Handling an alternate s-nssai in a wireless network system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein is to provide a method and system for handling an S-NSSAI. The method includes receiving, by a UE (102), a PDU session release command from a session management function (SMF) apparatus (300A). The PDU session release command adds a primary S-NSSAI and omits addition of an alternate S-NSSAI, when the PDU session is of the SSC mode 1 or SSC mode 2. Further, receiving a PDU session modification command from the SMF apparatus (300A) to omit addition of the alternate S-NSSAI when the PDU session is of SSC mode 3. Further generating a PDU session establishment request to be transmitted to the SMF apparatus (300A) when the PDU session is of SSC mode 1 or SSC mode 2. In addition, generating a PDU session modification complete message to be the transmitted to the SMF apparatus (300A) when the PDU session is of SSC mode 3.

Description

HANDLING AN ALTERNATE S-NSSAI IN A WIRELESS NETWORK SYSTEM

[0001] The present disclosure is related to wireless network systems. More particularly, the present disclosure is related to a method and system for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in wireless network systems.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in“Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] Generally, according to a 3rd generation partnership project (3GPP) TS 24.501, if a User Equipment (UE) has indicated that the UE supports network slice replacement feature and a Access and Mobility Management Function (AMF) determines to provide the mapping information between a Single - Network Slice Selection Assistance Information (S-NSSAI) to be replaced and the alternate S-NSSAI to the UE, the network shall provide the UE with the alternate NSSAI. The alternate NSSAI is applicable for the registration area and is maintained separately for each type of access, i.e., 3GPP access or non-3GPP access. When the UE is updating its configuration or registering, the AMF sends the updated alternate NSSAI―which does not include the replaced S-NSSAI―as well as the corresponding alternate S-NSSAI to the UE if it finds that the replaced S-NSSAI is available.

[0009] The UE shall delete any stored alternate NSSAI for this PLMN and its equivalent PLMN(s) or this SNPN for the same access type when a new alternate NSSAI for a given public land mobile network (PLMN) or standalone (SNPN) is received and the new alternate NSSAI does not include any mapping information between the S-NSSAI to be replaced and the alternate S-NSSAI. The AMF offers the alternate NSSAI with Length of Alternate NSSAI contents set to 0 in the UE configuration update method or registration procedure if all the S-NSSAI(s) that were replaced in the alternate NSSAI are accessible. Additionally, the AMF gives the UE access to the specified and updated permitted NSSAI.

[0010] The AMF evaluates whether the S-NSSAI(s) should be included in the partially allowed NSSAI or the partially rejected NSSAI if the UE has indicated that the UE supports the partial network slicing feature and includes the S-NSSAI(s) in the requested NSSAI.

[0011] The network assigns the alternate S-NSSAI (such as S-NSSAI-2) and notifies the UE when the S-NSSAI is congested　or unavailable for operational reasons. However, a protocol must be in place to deal with the case where S-NSSAI becomes available once again and no alternate S-NSSAI is required. The issue gets more complex because it's likely that the slice's PDU sessions belong to separate SSC modes and that they can't be retained because the replaced S-NSSAI or the original S-NSSAI becomes available again. Thus, there is a need for the mechanism which considers the type of PDU session and provide appropriate indications to different network functions NFs and to the UE based on different conditions as described in this invention to handle gracefully moving back to original or replaced S-NSSAI from alternative S-NSSAI all the PDU sessions of the replaced S-NSSAI.

[0012] Thus, it is desired to address the above mentioned disadvantages or other shortcomings or at least provide a useful alternate.

[0013] The principal object of the embodiments herein is to disclose methods and systems for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in wireless network systems.

[0014] Yet another object of the embodiments herein is to proceed with the UCU and wait for the network response to the SM procedure.

[0015] Yet another objective of the embodiment herein is to proceed with the UCU and retry the 5GSM procedure.

[0016] Yet another objective of the embodiment herein is for the network to reject the 5GSM Procedure by using the DL NAS TRANSPORT message.

[0017] Yet another objective of the embodiment herein is the PDU session retention, with / without explicit the PDU modification command.

[0018] Yet another objective of the embodiment herein is the PDU session re-establishment.

[0019] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time.

[0020] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time, wherein User Plane Resource Activation is not requested for Always-on PDU in non-allowed areas.

[0021] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time, wherein user plane resources are active in non-allowed areas (locally released).

[0022] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time, wherein user plane resources are active in non-allowed areas (T3540 based Release).

[0023] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time, wherein user plane resources are active in non-allowed areas (using UL Data status).

[0024] Yet another objective of the embodiment herein is to disclose methods and systems for handling user plane activation request(s) / release(s) outside of network slice supported area or time, wherein user plane resources are active in non-allowed areas (block sending user plane data).

[0025] In one aspect, the objectives are achieved by providing a method for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system. The method includes establishing, by an access and mobility management function AMF apparatus, a PDU session with a user equipment (UE) over a primary S-NSSAI. Further, the method includes determining, by the AMF apparatus, whether the primary S-NSSAI is available and necessity　of the alternate S-NSSAI for the PDU session. Further, the method includes generating, by the AMF apparatus, a service operation message by adding the primary S-NSSAI while omitting (i.e. without including) the alternate S-NSSAI, when the primary S-NSSAI is available and the alternate S-NSSAI is not necessary　for the PDU session. In addition, the method includes transmitting, by the AMF apparatus, the service operation message to a session management function (SMF) apparatus associated with the UE. The primary S-NSSAI in the service operation message causes the PDU session to be transferred to the primary S-NSSAI.

[0026] In an embodiment, the method includes transmitting, by the AMF apparatus, a configuration update command to a user equipment (UE). The configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI.

[0027] In an embodiment, the configuration update command includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0028] In an embodiment, the service operation message is a Nsmf PDU Session Update SM Context service operation message.

[0029] In one aspect, the objectives are achieved by providing a method for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system. The method includes detecting, by a session management function (SMF) apparatus, a PDU session established over a primary S-NSSAI with a user equipment (UE). Further, the method includes determining, by the SMF apparatus, whether the PDU session needs to be re-established. Further, the method includes performing one of: transmitting the primary S-NSSAI by omitting (not including) the alternate S-NSSAI for the PDU session to the UE in response to determining that the PDU session associated with the UE need to be re-established. The primary S-NSSAI causes the PDU session to be transferred to the primary S-NSSAI. In addition, the method includes generating a non-access stratum (NAS) message including an indication that Alternate S-NSSAI is not applicable for the PDU session to the UE in response to determining that the PDU session associated with the UE need not to be re-established. The indication causes the PDU session to be transferred to the primary S-NSSAI.

[0030] In an embodiment, transmitting the primary S-NSSAI by omitting the alternate S-NSSAI for the PDU session to the UE includes determining whether the PDU session is of a session and service continuity (SSC) mode 1, a SSC mode 2, or a SSC mode 3. Further, the method includes performing one of: generating a PDU session release command by adding a primary S-NSSAI and omitting addition of the alternate S-NSSAI, when the PDU session is of the SSC mode 1 or the SSC mode 2 and transmitting the PDU session release command to a user equipment (UE), and generating a PDU session modification command by omitting addition of the alternate S-NSSAI when the PDU session is of the SSC mode 3 and transmitting the PDU session modification command to the UE.

[0031] In an embodiment, the method includes receiving, by the SMF apparatus, a PDU session establishment request from the UE, wherein the PDU session establishment request includes the primary S-NSSAI.

[0032] In an embodiment, the method includes determining, by the SMF apparatus, whether the PDU session needs to be retained. Further, the method includes generating, by the SMF apparatus, a PDU session modification command by omitting addition of the alternate S-NSSAI when the PDU session is retained. In addition, the method includes transmitting, by the SMF apparatus, the PDU session modification command to the UE.

[0033] In one aspect, the objectives are achieved by providing a method for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system. The method includes receiving, by a user equipment (UE), a PDU session release command from a session management function (SMF) apparatus. The PDU session release command adds a primary S-NSSAI and omits addition (does not include) of an alternate S-NSSAI, when the PDU session is of the SSC mode 1 or the SSC mode 2. Further, the method includes receiving, by the UE, a PDU session modification command from the SMF apparatus. The PDU session modification command omits (does not include) addition of the alternate S-NSSAI when the PDU session is of the SSC mode 3. Further, the method includes generating, by the UE, a PDU session establishment request to be transmitted to the SMF apparatus. The PDU session establishment request includes only the primary S-NSSAI when the PDU session is of the SSC mode 1 or the SSC mode 2. In addition, the method includes generating, by the UE, a PDU session modification complete message to be the transmitted to the SMF apparatus when the PDU session is of the SSC mode 3.

[0034] In an embodiment, the method includes receiving, by the UE, a configuration update command from an access and mobility management function (AMF) apparatus. The configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI.

[0035] In an embodiment, the configuration update command includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0036] In one aspect, the objectives are achieved by providing an access and mobility management function (AMF) apparatus for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system. The AMF apparatus includes a memory, a processor coupled to the memory, and a first S-NSSAI controller communicatively coupled to the memory and the processor. The first S-NSSAI controller establishes a PDU session with a user equipment (UE) over a primary S-NSSAI. Further, the first S-NSSAI controller determines whether the primary S-NSSAI is available and necessity　of the alternate S-NSSAI for the PDU session. Further, the first S-NSSAI controller generates a service operation message by adding the primary S-NSSAI while omitting the alternate S-NSSAI, when the primary S-NSSAI is available and the alternate S-NSSAI is not necessary　for the PDU session. In addition, the first S-NSSAI controller transmits the service operation message to a session management function (SMF) apparatus associated with the UE. The primary S-NSSAI in service operation message causes the PDU session to be transferred to the primary S-NSSAI.

[0037] In an embodiment, the first S-NSSAI controller transmits a configuration update command to a user equipment (UE). The configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI.

[0038] In an embodiment, the configuration update command includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0039] In an embodiment, the service operation message is a Nsmf PDU Session Update SM Context service operation message.

