GB2605771A

GB2605771A - Method, apparatus and computer program

Info

Publication number: GB2605771A
Application number: GB2104851.7A
Authority: GB
Inventors: Chandramouli Devaki; Thiebaut Laurent; Liebhart Rainer
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2022-10-19
Also published as: GB202104851D0

Abstract

An AMF apparatus of an overlay network (O-AMF) receives a first message such as a registration request message from a user equipment, wherein the first message identifies a first underlay network that the UE is connected to. In response, the O-AMF determines whether the first underlay network supports one or more service types (e.g. IMS voice or IMS emergency services). The O-AMF provides a second message such as a registration accept message to the user equipment, wherein the second message comprises, based on the said determination, an indication of whether the one or more service types are supported by the underlay network and by the overlay network. The underlay network may be a standalone non-public network (SNPN) and the overlay network may be a public land mobile network (PLMN).

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

Field

The present application relates to a method, apparatus, and computer program for a wireless communication system.

Background

A communication system may be a facility that enables communication sessions between two or more entities such as user terminals, base stations/access points and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system may be provided, for example, by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

Summary

According to an aspect, there is provided an apparatus of an overlay network, the apparatus comprising means configured to perform: receiving a first message from a user equipment, wherein the first message identifies a first underlay network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the one or more service types are supported.

In an example, the means configured to perform determining whether the first underlay network supports the one or more service types is performed by: accessing a data store which comprises one or more indications of support for the one or more service types for at least one of: the first underlay network, and other underlay networks.

In an example, the indication of whether the one or more service types are supported is also based on support of the one or more service types in the overlay network.

In an example, the means configured to perform determining whether the first underlay network supports one or more service types is performed by: querying the first underlay network; storing an indication of whether the first underlay network supports the one or more service types in a data store, based on the querying.

In an example, the means configured to perform querying the first underlay network is performed by: providing a query message to one or more underlay networks including the first underlay network, to query whether the one or more underlay networks support the one or more service types; and receiving a response message from the one or more underlay network, wherein the response message comprises one or more indications of whether the one or more underlay networks support the one or more service types.

In an example, the means configured to perform querying the first underlay network is performed before the receiving the first message from the user equipment in order to learn about underlay network capabilities for the one or more service types and to store the indications in the data store accordingly.

In an example, the query message is provided to a network exposure function 20 of the one or more underlay networks.

In an example, a fully qualified domain name is derived, based on the identifier of the underlay network in the first message, to determine a network exposure function address of the network exposure function of the first underlay network.

In an example, the first message is a registration request message, and the 25 second message is a registration response message.

In an example, the one or more service types comprise at least one of: internet protocol multimedia subsystem voice services; internet protocol multimedia subsystem emergency services; an internet protocol multimedia subsystem voice over packet switched session; an internet protocol multimedia subsystem emergency over packet switched session.

In an example, the identifier of the first underlay network in the first message comprises at least one of: a stand alone non-public network identification comprising a public land mobile network identification and a network identifier; a public land mobile network identification comprising a mobile country code and a mobile network code.

In an example, the registration request message comprises next generation radio access network information.

In an example, the means are configured to perform: providing to at least one other network entity of the overlay network, the identifier of the first underlay network from the first message.

In an example, the at least one other network entity of the overlay network uses the identifier of the first underlay network to determine policies to apply for data services accessed by the user equipment, or uses the identification for charging data records.

In an example, the apparatus of the overlay network comprises an access and mobility management function.

In an example, the means is configured to perform: receiving a further registration request message from the user equipment, wherein the further registration request message identifies a second underlay network that the user equipment has connected to, wherein the first and second underlay networks are different.

According to an aspect, there is provided an apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: receiving a first message from a user equipment, wherein the first message identifies a first underlay network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the one or more service types are supported.

In an example, the apparatus is caused to perform determining whether the first underlay network supports the one or more service types is performed by: accessing a data store which comprises one or more indications of support for the one or more service types for at least one of: the first underlay network, and other underlay networks.

In an example, the apparatus is caused to perform determining whether the first underlay network supports one or more service types is performed by: querying the first underlay network; storing an indication of whether the first underlay network supports the one or more service types in a data store, based on the querying.

In an example, the apparatus is caused to perform querying the first underlay network is performed by: providing a query message to one or more underlay networks including the first underlay network, to query whether the one or more underlay networks support the one or more service types; and receiving a response message from the one or more underlay network, wherein the response message comprises one or more indications of whether the one or more underlay networks support the one or more service types.

In an example, the apparatus is caused to perform querying the first underlay network is performed before the receiving the first message from the user equipment in order to learn about underlay network capabilities for the one or more service types and to store the indications in the data store accordingly.

In an example, the query message is provided to a network exposure function of the one or more underlay networks.

In an example, the first message is a registration request message, and the 20 second message is a registration response message.

In an example, the apparatus is caused to perform: providing to at least one other network entity of the overlay network, the identifier of the first underlay network from the first message.

