Replacement of an alternative network slice

Abstract

There is provided an apparatus comprising means for receiving information from a network indicating a first allowed network slice, establishing a first protocol data unit session using the first allowed network slice, receiving from the network the trigger for replacement of the first network slice by a second allowed network slice, triggering the replacement of the first network slice by the second network slice for the PDU session, receiving updated information from the network indicating at least one third allowed network slice, mapping the at least one third allowed network slice to the first network slice based on the updated information and triggering the replacement of the second allowed network slice by one of the at least one third allowed network slice

Description

TITLEApparatus, Method and Computer ProgramTECHNICAL FIELD

[0001] Various embodiments of this disclosure relate generally to methods, apparatus and computer programs, and in particular, but not exclusively, to temporary available network slices and network slice replacement.BACKGROUND

[0002] A communication system can be seen as a facility that enables communication sessions between two or more communication devices, or provides communication devices access to a network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

[0003] A mobile or wireless communication network may operate in accordance with standard^), such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of mobile or wireless communication network that operate in accordance with 3GPP standards are generally referred to as 4G (4th Generation) networks, 5G (5th Generation) network, 5G-Advanced networks and 6G networks.SUMMARY

[0004] Some embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the various example embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described herein.

[0005] In a first aspect there is provided a method comprising receiving information from a network indicating a first allowed network slice, establishing a first protocol data unit, PDU, session with the network using the first allowed network slice, receiving from the network a trigger for replacement of the first network slice by a second allowed network slice, triggering replacement of the first network slice by the second network slice for the PDU session, receiving updated information from the network indicating the second allowed network slice and at least one third allowed network slice, mapping each of the alternative second allowed network slice and at least one alternative third allowed network slice to the first network slice based on the updated information and triggering, based on the receiving updated information, the replacement of the second allowed network slice by one of the at least one third allowed network slice for the PDU session.

[0006] The first allowed network slice may be a temporarily allowed network slice.

[0007] The second and third allowed network slices may be alternative network slices.

[0008] The method may comprise receiving the information and the updated information from a network function.

[0009] The network function may be at least one of an access and mobility function or a session management function.

[0010] The method may comprise receiving the updated information in a user equipment configuration update message.

[0011] The method may comprise receiving the updated information in a protocol data unit session modification message.

[0012] The method may comprise receiving the updated information via non access stratum signalling.

[0013] The method may comprise providing information to the network indicative of support for network slice replacement using a temporary available network slice replacement.

[0014] The method may comprise, upon receiving the updated information indicating the at least one third allowed network slice, removing the second allowed network slice from a memory of the apparatus.

[0015] In a second aspect there is provided a method comprising providing information to a user equipment indicating a first allowed network slice, establishing a first protocol data unit session with the user equipment using the first allowed network slice, triggering the replacement of the first allowed network slice by a second network slice for the PDU session, determining that the second allowed network slice is becoming unavailable; and providing updated information to the user equipment indicating the second allowed network slice and at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice.

[0016] The first allowed network slice may be a temporarily allowed network slice.

[0017] The second and third allowed network slices may be alternative network slices.

[0018] The method may be performed at an access and mobility function.

[0019] The method may comprise providing the updated information in a user equipment configuration update message.

[0020] The method may comprise receiving the updated information via non access stratum signalling.

[0021] The method may comprise receiving information indicative of support for network slice replacement using a temporary available network slice replacement.

[0022] Determining that the second allowed network slice is becoming unavailable may comprise determining that the second allowed network slice is congested or an availability time period for the second allowed network slice has expired.

[0023] The method may comprise determining to provide an indication of the at least one third allowed network slice based on load information received from a network data and analytics function.

[0024] In a third aspect, there is provided a method, comprising, at an apparatus, triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session, receiving indication from an access management function to replace the second allowed network slice by at least one third network slice and providing updated information to the user equipment indicating the second allowed network slice and at least one third allowed network slice, and information for mapping each of the second allowed network slice and the at least one third allowed network slice to the first network slice.

[0025] The method may comprise providing the updated information in a protocol data unit session modification message.

[0026] The second and third allowed network slices may be alternative network slices.

[0027] In a fourth aspect there is provided a method comprising receiving information from a network indicating a first allowed network slice, establishing a first protocol data unit session using the first allowed network slice, receiving from the network the trigger for replacement of the first network slice by a second allowed network slice, triggering the replacement of the first network slice by the second network slice for the PDU session, receiving updated information from the network indicating at least one third allowed network slice, mapping the at least one third allowed network slice to the first network slice based on the updated information and triggering the replacement of the second allowed network slice by one of the at least one third allowed network slice.

[0028] The first allowed network slice may be a temporarily allowed network slice.

[0029] The second and third allowed network slices may be alternative network slices.

[0030] The method may compromise receiving the information and the updated information from a network function.

[0031] The network function may be at least one of an access and mobility function or a session management function.

[0032] The method may comprise receiving the updated information in a user equipment configuration update message.

[0033] The method may comprise receiving the updated information in a protocol data unit session modification message.

[0034] The method may comprise providing information to the network indicative of support for network slice replacement using a temporary available network slice replacement.

[0035] The method may comprise, upon receiving the updated information indicating the at least one third allowed network slice, removing the second allowed network slice from a memory of the apparatus.

[0036] In a fifth aspect there is provided a method comprising providing information to a user equipment indicating a first allowed network slice, establishing a first protocol data unit session with the user equipment using the first allowed network slice, triggering the replacement of the first allowed network slice by a second network slice for the PDU session, determining that the second allowed network slice is becoming unavailable and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

[0037] The first allowed network slice may be a temporarily allowed network slice.

[0038] The second and third allowed network slices may be alternative network slices.

[0039] The method may be performed at an access and mobility function.

[0040] The method may comprise providing the updated information in a user equipment configuration update message.

[0041] The method may comprise receiving information from the user equipment indicative of support for network slice replacement using a temporary available network slice replacement.

[0042] Determining that the second allowed network slice is becoming unavailable comprises determining that the second allowed network slice is congested or an availability time period for the second allowed network slice has expired or is going to expire.

[0043] The method may comprise determining to provide an indication of the at least one third allowed network slice based on load information received from a network data and analytics function.

[0044] In a sixth aspect there is provided a method at a session management function comprising triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session, receiving indication from an access management function to replace the second allowed networks slice by at least one third network slice and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

[0045] The method may comprise providing the updated information in a protocol data unit session modification message.

[0046] The second and third allowed network slices may be alternative network slices.

[0047] In a seventh aspect there is provided a method comprising receiving information from a network indicating a first allowed network slice, establishing a first protocol data unit session using the first allowed network slice, receiving further information from the network indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice, mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice based on the further information, receiving information to trigger the replacement of first allowed network slice by the second allowed network slice,replacing the first allowed network slice by the second allowed network slice for the PDU session, determining that the second network slice is becoming unavailable based on the received availability time period for the second allowed network slice and triggering, based on the determining, the replacement of the second network slice for the PDU session using the at least one third allowed network slice.

[0048] The method may comprise establishing a second protocol data unit session using the at least one third allowed network slice when the availability time period for the second allowed network slice has expired.

[0049] The method may comprise providing an indication to the network of the time that the at least one third allowed network slice is to be used for establishing the second protocol data unit session.

[0050] The method may comprise receiving the information and the updated information from a network function.

[0051] The network function may be at least one of an access and mobility function or a session management function.

[0052] The method may comprise receiving the updated information in a user equipment configuration update message.

[0053] The method may comprise receiving the updated information in a protocol data unit session modification message.

[0054] The method may comprise providing information to the network indicative of support for network slice replacement using a temporary available network slice replacement.

[0055] The second and third allowed network slices may be alternative network slices.

[0056] In an eighth aspect there is provided a method comprising providing information to a user equipment indicating a first allowed network slice, establishing a first protocol data unit session with the user equipment using the first allowed network slice, providing further information to the user equipment indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice, triggering the replacement of the first allowed network slice by the second allowed network slice and receiving, from the user equipment, a request to replace the second allowed network slice using the at least one third allowed network slice.

[0057] The method may be performed at an access and mobility function.

[0058] The method may comprise providing the updated information in a user equipment configuration update message.

[0059] The method may comprise receiving information from the user equipment indicative of support for network slice replacement using a temporary available network slice replacement.

[0060] The method may comprise determining to provide an indication of the at least one third allowed network slice based on load information received from a network data and analytics function.

[0061] The second and third allowed network slices may be alternative network slices.

[0062] In a ninth aspect, there is provided a method at a session management function comprising providing information to a user equipment indicating a first allowed network slice, establishing a first protocol data unit session with the user equipment using the first allowed network slice, providing further information to the user equipment indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice, triggering the replacement of the first allowed network slice by the second allowed network slice and receiving, from the user equipment, a request to establish a PDU session using the at least one third allowed network slice.

[0063] The method may comprise providing the further information in a protocol data unit session modification message.

[0064] The second and third allowed network slices may be alternative network slices.

[0065] In a tenth aspect there is provided an apparatus comprising means for performing the method according to any of the first to ninth aspects.

[0066] In an eleventh aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus at least to perform a method according to any of the first to ninth aspect.

[0067] In a twelfth aspect there is provided a non-transitory computer readable medium comprising instructions wherein the instructions when executed by at least one processor of an apparatus cause the apparatus to perform the method according to any of the first to ninth aspect.

[0068] Some embodiments of the disclosure are defined in the dependent claims.

[0069] In the above, many different aspects have been described. As previously noted, it should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above (or otherwise in this disclosure).

[0070] Various other aspects are also described in the following detailed description and in the claims.BRIEF DESCRIPTION OF THE FIGURES

[0071] Some embodiments will be described, by way of non-limiting and illustrative example only, with reference to the figures, in which:

[0072] Fig. 1 shows an example of a communication network to which examples disclosed herein may be applied;

[0073] Fig. 2 shows an example format of an S-NSSAI;

[0074] Fig. 3 shows an example format of an Alternative NSSAI IE;

[0075] Fig. 4 shows an example format of mapping between S-NSSAI to be replaced and Alternative S-NSSAI;

[0076] Fig. 5 shows a flowchart of an example method;

[0077] Fig. 6 shows a flowchart of an example method;

[0078] Fig. 7 shows a flowchart of an example method;

[0079] Fig. 8 shows an example format of an Extended Alternative NSSAI IE;

[0080] Fig. 9 shows an example signaling flow;

[0081] Fig. 10 shows a flowchart of an example method;

[0082] Fig. 11 shows a flowchart of an example method;

[0083] Fig. 12 shows a flowchart of an example method;

[0084] Fig. 13 shows an example format of an Alternative NSSAI IE with enhanced mapping;

[0085] Fig. 14 shows a flowchart of an example method;

[0086] Fig. 15 shows a flowchart of an example method;

[0087] Fig. 16 shows a flowchart of an example method;

[0088] Fig. 17 shows an example format of an Extended Alternative NSSAI IE;

[0089] Fig. 18 shows an example of an apparatus.DETAILED DESCRIPTION

[0090] The following embodiments are provided by way of non-limiting and illustrative example. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it intended such feature, structure, or characteristic may be applied in connection with other embodiments (whether or not explicitly described).

[0091] It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0092] For the purposes of this disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of this disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0093] As used herein, the term “or” refers to a non-exclusive “or” unless otherwise indicated (e.g., use of “or else” or “or in the alternative”).

[0094] As used herein, unless stated explicitly, performing a respective feature, step, or functionality “in response to A” does not indicate that the respective feature, step, or functionality is performed immediately after “A” occurs as one or more intervening features, steps, or functionalities may be performed (at least in part) between an occurrence of the respective feature, step, or function and “A”. Analogously, performing a respective feature, step, or functionality “based on A” does not indicate that the respective feature, step, or functionality is performed solely based on “A” as the respective feature, step, or functionality may be further based on one or more other features, steps, or functionalities in addition to “A”.

[0095] Embodiments described herein may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0096] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the network and / or which is configured to control radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or non-ground network device, such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0097] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralised unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an F1 interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical(PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0098] The term “terminal device” refers to any end device that may be configured to perform wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like.

[0099] A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources may include, e.g., a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0100] Fig. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 configured to provide one or more cells, such as cell 100, and a network node 112 configured to provide one or more other cells, such as cell 102. Each cell may, for example, be a macro cell, a micro cell, femto, or a pico cell. The cell may define a coverage area or a service area of the corresponding access node.

[0101] The network node (110, 112) may be configured to provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node (110, 112) to the UE 120 and uplink (UL) communication from the UE 120 to the network node (110, 112). Examples of uplink channels may comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels may comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0102] There may be a plurality of UEs (120, 122) in the system. Each of the plurality of UEs may be served by the same or by different network nodes (110, 112). UE may be configured with dual connectivity (DC), wherein the UE, for example UE 120, may be connected to multiple network nodes (110, 112). The UEs (120, 122) may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0103] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications, for example, refer to such an interface as an X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called an Xn interface.

[0104] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise a plurality of entities (e.g. a mobility management entity (MME) and a gateway node). The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5GC may, for example, comprise an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may, for example, support packet routing and forwarding, packet inspection and quality of service (QoS) handling.

[0105] Network slicing is a 5G feature to support different services using the same underlying mobile network infrastructure. Network slices can differ either in their service requirements like UltraReliable Low Latency Communication (URLLC) and enhanced Mobile Broadband (eMBB) or the tenant that provides those services.

[0106] A network slice is uniquely identified via the S-NSSAI (Single-Network Slice Selection Assistance Information). Current 3GPP specifications allow a UE to be simultaneously connected and served by at most eight slices corresponding to eight network slices meaning eight S-NSSAIs. On other hand, each cell may support tens or even hundreds of slices, e.g., in the current specifications a Tracking Area (TA) can have a support up to 1024 network slices, which may be further extended with an additional number of 65535 slices.

[0107] Fig. 2 shows an example format of S-NSSAI. The S-NSSAI may include both Slice Service Type (SST) and Slice Differentiator (SD) field with a total length of 32 bits or include only SST field part in which case the length of S-NSSAI is 8 bits only.

[0108] The SST field may have standardized and non-standardized values. Values 0 to 127 belong to the standardized SST range. For instance, SST value of 1 may indicate that the slice is suitable for handling of 5G eMBB, 2 for handling of LIRLLC, etc. SD is operator-defined.

[0109] The concept of network slice replacement may be used to replace an S-NSSAI with an Alternative S-NSSAI when an S-NSSAI becomes unavailable or congested.

[0110] The Network Slice Replacement may be triggered in the following cases:If the NSSF detects that an S-NSSAI becomes unavailable or congested (e.g. based on Orchestration and Management Entity (OAM) or Network Data and Analytics Function (NWDAF) analytics output), it sends network slice availability notification for the S-NSSAI to the AMF. The notification may include an Alternative S-NSSAI which can be used by the AMF to replace the S- NSSAI. The Network Slice Selectin Function (NSSF) notifies the AMF when the S-NSSAI is available again.If the Policy and Charging Function (PCF) detects that an S-NSSAI becomes unavailable or congested for a UE (e.g. based on OAM or NWDAF analytics output), it sends access and mobility related policy notification to the AMF. The notification may include an Alternative S-NSSAI which can be used by the AMF to replace the S-NSSAI. The PCF notifies the AMF when the S- NSSAI is available again for the UE.The OAM sends notification to AMF when an S-NSSAI becomes unavailable or congested (and also when this S-NSSAI becomes available again) and provides the Alternative S- NSSAI to AMF.

[0111] Depending on the connected state of the UE, the AMF may provide the Alternative S- NSSAI for this S-NSSAI in the Allowed NSSAI and in the Configured NSSAI, if not included yet, and the mapping between S-NSSAI(s) to Alternative S-NSSAI(s) to the UE in a UE Configuration Update message or a Registration Accept message.

[0112] For example, if the UE has not yet received with the Allowed NSSAI a mapping of the S-NSSAI to the Alternative S-NSSAI, the UE provides only the S-NSSAI in the Protocol Data Unit (PDU) Session Establishment message. If the AMF determines that the requested S-NSSAI is to be replaced with the Alternative S-NSSAI and if the UE supports Network Slice Replacement, the AMF performs UE Configuration Update procedure to reconfigure the UE with the Alternative S-NSSAI. The AMF continues the PDU Session establishment procedure with the Alternative S-NSSAI and uses SMF Selection Subscription data of the replaced S-NSSAI and selects a suitable SMF supporting Network Slice Replacement and the Alternative S-NSSAI. The AMF provides both the Alternative S-NSSAI and the S-NSSAI to the SMF in Nsmf_PDUSession_CreateSMContext service operation.

[0113] Fig. 3 shows an example format of a NSSAI Information Element (IE) and Fig. 4 shows an example format of mapping between S-NSSAI to be replaced and Alternative S-NSSAI. As shown in Fig. 4, a replaced S-NSSAI has one alternative S-NSSAI to be used as replacement during the procedure.

[0114] A network slice may be available for a UE or group of UEs available only for a certainamount of time that is known to the network in advance either via OAM configuration or via subscription information.

[0115] Based on information received from NSSF or Unified Data Management (UDM), an AMF may indicate to supporting UEs the validity time for one or more S-NSSAIs in the Configured NSSAI towards the UE in the Registration Accept or UE Configuration Update message.

[0116] If validity time indicates S-NSSAI not available the UE shall not include the S-NSSAI in the Requested NSSAI and if the S-NSSAI is already part of Allowed NSSAI or Partially Allowed NSSAI the UE shall remove the S-NSSAI from the locally stored Allowed NSSAI or Partially Allowed NSSAI and the UE shall locally release any PDU session associated with the S-NSSAI. From the UE perspective, the UE receives time constraints of a slice in the form of S-NSSAI time validity information. There may be up to 16 S-NSSAIs for which time validity is provided. For each S-NSSAI, there can be one or more time windows of validity, where each time window is associated with the start and end time of the validity.

[0117] If the S-NSSAI that is no longer valid (validity time indicates the S-NSSAI is unavailable) is included in the Allowed NSSAI or the Partially Allowed NSSAI, the AMF removes the S-NSSAI from them locally and also request the SMF to release the PDU sessions associated with the S- NSSAI if there are any.

[0118] Currently, the mapping between a replaced slice and an alternative slice for the slice replacement feature only includes a one-to-one mapping, i.e., only one alternative slice is mapped to the replaced one during the procedure. The possibility of triggering network slice replacement when the replaced slice is congested is considered, however, there is currently no defined operation when the alternative slice, i.e., the one used as a replacement, becomes unavailable during the operation.

[0119] In the following, the term the term “replaced slice” is the slice that the UE was originally using before the slice became congested or underwent maintenance at the core network. The term “original slice” and “replaced slice” are interchangeable.

[0120] The term “alternative slice” is the slice that replaces the slice that the UE was originally using before the original slice became congested or underwent maintenance at the core network. The term “alternative slice” and “replacement slice” are interchangeable.

[0121] Three scenarios (S1 , S2, S3) are considered, where Trep= replacement period / conges- tion time of the replaced slice and Tait = time availability of the alternative slice:• S1 : Replacement period of the replaced slice and the alternative slice have the same time duration: Trep= Tait• S2: Replacement period of the replaced slice has a shorter time duration than the alternative slice duration: Trep< Tait and,• S3: Replacement period of the replaced slice has a longer time duration than the alternative slice duration: Trep> Tait.

