and their availability depends on the TA in which the UE 101 is currently camped. At operation 104, the UE may attempt to establish the PDU session using the S-NSSAI-1 and a Data Network Name (DNN1). The DNN may be used to identify an external data network. In an implementation, the UE 101 may transmit a PDU Establishment Request message corresponding to the S-NSSAI-1 and DNN1 to the gNB1. At operation 106, the PDU Establishment Request message corresponding to S-NSSAI-1 and DNN1 may be forwarded from the gNB1 103 to the 5G network 107. At operation 108, the 5G network 107 may identify that the network service across the S-NSSAI-1 and the DNN1 may be congested. In a non-limiting example, the PDU Establishment Request message may be rejected with 5GSM due to insufficient resources for specific slice DNN1, indicating the slice congestion. Therefore, at operation 110, a PDU Establishment Reject message corresponding to S-NSSAI-1 may be transmitted to the UE 101 with a back-off timer, which is interchangeably referred to herein and after as "predefined timer", for example, of 2 minutes. As a result, at operation 112, the predefined timer may be initiated by the UE 101 corresponding to the S-NSSAI-1, to prevent immediate retry. In a non-limiting example, the predefined timer may be for a duration from 10 seconds to 3 hours. The same rejection and a back-off timer activation may occur for the S-NSSAI-2. Similar operations, i.e., operation 104 - operation 112 corresponding to S-NSSAI-1 and DNN1, may be performed at operation 114 - operation 122 corresponding to S-NSSAI-2 and DNN2, respectively. For the sake of brevity, operation 114 - operation 122 are not reproduced here again. At operation 124, the 5G network 107 may identify that the network service across the S-NSSAI-1 and the S-NSSAI-2 is congested. The 5G network 107 may prevent UE 101 from connecting to the S-NSSAI-1 and the S-NSSAI-2 due to congestion control. Thus, the network entity 111 may decide to remove the S-NSSAI-2 from a list of configured N-SSAI. At operation 126, when the congestion subsides, and the subscription is held, the 5G network 107 may send a Configuration update command for restoring S-NSSAI-1 to the allowed and configured NSSAI list. At operation 128, upon receiving the updated configuration from operation 126, the UE 101 may not have stopped the predefined timer that was initiated at operation 122. Hence, the UE 101 may continue to treat the S-NSSAI-1 as unavailable and may refrain from initiating new sessions, even though the S-NSSAI-1 may be accessible. At operation 130, the UE 101 may remain in NR for 10 minutes without service. The same rejection for initiating new sessions may occur for the S-NSSAI-2. At operation 132, the 5G network 107 may send the Configuration update command to the UE 101 to indicate that the S-NSSAI-1 and S-NSSAI-2 are allowed and configured. At operation 134, the S-NSSAI-2 may be available again. At operation 136, since the UE 101 may not have stopped the congestion timer, the UE 101 may not be able to trigger the PDU for S-NSSAI-2. Thus, the present scenario highlights a broader issue in 5G congestion control, that is, failure to stop or reset the back-off timer T3584 that may lead to unnecessary service denial, even after network conditions improve.

[0075] Further to overcome the above problem, as depicted in Figs. 1A-1C, the solution is provided in the forthcoming paragraph while explaining Figs. 2A-2C.

[0076] Fig. 2A and 2B illustrate a network slicing and mobility scenario across the different RATs, the LTE and the Wi-Fi, within the multiple TAs and network slices, according to implementations of the present disclosure.

[0077] Fig. 2A and Fig. 2B may depict the significance of stopping the back-off timer once a network slice subscription is updated to maintain the network connectivity. In particular, Fig. 2A and Fig. 2B may overcome the problem associated with the back-off time that is explained in Fig. 1A, Fig. 1B, and Fig. 1C. Figs. 2A and 2B relate to the handling of the network slice-specific registration and back-off timer behaviour during the mobility events across the various RATs and Registration Areas (RAs).

[0078] As referred to in Fig. 2A, an inter-Cell and inter-RAT mobility scenario is depicted while maintaining the network slice continuity. As shown in Fig. 2A, the UE 101 may be moving across different 5G NR and LTE cells, for example, starting from the NR TA1 in the first Cell supporting NSSAI-1 and NSSAI-2. The UE 101 may move to the NR TA2 further in a second Cell supporting the same network slices, that is, NSSAI-1 and NSSAI-2. Finally, the UE 101 may move to LTE-TA5 in a third Cell. The RAs corresponding to the NR may be TA1, TA2, and the LTE may be TA5.

[0079] As referred to in Fig. 2B, a multi-network slice and multi-access technology management is demonstrated where UEs 101 may switch between Wi-Fi and cellular networks while preserving the network slice information.

[0080] In an implementation, as referred to in Fig. 2A and Fig. 2B, the network entity 111 may manage the back-off timer during the mobility events involving the multiple access technologies, such as, but not limited to, the 5G NR, the LTE, the Wi-Fi, and the network slicing. As the UE moves across the different Cells and technologies, for example, from NR TA1 to TA2, then to LTE TA5, or from the Wi-Fi to the NR in a fifth Cell, the UE 101 may transition between the different RAs and TAs. In general, if the network slice is not available in the current Cell or RA, the UE 101 may enter the back-off timer to temporarily avoid further attempts. However, in the present scenario, the network entity may dynamically update the slice subscription when the UE 101 moves into a new area that supports the required one or more network slicess. When the updated Cell or RA provides the appropriate network slice, for example, NSSAI-1, NSSAI-2, or NSSAI-3, the back-off timer may stop. As soon as the back-off timer stops, the UE 101 may immediately attempt to access the network again to access one or more services, to avoid unnecessary delays.

[0081] Fig. 2C (which includes Fig. 2C1 and Fig. 2C2) illustrates a sequence of operations depicting a method 200c for network slice management (as explained in Fig. 2A also) for accessing one or more services, according to implementations of the present disclosure. In an implementation, the method 200c may provide a solution to one or more challenges illustrated in Figs. 1A-1C.

[0082] Operations 202-224 relate to the failure of the PDU establishment procedure, as explained in reference to operations 102-114 (shown in Fig. 1), respectively. Accordingly, a detailed description of the operations 202-224 has been omitted for the sake of brevity. At operation 226, the 5G network 107 may transmit a Configuration update command to the UE 101 in response to the removal of S-NSSAI-1 and S-NSSAI-2 from the configured NSSAI list. At operation 228, the UE 101 may stop the back-off timers that were initiated in operation 212 and 222, corresponding to S-NSSAI-1 and S-NSSAI-2. At operation 230 and operation 232, the back-off timers initiated in operation 212 and 222, corresponding to S-NSSAI-1 and S-NSSAI-2, respectively, may be stopped. The back-off timer may be stopped when the network slice subscription is updated. At operation 234, the UE 101 may perform the RAT / PLMN selection and transit to the LTE to access one or more services associated with the S-NSSAI-1 and DNN-1 using an Access Point Name (APN1) in the LTE.

[0083] Therefore, at operation 236, the UE 101 may transmit an Attach request message to the eNB 105. At operation 238, the ATTACH request message may be forwarded to the MME 109 by the eNB 105. The ATTACH request message may be related to the PDN connectivity. At operation 240, the UE 101 may receive an ATTACH Accept message from the MME 109 to begin a default bearer setup process. At operation 242, the UE 101 may receive an Activate default EPS bearer request message from the MME 109. At operation 244, the UE 101 may transmit an Activate default EPS bearer Accept message to the MME 109. During operation 244, none of the mapped network slices for the NR may be available. The unavailability of the network slices may be due to congestion. At operation 246, the MME 109 may provide the mapped NSSAI in an extended Protocol Configuration Options (EPCO) when the at least one network slice becomes available. At operation 248, the UE 101 may receive an EPS bearer Modification request from the MME 109 to store the configured NSSAI. At operation 250, the UE 101 may transmit an EPS bearer modification Accept message to the MME 109. At operation 252, the UE 101 may add the at least one network slice, such as S-NSSAI-1, to the configured NSSAI list. At operation 254, the UE 101 may reselect the NR if a Home (HO) network slice becomes available. In an implementation, the UE 101 may reselect to the NR to acquire a higher data rate. At operation 256, the UE 101 may transmit the PDU Establishment Request message to the gNB1 in the first TA (TA1), which may be associated with the Home (HO) network slice, such as but not limited to S-NSSAI-1 and DNN1. At operation 258, the gNB1 may transmit the PDU Establishment Request message corresponding to the S-NSSAI-1 and DNN1 to the 5G network 107. At operation 260, the 5G network 107 may transmit a PDU Establishment Accept message to the UE 101 in response to the PDU Establishment Request message received from the UE 101. Thus, in an advantageous aspect, the present solution may ensure resilience and backwards compatibility in multi-generation mobile networks, allowing UE 101 to stay connected even when advanced 5G slice resources are temporarily unavailable.

[0084] Fig. 3A illustrates another environment 300a depicting challenges during the network slice management at the UE 101, according to the related art.

[0085] Fig. 3B illustrates a sequence of operations 300b depicting a challenge network slice management at the UE as shown in Fig. 3A, according to the related art.

[0086] Referring to Fig. 3A, an environment 300a may include the UE 101 may encounter situations where the requested network slices may be congested. For instance, the UE 101 may initially be located in NR TA1 associated with the first Cell supporting the plurality of network slices, including the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3. Adjacent to the NR TA1, there may be NR TA2 associated with the second Cell (Cell 2) supporting only the S-NSSAI-1 and the S-NSSAI-2, indicating limited network slice availability. Adjacent to the NR TA1 and the NR TA2, there may be LTE TA5 associated with the third Cell (Cell 3), representing a legacy LTE coverage. However, a re-selection to the LTE may not be possible, which may be a limitation. The UE 101 may be unable to reselect the LTE if the required network slice is unavailable in the NR cell. Such a scenario may result in reduced service continuity / accessibility and user experience.

[0087] In an implementation, as referred to in Fig. 3B, at operation 302, the UE 101 may be configured with the plurality of network slices, that is, the S-NSSAI-1 and the S-NSSAI-2, and the default slice, i.e., the S-NSSAI-3. The plurality of network slices may represent distinct service types or applications, and the availability of the plurality of network slices may depend on the UE's 101 location within the specific TAs. In the present environment 300a, the UE 101 may be camped in TA1, which may support the plurality of network slices. In an implementation, the UE 101 may include the S-NSSAI-1 and the S-NSSAI-2 from the configured NSSAI list, upon initiating a registration request over the 3GPP access. At operation 304, the UE 101 may transmit an RRCConnectionSetupComplete Registration to the gNB1 103, which may correspond to TA1, and the S-NSSAI-1 and the S-NSSAI-2. At operation 306, the gNB1 may forward the RRCConnectionSetupComplete Registration to the 5G network 107. The RRCConnectionSetupComplete message may be used in the access and registration procedure between the User Equipment (UE) and the network entity 111. At operation 308, upon receiving the request, the 5G network 107 may acknowledge the request by transmitting a Registration Accept message to the UE 101 to include the S-NSSAI-1 and the S-NSSAI-2 from the configured NSSAI list. At operation 310, the UE 101 may trigger the PDU Establishment Request message for at least one network slice, for example, the S-NSSAI-1. At operation 312, the UE 101 may transmit the PDU Establishment Request message to the gNB1 103. At operation 314, the PDU Establishment Request message from the gNB1 103 to the 5G network 107. At operation 316, the 5G network 107 may identify that the S-NSSAI-1 is congested. Therefore, at operation 318, the 5G network 107 may transmit the PDU Establishment Reject message to the UE 101. The backoff timer of 10 minutes may be initiated when the PDU Establishment Reject message is transmitted to the UE 101. At operation 320, the congestion timer may be initiated at the UE 101 due to insufficient resources for the requested slice S-NSSAI-1. In a non-limiting example, the congestion timer may be 10 minutes. Therefore, at operation 322, the UE 101 may trigger the PDU session for another network slice, that is, the S-NSSAI-2, as the S-NSSAI-1 is congested.