In an example, the apparatus is caused to perform: receiving a further registration request message from the user equipment, wherein the further registration request message identifies a second underlay network that the user equipment has connected to, wherein the first and second underlay networks are different.

According to an aspect, there is provided an apparatus comprising means configured to perform: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.

In an example, the indication of whether the one or more service types are supported is based on support of the one or more service types in the overlay network and the first underlay network.

In an example, the identification of the first underlay networks comprises at least one of: a stand alone non-public network identification comprising a public land mobile network identification and a network identifier; and a public land mobile network identification comprising a mobile country code and a mobile network code.

In an example, the first message is provided to an access and mobility management function of the overlay network.

In an example, the means are configured to perform: connecting to the first underlay network, before providing the first message.

In an example, the means are configured to perform: providing a further message to the overlay network, wherein the further 5 message identifies a second underlay network that the user equipment has subsequently connected to, wherein the first and second underlay networks are different.

In an example, the apparatus is comprised in a user equipment.

According to an aspect, there is provided an apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.

In an example, the apparatus is caused to perform: connecting to the first underlay network, before providing the first message.

In an example, the apparatus is caused to perform: providing a further message to the overlay network, wherein the further message identifies a second underlay network that the user equipment has subsequently connected to, wherein the first and second underlay networks are different.

In an example, the apparatus is comprised in a user equipment.

According to an aspect, there is provided a method comprising: receiving a first message from a user equipment, wherein the first message identifies a first underlay lo network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the one or more service types are supported.

In an example, the determining whether the first underlay network supports the 15 one or more service types comprises: accessing a data store which comprises one or more indications of support for the one or more service types for at least one of: the first underlay network, and other underlay networks.

In an example, the indication of whether the one or more service types are supported is also based on support of the one or more service types in the overlay 20 network.

In an example, the determining whether the first underlay network supports one or more service types comprises: querying the first underlay network; storing an indication of whether the first underlay network supports the one or more service types in a data store, based on the querying.

In an example, the querying the first underlay network comprises: providing a query message to one or more underlay networks including the first underlay network, to query whether the one or more underlay networks support the one or more service types; and receiving a response message from the one or more underlay network, wherein the response message comprises one or more indications of whether the one or more underlay networks support the one or more service types.

In an example, the querying the first underlay network is performed before the receiving the first message from the user equipment in order to learn about underlay network capabilities for the one or more service types and to store the indications in the data store accordingly.

In an example, the first message is a registration request message, and the second message is a registration response message.

In an example, the method comprises: providing to at least one other network entity of the overlay network, the identifier of the first underlay network from the first message.

In an example, the method is performed by an access and mobility management function of the overlay network.

In an example, the method comprises: receiving a further registration request message from the user equipment, wherein the further registration request message identifies a second underlay network that the user equipment has connected to, wherein the first and second underlay networks are different.

According to an aspect, there is provided a method comprising: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.

In an example, the first message is provided to an access and mobility 20 management function of the overlay network.

In an example, the method comprises: connecting to the first underlay network, before providing the first message.

In an example, the method comprises: providing a further message to the overlay network, wherein the further message identifies a second underlay network that the user equipment has subsequently connected to, wherein the first and second underlay networks are different.

In an example, the method is performed by a user equipment.

According to an aspect, there is provided a computer program comprising computer executable instructions which when run on one or more processors perform: receiving a first message from a user equipment, wherein the first message identifies a first underlay network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the one or more service types are supported.

According to an aspect, there is provided a computer program comprising computer executable instructions which when run on one or more processors perform: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.

A computer product stored on a medium may cause an apparatus to perform lo the methods as described herein.

An electronic device may comprise apparatus as described herein.

According to an aspect, there is provided an apparatus comprising means configured to perform: receiving a first indication from an underlay network as to whether the underlay network supports one or more service types; receiving a second indication from an overlay network as to whether the overlay network supports the one or more service types; and determining whether there is support for the one or more service types based on the first and second indications.

In an example, the means are configured to perform: when both the first and second indications indicate support for the one or more service types, determining that there is support for the one or more service types.

In an example, the one or more service types comprises: internet protocol multimedia subsystem voice over packet switched sessions.

In an example, the means configured to perform determining whether there is support for the one or more service types based on the first and second indications is performed by: determining whether there is support for internet protocol multimedia subsystem voice over packet switched sessions based on the first and second indications.

In an example, the one or more service types comprises: internet protocol multimedia subsystem emergency services.

In an example, the means configured to perform determining whether there is support for the one or more service types based on the first and second indications is performed by: determining whether there is support for internet protocol multimedia subsystem emergency services based on the first and second indications.

In an example, at least one of the first and second indications are comprised within a registration accept message.

In an example, the first indication is received from an access and mobility management function of the underlay network, and the second indication is received 5 from an access and mobility management function of the overlay network.

