WO2020104925A1

WO2020104925A1 - First core network to second core network interworking while reducing usage of default second core network resources

Info

Publication number: WO2020104925A1
Application number: PCT/IB2019/059901
Authority: WO
Inventors: Peter Hedman; Peter Ramle; Qian Chen
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2018-11-19
Filing date: 2019-11-18
Publication date: 2020-05-28

Abstract

A method, system and nodes are disclosed. In some embodiments, a mobility control node of a first core network is configured to select a second node in a second core network for a handover of a user equipment, UE, to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE to the second core network; and provide to the selected second node in the second core network, at the handover of the UE, the network slicing related information.

Description

FIRST CORE NETWORK TO SECOND CORE NETWORK

INTERWORKING WHILE REDUCING USAGE OF DEFAULT SECOND CORE NETWORK RESOURCES

TECHNICAL FIELD

The present disclosure relates to wireless communications, and in particular, to at least in part reducing and/or avoiding the use of at least one network functions resource at least in part by providing network slicing related information.

BACKGROUND

The System Architecture WG (SA2) study on Network Slicing, documented in Third Generation Partnership Projection (3GPP) Technical Report (TR) 23.740 includes a study on enabling interworking for network slicing between evolved packet core (EPC) and 5th Generation core (5GC) networks. Network slicing is generally considered a form of virtualization that allows multiple virtual networks to run on top of a shared physical network infrastructure.

The 3GPP Release 15 (Rel-15) solution for interworking (IW) may include the following limitations (based on key issue descriptions):

1. Selection of access management functions (AMFs) not part of the

Network Slices currently used by the packet data network (PDN) Connections may lead to, e.g., a need to allocate more resources to default AMF Set(s);

2. Selection of visitor- session management functions (V-SMFs) not part of the Network Slices currently used by the protocol data unit (PDN) Connections may lead to, e.g., a need to allocate more resources to default V-SMFs;

3. Only one PDU session may have the Evolved Packet System (EPS) bearer ID (EBI), i.e., enabled for IW with EPS, for the same data network name (DNN).

The 3 GPP TR may include the following assumptions for interworking for slicing between evolved packet core (EPC) and 5GC:

It may be assumed that the interworking for slicing between EPC and 5GC uses a 3 GPP Rel-15 solution as the basis.

The interworking for slicing between EPC and 5GC may not impact 3 GPP Rel-15 5G UEs behavior. The system may support slicing interworking between EPC and 5GC for a roaming case when the packet data network gateway-control (PGW-C)+SMF is according to 3 GPP Rel-15.

SUMMARY

According to an aspect of the present disclosure, a method implemented in a mobility control node of a first core network is provided. The method includes selecting a second node in a second core network for a handover of a user equipment, UE, to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE to the second core network. The method includes providing to the selected second node in the second core network, at the handover of the UE, the network slicing related information.

In some embodiments of this aspect, selecting the second node for the handover of the UE further includes at least one of: selecting the second node using the at least a portion of the network slicing related information as an input into a domain name system, DNS, lookup procedure; and selecting the second node using the at least a portion of the network slicing related information to query a network repository function, NRF, node.

In some embodiments, the mobility control node of the first core network is a mobility management entity, MME, node and the first core network is an evolved packet core, EPC, network. In some embodiments, the second node is an access management function, AMF, node and the second core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network. In some embodiments, the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE for the Packet Data session. In some embodiments, the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE. In some embodiments, the method further includes during one of a Packet Data Network, PDN, Connectivity procedure and a Bearer Modification procedure for the UE, receiving, from a common session control node, the network slicing related information; and wherein the providing the network slicing related information to the second node in the second core network further comprises providing the network slicing related information that is received from the common session control node.

In some embodiments, providing the network slicing related information to the second node further includes including the network slicing related information in a forward relocation request to the second node in the second core network. In some embodiments, providing the network slicing related information to the second node further includes including the network slicing related information in a context response message to the second node in the second core network.

According to another aspect of the present disclosure, a method implemented in a mobility control node of a first core network is provided. The method includes receiving, at a handover of a user equipment, UE, to the first core network, network slicing related information from a mobility control node of a second core network, the network slicing related information associated to a Packet Data session established by the UE over the second core network. The method includes selecting a second node of the first core network for the handover of the UE to the first core network using at least a portion of the network slicing related information, the selecting the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE from the second core network to the first core network.

In some embodiments, the mobility control node of the first core network is an access management function, AMF, node and the first core network is a 3^rd

Generation Partnership Project 5th Generation core, 5GC, network. In some embodiments, the selected second node of the first core network is a visitor- session management function, V-SMF, node. In some embodiments, the mobility control node of the second core network is a mobility management entity, MME, node and the second core network is an evolved packet core, EPC, network. In some embodiments, the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE for the Packet Data session. In some embodiments, the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE.

According to yet another aspect of the present disclosure, a mobility control node of a first core network is provided. The mobility control node comprises processing circuitry. The processing circuitry is configured to cause the mobility control node to select a second node in a second core network for a handover of a user equipment, UE, to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE to the second core network. The processing circuitry is configured to cause the mobility control node to provide to the selected second node in the second core network, at the handover of the UE, the network slicing related information.

In some embodiments, the processing circuitry is further configured to cause the mobility control node to select the second node for the handover of the UE by being configured to cause the mobility control node to at least one of select the second node using the at least a portion of the network slicing related information as an input into a domain name system, DNS, lookup procedure; and select the second node using the at least a portion of the network slicing related information to query a network repository function, NRF, node.

In some embodiments, the mobility control node of the first core network is a mobility management entity, MME, node and the first core network is an evolved packet core, EPC, network. In some embodiments, the second node is an access management function, AMF, node and the second core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network. In some embodiments, the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE for the Packet Data session. In some embodiments, the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE. In some embodiments, the processing circuitry is further configured to cause the mobility control node to during one of a Packet Data Network, PDN, Connectivity procedure and a Bearer Modification procedure for the UE, receive, from a common session control node, the network slicing related information; and provide the network slicing related information to the second node in the second core network by being configured to cause the mobility control node to provide the network slicing related information that is received from the common session control node. In some embodiments, the processing circuitry is further configured to cause the mobility control node to provide the network slicing related information to the second node by being configured to cause the mobility control node to include the network slicing related information in a forward relocation request to the second node in the second core network. In some embodiments, the processing circuitry is further configured to cause the mobility control node to provide the network slicing related information to the second node by being configured to cause the mobility control node to include the network slicing related information in a context response message to the second node in the second core network.

According to another aspect of the present disclosure, a mobility control node of a first core network is provided. The mobility control node comprises processing circuitry. The processing circuitry is configured to cause the mobility control node to receive, at a handover of a user equipment, UE, to the first core network, network slicing related information from a mobility control node of a second core network, the network slicing related information associated to a Packet Data session established by the UE over the second core network. The processing circuitry is configured to cause the mobility control node to select a second node of the first core network for the handover of the UE to the first core network using at least a portion of the network slicing related information, the selection of the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE from the second core network to the first core network.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic diagram of an exemplary network architecture illustrating a communication system connected according to the principles in the present disclosure;

FIG. 2 is a block diagram of nodes according to some embodiments of the present disclosure;

FIG. 3 is a flowchart of an exemplary process in a node according to some embodiments of the present disclosure;

FIG. 4 is a flowchart of an exemplary process in another node according to some embodiments of the present disclosure;

FIG. 5 is a signaling diagram of a wireless device requested PDU session establishment for home-routed roaming according to some embodiments of the present disclosure;

FIG. 6 is a signaling diagram for EPS to 5GS handover using N26 interface according to some embodiments of the present disclosure; and

FIG. 7 is a signaling diagram for EPS to 5GS mobility for signal-registration mode with N26 interface according to some embodiments of the present disclosure. DETAILED DESCRIPTION

None of the solutions in the 3GPP TR 23.740 avoid the need for use of 5GS default network function (NF) resources while complying with one or more assumptions, such as the assumptions described above. While some solutions may comply with the assumptions and have limited impacts, such solutions may add some delay to the handover (HO) procedure and may avoid default V-SMF resources but may not avoid the use of default AMF resources. To completely avoid the use for 5GS of default network function (NF) (e.g., AMF and V-SMF) resources, the EPC and possibly the UE may be impacted and/or configured. Impacting the EPC and the UE may be regarded as an optional additional enhancement in the systems. In one or more embodiments, default resource(s) such as default 5GS resources may generally refer to non-dynamic ally assigned/selected resources that may be preconfigured for use at a node (e.g., AMF and/or MME) for one or more predefined uses. In one or more embodiments, default resource(s) such as default 5GS resources may generally refer to resource(s) used if information for use of other resource(s) is insufficient or unavailable. For example, in one or more embodiments, the use of at least one default resource is avoided by providing network slicing information for dynamically selecting resource(s), where the selected resource(s) may differ at least in part from the default resources. This may lead to a reduction in the use of default resource(s) as selected resource(s) are used.