[0122] By using the procedures in the current specification as explained above, both S1 and S2 are supported.

[0123] However, S3 needs changes / additions to the specification since currently there is no supported behavior.

[0124] The time availability of the alternative slice may be shorter than the time needed to be used as replacement, i.e., Trep> Tait, due to the alternative slice being congested itself or based on some other time constraint. In this case, the availability of the alternative slice for the UE will stop before the expected availability of the replacement slice leaving the UE without an available slice within the network slice procedure.

[0125] For the case of Trepis based on maintenance of the replaced slice, the AMF might know that Trepis longer than Tait and select an alternative slice that fulfills the requirement Tait > Trep(if such alternative slice is possible to be found)

[0126] However, this issue cannot be easily solved for the case that Trepis based on congestion since the PCF / NSSF / OAM does not know precisely for how long the replaced S-NSSAI will remain congested.

[0127] The network may not know before using the alternative slice as replacement slice the specific time availability Tait, for example if the alternative slice becomes congested itself during the network slice replacement operation. It may be difficult to estimate to estimate the needed time for the replacement (Trep), for example if the replacement is triggered due to congestion and not simply due to maintenance.

[0128] Currently, there is no procedure that handles what happens when the alternative slice for which the UE has been updated to operate with during the replacement of the original slice becomes unavailable.

[0129] That is, network and UE behaviour are not specified in the case where the duration of the alternative slice is longer than that of the replacement slice and the UE may not be able to access neither of the two after the duration of the alternative slice expires.

[0130] Fig. 5 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a UE.

[0131] At 501 , the method comprises receiving information from a network indicating a first allowed network slice.

[0132] At 502, the method comprises establishing a first protocol data unit, PDU, session with the network using the first allowed network slice.

[0133] At 503, the method comprises receiving from the network a trigger for replacement of the first network slice by a second allowed network slice.

[0134] At 504, the method comprises triggering replacement of the first network slice by the second network slice for the PDU session.

[0135] At 505, the method comprises receiving updated mapping information from the networkindicating the second allowed network slice and at least one third allowed network slice.

[0136] At 506, the method comprises mapping each of the alternative second allowed network slice and at least one alternative third allowed network slice to the first network slice based on the updated mapping information.

[0137] At 507, the method comprises triggering, based on the receiving, the replacement of the second allowed network slice by one of the at least one third allowed network slice for the PDU session.

[0138] A method as described with reference to Fig. 5 may comprise receiving the information and the updated information from a network function. The network function may be at least one of an access and mobility function or a session management function.

[0139] Fig. 6 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a network node. The network node may be or implement a network function such as AMF or SMF.

[0140] At 601 , the method comprises providing information to a user equipment indicating a first allowed network slice.

[0141] At 602, the method comprises establishing a first protocol data unit session with the user equipment using the first allowed network slice.

[0142] At 603, the method comprises triggering the replacement of the first allowed network slice by a second network slice for the PDU session.

[0143] At 604, the method comprises determining that the second allowed network slice is becoming unavailable.

[0144] At 605, the method comprises providing updated information to the user equipment indicating the second allowed network slice and at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice.

[0145] In a method as described with reference to Fig. 6, determining that the second allowed network slice is becoming unavailable may comprise determining that the second allowed network slice is congested or an availability time period for the second allowed network slice has expired.

[0146] Fig. 7 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a network node. The network node may be or implement a SMF.

[0147] At 701 , the method comprises triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session.

[0148] At 702, the method comprises receiving indication from an access management function to replace the second allowed network slice by at least one third network slice.

[0149] At 703, the method comprises providing updated information to the user equipment indicating the second allowed network slice and at least one third allowed network slice, andinformation for mapping each of the second allowed network slice and the at least one third allowed network slice to the first network slice.

[0150] The first allowed slice may be a temporarily allowed slice. The second and third allowed network slices may be alternative network slices.

[0151] For example, methods as described with reference to Figs. 5 to 7 may involve the creation of an Extended Alternative NSSAI IE, where more than one alternative slice is mapped to a replaced slice for the UE. The Extended Alternative NSSAI IE is an example of updated information indicating the second allowed network slice and at least one third allowed network slice. Fig. 8 shows an example format of an Extended Alternative NSSAI IE. In this figure, two alternative S-NSSAI (1 and 2) and only one S-NSSAI to be replaced for simplicity but in general more slices may be included as Alternative S-NSSAIs. Upon receiving the updated information indicating the at least one third allowed network slice, the UE may remove the second allowed network slice from a memory of the apparatus.

[0152] The maximum number of alternative slices mapped to one S-NSSAI to be replaced may be limited to N in this new Extended Alternative NSSAI IE, e.g., 8 slices, and the total number of alternative slices for all the slices to be replaced may be also considered to be limited.

[0153] The UE will receive in the updated information (e.g., extended NSSAI IE) more than one alternative slice which upon further replacement of the first alternative slice need to be replaced by the second alternative slice contained in the IE, and potentially, subsequent replacement with a third, fourth, etc. alternative slice.

[0154] The UE may ignore the previous Alternative NSSAI IE (Rel-18) if the Extended Alternative NSSAI IE is received and trigger SSC mode 3 upon receiving the new Extended Alternative NSSAI IE (i.e. setup the new PDU session with alternative S-NSSAI_2 before releasing the PDU session with alternative S-NSSAI_1). This is an example of triggering, based on receiving updated information, the replacement of the second allowed network slice by one of the at least one third allowed network slice for the PDU session This will enable seamless switch of alternative S-NSSAI similar to the legacy case of the network slice replacement.

[0155] The update of Alternative NSSAI IE may be triggered by using UE configuration update procedure or registration procedure.

[0156] A method as described with reference to Fig. 5 may comprise protocol data unit session modification message. In an example, there is an extension of the PDU Session Modification Command to enable seamless PDU session modification between several alternative slices mapped to the same replaced slice.

[0157] A method as described with reference to Fig. 5 may comprise receiving the updated information in a UE configuration update message (e.g., from SMF). In an example there is an extension of the UE configuration update including the additional alternative slices that can be used by the UE during network slice replacement.

[0158] The updated information may be received via NAS signalling, e.g., during registration procedure.

[0159] Changes to the Alternative S-NSSAI IE may be needed to allow having multiple alternative S-NSSAI mapped to the same replaced S-NSSAI in different entries.

[0160] This will also require changes to decide which entry is used or at least a clarification on whether multiple alternative slices can be mapped to the same replaced slice.

[0161] An indication of the at least one third allowed network slice may be provided to- the UE by the network. There may be a network created (automatically) slice for capacity enhancement / con- gestion management. Trigger for creating new slice can be due to NWDAF report slice usage / load conditions. The indication may be based on load information received from a network data and analytics function.

[0162] Information may be provided from the UE to the network indicative of support for network slice replacement using a temporary available network slice replacement.

[0163] Fig. 9 shows an example signalling flow between a UE, RAN node and CN (AMF, SMF and UPF).

[0164] At step 1 , UE registers with the network and requests slice 1 for usage. UE also indicates to the network that it supports the features of network slice replacement and temporary available network slices. This is an example of providing information to the network indicative of support for network slice replacement using a temporary available network slice replacement.

[0165] At step 2, AMF provides to the UE an Allowed NSSAI list that contains slice 1. This is an example of providing information to a user equipment indicating a first allowed network slice.

[0166] At step 3, UE establishes a PDU session with the network with slice 1.

[0167] At steps 4-5, after some time, slice 1 becomes congested or unavailable at the core network and AMF based on internal configuration or via communication with other core network NFs, for instance NSSF or PCF determines a new replacement slice for the original slice 1 of the UE. AMF provides to the UE a new Allowed NSSAI that includes slice 1 and slice 2 that is the alternative S- NSSAI for the replaced slice 1. Slice 2 is a temporary available S-NSSAI in this scenario as AMF could not find any other suitable S-NSSAI to replace slice 1 with, e.g., considering slice service level agreement s (SLAs). This is an example of a trigger for replacement of the first network slice by a second allowed network slice and triggering replacement of the first network slice by the second network slice for the PDU session

[0168] At step 6, after some time, AMF detects that slice 2 that has replaced slice 1 of the UE will not be available, e.g., due to expire or becomes unavailable, but slice 1 is still congested, and therefore, still needs to be replaced to keep service to the UE. This is an example of determining that the second allowed network slice is becoming unavailable.

[0169] At step 7, AMF triggers a UE configuration update command to the UE via NAS signaling that indicates a new extended Alternative NSSAI IE that includes the original slice of the UE (i.e., slice 1) and more alternative S-NSSAIs. This is an example of providing updated information fromthe network indicating the second allowed network slice and at least one third allowed network slice.

[0170] At step 8, AMF provides a PDU session modification command to the UE, in this example, via NAS signaling that indicates a new extended Alternative NSSAI that includes the original slice of the UE (i.e. , slice 1) and more alternative S-NSSAIs. This is an example of providing updated information from the network indicating the second allowed network slice and at least one third allowed network slice. In this example scenario, slice 2 is the first alternative S-NSSAI as well as slice 3 that is the second alternative S-NSSAI. AMF updates the Allowed NSSAI of the UE that include now instead of slice 2, slice 3. AMF may further provide to the UE indicate to enable SSC mode 3 for the PDU session establishment to allow for PDU session continuity.

[0171] At step 9, UE utilizes the new Allowed NSSAI list as well as the new mapping information between the original slice 1 and the second alternative slice 3 for the PDU session establishment. This is an example of mapping each of the alternative second allowed network slice and at least one alternative third allowed network slice is mapped to the first network slice based on the updated information and triggering, based on the receiving updated information, the replacement of the second allowed network slice by one of the at least one third allowed network slice for the PDU session

[0172] Figures 10 to 15 relate to example embodiments where the encoding of the Extended Alternative NSSAI is different to that described with reference to Figs. 5 to 8.

[0173] In one option, once the first alternative slice that has been used to replace the original slice of the UE is not available anymore, e.g., Tait is exceeded because the alternative slice was a temporary slice or due to congestion, the alternative NSSAI IE may be updated to remove the previous alternative S-NSSAI with Tait and adding new network slice replacement for the replaced S- NSSAI.

[0174] If the alternative slice is not available and the AMF determines that the S-NSSAI which has been replaced is not yet available, the AMF provides the updated alternative NSSAI excluding the non-available alternative S-NSSAI to the UE during the UE configuration update procedure or during the registration procedure.

[0175] These additions have the advantage of “cleaning / flashing” the Alternative NSSAI, (i.e., removing the non-available Alternative S-NSSAI), which currently is only updated when the replaced S-NSSAI becomes available again.

[0176] Fig. 10 shows a flowchart of an example method where the previous alternative S_NSSAI is removed and the adding new network slice replacement for the replaced S-NSSAI is added. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a UE.

[0177] At 1001 , the method comprises receiving information from a network indicating a first allowed network slice.

[0178] At 1002, the method comprises establishing a first protocol data unit session using thefirst allowed network slice.

[0179] At 1003, the method comprises receiving from the network the trigger for replacement of the first network slice by a second allowed network slice.

[0180] At 1004, the method comprises triggering the replacement of the first network slice by the second network slice for the PDU session,

[0181] At 1005, the method comprises receiving updated information from the network indicating at least one third allowed network slice.

[0182] At 1006, the method comprises mapping the at least one third allowed network slice to the first network slice based on the updated information.

[0183] At 1007, the method comprises triggering the replacement of the second allowed network slice by one of the at least one third allowed network slice.

[0184] Fig. 11 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a network node. The network node may be or implement a network function such as AMF or SMF.

[0185] At 1101 , the method comprises providing information to a user equipment indicating a first allowed network slice.

[0186] At 1102, the method comprises establishing a first protocol data unit session with the user equipment using the first allowed network slice.

[0187] At 1103, the method comprises triggering the replacement of the first allowed network slice by a second network slice for the PDU session.

[0188] At 1104, the method comprises determining that the second allowed network slice is becoming unavailable.

[0189] At 1105, the method comprises providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

[0190] Fig. 12 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a network node. The network node may be or implement a SMF.

[0191] At 1201 , the method comprises triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session.

[0192] At 1202, the method comprises receiving indication from an access management function to replace the second allowed networks slice by at least one third network slice.

[0193] At 1203, the method comprises providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

[0194] Fig. 13 shows an example format of an IE for mapping between S-NSSAI to be replaced and an alternative S-NSSAI as described with reference to Figs. 10 to 12.

[0195] The time validity of each of the alternative S-NSSAIs may be included in the Alternative NSSAI IE sent to the UE. In that way, UE can make automated decisions and switch to the next alternative S-NSSAI without needing the updated information from the network.

[0196] Fig. 14 shows a flowchart of an example method where an availably time period (or time validity) is included in updated information. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a UE.

[0197] At 1401 , the method comprises receiving information from a network indicating a first allowed network slice.

[0198] At 1402, the method comprises establishing a first protocol data unit session using the first allowed network slice.

[0199] At 1403, the method comprises receiving further information from the network indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice.

[0200] At 1404, the method comprises mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice based on the further information.

[0201] At 1405, the method comprises receiving information to trigger the replacement of first allowed network slice by the second allowed network slice.

[0202] At 1406, the method comprises replacing the first allowed network slice by the second allowed network slice for the PDU session.

[0203] At 1407, the method comprises determining that the second network slice is becoming unavailable based on the received availability time period for the second allowed network slice.

[0204] At 1408, the method comprises triggering, based on the determining, the replacement of the second network slice for the PDU session using the at least one third allowed network slice.

[0205] Fig. 15 shows a flowchart of an example method. The method may be performed at an apparatus. The apparatus may comprise or be comprised in a network node. The network node may be or implement a network function such as AMF or SMF.

[0206] At 1501 , the method comprises providing information to a user equipment indicating a first allowed network slice.

[0207] At 1502, the method comprises establishing a first protocol data unit session with the user equipment using the first allowed network slice.

[0208] At 1503, the method comprises providing further information to the user equipment indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice.

[0209] At 1504, the method comprises triggering the replacement of the first allowed networkslice by the second allowed network slice.

[0210] At 1505, the method comprises receiving, from the user equipment, a request to replace the second allowed network slice using the at least one third allowed network slice.

[0211] Fig. 16 shows a flowchart of an example method.

[0212] At 1601 , the method comprises providing information to a user equipment indicating a first allowed network slice.

[0213] At 1602, the method comprises establishing a first protocol data unit session with the user equipment using the first allowed network slice.

[0214] At 1603, the method comprises providing further information to the user equipment indicating a second allowed network slice, an availability time period for the second allowed network slice, at least one third allowed network slice and an availability time period for each at least one third allowed network slice, and information for mapping each of the second allowed network slice and at least one third allowed network slice to the first network slice.

[0215] At 1604, the method comprises triggering the replacement of the first allowed network slice by the second allowed network slice.

[0216] At 1605, the method comprises receiving, from the user equipment, a request to establish a PDU session using the at least one third allowed network slice.

[0217] Validity time (also referred to as an availability time period) may be included in the Alternative NSSAI IE as an extension to the example formats shown in Figs. 8 and 13.

[0218] The UE can use a particular slice based on this timer and select the next one, once the timer expires. This is an example of determining that the second network slice is becoming unavailable based on the received availability time period for the second allowed network slice, triggering, based on the determining, the replacement of the second network slice for the PDU session using the at least one third allowed network slice.

[0219] In some scenarios, the network may know in advance how long the slice will be available (e.g., event, match, gaming session). The timing can be obtained / updated from the Application Function as an option.

[0220] The UE may provide indication to the network of the time that the at least one third allowed network slice is to be used for establishing the second protocol data unit session. For example, a UE can signal the time that the requested slice needs to be used. In this example, timing for each of the slices is provided by the network and the UE can signal which slice to be used depending on the remaining time. Methods as described with reference to Figs. 14 to 16 may be described as a UE based behavior where the UE selects the alternative slice to be used.

[0221] Synchronization between the UE and the AMF is needed in order to align the used alternative slice (e.g., UE could use UE triggered PDU Session Modification procedure to update from one alternative slice to another if the SMF indicated support for both slices.)

[0222] Fig. 17 shows an example format of an Extended Alternative NSSAI IE that includesthe mapping between the replaced slice and multiple alternative slices along with their corresponding time availability timer.

[0223] The methods as described above may provide solutions to resolve the issue during the network slice replacement procedure where the alternative slice, i.e., the slice used by the network as replacement for the original replaced slice, becomes unavailable, e.g., due to time expiration or due to congestion, while the slice original replaced slice is still not available\ maintaining seamless operation for the PDU session of the UE while switching among the different slices. Definition of the standard (currently missing) procedure / behavior in the specification both for the network and the UE when the alternative slice is not available.

[0224] Update to alternative slice(s) list by replacing the non-available alternative slice with available alternative slice.

[0225] Fig. 18 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof). In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof).

[0226] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with embodiments described herein.

[0227] As used herein, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0228] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may, for example, be at least in part external to apparatus 10 but accessible to apparatus 10.

[0229] The instructions 15 may be comprised in a computer readable medium or a non-tran- sitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM).

[0230] For example, the apparatus 10 is a terminal device, such as a UE. As another example, the apparatus is comprised in such a terminal device, e.g. as a chipset configured to control the terminal device. The apparatus 10 may be caused or configured or comprise means to perform at least the method of Figs. 5, 10 or 14 and / or any one or more of the embodiments described herein.

[0231] As another example, the apparatus 10 is a network entity. In another embodiment, the apparatus is comprised in such a network entity, e.g. as a chipset configured to control the network entity. The apparatus 10 may be caused or configured or comprise means to perform at least the method of Figs. 6, 7, 11 , 12, 15 or 16 and / or any one or more of the embodiments described herein.

[0232] The apparatus may comprise one or more entities of any of protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity ora PHY entity. In some embodiments, the entity is configured to perform at least the method of Figs. 6, 7, 11 , 12, 15 or 16, and / or any one or more of the embodiments described.

[0233] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0234] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0235] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware componentsof the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof). As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C.

