Method and apparatus for establishing a network-controlled radio resource control connection

Abstract

A method, device, and software are provided for establishing a network-controlled Radio Resource Control (RRC) connection. The method, device, and software receive a registration request from the user's equipment on a communication network. They then generate a registration acceptance message that includes an NSSAI (Network Segment Selection Assistance Information) inclusion mode parameter for establishing the access stratum connection. Finally, the method, device, and software transmit the registration acceptance message to the user's equipment.

Description

TECHNICAL FIELD

[0001] This application relates generally to providing a network controlled radio resource control (RRC) connection establishment mechanism.BACKGROUND

[0002] In celluar systems such as the Evolved Packet System (EPS) or the fifth generation (5G) network system, a user equipment (UE) may establish a RRC connection with a radio access network (RAN) by sending a RRC connection establishment request. Some information may be provided in the RRC connection for the purpose of allowing the RAN to apply various policies, such as accepting the RRC connection establishment request, rejecting the RRC connection establishment request, or releasing the RRC connection establishment request. The RRC connection establishment request may be triggered by a service request in a 5G system.

[0003] Network slice selection assistance information (NSSAI) is one type of information that could be provided by the UE to the RAN. In a RRC connection establishment request, the UE may include a NSSAI which could be: the Allowed NSSAI (e.g., the list of S-NSSAIs associated to the Network Slices the UE is allowed to use at the time it requests the RRC connection to be established, see 3GPP TS 23.501 for an example definition), one or more S-NSSAI (Single NSSAI) associated to the Network Slices of which there is data or signalling to be transmited at the time the UE equests the RRC connection to be established, or no NSSAI at all. The RAN may process the RRC connection establishment request depending on the NSSAI or lack thereof. Currently, there is no definition regarding what NSSAI, if any, the RRC connection establishment request would include. Various proposals were provided to address this issue. However, these proposals do not allow flexible RRC connection establishment behaviour.

[0004] US 2017 / 303259 A1 discloses a communication method and apparatus using network slicing. A communication method of a communication apparatus performing communication with a user equipment receives a predetermined request from the user equipment, selects a single network slice instance to be allocated to the user equipment from among a plurality of network slice instances in the communication apparatus in response to the request, selects a single network function instance to be allocated to the user equipment from among a plurality of network function instances included in the selected network slice instance. The network slice instance is in an instantiated form of a network slice that includes at least one network function and resource for providing a network service having a predetermined capability and characteristic to the user equipment.

[0005] ZTE ET AL: "Network slicing in the registration procedure", 3GPP DRAFT, C1-173561, 25 August 2017, discloses that the UE initiates the registration procedure for initial registration by sending a REGISTRATION REQUEST message to the AMF, starting timer Ta. If timer Tb is currently running, the UE shall stop timer Tb. If timer Tc is currently running, the UE shall stop timer Tc. If the UE supports network slicing, the UE shall include the Requested NSSAI containing the S-NSSAI(s) corresponding to the slice(s) to which the UE wishes to register in the REGISTRATION REQUEST. The Requested NSSAI shall be either:-the Configured NSSAI for the current PLMN, or a subset thereof as described below, if the UE has no Allowed NSSAI for the current PLMN; or -the Allowed NSSAI for the current PLMN, or a subset thereof as described below, if the UE has an Allowed NSSAI for the current PLMN; or -the Allowed NSSAI for the current PLMN, or a subset thereof as described below, plus one or more S-NSSAIs from the Configured NSSAI for which no corresponding S-NSSAI is present in the Allowed NSSAI and that were not previously rejected with "S-NSSAI not available in this PLMN" or "S-NSSAI not available in this registration area" by the network for the present tracking area. The subset of Configured NSSAI provided in the Requested NSSAI consists of one or more S-NSSAI(s) in the Configured NSSAI applicable to this PLMN, if: -some S-NSSAI was not previously rejected with "S-NSSAI not available in this PLMN" or "S-NSSAI not available in this registration area" by the network for the present registration area; or - some S-NSSAI was not 30 previously added by the UE in a Requested NSSAI. The subset of Allowed NSSAI provided in the Requested NSSAI consists of one or more S-NSSAI(s) in the Allowed NSSAI for this PLMN.

