Mobility across limited slice regions of services during intra-GNB and inter-GNB handover

Abstract

A method performed by an apparatus for a base station is provided. The method comprises: after determining that user equipment UE is leaving a service area AoS of a network slice, releasing resources of a protocol data unit PDU session established for the network slice. The method also includes storing a PDU session context for the PDU session and notifying the core network that the network slice is unavailable or the UE is outside of the AoS of the network slice.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 484,470, filed on February 10, 2023, which is incorporated herein by reference as if reproduced in its entirety. Technical Field

[0003] The subject disclosure relates generally to wireless telecommunication networks and, more particularly, to operating user equipment and network equipment in a wireless telecommunication network. Background Art

[0004] Wireless telecommunications networks are constantly evolving. There is a constant demand for higher data rates and improved quality of service. Reliability requirements are increasing, and the methods and components that ensure reliable connections and data flows while minimizing transmission delays are constantly evolving.

[0005] Wireless communication networks provide services to customers. For example, in 5G wireless telecommunications networks, network slicing is a key feature that provides customers with network slices of different services. Network slicing enables wireless telecommunications network operators to offer 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 and provides specific capabilities and features. Multiple network slices can be created on top of a common shared physical network infrastructure to provide services that may have different requirements for latency, reliability, throughput, and mobility. Summary of the Invention

[0006] According to a first aspect, a method performed at a base station is provided. The method comprises: after determining that a user equipment (UE) is leaving a service area (AoS) of a network slice: releasing resources of a protocol data unit (PDU) session established for the network slice; storing a PDU session context for the PDU session; and notifying a core network that the network slice is unavailable or the UE is outside the AoS of the network slice.

[0007] For example, the UE may be in an RC connected state. In this case, the base station, such as the gNB, knows at any point in time which cell the UE is in and whether it is within or outside the AoS.

[0008] In some examples of the first aspect, the AoS includes one or more cells in which a network slice is available, and the determining includes determining that the UE is undergoing a handover from a first cell in which the network slice is available to a second cell in which the network slice is not available.

[0009] For example, the method may be for operating the mobility of a UE that leaves the AoS of a network slice. Leaving the AoS may mean that the UE is undergoing a handover from a cell within the AoS to a cell outside the AoS.

[0010] In some examples of the first aspect, both the first cell and the second cell are served by a base station.

[0011] For example, the UE may leave the AoS of a network slice during intra-gNB handover.

[0012] In some examples of the first aspect, the method further includes: setting resources for the PDU session based on the stored PDU session context after determining that the UE has re-entered the AoS of the network slice; and notifying the core network: the availability of the network slice, or that the UE has re-entered the AoS of the network slice.

[0013] For example, the method may be an AoS mobility for operating a UE to re-enter a network slice.

[0014] In some examples of the first aspect, the determination includes determining that the UE is undergoing a handover from a second cell in which a network slice is unavailable to a third cell in which a network slice is available.

[0015] In some examples of the first aspect, setting up resources for the PDU session includes setting up a data radio bearer (DRB) for the UE for the PDU session.

[0016] In some examples of the first aspect, setting resources for the PDU session includes sending a radio resource control (RRC) reconfiguration message to the UE, the RRC reconfiguration message including information enabling the UE to set a DRB of the UE for the PDU session.

[0017] In some examples of the first aspect, the notification includes sending a Next Generation NG Application Protocol NGAP UE-related message to the core network, which includes the following indications: the network slice is not available, or the UE is outside the AoS of the network slice, or the network slice is available, or the UE is within the AoS of the network slice.

[0018] In some examples of the first aspect, the NGAP UE-related message is an NGAP PDU Session Notification message.

[0019] In some examples of the first aspect, releasing the resources of the PDU session includes: sending a radio resource control RRC reconfiguration message to the UE, where the RRC configuration message includes: information causing the UE to release the resources of the PDU session.

[0020] In some examples of the first aspect, the first cell is served by a first base station and the second cell is served by a second base station.

[0021] For example, a UE may leave the AoS of a network slice during an inter-gNB handover.

[0022] In some examples of the first aspect, the method further includes: sending a handover HO request to the second base station, the HO request including: a PDU session context for the PDU session with resources for the PDU session; and receiving a HO request confirmation from the second base station, the HO request confirmation including: an indication to be forwarded to the UE, and the indication causing the UE to release resources for the PDU session.

[0023] In some examples of the first aspect, the method further includes: sending an HO request from the base station to a second base station, the HO request including: a PDU session context for the PDU session without resources for the PDU session; and receiving an HO request confirmation from the second base station, the HO request confirmation including: an indication to be forwarded to the UE, and the indication causing the UE to set resources for the PDU session.

[0024] In some examples of the first aspect, the HO request further includes an indication that the PDU session has no resources to be established at the first base station.

[0025] According to a second aspect, a method performed at a core network is provided. The method includes determining that a protocol data unit (PDU) session for network slice establishment is set up and is in an active state; receiving a message from a base station, the message including the following indication: the network slice is unavailable, or the user equipment (UE) is outside the service area (AoS) of the network slice; and in response to the indication, determining to release resources for the PDU session or to locally deactivate resources for the PDU session.

[0026] In some examples of the second aspect, the message is an NGAP UE-related message.

[0027] In some examples of the second aspect, the message is an NGAP path switch request message.

[0028] In some examples of the second aspect, the message is an NGAP PDU Session Notification message.

[0029] In some examples of the second aspect, the method also includes determining that a protocol data unit (PDU) session established for the network slice is set and is in a deactivated state or an inactive state; receiving a message from a base station, the message including the following indication: the network slice is unavailable, or the user equipment UE is outside the service range AoS of the network slice; and in response to the indication, determining based on the indication that the PDU session is activated or in an active state.

[0030] In some examples of the second aspect, the message is an NGAP UE-related message.

[0031] In some examples of the second aspect, the message is an NGAP PDU Session Notification message.

[0032] In some examples of the second aspect, the method also includes: receiving a handover HO request for the UE from the base station at the second base station, the HO request including: a PDU session context for the PDU session with resources for the PDU session; determining at the second base station that the target cell for handover is outside the AoS of the network slice associated with the PDU session; avoiding setting up resources for the PDU session at the second base station; and sending a HO request confirmation from the second base station to the base station, the HO request confirmation including: an indication to be forwarded to the UE, which causes the UE to release resources for the PDU session.

[0033] In some examples of the second aspect, the indication includes an RRC reconfiguration message toward the UE, the RRC reconfiguration message including a request to release a list of DRBs, the list of DRBs corresponding to the DRBs associated with the PDU session.

[0034] In some examples of the second aspect, the method also includes sending an NGAP path switch request message from the second base station to the core network, the NGAP path switch request message including the following indication: indicating that the network slice is unavailable, or the UE is outside the AoS.

[0035] In some examples of the second aspect, the method also includes: receiving a handover HO request for the UE from the base station at the second base station, the HO request including: a PDU session context for the PDU session without resources for the PDU session; determining at the second base station that the target cell for handover is within the AoS of the network slice associated with the PDU session; setting resources for the PDU session corresponding to the received PDU session context at the second base station; and sending a HO request confirmation from the second base station to the base station, the HO request confirmation including: an indication to be forwarded to the UE, and the indication causing the UE to set resources for the PDU session.

