CN117158049A

CN117158049A - Method and apparatus for supporting alternative network slicing in a wireless communication system

Info

Publication number: CN117158049A
Application number: CN202280025450.9A
Authority: CN
Inventors: 徐东垠; 李淏娟
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2021-10-26
Filing date: 2022-10-25
Publication date: 2023-12-01

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. A method is provided for solving the problem of rejecting PDU session creation due to NSAC in a wireless communication system by replacing S-nsai in accordance with an embodiment of the present disclosure.

Description

Method and apparatus for supporting alternative network slicing in a wireless communication system

Technical Field

The present disclosure relates to a method and apparatus for supporting alternative network slicing in a wireless communication system.

Background

The 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services, and can be implemented not only in a "below 6 GHz" frequency band such as 3.5GHz, but also in a "above 6 GHz" frequency band called mmWave including 28GHz and 39 GHz. Further, it has been considered to implement a 6G mobile communication technology (referred to as a super 5G system) in a terahertz frequency band (e.g., 95GHz to 3THz frequency band) in order to achieve a transmission rate 50 times faster than that of the 5G mobile communication technology and an ultra-low delay of one tenth of that of the 5G mobile communication technology.

In the early stages of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (embbb), ultra-reliable low-delay communication (URLLC), and large-scale machine type communication (emtc), beamforming and massive MIMO for reducing radio wave path loss and increasing radio wave transmission distance in mmWave, support of dynamic operation of a parameter set (e.g., operating a plurality of subcarrier intervals) and a slot format for efficiently utilizing mmWave resources, initial access technology for supporting multi-beam transmission and broadband, definition and operation of a bandwidth part (BWP), new channel coding methods such as Low Density Parity Check (LDPC) codes for mass data transmission and polarity codes for highly reliable control information transmission, L2 pre-processing, and standardization of network slices for providing a dedicated network for a specific service have been performed.

Currently, considering services that the 5G mobile communication technology will support, discussions are underway regarding improvement and performance enhancement of the initial 5G mobile communication technology, and there have been physical layer standardization regarding technologies such as V2X (vehicle-to-everything) for assisting driving determination of an autonomous vehicle based on information about the position and state of the vehicle transmitted by the vehicle, new radio unlicensed (NR-U) aimed at system operation meeting various regulatory-related requirements in an unlicensed band, NR UE power saving, non-terrestrial network (NTN) as a technology for providing covered UE-satellite direct communication in an area where communication with a terrestrial network is unavailable, and positioning.

Further, standardization has been in progress in air interface architecture/protocols such as technologies for supporting an industrial internet of things (IIoT) of new services through interworking and convergence with other industries, for providing Integrated Access and Backhaul (IAB) for nodes of network service area extension by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional handover and Dual Active Protocol Stack (DAPS) handover, and two-step random access (2-step RACH of NR) for simplifying a random access procedure. Standardization has also been underway in relation to 5G baseline architecture (e.g., service-based architecture or service-based interface) for combined Network Function Virtualization (NFV) and Software Defined Network (SDN) technologies, and system architecture/services for Mobile Edge Computing (MEC) for receiving services based on UE location.

As 5G mobile communication systems are commercialized, exponentially growing connection devices will be connected to communication networks, and thus, it is expected that enhanced functions and performance of the 5G mobile communication systems and integrated operations of the connection devices will be necessary. For this reason, new researches are being planned in connection with augmented reality (XR) for efficiently supporting Augmented Reality (AR), virtual Reality (VR), mixed Reality (MR), etc., 5G performance improvement and complexity reduction by using Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metauniverse service support, and unmanned aerial vehicle communication.

Further, such development of the 5G mobile communication system will be the basis for developing not only new waveforms for providing coverage in the terahertz band of the 6G mobile communication technology, multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas and large antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM) and Reconfigurable Intelligent Surfaces (RIS), but also full duplex technology for improving frequency efficiency of the 6G mobile communication technology and improving system network, AI-based communication technology for implementing system optimization by utilizing satellites and Artificial Intelligence (AI) from the design stage and internalizing end-to-end AI support functions, and next generation distributed computing technology for implementing services exceeding the complexity level of the UE operation capability limit by utilizing ultra-high performance communication and computing resources.

