GB2624435A - Enhancement for data session management - Google Patents

Abstract

A Network Slice Admission Control Function NSACF, keeps track of the current number of Protocol Data Unit PDU sessions existing per Single-Network Slice Selection Assistance Information S-NSSAI that is subject to Network Slice Admission Control NSAC. When an event triggers the number of PDU sessions of a UE within a network slice to increase, then the NSACF checks if the maximum number of PDU sessions for the particular S-NSSAI has been reached and, if so, applies admission control. However, this monitoring may be prone to error particularly in relation to handover of an endpoint terminal from a first access network function (e.g. AMF), at which the endpoint terminal had established data sessions for a network slice, to a second access network function, at which the established data sessions are suspended or at which the network slice is not supported. In this instance, a network management function transmits a notification towards the NSACF comprising information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice. This facilitates an accurate count of the current active PDU sessions.

Description

ENHANCEMENT FOR DATA SESSION MANAGEMENT

DESCRIPTION

Technical Field

The present disclosure relates to a method and an apparatus for enhancing a network function for slice admission control for suspended data sessions.

Background Art

The following description of background art may include insights, discoveries, understandings or disclosures, or associations, together with disclosures not known to the relevant prior art, to at least some examples of embodiments of the present disclosure but provided by the disclosure. Some of such contributions of the disclosure may be specifically pointed out below, whereas other of such contributions of the disclosure will be apparent from the related context.

In the last years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), Digital Subscriber Line (DSL), or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3" generation (3G) like the Universal Mobile Telecommunications System (UMTS), fourth generation (4G) communication networks or enhanced communication networks based e.g. on Long Term Evolution (LTE) or Long Term Evolution-Advanced (LTE-A), fifth generation (5G) communication networks, cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolution (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN), Bluetooth or Worldwide Interoperability for Microwave Access (WiMAX), took place all over the world. Various organizations, such as the European Telecommunications Standards Institute (EIS!), the 3' Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International Telecommunication Union (ITU), 3' Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WMAX Forum and the like are working on standards or specifications for telecommunication network and access environments.

In this context, network slicing is a feature of great interest.

Network slicing is a key 5G feature to support different services using the same underlying mobile network infrastructure [1]. Network slices can differ either in their service requirements like Ultra-Reliable Low Latency Communication (URLLC) and enhanced Mobile Broadband (eMBB) or the tenant that provides those services.

A network slice is uniquely identified via the S-NSSAI (Single-Network Slice Selection Assistance Information). Current 3GPP specifications allow a user equipment (UE) to be simultaneously connected and served by at most eight slices corresponding to eight network slices meaning eight S-NSSAls [1]. On other hand, each cell may support tens or even hundreds of slices, e.g., in the current specifications a Tracking Area (TA) can have a support up to 1024 network slices [2].

The S-NSSAI may include both Slice Service Type (SST) and Slice Differentiator (SD) field with a total length of 32 bits or include only SST field part in which case the length of S-NSSAI is 8 bits only, as illustrated in Figure 1 [3] [4].

The SST field may have standardized and non-standardized values. Values 0 to 127 belong to the standardized SST range. For instance, SST value of 1 may indicate that the slice is suitable for handling of 5G eMBB, 2 for handling of URLLC, etc. SD is operator-defined only To enable monitoring at a slice level, the Network Slice Admission Control Function (NSACF) controls the number of registered UEs per S-NSSAI and/or the number of PDU sessions that can be generated in case that a S-NSSAI is subject to admission control [3].

NSACF is configured with a maximum number of UEs and/or maximum number of PDU sessions allowed per S-NSSAI subject to Network Slice Admission Control (NSAC). Moreover, it is also configured with details with respect to the applicable access types for the S-NSSAI, for instance 3GPP access type or non-3GPP or both.

To facilitate further slice monitoring, the NSACF can enable an event-based network slice status notification and report it to the consumer Network Functions (NF)s. The NSACF may be responsible for one or more S-NSSAls and there may be one or multiple NSACFs deployed in the network.

With regard to the NSACF, NSACF records the maximum number of UEs that can access an S-NSSAI that is subject to NSAC. When an event that causes the number of UEs of an S-NSSAI to increase, for instance Access and Mobility Management Function (AMF) triggers a UE registration procedure as of clause 4.2.2.2.2 [5], then NSACF confirms whether the UE ID exists in the list of registered UEs and if not NSACF checks if the maximum number of UEs for that S-NSSAI is reached. In case of such an occurrence NSACF applies admission control.

With further regard to the NSACF, NSACF keeps track of the current number of PDU sessions existing per S-NSSAI that is subject to NSAC. When an event that triggers the number of PDU sessions of a UE within a network slice to increase (i.e., SMF that triggers PDU session establishment as of clause 4.3.2 [5] occurs, then NSACF checks if the maximum number of PDU sessions for the particular S-NSSAI has been reached. If that is the case, then it applies admission control.

However, the above-outlined NSACF's monitoring of the maximum number of UEs as well as of the maximum number of PDU sessions may be prone to error.

Thus, there is need for improvement. Particularly, there is need for NSACF enhancement for suspended PDU sessions.

It is therefore an object of the present disclosure to improve the prior art.

Cited References [1]: 3GPP TS 38.300 [2]: 3GPP TS 38.423 [3]: 3GPP TS 23.501 [4]: 3GPP TS 23.003 [5]: 3GPP TS 23.502 35 The following meanings for the abbreviations used in this specification apply: 2G Second Generation 3G Third Generation 3GPP 31d Generation Partnership Project 3GGP2 31d Generation Partnership Project 2 4G Fourth Generation 5G Fifth Generation 6G Sixth Generation AMF Access and Mobility Management Function AN Access Node AP Access Point BS Base Station CDMA Code Division Multiple Access DSL Digital Subscriber Line ORB Data Radio Bearer EDGE Enhanced Data Rates for Global Evolution EEPROM Electrically Erasable Programmable Read-only Memory eMBB enhanced Mobile Broadband eNB Evolved Node B ETSI European Telecommunications Standards Institute gNB Next Generation Node B GPRS General Packet Radio System GSM Global System for Mobile communications IEEE Institute of Electrical and Electronics Engineers ISDN Integrated Services Digital Network ITU International Telecommunication Union LTE Long Term Evolution LTE-A Long Term Evolution-Advanced MANETs Mobile Ad-Hoc Networks MT Mobile Terminated NB Node B NF Network Function NSAC Network Slice Admission Control NSACF Network Slice Admission Control Function PDU Protocol Data Unit RA Radio Area RAM Random Access Memory RAN Radio Access Network ROM Read Only Memory S-NSSAI Single-Network Slice Selection Assistance Information SD Slice Differentiator SMF Session Management Function SST Slice Service Type TA Tracking Area TISPAN Telecoms & Internet converged Services & Protocols for Advanced Networks UE User Equipment UMTS Universal Mobile Telecommunications System URLLC Ultra-Reliable Low Latency Communication UWB Ultra-Wideband WCDMA Wideband Code Division Multiple Access VVIMAX Worldwide Interoperability for Microwave Access

SUMMARY

It is an objective of various examples of embodiments of the present disclosure to improve the prior art. Hence, at least some examples of embodiments of the present disclosure aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of examples of embodiments of the present disclosure are set out in the appended claims and relate to methods, apparatuses and computer program products relating to enhancement of control network function for controlling slice admission for suspended data sessions.

The objective is achieved by the methods, apparatuses and non-transitory storage media as specified in the appended claims. Advantageous further developments are set out in respective dependent claims.

Any one of the aspects mentioned according to the appended claims enables enhancement of control network function for controlling slice admission for suspended data sessions, thereby allowing to solve at least part of the problems and drawbacks as identified/derivable from above. Thus, improvement as well as advantages over the prior art are achieved by methods, apparatuses and computer program products enabling enhancement of control network function for controlling slice admission for suspended data sessions.

Further advantages become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying drawings, in which (in the individual parts per Figure, hollow circles indicate where to connect the parts per Figure with each other): Figure 1 shows a format of S-NSSAI; Figure 2 (parts 1/2 and 2/2) shows a message sequence chart for embodiment 1 for UE count, Figure 3 (parts 1/2 and 2/2) shows a message sequence chart for embodiment 1 for PDU session count; Figure 4 shows interactions among AMF and SMF; Figure 5 (parts 1/2 and 2/2) shows a message sequence chart for embodiment 2 for UE count; Figure 6 (parts 1/3, 2/3 and 3/3) shows a message sequence chart for embodiment 2 for PDU session count; Figure 7 (parts 1/2 and 2/2) shows a messages sequence chart for embodiment 3 for UE count; Figure 8 (parts 1/2 and 2/2) shows a message sequence chart for embodiment 3 for PDU session count; Figure 9 shows a flowchart illustrating steps corresponding to a method according to various examples of embodiments; Figure 10 shows a flowchart illustrating steps corresponding to a method according to various examples of embodiments; Figure 11 shows a block diagram illustrating an apparatus according to various examples of embodiments; and Figure 12 shows a block diagram illustrating an apparatus according to various examples of embodiments.

DESCRIPTION OF EMBODIMENTS

Basically, for properly establishing and handling a communication between two or more end points (e.g. communication stations or elements or functions, such as terminal devices, user equipments (U Es), or other communication network elements, a database, a server, host etc.), one or more network elements or functions (e.g. virtualized network functions), such as communication network control elements or functions, for example access network elements like access points (APs), radio base stations (BSs), relay stations, eNBs, gNBs etc., and core network elements or functions, for example control nodes, support nodes, service nodes, gateways; user plane functions, access and mobility functions etc., may be involved, which may belong to one communication network system or different communication network systems.

In the following, different exemplifying embodiments will be described using, as an example of a communication network to which examples of embodiments may be applied, a communication network architecture based on 3GPP standards for a communication network, such as a 5G/NR, without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communication networks like 4G and/or LTE (and even 6G) where mobile communication principles are integrated, e.g. Wi-Fi, worldwide interoperability for microwave access (VViMAX), Bluetoothe, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, mobile ad-hoc networks (MANETs), wired access, etc.. Furthermore, without loss of generality, the description of some examples of embodiments is related to a mobile communication network, but principles of the disclosure can be extended and applied to any other type of communication network, such as a wired communication network or datacenter networking.

The following examples and embodiments are to be understood only as illustrative examples. Although the specification may refer to "an", "one", or "some" example(s) or embodiment(s) in several locations, this does not necessarily mean that each such reference is related to the same example(s) or embodiment(s), or that the feature only applies to a single example or embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, terms like "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned; such examples and embodiments may also contain features, structures, units, modules etc. that have not been specifically mentioned.