[0088] Similar operations, i.e., operation 312 - operation 320 corresponding to N-SSAI-1 and DNN1, may be performed at operation 324 - operation 332 corresponding to N-SSAI-2 and DNN2, respectively. For the sake of brevity, the operation 324 - operation 332 are not reproduced here again.

[0089] At operation 334, the UE may block both the S-NSSAI-2 and the S-NSSAI-1 due to the congestion timer and no alternative network slice may be available for providing the one or more network services. At operation 336, when both network slices, that is, the S-NSSAI-2 and the S-NSSAI-1, are congested, the UE 101 may remain camped in the NR but is unable to access any service for the duration of the congestion. The duration of the congestion may be 10 minutes. During the congestion, the UE 101 may be effectively idle, despite being connected to the network. In a non-limiting example, the congestion timer, which may range from 10 seconds to approximately 3 hours, may govern how long the UE 101 must wait before retrying a session establishment for the congested network slices. Such a situation may result in prolonged service denial in congested conditions.

[0090] Further to overcome the above problem as depicted in Figs. 3A-3B, the solution is provided in the forthcoming paragraph while explaining Figs. 4A and 4B.

[0091] Fig. 4A illustrates a network slice management by re-selecting the LTE to maintain the network connectivity, according to implementations of the present disclosure.

[0092] Fig. 4A may overcome the problem associated with the blocking of both the S-NSSAI-2 and the S-NSSAI-1 due to the activation of the congestion timer that is explained earlier in Fig. 3A and 3B. Fig. 4A depicts the significance of re-selecting the LTE to maintain the network connectivity. The UE 101 may successfully complete the RRC connection setup process and may further request a TA Update (TAU) to register with the network entity 111. As referred to in Fig. 4B, a potential handover or a fallback scenario is depicted, where the UE 101 may move from the 5G NR coverage to the LTE. In the present scenario, the network slice-based mobility management is performed where the UE 101 may select or re-select cells based on the availability of the required network slices for one or more services.

[0093] Fig. 4B illustrates a sequence of operations depicting a method 400b for the network slice management for accessing one or more services (as explained in Fig. 4A), according to implementations of the present disclosure. In an implementation, the method 400b may provide a solution to one or more challenges illustrated in Figs. 3A-3B.

[0094] Operations 402-435 relate to the blocking of both the network slices, that is, the S-NSSAI-1 and the S-NSSAI-2, as explained in reference to operations 302-335 (shown in FIG. 3B), respectively. Accordingly, a detailed description of the operations 402-435 has been omitted for the sake of brevity. At operation 436, the UE 101 may perform the RAT / PLMN selection and transit to the LTE to access one or more services associated with the S-NSSAI-1 and DNN-1 using an Access Point Name (APN1) in the LTE. Thus, when the UE 101 is unable to access a desired service, such as one associated with S-NSSAI-1 and DNN-1, due to slice unavailability, congestion, or access restrictions, the UE 101 may initiate the RAT and the PLMN selection procedures to find an alternative path. Such a transition may allow the UE 101 to maintain service continuity / accessibility. The UE 101 may perform the transition autonomously or based on network guidance, scanning available PLMNs and RATs to identify one that supports the required configuration associated with the APN1. Once connected to LTE, the UE 101 may establish a PDN connection using the APN1, effectively accessing the same service through legacy infrastructure. In a non-limiting example, when the service continuity / accessibility is impacted, the UE 101 may initiate the transition to the LTE or an alternative partner PLMN, including a slice availability in non-Third Generation Partnership Project (non-3GPP) access options, guided by a PLMN / RAT / TAC / CELL Selection Assistance Information. The selection process may be influenced by a range of dynamic parameters that may help determine the most suitable PLMN, RAT, TA, or Cell. The dynamic parameters may include, but are not limited to, received signal strength, available Physical Resource Blocks (PRBs) indicating cell load, and Channel State Information (CSI) reports. The UE 101 may intelligently prioritise and select the optimal access network to maintain service availability and performance by evaluating dynamic parameters. An example of the PLMN / RAT / TAC / CELL Selection Assistance Information is depicted in Table 1 given below:

[0095] PLMNRATTACCellSliceSubscriptionLTE sliceslice AvailableCongestionPriority　mappingover Non-3GPPPLMN-1NRTA1C1eMBB,YesNANAeMBB &1(Home)URLLCNoURLLC　TA2C2eMBB,YesNANAcongested2　URLLCNo　PLMN-2NRTA3C4eMBB,YesNAeMBBNo3(Partner)URLLCYescongestion　TA4C5URLLC,YesNAeMBB　4　MIOTYes　PLMN-1LTETA5C3NAYesDedicated APN:eMBB (Internet / IMS)NANo5(Home)congestion

[0096] At operation 438, the UE 101 may transmit an RRCConnectionSetupComplete and Tracking Area Update (TAU REQUEST) to the eNB 105. The RRCConnectionSetupComplete and TAU REQUEST may be used to allow the network entity 111 to identify the UE's 101 new location and validate a mobility status. Subsequently, at operation 440, the RRCConnectionSetupComplete and TAU REQUEST may be forwarded to the MME 109. In an implementation, coordination between the LTE and the NR elements may be performed to complete the mobility procedure. At operation 442, the MME 109 may transmit the TAU Accept message to the UE 101, confirming that the UE 101 is successfully accepted in the LTE. Finally, the UE 101 may also receive the Activate default EPS bearer request from the MME 109, allowing the UE 101 to establish the data connectivity over the LTE. Thus, the present solution may provide an enhanced mobility handling mechanism that may enable the fallback to the LTE when the preferred NR slice is unavailable.

[0097] Further, the above method 400b may be applicable for any NAS or AS signalling, which may lead to non-availability of the network slice or services.

[0098] Fig. 5A illustrates another environment 500a depicting challenges during the network slice management at the UE 101, according to the related art.

[0099] As referred to in Fig. 5A, an environment 500a may include the UE 101 may encounter situations where the requested network slices may be congested. In an implementation, since the UE may not support a NS-AoS) feature, due to which the UE 101 may face service continuity / accessibility challenges during mobility events. For instance, the UE 101 may be located in TA1 associated with the first Cell (Cell 1), supporting the S-NSSAI-1 and S-NSSAI-2. The UE 101 may successfully register both the S-NSSAI-1 and S-NSSAI-2. As shown in Fig. 5A, the base station may transmit a UE configuration Update (UCU) message to the UE 101, configuring and adding the S-NSSAI-1 in the allowed network slice list. In an implementation, the UE 101 may transit into a geographic area where Slice 2 may not be supported due to the NS-AoS criteria. For instance, due to the network slice-specific service restrictions or deployment limitations, the network entity 111 may respond by transmitting the UCU message that marks Slice 2 as partially allowed and retains the S-NSSAI-1 as fully allowed. During that time instance, if the PDU congestion control is applied to the S-NSSAI-2, the network entity 111 may start the back-off timer, preventing the UE 101 from retrying the PDU session establishment for that network slice (S-NSSAI-2). Further, another UCU message may be transmitted to expand the network slice configuration, allowing access to both the S-NSSAI-1 and the S-NSSAI-2, reflecting a dynamic update based on network conditions. In an implementation, when the UE 101 transitions back into an area where the S-NSSAI-2 may again be supported under the NS-AoS, the network entity 111 may transmit another UCU message restoring both the network slices as configured and allowed. However, because the UE 101 may not support the NS-AoS and fails to stop the back-off timer. The UE 101 may continue to treat the S-NSSAI-2 as unavailable, even though the network entity 111 may have cleared the congestion condition and reauthorised access. Further, the UE 101 may try to initiate the PDU session Establishment request associated with the S-NSSAI-2, which may be currently permitted as the newly allowed network slice. As a result, the UE 101 may be unable to initiate the PDU session for the S-NSSAI-2, leading to unnecessary service denial. Such an issue of the 5G congestion and mobility management may arise since the back-off timer was not properly synchronised with network updates, especially when the network slice availability changes due to mobility or policy shifts. Thus, the UE 101 may remain blocked from accessing services that are technically available due to a lack of coordination, impacting user experience and network efficiency. Such a problem is not limited to the back-off timer but also applies to all congestion-related back-off timers, underscoring the need for smarter UE 101 behaviour and more responsive network signalling.

[0100] Fig. 5B illustrates a sequence of operations 500b depicting a challenge encountered during the network slice management at the UE due to the congestion timer issue, as shown in Fig. 5A, according to the related art.

[0101] In an implementation, as referred to in Fig. 5B, at operation 502, the UE 101 may be configured with the plurality of network slices, that is, the S-NSSAI-1 and the S-NSSAI-2.

[0102] Operations 504-518 relate to the process of the PDU Establishment Reject message for one of the network slices, that is, the S-NSSAI-2 and the DNN1, as explained in reference to operations 304-318, respectively, (shown in FIG. 3b, where the process of the PDU Establishment Reject message for S-NSSAI-1 was explained). Accordingly, a detailed description of the operations 504-518 has been omitted for the sake of brevity. At operation 520, the UE 101 may trigger the congestion timer for S-NSSAI-2. At operation 522, the congestion timer may initiate. At operation 524, due to the congestion, the 5G network 107 may decide to avoid the UE 101 from connecting for S-NSSAI-2 due to congestion control. Hence, the 5G network 107 may decide to remove the S-NSSAI-2 from the configured NSSAI list. Thus, at operation 526, the 5G network 107 may transmit the Configuration update command to the UE 101 for only the S-NSSAI-1 to be allowed. At operation 528, the 5G network 107 may initiate to temporarily remove the congestion control for the S-NSSAI-2. The 5G network 107 may include the S-NSSAI-2 back in the configured NSSAI list along with the S-NSSAI-1. At operation 530, the 5G network 107 may transmit the Configuration update command to the UE 101 for the S-NSSAI-1 and the S-NSSAI-2 to be allowed. At operation 532, the S-NSSAI-2 may be available again for use by the UE 101. However, at operation 534, the UE 101 may not be able to trigger the PDU session corresponding to the S-NSSAI-2, as the congestion timer initiated in operation 522 may not have stopped. Hence, later, even when the congestion may be cleared and the S-NSSAI-2 becomes available, the UE 101 may not use the S-NSSAI-2 because the congestion timer is still active. As a result, the UE 101 may be unable to access services for the S-NSSAI-2 despite being available again. Such an issue may not be limited to the T3584, but may also be applied to all the congestion timers and back-off timers if not properly managed or reset.

[0103] Fig. 5C illustrates a sequence of operations 500c depicting another challenge encountered during the network slice management, as the UE 101 may not support the NS-AoS feature, as shown in Fig. 5A, according to the related art.

[0104] At operation 550, the UE 101 may be configured with the plurality of network slices, that is, the S-NSSAI-1 and the S-NSSAI-2. At operation 552, the UE 101 may transmit the RRCConnectionSetupComplete request to the gNB1 103 to register the plurality of network slices for accessing one or more services. In response, at operation 554, the gNB1 103 may forward the request to the 5G network 107. At operation 556, upon receiving the request from the gNB1 103, the 5G network 107 may transmit the Registration Accept message to the UE 101, allowing the plurality of network slices, that is, the S-NSSAI-1 and the S-NSSAI-2, to be accessed for providing one or more services. At operation 558, the UE 101 may transit and get connected to other TA, for example, the second TA (TA2). At operation 560, the UE 101 may trigger the PDU session corresponding to the S-NSSAI-2. At operation 562, the UE 101 may transmit the PDU Establishment Request message to the gNB1 103. At operation 564, the gNB1 103 may forward the PDU Establishment Request message to the 5G network 107. At operation 566, upon receiving the PDU Establishment Request message from the gNB1 103, the 5G network 107 may identify that the UE 101 may not be supporting NS-AoS and may have moved out of the NS-AoS area. Hence, at operation 568, the 5G network 107 may transmit the PDU Establishment Reject message to the UE 101 to inform about the unavailability of the S-NSSAI-2 for providing one or more services to the UE 101. As a result, the back-off timer of around 20 minutes may be initiated. In a non-limiting example, the congestion timer may range from 10 seconds to approximately 3 hours. At operation 570, the UE 101 may initiate the back-off timer corresponding to the S-NSSAI-2. At operation 572, the back-off timer may be triggered at the UE 101. At operation 574, the 5G network 107 may decide to remove the S-NSSAI-2 from the configured NSSAI list. Thus, at operation 574, the 5G network 107 may transmit the Configuration update command to the UE 101 for only the S-NSSAI-1 to be allowed. At operation 576, the UE 101 may transit back to the first TA (TA1). Thus, at operation 578, the 5G network 107 may further transmit the Configuration update command to notify the UE 101 that the configured and allowed network slices, e.g., the S-NSSAI-1 and the S-NSSAI-2, are now available. Hence, at operation 580, the UE 101 may identify that the S-NSSAI-2 is available again to avail the one or more services. However, at operation 582, the UE may not be able to trigger the PDU session corresponding to the S-NSSAI-2, as the back-off timer that was initiated earlier is not stopped. Such a scenario may lead to a blockage in availing of the one or more services corresponding to the S-NSSAI-2, even when the S-NSSAI-2 becomes available.