Disclosure of Invention

Technical problem

It may occur that Protocol Data Unit (PDU) session creation is denied due to the maximum number of admission controls for PDU sessions per network slice during PDU session creation, i.e. the maximum number of Network Slice Admission Controls (NSACs) for PDU sessions. In particular, when PDU session creation by a specific slice (e.g., S-nsai) that is the NSAC target is focused on a certain period of time and reaches the maximum number of established PDU sessions for the corresponding slice, many PDU session creation requests may all be rejected to the corresponding slice according to NSAC. Accordingly, there is a need for a method for mitigating rejection of a PDU session creation request due to NSACs.

The technical problems to be solved by the present disclosure are not limited to the above technical problems, and other technical problems not mentioned will be clearly understood from the following description by those of ordinary skill in the art to which the present disclosure pertains.

Problem solution

According to one aspect of the present disclosure, a method performed by an access and mobility management function (AMF) in a communication system is provided. The method comprises the following steps: receiving a first message from a terminal requesting establishment of a Protocol Data Unit (PDU) session associated with a first network slice; identifying whether the first network slice is unavailable; selecting a second network slice that replaces the first network slice if the first network slice is not available; and sending a second message to a Session Management Function (SMF) associated with the second network slice for establishing the PDU session.

In one embodiment, the method further comprises selecting the SMF based on the second network slice.

In one embodiment, the first message includes single network slice selection assistance information (S-NSSAI) for the first network slice.

In one embodiment, the method further includes receiving information about at least one network slice and information about at least one alternate network slice associated with each of the at least one network slice from a Universal Data Management (UDM).

In one embodiment, identifying whether the first network slice is unavailable comprises: receiving a third message from the SMF comprising information indicating whether the first network slice is unavailable; and identifying whether the first network slice is unavailable based on the information.

In one embodiment, the third message further includes information about a second network slice that is a substitute network slice for the first network slice.

In one embodiment, the first network slice is not available in case the number of established PDU sessions is equal to the maximum number of PDU sessions of the first network slice or the number of registered terminals is equal to the maximum number of available terminals of the first network slice.

The present disclosure also provides an access and mobility management function (AMF) in a communication system. The AMF includes: a transceiver; and a controller coupled with the transceiver and configured to: the method includes receiving a first message from a terminal requesting establishment of a Protocol Data Unit (PDU) session associated with a first network slice, identifying whether the first network slice is unavailable, selecting a second network slice to replace the first network slice if the first network slice is unavailable, and sending a second message for establishing the PDU session to a Session Management Function (SMF) associated with the second network slice.

Advantageous effects of the invention

According to embodiments of the present disclosure, the rejection of Protocol Data Unit (PDU) session creation requests due to Network Slice Admission Control (NSAC) in 5G systems may be mitigated or prevented by alternative network slicing techniques. Alternative network slicing techniques may be utilized as shown in the examples below.

In one example, in the event that the originally requested network slice is not available, the network manager may create the session by replacing the slice. Therefore, there is an advantage in that the usability of the network slice is improved.

In another example, when a session is concentrated in a particular network slice, the network manager may obtain the effect of distributing load among the network slices by enabling the use of alternate slices for new session requests requesting the corresponding network slices.

In yet another example, the network manager may prevent the corresponding session creation request from being denied by providing an alternate slice for the session creation request, where the session creation request should not be denied for reasons of non-availability of the network slice (e.g., emergency call services, national security/regulatory related services, and the case where a session established in an environment that does not support NSAC is moved to an environment that supports NSAC).

The effects obtainable in the present disclosure are not limited to the above-described effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art to which the present disclosure pertains from the following description.

Drawings

In the drawings, the same or similar reference numerals may be used for the same or similar components:

fig. 1 illustrates a method for an AMF to receive alternative S-nsai information during registration when the alternative S-nsai information is defined and provided in Access and Mobility (AM) subscription data of a UDM according to an embodiment of the present disclosure;

fig. 2 illustrates a method by which an AMF re-selects S-nsai for a PDU session through alternative S-nsai information during PDU session establishment when the alternative S-nsai information is defined and provided in Access and Mobility (AM) subscription data of a UDM according to an embodiment of the present disclosure;

fig. 3 illustrates a method by which an AMF re-selects S-nsai for a PDU session through alternative S-nsai information during PDU session establishment when the alternative S-nsai information is defined and provided in Session Management (SM) subscription data of a UDM according to an embodiment of the present disclosure;

fig. 4 illustrates a method of the AMF re-selecting S-nsai for a PDU session through alternative S-nsai information during PDU session establishment when the alternative S-nsai information is defined and provided in an NSAC function (nsacp) according to an embodiment of the present disclosure;

fig. 5 illustrates a configuration of a UE according to an embodiment of the present disclosure; and is also provided with

Fig. 6 illustrates a configuration of a network entity according to an embodiment of the present disclosure.