According to an aspect, there is provided an apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: receiving a first indication from an underlay network as to whether the underlay network supports one or more service 10 types; receiving a second indication from an overlay network as to whether the overlay network supports the one or more service types; and determining whether there is support for the one or more service types based on the first and second indications. In an example, the apparatus is caused to perform: when both the first and second indications indicate support for the one or more service types, determining that there is support for the one or more service types.

In an example, the determining whether there is support for the one or more service types based on the first and second indications is performed by: determining 20 whether there is support for internet protocol multimedia subsystem voice over packet switched sessions based on the first and second indications.

In an example, the determining whether there is support for the one or more service types based on the first and second indications is performed by: determining whether there is support for internet protocol multimedia subsystem emergency services based on the first and second indications.

In an example, the first indication is received from an access and mobility management function of the underlay network, and the second indication is received from an access and mobility management function of the overlay network.

According to an aspect, there is provided a method comprising: receiving a first indication from an underlay network as to whether the underlay network supports one or more service types; receiving a second indication from an overlay network as to whether the overlay network supports the one or more service types; and determining whether there is support for the one or more service types based on the first and second indications.

In an example, the method comprises: when both the first and second indications indicate support for the one or more service types, determining that there is support for the one or more service types.

In an example, the determining whether there is support for the one or more service types based on the first and second indications comprises: determining whether there is support for internet protocol multimedia subsystem voice over packet switched sessions based on the first and second indications.

In an example, the one or more service types comprises: internet protocol 15 multimedia subsystem emergency services.

In an example, the determining whether there is support for the one or more service types based on the first and second indications comprises: determining whether there is support for internet protocol multimedia subsystem emergency services based on the first and second indications.

According to an aspect, there is provided a computer program comprising computer executable instructions which when run on one or more processors perform: receiving a first indication from an underlay network as to whether the underlay network supports one or more service types; receiving a second indication from an overlay network as to whether the overlay network supports the one or more service types; and determining whether there is support for the one or more service types based on the first and second indications.

A computer product stored on a medium may cause an apparatus to perform the methods as described herein.

An electronic device may comprise apparatus as described herein.

In the above, various aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described above.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims.

According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure.

List of abbreviations: AF: Application Function AMF: Access Management Function AN: Access Network BS: Base Station CHF Charging Function DL: Downlink eNB: eNodeB FQDN: Fully Qualified Domain Name gNB: gNodeB IPSec: Internet Protocol Security IMS: Internet Protocol Multimedia Subsystem LTE: Long Term Evolution NEF: Network Exposure Function NG-RAN: Next Generation Radio Access Network NF: Network Function NID: Network Identifier N3IWF: Non-3GPP Interworking Function NR: New Radio NRF: Network Repository Function NW: Network MCC: Mobile Country Code MNC: Mobile Network Code MS: Mobile Station RAN: RF: SMF: SNPN: UE: UL: ULI: U-Network: UPF: 3GPP: 5G: 5GC: 5G-AN: 5GS: Mobile Termination Overlay Network Policy Control Function Public Land Mobile Network Radio Access Network Radio Frequency Session Management Function Stand-alone Non-Public Network User Equipment Uplink User Location Information Underlay Network User Plane Function 3rd Generation Partnership Project 5th Generation Core network Radio Access Network 5G System

Description of Ficiures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a schematic representation of a 5G system; Figure 2 shows a schematic representation of a control apparatus; Figure 3 shows a schematic representation of a terminal; Figure 4 shows a schematic example of a system with an underlay and an overlay network; Figure 5 shows an example signalling diagram between a user equipment, an underlay network and an overlay network; Figure 6 shows another example signalling diagram between a user equipment, an underlay network and an overlay network; Figure 7 shows an example signalling diagram of communications between network functions of an overlay network and network functions of underlay networks; Figure 8 shows an example method flow diagram performed by a network entity; Figure 9 shows another example method flow diagram performed by a network entity; and Figure 10 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the method of Figures 8 and 9.

Detailed description

Before explaining in detail some examples of the present disclosure, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described examples.

In a wireless communication system 100, such as that shown in Figure 1, mobile communication devices/terminals or user apparatuses, and/or user equipments (UE), and/or machine-type communication devices 102 are provided wireless access via at least one base station (not shown) or similar wireless transmitting and/or receiving node or point. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices. The communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier.

In the following certain examples are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. Before explaining in detail the examples of disclose, certain general principles of a wireless communication system, access systems thereof, and mobile communication devices are briefly explained with reference to Figures 1, 2 and 3 to assist in understanding the technology underlying the described examples.

Figure 1 shows a schematic representation of a 5G system (5GS) 100. The SOS may comprises a device 102 such as user equipment or terminal, a 5G access network (5G-AN) 106, a 50 core network (500) 104, one or more network functions (NF), one or more application function (AF) 108 and one or more data networks (DN) 110.

The 50-AN 106 may comprise one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) centralized unit functions.