A basic system architecture of a (tele)communicafion network including a mobile communication system where some examples of embodiments are applicable may include an architecture of one or more communication networks including wireless access network subsystem(s) and core network(s). Such an architecture may include one or more communication network control elements or functions, access network elements, radio access network elements, access service network gateways or base transceiver stations, such as a base station (BS), an access point (AP), a NodeB (NB), an eNB or a gNB, a distributed or a centralized unit (CU), which controls a respective coverage area or cell(s) and with which one or more communication stations such as communication elements or functions, like user devices (e.g. customer devices), mobile devices, or terminal devices, like a UE, or another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a station, an element, a function or an application capable of conducting a communication, such as a UE, an element or function usable in a machine-to-machine communication architecture, or attached as a separate element to such an element, function or application capable of conducting a communication, or the like, are capable to communicate via one or more channels via one or more communication beams for transmitting several types of data in a plurality of access domains. Furthermore, (core) network elements or network functions ((core) network control elements or network functions, (core) network management elements or network functions), such as gateway network elements/functions, mobility management entities, a mobile switching center, servers, databases and the like may be included.

The general functions and interconnections of the described elements and functions, which also depend on the actual network type, are known to those skilled in the art and described in corresponding specifications, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional network elements and signaling links may be employed for a communication to or from an element, function or application, like a communication endpoint, a communication network control element, such as a server, a gateway, a radio network controller, and other elements of the same or other communication networks besides those described in detail herein below.

A communication network architecture as being considered in examples of embodiments may also be able to communicate with other networks, such as a public switched telephone network or the Internet. The communication network may also be able to support the usage of cloud services for virtual network elements or functions thereof, wherein it is to be noted that the virtual network part of the telecommunication network can also be provided by non-cloud resources, e.g. an internal network or the like. It should be appreciated that network elements of an access system, of a core network etc., and/or respective functionalities may be implemented by using any node, host, server, access node or entity etc. being suitable for such a usage. Generally, a network function can be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

Furthermore, a network element, such as communication elements, like a UE, a mobile device, an endpoint terminal, a terminal device, control elements or functions, such as access network elements or functions, like a base station (BS), an eNB/gNB, a radio network controller, a core network control element or function, such as a gateway element, or other network elements or functions, as described herein, (core) network management element or function and any other elements, functions or applications may be implemented by software, e.g. by a computer program product for a computer, and/or by hardware. For executing their respective processing, correspondingly used devices, nodes, functions or network elements may include several means, modules, units, components, etc. (not shown) which are required for control, processing and/or communication/signaling functionality. Such means, modules, units and components may include, for example, one or more processors or processor units including one or more processing portions for executing instructions and/or programs and/or for processing data, storage or memory units or means for storing instructions, programs and/or data, for serving as a work area of the processor or processing portion and the like (e.g. ROM, RAM, EEPROM, and the like), input or interface means for inputting data and instructions by software (e.g. floppy disc, CD-ROM, EEPROM, and the like), a user interface for providing monitor and manipulation possibilities to a user (e.g. a screen, a keyboard and the like), other interface or means for establishing links and/or connections under the control of the processor unit or portion (e.g. wired and wireless interface means, radio interface means including e.g. an antenna unit or the like, means for forming a radio communication part etc.) and the like, wherein respective means forming an interface, such as a radio communication part, can be also located on a remote site (e.g. a radio head or a radio station etc.). It is to be noted that in the present specification processing portions should not be only considered to represent physical portions of one or more processors, but may also be considered as a logical division of the referred processing tasks performed by one or more processors.

It should be appreciated that according to some examples, a so-called "liquid" or flexible network concept may be employed where the operations and functionalities of a network element, a network function, or of another entity of the network, may be performed in different entities or functions, such as in a node, host or server, in a flexible manner. In other words, a "division of labor" between involved network elements, functions or entities may vary case by case.

In the following, for the sake of simplicity reference will be made to elements and concepts of a 5G network, but the concepts of the present invention are not limited to the specific implementation of a 5G network.

With regard to network slicing as introduced above, the following is to be considered.

PDU session suspension with deactivated Data Radio Bearers (DRB)s is published in TR 23.700-41 V0.3.0. A PDU session is an example of data session. In the prior art the PDU session is suspended at Radio Access Network (RAN) node, which then notifies AMF about suspension of PDU session with deactivated DRBs. AMF contacts Session Management Function (SMF), which in turn removes the tunnel. In a second option the tunnel is not removed but data is discarded at RAN node. Once UE returns to a slice then resumption occurs by path switch request from RAN node towards AMF. The latter node contacts SMF and a new tunnel is setup or data is forwarded to the UE from RAN node.

To avoid the UE generating more signalling (PDU session establishment procedure) while requesting the connectivity again when a network slice is supported again in the next cell the UE is moving under coverage, suspension of a PDU session has been introduced (see prior art below) in TR 23.700-41 V0.3.0. However, if PDU sessions have been suspended for S-NSSAls that are subject to NSAC without NSACF getting informed, then it can occur that other UEs that want to use the slice will not have access due to the fact that the maximum number has been reached for the slice while this number inaccurately includes suspended PDU sessions of UEs (that are still counted as active from NSACF's perspective). The NSACF is an example of control network function for controlling slice admission.

It is thus an issue that the suspended PDU sessions of some UEs may block new UEs from getting admitted by the NSACF (when a maximum number for the slice has been reached). This results in under utilization of network resources as UEs with suspended PDU sessions are not currently using them.

According to at least some examples of embodiments, this specification proposes a method to optimize network utilization by indicating to NSACF when UEs have suspended PDU session(s) for a S-NSSAI that is subject to NSAC.

In the following, three embodiments (Embodiment 1, Embodiment 2 and Embodiment 3) are first briefly outlined, wherein a more detailed description is provided further below. However, the present specification is not limited to such three embodiments, but several more embodiments are to be considered, as e.g. outlined further below with regard to Figures 9 to 12.

Embodiment 1:. AMF is notified via a PDU session suspend request for intra-gNB handover scenario or a path switch request for inter-gNB handover scenario, that the UE handovers to a gNB/cell where a slice subject to NSAC is not supported and its PDU sessions are suspended. AMF then triggers a notification for UE count reduction towards NSACF in relation to that slice. AMF notifies SMF via a session modification request that the UE handovers to a gNB/cell where a slice subject to NSAC is not supported and its PDU sessions are suspended. SMF then triggers a notification towards NSACF for PDU session count reduction in relation to that slice.

AM F triggers a notification for UE count increase towards NSACF for UEs of a slice subject to NSAC that can be allowed to resume again the suspended PDU sessions through a path switch request for inter-g NB handover or PDU session resume request for intra-gNB handover scenarios.

If the UE is allowed to resume again its suspended PDU sessions, AMF indicates this to SMF via a session modification request. SMF then triggers a notification for PDU session count increase towards NSACF for UEs of a slice subject to NSAC whose PDU sessions of this slice are allowed to be resumed.

There is an advantage over the prior art that the aforementioned procedures allow the communication among AM F/SM F and NSACF for further use cases than what is allowed by current specification, where the AMF/SMF communication can only occur when a UE performs registration or de-registration procedures or when a PDU session is being established/released.

Further, AMF/SMF indicate to NSACF when UE enters idle mode. NSACF can keep one counter for both connected mode and idle mode UEs. In another option, NSACF can keep two counters, one for connected mode UEs and one for idle mode UEs respectively.

Accordingly, there is an advantage over the prior art that this allows NSACF to obtain a finer granularity overview on the UE status and accordingly perform better resource utilization depending on UE status.

Embodiment 2: AMF/SMF ask NSACF to indicate when the maximum number or percentage of maximum number of UEs/PDU sessions has been reached at NSACF for a specific slice. This allows AM F/SMF to directly release UEs/PDU sessions if quota has been reached at NSACF and save signaling overhead. The NSACF indicates to AMF/SMF when the maximum number or percentage of the maximum number of UEs/PDU sessions has been reached at NSACF for a specific slice. NSACF also updates AMF/SMF in case that quota becomes again available for that slice.

Accordingly, there is an advantage over the prior art that in that in this case, unnecessary UE/PDU session releases are avoided.

Embodiment 3: AMF/SMF register with NSACF to receive a quota for UEs/PDU sessions that they can allow to resume without notifying NSACF.

Hence, there is the advantage that AMF/SMF save signaling communication overhead when allowing UEs to resume PDU sessions after being suspended.

Further, AMF/SMF update the status of the respective quota towards NSACF when suspending or allowing to resume UEs/PDU sessions in order to let NSACF know the current status. Based on the obtained overview, NSACF can dynamically adjust the quota 35 towards AM Fs/SM Fs.

Accordingly, there is an advantage over the prior art that such dynamical adjusting may lead to better/improved resource utilization.

In the following, the above-outlined three embodiments are described in more detail.

Referring now to Figure 2 (consisting of parts 1/2 and 2/2), Figure 2 shows a message sequence chart for Embodiment 1 for UE count.

* Steps 1-2: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gNB2 240) where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF denotes that maximum UE count not yet reached.

o UE1 220 handovers to gNB2 240 ce112 where slice B is no longer supported and its PDU sessions are suspended.

* Steps 3-4: AMF 250 notifies NSACF 260 to reduce the UE counter for slice B. * Step 5: Another UE2 210 joins the network at gNB1 230 for slice B and the maximum number of UEs per slice B still not reached at NSACF 260, which involves interaction among AMF 250 and NSACF 260 as per current specification.

* Step 6: UE1 220 handovers back to gNB1 230 celll where slice B is supported but PDU sessions are suspended.

* Steps 7-9: AMF 250 triggers a notification towards NSACF 260 for increasing the UE counter for slice B due to a pass switch request.

* Steps 10-13: Depending on the availability of a UE count on NSACF 260 with respect to slice B, AMF 250 either allows UE1 220 to resume PDU sessions again if the maximum number of UEs per slice B has not been reached at NSACF 260 or releases the UE 220 otherwise * Steps 14-15: UE2 210 enters idle mode and AMF 250 triggers a notification towards NSACF 260 to increase the UE counter * Step 16: NSACF 260 increases the counter for UEs.

Embodiment 1: When UE (e.g. UE1 220) handovers to a gNB/cell (e.g. gNB2 240) where a slice that is subject to slice admission control is not supported and for which the UE had previously established PDU sessions and for such UE those PDU sessions are suspended (e.g. due to no support in the new handed over cell), the AMF 250 triggers a notification towards NSACF 260 to indicate a reduction on the UE count/UE counter for the respective slice.

In current specification according to the prior art, the communication between AMF 250 and NSACF 260 is only possible when an UE registers or leaves the network.

According to the present specification, however, there is the advantage that once the UE (e.g. UE1 220) handovers back to the initial gNB/cell (e.g. gN B1 230) or to any other gNB/cell which supports again the slice and can resume the suspended PDU sessions for the UE of that slice, then the AMF 250 triggers a notification towards NSACF 260 to increase the counter. In an inter-gNB scenario, the trigger comes from a path switch request and is depicted in the figures appended to the present specification. It shall be noted that for intra-cell gNB scenario a different message than Path Switch Request shall be used. For instance, a message may be named "PDU session resume request".