[0036] In some examples of the second aspect, the HO request confirmation includes: setting a DRB at the second base station.

[0037] In some examples of the second aspect, setting resources for the PDU session for the PDU session at the second base station includes setting a DRB corresponding to the received PDU session context.

[0038] In some examples of the second aspect, the indication to be forwarded to the UE includes an RRC reconfiguration message toward the UE, the RRC reconfiguration message including a request to set a list of DRBs corresponding to the DRBs associated with the accepted PDU session context.

[0039] In some examples of the second aspect, the method also includes sending an NGAP path switch request message to the core network, where the NGAP path switch request message includes an indication that the slice is available, or that the UE is within the AoS of the network slice.

[0040] In some examples of the second aspect, the core network includes at least one of an access management function AMF and a session management function SMF.

[0041] In some examples of the second aspect, releasing resources of the PDU session includes releasing a data radio bearer (DRB).

[0042] In some examples of the second aspect, the PDU session context includes one or more quality of service (QoS) profiles for one or more QoS flows of the PDU session.

[0043] In some examples of the second aspect, network slicing being available in a cell means that the base station has configured more than zero resources for the network slicing in the cell and the cell belongs to a tracking area where network slicing is supported.

[0044] In some examples of the second aspect, the UE is in an RRC_CONNECTED state in the base station.

[0045] According to a third aspect, an apparatus for a base station is provided. The apparatus includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the apparatus to, upon determining that a user equipment (UE) is leaving a service area (AoS) of a network slice, release a protocol data unit (PDU) session established for the network slice; store a PDU session context of the PDU session; and notify a core network that the network slice is unavailable or the UE is outside the AoS of the network slice.

[0046] According to a fourth aspect, a core network is provided. The core network includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the network to: determine that a protocol data unit (PDU) session established for a network slice is set up and is in an active state; receive a message from a base station, the message including the following indication: the network slice is unavailable or a user equipment (UE) is outside the service area (AoS) of the network slice; and, in response to the indication, determine to release resources for the PDU session or determine to locally deactivate resources for the PDU session.

[0047] Depending on the desired configuration, the aforementioned aspects and features can be implemented in systems, apparatuses, methods, articles of manufacture, and / or non-transitory computer-readable media. The subject disclosure can be implemented in and / or used with a variety of different types of devices, including but not limited to cell phones, tablet computers, wearable computing devices, portable media players, and any other various computing devices.

[0048] This disclosure is intended to provide a brief overview of some of the aspects and features disclosed herein. It should be understood that the features described above are merely examples and should not be construed in any way to narrow the scope of this disclosure. Other features, aspects, and advantages of this disclosure will become apparent from the following detailed description, accompanying drawings, and claims.

[0049] List of abbreviations

[0050] In the subject disclosure, the following abbreviations are used and should be understood according to the given definitions:

[0051] 3GPP 3rd Generation Partnership Project

[0052] 5G 5th generation (mobile communication network)

[0053] 5GC 5G Core

[0054] 5GS 5G system

[0055] AF application function

[0056] AMF Access and Mobility Function

[0057] AN Access Network

[0058] APN Access Point Name

[0059] AoS service area

[0060] BS Base Station

[0061] CDMA Code Division Multiple Access

[0062] CN Core Network

[0063] CP Control Plane

[0064] DL Downlink

[0065] DNN data network name

[0066] DRB Data Radio Bearer

[0067] eNB Evolved Node B

[0068] EPC Evolved Packet Core

[0069] EPS Evolved Packet System

[0070] ETSI European Telecommunications Standards Institute

[0071] E-UTRAN Evolved UMTS Terrestrial Radio Access

[0072] gNB Next Generation Node B / 5G Base Station

[0073] HO Handover

[0074] IE Information Element

[0075] IMS IP Multimedia Subsystem

[0076] IP Internet Protocol

[0077] LTE Long Term Evolution

[0078] MME Mobility Management Entity

[0079] NAS Non-Access Stratum

[0080] NR New Radio

[0081] NSSAI Network Slice Selection Assistance Information

[0082] PCF Policy Control Function

[0083] PCO Protocol Configuration Options

[0084] PDN Packet Data Network

[0085] PDP Packet Data Protocol

[0086] PDU Protocol Data Unit

[0087] PGW PDN Gateway

[0088] PGW-C PGW control function

[0089] PLMN Public Land Mobile Network

[0090] QoS Quality of Service

[0091] RA Registration Area

[0092] RAN Radio Access Network

[0093] RCS Rich Communication Services

[0094] RRC Radio Resource Control (protocol)

[0095] SGW Service Gateway

[0096] SIB System Information Block

[0097] SIM Subscriber Identity Module

[0098] SM Session Management

[0099] SMF session management functions

[0100] S-NSSAI Single NSSAI

[0101] TA Tracking Area

[0102] TAI Tracking Area Identifier

[0103] TS Technical Specifications

[0104] UDM Unified Data Management

[0105] UE User Equipment / Mobile Terminal

[0106] UL Uplink

[0107] URLLC Ultra-Reliable Low Latency Communication

[0108] VoNR Voice over NR BRIEF DESCRIPTION OF THE DRAWINGS

[0109] A better understanding of the subject disclosure may be obtained when the following detailed description of various embodiments is considered in conjunction with the following drawings, in which:

[0110] Figure 1 A schematic diagram illustrating an example communication system including a base station and a plurality of communication devices;

[0111] Figure 2 A schematic diagram illustrating an example mobile communication device;

[0112] Figure 3 A schematic diagram illustrating an example controller arrangement;

[0113] Figure 4 The method is shown in its simplest embodiment;

[0114] Figure 5 An embodiment outside of AoS is shown when the UE moves into the gNB;

[0115] Figure 6 An embodiment of AoS is shown in the figure when the UE moves into the gNB;

[0116] Figure 7 Describes an out-of-AoS embodiment for the case where the UE moves to an inter-gNB;

[0117] Figure 8 Depicts an embodiment in AoS where the UE moves to an inter-gNB case. DETAILED DESCRIPTION

[0118] Before explaining the examples in detail, refer to Figures 1 to 3 , certain general principles of wireless telecommunication networks and mobile communication devices are briefly explained to assist in understanding the underlying technology of the described examples.

[0119] In such as Figure 1 In the wireless telecommunications network 100 shown in FIG, communication devices 102, 104, 105 (otherwise referred to as user equipment or user equipment (UE)) are provided to a data network 113 via base stations 106, 107 (e.g. next generation NB gNB), or similar wireless transmission and / or reception nodes, or access nodes and a core network 112. The base stations 106, 107 may be controlled or assisted by at least one suitable controller device to enable management of operation therein and communication of the communication devices 102, 104, 105 with the base stations 106, 107. The controller device may be located in the radio access network 100 and may be implemented as one central device or its functionality may be distributed across a plurality of devices. The controller device may be part of a base station and / or provided by a separate entity such as a radio network controller (RNC). In the Figure 1 In FIG, controller means 108 and 109 are shown to control respective base stations 106 and 107 for providing macro cells. The controller means of the base stations may be interconnected with other control entities. The controller means comprises at least one memory capacity and at least one processor.