[0040] In one aspect, the objectives are achieved by providing a session management function (SMF) apparatus for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system. The SMF apparatus includes a memory, a processor, and a second S-NSSAI controller communicatively coupled to the memory and the processor. The second S-NSSAI controller detects a PDU session established over a primary S-NSSAI with a user equipment (UE). Further, the second S-NSSAI controller determines whether the PDU session needs to be re-established. Further, the second S-NSSAI controller transmits the primary S-NSSAI by omitting the alternate S-NSSAI for the PDU session to the UE in response to determining that the PDU session associated with the UE need to be re-established. The primary S-NSSAI causes the PDU session to be transferred to the primary S-NSSAI. In addition, the second S-NSSAI controller generates a non-access stratum (NAS) message including an indication that Alternate S-NSSAI is not applicable for the PDU session to the UE in response to determining that the PDU session associated with the UE need not to be re-established. The indication causes the PDU session to be transferred to the primary S-NSSAI.

[0041] In an embodiment, the second S-NSSAI controller determines whether the PDU session is of a session and service continuity (SSC) mode 1, a SSC mode 2, or a SSC mode 3. Further, the second S-NSSAI controller generates a PDU session release command by adding a primary S-NSSAI and omitting addition of the alternate S-NSSAI, when the PDU session is of the SSC mode 1 or the SSC mode 2, and transmits the PDU session release command to a user equipment (UE). In addition, the second S-NSSAI controller generates a PDU session modification command by omitting addition of the alternate S-NSSAI when the PDU session is of the SSC mode 3, and transmits the PDU session modification command to the UE.

[0042] In an embodiment, the second S-NSSAI controller receives a PDU session establishment request from the UE, wherein the PDU session establishment request includes only the S-NSSAI when the PDU session is of the SSC mode 1 or the SSC mode 2.

[0043] In an embodiment, the second S-NSSAI controller determines whether the PDU session needs to be retained. Further, the second S-NSSAI controller generates a PDU session modification command by omitting addition of the alternate S-NSSAI when the PDU session is retained. In addition, the second S-NSSAI controller transmits the PDU session modification command to the UE.

[0044] In one aspect, the objectives are achieved by providing a user equipment (UE) for handling collision between a single network slice selection assistance information (S-NSSAI) and an alternate S-NSSAI during a PDU session. The UE includes a memory, a processor, and a third S-NSSAI controller communicatively coupled to the memory and the processor. The third S-NSSAI controller receives a PDU session release command from a session management function (SMF) apparatus. The PDU session release command adds a primary S-NSSAI and omits addition of an alternate S-NSSAI, when the PDU session is of the SSC mode 1 or the SSC mode 2. Further, the third S-NSSAI controller receives a PDU session modification command from the SMF apparatus. The PDU session modification command omits addition of the alternate S-NSSAI when the PDU session is of the SSC mode 3. Further, the third S-NSSAI controller generates a PDU session establishment request to be transmitted to the SMF apparatus. The PDU session establishment request includes only the primary S-NSSAI when the PDU session is of the SSC mode 1 or the SSC mode 2. In addition, the third S-NSSAI controller generates a PDU session modification complete message to be the transmitted to the SMF apparatus when the PDU session is of the SSC mode 3.

[0045] In an embodiment, the third S-NSSAI controller receives a configuration update command from an access and mobility management function (AMF) apparatus. The configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI.

[0046] In an embodiment, the configuration update command includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0047] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications be made within the scope of the embodiments herein.

[0048] According to an embodiment of present disclosure, methods and apparatus are provided for handling an alternate Single Network Slice Selection Assistance Information (S-NSSAI) in a wireless network system.

[0049] These and other features, aspects, and advantages of the present embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings in which:

[0050] Fig. 1 is a sequence diagram that illustrates a user plane resource activation that is requested in a non-allowed area for always-on PDU according to the prior art;

[0051] Fig. 2 is a sequence diagram that illustrates user plane resources that are active in a non-allowed area according to the prior art;

[0052] Fig. 3 is a block diagram that illustrates a schematic of an AMF apparatus implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein;

[0053] Fig. 4 is a block diagram that illustrates a schematic of a SMF apparatus implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein;

[0054] Fig. 5 is a block diagram that illustrates a schematic of a user equipment (UE) implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein;

[0055] Fig. 6 is a sequence diagram that illustrates a user plane resource activation that is not requested for always-on PDU in non-allowed areas according to the embodiment as disclosed herein;

[0056] Fig. 7 is a sequence diagram that illustrates user plane resources active in non-allowed areas according to the embodiment as disclosed herein;

[0057] Fig. 8 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas based on T3540 based release according to the embodiment as disclosed herein;

[0058] Fig. 9 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas using UL data status according to the embodiment as disclosed herein;

[0059] Fig. 10 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas by blocking a sending user plane data according to the embodiment as disclosed herein;

[0060] Fig. 11 is a sequence diagram that illustrates a collision between the 5GSM procedure for the alternate S-NSSAI and a UCU removing of the alternate S-NSSAI according to the embodiment as disclosed herein;

[0061] Fig. 12 is a sequence diagram that illustrates proceeding with the UCU and waiting for a network response to a SM procedure according to the embodiment as disclosed herein;

[0062] Fig. 13 is a sequence diagram that illustrates proceeding with the UCU and a retry SM procedure according to the embodiment as disclosed herein;

[0063] Fig. 14 is a sequence diagram that illustrates rejection of the 5GSM procedure by using a DL NAS TRANSPORT message according to the embodiments as disclosed herein;

[0064] Fig. 15 is a sequence diagram that illustrates resending of the UCU according to the embodiments as disclosed herein;

[0065] Fig. 16 is a sequence diagram that illustrates handling removal of the alternate S-NSSAI according to the embodiments as disclosed herein;

[0066] Fig. 17A is a sequence diagram that illustrates a PDU session retention with an explicit PDU modification command according to the embodiments as disclosed herein;

[0067] Fig. 17B is a sequence diagram that illustrates a PDU session retention with an explicit PDU modification command according to the embodiments as disclosed herein;

[0068] Fig. 18A is a sequence diagram that illustrates the PDU session retention without the explicit PDU modification command according to the embodiments as disclosed herein;

[0069] Fig. 18B is a sequence diagram that illustrates the PDU session retention without the explicit PDU modification command according to the embodiments as disclosed herein;

[0070] Fig. 19 is a sequence diagram that illustrates a PDU session re-establishment according to the embodiments as disclosed herein;

[0071] Fig. 20 is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system according to the embodiment as disclosed herein;

[0072] Fig. 21 is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system in which a PDU session is re-established according to the embodiment as disclosed herein; and

[0073] Fig. 22A is flow diagrams that illustrates a method for handling an alternate S-NSSAI in a wireless network system based on a SSC mode according to the embodiment as disclosed herein.

[0074] Fig. 22B is flow diagrams that illustrates a method for handling an alternate S-NSSAI in a wireless network system based on a SSC mode according to the embodiment as disclosed herein.

[0075] It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawing. Further, those of ordinary skill in the art will appreciate that elements in the drawing are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimensions of some of the elements in the drawing may be exaggerated relative to other elements to help improve the understanding of aspects of the invention. Furthermore, the elements may have been represented in the drawing by conventional symbols, and the drawings may show only those specific details that are pertinent to the understanding of the embodiments of the invention so as not to obscure the drawing with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0076] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein refers to a non-exclusive "or" unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples are not to be construed as limiting the scope of the embodiments herein.

[0077] As is traditional in the field, embodiments are described and illustrated in terms of blocks that carry out a described function or functions. These blocks, which are referred to herein as managers, units, modules, hardware components, or the like, are physically implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits, and the like, and optionally be driven by firmware and software. The circuits, for example, be embodied in one or more semiconductor chips or on substrate supports such as printed circuit boards and the like. The circuits constituting a block be implemented by dedicated hardware or by a processor (e.g., one or more programmed microprocessors and associated circuitry) or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments be physically separated into two or more interacting and discrete blocks without departing from the scope of the proposed method. Likewise, the blocks of the embodiments be physically combined into more complex blocks without departing from the scope of the proposed method.

[0078] The accompanying drawings are used to help easily understand various technical features, and it is understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the proposed method is construed to extend to any alterations, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. are used herein to describe various elements, these elements are not to be limited by these terms. These terms are generally used to distinguish one element from another.

[0079] Fig. 1 is a sequence diagram that illustrates a user plane resource activation that is requested in a non-allowed area for always-on PDU according to the prior art. As shown, the sequence diagram includes a user equipment (UE) (102) in communication with an access and mobility management function (AMF) apparatus (104). In step 1, the UE (102) sends a UL non-access stratum (NAS) message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including Single Network Slice Selection Assistance Information (S-NSSAI) in a requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For instance, the DL NAS message may be a registration accept including S-NSSAI in a partially allowed NSSAI list. The partially allowed NSSAI list indicates a supported list of tracking areas (TAs) as TAI-1 and the current registration area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1.

[0080] In step 4, the PDU ID-1 is set as Always-on PDU session. The Always-on PDU session is a PDU session for which user-plane resources have to be established during every transition from 5GMM-IDLE mode to 5GMM-CONNECTED mode. The UE (102) requests a PDU session to be established as an always-on PDU session based on indication from upper layers and the network decides whether a PDU session is established as an always-on PDU session. In step 5, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request by including the Always on PDU session requested for PDU ID-1 / S-NSSAI. In step 6, the AMF apparatus (104) sends the DL NAS message to the UE (102). For example, the DL NAS message may be a PDU session establishment accept by including Always-on PDU session indication for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2. In step 8, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a service request by including UL Data status IE with uplink data status set to true for Always-on PDU ID-1 / S-NSSAI. In step 9, the TAI-2 is not part of the supported TAI list of partially allowed NSSAI list i.e. for S-NSSAI. However, the UE (102) requests user plane resource activation for always-on PDU ID-1 / S-NSSAI.

[0081] Fig. 2 is a sequence diagram that illustrates user plane resources that are active in a non-allowed area according to the prior art. As shown, the sequence diagram includes a user equipment (UE) (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including S-NSSAI in a requested NSSAI list. In step 2, the AMF apparatus (104) sends the DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in a partially allowed NSSAI list, which indicates a supported list of TAs as TAI-1. The current registration area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in the TAI-1. In step 4, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU Session Establishment request for PDU ID-1 / S-NSSAI. In step 5, the AMF apparatus (104) sends the DL NAS message to the UE (102). For example, the DL NAS message may be a PDU Session Establishment Accept for PDU ID-1 / S-NSSAI. In step 6, the user plane resources are activated for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2 in a 5GMM-CONNECTED mode. In step 8, the user plane resources continue to be active even though TAI-2 is not part of the supported TAI list of the partially allowed NSSAI list.