The instant disclosure solves at least a portion of at least one problem associated with default NF resource usage. Some embodiments advantageously provide methods, systems, nodes for at least in part reducing the use of at least one network functions resource at least in part by providing network slicing related information.

In one or more embodiments, network slice information in the UE context for MME is provided to help the AMF avoid slice information retrieval and for reducing default V-SMF resource consuming. In one or more embodiments, an MME may select an AMF based on slice information, which may help avoid default AMF resource consuming. One or more of the embodiments described herein help reduce the handover (HO) latency. In one or more embodiments, at least one of the following may be implemented: 1) impact the EPC avoiding AMF to retrieve single-network slice selection assistance information (S-NSSAI) during HO and for selection of AMF and V-SMF at HO (e.g., connected mode mobility) and 2) ensure that appropriate information is available while accessing 5GS for reducing default AMF resources and/or AMF receives appropriate information for V-SMF selection for reducing default V-SMF resources (e.g., idle mode mobility).

For 1) the following could be an option:

At the time and (via the same procedure, e.g., PDN Connectivity Request and Modify Bearer) when the combined PGW-C+SMF (i.e., common session control node) in the protocol configuration option (PCO or ePCO) provides the UE with slicing information, the PGW-C+SMF may also provide mobility management entity (MME) with EBI address and S- NSSAI (possibly also PDU Session ID) for the PDN Connection.

An MME being aware of S-NSSAIs in use, by the UE, could enhance the possibility of directly selecting a correct AMF in the first place at handover, but that may require enhancements of AMF selection, e.g., domain name system (DNS) procedures or MME support network repository functions (NRF) query.

At handover to 5GS, the MME may, in Forward Relocation Request per PDN Connection (PDU Session), include information on the EBI address and S-NSSAI (possibly also PDU Session ID) towards an Initial AMF where the Initial AMF may not need to fetch or retrieve this (as is done in some existing system) from the PGW-C+SMFs -> Less latency. The rest of the handover procedure may then be as described herein.

For 2) the following could be an option for reducing default V-SMF (vSMF) resources (e.g., reducing the use and/or scheduling of V-SMF resources):

At Idle mode mobility, the MME may, in a Context Response per PDN Connection (PDU Session), include information on the EBI address and S- NSSAI (possibly also PDU Session ID) towards a requesting AMF. For the HR case, a V-SMF may then be selected (instead of a default SMF) where the selection may be based on one or more rules, criterion, etc. Therefore, some embodiments of the instant disclosure advantageously provide for the appropriate Network Slices and corresponding 5G Network Functions and resources to be selected without impacting handover (HO) performance.

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to at least in part reducing the use of at least one network functions resource at least in part by providing network slicing related information. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as“first” and“second,”“top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms“a”,“an” and“the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,”“comprising,”“includes” and/or“including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In embodiments described herein, the joining term,“in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication. In some embodiments described herein, the term“coupled,”“connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

The term“network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc.

The network node may also comprise test equipment. The term“radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

In some embodiments, the term first node and/or second node correspond to one or more core network nodes (e.g., mobile management entity (MME), AMF, etc.). In one or more embodiments, first node and/or second node may be network nodes or part of network nodes.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The UE herein can be any type of wireless device capable of communicating with a network node or another UE over radio signals, such as wireless device (WD). The UE may also be a radio communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), low-cost and/or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer

Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, etc. Also, in some embodiments the generic term“radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

A node may include physical components, such as processors, allocated processing elements, or other computing hardware, computer memory,

communication interfaces, and other supporting computing hardware. The node may use dedicated physical components, or the node may be allocated use of the physical components of another device, such as a computing device or resources of a datacenter, in which case the node is said to be virtualized. A node may be configured to execute instructions corresponding to a network function or other software stored in a memory to implement the techniques disclosed herein. A node may be associated with multiple physical components that may be located either in one location, or may be distributed across multiple locations. Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA),

Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Further, note that although terminology for one particular core network (such as“PDU Session Establishment” and“PDU Session Modification” for 5G) may be used in some embodiments of the present disclosure, it should be understood that such terms may also encompass other terminology that may be used for a corresponding (e.g., same/similar) procedure/messaging/service for another core network (e.g., terminology applicable for EPS, such as“PDN Connectivity Request” and“Modify Bearer”). The term“Packet Data session” is used herein and may be used to indicate session establishment or modification for a UE by e.g., a particular core network, such as, for example, a PDU Session Establishment or a PDU Session Modification for 5GS in some embodiments, or a PDN Connection or Modify Bearer for EPS in some embodiments.

An indication generally may explicitly and/or implicitly indicate the information it represents and/or indicates. Implicit indication may for example be based on position and/or resource used for transmission. Explicit indication may for example be based on a parametrization with one or more parameters, and/or one or more index or indices, and/or one or more bit patterns representing the information. It may in particular be considered that control signaling as described herein, based on the utilized resource sequence, implicitly indicates the control signaling type.

Transmitting in downlink may pertain to transmission from the network or network node to the terminal. Transmitting in uplink may pertain to transmission from the terminal to the network or network node. Transmitting in sidelink may pertain to (direct) transmission from one terminal to another. Uplink, downlink and sidelink (e.g., sidelink transmission and reception) may be considered communication directions. In some variants, uplink and downlink may also be used to described wireless communication between network nodes, e.g. for wireless backhaul and/or relay communication and/or (wireless) network communication for example between base stations or similar network nodes, in particular communication terminating at such. It may be considered that backhaul and/or relay communication and/or network communication is implemented as a form of sidelink or uplink communication or similar thereto.

Note further, that functions described herein as being performed by a UE or a network node may be distributed over a plurality of UEs and/or network nodes. In other words, it is contemplated that the functions of the network node and UE described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Embodiments provide at least in part for helping reduce and/or avoid the use of at least one network functions resource at least in part by providing network slicing related information.

Referring now to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 1 a schematic diagram of a

communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first UE 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second UE 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of UEs 22a, 22b (collectively referred to as UEs 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding network node 16. Note that although only two UEs 22 and three network nodes 16 are shown for convenience, the communication system may include many more UEs 22 and network nodes 16.

Also, it is contemplated that a UE 22 can be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a UE 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, UE 22 can be in communication with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN. Core network 14 may include node 24 and node 25 that may be in communication with each other via one or more interfaces. In one or more embodiments, node 24 and/or 25 are entities in a core network such as MME, AMF, etc. Node 24 may include an information providing unit 26 which may be configured to select a second node in a second core network for a handover of a user equipment, UE, 22 to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE 22 over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE 22 to the second core network; and provide to the selected second node in the second core network, at the handover of the UE 22, the network slicing related information.

Node 25 may include a slicing information unit 27 which may be configured to receive, at a handover of a user equipment, UE, 22 to the first core network, network slicing related information from a mobility control node of a second core network, the network slicing related information associated to a Packet Data session established by the UE 22 over the second core network; and select a second node of the first core network for the handover of the UE 22 to the first core network using at least a portion of the network slicing related information, the selection of the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE 22 from the second core network to the first core network.

Example implementations, in accordance with an embodiment, of the node 24 and node 25 discussed in the preceding paragraphs will now be described with reference to FIG. 2.

The communication system 10 further includes a node 24 provided in a communication system 10 which includes hardware 28 enabling it to communicate with one or more of network node 16, node 25, other nodes 24 and other entities in communication system 10. The hardware 28 may include a communication interface 29 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10, as well as a radio interface 30 for setting up and maintaining at least a wireless connection with one or more entities. The radio interface 30 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface 29 may be configured to facilitate communication to one or more nodes 24, network node 16 and node 25.

In the embodiment shown, the hardware 28 of the node 24 further includes processing circuitry 32. The processing circuitry 32 may include a processor 34 and a memory 36. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 32 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 34 may be configured to access (e.g., write to and/or read from) the memory 36, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only

Memory).