If NSACF 260 replies back to AMF 250 that the maximum number of UEs for that particular slice has not been reached, then AMF 250 allows the UE (e.g. UE1 220) to resume its suspended PDU sessions again, otherwise it releases the UE. If the UE (e.g. UE2 210) enters in idle mode in a gNB/cell (e.g. gNB2 240) for a slice that is subject to slice admission control and for which the UE (e.g. UE2 210) had previously established PDU sessions and for that UE those PDU sessions are suspended (e.g. due to no support in the cell), and therefore the AMF 250 had triggered a notification towards NSACF 260 to indicate a reduction on the UE count for the respective slice when the UE was in connected mode, then the AMF 250 notifies the NSACF 260 to increase the UE counter as the PDU session is available for Mobile Terminated (MT) services as the location of the UE becomes uncertain within the TA if this TA is in a Radio Area (RA) including TAs where the same slice is supported. In one option, NSACF 260 only keeps one counter for both idle and connected mode UEs and updates the counter. In another option, NSACF 260 keeps two separate counters, one for connected mode UEs and one for idle mode UEs and consequently increases the counter accordingly. This allows the NSACF 260 to obtain a finer granularity overview on the UE status and accordingly perform better/improved resource utilization depending on UE status.

Referring now to Figure 3 (consisting of parts 1/2 and 2/2), Figure 3 shows a message sequence chart for Embodiment 1 for PDU session count.

* Steps 1-2: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gN B2 240), where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF 260 denotes that maximum UE count not yet reached.

o UE1 220 handovers to gNB2 240 ce112 where slice B is no longer supported and its PDU sessions are suspended.

* Steps 3-4: SMF 310 is notified that PDU sessions of UE1 220 are suspended and indicates to NSACF 260 to reduce the PDU session counter for slice B. * Step 5: Another UE2 220 joins the network at gNB1 230 for slice B and the maximum number of UEs per slice B still not reached at NSACF 260, which involves interaction among AMF 250 and NSACF 260 as per current specification.

* Steps 6-7: UE1 220 handovers back to gNB1 230 ce111 where slice B is supported but PDU sessions are suspended.

Scenario 1: * Steps 8-9: UE1 220 is allowed to resume its suspended PDU sessions, AMF 250 then sends a session modification request to SMF 310.

* Steps 10-11: SMF 310 triggers a notification towards NSACF 260 for increasing the PDU session counter for slice B due to a session modification request. This may be done sequentially for each PDU session or for a group of PDU sessions altogether.

* Steps 12-15: Depending on the availability of PDU session count on the NSACF 260 with respect to slice B, SMF 310 either resumes PDU sessions of UE1 220 back, if the maximum number of PDU sessions per slice B has not been reached at NSACF 260, or releases the PDU sessions otherwise.

Scenario 2: * Steps 16-17: UE1 220 is not allowed to resume its suspended PDU sessions, AMF 250 then sends a session modification request to SMF 310.

* Steps 18: SMF 310 releases the PDU sessions of UE1 220.

* Steps 19-20: UE2 210 enters idle mode and SMF 310 triggers a notification towards NSACF 260 to increase PDU session counter for slice B. * Step 21: NSACF 260 increases the counter for PDU sessions.

Embodiment 1: Mien UE (e.g. UE1 220) handovers to a gNB/cell where a slice that is subject to slice admission control is not supported and for which the UE had previously established PDU sessions and for such UE those PDU sessions are suspended (e.g. due to no support in the new handed over cell), SMF 310 is informed that PDU sessions are suspended for that UE and triggers a notification towards NSACF 260 to indicate a reduction on the PDU session count for the respective slice. This may be done sequentially for each PDU session or for a group of PDU sessions altogether. Once the UE (e.g. UE1 220) handovers back to the initial gNB/cell (e.g. gNB1 230) or to any other gNB/cell, which supports again the slice, and it is allowed to resume the suspended PDU sessions for that slice (Scenario 1), then AMF 250 indicates this to SMF 310. AMF 250 contacts SMF 310 via a session modification request, which then triggers a notification towards NSACF 260 to increase the counter. Otherwise, if the UE (e.g. UE1 220) is not allowed to resume its PDU sessions again (Scenario 2), then SMF 310 releases the PDU sessions of the UE.

If NSACF 260 replies back to SMF 310 that the maximum number of PDU sessions for that particular slice has not been reached, then SMF 310 resumes the PDU session(s) of that UE (e.g. UE1 220) again, otherwise it releases the PDU session(s). This may be done sequentially for each PDU session or for a group of PDU sessions altogether. If the UE (e.g. UE2 210) enters in idle mode in a gNB/cell (e.g. gNB2 240) for a slice that is subject to slice admission control and for which the UE had previously established PDU sessions and for such UE those PDU sessions are suspended (e.g. due to no support in the cell), and therefore the SMF 310 had triggered a notification towards NSACF 260 to indicate a reduction on the PDU session count for the respective slice when the UE (e.g. UE1 210) was in connected mode, then the SMF 310 can update the NSACF 260 for PDU sessions of the UE, when the N3 tunnel is released as the UE enters idle state (or the N3 tunnel is restored as UE enters connected mode). In one option, NSACF 260 only keeps one counter for both idle and connected mode UEs and updates the PDU session counter. In another option, NSACF 260 keeps two separate counters, one for connected mode UEs and one for idle mode UEs and consequently updates the PDU session counter accordingly.

Such differentiation among two counters allows NSACF 260 to obtain a finer granularity overview on the UE status and accordingly to perform better/increased resource utilization depending on UE status.

Referring now to Figure 4, Figure 4 shows interactions among AMF 250 and SMF 310. I.e., for clarifying the interaction among the AMF 250 and the SMF 310, Figure 4 is used and explained as follows.

* Steps 1-2: AMF 250 detects that a UE (e.g. UE1 220 and/or UE2 210 with reference to Figures 2 and 3) has suspended PDU sessions for a slice (e.g. slice B with reference to Figures 2 and 3) and updates the counter for that UE towards NSACF (e.g. NSACF 260 with reference to Figures 2 and 3).

* Step 3: AMF 250 contacts SMF 310 to indicate that a UE has suspended PDU sessions for a particular slice.

* Steps 4-5: SMF 310 detects that UE has suspended PDU sessions for a slice and updates the PDU session counter for that slice towards NSACF.

Case 1: * Steps 6-7: Wien a UE is requesting to resume its PDU sessions and AMF 250 detects that the UE is allowed to resume the PDU sessions through interaction with NSACF, it notifies the SMF 310.

* Step 8: SMF 310 detects that UE is allowed to resume its suspended PDU sessions and therefore it checks with NSACF, whether available quota exist for the PDU sessions of that slice.

Case 2: * Steps 6-7: When a UE is requesting to resume its PDU sessions and AMF 250 detects that the UE is not allowed to resume the PDU sessions through interaction with NSACF, it notifies the SMF 310.

* Step 8: SMF 310 detects that UE is not allowed to resume its suspended PDU sessions and therefore releases the PDU sessions.

Referring now to Figure 5 (consisting of parts 1/2 and 2/2), Figure 5 shows a message sequence chart for Embodiment 2 for UE count.

* Steps 1-2: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gN B2 240), where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF 260 denotes that maximum UE count not yet reached.

o UE1 220 handovers to gNB2 240 ce112 where slice B is no longer supported and its PDU sessions are suspended.

* Steps 3-4: AMF 250 notifies NSACF 260 to reduce the UE counter for slice B and asks NSACF 260 to indicate, when the maximum number of UEs or a percentage of the maximum number of U Es has been reached at NSACF 260.

* Step 5: Another UE2 210 joins the network at gNB1 230 for slice B and the maximum number of UEs per slice B still not reached at NSACF 260, which involves interaction among AMF 250 and NSACF 260 as per current specification.

* Steps 6-7: NSACF 260 reaches maximum number of UEs per slice B and indicates it to AMF 250.

* Step 8: AMF 250 does not release the UE (e.g. UE1 220) directly, but waits until it rejoins, since maybe another update (with regard to the maximum number being reached) can arrive in the meantime from NSACF 260, e.g. indicating that the maximum number is no longer reached.

Case 1: * Steps 9-10: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended.

* Step 11: AMF 250 releases UE1 220.

Case 2: * Step 12-13: NSACF 260 identifies that quota is again available and sends a new update to AMF 250, that the maximum number of UEs per slice B is no longer reached.

* Steps 14-15: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended.

* Steps 16-18: AMF 250 allows UE1 220 to resume its suspended PDU sessions and notifies NSACF 260 to increase UE counter for slice B. Embodiment 2: When UE (e.g. UE1 220) handovers to a gNB/cell (e.g. gNB2 240), where a slice that is subject to slice admission control is not supported and for which the UE had previously established PDU sessions and for such UE those PDU sessions are suspended (e.g. due to no support in the new handed over cell), the AMF 250 triggers a notification towards NSACF 260 to indicate a reduction on the UE count/UE counter for the respective slice and simultaneously request NSACF 260 to indicate to AMF 250, when the maximum number of UEs or a percentage of the maximum number of UEs has been reached.

That way, once the UE handovers back to the initial gNB (e.g. gNB1 230) that has suspended PDU sessions for that slice and/or to any gNB/cell (e.g. a third gNB (not illustrated)) supporting again the slice, then the AMF 250, if it has received indication from NSACF 260 that the maximum number of UEs or a percentage of the maximum numbers of UEs has been reached, releases the UE without further signalling towards the NSACF 260.

Hence, there is the advantage of avoiding unnecessary signalling.

The same applies for any other UE trying to access the slice. The AMF 250 does not release the UE directly after receiving the indication from NSACF 260, rather it waits until the UE (e.g. UE1 220) handovers back to the initial gNB (e.g. gNB1 230) or the new UE trying to access the slice pops up, since in the meantime maybe another update from NSACF 260 can be received, which indicates that there are again resources available for that slice.

In that regard, there is the advantage that unnecessary UE releases are avoided.

Once the UE (e.g. UE1 220) handovers back to the initial gNB (e.g. gNB1 230) that has suspended PDU sessions for that slice, then the AMF 250, if it has not received indication from NSACF 260 that the maximum number of UEs or a percentage of the maximum numbers of UEs has been reached, signals the NSACF 260 to increment the UE count and allows the UE to resume its suspended PDU sessions again.

Referring now to Figure 6 (consisting of parts 1/3, 2/3 and 3/3), Figure 6 shows a message sequence chart for Embodiment 2 for PDU session count.

* Steps 1-2: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gNB2 240), where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF 260 denotes that maximum UE count not yet reached.

o UE1 220 handovers to gNB2 240 ce112, where slice B is no longer supported and its PDU sessions are suspended.

