CN112352460B

CN112352460B - Method for controlling terminal for cellular IoT service in 5G mobile communication system

Info

Publication number: CN112352460B
Application number: CN201980042308.3A
Authority: CN
Inventors: 金成勋; 白令教; 孙仲济; 李淏娟
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2018-05-14
Filing date: 2019-05-14
Publication date: 2024-03-22
Anticipated expiration: 2039-05-14
Also published as: CN112352460A; KR20190130487A; KR20190130473A

Abstract

The present disclosure relates to communication technologies and systems thereof that fuse a 5G communication system supporting higher data transmission rates than a 4G system with IoT technologies. The present disclosure may be applied to smart services based on 5G communication technology and IoT-related technology, such as smart homes, smart buildings, smart cities, smart or networked automobiles, healthcare, digital education, retail, and security-related services. A method for effectively controlling a terminal for a cellular IoT service in a 5G mobile communication system is disclosed.

Description

Method for controlling terminal for cellular IoT service in 5G mobile communication system

Technical Field

A detailed description of embodiments of the present disclosure is provided mainly with reference to a New RAN (NR) and packet core as a radio access network and core network (5G system, 5G core network, or next generation core network (NG core)) in a 5G mobile communication standard specified by 3 GPP. However, the subject matter of the present disclosure may be slightly modified without departing from the scope of the present disclosure, and may be applied to other communication systems having similar technical backgrounds. Modifications and applications thereof may be determined by those skilled in the art.

The CIoT service of the 5G system may support a function of transmitting data between the UE and the core network via a non-access stratum (NAS) message such that the core network transmits it to an external data network, and may support a function of transmitting data transmitted from the UE to an external server through a network exposure function (network exposure function, NEF).

In addition, 5G systems also provide factory automation services called industrial IoT. Robots and other devices for factory automation can communicate with each other via a cellular network and can fall within the broad scope of IoT devices. These devices may require time-sensitive data communications. For example, a device may need to send status information and command messages to another device over a network within 10ms and may be configured to provide the required status information at a predetermined time or to receive the required status information at a predetermined time.

In the following description, for ease of illustration, the present disclosure uses terms and names defined in the third generation partnership project long term evolution (3 GPP LTE) standard. However, the present disclosure is not limited by these terms and names, and may be applied in the same manner to systems conforming to other standards.

Background

In order to meet the demand for increased wireless data services since the deployment of 4G communication systems, efforts have been made to develop improved 5G communication systems or quasi-5G (pre-5G) communication systems. Therefore, a 5G or quasi 5G communication system is also referred to as a "super 4G network" or a "LTE-after-system". A 5G communication system is considered to be implemented in a higher frequency (millimeter wave) band (e.g., 60GHz band) in order to achieve a higher data rate. In order to reduce propagation loss of radio waves and increase transmission distance, beamforming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, massive antenna techniques are discussed in 5G communication systems. Further, in the 5G communication system, system network improvements based on advanced small cells, cloud Radio Access Networks (RANs), ultra dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), reception-side interference cancellation, and the like are underway. In the 5G system, hybrid FSK and QAM modulation (FQAM) as Advanced Code Modulation (ACM) and Sliding Window Superposition Coding (SWSC) have been developed, and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access technologies have also been developed.

As the internet of human-centric connected networks, where people generate and consume information, is now evolving towards the internet of things (IoT), where distributed entities, such as items, can exchange and process information without human intervention. Internet of everything (IoE) has emerged as a combination of IoT technology and big data processing technology through a connection with a cloud server. As technical elements, such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "security technology" have been demanded for IoT implementations, sensor networks, machine-to-machine (M2M) communication, machine Type Communication (MTC), and the like have been recently studied. Such IoT environments may provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated between connected items. IoT may be applied in a variety of fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, and advanced healthcare through fusion and integration between existing Information Technology (IT) and various industrial applications.

To this end, various attempts have been made to apply 5G communication systems to IoT networks. For example, techniques such as sensor networks, machine Type Communications (MTC), and machine-to-machine (M2M) communications may be implemented through beamforming, MIMO, and array antennas. The application of a cloud Radio Access Network (RAN) as the big data processing technology described above may also be considered as an example of a convergence between 5G technology and IoT technology.

Recently, as Long Term Evolution (LTE) and LTE-Advanced (LTE-Advanced) have been developed, methods and apparatuses for effectively controlling User Equipment (UE) in order to provide cellular IoT services in a 5G mobile communication system are needed.

Disclosure of Invention

Technical problem

In order to support CIoT service in a 5G mobile communication system, a method of supporting the following two services is provided.

AS one of IoT-related services provided in the 5G mobile communication system, if downlink data to be transmitted to a User Equipment (UE) is scheduled at a predetermined time (e.g., 9 am on monday, 12 am daily, etc.), a third party application server (hereinafter referred to AS) may provide corresponding scheduling information to the mobile communication network, so the mobile communication network can prepare data transmission to the UE at the corresponding time. The mobile communication network may perform control such that a time scheduled by the UE in the scheduling information is reachable or may protect resources for data transmission. The present disclosure provides a method in a mobile communication network that enables a corresponding UE to maintain a state of connection to the mobile communication network at a scheduled data transmission time. The method is particularly effective for IoT UEs that change to a state that is not reachable by the mobile communication network to reduce the amount of power consumed. The UE performing a predetermined operation to reduce the amount of power consumed may be a UE that turns on a modem and wakes up (e.g., a MICO mode) only when having data to be transmitted, or a UE that operates by negotiating with a mobile communication network to reduce the amount of power consumed and cannot receive a page from the network during a predetermined period of time.

As another IoT-related service used in 5G mobile communication systems, there is an industrial IoT for factory automation. Industrial IoT needs to transmit/receive data that is sensitive to transmit time. For example, there may be a requirement, such as a requirement to send data to the UE within 5ms, or a requirement to transmit data from the UE to the server within 10 ms. In the case of industrial IoT, private networks that only the corresponding factory can use may be configured and used. Further, a localization server may be prepared in a predetermined area of the factory in order to receive data from the UE, analyze the data, or transmit the data to the UE. If the server sends data to the UE, the network wakes the UE in an idle state, changes the UE into a connected state, allocates resources for data transmission, and sends the data. The process of changing the idle state to the connected state as described above may take time. AS another example, if downlink data to be transmitted to the UE is scheduled at a predetermined time (e.g., 9 a.m., 12 a.m., 10 minutes after the present, etc.), an application server (hereinafter, referred to AS) may provide scheduling information associated with a corresponding data transmission to the mobile communication network, so the mobile communication network can prepare the data transmission to the UE at the corresponding time. The mobile communication network may perform control such that a time scheduled by the UE in the scheduling information is reachable, may enable the UE to be in a connected state such that data transmission is immediately performed, or may secure resources for data transmission to the corresponding UE before changing the UE to the connected state. The present disclosure provides a method of changing a corresponding UE to a state of being connected to a mobile communication network in advance based on a predetermined data transmission schedule or providing scheduling information indicating when to change to a state of being connected to a network to a UE in a mobile communication network.

AS another CIoT service provided in the 5G mobile communication system, a function of the UE for transmitting non-IP data to the AS via the NEF may be supported. This is the delivery of non-IP data, abbreviated as "NIDD". Alternatively, there may be a reliable data service, abbreviated as "RDS", that provides a reliable data transmission service between the UE and the NEF. As described above, to support the function of transmitting IoT small data via the NEF, the NEF and the SMF may need to establish a connection for data transmission, or may need to exchange related information. According to conventional methods, the configuration associated with NIDD is performed between the third party AS and the NEF. Subsequently, if the UE establishes a PDU session associated with the NIDD service with the SMF, the SMF may perform activation of the NIDD service with the NEF. If NIDD configuration is not performed in advance between the third party AS and the NEF, information associated with the NIDD configuration is not present in the network. Accordingly, the SMF may not approve the PDU session establishment procedure performed by the UE and may reject the corresponding request. In addition, after performing NIDD configuration between the third party AS and the NEF, the third party AS may need to send application layer signaling so that the UE may perform PDU session establishment for NIDD services or may need to perform device triggering using the 3GPP network. In order to transmit application layer signaling before the UE establishes a PDU session for NIDD, a PDU session different from the PDU session for NIDD needs to be established. In addition, the UE needs to support SMS in order to support device triggering. In other words, the limitations of current systems require that only IoT UEs developed at low cost support additional functionality. This may deteriorate the activation of IoT UEs. In the case where the UE establishes a PDU session for the "data transfer service via NEF" in order to establish a connection between the SMF and the NEF associated with the "support data transfer service via NEF", the present disclosure provides a procedure of completing the PDU session establishment procedure without performing NIDD configuration between the third party AS and the NEF, and activating the NIDD service between the SMF and the NEF when NIDD configuration is subsequently performed.

As another CIoT function used in the 5G mobile communication system, there may be a low-rate control function. According to this function, ioT UEs frequently send small amounts of data in order to prevent network congestion. The number of data packets that the UE can transmit per time unit or the amount of data that the UE can transmit per time unit may be set for the network and the value may be transmitted to the UE. The UE receiving the value may limit its own data transmission based on the set value. However, this function is suitable for UEs using CIoT functions, and may not need to be applied to UEs using broadband communication such as smartphones or tablets. Thus, there is a need for a method in which a network recognizes the type of a UE and determines whether to apply a low rate control function. This is provided in the present disclosure.