Thus, the node 24 further has software 38 stored internally in, for example, memory 36, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the node 24 via an external connection. The software 38 may be executable by the processing circuitry 32. The processing circuitry 32 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by node 24. Processor 34 corresponds to one or more processors 34 for performing node 24 functions described herein. The memory 36 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 38 may include instructions that, when executed by the processor 34 and/or processing circuitry 32, causes the processor 34 and/or processing circuitry 32 to perform the processes described herein with respect to node 24. For example, processing circuitry 32 of the network node 16 may include information providing unit 26 configured to providing information as described herein. In one or more embodiments, node 24 is a mobility control node (e.g., an MME node or an access management function, AMF, node) or other node.

The communication system 10 further includes node 25, already referred to. The node 25 may have hardware 39 that may include a radio interface 40 configured to set up and maintain one or more connections such as with a network node 16 serving a coverage area 18 in which the UE 22 is currently located, node 24 and/or other entities in communication system 10. The radio interface 40 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware 39 of the node 25 further includes processing circuitry 42. The processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) memory 46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the node 25 may further comprise software 47, which is stored in, for example, memory 46 at the node 25, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the node 25. The software 47 may be executable by the processing circuitry 42.

The processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by node 25. The processor 44 corresponds to one or more processors 44 for performing node 25 functions described herein. The node 25 includes memory 46 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 47 may include instructions that, when executed by the processor 44 and/or processing circuitry 42, causes the processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to node 25. For example, the processing circuitry 42 of the node 25 may include a slicing information unit 27 configured to perform one or more functions as described herein. In one or more embodiments, node 25 is a mobility control node (e.g., an MME node or an access management function, AMF, node) or other node.

In some embodiments, the inner workings of the node 24 and node 25 may be as shown in FIG. 2 and independently, the surrounding network topology may be that of FIG. 1. In one or more embodiments, node 24 and/or node 25 may respectively correspond to one or more other entities in the core network. In one or more embodiments, default resource(s) such as default 5GS resources may generally refer to non-dynamically assigned/selected resources that may be preconfigured for use at a node (i.e., node 24 and/or node 25) for one or more predefined uses. In one or more embodiment, default resource(s) such as default 5GS resources may generally refer to resource(s) used if information for use of other resource(s) is insufficient or unavailable.

FIG. 3 is a flowchart of an exemplary process in a node 24 (e.g., mobility control node of a first core network, such as MME node of EPC) for helping reduce and/or avoid the use of default resources as compared with other solutions and as described herein. One or more Blocks and/or functions performed by the node 24 may be performed by one or more elements of the node 24 such as by information providing unit 26 in processing circuitry 32, processor 34, radio interface 30, the communication interface 29, etc. In one embodiment, the method includes selecting (Block S100), such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, a second node in a second core network for a handover of a user equipment, UE, 22 to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE 22 over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE 22 to the second core network. The method includes providing (Block S102), such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, to the selected second node in the second core network, at the handover of the UE 22, the network slicing related information. In some embodiments, selecting the second node for the handover of the UE 22 further includes selecting, such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, the second node using the at least a portion of the network slicing related information as an input into a domain name system, DNS, lookup procedure. In some

embodiments, selecting the second node for the handover of the UE 22 further includes selecting, such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, the second node using the at least a portion of the network slicing related information to query a network repository function, NRF, node.

In some embodiments, the mobility control node of the first core network is a mobility management entity, MME, node and the first core network is an evolved packet core, EPC, network. In some embodiments, the second node is an access management function, AMF, node and the second core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network. In some embodiments, the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE 22 for the Packet Data session. In some embodiments, the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE 22.

In some embodiments, the method further includes during one of a Packet Data Network, PDN, Connectivity procedure and a Bearer Modification procedure for the UE 22, receiving (e.g., via radio interface 30 and/or the communication interface 29), from a common session control node (e.g., PGW-C+SMF), the network slicing related information. In some embodiments, the providing the network slicing related information to the second node in the second core network further includes providing the network slicing related information that is received from the common session control node (e.g., PGW-C+SMF).

In some embodiments, providing the network slicing related information to the second node further includes including, such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, the network slicing related information in a forward relocation request to the second node in the second core network. In some embodiments, providing the network slicing related information to the second node further includes including, such as by information providing unit 26, processing circuitry 32, processor 34, radio interface 30 and/or the communication interface 29, the network slicing related information in a context response message to the second node in the second core network.

In another embodiment, node 24 such as via processing circuitry 32 and/or processor 34 is configured to avoid use of at least one default resource at least in part by providing network slicing related information to a second node. In one or more embodiments, a reduction in the use of default resources may come from avoiding the use of at least one of these default resources.

In one or more embodiments, the second node (e.g., node 25) is one selected from a group consisting of a mobility control node of one or more different core networks (e.g., an access management function, AMF, node for 5GC and/or an MME node for EPC). In one or more embodiments, the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single network slice selection assistance information, S-NSSAI. In one or more

embodiments, the at least one default resource includes at least one network functions, NF, resource.

FIG. 4 is a flowchart of an exemplary process in a node 25 (e.g., mobility control node of another core network, such as AMF node of 5GC) according to some embodiments of the present disclosure. In one or more embodiments, node 25 may be a different type of core node or core network node than node 24 where these two different nodes 24/25 perform different functions as described herein. One or more Blocks and/or functions performed by the node 25 may be performed by one or more elements of the node 25 such as by slicing information unit 27 in processing circuitry 42, processor 44, radio interface 40, etc. In one embodiment, the method includes receiving (Block S104), such as by slicing information unit 27, processing circuitry 42, processor 44 and/or radio interface 40, at a handover of a user equipment, UE, 22 to the first core network, network slicing related information from a mobility control node of a second core network, the network slicing related information associated to a Packet Data session established by the UE 22 over the second core network. The method includes selecting (Block S106), such as by slicing information unit 27, processing circuitry 42, processor 44 and/or radio interface 40, a second node of the first core network for the handover of the UE 22 to the first core network using at least a portion of the network slicing related information, the selecting the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE 22 from the second core network to the first core network.

Generation Partnership Project 5th Generation core, 5GC, network. In some embodiments, the selected second node of the first core network is a visitor- session management function, V-SMF, node. In some embodiments, the mobility control node of the second core network is a mobility management entity, MME, node and the second core network is an evolved packet core, EPC, network. In some embodiments, the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE for the Packet Data session. In some embodiments, the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE 22.

In another embodiment, the node 25 such as via processing circuitry 42 and/or processor 44 is configured to receive network slicing related information from the second node (e.g., node 24), the network slicing information configured to avoid use of at least one default resource. In one embodiment, node 25 such as via processing circuitry 42 and/or processor 44 is configured to optionally perform at least one action based on the received network slicing related information.

In one or more embodiments, the first node (e.g., node 25) is one selected from a group consisting of an access management function, AMF, and visitor- session management function, V-SMF. In one or more embodiments, the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI. In one or more embodiments, the at least one default resource includes at least one network functions, NF, resource. Having generally described arrangements for at least helping avoid and/or reduce the use of at least one default resource at least in part by providing network slicing related information to node 25, details for these arrangements, functions and processes are further provided below where one or more of the below described functions/processes may be performed by the node 24, node 25 and/or other entity in communication system 10.

In one or more embodiments, network slicing relates to configuring one or more logical networks operating on a common physical network infrastructure where each logical network can be configured to provide one or more network performance characteristics. In one or more embodiments, each logical network is a“network slice.”

The signaling chart in FIG. 5 illustrates one or more steps according to the teachings described herein.

Home-routed Roaming (HR)

This procedure may be used in case of home-routed roaming scenarios. As described herein,“clause” may refer to a clause in, for example, 3GPP TS 23.501 and/or 23.502, unless otherwise specified.

Step 1A. This step may correspond to step 1 in clause 4.3.2.2.I.

Step 2A. This step may be as described in step 2 of clause 4.3.2.2.1 with the addition that the AMF (e.g., node 25) also selects an SMF in home public land mobile network (HPLMN) using the S-NSSAI with the value defined by the HPLMN, as described in clause 4.3.2.2.3. The AMF (e.g., node 25) may also receive alternative H-SMFs from the network repository function (NRF). The AMF (e.g., node 25) stores the association of the S-NSSAI, the data network name (DNN), the PDU Session ID, the SMF ID in the visited home public land mobile network (VPLMN) as well as Access Type of the PDU Session.

