WO2021063496A1

WO2021063496A1 - Registration in ims using slice-specific identifier

Info

Publication number: WO2021063496A1
Application number: PCT/EP2019/076709
Authority: WO
Inventors: Alexander Milinski; Martin Konecny
Original assignee: Nokia Technologies Oy
Priority date: 2019-10-02
Filing date: 2019-10-02
Publication date: 2021-04-08

Abstract

An apparatus comprising means for performing: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem (190); registering the apparatus in the internet protocol multimedia subsystem (190) using the first slice-specific identifier.

Description

REGISTRATION IN IMS USING SLICE-SPECIFIC IDENTIFIER

Field

This disclosure relates to wireless communications. Some examples relate to a mechanism for a device to use multiple network slices.

Background

In some networks, such as 5G networks, a network may comprise one or more network slices. A different application may operate in each network slice.

Statement of invention

According to a first aspect there is provided an apparatus comprising means for performing: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; and registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to some examples, the means are further configured to perform: generating a second slice-specific identifier using the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the second slice-specific identifier.

According to some examples, the means are further configured to perform: using the first slice-specific identifier to communicate in the first network slice of the internet protocol multimedia subsystem; and using the second slice-specific identifier to communicate in the second network slice of the internet protocol multimedia subsystem.

According to some examples, generating a first slice-specific identifier comprises appending or prepending the identifier of the first network slice to the first private user identity. According to some examples, generating a second slice-specific identifier comprises appending or prepending the identifier of the second network slice to the first private user identity.

According to some examples, the means are further configured to perform: using, for requesting communications with at least one device, at least one public user identity assigned to the first slice specific identifier at the internet protocol multimedia subsystem.

According to some examples, two or more public user identities are assigned to the first slice specific identifier.

According to some examples, the at least one public user identity is assigned by the internet protocol multimedia subsystem to the first slice-specific identifier and to at least one other slice-specific identifier.

According to some examples, the at least one public user identity can be assigned to the first slice-specific identifier and to an identifier derived from a second private user identity.

According to some examples, the identifier derived from a second private user identity comprises a slice-specific identifier.

According to some examples, a private user identity comprises an internet protocol multimedia subsystem private user identity (IMPI).

According to some examples, a public user identity comprises an internet protocol multimedia subsystem public user identity (IMPU).

According to some examples, the apparatus comprises a user equipment.

According to a second aspect there is provided an apparatus comprising at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: generating a first slice- specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; and registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to some examples, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: generating a second slice-specific identifier using the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the second slice-specific identifier.

According to some examples, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: using the first slice-specific identifier to communicate in the first network slice of the internet protocol multimedia subsystem; and using the second slice-specific identifier to communicate in the second network slice of the internet protocol multimedia subsystem.

According to some examples, generating a first slice-specific identifier comprises appending or prepending the identifier of the first network slice to the first private user identity.

According to some examples, generating a second slice-specific identifier comprises appending or prepending the identifier of the second network slice to the first private user identity.

According to some examples, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform: using, for requesting communications with at least one device, at least one public user identity assigned to the first slice specific identifier at the internet protocol multimedia subsystem.

According to some examples, the apparatus comprises a user equipment. According to a third aspect there is provided an apparatus comprising: circuitry for generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; and circuity for registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier

According to a fourth aspect there is provided a method comprising: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering an apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to some examples, the method comprises: generating a second slice-specific identifier using the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the second slice- specific identifier.

According to some examples, the method comprises: using the first slice- specific identifier to communicate in the first network slice of the internet protocol multimedia subsystem; and using the second slice-specific identifier to communicate in the second network slice of the internet protocol multimedia subsystem.

According to some examples, the method comprises: using, for requesting communications with at least one device, at least one public user identity assigned to the first slice specific identifier at the internet protocol multimedia subsystem.

According to some examples, the at least one public user identity is assigned by the internet protocol multimedia subsystem to the first slice-specific identifier and to at least one other slice-specific identifier. According to some examples, the at least one public user identity can be assigned to the first slice-specific identifier and to an identifier derived from a second private user identity.

According to some examples, the method is performed by a user equipment.