The 5GC 104 may comprise an access management function (AMF) 112, a session management function (SMF) 114, an authentication server function (AUSF) 116, a user data management (UDM) 118, a user plane function (UPF) 120, a network exposure function (NEF) 122, non-3GPP interworking function (N3IWF) 124 and/or other NFs. Some of the examples as shown below may be applicable to 3GPP 50 standards. However, some examples may also be applicable to 40, 30 and other 3GPP standards.

In a communication system, such as that shown in Figure 1, mobile communication devices/terminals or user apparatuses, and/or user equipments (UE), and/or machine-type communication devices are provided with wireless access via at least one base station or similar wireless transmitting and/or receiving node or point.

The terminal is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices. The communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier. Terminal 102 is also depicted in Figure 5, with labels 10, 16, 19, 20A, 20B. Terminal 102 is also depicted in Figure 6 with label 601, for example. The terminal 102 may use communications services. Two or more terminals may use the same communications services. In other examples, two or more terminals may have different services from each other.

Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the 50-AN or the 500 as illustrated on Figure 1. The control apparatus may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and an input/output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 50-AN or the SOC. In some examples, each function of the 50-AN or the 5GC comprises a control apparatus 200. In alternative examples, two or more functions of the 50-AN or the 5GC may share a control apparatus.

Figure 3 illustrates an example of a terminal 300, such as the terminal illustrated 5 on Figure 1. The terminal 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with 10 wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device or any combinations of these or the like. The terminal 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

The terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement.

The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302a and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a.

The processor, storage and other relevant control apparatus may be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

A work item has been presented, that is related to 3GPP TS 23.501, which introduces an architecture that enables use of underlay network and overlay network architecture. An underlay network is physical infrastructure via which a user equipment (UE) can utilise to access to an overlay network. The underlay network provides the UE access to a data network and the UE can use this access to the data network to register at, and obtain services from, the overlay network. The underlay and overlay networks may comprise all of the physical devices, radio equipment, switches and routers in a network. The underlay and overlay networks may also comprise all of the network functions that control the physical infrastructure and handle the user equipment initiated and related signalling and user plane traffic. The UE may achieve access to the overlay network via a non-3GPP interworking function (N3IWF). In this case, the underlay network and the overlay network may not trust each other nor have business relationship between each other. An example of the business relationship is a service level agreement (SLA). However, the UE should have valid credentials to access services in both networks. Example services that a UE may wish to access include a connectivity service in the underlay network and IF Multimedia Subsystem (IMS) services in the overlay network.

Although the above and the following may refer to the N3IWF and specific 3GPP entities, it is understood that the presently described techniques are applicable for various example use cases. For example, obtaining stand-alone non-public network (SNPN) services via a public land mobile network (PLMN) access. In another example, obtaining PLMN services via a SNPN access. In another example, using a Layer 3 (L3) relay solution wherein a relay UE obtains connectivity via an underlay network and a remote UE uses the connectivity to obtain services via an overlay network.

In the 30PP specifications, a scenario is presented in which a user equipment obtains services from a PLMN via a SNPN. This scenario is shown in Figure 4. In this architecture the UE will register with an AMF in the underlay network, and subsequently register with an AMF in the overlay network.

Figure 4 shows a schematic example of a system with an underlay and an overlay network. The system comprises a user equipment 401. There is also provided an underlay network 403. The underlay network 403 may be a stand-alone non-public network or a public land mobile network. The system also comprises an overlay network 405. The overlay network may be a public land mobile network or stand-alone non-public network.

The underlay network 403 comprises an underlay AMF (U-AMF) 407. The underlay network 403 also comprises an underlay SMF (U-SMF) 409. The underlay network 403 also comprises an underlay UPF (U-UPF) 411. The underlay network 403 may comprise further network elements, as shown in Figure 1. The U-AMF 407 and U-SMF 409 can communicate via an N11 link. The U-SMF 409 and U-UPF 411 can communicate via an N4 link.

The system also comprises a non-public network 30PP access 413. The non-public network 30PP access 413 can communicate with the U-AMF 407 and U-UPF 411 via N2 and N3 links respectively. The UE 401 can communicate with the U-AMF 407 via an Ni link.

The overlay network 405 comprises an overlay AMF (0-AMF) 415. The overlay network 405 also comprises an overlay SMF (0-SMF) 417. The overlay network 405 also comprises an overlay UPF (0-UPF) 419. The overlay network 405 also comprises a non-3GPP interworking function 421 (N3IWF). The O-AMF 415 can communicate with the O-SMF 417 via an N11 link. The O-SMF 417 and the O-UPF 419 can communicate via an N4 link. The 0-UPF 419 and the non-3GPP interworking function 421 can communicate via an N3 link. The non-3GPP interworking function 421 and the O-AMF 415 can communicate via an N2 link. Furthermore, the O-UPF 419 can communicate with a first data network (DN) 423 via an N6 link.