[0105] Further to overcome the above problem, as depicted in Figs. 5A-5C, the solution is provided in the forthcoming paragraph while explaining Figs. 6A-6C.

[0106] Fig. 6A illustrates an environment 600a depicting a solution to overcome the congestion timer issue as depicted in Figs. 5A-5B, according to implementations of the present disclosure.

[0107] As referred to in Fig. 6A, the UE 101 may overcome the congestion timer issue (as explained earlier in Figs. 5A-5B) by intentionally stopping the congestion timer associated with S-NSSAI-2. Later, when the S-NSSAI-2 becomes available again, the UE 101 may be able to activate the PDU session for the S-NSSAI-2 without waiting for the congestion timer to expire, ensuring faster service recovery.

[0108] Fig. 6B illustrates a sequence of operations depicting a method 600b for the network slice management to overcome the congestion timer issue (as explained in Fig. 6A), according to implementations of the present disclosure.

[0109] Fig. 6B may overcome the challenge in network slice management at the UE 101 due to the congestion timer issue associated with at least one of the network slices, for instance, the S-NSSAI-2, which is explained earlier in Fig. 5A and 5B.

[0110] Fig. 6C is a sequence of operations depicting a method 600c for network slice management, as the UE 101 may not support the NS-AoS feature (as explained in Fig. 6A), according to implementations of the present disclosure.

[0111] Operations 602-625 of Fig. 6B relate to the availability of the S-NSSAI-2 again for usage by the UE 101, after the congestion, as explained in reference to operations 502-525 (shown in Fig. 5B), respectively. Accordingly, a detailed description of the operations 602-625 has been omitted for the sake of brevity. At operation 626, when the UE receives a CONFIGURATION UPDATE COMMAND message or REGISTRATION ACCEPT message and an S-NSSAI is removed from the allowed NSSAI, the partially allowed NSSAI or the configured NSSAI, the UE shall stop the timers T3584 and T3585 associated with the S-NSSAI and serving PLMN or SNPN, if running. If the timers were running for multiple other PLMNs or equivalent SNPNs, the UE shall stop the timers for all such PLMNs or equivalent SNPNs.At operation 628, the UE 101 may initiate stopping the congestion timer associated with the S-NSSAI-2 that was initiated earlier at operation 622 when the 5G network 107 found the S-NSSAI-2 being congested, and as the S-NSSAI-2 is removed from the allowed NSSAI, the partially allowed NSSAI or the configured NSSAI at operation 626. At operation 630, the congestion timer may be stopped. At operation 632, the 5G network 107 may initiate to temporarily remove the congestion control for the S-NSSAI-2. The 5G network 107 may include the S-NSSAI-2 back in the configured NSSAI list along with the S-NSSAI-1. At operation 634, the 5G network 107 may transmit the Configuration update command to the UE 101 for the S-NSSAI-1 and the S-NSSAI-2 to be allowed. At operation 636, the S-NSSAI-2 may be available again for use by the UE 101. At operation 638, once the congestion timer associated with the S-NSSAI-2 is intentionally stopped by the UE 101, the PDU Establishment Request message associated with the S-NSSAI-2 may be transmitted by the UE 101 to the gNB1 103. Further, at operation 640, the gNB1 103 may forward the PDU Establishment Request message to the 5G network 107 to access one or more services from at least one network slice, that is, the S-NSSAI-2. At operation 642, the 5G network 107 may transmit to the UE 101 the PDU Establishment Accept corresponding to the S-NSSAI-2.

[0112] Fig. 6C is a sequence of operations depicting a method 600c for network slice management, as the UE 101 may not support the NS-AoS feature (as explained in Fig. 6A), according to implementations of the present disclosure.

[0113] Fig. 6C may overcome the challenge in network slice management, as the UE 101 may not support the NS-AoS feature that is explained earlier in Fig. 5C.

[0114] Operations 652-670 of Fig. 6C relate to the PDU Establishment Reject message as explained in reference to operations 552-570 (shown in Fig. 5C), respectively. Accordingly, a detailed description of the operations 652-670 has been omitted for the sake of brevity. At operation 672, the 5G network 107 may transmit the Configuration update command to notify the UE 101 that the configured network slices, e.g., the S-NSSAI-1, are available, while the S-NSSAI-2 in the first TA (TA1) is partially allowed. At operation 674, the UE 101 may intentionally stop the congestion timer that was initiated at operation 670. At operation 676, the congestion timer may be stopped.. At operation 678, the UE 101 may transit back to the first Tracking area (TA1). Thus, at operation 680, the 5G network 107 may further transmit the Configuration update command to notify the UE 101 that the configured and allowed network slices, e.g., the S-NSSAI-1 and the S-NSSAI-2, are now available. Hence, at operation 682, the UE 101 may identify that the S-NSSAI-2 is available again to avail the one or more services. Further, at operation 684, the UE 101 may transmit the PDU Establishment Request corresponding to the S-NSSAI-2 to the gNB1 103. At operation 686, the gNB1 103 may forward the PDU Establishment Request to the 5G network 107. At operation 688, the UE 101 may receive the PDU Establishment Accept message from the 5G network 107. The intentional stopping of the back-off timer associated with the S-NSSAI-2 may help the UE 101 to access the one or more services associated with the S-NSSAI-2.

[0115] Further, the above method 600c may be applicable for any NAS or AS signalling, which may lead to non-availability of the network slice or services.

[0116] Fig. 7A illustrates another environment 700a depicting challenges during the network slice management during the UE 101 mobility, according to the related art.

[0117] As referred to in Fig. 7A, an environment 700a may include the UE 101 may encounter a network slice availability problem during the UE 101's mobility. In an implementation, the UE 101 may be registered and camped in the first Cell (for example, Cell 1), in RA corresponding to the first TA (TA1). The UE may have the plurality of registered network slices, that is, the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3, with the S-NSSAI-2 being fully allowed and the S-NSSAI-1 being partially allowed in the first TA (TA1). As the UE 101 moves to the second TA (TA2), corresponding to the second Cell (Cell 2), only the S-NSSAI-2 may be supported, while the S-NSSAI-1 may not be available in the second TA (TA2). The UE 101 may continue operating using the S-NSSAI-2. Later, when a second UE 101a tries to re-establish or reconnect with the S-NSSAI-1, the PDU Establishment Request message may be rejected because the network slice admission control (NSAC) quota for the S-NSSAI-1 in the second TA (TA1) may be full. Consequently, even though the UE 101a may have subscription to one or more services corresponding to the S-NSSAI-1, the UE 101a may not regain access due to quota exhaustion in the TA1, as first UE 101 not deregistring S-NSSAI-1 while it is staying in second TA(TA2) eventhough S-NSSAI-1 is not supported in TA2. Such a situation may lead to limitations where the mobility between the TAs with different network slices may be supported, and the quota constraints may cause the services disruption, which may prevent the UE 101 from reusing the originally configured network slice.

[0118] Fig. 7B illustrates a sequence of operations 700b depicting a challenge of resource blocking associated with network slice management during the UE 101 mobility, as shown in Fig. 7A, according to the related art.

[0119] As referred to in Fig. 7B, at operation 702, the UE 101 may be configured with the plurality of network slices, that is, the S-NSSAI-1 and the S-NSSAI-2.

[0120] At operation 704, the UE 101 may transmit the RRCConnectionSetupComplete request to the gNB1 103 to register the plurality of network slices for accessing one or more services. In response, at operation 706, the gNB1 103 may forward the request to the 5G network 107. At operation 708, upon receiving the request from the gNB1 103, the 5G network 107 may transmit the Registration Accept message to the UE 101, allowing one of the network slices, that is the S-NSSAI-2 and the S-NSSAI-1 to be partially allowed, in the first TA (TA1), to be accessed for providing one or more services. At operation 710, the UE 101 may transmit the PDU Establishment Request message corresponding to the S-NSSAI-1 to the gNB1 103. At operation 712, the gNB1 103 may forward the PDU Establishment request message to the 5G network 107. At operation 714, upon receiving the PDU Establishment Request message from the gNB1 103, the 5G network 107 may transmit the PDU Establishment Accept message to the UE 101. At operation 716, the UE 101 may transmit the PDU Establishment Request message corresponding to the S-NSSAI-2 to the gNB1 103. At operation 718, the gNB1 103 may forward the PDU Establishment Request message to the 5G network 107. At operation 720, upon receiving the PDU Establishment Request message from the gNB1 103, the 5G network 107 may transmit the PDU Establishment Accept message to the UE 101. At operation 722, the UE 101 may transit and get connected to the second TA (TA2). At operation 724, the UE 101 may stay for a very long time in the second TA (TA2). Since in the second TA (TA2), the UE 101 may not utilise the services associated with the S-NSSAI-1 while being registered. Thus, the services associated with the S-NSSAI-1 may be wasted, blocking other users from availing the services associated with the S-NSSAI-1. In an implementation, the AMF 107 may use the NSAC feature to restrict the number of users to connect to a specific slice. Thus, the present scenario may lead to insufficient resource utilisation and potential service denial for the other users.

[0121] Further to overcome the above problem, as depicted in Figs. 7A-7B, the solution is provided in the forthcoming paragraph while explaining Figs. 8B-8C.

[0122] Fig. 8A illustrates an environment 800a depicting a solution to overcome the problem of resource blocking during the UE 101 mobility as depicted in Fig. 7B, according to implementations of the present disclosure.

[0123] In an implementation, the UE 101 may overcome the problem, as referred to in Fig. 7A, of resource blocking caused by the UE 101 holding unused network slice registrations in the TA (TA) where the network slices are unsupported. In an implementation, initially the UE 101 may register both the network slices, that is, the S-NSSAI-1 and the S-NSSAI-2, in the first TA (TA1) with the first Cell (i.e., Cell 1), where both the network slices, that is, the S-NSSAI-1 and the S-NSSAI-2 available. In a scenario where the UE 101 transits to the second TA (TA2) with the second Cell (i.e., Cell 2), only the S-NSSAI-2 may be supported, whereas the S-NSSAI-1 may remain registered. As the S-NSSAI-1 may remain registered, the UE 101 may unnecessarily occupy the NSAC quota corresponding to the S-NSSAI-1. Hence, to resolve such a challenge, a network slice inactivity timer may be introduced. The network slice inactivity timer may be initiated when the UE 101 moves to a Cell where a specific network slice, for example, the S-NSSAI-1, may be unavailable. Further, once the network slice inactivity timer expires, the UE 101 may automatically deregister the unused network slice to free the reserved resources.

[0124] In an implementation, an Artificial Intelligence (AI) model-based optimisation may be implemented. The AI model may be trained to predict the UE's 101 mobility and estimate the timestamp for how long the UE 101 may remain in the second TA (TA2) and predict the inactive timer value accordingly. In an advantageous aspect, the present solution may ensure better resource efficiency, dynamic network slice management, and improved user experience by preventing long-term blocking of the network slice quota.