According to a fifth aspect there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; and registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to a sixth aspect there is provided a computer program comprising instructions stored thereon for performing at least the following: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering an apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to a seventh aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; and registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

According to an eighth aspect there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering an apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier. According to a ninth aspect there is provided an apparatus comprising means for performing: receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice- specific identifier in association with a first private user identity.

According to some examples, the first slice-specific identifier is sent from a UE and received from a S-CSCF via a P-CSCF and l-CSCF.

According to some examples, the first slice specific identifier is generated at the user equipment from the first private user identity and an identifier of a first network slice of the internet protocol multimedia subsystem.

According to some examples, the means are further configured to perform: receiving a second slice-specific identifier generated at the user equipment in the internet protocol multimedia subsystem; storing the second slice-specific identifier in connection with the first private user identity.

According to some examples, the second slice specific identifier is generated at the user equipment from the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem.

According to some examples, the means are further configured to perform: storing at least one public user identity in association with at least one service profile and the first slice specific identifier.

According to some examples, the means are further configured to perform: storing two or more public user identities in association with the first slice specific identifier.

According to some examples, the means are further configured to perform: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and at least one other slice-specific identifier.

According to some examples, the means are further configured to perform: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and a second private user identity.

According to some examples, the means are further configured to perform: receiving a query from a network entity of the internet protocol multimedia subsystem, the query comprising a public user identity; and sending, to the network entity, the at least one service profile associated with the public user identity.

According to some examples, the query comprises a private user identity. According to some examples, the network entity comprises a call state control function.

According to a tenth aspect there is provided an apparatus comprising at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receiving a second slice-specific identifier generated at the user equipment in the internet protocol multimedia subsystem; storing the second slice- specific identifier in connection with the first private user identity.

According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: storing at least one public user identity in association with at least one service profile and the first slice specific identifier.

According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: storing two or more public user identities in association with the first slice specific identifier.

According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and at least one other slice- specific identifier.

According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and a second private user identity. According to some examples, the at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receiving a query from a network entity of the internet protocol multimedia subsystem, the query comprising a public user identity; and sending, to the network entity, the at least one service profile associated with the public user identity.

According to some examples, the query comprises a private user identity.

According to some examples, the network entity comprises a call state control function. According to some examples, the identifier derived from a second private user identity comprises a slice-specific identifier.

According to a eleventh aspect there is provided an apparatus comprising: circuitry for receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; circuity for storing the first slice-specific identifier in association with a first private user identity.

According to a twelfth aspect there is provided a method comprising: receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity. According to some examples, the first slice-specific identifier is sent from a UE and received from a S-CSCF via a P-CSCF and l-CSCF.

According to some examples the method comprises: receiving a second slice- specific identifier generated at the user equipment in the internet protocol multimedia subsystem; storing the second slice-specific identifier in connection with the first private user identity.

According to some examples the method comprises: storing at least one public user identity in association with at least one service profile and the first slice specific identifier.

According to some examples, the method comprises: storing two or more public user identities in association with the first slice specific identifier.

According to some examples, the method comprises: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and at least one other slice-specific identifier.

According to some examples, method comprises: storing the at least one public user identity in association with: the first slice-specific identifier; the at least one service profile; and a second private user identity.

According to some examples, wherein the method comprises: receiving a query from a network entity of the internet protocol multimedia subsystem, the query comprising a public user identity; and sending, to the network entity, the at least one service profile associated with the public user identity.

According to some examples, the query comprises a private user identity.

According to some examples, the network entity comprises a call state control function.

According to some examples, the identifier derived from a second private user identity comprises a slice-specific identifier. According to some examples, a private user identity comprises an internet protocol multimedia subsystem private user identity (IMPI).

According to some examples, the method is performed by a home subscriber server.

According to a thirteenth aspect there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice- specific identifier in association with a first private user identity.

According to a fourteenth aspect there is provided a computer program comprising instructions stored thereon for performing at least the following: receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

According to a fifteenth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

According to an sixteenth aspect there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

Brief description of Figures

The invention will now be described in further detail, byway of example only, with reference to the following examples and accompanying drawings, in which:

Figure 1 A shows a schematic representation of a network architecture; Figure 1 B shows a schematic representation of a network architecture;

Figure 2 shows a schematic representation of an information structure;

Figure 3 shows schematic representation of an apparatus according to an example; Figure 4 shows a schematic representation of an apparatus according to an example;

Figure 5 shows a flow chart of a method; and Figure 6 shows a flow chart of a method.

