Base station and method

Abstract

To solve a problem of handover to an inappropriate base station, or a problem of setting an inappropriate secondary node when not all slice types are available at each base station.SOLUTION: During handover, a source base station selects a target base station that supports an appropriate slice by exchanging network slice selection support information between base stations in advance. Also, during dual connectivity setup, a master node selects a secondary node that supports the appropriate slice.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to radio access networks in cellular or wireless telecommunications networks, and in particular, but not exclusively, to sharing of radio access networks by multiple operators. The present invention is particularly, but not exclusively, related to wireless telecommunications networks implemented in accordance with various standards defined by the 3rd Generation Partnership Project (3GPP). For example, the present invention is related to Long Term Evolution (LTE) networks, LTE Advanced (LTE-A) networks, related extensions and developments of LTE / LTE-A, and more recently developed communication technologies beyond LTE / LTE-A, so-called "5G", "Next Generation" (NG) or "New Radio" (NR) technologies. [Background technology]

[0002] Radio Access Network (RAN) sharing deployment scenarios are known, and methods and capabilities to facilitate the implementation of these scenarios have been introduced into 3rd Generation Partnership Project (3GPP) standards from Release 5 onwards.

[0003] Traditionally, RAN sharing provides a way for network operators (network operators, service providers) to reduce their capital expenditure requirements when setting up wireless communication networks and / or to expand the areas covered by cellular communication services. Rather than each operator having to provide their own base stations and associated equipment for each cell of the network, operators sharing another operator's RAN can provide their services in areas served by the other operator without investing in their own base stations at that location.

[0004] It also reduces ongoing operational costs (OPEX) for sharing operators by reducing the number of base stations that they must provide and operate (reducing CAPEX). Indeed, since each base station can consume a large amount of power during operation, reducing the number of base stations in operation can significantly reduce power requirements and thus can also be considered environmentally friendly.

[0005] Typically, operator RAN sharing is a fixed, long-term agreement for each operator to obtain some access to the other operator's RAN. RAN sharing is particularly advantageous in areas where operators have underutilized cell capacity, as this free capacity can be shared without affecting the original operator's ongoing service provision. Furthermore, RAN sharing can be useful to ensure that the services provided by the operators reach a certain percentage of the population, which may be specified by the license conditions in some countries, without each operator having to set up expensive capacity in remote areas that are likely to be underutilized.

[0006] The terms "5G" and "New Radio" (NR) refer to evolving communications technologies that are expected to support a variety of applications and services, such as Machine Type Communications (MTC), Internet of Things (IoT) communications, vehicular communications and autonomous vehicles (V2V / V2X), high-definition video streaming, and smart city services. 5G / NR technologies are therefore expected to enable network access to vertical markets, provide networking services to third parties, and support network sharing to create new business opportunities. Base stations in 5G / NR communications systems are commonly referred to as "NR-BS" (New Radio Base Station) or "gNB," with the understanding that they may be referred to using the term eNB (or 5G / NReNB), which is more typically associated with LTE base stations.

[0007] Recently, it has been proposed that the functionality of a gNB (herein referred to as a "distributed" gNB) be split between one or more Distributed Units (DUs) and a Central Unit (CU), with the CU typically performing higher level functions and communicating with a next generation core network (it will be understood by those skilled in the art that either the term "core network" or "core" may be used) and the DU performing lower level functions and communicating over the air interface with nearby User Equipment (UE) (i.e., within a cell operated by the gNB).

[0008] To support such a variety of applications and services, mobile network operators must satisfy the diverse and often conflicting requirements of these applications and must handle large amounts of data traffic. For example, some of these applications may have relatively loose Quality of Service (QoS) / Quality of Experience (QoE) requirements, while some applications may have relatively stringent QoS / QoE requirements (e.g., high bandwidth and / or low latency).

[0009] Since it is expensive and impractical to provide a dedicated network infrastructure for each type of service or application, network virtualization and "network slicing" are considered as a flexible and cost-effective way to support and accommodate heterogeneous applications with diverse requirements on a common network infrastructure. Such network slicing is described, for example, in Non-Patent Document 1. In essence, network slicing represents a logical network, typically with respect to a specific service level agreement (SLA) for a specific tenant. In fact, each slice represents a specific system behavior (or set of behaviors). Tenants of a network (e.g., a Public Land Mobile Network (PLMN)) are the wholesale customers of the network. For example, a tenant may be a large enterprise, an intermediary that requires that the PLMN provide access to at least a predefined set of resources, or a specific policy for handling subscribers of a slice in case of congestion. Examples of tenants include a Public Safety Agency. Tenants may also have application-specific requirements. For example, in an enterprise deployment, an enterprise may have a set of manufacturing floor equipment in a factory, as well as equipment related to operations outside the manufacturing floor. An enterprise may have a policy to allocate at least 60% of resources (whether in the RAN or core network) to manufacturing floor operations during congestion, but not to segregate resources all the time.

[0010] More specifically, a network slice (e.g., a "5G slice") may support a particular connection type of communication service with a particular way of handling the control plane and user plane for that service. In practice, a slice may include multiple network functions and a particular Radio Access Technology (RAT) setting that are combined together for a particular use case, technical and / or business model. Slices do not need to include all the same functions, and some functions that are considered essential today may be missing in one or more slices. In essence, the intention is for a slice to provide only the traffic processing required for a given use case, thereby avoiding other unnecessary functions.

[0011] As an example, multiple slices operating simultaneously on the same infrastructure include a slice for typical smartphone use, configured by setting up full-scale smartphone-only functionality distributed across the network. A slice supporting automotive use cases may also be provided where security, reliability, and latency are critical, with all necessary (and potentially dedicated) functionality realized at the cloud edge nodes, including vertical applications required as a result of latency constraints. Massive Machine Type devices (IoT devices, e.g., sensors) supporting another slice may be provided with basic control plane functionality with contention-based resource access, e.g., configured omitting any mobility functionality. There may be other dedicated slices operating in parallel to address unknown use cases and traffic, and potentially a generic slice providing basic best-effort connectivity.

[0012] Each network slice is defined by a respective Network Slice Template (NST), which is a logical representation of the network functions and corresponding resource requirements needed to provide the required telecommunication services and network capabilities. Each template is used to implement "instances" (called Network Slice instances (NSIs)) corresponding to the respective network slice.

[0013] Network slicing therefore achieves a number of beneficial objectives from the UE's perspective, including: providing specific system operations for a given UE tailored to specific application needs in terms of specific control plane operations (e.g., the UE may or may not require Mobile Terminating (MT) procedures, optimal operation of high capacity machine type communications (MTC), Critical Communications (CriC), etc.) and user plane operations (e.g., the UE may require slices supporting header compression); Provides a UE with access to resources, application domains, or tenants allocated to a particular service (e.g., a minimum level of guaranteed resources or total number of subscribers allowed to access a service at any one time).

[0014] So far, it appears that a number of key principles need to be applied to support network slicing in the RAN. First, for example, the RAN needs slice awareness. Specifically, the RAN needs to support differentiated handling of different network slices preconfigured by the operator. The RAN may also support selection of the RAN part of a network slice by an identifier such as a "slice ID" provided by the user equipment (UE). This identifier unambiguously identifies one of the network slices (or associated NSTs) preconfigured in the public land mobile network (PLMN). Similarly, the RAN may support resource management between slices (e.g., enforcement of inter-slice policies by service level agreements), QoS differentiation within slices, and / or resource isolation between slices. The RAN may also support RAN selection of Core Network (CN) entities for initial routing of uplink messages based, for example, on the received slice ID and the mapping (CN entity, supported slices) in the RAN node. If no slice ID is received, the RAN may select a CN entity based on a function such as a Non Access Stratum (NAS) Node Selection Function (NNSF), e.g., based on a UE temporary ID.

[0015] Since some slices may be available only in parts of the network, knowledge at a base station of the slices supported in its neighboring base station cells can be beneficial for inter-frequency mobility for UEs in connected mode. The slice configuration is assumed not to change within the registration area of ​​the UE.

[0016] The RAN and CN are responsible for handling service requests for slices that may or may not be available in a given area. Granting or denying access to a slice may depend on factors such as support for such slice, availability of resources, support of the requested service by other slices, etc. [Prior art documents] [Non-patent literature]

[0017] [Non-Patent Document 1] 'NGMN 5G White Paper' V1.0, Next Generation Mobile Networks (NGMN) Alliance, Internet<URL : https: / / www.ngmn.org / 5g-white-paper.html > Summary of the Invention [Problem to be solved by the invention]

[0018] However, the inventors have found that some problems may arise if not all slice types are available at each base station (e.g., due to local load or hardware limitations).

[0019] For example, in a sliced ​​RAN, a Mobility Management Entity (MME), or similar NG-Core network function, may improperly configure a paging / tracking area for a UE to include cells of base stations where the slice type supported by a given UE is not available, resulting in inefficient paging. Similarly, the MME (or similar NG-Core network function) may improperly configure roaming and access restrictions.