[0236] Even though this disclosure has been described above with reference to non-limiting and illustrative examples according to the accompanying figures, it is clear that the scope of this disclosure is not restricted thereto - but can be modified in many different ways. As technology advances, it will become apparent to a person skilled in art as to how the disclosure can be further implemented and / or modified in various ways. Further, it is clear to a person skilled in the art that the embodiments described herein may, but are not required to, be combined in various ways with other embodiments described herein.The following provides an example of an implementation:For HELP on using this form: comprehensive instructions can be found at http: / / www.3gpp. org / Change-Reguests.Proposed change affects: UICC appsME x~| Radio Access Network) | Core NetworkReason for change: Based on the combination of the feature of network slice replacement and the availability of the alternative slice, we can have the following 3 different scenarios (S1 , S2, S3), where, Trep: replacement period / congestion time of the replaced slice, Tait= time availability of the alternative slice:• S1 : Replacement period of the replaced slice and the alternative slice have the same time duration: Trep= Tait• S2: Replacement period of the replaced slice has a shorter time duration than the alternative slice duration: Trep< Tait and,• S3: Replacement period of the replaced slice has a longer time duration than the alternative slice duration: Trep> Tait.• By using the procedures in the current specification as explained in Section 3, both S1 and S2 work without any addition / modification to the specifications.However, S3 needs chanqes / additions to the specification since currently there is no supported behaviour:• Since the time availability of the alternative slice can be shorter than the time needed to be used as replacement, i.e., Trep> Tait, due to the alternative slice being congested itself or based on some other time constraint.• In this case, the availability of the alternative slice for the UE will stop before the expected availability of the replacement slice leaving the UE without an available slice within the network slice procedure thus requiring a certain action.• It is not always possible to know by the network before using the alternative slice as replacement slice about the specific time availability* * * Start of Change * * *4.6.2.7 Mobility management based network slice replacementThe support for network slice replacement by a UE or network is optional. If the UE and network support network slice replacement, and the AMF determines that an S-NSSAI included in the allowed NSSAI needs to be replaced with an alternative S-NSSAI, the AMF provides: a) the alternative S-NSSAI in the allowed NSSAI, if not included yet; b) the alternative S-NSSAI in the configured NSSAI, if not included yet; c) the alternative S-NSSAI in the NSAG information, if not included yet and the UE supports NSAG; and d) the alternative NSSAI including the mapping information between the S-NSSAI to be replaced and the corresponding alternative S-NSSAI, to the UE, during the generic UE configuration update procedure or during the registration procedure as follows: a) for non-roaming UE, the AMF provides the mapping information between the S-NSSAI included in the allowed NSSAI and the alternative S-NSSAI to the UE; orNOTE 1: In non-roaming scenarios, the alternative S-NSSAI does not have to be part of the subscribed S-NSSAI(s) in the UE subscription. b) for roaming UE:1) if the S-NSSAI included in the allowed NSSAI needs to be replaced (i.e. , the S-NSSAI to be replaced is part of the VPLMN S-NSSAIs), the AMF provides the mapping information between the S-NSSAI included in the allowed NSSAI and the alternative S-NSSAI to the UE; and2) if the S-NSSAI included in the mapped S-NSSAI(s) for the allowed NSSAI needs to be replaced (i.e., the S-NSSAI to be replaced is part of the HPLMN S-NSSAIs), the AMF provides the mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI to the UE.NOTE 1 A: In roaming scenarios, the alternative S-NSSAI, being part of the HPLMN S-NSSAIs does not have to be part of the subscribed S-NSSAI(s) in the UE subscription.NOTE 2: It is up to AMF local policy to determine when to provide the mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI to the UE, which can be either when the alternative S-NSSAI is available and there is no established PDU session associated with the S-NSSAI to be replaced, or when the UE has established the first PDU session associated with the S-NSSAI to be replaced.If the requested NSSAI contains alternative S-NSSAI(s) that are not subscribed S-NSSAI(s), the AMF shall verify the alternative S-NSSAI(s) based on the stored alternative NSSAI.If the alternative S-NSSAI is subject to NSSAA, the alternative S-NSSAI provided by AMF shall be part of the subscribed S-NSSAI(s) in the UE subscription. The AMF shall perform NSSAA procedure for such alternative S-NSSAI and perform network slice replacement as specified above after the NSSAA procedure for the alternative S-NSSAI is completed as success.If re-NSSAA procedure is ongoing for the S-NSSAI to be replaced, the AMF shall continue with the re- NSSAA procedure and perform network slice replacement as specified above after the re-NSSAA procedure for the S-NSSAI to be replaced is completed as success.NOTE 2A: When configuring the alternative S-NSSAI, the maximum number of S-NSSAIs defined for the allowed NSSAI and configured NSSAI in subclause 4.6.2.2 are applicable.If the AMF determines that the replaced S-NSSAI is available again, the AMF provides the updated alternative NSSAI excluding the replaced S-NSSAI and the corresponding alternative S-NSSAI to the UE during the UE configuration update procedure or during the registration procedure.If all the replaced S-NSSAI(s) in alternative NSSAI are available again, the AMF provides the alternative NSSAI with Length of Alternative NSSAI contents set to 0 in the UE configuration update procedure or registration procedure.NOTE 3 : If there is S-NSSAI location validity information for both the S-NSSAI to be replaced and the alternative S-NSSAI, the NS-AoS of the alternative S-NSSAI is the same as or larger than the NS-AoS of the S-NSSAI to be replaced.If the UE is in a cell outside the NS-AoS of the replaced S-NSSAI but within the NS-AoS of the alternative S-NSSAI, the AMF provides the updated allowed NSSAI and partially allowed NSSAI excluding the replaced S-NSSAI, if included, in the allowed NSSAI or partially allowed NSSAI during the UE configuration update procedure or during the registration procedure.If the alternative S-NSSAI is not part of the subscribed S-NSSAI(s), and: a) the replaced S-NSSAI is removed from the allowed NSSAI or the partially allowed NSSAI; or b) the replaced S-NSSAI is available again, then the AMF shall provide updated allowed NSSAI or partially allowed NSSAI excluding the alternative S-NSSAI to the UE during the UE configuration update procedure or during the registration procedure. For case a), the AMF may also provide updated configured NSSAI excluding the alternative S- NSSAI to the UE during the UE configuration update procedure or during the registration procedure. For case b), the AMF shall also provide updated configured NSSAI excluding the alternative S-NSSAI to the UE during the UE configuration update procedure or during the registration procedure.Based on SMF local configuration, if the replaced S-NSSAI is subject to NSAC or the alternative S- NSSAI is subject to NSAC or both, the SMF may perform NSAC for the replaced S-NSSAI or the alternative S-NSSAI or both.If the AMF determines that the alternative S-NSSAI currently in use for network slice replacement is not available and the replaced S-NSSAI still needs to be replaced, the AMF provides to the UE updated alternative S-NSSAI(s) during the UE configuration procedure or during the registration procedure.* * * Next Change * * *4.6.3.4 Session management based network slice replacementIf: a) the UE and network support network slice replacement; b) the UE is provided with the mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI; and c) the UE decides to establish a new PDU session with the S-NSSAI to be replaced, the UE provides both the S-NSSAI to be replaced and the alternative S-NSSAI during PDU session establishment procedure. If the timer T3584 or timer T3585 is running for the S-NSSAI to be replaced, the UE should not stop the timer during PDU session establishment procedure. If the SMF receives both the S-NSSAI to be replaced and the alternative S-NSSAI during PDU session establishment procedure, the SMF proceeds with the PDU session establishment procedure with the alternative S-NSSAI. If the PDU session establishment request is accepted, the SMF includes the alternative S-NSSAI in the PDU sessionestablishment accept message. The S-NSSAI for the established PDU session is the S-NSSAI to be replaced and the alternative S-NSSAI on the UE side.If the UE is provided with the mapping of the VPLMN S-NSSAI to a VPLMN alternative S-NSSAI, the UE provides both the VPLMN alternative S-NSSAI and the VPLMN S-NSSAI during PDU session establishment procedure. The AMF sends both VPLMN alternative S-NSSAI and VPLMN S-NSSAI to the SMF. If the UE is provided with the mapping of the HPLMN S-NSSAI to a HPLMN Alternative S- NSSAI, the UE provides both the HPLMN alternative S-NSSAI and the HPLMN S-NSSAI during PDU session establishment procedure. The AMF sends both HPLMN alternative S-NSSAI and HPLMN S- NSSAI to the SMF.If the SMF receives from the AMF an alternative S-NSSAI for existing PDU session and: a) if the SMF decides to retain the existing PDU session (i.e. the SMF can serve both the alternative S-NSSAI and the S-NSSAI to be replaced with), the SMF sends the alternative S-NSSAI to the UE during network-requested PDU session modification procedure; or b) if the SMF decides to re-activate the existing PDU session and:1) if the SSC mode of the PDU session is SSC mode 3, the SMF initiates PDU session modification procedure to trigger PDU session reactivation by the UE; or2) if the SSC mode of the PDU session is SSC mode 1 or SSC mode 2, the SMF initiates PDU session release procedure to trigger PDU session reactivation by the UE, and the UE provides both the S-NSSAI to be replaced and the alternative S-NSSAI during PDU session establishment procedure.When the replaced S-NSSAI becomes available again, if the SMF receives from the AMF the replaced S-NSSAI for the existing PDU session and: a) if the SMF decides to retain the existing PDU session (i.e. the SMF can serve the replaced S- NSSAI), the SMF sends the replaced S-NSSAI to the UE during network-requested PDU session modification procedure; or b) if the SMF decides to re-activate the existing PDU session and:1) if the SSC mode of PDU session is SSC mode 3, the SMF sends the replaced S-NSSAI to the UE during PDU session modification procedure to trigger PDU session reactivation by the UE; or2) if the SSC mode of the PDU session is SSC mode 1 or SSC mode 2, the SMF sends the replaced S-NSSAI to the UE during PDU session release procedure to trigger PDU session reactivation by the UE; and the UE provides the replaced S-NSSAI during PDU establishment procedure.If the timer T3584 or timer T3585 is running for the replaced S-NSSAI and the replaced S-NSSAI in alternative NSSAI is available and the AMF provides the updated allowed NSSAI and configured NSSAI to the UE, the UE should stop the timer.When the alternative S-NSSAI becomes unavailable during network slice replacement, if the SMF receives from the AMF the additional alternative S-NSSAI for the existing PDU session and: a) if the SMF decides to retain the existing PDU session (i.e. the SMF can serve the additional alternative S-NSSAI), the SMF sends the additional alternative S-NSSAI to the UE during network- requested PDU session modification procedure; or b) if the SMF decides to re-activate the existing PDU session and:1) if the SSC mode of PDU session is SSC mode 3, the SMF sends the additional alternative S- NSSAI to the UE during PDU session modification procedure to trigger PDU session reactivation by the UE;* * * Next Change * * *5.4.4.2 Generic UE configuration update procedure initiated by the networkThe AMF shall initiate the generic UE configuration update procedure by sending the CONFIGURATION UPDATE COMMAND message to the UE.The AMF shall in the CONFIGURATION UPDATE COMMAND message either: a) include one or more of the following parameters: 5G-GUTI, TAI list, allowed NS SAI that may include the mapped S-NSSAI(s), LADN information, extended LADN information, service area list, MICO indication, NITZ information, configured NSSAI that may include the mapped S- NSSAI(s), NSSRG information, S-NSSAI location validity information, S-NSSAI time validity information, rejected S-NSSAI(s) in the Rejected NSSAI IE or in the Extended rejected NSSAI IE, network slicing subscription change indication, operator-defined access category definitions, SMS indication, "CAG information list", UE radio capability ID, 5GS registration result, UE radio capability ID deletion indication, truncated 5G-S-TMSI configuration, T3447 value, "list of PLMN(s) to be used in disaster condition", disaster roaming wait range, disaster return wait range, PEIPS assistance information, the priority indicator, the NSAG information, alternative NSSAI, partially allowed NSSAI, partially rejected NSSAI, on-demand NSSAI, feature authorization indication, or discontinuous coverage maximum time offset; b) include the Configuration update indication IE with the Registration requested bit set to "registration requested"; or c) include a combination of both a) and b).If the UE is registering or registered for onboarding services in SNPN, the serving SNPN shall not provide the configured NSSAI, the allowed NSSAI or the rejected NSSAI to the UE.If the UE supports extended rejected NSSAI, the rejected S-NSSAI(s) shall be included in the Extended rejected NSSAI IE. Otherwise, the rejected S-NSSAI(s) shall be included in the Rejected NSSAI IE.In roaming scenarios, if the Extended rejected NSSAI IE is included in the CONFIGURATION UPDATE COMMAND message, the AMF shall provide mapped S-NSSAI(s) for the rejected NSSAI.If an acknowledgement from the UE is requested, the AMF shall indicate "acknowledgement requested" in the Acknowledgement bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message and shall start timer T3555. Acknowledgement shall be requested for all parameters except when only NITZ information is included.To initiate parameter re-negotiation between the UE and network, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message.NOTE 1 : Generic UE configuration update procedure can be initiated by the AMF for updating the emergency number list, the extended emergency number list or both by indicating "registration requested" in the Registration requested bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message to the UE.If a new allowed NSSAI information or AMF re-configuration of supported S-NSSAIs requires an AMF relocation, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE and include the Allowed NSSAI IE in the CONFIGURATION UPDATE COMMAND message.If the AMF includes a new allowed NSSAI in the CONFIGURATION UPDATE COMMAND message and the subscription information includes the NSSRG information, then the S-NSSAIs of the allowed NSSAI shall be associated with at least one common NSSRG value. If the network has pending NSSAI, the S-NSSAIs in the pending NSSAI and allowed NSSAI shall be associated with at least one common NSSRG value.If the AMF includes a new partially allowed NSSAI and the new partially allowed NSSAI requires an AMF relocation, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE and include the Partially allowed NSSAI IE in the CONFIGURATION UPDATE COMMAND message.If the AMF includes a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message and the new configured NSSAI requires an AMF relocation as specified in 3GPP TS 23.501 [8], the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE in the message.If the AMF includes a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message, the subscription information includes the NSSRG information, and the UE has set the NSSRG bit in the 5GMM capability IE of the REGISTRATION REQUEST message to: a) "NSSRG supported", then the AMF shall include the NSSRG information in the CONFIGURATION UPDATE COMMAND message; or b) "NSSRG not supported", then the configured NSSAI shall include one or more S-NSSAIs each of which is associated with all the NSSRG value(s) of the default S-NSSAI(s), or the configured NSSAI shall include, based on the indication received from the UDM as specified in3GPP TS 23.501 [8], all subscribed S-NSSAIs even if these S-NSSAIs do not share any common NSSRG value.If the AMF needs to update the NSSRG information and the UE has set the NSSRG bit to "NSSRG supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, then the AMF shall include the new NSSRG information in the CONFIGURATION UPDATE COMMAND message.If the AMF includes a new NSSRG information in the CONFIGURATION UPDATE COMMAND message and the AMF determines that the UE needs to provide a new requested NSSAI due to no NSSRG value common to all the S-NSSAI(s) of the allowed NSSAI based on the new NSSRG information, then the CONFIGURATION UPDATE COMMAND message shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE.If the UE supports S-NSSAI time validity information and the AMF needs to update the S-NSSAI time validity information, then the AMF shall include the new S-NSSAI time validity information in the CONFIGURATION UPDATE COMMAND message.If the AMF needs to update the S-NSSAI location validity information toward a UE which has set the SLVI bit to "S-NSSAI location validity information supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, then the AMF shall include the new S-NSSAI location validity information in the CONFIGURATION UPDATE COMMAND message.If the CONFIGURATION UPDATE COMMAND message is initiated only due to changes to the allowed NSSAI and these changes require the UE to initiate a registration procedure, but the AMF is unable to determine an allowed NSSAI for the UE as specified in 3GPP TS 23.501 [8], then the CONFIGURATION UPDATE COMMAND message shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE, and shall not contain any other parameters.If the slice deregistration inactivity timer has expired, the UE does not support network slice usage control and the AMF removes the on-demand S-NSSAI from the allowed NSSAI over the corresponding access type, the AMF shall include the new allowed NSSAI in the CONFIGURATION UPDATE COMMAND message.If:the AMF needs to enforce a change in the restriction on the use of enhanced coverage or use of CE mode B as described in subclause 5.3.18; or- the AMF decides to inform a UE in 5GMM-CONNECTED mode and registered for disaster roaming services, that a disaster condition is no longer applicable;NOTE 1 A: The case of the AMF triggering a generic UE configuration update procedure to inform a UE registered for disaster roaming services that a disaster condition is no longer applicable, is only applicable for a UE already in 5GMM-CONNECTED mode. the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE and "release of N 1 NAS signalling connection not required" in the Signalling connection maintain request bit of the Additional configuration indication IE in the CONFIGURATION UPDATE COMMAND message.If a network slice-specific authentication and authorization procedure for an S-NSSAI is completed as a: a) success, the AMF shall include this S-NSSAI in the allowed NSSAI over the same access of the requested S-NSSAI or in the partially allowed NSSAI over 3GPP access; or b) failure, the AMF shall include this S-NSSAI in the rejected NSSAI for the failed or revoked NSSAA with the rejection cause "S-NSSAI not available due to the failed or revoked network slice-specific authentication and authorization" over either 3 GPP access or non-3GPP access.If authorization is revoked for an S-NSSAI that is in the current allowed NSSAI for an access type, the AMF shall: a) provide a new allowed NSSAI to the UE, excluding the S-NSSAI for which authorization is revoked; and b) provide a new rejected NSSAI for the failed or revoked NSSAA, including the S-NSSAI in the rejected NSSAI for which the authorization is revoked, with the rejection cause "S-NSSAI not available due to the failed or revoked network slice-specific authentication and authorization".The allowed NSSAI, the partially allowed NSSAI and the rejected NSSAI shall be included in the CONFIGURATION UPDATE COMMAND message to reflect the result of the procedures subject to network slice-specific authentication and authorization.NOTE 2: If there are multiple S-NSSAIs subject to network slice-specific authentication and authorization, it is implementation specific if the AMF informs the UE about the outcome of the procedures in one or more CONFIGURATION UPDATE COMMAND messages.If the AMF includes the Network slicing indication IE in the CONFIGURATION UPDATE COMMAND message with the Network slicing subscription change indication set to "Network slicing subscription changed", and changes to the allowed NSSAI require the UE to initiate a registration procedure, but the AMF is unable to determine an allowed NSSAI for the UE as specified in3GPP TS 23.501 [8], then the CONFIGURATION UPDATE COMMAND message shall additionally indicate "registration requested" in the Registration requested bit of the Configuration update indication IE and shall not include an allowed NSSAI.If EAC mode is activated for an S-NSSAI, the AMF shall perform NSAC for the S-NSSAI subject to NSAC before such S-NSSAI is included in the allowed NSSAI in the CONFIGURATION UPDATE COMMAND message. If EAC mode is deactivated for an S-NSSAI, the AMF shall perform NSAC for the S-NSSAI subject to NSAC after such S-NSSAI is included in the allowed NSSAI in the CONFIGURATION UPDATE COMMAND message.If the UE supports extended rejected NSSAI and the AMF determines that maximum number of UEs reached for one or more S-NSSAI(s) in the allowed NSSAI as specified in subclause 4.6.2.5, the AMF shall include the rejected NSSAI containing one or more S-NSSAIs with the rejection cause "S-NSSAI not available due to maximum number of UEs reached" in the Extended rejected NSSAI IE in theCONFIGURATION UPDATE COMMAND message. In addition, the AMF may include a back-off timer value for each S-NSSAI with the rejection cause "S-NSSAI not available due to maximum number of UEs reached" included in the Extended rejected NSSAI IE of the CONFIGURATION UPDATE COMMAND message. To avoid that large numbers of UEs simultaneously initiate deferred requests, the network should select the value for the backoff timer for each S-NSSAI for the informed UEs so that timeouts are not synchronised.If the UE does not indicate support for extended rejected NSSAI and the maximum number of UEs has been reached, the AMF should include the rejected NSSAI containing one or more S-NSSAIs with the rejection cause "S-NSSAI not available in the current registration area" in the Rejected NSSAI IE and should not include these S-NSSAIs in the allowed NSSAI in the CONFIGURATION UPDATE COMMAND message. In addition, the AMF may based on the network policies start a local implementation specific timer for the UE per rejected S-NSSAI and upon expiration of the local implementation specific timer, the AMF may remove the rejected S-NSSAI from the rejected NSSAI and update to the UE by initiating the generic UE configuration update procedure.NOTE 3 : Based on network policies, the AMF can include the S-NSS AI(s) for which the maximum number of UEs has been reached in the rejected NSSAI with rejection causes other than "S-NSSAI not available in the current registration area".If the UE has set the NSAG bit to "NSAG supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, the AMF may include the NSAG information IE in the CONFIGURATION UPDATE COMMAND message. Up to 4 NSAG entries are allowed to be associated with a TAI list in the NSAG information IE.NOTE 3A: How the AMF selects NSAG entries to be included in the NSAG information IE is implementation specific, e.g. take the NSAG priority and the current registration area into account.NOTE 3B: If the NSAG for the PLMN and its equivalent PLMN(s) have different associations with S-NSSAIs, then the AMF includes a TAI list for the NSAG entry in the NSAG information IE.If the UE supports network slice replacement and the AMF determines to provide the mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI to the UE, then the AMF shall include the Alternative NSSAI IE or Extended Alternative NSSAI IE, the Allowed NSSAI IE including the alternative S-NSSAI, if not included in the current allowed NSSAI, and the Configured NSSAI IE including the alternative S-NSSAI, if not included in the current configured NSSAI, in the CONFIGURATION UPDATE COMMAND message. If the AMF