The U-UPF 411 and the non-3GPP interworking function 421 can both communicate with a second ON 425 via an N6 link. The UE 401 is able to communicate with the O-AMF 415 via the underlay network 403 and the non-3GPP interworking function 421. There is also shown a link 'NWu' between the UE 401 and the N3IWF 421. NWu is a reference point between the UE and the N3IWF for establishing a secure tunnel between the UE 401 and the N3IWF 421 so that control-plane and user-plane data can be exchanged securely between the UE 401 and a core network.

In has been proposed that voice services and emergency services support should be introduced for SNPN deployment scenarios, as well as the example scenario of Figure 4. It has been proposed that if the UE 4W accesses the PLMN 405 over a NWu via a SNPN 403, the AMF 415 in the serving PLMN may send an indication toward the UE 401. The indication may be sent during a registration procedure to indicate whether an IP multimedia subsystem (IMS) voice over packet-switched (PS) session is supported or not.

Since the overlay and underlay networks may not have a service level agreement (SLA) between each other, the underlay network capability regarding voice support is not known to the overlay network. However, the AMF in the overlay network should indicate whether IMS voice over PS is supported or not. In order to indicate support for IMS voice over PS to the UE, the overlay and underlay networks should satisfy two capabilities: Firstly, the radio and core networks are capable of delivering the necessary quality of service needed to deliver voice services.

Secondly, an IMS network is deployed offering voice service to UEs.

The overlay network does not necessarily know about underlay radio and core network capabilities. The overlay network may not know about the capability of the underlay network due to, for example, a lack of SLA and vice versa. Therefore, the proposal identified above may not always be possible if the overlay network does not know the capabilities of the underlay network, but does only know IMS services are offered by the overlay network. One of more of the following examples discussed below aim to address this.

Figure 5 shows an example signalling diagram between a UE, an underlay 20 network and an overlay network.

At 5501, an AMF in underlay network (U-AMF) provides an indication to the UE regarding support of at least one of: IMS voice over PS session, support of emergency services, and other potential services. The U-AMF may provide the indication in a registration accept message to the UE once the UE registers with the underlay network. In other examples, the indication is provided in other suitable messages.

Setting this indication may be based on underlay network capabilities. For example, the indication may be based on underlay NO-RAN capability to support voice and/or underlay 5GC capability to support IMS services. The capability can be locally configured in the AMF.

At, S503, an AMF in an overlay network (0-AMF) provides an indication to a UE regarding support of at least of: IMS voice over PS session, support of emergency services, and other potential services. The O-AMF may provide the indication in a registration accept message to the UE once the UE registers with the overlay network. In other examples, the indication is provided in other suitable messages. Setting this indication may be based on overlay network capabilities. For example, the indication may be based on overlay NO-RAN capability to support voice and/or overlay 500 capability to support IMS services and/or presence of IMS. The capability can be locally configured in the AMF.

At 5505, if the UE is initiating registration with the underlay network and subsequently with the overlay network with the intent to use IMS voice service, emergency services or other potential services, using the underlay and overlay network capabilities, then the UE has to interpret the voice support indicators provided by underlay and overlay networks as follows.

For example, when the indication from the U-AMF indicates that IMS voice over PS session indicator is supported, then this is interpreted by the UE that radio and core of the underlay network supports IMS voice service. If the indication from the UAMF indicates that IMS emergency services over PS is supported, then this is interpreted by the UE that the radio and core network of the underlay network are capable of delivering the necessary quality of service needed to deliver IMS voice and emergency services..

For example, when the indication from the O-AMF indicates that IMS voice over PS session is supported, then this is interpreted by the UE that IMS voice is supported. If the indication from the O-AMF indicates that IMS emergency services over PS session is supported, then this is interpreted by the UE that IMS emergency service is supported.

Both IMS voice over PS Session indicators provided by the overlay network and the underlay network should indicate IMS voice service is supported for the UE to interpret that IMS voice service is supported in this scenario where UE connects via underlay network to access IMS services in overlay network.

Figure 6 shows another example signalling diagram between a UE, an underlay network and an overlay network.

At S601, the UE provides a registration request message to an AMF of an overlay network (0-AMF). The registration request message may identify the underlay network that the UE is connected to. The UE may provide an SNPN ID of the underlay network that the UE is connected to, in the message (in example case where the underlay network is a SNPN). The SNPN ID may comprise a PLMN ID and a network identifier (N ID). The UE may provide an PLMN ID of the underlay network that the UE is connected to, in the message (in example case where the underlay network is a PLMN). The PLMN ID may comprise an MCC and an MNC of the underlay network that the UE is connected to. The message may also comprise NG-RAN information of the underlay network. The NG-RAN information may comprise a gNB ID, a cell ID or a tracking area ID.

At S603, an N3IWF of the overlay network provides a message to the O-AMF.

