Improved service continuity

Abstract

A method and apparatus for improving service continuity are disclosed. The solution comprises storing (300) information about slice remapping, which describes how a given network slice can be mapped to another network slice, receiving (302) a first message from an access node indicating that the node serves a terminal utilizing a network slice not supported by the node or that the node has received a request to serve a terminal utilizing a network slice not supported by the node, and transmitting (304) a message for controlling the connection of the terminal to a network entity responsible for session management based on the first message, the message having information about the slice remapping and / or an activity status of a packet data unit session associated with a slice not supported by the node.

Description

Technical Field

[0001] The exemplary and non-limiting embodiments of the present invention generally relate to wireless communication systems. In particular, the embodiments of the present invention relate to apparatus and methods in wireless communication networks. Background Art

[0002] Wireless telecommunications systems are constantly evolving. The need for higher data rates and higher quality of service continues. Reliability requirements are increasing, and so are the methods and means to ensure reliable connections and data throughput while minimizing transmission delays.

[0003] In communications systems, particularly those supporting multiple access nodes or base stations, handover is one of the key processes performed during connectivity for mobility. In many systems, a handover process is initiated for a user terminal based on measurement reports received from the user terminal when the reference signal received power level from a nearby node is superior to that from the serving node. The source node initiates a handover request to the target node, and upon successful handover, one or more communication links are transferred to the target node.

[0004] Evolving networks to support new services for customers. One proposed service is network slicing, which can provide connectivity, quality of service, and data processing solutions tailored to specific customer requirements. A network slice is a logical end-to-end virtual network that can be dynamically created to provide specific capabilities and features. Multiple network slices can be created on a common shared physical network infrastructure to run services that may have different requirements for latency, reliability, throughput, and mobility.

[0005] A user terminal can utilize one or more slices in its communication. To ensure smooth handover and efficient mobility between nodes, slices should be taken into account. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the present invention, a simplified overview of the present invention is presented below. This summary is not an expanded overview of the present invention. It is not intended to identify the main / critical elements of the present invention, nor is it intended to delineate the scope of the present invention. Its sole purpose is to present some concepts of the present invention in a simplified form as a prelude to the more detailed description presented later.

[0007] According to an aspect of the present invention, the apparatus of claim 1, claim 11, claim 15, and claim 18 are provided.

[0008] According to an aspect of the present invention, the methods of claim 19, claim 29, claim 33, and claim 36 are provided.

[0009] According to an aspect of the present invention, a computer program is provided comprising the instructions of claim 37, claim 38, claim 39, and claim 40.

[0010] One or more examples of implementations are described in more detail in the accompanying drawings and the following description. Other features will be apparent from the description and drawings, as well as from the claims. The embodiments and / or examples and features (if any) described in this specification that do not fall within the scope of the independent claims are to be construed as examples useful for understanding the various embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which:

[0012] Figure 1 and Figure 2 An example of a simplified system architecture for a communication system is shown;

[0013] Figure 3 、 Figure 4A 、 Figure 4B ,and Figure 4C is a flow chart illustrating some embodiments;

[0014] Figure 5 and Figure 6 is a signaling diagram illustrating some embodiments;

[0015] Figure 7 An example of an apparatus is shown. DETAILED DESCRIPTION

[0016] The following embodiments are merely examples. Although the specification may quote "one", "an", or "some" (multiple) embodiments in several places, this does not necessarily mean that each such reference is directed to the same (multiple) embodiment, or that the feature only applies to a single embodiment. The individual features of different embodiments may also be combined to provide other embodiments. In addition, the words "comprise" and "comprising" should be understood as not limiting the described embodiments to consisting only of those features mentioned, and such embodiments may also include features, structures, units, modules, etc. that are not specifically mentioned.

[0017] Some embodiments of the present invention may be applicable to: a base station, an eNodeB, a gNodeB, a distributed implementation of a base station, a network element of a communication system, a corresponding component, and / or any communication system or any combination of different communication systems supporting the required functionality.

[0018] The protocols used, standards for communication systems, servers, and user equipment, particularly in wireless communications, are evolving rapidly. Such developments may require additional changes to the embodiments. Therefore, all words and expressions should be interpreted broadly and are intended to illustrate, not to limit, the embodiments.

[0019] In the following, different exemplary embodiments will be described using a radio access architecture based on Long Term Evolution Advanced (LTE-Advanced, LTE-A) or New Radio (NR, 5G) as an example of an access architecture to which the embodiments may be applied, but the embodiments are not limited to such architectures. By suitably adjusting the parameters and procedures, the embodiments may also be applied to other kinds of communication networks with appropriate components. Some examples of other options for appropriate systems are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE, same as E-UTRA), Wireless Local Area Network (WLAN or WiFi), Worldwide Interoperability for Microwave Access (WiMAX), Personal Communications Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, Mobile Ad Hoc Networks (MANET), and Internet Protocol Multimedia Subsystem (IMS), or any combination thereof.

[0020] Figure 1 An example of a simplified system architecture is depicted, showing only some elements and functional entities, all logical units, whose implementation may differ from what is shown. Figure 1 The connections shown are logical connections; the actual physical connections may be different. It will be apparent to those skilled in the art that a system typically includes, in addition to Figure 1 Other functions and structures than those shown.

[0021] However, the embodiments are not limited to the systems given as examples, but a person skilled in the art may apply the solutions to other communication systems provided with the necessary properties.

[0022] Figure 1 The example of FIG. 1 shows a portion of an exemplary radio access network.

[0023] Figure 1Device 100 and device 102 are shown. Device 100 and device 102 can be, for example, user equipment or user terminals. Device 100 and device 102 are configured to be in wireless connection with node 104 on one or more communication channels. Node 104 is also connected to core network 110. In one example, node 104 can be an access node, such as an (e / g) node B that provides a cell or serves the equipment in the cell. In one example, node 104 can be a non-3GPP access node. The physical link from the device to the (e / g) node B is called an uplink or reverse link, and the physical link from the (e / g) node B to the device is called a downlink or forward link. It should be understood that the (e / g) node B or its functions can be implemented by using any node, host, server, or access point that is suitable for such purposes.

[0024] A communication system typically includes more than one (e / g) Node B. In this case, the (e / g) Node Bs may also be configured to communicate with each other over links (wired or wireless) designed for this purpose. These links may be used for signaling purposes. An (e / g) Node B is a computing device configured to control the radio resources of the communication system to which it is coupled. A Node B may also be referred to as a base station, access point, or any other type of interface device, including a relay station capable of operating in a wireless environment. The (e / g) Node B includes a transceiver or is coupled to a transceiver. A connection is provided from the (e / g) Node B's transceiver to an antenna unit, which establishes a bidirectional radio link to the device. The antenna unit may include multiple antennas or antenna elements. The (e / g) Node B is also connected to the core network 110 (CN or Next Generation Core NGC). Depending on the system, equivalents on the CN side may include an access and mobility management function (AMF), a session management function (SMF) for managing data connectivity for devices (user terminals), a user plane function (UPF) for providing connectivity between devices (user terminals) and the data network, etc.