[0020] Also, in connected mode mobility, following a decision to handover the UE to a target base station based purely on signal strength, the target base station may attempt to use core network control plane and / or user plane functionality that is inappropriate for the slice that the UE is currently using. Furthermore, for on-demand system information at the target base station, all system information required by the UE to support that slice may not be available.

[0021] There are also many other issues not yet considered or recognized that need to be addressed in order to provide a functional slicing mechanism.

[0022] It can therefore be seen that there are many issues that need to be addressed in order to make significant progress towards providing a well-functioning and efficient slicing mechanism.

[0023] The present invention aims to provide an apparatus, and associated methods, that address one or more of these problems, thereby contributing, at least in part, to the provision of a practical slicing mechanism.

[0024] Notwithstanding the above recognized problems, the inventors have discovered that progress can be made towards a practical slicing mechanism by addressing several issues that have not yet been considered. [Means for solving the problem]

[0025] In one aspect of the present invention, a communications device for a communications system supporting network slicing is provided, comprising a controller and a transceiver, the controller configured to generate a message including slice support information indicating at least one slice support capability of the communications device, and to control the transceiver to transmit the message to a node of a core network.

[0026] In another aspect of the present invention, a core node for a core network of a communication system supporting network slicing is provided, the core node comprising a controller and a transceiver, the controller being configured to control the transceiver to receive a message from a communication device including slice support information indicating at least one slice support capability of the communication device, and to configure information stored in the core node based on the slice support information.

[0027] In another aspect of the present invention, a communications apparatus for a communications system supporting network slicing is provided, comprising a controller and a transceiver, wherein the controller is configured to control the transceiver to receive, as part of a handover procedure for at least one communication device, a message from another communication device including slice support information related to at least one slice supported by the at least one communication device, and to configure the communications apparatus to support communication of the at least one communication device based on the slice support information by at least one of selecting an appropriate slice-specific core network function based on the slice support information and enabling slice-specific on-demand system information based on the slice support information.

[0028] In another aspect of the present invention, there is provided a communications apparatus for a communications system supporting network slicing, comprising a controller and a transceiver, the controller being configured to: send a message to configure a communications device to perform measurements with respect to at least one neighboring cell of another communications device supporting a slice used by the communications device; control the transceiver to receive at least one associated measurement report from the communications device; and select a target for handover based on the at least one associated measurement report.

[0029] In another aspect of the present invention, a communications device for a communications system supporting network slicing is provided, comprising a controller and a transceiver, wherein the controller is configured to control the transceiver to receive messages from other communications devices as part of a procedure for configuring dual connectivity for at least one communications device, the messages including slice support information relating to at least one slice supported by the at least one communications device, and to configure the communications device for dual connectivity based on the slice support information.

[0030] In another aspect of the present invention, a communications apparatus for a communications system supporting network slicing is provided, comprising a controller and a transceiver, wherein the controller is configured to control the transceiver to receive a connection re-establishment message from at least one communications device as part of a connection re-establishment procedure, the connection re-establishment message including slice support information relating to at least one slice supported by the at least one communications device, and to configure the communications apparatus to support re-establishment of a connection with the communications device based on the slice support information.

[0031] In another aspect of the present invention, a communications device for a communications system supporting network slicing is provided, comprising a controller and a transceiver, the controller configured to control the transceiver to transmit a connection re-establishment message to a communications device as part of a connection re-establishment procedure, the connection re-establishment message including slice support information relating to at least one slice supported by the communications device.

[0032] In another aspect of the present invention, a communications apparatus for a communications system supporting network slicing is provided, comprising a controller and a transceiver, wherein the controller is configured to control the transceiver to receive from a core node at least one message for at least one communication device, the message including slice support information related to at least one slice used by the at least one communication device, and to configure the communications apparatus to support communication of the at least one communication device based on the slice support information.

[0033] In another aspect of the present invention, a method is provided, performed by a communication device in a communication system, generating a message including slice support information indicating at least one slice support capability of the communication device, and transmitting the message to a node of a core network.

[0034] In another aspect of the present invention, there is provided a method performed by a core node in a core network of a communication system supporting network slicing, comprising receiving a message from a communication device including slice support information indicating at least one slice support capability of the communication device, and configuring information stored in the core node based on the slice support information.

[0035] In another aspect of the present invention, there is provided a method performed by a communication device in a communication system supporting network slicing, comprising: receiving, as part of a handover procedure for at least one communication device, a message from another communication device including slice support information related to at least one slice supported by the at least one communication device; and configuring the communication device to support communication of the at least one communication device based on the slice support information by at least one of selecting an appropriate slice-specific core network function based on the slice support information and enabling slice-specific on-demand system information based on the slice support information.

[0036] In another aspect of the present invention, there is provided a method performed by a communication device in a communication system supporting network slicing, the method comprising: sending a message configuring the communication device to perform measurements on at least one neighboring cell of another communication device supporting a slice used by the communication device; receiving at least one associated measurement report from the communication device; and selecting a target for handover based on the at least one associated measurement report.

[0037] In another aspect of the present invention, a method is provided for a communication device in a communication system supporting network slicing, comprising: as part of a procedure for configuring dual connectivity for at least one communication device, receiving a message from another communication device including slice support information related to at least one slice supported by the at least one communication device; and configuring the communication device for dual connectivity based on the slice support information.

[0038] In another aspect of the present invention, there is provided a method performed by a communication device in a communication system supporting network slicing, comprising: receiving, as part of a connection re-establishment procedure, a connection re-establishment message from at least one communication device, the connection re-establishment message including slice support information relating to at least one slice supported by the at least one communication device; and configuring the communication device to support re-establishment of a connection with the communication device based on the slice support information.

[0039] In another aspect of the present invention, a method is provided, performed by a communication device in a communication system supporting network slicing, comprising: transmitting, as part of a connection re-establishment procedure, a connection re-establishment message to a communication device, the connection re-establishment message including slice support information relating to at least one slice supported by the communication device.

[0040] In another aspect of the present invention, a method is provided, performed by a communication device in a communication system supporting network slicing, comprising: receiving at least one message for at least one communication device from a core node, the message including slice support information related to at least one slice used by the at least one communication device; and configuring the communication device to support communication of the at least one communication device based on the slice support information.

[0041] Aspects of the invention extend to corresponding systems, methods and computer program products, such as computer readable storage media having stored thereon instructions operable to program a programmable processor or system to perform the methods described in the above aspects and possible methods as set out above or in the claims, and / or to program a computer suitably adapted to provide an apparatus as described in any of the claims.

[0042] Each feature disclosed in this specification (including the claim terminology) and / or shown in the drawings may be incorporated in the present invention independently (or in combination) with other disclosed and / or shown features. In particular, but not limited to, any feature of a claim dependent on a particular independent claim may be introduced into that independent claim in any combination or individually.

[0043] Although particular hardware apparatus having particular physical structures (e.g., controller and transceiver circuitry) for performing the various procedures described herein are disclosed, each step of the methods described herein and / or forming part of the claims may be performed by any suitable means for performing that step. Accordingly, each method aspect of the present invention has a corresponding apparatus aspect including respective means for performing each step of that method aspect.

[0044] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0045] [Figure 1] FIG. 1 illustrates diagrammatically a mobile telecommunications system of the type to which the present invention is applicable. [Diagram 2] FIG. 2 is a block diagram of the physical equipment for implementing a mobile telephone suitable for use in the telecommunications system of FIG. [Diagram 3] FIG. 3 is a block diagram of physical equipment for implementing a base station suitable for use in the telecommunications system of FIG. [Figure 4] FIG. 4 is a block diagram of physical equipment for implementing a distributed base station suitable for use in the telecommunications system of FIG. [Diagram 5] FIG. 5 is a block diagram of physical equipment for implementing core network functions suitable for supporting the provision of mobility management functions for use in the telecommunications system of FIG. [Figure 6]FIG. 6 is a block diagram of physical equipment for implementing core network functions suitable for supporting slice selection in the telecommunications system of FIG. [Figure 7] FIG. 7 is a simplified sequence diagram illustrating procedures performed between base stations and a core network to support configuration of paging areas and / or roaming and access restrictions in the telecommunications system of FIG. [Figure 8] FIG. 8 is a diagram illustrating how a handover restriction list may be constructed according to the procedure shown in FIG. [Figure 9] FIG. 9 is a simplified sequence diagram illustrating procedures that may be performed between user equipment and base stations in the telecommunications system of FIG. 1 to support connected mode mobility in the context of network slicing. [Figure 10] FIG. 10 is a diagram illustrating how a handover request may be constructed for use in the procedure shown in FIG. [Figure 11] FIG. 11 is a simplified sequence diagram illustrating procedures that may be performed between base stations of the telecommunications system of FIG. 1 to support dual connectivity in the context of network slicing. [Figure 12] FIG. 12 is a simplified sequence diagram illustrating procedures that may be performed between user equipment and base stations of the telecommunications system of FIG. 1 to support connection re-establishment in the context of network slicing. [Figure 13] FIG. 13 is a diagram showing how an RRC connection re-establishment request message may be configured for use in the procedure shown in FIG. [Figure 14] FIG. 14 is a simplified sequence diagram illustrating procedures that may be performed between base stations and core networks of the telecommunications system of FIG. 1 to support various communication processes in the context of network slicing. [Figure 15]FIG. 15 is a simplified sequence diagram illustrating another procedure that may be performed between a base station and a core network of the telecommunications system of FIG. 1 in the context of network slicing. [Figure 16] FIG. 16 is a diagram illustrating how different slices / slice types can be supported by different base stations. [Figure 17] FIG. 17 is a simplified block diagram illustrating a possible configuration of some possible slice specific core network functions and the interfaces / reference points between them. [Figure 18] FIG. 18 is a simplified schematic diagram illustrating how 'm' slice types and Z UEs for 'n' tenants can be supported via the radio access network and core network. [Figure 19] FIG. 19 is a simplified schematic diagram illustrating how slices for different UEs communicating over the same RAN may have different sets of slice-specific core network functions and / or common control plane network functions. [Figure 20] FIG. 20 is a simplified sequence diagram illustrating a typical connection procedure that may take place in a network including a slice selection function (SSF). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] overview FIG. 1 shows diagrammatically a mobile (cellular) telecommunication system 1 in which a number of differently configured network slices 2 are defined. Through the mobile telecommunication system 1, a Network Operator provides cellular services to different tenants based on their Service Level Agreements (SLAs). It is understood that the tenant concept allows the Network Operator to differentiate between different customer requirements and provide customized services using one / many slices. In this example, the mobile telecommunication system 1 operates as a next generation ("5G") system, but it is understood that many of the features described with reference to this example are more broadly applicable to other communication systems. The base stations 5 each form part of an associated Radio Access Network (RAN) for enabling User Equipment (UE) 3 (such as mobile phones / smartphones 3-1, 3-2, 3-3, MTC / IoT devices (not shown) and / or other mobile or fixed location communication devices) to connect to those networks and receive one or more associated services.