* Steps 3-4: SMF 310 is notified that PDU sessions of UE1 220 are suspended and indicates to NSACF 260 to reduce the PDU session counter for slice B and asks NSACF 260 to indicate, when the maximum number of PDU sessions or a percentage of the maximum number of PDU sessions has been reached at NSACF 260.

* Step 5: Another UE2 210 joins the network at gNB1 230 for slice B and the maximum number of UEs per slice B still not reached at NSACF 260, which involves interaction among AMF 250 and NSACF 260 as per current specification.

* Steps 6-7: NSACF 260 reaches maximum number of PDU sessions per slice B and indicates this to SMF 310.

* Step 8: SMF 310 does not release the PDU sessions of UE1 220 directly, but waits until UE1 220 re-joins, since maybe another update can arrive in the meantime from the NSACF 260 with regard to whether or not the maximum number being reached.

Case 1: * Steps 9-12: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended, UE1 220 is allowed to resume its suspended PDU sessions and AMF 250 notifies SMF 310 via session modification request, accordingly.

* Step 13: SMF 310 releases PDU sessions of UE1 220. Case 2: * Step 14-15: NSACF 260 sends a new update to SMF 310, indicating that the maximum number of PDU sessions per slice B is no longer reached.

* Steps 16-19: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended, UE1 220 is allowed to resume its suspended PDU sessions and AMF 250 notifies SMF 310 via session modification request, accordingly.

* Steps 20-22: SMF 310 accepts PDU sessions of UE1 220 again and notifies NSACF 260 to increase PDU session counter for slice B. Case 3: * Steps 23-26: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended, UE1 220 is not allowed to resume its suspended PDU sessions and AMF 250 notifies SMF 310 via session modification request, accordingly.

* Step 27: SMF 310 releases PDU sessions of UE1 220.

Embodiment 2: When UE (e.g. UE1 220) handovers to a gNB/cell (e.g. gNB2 240), where a slice that is subject to slice admission control is not supported and for which the UE had previously established PDU sessions and for such UE those PDU sessions are suspended (e.g. due to no support in the new handed over cell), SMF 310 is informed that PDU sessions are suspended for that UE and triggers a notification towards NSACF 260 to indicate a reduction on the PDU session count for the respective slice and simultaneously requests NSACF 260 to indicate to SMF 310, when the maximum number of PDU sessions or a percentage of the maximum number of PDU sessions has been reached.

That way, once the UE (e.g. UE1 220) handovers back to the initial gNB/cell (e.g. gNB1 230), that has suspended PDU sessions for that slice and/or to any gNB/cell (e.g. a third gNB (not illustrated)) supporting again the slice, then the SMF 310, if it has received indication from NSACF 260 that the maximum number of PDU sessions or a percentage of the maximum number of PDU sessions has been reached, releases the PDU sessions without further signalling towards the NSACF 260. The SMF 310 does not release the PDU sessions of that UE directly after receiving the indication from NSACF, rather it waits until the UE handovers back to the initial gNB or the new UE trying to access the slice pops up, since in the meantime maybe another update from NSACF 260 may be received, which indicates that there are again resources available for that slice.

In that regard, there is the advantage that unnecessary PDU session releases are avoided.

Once the UE (e.g. UE1 220) handovers back to the initial gNB (e.g. gNB1 230) that has suspended PDU sessions for that slice and the UE is allowed to resume its suspended PDU sessions, AMF 250 notifies SMF 310 via session modification request, accordingly. If SMF 310 has not received indication from NSACF 260 that the maximum number of PDU sessions or a percentage of the maximum numbers of PDU sessions has been reached, SMF 310 signals the NSACF 260 to increment the PDU sessions count per slice and activates the UE, otherwise it releases the PDU sessions. If the UE is not allowed to resume its suspended PDU sessions, SMF 310 releases the PDU sessions of the UE.

Referring now to Figure 7 (consisting of part 1/2 and 2/2), Figure 7 shows a 25 messages sequence chart for Embodiment 3 for UE count.

* Steps 1-2: AMF 250 subscribes to the quota handling method for suspended UEs and it receives a specific amount of UE quota from NSACF 260 that can use for suspended UEs without sending a notification to the NSACF 260, wherein sending such notification may comprise asking NSACF 260 for permission.

* Steps 3-4: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gNB2 240) where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF 260 denotes that maximum UE count not yet reached. * * * * * * *

o NSACF 260 is updated and AMF quota is not used. The AMF quota may be understood to represent the available (e.g. remaining) quota prevailing at the AMF.

o UE1 220 handovers to gNB2 240 ce112, where slice B is no longer supported and its PDU sessions are suspended.

Step 5: AMF 250 indicates to NSACF 260 to reduce UE counter for slice B and updates current (i.e. prevailing) AMF quota towards NSACF 260.

o The update is needed for UEs that are not previously in suspended mode, but have moved from slice enabled mode to suspended mode. So they should not be counted by the NSACF quota but the AMF quota. The NSACF quota may be understood to represent the available quota prevailing at the NSACF (i.e. the quota (e.g. number of U Es) available until a predetermined threshold value (e.g. the maximum number of U Es possible) is reached).

Step 6: Another UE2 210 joins the network at gN B1 230 for slice B and the maximum number of U Es per slice B still not reached at NSACF 260, which involves interaction among AMF 250 and NSACF 260 as per current specification.

Steps 7-8: UE1 220 handovers back to gN B1 230 cent where slice B is supported but PDU sessions are suspended.

o UE1 220 is a previously suspended UE at step 5. Hence, there is the advantage that there is no need to inform the NSACF 260 and it can be made use of the AMF quota to handle suspended UEs.

Steps 9-10: AMF 250 reduces its current quota counter and notifies NSACF 260 about its counter value and increases UE counter for slice B. Step 11-12: UE2 210 handovers to gNB2 240 ce112, where slice B is no longer supported and its PDU sessions are suspended. AMF 250 indicates to NSACF 260 to reduce UE counter for slice B and updates current AMF quota towards NSACF 260.

o The update is needed for UEs that are not previously in suspended mode, but have moved from slice enabled mode to suspended mode. So they should not be counted by the NSACF quota but the AMF quota.

Steps 13-14: UE2 210 handovers back to gN B1 230 ce111, where slice B is supported but PDU sessions are suspended.

Step 15: AMF 250 does not have any more quota available. Therefore, a process similar to one of Embodiment 1 or Embodiment 2 may be used for proceeding further.

Embodiment 3: In this embodiment, the AMF 250 subscribes to the NSACF 260 for a quota of U Es, which are allowed to resume its PDU sessions without sending a notification to NSACF 260, wherein sending such notification may comprise asking NSACF 260 for permission. This is a dynamic quota, which the NSACF 260 updates when needed among multiple AMFs (comprising AMF 250). When UE (e.g. UE1 220) handovers to a gNB/cell (e.g. gNB2 240), where a slice that is subject to slice admission control is not supported and for which the UE may have previously established PDU sessions, which had been suspended and are allowed to be resumed and/or for new UE requests for a PDU session of this slice, the AMF 250 accepts the UE, if quota is available (e.g. if there is remaining quota), decreases the available quota by one, may indicate a UE count increase to NSACF 260 and may notify NSACF 260 about the quota. Otherwise, if there is no quota available, the AMF 250 may e.g. proceed as outlined with reference to Embodiment 1 or Embodiment 2 With this method as outlined with reference to Embodiment 3, there is the advantage that signalling can be saved between the AMF 250 and the NSACF 260, in cases where the AMF 250 first has to wait for a reply from the NSACF 260 about whether or not the AMF 250 can allow the UE to resume its suspended PDU sessions. In contrast thereto, by use of such method as outlined with reference to Embodiment 3, by using quota(s), the AMF 250 may allow an UE certainly to resume its suspended PDU sessions, if (e.g. remaining) quota is available.

Referring now to Figure 8 (consisting of parts 1/2 and 2/2), Figure 8 shows a message sequence chart for Embodiment 3 for PDU session count.

* Steps 1-2: SMF 310 subscribes to a quota handling method for suspended PDU sessions and it receives a specific amount of PDU sessions quota from NSACF 260, wherein the received quota can use for suspended PDU sessions without sending a notification to NSACF 260, wherein sending such notification may comprise asking the NSACF 260 for permission.

* Steps 3-4: A UE (e.g. UE1 220) joins a network slice at gNB1 230, which is subject to NSAC, where available UE count is detected from NSACF 260, but handovers to a new gNB (e.g. gNB2 240), where the S-NSSAI is not available anymore.

o UE1 220 joins slice B in gNB1 230 cell 1 subject to NSAC, where NSACF 260 denotes that maximum UE count not yet reached.

o UE1 220 handovers to gNB2 240 ce112, where slice B is no longer supported and its PDU sessions are suspended.

* Step 5: SMF 310 indicates to NSACF 260 to reduce PDU session counter for slice B and updates current SMF quota towards NSACF 260. The SMF quota may be understood to represent the available (e.g. remaining) quota prevailing at the SMF.

* Step 6: Another UE2 210 joins the network at gNB1 230 for slice B and the maximum number of UEs per slice B still not reached at NSACF 260.

* Steps 7-9: UE1 220 handovers back to gNB1 230 cent where slice B is supported but PDU sessions are suspended.

* Steps 10-11: SMF 310 reduces its current quota counter, notifies NSACF 260 about its reduced quota counter value and increases PDU session counter for slice B. * Steps 12-13: UE2 210 handovers to gNB2 240 ce112, where slice B is no longer supported and the PDU sessions of the UE2 210 are suspended. SMF 310 indicates to NSACF 260 to reduce PDU session counter for slice B and updates current (i.e. prevailing) SMF quota towards NSACF 260.

* Steps 14-16: UE2 210 handovers back to ce111, where slice B is supported but PDU sessions are suspended.

* Step 17: SMF 310 does not have any more available quota. Therefore, for proceeding further, the SMF 310 may e.g. apply one of such methods as outlined with regard to Embodiment 1 or Embodiment 2.

Embodiment 3: In this embodiment, SMF 310 subscribes to NSACF for a quota of PDU sessions that can resume a PDU session of the slice without sending a notification to NSACF 260, wherein such sending may comprise asking NSACF 260 for permission. This is a dynamic quota, which the NSACF 260 may update when/as needed among multiple SMFs (comprising the SMF 310). When UE (e.g. UE1 220) handovers to a gNB/cell (e.g. gNB2 240), where a slice that is subject to slice admission control is not supported and for which the UE may have previously established PDU sessions, which had been suspended and are resumed and/or for new UE requests for a PDU session of this slice, the SMF 310 accepts the PDU session, if quota is available (e.g. if there is remaining quota), decreases available (i.e. prevailing) (PDU) quota by one or more (depending on PDU sessions), may indicate a PDU session count increase to the NSACF 260 and may notify the NSACF 260 about the quota. Otherwise, if there is no quota available, the SMF 310 may e.g. apply one of such methods as outlined with reference to Embodiment 1 or Embodiment 2.