Detailed description

The present disclosure relates to wireless communications. Some examples relate to a mechanism for a device to use multiple network slices.

In some cases, a network may be divided into network slices. For example, 3GPP Release 15 (Rel-15) describes network slicing of a mobile 5G network.

Network slicing may be used for applications in an internet protocol (IP) multimedia subsystem (IMS).

Each network slice of a network maybe considered to be a virtualized and independent logical network on the same physical network infrastructure of the network. Each network slice may comprise an isolated end-to-end network adapted to fulfil requirements requested by a particular application.

In an exemplary scenario as shown in Figure 1A, a network 105 may comprise 3 slices: Slice a 103a; Slice b 103b; and Slice c 103c. It will be understood that in other examples, the network may comprise fewer or more network slices. Each network slice 103a, 103b and 103c of Figure 1A may be used for a different application. For example, slice a 103a may be used by User Equipment (UE) 101 a for mobile and wireless communications, slice b 103b may be used by UE 101 b for Internet of Things (loT) communications and slice b 103c may be used by UE 101c for Reliable low latency communications. These applications are listed for exemplary purposes only. Another exemplary application that could use a network slice may be, for example, machine-to-machine communications. It may be desirable for a UE (which may comprise mobile phone or any 5G enabled device, for example a car) to communicate using more than one slice. In the example of Figure 1B, UE 101a accesses an Internet Protocol (IP) Multimedia Subsystem (IMS) 190 of a network from more than one network slice. In the example of Figure 1 B, UE 101a accesses IMS 190 from network slice 103c and 103b.

In the example of Figure 1B, IMS 190 comprises at least: a Serving Call State Control Function (S-CSCF) 190a; an Interrogating Call State Control Function (S- CSCF) 190b and a Proxy Call State Control Function (P-CSCF) 190c.

In some examples, when a UE such as UE 101a accesses an IMS from more than one slice, UE 101a registers with multiple (slice-specific) IP addresses. These multiple IP addresses may be valid at the same time.

It is desirable that the network slice can be extended to IMS 190; in other words, it should be possible to use different IMS entities for a UE using different network slices in some cases, but also to use the same IMS entities for a UE using different network slices in other cases.

In some examples, a UE 101 a may use the same S-CSCF 190a of IMS 190 for different network slices 103a, 103b and 103c.

According to definitions in 3GPP standards, an IP Multimedia Private Identity (IMPI) and an IP Multimedia Public Identity (IMPU) comprise uniform resource identifier (URIs). A URI for an IMPU may comprise digits (a Tel URI, such as tel:+1- 555-555-5555) or alphanumeric identifiers (a Session Initiation Protocol (SIP) URI, such as sip:john.smith@example.com" ).

An IMPI comprises a unique allocated global identity assigned by a home network operator. An IMPU is used by a user for requesting communications to other users.

According to definitions in 3GPP standards, there may be multiple IMPUs per IMPI. The IMPU can also be shared with another phone, so that both can be reached with the same IMPU.

According to some examples of the invention, a UE which wants to register to the IMS via a certain 5G network slice creates a second level of IMPIs. In some examples of the invention, these IMPIs may be referred to as slice-specific IMPIs. For each network slice and for each particular IMPI, one slice-specific IMPI may be generated. The slice-specific IMPIs may be used for IMS registration. With this procedure, different slices may use the same IMS network or network functions. A UE can create a slice-specific IMPI for each combination of slice used in an IMS and generic IMPI. The slice-specific IMPI matches to the slice-specific IMPI provisioned in the subscriber profile in the HSS.

The slice-specific IMPI can be generated at a UE by an application using a generation mechanism. To ensure that the slice-specific IMPI provisioned at a HSS matches the slice-specific IMPI generated at a UE, an application used at a HSS to provision a slice-specific IMPI may use the same mechanism as the generation mechanism used at the UE.

For example the slice-specific IMPI can be built from: a generic IMPI assigned to a user equipment by a home network operator; and a slice ID.

According to some examples, a UE may register with an IMS. When registering with the IMS via a certain 5G network slice, a UE may add a slice identification to the registration.