[0025] A device (also referred to as user equipment, subscriber unit, user device (UE), user terminal, terminal device, etc.) represents a type of device to which resources on the air interface are allocated and assigned by the network, and therefore any features described herein with respect to a device can be implemented with a corresponding device (such as a smartphone, a wired residential gateway, or a relay node). An example of such a relay node is a layer 3 relay (self-backhaul relay) toward a base station.

[0026] Devices generally refer to devices (e.g., portable or non-portable computing devices) including wireless mobile communication devices that operate with or without a Universal Subscriber Identity Module (USIM), including but not limited to the following types of devices: mobile stations (mobile phones), smartphones, personal digital assistants (PDAs), handheld devices, devices using wireless modems (such as alarm or measurement devices), laptops and / or touchscreen computers, tablet devices, game consoles, notebook computers, and multimedia devices. It should be understood that devices can also be almost exclusively uplink-only devices, an example of which is a camera or video camera that uploads images or video clips to a network. Devices can also be devices capable of operating in an Internet of Things (IoT) network, which is a scenario in which objects are provided with the ability to transmit data over a network without human-to-human or human-to-computer interaction, such as for smart grids and connected vehicles. Devices can also utilize the cloud. In some applications, a device can include a user-portable device with a radio component (such as a watch, headphones, or glasses), with computing performed in the cloud. A device (or, in some embodiments, a Layer 3 relay node) is configured to perform one or more user device functions.

[0027] The various techniques described herein can also be applied to cyber-physical systems (CPS)—systems of cooperating computing elements that control physical entities. CPS can support the implementation and utilization of large numbers of interconnected information and communication technology (ICT) devices (sensors, actuators, processors, microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber-physical systems are a subclass of cyber-physical systems in which the physical systems in question are inherently mobile. Examples of mobile physical systems include mobile robots and electronic devices carried by humans or animals.

[0028] Furthermore, although the apparatus has been depicted as a single entity, different units, processors, and / or memory units ( Figure 1 Not all are shown) can also be implemented.

[0029] 5G supports the use of multiple-input, multiple-output (MIMO) antennas, significantly more base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperation with smaller stations, and employing various radio technologies depending on service requirements, use cases, and / or available spectrum. 5G mobile communications support a wide range of use cases and related applications, including video streaming, augmented reality, diverse data sharing methods, and various forms of machine-type applications such as (massive) machine-type communications (mMTC), including vehicle safety, diverse sensors, and real-time control. 5G is expected to have multiple radio interfaces: sub-6 GHz, cmWave, and mmWave, and can also be integrated with existing legacy radio access technologies (such as LTE). At least in the early stages, integration with LTE can be implemented as a system where macro coverage is provided by LTE, and 5G radio interface access comes from small cells via aggregation to LTE. In other words, 5G plans to support both inter-RAT operation capabilities (such as LTE-5G) and inter-RI operation capabilities (operation between radio interfaces, such as sub-6 GHz-cmWave and sub-6 GHz-cmWave-mmWave). One of the concepts being considered for use in 5G networks is network slicing, in which multiple independent and dedicated virtual subnets (network instances) can be created within the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0030] The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. Low-latency applications and services in 5G require content to be delivered close to the radio, leading to local grooming and multi-access edge computing (MEC). 5G enables analysis and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for hosting applications and services. It also has the ability to store and process content close to cellular subscribers for faster response times. Edge computing covers a wide range of technologies, such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer self-organizing networking and processing, and can also be categorized as: local cloud / fog computing and grid / mesh computing, exposed computing, mobile edge computing, cloudlets, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, the Internet of Things (massive connectivity and / or latency-critical), and critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, and healthcare applications).

[0031] The communication system can also communicate with other networks such as the public switched telephone network or the Internet 112, or utilize services provided by other network communications. The communication network can also support the use of cloud services, for example, at least part of the core network operations can be implemented as a cloud service (this is in Figure 1 114). The communication system may also include a central control entity or the like providing facilities for the networks of different operators to collaborate, for example, in spectrum sharing.

[0032] By leveraging network function virtualization (NVF) and software-defined networking (SDN), edge cloud technology can be introduced into the radio access network (RAN). Using edge cloud technology may mean that access node operations are at least partially implemented in a server, host, or node that is operably coupled to a remote radio head or base station that includes radio components. Node operations may also be distributed among multiple servers, nodes, or hosts. The application of cloud RAN architecture enables RAN real-time functions to be implemented on the RAN side (in the distributed unit DU 104), and non-real-time functions to be implemented in a centralized manner (in the centralized unit CU108).

[0033] It should also be understood that the division of labor between core network operations and base station operations may differ from LTE, or even not exist. Other technological advancements that may be utilized are big data and all-IP, which could change the way networks are built and managed. 5G (or New Radio, NR) networks are designed to support multiple layers, where MEC servers can be placed between the core and base stations or Node Bs (gNBs). It should be understood that MEC can also be applied in 4G networks.

[0034] 5G can also leverage satellite communications to enhance or supplement the coverage of 5G services, for example by providing backhaul. Possible use cases include providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers in vehicles, or ensuring service availability for critical communications and future rail / maritime / aeronautical communications. Satellite communications can leverage geostationary (GEO) satellite systems as well as low Earth orbit (LEO) satellite systems, particularly super constellations (systems with hundreds of (nano)satellites deployed). Each satellite 106 in a super constellation can cover several satellite-implemented network entities that create terrestrial cells. Terrestrial cells can be created by ground relay nodes 104 or by gNBs located on the ground or in satellites.

[0035] It will be apparent to those skilled in the art that the depicted system is merely an example of a portion of a radio access system. In practice, the system may include multiple (e / g) Node Bs, a device may have access to multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements. At least one of the (e / g) Node Bs may be a Home (e / g) Node B. Furthermore, multiple different types of radio cells and multiple radio cells may be provided within a geographical area of ​​the radio communication system. A radio cell may be a macro cell (or umbrella cell), which is a large cell typically having a diameter of up to tens of kilometers, or a smaller cell, such as a micro cell, a femto cell, or a pico cell. Figure 1 A Node B (e / g) in a cellular radio system can provide any of these types of cells. A cellular radio system can be implemented as a multi-layer network comprising several types of cells. Typically, in a multi-layer network, one access node provides one or more cells of one type, and therefore multiple Node Bs (e / g) are required to provide such a network structure.