[0125] Fig. 8B illustrates a sequence of operations depicting a method 800b for overcoming the challenge of resource blocking associated with network slice management at the UE 101 (as explained in Fig. 8A), according to implementations of the present disclosure.

[0126] Operations 802-822 of Fig. 8B are explained in reference to operations 702-722 (shown in Fig. 7B), respectively. Accordingly, a detailed description of operations 802-822 has been omitted for the sake of brevity. At operation 824, the UE 101 may execute the network slice inactivity timer to track the inactivity usage of the S-NSSAI-1 in the second TA (TA2). At operation 826 and operation 828, the network slice inactivity timers may be initiated and expired / terminated, respectively, by the UE 101. At operation 830, the UE 101 may trigger the PDU session release for the S-NSSAI-1. At operation 832, the UE 101 may transmit the PDU session Release request corresponding to the S-NSSAI-1 to the gNB2 113 associated with the second TA (TA2). At operation 834, the gNB2 113 may forward the PDU session Release request to the 5G network 107. In response, at operation 836, the 5G network 107 may transmit to the UE 101 the PDU session Release command. At operation 838, 5G network 107 may acknowledge the PDU session Release command by transmitting the PDU session release Complete message to the UE.

[0127] Fig. 8C illustrates a sequence of operations depicting another implementation of a method 800c for overcoming the challenge of resource blocking associated with network slice management at the UE 101 (as explained in Fig. 8A), according to implementations of the present disclosure.

[0128] Operations 850-890 of Fig. 8C are explained in reference to operations 702-722 (shown in Fig. 7B) (as well as operations 802-822 shown in FIG. 8B), respectively. Accordingly, a detailed description of operations 850-870a has been omitted for the sake of brevity. At operation 870b, the 5G network 107 (in place of the UE 101 as explained in operation 824 of Fig. 8B) may execute the network slice inactivity timer to track inactivity usage of the S-NSSAI-1 in the second TA (TA2). At operation 872 and operation 874, the network slice inactivity timers may be initiated and expired / terminated by the 5G network 107, respectively (in place of the UE 101 as explained in operations 826 and 828 of Fig. 8B). At operation 876, the 5G network 107 may de-register the S-NSSAI-1 and update the configuration update command with only S-NSSAI-2 as allowed. At operation 878, the 5G network 107 may transmit the Configuration update command corresponding to the S-NSSAI-2 to the UE 101. At operation 890, upon receiving the Configuration update command, the UE 101 may release the PDU session related to the S-NSSAI-1 locally.

[0129] Further, the above method 800c may be applicable for any NAS or AS signalling, which may lead to non-availability of the network slice or services.

[0130] Fig. 9A illustrates an environment 900a depicting challenges during the network slice management when the UE 101 gets stuck in the first TA (TA1), according to the related art.

[0131] As referred to in Fig. 9A, an environment 900a may include the UE 101, which may encounter restricted mobility and service access due to the network slice-specific congestion handling. In an implementation, initially the UE 101 may be registered in the first TA (TA1) corresponding to the first Cell (i.e., Cell 1) with the plurality of network slices, such as the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3. In the first TA (TA1), the S-NSSAI-1 may be fully allowed, while the S-NSSAI-2 and the S-NSSAI-3 may be partially allowed. When the UE 101 attempts to establish the PDU session for the S-NSSAI-3, the UE 101 may get rejected, triggering the congestion timer corresponding to the S-NSSAI-3. While the congestion timer is active, the UE 101 may remain in the first TA (TA1), and may not be able to re-select to the second TA (TA2) because a Network Slice Admission Group (NSAG) configuration may restrict the movement. The second TA (TA2) may contain services for the S-NSSAI-1 and the S-NSSAI-2. Such a scenario may create a problem where the UE 101 may be stuck in the first TA (TA1), and unable to benefit from the available network slice in the second TA (TA2), and the associated one or more services may also remain inaccessible. The present scenario also highlights the way the NSAG priorities and the congestion timers may unintentionally block the mobility and the service continuity / accessibility. An example of NSAG priority is illustrated in Table 2 below:

[0132] NSAG IDList of S-NSSAIsNSAG areas (List of TAIs)NSAG priority1S-NSSAI-1, the S-NSSAI-3TA112S-NSSAI-1, the S-NSSAI-2TA21

[0133] Fig. 9B illustrates a sequence of operations 900b depicting a challenge of resource blocking associated with network slice management during the UE 101 mobility, as shown in Fig. 9A, according to the related art.

[0134] As referred to in Fig. 9B, at operation 902, the UE 101 may be configured with the plurality of network slices, that is, the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3. At operation 904, the UE 101 may be camped on the first TA (TA1). At operation 906, the UE 101 may transmit the RRCConnectionSetupComplete request to the gNB1 103 to register the plurality of network slices for accessing one or more services. In response, at operation 908, the gNB1 103 may forward the request to the 5G network 107. At operation 910, upon receiving the request from the gNB1 103, the 5G network 107 may transmit the Registration Accept message to the UE 101, allowing one of the network slices, that is the S-NSSAI-1, while the S-NSSAI-2 being partially allowed in the second TA (TA2) and the S-NSSAI-3 being partially allowed in the first TA (TA1). Further, the priority of the first TA (TA1) and the second TA (TA2) are provided in Table 2 above. At operation 912, at the UE 101, the NAS may indicate the allowed NSSAI list and the NSAG information to the Access Stratum (AS) layer for cell camping on the RRC release. At operation 914, the UE 101 may trigger the PDU session corresponding to the S-NSSAI-3. At operation 916, the UE 101 may transmit the PDU Establishment Request message corresponding to the S-NSSAI-3 to the gNB1 103. At operation 918, the gNB1 103 may forward the PDU Establishment Request message to the 5G network 107. At operation 920, the 5G network 107 may identify that the S-NSSAI-3 may be congested. At operation 922, upon receiving the PDU Establishment Request message from the gNB1 103, the 5G network 107 may transmit the PDU Establishment Reject message to the UE 101. Hence, at operation 924, the UE 101 may initiate the congestion timer, e.g., for 20 minutes. At operation 926, the congestion timer may be initiated for 20 minutes. In a non-limiting example, the congestion timer may range from 10 seconds to approximately 3 hours. At operation 928, the UE 101 may receive the RRC Release message from the 5G network 107. At operation 930, upon receiving the RRC release message, the UE 101 may remain in the first TA (TA1) and may not re-select to the second TA (TA2), since the congested S-NSSAI-3 may have the higher priority in the allowed NSSAI that may not be removed from the AS layer. At operation 932, even though the UE 101 may require using the one or more services of the S-NSSAI-2, due to cell selection criteria, the UE 101 may not be able to use the S-NSSAI-2 and may remain stuck in the first TA (TA1). Hence, although the UE wants to use S-NSSAI-2, which is supported in TA2, the UE 101 may remain camped in the first TA (TA1) and governed by the higher-priority NSAG ID-1. Such a situation illustrates how the priority-based NSAG assignment and the congestion timers may inadvertently prevent the UE 101 from accessing available services, leading to inefficient resource utilisation and degraded user experience. To resolve such issues, networks need to implement smarter slice mobility and timer management strategies, ensuring that UEs can dynamically switch to available slices based on real-time conditions and service needs.

[0135] Further to overcome the above problem as depicted in Figs. 9A-9B, the solution is provided in the forthcoming paragraph while explaining Figs. 10A and 10B.

[0136] Fig. 10A illustrates an environment 1000a depicting a solution to overcome the challenges during the network slice management when the UE 101 gets stuck in the first TA (TA1), as depicted in Figs. 9A-9B, according to implementations of the present disclosure.

[0137] In an implementation, to overcome the challenges, as referred to in Fig. 9A, during the network slice management when the UE 101 gets stuck in the first TA (TA1), the NAS layer exclude congested slice (S-NSSAI-3) and indicate to AS and the AS layer may re-select to the second TA (TA2) as the next high priority. When the UE intends to use the S-NSSAI-2 and transmits the PDU Establishment Request message with the S-NSSAI-2 and 5G network may accept the request. When the congestion timer expires, a Non-Access Stratum (NAS) may update the allowed NSSAI list to the AS layer to include the S-NSSAI-3. Thus, the allowed NSSAI may include the S-NSSAI-1, the S-NSSAI-2 and the S-NSSAI-3. Further, the UE 101 may release the N1 NAS signalling connection and re-selects to first TA (TA1). Hence, the UE 101 may further request the S-NSSAI-3 for using associated one or more services, once the S-NSSAI-3 becomes available.

[0138] Fig. 10B (which includes Fig. 10B1 and Fig. 10B2) illustrates a sequence of operations depicting a method 1000b for overcoming the challenge (as explained in Fig. 10A) encountered during the network slice management when the UE 101 gets stuck in the first TA (TA1), according to implementations of the present disclosure.

[0139] Operations 1002-1026 of Fig. 10B are explained in reference to operations 902-926 (shown in Fig. 9B), respectively. Accordingly, a detailed description of operations 1002-1026 has been omitted for the sake of brevity. At operation 1028, the NAS signalling message may be to remove the S-NSSAI-3 and may indicate to the UE 101 about the allowed network slices from the NSSAI list, that is, the S-NSSAI-1 and the S-NSSAI-2, to the AS layer as allowed for accessing the one or more services. At operation 1030, the UE 101 may receive the RRC release message from the 5G network 107. At operation 1032, upon receiving the RCC release message, the UE 101 may re-select the TA2, since the S-NSSAI-1 and the S-NSSAI-3 may not be obtained for accessing the one or more services, as being on the second priority in the priority list (as shown in Table 2). At operation 1034, the UE 101 may require using the services associated with the S-NSSAI-2. At operations 1036-1040, the UE 101 may transmit the PDU Establishment request message to the 5G network 107 via the gNB1 103, and in response, the UE 101 may receive the PDU Establishment Accept message corresponding to the S-NSSAI-2 from the 5G network 107. At operation 1042, the congestion timer may be stopped. At operation 1044, the NAS signalling message may be transmitted to add the S-NSSAI-3 and to indicate the plurality of network slices, such as the S-NSSAI-3, the S-NSSAI-1, and the S-NSSAI-2, as allowed to the AS layer. At operation 1046, the UE 101 may re-select to the TA (TA1) to access the one or more services from the S-NSSAI-3 as high priority. At operations 1048-1052, the UE 101 may transmit the PDU Establishment request message to the 5G network 107 via the gNB1 103, and in response, the UE 101 may receive the PDU Establishment Accept message corresponding to the S-NSSAI-3 from the 5G network 107.

[0140] Fig. 11A illustrates another environment 1100a depicting challenges during the network slice management at the UE 101, according to the related art.

[0141] As referred to in Fig. 11A, an environment 1100a may include the UE 101 may be configured with three network slices, that is, the S-NSSAI-1, S-NSSAI-2, and S-NSSAI-3. The UE 101 may currently be camped in the first TA (TA1), which may support only the S-NSSAI-1 and the S-NSSAI-2. However, another TA, for example, the second TA (TA2), may be supporting the S-NSSAI-1 and the S-NSSAI-3. The UE 101 may transmit the registration request, including all three configured network slices. The network entity 111 may respond with the Registration Accept message, indicating that the S-NSSAI-1 is allowed, the S-NSSAI-2 is partially allowed in the first TA (TA1), and the S-NSSAI-3 is partially allowed in the second TA (TA2). Further, two NSAGs, that is the NSAG ID-1 may include the S-NSSAI-1 and the S-NSSAI-2 with higher priority (priority 1) and may be associated with the first TA (TA1), while the NSAG ID-2 may include the S-NSSAI-1 and the S-NSSAI-3 with lower priority (priority 2) and which may be associated with the second TA (TA2). Although the UE 101 may successfully register for the S-NSSAI-2 over the non-3GPP (Wi-Fi) access, the UE 101 may not utilise the S-NSSAI-3 in the current TA location, that is, the first TA (TA1), because the first TA (TA1) may not support the S-NSSAI-3. The UE 101 may remain in the first TA (TA1) due to the higher priority of the NSAG ID-1, even though the UE 101 may not access the S-NSSAI-3 services in the first TA (TA1). The UE 101 may not re-select the second TA (TA2), where the S-NSSAI-3 is available via the 3GPP cellular, because the reselection logic may prioritise the NSAG ID-1 and may not consider the availability of the S-NSSAI-3 in the second TA (TA2) sufficient to override the priority. As a result, the UE 101 may be unable to access the S-NSSAI-3 services via the 3GPP cellular, despite their availability in the second TA (TA2), leading to a situation where the UE 101 may remain in the location with no service for the desired network slice due to the NSAG prioritisation constraints.