[0120] exist Figure 1 , base stations 106 and 107 are shown as being connected to a data network 113 via a core network 112 (eg, via a gateway or user plane function of the core network 112).

[0121] As used herein, the term "base station" has the full scope of its ordinary meaning and includes at least: a wireless communication station that is installed at a fixed location and is used to communicate as part of a wireless telephone system or radio system. The communication area (or coverage area) of a base station may be referred to as a "cell". The base station and mobile communication devices may be configured to communicate wirelessly over the air interface using any of the various radio access technologies (RATs) specified in the telecommunications standards described herein below. As described in Figure 1As illustrated in FIG, although one of the base stations may act as a “serving cell” for a mobile communication device (i.e., UE), each mobile communication device (i.e., UE) may also be able to receive wireless signals (i.e., radio signals) from (and possibly within communication range of) one or more other cells (which may be provided by the base station and / or any other base station), which may be referred to as “neighboring cells.”

[0122] The smaller base stations 116, 118 and 120 may also be connected to the core network 112, for example, via separate controller devices and / or via controller devices of macro-level stations. The base stations 116, 118 and 120 may provide pico cells or femto cells. In the example, the base stations 116 and 118 are connected to the core network 112 via the controller device 111, while the base station 120 is connected to the core network 112 via the controller device 108. In some embodiments, the smaller base stations may not be provided. The smaller base stations 116, 118 and 120 may be part of a second radio access network. The mobile communication devices 102, 104, 105 may access the base stations of the radio access network using various access technologies such as code division multiple access (CDMA) or wideband CDMA (WCDMA). Other non-limiting examples include time division multiple access (TDMA), frequency division multiple access (FDMA), and various schemes therein such as interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA), and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA), etc.

[0123] An example of an architecture for a core network 112 wireless telecommunications network is described in TS 23.501 of the 3rd Generation Partnership Project (3GPP) for New Radio (NR). The core network 112 can utilize network function virtualization (NFV), which is a concept that proposes virtualizing the network functions of the core network 112 into "building blocks" or entities that can be operably connected or linked together to provide services. Virtualized network functions (VNFs) can include one or more virtual machines that use standard or general types of servers rather than customized hardware or containers to run computer program code. Cloud computing can be utilized to provide or instantiate various VNFs. In some implementations, the VNFs of the core network 112 can be distributed among multiple distributed computing systems, such as servers.

[0124] An example of a core network 112 is a 5G core network (5GC) that includes various VNFs. The 5GC is connected to communication devices via base stations (e.g., base stations 106, 107, 118, 116, 120). The base stations are part of the radio access network (RAN). The UPF (User Plane Function) is a VNF of the core network 112, and its role is called the PSA (PDU Session Anchor). It can be responsible for forwarding traffic between the data network 113 and one or more PDU sessions established between the core network 112 and the communication devices 102, 104, 105.

[0125] The UPF is controlled by the SMF (Session Management Function) which receives policies from the PCF (Policy Control Function). Both the SMF and the PCF are VNFs of the core network 112. The core network 112 also has other VNFs, including the AMF (Access and Mobility Function).

[0126] The communication device 200 is now shown with reference to a schematic partial cross-sectional view of Figure 2 is described in more detail. Figure 1 The communication devices 102, 104, and 105 shown in FIG are examples of communication devices 200. Communication devices 200 are often referred to as user equipment (UE), user devices, or terminal devices. A suitable communication device 200 can be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) or mobile device such as a mobile phone or smartphone, a computer provided with a wireless interface card or other wireless interface facility (e.g., a USB dongle), a personal data assistant (PDA) or a tablet computer provided with wireless communication capabilities, or any combination thereof. Communication device 200 can provide, for example, data communication for carrying communications such as voice, electronic mail (e-mail), text messages, multimedia, etc. Users can thus be provided with or offered a variety of services via their communication devices. Non-limiting examples of these services include two-way or multi-way calling, data communication or multimedia services, or simply access to a data communication network system such as the Internet. Users can also be provided with broadcast or multicast data. Non-limiting examples of content include downloads, television and radio programs, videos, advertisements, various alerts, and other information.

[0127] In industrial applications, the communication device 200 can be a modem integrated into an industrial actuator (e.g., a robotic arm) and / or a modem acting as an Ethernet hub that serves as a connection point for one or more connected Ethernet devices (whose links can be wired or wireless).

[0128] The communication device 200 is typically provided with at least one processor 201, at least one memory 202, and possibly other components 203 for software and hardware assistance in performing the tasks it is designed to perform, including controlling access to and communications with base stations and other communication devices. The at least one processor, at least one memory 202, and possibly other components 203 may be provided on a suitable circuit board and / or in a chipset 204. A user may control the operation of the communication device 200 through a suitable user interface such as a keyboard 205, voice commands, a touch-sensitive screen or touch-sensitive pad, a combination thereof, or the like. A display 208, a speaker, and a microphone may also be provided. In addition, the communication device 200 may include suitable connectors (wired or wireless) to other devices and / or for connecting external accessories such as hands-free devices.

[0129] The communication device 200 can receive radio signals transmitted by a base station (e.g., base stations 106, 107, 116, 118, 120) over an air interface or radio interface 207 and can use the transceiver device 206 to transmit radio signals to the base station (e.g., base stations 106, 107, 116, 118, 120). The transceiver device 206 can be provided, for example, by a radio section and associated antenna device. The antenna device can be arranged internally or externally to the communication device 200 and can include one or more antenna elements.

[0130] The communication device 200 may also include equipment or alternatively be configured to communicate with one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one or more mobile television broadcast standards (such as ATSC-M / H or DVB-H), and / or any other wireless communication protocol.

[0131] Usually, in Figure 2 The communication device 200 illustrated in FIG. 1 includes a component set configured to perform core functionality. For example, the component set may be implemented as a system on a chip (SoC), which may include parts for various purposes. Alternatively, the component set may be implemented as individual components or groups of components for various purposes. The component set may be coupled (e.g., communicatively; directly or indirectly) to various other circuits of the communication device 200.

[0132] The communication device 200 may include: at least one antenna in communication with a transmitter and a receiver (e.g., a transceiver device 206). Alternatively, the transmitting antenna and the receiving antenna may be separate. At least one processor 201 may be configured to provide signals to the transmitter and the receiver, respectively, and receive signals from the transmitter and the receiver, respectively, and control the functions of the communication device 200. The at least one processor 201 may be configured to control the functions of the transmitter and the receiver by affecting control signaling via electrical leads to the transmitter and the receiver. Similarly, the at least one processor 201 may be configured to control other components of the communication device 200 by affecting control signaling via electrical leads connecting the at least one processor 201 to the communication device 200, such as the display 208 and the at least one memory 202. The at least one processor 201 can be implemented in a variety of ways, including circuitry, at least one processing core, one or more microprocessors with accompanying digital signal processors (DSPs), one or more processors without accompanying digital signal processors (DSPs), one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (e.g., application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and / or the like), or some combination thereof. Thus, in some examples, the at least one processor 201 can include multiple processors or processing cores.