During a registration process, a UE may send a request for registration to a S- CSCF (via P-CSCF; l-CSCF) in a SIP message. The request received by the S-CSCF may be mapped to a Diameter message or HTTP2 message that is sent to a HSS.

In some examples, a UE may insert a slice identification to an IMPI used at registration. When inserting the slice identification to the IMPI, the UE may, for example append or prepend the slice identification to the IMPI.

In some examples, different slices of a network may use the same IMS networks or network functions.

For registration in Internet Protocol (IP) Multimedia Subsystem (IMS), a slice- specific IMPI may comprise, for example, an International Mobile Subscriber Identity (IMSI), a Network Slice Selection Identifier (NSSID), Mobile Network Code (MNC) and Mobile Country Code (MCC). The format of slice specific IMPI could, for example, be as follows

IMSI@Nssid<NSSID>.ims.mnc<MNC>.mcc<MCC>.3gppnetwork.org

From all IMS network functions the HSS may be aware of above defined slice specific IMPIs. The HSS may provision the slice-specific IMPI in the HSS.

The structure of subscriber profile, or service profile, in the HSS is extended to contain also slice specific IMPIs that are used in SIP messages as standard IMPIs. A subscriber profile is shown in Figure 2. An example of a subscriber profile that may be stored in a home subscription server (HSS) is shown in Figure 2. As shown in Figure 2, the structure of subscriber profile in the FISS can be extended to comprise slice specific IMPIs. These slice specific IMPIs may be used in SIP messages as standard IMPIs. In the example of Figure 2, subscription 220 comprises two generic IMPIs 222a and 222b which may be assigned, for example by the network operator. Each IMPI 222a and 222b is valid per SIM card or terminal.

Slice specific IMPIs and service profiles (SP) containing letter a are related to slice a of the network of Figure 2, and slice specific IMPIs and service profiles (SP) containing letter b are related to slice b.

IMPMa 224 is a slice specific IMPI related to slice a and derived from IMPI1 222a. IMP1a 224 is derived at a UE. A UE may use IMPI1 222a assigned by the network operator and a slice ID for slice a to derive IMP1a 224.

IMPMb 226 is a slice specific IMPI related to slice b and derived from IMPI1 222a. IMP1b 226 is derived at a UE. A UE may use IMPI1 222a assigned by the network operator and a slice ID for slice b to derive IMP1b 226.

IMPI2a 228 is a slice specific IMPI related to slice a and derived from IMPI2 222b. IMP2a 228 is derived at a UE. A UE may use IMPI2 222b assigned by the network operator and a slice ID for slice a to derive IMP2a 228. IMPI2b 230 is a slice specific IMPI related to slice b and derived from IMPI2

222b. IMP2b 230 is derived at a UE. A UE may use IMPI2 222b assigned by the network operator and a slice ID for slice b to derive IMP2b 230.

From the point of view of an IMS core, the slice specific IMPIs 224, 226, 228 and 230 may be used as standard IMPIs. IMS Public User Identities (IMPUs) may be assigned to slice specific IMPIs depending on whether IMPUs are used in one slice or multiple slices. IMPUs may be assigned by the HSS. This assignment may take place during the provision of a subscriber profile by the HSS. IMPUs may also be assigned to slice specific IMPIs depending on whether the IMPUs are shared or non-shared from the generic IMPIs 222a and 222b point of view (i.e. whether the IMPUs can be registered in multiple

UEs).

IMPU1 232 and IMPU2234 can be registered in one slice for a UE mapped to generic IMPI1 222a. IMPU1 232 and IMPU2 234 are part of the same Implicit Registration Set (IRS), IRS1. IMPU6 242 and IMPU7 244 can be registered in one slice in a UE mapped to generic IMPI2222b. IMPU6242 and IMPU7244 are part of the same IRS, IRS5.

IMPU3 236 can be registered in two slices (mapped to IMPMa 224 and IMPMb 226) in a UE mapped to generic IMPI1 222a. IMPU3236 forms IRS2. IMPU4 238 is shared across UEs and can be registered in two slices, a and b, in all UEs. IMPU4238 forms IRS3.

IMPU5 240 is shared across UEs can be registered in one slice in all UEs. IMPU5 240 forms IRS4.