[0006] SAMSUNG R&D INSTITUTE UK ET AL: "Configured NSSAI added to registration accept message", 3GPP DRAFT, C1-183114, 20 May 2018, discloses that if the AMF derives a Configured NSSAI at the time of registration, it follows that the AMF may send that Configured NSSAI to the UE in the REGISTRATION ACCEPT message rather than using the UE Configuration Update procedure. In addition, during Initial UE Registration the network may need to provide to the UE both, the Allowed NSSAI and the Configured NSSAI. Currently, the AMF can only provide the Allowed NSSAI and initiate a separate UE Configuration Update (UCU) procedure to provide the Configured NSSAI. This second UCU procedure triggers another UE Registration, which is unneccessary.BRIEF SUMMARY

[0007] The invention is defined by the independent claims. Particular embodiments are set out in the dependent claims. An example embodiment relates generally to a method, apparatus and computer program product for providing a network controlled radio resource control (RRC) connection establishment mechanism. In one example embodiment, a method is provided that includes receiving a registration request originating with user equipment in a communication network. The method further includes constructing a registration accept message. The registration accept message includes an indication comprising an Access Stratum Connection Establishment NSSAI (Network Slice Selection assistance information) Inclusion Mode parameter defining what network slice assistance information, if any, to include, by the user equipment, in a subsequent access stratum connection establishment. The method further includes transmitting the registration accept message to the user equipment.

[0008] In some embodiments, the registration request comprises an access stratum connection establishment request that is triggered by a service request based on, that is, triggered by, pending data or signaling related to one or more network slices. In some embodiments, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter indicates whether the user equipment will transmit one of: an Allowed NSSAI for the user equipment or one or more S-NSSAIs associated with the network slice or network slices which trigger the service request. In some embodiments, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter is derived based on a set of policies implemented in one or more radio access nodes in a registration area of the communication network.

[0009] In another example embodiment, a core network is provided that includes means for carrying out the method of above.

[0010] In another example embodiment, a computer program product is provided that includes at least one non-transitory computer-readable storage medium having computer executable program code instructions stored therein with the computer executable program code instructions comprising program code instructions configured, upon execution, to receive a registration request originating with user equipment in a communication network. The computer executable program code instructions comprise program code instructions that are further configured, upon execution, to carry out the method of above.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Having thus described certain example embodiments of the present disclosure in general terms, reference will hereinafter be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: Figure 1 is a block diagram of an apparatus that may be specifically configured in accordance with an example embodiment of the present disclosure; Figure 2 is a flowchart depicting operations performed, such as by the apparatus of Figure 1, in accordance with an example embodiment of the present disclosure; and Figure 3 illustrates example transmissions between a user equipment and a core network in accordance with an example embodiment of the present disclosure. DETAILED DESCRIPTION

[0012] Some embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, various embodiments of the invention may be embodied in many different forms and need to not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. As used herein, the terms "data," "content," "information," and similar terms may be used interchangeably to refer to data capable of being transmitted, received and / or stored in accordance with embodiments of the present invention. Thus, use of any such terms need to not be taken to limit the spirit and scope of embodiments of the present invention.

[0013] Additionally, as used herein, the term 'circuitry' refers to (a) hardware-only circuit implementations (e.g., implementations in analog circuitry and / or digital circuitry); (b) combinations of circuits and computer program product(s) comprising software and / or firmware instructions stored on one or more computer readable memories that work together to cause an apparatus to perform one or more functions described herein; and (c) circuits, such as, for example, a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term 'circuitry' also includes an implementation comprising one or more processors and / or portion(s) thereof and accompanying software and / or firmware. As another example, the term 'circuitry' as used herein also includes, for example, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, other network device, field programmable gate array, and / or other computing device.

[0014] As defined herein, a "computer-readable storage medium" refers to a physical storage medium (e.g., volatile or non-volatile memory device).

[0015] An example embodiment relates generally to a method, apparatus and computer program product for providing a network controlled radio resource control (RRC) connection establishment mechanism.

[0016] In celluar systems such as the Evolved Packet System (EPS) or the fifth generation (5G) network system, a user equipment (UE) may establish an Access Stratum connecttion (e.g. RRC connection) with a radio access network (RAN) by sending e.g. a RRC connection establishment request (see 3GPP TS 38.331). Some information may be provided in the RRC connection establishment procedure for the purpose of allowing the RAN to apply various policies, such as accepting the RRC connection establishment request or releasing the RRC connection establishment request. The RRC connection establishment request may be triggered by a service request in a 5G system.

[0017] Network slice selection assistance information (NSSAI) is one type of information that could be provided by the UE to the RAN. In a RRC connection establishment request, the UE may include a NSSAI which could be: the Allowed NSSAI (e.g., the list of S-NSSAIs associated to the Network Slices the UE is allowed to use at the time the UE requests the RRC connection to be established), one or more S-NSSAI (Single NSSAI) associated to the Network Slices of which there is data or signalling to be transmited at the time the UE requests the RRC connection to be established , or no NSSAI at all.A NSSAI is a collection of S-NSSAIs. Each S-NSSAI identifies a network slice in the 5G network system. Example S-NSSAIs include a slice / service type (SST) and a slice differentiator (SD). The SST indicates expected network slice behaviour such as features and services provided. The SD includes optional information that differentiates amongst multiple network slices that are of the same slice / service type.