[0142] Fig. 11B illustrates a sequence of operations 1100b depicting a challenge in network slice management at the UE due to the NSAG prioritisation constraints as shown in Fig. 11A, according to the related art.

[0143] In an implementation, as referred to in Fig. 11B, at operation 1102, the UE 101 may be configured with the plurality of network slices associated with the 3GPP cellular, that is, the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3, and one network slice associated with the non-3GPP (Wi-Fi) access, that is the S-NSSAI-2. At operation 1104, the UE 101 may transmit to the gNB1 103 the RRCConnectionSetupComplete (REGISTRATION REQUEST) corresponding to the one or more network slicess, such as the S-NSSAI-2 and the S-NSSAI-3, which may be supporting the NSAG. At operation 1106, the gNB1 103 may forward the request received from the UE 101 to the 5G network 107. At operation 1108, the 5G network 107 may transmit the Registration Accept message to the UE 101, allowing one of the network slices, that is, the S-NSSAI-1, while the S-NSSAI-2 is partially allowed in the second TA (TA2), and the S-NSSAI-3 is partially allowed in the first TA (TA1). The UE may obtain NSAG Information. At operation 1110, the NSAG1 may include the S-NSSAI-1 / S-NSSAI-2 at the Priority-1, while the NSAG2 may include the S-NSSAI-1 / S-NSSAI-3 at the Priority-2. At operation 1112, the UE 101 may transmit the Registration request corresponding to the registered network slice, that is, the S-NSSAI-2, to a non-3GPP (Wi-Fi) access 115 supporting the S-NSSAI-2. At operation 1114, the non-3GPP (Wi-Fi) access 115 may forward the request to the 5G network 107. At operation 1116, the UE 101 may receive a Registration Accept message from the 5G network 107 to notify the UE 101 that the required network slice, that is, the S-NSSAI-2, is now available to access the associated one or more services. However, at operation 1118, UE want to use service related to S-NSSAI-3, since the S-NSSAI-3 is not allowed in the first TA (TA1) and due to the NSAG priority, the UE 101 may not be able to access the S-NSSAI-3, as the UE 101 may not re-select the second TA (TA2).

[0144] Further to overcome the above problem as depicted in Figs. 11A-11B, the solution is provided in the forthcoming paragraph while explaining Figs. 12A and 12B.

[0145] Fig. 12A illustrates an environment 1200a depicting a solution to overcome the congestion timer issue as depicted in Figs. 11A-11B, according to implementations of the present disclosure.

[0146] As explained in reference to Fig. 11B, once the UE 101 registers for the S-NSSAI-2 in the non-3GPP (Wi-Fi) access 115, and the UE intends to use the services associated with the S-NSSAI-2. While operating within the 3GPP cellular, the UE 101 may have access to the S-NSSAI-1 and the S-NSSAI-2 linked to the first TA (TA1), which may potentially restrict access to the one or more services associated with the S-NSSAI-3. To address this limitation, the NAS signalling message to remove the S-NSSAI-2 from the allowed / partially allowed NSSAI list may be sent to the RRC. Such an adjustment may enable the UE 101 to re-select the second TA (TA2), thereby allowing access to one or more services tied to both the S-NSSAI-1 and the S-NSSAI-3 within the 3GPP cellular. Additionally, the UE 101 may still be able to connect to services associated with the S-NSSAI-2 through the non-3GPP (Wi-Fi) access 115. Here, the UE 101 may not want the MA PDU for S-NSSAI-2.

[0147] Fig. 12B illustrates a sequence of operations depicting a method 1200b depicting the solution (as explained in Fig. 12A) to overcome the slice accessibility issue as depicted in Figs. 11A-11B, according to implementations of the present disclosure.

[0148] Operations 1202-1216 of Fig. 12B relate to the receipt of the Registration Accept message by the UE 101, as explained in reference to operations 1102-1116 (shown in Fig. 11B), respectively. Accordingly, a detailed description of the operations 1202-1216 has been omitted for the sake of brevity. At operation 1218, the UE 101 may intend to use the S-NSSAI-3 also. Thus, at operation 1220, the NAS is to remove S-NSSAI-2 from the RRC allowed / partially allowed list. At operation 1222, the RRC may be re-selected to the second TA (TA2). At operation 1224, once the RRC may be re-selected to the second TA (TA2), the UE 101 may get the one or more network services associated with the S-NSSAI-1 and the S-NSSAI-3 from the 3GPP cellular and the one or more network services associated with the S-NSSAI-2 from the non-3GPP (Wi-Fi) access 115. When UE intend to use the MA PDU for S-NSSAI-2 / WIFI, the coverage may be lost, and the NAS may add the S-NSSAI-2 to allowed list sent to the AS layer.

[0149] Fig. 13A illustrates an environment 1300a depicting challenges during the network slice management due to mobility registration, according to the related art.

[0150] As referred to in Fig. 13A, an environment 1300a may include the UE 101, which may not be pre-configured with any of the plurality of slices but holds a subscription for the plurality of network slices, such as the S-NSSAI-1, the S-NSSAI-2, and the S-NSSAI-3, as provisioned at the 5G network 107. The UE 101 may camp in the first TA (TA1), which may be supporting all three network slices, while the second TA (TA2) may be supporting only the S-NSSAI-2 and the S-NSSAI-3. During initial registration, the UE 101 may send a request without specifying any of the network slices, and the network entity 111 may respond with the Registration Accept message, indicating that the S-NSSAI-2 and the S-NSSAI-3 are allowed, and the S-NSSAI-1 is partially allowed. The registration area (RA) may include both the first TA (TA1) and the second TA (TA2). Later, the UE 101 may intend to de-register from the S-NSSAI-2 and register only for the S-NSSAI-1 and the S-NSSAI-3. However, due to the 3GPP specification constraints, the UE 101 may not include partially allowed slices (like S-NSSAI-1) in the Requested NSSAI list during a mobility registration procedure. As a result, the UE 101 may send the mobility registration request with only the S-NSSAI-3, inadvertently excluding the S-NSSAI-1. Such a scenario may lead to a mismatch between the UE's 101 intended network slice usage and the actual registration outcome, potentially causing service denial or inefficient slice utilisation. Ideally, the UE 101 should have been able to include both the S-NSSAI-1 and the S-NSSAI-3 in the mobility registration request, but current standards prohibit the inclusion of the partially allowed network slices, exposing a gap in slice-aware mobility handling.

[0151] Fig. 13B illustrates a sequence of operations 1300b depicting the challenge associated with network slice management due to mobility registration as shown in Fig. 13A, according to the related art.

[0152] As referred to in Fig. 13B, at operation 1302, the UE 101 may not have any of the plurality of network slices configured. At operation 1304, the UE 101 may transmit the RRCConnectionSetupComplete (REGISTRATION REQUEST) to the gNB1 103. Further, at operation 1306, the gNB1 103 may forward the request received from the UE 101 to the 5G network 107. In response, at operation 1308, the 5G network 107 may revert the UE 101 by transmitting the Registration Accept message corresponding to the first TA (TA1) and the second TA (TA2). Through the Registration Accept message the UE 101 may identify that the S-NSSAI-2 may be fully allowed, while the S-NSSAI-1 may be partially allowed in the first TA (TA1). At operation 1310, the UE 101 may intend to de-register for the S-NSSAI-2 and register only for the S-NSSAI-1. However, at operation 1312, the UE 101 may not transmit the mobility registration with the S-NSSAI-1 because the specification may not allow including the partially allowed network slices in the mobility registration.

[0153] Further to overcome the above problem as depicted in Figs. 13A-13B, the solution is provided in the forthcoming paragraph while explaining Fig. 14A and Fig. 14B.

[0154] Fig. 14A illustrates an environment 1400a depicting a solution to overcome the depicting the challenges during the network slice management due to mobility registration as depicted in Figs. 13A-13B, according to implementations of the present disclosure.

[0155] As explained in reference to Figs.14A-14B, once the UE 101 receives the Registration Accept message indicating that the S-NSSAI-2 is allowed and the S-NSSAI-1 is partially allowed in the first TA (TA1), while the S-NSSAI-1 is partially rejected in the second TA (TA2). The UE's registration area includes both TA1 and TA2. Later, the UE decides to de-register from Slice 2 (S-NSSAI-2) and register only for the S-NSSAI-1. To initiate the change, the UE 101 may transmit the mobility registration request that may include only the S-NSSAI-1. Such an action may reflect the UE's 101 intent to continue using the S-NSSAI-1, despite being partially available across the registration area (RA), and to exclude the S-NSSAI-2 from the NSSAI list to avoid future service access.

[0156] Fig. 14B illustrates a sequence of operations depicting a method 1400b depicting the solution (as explained in Fig. 14A) to overcome the challenges during the network slice management due to mobility registration as depicted in Figs. 13A-13B, according to implementations of the present disclosure.

[0157] Operations 1402-1416 of Fig. 12B relate to the receipt of the Registration Accept message by the UE 101, as explained in reference to operations 1302-1308 (shown in Fig. 11B), respectively. Accordingly, a detailed description of the operations 1402- 1408 has been omitted for the sake of brevity. At operation 1410, the UE decides to de-register from Slice 2 (S-NSSAI-2) and register only for the S-NSSAI-1. At operation 1412, the UE 101 may trigger the Mobility Registration with the S-NSSAI-1. At operation 1414, the UE 101 may transmit the RRCConnectionSetupComplete (REGISTRATION REQUEST) corresponding to the S-NSSAI-1 to the gNB1 103. At operation 1416, the gNB1 103 may forward the Request received from the UE 101 to the 5G network 107. In response, at operation 1418, the 5G network 107 may transmit the Registration Accept message to the UE 101 corresponding to the S-NSSAI-1 being allowed in the registration area (RA) associated with the first TA (TA1).

[0158] Fig. 15A illustrates an environment 1500a depicting challenges during the network slice management when the partially allowed NSSAI is not considered, according to the related art.

[0159] As referred to in Fig. 15A, an environment 1500a may include the UE 101, which may be configured to use two network slices, for example, the S-NSSAI-1 and the S-NSSAI-2, and is camped in the first TA (TA1), which may support both the network slices. The UE 101 may initiate the registration request over the 3GPP access, including both the network slices. The UE 101 may receive the Registration Accept message indicating that the S-NSSAI-2 is fully allowed, while the S-NSSAI-1 is only partially allowed in the first TA (TA1). The registration area (RA1) may include both the first TA (TA1) and the second TA (TA2). Subsequently, the UE 101 may transmit the registration request over the non-3GPP access (Wi-Fi) 115 for the S-NSSAI-1 and may receive the Registration Accept message confirming that the S-NSSAI-1 is allowed. The UE 101 may successfully establish a Multi-Access (MA) PDU session for the S-NSSAI-1 over the non-3GPP access. In an implementation, the MA PDU may allow the UE 101 to utilize both the 3GPP cellular and the non-3GPP access simultaneously or individually for data transmissionHowever, when the UE 101 attempts to establish the MA PDU session for the S-NSSAI-1 over the 3GPP access, the UE 101 may fail because partially allowed network slices may not be considered valid for the MA PDU session establishment. Such a scenario may lead to a service gap, where the UE 101 may be unable to fully utilise the configured network slice across both access types, that is, the 3GPP access and the non-3GPP access, despite partial support in the registration area.

[0160] Fig. 15B illustrates a sequence of operations 1500b depicting a challenge of resource blocking associated with network slice management when the partially allowed NSSAI is not considered, as shown in Fig. 15A, according to the related art.