[0047] While Figure 1 shows what appears to be a "network-wide" slice, it is understood that this is for illustrative purposes only. The core may have its own slice, and may have a radio access network, RAN. Similarly, the control plane (CP) and user plane (UP) may have entirely different slices. Standardization and cellular operator policies may result in different mappings from RAN slices to core slices.

[0048] In this example, each UE 3 is provided with communication services by at least one tenant, which has its own unique tenant ID. Thus, with the tenant and slice concept, a network operator can provide communication services using one or more types of network slices 2 depending on the communication requirements of each tenant.

[0049] A Multi-Dimensional Descriptor (MDD) is configured in each UE 3 and represents at least the Tenant ID of the tenant to which it belongs and the Service Descriptor / Slice Type (partially governed by the Tenant ID) that they are entitled to use. The Service Descriptor / Slice Type may contain standardized and / or operator specific values. The MDD is essentially a matrix indicating in each of its rows the slices 2 that the UE 3 may request to access or address (hence the MDD is a vector if there is a single slice). A row in the MDD is called an MDD Vector. The MDD Vector has the combined purpose of identifying the tenant (identified by the Tenant ID component) and the network operation for the target network service (identified by the Slice Type component, e.g. enhanced Mobile Broadband (eMBB) service, Critical Communications (CriC), massive Machine Type Communications (mMTC), or other operation that may be operator specific).

[0050] Each tenant's respective UE 3 is served via one or more base stations 5-1, 5-2 of the telecommunications system 1. As will be appreciated by those skilled in the art, each base station 5 operates one or more cells 6-1, 6-2, 6-3 over which communication can take place between the base station 5 and the UE 3 using a suitable radio access technology, such as, for example, Evolved Universal Terrestrial Radio Access (E-UTRA) technology.

[0051] Each UE 3 may provide a respective Network Slice Selection Assistance Information (NSSAI), consisting of a set of parameters such as a network slice type ID, service type, and UE capabilities to the network (i.e., via gNB 5), to allow selection of a RAN (e.g., base station 5) and a core network portion (e.g., an appropriate core network function 7) of a network slice instance (NSI) for that UE.

[0052] The base station is configured to operate according to the next generation (5G) standard and in this example comprises a non-distributed gNB 5-1 and a distributed gNB 5-2. As seen in FIG. 1, the distributed gNB 5-2 in this example comprises a central unit (CU) 5-2b and a number of distributed units (DUs) 5-2a, each serving at least one associated cell.

[0053] Although a "gNB" type base station is described in this example, it will be understood that many of its functions can be extended to other base stations or similar devices to provide wireless access to UE3, such as mobile (cellular) phones / smartphones, MTC / IoT devices, and / or other mobile or fixed location communication devices.

[0054] The gNBs 5 are connected via an associated core network having a number of logical core network nodes 7 for supporting communications in the telecommunications system 1. The core network nodes 7 in this example implement, among other functions, at least one Control Plane (CP) function 7-1, at least one User Plane (UP) function 7-2, at least one network slice selection function (SSF (Slice Selection function)) 7-4, and several other functions 7-n, such as an Access Management Function (AMF) and a Session Management Function (SMF). Also, in this example, one of the core network nodes 7 may implement a Mobility Management Function 7-3 providing mobility management functionality, e.g., corresponding to an LTE Mobility Management Entity (MME). It is noted that although separate functions with specific names are described for illustrative purposes, the corresponding functions may be implemented in isolation or in combination by one or more appropriate core network nodes 7 implemented using dedicated circuitry and / or software instructions for controlling associated processors. For example, the slice selection function 7-4 may be implemented as part of any suitable core network node 7, such as a core node 7 implementing a mobility management function 7-3.

[0055] In this example, the User Plane Function 7-2 comprises at least one, and typically several, so-called Terminating User Plane Functions (TUPFs) for terminating user plane traffic and interfacing with the data network. By way of additional background, 3GPP Technical Report (TR) 23.799 V0.7.0 introduces the concept of a TUPF, which is effectively a logical network node coupled to one or more cells (gNBs). It is assumed that appropriate Protocol Data Unit (PDU) sessions are provided between the TUPFs and the respective connected UEs 3 (i.e. UEs served by the base stations coupled to that TUPF).

[0056] To enable a particular UE 3 to know as early as possible whether the tenant IDs and / or slice types that the UE allows are supported in a particular cell, information identifying the supported tenant IDs, (per tenant ID) slice types, and TUPF 7-2 is broadcast by the corresponding gNB 5 in system information (e.g., System Information Blocks "SIBs" such as SIB2 in LTE). The UE 3 can then listen to the relevant SIBs in order to ascertain whether a given cell supports a particular desired tenant ID, per tenant ID slice type, and / or TUPF. Support for a particular desired tenant ID, per tenant ID slice type, and / or TUPF can be ascertained based on the MDD, UE capabilities, and / or USIM configuration. Once the UE 3 identifies that its desired tenant ID, per tenant ID slice type, and TUPF are supported by the cell 6 based on the system information broadcast by the gNB 5, the UE 3 can then camp on the cell 6 for any of a variety of different purposes (e.g., to request an initial access procedure or a service).

[0057] Thus, the gNB 5 can dynamically change the tenant IDs, slice types per tenant ID, and / or TUPFs supported in a particular cell 6 (e.g., based on operator requirements, demand, etc.), and the UE 3 can identify whether the allowed tenant IDs and / or slice types are supported within that cell 6.

[0058] System Information (SI) includes minimum system information (e.g., including a subset of System Information Blocks (SIBs) such as Master Information Block (MIB), SIB1, SIB2, and SIB14) that carries the "minimal" set of information elements (e.g., those elements required to support cell selection, obtain Other System Information (OSI), or access a cell). System Information also includes OSI, which contains all system information in other SIBs typically available in a telecommunications system. Minimum system information is transmitted periodically, whereas OSI may be broadcast periodically or broadcast / unicast on demand.

[0059] Advantageously, in an exemplary manner described in more detail below, the telecommunications system shown in FIG. 1 provides a number of procedures that may be performed between base stations 5 of the type shown in the telecommunications system of FIG. 1 and a core network 7 to support efficient configuration of paging areas and / or roaming and access restrictions.

[0060] Preferably, in an exemplary manner described in more detail later, the telecommunications system shown in FIG. 1 also provides several procedures that may be performed between different types of base stations 5 shown in the telecommunications system of FIG. 1 to support connected mode mobility, dual mode connectivity setup and connection re-establishment in the context of network slicing.

[0061] Preferably, in an exemplary manner described in more detail below, the telecommunications system shown in FIG. 1 also provides several procedures that may be performed between a base station of the type shown in the telecommunications system of FIG. 1 and the core network 7 to support UE context setup and modification, connected mode mobility, efficient paging and slice selection.

[0062] User Equipment Figure 2 is a block diagram illustrating the main components of the user equipment 3 (such as a mobile phone) shown in Figure 1. As shown, the UE 3 has transceiver circuitry 231 operable to transmit signals to and receive signals from a base station 5 (such as a gNB) via one or more antennas 233. Although not necessarily shown in Figure 2, the UE 3 may of course have all the usual functionality of a conventional UE 3 (such as a user interface 235), which may be provided by any one or any combination of hardware, software and firmware as appropriate. The UE 3 has a controller 237 for controlling the operation of the user equipment 3.