[0133] The communication device 200 can utilize one or more air interface standards, communication protocols, modulation types, access types, and / or the like. Signals transmitted and received by the processor may include signaling information in accordance with the air interface standard of the applicable cellular system and / or any number of different wired or wireless network technologies, including but not limited to Wi-Fi, WLAN technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, and / or the like. In addition, these signals may include voice data, user-generated data, user-requested data, and / or the like.

[0134] For example, the communication device 200 and / or the cellular modem therein can operate in accordance with various protocols of fourth generation (4G) or fifth generation (5G) radio access technologies. For example, the communication device 200 can operate in accordance with 4G wireless communication protocols such as the LTE Advanced protocol, 5G, and / or similar wireless communication protocols that may be subsequently developed.

[0135] It should be understood that the processor may include circuits for implementing the audio / video and logic functions of the communication device 200. For example, the processor may include a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, and / or the like. The control and signal processing functions of the communication device 200 may be allocated between these devices according to their respective capabilities. The processor may additionally include an internal voice coder (VC), an internal data modem (DM), and / or the like. In addition, the processor may include functionality to operate one or more software programs stored in the memory. Typically, the processor and the stored software instructions may be configured to cause the communication device 200 to perform actions. For example, the processor may be capable of running a connectivity program such as a web browser. The connectivity program may allow the communication device 200 to send or receive web content such as location-based content based on protocols such as the Wireless Application Protocol (WAP), the Hypertext Transfer Protocol (HTTP), and / or the like.

[0136] The communication device 200 may also include a user interface, which includes, for example, an earphone or speaker, a ringer, a microphone, a display, a user input interface, and / or the like, which may be operably coupled to the processor. As described above, the display may include a touch-sensitive display, wherein the user can touch and / or gesture to make selections, input values, etc. The processor may also include a user interface circuit, which is configured to control at least some functions of one or more elements of a user interface such as a speaker, a ringer, a microphone, a display, and / or the like. The processor and / or the user interface circuit include a processor, which may be configured to control one or more functions of one or more elements of the user interface via computer program instructions, which computer program instructions (e.g., software and / or firmware) are stored in a memory accessible to the processor (e.g., volatile memory, non-volatile memory, and / or the like). The communication device 200 may include various circuits for driving the mobile terminal, such as a circuit for providing mechanical vibration as a detectable output. The user input interface may include a device that allows the communication device 200 to receive data, such as a keyboard (e.g., keyboard 206) and / or other input devices. The keyboard can also be a virtual keyboard displayed on the display or an externally coupled keyboard.

[0137] The communication device 200 may also include one or more devices or components for sharing data and / or obtaining data. For example, the communication device 200 may include a short-range radio frequency (RF) transceiver and / or interrogator so that data can be shared with and / or obtained from electronic devices in accordance with RF technology. The communication device 200 may include other short-range transceivers, such as infrared (IR) transceivers, Bluetooth TMThe communication device 200 may include a Bluetooth™ (BT) transceiver, a wireless Universal Serial Bus (USB) transceiver, a Bluetooth™ (BT) low energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and / or any other short-range radio technology that operates with a wireless technology. For example, the communication device 200 and more specific short-range transceivers can send data to and / or receive data from electronic devices near the device, such as within 10 meters. The communication device 200, which includes a Wi-Fi or wireless local area network modem, can also send data to and / or receive data from electronic devices according to various wireless technologies, including 6LoWpan, Wi-Fi, Wi-Fi low power, WLAN technologies such as IEEE 802.11 technology, IEEE 802.15 technology, IEEE 802.16 technology, and / or the like.

[0138] The communication device 200 may include memory that can store information elements related to mobile users, such as one or more subscriber identity modules (SIMs), one or more universal subscriber identity modules (USIMs), one or more removable subscriber identity modules (R-UIMs), one or more eUICCs, one or more UICCs, and / or the like. In addition, the at least one memory 202 of the communication device 200 may include other removable memory and / or fixed memory. The communication device 200 may include volatile memory and / or non-volatile memory. For example, the volatile memory may include random access memory (RAM) including dynamic RAM and / or static RAM, on-chip cache memory or off-chip cache memory, and / or the like. The non-volatile memory that may be embedded and / or removable may include, for example, read-only memory, flash memory, magnetic storage devices such as hard disks, floppy disk drives, tapes, optical disk drives and / or media, non-volatile random access memory (NVRAM), and / or the like. Like volatile memory, non-volatile memory may include a cache area for temporary storage of data. At least some volatile and / or non-volatile memory may be embedded in the processor. The memory may store one or more software programs, instructions, information segments, data, and / or the like that may be used by the apparatus to perform the operations disclosed herein.

[0139] The at least one memory 202 may include or store an identifier, such as an International Mobile Equipment Identity (IMEI) code, that can uniquely identify the communication device 200. The at least one memory 202 may include an identifier, such as an International Mobile Equipment Identity (IMEI) code, that can uniquely identify the communication device 200. In an example embodiment, the processor may be configured using computer code stored at the memory to cause the processor to perform the operations disclosed herein.

[0140] Some embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. For example, the software, application logic, and / or hardware may reside in a memory, a processor, or an electronic component. In some example embodiments, the application logic, software, or an instruction set is maintained on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any non-transitory medium that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or data processor circuit. Figure 2 As depicted herein, computer-readable media may include non-transitory computer-readable storage media, which may be any medium that can contain or store instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0141] Figure 3 An example embodiment of a controller device 300 is shown, for example coupled to a base station of a radio access network and / or for controlling a base station of a radio access network. Figure 1 The controller devices 108 / 109 and 111 shown in the figure are examples of controller devices 300. As described above, the base station can be an eNB, gNB, access node, or radio access network node. The controller device 300 can be integrated with the base station (e.g., base stations 106, 107, 118) or external to the base station. As described above, each base station can include a separate controller device 300. The controller device 300 can be a radio network controller or a spectrum controller. In some embodiments, each base station can have a controller device 300 as well as a radio network controller. The controller device 300 can be arranged to control communications with communication devices (e.g., communication devices 102, 104, 105) located in the service area of ​​the wireless telecommunications network 100. The controller device 300 includes a memory 301, a processor 302, and an input / output interface 304. Via the input / output interface 304, the controller device 300 can be coupled to the receiver and transmitter of the base station. The receiver and / or transmitter of the base station can be a radio front end or a remote radio head.

[0142] The radio front end or remote radio head of a base station includes an antenna configured to transmit and receive radio frequency (RF) signals and an RF transceiver module coupled to the antenna assembly that receives RF signals from the antenna, converts them to baseband signals, and transmits them to a baseband processor. The RF transceiver also converts baseband signals received from the baseband processor, converts them to RF signals, and transmits the RF signals to a communication device using the antenna. The baseband processor processes the received baseband signals.