[0036] To meet the need for improved deployment and performance of communication systems, the concept of "plug and play" (e / g) Node Bs has been introduced. Typically, a network capable of using "plug and play" (e / g) Node Bs includes, in addition to Home (e / g) Node Bs, a Home Node B Gateway, or HNB-GW ( Figure 1 (not shown). An HNB gateway (HNB-GW) is typically installed within an operator's network and can aggregate traffic from a large number of HNBs back to the core network.

[0037] Figure 2 An example of a communication system based on 5G network entities is shown. A user terminal or user equipment 200 communicates with a data network 204 via a 5G network 202. The user terminal 200 is connected to a base station or gNB 206, which provides the user terminal with connectivity to the data network 204 via one or more user plane functions 208. The user terminal 200 is also connected to a core access and mobility management function (AMF) 210, which is the control plane core connector for the (radio) access network and, from this perspective, can be considered the 5G version of the mobility management entity (MME) in LTE. The 5G network also includes a session management function (SMF) 212, which is responsible for subscriber sessions, such as session establishment, modification, and release, and a policy control function 214, which is configured to manage network behavior by providing policy rules to the control plane functions. The network also includes the network operator's operation and maintenance (O&M) unit 220.

[0038] In 5G or NR networks, the concept of session and service continuity (SSC) has been defined. Three SSC modes have been defined, namely SSC Mode 1, SSC Mode 2, and SSC Mode 3. In SSC Mode 1, the network maintains a packet data unit (PDU) session throughout the session lifetime, regardless of the mobility of the user terminal. In SSC Mode 2, the network can interrupt connectivity and release the PDU session before creating a new connectivity. In SSC Mode 3, the network does not interrupt the existing connection before creating a new connection, thereby maintaining service connectivity.

[0039] As mentioned, network slicing is the concept of slicing the network resources of the end-to-end connection between a user terminal and another endpoint in a public land mobile network (PLMN) or data network 204. Similar network slicing can also be adopted in private networks. Network slices can be understood as logical end-to-end networks that can be dynamically created and / or modified. (Multiple) networks between terminal devices can be sliced ​​from one end device to another, and these slices thus form logical pipes within (multiple) networks. User terminals can access slices over the radio interface. Each pipe / slice can serve a specific service type. Examples of different network slices / service types include, for example, eMBB (slices suitable for handling 5G enhanced mobile broadband), URLLC (slices suitable for handling ultra-reliable low-latency communications), and MIoT (slices suitable for handling massive Internet of Things). If necessary, the communication service provider (CSP) can define additional network slices / service types. A given user terminal can access multiple slices on the same access network (e.g., over the same radio interface).

[0040] Therefore, network slicing enables communication service providers to provide dedicated virtual networks on a public network infrastructure. Different virtual or logical networks can be designed to provide different network characteristics, such as different quality of service (QoS). For example, virtual networks can be customized to meet the specific needs of various applications, services, devices, customers, and / or operators.

[0041] In a system that utilizes network slicing, a single physical network or a group of networks is sliced ​​into multiple virtual networks (slices) that can support different radio access networks (RANs) or different service types running across a single RAN. Network slicing can be used to segment the core network of a cellular communication system (such as a 5G system), but can also be implemented in a RAN (such as a WLAN).

[0042] Each network slice can be optimized to provide resources and network topology for the specific services and traffic that will use that slice. Network resources can be allocated based on requirements for mobility, capacity, connectivity, and coverage so that the specific needs of each use case are met. Physical network components or resources can be shared across different network slices.

[0043] Slices are identified by Single Network Slice Assistance Information (S-NSSAI). A packet data unit (PDU) session of a user terminal utilizing a slice is associated with a single S-NSSAI. During the attachment process of the user terminal to the network, the configured NSSAI is sent from the core network to the user terminal. At each registration area update, the user terminal can indicate the requested NSSAI, which is a list of requested (multiple) S-NSSAIs. The network's AMF considers this together with the subscribed NSSAI to infer the allowed NSSAI, which is sent back to the user terminal. The allowed NSSAI represents a list of (multiple) S-NSSAIs that the user terminal is allowed to use for further requests occurring in that registration area.

[0044] The slices supported by nearby base stations or access nodes may be different. Currently, when a user terminal with a PDU session utilizing slice X running at a source node is handed over to a target node, if the target node does not support slice X, the PDU session will be released at the target node. Therefore, the service utilizing the PDU session needs to be restarted after the handover. The new PDU session will be mapped to another slice supported by the target node. However, the interruption caused by the handover and the subsequent PDU session establishment disrupts service continuity and may cause problems with the service.

[0045] In an embodiment, slice remapping is applied. Thus, a given slice X supported by a radio access node is mapped to another slice Y on a neighboring radio access node. When a user terminal having a PDU session utilizing slice X is handed over to a neighboring node that does not support slice X, slice X is at least temporarily mapped to another slice Y.

[0046] In an embodiment, the proposed slice remapping can be interpreted as a downgraded mode of the original slice. For example, given slice X is a URLLC slice, it can be remapped to slice Y, which is a universal slice. As a result, the data service of the user terminal in question is mapped to a slice of lower quality than the previously supported slice. However, the service continues without interruption. This applies to both Xn and N2 handovers performed by the user terminal.

[0047] In an embodiment, the proposed slice remapping may also occur when slice support is terminated in a node.

[0048] In an embodiment, the node may temporarily accept a user terminal PDU session for an unsupported slice while the node triggers the core network to command the user terminal to establish a new PDU session to the target slice via SSC mode 3 or SSC mode 2, and then perform removal of the PDU session for the unsupported slice as part of the allowed NSSAI for the user terminal.

[0049] Figure 3 is a flow chart illustrating an embodiment. The flow chart illustrates an example of the operation of an apparatus or network entity acting as a core access and mobility management function or AMF. It may be noted here that the terms "first" and "second" are used to identify different messages and do not imply any particular order in which the messages are transmitted.

[0050] In step 300, the apparatus is configured to store information about slice remapping, which describes how a given network slice can be mapped to another network slice.

[0051] In step 302, the apparatus is configured to receive a first message from a radio access node that the radio access node serves a terminal utilizing a network slice that is not supported by the radio access node or that the radio access node has received a request to serve a terminal utilizing a network slice that is not supported by the radio access node.

[0052] In step 304, the apparatus is configured to transmit a message for controlling the connection of the terminal to a network entity responsible for session management based on a message from the radio access node, information about slice remapping and / or an activity status of a packet data unit session associated with a slice not supported by the node.

[0053] Thus, in step 300, the apparatus is aware of a slice remapping table indicating which slice X (e.g., slice X of the source radio access node) can be remapped to which slice Y (e.g., slice Y of the target radio access node). There are several solutions for configuring this table in the apparatus.

[0054] In an embodiment, the device or AMF has obtained information about slice remapping (e.g., slice X remapped to slice Y) from the operation and maintenance unit (O&M) of the network.