[0018] The RAN may process the RRC connection establishment request depending on the NSSAI or lack thereof. Currently, there is no definition regarding what NSSAI, if any, the RRC connection establishment request would include. Various proposals are provided to address this issue. One proposal is to include S-NSSAI(s) for the slices that have data or signalling to transmit at the time the Service Request is triggering the RRC connection establishment, another proposal is to include the Allowed NSSAI which includes a collection of S-NSSAIs, and yet another proposal is to not include any NSSAI at all. However, these proposals do not allow a flexible deployment for RRC connection establishment.

[0019] An example embodiment relates generally to a method, apparatus and computer program product for providing a network controlled radio resource control (RRC) connection establishment mechanism that allows such flexibile deployment.

[0020] In order to embody the core network including a RAN and an access and mobility management function, an apparatus 10 is provided and as shown, for example, in Figure 1. The apparatus may be embodied by any of a variety of different components such as different nodes of a 5G core network instance. As shown in Figure 1, the apparatus of an example embodiment includes, is associated with or is otherwise in communication with a processor 12, an associated memory 14 and a communication interface 16.

[0021] The processor 12 (and / or co-processors or any other circuitry assisting or otherwise associated with the processor) may be in communication with the memory device 14 via a bus for passing information among components of the apparatus 10. The memory device may be non-transitory and may include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory device may be an electronic storage device (e.g., a computer readable storage medium) comprising gates configured to store data (e.g., bits) that may be retrievable by a machine (e.g., a computing device like the processor). The memory device may be configured to store information, data, content, applications, instructions, or the like for enabling the apparatus to carry out various functions in accordance with an example embodiment of the present disclosure. For example, the memory device could be configured to buffer input data for processing by the processor. Additionally or alternatively, the memory device could be configured to store instructions for execution by the processor.

[0022] The apparatus 10 may, in some embodiments, be embodied in various computing devices as described above. However, in some embodiments, the apparatus may be embodied as a chip or chip set. In other words, the apparatus may comprise one or more physical packages (e.g., chips) including materials, components and / or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and / or limitation of electrical interaction for component circuitry included thereon. The apparatus may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0023] The processor 12 may be embodied in a number of different ways. For example, the processor may be embodied as one or more of various hardware processing means such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without an accompanying DSP, or various other circuitry including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. As such, in some embodiments, the processor may include one or more processing cores configured to perform independently. A multi-core processor may enable multiprocessing within a single physical package. Additionally or alternatively, the processor may include one or more processors configured in tandem via the bus to enable independent execution of instructions, pipelining and / or multithreading.

[0024] In an example embodiment, the processor 12 may be configured to execute instructions stored in the memory device 14 or otherwise accessible to the processor. Alternatively or additionally, the processor may be configured to execute hard coded functionality. As such, whether configured by hardware or software methods, or by a combination thereof, the processor may represent an entity (e.g., physically embodied in circuitry) capable of performing operations according to an embodiment of the present disclosure while configured accordingly. Thus, for example, when the processor is embodied as an ASIC, FPGA or the like, the processor may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor is embodied as an executor of instructions, the instructions may specifically configure the processor to perform the algorithms and / or operations described herein when the instructions are executed. However, in some cases, the processor may be a processor of a specific device (e.g., an image processing system) configured to employ an embodiment of the present invention by further configuration of the processor by instructions for performing the algorithms and / or operations described herein. The processor may include, among other things, a clock, an arithmetic logic unit (ALU) and logic gates configured to support operation of the processor.

[0025] The communication interface 16 may be any means such as a device or circuitry embodied in either hardware or a combination of hardware and software that is configured to receive and / or transmit data from / to a network. In this regard, the communication interface may include, for example, an antenna (or multiple antennas) and supporting hardware and / or software for enabling communications with a wireless communication network. Additionally or alternatively, the communication interface may include the circuitry for interacting with the antenna(s) to cause transmission of signals via the antenna(s) or to handle receipt of signals received via the antenna(s). In some environments, the communication interface may alternatively or also support wired communication. As such, for example, the communication interface may include a communication modem and / or other hardware / software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB) or other mechanisms.