The message may comprise user location information (ULD. The N3IWF in the overlay network may be aware of the source IF address of an IF security (IPsec) tunnel between the UE and the N3IWF. The N3IWF may provide this source IF address as part of the ULI in the message to the O-AMF. The O-AMF may determine the corresponding underlay network based on the source IF address.

At S605, the O-AMF determines whether one or more underlay networks have the capability for at least one of IMS voice and IMS emergency services. Once the 0-AMF has determined the capability of an underlay network, the O-AMF may store the information in a table or in any other suitable store. In some examples, the determination may be performed by another network function of the overlay network. This determination by the O-AMF will be discussed in more detail below alongside Figure 7. In other examples, the determination may include accessing the information from a table or other suitable store.

In an example, the O-AMF may determine whether IMS voice and/or emergency services are supported in the underlay network based on the SNPN ID or the PLMN ID provided by the UE during the registration message. In another example, the O-AMF may determine whether IMS voice and/or emergency services are supported in the underlay network based on the source IF address of the IPsec tunnel established between UE and N3IWF provided by the N3IWF to the AMF.

The O-AMF can propagate the underlay network identifier (SNPN ID or PLMN ID) or source IF address of the IPsec tunnel to other network functions (e.g., O-SMF) within the message of 5611, which will be discussed below.

If the UE changes the underlay network, the UE may re-register in the overlay network to refresh the information about the underlay network. For example, the UE 30 may send a new SNPN ID or PLMN ID in a registration request message to the 0-AMF.

The O-AMF, or other network function in the overlay network, may use the NEF to query the underlay network about voice and emergency services support. This query procedure may take place during the UE registration. In other examples, the query procedure may take place independently of the UE registration. For example, the query procedure may take place during a previous registration of another UE via the same underlay network. In another example, the query procedure may take place at any point before a UE from the underlay network registers in the overlay network. 5 The underlay networks may reply to the NEF query with an indication of whether the underlay network supports voice and/or emergency services or not. From the query result the overlay network may build an internal database containing this information. The information in the database may be used by any O-AMF or other network function in the overlay network. The database may be stored at the UDM of the overlay 10 network. In an example, the database may be in the form of a table.

Mapping of an underlay network SNPN ID or PLMN ID to an NEF address to query the underlay network for voice and/or emergency services support may be performed by a local configuration in the overlay network. Alternatively, mapping of an underlay network SNPN ID or PLMN ID to an NEF address to query the underlay network for voice and/or emergency services support may be performed by the underlay SNPN ID or PLMN ID being used to derive a fully qualified domain name (FQDN) to determine the NEF address in the overlay network. The derivation of the FQDN to determine the NEF address may be used in case of a globally unique PLMN ID or in a case of an NID assignment mode 2 (as defined in TS 23.003). When NID assignment mode 2 is used, an example for an NEF FQDN may be "nef.NID.5gc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org".

At 5607, the O-AMF provides a registration accept message to the UE. The registration accept message may comprise an indication of whether IMS voice and/or emergency services are supported. This indication may be set based on whether the underlay network supports the capabilities required for these services and also the overlay network supports the capabilities required for these services The O-AMF may retrieve the capability information from the table (or other data store) using an network identifier of the underlay network. If the underlay network is an SNPN then the underlay network may be identified by a PLMN ID and an NID. If the underlay network is a PLMN then the underlay network may be identified by a PLMN ID.

At 5609, the UE provides a protocol data unit (PDU) session establishment request message to the O-AMF.

At S611, the O-AMF forwards the PDU session establishment request message to an SMF of the overlay network (0-SMF). When the UE issues the PDU Session establishment request (e.g. as defined in 30PP TS 24.501) to the overlay network, the O-AMF may propagate/forward the request to the O-SMF (e.g. as defined in 30PP TS 23.502). When the O-AMF propagates the message, the O-AMF may add in the underlay network identifier based on the SNPN ID or the PLMN ID provided by the UE during the registration request message (S601).

At S613, the O-SMF forwards the PDU session establishment request message to another network function of the overlay network. For example, the another network function may be a PCF or charging function (CHF). The message may comprise the underlay network identifier based on the SNPN ID or the PLMN ID provided by the UE during the registration request message (S601). The O-SMF may propagate/forward the underlay network identifier information to other entities of the overlay network such as the O-PCF and 0-CHF. The O-PCF and 0-CHF may use the information to determine proper network policies (0-PCF) or to store it in charging data records (0-CHF) e.g. for statistical purposes. The different network entities of the overlay network, such as for example, the O-AMF, O-SMF, O-PCF and 0-CHF, may be embodied by a single entity (i.e. single apparatus entity).

Figure 7 shows an example signalling diagram of communications between network functions of an overlay network and network functions of underlay networks. In the example of Figure 7, two different underlay network are shown. It should be 20 understood that any number of underlay networks may be provided in a system.

At S701, an NEF of a first underlay network sends a query to an AMF of the first underlay network. The query may request whether the first underlay network supports IMS voice and/or emergency services. The AMF of the first underlay network may send a response message to the NEF (not shown). In this example, the NEF learns the support from the AMF. In other examples, the NEF is configured with the information of whether the first network supports IMS voice and/or emergency services.