[0055] In an embodiment, the device or AMF obtains information about slice remapping in a second message independent of the terminal from a radio access node before receiving the first message, where the node indicates that it serves the terminal or has received a request to serve the terminal.

[0056] In an embodiment, the apparatus or AMF is configured to receive information from a radio access node such as a NG-RAN node in a semi-static manner: during an NG-SETUP REQUEST message and a RAN CONFIGURATION UPDATE message, the NG-RAN node may include the remapping information in the message.

[0057] In an embodiment, the apparatus or AMF is configured to receive information in a dynamic manner: the remapping information for terminating slice X is sent by a radio access node such as an NG-RAN node simultaneously with the information of step 302.

[0058] Whenever the radio access node detects that it is about to serve a user terminal for which support for slice X of allowed NSSAI will not be supported or is no longer supported, it notifies a device such as the AMF at step 302.

[0059] There are various ways in which the apparatus or AMF may receive the information of step 302 from the radio access node.

[0060] The radio access node may be configured to inform the AMF that it no longer supports a given slice X, for example by one of the following mechanisms:

[0061] In an embodiment, it is assumed that a radio access node is involved in an Xn handover and detects that the target radio access node does not support slice X included in the allowed NSSAI. The radio access node notifies the AMF using an NG Path Switch Request (PSR) message including this information, for example, PSR (terminating slice X). In the case of a dynamic method of indicating slice remapping, the PSR also contains a slice remapping table or a slice remapping option for slice X (such as slice X can be remapped to slice Y).

[0062] In an embodiment, it is assumed that the radio access node is involved in an NG handover and detects that the target radio access node does not support slice X included in the allowed NSSAI. The radio access node is configured to notify the AMF using an NG handover notification message including this information, such as a handover notification (terminating slice X). In the case of applying a dynamic method of indicating slice remapping, the handover notification message also contains a slice remapping table or a slice remapping option for slice X (such as slice X can be remapped to slice Y).

[0063] In an embodiment, it is assumed that the radio access node is not involved in the handover, but for any reason, support for slice X is removed. The radio access node is configured to use the existing RAN Configuration Update message (Terminate Slice X) or the new NG message (Terminate Slice X) to notify the AMF that it no longer supports slice X. In the case of applying a dynamic way of indicating slice remapping, the above message contains a slice remapping table or a slice remapping option for slice X (such as slice X can be remapped to slice Y).

[0064] There are various ways for the device or AMF to transmit the message of step 304 to the network entity responsible for session management (such as SMF).

[0065] In an embodiment, consider the following situation: the user terminal has a PDU session for slice X, which PDU session has active resources present for the terminal device, and slice X can be remapped to slice Y according to the remapping table. The AMF sends an update message to the SMF, which includes a new indication (terminate slice X, try slice Y). The SMF then triggers the SSC Mode 3 procedure to the user terminal: NAS PDU Session Modification Command (Cause, PCO (PDU Session Address Lifetime Value)), where NAS indicates the non-access layer and PCO indicates the protocol configuration option field. In this message, the SMF can add the new (terminate slice X, try alternative slice Y) information to the user terminal so that the user terminal subsequently triggers the establishment of PDU Session 2 using slice Y (instead of slice X) as part of SSC Mode 3.

[0066] In an embodiment, consider the following case: the user terminal has a PDU session for slice X, which PDU session has no active resources for the user terminal, and slice X can be remapped to slice Y according to the remapping table: the AMF sends a delete message to the SMF, which includes a new indication (terminate slice X, try slice Y). The behavior of the SMF is the same as the above case, or it can alternatively trigger SSC mode 2 instead of SSC mode 3.

[0067] In an embodiment, consider the following situation: the user terminal has a PDU session existing for the user terminal for slice X, but slice X cannot be remapped to another slice according to the remapping table. The AMF is configured to send a delete message to the SMF to trigger the release of the PDU session.

[0068] The proposed solution also works for legacy user terminals, which are unaware of the proposed solution. A legacy user terminal, not understanding the new (Terminate Slice X, Try Alternative Slice Y) message, might first attempt to trigger PDU Session 2 again using Slice X, which would be rejected. The user terminal could then attempt to establish a new PDU Session 2 using Slice Y, following the second-priority rule of the URSP (User Equipment Routing Policy). Therefore, for legacy terminals, the process works, albeit slightly less efficiently.

[0069] Figure 4A is a flow chart illustrating an embodiment. The flow chart shows an example of the operation of an apparatus or network entity acting as a radio access node that is a target node for a user terminal performing a handover from a source radio access node.

[0070] In step 400, the apparatus is configured to receive a request to serve a user terminal having a session utilizing a network slice that is not supported by the apparatus, or to receive a request that the network slice utilized by the session serving the terminal will no longer be supported.

[0071] In step 402, the apparatus is configured to transmit a message to the node serving the terminal that sent the received request, the message having information that the apparatus will temporarily accept the terminal session.

[0072] At step 404, the apparatus is configured to transmit a message regarding remapping of the terminal and the session to a network entity responsible for mobility management in the network.

[0073] Figure 4B is a flow chart illustrating an embodiment. The flow chart shows an example of the operation of an apparatus or a network entity acting as a session management function, SMF, or a part of an SMF.

[0074] At step 420, the apparatus is configured to receive a request to update or release a packet data unit session from a network entity responsible for mobility management in the network, the request including information about an associated slice to be released and a slice replacing the slice to be released.

[0075] At step 422, the apparatus is configured to transmit a message to the user terminal for releasing the packet data unit session, the message including information about an associated slice to be released and a slice replacing the slice to be released.

[0076] In an embodiment, the message transmitted to the user terminal is a non-access stratum PDU session modification command (cause, protocol configuration option (PDU session address lifetime value)).

[0077] In an embodiment, the message transmitted to the user terminal is a non-access stratum PDU session release, which includes a cause (re-establishment to the same data network).

[0078] Figure 4C 1 is a flowchart illustrating an embodiment. This flowchart shows an example of the operation of the user terminal device.

[0079] At step 430, the apparatus is configured to receive a request from a network entity responsible for session management in the network, the request to trigger SSC mode 3 or SSC mode 2 for a packet data unit session, the request including information about an associated slice to be released and a slice replacing the slice to be released;

[0080] In step 432, the apparatus is configured to transmit a request to establish a new packet data unit session as part of a triggered SSC mode 3 or SSC mode 2 process that uses an associated slice for the packet data unit session, regardless of a user equipment routing policy (URSP) contained in the apparatus, the associated slice being a slice that was previously indicated as an alternative slice.

[0081] Figure 5 FIG1 is a signaling diagram illustrating an example. The diagram illustrates the various stages mentioned above. The diagram shows signaling between a user terminal 200, a source radio access node 206, a target radio access node 500, an AMF 210, and three SMFs 212, 502, 504. The user terminal 200 is about to perform an Xn handover from the source node 206 to the target node 500, where slice remapping is utilized.