[0063] The controller 237 is connected to the memory 239 and coupled to the transceiver circuitry 231. For example, the software may be pre-installed in the memory 239 and / or downloaded over a telecommunications network or from a Removable Data Storage Device (RMD).

[0064] The controller 237, in this example, is configured to control the overall operation of the UE 3 by way of program or software instructions stored in memory 239. As shown, these software instructions include, among others, an operating system 241, a communications control module 243, a slice / tenant information module 245, a Radio Resource Control (RRC) entity 247, a Medium Access Control (MAC) entity 249, a Physical layer (PHY) entity 251, a Non-Access Stratum (NAS) module 252, and a measurement module 253.

[0065] The memory 239 also includes configuration information 255 used by the UE 3 for communication and control purposes. Typically this information includes, among other things, a Multi-Dimensional Descriptor (MDD) (if configured for the UE 3), information identifying the communication and other capabilities of the UE, and information identifying how to configure a Subscriber Identity Module (SIM), e.g. a Universal SIM (USIM).

[0066] The communication control module 243 is operable to control the communication between the UE 3 and the base station 5 shown in Fig. 1. The communication control module 243 also controls the separate flow of uplink data and control data to be transmitted to the base station 5, and controls the reception of downlink data and control data transmitted by the base station 5. The communication control module 243 is responsible for managing parts of the UE in idle and connected mode procedures such as cell (re)selection, camping on a cell, listening to system information, Random Access Channel (RACH) procedures, etc.

[0067] The slice / tenant information module 245 is responsible for managing and maintaining information identifying the tenant to which the UE 3 belongs and information identifying the slices / slice types that the UE 3 can use.

[0068] The RRC entity 247 is responsible for controlling the RRC layer functionality of the UE 3 (under the overall control of the communication control module 243). The MAC entity 249 is responsible for controlling the MAC layer functionality of the UE 3 (under the overall control of the communication control module 243). The PHY entity 251 is responsible for controlling the physical layer functionality of the UE 3 (under the overall control of the communication control module 243). The NAS module 252 is responsible for controlling the NAS functionality of the UE 3 (under the overall control of the communication control module 243).

[0069] The measurement module 253 handles performing measurements of communication conditions (e.g., received signal power and quality) in the serving cell and neighboring cells (e.g., based on a measurement configuration and control information received from the base station 5). The measurement module 253 also generates associated measurement reports for transmission to the base station 5.

[0070] Non-distributed base station (gNB) Figure 3 is a block diagram illustrating the main components of a non-distributed gNB 5-1 of the type shown in Figure 1. As shown, the gNB 5-1 includes a transceiver circuit 351 operable to transmit signals to and receive signals from the UE 3 via one or more antennas 353, and to transmit signals to and receive signals from the core network 7 and / or other gNB 5 functions via a network interface 355. The network interface 355 typically includes an interface such as S1 for communicating with the core network and a gNB to gNB interface (e.g., X2) for communicating with other gNBs. A controller 357 controls the operation of the transceiver circuit 351 according to software stored in memory 359. The software includes, among other things, an operating system 361, a communication control module 363, and a network slice / tenant management module 364.

[0071] The communication control module 363 is operable to control communication between the gNB 5-1 and the UE 3 and other network entities connected to the gNB 5-1. The communication control module 363 also controls separate flows of uplink and downlink user traffic and control data for receiving from and transmitting to communication devices served by the gNB 5-1, including, for example, control data for managing the operation of the UE 3. The communication control module 363 is responsible for controlling procedures such as, for example, measurement control / configuration information, communication of system information (on-demand and periodic), the gNB's part in the Random Access Channel (RACH) procedures. The communication control module 363 is also responsible for managing the gNB's part in the setup, configuration, and reconfiguration of gNB-to-gNB interfaces with neighboring gNBs, and in the setup, configuration, and reconfiguration of gNB to core network interfaces with core network nodes 7 (such as mobility management function 7-3). The communication control module 363 is also responsible for managing the gNB's part in handovers (both gNB-to-gNB interface based and gNB-to-core network interface based), including handover decisions (where applicable), target selection, etc. The communication control module 363 is also responsible for managing the gNB's part in UE context setup and modification procedures, dual connectivity (e.g., operating as master or secondary gNB, adding and managing secondary gNBs, etc.), connection (re)establishment procedures with the UE 3, and paging procedures.

[0072] The network slice / tenant management module 364 is operable to store and manage configuration data 365 for defining, per service / tenant, the various radio access network (RAN) slices available via gNB5-1.

[0073] Distributed base station (gNB) Figure 4 is a block diagram illustrating the main components of a distributed gNB 5-2 of the type shown in Figure 1. As shown, the gNB 5-2 includes a distributed unit 5-2a and a central unit 5-2b. Each unit 5-2a, 5-2b includes transceiver circuitry 451a, 451b, respectively. The transceiver circuitry 451a of the distributed unit 5-2a is operable to transmit signals to and receive signals from the UE 3 via one or more antennas 453a, and is operable to transmit signals to and receive signals from the central unit 5-2b via an interface 454a.

[0074] The transceiver circuitry 451b of the central unit 5-2b is operable to transmit signals to and receive signals from the core network 7 and / or other gNB 5 functions via a network interface 456b. The network interface 456b typically includes an S1-like interface for communicating with the core network and a gNB-to-gNB interface (e.g., X2-like) for communicating with other gNBs. The transceiver circuitry 451b of the central unit 5-2b is also operable to transmit signals to and receive signals from one or more distributed units 5-2b via an interface 454b.

[0075] Each unit 5-2a, 5-2b includes a respective controller 457a, 457b that controls the operation of the corresponding transceiver circuit 451a, 451b in accordance with software stored in the respective memories 459a and 459b of the distributed unit 5-2a and the central unit 5-2b. The software of each unit includes, among other things, a respective operating system 461a, 461b, a respective communication control module 463a, 463b, a respective network slice / tenant management module 464a, 464b, and a respective DU / CU function partition management module 467a, 467b.

[0076] Each communication control module 463a, 463b is operable to control the communications of the corresponding unit 5-2a, 5-2b, including communications from one unit to the other. The communication control module 463a of the distributed unit 5-2a controls communications between the distributed unit 5-2a and the UEs 3, and the communication control module 463b of the central unit 5-2b controls communications between the central unit 5-2b and other network entities connected to the gNB 5-2.

[0077] The communication control modules 463a, 463b are also responsible for controlling the parts operated by the distributed units 5-2a and the central unit 5-2b, respectively, in the flow of uplink and downlink user traffic and control data for transmission to communication devices served by the gNB 5-2, including, for example, control data for managing the operation of the UE 3. Each communication control module 463a, 463b is responsible for controlling the parts operated by the distributed units 5-2a and the central unit 5-2b, respectively, in procedures such as, for example, measurement control / configuration information, communication of system information (on-demand and periodic), the gNB's part in the Random Access Channel (RACH) procedures, etc. Each communication control module 463a, 463b is also responsible for controlling the parts operated by the distributed units 5-2a and the central unit 5-2b, respectively, in the management of, for example, the gNB's part in the setup, configuration, and reconfiguration of gNB-to-gNB interfaces with neighboring gNBs, and with the core network nodes 7 (such as the mobility management function 7-3). Each communication control module 463a, 463b is also responsible for controlling the respective parts operated by the distributed unit 5-2a and the central unit 5-2b in managing the gNB part of the handover, including, for example, handover decision (where applicable), target selection, etc. Each communication control module 463a, 463b is also responsible for controlling the parts operated by the distributed unit 5-2a and the central unit 5-2b in managing the gNB part of, for example, UE context setup and modification procedures, dual connectivity (e.g., operation as master or secondary gNB, adding and managing secondary gNBs, etc.), connection (re)establishment procedures with UE 3, and paging procedures.

[0078] Each network slice / tenant management module 464a, 464b is operable to perform the respective parts operated by the distributed unit 5-2a and the central unit 5-2b in storing and managing configuration data for defining, per service / tenant, various radio access network (RAN) slices available via the gNB 5-2.

[0079] Each DU / CU functional division management module 467a, 467b is responsible for the respective parts operated by the distributed unit 5-2a and the central unit 5-2b in managing, configuring, and reconfiguring the functional division between the distributed unit 5-2a and the central unit 5-2b.

[0080] Mobility Management Function Figure 5 is a block diagram illustrating the main components of a core node 7 providing a mobility management function 7-3 (e.g. a mobility management entity (MME)). The core node 7-3 comprises a transceiver circuit 571 operable to transmit signals to and receive signals from the gNB 5 and / or other nodes (e.g. other core nodes providing other core network functions) via a network interface 575. A controller 577 controls the operation of the transceiver circuit 571 in accordance with software stored in a memory 579. The software includes, among other things, an operating system 581, a communication control module 583, and a mobility management module 584.

[0081] The communications control module 583 is operable to control direct and / or indirect communications between the core node 7-3 and other network entities connected (directly or indirectly) to the core node 7-3 (e.g., gNBs 5 and other core nodes 7 providing other core network functions).