[0082] In the existing art, if the UE (102) has indicated that it supports the partial network slice feature and includes the S-NSSAI(s) in the requested NSSAI, the AMF apparatus (104) determines the S-NSSAI(s) to be included in the partially allowed NSSAI or the partially rejected NSSAI. If the S-NSSAI is congested or not available due to operation reasons, then network assigns the alternate S-NSSAI (e.g. S-NSSAI-2) and provides this information to the UE (102). However when S-NSSAI is available again and there is no need for alternate S-NSSAI, there is a need for a procedure to handle this situation. The problem becomes more complicated as the PDU session of the slice may belong to different SSC modes and it may not be possible to retain those PDU sessions.

[0083] The solution to eliminate the mapping between Alternate S-NSSAI and the original / replaced S-NSSAI is introduced in the proposed solution. For the original slice to be instantiated, a number of criteria need to be considered, including the kind of PDU session and the SMF's judgment of whether the PDU session has to be preserved or re-established. Slicing is a crucial 5GS feature. In order to facilitate switching to an alternate S-NSSAI, it is necessary to first switch to the original S-NSSAI.　This invention describes the process for doing so.

[0084] In an embodiment, the S-NSSAI may also be referred to as a 'primary S-NSSAI'. Further, the S-NSSAI-2 may be referred to as the 'alternate S-NSSAI'.

[0085] Fig. 3 is a block diagram that illustrates a schematic of the AMF apparatus (104) implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein. As shown, the electronic device (300) includes a processor (302), a memory (304), an I / O interface (306), and a first S-NSSAI controller (308).

[0086] The processor (302) communicates with the memory (304), the I / O interface (306), and the first S-NSSAI controller (308). The processor (302) is configured to implement instructions stored in the memory (304) and to perform various methodes. The processor (302) may include one or a plurality of methodors. It is a general-purpose processor such as a central methoding unit (CPU), an application processor (AP), or the like, a graphics-only methoding unit such as a graphics methoding unit (GPU), a visual methoding unit (VPU), and / or an Artificial Intelligence (AI) dedicated processor such as a neural methoding unit (NPU).

[0087] The electronic device (300) has a memory (304) that is accessed through the processor (302). The memory (304) is not restricted to volatile or non-volatile memory and may consist of one or more computer-readable storage media. Further, the memory (304) may contain non-volatile storage elements such as magnetic hard discs, optical discs, floppy discs, flash memories, EPROM, or EEPROM memories.

[0088] The I / O interface (306) transmits information between the memory (304) and external peripheral devices. The peripheral devices are the input-output devices associated with the electronic device (300). Furthermore, the first S-NSSAI controller (308) communicates with the I / O interface (306) and the memory (304). The first S-NSSAI controller (308) is an innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, micromethodors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0089] The AMF apparatus (104) is responsible for managing various aspects related to the connection and mobility of the UE (102). The AMF apparatus (104) manages the registration of the UE (102) by ensuring that it is authorized to access the wireless network system. The AMF apparatus (104) manages the connection setup, modification, and release processes between the UE (102) and the wireless network. The AMF apparatus (104) may also handle mobility-related signaling, including handover procedures when the UE (102) moves from one cell to another. It manages tracking area updates and maintains the location information associated with the UE (102).

[0090] Over a primary　S-NSSAI, the UE (102) and the first S-NSSAI controller (308) establish a PDU session. Additionally, the first S-NSSAI controller (308) establishes if the alternate S-NSSAI is required for the PDU session and whether the primary S-NSSAI is accessible. Furthermore, when the primary S-NSSAI is available and the alternate S-NSSAI is not required for the PDU session, the first S-NSSAI controller (308) creates a service operation message by adding the primary S-NSSAI and omitting (does not include) the alternate S-NSSAI. Additionally, the service operation message is sent to a session management function (SMF) apparatus (300A) connected to the user equipment (102) via the first S-NSSAI controller (308). The primary S-NSSAI in service operation message causes the PDU session to be transferred to the primary S-NSSAI. The UE (102) receives a configuration update command from the AMF APPARATUS (104). The configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI. The configuration command also includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0091] The PDU (packet data unit) session is a logical connection between the UE (102) and the AMF apparatus (104) / SMF apparatus (300A), enabling the transfer of data packets. The S-NSSAI is used by the wireless network system to select the appropriate network slice for a particular service of the UE (102). This ensures that the service requirements of the UE (102) are met by the network slice's characteristics. Different services and applications have varying requirements for bandwidth, latency, reliability, etc. By using S-NSSAI, the network can allocate resources more efficiently and provide tailored services for each type of application. When the UE (102) registers with the wireless network, it includes its required S-NSSAI(s) in the registration request. The AMF APPARATUS (104) uses this information to select the appropriate network slice. When a session is established or modified, the S-NSSAI helps the SMF apparatus (300A) allocate the correct resources and route the traffic through the appropriate user plane functions (UPFs).

[0092] The alternate S-NSSAI provides a mechanism for fallback or alternate network slice options when the primary S-NSSAI requested by the UE (102) is not available or cannot be provided by the wireless network. When the UE (102) requests the primary S-NSSAI during registration or session establishment, the wireless network may not always be able to fulfill this request due to resource constraints or other reasons. The alternate S-NSSAI provides fallback options to ensure that the UE (102) may still receive an appropriate level of service. The alternate S-NSSAI ensures that the UE (102) may continue to receive service even if the preferred network slice is unavailable. This is critical for maintaining a seamless user experience and preventing service disruptions.

[0093] Fig. 4 is a block diagram that illustrates a schematic of the SMF apparatus (300A) implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein. As shown, the SMF apparatus (300A) includes the processor (302), the memory (304), the I / O interface (306), and a second S-NSSAI controller (310).

[0094] The SMF apparatus (300A) is responsible for managing session-related functions and ensuring seamless data connectivity for the UE (102). The SMF apparatus (300A) manages the establishment, modification, and release of PDU (Packet Data Unit) sessions. It allocates IP addresses to the UE (102) and handles the assignment of user plane resources. The SMF apparatus (300A) determines the routing of data traffic through the appropriate user plane functions. It coordinates with the AMF apparatus (104) for signaling and control plane functions. The SMF apparatus (300A) may also manage handovers and ensures session continuity when the UE (102) move between different cells or networks.

[0095] The second S-NSSAI controller (310) detects a PDU session established over a primary S-NSSAI with the UE (102). Further, the second S-NSSAI controller (310) determines whether the PDU session needs to be re-established. Further, the second S-NSSAI controller (310) transmits the primary S-NSSAI by omitting the alternate S-NSSAI for the PDU session to the UE (102) in response to determining that the PDU session associated with the UE (102) need to be re-established. The primary S-NSSAI causes the PDU session to be transferred to the primary S-NSSAI. In addition, the second S-NSSAI controller (310) generates a non-access stratum (NAS) message including an indication that Alternate S-NSSAI is not applicable for the PDU session to the UE (102) in response to determining that the PDU session associated with the UE (102) need not to be re-established. The indication causes the PDU session to be transferred to the primary S-NSSAI.

[0096] When it is determined that the PDU session associated with the UE (102) has to be re-established, the second S-NSSAI controller (310) decides if the PDU session is of a session and service continuity (SSC) mode 1, an SSC mode 2, or an SSC mode 3. Additionally, whether the PDU session is of SSC mode 1 or SSC mode 2, the second S-NSSAI controller creates a PDU session release command　by adding a primary S-NSSAI and ignoring the insertion of the alternate S-NSSAI. The PDU session release command is then transmitted to the UE (102). In addition, the second S-NSSAI controller generates a PDU session modification command by omitting addition of the alternate S-NSSAI when the PDU session is of the SSC mode 3, and transmits the PDU session modification command to the UE (102).

[0097] The SSC modes define how user sessions are maintained and managed, especially during mobility events like handovers or changes in the wireless network. In SSC Mode 1, the PDU session remains established and unchanged as the UE (102) moves across different cells or network areas. The session context, including IP address and QoS settings, is preserved throughout the session. In SSC Mode 2, the PDU session may be modified during mobility events. This includes changes in user plane function (UPF) and potential rerouting of the session. The IP address assigned to the UE (102) remains unchanged, ensuring that ongoing connections are not disrupted. In SSC Mode 3, the PDU session can be released and re-established during mobility events. This means that the IP address may change, and a new session context is created.

[0098] The necessity to retain the PDU session is likewise decided by the second S-NSSAI controller (310). When the PDU session is maintained, the second S-NSSAI controller (310) then creates a PDU session modification command by leaving out the inclusion of the alternate S-NSSAI and sends it to the UE (102).

[0099] Fig. 5 is a block diagram that illustrates a schematic of the UE (102) implemented to carry out the disclosed subject matter according to the embodiment as disclosed herein. As shown, the UE (102) includes the processor (302), the memory (304), the I / O interface (306), and a third S-NSSAI controller (312). For example, the UE (102) may include, but not limited to a smartphone, personal computer (PC), tablet, personal device assistant (PDA), and the like.

[0100] The SMF apparatus (300A) sends a PDU session release command to the third S-NSSAI controller (310). When the PDU session is of SSC mode 1 or SSC mode 2, the PDU session release command adds a main S-NSSAI and omits adding an alternate S-NSSAI. Additionally, the SMF apparatus (300A) sends a PDU session modification command to the third S-NSSAI controller (310). When the PDU session is in SSC mode 3, the alternate S-NSSAI is not added by the PDU session modification command. Additionally, a PDU session setup request is generated by the third S-NSSAI controller (310) and sent to the SMF apparatus (300A). When the PDU session is of SSC mode 1 or SSC mode 2, the PDU session establishment request simply contains the primary S-NSSAI. Furthermore, when the PDU session is in SSC mode 3, the third S-NSSAI controller (310) creates a PDU session modification complete message that has to be sent to the SMF apparatus (300A).

[0101] Additionally, the UE (102), through the third S-NSSAI controller (310), gets a configuration update command. A mapping between the primary S-NSSAI and the alternate S-NSSAI is absent from the configuration update command, which contains the alternate S-NSSAI. The alternate S-NSSAI, in which the length of the alternate S-NSSAI contents has been set to 0, may also be included in the configuration update command.