[0143] In some embodiments, the processor comprises any suitable processor, including, by way of example, a special purpose processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, a tensor processing unit, a central processing unit, a graphics processing unit, an integrated circuit (IC), and / or a state machine. The memory 302 includes computer program code that causes the controller device 300 to perform processing according to the methods further described below. Although in Figure 2 Only one processor 301 and one memory 302 are shown in FIG. 1 , but the controller device may include multiple processors 301 and multiple memories 302 .

[0144] As mentioned, network slicing is a concept in which the network resources of the end-to-end connection between communication devices (e.g., 102, 104, 105) and endpoints (e.g., the N6 interface between the core network 112 and the data network 113) in a wireless telecommunications network (e.g., wireless telecommunications network 100, which can be a public land mobile network or a standalone private network) are sliced. A network slice can be understood as a logical end-to-end network that can be dynamically created and / or modified by the operator of the wireless telecommunications network. The network(s) between the end devices can be sliced ​​from one end device to other end devices, with the slices thus forming logical pipes within the network(s). User devices can access the slices on the radio interface. As described in 3GPP TS 38.300 (e.g., Version 16.8.0 Release 16, 2022-01), network slicing will be a key feature in 5G to support different services using the same underlying mobile network infrastructure.

[0145] A network slice can provide or serve a specific type of service ("service type"). To date, three different network slices / service types have been standardized: eMBB (processing slices for 5G enhanced mobile broadband), URLLC (processing slices for ultra-reliable low-latency communication), and MIoT (processing slices for massive Internet of Things). Communications service providers (CSPs) can define additional network slices / service types if required. A given communications device can access multiple network slices on the same access network (e.g., on the same radio interface).

[0146] Thus, network slicing enables network operators to provide dedicated virtual networks on a public network infrastructure. Different virtual networks or logical networks may have different network characteristics such as different quality of service (QoS) in order to host services with different requirements based on service level agreements (SLAs) with customers. For example, a virtual network may be customized to meet the specific requirements of various applications, services, devices, customers and / or network operators. Thus, network slicing enables the provision of different services to communication devices (e.g., UEs). In an example, the service requirements of a network slice for services such as URLLC and eMBB may be different, or the tenants providing those services may also be different.

[0147] A network slice is uniquely identified by a single network slice selection assistance information (S-NSSAI). Current 3GPP regulations (e.g., 3GPP TS 38.300 Version 17.3.0 Release 17, 2023-01) allow a communication device (e.g., UE) to be simultaneously connected to or served by up to eight network slices corresponding to eight S-NSSAIs. On the other hand, each cell can support (i.e., be able to provide) dozens or even hundreds of S-NSSAIs. In current 3GPP regulations (e.g., 3GPP TS 38.423 Version 17.3.0 Release 17 2023-01), a tracking area (TA) can support (i.e., be able to handle) up to 1024 network slices.

[0148] The format of S-NSSAI may include a slice service type (SST) and a slice differentiator (SD) field with a total length of 32 bits or only a portion of the SST field in the case where the length of the S-NSSAI is only 8 bits. Examples of the format of S-NSSAI are described in 3GPP specifications such as 3GPP TS 23.501 or 3GPP TS 23.003. The SST field may have standard values ​​and non-standard values. Values ​​0 to 127 belong to the standardized SST range. For example, an SST value of 1 may indicate that the slice is applicable to 5G eMBB processing, an SST value of 2 may indicate that the slice is applicable to URLLC processing, and so on. SD is defined only by the network operator.

[0149] Other concepts involve defining Tracking Areas (TAs) and Registration Areas (RAs). A TA is a logical concept of an area in which a user can move around without updating the MME, and is the LTE, EPS or 5GS counterpart to the Location Area and Routing Area for GSM, WCDMA and GPRS. A TA consists of a collection of cells. TAs can be grouped into a list of tracking areas (TA list) that can be configured on the UE. For example, the network assigns a list with one or more TAs to the user. In certain operations, the UE can move freely among all the TAs in the list without updating the MME. A RA consists of a list of Tracking Areas (TAs), which are configured to the UE by the network. The RA is used to track the UE for paging purposes. If the UE leaves a RA, the UE will let the network know via a NAS Registration Request (called Mobility Registration Update) so that the correct RA can be configured to the UE.

[0150] In a 5G wireless telecommunications network, RA also has the role of maintaining the allowed network slices (alternatively allowed NSSAI) of a communication device (e.g., UE). The allowed NSSAI is provided to the communication device (e.g., UE) through the core network (e.g., the AMF of the core network 112). Throughout the subject disclosure, allowed S-NSSAI may refer to an S-NSSAI that is included in the not allowed NSSAI. A communication device (e.g., UE) may request an S-NSSAI during registration (e.g., by including the request S-NSSAI in a NAS message sent by the communication device to the core network), and the core network will decide whether to add the requested S-NSSAI to the list of allowed S-NSSAI for the communication device (e.g., UE).

[0151] In a recent development, 3GPP has agreed to have homogeneous network slicing support within the TA as well as the RA. This means that the same network slice is supported throughout the TA and the allowed NSSAI of the RA is valid across the communication devices (e.g., UEs).

[0152] However, a RA may include multiple TAs that do not support all allowed network slices of a communication device (e.g., a UE) to allow for more flexible registration area configuration, including support for non-homogeneous network slices in the TA that includes the RA.

[0153] A network slice is deployed for services over a service area (AoS), which may match an existing TA or the AoS may be different. Currently, network slice availability (i.e., where a network slice is defined to be supported or provided) is designed to match the boundaries of the deployed TA. Furthermore, communication devices (e.g., UEs) and network configurations may be affected when network slices are deployed and deactivated over certain time intervals (e.g., the configured NSSAI may change when a network slice becomes available or becomes available, which may affect the allowed NSSAI and other parameters, and subsequently RAs may need to change, etc.).

[0154] From this arises the problem that the AoS does not necessarily map to existing TA boundaries and temporary network slices. In addition, when a communication device (e.g., UE) in RRC_Connected mode with a PDU session associated with a specific network slice active moves outside the AoS, that is, when the network device (e.g., UE) is physically moving away from the AoS and / or TA, the PDU session is deactivated.

[0155] Deactivation of a PDU Session generally means that no more RAN resources are allocated to the PDU Session and no PDU Session context exists in the base station (e.g. gNB). If a PDU Session is deactivated in a part of a RA outside of an AoS, it is not defined how the PDU Session can be reactivated when the UE re-enters an AoS in a RA.

[0156] Furthermore, the issue becomes more complex depending on whether the edge of the AoS matches the edge of a base station (e.g., gNB), i.e., whether crossing the AoS boundary involves changing gNBs and an inter-gNB handover is performed, or crossing the AoS boundary is performed within the same gNB and an intra-gNB handover is performed.

[0157] The methods and apparatus described herein address the problems described above.

[0158] Now refer to Figure 4 , to describe the method of the present disclosure in its simplest embodiment. Figure 4 In FIG, UE 400 is a communication device such as communication device 102 , 104 or 105 .