[0082] The mobility management module 584 is responsible for providing mobility management functions for the core node 7 including, for example, control of the radio access network, idle mode UE paging, bearer activation / deactivation functions, selection of an appropriate core node 7 (e.g., Serving Gateway and / or TUPF) for the UE 3 upon initial attach and upon handover involving core node relocation. It is also responsible for user authentication, Non-Access Stratum (NAS) signaling termination, generation and assignment of temporary identities to UEs, and other functions.

[0083] Slice selection function Figure 6 is a block diagram illustrating the main components of a core node 7 providing slice selection functionality 7-4. The core node 7-4 comprises a transceiver circuit 671 operable to transmit signals to and receive signals from the gNB5 and / or other nodes (e.g., other core nodes providing other core network functions) via a network interface 675. A controller 677 controls the operation of the transceiver circuit 671 according to software stored in a memory 679. The software includes, among other things, an operating system 681, a communication control module 683, and a slice selection management module 684.

[0084] The communications control module 683 is operable to control direct and / or indirect communications between the core node 7-4 and other network entities connected (directly or indirectly) to the core node 7-4 (e.g., gNBs 5 and other core nodes 7 providing other core network functions).

[0085] The slice selection management module 684 is responsible for providing slice selection related functions of the core node 7-4 including, for example, selecting an appropriate slice for the UE 3 in response to the UE's initial attach request and / or new session establishment request.

[0086] Other Features Although not described in detail, it will be appreciated that other core network functions (e.g., AMF and SMF) may be implemented in a manner similar to that shown in Figures 5 and 6 by means of suitable transceiver circuitry for transmitting signals to and receiving signals from the gNB 5 and / or other nodes (e.g., other core nodes 7 providing other core network functions) and a controller for controlling operation of the transceiver circuitry in accordance with software stored in memory. The software typically includes, among other things, an operating system, a communication control module, and other modules specific to the functionality of that core network function.

[0087] In the above description, the mobile phone, the UE 3, the gNB 5, and the core network node 7 implementing the core network functions are described as having several separate modules for ease of understanding. These modules may be provided in this way for a particular application, but in other applications, for example when an existing system is modified to implement the invention, for example in a system designed from the beginning with the features of the invention in mind, these modules may be incorporated into an overall operating system or code, so that they may not be recognizable as separate entities. These modules may also be implemented in software, hardware, firmware, or a combination of these.

[0088] Described herein, merely by way of example, are several procedures that may be implemented to help provide an efficient slicing mechanism having several advantages, it being understood that each of these procedures may provide an independent technical advantage when implemented alone, or any combination of these procedures may be implemented together.

[0089] Setting paging areas, roaming and access restrictions Figure 7 shows procedures that may be performed between a base station of the type shown in the telecommunications system of Figure 1 and a core network node 7 (e.g. a mobility management function 7-3) to support efficient configuration of paging areas and / or roaming and access restrictions in the context of network slicing.

[0090] In the procedure of Figure 7, the core network node 7 obtains information from the gNB 5 to assist in the configuration of paging areas and / or handover restriction lists. This information includes information identifying tracking areas and / or paging areas (e.g. Tracking Area Code (TAC) and / or RAN paging area code) as well as information identifying hardware capabilities and / or information identifying a list of NSTs that can be supported by the gNB 5. From this information, the core network node 7 is able to identify slice support and configure paging areas and / or roaming and access restrictions depending on the UE, taking into account UE capabilities, SLAs for slice support, tenant type.

[0091] In the procedure of Figure 7(a), information to assist in the configuration of the paging area and / or handover restriction list is obtained during a gNB-core network interface setup procedure (e.g., an S1 setup procedure or an NG-C setup procedure). In particular, the gNB 5 provides that information to the core network node 7 by an Interface Setup Request (e.g., an S1 setup request or an NG-C setup request) at S700. The core network node 7 configures the interface accordingly and, upon successful interface setup, responds with an appropriate Interface Setup Response message at S702.

[0092] Preferably, the RAN-core slice mapping details may be provided by the core network node 7 (e.g. AMF / Mobility Management Function) in an Interface Setup Response message. This slice mapping information may be used by the base station 5 when implementing a Non Access Stratum (NAS) node selection function or similar process to select one or more specific CN nodes to which Initial NAS Signalling messages should be routed.

[0093] In the procedure of Figure 7(b), information to assist in the configuration of the paging area and / or handover restriction list is obtained during a base station configuration update procedure (e.g. an eNB / gNB / NR-BS setup procedure). In particular, the gNB 5 provides that information to the core network node 7 by an eNB / gNB / NR-BS Configuration Update message at S704. The core network node 7 updates its eNB / gNB / NR-BS configuration accordingly and, upon successful eNB / gNB / NR-BS configuration update, responds with an appropriate eNB / gNB / NR-BS Configuration Update Acknowledge message at S706, which may include details of the core-RAN slice mapping if required.

[0094] Regardless of how the core network node 7 obtains its information, the core network function 7 may configure a paging area for a given UE 3 based on the supported slice type of the UE 3 and gNB 5 from which the information was received (as shown in S708).

[0095] To optimize paging such that paging is performed only in cells that support slice types supported by the UE 3 being paged, if the paging message is sent to a gNB 5 in a tracking area associated with the paged UE (e.g., as shown in S710), the paging message (Paging Request) may include Assistance Data for Paging Information Element (IE) identifying cells that should (and / or may not) be paged (e.g., in a Preferred Cells IE or similar IE). Thus, as shown, that information may be provided as part of the Assistance Data for Paging passed by a core network entity (e.g., Mobility Management Function / MME) to the base station (eNB / gNB) in the paging request.

[0096] Regardless of how the core network node 7 obtains its information, the core network function 7 may also configure a handover restriction list for a given UE 3 to identify forbidden tracking areas, location areas and / or cells, which may be based on the UE's service level agreements (as shown in S712), the UE capabilities, and supported slice types of the UE 3 and the gNB 5 from which the information was received.

[0097] As shown in S714, the handover restriction list for a given UE 3, once configured, can be sent to the gNB 5 to which the UE 3 is connected in an Initial Context Setup Request message from the core network node 7 during an initial context setup procedure for that UE 3. As shown in S714, the handover restriction list for a given UE 3, once configured, can also be sent to the gNB 5 to which the UE is handing over (e.g., a target gNB) in a handover request message from the core network node 7 during a handover procedure (e.g., a gNB-core network interface based handover procedure).

[0098] For completeness, it is understood that the availability of a slice type network for which a UE is configured to be allowed to register may also be configured by an Operations, Administration and Management (OAM) function.

[0099] As shown in S716, the core network node 7 may also configure one or more Allowed Cell Lists (ACLs) based on the eNB / gNB capability information regarding slice support information collected via the above-mentioned signaling mechanism (or OAM-based configuration). In particular, the core network node 7 (e.g., Mobility Management Function / AMF) may configure an ACL per Tracking Area and / or per RAN routing area for each UE 3 based on the UE capability, the SLA requirements regarding slice support, and the tenant ID. The configured ACL may be included in an Initial Context Setup Request message sent by the core network node 7 (e.g., at the time of the Service Request and / or Tracking Area Update (TAU)). Preferably, the configuration per TA and / or RAN routing area limits the number of cells included in the ACL. Thus, the UE 3 may camp on the cells identified in the corresponding ACL, and the need to broadcast the slice types, tenant types supported by each base station may be avoided or at least minimized.

[0100] 8 shows, by way of example, how a Handover Restriction List can be configured to allow handovers to be restricted at the Cell Granularity Level (i.e., not at the TA granularity level) based on slice type, gNB5 and / or tracking area, UE SLA and / or UE capability supported by the cell. Specifically, the Handover Restriction List is configured to include a Forbidden Cell-List 800 in the form of a list of base station / cell identifiers (e.g., global eNB IDs (or equivalent gNB IDs) with an associated list of E-UTRAN cell global identifiers (or equivalent 5G / NG cell identifiers).

[0101] Therefore, preferably, when a handover is requested, the source gNB5 (e.g., the gNB serving the UE3) can select a target gNB based, at least in part, on the prohibited cell list 800 in the handover restriction list.

[0102] It is understood that in legacy LTE systems, all eNBs are the same from the MME's perspective, and this changes when slicing is adopted. Configuring handover restriction lists at cell level granularity (as opposed to TA level access restrictions) beneficially allows the differences between gNBs caused by slicing to be understood at the gNBs and taken into account within the system.

[0103] Support for connected mode mobility (based on gNB to gNB interfaces) Figure 9 shows procedures that may be performed between a base station 5 and user equipment 3 of the type shown in the telecommunications system of Figure 1 to support gNB-to-gNB interface based mobility in the context of network slicing.

[0104] In the example of FIG. 9, the (source) gNB(A) configures the UE 3 to perform appropriate Neighbour Cell Measurements on neighbouring gNBs such as gNB(B) (and possibly the serving gNB) using the appropriate Measurement Control message sent in S900. It is understood that the source base station can limit the number of target candidates for measurement purposes to those that support the slices of interest to the UE in question. The source can collect the hardware and slice support capabilities of the targets by exchanging such information at X2 / Xn setup or at periodic eNB configuration updates. The UE 3 performs the configured measurements in S901 and reports the measurements with at least one Measurement Report message in S902. It is understood that this mechanism can be extended to enable the gNB 5 to obtain and exchange neighbour gNB information for any supported tenant / slice type and / or for any Hardware / Frequency-Specific Slice.