If an IMPU can be registered in multiple slices, then multiple service profiles (one for each slice) may be assigned to such IMPU, because different slices will use different services. For example, IMPU3 236 can be used in slice a and slice b. As such, SPa2248 and SPb1 250 are assigned to IMPU3236. Similarly, IMPU4238 can be used in slice a and slice b. SPa3252 and SPb3256 are assigned to IMPU4238.

IMPU1 232 and IMPU2 234 can be used in slice a. They are both assigned SPa1 246.

IMPU5 240 can be used in slice b. IMPU5240 is assigned SPb2254.

IMPU7 244 can be used in slice b. IMPU7244 is assigned SPb4258.

According to some examples, only a single IMPI needs to be provisioned to the UE, but the UE can use the IMPI to build multiple slice specific IMPIs, allowing multiple independent registrations in the same IMS network. There is no requirement to change the IMS core nodes (e.g. there is no requirement to change the l-CSCF, P- CSCF or S-CSCF).

According to some examples, a FISS may receive a query from a network entity, such as a CSCF for example. The query may comprise an IMPU and IMPI. The HSS may then return the subscriber profile associated with the IMPU to the network entity. For example, if a network entity queries a HSS using IMPU2234 and IMPI1 a 224, the HSS may search the HSS using IMPI1 a 224 or IMPU2234 and return subscriber profile 220.

A possible wireless communication device will now be described in more detail with reference to Figure 3 showing a schematic, partially sectioned view of a communication device 300. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise 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), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

A wireless communication device may be for example a mobile device, that is, a device not fixed to a particular location, or it may be a stationary device. The wireless device may need human interaction for communication, or may not need human interaction for communication. In the present teachings the terms UE or “user” are used to refer to any type of wireless communication device.

The wireless device 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 wireless device. A wireless device is typically provided with at least one data processing entity

301 , at least one memory 302 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 data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The user may control the operation of the wireless device by means of a suitable user interface such as key pad 305, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 308, a speaker and a microphone can be also provided. Furthermore, a wireless communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto. The communication devices 302, 304, 305 may access the communication system based on various access techniques. Figure 4 shows an example of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, gNB, a central unit of a cloud architecture or a node of a core network such as an MME or S-GW, a scheduling entity such as a spectrum management entity, or a server or host, or an IAB or relay node. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 600 can be arranged to provide control on communications in the service area of the system. The control apparatus 400 comprises at least one memory 401 , at least one data processing unit 402, 403 and an input/output interface 404. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head. For example the control apparatus 400 or processor4601 can be configured to execute an appropriate software code to provide the control functions.

Figure 5 is a flow chart of a method according to an example. The flow chart of Figure 5 is viewed from the perspective of an apparatus such as UE 101 a, for example. At S501, the method comprises the step of generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem.

At S502, the method comprises the step of registering an apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier. The method may comprise registering the apparatus that is performing the method.

Figure 6 is a flow chart of a method according to an example. The flow chart of Figure 6 is viewed from the perspective of an apparatus such as a FISS, for example At S601, the method comprises the step of receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem. At S602, the method comprises storing the first slice-specific identifier in association with a first private user identity.

It will be understood that the described steps of the method are not necessarily purely sequential, according to some examples. For example, in terms of timings there may be overlap between S601 and S602.

In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention 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 the invention is not limited thereto. While various aspects of the invention 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.

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 analog and/or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) 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 a mobile phone or server, to perform various functions) 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 and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device. The embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures 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 physical media is a non-transitory media.

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 comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this invention. Flowever, 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 of this invention will still fall within the scope of this invention as defined in the appended claims. Indeed there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1 . An apparatus comprising means for performing: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

2. An apparatus according to claim 1 , wherein the means are further configured to perform: generating a second slice-specific identifier using the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the second slice-specific identifier.

3. An apparatus according to claim 2, wherein the means are further configured to perform: using the first slice-specific identifier to communicate in the first network slice of the internet protocol multimedia subsystem; and using the second slice-specific identifier to communicate in the second network slice of the internet protocol multimedia subsystem.

4. An apparatus according to any preceding claim, wherein generating a first slice-specific identifier comprises appending or prepending the identifier of the first network slice to the first private user identity.