With this method, there is the advantage that signalling can be saved between the SMF 310 and the NSACF 260, in cases where the SMF 310 first has to wait for a reply from the NSACF 260, about whether or not the SMF 310 can resume the PDU sessions of the UE. In contrast thereto, by applying such method as outlined with reference to Embodiment 4, by using quota(s), the SMF 310 can resume the PDU sessions certainly if (e.g. remaining) quota is available.

In the following, further examples of embodiments are described in relation to the above described methods and/or apparatuses.

Referring now to Figure 9, there is shown a flowchart illustrating steps corresponding to a method according to various examples of embodiments. With regard to the steps illustrated in Figure 9, the steps are illustrated in relation to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established PDU sessions for a network slice, to a second access network element or function, at which the established PDU sessions are suspended or at which the network slice is not supported.

In particular, according to Figure 9, in 5910, the method comprises, receiving a handover message relative to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established PDU sessions for a network slice, to a second access network element or function; determining, based on the reception of the handover message, that the established PDU sessions are suspended or that the network slice is not supported at the second access network element or function; based on the determining transmitting, at a network management entity or function associated with at least the first access network element or function and/or the second access network element or function, a first notification towards a control network function for controlling network slice admission, wherein the first notification comprises information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice.

An example of control network function could be, for instance, a Network Slice Admission Control Function (NSACF). An example of data session could be, for instance, a Packet Data Unit, PDU, session. In the following sometimes reference will be made to the NSACF and PDU session for the sake of simplicity, but it should be clear that the concepts described below have a more general validity and are not limited to the NSACF and PDU session.

It shall be noted that the information comprised in the first notification may cause the network control function to reduce (i.e. the network control function reduces the respective counter) the at least one of endpoint terminal counter and data session counter. However, the information comprised in the first notification may also be understood to (alternatively) indicate towards the network control function that the at least one of endpoint terminal counter and data session counter has already been reduced by the network management entity or function. Additionally, the expressions "an endpoint terminal" and "a network slice" may also be understood as meaning "at least one endpoint terminal" and "at least one network slice", respectively. I.e., the method may be applied for several endpoint terminals simultaneously/at the same time, wherein the handover may comprise that e.g. a group of endpoint terminals is handovered. Moreover, the method may be applied for several network slices simultaneously/at the same time.

It shall further be noted that the endpoint terminal may represent such user equipment UE1 220 and/or UE2 210 as outlined above with reference to Figures 2 to 8. Moreover, such first and second access network elements or functions may represent such nodes gNB1 230 and gNB2 240 as outlined above with reference to Figures 2 to 8.

Furthermore, the network control function may be such NSACF 260 as outlined above with reference to Figures 2 to 8. Further, the network slice may represent such network slice B as outlined above with reference to Figures 2 to 8. Still further, the endpoint terminal counter and the data session counter may represent such UE counter and data session counter as outlined above with reference to Figures 2 to 8, respectively. In this regard, the endpoint terminal counter may be understood to represent a number of endpoint terminals already/currently using the network slice and the data session counter may be understood to represent a number of data sessions already/currently using the network slice. The suspended data sessions of the endpoint terminal may represent such suspended data sessions of the UE as outlined above with reference to Figures 2 to 8. Additionally, Step 5910 may correspond to at least part of e.g. such Steps 3 and 4 as outlined above with reference to Figures 2, 3, 5 and 6 as well as of e.g. such Step 5 as outlined above with reference to Figures 7 and 8. Accordingly, such network management entity or function may comprise at least one of such AM F 250 and SMF 310 as outlined above with reference to Figures 2 to 8.

Additionally, according to various examples of embodiments, the reduction of the at least one of endpoint terminal counter and data session counter may comprise a reduction of the at least one of -endpoint terminal counter by an amount of endpoint terminals participating in the handover, the amount of endpoint terminals comprising at least the endpoint terminal, and -data session counter by an amount of the suspended data sessions.

Furthermore, according to various examples of embodiments, the method may include determining that the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the method may further comprise transmitting, based on the determining, a second notification towards the control network function, wherein the second notification comprises information indicative of an increase of at least one of the endpoint terminal counter and the data session counter.

It shall be noted that the information comprised in the second notification may cause the NSACF to increase (i.e. the NSACF increases the respective counter) the at least one of endpoint terminal counter and PDU session counter. However, the information comprised in the second notification may also be understood to (alternatively) indicate towards the NSACF that the at least one of endpoint terminal counter and PDU session counter has already been increased by the network management entity or function.

It shall further be noted that such transmitting of the second notification may correspond to at least part of e.g. such Steps 8 and 9 as well as 10 and 11 as outlined above with reference to Figures 2 and 3, respectively.

Additionally, according to various examples of embodiments, the method may further comprise, receiving a response to the second notification indicating whether or not a predetermined threshold value related to the network slice is reached; and based on the received response, determining whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.

It shall be noted that such receiving of the response may correspond to at least part of e.g. such Steps 10 and 12 as well as 12 and 14 as outlined above with reference to Figures 2 and 3, respectively. Further, such determining may correspond to at least part of e.g. such Steps 11 and 13 as well as 13 and 15 as outlined above with reference to Figures 2 and 3, respectively.

Optionally, according to at least some examples of embodiments, the predetermined threshold value may be at least one of -a first predetermined threshold value representing a maximum number of endpoint terminals allowable for the network slice or a percentage of the maximum number of endpoint terminals, and -a second predetermined threshold value representing a maximum number of data sessions allowable for the network slice or a percentage of the maximum number of data sessions.

Additionally, the method may further comprise: -if the first predetermined threshold value is not reached, allowing the endpoint terminal to resume the suspended data sessions; -if the first predetermined threshold value is reached, releasing the endpoint terminal and/or releasing the suspended data sessions of the endpoint terminal; -if the second predetermined threshold value is not reached, resuming the suspended data sessions of the endpoint terminal; and -if the second predetermined threshold value is reached, releasing at least one suspended data session of the suspended data sessions of the endpoint terminal.

It shall be noted that such first and second predetermined threshold values may e.g. represent such threshold values as outlined e.g. with regard to Figures 2 and 3, respectively.

Accordingly, such situation where the first predetermined threshold value is not reached may correspond to at least part of such Case 1 as illustrated with regard to Figure 2. Further, such situation where the first predetermined threshold value is reached may correspond to at least part of such Case 2 as illustrated with regard to Figure 2. In addition, such situation where the second predetermined threshold value is not reached may correspond to at least part of such Case 2 as illustrated with regard to Figure 3. Moreover, such situation where the second predetermined threshold value is reached may correspond to at least part of such Case 1 as illustrated with regard to Figure 3.

Further, according to various examples of embodiments, the transmitting of the second notification may comprise at least one of sequentially transmitting a notification for a single data session out of the suspended data sessions, and transmitting a notification to a group of data sessions out of the suspended data sessions.

It shall be noted that such further specified transmitting may e.g. correspond to at least part of such Step 11 as illustrated with regard to Figure 3.

Moreover, according to at least some examples of embodiments, based on determining at the network management entity or function that the endpoint terminal enters idle mode at the second access network element or function, the method may further comprise transmitting a third notification towards the network control function to notify the network control function about the endpoint terminal entering idle mode.

It shall be noted that such transmitting of the third notification may e.g. correspond to at least part of such Steps 14 and 15 as well as 19 and 20 as illustrated with regard to Figures 2 and 3, respectively.

Furthermore, according to various examples of embodiments, the third notification may comprise an indication to increase the data session counter and the endpoint terminal counter.

It shall be noted that such further specification of the third notification may e.g. correspond to at least part of such Steps 14 and 15 as well as 19 and 20 as illustrated with regard to Figures 2 and 3, respectively.

Additionally, according to various examples of embodiments, the method may further comprise requesting the network control function for an indication about whether or not at least one of the first predetermined threshold value and the second predetermined threshold value is reached; and based on a reception of the requested indication, determining whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.

It shall be noted that such requesting may e.g. correspond to at least part of e.g. such Step 4 as illustrated with regard to Figures 5 and 6, respectively. Further, such determining may e.g. correspond to at least part of e.g. such Steps 11 and 18 as well as 13 and 22 as illustrated with regard to Figures 5 and 6, respectively.

Optionally, according to at least some examples of embodiments, based on the reception of the requested indication, the method may further comprise: i) if the first predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmitting a fourth notification towards the network control function to increase the endpoint terminal counter; and allowing the endpoint terminal to resume the suspended data sessions; ii) if the first predetermined threshold value is reached, refraining from releasing the endpoint terminal and waiting until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitoring for an update with regard to whether or not the first predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determining whether or not to release the endpoint terminal based on a result obtained from the monitoring for the update; iii) if the second predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmitting a fifth notification towards the network control function to increase the data sessions counter; and resuming the suspended data sessions of the endpoint terminal; and iv) if the second predetermined threshold value is reached, refraining from releasing the suspended data sessions and waiting until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitoring for an update with regard to whether or not the second predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determining whether or not to release the suspended data sessions of the endpoint terminal based on a result obtained from the monitoring for the update.

It shall be noted that such situation i) may e.g. correspond to at least part of e.g. such Case 2 as illustrated with regard to Figures 5. In doing so, the transmitting of the fourth notification may correspond to at least part of e.g. such Steps 16 and 17, and the allowing to resume may correspond to at least part of e.g. such Step 18. Further, such situation ii) may e.g. correspond to at least part of e.g. such Case 1 as illustrated with regard to Figures 5. In doing so, the refraining, waiting and monitoring may correspond to at least part of e.g. such Step 8, and the determining whether or not to release may correspond to at least part of e.g. such Step 11. Moreover, such situation iii) may e.g. correspond to at least part of e.g. such Case 2 as illustrated with regard to Figures 6. In doing so, the transmitting of the fifth notification may correspond to at least part of e.g. such Steps 20 and 21, and the accepting of the suspended PDU sessions may correspond to at least part of e.g. such Step 22. Further, such situation iv) may e.g. correspond to at least part of e.g. such Case 1 as illustrated with regard to Figures 6. In doing so, the refraining, waiting and monitoring may correspond to at least part of e.g. such Step 8, and the determining whether or not to release may correspond to at least part of e.g. such Step 13.

Further, according to various examples of embodiments, wherein if the endpoint terminal handovers from the second access network element or function to another access network element or function, the method may further comprise determining whether or not the endpoint terminal is allowed to resume the suspended data sessions; and, if the endpoint terminal is not allowed to resume the suspended data sessions, releasing the suspended data sessions of the endpoint terminal.