[0159] The method is performed by a device of a base station (e.g., a controller device 300), and includes, after determining that a user equipment UE 400 is leaving a service area AoS 402 of a network slice, the base station releasing resources of a protocol data unit (PDU) session established for the network slice. The PDU session context is stored for the PDU session, and the base station notifies the core network that the network slice is unavailable or the UE 400 is outside the AoS 402 of the network slice.

[0160] UE 400, connected to cell 401 using a specific slice, is moving outside of AoS 402. Since UE 400 is outside AoS 402 and still moving near cell 404 within TA 403, this embodiment refers to an intra-gNB embodiment, meaning there is no handover to another gNB. When UE 400 is leaving the AoS, the gNB releases its resources and saves the PDU session context for UE 400's return. Later, when UE 400 re-enters AoS 402, the PDU session context can be used to reactivate the PDU session. Leaving the AoS can mean that the UE is being handed over from a cell within the AoS to a cell outside the AoS, while entering the AoS can mean that the UE is undergoing a handover from a cell outside the AoS to a cell within the AoS.

[0161] This approach offers several advantages over the previously discussed problems. First, it significantly reduces the signaling involved in this process for intra-gNB handovers, and even more so for inter-gNB handovers. Second, in the case of inter-gNB handovers, the UE does not require a double RRC reconfiguration—that is, the UE resumes the PDU session by reactivating it—and therefore does not need to reregister the network slice via the signaling steps of the full mobility registration procedure. Third, this approach avoids the need to support the 3GPP location reporting procedure in all nodes, while also avoiding the configuration and reporting of the area of ​​interest as part of this procedure, which introduces additional signaling and complexity.

[0162] Furthermore, there is less complexity in managing multiple simultaneous areas of interest for multiple UEs which overlap and create a lot of signaling towards the AMF, and means are provided for avoiding interaction between UE context level concepts like UE mobility reporting and PDU session context level concepts like activation / deactivation of PDU sessions.

[0163] refer to Figure 5 , an embodiment of an intra-gNB handover scenario with a UE moving outside the AoS is shown, i.e. handover of the UE is performed from a cell within the AoS to a cell outside the AoS and still in the same gNB, which will now be described in more detail.

[0164] The UE 500 is in RRC_Connected mode to a cell of gNB1 501 within the AoS of a network slice, e.g., network slice 1. Then, at 504, a PDU Session 1 with context and corresponding resources is set up. Likewise, a PDU Session 1 for the AMF 502 or SMF 503 is set up and is in an active state (e.g., activated or active 0).

[0165] Next, at 506, upon detecting that the UE 500 leaves the AoS of the network slice 1, i.e., the UE 500 is handed over from a cell within the AoS of the network slice 1 to a cell outside the AoS of the network slice 1, the gNB1 501 releases the resources for the PDU Session 1, including releasing the data radio bearers (DRBs) of the UE 500 by sending an RRC reconfiguration at 507, the RRC reconfiguration including an indication for the UE 500 to release its DRBs, and the gNB1 501 still maintains the storage of the PDU session context for the PDU Session 1. In this case, the context of the PDU session (generally referred to as the PDU session context) for the PDU session still exists and / or is retained for the PDU resources for which the PDU session was not established (i.e., setup).

[0166] At 508, gNB1 501 notifies the AMF 502 of the core network (e.g., core network 112) by sending an NG Application Protocol (NGAP) PDU Session Notification message that includes an indication that network slice 1 is unavailable or, alternatively, UE 500 is outside the AoS of network slice 1.

[0167] Finally, at 509 and 510, upon receiving an indication that network slice 1 is unavailable or alternatively that the UE is outside the AoS of network slice 1, the AMF 502 and SMF 503 of the core network decide or behave as if the PDU Session associated with network slice 1 is deactivated (e.g., buffering traffic of PDU Session 1) or release PDU Session 1. The AMF 502 and SMF 503 may decide whether to maintain or release the PDU Session based on previous UE behavior, UE mobility behavior, traffic of the gNB, or other factors.

[0168] Figure 6 The illustrated embodiment shows an intra-gNB handover scenario where the UE moves into the AoS, meaning a handover between two cells in the same gNB, one outside the AoS and the other within the AoS. This embodiment assumes that the UE has moved out of the AoS at least once, so that the following methods apply accordingly.

[0169] At 600, the UE 500 is outside the AoS of the network slice 1 and the PDU Session 1 does not have resources for PDU Session 1 establishment (i.e., setup), and the gNB1 501 however has a context for the PDU Session 1 with a corresponding Quality of Service (QoS) profile for the QoS flow of the PDU Session 1 of the UE 500. Similarly for the AMF 502 and SMF 503 at 601, the PDU Session 1 is setup and is in a deactivated state or an inactive state (i.e., has been deactivated or is not activated).

[0170] At 602, after gNB1 501 detects the re-entry of UE 500 in the AoS of network slice 1, i.e., the UE is undergoing a handover from a cell outside the AoS of network slice 1 to a cell within the AoS of network slice 1, gNB1 501 sets up resources for PDU Session 1, including setting up the DRB of gNB1 501 towards UE 500. At 603, the DRB is set up in an RRC reconfiguration message from gNB1 501 to UE 500.

[0171] Next, at 604, gNB1 501 then sends an NGAP PDU SESSION NOTIFICATION message including a new indication that slice 1 is available or alternatively a new indication that the UE is now within the AoS of slice 1.

[0172] At 605 and 606, upon receiving a new indication that Slice 1 is available or alternatively a new indication that the UE is now within the AoS of Network Slice 1, the AMF 502 and SMF 503 behave as if the PDU Session associated with Network Slice 1 is activated again (e.g. delivering traffic for PDU Session 1).

[0173] In the following embodiments, the UE is leaving and / or re-entering the AoS and involves a change of gNB, i.e. during an inter-gNB handover.

[0174] Figure 7 Depicting an embodiment of an inter-gNB handover scenario with a UE moving outside of the AoS.

[0175] Initially, at 701, the UE 500 is within the AoS for slice 1 in RRC connected mode to gNB1 501, with PDU Session 1 having context and resources set up. At 702, PDU Session 1 is set up and active for the AMF 502 and SMF 503 (i.e., PDU Session 1 is active). The UE 500 leaves the AoS from gNB1 501 in inter-gNB handover at 703. Leaving the AoS means that the UE is being handed over from gNB1 to gNB2.

[0176] Now at 704, the source gNB1 501 sends a handover request to gNB2 700, as in any common handover, and includes the PDU session context for the PDU session and the resources for the PDU session established at the source gNB1 501, such as the DRB for PDU session 1.

[0177] At 705, after detecting that the target cell is outside the AoS of network slice 1, target gNB2 700 decides to create and store a context for PDU Session 1 based on the PDU Session 1 context received from gNB1 501. However, target gNB2 700 avoids setting up resources for PDU Session 1 in the target gNB and also constructs an RRC container containing an RRC reconfiguration message intended to release the DRB of UE 500 corresponding to PDU Session 1.

[0178] At 706 and 707, target gNB2 700 sends a Handover Request Ack message including a command (or indication) to release the UE's DRB encapsulated in an RRC Reconfiguration message (delivered to the UE as an RRC container, which is transparent to source gNB1 501), even though it has retained (i.e., stored) the PDU Session 1 context for the QoS profile of the QoS flow of PDU Session 1. UE 500 receives the RRC Reconfiguration message and releases the DRB, and then UE 500 accesses the target cell at 708.