5. An apparatus according to any preceding claim, wherein the means are further configured to perform: using, for requesting communications with at least one device, at least one public user identity assigned to the first slice specific identifier at the internet protocol multimedia subsystem.

6. An apparatus according to claim 5, wherein the at least one public user identity is assigned by the internet protocol multimedia subsystem to the first slice- specific identifier and to at least one other slice-specific identifier.

7. An apparatus according to claim 5 or claim 6, wherein the at least one public user identity can be assigned to the first slice-specific identifier and to an identifier derived from a second private user identity.

8. An apparatus according to any preceding claim wherein the means comprises: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

9. An apparatus comprising means for performing: receiving, at the apparatus, a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

10. An apparatus according to claim 9, wherein the means are further configured to perform: receiving a second slice-specific identifier generated at the user equipment in the internet protocol multimedia subsystem; storing the second slice-specific identifier in connection with the first private user identity.

11. An apparatus according to any preceding claim, wherein the means are further configured to perform: storing at least one public user identity in association with at least one service profile and the first slice specific identifier.

12. An apparatus according to claim 11 , wherein the means are further configured to perform: storing the at least one public user identity in association with: the first slice- specific identifier; the at least one service profile; and at least one other slice-specific identifier.

13. An apparatus according to claim 11 or claim 12, wherein the means are further configured to perform: storing the at least one public user identity in association with: the first slice- specific identifier; the at least one service profile; and a second private user identity.

14. An apparatus according to any of claims 11 to 13, wherein the means are further configured to perform: receiving a query from a network entity of the internet protocol multimedia subsystem, the query comprising a public user identity; and sending, to the network entity, the at least one service profile associated with the public user identity.

15. An apparatus according to any of claims 9 to 14, wherein the means comprises: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

16. A method comprising: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering an apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

17. A method according to claim 16, wherein the method comprises: generating a second slice-specific identifier using the first private user identity and an identifier of a second network slice of the internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the second slice-specific identifier.

18. A method according to claim 17, wherein the method comprises: using the first slice-specific identifier to communicate in the first network slice of the internet protocol multimedia subsystem; and using the second slice-specific identifier to communicate in the second network slice of the internet protocol multimedia subsystem.

19. A method according to any of claims 16 to 18, wherein generating a first slice- specific identifier comprises appending or prepending the identifier of the first network slice to the first private user identity.

20. A method according to any of claims 16 to 19, wherein the method comprises: using, for requesting communications with at least one device, at least one public user identity assigned to the first slice specific identifier at the internet protocol multimedia subsystem.

21. A method according to claim 20, wherein the at least one public user identity is assigned by the internet protocol multimedia subsystem to the first slice-specific identifier and to at least one other slice-specific identifier.

22. A method according to claim 20 or claim 21 , wherein the at least one public user identity can be assigned to the first slice-specific identifier and to an identifier derived from a second private user identity.

23. A computer program comprising instructions for causing an apparatus to perform at least the following: generating a first slice-specific identifier using a first private user identity and an identifier of a first network slice of an internet protocol multimedia subsystem; registering the apparatus in the internet protocol multimedia subsystem using the first slice-specific identifier.

24. A method comprising: receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.

25. A method according to claim 24, wherein the method comprises: receiving a second slice-specific identifier generated at the user equipment in the internet protocol multimedia subsystem; storing the second slice-specific identifier in connection with the first private user identity.

26. A method according to preceding claim 24 or claim 25, wherein the method comprises: storing at least one public user identity in association with at least one service profile and the first slice specific identifier.

27. A method according to claim 26, wherein the method comprises: storing the at least one public user identity in association with: the first slice- specific identifier; the at least one service profile; and at least one other slice-specific identifier.

28. A method according to claim 26 or claim 27, wherein the method comprises: storing the at least one public user identity in association with: the first slice- specific identifier; the at least one service profile; and a second private user identity.

29. A method according to any of claims 26 to 28, wherein the method comprises: receiving a query from a network entity of the internet protocol multimedia subsystem, the query comprising a public user identity; and sending, to the network entity, the at least one service profile associated with the public user identity.

30. A computer program comprising instructions for causing an apparatus to perform at least the following: receiving a first slice-specific identifier generated at a user equipment in an internet protocol multimedia subsystem; storing the first slice-specific identifier in association with a first private user identity.