Detailed Description

Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "associated with … …" and "associated therewith" and derivatives thereof may mean inclusion, inclusion within … …, interconnection with … …, inclusion within … …, connection or connection with … …, coupling or coupling with … …, communicable with … …, cooperative with … …, interweaving, juxtaposition, proximity, binding or binding with … …, having the properties of … …, and the like; and the term "controller" means any device, system, or portion thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

Furthermore, the various functions described below may be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read Only Memory (ROM), random Access Memory (RAM), a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), or any other type of memory. "non-transitory" computer-readable media do not include wired, wireless, optical, or other communication links that carry transitory electrical or other signals. Non-transitory computer readable media include media in which data can be permanently stored and media in which data can be stored and subsequently overwritten, such as rewritable optical disks or erasable memory devices.

Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

Figures 1 through 6, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged system or device.

Hereinafter, the operation principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, in describing the present disclosure, a detailed description thereof will be omitted in the event that it is determined that the detailed description of related well-known functions or constructions may unnecessarily obscure the gist of the present disclosure. The terms described below are terms defined in consideration of functions in the present disclosure, which may vary according to intention or habit of a user and an operator. Therefore, the definition should be made based on the content throughout the present specification.

In the following description, in describing the present disclosure, a detailed description thereof will be omitted in the event that it is determined that the detailed description of related well-known functions or constructions may unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

Hereinafter, for convenience of description, terms used in the description to identify an access node, terms to indicate a network entity, terms to indicate a message, terms to indicate an interface between network objects, terms to indicate various types of identification information, and the like are exemplified. Accordingly, the present disclosure is not limited to the terms described below, and other terms indicating objects having equivalent technical meanings may be used.

The 5G mobile communication network is composed of 5G user equipments (UE, terminal, etc.), 5G radio access networks (RAN, base station, 5G nodeB (gNB), evolved nodeB (eNB), etc.), and 5G core networks. The 5G core network is composed of an access and mobility management function (AMF) providing a mobility management function of the UE, a Session Management Function (SMF) providing a session management function, a User Plane Function (UPF) performing a data transfer role, a Policy Control Function (PCF) providing a policy control function, a Unified Data Management (UDM) providing a data management function such as subscriber data and policy control data, and a network function such as a Unified Data Repository (UDR) storing data of various network functions such as UDM.

In 5G systems, network slicing refers to techniques and structures that implement virtualized, independent, and multiple logical networks in one physical network. Network operators provide services by constructing virtual end-to-end networks of network slices in order to meet the specific needs of the services/applications. In this case, the network slice may be identified by an identifier of single network slice selection assistance information (S-NSSAI). The network may send information about the allowed slice set (e.g., allowed nsai) to the terminal during a terminal registration procedure (e.g., a UE registration procedure), and the terminal may send and receive application data through a Protocol Data Unit (PDU) session generated via one of its S-nsais (i.e., network slices).

In a 5G system, there is a Network Slice Admission Control (NSAC) function that causes each of the number of registered UEs per network slice and the number of PDU sessions established (e.g., each of the number of registered UEs per network slice and the number of PDU sessions established per network slice) to not exceed a defined maximum value.

For admission control of the maximum number of registered UEs per network slice, the AMF may update (request to increase or decrease) the number of registered UEs for the corresponding slice to the NSAC function (nsacp) whenever the set of allowed S-nsais (allowed nsais) needs to be changed to the UE (S-nsais added or deleted). When the nsaf receives an incremental update request from the AMF for the maximum number of S-nsais for registered UEs per network slice that have reached the pre-configuration, the nsaf may provide the AMF with information that the corresponding S-nsais has reached the maximum number of registered UEs. When the AMF receives the corresponding information, the AMF may exclude the corresponding S-NSSAI from the set of allowed S-NSSAIs.