[0102] The following abbreviations and definitions have been disclosed herein:

[0103] AMF: Access and Mobility Management Function

[0104] SoR: Steering of Roaming

[0105] SoR - AF: Steering of Roaming - Application Function

[0106] S-NSSAI: Single Network (i.e., Network function; for example, AMF / SMF / UPF) Slice Selection Assistance Information

[0107] NSSAI: Network (i.e., Network function, for example, AMF / SMF / UPF) Slice Selection Assistance Information

[0108] UE: User Equipment

[0109] PCF: Policy Control Function

[0110] NF: Network (i.e., Network function, for example, AMF / SMF / UPF) Function

[0111] UDM: Unified Data Management

[0112] 3GPPA: 3GPP Access

[0113] N3GPPA: Non 3GPP Access

[0114] TA: Tracking Area

[0115] RA: Registration Area

[0116] SoR-CMCI: Steering of roaming connected mode control information

[0117] SoR: Steering of Roaming

[0118] SR: Service Request

[0119] TAI: Tracking Area Identity

[0120] TAC: Tracking Area Code

[0121] CAG: Closed Access Group

[0122] 3GPP: 3rd Generation Partnership Project

[0123] AMF: Access and Mobility Function

[0124] GCI: Global Cell Id

[0125] NSSAI: Network (i.e., Network function, for example, AMF / SMF / UPF) Slice Selection Assistance Information

[0126] CAG: Closed Access Group

[0127] OPLMN: Operator Preferred PLMN

[0128] PLMN: Public Land Mobile Network (i.e., Network function, for example, AMF / SMF / UPF)

[0129] NS-AoS: Network Slice Area of Service

[0130] In this embodiment the term EMM sublayer states are at least one of the below:

[0131] 1) EMM-NULL

[0132] 2) EMM-DEREGISTERED

[0133] a) EMM-DEREGISTERED.NORMAL-SERVICE

[0134] b) EMM-DEREGISTERED.LIMITED-SERVICE

[0135] c) EMM-DEREGISTERED.ATTEMPTING-TO-ATTACH

[0136] d) EMM-DEREGISTERED.PLMN-SEARCH

[0137] e) EMM-DEREGISTERED.NO-IMSI

[0138] f) EMM-DEREGISTERED.ATTACH-NEEDED

[0139] g) EMM-DEREGISTERED.NO-CELL-AVAILABLE

[0140] h) EMM-DEREGISTERED.eCALL-INACTIVE

[0141] 3) EMM-REGISTERED-INITIATED

[0142] 4) EMM-REGISTERED

[0143] a) EMM-REGISTERED.NORMAL-SERVICE

[0144] b) EMM-REGISTERED.ATTEMPTING-TO-UPDATE

[0145] c) EMM-REGISTERED.LIMITED-SERVICE

[0146] d) EMM-REGISTERED.PLMN-SEARCH

[0147] e) EMM-REGISTERED.UPDATE-NEEDED

[0148] f) EMM-REGISTERED.NO-CELL-AVAILABLE

[0149] g) EMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM

[0150] h) EMM-REGISTERED.IMSI-DETACH-INITIATED

[0151] 5) EMM-DEREGISTERED-INITIATED

[0152] 6) EMM-TRACKING-AREA-UPDATING-INITIATED

[0153] 7) EMM-SERVICE-REQUEST-INITIATED

[0154] The term 5GMM sublayer states in this embodiment are at least one of the below:

[0155] 1) 5GMM-NULL

[0156] 2) 5GMM-DEREGISTERED

[0157] a) 5GMM-DEREGISTERED.NORMAL-SERVICE

[0158] b) 5GMM-DEREGISTERED.LIMITED-SERVICE

[0159] c) 5GMM-DEREGISTERED.ATTEMPTING-REGISTRATION

[0160] d) 5GMM-DEREGISTERED.PLMN-SEARCH

[0161] e) 5GMM-DEREGISTERED.NO-SUPI

[0162] f) 5GMM-DEREGISTERED.NO-CELL-AVAILABLE

[0163] g) 5GMM-DEREGISTERED.eCALL-INACTIVE

[0164] h) 5GMM-DEREGISTERED.INITIAL-REGISTRATION-NEEDED

[0165] 3) 5GMM-REGISTERED-INITIATED

[0166] 4) 5GMM-REGISTERED

[0167] a) 5GMM-REGISTERED.NORMAL-SERVICE

[0168] b) 5GMM-REGISTERED.NON-ALLOWED-SERVICE

[0169] c) 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE

[0170] d) 5GMM-REGISTERED.LIMITED-SERVICE

[0171] e) 5GMM-REGISTERED.PLMN-SEARCH

[0172] f) 5GMM-REGISTERED.NO-CELL-AVAILABLE

[0173] g) 5GMM-REGISTERED.UPDATE-NEEDED

[0174] 5) 5GMM-DEREGISTERED-INITIATED

[0175] 6) 5GMM-SERVICE-REQUEST-INITIATED

[0176] 5GMM-IDLE mode: In this specification, if the term is used standalone, the UE (102) in 5GMM-IDLE mode means the UE (102) can be either in 5GMM-IDLE mode over 3GPP access or in 5GMM-IDLE mode over non-3GPP access.

[0177] 5GMM-CONNECTED mode: In this specification, if the term is used standalone, the UE (102) in 5GMM-CONNECTED mode means the UE (102) can be either in 5GMM-CONNECTED mode over 3GPP access or in 5GMM-CONNECTED mode over non-3GPP access.

[0178] 5GMM-IDLE mode over 3GPP access: The UE (102) is in 5GMM-IDLE mode over 3GPP access when no N1 NAS signalling connection between the UE (102) and Network (i.e., Network function e.g., AMF / SMF / UPF) over 3GPP access exists. The term 5GMM-IDLE mode over 3GPP access used in the present document corresponds to the term CM-IDLE state for 3GPP access used in 3GPP　TS　23.501.

[0179] 5GMM-CONNECTED mode over 3GPP access: The UE (102) is in 5GMM-CONNECTED mode over 3GPP access when an N1 NAS signalling connection between the UE (102) and Network (i.e., Network function e.g., AMF / SMF / UPF) over 3GPP access exists. The term 5GMM-CONNECTED mode over 3GPP access used in the present document corresponds to the term CM-CONNECTED state for 3GPP access used in 3GPP　TS　23.501.

[0180] Partially Allowed NSSAI: Indicating the S-NSSAIs values the UE (102) could use in the Serving PLMN or SNPN in some of the TAs in the current Registration Area. Each S-NSSAI in the Partially Allowed NSSAI is associated with a list of TAs where the S-NSSAI is supported.

[0181] Partially rejected NSSAI: Indicating the S-NSSAI(s) is rejected by the network in some TA(s) but not all TAs of the registration area. Each S-NSSAI in the partially rejected NSSAI is associated with a list of TAs where the S-NSSAI is rejected.

[0182] Network Slice Area of Service: The area where the UE (102) can access and get service of a particular network slice as more than zero resources are allocated to the network slice in the NG-RAN cells.

[0183] S-NSSAI location availability information: The S-NSSAI location availability information sent to the UE (102) includes, for each applicable S-NSSAI (optionally of the Configured NSSAI), Location information indicating the cells of TAs in the RA where the related S-NSSAI is available (or supported) if the S-NSSAI is not available (or not supported) in all the cells of the TA. This information can also include the cells where the related / respective S-NSSAI is not supported. The cell can be identified using a cell ID or any other identifier which can identify a given cell or group of cells.

[0184] Always-on PDU session: A PDU session for which user-plane resources have to be established during every transition from 5GMM-IDLE mode to 5GMM-CONNECTED mode. The UE (102) requests a PDU session to be established as an always-on PDU session based on indication from upper layers and the network decides whether a PDU session is established as an always-on PDU session.

[0185] Alternate NSSAI: A list of mapping information between the S-NSSAI to be replaced and the alternate S-NSSAI.

[0186] Fig. 6 is a sequence diagram that illustrates a user plane resource activation that is not requested for always-on PDU in non-allowed areas according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends a UL NAS message to the AMF apparatus (104) For example, the UL NAS message may be a registration request message including S-NSSAI in requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in the partially allowed NSSAI list, indicating supported list of TAs as TAI-1. The current registration Area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1. In step 4, the PDU ID-1 is set as Always-on PDU. In step 5, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the PDU session establishment request includes Always on PDU session requested for PDU ID-1 / S-NSSAI.

[0187] In step 6, the AMF apparatus (104) sends the DL NAS message to the UE (102). For example, the DL NAS message may be a PDU session establishment accept by including Always-on PDU session indication for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2. In step 8, the TAI-2 is not part of the supported TAI list of the partially allowed NSSAI list for S-NSSAI. In step 9, the user plane resources should not be requested for Always-on PDU ID-1 / S-NSSAI. In step 10, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may include a service request by including uplink (UL) Data status IE with pending uplink data status set to false (i.e. value zero) for Always-on PDU ID-1 / S-NSSAI (for example, indicate the uplink data is not pending for this PDU session). In step 11, when the UE (102) moves to TAI-1 (where S-NSSAI is supported), the UE (102) sends a UL NAS message (e.g., Service request) by including UL Data status IE with pending uplink data status set to TRUE (for example, value 1) for Always-on PDU ID-1 / S-NSSAI (for example, indicate the uplink data is pending for this PDU session) optionally for any idle to connected mode transition.

[0188] Fig. 7 is a sequence diagram that illustrates user plane resources active in non-allowed areas according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including S-NSSAI in requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in the partially allowed NSSAI list, indicating supported list of TAs as TAI-1 and current Registration Area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1. In step 4, the UE (102) sends the UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request for PDU ID-1 / S-NSSAI. In step 5, the AMF apparatus (104) sends the DL NAS message to the UE (102). For example, the DL NAS message may be a PDU Session Establishment Accept for PDU ID-1 / S-NSSAI.

[0189] In step 6, the user plane resources are activated for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2 in 5GMM-CONNECTED mode. In an embodiment, in step 8, if no other PDUs are active, the UE (102) shall locally release NAS Signalling connection. In an embodiment, in step 9, the UE (102) shall locally release the NAS signalling connection. In an embodiment, in step 10, the UE (102) shall consider the user plane resources of the PDU session which is not allowed in a given area (based on partially allowed NSSAI list or NS_AoS) as deactivated or it should perform a local release of the user plane resources of the respective PDU session. In step 11, when the UE (102) moves to TAI-1 (where S-NSSAI is supported and the UE (102) has uplink user data to be sent over PDU ID-1 / S-NSSAI), the UE (102) sends the UL NAS message (e.g., Service request) by including UL Data status IE with uplink data status set to TRUE for PDU ID-1 / S-NSSAI optionally for any idle to connected mode transition.