Technical proposal

According to one aspect of the disclosure, a method of establishing a Protocol Data Unit (PDU) session by a Session Management Function (SMF) in a wireless communication system may include: receiving a first message from an Access Management Function (AMF), the first message containing Radio Access Technology (RAT) type information indicating a RAT to which a User Equipment (UE) is currently accessing; determining whether to apply a small data rate control function to the UE based on the RAT type information; and sending a second message to the AMF, the second message containing information associated with whether to apply the small data rate control function to the UE.

In this instance, the small data rate control function is a function in which the UE controls transmission of small data based on a set value set in the network, and the set value may contain at least one of the number of data packets that the UE can transmit per hour and the amount of data that the UE can transmit per hour.

A Protocol Configuration Option (PCO) including the set value may be configured, a PCO may be included in the second message and may be transmitted to the AMF, and the PCO may be included in a PDU session establishment acceptance message and may be transmitted to the UE.

The PDU session establishment method through the SMF may include: subscription information associated with the UE is received from a User Data Management (UDM), wherein the subscription information may be considered together with the RAT type information to determine whether to apply the small data rate control function to the UE.

The RAT type information may indicate a RAT that the UE accesses among narrowband IoT (NB-IoT), wideband EUTRAN (WB-EUTRAN), new Radio (NR), new wireless IoT (NR-IoT), and LTE for machine type communication (LTE-M).

According to another aspect of the disclosure, a method of establishing a Protocol Data Unit (PDU) session by a User Equipment (UE) in a wireless communication system may include: transmitting a PDU session establishment request message to an Access Management Function (AMF), the PDU session establishment request message including Radio Access Technology (RAT) type information indicating a RAT to which the UE is currently accessing; receiving information indicating whether to apply a small data rate control function to the UE and determined based on the RAT type information; and controlling small data transmission of the UE according to a setting value set in the network based on information indicating whether the small data rate control function is applied to the UE.

In this instance, the set value may include at least one of the number of data packets that the UE can transmit per time unit, and the amount of data that the UE can transmit per time unit.

The PDU session establishment method of the UE may further include: a PDU session establishment acceptance message is received, the PDU session establishment acceptance message including a Protocol Configuration Option (PCO) associated with the set value.

In this example, it may be determined whether to apply the small data rate control function to the UE based on subscription information associated with the UE and the RAT type information provided from User Data Management (UDM).

According to another aspect of the present disclosure, a Session Management Function (SMF) for establishing a Protocol Data Unit (PDU) session in a wireless communication system may include: a transceiver; and a controller configured to: performing control so as to receive a first message from an Access Management Function (AMF), the first message containing Radio Access Technology (RAT) type information indicating a RAT to which a User Equipment (UE) is currently accessing; determining whether to apply a small data rate control function to the UE based on the RAT type information; and performing control so as to transmit a second message to the AMF, the second message containing information associated with whether to apply the small data rate control function to the UE.

According to another aspect of the present disclosure, a User Equipment (UE) for establishing a Protocol Data Unit (PDU) session in a wireless communication system may include: a transceiver; and a controller configured to: performing control so as to transmit a PDU session establishment request message to an Access Management Function (AMF), the PDU session establishment request message containing Radio Access Technology (RAT) type information indicating a RAT to which the UE is currently accessing; performing control so as to receive information indicating whether to apply a small data rate control function to the UE and determined based on the RAT type information; and controlling small data transmission of the UE according to a setting value set in the network based on information indicating whether the small data rate control function is applied to the UE.

Beneficial technical effects

According to the present disclosure, a 5G system may support an operation of connecting a User Equipment (UE) to a network at a time scheduled in scheduling in order to transmit data to the UE according to scheduling requested from a third party AS providing an application service. Thus, without any additional operation of controlling the operation of the UE, the UE wakes up at a predetermined time and connects to the network by connecting only to the 3GPP network.

According to the present disclosure, the 5G system may activate the NIDD service by removing the dependency between the PDU session establishment procedure for NIDD performed by the UE and the NIDD configuration procedure performed between the third party AS and the NEF, regardless of the order of the PDU session establishment procedure and the NIDD configuration procedure.

Furthermore, this may not require support of application layer signaling or other additional functionality to enable the UE to use NIDD services. Furthermore, this may not require that the 5G system be enabled to support NIDD services for the UE depending on another function.

According to the present disclosure, the 5G system may keep the UE in a network-connected state for a predetermined time in order to support time-sensitive mobile communication services (e.g., factory automation IoT).

According to the present disclosure, the 5G system may determine UEs to which CIoT functions need to be applied, and may determine to apply only small data rate control functions to the corresponding UEs. Thus, UEs using broadband mobile data, such as smartphones or tablets, may not be limited by small data rate control.

Drawings

Fig. 1 is a diagram illustrating a method in which an AMF acquires scheduling information associated with scheduled data transmissions and provides corresponding times to a User Equipment (UE) in accordance with an embodiment of the present disclosure;

Fig. 2 is a diagram illustrating operations performed when a UE is already in an unreachable state in a case where an AMF acquires scheduling information associated with scheduled data transmission according to an embodiment of the present disclosure;

fig. 3 is a diagram illustrating operations performed when a UE is already in an unreachable state in a case where an SMF provides scheduling information associated with scheduled data transmissions to an AMF, according to an embodiment of the present disclosure;

fig. 4 is a diagram illustrating a method in which, when a UE and an SMF perform an establishment of a PDU session associated with NIDD, the SMF recognizes that no NIDD configuration exists and allows a corresponding PDU session establishment request but performs deactivation, according to an embodiment of the present disclosure;

fig. 5 is a diagram illustrating an operation in which, when a PDU session is established, an SMF determines whether to apply small data rate control based on information received from an AMF, UDM, or PCF and reports it to a UE, according to an embodiment of the present disclosure;

fig. 6 is a diagram illustrating operations in which when a UE changes RAT type, the UE reports it to an SMF, which determines whether to apply small data rate control and informs the UE based on the changed RAT type, according to an embodiment of the present disclosure;

Fig. 7 is a diagram illustrating a structure of a UE according to an embodiment of the present disclosure; and

fig. 8 is a diagram illustrating a structure of a network entity according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, a detailed description of known functions or configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear. The terms to be described below are terms defined in consideration of functions in the present disclosure, and may be different according to users, user intention, or habits. Accordingly, the definition of the terms should be based on the contents of the entire specification.

The advantages and features of the present disclosure and methods of accomplishing the same may become apparent by reference to the following detailed description of embodiments taken in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following examples are provided solely for the purpose of fully disclosing the present disclosure and informing those skilled in the art the scope of the present disclosure and are defined solely by the scope of the appended claims. The same or similar reference numbers designate the same or similar elements throughout the specification.

The entities used in this disclosure are as follows.

A User Equipment (UE) is connected to a Radio Access Network (RAN) and accesses a device performing a mobility management function of a core network device of 5G. In this disclosure, this is referred to as an access and mobility management function (AMF). This may be a function or device responsible for both access to the RAN and mobility management of the UE.

SMF is the name of the network function that performs the session management function. The AMF is connected to a Session Management Function (SMF), which routes session related messages associated with the UE to the SMF. The SMF connects to a User Plane Function (UPF), allocates user plane resources to be provided to the UE, and establishes a tunnel for data transmission between a Base Station (BS) and the UPF.

NRF, an abbreviation of a network repository function, stores information associated with NF installed in a mobile communication carrier network, and reports information associated therewith. NRF is connected to all NFs. When operating in an operator network, each NF performs registration on the NRF, and the NRF knows that the corresponding NF is operating in the network.

The NEF, which is an abbreviation of a network exposure function, performs a function of exposing an internal function and a service of a mobile communication carrier network to the outside. Thus, the NEF is connected to an external Application Server (AS) such that the NEF transmits events or information occurring from NFs in the network to the AS or transmits events or information requested from the AS to an internal NF.

UDR is an abbreviation for user data repository and performs the same function as HSS of 4G networks. It may store subscription information of the UE or a context of use of the UE in the network.

As background of the present disclosure, the function of supporting CIoT service is as follows.

Function of data transmission via control plane signaling: it is also inefficient for IoT UEs to send or receive small amounts of data, and therefore, to establish user plane connections for small amounts of data transmission or reception is inefficient in terms of use of radio resources, and signaling of user plane connection establishment always occurs.

Accordingly, a technique of transmitting a small amount of data from a UE for CIoT service via control plane signaling has been developed. According to this technique, the UE may include data that it wishes to transmit in an SM-NAS message sent to the SMF, and may transmit it. The SMF receiving the data may transfer the corresponding data to the destination NF and support the data transfer.

In the same manner, if the data comes from outside, the UPF or the NEF may report to the SMF that the data directed to the UE has arrived and transfer the corresponding data to the SMF. The SMF receiving the data may include the corresponding data in an SM-NAS message transmitted to the UE and transmit it to the UE. For data transmission as described above, the UE and the SMF need to establish a PDU session, and the PDU session is used for a data transmission function via control plane signaling. Thus, in case of establishing a PDU session with the SMF, the UE may perform the procedure by including an indicator indicating a data transmission function via control plane signaling in the procedure.

non-IP data transfer services via NEF: the 5G mobile communication network may transfer the non-IP data transmitted from the UE to the third party AS via the NEF. The UE may include non-IP data in a NAS message to be transmitted to the SMF and transmit it to the SMF, which may transmit it to the NEF. The NEF may send it to the AS. If the AS sends data, the AS sends non-IP data associated with the UE to the NEF, and the NEF may send it to the SMF. The SMF may include the data in the NAS message and send it to the UE.