determines that the replaced S-NSSAI is available, then the AMF shall provide the updated alternative NSSAI excluding the replaced S-NSSAI and the corresponding alternative S-NSSAI in the Alternative NSSAI IE in the CONFIGURATION UPDATE COMMAND message. If the AMF determines that the alternative S-NSSAI is not available while the replaced S-NSSAI still needs to be replaced, then the AMF shall provide the updated alternative NSSAI list included in the Extended Alternative NSSAI IE in the CONFIGURATION UPDATE COMMAND. If the AMF determines that all the replaced S-NSSAI(s) are available, then the AMF shall provide the Alternative NSSAI IE with Length of Alternative NSSAI contents set to 0 in the CONFIGURATION UPDATE COMMAND message. If the AMF determines that the replaced S-NSSAI is not supported due to the UE moving outside of NS-AoS of the S-NSSAI while the alternative S-NSSAI is available, then the AMF shall provide the updated allowed NSSAI and partially allowed NSSAI, if available, excluding the replaced S-NSSAI, if included, in the allowed NSSAI or partially allowed NSSAI in the CONFIGURATION UPDATE COMMAND message.If the UE supports partial network slice and the AMF needs to update the partially allowed NSSAI, partially rejected NSSAI or both, then the AMF shall include the Partially allowed NSSAI IE, the Partially rejected NSSAI IE or both, in the CONFIGURATION UPDATE COMMAND message.If the UE supports network slice usage control and the AMF needs to update the on-demand NSSAI, the AMF shall include the On-demand NSSAI IE in the CONFIGURATION UPDATE COMMAND message.If the AMF needs to update the LADN information, the AMF shall include the LADN information in the LADN information IE of the CONFIGURATION UPDATE COMMAND message.If the UE supports LADN per DNN and S-NSSAI and the AMF needs to update the extended LADN information, the AMF shall include the extended LADN information in the Extended LADN information IE of the CONFIGURATION UPDATE COMMAND message.If:- the UE does not support LADN per DNN and S-NSSAI;- the UE is subscribed to the LADN DNN for a single S-NSSAI only; and- the AMF only has the extended LADN information; the AMF may decide to provide the LADN service area for that LADN DNN of the extended LADN information as the LADN information and include the LADN information in the LADN information IE of the CONFIGURATION UPDATE COMMAND message.NOTE 3C: If the LADN service area is configured per DNN and S-NSSAI, in order to serve the UEs that do not support LADN per DNN and S-NSSAI, it is recommended that the LADN DNN is only served by a single S-NSSAI.NOTE 3D: In case of the UE is subscribed to the LADN DNN for multiple S-NSSAIs, the AMF can treat this as no extended LADN information is available.NOTE 3E: The AMF allocates the LADN service area and the TAI list associated with the S- NSSAI in the partially allowed NSSAI independently, if applicable.If the UE does not support LADN per DNN and S-NSSAI and the AMF has neither the LADN information nor the extended LADN information, the AMF shall not provide any LADN information to the UE.If the AMF needs to update the "CAG information list", the AMF shall include the CAG information list IE or the Extended CAG information list IE in the CONFIGURATION UPDATE COMMAND message.NOTE 4: If the UE supports extended CAG information list, the CAG information list can be included either in the CAG information list IE or Extended CAG information list IE.If the UE does not support extended CAG information list, the CAG information list shall not be included in the Extended CAG information list IE.If the AMF needs to update the "CAG information list", the UE has an emergency PDU session, and the AMF can determine that the UE is in a) a CAG cell and none of the CAG-ID(s) supported by the CAG cell is authorized based on the "allowed CAG list" for the current PLMN in the updated "CAG information list"; or b) a non-CAG cell and the entry for the current PLMN in the updated "CAG information list" includes an "indication that the UE is only allowed to access 5GS via CAG cells"; the AMF may indicate to the SMF to perform a local release of: a) all non-emergency single access PDU sessions associated with 3 GPP access; b) all MA PDU sessions without a PDN connection established as a user-plane resource and without user plane resources established on non-3GPP access; and c) the 3 GPP access user plane resources of all those MA PDU sessions with user plane resources established on both accesses.The AMF shall not indicate to the SMF to release the emergency PDU session. If the AMF indicated to the SMF to perform a local release of: a) all single access non-emergency PDU sessions associated with 3 GPP access; b) all MA PDU sessions without a PDN connection established as a user-plane resource and without user plane resources established on non-3GPP access; and c) the 3 GPP access user plane resources of all those MA PDU sessions with user plane resources established on both accesses; the network shall behave as if the UE is registered for emergency services over 3 GPP access and shall set the emergency registered bit of the 5GS registration result IE to "Registered for emergency services" in the CONFIGURATION UPDATE COMMAND message.If the AMF is initiating the generic UE configuration update procedure to indicate to a UE which is registered for disaster roaming services, and which has an ongoing emergency PDU session, that the UE is registered for emergency services as described in subclause 4.24, the AMF shall set the emergency registered bit of the 5GS registration result IE to "Registered for emergency services" in the CONFIGURATION UPDATE COMMAND message.If the AMF:- updated the "CAG information list" to remove one or more CAG-ID(s) authorized based on the Allowed CAG list for the serving PLMN or an equivalent PLMN; or- updated the "CAG information list" to set the "indication that the UE is only allowed to access 5GS via CAG cells" for the serving PLMN or an equivalent PLMN which was not set before, then upon completion of the configuration update procedure and if the UE does not have an emergency PDU session, the AMF shall initiate the release of the N1 NAS signalling connection according to subclause 5.3.1.3.If the AMF needs to update the truncated 5G-S-TMSI configuration for a UE in NB-N1 mode using control plane CIoT 5GS optimization, the AMF shall include the Tmncated 5G-S-TMSI configuration IE in the CONFIGURATION UPDATE COMMAND message.If the AMF includes a UE radio capability ID deletion indication IE in the CONFIGURATION UPDATE COMMAND message, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE.If the AMF needs to redirect the UE to EPC as described in subclause 4.8.4A.2, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE and "release of N1 NAS signalling connection not required" in the Signalling connection maintain request bit of the Additional configuration indication IE in the CONFIGURATION UPDATE COMMAND message.If the UE is not in NB-N1 mode and the UE supports RACS, the AMF may include either a UE radio capability ID IE or a UE radio capability ID deletion indication IE in the CONFIGURATION UPDATE COMMAND message.During an established 5GMM context, the network may send none, one, or more CONFIGURATION UPDATE COMMAND messages to the UE. If more than one CONFIGURATION UPDATE COMMAND message is sent, the messages need not have the same content.Upon receipt of the result of the UUAA-MM procedure from the UAS-NF, the AMF shall include: a) the service-level-AA response with the SLAR field set to:1) "Service level authentication and authorization was successful" if the AMF detects the UUAA-MM procedure has succeeded; or2) "Service level authentication and authorization was not successful or service level authorization is revoked" if the AMF detects the UUAA-MM procedure has failed; b) if the CAA-Level UAV ID is provided by the UAS-NF, the service-level device ID with the value set to the CAA-Level UAV ID; and; c) if a pay load is received from the UAS-NF :1) the service-level-AA payload with the value set to the payload; and2) if a payload type associated with the payload is received, the service-level-AA payload type with the values set to the payload type; and3) if the payload type associated with the payload is for C2 authorization payload, the service- level-AA response with C2AR field set to either "C2 authorization was successful" or "C2 authorization was not successful or C2 authorization is revoked" according to the authorization result received from the UAS-NF; in the Service-level-AA container IE of the CONFIGURATION UPDATE COMMAND message.NOTE 5: UAS security information can be included in the UUAA payload by the USS as specified in 3GPP TS 33.256 [24B],NOTE 5A: The service-level-AA payload associated with the payload type "C2 authorization payload" can include pairing information for the direct C2 communication, or the security information as specified in TS 33.256 [24B], or both.NOTE 6: If the AMF receives the HTTP code set to "4xx" or "5xx" as specified in3 GPP TS 29.500 [20AA] or the AMF detects that the UUAA-MM failure as specified in 3GPP TS 29.256 [2 IB], then the AMF considers the UUAA-MM procedure has failed.If the AMF needs to deliver to the UE the UUAA revocation notification received from the UAS-NF, the AMF shall include the service-level-AA response with SLAR set to "Service level authentication and authorization was not successful or service level authorization is revoked" in the Service-level-AA container IE of the CONFIGURATION UPDATE COMMAND message.If the UE supports UAS services and UAS services become enabled for the UE (e.g. because of the aerial subscription becomes a part of the UE subscription data retrieved from the UDM), the AMF may include the service-level-AA service status indication with UAS field set to "UAS services enabled" in the Service-level-AA container IE of the CONFIGURATION UPDATE COMMAND message.If the UE supports MINT, the AMF may include the List of PLMNs to be used in disaster condition IE in the CONFIGURATION UPDATE COMMAND message.If the UE supports MINT, the AMF may include the Disaster roaming wait range IE in the CONFIGURATION UPDATE COMMAND message.If the UE supports MINT, the AMF may include the Disaster return wait range IE in the CONFIGURATION UPDATE COMMAND message.NOTE 7: The AMF can determine the content of the "list of PLMN(s) to be used in disaster condition", the value of the disaster roaming wait range and the value of the disaster return wait range based on the network local configuration.If the UE supports discontinuous coverage, the AMF may include the Discontinuous coverage maximum time offset IE in the CONFIGURATION UPDATE COMMAND message.If the UE supports and the network supports and accepts the use of the PEIPS assistance information, and the AMF needs to update the PEIPS assistance information, the AMF may include the PEIPS assistance information in the Updated PEIPS assistance information IE of the CONFIGURATION UPDATE COMMAND message.If the AMF needs to inform the UE that the use of access identity 1 is valid or is no longer valid, then,1) if the UE supports MPS indicator update via the UE configuration update procedure, the AMF: a) informs the UE by setting the MPS indicator bit of the Priority indicator IE to "Access identity 1 valid" or "Access identity 1 not valid" respectively, in the CONFIGURATION UPDATE COMMAND message. Based on operator policy, the AMF sets the MPS indicator bit in the CONFIGURATION UPDATE COMMAND message based on the MPS priority information in the user's subscription context obtained from the UDM; or b) indicates "registration requested" in the Registration requested bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message; or2) if the UE supports MCS indicator update via the UE configuration update procedure, the AMF: a) informs the UE by setting the MCS indicator bit of the Priority indicator IE to "Access identity 2 valid" or "Access identity 2 not valid" respectively, in the CONFIGURATION UPDATE COMMAND message. Based on operator policy, the AMF sets the MCS indicator bit in the CONFIGURATION UPDATE COMMAND message based on the MCS priority information in the user's subscription context obtained from the UDM; or b) indicates "registration requested" in the Registration requested bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message; or3) otherwise, the AMF shall indicate "registration requested" in the Registration requested bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message.If the UE has set the Reconnection to the network due to RAN timing synchronization status change (RANtiming) bit to "Reconnection to the network due to RAN timing synchronization status change supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, the AMF may include the RAN timing synchronization IE with the RecReq bit set to "Reconnection requested" in the CONFIGURATION UPDATE COMMAND message.When the UE is operating as an MBSR and its status of the MBSR authorization changes to not authorized for MB SR operation based on the UE subscription and local policy and the UE is allowed to operate as a UE, then the AMF shall include the Feature authorization indication IE in the CONFIGURATION UPDATE COMMAND message and shall set the MBSRAI field to "not authorized to operate as MBSR but allowed to operate as a UE", and the AMF can request the SMF to release the PDU session for 0AM access (see 3GPP TS 23.501 [8]) provided in the serving PLMN. When the UE that was not allowed for MBSR operation becomes to be allowed for MBSR operation based on the UE subscription and local policy, then the AMF shall include the Feature authorization indication IE in the CONFIGURATION UPDATE COMMAND message and shall set the MBSRAI field to "authorized to operate as MBSR"* * * Next Change * * *5.4.4.3 Generic UE configuration update accepted by the UEUpon receiving the CONFIGURATION UPDATE COMMAND message, the UE shall stop timer T3346 if running and use the contents to update appropriate information stored within the UE.If "acknowledgement requested" is indicated in the Acknowledgement bit of the Configuration update indication IE in the CONFIGURATION UPDATE COMMAND message, the UE shall send a CONFIGURATION UPDATE COMPLETE message.If the UE receives a new 5G-GUTI in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new 5G-GUTI as valid, the old 5G-GUTI as invalid, stop timer T3519 if running, and delete any stored SUCI; otherwise, the UE shall consider the old 5G-GUTI as valid. The UE shall provide the 5G-GUTI to the lower layer of 3GPP access if the CONFIGURATION UPDATE COMMANDmessage is sent over the non-3GPP access, and the UE is in 5GMM-REGISTERED in both 3GPP access and non-3GPP access in the same PLMN.If the UE receives a new TAI list in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new TAI list as valid and the old TAI list as invalid; otherwise, the UE shall consider the old TAI list as valid. If the registration area contains TAIs belonging to different PLMNs, which are equivalent PLMNs, and a) the UE already has stored allowed NSSAI for the current registration area, the UE shall store the allowed NSSAI for the current registration area in each of the allowed NSSAIs which are associated with each of the PLMNs in the registration area; b) the UE already has stored rejected NSSAI for the current registration area, the UE shall store the rejected NSSAI for the current registration area in each of the rejected NSSAIs which are associated with each of the PLMNs in the registration area; c) the UE already has stored rejected NSSAI for the failed or revoked NSSAA, the UE shall store the rejected NSSAI for the failed or revoked NSSAA in each of the rejected NSSAIs which are associated with each of the PLMNs in the registration area; d) the UE already has stored rejected NSSAI for the maximum number of UEs reached, the UE shall store the rejected NSSAI for the maximum number of UEs reached in each of the rejected NSSAIs which are associated with each of the PLMNs in the registration area; and e) the UE already has stored pending NSSAI, the UE shall store the pending NSSAI in each of the pending NSSAIs which are associated with each of the PLMNs in the registration area.If the UE receives a new truncated 5G-S-TMSI configuration in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new truncated 5G-S-TMSI configuration as valid and the old truncated 5G-S-TMSI configuration as invalid; otherwise, the UE shall consider the old truncated 5G-S-TMSI configuration as valid.If the UE receives a new service area list in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new service area list as valid and the old service area list as invalid; otherwise, the UE shall consider the old service area list, if any, as valid.If the UE receives new NITZ information in the CONFIGURATION UPDATE COMMAND message, the UE considers the new NITZ information as valid and the old NITZ information as invalid; otherwise, the UE shall consider the old NITZ information as valid.If the UE receives a LADN information IE in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the old LADN information as invalid and the new LADN information as valid, if any; otherwise, the UE shall consider the old LADN information as valid.If the UE receives an Extended LADN information IE in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the old extended LADN information as invalid and the new extended LADN information as valid, if any; otherwise, the UE shall consider the old extended LADN information as valid.If the UE receives a new allowed NSSAI for the associated access type in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new allowed NSSAI as valid for the associated access type, store the allowed NSSAI for the associated access type as specified in subclause 4.6.2.2 and consider the old allowed NSSAI for the associated access type as invalid; otherwise, the UE shall consider the old allowed NSSAI as valid for the associated access type.If the UE receives a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message, the UE shall consider the new configured NSSAI for the registered PLMN or SNPN as valid and the old configured NSSAI for the registered PLMN or SNPN as invalid; otherwise, the UE shall consider the old configured NSSAI for the registered PLMN or SNPN as valid. The UE shall store the newconfigured NSSAI as specified in subclause 4.6.2.2. In addition, if the CONFIGURATION UPDATE COMMAND message contains: a) an NSSRG information IE, the UE shall store the contents of the NSSRG information IE as specified in subclause 4.6.2.2. If the UE receives a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message and no NSSRG information IE, the UE shall delete any stored NSSRG information, if any, as specified in subclause 4.6.2.2;NOTE 1 : When the UE receives the NSSRG information IE, the UE may provide the NSSRG information to lower layers for the purpose of NS AG-aware cell reselection. b) an S-NSSAI location validity information IE, the UE shall store the contents of the S-NSSAI locationvalidity information IE as specified in subclause 4.6.2.2. If the UE receives a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message and no S-NSSAI location validity information IE, the UE shall delete any stored S-NSSAI location validity information, if any, as specified in subclause 4.6.2.2; c) an S-NSSAI time validity information IE, the UE shall store the contents of the S-NSSAI time validity information IE as specified in subclause 4.6.2.2. If the UE receives a new configured NSSAI in the CONFIGURATION UPDATE COMMAND message and no S-NSSAI time validity information IE, the UE shall delete any stored S-NSSAI time validity information, if any, as specified in subclause 4.6.2.2; or d) an On-demand NSSAI IE, the UE shall store the contents of the On-demand NSSAI IE as specified in subclause 4.6.2.2. If the UE receives a new Configured NSSAI IE in the CONFIGURATION UPDATE COMMAND message and no On-demand NSSAI IE, the UE shall delete any stored on-demand NSSAI as specified in subclause 4.6.2.2. The UE shall stop slice deregistration inactivity timer, if running for the S-NSSAI which is deleted from the on-demand NSSAI.If the CONFIGURATION UPDATE COMMAND message contains Partially allowed NSSAI IE the UE shall store the contents of the Partially allowed NSSAI IE as specified in subclause 4.6.2.2. If the CONFIGURATION UPDATE COMMAND message contains Partially rejected NSSAI IE the UE shall store the contents of the Partially rejected NSSAI IE as specified in subclause 4.6.2.2.If the UE receives the Network slicing indication IE in the CONFIGURATION UPDATE COMMAND message with the Network slicing subscription change indication set to "Network slicing subscription changed", the UE shall delete the network slicing information for each and every PLMN or SNPN except for the current PLMN or SNPN as specified in subclause 4.6.2.2 and remove all tracking areas from the list of "5GS forbidden tracking areas for roaming" which were added due to rejection of S-NSSAI due to "S-NSSAI not available in the current registration area".If the UE receives Operator-defined access category definitions IE in the CONFIGURATION UPDATE COMMAND message and the Operator-defined access category definitions IE contains one or more operator-defined access category definitions, the UE shall delete any operator-defined access category definitions stored for the RPLMN and shall store the received operator-defined access category definitions for the RPLMN. If the UE receives the Operator-defined access category definitions IE in the CONFIGURATION UPDATE COMMAND message and the Operator-defined access category definitions IE contains no operator-defined access category definitions, the UE shall delete any operator-defined access category definitions stored for the RPLMN. If the CONFIGURATION UPDATE COMMAND message does not contain the Operator-defined access category definitions IE, the UE shall not delete the operator-defined access category definitions stored for the RPLMN.If the UE receives the SMS indication IE in the CONFIGURATION UPDATE COMMAND message with the SMS availability indication set to: a) "SMS over NAS not available", the UE shall consider that SMS over NAS transport is not allowed by the network; andb) "SMS over NAS available", the UE may request the use of SMS over NAS transport by performing a registration procedure for mobility and periodic registration update as specified in subclause 5.5.1.3, after the completion of the generic UE configuration update procedure.If the UE receives the CAG information list IE or the Extended CAG information list IE in the CONFIGURATION UPDATE COMMAND message, the UE shall: a) replace the "CAG information list" stored in the UE with the received CAG information list IE or the Extended CAG information list IE when received in the HPLMN or EHPLMN;NOTE 2: When the UE receives the CAG information list IE or the Extended CAG information list IE in the HPLMN whose PLMN code is derived from the IMSI, the EHPLMN list is present and is not empty and the HPLMN is not present in the EHPLMN list, the UE behaves as if it receives the CAG information list IE or the Extended CAG information list IE in a VPLMN. b) replace the serving VPLMN's entry of the "CAG information list" stored in the UE with the serving VPLMN's entry of the received CAG information list IE or the Extended CAG information list IE when the UE receives the CAG information list IE or the Extended CAG information list IE in a serving PLMN other than the HPLMN or EHPLMN; orNOTE 3 : When the UE receives the CAG information list IE or the Extended CAG information list IE in a serving PLMN other than the HPLMN or EHPLMN, entries of a PLMN other than the serving VPLMN, if any, in the received CAG information list IE or the Extended CAG information list IE are ignored. c) remove the serving VPLMN's entry of the "CAG information list" stored in the UE when the UE receives the CAG information list IE or the Extended CAG information list IE in a serving PLMN other than the HPLMN or EHPLMN and the CAG information list IE or the Extended CAG information list IE does not contain the serving VPLMN's entry.The UE shall store the "CAG information list" received in the CAG information list IE or the Extended CAG information list IE as specified in annex C.If the received "CAG information list" includes an entry containing the identity of the current PLMN and the UE had set the CAG bit to "CAG supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, the UE shall operate as follows. a) If the UE receives the CONFIGURATION UPDATE COMMAND message via a CAG cell, none of the CAG-ID(s) supported by the current CAG cell is authorized based on the "Allowed CAG list" of the entry for the current PLMN in the received "CAG information list", and:1) the entry for the current PLMN in the received "CAG information list" does not include an "indication that the UE is only allowed to access 5GS via CAG cells", then the UE shall enter the state 5GMM-REGISTERED.LIMITED-SERVICE and shall search for a suitable cell according to 3GPP TS 38.304