[0190] Fig. 8 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas based on T3540 based release according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including S-NSSAI in requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in the partially allowed NSSAI list, indicating supported list of TAs as TAI-1. The current registration area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1. In step 4, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request for PDU ID-1 / S-NSSAI. In step 5, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a PDU session establishment accept for PDU ID-1 / S-NSSAI.

[0191] In step 6, the user plane resources are activated for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2 in 5GMM-CONNECTED mode. In one embodiment, in step 8, if no other PDUs are active, the UE (102) shall start T3540 timer. Upon timer expiry, NAS signalling connection is released. In an embodiment, in step 9, the UE (102) shall start T3540 timer. Upon timer expiry, the NAS signalling connection is released. In step 10, when the UE (102) moves to TAI-1 (where S-NSSAI is supported and the UE (102) has uplink user data to be sent over PDU ID-1 / S-NSSAI), the UE (102) sends a UL NAS message (e.g. Service request) by including UL Data status IE with uplink data status set to TRUE for PDU ID-1 / S-NSSAI optionally for any idle to connected mode transition.

[0192] Fig. 9 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas using UL data status according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including S-NSSAI in requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in the partially allowed NSSAI list, indicating supported list of TAs as TAI-1. The current registration area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1. In step 4, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request for PDU ID-1 / S-NSSAI. In step 5, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a PDU Session Establishment Accept for PDU ID-1 / S-NSSAI.

[0193] In step 6, the user plane resources are activated for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2 in 5GMM-CONNECTED mode. In step 8, the UE (102) requests the AMF apparatus (104) to release user plane resources of PDU ID-1 / S-NSSAI by sending a NAS message to network and indicating to release the user plane resources of the PDU ID-1 / S-NSSAI. For example in service request or registration request message by including an IE like uplink data status IE / or new IE etc. In step 9, the AMF apparatus (104) triggers user plane resource release of PDU-1 / S-NSSAI. In step 10, when the UE (102) moves to TAI-1 (where S-NSSAI is supported and the UE (102) has uplink user data to be sent over PDU ID-1 / S-NSSAI), the UE (102) sends UL NAS message (e.g. Service request) by including UL Data status IE with uplink data status set to TRUE for PDU ID-1 / S-NSSAI optionally for any idle to connected mode transition.

[0194] Fig. 10 is a sequence diagram that illustrates user plane resources that are active in non-allowed areas by blocking a sending user plane data according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). In step 1, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a registration request message including S-NSSAI in requested NSSAI list. In step 2, the AMF apparatus (104) sends a DL NAS message to the UE (102). For example, the DL NAS message may be a registration accept including S-NSSAI in the partially allowed NSSAI list, indicating supported list of TAs as TAI-1. The current registration area includes TAI-1 and TAI-2. TAI-2 is not supporting S-NSSAI. In step 3, the UE (102) is in TAI-1. In step 4, the UE (102) sends a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request for PDU ID-1 / S-NSSAI. In step 5, the AMF apparatus (104) entity sends a DL NAS message to the UE (102). For example, the DL NAS message may be a PDU session establishment accept for PDU ID-1 / S-NSSAI.

[0195] In step 6, the user plane resources are activated for PDU ID-1 / S-NSSAI. In step 7, the UE (102) moves to TAI-2 in 5GMM-CONNECTED mode. In step 8, the UE (102) shall block sending user plane data over PDU ID-1 / S-NSSAI. The UE (102) shall not send any user plane data using the user plane resource of PDU ID-1 / S-NSSAI. The UE (102) shall consider the respective user plane resources as deactivated and wait for the AMF apparatus (104) to release the user plane resources. Additionally, in step 9, if the AMF apparatus (104) has not released the user plane resources for PDU ID-1 / S-NSSAI on TAI-2, but the UE (102) has moved to TAI-1 (where S-NSSAI is supported), the UE (102) shall start sending user data over the corresponding user plane resources for PDU ID-1 / S-NSSAI. Optionally, in step 10, when the UE (102) moves to TAI-1 (where S-NSSAI is supported and the UE (102) has uplink user data to be sent over PDU ID-1 / S-NSSAI), the UE (102) sends UL NAS message (e.g. Service request) by including UL Data status IE with uplink data status set to TRUE for PDU ID-1 / S-NSSAI optionally for any idle to connected mode transition.

[0196] In an embodiment, the TAI is used for illustration based on which the UE determines it is in non-allowed area. The TAI is used only for illustration purpose. This may be any geographical area which can be determined for e.g., using latitudes / longitudes, NS-AoS, Area of service, group of cells(s), group of TAI(s), CAG ID(s), area of interest etc.

[0197] In an embodiment, the partially allowed NSSAI list is used for illustration based on which it is determined if the UE (102) is outside the allowed areas / allowed time duration. However, this allowed boundary information may be from any of the following: Partially Allowed NSSAI list, or partially rejected NSSAI list, or S-NSSAI location validity information, or S-NSSAI time validity information.

[0198] In an embodiment, the S-NSSAI location validity information list is used for illustration based on which it is determined if the UE (102) is outside the allowed Areas / allowed time duration. However, the allowed boundary information can be determined from any of the following: Partially Allowed NSSAI list, or partially rejected NSSAI list, or S-NSSAI location validity information, or NS-AoS, or S-NSSAI time validity information.

[0199] In an embodiment herein, the Partially Allowed NSSAI indicates the S-NSSAIs values the UE (102) could use in the Serving PLMN or SNPN in some of the TAs in the current Registration Area. Each S-NSSAI in the Partially Allowed NSSAI is associated with a list of TAs where the S-NSSAI is supported.

[0200] In an embodiment, the NSSAI is the area where the UE (102) may access and get service of a particular network slice as more than zero resources are allocated to the network slice in the NG-RAN cells.

[0201] In an embodiment, the S-NSSAI location availability information sent to the UE (102) includes, for each applicable S-NSSAI of the Configured NSSAI, Location information indicating the cells of TAs in the RA where the related S-NSSAI is available if the S-NSSAI is not available in all the cells of a Tracking Area (TA).

[0202] In an embodiment, an Alternate NSSAI is a list of mapping information between the S-NSSAI to be replaced and the alternate S-NSSAI.

[0203] In an embodiment, the partially rejected NSSAI Indicates the S-NSSAI(s) is rejected by the network in some TA(s) but not all TAs of the registration area. Each S-NSSAI in the partially rejected NSSAI is associated with a list of TAs where the S-NSSAI is rejected.

[0204] In an embodiment, On-demand S-NSSAI is the S-NSSAI that the UE (102) is allowed to be registered with the network only when this S-NSSAI is used by the UE (102) to establish a PDU session for user data transmission.

[0205] In an embodiment, when a PDU session establishment accept is received with only S-NSSAI and not including the Alternate S-NSSAI, the UE (102) shall consider the PDU session is established for S-NSSAI. Additionally, the UE (102) shall delete the corresponding Alternate NSSAI mapping. At the same time, the AMF apparatus (104) sends a configuration update command or any other NAS message by including Alternate NSSAI which excludes the mapping information between S-NSSAI and S-NSSAI-2 or by including alternate NSSAI with Length of Alternate NSSAI contents set to 0. This removes the mapping of S-NSSAI and the alternate S-NSSAI. The UE (102) deletes the corresponding alternate NSSAI mapping and waits for the AMF apparatus (104) to respond to the SM procedure for the S-NSSAI.

[0206] In an embodiment, the User-plane resources is a resources established between the UE (102) and a User Plane Function (UPF) (1704). The user-plane resources includes of one of the following:

[0207] ● user plane radio bearers via the Uu reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for 3GPP access;

[0208] ● IPsec tunnels via the NWu reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for untrusted non-3GPP access;

[0209] ● IPsec tunnels via the NWt reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for trusted non-3GPP access used by the UE (102);

[0210] ● a layer-2 connection via the Yt reference point, a layer-2 or layer-3 connection via the Yw reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for trusted non-3GPP access used by the N5CW device;

[0211] ● W-UP resources via Y4 reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for wireline access used by the 5G-RG; and

[0212] ● L-W-UP resources via Y5 reference point, a tunnel via the N3 reference point and a tunnel via the N9 reference point (if any) for wireline access used by the FN-RG.

[0213] Accordingly, the embodiment is for a generic UE configuration update procedure: The following parameters are supported by the generic UE configuration update procedure without the need to request the UE (102) to perform the registration procedure for mobility and periodic registration update:

[0214] a) 5G-GUTI;

[0215] b) TAI list;

[0216] c) Service area list;

[0217] d) NITZ information;

[0218] e) LADN information;

[0219] e1) Extended LADN information;

[0220] f) Rejected NSSAI;

[0221] NOTE: A cause value associated with a rejected S-NSSAI can be included in the Rejected NSSAI IE or in the Extended rejected NSSAI IE and a back-off timer value associated with rejected S-NSSAI(s) can be included in the Extended rejected NSSAI IE.

[0222] g) void;

[0223] h) Operator-defined access category definitions;

[0224] i) SMS indication;

[0225] j) "CAG information list";

[0226] k) UE radio capability ID;

[0227] l) 5GS registration result;

[0228] m) Truncated 5G-S-TMSI configuration;

[0229] n) T3447 value;

[0230] o) "list of PLMN(s) to be used in disaster condition";

[0231] p) disaster roaming wait range;

[0232] q) disaster return wait range; and

[0233] r) PEIPS assistance information;

[0234] s) Priority indicator;

[0235] t) NSAG information;

[0236] u) RAN timing synchronization;

[0237] v) Alternate NSSAI;

[0238] w) Discontinuous coverage maximum NAS signalling wait time.

[0239] x) Partially allowed NSSAI; and

[0240] y) Patrially rejected NSSAI.

[0241] Accordingly the embodiment is for the support if the Network Slices with Network Slice Area of Service not matching deployed Tracking Areas.

[0242] In an embodiment, the AMF apparatus (104) receives from the OAM the information on availability of a network slice when the granularity is smaller than TA, i.e. if the NS-AoS includes TAs where the network slice is not available in some cells of the TA.