[0161] As shown in Fig. 15B, at operation 1502, the UE 101 may be configured to use the S-NSSAI-1 and the S-NSSAI-2. At operation 1504, the UE 101 may transmit the RRCConnectionSetupComplete (REGISTRATION REQUEST) corresponding to the 3GPP access that may be associated with the gNB1 103 in the second TA (TA2). The second TA (TA2) may be having S-NSSAI-2 to the gNB2 113 for both the network slices. At operation 1506, the gNB1 103 may forward the registration request received from the UE 101 to the 5G network 107. In response, at operation 1508, the UE 101 may receive the Registration Accept message from the 5G network 107, indicating that the S-NSSAI-2 is fully allowed, while the S-NSSAI-1 is only partially allowed in the first TA (TA1). Accordingly, at operation 1510, the UE 101 may transmit the RRCConnectionSetupComplete (REGISTRATION REQUEST) for the S-NSSAI-1 corresponding to the non-3GPP access to a Non-3GPP Interworking Function (N3iwf) 117. At operation 1512, upon receiving the registration request from the UE 101, the N3iwf 117 may forward the registration request to the 5G network 107. In response, at operation 1514, the UE 101 may receive the Registration Accept message from the 5G network 107. At operation 1516, the UE 101 may trigger the MA PDU registration with the S-NSSAI-1 over the non-3GPP connectivity. Further, the UE 101 may transmit the MA PDU Establishment Request (MA PDU) message to the N3iwf 117. At operation 1520, the N3iwf 117 may forward the MA PDU request received from the UE 101 to the 5G network 107. At operation 1522, the UE 101 may receive the PDU Establishment Accept message from the 5G network 107. At operation 1524, the UE 101 may attempt to trigger the MA PDU for the S-NSSAI-1 over the 3GPP cellular. However, the UE 101 may fail to trigger the MA PDU for the S-NSSAI-1 as the network slice present in the current TA may be partially allowed. Such an issue underscores a limitation in the current 3GPP specifications, where the partial slice allowance may restrict cross-access network slice utilization, impacting the service continuity / accessibility and multi-access efficiency.

[0162] Fig. 16A illustrates an environment 1600a depicting a solution to overcome the challenges during the network slice management when the partially allowed NSSAI is not considered, as shown in Figs. 15A-15B, according to implementations of the present disclosure.

[0163] In an implementation, to overcome the challenges, as referred to in Fig. 10A, the UE 101 may receive the Registration Accept message over the non-3GPP access (such as Wi-Fi), confirming that the S-NSSAI-1 is allowed. Based on the authorisation, the UE 101 may successfully establish the MA PDU session for the S-NSSAI-1 over the non-3GPP access, enabling the service continuity / accessibility through the corresponding access type. Subsequently, the UE 101 may also initiate and successfully establish the MA PDU session for the S-NSSAI-1 over the 3GPP access (e.g., 5G NR), demonstrating that the network slice may be permitted and available across both the access domains, i.e., the 3GPP access, and the non-3GPP access. In an advantageous aspect, such seamless dual-access connectivity may reflect proper slice configuration, synchronised slice availability across access types, and effective coordination between the UE and the core network functions like the AMF and SMF. Furthermore, the dual-access connectivity may also ensure that the UE 101 may leverage the same network slice for consistent service delivery, regardless of whether the UE 101 is connected via the 3GPP cellular or the non-3GPP (Wi-Fi).

[0164] Fig. 16B illustrates a sequence of operations depicting a method 1600b depicting the solution (as explained in Fig. 16A) to overcome the challenges during the network slice management when the partially allowed NSSAI is not considered, as shown in Figs. 15A-15B, according to implementations of the present disclosure.

[0165] Operations 1602-1622 of Fig. 16B are explained in reference to operations 1502-1522 (shown in Fig. 15B), respectively. Accordingly, a detailed description of the operations 1602-1622 has been omitted for the sake of brevity. At operation 1624, the UE 101 may intend to trigger the MA PDU over the 3GPP access for the partially allowed network slice, that is, the S-NSSAI-1. At operation 1626, the UE 101 may transmit the MA PDU Establishment Request message corresponding to the S-NSSAI-1 to the gNB1 103. At operation 1628, the gNB1 103 may forward the request received from the UE 101 to the 5G network 107. In response, at operation 1630, the UE 101 may receive the PDU Establishment Accept message corresponding to the S-NSSAI-1 from the 5G network 107 to notify the UE that the S-NSSAI-1 may be allowed.

[0166] Fig. 17 illustrates an example process flow depicting a method 1700 for network slice management at the UE 101, in the wireless communication system, according to implementations of the present disclosure.

[0167] At operation 1702, the method 1700 may include generating a request to access one or more services associated with at least one network slice. In an implementation, generating the request to access the one or more services associated with the at least one network slice may include generating the request in response to at least receiving, from an application, an application request to access the one or more services. In another implementation, generating the request to access the one or more services associated with the at least one network slice may include detecting the expiration of a congestion timer associated with the at least one network slice expires and receiving the application request to access the one or more services associated with at least one network slice. In another implementation, generating the request to access the one or more services associated with the at least one network slice may include detecting an addition of the at least one network slice and receiving the application request to access the one or more services associated with at least one network slice.

[0168] At operation 1704, the method 1700 may include determining whether the at least one network slice associated with the one or more services is available in the current PLMN and the associated RAT, based on a predefined PLMN / RAT / TAC / CELL selection assistance information is maintained by the UE 101. In an implementation, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on a successful UE 101 registration with the at least one network slice to access the one or more services based on the generated request. In another implementation, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on the UE 101 mobility information indicating the movement or transit of the UE 101 to a different PLMN, a different Tracking Area Identifier (TAI), a different Registration Area (RA), and a different Cell. In an implementation, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on a change in configured slice information based at least on either addition or removal of one or more network slicess due to a subscription change or network congestion. In another implementation, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on a failure in the UE 101 access request to the at least one network slice. In an implementation, the predefined PLMN / RAT / TAC / CELL selection assistance information may include a list of PLMNs. The each PLMN of the list of PLMNs may be associated with a list of RATs, a list of Tracking Area Code (TAC), a list of cells, a list of network slices, subscription information, slice mapping information, slice availability information, congestion information, corresponding priority information and the like.

[0169] At operation 1706, the method 1700 may include selecting at least one of the current PLMN, a new PLMN, the current PLMN with a different RAT, the current PLMN with the same RAT and a different cell in response to determining. In an implementation, selecting may include updating the predefined PLMN / RAT / TAC / CELL selection assistance information based on network slice congestion and availability information. In another implementation, selecting the PLMN, the RAT, the TAC, and the Cell based on the network slice congestion and availability information from the updated predefined PLMN / RAT / TAC / CELL selection assistance information table (i.e., Table 1).

[0170] At operation 1708, the method 1700 may include transmitting (1708), to the network entity, the NAS signalling message to access the one or more services. In an implementation, transmitting the NAS signalling message may include transmitting, to the network entity 111, an Initial and Mobility registration request message for accessing one or more registers associated with the network entity. In another implementation, transmitting the NAS signalling message may include transmitting, to the network entity 111, the MA PDU Establishment Request message. In another implementation, transmitting the NAS signalling message may further include transmitting, to the network entity 111, the PDU Establishment Request message to access the one or more services.

[0171] In an implementation, the method 1700 may further include requesting, from the network entity 111, at least one of the default configured and the partially allowed network slice in the NAS signalling message.

[0172] Fig. 18 illustrates another example process flow depicting a method 1800 for network slice management at the UE 101, in the wireless communication system, according to implementations of the present disclosure.

[0173] At operation 1802, the method 1800 may include transmitting, to the network entity 111, the NAS signalling message to access one or more services from at least one first network slice from a default or configured or allowed or partially allowed network slice list associated with the PLMN, the RAT, the TAC, and the Cell.

[0174] At operation 1804, the method 1800 may include receiving, from the network entity 111, the NAS signalling reject message indicating the congestion at the at least one first network slice, such as the S-NSSAI-1, associated with the PLMN, the RAT, the TAC, and the Cell and initiating the congestion / back-off timer.

[0175] At operation 1806, the method 1800 may include updating the predefined PLMN / RAT / TAC / CELL selection assistance information table (i.e., Table 1).

[0176] At operation 1808, the method 1800 may include performing selection of the PLMN and the RAT combination based on the updated predefined PLMN / RAT / TAC / CELL selection assistance information table, i.e., Table 1.

[0177] In an implementation, the method 1800 may further include receiving, from the network entity 111, at least one of a NAS signalling message or the AS signalling message indicating the removal of the at least one network slice from at least one of the default, the configured, the allowed, or the partially allowed network slice list for which the congestion timer may be running. The method 1800 may further include stopping the congestion timer associated with the at least one removed network slice in response to receiving the at least one of the NAS or the AS signalling message. In an implementation, if the congestion timers may be running for multiple other PLMNs or equivalent SNPNs, the UE 101 may stop the congestion timers for all such PLMNs or equivalent SNPNs.

[0178] Furthermore, the method 1800 may include updating the predefined PLMN / RAT / TAC / CELL selection assistance information table (Table 1) based on the received at least one of the NAS signalling message or the AS signalling message.

[0179] Fig. 19 illustrates another example process flow depicting a method 1900 for network slice management at the UE 101, in the wireless communication system, according to implementations of the present disclosure.

[0180] At operation 1902, the method 1900 may include identifying the transition of the UE 101 to the second Cell (Cell 2) in the second Tracking Area (TA2). The UE is initially registered for at least one network slice available in the first Cell in the first TA (TA1).

[0181] At operation 1904, the method 1900 may include initiating at least one predefined timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA (TA2) in response to identifying the transition. In an implementation, initiating the at least one predefined timer for tracking the inactivity usage may include predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA (TA2). In an implementation, initiating the at least one predefined timer for tracking the inactivity usage may include initiating the predefined timer with a value identified based on the predicted duration of the UE in the second TA (TA2).

[0182] At operation 1906, the method 1900 may include triggering the PDU session release request message to de-register the at least one network slice based on the expiration of the initiated at least one predefined timer.

[0183] Fig. 20 illustrates another example process flow depicting a method 2000 for network slice management at the network entity 111, in the wireless communication system, according to implementations of the present disclosure.

[0184] At operation 2002, the method 2000 may include tracking the TA of the UE 101. The UE 101 may be registered for at least one network slice available in the first Cell (Cell 1) in the first TA (TA1) associated with the network entity 111.

[0185] At operation 2004, the method 2000 may include identifying the transition of the UE 101 from the first TA (TA1) to a second cell in a second TA (TA2) based on the tracking.

[0186] At operation 2006, the method 2000 may include initiating at least one predefined timer for tracking the inactivity usage corresponding to the at least one network slice not supported in the second TA (TA2). In an implementation, initiating the at least one predefined timer for tracking the inactivity usage may include predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA (TA2). In another implementation, initiating the at least one predefined timer for tracking the inactivity usage may include initiating the predefined timer with a value identified based on the predicted duration of the UE in the second TA (TA2).

[0187] At operation 2008, the method 2000 may include triggering the PDU session release command message, to de-register the at least one network slice in response to detecting the expiration of the predefined timer.

[0188] Fig. 21 illustrates an example diagram of a device 2100 implemented in the UE 101, according to implementations of the present disclosure. The configuration of Fig. 21 may be understood as a part of the configuration of the UE 101. Further, the method as disclosed above may be implemented in the UE 101 according to implementations. In implementations, the UE 101 may correspond to the UE 101. Herein, it is understood that terms including "unit" or "module" at the end may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0189] Referring to Fig. 21, the device 2100 may include at least one at least one processor 2102 (generally referred to herein as the at least one processor 2102), a communication unit 2104 (e.g., communicator or communication interface), and / or a memory unit 2106 (e.g., a memory). By way of example, the UE 101 may be a User Equipment, such as a cellular phone or other device that communicates over a plurality of cellular networks (such as a 3G, 4G, a 5G or pre-5G, 6G network or any future wireless communication network). The communication unit 2104 may perform functions for transmitting and receiving signals via a wireless channel.