That is, the data route is UE-AMF-SMF-NEF-AS. The process of providing data transmission services to a predetermined UE and a predetermined AS via NEF for non-IP data transmission for IoT services is referred to AS "NIDD services".

non-IP data is a transport protocol in any form other than IP format. non-IP data may be used in order to reduce the capacity of the IP header too much compared to actual data, and may be a protocol for simple data transmission, such as a sensor network or the like. In addition, since the UE transmits data to the AS via the NEF, a protocol between the UE and the NEF may be used. This protocol supports reliable data transmission between the UE and the NEF and is therefore referred to as reliable data service, abbreviated RDS.

In other words, a service transmitting data via NEF is called "NIDD" or "RDS" in the 3GPP standard, and may be called by other names. However, the function of performing data transmission via the NEF corresponds to "a service of transmitting data via the NEF" used in the present disclosure, regardless of the name thereof. In this disclosure, a process of providing NIDD services via SMF is described.

Thus, in order to use the NEF and NIDD services, the UE may need to perform a PDU session establishment procedure with the SMF. The PDU session establishment procedure is a procedure associated with a predetermined data network performed between the UE and the SMF. If the PDU session is for NIDD service, the UE may perform a PDU session establishment procedure with the SMF by including an indicator corresponding to the NIDD service or a data network name associated with the NIDD service in the procedure.

Support service for scheduled data transmission (scheduled downlink data communication service): the 5G mobile communication network may receive scheduling information associated with scheduled downlink data transmission times of a predetermined UE or group from a third party AS. The third party AS is an application server that exists outside the scope of the 5G mobile communication network element.

For example, in the case where the industrial IoT supports data transmission using a 5G mobile communication system, an application server operating for the industrial IoT service may be considered a third party AS from the perspective of the 5G mobile communication system. The third party AS may provide scheduling information to the 3GPP network via the NEF via the "expected UE behavior" of the provisioning API or the time the UE needs to be available for data reception (i.e. the time the UE can reach the network, be able to receive pages or need to be in a connected state). The scheduling information may include a plurality of pieces of scheduling information. The pieces of scheduling information may be, for example, 9 am on monday, 12 am every day, 10 hours after the current time, 20 minutes after the current time, and so on.

The network that receives it may perform configuration such that when the UE wants to use a power saving state (a state in which the UE is not reachable from the network in order to reduce power consumption, that is, a state in which the UE does not perform operations related to network connection, such as a state in which the paging channel is not monitored, etc.), the network can detect the UE (reachable) at the scheduled communication time.

For example, by comparing the scheduled communication time to a time at which the UE periodically reports reachability to the network (e.g., a periodic registration update timer), the network may set a subsequent periodic registration update time appropriate for the scheduled communication time. As another example, if the scheduled communication time is before the subsequent periodic registration update time of the UE, the network does not allow the power saving function of the UE so that the UE is reachable at the corresponding time.

Alternatively, in the case where the UE uses industrial IoT services, that is, in the case where the subscription information of the UE indicates that the UE is for industrial IoT, or indicates that the UE is using a dedicated network established for industrial IoT, or the 5G network is only industrial IoT operation, the 5G network receiving the scheduling information from the AS may determine that the corresponding UE is to use time-sensitive data communication.

Accordingly, the 5G network may perform configuration such that the UE is ready for data transmission/reception at a time scheduled in the scheduling information received from the AS. For example, based on scheduling information associated with data transmission received from the AS, e.g., 9 am on monday, 12 am on day, 10 minutes after the current time, etc., the 5G network may configure the scheduling information for the UE such that the UE changes to a connected state based on the corresponding schedule, or may perform paging for the UE such that the UE changes to a connected state immediately before the corresponding schedule.

Fig. 1 illustrates a method in which an AMF acquires scheduling information associated with scheduled data transmissions and provides corresponding times to a UE, according to an embodiment of the present disclosure.

The third party application server or AS may set the scheduled communication time of the 5G network. The AS may send it by sending a message directly to the UDM or AMF, or may send corresponding information to the UDM, AMF or SMF via the NEF. The AS may configure the scheduled communication time into multiple schedules and may send them.

For example, the AS may send pieces of scheduling information to the 5G network, such AS 0 per day: 00. 12 per day: 30 or 20 minutes after the current time, or an absolute time value indicating a time after the current time (e.g., 7 months 10 days 2018, UTC 20: 00).

Referring to fig. 1, the present disclosure assumes that scheduled communication times are stored in a context associated with a User Equipment (UE) 110 included in a UDM, and in operations S101 and S103, the AMF 120 or the SMF 130 may acquire the scheduled communication times.

Alternatively, in operations S101 and S103 of fig. 1, the NEF directly transmits the scheduled communication time associated with the predetermined UE to the AMF 120 or the SMF 130, so that the AMF 120 or the SMF 130 may obtain the corresponding value. The UDM may classify the corresponding information obtained from the NEF as a session management context and may store it.

The scheduled communication time is provided from the third party to the UDM in association with a predetermined UE indicated by an external ID or an external group ID. Thus, the UDM may store a scheduled communication time value for each external ID or external group ID of the UE in the SM context. This is because the UE has a plurality of external IDs or external group IDs. Alternatively, the scheduled communication time may be provided from the third party to the UDM as a value associated with a predetermined Data Network Name (DNN) of the predetermined UE indicated by the external ID or the external group ID. In this case, the UDM may store a scheduled communication time value based on the DNN value of each external ID or external group ID of the UE in the SM context. This is to support the following scenario: wherein the UE has a plurality of external IDs or external group IDs, or wherein subscription information is set such that the UE can use a plurality of DNNs for NIDD services.

That is, the scheduled communication time is configured for each UE in subscription information in the UDM, and a plurality of pieces of scheduled communication time information may be configured for each external ID or external group ID, or for each external ID or external group ID and each DNN.

Operation S105 is a subsequent operation performed after the SMF 130 obtains a scheduled communication time from the UDM as an SM context associated with the UE 110, or after the SMF 130 obtains a predetermined communication time from the NEF. The SMF 130 may determine when to perform downlink data transmission to the corresponding UE 110 based on the scheduled communication time. The smf 130 may transmit a message requesting the reachability of the UE 110 to the AMF 120 responsible for mobility management of the UE, since the UE 110 needs to be reachable by the 5G network at a corresponding time. If the message is one of the APIs provided by the AMF 120 and includes a meaning that the SMF 130 requests the AMF 120 to enable the reachability of the predetermined UE at the scheduled communication time, any message may be used as such a message in the present disclosure, although the name of the message is different from that of the operation S105.

In operation S105, the SMF 130 may contain an ID of the UE 110 (an ID enabling the AMF to identify the UE, for example, a subscription hidden identifier (sui) or a subscription permanent identifier (SUPI) (previous IMSI), or an external ID), may contain the scheduled communication time obtained in operation S103, and may contain a PDU session ID indicating a corresponding PDU session. The reason for including the PDU session ID is that if the UE 110 performs data communication using a plurality of PDU sessions, the UE 110 needs to determine a PDU session to be activated when the UE 110 transmits a service request at a scheduled communication time and wakes up. In addition, if the UE performs data communication using multiple PDU sessions, the AMF 120 may need to identify a PDU session associated with the scheduled communication time. If the AMF 120 receives a plurality of scheduled communication time values from a plurality of SMFs or a single SMF, the AMF 120 may use the PDU session ID contained in the message of operation S105 in order to identify a scheduled communication time value of each PDU session.

The AMF 120 receiving the message of operation S105 or the AMF 120 identifying the scheduled communication time associated with the UE 110 via operation S101 may store the corresponding information in the context of the UE 110. If UE 110 requests an operation to leave a reachable network state during a predetermined period of time in order to reduce the amount of power consumed, AMF 120 may use a scheduled communication time value to enable UE 110 to wake up at the predetermined time and be reachable by the network. Alternatively, if the UE 110 uses time-sensitive data communication, the AMF 120 may enable the UE 110 to change to a network-connected state at a scheduled time in the scheduling information based on the scheduled communication time value.

UE 110 may suspend monitoring the operation of the paging channel (e.g., MICO mode, PSM in a 4G system) or monitor the paging channel (e.g., idle mode DRX) only for a predetermined time in order to reduce the amount of power consumed. To this end, UE 110 may negotiate with AMF 120 and may perform the negotiation via a registration procedure.

In operation S107, the UE 110 negotiates the use of the MICO mode. However, this may include the use of other functions that UE 110 needs to negotiate with AMF 120 in order to reduce the amount of power consumed. For example, there may be 5G power saving mode, 5G DRX, 5G extended DRX, etc.

For ease of description, the description will be provided with reference to the MICO mode. The MICO mode is the following mode: wherein when UE110 changes to idle mode, the UE no longer monitors all paging channels and UE110 is undetectable in the 5G network. That is, the MICO mode is a mode in which the UE110 changes to an unreachable state. If UE110 needs to send data or signaling, UE110 may wake up at the periodic registration update time set by the network and may access the 5G network again. Thus, the network does not wake up UE110 until the registration procedure performed at the UE110 at the periodically set time occurs. UE110 may include an indicator indicating that the UE will use the MICO mode in the registration request process of operation S107.

Operation S107 may be a registration procedure performed based on mobility of the UE110, or may be a registration procedure performed at a periodic time, except for negotiating with the AMF 120 in order to reduce the amount of power consumed. Further, the operation may be a registration procedure performed by UE110 to synchronize with the network. This operation may include all cases where UE110 performs a registration procedure with AMF 120 under other conditions.