[0243] In an embodiment, in order to optimize the end-to-end behavior, the AMF apparatus (104) can, based on NS-AoS information received from OAM, configure supporting UEs with S-NSSAI location availability information, and the 5GCnetwork may need to monitor the S-NSSAI usage and enforce the NS-AoS e.g. if the UE (102) does not support the S-NSSAI location availability information.

[0244] In an embodiment, the UE (102) that receives S-NSSAI location availability information applies the information as follows.

[0245] In an embodiment, if the S-NSSAI is rejected in the RA or rejected partially in the RA or rejected with a cause code that allows attempting to register the S-NSSAI again, the UE (102) may request the S-NSSAI only if the S-NSSAI location availability information indicates that the S-NSSAI is available at the cell where the UE (102) is camping.

[0246] In an embodiment, if the S-NSSAI is in the partially allowed NSSAI, the UE (102) shall not activate (or request) User Plane resources for any already established PDU Session with that S-NSSAI if the UE (102) is in a cell within the RA but outside the Location information of the S-NSSAI.

[0247] In an embodiment, if the S-NSSAI is in the Partially Allowed NSSAI, and the UE (102) in CM-IDLE mode is moved to a cell outside the Location information of the S-NSSAI, and the UE (102) has an established PDU Session with that S-NSSAI, the PDU Session is kept.

[0248] Accordingly, the embodiment is for the alternate NSSAI IE, where the purpose of the Alternate NSSAI information element is to identify a list of mapping information between the S-NSSAI to be replaced and the alternate S-NSSAI. The Alternate S-NSSAI information element is coded as shown in figure　9.11.3.97.1, figure　9.11.3.97.2 and table　9.11.3.97.1. The Alternate S-NSSAI is a type 4 information element with minimum length of 6 octets and maximum length of 146 octets. The Alternate NSSAI is a type 4 information element with minimum length of 2 octets.

[0249] The Table 1 illustrates alternate NSSAI IE and the Table 2 illustrates entry in the alternate NSSAI IE:

[0250] 87654321Alternate NSSAI IEIoctet 1Length of Alternate NSSAI contentsoctet 2octet 3*Entry 1octet a*octet a+1*Entry 2octet b*octet b+1*...octet c*octet c+1*Entry noctet d*

[0251] 87654321octet 3S-NSSAI to be replacedoctet xoctet x+1Alternate S-NSSAIoctet a

[0252] As per the prior art, if the S-NSSAI is not supported in entire registration area or entire TA, the AMF apparatus (104) will notify the UE (102) in one of the NSSAI lists: the Partially Allowed NSSAI, Partially Rejected NSSAI, or Network Slice Area of Service (NS-AOS). The UE (102) is provided with the alternate S-NSSAI. If the UE (102) initiates the 5GSM procedure for the alternate S-NSSAI e.g. PDU establishment request, at the same time the AMF apparatus (104) tries to remove the mapping between the S-NSSAI to be replaced and the alternate S-NSSAI by sending the UE Configuration update command or any other NAS message. How the UE (102) and the AMF apparatus (104) need to progress on the procedures is not clear.

[0253] Accordingly the embodiment discloses methods to handle collision between a UE requested 5GSM procedure and a UCU involving the alternate S-NSSAI. The method includes sending, by the AMF apparatus (104) an alternate S-NSSAI to the UE (102) by including mapping information between the S-NSSAI and alternate S-NSSAI. The UE (102) initiates the 5GSM procedure by sending the UL NAS message. The AMF apparatus (104) ignores the alternate-S-NSSAI) and includes only S-NSSAI (also called as primary S-NSSAI or Original S-NSSAI or replaced S-NSSAI) in the service operation (for example, a message or a signal) to the SMF apparatus (300A), as the mapping of S-NSSAI to the alternate-S-NSSAI is removed. Further, the SMF apparatus (300A) sends the service operation response to the AMF apparatus (104) for the primary S-NSSAI. If the alternate S-NSSAI is received in a 5GSM message, then the SMF apparatus (300A) will ignore it.

[0254] In general, when a 5GSM message( for example PDU session establishment accept or PDU session modification message) is received with only S-NSSAI and not including the alternate S-NSSAI, the UE (102) shall consider the PDU session as established for S-NSSAI. Additionally, the UE (102) shall delete the corresponding alternate S-NSSAI mapping. At the same time, the AMF apparatus (104) sends a configuration update command or any other NAS message by including the Alternate S-NSSAI. The configuration update command excludes the mapping information between S-NSSAI and the alternate S-NSSAI, or includes the alternate NSSAI with a length of alternate NSSAI contents set to 0. This removes the mapping of S-NSSAI and the alternate S-NSSAI. The UE (102) deletes the corresponding alternate S-NSSAI mapping, and waits for the AMF apparatus (104) to respond to the 5GSM procedure for the S-NSSAI.

[0255] Fig. 11 is a sequence diagram that illustrates a collision between the 5GSM procedure for the alternate S-NSSAI and a UCU removing of the alternate S-NSSAI according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). At step 1, the AMF apparatus (104) sends the alternate A-NSSAI to the UE (102) by containing mapping information between the S-NSSAI and alternate S-NSSAI. At step 2, the UE (102) initiates SM procedure by sending UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU session establishment request by including S-NSSAI and the alternate S-NSSAI containing mapping information between the S-NSSAI and the alternate S-NSSAI. At step 3, the AMF apparatus (104) sends a configuration update command or any other NAS message by including Alternate NSSAI which excludes the mapping information between S-NSSAI and the alternate S-NSSAI to the UE (102). This may include the alternate S-NSSAI with a length of alternate NSSAI contents set to 0 to remove mapping of S-NSSAI and S-NSSAI-2.

[0256] The UE (102) shall delete the corresponding alternate S-NSSAI mapping and waits for the AMF apparatus (104) to respond to the 5GSM procedure for S-NSSAI. The AMF apparatus (104) shall ignore / discard the alternate S-NSSAI and include only primary S-NSSAI in a service operation to the SMF apparatus (300A), as the mapping of primary S-NSSAI to the alternate S-NSSAI is removed. The SMF apparatus (400A) shall send a service operation response to the AMF apparatus (104) for the primary S-NSSAI. IF the alternate S-NSSAI is received in a 5GSM message, then the SMF apparatus (300A) will ignore / discard it. The AMF apparatus (104) sends a DL NAS message e.g. PDU Session Establishment Accept (or any other 5GSM message) for S-NSSAI. In general when the PDU session establishment accept (or any other 5GSM message) is received with only the primary S-NSSAI and not including the Alternate S-NSSAI, the UE (102) shall consider the PDU session is established for the primary S-NSSAI. Additionally, the UE (102) shall delete the corresponding alternate NSSAI mapping.

[0257] Fig. 12 is a sequence diagram that illustrates proceeding with the UCU and waiting for a network response to a SM procedure according to the embodiment as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104) and the SMF apparatus (300A). At step 1, the AMF apparatus (104) shares the alternate NSSAI-1 to the UE (102) by including mapping information between the primary S-NSSAI and the alternate S-NSSAI. At step 2, the UE (102) initiates SM procedure by sending UL NAS message to the SMF apparatus (300A). For example, the UL NAS message may include a PDU session establishment request by including S-NSSAI (also called as primary S-NSSAI) and the alternate S-NSSAI containing mapping information between S-NSSAI and alternate S-NSSAI. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message by including the alternate S-NSSAI. The configuration update command excludes the mapping information between S-NSSAI and the alternate S-NSSAI, or includes the alternate NSSAI with the length of alternate S-NSSAI contents set to 0. This removes the mapping between the S-NSSAI and the alternate S-NSSAI.

[0258] At step S4, the UE (102) shall delete the corresponding Alternate S-NSSAI mapping, and wait for the SMF apparatus (300A) to respond to the 5GSM procedure for S-NSSAI. At step S5, the AMF apparatus (104) shall ignore / discard S-NSSAI-2 (alternate-S-NSSAI) and include only S-NSSAI in send a Nsmf_PDUSession_CreateSMContext Request (or any other service operation) to the SMF apparatus (300A), as the mapping of S-NSSAI to S-NSSAI-2 (Alternate-S-NSSAI) is already removed. At step S6, the SMF apparatus (300A) sends a Nsmf_PDUSession_CreateSMContext response to the AMF apparatus (104) for S-NSSAI. IF S-NSSAI-2 is received in the 5GSM message, then the SMF apparatus (300A) will ignore / discard it. At step S7, the SMF apparatus (300A) sends a DL NAS message e.g. PDU Session Establishment Accept (or any other 5GSM message) for S-NSSAI to the UE (102). In general, when the PDU session establishment accept (or any other 5GSM message) is received with only S-NSSAI and not including the alternate S-NSSAI, the UE (102) shall consider the PDU session is established for S-NSSAI. Additionally, the UE (102) shall delete the corresponding alternate S-NSSAI mapping.

[0259] Fig. 13 is a sequence diagram that illustrates proceeding with the UCU and a retry SM procedure according to the embodiment as disclosed herein. At step 1, the AMF apparatus (104) shares the alternate S-NSSAI to the UE (102) by including mapping information between the S-NSSAI and the alternate S-NSSAI. At step S2, the UE (102) initiates the 5GSM procedure by sending a UL NAS message to the SMF apparatus (300A). For example, the UL NAS message may be a PDU session establishment request by including S-NSSAI and the alternate S-NSSAI containing mapping information between S-NSSAI and the alternate S-NSSAI. At step S3, the AMR apparatus (104) sends a configuration update command or any other NAS message to the UE (102). The configuration update command includes the alternate S-NSSAI that excludes the mapping information between S-NSSAI and the alternate S-NSSAI, or by including the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0. This removes the mapping of S-NSSAI and the alternate S-NSSAI. At step S5, the AMF apparatus (104) shall ignore SM procedure and proceed with the configuration update command or NAS procedure. At step S4, the UE (102) shall delete the mapping between S-NSSAI to the alternate S-NSSAI.