It shall be noted that such determining may e.g. correspond to at least part of e.g. such Scenario 2 as illustrated with regard to Figure 3 as well as of e.g. such Case 3 as illustrated with regard to Figure 6.

Moreover, according to at least some examples of embodiments, the method of any of the preceding embodiments may further comprise subscribing at the network control function for a quota handling for at least one of suspended endpoint terminals and suspended data sessions; and based on the subscribing, receiving at least one of -a predetermined amount of endpoint terminal quota to be used for resuming suspended endpoint terminals without sending a notification to the network control function, and -a predetermined amount of data session quota to be used for resuming suspended data sessions without sending a notification to the network control function.

In addition, the method may further comprise adapting the at least one of -received predetermined amount of endpoint terminal remaining quota according to the reduction of the terminal endpoint counter indicated in the first notification, and -received predetermined amount of data session remaining quota according to the reduction of the data session counter indicated in the first notification.

It shall be noted that adapting such respective remaining quota according to an indicated reduction of the terminal endpoint counter/ the data session counter may be understood as increasing the respective remaining quota, accordingly.

It shall further be noted that further to the subscribing and the receiving based on the subscribing, the method may further comprise reducing the at least one of endpoint terminal counter and PDU session counter according to the reduction indicated in the first notification; and/or updating towards the NSACF the at least one of -adapted predetermined amount of endpoint terminal remaining quota as representing a prevailing amount of endpoint terminal remaining quota prevailing at the network management entity or function, and -adapted predetermined amount of PDU session remaining quota as representing a prevailing amount of PDU session remaining quota prevailing at the network management entity or function.

It shall still further be noted that such subscribing may e.g. correspond to at least part of e.g. such Step 1 as illustrated with regard to Figures 7 and 8, wherein such receiving may e.g. correspond to at least part of e.g. such step 2 as illustrated with regard to Figures 7 and 8.

Furthermore, according to various examples of embodiments, if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, the method of any of the preceding embodiments may further comprise allowing the endpoint terminal to resume its suspended data sessions for the network slice; and, based on the allowing, adapting the at least one of -amount of endpoint terminal remaining quota prevailing at the network management entity or function by reducing the amount of endpoint terminal remaining quota by one, and -amount of data session remaining quota prevailing at the network management entity or function by reducing the amount of data session remaining quota according to an amount of the suspended data sessions of the endpoint terminal.

It shall be noted that further to the accepting and the adapting based on the accepting, the method may further comprise increasing the at least one of endpoint terminal counter and PDU session counter according to the increase indicated in the second notification; and/or updating towards the NSACF the at least one of -adapted amount of endpoint terminal remaining quota prevailing at the network management entity or function, and -adapted amount of PDU session remaining quota prevailing at the network management entity or function.

It shall further be noted that such adjusting process may e.g. correspond to at least part of e.g. such Steps 9 and 10 as well as 10 and 11 as illustrated with regard to Figures 7 and 8.

Additionally, according to various examples of embodiments, if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, the method of any of the preceding embodiments may further comprise determining whether or not a remaining quota is available from the at least one of received amount of endpoint terminal quota, and received amount of data session quota; and determining whether or not to perform the allowing based on a result obtained from the determining of whether or not a remaining quota is available.

It shall be noted that such quota determination may e.g. correspond to at least part of e.g. such Steps 9 and 15 as well as 10 and 17 as illustrated with regard to Figures 7 and 8.

The above-outlined solution allow for NSACF enhancement for suspended PDU sessions. Therefore, the above-outlined solution is advantageous in that it enables for efficient and/or secure and/or robust and/or failure resistant and/or flexible NSACF enhancement for suspended PDU sessions.

The network management entity or function be implemented as an access and mobility management function, AM F or as a session management function, SM F. Referring now to Figure 10, there is shown a flowchart illustrating steps corresponding to a method according to various examples of embodiments. With regard to the steps illustrated in Figure 10, the steps are illustrated in relation to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established PDU sessions for a network slice, to a second access network element or function, at which the established PDU sessions are suspended or at which the network slice is not supported.

In particular, according to Figure 10, in S1010, the method comprises, receiving, at a network control function for controlling slice admission, a first notification, wherein the first notification comprises information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice.

Further, in 51020, the method comprises, based on the received first notification, adjusting the at least one of endpoint terminal counter and data session counter.

It shall be noted that the information comprised in the first notification may indicate towards the network control function to reduce (e.g.. the NSACF adjusts the respective counter by reducing the respective counter) the at least one of endpoint terminal counter and data session counter. However, the information comprised in the first notification may also be understood to (alternatively) indicate towards the network control function that the at least one of endpoint terminal counter and data session counter has already been reduced (e.g. by a network management entity or function comprising at least one of an AMF and SMF, as derivable from e.g. Embodiment 3). Hence, the adjusting may further be understood as adjusting by accepting the already reduced respective counter. Additionally, the expressions "an endpoint terminal" and "a network slice" may also be understood as meaning "at least one endpoint terminal" and "at least one network slice", respectively. I.e., the method may be applied for several endpoint terminals simultaneously/at the same time, wherein the handover may comprise that e.g. a group of endpoint terminals is handovered. Moreover, the method may be applied for several network slices simultaneously/at the same time.

It shall further be noted that the endpoint terminal may represent such user equipment UE1 220 and/or UE2 210 as outlined above with reference to Figures 2 to 8. Moreover, such first and second access network elements or functions may represent such nodes gNB1 230 and gNB2 240 as outlined above with reference to Figures 2 to 8.

Furthermore, the NSACF may be such NSACF 260 as outlined above with reference to Figures 2 to 8. Further, the network slice may represent such network slice B as outlined above with reference to Figures 2 to 8. Still further, the endpoint terminal counter and the data session counter may represent such UE counter and PDU session counter as outlined above with reference to Figures 2 to 8, respectively. In this regard, the endpoint terminal counter may be understood to represent a number of endpoint terminals already/currently using the network slice and the data session counter may be understood to represent a number of PDU sessions already/currently using the network slice. The suspended data sessions of the endpoint terminal may represent such suspended PDU sessions of the UE as outlined above with reference to Figures 2 to 8, Additionally, in Step S1010, the first notification may be received from a network management entity or function, which may comprise at least one of such AM F 250 and SMF 310 as outlined above with reference to Figures 2 to 8. Moreover, Steps S1010 and S1020 may be interrelated with Step S910 according to Figure 9.

Furthermore, according to various examples of embodiments, if the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the method may further comprise: receiving a second notification, wherein the second notification comprises information indicative of an increase of at least one of the endpoint terminal counter and the data session counter; determining whether or not a predetermined threshold value related to the network slice is reached; and based on a result obtained from the determining, adjusting the at least one of endpoint terminal counter and data session counter according to the increase indicated by the received second notification.

It shall be noted that the information comprised in the second notification may indicate towards the network control function to increase (e.g. the NSACF adjusts the respective counter by increasing, if allowed, the respective counter) the at least one of endpoint terminal counter and data session counter. However, the information comprised in the second notification may also be understood to (alternatively) indicate towards the network control function that the at least one of endpoint terminal counter and data session counter has already been increased (e.g. by a network management entity or function comprising at least one of an AM F and SMF, as derivable from e.g. Embodiment 3). Hence, the adjusting may further be understood as adjusting by accepting the already increased respective counter.

It shall further be noted that such receiving of the second notification, determining and increasing may correspond to at least part of e.g. such Step 9 as well as 11 as outlined above with reference to Figures 2 and 3, respectively.

Additionally, according to various examples of embodiments, the method may further comprise responding to the second notification by indicating the result obtained from the determining about whether or not the predetermined threshold value related to the network slice is reached.

It shall be noted that such further specified responding may correspond to at least part of e.g. such Steps 10 and 12 as well as 12 and 14 as outlined above with reference to Figures 2 and 3, respectively. Further, the predetermined threshold value may be such the predetermined threshold value as outlined above with reference to Figure 9.

Optionally, according to at least some examples of embodiments, the method may further comprise receiving a third notification indicating that the endpoint terminal enters idle mode at the second access network element or function; differentiating between endpoint terminals in connected mode and endpoint terminals in idle mode by keeping two counters, the endpoint terminal counter and an endpoint terminal idle mode counter; and updating the endpoint terminal counter and the endpoint terminal idle mode counter according to the received third notification It shall be noted that such receiving of the third notification, differentiating and updating may e.g. correspond to at least part of such Steps 15 and 16 as well as 20 and 21 as illustrated with regard to Figures 2 and 3, respectively.

Further, according to various examples of embodiments, the method may further comprise receiving a request to indicate towards a network management entity or function associated with at least the first access network element or function and/or the second access network element or function about whether or not the predetermined threshold value is reached; determining whether or not the predetermined threshold value is reached; and responding to the request based on a result obtained from the determining.

It shall be noted that such receiving of a request may e.g. correspond to at least part of e.g. such Step 4 as illustrated with regard to Figures 5 and 6, respectively. Further, such determining and responding may e.g. correspond to at least part of e.g. such Steps 6, 17, 12 and 13 as well as 6, 7, 14 and 15 as illustrated with regard to Figures 5 and 6, respectively.

Moreover, according to at least some examples of embodiments, the method of any of the preceding embodiments may further comprise receiving a subscription for a quota handling for at least one of suspended endpoint terminals and suspended data sessions; and based on the subscription, providing at least one of -a predetermined amount of endpoint terminal quota to be used for resuming suspended endpoint terminals without sending a notification to the network control function, and -a predetermined amount of data session quota to be used for resuming suspended data sessions without sending a notification to the network control function.

It shall be noted that further to the receiving of the subscription and the corresponding providing of the endpoint terminal quota and/or data session quota, the method may further comprise that the receiving of the first notification further comprises receiving at least one of -an updated amount of the provided endpoint terminal remaining quota, updated according to the reduction indicated in the first notification, and -an updated amount of the provided data session remaining quota, updated according to the reduction indicated in the first notification.

It shall further be noted that such receiving of a subscription may e.g. correspond to at least part of e.g. such Step 1 as illustrated with regard to Figures 7 and 8, wherein such providing may e.g. correspond to at least part of e.g. such Step 2 as illustrated with regard to Figures 7 and 8.

Furthermore, according to various examples of embodiments, if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, and if at least one remaining quota is available from the at least one of provided endpoint terminal quota and data session quota, the receiving of the second notification may further comprise receiving at least one of: -an updated amount of the provided endpoint terminal remaining quota, updated according to the increase indicated in the second notification, and -an updated amount of the provided PDU session remaining quota, updated according to the increase indicated in the second notification. Wherein the method may further comprise notifying an increase of the at least one of -endpoint terminal counter according to the increase indicated in the second notification; 15 and -data session counter according to the increase indicated in the second notification.