[0082] The user terminal 200 has allowed NSSAI, including slice 10, slice 11, slice 12, slice 13, slice 14, and slice 15.

[0083] In this example scenario, the user terminal has PDU Session 1 for slice 10 active in the source radio access node 206. It is remapped to a new PDU Session 4 for slice 11 because slice 10 is not supported in the target radio access node.

[0084] Furthermore, the user terminal has a PDU Session 2 for slice 12 which is inactive in the source radio access node 206. It is remapped to a new PDU Session 5 for slice 13 since slice 12 is not supported in the target radio access node.

[0085] Furthermore, the user terminal 200 has a PDU session 3 of slice 14 which is no longer supported in the target radio access node and will not be remapped.

[0086] The mapping table here includes the following items:

[0087] Slice 10->11;

[0088] Slice 12->13.

[0089] The user terminal has 506 three PDU sessions 1 , PDU session 2 and PDU session 3 .

[0090] The system's O&M configures slice remapping information 508 for the wireless access node.

[0091] The AMF sends 510 the UE-allowed NSSAI to the serving radio access node 206 and the user terminal 200 according to existing procedures.

[0092] The source radio access node 206 transmits a handover request 512 to the target radio access node 500 .

[0093] The target radio access node may inform 514 the source radio access node via a "PDU Session Temporarily Accepted" information element during the HO procedure that it temporarily accepts PDU Session 1 of slice 10 due to the slice remapping action.

[0094] It should be noted that the selection of the remapped slice to be used as a replacement for slice 10 depends on the list of slices that can be remapped from slice 10 (e.g., 11 and 21), as well as the slices supported by the user terminal according to its allowed NSSAI. Therefore, for example, for user terminal 1, which has slices 10 and 11 but not 21 in its allowed NSSAI, slice 11 will be selected, and for another user terminal 2, which has slices 10 and 21 in its allowed NSSAI, slice 21 will be selected.

[0095] The source radio access node transmits 516 a handover complete message to the target radio access node.

[0096] When the handover is completed, the target radio access node 500 is configured to include the indicators "Terminate slice 10, try alternative slice 11", "Terminate slice 12, try 13", "Terminate slice 14" in the path switch request (PSR) sent 518 to the AMF.

[0097] Then, the PDU Session 1, PDU Session 2, and PDU Session 3 of the user terminal are processed by AMF.

[0098] The AMF detects that the PDU session 1 of the user terminal 200 using slice 10 in the source node 206 is to be remapped to slice 11 and is active. The AMF is configured to send 520 an update message to the SMF 212 indicating "terminate slice 10 and attempt to remap to slice 11". The SMF 212 then triggers step 530.

[0099] The AMF also detects that PDU Session 2, which utilizes slice 12, is to be remapped to slice 13 and is inactive. The AMF is configured to send 524 a delete message to SMF2 502 indicating "terminate slice 12 and attempt to remap to slice 13." SMF2 502 then triggers step 532.

[0100] The AMF also detects that PDU Session 3 of Slice 14 will not be remapped. It sends 528 a DELETE to SMF3 to indicate the termination of Slice 14. SMF3 then triggers step 534.

[0101] The user terminal 200 is configured to perform 522 a post-handover registration. Since the source radio access node and the target radio access node have different slice support, they cannot belong to the same registration area for the user terminal. Since the AMF received the "termination slice 10, 12, 14" indicator in the PSR 518 message, the AMF still includes 526 Slices, S-NSSAI, 10, 12, 14 in the latest allowed NSSAI to the user terminal. The AMF considers that slices 10, 12, 14 are still temporarily available for the user terminal until it receives a notification from the (multiple) SMFs for the actual release of all PDU Sessions established on slices 10, 12, 14 (or when the protection timer expires). In this example, this corresponds to a notification that PDU Session 1, PDU Session 2, PDU Session 3 using slices 10, 12, 14 have been released when step 542 is reached.

[0102] In response to step 520, the SMF 212 is configured to trigger a NAS PDU Session Modification command "Cause, PCO (PDU Session Address Lifetime Value), Terminate Slice 10, Try Alternative Slice 11" 530 to the user terminal to invoke SSC Mode 3. It may include an optional "Terminate Slice 10, Try Alternative Slice 11" Information Element IE directed to the user terminal to indicate the target slice 11 and a special treatment in the user terminal (if supported by the user terminal). The special treatment is to set up a new PDU Session 4 using slice 11, even if the URSP rules in the user terminal indicate that slice 10 has a higher priority.

[0103] It should be noted that, as background information, SSC mode 3 corresponds to network behavior, in which the network instructs the user terminal that the existing PDU session will be released by the network after some timer, inviting the user terminal to re-establish another (new) PDU session as soon as possible to compensate. In an embodiment, an optional new "Terminate slice 10, try alternative slice 11" information element is used to indicate the target slice for the new PDU session, to indicate to the user terminal that it is meaningless to try to establish a PDU session using the initial slice 10.

[0104] The user terminal triggers 538 the establishment of a new PDU session 4 using slice 11 according to the SSC mode 3 procedure. This procedure can be performed like the prior art (in the case of non-roaming or local breakout (LBO)).

[0105] In response to step 524, SMF2 502 may be configured to invoke SSC Mode 3 or SSC Mode 2, assuming that the PDU session for slice 12 is inactive and no data is delivered. If SMF2 invokes SSC Mode 3, the behavior is similar to that of SMF 212 described above at step 530.

[0106] Figure 5 Instead, the call flow shown in FIG5 shows an example of SMF2 502 triggering SSC Mode 2. In this case, SMF2 502 triggers a NAS PDU Session Release 532 to the user terminal, which includes the cause "Reestablish to the same Data Network (DN)" and includes a new "Terminate Slice 12, Try Slice 13" element.

[0107] In both cases, after receiving the message 532 , the user terminal triggers a step 538 similar to step 536 .

[0108] As a reaction to step 528, SMF3 504 may immediately trigger the release 534 of PDU Session 3, since this PDU Session belongs to slice 14, which will not be remapped. It may include an appropriate cause value to avoid a retry by the user terminal.

[0109] SMF1 is configured to trigger the release 542 of PDU Session 1 of slice 10 according to SSC Mode 3 at the end of the timer 540. This process can be performed as in the prior art (in the case of non-roaming or local breakout (LBO)).

[0110] When notified from various SMFs that all PDU sessions corresponding to slices that are no longer supported (i.e., slice 10, slice 12, slice 14) have been released, the AMF sends a UCU (UE Configuration Update) message 544 in sequence at this stage to update the allowed NSSAI to the NG-RAN and the user terminal. Therefore, in this example, the newly generated allowed NSSAI will be "slice 11, slice 13, slice 15".

[0111] Above Figure 5 The Xn handover from source node 206 to target node 500 is described. Figure 5 Some modifications of are performed in a similar manner.