[0190] As an example, the at least one processor 2102 may be a single processing unit or a number of units, all of which could include multiple computing units. The at least one processor 2102 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and / or any devices that manipulate signals based on operational instructions. Among other capabilities, the at least one processor 2102 is configured to fetch and execute computer-readable instructions and data stored in the memory. The at least one processor 2102 may include one or a plurality of processors. At this time, one or a plurality of processors 2102 may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The one or a plurality of processors 2102 may control the processing of the input data in accordance with a predefined (or alternatively, given) operating rule or artificial intelligence (AI) model stored in the non-volatile memory and the volatile memory, e.g., memory unit 2106. The predefined (or alternatively, given) operating rule or artificial intelligence model is provided through training or learning.

[0191] The memory unit 2106 may include any non-transitory computer-readable medium known in the art including, for example, volatile memory, such as Static Random Access Memory (SRAM) and Dynamic Random Access Memory (DRAM), and / or non-volatile memory, such as Read-Only Memory (ROM), erasable programmable ROM, flash memories, hard disks, optical disks, and magnetic tapes.

[0192] In an implementation, the at least one processor 2102 may be configured to generate the request to access one or more services associated with at least one network slice. In an implementation, the at least one processor 2102 may be configured to generate the request in response to receiving, from an application, an application request to access the one or more services. In another implementation, the at least one processor 2102 may be configured to generate the request in response to detecting an expiration of a congestion timer associated with the at least one network slice expires and receive the application request to access the one or more services associated with at least one network slice. In another implementation, the at least one processor 2102 may be configured to generate the request in response to detecting the addition of the at least one network slice and receiving the application request to access the one or more services associated with at least one network slice.

[0193] In an implementation the at least one processor 2102 may be configured to determine whether the at least one network slice associated with the one or more services may be available in the current PLMN and the associated RAT based on the predefined PLMN / RAT / TAC / CELL selection assistance information maintained by the UE 101. The predefined PLMN / RAT / TAC / CELL selection assistance information may include the list of PLMNs. Each PLMN of the list of PLMNs may be associated with the list of RATs, the list of TAC, the list of Cells, the list of network slices, the subscription information, the slice mapping information, the slice availability information, the congestion information, the access availability (3GPP and non-3GPP) and the corresponding priority information.

[0194] In an implementation, the at least one at least one processor 2102 may be configured to update the PLMN / RAT / TAC / CELL selection assistance information based on the successful UE 101 registration with the at least one network slice to access the one or more services based on the generated request. Further, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on the UE 101 mobility information indicating the movement of the UE 101 to a different PLMN, a different TAI, a different Registration Area (RA), and a different Cell. Further, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on the network slice information. Furthermore, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on the change in configured slice information based at least on one addition or removal of one or more network slices due to the subscription change or network congestion. Additionally, the PLMN / RAT / TAC / CELL selection assistance information may be updated based on the failure in the UE 101 access request to the at least one network slice. In response to determining, the at least one processor 2102 may be configured to select at least one of the current PLMN, the new PLMN, the current PLMN with the different RAT, the current PLMN with the same RAT and the different Cell. In an implementation, the at least one at least one processor 2102 may be configured to update the predefined PLMN / RAT / TAC / CELL selection assistance information based on network slice congestion and availability information. Furthermore, the at least one at least one processor 2102 may be configured to select the PLMN, the RAT,the TAC, and the Cell based on the network slice congestion and availability information from the updated predefined PLMN / RAT / TAC / CELL selection assistance information table.

[0195] In an implementation, the at least one at least one processor 2102 may be configured to request, from the network entity 111, at least one of a default configured and a partially allowed network slice in the NAS signalling message.

[0196] In an implementation, the at least one processor 2102 may be configured to transmit, to the network entity 111, a Non-Access Stratum (NAS) signalling message to access the one or more services. In an implementation, to transmit the NAS signalling message, the at least one at least one processor 2102 may be configured to transmit, to the network entity 111, the Initial and Mobility registration request message for accessing one or more registers associated with the network entity 111. Further, the at least one processor 2102 may be configured to transmit, to the network entity 111, the MA PDU Establishment Request message. The at least one processor 2102 may be further configured to transmit, to the network entity 111, the PDU Establishment Request message to access the one or more services.

[0197] In another implementation, the at least one processor 2102 may be configured to transmit, to the network entity, the NAS signalling message to access one or more services from at least one first network slice from the default or the configured or the allowed or the partially allowed network slice list associated with the PLMN, the RAT, the TAC, and the Cell. The at least one processor 2102 may be configured to receive, from the network entity 111, the NAS signalling reject message indicating the congestion at the at least one first network slice associated with the PLMN, the RAT, the TAC, and the Cell and initiating the congestion / back-off timer. The at least one processor 2102 may be further configured to update a predefined PLMN / RAT / TAC / CELL selection assistance information table. Furthermore, the at least one processor 2102 may be configured to perform selection of the PLMN and the RAT combination based on the updated predefined PLMN / RAT / TAC / CELL selection assistance information table, for example, Table 1. In an implementation, the at least one processor 2102 may be configured to receive, from the network entity 111, at least one of the NAS or the AS signalling message indicating the removal of the at least one network slice from at least one of the default, configured, the allowed, or the partially allowed network slice list for which the congestion timer is running. Furthermore, the at least one processor 2102 may be configured to stop the congestion timer associated with the at least one removed network slice in response to receiving the at least one of the NAS or the AS signalling message. Additionally, the at least one processor 2102 may be configured to update the predefined PLMN / RAT / TAC / CELL selection assistance information table based on the received at least one of the NAS or AS signalling message.

[0198] In another implementation, the at least one processor 2102 may be configured to identify a transition of the UE to the second Cell (Cell 2) in the second TA (TA2). in an implementation, the UE 101 may be initially registered for at least one network slice available in first Cell in the first TA (TA1). In response to identifying the transition, initiate at least one predefined timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA (TA2). Further, the at least one processor 2102 may be configured to trigger a Protocol Data Unit (PDU) session release request message to de-register the at least one network slice based on the expiration of the initiated at least one predefined timer.

[0199] In an implementation, to initiate the at least one predefined timer for tracking the inactivity usage, the at least one processor is configured to predict, using one or more Artificial Intelligence / Machine Learning (AI / ML), the duration of the UE 101 in the second TA (TA2). The at least one processor is configured to initiate the predefined timer with the value identified based on predicted duration of the UE 101 in the second TA (TA2).

[0200] Fig. 22 illustrates an example diagram of a device implemented in the network entity 111 (e.g., a network), according to implementations of the present disclosure. The network entity 111, which corresponds to 5G Session Management (5GSM), may include, but not limited to, the gNB1 103, the gNB2 113, the 5G network 107, the eNB 105, and the MME 109, as discussed throughout this disclosure. The network entity 111 may include at least one at least one processor 2202 (generally referred to herein as the at least one processor 2202 ), a memory unit 2206 (e.g., memory, storage, etc.), and / or a communication unit 2204 (e.g., communicator or communication interface). Further, the network 2200 may also include the Cloud -RAN (C-RAN), a Central Unit (CU), a core Network (NW), a Distributed unit (DU), or the any other possible network (NW) entity. The communication unit 2204 may perform one or more functions for transmitting and receiving signals via a wireless channel.

[0201] As an example, the at least one processor 2202 may be a single processing unit or a number of units, all of which could include multiple computing units. The at least one processor 2202 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and / or any devices that manipulate signals based on operational instructions. Among other capabilities, the at least one processor 2202 is configured to fetch and execute computer-readable instructions and data stored in the memory. The at least one processor 2202 may include one or a plurality of processors. At this time, one or a plurality of processors 2202 may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The one or a plurality of processors 2202 may control the processing of the input data in accordance with a predefined (or alternatively, given) operating rule or artificial intelligence (AI) model stored in the non-volatile memory and the volatile memory, e.g., memory unit 2206. The predefined (or alternatively, given) operating rule or artificial intelligence model is provided through training or learning.

[0202] The memory 2206 may include any non-transitory computer-readable medium known in the art including, for example, volatile memory, such as Static Random Access Memory (SRAM) and Dynamic Random Access Memory (DRAM), and / or non-volatile memory, such as Read-Only Memory (ROM), erasable programmable ROM, flash memories, hard disks, optical disks, and / or magnetic tapes.

[0203] In an implementation, the at least one processor 2202 may be configured to track the TA of the UE 101.The UE 101 may be registered for at least one network slice available in the first Cell in the first TA (TA1) associated with the network entity. The at least one processor 2202 may be further configured to identify a transition of the UE from the first TA (TA1) to a second cell in a second TA (TA2) based on the tracking. Furthermore, the at least one processor 2202 may be configured to initiate at least one predefined timer, to track the inactivity usage corresponding to the at least one network slice not supported in the second TA (TA2).

[0204] In an implementation, to initiate the at least one predefined timer for tracking the inactivity usage, the at least one at least one processor 2202 may be configured to predict, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA (TA2). Further, the at least one at least one processor 2202 may be configured to initiate the predefined timer with a value identified based on predicted duration of the UE in the second TA (TA2). The at least one at least one processor 2202 may be configured to trigger a Protocol Data Unit (PDU) session release command message, to de-register the at least one network slice in response to detecting an expiration of the predefined timer.

[0205] In an advantageous aspect, when the UE 101 encounters congestion across all allowed slices, resulting in service denial despite being registered, the ability to perform the prioritized RAT and the PLMN selection becomes a critical advantage. The present disclosure provides various mechanism that empowers the UE 101 to dynamically evaluate alternative access options, such as switching from 5G NR to LTE or connecting to a partner PLMN, based on predefined priorities and real-time conditions. The selection process considers multiple parameters, including signal strength, cell load (e.g., available PRBs), CSI, and user-defined preferences. By leveraging such reselection strategies, the UE 101 can bypass congested network slices and access equivalent services through fallback RATs or PLMNs, ensuring uninterrupted connectivity. Such capability enhances service resilience, optimizes resource utilization, and improves user experience, especially in scenarios where slice-specific congestion would otherwise leave the UE idle and disconnected.

[0206] In another advantageous aspect, the present disclosure enables the UE 101 to maximize slice availability by considering non-3GPP access technologies, such as Wi-Fi, offers a significant boost to service continuity / accessibility and resource optimization. Traditionally, the network slice selection and availability are constrained to the 3GPP-defined access networks like 5G NR or LTE. However, by extending the network slice awareness and the selection capabilities to the non-3GPP domains, the UE 101 can tap into additional connectivity options when 3GPP access is limited, congested, or unavailable. As a result, the UE 101 can maintain active PDU sessions across diverse access networks, ensuring seamless service delivery for applications tied to specific network slices. The present disclosure not only enhances the user experience and mobility but also empowers users / operators to offload traffic intelligently, reduce core network strain, and deliver differentiated services across heterogeneous environments.

[0207] According to implementations, operations described herein as being performed by the UE 101, the network entity 111, the gNB1 103, the eNB 105, 5G network 107, the MME 109, the gNB2 113, the E-UTRAN 107, the E-UTRAN satellite 109, the network 1200, the at least one processor 1202, the communication unit 1204, the UE 1300, the at least one processor 1302 and / or the communication unit 1304 may be performed by processing circuitry. The term 'processing circuitry,' as used in the present disclosure, may refer to, for example, hardware including logic circuits; a hardware / software combination such as a processor executing software; or a combination thereof.　For example, the processing circuitry more specifically may include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, application-specific integrated circuit (ASIC), etc.

[0208] The various operations of the methods described above may be performed by any suitable device capable of performing the operations, such as the processing circuitry discussed above. For example, as discussed above, the operations of the methods described above may be performed by various hardware and / or software implemented in some form of hardware (e.g., processor, ASIC, etc.).

[0209] The software may comprise an ordered listing of executable instructions for implementing logical functions and may be embodied in any "processor-readable medium" for use by or in connection with an instruction execution system, apparatus, or device, such as a single or multiple-core processor or processor-containing system.