It shall be noted that such further specified receiving of the second notification and such notifying may e.g. correspond to at least part of e.g. such Steps 9 as well as 10 as illustrated with regard to Figures 7 and 8.

Moreover, according to at least some examples of embodiments, the network slice may be subject to network slice admission control, NSAC; and/or the network slice may be identified via a single-network slice selection assistance information, S-NSSAI; and/or the NSACF may be configured with a maximum number of endpoint terminals with regard to the endpoint terminal counter and/or a maximum number of PDU sessions with regard to the PDU session counter allowed per S-NSSAI subject to NSAC; and/or wherein the method may further comprise performing the NSAC on the network slice.

The above-outlined solution allow for NSACF enhancement for suspended PDU sessions. Therefore, the above-outlined solution is advantageous in that it enables for efficient and/or secure and/or robust and/or failure resistant and/or flexible NSACF enhancement for suspended PDU sessions.

Referring now to Figure 11, Figure 11 shows a block diagram illustrating an apparatus according to various examples of embodiments.

Specifically, Figure 11 shows a block diagram illustrating an apparatus 1100, which is adapted to implement a network management entity or function, like e.g. at least one of AMF 250 and SMF 310 as outlined above with reference to Figures 2 to 8, according to various examples of embodiments, which may participate in NSACF enhancement for suspended PDU sessions. Furthermore, even though reference is made to a network management entity or function, the network management entity or function may be also another device or function having a similar task, such as a chipset, a chip, a module, an application etc., which can also be part of a network element or attached as a separate element to a network element, or the like. It should be understood that each block and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry.

The apparatus 1100 shown in Figure 11 may include a processing circuitry, a processing function, a control unit or a processor 1110, such as a CPU or the like, which is suitable to enable NSACF enhancement for suspended PDU sessions. The processor 1110 may include one or more processing portions or functions dedicated to specific processing as described below, or the processing may be run in a single processor or processing function. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors, processing functions or processing portions, such as in one physical processor like a CPU or in one or more physical or virtual entities, for example. Reference signs 1131 and 1132 denote input/output (I/O) units or functions (interfaces) connected to the processor or processing function 1110. The I/O units 1131 and 1132 may be a combined unit including communication equipment towards several entities/elements, or may include a distributed structure with a plurality of different interfaces for different entities/elements. Reference sign 1120 denotes a memory usable, for example, for storing data and programs to be executed by the processor or processing function 1110 and/or as a working storage of the processor or processing function 1110. It is to be noted that the memory 1120 may be implemented by using one or more memory portions of the same or different type of memory, but may also represent an external memory, e.g. an external database provided on a cloud server.

The processor or processing function 1110 is configured to execute processing related to the above described processing. In particular, the processor or processing circuitry or function 1110 includes one or more of the following sub-portions. Sub-portion 1111 is a transmitting portion, which is usable as a portion for transmitting a notification towards a network function such as a control network function for controlling slice admission. Said control network function may be, for instance, implemented as network slice admission control function, NSACF. The portion 1111 may be configured to perform processing according to S910 of Figure 9.

Referring now to Figure 12, Figure 12 shows a block diagram illustrating an apparatus according to various examples of embodiments.

Specifically, Figure 12 shows a block diagram illustrating an apparatus 1200, which is adapted to implement a control network function for controlling slice admission such as, for example, a network slice admission control function, NSACF, like e.g. such NSACF 260 as outlined above with reference to Figures 2 to 8, according to various examples of embodiments, which may participate in NSACF enhancement for suspended PDU sessions. Furthermore, even though reference is made to an NSACF, the NSACF may be also another device or function having a similar task, such as a chipset, a chip, a module, an application etc., which can also be part of a network element or attached as a separate element to a network element, or the like. It should be understood that each block and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry.

The apparatus 1200 shown in Figure 12 may include a processing circuitry, a processing function, a control unit or a processor 1210, such as a CPU or the like, which is suitable to enable admission control enhancement for suspended data sessions. The processor 1210 may include one or more processing portions or functions dedicated to specific processing as described below, or the processing may be run in a single processor or processing function. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors, processing functions or processing portions, such as in one physical processor like a CPU or in one or more physical or virtual entities, for example. Reference signs 1231 and 1232 denote input/output (I/0) units or functions (interfaces) connected to the processor or processing function 1210. The I/O units 1231 and 1232 may be a combined unit including communication equipment towards several entities/elements, or may include a distributed structure with a plurality of different interfaces for different entities/elements. Reference sign 1220 denotes a memory usable, for example, for storing data and programs to be executed by the processor or processing function 1210 and/or as a working storage of the processor or processing function 1210. It is to be noted that the memory 1220 may be implemented by using one or more memory portions of the same or different type of memory, but may also represent an external memory, e.g. an external database provided on a cloud server.

The processor or processing function 1210 is configured to execute processing related to the above-described processing with reference to the method of the above-described embodiments. In particular, the processor or processing circuitry or function 1210 includes one or more of the following sub-portions. Sub-portion 1211 is a receiving portion, which is usable as a portion for receiving a notification. The portion 1211 may be configured to perform processing according to 51010 of Figure 10. Further, sub-portion 1212 is an adjusting portion, which is usable as a portion for adjusting at least one of an endpoint terminal counter and a PDU session counter. The portion 1212 may be configured to perform processing according to 51020 of Figure 10.

It shall be noted that the apparatuses 1100 and 1200 as outlined above with reference to Figures 11 and 12 may comprise further/additional sub-portions, which may allow the apparatuses 1100 and 1200 to perform such methods/method steps as outlined above with reference to Figures 2 to 8, as well as such methods/method steps as outlined above with reference to Figures 9 and 10.

It should be appreciated that -an access technology via which traffic is transferred to and from an entity in the communication network may be any suitable present or future technology, such as VVLAN (Wireless Local Access Network), VViMAX (Worldwide lnteroperability for Microwave Access), LTE, LTE-A, 50, Bluetooth, Infrared, and the like may be used; additionally, embodiments may also apply wired technologies, e.g. IP based access technologies like cable networks or fixed lines.

-embodiments suitable to be implemented as software code or portions of it and being run using a processor or processing function are software code independent and can be specified using any known or future developed programming language, such as a high-level programming language, such as objective-C, C, C++, C#, Java, Python, Javascript, other scripting languages etc., or a low-level programming language, such as a machine language, or an assembler.

-implementation of embodiments is hardware independent and may be implemented using any known or future developed hardware technology or any hybrids of these, such as a microprocessor or CPU (Central Processing Unit), MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), and/or TTL (Transistor-Transistor Logic).

-embodiments may be implemented as individual devices, apparatuses, units, means or functions, or in a distributed fashion, for example, one or more processors or processing functions may be used or shared in the processing, or one or more processing sections or processing portions may be used and shared in the processing, wherein one physical processor or more than one physical processor may be used for implementing one or more processing portions dedicated to specific processing as described, -an apparatus may be implemented by a semiconductor chip, a chipset, or a (hardware) module including such chip or chipset; -embodiments may also be implemented as any combination of hardware and software, such as ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) or CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components.

-embodiments may also be implemented as computer program products, including a computer usable medium having a computer readable program code embodied therein, the computer readable program code adapted to execute a process as described in embodiments, wherein the computer usable medium may be a non-transitory medium.

Although the present disclosure has been described herein before with reference to particular embodiments thereof, the present disclosure is not limited thereto and various modifications can be made thereto.

Claims (36)