Step 3. In step 3 of clause 4.3.2.2.1, in the local breakout roaming case, if the V-SMF responds to the AMF (e.g., node 25) indicating that V-SMF is not able to process some part of the N1 SM information, the AMF (e.g., node 25) proceeds with the home routed case from this step and may select an SMF in the VPLMN different from the V-SMF selected earlier. -Step 3A(a). This step may be as described in step 3 of clause 4.3.2.2.1 with the addition that:

o the AMF (e.g., node 25) may also provide the identity of the H- SMF it has selected in Step 2A and both the S-NSSAI from the allowed NSSAI and the corresponding Subscribed S-NSSAI. The H-SMF is provided when the PDU Session is home-routed. The AMF (e.g., node 25) may also provide the identity of alternative H- SMFs, if it has received such identities in Step 2A. o The V-SMF does not use DNN Selection Mode received from the AMF (e.g., node 25) but relays this information to the H-SMF.

-The AMF (e.g., node 25) may include the H-PCF ID in this step and the V-SMF may pass it to the H-SMF in Step 6A. This may enable the H-SMF to select the same H-PCF in step 9A(a).

-Step 3A(b): This step may correspond to step 5 of clause 4.3.2.2.1.

Step 4A. The V-SMF selects a user plane function (UPF) in VPLMN as described in, for example, 3GPP TS 23.501, clause 6.3.3.

Step 5A. The V-SMF initiates an N4 Session Establishment procedure with the selected V-UPF:

-Step 5A(a). The V-SMF sends an N4 Session Establishment Request to the V-UPF. If core network (CN) Tunnel Info is allocated by the SMF, the CN Tunnel Info is provided to V-UPF in this step.

-Step 5A(b). The V-UPF acknowledges by sending an N4 Session Establishment Response. If CN Tunnel Info is allocated by the V-UPF, the CN Tunnel Info is provided to V-SMF in this step.

Step 6A. V-SMF to H-SMF: Nsmf_PDUSession_Create Request (subscriber permanent identifier (SUPI), general public subscription identifier (GPSI) (if available), DNN, S-NSSAI with the value defined by the HPLMN, PDU Session ID, V-SMF ID, V -CN -T unnel-Info, PDU Session Type, PCO, Number Of Packet Filters, User location information, Access Type, policy control function (PCF) ID,

SM PDU DN Request Container, DNN Selection Mode). Protocol Configuration Options (PCO) may contain information that H-SMF may need for establishing the PDU Session (e.g., SSC mode or SM PDU DN Request Container to be used to authenticate the UE 22 by the DN-AAA as defined in clause 4.3.2.3). The H-SMF may use DNN Selection Mode when deciding whether to accept or reject the UE 22 request. If the V-SMF does not receive any response from the H-SMF due to communication failure on the N16 interface, depending on operator policy the V-SMF may create the PDU Session to one of the alternative H-SMF(s) if additional H-SMF information is provided in step 3a, as specified in detail in 3GPP TS 29.502.

Step 7A-12A. These steps may correspond to steps 4-10 in clause 4.3.2.2.1 with one or more of the following differences from clause 4.3.2.2.1:

These steps may be executed in the Home PFMN;

The H-SMF stores an association of the PDU Session and V-SMF ID for this PDU Session for this UE 22;

The H-SMF does not provide the Inactivity Timer to the H-UPF as described in step 9A(a) in clause 4.3.2.2.I.

The H-SMF registers for the PDU Session ID with the unified data management (UDM) using Nudm_UECM_Registration (SUPI, DNN, S- NSSAI with the value defined by the HPFMN, PDU Session ID);

Step 4 of clause 4.3.2.2.1 may not be executed.

When the policy control function (PCF) is deployed, the SMF may further report the packet switched (PS) Data Off status to PCF if the PS Data Off event trigger is provisioned, the additional behavior of SMF and PCF for 3GPP PS Data Off is defined in, for example, 3GPP TS 23.503.

Step 13A. H-SMF to V-SMF: Nsmf_PDUSession_Create Response (QoS Rule(s), QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s), PCO including session level information that the V-SMF is not expected to understand, selected PDU Session Type and session and service continuity (SSC) mode, H-CN Tunnel Info, QFI(s), QoS profile(s), Session-AMBR, Reflective quality of service (QoS) Timer (if available), information needed by V- SMF in case of EPS interworking such as the PDN Connection Type, User Plane Policy Enforcement, EBI address and S-NSSAI (possibly also PDU Session ID) for the PDN Connection);

The information that the H-SMF may provide may be the same as defined for step 14 of FIG. 5. The H-CN Tunnel Info contains the tunnel information for uplink traffic towards H-UPF.

Multiple QoS Rules and QoS Flow level QoS parameters for the QoS Flow(s) associated with the QoS rule(s) may be included in the

Nsmf_PDUSession_Create Response.

Steps 14A-18A. These steps may correspond to steps 11-15 in clause 4.3.2.2.1 with one or more of the following differences from clause 4.3.2.2.1:

These steps are executed in the Visited PLMN;

The V-SMF stores an association of the PDU Session and H-SMF ID for this PDU Session for this UE 22.

The V-SMF forwards the EBI address and S-NSSAI (possibly also PDU Session ID) for the PDN Connection to the AMF (e.g., node 25) (this should also be part of clause 4.3.2.2.1), i.e., in one or more embodiments, at least a portion of the information may correspond to at least a portion of the network slicing related information.

Step 19A(a). The V-SMF initiates an N4 Session Modification procedure with the V-UPF. The V-SMF provides Packet detection, enforcement and reporting rules to be installed on the V-UPF for this PDU Session, including AN Tunnel Info, H-CN Tunnel Info and V-CN Tunnel Info.

Step 19A(b). The V-UPF provides a N4 Session Modification Response to the V-SMF. After step 19A(a) and/or 19A(b), the V-UPF provides any down-link packets to the UE 22 that may have been buffered for this PDU Session.

Step 20A. This step may be the same and/or may correspond to step 17 in clause 4.3.2.2.1 with the following differences from clause 4.3.2.2.1:

The SMF is a V-SMF.

Step 21 A. This step may be the same and/or may correspond to as step 18 in clause 4.3.2.2.1.

Step 22A. The H-SMF to the UE 22, via H-UPF and V-UPF in VPLMN: In case of PDU Session Type IPv6 or IPv4v6, the H-SMF generates an IPv6 Router Advertisement and sends it to the UE 22 via N4 and the H-UPF and V-UPF.

Step 23 A. If the V-SMF received in step 18A an indication that the

(R)AN 16 has rejected some QFI(s) the V-SMF notifies the H-SMF via a Nsmf_PDUSession_Update Request. The H-SMF is responsible of updating accordingly the QoS rules and QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s) in the UE 22.

Step 24A. This step may be the same as and/or may correspond to step 20 in clause 4.3.2.2.1 with the difference that this step is executed in the Home PLMN.

In one or more embodiments, the SMF in HPLMN can initiate Step 21 A after Step 13A.

Preparation phase

FIG. 6 illustrates an example of a preparation phase of a Single Registration- based Interworking from EPS to 5GS procedure. Steps in FIG. 6 are described below. In one or more embodiments, this procedure applies to one or more of the Non- Roaming (3GPP TS 23.501 Figure 4.3.1-1), Home -routed roaming (3GPP TS 23.501 Figure 4.3.2-1) and Local Breakout roaming Local Breakout (3GPP TS 23.501 Figure 4.3.2-2) cases.

For non-roaming scenario, one or more of V-SMF, v-UPF and v-PCF+v- PCRF are not present;

For home-routed roaming scenario, the one or more of PGW-C+SMF and UPF+PGW-U are in the HPLMN, and v-PCF+v-PCRF are not present;

For local breakout roaming scenario, V-SMF and/or v-UPF are not present, and PGW-C+SMF and/or UPF+PGW-U are in the VPLMN.

In local-breakout roaming case, the v-PCF+v-PCRF interacts with the PGW-C+SMF.

Steps 1B-2B are the same as and/or correspond to step 1 - 2 from clause 5.5.1.2.2 (Sl-based handover, normal) in 3GPP TS 23.401.

Step 3B is the same as and/or corresponds to step 3 from clause 5.5.1.2.2 (Sl- based handover, normal) in 3GPP TS 23.401 with the following modifications:

The MME node 24, which is aware of the S-NSSAIs in use by the UE 22, directly selects a correct AMF (e.g., node 25) in the first place at handover by using, for example, enhanced DNS procedures (enhanced to support S- NSSAIs as input to the DNS lookup) or MME support for a NRF query specified for 5GS. As an alternative, the MME node 24 may query the network slice selection function (NSSF) in the same way as the initial AMF node 25 would.