[0028] or 3GPP TS 36.304 [25C] with the updated "CAG information list"; or2) the entry for the current PLMN in the received "CAG information list" includes an "indication that the UE is only allowed to access 5GS via CAG cells" and: i) if one or more CAG-ID(s) are authorized based on the "Allowed CAG list" of the entry for the current PLMN in the received "CAG information list", the UE shall enter the state 5GMM-REGISTERED. LIMITED-SERVICE and shall search for a suitable cell according to 3GPP TS 38.304

[0028] with the updated "CAG information list"; or ii) if no CAG-ID is authorized based on the "Allowed CAG list" of the entry for the current PLMN in the received "CAG information list" and:A) the UE does not have an emergency PDU session, then the UE shall enter the state 5GMM-REGISTERED.PLMN-SEARCH and shall apply the PLMN selection process defined in 3GPP TS 23.122 [5] with the updated "CAG information list"; orB) the UE has an emergency PDU session, then the UE shall perform a local release of all PDU sessions associated with 3 GPP access except for the emergency PDU session and enter the state 5GMM-REGISTERED.LIMITED-SERVICE; or b) If the UE receives the CONFIGURATION UPDATE COMMAND message via a non-CAG cell and the entry for the current PLMN in the received "CAG information list" includes an "indication that the UE is only allowed to access 5GS via CAG cells" and:1) if one or more CAG-ID(s) are authorized based on the "allowed CAG list" for the current PLMN in the received "CAG information list", the UE shall enter the state 5GMM-REGIS- TERED.LIMITED-SERVICE and shall search for a suitable cell according to3GPP TS 38.304

[0028] with the updated "CAG information list"; or2) if no CAG-ID is authorized based on the "Allowed CAG list" of the entry for the current PLMN in the received "CAG information lisf'and: i) the UE does not have an emergency PDU session, then the UE shall enter the state 5GMM-REGISTERED.PLMN-SEARCH and shall apply the PLMN selection process defined in 3GPP TS 23.122 [5] with the updated "CAG information list"; or ii) the UE has an emergency PDU session, then the UE shall perform a local release of all PDU sessions associated with 3 GPP access except for the emergency PDU session and enter the state 5GMM-REGISTERED.LIMITED-SERVICE.If the received "CAG information list" does not include an entry containing the identity of the current PLMN and the UE receives the CONFIGURATION UPDATE COMMAND message via a CAG cell, the UE shall enter the state 5GMM-REGISTERED.LIMITED-SERVICE and shall search for a suitable cell according to 3GPP TS 38.304

[0028] or 3GPP TS 36.304 [25C] with the updated "CAG information list".If the CONFIGURATION UPDATE COMMAND message indicates "registration requested" in the Registration requested bit of the Configuration update indication IE and: a) contains no other parameters or contains at least one of the following parameters: a new allowed NSSAI, a new partially allowed NSSAI, a new configured NSSAI, a new NSSRG information or the Network slicing subscription change indication, and:1) an emergency PDU session exists, the UE shall, after the completion of the generic UE configuration update procedure and the release of the emergency PDU session, release the existing N1 NAS signalling connection. Additionally, the UE shall: i) if any Tsor-cm timer(s) were running and have stopped, attempt to obtain service on a higher priority PLMN (see 3GPP TS 23.122 [5]); or ii) in all other cases, start a registration procedure for mobility and periodic registration update as specified in subclause 5.5.1.3; or2) no emergency PDU Session exists, the UE shall, after the completion of the generic UE configuration update procedure and the release of the existing N1 NAS signalling connection: i) if any Tsor-cm timer(s) were running and have stopped, attempt to obtain service on a higher priority PLMN (see 3GPP TS 23.122 [5]); or ii) in all other cases, start a registration procedure for mobility and periodic registration update as specified in subclause 5.5.1.3;b) a MICO indication is included without a new allowed NS SAI, a new configured NS SAI, a new NSSRG information or the Network slicing subscription change indication, the UE shall, after the completion of the generic UE configuration update procedure, start a periodic registration procedure for mobility and registration update as specified in subclause 5.5.1.3 to re-negotiate MICO mode with the network; c) an Additional configuration indication IE is included, and:1) "release of N1 NAS signalling connection not required" is indicated in the Signalling connection maintain request bit of the Additional configuration indication IE; and2) a new allowed NSSAI, a new configured NSSAI, a new NSSRG information or the Network slicing subscription change indication is not included in the CONFIGURATION UPDATE COMMAND message, the UE shall, after the completion of the generic UE configuration update procedure, start a registration procedure for mobility and periodic registration update as specified in subclause 5.5.1.3 ; or d) a UE radio capability ID deletion indication IE set to "Network-assigned UE radio capability IDs deletion requested" is included, and:1) the UE is not in NB-N1 mode;2) a new allowed NSSAI, a new configured NSSAI, a new NSSRG information or a Network slicing subscription change indication is not included; and3) the UE has set the RACS bit to "RACS supported" in the 5GMM capability IE of the REGISTRATION REQUEST message, the UE shall, after the completion of the generic UE configuration update procedure, start a registration procedure for mobility and periodic registration update as specified in subclause 5.5.1.3.The UE receiving the rejected NSSAI in the CONFIGURATION UPDATE COMMAND message takes the following actions based on the rejection cause in the rejected S-NSSAI(s):"S-NSSAI not available in the current PLMN or SNPN"The UE shall add the rejected S-NSSAI(s) in the rejected NSSAI for the current PLMN or SNPN as specified in subclause 4.6.2.2 and shall not attempt to use this S-NSSAI(s) in the current PLMN or SNPN over any access until switching off the UE, the UICC containing the USIM is removed, the entry of the "list of subscriber data" with the SNPN identity of the current SNPN is updated, or the rejected S-NSSAI(s) are removed as described in subclause 4.6.2.2."S-NSSAI not available in the current registration area"The UE shall add the rejected S-NSSAI(s) in the rejected NSSAI for the current registration area as specified in subclause 4.6.2.2 and shall not attempt to use this S-NSSAI(s) in the current registration area over the current access until switching off the UE, the UE moving out of the current registration area, the UICC containing the USIM is removed, the entry of the "list of subscriber data" with the SNPN identity of the current SNPN is updated, or the rejected S-NSSAI(s) are removed as described in subclause 4.6.2.2."S-NSSAI not available due to the failed or revoked network slice-specific authentication and authorization"The UE shall add the rejected S-NSSAI(s) in the rejected NSSAI for the failed or revoked NSSAA as specified in subclause 4.6.2.2 and shall not attempt to use this S-NSSAI in the current PLMN or SNPN over any access until switching off the UE, the UICC containing the USIM isremoved, the entry of the "list of subscriber data" with the SNPN identity of the current SNPN is updated, or the rejected S-NSSAI(s) are removed as described in subclause 4.6.1 and 4.6.2.2."S-NSSAI not available due to maximum number of UEs reached"Unless the back-off timer value received along with the S-NSSAI is zero, the UE shall add the rejected S-NSSAI(s) in the rejected NSSAI for the maximum number of UEs reached as specified in subclause 4.6.2.2 and shall not attempt to use this S-NSSAI in the current PLMN or SNPN over the current access until switching off the UE, the UICC containing the USIM is removed, the entry of the "list of subscriber data" with the SNPN identity of the current SNPN is updated, or the rejected S-NSSAI(s) are removed as described in subclauses 4.6.1 and 4.6.2.2.NOTE 4: If the back-off timer value received along with the S-NSSAI in the rejected NSSAI for the maximum number of UEs reached is zero as specified in subclause 10.5.7.4a of 3GPP TS 24.008