[0260] Fig. 14 is a sequence diagram that illustrates rejection of the 5GSM procedure by using a DL NAS TRANSPORT message according to the embodiments as disclosed herein. As show, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). At step S1, the AMF apparatus (104) sends the alternate S-NSSAI to the UE (102) by including mapping information between the S-NSSAI and the alternate S-NSSAI. At step S2, the UE (102) initiates 5GSM procedure by sending a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU Session Establishment request by including S-NSSAI and the alternate S-NSSAI. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message to the UE (102). The configuration update command includes the alternate S-NSSAI that excludes the mapping information between S-NSSAI and the alternate S-NSSAI or includes the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0, to remove mapping between S-NSSAI and the alternate S-NSSAI.

[0261] At step S4, the UE (102) deletes the corresponding alternate S-NSSAI mapping and waits for completion of the 5GSM procedure. At step S5, the AMF apparatus (104) send a DL NAS TRANSPORT Message to the UE (102). The DL NAS transport message includes a payload container type IE set to "N1 SM information" and 5GMM cause IE set to new cause value e.g. Alternate S-NSSAI not applicable i.e. S-NSSAI-2. Additionally, the UE (102) may remove S1+S2 mapping from the alternate NSSAI-1 mapping. At step S6, the UE (102) shall stop T3580 and retry SM procedure for S-NSSAI without including the alternate S-NSSAI. At step S7, the UE (102) initiates the 5GSM procedure by sending the UL NAS message e.g. the PDU Session Establishment request by including the S-NSSAI to the AMF apparatus (104). At step S7, the AMF apparatus (104) sends the DL NAS message e.g. the PDU Session Establishment Accept for the S-NSSAI to the UE (102).

[0262] Fig. 15 is a sequence diagram that illustrates resending of the UCU according to the embodiments as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104). At step S1, the UE (102) initiates the 5GSM procedure by sending a UL NAS message to the AMF apparatus (104). For example, the UL NAS message may be a PDU Session Establishment request by including S-NSSAI and the alternate S-NSSAI. At step S2, the AMF apparatus (104) determines there is no mapping between S-NSSAI and S-NSSAI-2 available. At step S3, the AMF apparatus (104) shall consider the alternate S-NSSAI mapping requested by UE (102) is wrong and shall send a configuration update command to remove the mapping of S-NSSAI to S-NSSAI-2. At step S4, the AMF apparatus (104) sends a configuration update command or any other NAS message by including the alternate S-NSSAI. The configuration update command excludes the mapping information between S-NSSAI and S-NSSAI-2 or includes the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0. This removes the mapping of S-NSSAI and S-NSSAI-2. At step S5, the UE (102) deletes the mapping of S-NSSAI to S-NSSAI-2.

[0263] Fig. 16 is a sequence diagram that illustrates handling removal of the alternate S-NSSAI according to the embodiments as disclosed herein. As shown, the sequence diagram includes the UE (102) in communication with the AMF apparatus (104) and the SMF apparatus (300A). At step S1, the UE (102) receives the alternate S-NSSAI. At step S2, the AMF apparatus (104) determines that S-NSSAI is available again and decides to remove the alternate S-NSSAI. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message to the UE (102). The configuration update command includes the alternate S-NSSAI by excluding the mapping information between S-NSSAI and S-NSSAI-2, or includes the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0. This removes mapping of S-NSSAI and S-NSSAI-2. At step S4, the AMF apparatus (104) sends updates to the SMF apparatus (300A) of the PDU Session. For example, the updates may include triggering an Nsmf_PDUSession_UpdateSMContext service operation that the PDU Session is to be transferred to the S-NSSAI by not including the Alternative S-NSSIA but including only S-NSSAI.

[0264] Fig. 17A and fig. 17B are a sequence diagram that illustrates a PDU session retention with an explicit PDU modification command according to the embodiments as disclosed herein. As shown, the sequence diagram illustrates the UE (102) in communication with a RAN (1702), the AMF apparatus (104), the SMF apparatus (300A), and the UPF (1704). At step S1, the UE (102) receives the alternate S-NSSAI. At step S2, the AMF apparatus (104) determines that S-NSSAI is available again and decides to remove the alternate S-NSSAI. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message to the UE (102). The configuration update command includes the alternate S-NSSAI by excluding the mapping information between S-NSSAI and S-NSSAI-2, or by including the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0. This removes mapping of S-NSSAI and S-NSSAI-2. At step S4, the UE (102) shall delete the mapping of S-NSSAI to S-NSSAI-2, and consider that the corresponding PDU session is applicable only for S-NSSAI. At step S5, the AMF apparatus (104) sends updates to the SMF apparatus (300A) of the PDU Session. For example, the updates may include triggering a service operation ( for example, Nsmf_PDUSession_UpdateSMContext service operation that the PDU Session is to be transferred to the S-NSSAI (for example, by not including the alternative S-NSSAI. The AMF apparatus (104) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2.

[0265] At step S6, the SMF apparatus (300A) determines that the PDU Session needs to be retained (e.g. if the anchor UPF can be reused with the alternate S-NSSAI and SSC mode 1). At step S7, the SMF apparatus (300A) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2 removed to the UPF (1704) in the N4 message (for example, by not including the alternative S-NSSAI and including only S-NSSAI). At step S8, the SMF apparatus (300A) sends the alternate S-NSSAI removed to the RAN (1702) in the N2 message (for example, by not including the alternative S-NSSAI and including only S-NSSAI.. At step S9, the SMF apparatus (300A) sends a 5GSM message to the UE (102). For example, the 5GSM message may be a PDU session modification command with an indication that the alternate S-NSSAI is not applicable or by not including S-NSSAI-2. At step S10, the UE (102) shall delete the mapping of S-NSSAI to S-NSSAI-2, and consider corresponding PDU session is applicable only for S-NSSAI. At step S11, the UE sends a 5GSM message e.g. PDU session modification complete to the SMF apparatus (300A).

[0266] Fig. 18A and fig. 18B are a sequence diagram that illustrates the PDU session retention without the explicit PDU modification command according to the embodiments as disclosed herein. As shown, the sequence diagram illustrates the UE (102) in communication with the RAN (1702), the AMF apparatus (104), the SMF apparatus (300A), and the UPF (1704). At step S1, the UE (102) receives the alternate S-NSSAI. At step S2, the AMF apparatus (104) determines that S-NSSAI is available again and decides to remove the alternate S-NSSAI i.e. S-NSSAI-2. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message to the UE (102). The configuration update command includes the alternate S-NSSAI by excluding the mapping information between S-NSSAI and S-NSSAI-2, OR by including the alternate S-NSSAI with the length of alternate S-NSSAI contents set to 0. This removes mapping of S-NSSAI and S-NSSAI-2. At step S4, the UE (102) shall delete the mapping of S-NSSAI to S-NSSAI-2.

[0267] At step S5, the AMF apparatus (104) sends updates to the SMF apparatus (300A) of the PDU Session. For example, the updates may be triggering a Nsmf_PDUSession_UpdateSMContext service operation, that the PDU Session is to be transferred to the S-NSSAI. The AMF apparatus (104) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2. The SMF apparatus (300A) determines that the PDU Session needs to be retained (for example, if the UPF (1704) may be reused with the alternate S-NSSAI and SSC mode 1). At step S6, the SMF apparatus (300A) determines that the PDU session needs to be retained (for example, if the UPF (1704) may be reused with the alternate S-NSSAI and SSC mode 1). At step S7, the SMF apparatus (300A) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2 removed) to the UPF (1704) in the N4 message. At step S8, the SMF apparatus (300A) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2 removed) to the RAN (1702) in the N2 message.

[0268] At step S9, the UE (102) shall consider corresponding the PDU session is applicable only for S-NSSAI and continue to use it. The UE (102) may consider current PDU session is applicable only to S1 implicitly without the need for any 5GSM signaling message from SMF apparatus (300A) when it receives UCU with the respective indication. With an indication that the alternate S-NSSAI is not applicable now or by not including the alternate S-NSSAI in the 5GSM message, the UE (102) understands that alternate S-NSSAI is removed. Then the UE (102) shall consider the respective PDU session applicable only for S-1.

[0269] Fig. 19 is a sequence diagram that illustrates a PDU session re-establishment according to the embodiments as disclosed herein. As shown, the sequence diagram illustrates the UE (102) in communication with the RAN (1702), the AMF apparatus (104), the SMF apparatus (300A), and the UPF (1704). At step S1, the UE (102) receives the alternate S-NSSAI i.e. S-NSSAI is replaced with S-NSSAI-2. At step S2, the AMF apparatus (104) determines that S-NSSAI is available again and decides to remove S-NSSAI-2. At step S3, the AMF apparatus (104) sends a configuration update command or any other NAS message. The configuration update command includes the alternate S-NSSAI that excludes the mapping information between S-NSSAI and S-NSSAI-2, or includes the alternate S-NSSAI with the length of alternate NSSAI-1 contents set to 0. This removes mapping of S-NSSAI and S-NSSAI-2. At step S4, the UE (102) shall delete the mapping of S-NSSAI to S-NSSAI-2.

[0270] At step S5, the AMF apparatus (104) sends updates to the SMF apparatus (300A) of the PDU Session. For example, the updates may include triggering a Nsmf_PDUSession_UpdateSMContext service operation, that the PDU Session is to be transferred to the S-NSSAI (for example, by not including the alternative S-NSSAI and including only S-NSSAI.. The SMF apparatus (300A) sends the alternate S-NSSAI (with mapping of S-NSSAI to S-NSSAI-2) removed indication by not including alternative S-NSSAI or with explicit indication. At step S6, the SMF apparatus (300A) determines that the PDU session needs to be retained (for example, if the UPF (1702) may be reused with the alternate S-NSSAI and SSC mode 1). At step S6, the SMF apparatus (300A) determines that the PDU session needs to be re-established. At step S7, the SMF apparatus (300A) sends the Primary / Original / Replaced S-NSSAI to the UE (102) either in a PDU Session Modification Command if the PDU Session is of SSC mode 3, or in PDU Session Release if the PDU Session is of SSC mode 2 or SSC mode 1, to trigger the re-establishment of the PDU Session, with an indication that alternate S-NSSAI is not applicable. At step S8, the UE (102) shall delete the mapping of S-NSSAI to S-NSSAI-2. At step S9, the UE (102) sends a 5GSM message to the SMF apparatus (300A). For example, the 5GSM message may be a PDU session modification complete if SSC mode is 3 or 5GSM message e.g. PDU session establishment request by including only the S-NSSAI when SSC mode is 2 or 1.