An additional optional parameter“Return preferred”. Return preferred is an optional indication provided by the MME node 24 to indicate a preferred return of the UE 22 to the last used EPS PLMN at a later access change to an EPS shared network. Based on the Return Preferred indication, the AMF (e.g., node 25) may store the last used EPS PLMN ID in the UE 22 Context.

The AMF (e.g., node 25) converts the received EPS Mobility Management (MM) Context into the 5GS MM Context. This may include converting the EPS security context into a mapped 5G security context as described in, for example, 3GPP TS 33.501. The MME node 14 UE 22 context may include the International Mobile Subscriber Identity (IMSI), Mobile Equipment (ME) Identity, UE security context, UE Network Capability, and EPS Bearer context(s), etc. The MME EPS Bearer context(s) may include for each EPS PDN connection the IP address and fully qualified domain names (FQDN) for the S5/S8 interface of the PGW-C+SMF and Access Point Name (APN), and for each EPS bearer the IP address and core network (CN) Tunnel Info at the UPF+PGW-U for uplink traffic.

The AMF (e.g., node 25) may query the (PLMN level) NRF in the serving PLMN by issuing the Nnrf_NFDiscovery_Request including the FQDN for the S5/S8 interface of the PGW-C+SMF, and the NRF may provide the IP address or FQDN of the N 11/N16 interface of the PGW-C+SMF.

The MME node 24, per PDN Connection (PDU Session) includes information on the EBI address and S-NSSAI (possibly also PDU Session ID) towards the Initial AMF (e.g., node 25) whereby the Initial AMF (e.g., node 25) does not need to fetch this information from the common session control nodes (e.g., PGW-C+SMFs). In one or more embodiments, at least a portion of the information may correspond to at least a portion of the network slicing related information. If the AMF node 25 cannot retrieve the address of the corresponding SMF for a PDN connection, the AMF node 25 may not move the PDN connection to 5GS.

NOTE 1: If the AMF node 25 holds a native 5G security context for the UE 22, the AMF node 25 may activate this native 5G security context by initiating a Non-access Stratum (NAS) security mode command (SMC) upon completing the handover procedure.

Step 4B. The AMF node 25 invokes and/or initiates the

Nsmf_PDUSession_CreateSMContext service operation (UE 22 EPS PDN

Connection, AMF ID, Direct Forwarding Flag) on the SMF identified by the PGW- C+SMF address and indicates HO preparation indication (to avoid switching the UP path). The AMF ID may be the UE 22’ s globally unique AMF identifier (GUAMI) which uniquely identifies the AMF node 25 serving the UE 22. This step is performed for each PDN Connection and the corresponding PGW-C+SMF address/ID in the UE 22 context the AMF node 25 received in Step 3B. The SMF determines the corresponding PDU Session based on EPS Bearer Context(s).

The AMF node 25 may include a Direct Forwarding Flag to inform the SMF of the applicability of indirect data forwarding.

For home-routed roaming scenario, the AMF node 25 may select a default V-SMF per PDU Session and may invoke and/or initiate the

Nsmf_PDUSession_CreateSMContext service operation (UE PDN Connection Contexts, AMF ID, SMF + PGW-C address, S-NSSAI). In another embodiment, the correct SMF may be directly selected based on the received S-NSSAI for the EBI address. The S-NSSAI may be the S- NSSAI configured in the AMF node 25 (i.e., received from the MME node 24 for this PDU session) for interworking, which is associated with the V- SMF. The V-SMF may put this S-NSSAI in the N2 SM Information container in Step 7B.

The V-SMF selects the PGW-C+SMF using the received H-SMF address as received from the AMF node 25, and initiates a

Nsmf_PDUSession_Create service operation with the PGW-C+SMF. Step 5B. If dynamic PCC is deployed, the SMF+ PGW-C (V-SMF via H-SMF for home -routed scenario) may initiate SMF initiated SM Policy Modification towards the PCF + PCRF.

Step 6B. In the case of non-roaming or local breakout (LBO) roaming, the PGW-C+SMF may send N4 Session modification to PGW-U+UPF to establish the CN tunnel for PDU Session. The PGW-U+UPF is ready to receive the uplink packets from NG-RAN. If the CN Tunnel info is allocated by the PGW-C+SMF, the PGW-U tunnel info for PDU session is provided to PGW-U+UPF. If the CN Tunnel info is allocated by PGW-U+UPF, the PGW-U+UPF sends the PGW-U tunnel info for PDU Session to the PGW-C+SMF. This step is performed at all PGW-C+SMFs allocated to the UE 22 for each PDU Session of the UE 22.

If the CN Tunnel info is not available in the PGW-U+UPF at Step 6B when the UE 22 moves to the target radio access technology (RAT), the PGW-U+UPF may not receive UL data until the Tunnel Info is provided to the PGW-U+UPF. This causes a short interruption to the UL data during the handover execution phase.

Step 7B. The PGW-C+SMF (V-SMF in the case of home-routed roaming scenario only) sends a Nsmf_PDUSession_CreateSMContext Response (PDU Session ID, S-NSSAI, N2 SM Information (PDU Session ID, S-NSSAI, QFI(s), QoS Profile(s), EPS Bearer Setup List, CN Tunnel-Info, cause code)) to the AMF node 25.

For home-routed roaming scenario, Step 8B may be executed first. The CN Tunnel-Info provided to the AMF node 25 in N2 SM Information is the V-CN

Tunnel-Info.

The SMF includes mapping between QoS flows and EPS bearers as part of N2 SM Information container. If the P-GW-C+SMF (H-SMF in the case of home-routed scenario) determines that seamless session continuity from EPS to 5GS is not supported for the PDU Session, then the P-GW-C+SMF does not provide SM information for the corresponding PDU Session but includes the appropriate cause code for rejecting the PDU Session transfer within the N2 SM Information. If the Direct Forwarding Flag indicates indirect forwarding and there is no indirect data forwarding connectivity between source and target, the SMF may further include a “Data forwarding not possible” indication in the N2 SM information container. In home routed roaming case, the S-NSSAI included in N2 SM Information container is the S-NSSAI received in Step 4B.

The AMF node 25 stores an association of the PDU Session ID, S-NSSAI and the SMF ID.

If the PDN Type of a PDN Connection in EPS is non-IP, and is locally associated in SMF to PDU Session Type Ethernet, the PDU Session Type in 5GS may be set to Ethernet. In case the PDN type of a PDN Connection in EPS is non-IP, and is locally associated in the UE 22 and SMF to PDU Session Type Unstructured, the PDU Session Type in 5GS may be set to Unstructured.

In the case of PDU Session Type Ethernet, which was using PDN type non-IP in EPS, the SMF creates and/or generates QoS rules and QoS Flow level QoS parameters for the QoS Flow(s) associated with the QoS rule(s) based on the policy and charging control (PCC) Rules received from PCF.

Step 8B. For home-routed roaming scenario only: The V-SMF selects a v-UPF and initiates an N4 Session Establishment procedure with the selected v-UPF. The V-SMF provides the v-UPF with packet detection, enforcement and reporting rules to be installed on the UPF for this PDU Session, including H-CN Tunnel Info. If CN Tunnel Info is allocated by the SMF, the V-CN Tunnel Info is provided to the v- UPF in this step. The v-UPF acknowledges procedure by sending an N4 Session Establishment Response message. If CN Tunnel Info is allocated by the UPF, the V- CN Tunnel info is provided to the V-SMF in this step.

Step 9B. The AMF node 25 sends a Handover (HO) Request (Source to Target Transparent Container, N2 SM Information (PDU Session ID, S-NSSAI, QFI(s), QoS Profile(s), EPS Bearer Setup List, V-CN Tunnel Info), Mobility

Restriction List) message to the NG-RAN 16. The AMF node 25 provides NG-RAN 16 with a PLMN list in the Mobility Restriction List containing at least the serving PLMN, taking into account the last used EPS PLMN ID and the Return preferred indication. The Mobility Restriction List contains information about PLMN IDs as specified by e.g., 3GPP TS 23.501.

NG-RAN 16 can use the source to target transparent container and N2 SM Information container to determine which QoS flows have been proposed for forwarding and deciding for which of the QoS flows it accepts or rejects for data forwarding.