In operation S109, the AMF 120 may determine whether to allow the MICO mode of the UE 110. If the scheduled communication time value of UE110 will soon come, AMF 120 may not allow the MICO mode of UE110 so that UE110 does not enter the MICO mode and remains continuously in an reachable state.

If the scheduled communication time value of the UE 110 will arrive a sufficient amount of time after the UE 110 enters the MICO mode, the AMF 120 may allow the MICO mode so that the UE 110 can enter the MICO mode and reduce the amount of power consumed. Alternatively, if the UE 110 uses time-sensitive data communication, operation S109 may be omitted. If time sensitive data communication is used, the function of reducing the amount of power consumed may not be used. Accordingly, the AMF 120 does not determine whether the MICO mode is allowed, and may perform operation S111 with respect to the UE 110.

In operation S111 according to an embodiment of the present disclosure, the AMF 120 may set a wake-up time for the UE 110 for which the MICO mode is allowed. Alternatively, the AMF 120 may set the wake-up time for a general UE not using the MICO mode or a UE using time-sensitive data communication. The wakeup time may be set based on a predetermined communication time value, and the AMF 120 may set a value indicating a time slightly earlier than the scheduled communication time. In this way, delays may occur when considering that UE 110 accesses the network. The wake-up time provided to UE 110 may be expressed as an absolute time. For example, the wake-up time may be expressed as universal coordinated time (UTC). The time value may be set to year/month/day/minute. Alternatively, the wake-up time may be expressed as a value corresponding to the time zone of the network in which the UE is currently accessing.

For example, in case of korea, the wake-up time may be represented by KST and the time value may be set to year/month/day/minute. Along with the wake-up time, an indicator may be included that indicates whether the corresponding time is based on UTC or a time zone in which the UE is currently accessing the network. The UE can distinguish it and if the UE moves to a country belonging to a different time zone, another time zone can be suitably applied. For example, in the case where the UE moves from korea to china, if UTC is used, the UE may use the same value. However, if the UE receives a value corresponding to the KST, the UE needs to change the value to CST corresponding to the standard time of china. The wake-up time is not limited by name and may be information provided from the AMF and indicating the time the UE needs to be reachable by the network. In other words, the wake-up time is information indicating a time at which the UE needs to change to monitor the state of the paging channel, or a time at which the UE needs to change to the connection state by performing a service request or a registration update procedure with the network, or the like.

The wake-up time may include a plurality of pieces of scheduling information. For example, a plurality of pieces of scheduling information expressed as absolute time values, such as 13 of Y days of X month: 00. 9 on X month and X day: 00, etc. As another example, pieces of scheduling information that are not expressed as absolute time values, such as at 9 points per day, 0 point in monday early morning, or z minutes after the current time, etc., may be included.

In operation S113, the AMF 120 may transmit the wake-up time determined in operation S111 and an indicator indicating that the MICO mode is allowed to the UE 110. In case that the UE uses time-sensitive data communication, the AMF 120 may transmit the wake-up time determined in operation S111 regardless of whether the MICO mode is allowed. The UE 110 that receives the request may determine that the UE itself needs to be reachable by the network, may send a service request to change to a connected state, or may determine to perform a registration update procedure.

The modem of UE 110 continuously stores time information and may perform a predetermined operation when a corresponding time is reached. The time value indicating the time that has elapsed is no longer valid. If UE 110 receives time values associated with multiple schedules, UE 110 may determine that the time value indicating the time that has elapsed is invalid, may determine that the time value indicating the time that has not arrived is valid information, and may check whether the corresponding time has arrived.

In operation S115, the UE 110 reports completion of the registration procedure. This may be performed when an ID (e.g., 5G-GUTI) associated with UE 110 is newly allocated, etc., or may be omitted in order to simplify the procedure.

After the registration procedure is completed, the UE 110 allowed to operate in the MICO mode may change to an IDLE (IDLE) state and operate in the MICO mode. When UE 110 is operating in the MICO mode, the network cannot page UE 110. If the UE 110 is operating in a long DRX cycle period (cycle) instead of the MICO mode, the network cannot page the UE 110 when the UE 110 is operating in a DRX sleep cycle period. However, if the UE has data or signaling to send to the network, the UE 110 may wake up at any time and may communicate with the network. This operation may not affect the wake-up time value.

However, if there is a newly set scheduled communication time value for the AMF 120 while performing operation S117, the AMF 120 may update the wake-up time of the UE 110. Via a registration procedure or a UE configuration update procedure, AMF 120 may send a new wake-up time to UE 110, and UE 110 may replace the existing value with the newly received wake-up time value. The above relates to exception handling and is not shown in the drawings of the present disclosure, but may occur during operation S117.

According to embodiments of the present disclosure, UE 110 may wake up at a time corresponding to the set wake-up time to be reachable through the network. The modem of UE 110 continuously stores time information and may perform a predetermined operation when a corresponding time is reached. The time value indicating the time that has elapsed is no longer valid. If the UE 110 receives time values associated with a plurality of schedules, the UE 110 determines that the time value indicating the time that has elapsed is invalid, determines that the time value indicating the time that has not arrived is valid information, and checks whether the corresponding time has arrived.

The operation performed by UE 110 reachable through the network may be two operations as follows. First, the UE 110 transmits a service request or a registration request to the AMF 120. UE 110 may wake up and access the network and may send a service request or a registration request to change to a connected state. The AMF 120 receiving it may change the UE 110 to a connected state and may trigger the corresponding SMF 130 suitable for the PDU session or DNN in which the scheduled communication time is set so as to activate the user plane of the UE 110 or the data path of the UE and thus perform the scheduled downlink data transmission.

Second, UE 110 enables listening to the paging channel. Since scheduled downlink communication is planned, the AMF 120 may perform paging of the UE 110 if downlink data regarding the UE 110 is received at a corresponding time. Accordingly, the UE 110 monitors the paging channel for a predetermined period of time from the wake-up time, and if downlink data arrives at the scheduled time, the UE 110 receives a page from the AMF 120 and transmits a service request. If there is no paging for a predetermined period of time, the UE returns to the power saving state again. In this example, UE 110 maintains the CM-IDLE state. The predetermined period of time is based on basically setting a set value for UE 110. Alternatively, in operation S113, the AMF 120 may transmit information associated with a period in which the UE 110 needs to monitor the paging channel to the UE 110, and the UE 110 may perform an operation based on the information.

Operation S121 indicates that downlink data is received as scheduled at the scheduled communication time. The UPF 140 receives downlink data from the data network, reports it to the SMF 130, and activates a data path for transmitting data to the UE 110. The process is performed in operation S123 in response to the NW-initiated service request. In response to the NW-initiated service request, the network performs paging of UE 110, the awakened UE sends the service request and UE 110 changes to a connected state.

Alternatively, if the UE 110 first transmits a service request in operation S123, the AMF 120 determines an SMF setting a scheduled communication time matching the corresponding time, triggers the corresponding SMF 130 to activate a data path, and transmits downlink data via the activated PDU session. Alternatively, if the UE 110 transmits a registration request in operation S123, the AMF 120 maintains the connection of the UE 110 for a predetermined period of time until a downlink data notification associated with the UE 110 is received. If UE 110 returns to the idle state, UE 110 becomes unreachable.

If downlink data arrives for UE 110 while maintaining the connection of UE 110, and SMF 130 reports to AMF 120 that the data path associated with UE 110 needs to be activated, AMF 120 may perform a procedure to activate the corresponding data path. As another example, in operation S123, the UE 110 may include information associated with a PDU session whose data path is to be activated among the "PDU sessions to be activated" and a registration request, and the AMF 120 receiving it may trigger the SMF 130 associated with the corresponding PDU session to activate the data path. After activating the data path for transmitting data to the UE via the three operations, the data is transmitted to the UE in operation S125.

As another example of fig. 1, although not shown, the UE 110 may request long DRX different from the MICO mode or other power saving mode in operation S107. Considering the long DRX cycle expected by UE 110, if AMF 130 determines that the time at which UE 110 will wake up arrives after the scheduled communication time, AMF 130 may set the DRX cycle of UE 110 such that UE 110 wakes up at a time corresponding to the scheduled communication time and may transmit it to UE 110.UE 110 may perform operations according to the DRX cycle provided by AMF 120.

As another example of fig. 1, the AMF 120, which receives the scheduled communication time in operation S101 or S105, may perform the following operation instead of configuring the wake-up time for the UE 110. The AMF 120 may determine a time when the UE 110 will be in a state of being connected to the network based on the scheduled communication time. The AS starts transmitting data to the UE 110 according to the scheduled communication time. In this instance, UE 110 needs to be in a network-connected state such that downlink data generated at the scheduled time is transmitted without delay. In general, if downlink data is generated for the UE 110 in an idle state, the AS performs paging for the UE 110 in order to change the UE 110 from the idle state to a connected state and allocates resources for data transmission or reception to the UE 110. However, when generating downlink data, if the UE 110 is already in a connected state before generating the downlink data and the corresponding UE 110 receives resources allocated in association with a PDU session in which data is transmitted at a scheduled communication time, data transmission may be immediately performed without delay due to a idle-to-connected state change operation. Thus, this is suitable for providing low-delay communication services to UE 110.