[0271] Fig. 20 is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system using the AMF apparatus (104) according to the embodiment as disclosed herein. The method includes steps (2002-2010). Each steps is explained in further detail below.

[0272] At step (2002), a packet data unit (PDU) session is established between the AMF apparatus (104) and the UE (102) over a primary S-NSSAI. Data packet transfer is made possible via the PDU session, which creates a logical link between the UE (102) and the AMF APPARATUS (104). The wireless network system uses the S-NSSAI to determine which network slice is best for a certain service. This guarantees that the features of the network slice satisfy service criteria of the UE (102).

[0273] At step (2004), the AMF apparatus (104) determines whether the primary S-NSSAI is available and necessity or a requirement of the alternate S-NSSAI for the PDU session is necessary. Reliability, latency, bandwidth, and other needs differ throughout services and applications. The AMF apparatus (104) may distribute resources more effectively and offer customized services for every kind of application by utilizing S-NSSAI.

[0274] At step (2006), a service operation message is generated by adding the primary S-NSSAI while omitting the alternate S-NSSAI. This may occur when the primary S-NSSAI is available and the alternate S-NSSAI is not necessary for the PDU session. For example, the service operation message is a Nsmf PDU Session Update SM Context service operation message.

[0275] At step (2008), the AMF apparatus (104) transmits the service operation message generated at step (2006) to the SMF apparatus (300A), which may be associated with the UE (102). The service operation message provides an indication that the PDU session is transferred to the S-NSSAI.

[0276] At step (2010), the AMF apparatus (104) transmits a configuration update command to the UE (102). For instance, the configuration update command includes the alternate S-NSSAI and does not include a mapping information between the primary S-NSSAI and the alternate S-NSSAI. Further, the configuration update command includes the alternate S-NSSAI in which a length of the alternate S-NSSAI contents have been set to 0.

[0277] Fig. 21 is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system in which a PDU session is re-established according to the embodiment as disclosed herein. The flow diagram includes steps (2102 - 2110). Each step is explained in further detail below.

[0278] At step (2102), a PDU session is established between the SMF apparatus (300A) and the UE (102). The PDU session is a logical connection between the UE (102) and the SMF apparatus (300A) to enable the transfer of data packets.

[0279] At step (2104), it is determined whether the PDU session established in step (2102) needs to be re-established. Based on this determination, steps (2106 - 2108) are carried out.

[0280] At step (2106), the SMF apparatus (300A) generates a PDU session modification command to be transmitted to the UE (102) in case the PDU session does not need to be re-established, but retained. In the PDU session modification command, an addition of the alternate S-NSSAI is omitted since the alternate S-NSSAI is not applicable to the PDU session.

[0281] At step (2108), if the PDU session needs to be re-established, the SMF apparatus (300A) determines whether the PDU session is a SSC mode 1, SSC mode 2, or a SSC mode 3. In SSC Mode 1, when the UE (102) travels between several cells or network regions, the PDU session stays intact and unaltered. Throughout the session, the session context―which includes the IP address and QoS settings―is maintained. During mobility events in SSC Mode 2, the PDU session may change. This covers modifications to the user plane function (UPF) and possible session rerouting. Maintaining the same IP address for the UE (102) prevents interruptions to active connections. During mobility events, the PDU session can be released and re-established in SSC Mode 3. This implies that a new session context is formed and that the IP address could change.

[0282] At step (2110), the SMF apparatus (300A) generates a PDU session release command to be transmitted to the UE (102) when the PDU session is of the SSC mode 1 or the SSC mode 2. The PDU session release command is generated by adding the primary S-NSSAI, reactivation required indication (also called as re-establishment required) and omitting addition of the alternate S-NSSAI,.

[0283] At step (2112), the SMF apparatus (300A) generates a PDU session modification command to be transmitted to the UE (102) when the PDU session is of the SSC mode 3. The PDU session modification command is generated by adding the primary S-NSSAI, reactivation required indication (also called as re-establishment required) and by omitting addition of the alternate S-NSSAI .

[0284] Fig. 22A is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system based on a SSC mode according to the embodiment as disclosed herein. The flow diagram includes steps (2202 - 2204). Each step is explained in further detail below.

[0285] At step (2202), the UE (102) receives a PDU session release command or a PDU session modification command from the SMF apparatus (300A) with a reactivation requested indication. The PDU session release command adds a primary S-NSSAI and omits(does not include) addition of an alternate S-NSSAI and sent when the PDU session is of the SSC mode 1 or the SSC mode 2. The PDU session modification command omits addition of the alternate S-NSSAI and sent when the PDU session is of the SSC mode 3.

[0286] At step (2204), a PDU session establishment request is generated to be transmitted to the SMF apparatus (300A). The PDU session establishment request includes only the primary S-NSSAI.

[0287] Fig. 22B is a flow diagram that illustrates a method for handling an alternate S-NSSAI in a wireless network system based on a SSC mode according to the embodiment as disclosed herein. The flow diagram includes steps (2206 - 2208). Each step is explained in further detail below.

[0288] At step (2206), the UE (102) receives a PDU session modification command from the SMF apparatus (300A). The PDU session modification command omits addition of the alternate S-NSSAI and sent when the PDU session is of the SSC mode 3.

[0289] At step (2208), a PDU session modification complete message is generated. The PDU session modification complete message is to be the transmitted to the SMF apparatus (300A) and sent when the PDU session is of the SSC mode 3.

[0290] The terms reactivation requested, reactivation required, reactivation indication, re-establishment required are used interchangeably and have the same meaning. This is an indication sent in the 5GSM message by SMF the network function to indicate to the UE that the UE should re-establish the PDU session.

[0291] The various actions, acts, blocks, steps, or the like in the method is performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some of the actions, acts, blocks, steps, or the like are omitted, added, modified, skipped, or the like without departing from the scope of the proposed method.

[0292] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a session management function (SMF) entity, the method comprising:receiving, from an access and mobility management function (AMF) entity, a first message associated with a protocol data unit (PDU) session update, in case that a PDU session associated with an alternative a single network slice selection assistance information (S-NSSAI) is established and an S-NSSAI is available again, wherein the PDU session is to be transferred to the S-NSSAI, and an alternative S-NSSAI is not included in the first message; andtransmitting, to a terminal, second message including the S-NSSAI.2.The method of claim 1, wherein the transmitting further comprising:determining whether the PDU session is to be re-established;identifying whether the PDU session is of session and service continuity (SSC) mode 3, in case that the PDU session is determined to be re-established; andtransmitting, to the terminal, a PDU session modification command message including the S-NSSAI in case that the PDU session is of the SSC mode 3, the alternative S-NSSAI being not included in the PDU session modification command message.3.The method of claim 2, further comprising:receiving, from the terminal, a PDU session modification complete message.4.The method of claim 1, wherein the transmitting further comprising:determining whether the PDU session is to be re-established;identifying whether the PDU session is of SSC mode 1 or SSC mode 2, in case that the PDU session is determined to be re-established; andtransmitting, to the terminal, a PDU session release message including the S-NSSAI to trigger a re-establishment of the PDU session in case that the PDU session is of the SSC mode 1 or the SSC mode 2, the alternative S-NSSAI being not included in the PDU session release message.5.The method of claim 4, further comprising:receiving, from the terminal, a PDU session establishment message including the S-NSSAI.6.The method of claim 1, wherein the transmitting further comprising:determining whether the PDU session is to be retained; andtransmitting, to the terminal, a PDU session modification command message including the S-NSSAI in case that the PDU session is to be retained, the alternative S-NSSAI being not included in the PDU session modification command message.7.A method performed by an access and mobility management function (AMF) entity, the method comprising:determining that a single network slice selection assistance information (S-NSSAI) is available again in case that a protocol data unit (PDU) session associated with an alternative a single network slice selection assistance information (S-NSSAI) is established; andtransmitting, to a session management function (SMF) entity, a message associated with a PDU session update, wherein the PDU session is to be the S-NSSAI, and the alternative S-NSSAI is not included in the message.8.A session management function (SMF) entity, the SMF comprising:a transceiver; andat least one processor configured to:receive, from an access and mobility management function (AMF) entity via the transceiver, a first message associated with a protocol data unit (PDU) session update, in case that a PDU session associated with an alternative a single network slice selection assistance information (S-NSSAI) is established and an S-NSSAI is available again, wherein the PDU session is to be transferred to the S-NSSAI, and an alternative S-NSSAI is not included in the first message, andtransmit, to a terminal via the transceiver, second message including the S-NSSAI.9.The SMF of claim 8, wherein the at least one processor is further configured to:determine whether the PDU session is to be re-established,identify whether the PDU session is of session and service continuity (SSC) mode 3, in case that the PDU session is determined to be re-established, andtransmit, to the terminal via the transceiver, a PDU session modification command message including the S-NSSAI in case that the PDU session is of the SSC mode 3, the alternative S-NSSAI being not included in the PDU session modification command message.10.The SMF of claim 9, wherein the at least one processor is further configured to:receive, from the terminal via the transceiver, a PDU session modification complete message.11.The SMF of claim 8, wherein the at least one processor is further configured to:determine whether the PDU session is to be re-established;identify whether the PDU session is of SSC mode 1 or SSC mode 2, in case that the PDU session is determined to be re-established;transmit, to the terminal via the transceiver, a PDU session release message including the S-NSSAI to trigger a re-establishment of the PDU session in case that the PDU session is of the SSC mode 1 or the SSC mode 2, the alternative S-NSSAI being not included in the PDU session release message.12.The SMF of claim 11, wherein the at least one processor is further configured to:receive, from the terminal via the transceiver, a PDU session establishment message including the S-NSSAI.13.The SMF of claim 8, wherein the at least one processor is further configured to:determining whether the PDU session is to be retained; andtransmitting, to the terminal, a PDU session modification command message including the S-NSSAI in case that the PDU session is to be retained, the alternative S-NSSAI being not included in the PDU session modification command message.14.An access and mobility management function (AMF) entity, the AMF entity comprising:a transceiver; andat least one processor configured to:determine that a single network slice selection assistance information (S-NSSAI) is available again in case that a protocol data unit (PDU) session associated with an alternative a single network slice selection assistance information (S-NSSAI) is established; andtransmitting, to a session management function (SMF) entity, a message associated with a PDU session update, wherein the PDU session is to be the S-NSSAI, and the alternative S-NSSAI is not included in the message.

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