[0012] , the UE does not consider the S-NSSAI as the rejected S-NSSAI.If there is one or more S-NSSAIs in the rejected NSSAI with the rejection cause "S-NSSAI not available due to maximum number of UEs reached", then for each S-NSSAI, the UE shall behave as follows: a) stop the timer T3526 associated with the S-NSSAI, if running; b) start the timer T3526 with:1) the back-off timer value received along with the S-NSSAI, if back-off timer value is received along with the S-NSSAI that is neither zero nor deactivated; or2) an implementation specific back-off timer value, if no back-off timer value is received along with the S-NSSAI; and c) remove the S-NSSAI from the rejected NSSAI for the maximum number of UEs reached when the timer T3526 associated with the S-NSSAI expires.If the UE receives the NS AG information IE in the CONFIGURATION UPDATE COMMAND message, the UE shall store the NSAG information as specified in subclause 4.6.2.2.If the UE receives the Alternative NSSAI IE in the CONFIGURATION UPDATE COMMAND message, the UE shall store the alternative NSSAI as specified in subclause 4.6.2.2.If the UE receives the Extended Alternative NSSAI IE in the CONFIGURATION UPDATE COMMAND message, the UE shall store the alternative NSSAI as specified in subclause 4.6.2.2.If the UE receives the On-demand NSSAI IE in the CONFIGURATION UPDATE COMMAND message, the UE shall store the on-demand NSSAI as specified in subclause 4.6.2.2.If the UE receives a T3447 value IE in the CONFIGURATION UPDATE COMMAND message and has indicated "service gap control supported" in the REGISTRATION REQUEST, then the UE shall replace the stored T3447 value with the received value in the T3447 value IE, and if neither zero nor deactivated use the received T3447 value with the timer T3447 next time it is started. If the received T3447 value is zero or deactivated, then the UE shall stop the timer T3447 if running.If the UE is not in NB-N1 mode, the UE has set the RACS bit to "RACS supported" in the 5GMM capability IE of the REGISTRATION REQUEST message and the CONFIGURATION UPDATE COMMAND message includes: a) a UE radio capability ID deletion indication IE set to "Network-assigned UE radio capability IDs deletion requested", the UE shall delete any network-assigned UE radio capability IDs associated with the RPLMN or RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, the selected entry of the "list of subscriber data" or the selected PLMN subscription stored at the UE; orb) a UE radio capability ID IE, the UE shall store the UE radio capability ID as specified in annex C.If the UE is not currently registered for emergency services and the emergency registered bit of the 5GS registration result IE in the CONFIGURATION UPDATE COMMAND message is set to "Registered for emergency services", the UE shall consider itself registered for emergency services and shall locally release all non-emergency PDU sessions, if any.If the UE receives the service-level-AA container IE of the CONFIGURATION UPDATE COMMAND message, the UE passes it to the upper layer.NOTE 5: The service-level-AA container IE can include a service-level-AA payload of type "C2 authorization payload" that includes pairing information for the direct C2 communication, or the security information as specified in TS 33.256 [24B], or both.If the CONFIGURATION UPDATE COMMAND message includes the service-level-AA response in the Service-level-AA container IE with the SLAR field set to "Service level authentication and authorization was not successful or service level authorization is revoked", the UE shall forward the service- level-AA response to the upper layers, so the UUAA authorization data is deleted as specified in 3GPP TS 33.256 [24B],If the UE receives the List of PLMNs to be used in disaster condition IE in the CONFIGURATION UPDATE COMMAND message and the UE supports MINT, the UE shall delete the "list of PLMN(s) to be used in disaster condition" stored in the ME together with the PLMN ID of the RPLMN, if any, and may store the "list of PLMN(s) to be used in disaster condition" included in the List of PLMNs to be used in disaster condition IE in the ME together with the PLMN ID of the RPLMN.If the UE receives the Disaster roaming wait range IE in the CONFIGURATION UPDATE COMMAND message and the UE supports MINT, the UE shall delete the disaster roaming wait range stored in the ME, if any, and store the disaster roaming wait range included in the Disaster roaming wait range IE in the ME.If the UE receives the Disaster return wait range IE in the CONFIGURATION UPDATE COMMAND message and the UE supports MINT, the UE shall delete the disaster roaming wait range stored in the ME, if any, and store the disaster roaming wait range included in the Disaster roaming wait range IE in the ME.If the UE receives, the Discontinuous coverage maximum time offset IE in the CONFIGURATION UPDATE COMMAND message, the UE shall replace any previously received discontinuous coverage maximum time offset value on the same satellite NG-RAN RAT type and PLMN with the latest received timer value.If the UE receives the Updated PEIPS assistance information IE in the CONFIGURATION UPDATE COMMAND message and the UE supports NR paging subgrouping, the UE shall use the PEIPS assistance information included in the Updated PEIPS assistance information IE.If the UE receives a CONFIGURATION UPDATE COMMAND message with the MPS indicator bit in the Priority indicator IE set to "Access identity 1 valid":- via 3 GPP access; or- via non-3GPP access if the UE is registered to the same PLMN or SNPN over 3GPP access and non-3GPP access; the UE shall act as a UE with access identity 1 configured for MPS, as described in subclause 4.5.2, in all NG-RAN of the registered PLMN and its equivalent PLMNs or in the case of SNPN, as described in subclause 4.5.2A, in all NG-RAN of the registered SNPN and its equivalent SNPNs.If the UE receives a CONFIGURATION UPDATE COMMAND message with the MPS indicator bit in the Priority indicator IE set to "Access identity 1 valid":via non-3GPP access; or- via 3 GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3 GPP access; the UE shall act as a UE with access identity 1 configured for MPS, as described in subclause 4.5.2, in non-3GPP access of the registered PLMN and its equivalent PLMNs or in the case of SNPN, as described in subclause 4.5.2A, in non-3GPP access of the registered SNPN and its equivalent SNPNs.The MPS indicator bit in the Priority indicator IE provided in the CONFIGURATION UPDATE COMMAND message is valid:- in all NG-RAN of the registered PLMN and its equivalent PLMNs, or in the case of SNPN in all NG-RAN of the registered SNPN and its equivalent SNPNs, until:- the UE receives a REGISTRATION ACCEPT message with the MPS indicator bit set to "Access identity 1 not valid" or the UE receives a CONFIGURATION UPDATE COMMAND message with the MPS indicator bit of the Priority indicator IE set to "Access identity 1 not valid":- via 3 GPP access; or- via non-3GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3GPP access; or- the UE selects a non-equivalent PLMN (or in the case of SNPN, selects a non-equivalent SNPN); or- in non-3GPP access of the registered PLMN and its equivalent PLMNs, or in the case of SNPN in non-3GPP access of the registered SNPN and its equivalent SNPNs, until:- the UE receives a REGISTRATION ACCEPT message with the MPS indicator bit set to "Access identity 1 not valid" or the UE receives a CONFIGURATION UPDATE COMMAND message with the MPS indicator bit of the Priority indicator IE set to "Access identity 1 not valid":- via non-3GPP access; or- via 3 GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3GPP access; or- the UE selects a non-equivalent PLMN (or in the case of SNPN, selects a non-equiva- lentSNPN).Access identity 1 is only applicable while the UE is in N1 mode.If the UE receives a CONFIGURATION UPDATE COMMAND message with the MCS indicator bit in the Priority indicator IE set to "Access identity 2 valid":- via 3 GPP access; or- via non-3GPP access if the UE is registered to the same PLMN or SNPN over 3GPP access and non-3GPP access; the UE shall act as a UE with access identity 2 configured for MCS, as described in subclause 4.5.2, in all NG-RAN of the registered PLMN and its equivalent PLMNs or in the case of SNPN, as described in subclause 4.5.2A, in all NG-RAN of the registered SNPN and its equivalent SNPNs.If the UE receives a CONFIGURATION UPDATE COMMAND message with the MCS indicator bit in the Priority indicator IE set to "Access identity 2 valid":via non-3GPP access; or- via 3 GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3 GPP access; the UE shall act as a UE with access identity 2 configured for MCS, as described in subclause 4.5.2, in non-3GPP access of the registered PLMN and its equivalent PLMNs or in the case of SNPN, as described in subclause 4.5.2A, in non-3GPP access of the registered SNPN and its equivalent SNPNs.The MCS indicator bit in the Priority indicator IE provided in the CONFIGURATION UPDATE COMMAND message is valid:- in all NG-RAN of the registered PLMN and its equivalent PLMNs, or in the case of SNPN in all NG-RAN of the registered SNPN and its equivalent SNPNs, until:- the UE receives a REGISTRATION ACCEPT message with the MCS indicator bit set to "Access identity 2 not valid" or the UE receives a CONFIGURATION UPDATE COMMAND message with the MCS indicator bit of the Priority indicator IE set to "Access identity 2 not valid":- via 3 GPP access; or- via non-3GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3GPP access; or- the UE selects a non-equivalent PLMN (or in the case of SNPN, selects a non-equivalent SNPN); or- in non-3GPP access of the registered PLMN and its equivalent PLMNs, or in the case of SNPN in non-3GPP access of the registered SNPN and its equivalent SNPNs, until:- the UE receives a REGISTRATION ACCEPT message with the MCS indicator bit set to "Access identity 2 not valid" or the UE receives a CONFIGURATION UPDATE COMMAND message with the MCS indicator bit of the Priority indicator IE set to "Access identity 2 not valid":- via non-3GPP access; or- via 3 GPP access if the UE is registered to the same PLMN or SNPN over 3 GPP access and non-3GPP access; or- the UE selects a non-equivalent PLMN (or in the case of SNPN, selects a non-equiva- lentSNPN).Access identity 2 is only applicable while the UE is in N1 mode.If the UE supporting UAS services is not currently registered for UAS services and the CONFIGURATION UPDATE COMMAND message includes the service-level-AA service status indication in the Service-level-AA container IE with the UAS field set to "UAS services enabled", then the UE passes the service-level-AA service status indication to the upper layers.If the UE supporting the reconnection to the network due to RAN timing synchronization status change receives the RAN timing synchronization IE with the RecReq bit set to "Reconnection requested" in the CONFIGURATION UPDATE COMMAND message, the UE shall operate as specified in subclauses 5.3.1.4, 5.5.1.3.2, and 5.6.1.1.If the UE operating as MB SR receives the MBSRAI field of the Feature authorization indication IE in the CONFIGURATION UPDATE COMMAND message, the UE NAS layer informs the lower layers of the status of MB SR authorization.* * * Next Change * * *6.3.2 Network- req nested PDU session modification procedure6.3.2.1 GeneralThe purpose of the network-requested PDU session modification procedure is to enable the network to modify a PDU session, re-negotiate header compression configuration associated to a PDU session, convey a port management information container, to trigger EAS rediscovery, provide updated DNS server address(es) due to the newly selected local DNS server or the newly selected EASDF, provide updated ECS configuration information, remove joined UE from one or more multicast MBS sessions associated with a PDU session, update ATSSS parameters (e.g. ATSSS rules), update the MBS service area or the security information of multicast MBS session that the UE has joined or to inform about the result of service-level AA procedure or C2 authorization for UAS services.6.3.2.2 Network-requested PDU session modification procedure initiationIn order to initiate the network-requested PDU session modification procedure, the SMF shall create a PDU SESSION MODIFICATION COMMAND message.If the authorized QoS rules of the PDU session is modified or is marked as to be synchronised with the UE, the SMF shall set the Authorized QoS rules IE of the PDU SESSION MODIFICATION COMMAND message to the authorized QoS rules of the PDU session. The SMF shall ensure that the number of the packet filters used in the authorized QoS rules of the PDU Session does not exceed the maximum number of packet filters supported by the UE for the PDU session. The SMF may bind service data flows for which the UE has requested traffic segregation to a dedicated QoS flow for the PDU session, if possible. Otherwise the SMF may bind the service data flows to an existing QoS flow. The SMF shall use only one dedicated QoS flow for traffic segregation. If the UE has requested traffic segregation for multiple service data flows with different QoS handling, the SMF shall bind all these service data flows to a single QoS flow. If the SMF allows traffic segregation for service data flows in a QoS rule, then the SMF shall create a new authorized QoS mle for these service data flows and shall delete packet filters corresponding to these service data flows from the other authorized QoS rules.If the authorized QoS flow descriptions of the PDU session is modified or is marked as to be synchronised with the UE, the SMF shall set the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message to the authorized QoS flow descriptions of the PDU session.If SMF creates a new authorized QoS rule for a new QoS flow, then SMF shall include the authorized QoS flow description for that QoS flow in the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message, if: a) the newly created authorized QoS rules is for a new GBR QoS flow; b) the QFI of the new QoS flow is not the same as the 5QI of the QoS flow identified by the QFI; c) the new QoS flow can be mapped to an EPS bearer as specified in subclause 4.11.1 of 3GPP TS 23.502 [9]; or d) the new QoS flow is established for the PDU session used for relaying, as specified in subclause 5.6.2.1 of 3GPP TS 23.304 [6E],NOTE 0: In cases other than above listed cases, it is up to the SMF implementation to include the authorized QoS flow description of the new QoS flow for the new authorized QoS rule in the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message.If the session-AMBR of the PDU session is modified, the SMF shall set the selected Session- AMBR IE of the PDU SESSION MODIFICATION COMMAND message to the session-AMBR of the PDU session.If interworking with EPS is supported for the PDU session and if the mapped EPS bearer contexts of the PDU session is modified, the SMF shall set the Mapped EPS bearer contexts IE of the PDU SESSION MODIFICATION COMMAND message to the mapped EPS bearer contexts of the PDU session. If the association between a QoS flow and the mapped EPS bearer context is changed, the SMF shall set the EPS bearer identity parameter in Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message to the new EPS bearer identity associated with the QoS flow.NOTE 0A: The SMF can include multiple mapped EPS bearer context fields with the same EPS bearer identity in the Mapped EPS bearer contexts IE of the PDU SESSION MODIFICATION COMMAND message in cases, e.g. the packet filters need to be modified and the modification requires more than one TFT operation codes or the mapped traffic flow template needs to be modified and the modification exceeds the maximum size of the TFT IE.If the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and the PDU SESSION MODIFICATION REQUEST message includes a 5GSM capability IE, the SMF shall: a) if the RQoS bit is set to:1) "Reflective QoS supported", consider that the UE supports reflective QoS for this PDU session; or2) "Reflective QoS not supported", consider that the UE does not support reflective QoS for this PDU session; and; b) if the MH6-PDU bit is set to:1) "Multi-homed IPv6 PDU session supported", consider that this PDU session is supported to use multiple IPv6 prefixes; or2) "Multi-homed IPv6 PDU session not supported", consider that this PDU session is not supported to use multiple IPv6 prefixes.If the SMF considers that reflective QoS is supported for QoS flows belonging to this PDU session, the SMF may include the RQ timer IE set to an RQ timer value in the PDU SESSION MODIFICATION COMMAND message.If a port management information container needs to be delivered (see 3GPP TS 23.501 [8] and 3GPP TS 23.502 [9]) and the UE has set the TPMIC bit to "Transfer of port management information containers supported" in the 5 GSM capability IE, the SMF shall include a Port management information container IE in the PDU SESSION MODIFICATION COMMAND message.For a PDN connection established when in SI mode, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and a UE-requested PDU session modification procedure has not been successfully performed yet, the PDU session type is "IPv4", "IPv6", "IPv4v6" or "Ethernet" and the PDU SESSION MODIFICATION REQUEST message includes a Maximum number of supported packet filters IE, the SMF shall consider this number as the maximum number of packet filters that can be supported by the UE for this PDU session. Otherwise the SMF considers that the UE supports 16 packet filters for this PDU session.For a PDN connection established when in SI mode, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and a UE-requested PDU session modification procedure has not been successfully performed yet, the SMF shall consider that the maximum data rate per UE for userplane integrity protection supported by the UE for uplink and the maximum data rate per UE for userplane integrity protection supported by the UE for downlink are valid for the lifetime of the PDU session.For a PDN connection established when in SI mode, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and a UE-requested PDU session modification procedure has not been successfully performed yet, and the SMF determines, based on local policies or configurations in the SMF and the Always-on PDU session requested IE in the PDU SESSION MODIFICATION REQUEST message (if available), that either: a) the requested PDU session needs to be an always-on PDU session, the SMF shall include the Always-on PDU session indication IE in the PDU SESSION MODIFICATION COMMAND message and shall set the value to "Always-on PDU session required"; or b) the requested PDU session shall not be an always-on PDU session and:1) if the UE included the Always-on PDU session requested IE, the SMF shall include the Always-on PDU session indication IE in the PDU SESSION MODIFICATION COMMAND message and shall set the value to "Always-on PDU session not allowed"; or2) if the UE did not include the Always-on PDU session requested IE, the SMF shall not include the Always-on PDU session indication IE in the PDU SESSION MODIFICATION COMMAND message.For a PDN connection established when in SI mode, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure, a UE-requested PDU session modification procedure has not been successfully performed yet, the UE supports EDC and the network allows the use of EDC, then the SMF shall include the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message with the EDC usage allowed indicator.For a PDN connection established when in SI mode, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure, a UE-requested PDU session modification procedure has not been successfully performed yet, the UE supports EDC and the network requires the use of EDC, then the SMF shall include the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message with the EDC usage required indicator.If a QoS flow for URLLC is created in a PDU session and the SMF has not provided the Always-on PDU session indication IE with the value set to "Always-on PDU session required" in the UE-requested PDU session establishment procedure or a network-requested PDU session modification procedure for the PDU session, the SMF shall include the Always-on PDU session indication IE in the PDU SESSION MODIFICATION COMMAND message and shall set the value to "Always-on PDU session required".For a PDN connection, upon an inter-system change from SI mode to N1 mode, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and a UE-requested PDU session modification procedure has not been successfully performed yet, the PDU session is a single access PDU session over 3 GPP access with IP PDU session type, the SMF may decide to provide the protocol description associated with the PDU session and may include the Protocol description IE in the PDU SESSION MODIFICATION COMMAND message.If the value of the RQ timer is set to "deactivated" or has a value of zero, the UE considers that RQoS is not applied for this PDU session and remove the derived QoS rule(s) associated with the PDU session, if any.If the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure, the SMF shall set the PTI IE of the PDU SESSION MODIFICATION COMMAND message to the PTI of the PDU SESSION MODIFICATION REQUEST message received as part of the UE-requested PDU session modification procedure.If the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and the UE has included the Requested MBS container IE in the PDUSESSION MODIFICATION REQUEST message with the MBS operation set to "Join multicast MBS session", the SMF: a) shall include the TMGI for the multicast MBS session IDs that the UE is allowed to join, if any, in the Received MBS container IE, shall set the MBS decision to "MBS join is accepted" for each of those Received MBS information, may include the MBS start time to indicate the time when the multicast MBS session starts, and shall include the MBS security container in each of those Received MBS information if security protection is applied for that multicast MBS session and the control plane security procedure is used as specified in annex W.4.1.2 in3GPP TS 33.501

[0024] , and shall use separate QoS flows dedicated for multicast by including the Authorized QoS flow descriptions IE if no separate QoS flows dedicated for multicast exist or if the SMF wants to establish new QoS flows dedicated for multicast;NOTE 1 : The network determines whether security protection applies or not for the multicast MBS session as specified in 3GPP TS 33.501

[0024] , b) shall include the TMGI for multicast MBS session IDs that the UE is rejected to join, if any, in the Received MBS container IE, shall set the MBS decision to "MBS join is rejected" for each of those Received MBS information, shall set the Rejection cause for each of those Received MBS information with the reason of rejection and, if the Rejection cause is set to "multicast MBS session has not started or will not start soon", may include an MBS back-off timer value; and c) may include in the Received MBS container IE the MBS service area for each multicast MBS session and include in it the MBS TAI list, the NR CGI list or both, that identify the service area(s) for the local MBS service;NOTE 2: For an multicast MBS session that has multiple MBS service areas, the MBS service areas are indicated to the UE using MBS service announcement as described in 3GPP TS 23.247

[0053] , which is out of scope of this specification. in the PDU SESSION MODIFICATION COMMAND message. If the UE has set the Type of multicast MBS session ID to "Source specific IP multicast address" in the Requested MBS container IE for certain multicast MBS session(s) in the PDU SESSION MODIFICATION REQUEST message, the SMF shall include the Source IP address information and Destination IP address information in the Received MBS information together with the TMGI for each of those multicast MBS sessions.NOTE 3 : Including the Source IP address information and Destination IP address information in the Received MBS information in that case is to allow the UE to perform the mapping between the requested multicast MBS session ID and the provided TMGI.NOTE 4: In SNPN, TMGI is used together with NID to identify an MBS Session.If: a) the SMF wants to remove joined UE from one or more multicast MBS sessions; or b) the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure and the UE has included the Requested MBS container IE in the PDU SESSION MODIFICATION REQUEST message with the MBS operation set to "Leave multicast MBS session", the SMF shall include the multicast MBS session IDs that the UE is removed from, if any, in the Received MBS container IE in the PDU SESSION MODIFICATION COMMAND message and shall set the MBS decision to "Remove UE from multicast MBS session" for each of those Received MBS information. The SMF may include the updated MBS service area in each of the Received MBS information, if any. The SMF may delete the QoS flows associated for the multicast by including the Authorized QoS flow descriptions IE in the PDU SESSION MODIFICATION COMMAND message. If the UE is removed from multicast MBS session due to the MBS session release, the SMF shall set the Rejection cause to "multicast MBS session is released". The SMF shall include the Rejection cause for each of theReceived MBS information, if any, and set its value with the reason of removing the UE from the corresponding multicast MBS session.NOTE 5: based on operator's policy, e.g. after a locally configured time period, the SMF is allowed to trigger the removal of joined UE from an multicast MBS session when the UE moves outside all the MBS service area(s) of that multicast MBS session.If the SMF wants to update the MBS security information of an multicast MBS session that the UE has joined, the SMF shall include the corresponding multicast MBS session ID and the MBS security container in the Received MBS container IE in the PDU SESSION MODIFICATION COMMAND message, and shall set the MBS Decision to "MBS security information update" in the Received MBS information.If the SMF wants to update the MBS service area of an multicast MBS session that the UE has joined, the SMF shall include the corresponding multicast MBS session ID and the updated MBS service area in the Received MBS container IE in the PDU SESSION MODIFICATION COMMAND message, and shall set the MBS decision to "MBS service area update" in the Received MBS information.NOTE 6: The MBS service area of an multicast MBS session is also allowed to be updated to the UE using the MBS service announcement as described in 3GPP TS 23.247

[0053] , which is out of scope of this specification.If the network needs to update ATSSS parameters (see subclause 5.2.4 of 3GPP TS 24.193 [13B]), the SMF shall include the ATSSS container IE with the updates of ATSSS parameters in the PDU SESSION MODIFICATION COMMAND message.If the network-requested PDU session modification procedure is not triggered by a UE-requested PDU session modification procedure, the SMF shall set the PTI IE of the PDU SESSION MODIFICATION COMMAND message to "No procedure transaction identity assigned".If the selected SSC mode of the PDU session is "SSC mode 3" and the SMF requests the relocation of SSC mode 3 PDU session anchor with multiple PDU sessions as specified in 3GPP TS 23.502 [9], the SMF shall include 5GSM cause #39 "reactivation requested", in the PDU SESSION MODIFICATION COMMAND message, and may include the PDU session address lifetime in a PDU session address lifetime parameter in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message. If the selected SSC mode of the PDU session is "SSC mode 3", the S- NSSAI or the mapped S-NSSAI associated with the PDU session needs to be replaced and the SMF determines that the PDU session needs to be re-established on the alternative S-NSSAI, the SMF shall include the Alternative S-NSSAI IE and 5GSM cause #39 "reactivation requested" in the PDU SESSION MODIFICATION COMMAND message. If the selected SSC mode of the PDU session is "SSC mode 3", the replaced S-NSSAI is available and the SMF determines that the PDU session needs to be re-established on the replaced S-NSSAI, the SMF shall include and 5GSM cause #39 "reactivation requested" and include the replaced S-NSSAI in the PDU SESSION MODIFICATION COMMAND message.NOTE 7: The relocation of SSC mode 3 PDU session anchor with multiple PDU sessions can also be initiated by the SMF in case of the SMF is requested by the AMF to release the PDU session due to the network slice instance of the PDU session is changed as specified in subclause 5.15.5.3 of 3GPP TS 23.501 [8],The SMF shall send the PDU SESSION MODIFICATION COMMAND message, and the SMF shall start timer T3591 (see example in figure 6.3.2.2.1).NOTE 8: If the SMF requests the relocation of SSC mode 3 PDU session anchor with multiple PDU sessions as specified in 3GPP TS 23.502 [9], the reallocation requested indication indicating whether the SMF is to be reallocated or the SMF is to be reused is provided to the AMF.If the control plane CIoT 5GS optimization is enabled for a PDU session and the IP header compression configuration IE was included in the PDU SESSION ESTABLISHMENT REQUEST message or the PDU SESSION MODIFICATION REQUEST message, and the SMF supports control plane CIoT 5GS optimization and IP header compression for control plane CIoT 5GS optimization, the SMF may include the IP header compression configuration IE in the PDU SESSION MODIFICATION COMMAND message to re-negotiate IP header compression configuration associated to the PDU session.If the control plane CIoT 5GS optimization is enabled for a PDU session and the Ethernet header compression configuration IE was included in the PDU SESSION ESTABLISHMENT REQUEST message or the PDU SESSION MODIFICATION REQUEST message, and the SMF supports control plane CIoT 5GS optimization and Ethernet header compression for control plane CIoT 5GS optimization, the SMF may include the Ethernet header compression configuration IE in the PDU SESSION MODIFICATION COMMAND message to re-configure Ethernet header compression configuration associated with the PDU session.If the network-requested PDU session modification procedure is associated with C2 authorization procedure, the SMF shall send the PDU SESSION MODIFICATION COMMAND message by including the Service-level-AA container IE containing: a) the service-level-AA response with the value of C2AR field set to the "C2 authorization was successful"; b) if a payload is provided from the UAS-NF, the service-level-AA payload with the value set to the payload; and c) if a payload type associated with the payload is provided from the UAS-NF, the service-level-AA payload type with the value set to the payload type; and d) if the CAA-level UAV ID is provided from the UAS-NF, the service-level device ID set to the CAA-level UAV ID.NOTE 9: The C2 authorization pay load in the service-level-AA pay load can include one, some or all of the pairing information for C2 communication, and the pairing information for direct C2 communication,NOTE 9A: The C2 authorization payload in the service-level-AA payload can include the security information for C2 session as specified in TS 33.256 [24B],If the service-level-AA procedure is triggered for the established PDU session for UAS services with reauthentication purpose, and the SMF is provided by the UAS-NF with the successful UUAA-SM result, the SMF shall transmit a PDU SESSION MODIFICATION COMMAND message to the UE, where the PDU SESSION MODIFICATION COMMAND message shall include the Service-level-AA container IE containing: a) the service-level-AA response with the value of SLAR field set to "Service level authentication and authorization was successful"; b) if received the CAA-level UAV ID from the UAS-NF, the service-level device ID with the value set to the CAA-level UAV ID; c) if received a payload from the UAS-NF, the service-level-AA payload with the value set to the payload; and d) if received a payload type associated with the payload, the service-level-AA payload type with the value set to the payload type.If the SMF needs to provide new ECS configuration information to the UE and the UE has indicated support for ECS configuration information provisioning in the PDU SESSION ESTABLISHMENT REQUEST message or while in SI mode, then the SMF may include the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message with:a) at least one of ECS IPv4 Address(es), ECS IPv6 Address(es), ECS FQDN(s); b) at least one associated ECSP identifier; c) optionally, spatial validity conditions associated with the ECS address; and d) optionally, ECS authentication methods associated with the ECS address.NOTE 10:The IP address(es), FQDN(s), or both are associated with the ECSP identifier and replace previously provided ECS configuration information associated with the same ECSP identifier, if any.If the SMF needs to provide DNS server address(es) to the UE and the UE has provided the DNS server IPv4 address request, the DNS server IPv6 address request or both of them, in the PDU SESSION ESTABLISHMENT REQUEST message or a PDU SESSION MODIFICATION REQUEST message, then the SMF shall include the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message with one or more DNS server IPv4 address(es), one or more DNS server IPv6 address(es) or both of them.If the SMF needs to trigger EAS rediscovery and the UE has indicated support of the E AS rediscovery in the PDU SESSION ESTABLISHMENT REQUEST message or the PDU SESSION MODIFICATION REQUEST message, then the SMF shall include the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message: a) with the EAS rediscovery indication without indicated impact; or b) with the following:1) one or more EAS rediscovery indication(s) with impacted EAS IPv4 address range, if the UE supports EAS rediscovery indication(s) with impacted EAS IPv4 address range;2) one or more EAS rediscovery indication(s) with impacted EAS IPv6 address range, if the UE supports EAS rediscovery indication(s) with impacted EAS IPv6 address range;3) one or more EAS rediscovery indication(s) with impacted EAS FQDN, if the UE supports EAS rediscovery indication(s) with impacted EAS FQDN; or4) any combination of the above.When UE has requested P-CSCF IPv6 address or P-CSCF IPv4 address and the SMF has provided P- CSCF address(es) during the PDU session establishment procedure, if the network-requested PDU session modification procedure is triggered for P-CSCF restoration, the SMF shall include the P-CSCF IP address(es) in the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message as specified in subclause 5.8.2.2 of 3GPP TS 23.380