For admission control of the maximum number of PDU sessions per network slice, the SMF may update (request to increase or decrease) the number of PDU sessions established for S-NSSAI to the NSAC function (NSACF) when performing a PDU session creation or release procedure for S-NSSAI. When the nsaf receives an incremental update request from the SMF for the S-nsai that has reached the maximum number of established PDU sessions per network slice that is preconfigured, the nsaf may provide the SMF with information that the S-nsai has reached the maximum number of established PDU sessions. When the SMF receives the corresponding information, the SMF may not perform PDU session creation through the corresponding S-nsai. The NSAC target information of each S-nsai may be configured in AMF and SMF, and the AMF and SMF may perform NSAC procedure only for S-nsai as a NSAC target.

Fig. 1 illustrates a method for an AMF to receive alternative S-nsai information during registration when the alternative S-nsai information is defined and provided in Access and Mobility (AM) subscription data of a UDM according to an embodiment of the present disclosure.

Referring to fig. 1, a UE 101 may send a message for a UE registration procedure to a base station (RAN, gNB) 102 (step 110). In this case, the message for the UE registration procedure may be AN message (AN parameter, registration request). Here, AN message means a message between the UE 101 and the RAN 102. In this case, the registration request message may include at least one of information such as a UE identifier (e.g., subscription hidden identifier (sui), 5G globally unique temporary identity (5G-GUTI), or permanent device identifier (PEI)), requested NSSAI, and UE Mobility Management (MM) core network capability.

RAN 102 may select AMF 103 based on information in AN message received from UE 101 (step 120).

RAN 102 may send an N2 message (which may include at least one of an N2 parameter or a registration request) to AMF 103 (step 130). The N2 parameters may include the selected PLMN ID, UE location information, UE context request, etc.

When it is determined that UE authentication is required, AMF 103 may select authentication server function (AUSF) 104 based on at least one of the UE identifiers (e.g., sui or subscription permanent identifier (SUPI)) (step 140).

The AMF 103 may perform an authentication procedure of the UE 101 through the selected AUSF 104 (step 145). Further, when there is no non-access stratum (NAS) security context for the UE 101, a procedure for obtaining the NAS security context may be performed.

When subscription information for the UE 101 is needed, the AMF 103 may select the UDM 105 based on the SUPI, and the UDM 105 may select a UDR (not shown) in which subscription information about the UE 101 is stored (step 150).

The AMF 103 may request access and mobility subscription information about the UE 101 from the UDM 105 via a nudm_sdm_get request (which may include SUPI or at least one of access and mobility subscription data) message (step 160).

In this case, information requesting replacement slice information (e.g., replacement S-nsai) may be included in the nudm_sdm_get request message in the following cases: in case the ongoing UE registration procedure is a registration due to movement from EPS to 5GS, etc., according to the determination of the local configuration of AMF 103.

The UDM 105 may send subscription information including subscribed S-nsais, alternate slice information (e.g., alternate S-nsais for each of the subscribed S-nsais) to the AMF 103 in a nudm_sdm_get response message (step 165). In this case, the alternative S-nsai information may be defined in Access and Mobility (AM) subscription data of the nudm_sdm_get response message and transmitted to the AMF 103.

The UDM 105 may include the alternate S-NSSAI in the nudm_sdm_get response message in the following case: the AMF 103 requests a replacement S-NSSAI, etc., based on a determination of the local configuration of the UDM 105.

In this case, according to an embodiment, the UDM 105 may obtain information to be transmitted to the AMF 103 from the UDR and transmit the information to the AMF 103.

AMF 103 may calculate an allowed NSSAI taking into account the subscribed S-NSSAI and store the allowed NSSAI in the UE context (step 170).

Furthermore, for S-NSSAIs that are NSAC targets among S-NSSAIs in the allowed NSSAIs, AMF 103 can store alternate S-NSSAIs for each S-NSSAI in the UE context. In the event that AMF 103 intends to use a surrogate slice in the event that an unavailable slice occurs (e.g., a slice congestion situation occurs, etc.) due to NSAC rejection or other reasons, AMF 103 may store the surrogate slice (surrogate S-nsai for each S-nsai) for subscribed S-nsais or allowed nsais in the UE context. The AMF 103 may utilize the stored alternate S-nsais for each S-nsai to determine the slice to use (i.e., the target slice) instead of the unavailable slice and move the PDU session to the target slice when PDU session generation/modification and handover to the unavailable slice is requested.