[0026] Figure 2 is a flowchart illustrating a workflow of a core network in accordance with the claimed invention. At block 20, the core network receives, for example by using means such as the processor 12 and the communication interface 16, a registration request from a user equipment in a communication network.

[0027] After the core network receives the registration request from the user equipment, the core network constructs, for example by using means such as the processor 12, at block 22, a registration accept message. The registration accept message includes a connection establishment NSSAI (network slice selection assistance information) inclusion mode parameter. The registration accept message includes an Access Stratum Connection Establishment NSSAI Inclusion Mode parameter which defines what NSSAI, if any, the UE is to include in a subsequent Access Stratum connection establishment such as, for example, a RRC message 5 part of the RRC connection Establishment procedure defined in 3GPP TS 38.331. In some embodiments, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter defines whether the UE would include 1) an allowed NSSAI for the UE, e.g., a NSSAI set to the Allowed NSSAI for the UE defined in 3GPP TS 23.501, 2) a NSSAI including one or more S-NSSAIs of one or more network slices that triggers the connection establishment, or 3) no NSSAI. In some embodiments, an AMF in the core network may construct the registration accept message. The Allowed NSSAI may include one or more S-NSSAIs.

[0028] The Access Stratum Connection Establishment NSSAI Inclusion Mode parameter is constructed based on a set of policies implemented in a set of RAN / AN nodes in a registration area that is assigned to the UE by the core network in the Registration Accept message. For example, if at least some (R)AN node in the registration area of the core network require information regarding all the NSSAIs in the allowed NSSAI, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter may indicate that an Allowed NSSAI for the UE, e.g., a NSSAI set to the Aallowed NSSAI for the UE, needs to be transmitted from the UE to the core network. If no (R)AN node in the registration area requires information regarding all the S-NSSAIs in the Allowed NSSAI for the UE, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter may indicate that a NSSAI including one or more S-NSSAIs of one or more network slices that triggers the connection establishment needs to be transmitted. In some embodiments, if no (R)AN node in the Registration area requires information regarding all the NSSAIs in the allowed NSSAI, the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter may indicate that no NSSAI needs to be transmitted.

[0029] In some embodiments, in order to let the RAN have information regarding the Allowed NSSAI, e.g., for the purpose of implementing network slice aware overload control mechanisms, the Access Stratum Connection Establishment NSSAI Inclusion mMde parameter may indicate that an allowed NSSAI for the UE needs to be transmitted from the UE to the core network.

[0030] After the core network constructs the registration accept message, the core network, for example by using means such as the processor 12, at block 24, transmits the registration accept message to the user equipment. In some embodiments, the AMF may transmit the registration accept message to the user equipment. The user equipment causes transmission of a RRC connection establishment message in accordance with the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter received. As illustrated in Figure 3, the AMF 34 transmits a registration accept message 38 to the UE 30.

[0031] As described above, Figure 2 is a flowchart of an apparatus 10, method, and computer program product according to an example embodiment. It will be understood that each block of the flowchart, and combinations of blocks in the flowcharts, may be implemented by various means, such as hardware, firmware, processor, circuitry, and / or other devices associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory device 14 of an apparatus employing an embodiment of the present invention and executed by a processor 12 of the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus implements the functions specified in the flowchart blocks. These computer program instructions may also be stored in a computer-readable memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture, the execution of which implements the function specified in the flowchart blocks. The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart blocks.

[0032] A computer program product is therefore defined in those instances in which the computer program instructions, such as computer-readable program code portions, are stored by at least one non-transitory computer-readable storage medium with the computer program instructions, such as the computer-readable program code portions, being configured, upon execution, to perform the functions described above, such as in conjunction with the flowchart of Figure 3. In other embodiments, the computer program instructions, such as the computer-readable program code portions, need not be stored or otherwise embodied by a non-transitory computer-readable storage medium, but may, instead, be embodied by a transitory medium with the computer program instructions, such as the computer-readable program code portions, still being configured, upon execution, to perform the functions described above.

[0033] Accordingly, blocks of the flowcharts support combinations of means for performing the specified functions and combinations of operations for performing the specified functions for performing the specified functions. It will also be understood that one or more blocks of the flowcharts, and combinations of blocks in the flowcharts, may be implemented by special purpose hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

[0034] In some embodiments, certain ones of the operations above may be modified or further amplified. Furthermore, in some embodiments, additional optional operations may be included. Modifications, additions, or amplifications to the operations above may be performed in any order and in any combination.