Step 10B. The NG-RAN 16 sends a Handover Request Acknowledge (Target to Source Transparent Container, N2 SM response (PDU Session ID, list of accepted QFI(s) and AN Tunnel Info), T-RAN SM N3 forwarding info list (PDU Session ID, N3 Tunnel Info for data forwarding)) message to the AMF node 25. The NG-RAN 16 may include one assigned TEID/TNL address per PDU Session (for which there is at least one QoS flow for which it has accepted the forwarding) within the SM Info container. It also includes the list of QoS flows for which it has accepted the forwarding. If one EPS bearer in EPS is mapped to multiple QoS flows in 5GS, all such QoS flows are to be accepted to support indirect data forwarding during EPS to 5GS mobility. Otherwise, the NG-RAN 16 rejects the indirect data forwarding for the QoS flows which are mapped to the EPS bearer.

Step 11B. The AMF node 25sends an Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, N2 SM response (list of accepted QoS flow IDs (QFI(s)) and AN Tunnel Info), T-RAN SM N3 forwarding info list (PDU Session ID, N3 Tunnel Info for data forwarding)) message to the SMF for updating N3 tunnel information. In a home routed roaming case, T-RAN SM N3 forwarding info list (PDU Session ID, N3 Tunnel Info for data forwarding) is handled by the V-SMF and may not be sent to the PGW-C+SMF.

Step 12B. PGW-C+SMF (V-SMF in home-routed roaming scenario) performs preparations for N2 Handover by indicating N3 UP address and Tunnel ID of NG- RAN 16 to the UPF if N2 Handover is accepted by NG-RAN 16 and by indicating the mapping between the TEID where the UPF receives data forwarded by the source SGW and the QFI and N3 Tunnel Info for data forwarding where the UPF is selected to forward such data (e.g., an intermediate UPF). In home routed roaming case, the V- SMF sends a V-UPF for data forwarding the mapping between the TEID where the UPF receives data forwarded by the source SGW and the QFI and N3 Tunnel Info for data forwarding.

If N2 Handover is not accepted by NG-RAN 16, PGW-C+SMF deallocates N3 UP address and Tunnel ID of the selected UPF. The EPS Bearer Setup list may be a list of EPS bearer Identifiers successfully handover to 5GC, which is generated based on the list of accepted QFI(s).

Step 13B. PGW-C+SMF (V-SMF in home-routed roaming scenario) to AMF node 25: Nsmf_PDUSession_UpdateSMContext Response (PDU Session ID, EPS Bearer Setup Fist, CN tunnel information for data forwarding). In a home routed roaming case, the V-SMF provides the CN tunnel information for data forwarding. This message is sent for each received

Nsmf_PDUSession_UpdateSMContext_Request message.

Step 14B. The AMF node 25 sends the message Forward Relocation Response (Cause, Target to Source Transparent Container, Serving GW change indication, CN Tunnel Info for data forwarding, EPS Bearer Setup Fist, AMF Tunnel Endpoint Identifier for Control Plane, Addresses and TEIDs). The EPS Bearer Setup list is the combination of EPS Bearer Setup list from different PGW-C+SMF(s).

Step 15B may be the same as and/or may correspond to Step 8 from clause 5.5.1.2.2 (Sl-based handover, normal) in 3GPP TS 23.401.

EPS to 5GS Mobility Registration Procedure (Idle State) using N26 interface

FIG. 7 illustrates an example of the mobility procedure from EPS to 5GS when N26 is supported for the idle state. The steps of FIG. 7 are described below in which one or more steps are described with respect to one or more steps in one or more standards.

Step 1C. The Registration procedure is triggered, e.g., the UE 22 moves into NG-RAN coverage. Steps 2C to 9C except Steps 5C, 6C and 8C may follow the Registration procedure in clause 4.2.2.2.2 except as modified and/or enhanced as described herein.

2C. The UE 22 may send Registration Request with registration type set to “Mobility Registration Update”, including 5G-globally unique temporary identifier (GUTI) mapped from EPS GUTI as the old GUTI, the native 5G-GUTI (if available) as additional GUTI and indicating that the UE 22 is moving from EPC. The

Additional 5G-GUTI enables the AMF node 25a to retrieve the UE 22’ s MM context from the old AMF node 25b (if available). The UE 22 includes at least the S-NSSAIs associated with the established PDN connections in the Requested NSSAI in radio resource control (RRC) and NAS (as described in 3GPP TS 23.501 clause 5.15.7.2 or 5.15.7.3).

In the case of idle mode mobility, the UE 22 additionally includes a tracking area update (TAU) request message integrity protected using the EPS security context (for further security verification by the MME) in the Registration Request. If the UE 22 holds a native 5G-GUTI for this PLMN then the UE 22 also includes the GUAMI part of the native 5G-GUTI in RRC to enable the NG-RAN network node 16 (“NG-RAN 16”) to route the Registration Request to the same AMF node 25a (if available), and otherwise the UE 22 provides in RRC signalling a GUAMI mapped from the EPS GUTI and indicates it as“Mapped from EPS”.

The UE 22 integrity protects the Registration Request message using a 5G security context (if available).

Steps 3C-4C. These steps may correspond to Steps 2-3 of clause 4.2.2.2.2.

Step 5C(a). [Conditional] This step may only be performed for IDLE mode mobility. The target AMF node 25a derives the MME address and 3GPP 4^th

Generation (4G) GUTI from the old 5G-GUTI and sends a Context Request to the MME node 24 including EPS GUTI mapped from 5G-GUTI and the TAU request message according to e.g., 3GPP TS 23.401. The MME node 24 validates the TAU message.

Step 5C(b). [Conditional] If Step 5C(a) is performed, step 5 from clause 5.3.3.1 (Tracking Area Update procedure with Serving gateway (GW) change) in 3GPP TS 23.401 is performed with the modification captured in clause 4.11.1.5.3.

The AMF node 25a converts the received EPS MM Context into the 5GS MM Context. The received EPS UE context includes IMSI, ME Identity, UE EPS security context, UE Network Capability, and EPS Bearer context(s). The MME EPS Bearer context includes for each EPS PDN connection the IP address and FQDN for the S5/S8 interface of the PGW-C+SMF and APN.

The AMF node 25a queries the NRF in the serving PLMN by issuing the Nnrf_NFDiscovery_Request including the FQDN for the S5/S8 interface of the PGW- C+SMF, and the NRF provides the IP address or FQDN of the N 11/N16 interface of the PGW-C+SMF. The Context Response may include new information Return Preferred. Return Preferred may be considered an indication by the MME node 24 of a preferred return of the UE 22 to the last used EPS PLMN at a later access change to an EPS shared network. Based on the Return Preferred indication, the AMF node 25a may store the last used EPS PLMN ID in the UE 22 Context.

The Context Response may per PDN Connection (PDU Session) include information on EBI address and S-NSSAI (possibly also PDU Session ID) towards the requesting AMF node 25a. For the HR case, a proper v-SMF may then be selected (instead of a default SMF). In one or more embodiments, at least a portion of the information may correspond to at least a portion of the network slicing related information.

If the AMF node 25a cannot retrieve the address of the corresponding SMF for a PDN connection, it will not move the PDN connection to 5GS.

Step 6C may be performed only if the target AMF node 25a is different from the old AMF node 25b and the old AMF node 25b is in the same PLMN as the target AMF node 25a.

6C(a). [Conditional] If the UE 22 includes the 5G-GUTI as Additional GUTI in the Registration Request message, the target AMF node 25 sends a message to the old AMF node 25b. The old AMF node 25b validates the Registration request message. The target AMF node 25a retrieves the UE 22’ s subscription permanent identifier (SUPI) and MM Context, event subscription information by each consumer NF and the list of SM PDU Session ID/associated SMF ID for the UE 22 using one of the following three options:

AMF node 25a may invoke the

Namf_Communication_UEContextTransfer to the old AMF node 25b identified by the additional 5G-GUTI; or

if the old AMF node 25b and the target AMF node 25a are in the same AMF Set and UDSF is deployed, AMF node 25a may invoke

Nudsf_UnstructuredDataManagement_Query service operation for the UE 22 identified by the additional 5G-GUTI from the UDSF; or if the old AMF node 25b and the target AMF node 25a are in the same AMF Set, AMF node 25a may use implementation specific means to share UE 22 context.

Step 6C(b). [Conditional] If step 6C(a) is performed, the response is performed as described in step 5 in clause 4.2.2.2.2. If a native 5G security context for 3GPP access is available in the AMF node 25a (or has been retrieved in step 6C(a)), the AMF node 25a may continue to use this security context. Otherwise, the AMF node 25a may either derive a mapped security context from the EPS security context obtained from the MME node 24 or initiate an authentication procedure to the UE 22.