The remaining registration process of the UE 101 may continue (step 180).

In one embodiment shown in fig. 1, the UE 101 receives the allowed set of slices through a registration process (UE registration process), then selects a slice within the corresponding set for each PDU session to be created, and creates a PDU session through a PDU session creation process. When an alternate slice (e.g., an alternate S-nsai) is provided through the registration procedure, as shown in fig. 1, there is an advantage in that signaling load is small because signaling for providing the alternate slice for each PDU session creation procedure is not required.

Fig. 2 illustrates a method by which an AMF re-selects S-nsai for a PDU session by replacing S-nsai information during PDU session establishment when the replacing S-nsai information is defined and provided in Access and Mobility (AM) subscription data of a UDM according to an embodiment of the present disclosure.

Referring to fig. 2, during UE registration, AMF 203 may store allowed nsais and alternate S-nsais information for each S-nsai that is an NSAC target in the allowed S-nsais in the UE context in the AMF (step 210). This may be performed according to the embodiment described with reference to fig. 1.

The UE 201 may send a request message (via the base station 202) to the AMF 203 for a PDU session establishment procedure (step 215). The message may be a PDU session establishment request message, and the PDU session establishment request message may be included in a non-access stratum (NAS) message and transmitted to the AMF 203.NAS messages refer to messages between UE 201 and AMF 203. According to an embodiment, the NAS message may include at least one of an S-nsai, a Data Network Name (DNN), or a PDU session ID.

In the case where the S-nsai included in the message received from the UE 201 is not currently available in step 250, the AMF 203 may not select the SMF 205, and in this case, steps 230, 240 and 250 may be omitted and the procedure from step 260 may be continued. The AMF 203 may select the SMF 205 based on at least one of DNN or S-NSSAI (step 220).

AMF 203 may send an Nsmf_PDUSation_CreateSMContext request to the selected SMF 205. According to an embodiment, the nsmf_pduse_createsmcontext request message may include at least one of an S-NSSAI, DNN, PDU session ID or a PDU session establishment request message (step 230).

When the S-nsai included in the message received from AMF 203 is a Network Slice Admission Control (NSAC) target, SMF 205 may send a nnssacf_nsac_numofpdusupdate request (which may include at least one of S-nsai, UE ID, PDU session ID, or update flag=increase) message to NSAC function (nsaf) 206 (step 240).

In the event that the update flag value of the received message is INCREASE and the number of PDU sessions established for S-NSSAI of the received message has reached the maximum number of PDU sessions established for S-NSSAI, NSACF 206 may include a value in the result value indicating that the maximum number of PDU sessions established has been reached and send the result value to SMF 205 (step 245). In this case, the message may be an nnssacf_nsac_numofpdusupdate response message.

The SMF 205 may send an nsmf_pduse_createsmcontext response message to the AMF 203 (step 250). In this case, the reason for the message may include information indicating that Session Management (SM) context creation fails due to reaching the maximum number of PDU sessions established for S-nsai.

When information indicating that SM context creation failed due to reaching the maximum number of PDU sessions established for S-nsai is included in the cause value of the message from SMF 205, or in case AMF 203 determines that S-nsai included in the message from UE 201 is not available in step 220, AMF 203 may select one of S-nsais included in allowed S-nsais among the failed or unavailable S-nsais' S alternative S-nsais to try PDU session creation again (step 260).

The alternate S-NSSAI may be stored in AMF 203 in the following form: stored in the AMF local configuration, stored in the UE context of AMF 203, etc.

The AMF 203 may again select the SMF based on the newly selected S-NSSAI (step 270). Although the drawing shows that the same SMF as that selected in step 220 is selected in step 270, the SMF selected in step 220 and the SMF selected in step 270 may be the same or different.

AMF 203 may send an Nsmf_PDUSation_CreateSMContext request message to the newly selected SMF (step 280). For ease of description, fig. 2 shows several SMFs as one SMF. The SMF newly selected by the AMF 203 in step 270 may be a different SMF than the SMF selected by the AMF 203 in step 220.

The remaining PDU session creation process may continue (step 290).

In one embodiment shown in fig. 2, in case of providing a substitute slice (e.g., substitute SNSSAI) in advance through a registration procedure (e.g., by the method shown in fig. 1), it indicates that the substitute slice is used for a PDU session, and has an advantage of small signaling load because signaling for providing the substitute slice for each PDU session creation procedure is not required.