[0054] ,If the S-NSSAI or the mapped S-NSSAI of the PDU session needs to be replaced and the SMF determines that the PDU session needs to be retained, the SMF shall include the Alternative S-NSSAI IE in the PDU SESSION MODIFICATION COMMAND message. If the replaced S-NSSAI is available and the SMF determines that the PDU session needs to be retained, the SMF include replaced S-NSSAI in the PDU SESSION MODIFICATION COMMAND message.If the S-NSSAI or the mapped S-NSSAI of the PDU session needs to be replaced and the SMF determines that the PDU session needs to be retained, the SMF shall include the Extended Alternative S- NSSAI IE in the PDU SESSION MODIFICATION COMMAND message. If the replaced S-NSSAI is available and the SMF determines that the PDU session needs to be retained, the SMF include replaced S-NSSAI in the PDU SESSION MODIFICATION COMMAND message.If the SMF includes the authorized QoS flow descriptions and the SMF determines to provide the N3QAI to the UE, the SMF shall include the N3QAI IE in the PDU SESSION MODIFICATION COMMAND message.If the PDU session was a single access PDU session established over 3GPP access with IP PDU session type and based on operator policy the SMF determines to provide the protocol description for UL PDU set handling to the UE, the SMF may include the Protocol description IE in the PDU SESSION MODIFICATION COMMAND message.UE SMFPDU SESSION MODIFICATION COMMAND 11Figure 6.3.2.2.1 : Network-requested PDU session modification procedure* * * Next Change * * *6.3.2.3 Network-requested PDU session modification procedure accepted by the UEUpon receipt of the PDU SESSION MODIFICATION COMMAND message, if the UE provided a DNN during the PDU session establishment, the UE shall stop timer T3396, if it is running for the DNN provided by the UE. If the UE did not provide a DNN during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3396 associated with no DNN if it is running. If the PDU SESSION MODIFICATION COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3396 associated with no DNN if it is running. In an SNPN, the timer T3396 to be stopped includes: b) the timer T3396 applied for all the equivalent SNPNs, associated with the RSNPN or an equivalent SNPN, and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and a) the timer T3396 applied for the registered SNPN, associated with the RSNPN, and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.Upon receipt of the PDU SESSION MODIFICATION COMMAND message, if the UE provided an S- NSSAI and a DNN during the PDU session establishment, the UE shall stop timer T3584, if it is running for the [S-NSSAI of the PDU session, DNN] combination provided by the UE. If the UE provided a DNN and did not provide an S-NSSAI during the PDU session establishment, the UE shall stop timer T3584, if it is running for the same [no S-NSSAI, DNN] combination provided by the UE. If the UE provided an S-NSSAI and did not provide a DNN during the PDU session establishment, the UE shall stop timer T3584, if it is running for the same [S-NSSAI, no DNN] combination provided by the UE. If the UE provided neither a DNN nor an S-NSSAI during the PDU session establishment, the UE shallstop timer T3584, if it is running for the same [no S-NSSAI, no DNN] combination provided by the UE. The timer T3584 to be stopped includes: a) in a PLMN:1) the timer T3584 applied for all the PLMNs, if running; and2) the timer T3584 applied for the registered PLMN, if running; or b) in an SNPN:1) the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and2) the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.Upon receipt of the PDU SESSION MODIFICATION COMMAND message, if the UE provided an S- NSSAI during the PDU session establishment, the UE shall stop timer T3585, if it is running for the S- NSSAI of the PDU session. If the UE did not provide an S-NSSAI during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3585 associated with no S-NSSAI if it is running. The timer T3585 to be stopped includes: a) in a PLMN:1) the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION MODIFICATION COMMAND is received, if running;2) the timer T3585 applied for all the PLMNs and for both 3GPP access type and non-3GPP access type, if running;3) the timer T3585 applied for the registered PLMN and for the access over which the PDU SESSION MODIFICATION COMMAND is received, if running; and4) the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3 GPP access type, if running; or b) in an SNPN:1) the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;2) the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non- 3 GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;3) the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and4) the timer T3585 applied for the registered PLMN and for both 3GPP access type and non- 3 GPP access type, associated with the RSNPN and, if the UE supports access to an SNPNusing credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.If the PDU SESSION MODIFICATION COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3585 associated with no S-NSSAI if it is running.NOTE 1 : Upon receipt of the PDU SESSION MODIFICATION COMMAND message for a PDU session, if the UE provided a DNN (or no DNN) and an S-NSSAI (or no S-NSSAI) when the PDU session is established, timer T3396 associated with the DNN (or no DNN, if no DNN was provided by the UE) is running, and timer T3584 associated with the DNN (or no DNN, if no DNN was provided by the UE) and the S-NSSAI of the PDU session (or no S-NSSAI, if no S-NSSAI was provided by the UE) is running, then the UE stops both the timer T3396 and the timer T3584.NOTE 2: Upon receipt of the PDU SESSION MODIFICATION COMMAND message for a PDU session, if the UE provided a DNN (or no DNN) and an S-NSSAI (or no S-NSSAI) when the PDU session is established, timer T3585 associated with the S-NSSAI of the PDU session (or no S-NSSAI, if no S-NSSAI was provided by the UE) is running, and timer T3584 associated with the DNN (or no DNN, if no DNN was provided by the UE) and the S-NSSAI of the PDU session (or no S-NSSAI, if no S-NSSAI was provided by the UE) is running, then the UE stops both the timer T3585 and the timer T3584.If the PDU SESSION MODIFICATION COMMAND message includes the Authorized QoS rules IE, the UE shall process the QoS rules sequentially starting with the first QoS rule.If the PDU SESSION MODIFICATION COMMAND message includes the Authorized QoS mles IE with the Rule operation code is set to "Delete existing QoS rule" for one or more QoS rules, the UE shall delete the protocol descriptions associated with the QoS mles, if any.If the PDU SESSION MODIFICATION COMMAND message includes the Mapped EPS bearer contexts IE, the UE shall process the mapped EPS bearer contexts sequentially starting with the first mapped EPS bearer context.If the PDU SESSION MODIFICATION COMMAND message includes the Authorized QoS flow descriptions IE, the UE shall process the QoS flow descriptions sequentially starting with the first QoS flow description.The UE shall replace the stored authorized QoS rules, authorized QoS flow descriptions and session- AMBR of the PDU session with the received value(s), if any, in the PDU SESSION MODIFICATION COMMAND message.If the PDU SESSION MODIFICATION COMMAND message includes a Mapped EPS bearer contexts IE, the UE shall check each mapped EPS bearer context for different types of errors as follows:NOTE 3 : An error detected in a mapped EPS bearer context does not cause the UE to discard the Authorized QoS rules IE and Authorized QoS flow descriptions IE included in the PDU SESSION MODICATION COMMAND message, if any. a) Semantic error in the mapped EPS bearer operation:1) operation code = "Create new EPS bearer" and there is already an existing mapped EPS bearer context with the same EPS bearer identity associated with any PDU session.2) operation code = "Delete existing EPS bearer" and there is no existing mapped EPS bearer context with the same EPS bearer identity associated with the PDU session that is being modified.3) operation code = "Modify existing EPS bearer" and there is no existing mapped EPS bearer context with the same EPS bearer identity associated with the PDU session that is being modified.4) operation code = "Create new EPS bearer" or "Modify existing EPS bearer" and the resulting mapped EPS bearer context has invalid mandatory parameters or missing mandatory parameters (e.g., mapped EPS QoS parameters or traffic flow template for a dedicated EPS bearer context).In case 1, if the existing mapped EPS bearer context is associated with the PDU session that is being modified, the UE shall not diagnose an error, further process the create request and, if it was process successfully, delete the old EPS bearer context.In case 2, the UE shall not diagnose an error, further process the delete request and, if it was processed successfully, consider the mapped EPS bearer context as successfully deleted.Otherwise, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #85 "Invalid mapped EPS bearer identity". b) if the mapped EPS bearer context includes a traffic flow template, the UE shall check the traffic flow template for different types of TFT IE errors as follows:1) Semantic errors in TFT operations: i) TFT operation = "Create new TFT" when there is already an existing TFT for the EPS bearer context. ii) When the TFT operation is an operation other than "Create a new TFT" and there is no TFT for the EPS bearer context. iii) TFT operation = "Delete packet filters from existing TFT" when it would render the TFT empty. iv) TFT operation = "Delete existing TFT" for a dedicated EPS bearer context.In case iv, after sending the PDU SESSfON MODiFfCATfON COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #41 "semantic error in the TFT operation".In the other cases the UE shall not diagnose an error and perform the following actions to resolve the inconsistency:In case i, the UE shall further process the new activation request to create a new TFT and, if it was processed successfully, delete the old TFT.In case ii, the UE shall:- process the new request and if the TFT operation is "Delete existing TFT" or "Delete packet filters from existing TFT", and if no error according to items 2, 3, and 4 was detected, consider the TFT as successfully deleted;- process the new request as an activation request, if the TFT operation is "Add packet filters in existing TFT" or "Replace packet filters in existing TFT".In case iii, if the packet filters belong to a dedicated EPS bearer context, the UE shall process the new deletion request and, if no error according to items 2, 3, and 4 was detected, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5 GSM cause #41 "semantic error in the TFT operation".In case iii, if the packet filters belong to the default EPS bearer context, the UE shall process the new deletion request and if no error according to items 2, 3, and 4 was detected then delete the existing TFT, this corresponds to using match-all packet filter for the default EPS bearer context.2) Syntactical errors in TFT operations: i) When the TFT operation = "Create new TFT", "Add packet filters in existing TFT", "Replace packet fdters in existing TFT" or "Delete packet filters from existing TFT" and the packet filter list in the TFT IE is empty. ii) TFT operation = "Delete existing TFT" or "No TFT operation" with a non-empty packet filter list in the TFT IE. iii) TFT operation = "Replace packet fdters in existing TFT" when the packet filter to be replaced does not exist in the original TFT. iv) TFT operation = "Delete packet filters from existing TFT" when the packet filter to be deleted does not exist in the original TFT. v) Void. vi) When there are other types of syntactical errors in the coding of the TFT IE, such as a mismatch between the number of packet fdters subfield, and the number of packet filters in the packet filter list.In case iii, the UE shall not diagnose an error, further process the replace request and, if no error according to items 3 and 4 was detected, include the packet filters received to the existing TFT.In case iv, the UE shall not diagnose an error, further process the deletion request and, if no error according to items 3 and 4 was detected, consider the respective packet filter as successfully deleted.Otherwise, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #42 "syntactical error in the TFT operation".NOTE 3a: An implementation that strictly follows packet filter list as defined in subclause 10.5.6.12 in 3GPP TS 24.008