[0179] At 709, the target gNB2 700 sends an NGAP Path Switch Request message to complete the handover, where the gNB2 700 includes an indication that slice 1 is not available or alternatively the UE is outside the AoS of slice 1.

[0180] Finally, at 710, upon receiving a new indication via a path switch request that network slice 1 is unavailable or, instead, that UE 500 is now outside the AoS of network slice 1, AMF 502 and SMF 503 decide whether to behave as if the PDU context associated with network slice 1 is deactivated (or inactive) (e.g., buffering traffic for the PDU session) or to release the PDU session. The AMF 502 and SMF 503 may decide whether to maintain or release the PDU context based on previous UE behavior, UE mobility behavior, traffic patterns, or other factors.

[0181] Figure 8An embodiment illustrates an inter-gNB handover scenario involving a UE moving into the AoS (i.e., when the UE re-enters the AoS). In this scenario, a source gNB (e.g., gNB1) sends a handover request for the UE to a target gNB (e.g., gNB2), where the selected target cell (included in the handover request message) indicates a cell within the AoS. Moving into or entering the AoS means that the UE 500 is handed over from a cell outside the AoS to a cell within the AoS. In the inter-gNB handover scenario, the cell outside the AoS is served by a base station, e.g., gNB1, and the cell within the AoS is served by another base station, e.g., gNB2.

[0182] At 800, the UE is outside the AoS of network slice 1 and gNB1 501 has maintained an existing context for PDU Session 1, even though all resources for PDU Session 1 have been previously released. PDU Session 1 is established and is in an inactive state or a deactivated state with respect to the AMF 502 and SMF 503 at 801 (i.e., PDU Session 1 is in an inactive state or a deactivated state).

[0183] Now the UE 500 moves from the cell of gNB1 501 to another cell belonging to gNB2 700 at 802, resulting in a handover in a gNB handover scenario.

[0184] At 803, gNB1 501 sends a handover request to gNB2 700, which includes: the context of PDU Session 1, resource settings without associated PDU Sessions, such as associated established DRBs, and optionally includes an explicit indication to inform that PDU Session 1 does not have associated resources established in the source gNB1.

[0185] At 804, after detecting that the selected target cell is now within the AoS of network slice 1, the target gNB2700 decides to create a context for PDU Session 1 based on the PDU Session Context received from gNB1 500 (even if it does not have resources associated with PDU Session 1, such as no related DRBs), and sets the resources for PDU Session 1, including setting the DRBs of the target gNB2 700 towards the UE 500.

[0186] At 805 and 806, target gNB2 700 sends a Handover Request Confirm message, which includes a command encapsulated in an RRC Reconfiguration message (transparently delivered to UE 500 as an RRC container via source gNB1 501), which sets the DRB for UE 500 determined at 804. UE 500 receives the RRC Reconfiguration message and sets the DRB. Consequently, UE 500 accesses the target cell at 807 via an RRC HO Complete message.

[0187] At 808, the target gNB2 700 sends an NGAP Path Switch Request message to complete the handover, where the target gNB2 700 includes an indication that network slice 1 is available or instead the UE is now within the AoS of slice 1.

[0188] Finally at 809, upon receiving a new indication via a path switch request that network slice 1 is available or alternatively a new indication that UE 500 is now within the AoS of network slice 1, the AMF 502 and SMF 503 behave as if the PDU session associated with network slice 1 is activated (e.g., delivering traffic for the PDU session associated with network slice 1).

[0189] The core network 112 may be a device including a network function virtualization infrastructure for providing various network functions of the core network 112, including Figures 5 to 8 502 and SMF 503 shown in FIG. Alternatively, the core network 112 may include an apparatus implementing AMF and an apparatus implementing SMF configured to communicate with each other. The apparatus of the core network 112 may include one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to perform the functions of the AMF 502 and SMF 503, including in connection with Figures 5 to 8 The operations or actions of the AMF 502 and SMF 503 described in this document.

[0190] It should be understood that the apparatus may include or be coupled to other units or modules, such as a radio part or radio head for transmission and / or reception. 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.

[0191] It should be noted that while the embodiments have been described with respect to LTE and 5G NR, similar principles can be applied to other networks and communication systems where fast connection re-establishment is required. Thus, while certain embodiments have been described above with reference to examples of certain example architectures for wireless networks, technologies, and standards, the embodiments can be applied to any other suitable form of communication system other than those illustrated and described herein.

[0192] It is also noted herein that while the above describes exemplifying embodiments, several variations and modifications may be made to the disclosed solution without departing from the scope of the subject disclosure.

[0193] In general, the various exemplary embodiments may be implemented in hardware or special purpose circuitry, software, logic, or any combination thereof. Some aspects of the subject disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device, although the subject disclosure is not limited thereto. Although various aspects of the subject disclosure may be illustrated and described as block diagrams, flow charts, or using other graphical representations, it will be well understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuitry or special purpose logic, general purpose hardware or a controller or other computing device, or some combination thereof.

[0194] The example embodiments disclosed in the present subject matter may be implemented by computer software that can be executed by a data processor of a mobile device, such as in a processor entity, or by hardware, or by a combination of software and hardware. Computer software or programs, also referred to as program products, include software routines, applets, and / or macros that can be stored in a data storage medium readable by any device and that include program instructions for performing specific tasks. A computer program product may include one or more computer executable components that are configured to implement an embodiment when the program is run. The one or more computer executable components may be at least one software code or a portion thereof.

[0195] Example embodiments of the subject disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools are available to convert a logic-level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0196] The foregoing description has been presented by way of non-limiting examples to provide a complete and informative description of the exemplary embodiments of the present subject disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant art(s) in view of the foregoing description when read in conjunction with the accompanying drawings and the appended claims. Nevertheless, all such and similar modifications of the teachings of this invention will still fall within the scope of the present subject disclosure as defined in the appended claims. Indeed, alternative embodiments include combinations of one or more embodiments with any other embodiments discussed above.

Claims

1. A method performed by an apparatus for a base station, the method comprising: After determining that the user equipment UE is leaving the service area AoS of the network slice: releasing resources for a protocol data unit (PDU) session established for the network slice; Storing a PDU session context for the PDU session; as well as Notify the core network that the network slice is unavailable or the UE is outside the AoS of the network slice.

2. The method according to claim 1, wherein The AoS comprises one or more cells where the network slice is available, and wherein The determination includes: Determining that the UE is undergoing a handover from a first cell where the network slice is available to a second cell where the network slice is not available. The method according to claim 2 , wherein the first cell and the second cell are both served by the base station.

4. The method according to any one of claims 1 to 3, further comprising: After determining that the UE has re-entered the AoS of the network slice, setting resources for a PDU session based on the stored PDU session context; and Notify the core network of the availability of the network slice or that the UE has re-entered the AoS of the network slice.