[0112] Figure 5 The switching signals 512 to 516 in FIG. 5 are replaced by the N2 HO preparation phase, which can be performed as in the prior art.

[0113] The PSR message 518 is replaced by the target RAN with a target AMF: Handover Notification (handover is considered successful in the target-RAN due to this message). The Handover Notification contains a new "terminating slice 10, attempting 11" indicator for the AMF.

[0114] Figure 6 is a signaling diagram illustrating an example. Figure 6There is no handover involved; instead, this example describes a situation where the serving radio access node is configured to remap a given slice to another slice for the corresponding PDU session. This may occur to overcome an overload situation, or for slices that are only temporarily supported in the radio access node (e.g., only during some events). In this example, the node is configured to remap slice 10 to slice 11.

[0115] The system's O&M 220 configures the radio access node 206 with the slice remapping information 600 .

[0116] The AMF sends 602 the allowed NSSAI to the serving radio access node 206 and the user terminal 200 according to existing procedures.

[0117] The radio access node 206 transmits a new indicator 604 to the AMF (in an existing Next Generation Application Protocol (NGAP) message or a new NGAP message) to notify about "terminating slice 10 and trying alternative slice 11". The AMF sends an update message to the SMF, which includes the new indicator "terminating slice 10 and trying alternative slice 11" in the update message 606.

[0118] Receiving these new indicators prompts the SMF to trigger SSC mode 3, 608, 610, 612, as combined Figure 5 shown.

[0119] The PDU session is cleared, such as Figure 5 Like in.

[0120] The AMF 210 transmits a UCU (UE Configuration Update) message 614 to update the allowed NSSAI to the NG-RAN and the user terminal.

[0121] It should be noted that in message 614, the AMF may require the user terminal to re-register (the registration step is not shown).

[0122] Figure 7 The figure shows a simplified example of an apparatus or network entity to which an embodiment of the present invention is applied. In some embodiments, the apparatus may be a network entity such as an AMF 210 or a radio access node 500 or a part of a network entity.

[0123] It should be understood that the apparatus is described herein as an example illustrating some embodiments. It will be apparent to those skilled in the art that the apparatus may also include other functions and / or structures, and that not all described functions and structures are required. Although the apparatus has been described as one entity, the different modules and memories may be implemented in one or more physical or logical entities.

[0124] The apparatus 700 of this example includes a control circuit 702 configured to control at least some operations of the apparatus.

[0125] The apparatus may include a memory 704 for storing data. Furthermore, the memory may store software 706 executable by the control circuit 702. The memory may be integrated in the control circuit.

[0126] The apparatus further comprises one or more interface circuits 708 configured to connect the apparatus to other devices and network elements or entities of a radio access network. The interface may provide a wired or wireless connection.

[0127] In an embodiment, the software 706 may comprise a computer program including program code means adapted to cause the control circuitry 702 of the apparatus to implement at least some of the above-described embodiments.

[0128] There is no absolute chronological order for the steps and related functions described above and in the accompanying drawings, and some steps may be performed simultaneously or in a different order than given. Other functions may also be performed between steps or within steps. Some steps may also be excluded or replaced with corresponding steps.

[0129] The device or controller capable of performing the above steps can be implemented as an electronic digital computer, processing system, or circuit, which can include a working memory (random access memory, RAM), a central processing unit (CPU), and a system clock. The CPU can include a set of registers, an arithmetic logic unit, and a controller. The processing system, controller, or circuit is controlled by a sequence of program instructions transferred from the RAM to the CPU. The controller can include some microinstructions for basic operations. The implementation of the microinstructions may vary depending on the CPU design. The program instructions can be encoded in a programming language, which can be a high-level programming language such as C, Java, etc., or a low-level programming language such as machine language or assembly language. The electronic digital computer can also have an operating system, which can provide system services to computer programs written using the program instructions.

[0130] The term "circuitry" as used in this application refers to all of the following: (a) hardware circuit implementations alone, such as implementations solely in analog and / or digital circuitry, and (b) combinations of circuitry and software (and / or firmware), such as, where applicable: (i) a combination of multiple processors or (ii) portions of multiple processors / software, including multiple digital signal processors, software, and multiple memories, that work together to enable the device to perform various functions, and (c) circuits, such as a microprocessor or portions of multiple microprocessors, that require software or firmware for operation, even if that software or firmware is not actually present.

[0131] This definition of "circuitry" applies to all uses of this term in this application. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its accompanying software and / or firmware. For example, if applicable to the particular component, the term "circuitry" would also cover a baseband integrated circuit or an applications processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network device, or other network equipment.

[0132] An embodiment provides a computer program embodied on a distribution medium, the computer program comprising program instructions which, when loaded into an electronic device, are configured to control the device to perform the above-described embodiments.

[0133] A computer program may be in source code form, object code form, or some intermediate form, and may be stored on a carrier, which may be any entity or device capable of carrying the program. Examples of such carriers include recording media, computer memory, read-only memory, and software distribution packages. Depending on the processing power required, a computer program may be executed on a single electronic digital computer or distributed across multiple computers.

[0134] The device can also be implemented as one or more integrated circuits, such as application specific integrated circuits (ASICs). Other hardware embodiments are also possible, such as circuits constructed from separate logic components. A mixture of these different implementations is also possible. When selecting an implementation method, those skilled in the art will consider requirements set for, for example, the size and power of the device, the necessary processing power, production costs, and output.

[0135] In an embodiment, an apparatus comprises: a component for storing information about slice remapping, the information about slice remapping describing how a given network slice can be mapped to another network slice; a component for receiving a first message from an access node, wherein the node serves a terminal that utilizes a network slice that the node does not support or the node has received a request to serve a terminal that utilizes a network slice that the node does not support; and a component for transmitting, based on the first message, a message to a network entity responsible for session management for controlling the connection of the terminal, the message having information about slice remapping and / or an activity status of a packet data unit session associated with a slice that the node does not support.

[0136] In an embodiment, an apparatus includes: a component for receiving a request to serve a terminal having a session that utilizes a network slice that is not supported by the apparatus, or receiving a request that the network slice utilized by the session serving the terminal will no longer be supported; a component for transmitting a message to a node serving the terminal, the node sending the received request, the message having information that the apparatus will temporarily accept the terminal session; and a component for transmitting a message about remapping of the terminal and the session to a network entity responsible for mobility management in the network.

[0137] In an embodiment, an apparatus includes: a component for receiving a request to update or release a packet data unit session from a network entity responsible for mobility management in a network, the request including information about an associated slice to be released and a slice that replaces the slice to be released; and a component for transmitting a message to a user terminal to release the packet data unit session, the message including information about the associated slice to be released and a slice that replaces the slice to be released.