Fig. 3 illustrates a method by which an AMF re-selects S-nsai for a PDU session through alternative S-nsai information during PDU session establishment when the alternative S-nsai information is defined and provided in Session Management (SM) subscription data of a UDM according to an embodiment of the present disclosure.

Referring to fig. 3, a ue 301 may include a PDU session establishment request message in a NAS message and send it (through a base station 302) to an AMF 303 for a PDU session establishment procedure (step 310). NAS messages refer to messages between UE 301 and AMF 303. The NAS message may include at least one of S-NSSAI, DNN, or PDU session ID.

AMF 303 may select SMF 305 based on at least one of DNN or S-NSSAI (step 320).

AMF 303 may send an Nsmf_PDUSion_CreateSMContext request (which may include at least one of an S-NSSAI, DNN, PDU session ID or PDU session establishment request message) to SMF 305 (step 330).

When the S-nsai included in the message received from AMF 303 is an NSAC target, SMF 305 may send an nsacf_nsac_numofpdusupdate request (which may include at least one of S-nsai, UE ID, PDU session ID, and update flag=update) message to nsaf 306 (step 340).

When the update flag value of the received message is INCREASE and the number of PDU sessions established for S-NSSAI of the received message has reached the maximum number of PDU sessions established for S-NSSAI, NSACF 306 may include information in the result value indicating that the maximum number of PDU sessions established for the corresponding S-NSSAI has been reached and is not available and send the information to SMF 305 (step 345). In this case, the message may be an nnssacf_nsac_numofpdusupdate response message.

The SMF 305 may send a nudm_sdm_get request (which may include at least one of SUPI, DNN, S-nsai or SM subscription data) to the UDM 308 to request SM subscription data for the UE 301 (step 350). In this case, the information requesting replacement of S-NSSAI may be included in the nudm_sdm_get request message in the following case: in accordance with a determination of the local configuration of the SMF 305, in case the ongoing UE registration procedure is a registration due to a movement from the first system (e.g., EPS) to the second system (e.g., 5 GS), in case the response message in step 345 includes information that S-nsai is not available, and so on.

The UDM 308 may send subscription information for the alternate NSSAI including the S-NSSAI included in the message received from the SMF 305 to the SMF 305 in the nudm_sdm_get response message (step 355). The UDM 308 may include an alternative S-NSSAI if: from the determination of the local configuration of the UDM 308, and in the case where the SMF 305 requests replacement of S-NSSAI, etc.

In this case, according to an embodiment, the UDM 308 may obtain information to be transmitted to the SMF 305 from a UDR (not shown) and transmit the information to the AMF 303.

SMF 305 may send an nsmf_pduse_createsmcontext response message to AMF 303 (step 360). In this case, the reason for the message may include information indicating that the SM context creation fails by reaching the maximum number of PDU sessions established for the S-nsai and the alternate S-nsai.

When information indicating that SM context creation failed due to reaching the maximum number of PDU sessions established for S-nsai and alternate S-nsai is included in the cause value of the message from SMF 305, AMF 303 may select one of S-nsais included in allowed nsais among the alternate S-nsais of failed S-nsais to try PDU session creation again (step 370).

AMF 303 may again select SMF based on the newly selected S-NSSAI (step 380).

AMF 303 may send an Nsmf_PDUSation_CreateSMContext request message to the newly selected SMF 305 (step 390). For ease of description, fig. 3 shows several SMFs as one SMF. The SMF newly selected by AMF 303 in step 380 may be a different SMF than the SMF selected by AMF 303 in step 320.

The remaining PDU session creation process may continue (step 395).

In one embodiment shown in fig. 3, because the alternate slices are provided by UDM 308 providing subscriber information for the session during the PDU session, there is the advantage that the alternate slices can be provided based on information about the sub-divided session of the subscriber.

Fig. 4 illustrates a method by which an AMF re-selects S-nsai for a PDU session through alternative S-nsai information in a PDU session establishment procedure when the alternative S-nsai information is defined and provided in an nsaacf according to an embodiment of the present disclosure.

Referring to fig. 4, ue 401 may include a PDU session establishment request message in a NAS message and send it (through base station 402) to AMF 403 for a PDU session establishment procedure (step 410). NAS messages refer to messages between UE 401 and AMF 403. The NAS message may include at least one of S-NSSAI, DNN, or PDU session ID.