[0210] The blocks or operations of a method or algorithm and functions described in connection with implementations disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a tangible, non-transitory computer-readable medium (e.g., the memory 1206 and / or the memory 1306). A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a CD ROM, or any other form of storage medium known in the art.In some implementations, the at least one processor described herein may include one or more processors. In some implementations, all of the functions of the at least one processor described herein may be performed by a single processor. In other implementations, the functions of the at least one processor may be distributed among multiple processors (e.g., one processor performs a subset of the functions of the at least one processor while one or more other processors perform the remaining functions of the at least one processor.)

[0211] Implementations disclosed herein may be implemented using processing circuitry. For example, implementations disclosed herein may be implemented using at least one software program running on at least one hardware device and performing network management functions to control the elements.

[0212] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concepts as taught herein.

[0213] The drawings and the foregoing description give examples of implementations. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one example may be added to another example. For example, orders of processes described herein may be changed and are not limited to the manner described herein.

[0214] Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of implementations is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of implementations is at least as broad as given by the following claims.

[0215] Benefits, other advantages, and solutions to challenges have been described above with regard to specific examples. However, the benefits, advantages, solutions to challenges, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

Claims

1.A method for network slice management at a User Equipment (UE), in a wireless communication system, the method comprising:generating a request to access one or more services associated with at least one network slice;determining whether the at least one network slice associated with the one or more services is available in a current Public Land Mobile Network (PLMN) and an associated Radio Access Technology (RAT) based on a selection assistance information;based on the determination of whether the at least one network slice associated with the one or more services is available in the current PLMN and the associated RAT, selecting at least one of the current PLMN, a new PLMN, the current PLMN with a different RAT, the current PLMN with the associated RAT and a different cell; andtransmitting, to a network entity, a Non-Access Stratum (NAS) signalling message to access the one or more services.2.The method of claim 1, wherein generating the request to access the one or more services associated with the at least one network slice comprises:generating the request based on at least one of:receiving, from an application, an application request to access the one or more services;detecting an expiration of a congestion timer associated with the at least one network slice, and receiving the application request to access the one or more services associated with at least one network slice; ordetecting an addition of the at least one network slice, and receiving the application request to access the one or more services associated with at least one network slice.3.The method of claim 1, wherein the selection assistance information comprises:a list of PLMNs, and wherein each PLMN of the list of PLMNs is associated with a list of RATs, a list of Tracking Area Codes (TACs), a list of cells, a list of network slices, subscription information, slice mapping information, slice availability information, congestion information, and corresponding priority information.4.The method of claim 1, comprises updating the selection assistance information based on at least one of:a successful UE registration with the at least one network slice to access the one or more services based on the generated request;UE mobility information indicating a movement of the UE to a different PLMN, a different Tracking Area Identifier (TAI), a different Registration Area (RA), and / or a different cell;network slice information;a change in configured slice information based at least on one addition or removal of one or more network slices due to a subscription change or network congestion; ora failure in an UE access request to the at least one network slice.5.The method of claim 1, wherein selecting comprises:updating the selection assistance information based on network slice congestion and availability information; andselecting a first PLMN, a first RAT, a first Tracking Area Code (TAC), and a first cell based on the network slice congestion and availability information from the updated selection assistance information table.6.The method of claim 1, comprising:requesting, from the network entity, at least one of a default network slice, a configured network slice, or a partially allowed network slice in the NAS signalling message.7.The method of claim 1, wherein transmitting the NAS signalling message comprises at least one of:transmitting, to the network entity, an initial and mobility registration request message for accessing one or more registers associated with the network entity;transmitting, to the network entity, a Multi-Access (MA) PDU Establishment Request message; ortransmitting, to the network entity, a Protocol Data Unit (PDU) Establishment Request message to access the one or more services.8.A method for network slice management at a User Equipment (UE), in a wireless communication system, the method comprising:transmitting, to a network entity, a Non-Access Stratum (NAS) signalling message to access one or more services from at least one first network slice from a default network slice list, a configured network slice list, an allowed network slice list, or a partially allowed network slice list associated with a Public Land Mobile Network (PLMN), a Radio Access Technology (RAT), a Tracking Area Code (TAC), and a cell;receiving, from the network entity, a NAS signalling reject message indicating a congestion at the at least one first network slice associated with the PLMN, the RAT, the TAC, and the Cell and initiating a first congestion timer; andupdating a selection assistance information table;performing selection of the PLMN and the RAT based on the updated selection assistance information table;receiving, from the network entity, at least one of the NAS signalling message or an Access Stratum (AS) signalling message indicating a removal of at least one network slice from at least one of a default network slice list, a configured network slice list, an allowed network slice list, or a partially allowed network slice list associated with serving the PLMN or a Stand-alone Non-Public Network (SNPN) for which the first congestion timer is running;stopping the first congestion timer associated with the at least one removed network slice based on receiving the at least one of the NAS signalling message or the AS signalling message;determining whether at least one second congestion timer is running for one or more other PLMNs or a corresponding SNPN;stopping the at least one second congestion timer associated with the one or more other PLMNs or the corresponding SNPN;andupdating the selection assistance information table based on the received at least one of NAS signalling message or AS signalling message.9.A method for network slice management at a User Equipment (UE), in a wireless communication system, the method comprising:identifying a transition of the UE to a second cell in a second Tracking Area, wherein the UE is initially registered for at least one network slice available in a first cell in a first TA;based on identifying the transition, initiating at least one timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA; andtriggering a Protocol Data Unit (PDU) session release request message to de-register the at least one network slice based on an expiration of the initiated at least one timer.10.The method of claim 9, wherein initiating the at least one timer for tracking the inactivity usage comprises:predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA; andinitiating the timer with a value identified based on the predicted duration of the UE in the second TA.11.A method for network slice management at a network entity, in a wireless communication system, the method comprising:tracking a Tracking Area (TA) of a User Equipment (UE), wherein the UE is registered for at least one network slice available in a first cell in a first TA associated with the network entity;identifying a transition of the UE from the first TA to a second cell in a second TA based on the tracking;initiating at least one timer, for tracking an inactivity usage corresponding to the at least one network slice not supported in the second TA; andtriggering a Protocol Data Unit (PDU) session release command message for the at least one network slice based on detecting an expiration of the timer.12.The method of claim 11, wherein initiating the at least one timer for tracking the inactivity usage comprises:predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA; andinitiating the timer with a value identified based on the predicted duration of the UE in the second TA.13.A device for network slice management at a User Equipment (UE), in a wireless communication system, the device comprising:a memory; andone or more processors, communicably coupled with the memory, the one or more processors configured to:generate a request to access one or more services associated with at least one network slice;determine whether the at least one network slice associated with the one or more services is available in a current Public Land Mobile Network (PLMN) and an associated Radio Access Technology (RAT) based on a selection assistance information maintained by the UE;based on determining, select at least one of the current PLMN, a new PLMN, the current PLMN with a different RAT, the current PLMN with the associated RAT and a different cell; andtransmit, to a network entity, a Non-Access Stratum (NAS) signalling message to access the one or more services.14.The device of claim 13, wherein generating the request to access the one or more services associated with the at least one network slice comprises:generating the request based on at least one of:receiving, from an application, an application request to access the one or more services;detecting an expiration of a congestion timer associated with the at least one network slice, and receiving the application request to access the one or more services associated with the at least one network slice; ordetecting an addition of the at least one network slice, and receiving the application request to access the one or more services associated with the at least one network slice.15.The device of claim 13, wherein the selection assistance information comprises:a list of PLMNs, and wherein each PLMN of the list of PLMNs is associated with a list of RATs, a list of Tracking Area Codes (TACs), a list of cells, a list of network slices, subscription information, slice mapping information, slice availability information, congestion information, and corresponding priority information.16.The device of claim 13, wherein the one or more processors are configured to:update the selection assistance information based on at least one of:a successful UE registration with the at least one network slice to access the one or more services based on the generated request;UE mobility information indicating a movement of the UE to a different PLMN, a different Tracking Area Identifier (TAI), a different Registration Area (RA), a different cell;network slice information;a change in configured slice information based at least on one addition or removal of one or more network slices due to a subscription change or network congestion; ora failure in an UE access request to the at least one network slice.17.The device of claim 13, wherein the selection comprises:updating the selection assistance information based on network slice congestion and availability information; andselecting a first PLMN, a first RAT, a first TAC, and a first cell based on the network slice congestion and availability information from the updated selection assistance information table.18.The device of claim 13, wherein the one or more processors are configured to:request, from the network entity, at least one of a default network slice, a configured network slice, or a partially allowed network slice in the NAS signalling message.19.The device of claim 13, wherein the transmission of the NAS signalling message comprises at least one of:transmitting, to the network entity, an initial and mobility registration request message for accessing one or more registers associated with the network entity;transmitting, to the network entity, a Multi-Access (MA) PDU Establishment Request message; ortransmitting, to the network entity, a Protocol Data Unit (PDU) Establishment Request message to access the one or more services.20.A device for network slice management at a User Equipment (UE), in a wireless communication system, the device comprising:a memory; andone or more processors, communicably coupled with the memory, the one or more processors configured to:transmit, to a network entity, a Non-Access Stratum (NAS) signalling message to access one or more services from at least one first network slice from a default network slice list, a configured network slice list, an allowed network slice list, or a partially allowed network slice list associated with a Public Land Mobile Network (PLMN), a Radio Access Technology (RAT), a Tracking Area Code (TAC), and a cell;receive, from the network entity, a NAS signalling reject message indicating a congestion at the at least one first network slice associated with the PLMN, the RAT, the TAC, and the cell and initiating a first congestion timer;update a selection assistance information table;select the PLMN and the RAT based on the updated selection assistance information table;receive, from the network entity, at least one of the NAS signalling message or an Access Stratum (AS) signalling message indicating a removal of at least one network slice from at least one of a default network slice list, a configured network slice list, an allowed network slice list, or a partially allowed network slice list for which the first congestion timer is running;stop the first congestion timer associated with the at least one removed network slice based on receiving the at least one of the NAS signalling message or the AS signalling message;determine whether at least one second congestion timer is running for one or more other PLMNs or a corresponding SNPN,stop the at least one second congestion timer associated with the one or more other PLMNs or the corresponding SNPN; andupdate the selection assistance information table based on the received at least one of NAS or AS signalling message.21.A device for network slice management at a User Equipment (UE), in a wireless communication system, the device comprising:a memory; andone or more processors, communicably coupled with the memory, the one or more processors configured to:identify a transition of the UE to a second Cell in a second Tracking Area, wherein the UE is initially registered for at least one network slice available in a first Cell in a first TA;based on identifying the transition, initiate at least one timer for tracking an inactivity usage corresponding to at least one network slice not supported in the second TA; andtrigger a Protocol Data Unit (PDU) session release request message to de-register the at least one network slice based on an expiration of the initiated at least one timer.22.The device of claim 21, wherein initiating the at least one timer for tracking the inactivity usagecomprises:predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA; andinitiating the timer with a value identified based on the predicted duration of the UE in the second TA.23.A device for network slice management at a network entity, in a wireless communication system, the device comprising:a memory; andone or more processors, communicably coupled with the memory, the one or more processors configured to:track a Tracking Area (TA) of a User Equipment (UE), wherein the UE is registered for at least one network slice available in a first Cell in a first TA associated with the network entity;identify a transition of the UE from the first TA to a second cell in a second TA based on the tracking;initiate at least one timer to track an inactivity usage corresponding to the at least one network slice not supported in the second TA; andtrigger a Protocol Data Unit (PDU) session release command message for the at least one network slice based on detecting an expiration of the at least one timer.24.The device of claim 23, wherein initiating the at least one timer for tracking the inactivity usagecomprises:predicting, using one or more Artificial Intelligence / Machine Learning (AI / ML), a duration of the UE in the second TA; andinitiating the at least one timer with a value identified based on the predicted duration of the UE in the second TA.

Images