The AMF 120 recognizes the received scheduled communication time and transmits a page to the UE 110 before reaching the corresponding time, so that the UE 110 accesses the network and changes to a connected state. The AMF 120 may desire to perform downlink data transmission with respect to the UE 110 at the scheduled communication time. In operation S105, the AMF 120, which received the scheduled communication time, determines a PDU session in which downlink data transmission is to be performed, based on the PDU session ID corresponding to the scheduled communication time. If there are multiple pieces of information of scheduled communication time for multiple PDU sessions, the AMF 120 may determine to activate PDU sessions having similar scheduled communication time values at the same time.

Based on this determination, AMF 120 may send a page to wake up UE 110. The AMF 120 may send the paging message to the UE 110 before the scheduled communication time (e.g., a few seconds before the scheduled communication time), or may calculate the amount of time the UE 110 typically remains in a connected state, and may send the paging message within the calculated time before the time set for the scheduled communication time (e.g., if the UE typically remains in a connected state for one minute, or less before the scheduled communication time value).

If there is a UE 110 having a scheduled communication time set to a predetermined scheduled communication time or its vicinity (e.g., within a few seconds) among UEs managed by the AMF 120, the AMF 120 may sequentially perform paging of the UE 110 to prevent the corresponding UE from immediately waking up and accessing the network via paging. This can prevent congestion of the network when a large number of UEs attempt network access at the same time at a predetermined point of time. In other words, if 100 UEs need to wake up at a predetermined scheduled communication time, pages are not simultaneously transmitted to 100 UEs, but are sequentially transmitted to a plurality of UEs, tens of UEs, etc. at regular intervals. The fixed interval is based on a value set in the AMF. The UE receiving the page transmits a service request message to the network and starts to change to a connected state. The AMF 120 receiving the service request transmitted from the UE 110 may identify a PDU session ID for which a scheduled communication time is set in association with the corresponding UE in the vicinity of the corresponding time, and may start the PDU session activation procedure for the SMF 130 corresponding to the corresponding PDU session ID. If there are a plurality of PDU session IDs for which the scheduled communication time is set near the time when the UE 110 transmits the service request, the AMF 120 may start the PDU session activation procedure for all SMFs corresponding to the PDU session IDs.

The procedure may be a service operation named "nsmf_pduse_updatsmcontext_request". Alternatively, the procedure may be a message for PDU session activation sent by the AMF called another name to the SMF. The SMF 130 that receives the message may select the UPF 140 for PDU session activation and may perform an operation of establishing a tunnel between the base station and the UPF 140. Subsequently, a message for resource allocation is transmitted to the base station, and the base station allocates radio resources associated with the corresponding PDU session to the UE 110. All operations may be performed before the scheduled communication time and when the scheduled communication time is reached, data transmission is performed in the previous PDU session. The AMF and the SMF may perform the same operations described above if the scheduled communication time arrives when the operations are performed in response to the service request.

Alternatively, if the scheduled communication time is not set for the predetermined session, the AMF 120, which received the scheduled communication time in operation S101, may perform the following operation. The AMF 120 may not be able to identify the scheduled communication time associated with the scheduled PDU session. Accordingly, the UE 110 may perform an operation of enabling the UE 110 to be in a network-connected state at a set scheduled communication time. Accordingly, the AMF 120 may send a page to wake up the UE 110.

The AMF 120 may send the paging message to the UE 110 before the scheduled communication time (e.g., a few seconds before the scheduled communication time), or may calculate the amount of time the UE 110 typically remains in a connected state, and may send the paging message within the calculated time before the time set for the scheduled communication time (e.g., if the UE typically remains in a connected state for one minute, or less before the scheduled communication time value).

If there is a UE having a scheduled communication time set to a predetermined scheduled time or its vicinity (e.g., within a few seconds) among UEs managed by the AMF 120, the AMF 120 may sequentially perform paging for the corresponding UE 110 to prevent the corresponding UE from immediately waking up and accessing the network via paging. This can prevent congestion of the network when a large number of UEs attempt network access at the same time. In other words, if 100 UEs need to wake up at a predetermined scheduled communication time, pages are not simultaneously transmitted to 100 UEs, but are sequentially transmitted to several UEs, tens of UEs, etc. at regular intervals. The fixed interval is based on the value set in the AMF. The UE 110 receiving the page transmits a service request to the AMF 120 and changes to a state of being connected to the network. The AMF 120, which receives the service request transmitted from the UE 110, may perform one of the following two operations.

First, the AMF 120, which determines that the UE 110 is a UE supporting low latency communications, may start a PDU session activation procedure for all PDU session contexts stored in the context of the UE 110. That is, the AMF 120 may start a service operation activated for the PDU session for all PDU sessions established by the UE 110 but changed to be deactivated when the UE changes to the idle state.

Accordingly, the AMF 120 may send a message for PDU session activation to the SMF 130 serving the corresponding session for all PDU sessions included in the context of the UE 110. This may be a service operation such as nsmf_pdustionupdatsmcontext_requst. The SMF 130 that receives it may perform a PDU session activation procedure with the UPF and the base station, and resources for the corresponding PDU session are allocated to the UE 110.

Since downlink data is to be generated for one of the PDU sessions possessed by the UE 110 at the scheduled communication time and resources for the corresponding PDU session have been allocated, the UE 110 can immediately receive the data. The operation corresponding to the "first" may reduce delay caused by the operation of paging the UE 110 and the operation in which the UE 110 transmits a service request in response thereto, changes to a state of being connected to a network, and performs a PDU session activation procedure of the corresponding UE. That is, since all PDU sessions are activated before downlink data is generated, data can be immediately transmitted without delay associated with the PDU session activation procedure when downlink data for UE 110 is generated.

Second, the AMF 120 may maintain a state in which the UE 110 has a control plane connection established with the AMF 120 without an active PDU session. That is, in a state in which the UE 110 has a control plane connection established with the AMF 120 by transmitting a service request, the AMF 120 may continuously maintain the UE 110 in a connected state without performing a PDU session activation procedure. When the scheduled communication time arrives, downlink data may be transmitted to the UE 110, and the data may be first transmitted to a UPF serving a PDU session corresponding to the UE 110.

The UPF 140 may report the downlink data arrival for the corresponding UE to the SMF associated with the corresponding PDU session. The SMF 130 that receives it may perform a PDU session activation procedure with the UPF 140 and the base station and resources for the corresponding PDU session are allocated to the UE 110. After the PDU session activation procedure, downlink data may be transmitted to UE 110. An operation corresponding to "second" may achieve low latency by removing a procedure in which the AMF 120 performs paging of the UE 110 and the UE 110 wakes up via a service request. However, delays caused by the procedure of establishing the PDU session may be unavoidable.

Fig. 2 is a diagram illustrating operations performed when a UE is already in an unreachable state in a case where an AMF obtains scheduling information associated with scheduled data transmission according to an embodiment of the present disclosure.

According to the embodiment disclosed in fig. 2, although the third party AS240 sets the scheduled communication time for the UE, in the case where the UE is in a low power mode and is not reachable through the network (e.g., the MICO mode), the AMF 210 may not enable the UE to be reachable at the scheduled communication time.

For example, if the time corresponding to the scheduled communication time is earlier than the time the UE expects to wake up, the AMF 210 may not confirm whether the UE was awake or not before the scheduled communication time. Accordingly, the AMF 210 cannot ensure the reachability of the UE, and may transmit information associated with the time at which the UE is expected to be reachable to a third party via the 5G system.

Referring to fig. 2, in operation S201, the AMF 210 already has a scheduled communication time. The information may be included in the UE context transmitted from the UDM 220 or may be information transmitted directly from the NEF 230.

In operation S203, the AMF 210 may determine that the UE is already in the MICO mode, and more precisely, in a state of being unreachable through the network due to the low power mode. In addition, the AMF 210 may determine when the UE is reachable based on a periodic registration update timer set for the UE.

If the time corresponding to the scheduled communication time is earlier than the time the UE expects to wake up, the AMF210 may not confirm whether the UE is awake at or before the scheduled communication time. Accordingly, the AMF210 may not configure the UE based on the scheduled communication time. The AMF210 may perform operation S205 to report the above information to the third party AS240.

In operation S205, the AMF210 may transmit information indicating that the UE is currently unreachable and time information associated with when the UE is expected to be reachable to the NEF 230 via the UDM 220. Alternatively, the AMF210 may directly transmit information indicating that the UE is currently unreachable and time information associated with the time at which the UE is expected to be reachable to the NEF 230.

The AMF210 may know the NEF from which the information is received in operation S201, and thus may transmit the above information to the corresponding NEF. The information in operation S205 may include a UE ID (e.g., an external ID) and a time at which the UE is expected to be reachable. The time at which the UE is expected to be reachable is determined based on a periodic registration update timer. The UE may wake up at a time corresponding to the periodic registration update timer.

The NEF 230 may report the received information AS a report to the third party AS240. In operation S207, the third party AS240 recognizes that data transmission is not allowed at an expected time, and may set the scheduled communication time again to a time suitable for the UE' S expected availability reported from the 5G system.

Fig. 3 is a diagram illustrating operations performed when a UE is already in an unreachable state in a case where an SMF provides scheduling information associated with scheduled data transmission to an AMF, according to an embodiment of the present disclosure.

According to the embodiment disclosed in fig. 3, although the third party AS 350 sets the scheduled communication time for the UE, in the case where the UE is in a low power mode and is not reachable through the network (e.g., the MICO mode), the AMF 310 may not enable the UE to be reachable at the scheduled communication time.