[0012] might not detect case 2) ii).3) Semantic errors in packet filters: i) When a packet filter consists of conflicting packet filter components which would render the packet filter ineffective, i.e. no IP packet will ever fit this packet filter. How the UE determines a semantic error in a packet filter is outside the scope of the present document. ii) When the resulting TFT, which is assigned to a dedicated EPS bearer context, does not contain any packet filter applicable for the uplink direction among the packet filters created on request from the network.After sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #44 "semantic errors in packet filter(s)".4) Syntactical errors in packet filters:i) When the TFT operation = "Create new TFT", "Add packet filters to existing TFT", or "Replace packet filters in existing TFT" and two or more packet filters in the resultant TFT would have identical packet filter identifiers. ii) When the TFT operation = "Create new TFT", "Add packet filters to existing TFT" or "Replace packet filters in existing TFT", and two or more packet filters among all TFTs associated with this PDN connection would have identical packet filter precedence values. iii) When there are other types of syntactical errors in the coding of packet filters, such as the use of a reserved value for a packet filter component identifier.In case i, if two or more packet filters with identical packet filter identifiers are contained in the new request, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #45 "syntactical error in packet filter(s)". Otherwise, the UE shall not diagnose an error, further process the new request and, if it was processed successfully, delete the old packet filters which have the identical packet filter identifiers.In case ii, if the old packet filters do not belong to the default EPS bearer context, the UE shall not diagnose an error, shall further process the new request and, if it was processed successfully, shall delete the old packet fdters which have identical filter precedence values.In case ii, if one or more old packet filters belong to the default EPS bearer context, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5 GSM cause #45 "syntactical errors in packet filter(s)".Otherwise, after sending the PDU SESSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #45 "syntactical error in packet filter(s)".And if a new EPS bearer identity parameter in Authorized QoS flow descriptions IE is received for a QoS flow which can be transferred to EPS, the UE shall update the association between the QoS flow and the mapped EPS bearer context, based on the new EPS bearer identity and the mapped EPS bearer contexts. If the "Delete existing EPS bearer" operation code in the Mapped EPS bearer contexts IE was received, the UE shall discard the association between the QoS flow and the corresponding mapped EPS bearer context and delete the corresponding mapped EPS bearer context.If: a) the UE detects different errors in the mapped EPS bearer contexts as described above which requires sending a PDU SESSION MODIFICATION REQUEST message to delete the erroneous mapped EPS bearer contexts; and b) optionally, if the UE detects errors in QoS rules that require to delete at least one QoS rule as described in subclause 6.3.2.4 which requires sending a PDU SESSION MODIFICATION REQUEST message to delete the erroneous QoS rules; the UE, after sending the PDU SESSION MODIFICATION COMPLETE message for the ongoing PDU session modification procedure, may send a single PDU SESSION MODIFICATION REQUEST message to delete the erroneous mapped EPS bearer contexts, and optionally to delete the erroneous QoS rules. The UE shall include a 5GSM cause IE in the PDU SESSION MODIFICATION REQUEST message.NOTE 4: The 5 GSM cause to use cannot be different from #41 "semantic error in the TFT operation", #42 "syntactical error in the TFT operation", #44 "semantic error in packet filter(s)", #45 "syntactical errors in packet filter(s)", #83 "semantic error in the QoS operation", #84 "syntactical error in the QoS operation", or #85 "Invalid mapped EPS bearer identity". The selection of a 5 GSM cause is up to UE implementation.Upon receipt of a PDU SESSION MODIFICATION COMMAND message and a PDU session ID, using the NAS transport procedure as specified in subclause 5.4.5, if the UE accepts the PDU SESSION MODIFICATION COMMAND message, the UE considers the PDU session as modified and the UE shall create a PDU SESSION MODIFICATION COMPLETE message.If the PDU SESSION MODIFICATION COMMAND message contains the PTI value allocated in the UE-requested PDU session modification procedure, the UE shall stop the timer T3581. The UE should ensure that the PTI value assigned to this procedure is not released immediately.NOTE 5: The way to achieve this is implementation dependent. For example, the UE can ensure that the PTI value assigned to this procedure is not released during the time equal to or greater than the default value of timer T3591.While the PTI value is not released, the UE regards any received PDU SESSION MODIFICATION COMMAND message with the same PTI value as a network retransmission (see subclause 7.3.1).If the selected SSC mode of the PDU session is "SSC mode 3" and the PDU SESSION MODIFICATION COMMAND message includes 5GSM cause #39 "reactivation requested", the UE can provide to the upper layers the PDU session address lifetime if received in the PDU session address lifetime parameter of the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message. After the completion of the network-requested PDU session modification procedure: a) if the PDU session is an MA PDU session:1) established over both 3GPP access and non-3GPP access, and:- the UE is registered over both 3 GPP access and non-3GPP access in the same PLMN:- the UE should re-initiate a UE-requested PDU session establishment procedure as specified in subclause 6.4.1 over the access the PDU SESSION MODIFICATION COMMAND message is received; or- the UE is registered over both 3 GPP access and non-3GPP access in different PLMNs:- the UE should re-initiate UE-requested PDU session establishment procedures as specified in subclause 6.4.1 over both accesses. The UE should re-initiate the UE-requested PDU session establishment procedure over the access the PDU SESSION MODIFICATION COMMAND message is received first; or2) established over only single access:- the UE should re-initiate a UE-requested PDU session establishment procedure as specified in subclause 6.4.1 over the access the user plane resources were established; or b) if the PDU session is a single access PDU session:- the UE should re-initiate a UE-requested PDU session establishment procedure as specified in subclause 6.4.1 over the access the PDU session was associated with; and for the re-initiated UE-requested PDU session establishment procedure(s) the UE should set a new PDU session ID different from the PDU session ID associated with the present PDU session and should set: a) the PDU session type to the PDU session type associated with the present PDU session; b) the SSC mode to the SSC mode associated with the present PDU session;c) the DNN to the DNN associated with the present PDU session; d) the S-NSSAI to:1) the S-NSSAI associated with (if available in roaming scenarios) a mapped S-NSSAI if provided in the UE-requested PDU session establishment procedure of the present PDU session; or2) the S-NSSAI received in the PDU SESSION ESTABLISHMENT ACCEPT message of the existing PDU session if the UE received the Alternative S-NSSAI IE or the Extended Alternative S-NSSAI IE in the PDU SESSION MODIFICATION COMMAND message; and e) the alternative S-NSSAI to the S-NSSAI associated with (if available in roaming scenarios) a mapped S-NSSAI if received in the Alternative S-NSSAI IE or the Extended Alternative S- NSSAI IE of the PDU SESSION MODIFICATION COMMAND message.If the UE has indicated support for CIoT 5GS optimizations and receives a small data rate control parameters container in the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message, the UE shall store the small data rate control parameters value and use the stored small data rate control parameters value as the maximum allowed limit of uplink user data for the PDU session in accordance with 3GPP TS 23.501 [8], If the UE has a previously stored small data rate control parameter value for the PDU session, the UE shall replace the stored small data rate control parameters value for the PDU session with the received small data rate control parameters value in the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message.If the UE has indicated support for CIoT 5GS optimizations and receives an additional small data rate control parameters for exception data container in the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message, the UE shall store the additional small data rate control parameters for exception data value and use the stored additional small data rate control parameters for exception data value as the maximum allowed limit of uplink exception data for the PDU session in accordance with 3GPP TS 23.501 [8], If the UE has a previously stored additional small data rate control parameters for exception data value for the PDU session, the UE shall replace the stored additional small data rate control parameters for exception data value for the PDU session with the received additional small data rate control parameters for exception data value in the Extended protocol configuration options IE in the PDU SESSION MODIFICATION COMMAND message.The UE shall include the PDU session ID of the old PDU session which is about to get released in the old PDU session ID IE of the UL NAS TRANSPORT message that transports the PDU SESSION ESTABLISHMENT REQUEST message.NOTE 6: The UE is expected to maintain the PDU session for which the PDU SESSION MODIFICATION COMMAND message including 5GSM cause #39 "reactivation requested" is received during the time indicated by the PDU session address lifetime value or until receiving an indication from upper layers (e.g. that the old PDU session is no more needed).If the selected PDU session type of the PDU session is "Unstructured", the UE supports inter-system change from N1 mode to SI mode, the UE does not support establishment of a PDN connection for the PDN type set to "non-IP" in SI mode, and the parameters list field of one or more authorized QoS flow descriptions received in the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message contains an EPS bearer identity (EBI), then the UE shall locally remove the EPS bearer identity (EBI) from the parameters list field of such one or more authorized QoS flow descriptions. After sending the PDU SESSION MODIFICATION COMPLETE message for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #85 "Invalid mapped EPS bearer identity".If the selected PDU session type of the PDU session is "Ethernet", the UE supports inter-system change from N 1 mode to S 1 mode, the UE does not support establishment of a PDN connection for the PDNtype set to "non-IP" in SI mode, the UE, the network or both of them do not support Ethernet PDN type in SI mode, and the parameters list field of one or more authorized QoS flow descriptions received in the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message contains an EPS bearer identity (EBI), the UE shall locally remove the EPS bearer identity (EBI) from the parameters list field of such one or more authorized QoS flow descriptions. After sending the PDU SESSION MODIFICATION COMPLETE message for the ongoing PDU session modification procedure, the UE shall initiate a PDU session modification procedure by sending a PDU SESSION MODIFICATION REQUEST message to delete the mapped EPS bearer context with 5GSM cause #85 "Invalid mapped EPS bearer identity".For a UE which is registered for disaster roaming services and for a PDU session which is not a PDU session for emergency services: a) if the parameters list field of one or more authorized QoS flow descriptions received in the Authorized QoS flow descriptions IE of the PDU SESSION MODIFICATION COMMAND message contains an EPS bearer identity (EBI), then the UE shall locally remove the EPS bearer identity (EBI) from the parameters list field of such one or more authorized QoS flow descriptions; and b) the UE shall locally delete the contents of the Mapped EPS bearer contexts IE if it is received in the PDU SESSION MODIFICATION COMMAND message.If the Always-on PDU session indication IE is included in the PDU SESSION MODIFICATION COMMAND message and: a) the value of the IE is set to "Always-on PDU session required", the UE shall consider the established PDU session as an always-on PDU session; or b) the value of the IE is set to "Always-on PDU session not allowed", the UE shall not consider the established PDU session as an always-on PDU session.If the UE does not receive the Always-on PDU session indication IE in the PDU SESSION MODIFICATION COMMAND message: a) if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure upon an inter-system change from SI mode to N1 mode for a PDN connection established when in S 1 mode, the UE shall not consider the modified PDU session as an always-on PDU session; or b) otherwise:1) if the UE has received the Always-on PDU session indication IE with the value set to "Always-on PDU session required" for this PDU session, the UE shall consider the PDU session as an always-on PDU session; or2) otherwise the UE shall not consider the PDU session as an always-on PDU session.If the PDU SESSION MODIFICATION COMMAND message contains a Port management information container IE, the UE shall forward the contents of the Port management information container IE to the DS-TT (see 3GPP TS 23.501 [8] and 3GPP TS 23.502 [9]).If the UE receives a Serving PLMN rate control IE in the PDU SESSION MODIFICATION COMMAND message, the UE shall store the Serving PLMN rate control IE value, replacing any existing value, and use the stored serving PLMN rate control value as the maximum allowed limit of uplink control plane user data for the corresponding PDU session in accordance with 3GPP TS 23.501 [8],If the PDU SESSION MODIFICATION COMMAND message includes the Received MBS container IE, for each of the Received MBS informations:a) if MBS decision is set to "MBS join is accepted", the UE shall consider that it has successfully joined the multicast MBS session. The UE shall store the received TMGI and shall use it for any further operation on that multicast MBS session. The UE shall store the received MBS service area associated with the received TMGI, if any, and provide the received TMGI to lower layers. The UE may provide the MBS start time if it is included in the Received MBS information to upper layers; b) if MBS decision is set to "MBS join is rejected", the UE shall consider the requested join as rejected. The UE shall store the received MBS service area associated with the received TMGI, if any. If the received Rejection cause is set to "User is outside of local MBS service area", the UE shall not request to join the same multicast MBS session if neither current TAI nor CGI of the current cell is part of the received MBS service area. If the received Rejection cause is set to "multicast MBS session has not started or will not start soon" and an MBS back-off timer value is included with value that indicates neither zero nor deactivated, the UE shall start a back-off timer T3587 with the value provided in the MBS back-off timer value for the received TMGI, and shall not attempt to join the multicast MBS session with the same TMGI, the Source IP address information of the TMGI, or the Destination IP address information of the TMGI until the expiry of T3587. If the MBS back-off timer value indicates that this timer is deactivated, the UE shall not attempt to join the multicast MBS session with the same TMGI until the UE is switched off, the USIM is removed, or the entry in the "list of subscriber data" for the current SNPN is updated. If the MBS back-off timer value indicates zero, the UE may attempt to join the MBS session with the same TMGI; c) if the MBS decision is set to "Remove UE from multicast MBS session", the UE shall consider that it has successfully left the multicast MBS session, and if the received Rejection cause is set to "multicast MBS session is released", the UE shall consider the multicast MBS session as released. Then the UE shall indicate to lower layers to delete the stored TMGI; d) if the MBS decision is set to "MBS service area update", the UE shall store the received MBS service area associated with the received TMGI and replace the current MBS service area with the received one. or e) if the MBS decision is set to "MBS security information update", the UE shall replace the current MBS security information with the MBS security information received in the MBS security container associated with the received TMGI.If the UE has indicated support for ECS configuration information provisioning in the SESSION ESTABLISHMENT REQUEST message or while in SI mode, then upon receiving a) one or more ECS IPv4 address(es), ECS IPv6 address(es), ECS FQDN(s); b) one or more associated ECSP identifier(s); c) optionally spatial validity conditions associated with the ECS address; and d) optionally, ECS authentication methods associated with the ECS address. in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message, then the UE shall pass them to the upper layers.If the UE supports receiving DNS server addresses in protocol configuration options and receives one or more DNS server IPv4 address(es), one or more DNS server IPv6 address(es) or both of them, in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message, then the UE shall pass the received DNS server IPv4 address(es), if any, and the received DNS server IPv6 address(es), if any, to upper layers.NOTE 7: The received DNS server address(es) replace previously provided DNS server address(es), if any.If the UE supports the EAS rediscovery and receives:a) the EAS rediscovery indication without indicated impact; or b) the following:1) one or more EAS rediscovery indication(s) with impacted EAS IPv4 address range, if supported by the UE;2) one or more EAS rediscovery indication(s) with impacted EAS IPv6 address range, if supported by the UE;3) one or more EAS rediscovery indication(s) with impacted EAS FQDN, if supported by the UE; or4) any combination of the above; in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message, then the UE shall pass the EAS rediscovery indication and the received impacted EAS IPv4 address range(s), if supported and included, the received EAS IPv6 address range(s), if supported and included, and the received EAS FQDN(s), if supported and included, to upper layers.NOTE 8: The upper layers handle the EAS rediscovery indication and the impacted EAS IPv4 address range(s), if any, the impacted EAS IPv6 address range(s), if any, and the received EAS FQDN(s), if any, according to 3GPP TS 23.548 [10A],Upon receipt of PDU SESSION MODIFICATION COMMAND message, if the network-requested PDU session modification procedure is triggered by a UE-requested PDU session modification procedure, the Service-level-AA container IE is included, then the UE shall forward the service-level-AA contents of the Service-level-AA container IE to the upper layers.If the UE supports EDC and receives the EDC usage allowed indicator in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message, the UE shall indicate to upper layers that network allows the use of EDC.If the UE supports EDC and receives the EDC usage required indicator in the Extended protocol configuration options IE of the PDU SESSION MODIFICATION COMMAND message, the UE shall indicate to upper layers that network requires the use of EDC.NOTE 9: Handling of indication that network allows the use of EDC or that network requires the use of EDC is specified in 3GPP TS 23.548

[0182] ,If the Alternative S-NSSAI IE is included in the PDU SESSION MODIFICATION COMMAND message, the UE shall replace the S-NSSAI or the mapped S-NSSAI associated with the PDU session according to the Alternative S-NSSAI IE. The S-NSSAI for the established PDU session shall be the S- NSSAI to be replaced and the alternative S-NSSAI on the UE side.If the Extended Alternative S-NSSAI IE is included in the PDU SESSION MODIFICATION COMMAND message, the UE shall replace the S-NSSAI or the mapped S-NSSAI associated with the PDU session according to the Extended Alternative S-NSSAI IE. The S-NSSAI for the established PDU session shall be the S-NSSAI to be replaced and the alternative S-NSSAI on the UE side.If the Protocol description IE is included in the PDU SESSION MODIFICATION COMMAND message, for each existing QoS rule, a) for the protocol description field with the value of the length of protocol description field set to 1 for the associated QoS mle, the UE shall delete any previously stored protocol description for the QoS rule indicated by the QRI field of the protocol description field; and b) for the protocol description field with the value of the length of protocol description field greater than 1 for the associated QoS rule, the UE shall, store the associated protocol description if thereis no stored protocol description or replace any previously stored protocol description with the new received protocol description when there is stored protocol description for the QoS rule.The UE may use it to identify PDUs belong to PDU sets for the uplink direction.NOTE 10: Whether and how to use the protocol description to identify PDU sets is up to the UE implementation.The UE shall transport the PDU SESSION MODIFICATION COMPLETE message and the PDU session ID, using the NAS transport procedure as specified in subclause 5.4.5.After sending the PDU SESSION MODIFICATION COMPLETE message, if the "Create new EPS bearer" operation code in the Mapped EPS bearer contexts IE was received in the PDU SESSION MODIFICATION COMMAND message and there is neither a corresponding Authorized QoS flow descriptions fE in the PDU SESSfON MODiFfCATfON COMMAND message nor an existing QoS flow description corresponding to the EPS bearer identity included in the mapped EPS bearer context, the UE shall send a PDU SESSION MODIFICATION REQUEST message including a Mapped EPS bearer contexts IE to delete the mapped EPS bearer context.After sending the PDU SESSION MODIFICATION COMPLETE message, if for the PDU session being modified, there are mapped EPS bearer context(s) but none of them is associated with the default QoS rule, the UE shall locally delete the mapped EPS bearer context(s) and shall locally delete the stored EPS bearer identity (EBI) in all the QoS flow descriptions of the PDU session, if any.If a port management information container needs to be delivered (see 3GPP TS 23.501 [8] and 3GPP TS 23.502 [9]), the UE shall include a Port management information container IE in the PDU SESSION MODIFICATION COMPLETE message.Upon receipt of a PDU SESSION MODIFICATION COMPLETE message, the SMF shall stop timer T3591 and shall consider the PDU session as modified. If the selected SSC mode of the PDU session is "SSC mode 3" and the PDU SESSION MODIFICATION COMMAND message included 5GSM cause #39 "reactivation requested", the SMF shall start timer T3593. If the PDU Session Address Lifetime value is sent to the UE in the PDU SESSION MODIFICATION COMMAND message then timer T3593 shall be started with the same value, otherwise it shall use a default value. If the PDU SESSION MODIFICATION COMPLETE message contains a Port management information container IE, the SMF shall handle the contents of the Port management information container IE as specified in 3GPP TS 23.501 [8] and 3GPP TS 23.502 [9],* * * Next Change * * *8.2.19 Configuration update command8.2.19.1 Message definitionThe CONFIGURATION UPDATE COMMAND message is sent by the AMF to the UE. See table 8.2.19.1.1.Message type: CONFIGURATION UPDATE COMMANDSignificance: dualDirection: network to UETable 8.2.19.1.1 : CONFIGURATION UPDATE COMMAND message content* * * Next Change * * *8.2.19.x Extended Alternative NSSAIThe network may include this IE to provide several alternative NSSAI to the UE upon unavailability of 5 the alternative slice currently in use for network slice replacement.* * * Next Change * * *8.3.9 PDU session modification command8.3.9.1 Message definitionThe PDU SESSION MODIFICATION COMMAND message is sent by the SMF to the UE to indicate a 0 modification of a PDU session. See table 8.3.9.1.1.Message type: PDU SESSION MODIFICATION COMMANDSignificance: dualDirection: network to UETable 8.3.9.1.1 : PDU SESSION MODIFICATION COMMAND message content5 NOTE: It is possible for networks compliant with version 15.2.1 or earlier versions of this specification to send the Mapped EPS bearer contexts IE with IEI of value "7F" for this message.* * * Next Change * * *8.3.9.x Extended Alternative NSSAIThe network may include this IE to provide several alternative NSSAI to the UE upon unavailability of the alternative slice currently in use for network slice replacement.* * * Next Change * * * 9.11.3.x Extended Alternative NSSAI IEThe purpose of the Extended Alternative NSSAI information element is to identify a list of mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI.The Alternative NSSAI information element is coded as shown in figure 9.11.3.x.1, figure 9.11.3.x.2 and table 9.11.3.X.1. The Alternative NSSAI is a type 4 information element with minimum length of 2 octets and maximum length of 146 octets.Figure 9.11.3.x.1 : Extended Alternative NSSAI information element8 7 6 5 4 3 2 1 octet 3 octet v octet v+1 octet w octet w +1 octet x* octet x+1* octet y* octet y +1*octet z*Figure 9.11.3.X.2: EntryTable 9.11.3.x.1 : Alternative NSSAI information element* * * End of Change(s) * * *

Claims

CLAIMS1 . An apparatus comprising means for: receiving information from a network indicating a first allowed network slice; establishing a first protocol data unit session using the first allowed network slice; receiving from the network the trigger for replacement of the first network slice by a second allowed network slice; triggering the replacement of the first network slice by the second network slice for the PDU session; receiving updated information from the network indicating at least one third allowed network slice; mapping the at least one third allowed network slice to the first network slice based on the updated information; and triggering the replacement of the second allowed network slice by one of the at least one third allowed network slice.

2. The apparatus according to claim 1 , wherein the first allowed network slice is a temporarily allowed network slice.

3. The apparatus according to claim 1 or claim 2, wherein the second and third allowed network slices are alternative network slices.

4. The apparatus according to any of claims 1 to 3, comprising means for: receiving the information and the updated information from a network function.

5. The apparatus according to claim 4, wherein the network function is at least one of an access and mobility function or a session management function.

6. The apparatus according to claim 4 or claim 5, comprising means for receiving the updated information in a user equipment configuration update message.

7. The apparatus according to any of claims 4 to 6, comprising means for:receiving the updated information in a protocol data unit session modification message.

8. The apparatus according to any of claims 1 to 7, comprising means for providing information to the network indicative of support for network slice replacement using a temporary available network slice replacement.

9. The apparatus according to any of claims 1 to 8, comprising means for upon receiving the updated information indicating the at least one third allowed network slice, removing the second allowed network slice from a memory of the apparatus.

10. An apparatus comprising means for: providing information to a user equipment indicating a first allowed network slice; establishing a first protocol data unit session with the user equipment using the first allowed network slice; triggering the replacement of the first allowed network slice by a second network slice for the PDU session; determining that the second allowed network slice is becoming unavailable; and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.11 . The apparatus according to claim 10, wherein the first allowed network slice is a temporarily allowed network slice.

12. The apparatus according to claim 10 or claim 11 , wherein the second and third allowed network slices are alternative network slices.

13. The apparatus according to any of claims 10 to 12, wherein the apparatus comprises an access and mobility function.

14. The apparatus according to claim 13, comprising means for providing the updated information in a user equipment configuration update message.

15. The apparatus according to any of claims 10 to 14, comprising means for receiving information from the user equipment indicative of support for network slice replacement using a temporary available network slice replacement.

16. The apparatus according to claim 10 to 15, wherein determining that the second allowed network slice is becoming unavailable comprises determining that the second allowed network slice is congested or an availability time period for the second allowed network slice has expired or is going to expire.

17. The apparatus according to claim 16, comprising means for determining to provide an indication of the at least one third allowed network slice based on load information received from a network data and analytics function.

18. A session management function comprising means for: triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session; receiving indication from an access management function to replace the second allowed networks slice by at least one third network slice; and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

19. The session management function of claim 18 comprising means for providing the updated information in a protocol data unit session modification message.

20. The apparatus according to claim 18 or claim 19, wherein the second and third allowed network slices are alternative network slices.

21. A method comprising: receiving information from a network indicating a first allowed net- work slice;establishing a first protocol data unit session using the first allowed network slice; receiving from the network the trigger for replacement of the first network slice by a second allowed network slice; triggering the replacement of the first network slice by the second network slice for the PDU session; receiving updated information from the network indicating at least one third allowed network slice; mapping the at least one third allowed network slice to the first network slice based on the updated information; and triggering the replacement of the second allowed network slice by one of the at least one third allowed network slice.

22. A method comprising: providing information to a user equipment indicating a first allowed network slice; establishing a first protocol data unit session with the user equipment using the first allowed network slice; triggering the replacement of the first allowed network slice by a second network slice for the PDU session; determining that the second allowed network slice is becoming unavailable; and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

23. A method comprising, at a session management function: triggering the replacement of a first allowed network slice by a second allowed network slice for a PDU session; receiving indication from an access management function to replace the second allowed networks slice by at least one third network slice; and providing updated information to the user equipment indicating at least one third allowed network slice, and information for mapping the at least one third allowed network slice to the first network slice.

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