Step 7C. [Conditional] If the target AMF node 25a determines to initiate the authentication procedure to the UE 22 in step 6C(b) (e.g. the target AMF node 25a may not obtain the UE 22 MM context from AMF or other reasons), steps 8-9 of clause 4.2.2.2.2 are optionally performed.

Step 8C. [Conditional] If step 5C(b) is performed and the target AMF node 25a accepts to serve the UE 22, the target AMF node 25a sends Context

Acknowledge (Serving GW change indication) to the MME node 24 according to e.g., 3 GPP TS 23.401.

Step 9C. Steps 11-12 of clause 4.2.2.2.2 are optionally performed.

Step IOC. Void or skip this step.

Step l lC. Steps 13-14e of clause 4.2.2.2.2 are performed, with the following difference: if the MM context retrieved indicates non-3GPP access, then the target AMF node 25a indicates to the UDM that the target AMF node 25 a identity to be registered in the UDM applies to both 3GPP and non-3GPP accesses.

Step 12C. Void or skip this step.

Step 13C. Void or skip this step.

Step 14C. Steps 16-20 of clause 4.2.2.2.2 are optionally performed (initiated by target AMF node 25a) with the following addition:

In the home-routed roaming case and idle state mobility, the AMF node 25a selects a V-SMF per PDU Session (e.g., based on the received S- NSSAI for the PDU session) and invokes

Nsmf_PDUSession_CreateSMContext service operation of the V-SMF to create an association with the AMF node 25a. It includes UE 22 EPS PDN Connection, H-SMF ID, S-NSSAI and indicates all the PDU Session(s) to be re-activated as received in the Registration request message along with List Of PDU Sessions To Be Activated. The S-NSSAI is the S-NSSAI configured in AMF (e.g. the S-NSSAI received in the context response from the source MME node 25) for interworking, which is associated with e.g., the V-SMF. The V-SMF creates the association and based on the received SMF ID, the V-SMF invokes Nsmf_PDUSession_Create request service operation of the H-SMF and provides the information received from the AMF node 25a.

In the home-routed roaming case, the AMF node 25a derives the corresponding S-NSSAI value for the Serving PLMN based on the S- NSSAI value for the HPLMN received from the common session control node (e.g., PGW-C+SMF). If two values (e.g., the S-NSSAI value configured in the AMF node 25a for interworking and the S-NSSAI value for the Serving PLMN) are different, the AMF node 25a invokes

Nsmf_PDU_Session_CreateSMContext(PDU Session ID, S-NSSAI value for the Serving PLMN). The V-SMF updates 5G AN with the new S- NSSAI of the VPLMN by sending a N2 SM message to 5G AN via AMF node 25a.

o The H-SMF finds the corresponding PDU Session based on the PDN Connection Context in the request. The H-SMF initiates N4 Session modification procedure to establish the CN tunnel for the PDU Session, and for Idle state mobility registration, release the resource of the CN tunnels for EPS bearers corresponding to the PDU session as well. If the CN Tunnel info is allocated by the PGW-C+SMF, the tunnel info for PDU session is provided to PGW-U+UPF. If the CN Tunnel info is allocated by PGW-U+UPF, the tunnel info for PDU Session is provided to the PGW-C+SMF. The H-SMF responds V-SMF with the PDU Session ID

corresponding to the PDN Connection Context in the request, the allocated EBI(s) information, the S-NSSAI of the PDU Session, S- NSSAI of HPLMN, and other PDU session parameters, such as PDU Session Type, Session AMBR in the

Nsmf_PDUSession_Create response. The V-SMF updates its SM contexts and returns a

Nsmf_PDU_Session_CreateSMContextResponse message including the information received from the H-SMF. The V-SMF also includes the N2 SM Context in the response message sent to the AMF node 25a if the corresponding PDU Session is in the received List Of PDU Sessions To Be Activated. The V-SMF stores an association of the PDU Session ID and the H-SMF ID. The AMF node 25a stores the V-SMF ID and it also stores S- NSSAI and the allocated EBI(s) associated to the PDU Session ID. The AMF node 25a derives the S-NSSAI value for the Serving PLMN based on S-NSSAI value for the HPLMN, and sends the S- NSSAI value for the Serving PLMN to V-SMF by invoking Nsmf_PDUSession_UpdateSMContext service operation. The V- SMF updates NG-RAN 16 with the S-NSSAI value for the Serving PLMN via N2 SM message.

o If the SMF has not yet registered for this PDU Session ID, then the SMF registers with the UDM using Nudm_UECM_Registration (SUPI, DNN, PDU Session ID) for a given PDU Session as in step 4 of PDU Session Establishment Procedure in clause 4.3.2.

In non-roaming and LBO cases, AMF node 25a invokes

Nsmf_PDUSession_CreateSMContext Request (UE EPS PDN

Connection) service operation of the PGW-C+SMF and indicates all the PDU Session(s) to be re-activated as received in the Registration request message along with List Of PDU Sessions To Be Activated. This step is performed for each PDN Connection and the corresponding PGW-C+SMF address/ID in the UE 22 context the AMF received in Step 6C.

If the P-GW-C+SMF (H-SMF in case of home-routed roaming case) determines that seamless session continuity from EPS to 5GS is not supported for the PDU Session, then it does not provide SM information for the corresponding PDU Session but includes the appropriate cause code for rejecting the PDU Session transfer within the N2 SM Information. The PGW-C+SMF finds the corresponding PDU Session based on the PDN Connection Context in the request. The PGW-C+SMF initiates N4 Session modification procedure to establish the CN tunnel for the PDU Session, and for Idle state mobility registration, release the resource of the CN tunnels for EPS bearers corresponding to the PDU session as well. If the CN Tunnel info is allocated by the PGW-C+SMF, the tunnel info for PDU session is provided to PGW-U+UPF. If the CN Tunnel info is allocated by PGW-U+UPF, the tunnel info for PDU Session is provided to the PGW-C+SMF. The PGW-C+SMF updates its SM contexts and returns to the AMF node 25a a Nsmf_PDUSession_CreateSMContext Response message including the PDU Session ID corresponding to the PDN Connection Context in the request, the allocated EBI(s) information, the S- NSSAI of the PDU Session, and the N2 SM Context if the corresponding PDU Session is in the received List Of PDU Sessions To Be Activated.

The AMF node 25a stores an association of the PDU Session ID and the SMF ID, S-NSSAI, and the allocated EBI(s) associated to the PDU Session ID.

For Connected State mobility registration, the release of CN tunnels for EPS bearers corresponds to the PDU session is performed in the handover execution phase.

If the PDN Type of a PDN Connection in EPS is non-IP, and it was originally established as Ethernet PDU Session when the UE 22 was camping in 5GS (known based on local context information that was set to PDU Session Type Ethernet in UE 22 and SMF), the PDU Session Type in 5GS may be set to Ethernet by the SMF and UE 22. In case the PDN type of a PDN Connection in EPS is non-IP, and is locally associated in UE 22 and SMF to PDU Session Type Unstructured, the PDU Session Type in 5GS may be set to Unstructured by the SMF and UE 22.

Step 15C - 16C. These steps may be the same as and/or may correspond to Step 13 - 14 from clause 5.3.3.1 (Tracking Area Update procedure with Serving GW change) in 3GPP TS 23.401. Subsequently, the Steps 18C - 19C from clause 5.3.3.1 (Tracking Area Update procedure with Serving GW change) in 3GPP TS 23.401 are also executed.

Step 17C-18C. These steps follow and/or correspond to the steps 21 and 22 of Registration procedure in clause 4.2.2.2.2.

The Registration Accept message may include the updated 5G-GUTI to be used by the UE 22 in that PLMN over any access. If the active flag was included in the Registration request, the AMF node 25 a may provide NG-RAN with a Mobility Restriction List taking into account the last used EPS PLMN ID and the Return preferred indication. The Mobility Restriction List contains a list of PLMN IDs as specified by 3GPP TS 23.501. The Allowed NSSAI in the Registration Accept message may contain at least the S-NSSAIs corresponding to the active PDN

Connection(s) and the corresponding mapping to the HPLMN S-NSSAIs.

Therefore, some embodiments of the instant disclosure advantageously provide for an enhanced EPC to provide Network Slicing related information to the AMF to enable directly selecting appropriate Network Slices in 5GS, and thereby avoiding usage of default 5G resources.

In addition, some embodiments may include one or more of the following:

Embodiment Al. A first node configured to communicate with a second node, the first node configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to:

avoid use of at least one default resource at least in part by providing network slicing related information to the second network node.