At S703, an NEF of a second underlay network sends a query to an AMF of the second underlay network. The query may request whether the second underlay network supports IMS voice and/or emergency services. The AMF of the second underlay network may send a response message to the NEF (not shown). In this example, the NEF learns the support from the AMF. In other examples, the NEF is configured with the information of whether the second network supports IMS voice and/or emergency services.

At S705, an AMF of an overlay network sends a query to the NEF of the first underlay network. The query may request whether the first underlay network supports IMS voice and/or emergency services. In some examples, step 5705 may trigger step S701; At S707, the NEF of the first underlay network sends a response message to the AMF of the overlay network. The response message may indicate whether the first underlay network supports IMS voice and/or emergency services.

At 5709, an AMF of an overlay network sends a query to the NEF of the second underlay network. The query may request whether the second underlay network 10 supports IMS voice and/or emergency services. In some examples, step S709 may trigger step 5703; At 5711, the NEF of the second underlay network sends a response message to the AMF of the overlay network. The response message may indicate whether the second underlay network supports IMS voice and/or emergency services.

At 5713, the AMF of the overlay network populates a table which shows the support/capabilities of the underlay networks for IMS voice and/or emergency services. If there is already an entry in the table for an underlay network, then the AMF may update the entry if it has changed. For example, the table may indicate that the first underlay network supports IMS voice and emergency services, while the second underlay network does not support IMS voice and emergency services. It should be understood that a table is used as an example of a data store. The information of the capabilities of the underlay networks may be stored in any suitable manner.

It should be understood that the order in which the steps occur in Figure 7 may take place in a different order.

One or more of the previous examples, allows the UE to determine, via which networks, the UE can access IMS voice and emergency services when these services are provided by an overlay network accessible via one or more underlay networks. The UE may make this determination by considering indicators received from both underlay network and overlay network (Figure 5), or by a unique indicator received from the overlay network (Figures 6 and 7). The overlay network can determine the capability of the underlay network based on the identification of the underlay network that has been received from the UE.

One of more of the examples above provide an efficient mechanism to allow a user equipment to know voice and emergency services capability of underlay and overlay networks. This may be of particular importance when there is no SLA between underlay and overlay networks.

Figure 8 shows an example method flow performed by an apparatus. The apparatus may be comprised within a network entity. In an example, the apparatus may be comprised within a network function of the overlay network. In an example, the apparatus may be comprised within an access and mobility management function. In S801, the method comprises receiving a first message from a user equipment, wherein the first message identifies a first underlay network.

In S803, the method comprises, in response to the receiving, determining 10 whether the first underlay network supports one or more service types.

In S805, the method comprises providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the one or more service types are supported.

Figure 9 shows an example method flow performed by an apparatus. The 15 apparatus may be comprised within a terminal. In an example, the apparatus may be comprised within a user equipment.

In S901, the method comprises providing a first message to an overlay network, wherein the first message identifies a first underlay network.

In S903, the method comprises receiving a second message from the overlay 20 network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.

Figure 10 shows a schematic representation of non-volatile memory media 1100a (e.g. computer disc (CD) or digital versatile disc (DVD)) and 1100b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 1102 which when executed by a processor allow the processor to perform one or more of the steps of the methods of Figure 8 or Figure 9.

It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

The examples may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Alternatively, or additionally some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and/or method steps previously described. That circuitry may be provided in the base station and/or in the communications device.

As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analogue and/or digital circuitry); (b) combinations of hardware circuits and software, such as: (i) a combination of analogue and/or digital hardware circuit(s) with software/firmware and (H) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example integrated device.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