1. CLAIMS: 1. A method at a network management entity associated with at least one of a first access network element or function and a second access network element or function, comprising, receiving a handover message relative to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established PDU sessions for a network slice, to a second access network element or function, determining, based on the reception of the handover message, that the established PDU sessions are suspended or that the network slice is not supported at the second access network element or function, based on the determining transmitting (S910) a first notification towards a control network function for controlling slice admission, wherein the first notification comprises information indicative of a reduction of at least one of the following: an endpoint terminal counter for the network slice, and a data session counter for the network slice.
2. 2. The method according to claim 1, wherein the reduction of the at least one of endpoint terminal counter and data session counter comprises a reduction of the at least one of endpoint terminal counter by an amount of endpoint terminals participating in the handover, the amount of endpoint terminals comprising at least the endpoint terminal, and data session counter by an amount of the suspended data sessions.
3. 3. The method according to claim 1 or 2, wherein, determining that the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the method further comprises based on the determining, transmitting a second notification towards the control network function, wherein the second notification comprises information indicative of an increase of at least one of the endpoint terminal counter and the data session counter.
4. 4. The method according to claim 3, further comprising receiving a response to the second notification indicating whether or not a predetermined threshold value related to the network slice is reached; and based on the received response, determining whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.
5. 5. The method according to claim 4, wherein the predetermined threshold value is at least one of a first predetermined threshold value representing a maximum number of endpoint terminals allowable for the network slice or a percentage of the maximum number of endpoint terminals, and a second predetermined threshold value representing a maximum number of data sessions allowable for the network slice or a percentage of the maximum number of data sessions, and wherein the method further comprises, if the first predetermined threshold value is not reached, allowing the endpoint terminal to resume the suspended data sessions; if the first predetermined threshold value is reached, releasing the endpoint terminal; and/or releasing the suspended data sessions of the endpoint terminal; if the second predetermined threshold value is not reached, resuming the suspended data sessions of the endpoint terminal; and if the second predetermined threshold value is reached, releasing at least one suspended data session of the suspended data sessions of the endpoint terminal.
6. 6. The method according to any one of claims 3 to 5, wherein the transmitting of the second notification comprises at least one of sequentially transmitting a notification for a single data session out of the suspended data sessions, and transmitting a notification to a group of data sessions out of the suspended data sessions
7. 7. The method according to claim 1, wherein based on determining at a network management entity or function that the endpoint terminal enters idle mode at the second access network element or function, transmitting a third notification towards the control network function to notify the control network function about the endpoint terminal entering idle mode, wherein the third notification comprises an indication to increase the data session counter and the endpoint terminal counter.
8. 8. The method according to claim 1, further comprising requesting the control network function for an indication about whether or not at least one of the first predetermined threshold value and the second predetermined threshold value is reached; and based on a reception of the requested indication, determining whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.
9. 9. The method according to claim 8, further comprising, based on the reception of the requested indication, if the first predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmitting a fourth notification towards the control network function to increase the endpoint terminal counter; and allowing the endpoint terminal to resume the suspended data sessions; if the first predetermined threshold value is reached, refraining from releasing the endpoint terminal and waiting until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitoring for an update with regard to whether or not the first predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determining whether or not to release the endpoint terminal based on a result obtained from the monitoring for the update; if the second predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmitting a fifth notification towards the control network function to increase the data sessions counter; and resuming the suspended data sessions of the endpoint terminal; and if the second predetermined threshold value is reached, refraining from releasing the suspended data sessions and waiting until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitoring for an update with regard to whether or not the second predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determining whether or not to release the suspended data sessions of the endpoint terminal based on a result obtained from the monitoring for the update.
10. 10. The method according to any of claims 3 to 5, 8 or 9, wherein, if the endpoint terminal handovers from the second access network element or function to another access network element or function, the method further comprises determining whether or not the endpoint terminal is allowed to resume the suspended data sessions; and based on determining that the endpoint terminal is not allowed to resume the suspended data sessions, releasing the suspended data sessions of the endpoint terminal.
11. 11. A method at a control network function for controlling slice admission, comprising, in relation to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established data sessions for a network slice, to a second access network element or function, at which the established data sessions are suspended or at which the network slice is not supported, receiving (S1010), a first notification, wherein the first notification comprises information indicative of a reduction of at least one of the following: an endpoint terminal counter for the network slice, and a data session counter for the network slice; and based on the received first notification, adjusting (S1020) the at least one of endpoint terminal counter and data session counter.
12. 12. The method according to claim 11, wherein if the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the method further comprises receiving a second notification, wherein the second notification comprises code indicative of an increase of at least one of the endpoint terminal counter and the data session counter; determining whether or not a predetermined threshold value related to the network slice is reached; and based on a result obtained from the determining, increasing the at least one of endpoint terminal counter and data session counter according to the increase indicated by the received second notification.
13. 13. The method according to claim 11, further comprising receiving a third notification indicating that the endpoint terminal enters idle mode at the second access network element or function; differentiating between endpoint terminals in connected mode and endpoint terminals in idle mode by keeping two counters, the endpoint terminal counter and an endpoint terminal idle mode counter; and updating the endpoint terminal counter and the endpoint terminal idle mode counter according to the received third notification.
14. 14. The method according to claim 11, further comprising receiving a request to indicate towards a network management entity or function associated with at least the first access network element or function and/or the second access network element or function about whether or not the predetermined threshold value is reached; determining whether or not the predetermined threshold value is reached; and responding to the request based on a result obtained from the determining.
15. 15. An apparatus (1100), comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to, in relation to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established data sessions for a network slice, to a second access network element or function, at which the established data sessions are suspended or at which the network slice is not supported, and wherein the apparatus is associated with at least the first access network element or function and/or the second access network element or function, transmit a first notification towards a network slice admission control function, control network function, wherein the first notification comprises information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice.
16. 16. The apparatus according to claim 15, wherein the reduction of the at least one of endpoint terminal counter and data session counter comprises a reduction of the at least one of endpoint terminal counter by an amount of endpoint terminals participating in the handover, the amount of endpoint terminals comprising at least the endpoint terminal, and data session counter by an amount of the suspended data sessions.
17. 17. The apparatus according to claim 15 or 16, wherein, if the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the apparatus is further caused to transmit a second notification towards the control network function, wherein the second notification comprises information indicative of an increase of at least one of the endpoint terminal counter and the data session counter.
18. 18. The apparatus according to claim 17, wherein the apparatus is further caused to responsive to the apparatus being caused to transmit the second notification, receive a response indicating whether or not a predetermined threshold value related to the network slice is reached; and based on the received response, determine whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.
19. 19. The apparatus according to claim 18, wherein the predetermined threshold value is at least one of a first predetermined threshold value representing a maximum number of endpoint terminals allowable for the network slice or a percentage of the maximum number of endpoint terminals, and a second predetermined threshold value representing a maximum number of data sessions allowable for the network slice or a percentage of the maximum number of data sessions, and wherein the apparatus is further caused to, if the first predetermined threshold value is not reached, allow the endpoint terminal to resume the suspended data sessions; if the first predetermined threshold value is reached, release the endpoint terminal; and/or release the suspended data sessions of the endpoint terminal; if the second predetermined threshold value is not reached, resume the suspended data sessions of the endpoint terminal; and if the second predetermined threshold value is reached, release at least one suspended data session of the suspended data sessions of the endpoint terminal.
20. 20. The apparatus according to any one of claims 17 to 19, wherein the apparatus being caused to transmit the second notification further comprises the apparatus being caused to at least one of sequentially transmit a notification for a single data session out of the suspended data sessions, and transmit a notification to a group of data sessions out of the suspended data sessions.
21. 21. The apparatus according to claim 15, wherein the apparatus is further caused to based on determining at a network management entity or function that the endpoint terminal enters idle mode at the second access network element or function, transmit a third notification towards the control network function to notify the control network function about the endpoint terminal entering idle mode wherein the third notification comprises an indication to increase the data session counter and the endpoint terminal counter.
22. 22. The apparatus according to claim 15, wherein the apparatus is further caused to request the control network function for an indication about whether or not at least one of the first predetermined threshold value and the second predetermined threshold value is reached; and based on a reception of the requested indication, determine whether or not to release at least one of the endpoint terminal and the suspended data sessions of the endpoint terminal.
23. 23. The apparatus according to claim 22, wherein the apparatus is further caused to, based on the reception of the requested indication, if the first predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmit a fourth notification towards the control network function to increase the endpoint terminal counter; and allow the endpoint terminal to resume the suspended data sessions; if the first predetermined threshold value is reached, refrain from releasing the endpoint terminal and wait until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitor for an update with regard to whether or not the first predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determine whether or not to release the endpoint terminal based on a result obtained from the monitoring for the update; if the second predetermined threshold value is not reached, when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, transmit a fifth notification towards the control network function to increase the data sessions counter; and resume the suspended data sessions of the endpoint terminal; and if the second predetermined threshold value is reached, refrain from releasing the suspended data sessions and wait until the endpoint terminal tries to handover back to the first access network element or function or to handover to the third access network element or function; during the waiting, monitor for an update with regard to whether or not the second predetermined threshold value being reached; and when the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determine whether or not to release the suspended data sessions of the endpoint terminal based on a result obtained from the monitoring for the update.
24. 24. The apparatus according to any of claims 17 to 19, 22 or 23, wherein, if the endpoint terminal handovers from the second access network element or function to another access network element or function, the apparatus is further caused to determine whether or not the endpoint terminal is allowed to resume the suspended data sessions; and based on determining that the endpoint terminal is not allowed to resume the suspended data sessions, release the suspended data sessions of the endpoint terminal.
25. 25. The apparatus according to any one of claims 15 to 24, wherein the apparatus is further caused to subscribe at the control network function for a quota handling for at least one of suspended endpoint terminals and suspended data sessions; based on the subscription, receive at least one of a predetermined amount of endpoint terminal quota to be used for resuming suspended endpoint terminals without sending a notification to the control network function, and a predetermined amount of data session quota to be used for resuming suspended data sessions without sending a notification to the control network function; and adapt the at least one of received predetermined amount of endpoint terminal remaining quota according to the reduction of the terminal endpoint counter indicated in the first notification, and received predetermined amount of data session remaining quota according to the reduction of the data session counter indicated in the first notification.
26. 26. The apparatus according to claim 25, wherein if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, the apparatus is further caused to allow the endpoint terminal to resume its suspended data sessions for the network slice; and based on the apparatus being caused to allow the endpoint terminal to resume its suspended data sessions, adapt the at least one of amount of endpoint terminal remaining quota prevailing at the apparatus by reducing the amount of endpoint terminal remaining quota by one, and amount of data session remaining quota prevailing at the apparatus by reducing the amount of data session remaining quota according to an amount of the suspended data sessions of the endpoint terminal.
27. 27. The apparatus according to claim 26, wherein the apparatus is further caused to if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, determine whether or not a remaining quota is available from the at least one of received amount of endpoint terminal quota, and received amount of data session quota; and determine whether or not to allow the endpoint terminal to resume its suspended PDU sessions for the network slice based on a result obtained from the determining of whether or not a remaining quota is available.
28. 28. An apparatus (1200), comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to, in relation to a handover of an endpoint terminal from a first access network element or function, at which the endpoint terminal had established data sessions for a network slice, to a second access network element or function, at which the established data sessions are suspended or at which the network slice is not supported, receive a first notification, wherein the first notification comprises information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice; and based on the received first notification, adjust the at least one of endpoint terminal counter and data session counter.
29. 29. The apparatus according to claim 28, wherein if the endpoint terminal handovers back to the first access network element or function or handovers to a third access network element or function, at which the suspended data sessions established for the network slice are supported or at which the network slice is supported, the apparatus is further caused to receive a second notification, wherein the second notification comprises information indicative of an increase of at least one of the endpoint terminal counter and the data session counter; determine whether or not a predetermined threshold value related to the network slice is reached; and based on a result obtained from the determining, increase the at least one of endpoint terminal counter and data session counter according to the increase indicated by the received second notification.
30. 30. The apparatus according to claim 29, wherein the apparatus is further caused to respond to the second notification by indicating the result obtained from the determining.
31. 31. The apparatus according to claim 28, wherein the apparatus is further caused to receive a third notification indicating that the endpoint terminal enters idle mode at the second access network element or function; differentiate between endpoint terminals in connected mode and endpoint terminals in idle mode by keeping two counters, the endpoint terminal counter and an endpoint terminal idle mode counter; and update the endpoint terminal counter and the endpoint terminal idle mode counter according to the received third notification.
32. 32. The apparatus according to claim 28, wherein the apparatus is further caused to receive a request to indicate towards a network management entity or function associated with at least the first access network element or function and/or the second access network element or function about whether or not the predetermined threshold value is reached; determine whether or not the predetermined threshold value is reached; and respond to the request based on a result obtained from the determining.
33. 33. The apparatus according to any one of claims 28 to 32, wherein the apparatus is further caused to receive a subscription for a quota handling for at least one of suspended endpoint terminals and suspended data sessions; and based on the subscription, provide at least one of a predetermined amount of endpoint terminal quota to be used for resuming suspended endpoint terminals without sending a notification to the apparatus, and a predetermined amount of data session quota to be used for resuming suspended data sessions without sending a notification to the apparatus.
34. 34. The apparatus according to claim 33, wherein if the endpoint terminal handovers back to the first access network element or function or handovers to the third access network element or function, and if at least one remaining quota is available from the at least one of provided endpoint terminal quota and data session quota, the apparatus being caused to receive the second notification further comprises the apparatus being caused to receive at least one of an updated amount of the provided endpoint terminal remaining quota, updated according to the increase indicated in the second notification, and an updated amount of the provided data session remaining quota, updated according to the increase indicated in the second notification; and wherein the apparatus is further caused to notify an increase of the at least one of endpoint terminal counter according to the increase indicated in the second notification; and data session counter according to the increase indicated in the second notification.
35. 35. A computer program product for a computer, including software code portions for performing the steps of any of claims 1 to 10, or any of claims 11 to 14, when said product is run on the computer.
36. 36. The computer program product according to claim 35, wherein the computer program product includes a computer-readable medium on which said software code portions are stored, and/or the computer program product is directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.