For example, if the time corresponding to the scheduled communication time is earlier than the time the UE is expected to wake up, the AMF 310 may not confirm whether the UE is awake or not before the scheduled communication time. Accordingly, the AMF 310 cannot ensure the reachability of the UE, and may transmit the time at which the UE is expected to be reachable to the SMF 320. The SMF 320 may transmit the information received from the AMF 310 to a third party via the 5G system.

Referring to fig. 3, in operation S301, the SMF 320 already has a scheduled communication time. This information may be included in the UE context transmitted from UDM 330 or may be information transmitted directly from NEF 340.

In operation S303, the SMF 320 may provide information indicating that a predetermined UE needs to be reachable at the scheduled communication time to the AMF 310. This operation is based on operation S105 of fig. 1 of the present disclosure. The AMF 310 receiving the message of operation S303 may determine that the UE is already in the MICO mode, and more precisely, in a state of being unreachable through the network due to the low power mode. In addition, the AMF 310 may determine the time at which the UE is reachable based on a periodic registration update timer set for the UE.

If the time corresponding to the scheduled communication time is earlier than the time the UE is expected to wake up, the AMF 310 may not confirm whether the UE is awake at or before the scheduled communication time. Accordingly, the AMF 310 may not configure the UE based on the scheduled communication time. The AMF 310 may proceed to operation S307 to report the information to the SMF 320.

The message in operation S307 may include a UE ID, a time at which the UE expects to wake up, or a PDU session ID of the corresponding UE. The time at which the UE is expected to be reachable is determined based on a periodic registration update timer. The UE may wake up at a time corresponding to the periodic registration update timer.

The SMF 320 may proceed to operation S309 to report this information to the third party AS 350.SMF 320 may transmit information indicating that the UE is not currently reachable and time information associated with the desired UE being reachable to NEF 340 via UDM 330. Alternatively, SMF 320 may transmit information indicating that the UE is currently unreachable and time information associated with the time when the UE is expected to be reachable directly to NEF 340.

The SMF 320 may know the NEF from which the information is received in operation S301, and thus may transmit the above information to the corresponding NEF. The information in operation S309 may include a UE ID (e.g., an external ID) and a time at which the UE is expected to be reachable (the time may be determined based on a periodic registration update timer).

NEF 340 may report the received information to third party AS 350. In operation S311, the third party AS 350 that received the message of operation S309 may recognize that data transmission is not allowed at an expected time and may set the scheduled communication time again to a time suitable for the expected availability of the UE reported from the 5G system.

Fig. 4 is a diagram illustrating a method in which when a UE and an SMF perform establishment of a PDU session for NIDD, the SMF recognizes that NIDD configuration does not exist and allows a corresponding PDU session establishment request but performs deactivation, according to an embodiment of the present disclosure.

The NEF 440 and the AS 450 may perform a configuration procedure in order to use a data transfer service via the NEF, which is background of the embodiments. In this disclosure, this is referred to as a NIDD configuration. AS 450 and NEF 440 may configure a "data transfer service via NEF" (hereinafter "NIDD service") to be used for a UE or a group of UEs. The UE is indicated by an external ID. The external ID is an identification for the AS 450 to identify the UE, and may identify an internal ID (e.g., SUCI, SUPI, IMSI, etc.) for identifying the UE in the 5G system.

The UE group may be indicated by an external group ID. The external group ID is an identification for the AS 450 to identify a predetermined UE group, and may identify an internal group ID for identifying the UE group or an internal ID of each UE included in the group of the 5G system. Via the NIDD configuration procedure performed between the NEF 440 and the AS 450, data transmission characteristics possessed by the corresponding UE or group, such AS maximum delay, the number of messages transmitted, scheduled transmission time, data transmission period of the UE, etc., may be set.

As another background, a procedure for establishing a connection for NIDD service between SMF 420 and NEF 440 is required. The SMF 420 needs to identify the NEF to which the data obtained from the UE is to be transmitted, and the NEF 440 needs to identify the SMF to which the data obtained from the third party AS 450 is to be transmitted in order to perform data transmission to the UE 410.

Thus, SMF 420 and NEF 440 need to perform a connection procedure for NIDD services, which is referred to as "NIDD service activation" for ease of illustration. As another example, data transmission may be performed via a connection between the UPF and the NEF 440 for NIDD services. The connection between the UPF and the NEF 440 may be established through arbitration by the SMF. Thus, in the case where NIDD services are supported via a connection between the UPF and the NEF, the SMF 420 and the NEF 440 may perform a connection procedure of the NIDD services, the SMF 420 may configure relevant data routing information for the UPF, and a connection needs to be established between the UPF and the NEF 440. NIDD service activation may be a procedure applied to both cases, that is, a case in which data transmission is performed via a connection between the SMF 420 and the NEF 440, and a case in which data transmission is performed via a connection between the UPF and the NEF 440.

As another background, the UE 410 needs to establish a PDU session (hereinafter, NIDD service) of a data transmission service via the NEF 440 in order to transmit non-IP data via the NEF 440. The UE 410 performs a PDU session establishment procedure with the SMF 420 in order to establish a PDU session. In this example, UE 410 may include an identification indicating a PDU session for the NIDD service of the procedure. When the corresponding Data Network Name (DNN) has a value indicating NIDD service, the identification may be an independent identification or DNN.

The problems that the present disclosure is intended to solve are as follows. According to the conventional method, after performing the NIDD configuration procedure between the third party AS 450 and the NEF 440, the UE 410 performs a PDU session establishment procedure associated with the corresponding NIDD service with the SMF 420. Then, the SMF 420 identifies NIDD configuration information included in subscriber data of the UE 410 obtained from the UDM 430, and may perform a NIDD service activation procedure with the NEF indicated by the correspondence information.

If NIDD configuration is not performed in advance between the third party AS 450 and the NEF 440, NIDD configuration information does not exist in subscriber data of the UE 410, and thus the SMF 420 may not know the NEF to which a connection for NIDD service is to be established. Thus, the SMF 420 may not allow the PDU session establishment procedure performed by the UE 410 and may need to reject the corresponding request.

Subsequently, if NIDD configuration is performed between the third party AS 450 and the NEF 440, the third party AS 450 may need to send application layer signaling so that the UE 410 can perform PDU session establishment for NIDD services or may need to perform device triggering using a 3GPP network. Otherwise, the UE 410 may not know when the UE 410 needs to perform the PDU session establishment procedure and may not perform data transmission until the PDU session establishment.

However, in order for the third party AS 450 to be able to send application layer signaling before the UE 410 establishes a PDU session for NIDD, another PDU session may be used that is different from the PDU session for NIDD. That is, there is a limitation in that the UE 410 must have another PDU session in addition to the PDU session for NIDD. In addition, in case of device triggering, the UE 410 needs to support SMS in order to support device triggering. In other words, the limitations of current systems require IoT users to develop only at low cost to support additional functionality.

The present disclosure provides a procedure of successfully performing a NIDD PDU session establishment procedure of the UE 410 even though NIDD configuration is not performed in advance, and a connection for NIDD service is established when NIDD configuration is performed. Thus, the 5G system may remove the dependency between NIDD configuration and NIDD PDU session establishment procedure of UE 410. In addition, the UE may not need to have another PDU session and may not need to support SMS. The third party AS 450 may not need to support additional application layer operations or device triggering services for the UE 410 using NIDD services.

Fig. 4 is a diagram illustrating a procedure in which a UE 410 establishes a PDU session for NIDD and operations performed after NIDD configuration is performed, according to an embodiment of the present disclosure.

In operation S401, the UE 410 requests a PDU session establishment request from the SMF 420. The request message may include an indicator indicating that NIDD services are to be used, or a DNN value indicating NIDD services. In addition, an external ID of the UE 410 for NIDD service may be included for the UE 410. The SMF 420 receiving the request message may determine that the UE 410 establishes a PDU session for NIDD service. In operation S403, the SMF 420 reports to the UDM 420 that the SMF 420 is to serve the UE 410, and subscriber data of the UE 410 may be obtained.

In operation S405, the SMF 420 recognizes that NIDD configuration information does not exist in the subscriber data of the UE 410 obtained in operation S403. The PDU session establishment request from UE 410 is associated with NIDD services. However, NIDD configuration information is not included in subscriber data of UE 410, and thus SMF 420 may determine that NIDD configuration has not been performed. The NIDD configuration information may include at least one of: an address or ID of NEF 440 for providing NIDD services to UE 410, DNN information for providing NIDD services to UE 410, an address of NEF 440 associated with DNN for NIDD services, and an external ID of UE 410 for NIDD services. However, the SMF 420 may identify from the subscriber data of the UE 410 whether the corresponding UE is a UE permitted to use NIDD services.

The identification method is based on at least one of the following operations. 1. Determining whether the DNN in the subscriber data is the same as the DNN of the NIDD requested by the UE; 2. determining whether an indicator indicating that the UE is allowed to use NIDD services of the corresponding DNN is included; 3. determining whether a network slice used by the UE is a network slice in which NIDD services are available; 4. in operation S401, it is determined whether an external ID for NIDD service by the UE is included in subscriber data, and it is determined whether the external ID is identical to a value transmitted by the UE in a PDU session establishment procedure; or 5. Determining whether to allow the information that allows the UE to use NIDD services to be included in the subscriber data.

If NIDD configuration information is included in the subscriber data received in operation S403, the SMF 420 may determine that NIDD configuration has been performed, may transmit a message of operation S417 to an address of the NEF 440 included in the correspondence information in order to perform NIDD service activation, and may complete a PDU session establishment procedure with the UE 410.