AMF 403 may select SMF 405 based on at least one of DNN or S-NSSAI (step 420).

AMF 403 may send an Nsmf_PDUSion_CreateSMContext request (which may include at least one of an S-NSSAI, DNN, PDU session ID or PDU session establishment request message) to the selected SMF 405 (step 430).

When the S-nsai included in the message received from AMF 403 is an NSAC target, SMF 405 may send an nsacf_nsac_numofpdusupdate request (which may include at least one of S-nsai, UE ID, PDU session ID, or update flag=update) message to nsaf 406 (step 440).

In this case, the information requesting replacement of S-nsai may be included in the nnssacf_nsac_numofpdusupdate request message in the following cases: in accordance with a determination of the local configuration of the SMF 405, the UE registration procedure in progress is in the case of registration due to movement from a first system (e.g., EPS) to a second system (e.g., 5 GS).

When the update flag value of the received message is INCREASE and the number of PDU sessions established for S-NSSAI of the Nnsacf_NSAC_NumOfPDUsUpdate request message has reached the maximum number of PDU sessions established for S-NSSAI, NSACF 406 may include a value in the result value indicating that the maximum number of PDU sessions established has been reached to send the result value to SMF 405 (step 445). Furthermore, nsaf 406 may include an alternative S-nsai if: in the event that S-nsai included in the message from SMF 405 is not available, in the event that SMF 405 requests replacement of S-nsai, and so on, based on the determination of the local configuration of nsaf 406.

The nsaf 406 may include S-nsais that do not reach the maximum number of established PDU sessions among the stored substitute S-nsais of the corresponding S-nsais, or S-nsais that are not targeted by NSAC NSSAI among the substitute S-nsais of the message sent to the SMF 405.

SMF 405 sends an nsmf_pduse_createsmcontext response message to AMF 403 (step 450). In this case, the reason for the message may include information received in step 445 indicating that the SM context creation failed by reaching the maximum number of PDU sessions established for S-nsai and alternate S-nsai.

When information indicating that SM context creation failed due to reaching the maximum number of PDU sessions established for S-nsai and alternate S-nsai is included in the cause value of the message from SMF 405, AMF 403 may select one of S-nsais included in allowed nsais among the alternate S-nsais of failed S-nsais to try PDU session creation again (step 460).

AMF 403 may again select SMF based on the newly selected S-NSSAI (step 470).

AMF 403 may send an Nsmf_PDUSation_CreateSMContext request message to the newly selected SMF 405 (step 480). For ease of description, fig. 4 shows several SMFs as one SMF. The SMF newly selected by AMF 403 in step 470 may be a different SMF than the SMF selected by AMF 403 in step 420.

The remaining PDU session creation process may continue (step 490).

In one embodiment shown in fig. 4, because nsaf 406, which knows the load information on the network slice, provides an alternate slice of the PDU session (e.g., an alternate SNSSAI), there is the advantage that the alternate slice can be determined/provided taking into account the load on the network slice. For example, nsaacf 406 may provide SMF 405 with alternate slices with a sufficiently large number of allowable PDU sessions remaining.

Fig. 5 illustrates a configuration of a UE according to an embodiment of the present disclosure.

Referring to fig. 5, a UE according to an embodiment of the present disclosure may include a transceiver 520 and a controller 510 for controlling the overall operation thereof. Transceiver 520 may include a transmitter 525 and a receiver 523.

Transceiver 520 may transmit signals to and receive signals from other network entities.

The controller 510 may control the UE to perform any of the operations of the above embodiments. The controller 510 and transceiver 520 do not necessarily have to be implemented in separate modules and may be implemented in a single component in the form of a single chip. The controller 510 and the transceiver 520 may be electrically connected. For example, the controller 510 may be a circuit, a dedicated circuit, or at least one processor. Furthermore, the operation of the UE may be achieved by providing a memory device storing corresponding program codes in any of the components in the UE.

The network entity of the present disclosure is a concept including a network function according to a system embodiment.

Referring to fig. 6, a network entity according to an embodiment of the present disclosure may include a transceiver 620 and a controller 610 for controlling the overall operation of the network entity. The transceiver 620 may include a transmitter 625 and a receiver 623.

The transceiver 620 may transmit signals to and receive signals from other network entities.