[0105] The gNB(A) then makes a handover decision. In this example, as shown in S904, the gNB(A) simply selects a target gNB (e.g., gNB(B)) based on signal strength measurements. However, by limiting the number of target candidates to those that support the slices of interest to the UE in question, the selected target is a gNB that supports the preferred slice type. Once the decision is made, the gNB(A) then transmits a handover request to the selected target gNB(B)5 at S906. This handover request message preferably includes Slice Usage Information that identifies the slice type used by the UE3. In this example, the slice usage information includes a slice identifier (sometimes referred to as a "slice type identifier") that represents a particular NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown in FIG. 9, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the handover request message also includes the associated MDD (i.e., tenant ID and / or slice type) and / or network slice selection assistance information (NSSAI), including, for example, UE capabilities, service types associated with the slice, and possibly requested services. The handover request message also includes information identifying the target gNB5 (gNB(B) in this example) and / or the target cell.

[0106] Preferably, in S908, the target gNB5 (gNB(B)) uses the received information to select a Slice Specific Control Plane and User Plane Network Function (e.g., the correct CCNF), which may be subject to Admission Control by the target for a given UE, taking into account its SLA requirements and current load. Preferably, in S910, if on-demand system information is enabled, the target gNB5 (gNB(B)) also uses the received information to identify whether slice specific system information needs to be made available, and if so, enables (switches on) the slice specific system information.

[0107] At S912, the gNB(B)5 responds to the handover request message with a Handover Acknowledge message (typically including a handover command sent by the source gNB(A)5 to the UE3 to initiate the handover).

[0108] The remainder of the handover process may proceed according to procedures well known to those skilled in the art (eg, at S914) and will not be described in detail for the sake of brevity.

[0109] FIG. 10 illustrates, by way of example, how a Handover Request message may be configured to provide slice usage and related information. Specifically, as seen at 1000 in FIG. 10, the Handover Request message is configured to include an MDD information element (IE) including an MDD vector for the UE 3 that allows the UE 3 to identify the customer type, tenant ID, and service level agreement, a UE Temporary Identifier IE (typically specific to a particular AMF and / or gNB) including information for identifying the UE 3, and a Slice Usage List IE. The Slice Usage List IE includes, for each slice used by the UE 3, a respective Slice Type (NST) ID IE to provide a slice ID representing the associated NST of that slice, and a respective NG-C CP NF ID information element (e.g., identifying the appropriate Common Control Network Function (CCNF) ID) including an identifier (e.g., AMF ID, SMF ID, and / or UPF ID) for each associated network function associated with that slice.

[0110] 10, the handover request may include a Quality of Service (QoS) Flow ID information element that identifies the relevant traffic flows associated with a particular Quality of Service (QoS), e.g., downlink Forwarding information and information identifying uplink GPRS Tunneling Protocol (GTP) tunnel endpoints for the QoS flows. While the slice ID may indicate Coarse-granular QoS, the indication of QoS preferably provides an indication of Fine-granular QoS that may be obtained from the MDD.

[0111] Thus, preferably, the target gNB 5 can know exactly which slice type the UE 3 is using among those to which the UE is subscribed, and can therefore beneficially determine, based on the associated SLA, what communication behavior the UE 3 requires with respect to the slices it subscribes to and uses, and thus select the core network functions 7 (e.g. slice-specific SMF, AMF, UPF and / or common control plane functions) accordingly (which may be subject to local admission controls and network-wide policies in terms of how to treat UEs belonging to a given tenant ID). Furthermore, this allows the adoption of common or slice-specific authentication procedures.

[0112] The presence of the slice ID and MDD in the handover request message also provides improved admission control and load management because by providing the MDD and slice ID information, the network can determine how many UEs of a particular tenant can access a particular slice at a given point in time (e.g., when the SLA is at its maximum limit).

[0113] Dual Connectivity Support Figure 11 illustrates procedures that may be performed between base stations 5 of the type shown in the telecommunications system of Figure 1 to support dual connectivity in the context of network slicing, where a so-called "master" base station (MeNB / MgNB) provides overall control and provides a subset of communication support for the UEs 3 (e.g. control plane communications and / or some user plane communications), and a so-called "secondary" base station (SeNB / SgNB) provides other communication support for the UEs (e.g. some / all user plane communications).

[0114] 11, in S1100, a message (in this example, an SeNB / SgNB Addition Request message) is sent from a first base station 5 (in this example, gNB(A)) to a second base station 5 (in this example, gNB(B)) to request gNB(B) 5 to allocate resources for dual connectivity operation for the specific UE. This message essentially requests the setup of dual connectivity for the specific UE, where gNB(A) 5 is configured as a master gNB and gNB(B) 5 is configured as a secondary gNB.

[0115] The SeNB / SgNB addition request message includes slice usage information that identifies the slice type used by the UE3. In this example, the slice usage information includes a slice identifier (sometimes also referred to as a "slice type identifier") that indicates a specific NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown in FIG. 11, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., in the case where AMF, SMF, and UPF are slice-specific). Preferably, the SeNB / SgNB addition request message also includes the associated MDD (i.e. tenant ID and / or slice type) and / or Network Slice Selection Assistance Information (NSSAI), e.g. including UE capability information, service types associated with the slice, and possibly requested services.

[0116] Preferably, the gNB(B)5 uses the received information to set up dual connectivity, e.g. to select slice specific user plane network functionality.

[0117] At S1102, gNB(B)5 responds to the SeNB / SgNB addition request message with an appropriate acknowledgement message (e.g., an SeNB / SgNB Addition Request Acknowledge message).

[0118] Connection re-establishment support FIG. 12 illustrates procedures that may be carried out between a base station 5 and user equipment 3 of the type shown in the telecommunications system of FIG. 1 to support connection re-establishment.

[0119] As can be seen in the example of Figure 12, in S1200 a message (in this example an RRC Connection Reestablishment Request message) is sent from the UE 3 to the base station 5 to re-establish the connection. In S1202, the base station 5 responds with an appropriate message (e.g. an RRC Connection Reestablishment message). To complete the connection re-establishment, the UE 3 sends an appropriate completion message (in the figure RRC Connection Reestablishment complete).

[0120] The RRC Connection Re-establishment Request (Figure 12(a)) or the RRC Connection Re-establishment Complete message (Figure 12(b)) includes a slice identifier (which may be sent along with or form part of the Network Slice Selection Assistance Information (NSSAI)) and an associated tenant ID (which may form part of the MDD vector).

[0121] Preferably, the base station 5 is therefore able to use the received information to re-establish the required connection.

[0122] FIG. 13 illustrates, at 1300, by way of example, how an RRC Connection Reestablishment Request message may be configured to provide a slice identifier and associated tenant ID when the RRC Connection Reestablishment Request is extended to include slice and tenant specific information.

[0123] Base Station-Core Network Procedures Figures 14 and 15 show, in the context of network slicing, some procedures that may be performed between base stations 5 and core network nodes 7 of the telecommunications system of Figure 1 to support various communication processes.

[0124] FIG. 14(a) shows a procedure that may be performed over a base station 5 to core network node 7 interface (e.g., an S1-like interface or an NG-C interface) to support setup of an Initial UE Context.

[0125] As can be seen in FIG. 14(a), when a context needs to be set up for a UE 3, a core network node 7 (e.g. a mobility management function 7-3 or other CN function described herein) initiates a context setup procedure at S1400 by sending an appropriate message (in this example an Initial Context Setup Request message) to the base station 5.

[0126] The initial context setup request message includes slice usage information that identifies the slice type used by the UE 3. In this example, the slice usage information includes a slice identifier (sometimes referred to as a "slice type identifier") that indicates a specific NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the initial context setup request message also includes an associated MDD (i.e., tenant ID and / or slice type) and / or a network slice selection assistance information (NSSAI) that includes, for example, UE capability information, a service type associated with the slice, and possibly a requested service.

[0127] The base station 5 uses the slice usage and other relevant information provided in the initial context setup request message to set up the initial context for the UE 3 and responds with an appropriately formatted response message (in this example, an Initial Context Setup response message) at S1402.

[0128] Figure 14(b) shows a procedure that may be performed over the base station 5 to core network node 7 interface (e.g. an S1-like interface or an NG-C interface) to support UE context modification.

[0129] As can be seen in FIG. 14(b), if the context needs to be modified for the UE 3, the core network node 7 (e.g., a mobility management function 7-3 or other CN function described herein) initiates a context modification procedure by sending an appropriate message (in this example a UE Context Modification Request message) to the base station 5 at S1404.

[0130] The UE context modification request message includes slice usage information that identifies the slice type used by the UE 3. In this example, the slice usage information includes a slice identifier (sometimes referred to as a "slice type identifier") that indicates a specific NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the UE context modification request message also includes an associated MDD (i.e., tenant ID and / or slice type) and / or a network slice selection assistance information (NSSAI) that includes, for example, UE capability information, a service type associated with the slice, and possibly a requested service.