5. The method of claim 4, wherein the determining comprises: Determining that the UE is undergoing a handover from a second cell where the network slice is unavailable to a third cell where the network slice is available.

6. The method according to any one of claims 4 or 5, wherein the setting of resources for the PDU session comprises: A data radio bearer (DRB) of the UE is set for the PDU session.

7. The method of claim 6, wherein setting the DRB of the UE for the PDU session comprises: A radio resource control (RRC) reconfiguration message is sent to the UE, where the RRC reconfiguration message includes a command for the UE to set the DRB of the UE for the PDU session.

8. The method according to any one of the preceding claims, wherein the notification comprises: A Next Generation NG Application Protocol NGAP UE-related message is sent to the core network, where the message includes the following indications: the network slice is unavailable, or the UE is outside the AoS of the network slice, or the network slice is available, or the UE is within the AoS of the network slice. 9 . The method according to claim 8 , wherein the NGAP UE-related message is the NGAP PDU Session Notification message.

10. The method according to any one of the preceding claims, wherein said releasing the resources for the PDU session comprises: A radio resource control (RRC) reconfiguration message is sent to the UE, where the RRC reconfiguration message includes a command for the UE to release a data radio bearer of the UE for the PDU session.

11. The method of claim 2, wherein the first cell is served by the base station and the second cell is served by a second base station.

12. The method according to claim 11, further comprising: Sending a handover HO request to the second base station, the HO request including: the PDU session context for the PDU session with resources for the PDU session; A HO request confirmation is received from the second base station, the HO request confirmation including a command to be forwarded to the UE, and the command causes the UE to release the DRB of the UE for the PDU session.

13. The method according to claim 11, further comprising: sending, from the base station to the second base station, a HO request, the HO request including: the PDU session context for the PDU session without the resources for the PDU session; A HO request confirmation is received from the second base station, the HO request confirmation including a command to be forwarded to the UE, and the command causes the UE to set the DRB of the UE for the PDU session.

14. The method according to claim 13, wherein the HO request further comprises: An indication that no resources are established for the PDU session at the first base station.

15. A method performed by a core network, the method comprising: Determine that the protocol data unit (PDU) session established for the network slice is set up and is active; receiving a message from a base station, the message including the following indication: the network slice is unavailable, or the user equipment UE is outside the service area AoS of the network slice; In response to the indication, it is determined to release resources of the PDU session used for the PDU session, or it is determined to locally deactivate the resources of the PDU session used for the PDU session. The method according to claim 15 , wherein the message is an NGAP UE-related message. The method of claim 16 , wherein the message is an NGAP Path Switch Request message. The method of claim 16 , wherein the message is an NGAP PDU Session Notification message.

19. The method according to claims 15 to 18, performed at a core network, further comprising: Determining that a protocol data unit (PDU) session established for the network slice is set up and is in a deactivated state or an inactive state; receiving a message from a base station, the message including an indication that the network slice is available or that a user equipment (UE) is within the service area (AoS) of the network slice; and In response to the indication, it is determined based on the indication that the PDU session is activated or in an active state.

20. The method of claim 19, wherein the message is an NGAP UE-related message.

21. The method of claim 20, wherein the message is an NGAP PDU Session Notification message.

22. The method of claim 20, wherein the message is an NGAP Path Switch Request message.

23. A method performed at a target base station, the method comprising: receiving, from a base station, a handover (HO) request for the UE, the HO request including: a PDU session context for a PDU session with resources for the PDU session; determining that a target cell for the handover is outside the AoS of a network slice associated with the PDU session; Avoiding setting, at a second base station, the resources for the PDU session; A HO request confirmation is sent to the base station, where the HO request confirmation includes an indication to be forwarded to the UE, where the indication causes the UE to release resources of the PDU session.

24. The method of claim 23, wherein the indication comprises: An RRC reconfiguration message towards the UE, the RRC reconfiguration message comprising a request to release a list of DRBs corresponding to the DRBs associated with the PDU session.

25. The method according to any one of claims 23 to 24, further comprising: An NGAP path switch request message is sent to the core network, where the NGAP path switch request message includes an indication that the network slice is unavailable or the UE is outside the AoS.

26. A method performed at a target base station, the method comprising: receiving, from a base station, a handover (HO) request for the UE, the HO request including: a PDU session context for a PDU session without the resources of the PDU session; determining that a target cell for the handover is within the AoS of a network slice associated with the PDU session, Setting resources for a PDU session corresponding to the received PDU session context, A HO request confirmation is sent to the base station, where the HO request confirmation includes an indication to be forwarded to the UE, and the indication causes the UE to set resources for the PDU session.

27. The method of claim 26, wherein sending the HO request confirmation comprises: The DRB is set at the target base station.

28. The method of claim 26, wherein setting resources for the PDU session comprises: The DRB corresponding to the received PDU session context is set.

29. The method according to any one of claims 26 to 28, wherein the indication to be forwarded to the UE comprises: An RRC reconfiguration message towards the UE, the RRC reconfiguration message comprising a request to set a list of DRBs corresponding to the DRBs associated with the received PDU session context.

30. The method according to any one of claims 26 to 29, further comprising: An NGAP path switch request message is sent to the core network, where the NGAP path switch request message includes an indication that the slice is available or that the UE is within the AoS of the network slice.

31. The method of any preceding claim, wherein the core network comprises: At least one of an Access Management Function (AMF) and a Session Management Function (SMF).

32. The method according to any one of the preceding claims, wherein said releasing the resources of the PDU session comprises: Release of Data Radio Bearer (DRB).

33. The method according to any one of the preceding claims, wherein the PDU session context comprises: One or more Quality of Service (QoS) profiles for one or more QoS flows for the PDU session.

34. A method according to any of the preceding claims, wherein the network slice being available in a cell means that the base station has configured more than zero resources for the network slice in the cell, and the cell belongs to a tracking area in which the network slice is supported.

35. A method according to any preceding claim, wherein the UE is in RRC_CONNECTED state in the base station.

36. An apparatus for a base station, the apparatus comprising a processor and a memory comprising instructions, wherein when the instructions are executed by the processor, the apparatus performs operations comprising: After determining that the user equipment UE is leaving the service area AoS of the network slice: Release resources of the protocol data unit (PDU) session established for the network slice; Storing a PDU session context of the PDU session; as well as Notify the core network that the network slice is unavailable or the UE is outside the AoS of the network slice.

37. The apparatus of claim 36, wherein when the instructions are executed by the processor, the apparatus is further caused to perform the method of any one of claims 2 to 14, and claims 23 to 30.

38. A core network comprising a processor and a memory comprising instructions, which, when executed by the processor, cause the core network to at least: Ensure that the protocol data unit (PDU) session established for the network slice is set up and is active; receiving a message from a base station, the message including an indication that the network slice is unavailable or that the user equipment (UE) is outside a service area (AoS) of the network slice; and In response to the indication, it is determined to release resources of the PDU session used for the PDU session, or it is determined to locally deactivate the resources of the PDU session used for the PDU session.

39. The core network of claim 38, wherein when the instructions are executed by the processor, the instructions further cause the network element to perform the method of any one of claims 15 to 22.

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