[0035] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it need to be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A method performed by a core network apparatus (34), the method comprising: receiving (20, 36) a registration request originated from a user equipment (30) in a communication network; constructing (22) a registration accept message, wherein the registration accept message includes an indication comprising an access stratum connection establishment network slice selection assistance information inclusion mode parameter, the access stratum connection establishment network slice selection assistance information inclusion mode parameter defining what network slice selection assistance information, if any, is to be included, by the user equipment (30), in a subsequent access stratum connection establishment; and transmitting (24, 38) the registration accept message to the user equipment (30).

2. The method according to claim 1, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is derived based on a set of policies implemented in one or more radio access nodes in a registration area of the communication network.

3. The method according to claim 1 or claim 2, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating one or more network slice selection assistance information that the user equipment (30) needs to transmit in a subsequent access stratum connection establishment.

4. The method according to claim 1 or claim 2, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating that the user equipment (30) does not need to transmit any network slice selection assistance information in a subsequent access stratum connection establishment.

5. The method according to any one of claims 1 to 4, further comprising triggering, by a service request, based on pending data or signalling related to one or more network slices, an access stratum connection establishment request.

6. The method according to claim 5, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter indicates whether the user equipment (30) will transmit one of: an allowed network slice selection assistance information for the user equipment (30), or one or more single-network slice selection assistance information associated with the network slice or network slices which triggers the service request.

7. A core network apparatus (34) comprising: means for carrying out the method of any preceding claim.

8. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored therein, the computer-executable program code instructions comprising program code instructions configured, upon execution by a processor of a core network apparatus (34), cause the core network apparatus (34) to: carry out the method of any one of claims 1-7.

9. A method performed by a user equipment (30), the method comprising: providing (36), to a core network apparatus (34), a registration request originated from the user equipment (30), wherein the user equipment (30) is of a communication network; receiving (38) a registration accept message from the core network apparatus (34), the registration accept message comprising an access stratum connection establishment network slice selection assistance information inclusion mode parameter, the access stratum connection establishment network slice selection assistance information inclusion mode parameter defining what network slice selection assistance information, if any, is to be included, by the user equipment (30), in a subsequent access stratum connection establishment; generating an RRC connection establishment message according to the access stratum connection establishment network slice selection assistance information inclusion mode parameter; and causing transmission of the RRC connection establishment message to a radio access network, RAN, node.

10. The method of claim 9, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is derived by the core network apparatus (34) based on a set of policies implemented in one or more radio access nodes in a registration area of the communication network.

11. The method according to claim 9 or claim 10, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating one or more network slice selection assistance information that the user equipment (30) needs to transmit in a subsequent access stratum connection establishment.

12. The method according to claim 9 or claim 10, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating that the user equipment (30) does not need to transmit any network slice selection assistance information in a subsequent access stratum connection establishment.

13. The method according to any one of claims 9 to 12, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter indicates whether the user equipment (30) will transmit one of: an allowed network slice selection assistance information for the user equipment (30), or one or more single-network slice selection assistance information associated with the network slice or network slices which triggers the service request.

14. A user equipment (30) comprising: means for providing (36), to a core network apparatus (34), a registration request originated from the user equipment (30), wherein the user equipment (30) is of a communication network; means for receiving (38) a registration accept message from the core network apparatus (34), the registration accept message comprising an access stratum connection establishment network slice selection assistance information inclusion mode parameter, the access stratum connection establishment network slice selection assistance information inclusion mode parameter defining what network slice selection assistance information, if any, is to be included, by the user equipment (30), in a subsequent access stratum connection establishment; means for generating an RRC connection establishment message according to the access stratum connection establishment network slice selection assistance information inclusion mode parameter; and means for causing transmission of the RRC connection establishment message to a radio access network, RAN, node.

15. The user equipment (30) of claim 14, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is derived by the core network apparatus (34) based on a set of policies implemented in one or more radio access nodes in a registration area of the communication network.

16. The user equipment (30) according to claim 14 or claim 15, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating one or more network slice selection assistance information that the user equipment (30) needs to transmit in a subsequent access stratum connection establishment.

17. The user equipment (30) according to claim 14 or claim 15, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter is indicating that the user equipment (30) does not need to transmit any network slice selection assistance information in a subsequent access stratum connection establishment.

18. The user equipment (30) according to any one of claims 14 to 17, wherein the access stratum connection establishment network slice selection assistance information inclusion mode parameter indicates whether the user equipment (30) will transmit one of: an allowed network slice selection assistance information for the user equipment (30), or one or more single-network slice selection assistance information associated with the network slice or network slices which triggers the service request.

19. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored therein, the computer-executable program code instructions comprising program code instructions configured, upon execution by a processor of a user equipment (30), cause the user equipment (30) to: carry out the method of any one of claims 9 to 13.

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