[0131] The base station 5 uses the slice usage and other relevant information provided in the UE Context Modification Request message in modifying the UE context for the UE 3 and responds at S1406 with an appropriately formatted response message (in this example a UE Context Modification Response message).

[0132] Figure 14(c) shows a procedure that may be performed via the base station 5 to core network node 7 interface (e.g., an S1-like interface or an NG-C interface) to support a RAN-CN interface based handover (e.g., an S1-like handover).

[0133] As can be seen in FIG. 14(c), if a handover is required for the UE, the core network node 7 (e.g., a mobility management function 7-3 or other CN function described herein) requests a handover to the base station 5 (i.e. the selected target gNB) by sending an appropriate message (in this example a Handover Request message) to the base station 5 at S1408.

[0134] The handover request message includes slice usage information that identifies the slice type used by the UE 3. In this example, the slice usage information includes a slice identifier (sometimes referred to as a "slice type identifier") that indicates a specific NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the handover request message also includes an associated MDD (i.e., tenant ID and / or slice type) and / or a network slice selection assistance information (NSSAI) that includes, for example, UE capability information, a service type associated with the slice, and possibly a requested service.

[0135] The base station 5 uses the slice usage and other relevant information provided in the handover request message in the handover process (e.g., in the manner described with reference to FIG. 9 by selecting appropriate core network UP and CP functions and / or enabling system information as necessary) and responds at S1410 with a suitably formatted response message (in this example a Handover Acknowledge message).

[0136] Figure 14(d) shows a procedure that may be performed via the base station to core network node 7 interface (e.g., an S1-like interface or an NG-C interface) to support a gNB-gNB interface based handover (e.g., an X2-like handover).

[0137] As seen in Figure 14(d), at S1412, during a gNB-gNB interface based handover of the UE 3 (e.g., as generally described with reference to Figure 9), the base station 5 (i.e., the selected target gNB) sends a Path Switch Request message to the core network node 7 (e.g., a mobility management function 7-3 or other CN function described herein) during the handover process (e.g., during the procedure represented by S914 in Figure 9). The core network node 7 responds by sending a Path Switch Acknowledge message to the base station 5 at S1414.

[0138] The path switch acknowledgement message includes slice usage information that identifies the slice type used by the UE 3. In this example, the slice usage information includes a slice identifier (also referred to as a "slice type identifier") that indicates a specific NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the path switch acknowledgement message also includes the associated MDD (i.e., tenant ID and / or slice type) and / or network slice selection assistance information (NSSAI) including, for example, UE capability information, service types associated with the slice, and possibly requested services.

[0139] It will be appreciated that the provision of slice usage and other related information in the path switch acknowledgement message may be done by adding or replacing the information in the handover request message, as described with reference to FIG. 9.

[0140] The base station 5 uses the slice usage and other relevant information provided in the path switch acknowledgement message in the handover process (e.g., in the manner described with reference to FIG. 9 by selecting appropriate core network UP and CP functions and / or by enabling system information as necessary).

[0141] FIG. 14(e) illustrates a procedure that may be performed over a base station-to-core network interface (eg, an S1-like interface or an NG-C interface) to support a paging procedure.

[0142] As seen in FIG. 14(e), if paging requires contacting UE 3, the core network node 7 (e.g., a mobility management function 7-3, or other CN function described herein) causes the base station 5 to page for UE 3 in a cell that supports the requested slice and tenant ID that the base station 5 is operating in, by sending an appropriate message (in this example a paging message) to the base station 5 in S1416.

[0143] The paging message includes slice usage information that identifies the slice type used by the UE 3 (paged and / or paging). In this example, the slice usage information includes a slice identifier (sometimes referred to as a "slice type identifier") that indicates a particular NST for each slice in use. The slice usage information may also include other information, such as information identifying one or more Next Generation Core Network Control Plane Functions (NG-C CP NFs) (e.g., by appropriate Common Control Network Function (CCNF) IDs). As shown, the identified core network functions may include information identifying one or more AMFs (e.g., identified by AMF IDs), one or more SMFs (e.g., identified by SMF IDs), and / or one or more user plane functions (e.g., identified by UPF IDs) associated with the slice (e.g., where AMF, SMF, and UPF are slice-specific). Preferably, the paging message also includes the associated MDD (i.e. tenant ID and / or slice type) and / or Network Slice Selection Assistance Information (NSSAI) including, for example, UE capability information, the service type associated with the slice, and possibly the requested service.

[0144] Figure 15 is a simplified sequence diagram illustrating a slice update procedure that may be performed between a base station 5 and a core network node 7 of the telecommunications system of Figure 1 in the context of network slicing.

[0145] In the procedure of Figure 15, a core network node (e.g., Mobility Management Function, AMF, SMF, etc.) provides a slice ID and / or tenant ID to a base station 5 (e.g., a target gNB before and after movement) using a dedicated "slice update" procedure.

[0146] As can be seen in the example of Figure 15, at S1500 an appropriate message (in this example a Slice Update Request message) is sent from the core network node 7 to the base station 5. The slice update request includes a slice identifier (which may be sent together with or form part of the Network Slice Selection Assistance Information (NSSAI)) and an associated tenant ID (which may form part of the MDD vector). At S1502 the base station 5 responds with an appropriate message (e.g. a Slice Update Response message).

[0147] Preferably, the base station 5 can use the received information to make appropriate decisions (e.g. selecting appropriate core network functionality for the UE's slice and / or enabling appropriate on-demand system information).

[0148] More Information Figures 16 to 20 are provided as background to aid in understanding how slicing may be implemented in a telecommunications network. In this regard, Figure 16 illustrates how different slices / slice types may be supported by different base stations. Figure 17 illustrates a possible configuration of several possible Slice Specific Core Network Functions and interfaces / reference points between them (i.e., represented by the "NG*" label in the figure). Figure 18 is a simplified schematic diagram illustrating how "m" slice types for "n" tenants and Z UEs may be supported via a Radio Access Network (RAN) and a Core Network (CN). Figure 19 is a simplified schematic diagram illustrating how slices for different UEs communicating via a given RAN may have different sets of slice specific core network functions and / or Common Control Plane Network Functions. Figure 20 is a simplified sequence diagram illustrating a typical attachment procedure that may take place in a network with a Slice Selection Function (SSF).

[0149] Modifications and substitutions A number of detailed exemplary embodiments have been described above. As will be appreciated by those skilled in the art, many modifications and alternatives may be made to the above-described embodiments while still benefiting from the invention embodied therein. For purposes of illustration, only a few of these alternatives and modifications are described herein.

[0150] In the above exemplary embodiments, several software modules for implementing user equipment, base station and / or core network functions, etc., have been described. As will be appreciated by those skilled in the art, such software modules may be provided in compiled or uncompiled form, and may be provided to corresponding hardware as a signal on a computer network or on a recording medium. Furthermore, the functions performed by part or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates updating the corresponding hardware to update its functionality. Similarly, although the above embodiments used a transceiver circuit, at least some of the functions of the transceiver circuit may be performed by software.

[0151] For example, although the functions of the core network are described as logical functions, it will be appreciated that they may be implemented using one or more computer processing devices having one or more hardware computer processors programmed with appropriate software instructions to provide the required logical functions (e.g. one or more computer processors forming part of the controller described with reference to Figures 5 and 6). It will further be appreciated that all or part of these functions may be implemented in hardware as dedicated circuitry, for example using one or more dedicated integrated circuits such as Application Specific Integrated Circuits (ASICs).

[0152] Similarly, the functionality of the user equipment and base station (gNB) is typically implemented using one or more computer processing devices having one or more hardware computer processors programmed with appropriate software instructions to provide the required functionality (e.g., one or more computer processors forming part of the controller described with reference to Figures 2, 3 and 4). It will further be appreciated that all or part of this functionality may be implemented in hardware as dedicated circuitry, for example using one or more dedicated integrated circuits such as application specific integrated circuits (ASICs).

[0153] It will be appreciated that the controllers referred to in the descriptions of the UE, gNB, and core network nodes / functions (i.e., with reference to Figures 2 to 7) may include any suitable controller, such as, for example, an analog or digital controller. Each controller may comprise any suitable form of processing circuitry, including, for example, but not limited to, one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuitry, internal memory / cache (program and / or data), processing registers, communication buses (e.g., control, data and / or address buses), Direct Memory Access (DMA) functionality, hardware or software implemented counters, pointers and / or timers, and / or the like.

[0154] While Figure 1 shows what would be an entire network slice for purposes of illustration, it is understood that the core can have its own slice, and so can the radio access network (RAN). Similarly, the control plane (CP) and user plane (UP) can have entirely different slices. Depending on standardization and cellular operator policies, the mapping from RAN slices to core slices may differ.