[0138] In an embodiment, an apparatus includes: a component for receiving a request from a network entity responsible for session management in a network, the request being used to trigger session and service continuity mode 3 or session and service continuity mode 2 for a packet data unit session, the request including information about an associated slice to be released and a slice replacing the slice to be released; and a component for transmitting a request to establish a new packet data unit session as part of the triggered session and service continuity mode 3 or session and service continuity mode 2 process, the process using an associated slice for the packet data unit session, regardless of a user equipment routing policy contained in the apparatus, the associated slice being a slice previously indicated as a replacement slice.

[0139] It is obvious to a person skilled in the art that as technology advances, the inventive concept can be implemented in various ways.The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A device in a communication network, comprising: at least one processor; and at least one memory including computer program code, The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least perform: storing information about slice remapping, said information about slice remapping describing how a given network slice may be mapped to another network slice; receiving a first message from an access node: the node serves a terminal that utilizes a first network slice that the node does not support or the node has received a request to serve a terminal that utilizes the first network slice that the node does not support; as well as Based on the first message, using the information about slice remapping and / or the activity state of the packet data unit session associated with the first network slice not supported by the node, transmit a message for controlling the connection of the terminal to a network entity responsible for session management, wherein the transmitted message is used to trigger the network entity responsible for session management to initiate a process of session and service continuity mode 3 for the packet data unit session to the terminal. The transmitted message includes a request to update or release a packet data unit session, the request including information about the associated first network slice to be released and a second network slice that replaces the first network slice, wherein the process of the session and service continuity mode 3 uses the second network slice for a new packet data unit session established for the terminal.

2. The apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: Controlling the receipt of information about slice remapping from an operation and maintenance unit of the network.

3. The apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: Prior to receiving the first message, control the reception of information about slice remapping in a second message from the access node that is independent of the terminal, wherein the node indicates that it serves the terminal or has received a request to serve the terminal.

4. The apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: Controlling reception of information about slice remapping in the first message, wherein the node indicates that it serves the terminal or has received a request to serve the terminal.

5. The apparatus of claim 1, wherein the message from the access node is a next generation path switch request from a radio access node.

6. The apparatus of claim 1, wherein the message from the access node is a Next Generation Handover Notification message from a radio access node.

7. The apparatus according to claim 3, wherein the second message is a Next Generation Setup Request message or a Next Generation Access Network Configuration Update message or any new Next Generation dedicated application protocol message.

8. The apparatus according to any one of claims 1 to 7, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: controlling, after said reception of said first message, the reception of a registration request from said terminal, Controlling the transmission of a registration acceptance to the terminal, the registration acceptance comprising a list of slices that the terminal is allowed to use, the list still comprising at least slices that are not supported by the access node currently serving the terminal.

9. The apparatus according to any one of claims 1 to 7, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: transmitting signaling to the terminal, the signaling including a list of the slices that the terminal is allowed to use, When the packet data unit session of the terminal no longer uses the slice that is no longer supported by the access node currently serving the terminal, or when the protection timer has expired, the list no longer includes the slice that is not supported by the access node currently serving the user terminal.

10. A device in a communication network, comprising: at least one processor; and at least one memory including computer program code, The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least perform: receiving a request to serve a terminal having a packet data unit session utilizing a first network slice that is not supported by the apparatus, or receiving a request that the first network slice utilized by the packet data unit session serving the terminal is no longer supported; transmitting a message to a node serving the terminal that sent the received request, the message having information that the device will temporarily accept the packet data unit session using the first network slice; as well as Transmitting a message about the remapping of the terminal and the packet data unit session from the first network slice to the second network slice to a network entity responsible for mobility management in the network, so as to initiate a session and service continuity mode 3 process for the packet data unit session to the terminal, wherein the session and service continuity mode 3 process uses the second network slice for the new packet data unit session.

11. The apparatus of claim 10, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: An indicator to terminate the first network slice is included in the message to the network entity responsible for mobility management in the network.

12. The apparatus of claim 10 or claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: An indicator to attempt the second network slice is included in the message to the network entity responsible for mobility management in the network.

13. The apparatus according to claim 10 or claim 11, wherein the message sent to the network entity responsible for mobility management in the network is one of the following: a path switch request, a handover notification, a radio access network configuration update message, or any other next generation message.

14. A device in a communication network, comprising: at least one processor; and at least one memory including computer program code, The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least perform: receiving a request to update or release a packet data unit session from a network entity responsible for mobility management in the network, the request comprising information about an associated first network slice to be released and a second network slice replacing the first network slice; transmitting a message for releasing the packet data unit session to a user terminal, the message being used to trigger a request for session and service continuity mode 3 for the packet data unit session, and the message including information about the associated first network slice to be released and the second network slice replacing the first network slice; as well as Receive a sixth message transmitted by the user terminal to establish a new packet data unit session, the sixth message being part of the process of the session and service continuity mode 3, which uses the second network slice for the new packet data unit session.

15. The apparatus of claim 14, wherein the message transmitted to the user terminal is a non-access stratum packet data unit session modification command including a cause and protocol configuration options, the protocol configuration options including a packet data unit session address lifetime value.

16. The apparatus of claim 14, wherein the message transmitted to the user terminal is a non-access stratum packet data unit session release including a cause, the cause including re-establishment to the same data network.

17. A user terminal in a communication network, comprising: at least one processor; and at least one memory including computer program code, The at least one memory and the computer program code are configured to, using the at least one processor, cause the user terminal to at least execute: receiving a fifth message from a third apparatus responsible for session management in the communication network, the fifth message being a request for triggering session and service continuity mode 3 for a packet data unit session, the fifth message including information about an associated first network slice to be released and a second network slice replacing the first network slice; A sixth message is transmitted to the communication network as part of the session and service continuity mode 3 process to establish a new packet data unit session, which uses the second network slice for the new packet data unit session regardless of the user equipment routing selection policy included in the user terminal.

18. A method in an apparatus in a communication network, comprising: storing information about slice remapping, said information about slice remapping describing how a given network slice may be mapped to another network slice; receiving a first message from an access node: the node serves a terminal that utilizes a first network slice that the node does not support or the node has received a request to serve a terminal that utilizes the first network slice that the node does not support; as well as Based on the first message, using the information about slice remapping and / or the activity state of the packet data unit session associated with the first network slice not supported by the node, transmit a message for controlling the connection of the terminal to a network entity responsible for session management, wherein the transmitted message is used to trigger the network entity responsible for session management to initiate a process of session and service continuity mode 3 for the packet data unit session to the terminal. The transmitted message includes a request to update or release a packet data unit session, the request including information about the associated first network slice to be released and a second network slice that replaces the first network slice, wherein the process of the session and service continuity mode 3 uses the second network slice for a new packet data unit session established for the terminal.

19. The method according to claim 18, further comprising: Controlling the receipt of information about slice remapping from an operation and maintenance unit of the network.