Claims: 1. An apparatus of an overlay network, the apparatus comprising means configured to perform: receiving a first message from a user equipment, wherein the first message identifies a first underlay network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises, based on the said determination, an indication of whether the one or more service types are supported.
2. An apparatus according to claim 1, wherein the means configured to perform determining whether the first underlay network supports the one or more service types is performed by: accessing a data store which comprises one or more indications of support for the one or more service types for at least one of: the first underlay network, and other underlay networks.
3. An apparatus according to claim 1 or claim 2, wherein the indication of whether the one or more service types are supported is also based on support of the one or more service types in the overlay network.
4. An apparatus according to any of claim 1 to 3, wherein the means configured to perform determining whether the first underlay network supports one or more service types is performed by: querying the first underlay network; storing an indication of whether the first underlay network supports the one or more service types in a data store, based on the querying.
5. An apparatus according to claim 4, wherein the means configured to perform querying the first underlay network is performed by: providing a query message to one or more underlay networks including the first underlay network, to query whether the one or more underlay networks support the one or more service types; and receiving a response message from the one or more underlay network, wherein 5 the response message comprises one or more indications of whether the one or more underlay networks support the one or more service types.
6. An apparatus according to claim 4 or claim 5, wherein the means configured to perform querying the first underlay network is performed before the receiving the first message from the user equipment in order to learn about underlay network capabilities for the one or more service types and to store the indications in the data store accordingly.
7. An apparatus according to any of claims 1 to 6, wherein a fully qualified domain name is derived, based on the identifier of the underlay network in the first message, to determine a network exposure function address of the network exposure function of the first underlay network.
8. An apparatus according to any of claims 1 to 7, wherein the first message is a registration request message, and the second message is a registration response message.
9. An apparatus according to any of claims 1 to 8, wherein the one or more service types comprise at least one of: internet protocol multimedia subsystem voice services; internet protocol multimedia subsystem emergency services; an internet protocol multimedia subsystem voice over packet switched session; an internet protocol multimedia subsystem emergency over packet switched session.
10. An apparatus according to any of claims 1 to 9, wherein the identifier of the first underlay network in the first message comprises at least one of: a stand alone non-public network identification comprising a public land mobile network identification and a network identifier; a public land mobile network identification comprising a mobile country code and a mobile network code.
11. An apparatus according to any of claims 1 to 10, wherein the means are configured to perform: providing to at least one other network entity of the overlay network, the identifier of the first underlay network from the first message.
12. An apparatus according to claim 11, wherein the at least one other network entity of the overlay network uses the identifier of the first underlay network to determine policies to apply for data services accessed by the user equipment, or uses the identification for charging data records.
13. An apparatus according to any of claims 1 to 12, wherein the means is configured to perform: receiving a further registration request message from the user equipment, wherein the further registration request message identifies a second underlay network that the user equipment has connected to, wherein the first and second underlay networks are different.
14. An apparatus comprising means configured to perform: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second 25 message comprises an indication of whether one or more service types are supported by the first underlay network.
15. An apparatus according to claim 14, wherein the indication of whether the one or more service types are supported is based on support of the one or more service types in the overlay network and the first underlay network.
16. An apparatus according to claim 14 or claim 15, wherein the first message is a registration request message, and the second message is a registration response message.
17. An apparatus according to any of claims 14 to 16, wherein the one or more service types comprise at least one of: internet protocol multimedia subsystem voice services; internet protocol multimedia subsystem emergency services; an internet protocol multimedia subsystem voice over packet switched session; an internet protocol multimedia subsystem emergency over packet switched session.lo
18. An apparatus according to any of claims 14 to 17, wherein the identification of the first underlay networks comprises at least one of: a stand alone non-public network identification comprising a public land mobile network identification and a network identifier; and a public land mobile network identification comprising a mobile country code 15 and a mobile network code.
19. An apparatus according to any of claims 14 to 18, wherein the first message is provided to an access and mobility management function of the overlay network.
20. An apparatus according to any of claims 14 to 19, wherein the means are configured to perform: connecting to the first underlay network, before providing the first message.
21. An apparatus according to any of claims 14 to 20, wherein the means are configured to perform: providing a further message to the overlay network, wherein the further message identifies a second underlay network that the user equipment has subsequently connected to, wherein the first and second underlay networks are different.
22. A method comprising: receiving a first message from a user equipment, wherein the first message identifies a first underlay network; in response to the receiving, determining whether the first underlay network supports one or more service types; and providing a second message to the user equipment, wherein the second message comprises based on the said determination an indication of whether the 5 one or more service types are supported.
23. A method comprising: providing a first message to an overlay network, wherein the first message identifies a first underlay network; and receiving a second message from the overlay network, wherein the second message comprises an indication of whether one or more service types are supported by the first underlay network.
24. An apparatus comprising means configured to perform: receiving a first indication from an underlay network as to whether the underlay network supports one or more service types; receiving a second indication from an overlay network as to whether the overlay network supports the one or more service types; and determining whether there is support for the one or more service types based on the first and second indications.
25. An apparatus according to claim 24, wherein the means are configured to perform: when both the first and second indications indicate support for the one or more service types, determining that there is support for the one or more service types.
26. An apparatus according to claim 24 or claim 25, wherein the one or more service types comprises: internet protocol multimedia subsystem voice over packet switched sessions.
27. An apparatus according to claim 26, wherein the means configured to perform determining whether there is support for the one or more service types based on the first and second indications is performed by: determining whether there is support for internet protocol multimedia subsystem voice over packet switched sessions based on the first and second indications.
28. An apparatus according to any of claims 24 to 27, wherein the one or more service types comprises: internet protocol multimedia subsystem emergency services.
29. An apparatus according to claim 28, wherein the means configured to perform determining whether there is support for the one or more service types based on the first and second indications is performed by: determining whether there is support for internet protocol multimedia subsystem emergency services based on the first and second indications.
30. An apparatus according to any of claims 24 to 29, wherein the first indication is received from an access and mobility management function of the underlay network, and the second indication is received from an access and mobility management function of the overlay network.