In operation S407, the SMF 420, which determines in operation S405 that the NIDD service is provided to the UE 410, may configure a PDU session establishment acceptance message and transmit it to the UE 410. Since NIDD configuration has not been performed, a NIDD service activation procedure is not performed between SMF 420 and NEF 440.

Thus, the message of operation S407 may include an indicator indicating that the PDU session establishment was successfully performed but the corresponding PDU session was not activated, that is, data transmission via the corresponding PDU session is not currently available. The UE 410 receiving the message may know that a PDU session for the corresponding NIDD has been established but not activated and cannot yet transmit data. Thus, the UE 410 may determine not to send a service request for a corresponding PDU session until the corresponding PDU session is activated. If the UE 410 transmits a service request for a corresponding PDU session, the SMF may reject the service request for the corresponding PDU session of the UE 410 if NIDD configuration has not been performed and NIDD service activation has not been performed. If the UE 410 transmits a service request for a PDU session and NIDD configuration and NIDD service activation are performed in advance, the SMF 420 may accept the service request and activate the PDU session.

As another example of operations S405 and S407, the SMF 420 may transmit a PDU session accept to the UE 410 via the AMF and the base station in operation S407. In this example, SMF 420 may determine not to transmit an N2 SM message (a message between the base station and the SMF) to the base station for session establishment. That is, the PDU session accept message is transmitted to the UE 410, but the base station does not obtain information associated with establishing a radio bearer for the UE 410 from the SMF 420, and thus, the base station may not establish a radio bearer with the UE 410. Since a radio bearer of a corresponding PDU session with the base station is not established, the UE 410 may determine that the corresponding PDU session is currently in a deactivated state.

In operation S411, the third party AS 450 may perform NIDD configuration with the NEF 440 for the 5G system in which the UE 410 is registered. AS 450 and NEF 440 may configure that "data transfer services via NEF" will be used for a UE or group of UEs. The UE is indicated by an external ID. The external ID is an identification for the AS 450 to identify the UE 410, and may also identify an internal ID (e.g., SUCI, SUPI, IMSI, etc.) for identifying the UE 410 in the 5G system. The UE group may be indicated by an external group ID. The external group ID is an identification for the AS to identify a predetermined UE group, and in the 5G system, an internal group ID for identifying the UE group or an internal ID of each UE included in the group may also be identified.

In operation S411, the NEF 440 and the AS 450 may set data transmission characteristics possessed by the corresponding UE or group, for example, a maximum delay, the number of transmitted messages, a scheduled transmission time, a data transmission period of the UE, and the like. In operation S411, the NEF 440 may obtain information indicating the SMF 420, via a procedure with the UDM 430, the SMF 420 serving the UE 410 associated with the requested NIDD service. In operation S403, the SMF 420 registers information indicating that the SMF 420 will serve the PDU session for NIDD of the corresponding UE in the UDM 430. Thus, UDM 430 may report to NEF 440 the address or ID of SMF 420 that services the PDU session for the NIDD of the corresponding UE.

The NEF 440, which obtains the address or ID of the SMF 420, may send the message of operation S413 to the corresponding SMF 420. This is a message for establishing a connection between SMF 420 and NEF 440 in order to support NIDD services.

In the message for establishing a connection between the SMF 420 and the NEF 440 in order to support NIDD service according to an embodiment of the present disclosure, an ID for identifying the UE 410, that is, an external ID, or an ID for identifying a group of the UE 410, that is, an external group ID, may be included. Further, information required to provide NIDD services to UE 410 may be included. The information may include an ID of NEF 440 and a reference ID for identifying a connection with NEF 440 for NIDD services. In addition, configuration information for the NIDD service may be included. The information may be information associated with a maximum delay required for the corresponding UE or group to perform data transmission, a data transmission period of the corresponding UE or group, or a scheduled data transmission time, etc.

When NIDD services are allowed and provided to UE 410, the message of operation S413 may operate similar to an event subscription requesting SMF 420 to send a report to NEF 440. Accordingly, the SMF 420 may store information included in the message of operation S413 received from the NEF 440.

In operation S415, the SMF 420, which determines that NIDD services are available to the UE 410, may report to the UE 410 that a PDU session corresponding to NIDD is activated. This may be performed as follows: the SMF 420 requests the reachability of the corresponding UE 410 from the AMF, the AMF performs paging for the UE 410, and the UE 410 transmits a service request in response thereto.

When the UE 410 responds via a service request, the AMF reports to the SMF 420 that the UE 410 has woken up, and the SMF 420 may perform a procedure of activating a data path associated with a PDU session of the corresponding UE 410. In this way, an N2 SM message is sent to the base station, and the setting of the radio bearer for the UE 410 is indicated to the base station.

The UE 410, knowing that a radio bearer for a predetermined PDU session was established, may determine that the data path for the PDU session for NIDD is activated. As another example, the SMF 420 may report to the UE 410 that the corresponding PDU session is activated using a PDU session modification procedure in the SM NAS procedure with the UE 410. In this example, the PDU session ID and an indicator indicating that the corresponding PDU session is activated are included in the PDU session modification command message. The UE 410 receiving it may determine that the PDU session corresponding to the PDU session ID is activated. UE 410 may identify the PDU session ID and may identify whether the corresponding PDU session is a PDU session for NIDD.

SMF 420 for the PDU session of NIDD activated for UE 410 may send a message of operation S417 to NEF 440 and may complete the NIDD service activation procedure between SMF 420 and NEF 440. In this instance, the SMF 420 may include in the message an external ID of the UE or an external group ID of a group to which the UE belongs, a reference ID for identifying a connection with the NEF 440 associated with the "data transmission service via the NEF" received in operation S413, an ID of the NEF 440 received in operation S413, and an SMF ID indicating itself. If there is data transmitted by the UE 410 via the "data transmission service via the NEF", the data may be included in the message of operation S417. The NEF 440 having received it may determine that "data transfer service via NEF" establishes a connection with the SMF 420 transmitting the message of operation S417, and may identify the connection by a combination of the reference ID and the SMF ID.

If the NEF 440 receives the data transmitted from the UE 410 in operation S417, the NEF 440 may identify the corresponding data, UE ID, or target ID, may determine the AS 450 to which the data is directed and configured with the "data transmission service via the NEF", and in operation S419, may transmit the data to the corresponding AS 450.

Fig. 5 illustrates a PDU session establishment operation in which a UE accesses a 5G system and establishes a data connection.

According to an embodiment of the present disclosure, the SMF 540 may determine whether to apply a small data rate control function, which is one of CIoT functions, to the corresponding UE 510 via the procedure of fig. 5. As another example, via the process of fig. 5, SMF 540 may receive subscription information of a corresponding UE 510 or policies associated with a corresponding DNN from UDM 560 or PCF 550. Based on this information, SMF 540 may determine whether to apply a small data rate control function to the corresponding UE 510 or the corresponding DNN.

A detailed description of each operation shown in fig. 5 is as follows.

Operation S501: the UE 510 configures a PDU session establishment request, which is an SM NAS message, and sends it to the AMF 530 in order to establish the PDU session. The UE 510 includes a Data Network Name (DNN) that it wishes to use in the PDU session establishment request message, and the UE 510 may set the DNN to a DNN value for CIoT. The DNN information may be used when SMF 540 or PCF 550 determines whether the corresponding DNN is a DNN that UE 510 is allowed to use for CIoT services. Alternatively, the UE 510 may include the radio access technology type (RAT type) currently used by the UE 510 in the PDU session establishment request message. That is, the RAT type may indicate whether the RAT currently accessed by the UE 510 is NB-IoT, WB-EUTRAN, NR-IoT (modified for NR of IoT), or LTE-M (this is the RAT type used by IoT UEs, which may be identified as LTE-M if the UE uses IoT dedicated radio technology, although the UE uses WB-EUTRAN). The indicator may include a meaning that a function needs to be applied differently to a corresponding PDU session depending on the RAT type. That is, it is determined that small data rate control is not applied to the UE accessing the NR. In the same manner, it is determined to apply small data rate control to UEs accessing NB-IoT. In addition, it is determined to apply small data rate control to the UE accessing LTE-M. This information may be used later when the SMF 540 receives a PDU session establishment request message sent by the UE 510. The RAT type may be included as NAS information in the PDU session establishment request message or may be included in PCO of the PDU session establishment request message.

Operation S503: AMF 530 may select SMF 540 based on the DNN value or the location of the UE, and may transmit an Nsmf_PDUSation_CreateSMContext request message to the selected SMF 540. The AMF 530 may include in the message a PDU session establishment request message received from the UE 510. Furthermore, according to embodiments of the present disclosure, AMF 530 may include the RAT type currently accessed by UE 510 in the nsmf_pduse_createsmcontext request. The AMF 530 may know the RAT type accessed by the UE 510 based on information received from the base station 520. For example, the AMF 530 may identify a tracking area code reported by the base station 520 that the UE is currently accessing and may recognize a RAT type corresponding to the tracking area code. The AMF 530 may determine that the UE 510 is a UE using CIoT function, and may include RAT type information in the nsmf_pduse_createsmcontext request message in order to inform the SMF 540 of the RAT type currently accessed by the UE 510. The radio access technology type (RAT type) may indicate whether the RAT to which the UE accesses is NB-IoT, WB-EUTRAN, NR-IoT (NR modified for IoT), or LTE-M (this is the RAT type used by IoT UEs, which may be identified as LTE-M if the UE uses IoT dedicated radio technology, although the UE uses WB-EUTRAN).