20. The method of claim 18, further comprising: Prior to receiving the first message, control the reception of information about slice remapping in a second message from the access node that is independent of the terminal, wherein the node indicates that it serves the terminal or has received a request to serve the terminal.

21. The method of claim 18, further comprising: Controlling reception of information about slice remapping in the first message, wherein the node indicates that it serves the terminal or has received a request to serve the terminal.

22. The method of claim 18, wherein the message from the access node is a Next Generation Path Switch Request from a radio access node.

23. The method of claim 18, wherein the message from the access node is a Next Generation Handover Notification message from a radio access node.

24. The method of claim 20, wherein the second message is a Next Generation Setup Request message or a Next Generation Access Network Configuration Update message or any new Next Generation dedicated application protocol message.

25. The method according to any one of claims 18 to 24, further comprising: controlling, after said reception of said first message, the reception of a registration request from said terminal, Controlling the transmission of a registration acceptance to the terminal, the registration acceptance comprising a list of slices that the terminal is allowed to use, the list still comprising at least slices that are not supported by the access node currently serving the terminal.

26. The method according to any one of claims 18 to 24, further comprising: Transmitting signaling to the terminal, the signaling including a list of the slices that the terminal is allowed to use, wherein the list no longer includes the slices that are no longer supported by the access node currently serving the terminal when the packet data unit session of the terminal no longer uses the slices that are no longer supported by the access node currently serving the terminal, or when a protection timer has expired.

27. A method in an apparatus in a communication network, comprising: receiving a request to serve a terminal having a packet data unit session utilizing a first network slice that is not supported by the apparatus, or receiving a request that the first network slice utilized by the packet data unit session serving the terminal is no longer supported; transmitting a message to a node serving the terminal that sent the received request, the message having information that the device will temporarily accept the packet data unit session using the first network slice; as well as A message about the remapping of the terminal and the packet data unit session from the first network slice to the second network slice is transmitted to a network entity responsible for mobility management in the network, so as to initiate a session and service continuity mode 3 process for the packet data unit session to the terminal, and the session and service continuity mode 3 process uses the second network slice for the new packet data unit session.

28. The method according to claim 27, further comprising: An indicator to terminate the first network slice is included in the message to the network entity responsible for mobility management in the network.

29. The method according to claim 27 or claim 28, further comprising: An indicator to attempt the second network slice is included in the message to the network entity responsible for mobility management in the network.

30. The method of claim 27 or claim 28, wherein the message sent to the network entity responsible for mobility management in the network is one of: a path switch request, a handover notification, a radio access network configuration update message, or any other next generation message.

31. A method in an apparatus in a communication network, comprising: receiving a request to update or release a packet data unit session from a network entity responsible for mobility management in the network, the request comprising information about an associated first network slice to be released and a second network slice replacing the first network slice; transmitting a message for releasing the packet data unit session to a user terminal, the message being used to trigger a request for session and service continuity mode 3 for the packet data unit session, and the message including information about the associated first network slice to be released and the second network slice replacing the first network slice; as well as Receive a sixth message transmitted by the terminal to establish a new packet data unit session, the sixth message being part of the session and service continuity mode 3 process, which uses the second network slice for the new packet data unit session.

32. The method of claim 31 , wherein the message transmitted to the user terminal is a non-access stratum packet data unit session modification command including a cause and protocol configuration options, the protocol configuration options including a packet data unit session address lifetime value.

33. The method of claim 31 , wherein the message transmitted to the user terminal is a non-access stratum packet data unit session release including a cause, the cause including re-establishment to the same data network.

34. A method in a user terminal in a communication network, comprising: receiving a fifth message from a third device responsible for session management in the network, the fifth message being a request for triggering session and service continuity mode 3 for a packet data unit session, the fifth message including information about an associated first network slice to be released and a second network slice replacing the first network slice; as well as A sixth message is transmitted to the communication network as part of the session and service continuity mode 3 process to establish a new packet data unit session, which uses the second network slice for the new packet data unit session regardless of the user equipment routing selection policy included in the user terminal.

35. A computer-readable storage medium having stored thereon instructions for causing an apparatus to at least perform the following: storing information about slice remapping, said information about slice remapping describing how a given network slice may be mapped to another network slice; receiving a first message from an access node: the node serves a terminal that utilizes a first network slice that the node does not support or the node has received a request to serve a terminal that utilizes the first network slice that the node does not support; and Based on the first message, using the information about slice remapping and / or the activity state of the packet data unit session associated with the first network slice not supported by the node, transmit a message for controlling the connection of the terminal to a network entity responsible for session management, wherein the transmitted message is used to trigger the network entity responsible for session management to initiate a process of session and service continuity mode 3 for the packet data unit session to the terminal. The transmitted message includes a request to update or release a packet data unit session, the request including information about the associated first network slice to be released and a second network slice that replaces the first network slice, wherein the process of the session and service continuity mode 3 uses the second network slice for a new packet data unit session established for the terminal.

36. A computer-readable storage medium having stored thereon instructions for causing an apparatus to at least perform the following: receiving a request to serve a terminal having a packet data unit session utilizing a first network slice that is not supported by the apparatus, or receiving a request that the first network slice utilized by the packet data unit session serving the terminal is no longer supported; transmitting a message to a node serving the terminal that sent the received request, the message having information that the device will temporarily accept the packet data unit session using the first network slice; as well as A message about the remapping of the terminal and the packet data unit session from the first network slice to the second network slice is transmitted to a network entity responsible for mobility management in the network, so as to initiate a session and service continuity mode 3 process for the packet data unit session to the terminal, and the session and service continuity mode 3 process uses the second network slice for the new packet data unit session.

37. A computer-readable storage medium having stored thereon instructions for causing an apparatus to at least perform the following: receiving a request to update or release a packet data unit session from a network entity responsible for mobility management in the network, the request comprising information about an associated first network slice to be released and a second network slice replacing the first network slice; transmitting a message for releasing the packet data unit session to a user terminal, the message being used to trigger a request for session and service continuity mode 3 for the packet data unit session, and the message including information about the associated first network slice to be released and the second network slice replacing the first network slice; as well as Receive a sixth message transmitted by the user terminal to establish a new packet data unit session, the sixth message being part of the session and service continuity mode 3 process, which uses the second network slice for the new packet data unit session.

38. A computer-readable storage medium having stored thereon instructions for causing an apparatus to at least perform the following: receiving a fifth message from a third device responsible for session management in the network, the fifth message being used to trigger a request for session and service continuity mode 3 for a packet data unit session, the fifth message including information about an associated first network slice to be released and a second network slice replacing the first network slice; and A sixth message is transmitted to the network to establish a new packet data unit session as part of the session and service continuity mode 3 process, which uses the second network slice for the new packet data unit session regardless of the user equipment routing selection policy included in the device.

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