[0155] It is also understood that a tenant may be a wholesale customer, such as a Mobile Virtual Network Operator (MVNO), Mobile Other Licensed Operator (MOLO), where the MVNO / MOLO is a wireless communication service provider that does not have its own wireless network infrastructure through which it provides services to its customers. However, a tenant does not necessarily have to be an MVNO / MOLO. A tenant may also be an enterprise customer, such as a multinational corporation, a fleet of vehicles, emergency services and / or security services (e.g., a security company). Each tenant may have different requirements regarding which slice type to use, based on service level agreements. The tenant concept allows a mobile network operator to differentiate between different customer requirements and provide customized services using one or many slices.

[0156] Although different devices are described as having transceiver circuitry for the purpose of communicating (i.e., sending / receiving) data to / from other devices / apparatuses, it will be understood that the transceiver functionality may also be implemented in software running on a corresponding hardware controller to communicate messages and / or information between different respective functions co-located on the same physical device.

[0157] It will be appreciated that alternatively or additionally, the TUPF or at least one additional TUPF may be co-located with the access network (eg, to enable stationary UE scenarios).

[0158] It is understood that the term "Participating Operator" may be used in place of the term "Tenant."

[0159] In the above exemplary embodiment, a telecommunications system operating according to the 3GPP standard has been described. However, as will be appreciated by those skilled in the art, the techniques described herein may be employed in communication systems operating according to other standards, in particular any Orthogonal Frequency-Division Multiplexing (OFDM) based system, such as Worldwide Interoperability for Microwave Access (WiMAX).

[0160] In summary, it has been described that a communication device comprises a controller and a transceiver, the controller being configured to generate a message including slice support information indicating at least one slice support capability of the communication device, and to control the transceiver to transmit the message to a node of a core network.

[0161] The slice support information includes hardware capability information from which the slice support information can be derived. The slice support information may include information identifying at least one network slice template (NST) associated with at least one slice supported by the communication device. The slice support information may include information identifying at least one area of ​​which the communication device is a part and in which the communication device may be paged (e.g., at least one of a tracking area code and a radio access network (RAN) paging area). The controller may be operative to terminate the message as part of an interface establishment procedure (e.g., an S1 or NG-C setup procedure) over a core network to base station interface. The message may be an interface setup request message (e.g., an S1 or NG-C setup message) for a core network to base station interface. The controller may be configured to transmit the message for the communication device over a core network to base station interface as part of a configuration update procedure (e.g., an eNB, gNB or NR-BS configuration procedure). The message may be a configuration update message (e.g., an eNB, gNB, or NR-BS configuration update message).

[0162] It was also described that the core node comprises a controller and a transceiver, the controller being configured to control the transceiver to receive a message from a communication device including slice support information indicating at least one slice support capability of the communication device, and to configure information stored in the core node based on the slice support information.

[0163] The controller may be configured to configure at least one allowed cell list (ACL) based on the slice support information when configuring the information stored in the core node. The controller may be configured to control the transceiver to transmit (e.g., in an initial context setup request message) at least one ACL to the communication device or another communication device. The controller may be configured to configure a paging area based on the slice support information when configuring the information stored in the core node. The controller may be configured to control the transceiver to transmit a paging message (e.g., a paging request) to the communication device or another communication device, the paging message including information for identifying cells of the paging area configured in the communication device. The information for identifying cells of the configured paging area may be provided in assistance data for a paging information element of the paging message. The controller may be configured to configure a handover restriction list based on the slice support information to identify cells for which handover is restricted at cell level granularity when configuring the information stored in the core node. The controller may be configured to control a transceiver to transmit a handover restriction list to the communication device or another communication device (e.g., in at least one of an initial context setup request message and a core network to base station interface based handover request message). The core node may be configured to perform at least one of a mobility management function (e.g., a mobility management entity), an access management function (AMF), and a session management function (SMF).

[0164] It has also been described that the communication device comprises a controller and a transceiver, wherein the controller is configured to control the transceiver to receive, as part of a handover procedure for at least one communication device, a message from another communication device including slice support information related to at least one slice supported by the at least one communication device, and to configure the communication device to support communication of the at least one communication device based on the slice support information by at least one of selecting an appropriate slice-specific core network function based on the slice support information and switching on slice-specific on-demand system information based on the slice support information.

[0165] The slice support information may include slice usage information identifying at least one slice (and / or at least one network slice template of a slice) used by the at least one communication device. The slice support information may include information identifying at least one tenant and / or corresponding slice type associated with the at least one communication device (e.g., at least one multi-dimensional descriptor (MDD) vector). The slice support information may include information identifying at least one core network function (e.g., an access management function (AMF), a session management function (SMF), and / or a user plane function) associated with the at least one slice used by the at least one communication device. The slice support information may include network slice selection assistance information (NSSAI) associated with the at least one slice used by the at least one communication device.

[0166] It has also been described that the communication device comprises a controller and a transceiver, the controller being configured to control the transceiver to receive a message from another communication device, the message including slice support information relating to at least one slice supported by at least one communication device, as part of a procedure for setting up dual connectivity for at least one communication device, and to configure the communication device for dual connectivity based on the slice support information.

[0167] The message may include a secondary base station addition request (e.g., SeNB / SgNB addition request) message.

[0168] It has been described that the communication apparatus comprises a controller and a transceiver, and the controller is configured to control the transceiver to receive a connection re-establishment message from at least one communication device as part of a connection re-establishment procedure, the connection re-establishment message including slice support information related to at least one slice supported by the at least one communication, and to configure the communication apparatus to support re-establishment of a connection with the communication device based on the slice support information.

[0169] The connection re-establishment message may include at least one of a connection re-establishment request message and a connection re-establishment completion message.

[0170] It was also described that the communication device comprises a controller and a transceiver, the controller being configured to control the transceiver to send a connection re-establishment message to a communication apparatus as part of a connection re-establishment procedure, the connection re-establishment message including slice support information relating to at least one slice supported by the communication device.

[0171] It has also been described that the communication apparatus comprises a controller and a transceiver, the controller being configured to control the transceiver to receive from a core node at least one message for at least one communication device, the message including slice support information relating to at least one slice used by the at least one communication device, and to configure the communication apparatus to support communication of the at least one communication device based on the slice support information.

[0172] The at least one message including the slice support information may be received as part of at least one of an initial context setup procedure, a user equipment (UE) context modification procedure, a core network-to-base station interface based handover procedure, a base station-to-base station interface based handover procedure, a paging procedure, or a slice update procedure. The at least one message may include at least one of an initial context setup request message, a user equipment (UE) context modification request message, a core network-to-base station interface based handover request message, a path switch request acknowledgement message, a paging message, or a slice update request message. The controller may be configured to configure the communication apparatus to support communication of the at least one communication device based on the slice support information by at least one of selecting an appropriate slice-specific core network function based on the slice support information and enabling slice-specific on-demand system information based on the slice support information.

[0173] In the above example, a mobile phone based telecommunication system has been described. As will be appreciated by those skilled in the art, the techniques described herein can be applied in any communication system. In the general case, base stations and mobile phones can be considered as communication nodes or devices that communicate with each other. Other communication nodes or devices may include access points and user devices, such as personal digital assistants, laptop computers, web browsers, etc.

[0174] Various other modifications will be apparent to those skilled in the art and will not be described in further detail herein.

[0175] This application claims priority to UK Patent Application No. 1700270.0 filed January 6, 2017, and UK Patent Application No. 1700505.9 filed January 11, 2017, the disclosures of which are incorporated herein by reference in their entireties.

Claims

1. A target base station, means for receiving, as part of a handover procedure between the target base station and a source base station, from the source base station, a message including at least a portion of Network Slice Selection Assistance Information (NSSAI) for a slice and a corresponding Quality of Service (QoS) flow identifier; Target base station.

2. means for performing admission control based on receipt of the message; The target base station of claim 1 .

3. The message includes a handover request message. A target base station according to claim 1 or 2.

4. means for receiving, as part of a procedure for supporting dual connectivity between the target base station and the source base station, from the source base station, a further message including at least a portion of information of an NSSAI for a slice. A target base station according to any one of claims 1 to 3.

5. the further message comprises a request message to add the target base station as a secondary node. The target base station of claim 4.

6. At least a portion of the information in the NSSAI includes information identifying a slice type. A target base station according to any one of claims 1 to 5.

7. the information in at least a portion of the NSSAI includes information for distinguishing at least one slice from another; A target base station according to any preceding claim.

8. Based on the message, Selecting an appropriate slice-specific core network function; and Enabling slice-specific on-demand system information; means for performing at least one of the following: A target base station according to any preceding claim.

9. A method in a target base station, comprising: receiving, as part of a handover procedure between the target base station and a source base station, from the source base station, a message including at least a portion of Network Slice Selection Assistance Information (NSSAI) for a slice and a corresponding Quality of Service (QoS) flow identifier; method.

10. A source base station, means for transmitting, as part of a handover procedure between a target base station and the source base station, to the source base station, a message including at least a portion of Network Slice Selection Assistance Information (NSSAI) for a slice and a corresponding Quality of Service (QoS) flow identifier; Source base station.

11. A method in a source base station, comprising: transmitting, as part of a handover procedure between a target base station and the source base station, to the source base station, a message including at least a portion of Network Slice Selection Assistance Information (NSSAI) for the slice and a corresponding Quality of Service (QoS) flow identifier; method.

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