Embodiment A2. The first node of Embodiment Al, wherein the second node is one selected from a group consisting of an access management function, AMF, and visitor- session management function, V-SMF.

Embodiment A3. The first node of Embodiment Al, wherein the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI.

Embodiment A4. The first node of Embodiment Al, wherein the at least one default resource includes at least one network functions, NF, resource.

Embodiment Bl. A method implemented in a first node, the method comprising: avoiding use of at least one default resource at least in part by providing network slicing related information to a second node.

Embodiment B2. The method of Embodiment B 1, wherein the second node is one selected from a group consisting of an access management function,

AMF, and visitor- session management function, V-SMF

Embodiment B3. The method of Embodiment B 1 , wherein the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI.

Embodiment B4. The method of Embodiment B 1, wherein the at least one default resource includes at least one network functions, NF, resource.

Embodiment Cl. A first node configured to communicate with a second node, the first node configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to:

receive network slicing related information from the second node, the network slicing information configured to avoid use of at least one default resource; and

optionally perform at least one action based on the received network slicing related information.

Embodiment C2. The first node of Embodiment Cl, wherein the first node is one selected from a group consisting of an access management function,

AMF, and visitor- session management function, V-SMF.

Embodiment C3. The first node of Embodiment Cl, wherein the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI.

Embodiment C4. The first node of Embodiment Cl, wherein the at least one default resource includes at least one network functions, NF, resource.

Embodiment Dl. A method implemented in a first node, the method comprising:

receiving network slicing related information from the second node, the network slicing information configured to avoid use of at least one default resource; and

optionally performing at least one action based on the received network slicing related information. Embodiment D2. The method of Embodiment Dl, wherein the first node is one selected from a group consisting of an access management function, AMF, and visitor-session management function, V-SMF.

Embodiment D3. The method of Embodiment D 1 , wherein the network slicing related information includes an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI.

Embodiment D4. The method of Embodiment Dl, wherein the at least one default resource includes at least one network functions, NF, resource.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, and/or computer program product. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or“module.” Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other

programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that

communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.

Claims

What is claimed is:

1. A method implemented in a mobility control node (24) of a first core network, the method comprising:

selecting (S100) a second node in a second core network for a handover of a user equipment, UE, (22) to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE (22) over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE (22) to the second core network; and

providing (S102) to the selected second node in the second core network, at the handover of the UE (22), the network slicing related information.

2. The method of Claim 1, wherein selecting the second node for the handover of the UE (22) further comprises at least one of:

selecting the second node using the at least a portion of the network slicing related information as an input into a domain name system, DNS, lookup procedure; and

selecting the second node using the at least a portion of the network slicing related information to query a network repository function, NRF, node.

3. The method of any one of Claims 1 and 2, wherein the mobility control node (24) of the first core network is a mobility management entity, MME, node and the first core network is an evolved packet core, EPC, network.

4. The method of any one of Claims 1-3, wherein the second node is an access management function, AMF, node and the second core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network.

5. The method of any one of Claims 1-4, wherein the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE (22) for the Packet Data session.

6. The method of Claim 5, wherein the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE (22).

7. The method of any one of Claims 1-6, further comprising:

during one of a Packet Data Network, PDN, Connectivity procedure and a Bearer Modification procedure for the UE (22), receiving, from a common session control node, the network slicing related information; and

wherein the providing the network slicing related information to the second node in the second core network further comprises providing the network slicing related information that is received from the common session control node.

8. The method of any one of Claims 1-7, wherein providing the network slicing related information to the second node further comprises:

including the network slicing related information in a forward relocation request to the second node in the second core network.

9. The method of any one of Claims 1-7, wherein providing the network slicing related information to the second node further comprises:

including the network slicing related information in a context response message to the second node in the second core network.

10. A method implemented in a mobility control node (25) of a first core network, the method comprising:

receiving (S104), at a handover of a user equipment, UE, (22) to the first core network, network slicing related information from a mobility control node (24) of a second core network, the network slicing related information associated to a Packet Data session established by the UE (22) over the second core network; and selecting (S106) a second node of the first core network for the handover of the UE (22) to the first core network using at least a portion of the network slicing related information, the selecting the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE (22) from the second core network to the first core network.

11. The method of Claim 10, wherein the mobility control node (25) of the first core network is an access management function, AMF, node and the first core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network.

12. The method of any one of Claims 10 and 11, wherein the selected second node of the first core network is a visitor-session management function, V-SMF, node.

13. The method of any one of Claims 10-12, wherein the mobility control node (25) of the second core network is a mobility management entity, MME, node and the second core network is an evolved packet core, EPC, network.

14. The method of any one of Claims 10-13, wherein the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE (22) for the Packet Data session.

15. The method of Claim 14, wherein the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE (22).

16. A mobility control node (24) of a first core network, the mobility control node (24) comprising processing circuitry (32), the processing circuitry (32) configured to cause the mobility control node (24) to:

select a second node in a second core network for a handover of a user equipment, UE, (22) to the second core network using at least a portion of network slicing related information associated to a Packet Data session established by the UE (22) over the first core network, the selecting the second node using the at least a portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE (22) to the second core network; and

provide to the selected second node in the second core network, at the handover of the UE (22), the network slicing related information.

17. The mobility control node of Claim 16, wherein the processing circuitry (32) is further configured to cause the mobility control node (24) to select the second node for the handover of the UE (22) by being configured to cause the mobility control node (24) to at least one of:

select the second node using the at least a portion of the network slicing related information as an input into a domain name system, DNS, lookup procedure; and

select the second node using the at least a portion of the network slicing related information to query a network repository function, NRF, node.

18. The mobility control node (24) of any one of Claims 16 and 17, wherein the mobility control node of the first core network is a mobility management entity, MME, node and the first core network is an evolved packet core, EPC, network.

19. The mobility control node (24) of any one of Claims 16-18, wherein the second node is an access management function, AMF, node and the second core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network.

20. The mobility control node (24) of any one of Claims 16-19, wherein the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE (22) for the Packet Data session.

21. The mobility control node (24) of Claim 20, wherein the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE (22).

22. The mobility control node (24) of any one of Claims 16-21, wherein the processing circuitry (32) is further configured to cause the mobility control node (25) to:

during one of a Packet Data Network, PDN, Connectivity procedure and a Bearer Modification procedure for the UE (22), receive, from a common session control node, the network slicing related information; and

provide the network slicing related information to the second node in the second core network by being configured to cause the mobility control node (24) to provide the network slicing related information that is received from the common session control node.

23. The mobility control node (24) of any one of Claims 16-22, wherein the processing circuitry (32) is further configured to cause the mobility control node (24) to provide the network slicing related information to the second node by being configured to cause the mobility control node (24) to:

include the network slicing related information in a forward relocation request to the second node in the second core network.

24. The mobility control node (24) of any one of Claims 16-22, wherein the processing circuitry (32) is further configured to cause the mobility control node (24) to provide the network slicing related information to the second node by being configured to cause the mobility control node (24) to:

include the network slicing related information in a context response message to the second node in the second core network.

25. A mobility control node (25) of a first core network, the mobility control node (25) comprising processing circuitry (42), the processing circuitry (42) configured to cause the mobility control node (25) to: receive, at a handover of a user equipment, UE, (22) to the first core network, network slicing related information from a mobility control node (24) of a second core network, the network slicing related information associated to a Packet Data session established by the UE (22) over the second core network; and

select a second node of the first core network for the handover of the UE (22) to the first core network using at least a portion of the network slicing related information, the selection of the second node of the first core network using the at least the portion of the network slicing related information being configured to avoid use of a default second node resource for the handover of the UE (22) from the second core network to the first core network.

26. The mobility control node (25) of Claim 25, wherein the mobility control node (24) of the first core network is an access management function, AMF, node and the first core network is a 3^rd Generation Partnership Project 5th Generation core, 5GC, network.

27. The mobility control node (25) of any one of Claims 25 and 26, wherein the selected second node of the first core network is a visitor- session management function, V-SMF, node.

28. The mobility control node (25) of any one of Claims 25-27, wherein the mobility control node (24) of the second core network is a mobility management entity, MME, node and the second core network is an evolved packet core, EPC, network.

29. The mobility control node (25) of any one of Claims 25-28, wherein the network slicing related information includes at least one of an evolved packet system, EPS, bearer identifier, EBI, address and single-network slice selection assistance information, S-NSSAI, used by the UE (22) for the Packet Data session.

30. The mobility control node (25) of Claim 29, wherein the network slicing related information further includes a protocol data unit, PDU, session identifier associated with the UE (22).