The controller 610 may control the network entity to perform any one of the operations of the above embodiments. The controller 610 and the transceiver 620 do not necessarily have to be implemented in separate modules and may be implemented in a single component in the form of a single chip. The controller 610 and the transceiver 620 may be electrically connected. For example, the controller 610 may be a circuit, a dedicated circuit, or at least one processor. Furthermore, the operation of the network entity may be implemented by providing a memory device storing corresponding program code in any component of the network entity.

The network entity may be any one of a base station (RAN), AMF, SMF, UPF, PCF, NSACF, UDM and UDR.

It should be noted that the construction diagrams, diagrams of control/data signal transmission methods, operation process diagrams, and construction diagrams shown in fig. 1 to 6 are not intended to limit the scope of the present disclosure. That is, all components, entities, or operational steps described in fig. 1 to 6 should not be construed as necessary components to implement the present disclosure, and the present disclosure may be implemented within a range that does not impair the essence of the present disclosure even by including only some components.

The operations of the network entity or UE described above may be implemented by providing a memory device storing corresponding program code in any of the components in the network entity or UE device. That is, the controller of the UE device or the network entity may perform the above-described operations by reading and executing program codes stored in the memory device by a processor or a Central Processing Unit (CPU).

The various components and modules of the network entities, base stations, or UE devices described in this specification may operate using hardware circuitry, such as complementary metal oxide semiconductor based logic circuitry, firmware, software, and/or combinations of hardware and firmware and/or software, inserted into machine readable media. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates, and application specific integrated circuits.

In the detailed description of the present disclosure, although specific embodiments have been described, various modifications are possible without departing from the scope of the disclosure. Thus, the scope of the disclosure should not be limited to the described embodiments, but should be defined by the claims and the equivalents of the claims.

While the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to embrace such alterations and modifications that fall within the scope of the appended claims.

Claims

1. A method performed by an access and mobility management function (AMF) in a communication system, the method comprising:

receiving a first message from a terminal requesting establishment of a Protocol Data Unit (PDU) session associated with a first network slice;

identifying whether the first network slice is unavailable;

selecting a second network slice that replaces the first network slice if the first network slice is not available; and

a second message for establishing a PDU session is sent to a Session Management Function (SMF) associated with the second network slice.

2. The method of claim 1, further comprising:

the SMF is selected based on the second network slice.

3. The method of claim 1, wherein the first message comprises single network slice selection assistance information (S-nsai) for the first network slice.

4. The method of claim 1, further comprising:

information about at least one network slice and information about at least one alternate network slice associated with each of the at least one network slice are received from a Unified Data Management (UDM).

5. The method of claim 1, wherein identifying whether the first network slice is unavailable comprises:

receiving a third message from the SMF comprising information indicating whether the first network slice is unavailable; and

based on the information, it is identified whether the first network slice is unavailable.

6. The method of claim 5, wherein the third message further comprises information about a second network slice that is a substitute network slice for the first network slice.

7. The method of claim 1, wherein the first network slice is unavailable in the event that a number of established PDU sessions is equal to a maximum number of PDU sessions for the first network slice or a number of registered terminals is equal to a maximum number of available terminals for the first network slice.

8. An access and mobility management function (AMF) in a communication system, the AMF comprising:

a transceiver; and

a controller coupled with the transceiver and configured to:

a first message is received from a terminal requesting establishment of a Protocol Data Unit (PDU) session associated with a first network slice,

identify whether the first network slice is unavailable,

selecting a second network slice that replaces the first network slice if the first network slice is not available, and

9. The AMF of claim 8, wherein the controller is further configured to select an SMF based on a second network slice.

10. The AMF of claim 8, wherein the first message comprises single network slice selection assistance information (S-nsai) for the first network slice.

11. The AMF of claim 8, wherein the controller is further configured to receive information about at least one network slice and information about at least one alternate network slice associated with each of the at least one network slice from a Unified Data Management (UDM).

12. The AMF of claim 8, wherein the controller is further configured to:

13. The AMF of claim 12, wherein the third message further comprises information about a second network slice that is a substitute network slice for the first network slice.

14. The AMF of claim 8, wherein the first network slice is unavailable in the event that a number of PDU sessions established is equal to a maximum number of PDU sessions of the first network slice or a number of registered terminals is equal to a maximum number of available terminals of the first network slice.