Operation S505: the SMF 540 receives the PDU session establishment request message received from the UE 510. The SMF 540 may perform a process of registering the SMF 540 as a service SMF in the UDM 560 so as to obtain subscription information related to a session associated with the UE 510, and may perform a process of obtaining subscription information for session management of the UE 510. UDM 560 that receives it may provide subscription information to SMF 540. The subscription information may include information indicating whether the UE 510 is capable of using CIoT services, and information associated with whether CIoT-related functions are applied to the UE 510, for example, information associated with whether small data rate control is applied or information associated with whether serving PLMN rate control is applied. Alternatively, the subscription information may include information associated with whether to apply CIoT-related functions to DNNs subscribed to the UE 510, e.g., information associated with whether to apply small data rate control or information associated with whether to apply serving PLMN rate control.

According to detailed embodiments of the present disclosure, if a RAT type indicating a RAT currently accessed by the UE 510 is included in a PDU session establishment request message or PCO of a corresponding message received from the UE 510, the SMF 540 may store the RAT type in a UE context, or may determine CIoT functions to be applied based on the RAT type of the UE.

Alternatively, if the RAT type indicating the current access of the UE 510 is included in the message of operation S503 received from the AMF 530, the SMF 540 may store the RAT type in the context of the UE 510, or may determine CIoT functions to be applied based on the RAT type of the UE 510.

The SMF 540 may determine whether to apply a small data rate control function to the UE 510 based on the RAT type. In this example, SMF 540 may identify subscription information received from UDM 560, and if an indicator indicating whether CIoT-related functions (e.g., small data rate control) are applied is included in the corresponding subscription information, SMF 540 may also reference it. For example, if the UE 510 is accessing via NB IoT RATs, the SMF 540 may determine to apply the small data rate control function. As another example, if the UE 510 accesses via WB-etura RAT, the SMF 540 may identify whether the DNN transmitted from the UE 510 is a DNN of CIoT, and if the DNN is identified as a DNN of CIoT, may determine to apply a small data rate control function. As another example, if the UE 510 accesses via WB-etura RAT, the SMF 540 may identify information included in subscription information of the UE 510 received from the UDM 560 and information indicating whether to apply the small data rate control function, and may determine to apply the small data rate control function. As another example, if the UE 510 is accessing via an NR RAT, the SMF 540 may determine not to apply a small data rate control function to the UE 510. As another example, if the SMF determines that the UE 510 accesses via the NR RAT and identifies information indicating whether to apply the small data rate control function and included in subscription information of the UE 510, or determines that the DNN requested by the UE 510 is a DNN of CIoT, the SMF may determine to apply the small data rate control even for the UE 510 accessed via the NR-RAT. As another example, if the UE 510 is accessing via the NR-IoT RAT, the SMF 540 may determine to apply a small data rate control function to the UE 510. As another example, if the UE 510 is accessing via an LTE-M RAT, the SMF 540 may determine to apply a small data rate control function to the UE 510.

Operation S507: the SMF 540 may identify the PDU session establishment request message received from the UE 510 and may perform an SM policy association establishment procedure with the PCF associated with the corresponding DNN. In this example, SMF 540 may communicate the DNN requested by UE 510 to PCF 550. The PCF 550 receiving this information may determine that the corresponding DNN is a DNN for a CIoT service, and may configure a session-related policy to be transferred to the SMF 540 to include information indicating whether to apply CIoT-related functions, for example, whether to apply small data rate control.

Operation S509: SMF 540 may configure PCO to be provided to UE 510. PCO is an abbreviation for protocol configuration options. PCO is a container including additional configuration information required to use a corresponding PDU session, and is information exchanged between the UE 510 and the SMF 540. According to an embodiment in operation S505 or S507, the SMF 540 may determine whether to apply small data rate control to the UE 510, and may set a value for the small data rate control for the PCO. The value for small data rate control may be a value set in SMF 540, a value obtained by SMF 540 from UDM 560, or a value obtained by SMF 540 from PCF 550. The information (pre-configuration) previously configured in the SMF 540 may be set in the SMF 540 via the OAM system, or may be information pre-configured in the SMF 540 according to management through a network of the mobile communication carrier.

The PCO is included in a session management NAS message called "PDU session establishment accept" and is transmitted as a NAS message to the UE 510 via the AMF 530.

Operation S509: SMF 540 selects UPF 570 and establishes the N4 session.

Operation S511: the SMF 540 may include a PDU session establishment accept message to be transmitted to the UE 510 and an N2message to be transmitted to the base station 520 in the namf_communication_n1n2message transfer message and may transmit it to the AMF 530. In the N2message, a PDU session ID, a QoS profile, a QoS flow ID, tunnel information on the UPF 530 side for connecting the N3 tunnel between the UPF 570 and the base station 520, and the like may be included.

AMF 530 may transmit an ACK associated with Namf_communication_N1N2message transfer to SMF 540.

Operation S513: AMF 530 may transmit a message received from SMF 540 to base station 520. In this message, an N2 SM message received from the SMF 540 and an N1 SM NAS message received from the SMF 540 may be included.

Operation S515: the base station 520 may receive the message of operation S513 and may perform an RRC signaling procedure for establishing a data radio bearer with the UE 510 according to the QoS information included in the N2 SM message. In addition, the base station 520 may transmit the received NAS message to the UE 510.

The UE 510 receiving the PDU session establishment acceptance message transmitted from the SMF 540 may complete the PDU session establishment procedure. The UE 510 may identify PCO information included in the PDU session establishment acceptance message, and may identify information indicating whether to apply small data rate control and a value for applying small data rate control included in the PCO. The UE 510 may apply the small data rate control configured as described above when using the corresponding PDU session.

Operation S517: the base station 520 transmits a response in response to operation S513. The message includes an N2 SM message. Including PDU session ID and tunnel information on the base station 520 side for connecting to the N3 tunnel of the UPF 570. In addition, information associated with the established QoS flows, etc. may be included.

Operation S519: the AMF 530 receiving the message of operation S517 may transmit the N2 SM message contained in the message of S517 to the SMF 540.

Operation S521: the SMF 540 may recognize the N2 SM message received in operation S519 and may perform an N4 session modification procedure together with the UPF 570. In this example, SMF 540 may communicate the N3 tunnel information on the base station 520 side received from base station 520 to UPF 570 and may also communicate packet forwarding rules associated therewith. A connection for establishing a tunnel for data transmission or reception between the UPF 570 and the base station 520 via operation S521 is also considered.

Operation S523: the SMF 540 sends a response to the AMF 530 in response to operation S519.

The UE 510 can perform data transmission or reception via the established PDU session.

Fig. 6 is a diagram illustrating a method of updating information associated with whether to apply small data rate control and small data rate control values to a UE via a PDU session modification procedure.

The SMF 640 may set update information associated with whether to apply the small data rate control and an updated small data rate control value in the PCO information and may transmit it to the UE 610 via the procedure of fig. 6.

The PDU session modification procedure may be performed under the following conditions.

-changing an access RAT of the UE: the AMF 630, which determines that the RAT to which the UE 610 accesses is changed, may notify the SMF 640 of the change in RAT type. Accordingly, the SMF 640, which determines that the RAT type of the UE 610 is changed, may determine to apply CIoT functions suitable for the current RAT of the UE 610. For example, if the UE 610 to which the small data rate control is applied changes from NB-IoT to NR RAT, the SMF 640 may determine not to apply the small data rate control. As another example, if a UE 610 that is always using NR RAT or WB-EUTRAN changes its RAT type to NR-IoT or LTE-M, the SMF 640 may determine to apply small data rate control. The SMF 640 may trigger a PDU session modification procedure to provide the UE 610 with a continuous PDU session. In this example, the SMF 640 may release the small data rate control related information in the PCO transmitted to the UE 610 so that the small data rate control is not applied any more. That is, the small data rate control related information may not be included, or null (null) or 0 may be input to indicate that the small data rate control need not be applied. As another example, if the UE 610 that is always using a PDU session in the NR RAT changes to the NB-IoT RAT or the LTE-M RAT, the SMF 640 may determine to apply small data rate control to the corresponding PDU session. The SMF 640 may trigger a PDU session modification procedure to provide the UE 610 with a continuous PDU session. In this example, the SMF 640 may include small data rate control related information in the PCO transmitted to the UE 610 in order to apply the small data rate control.

In operation S601, the UE 610 may configure a PDU session modification request, which is an SM NAS message, to change a PDU session since a RAT type of the UE 610 is changed. UE 610 may transmit a PDU session modification request to AMF 630. The UE 610 may include a RAT type in the PDU session modification message indicating the RAT to which the UE 610 has access. Alternatively, the UE 610 may include PCO information in the PDU session modification message and may include information indicating the RAT type of the UE 610 in the PCO. For example, the information may include at least one of NB-IoT, WB-EUTRAN, NR, NR-IoT and LTE-M (this is the RAT type used by the UE, which is identified as LTE-M despite the UE using WB-EUTRAN if the UE uses IoT dedicated radio technology). This information may then be used when the SMF 640 determines CIoT functions to apply based on the RAT type of the UE 610. Operation S601 occurs when the UE 610 triggers the operation, and the UE 610 may not perform operation S601 when the RAT type of the UE 610 is changed.

Operation S603: if the AMF 630 receives the message of operation S601, the AMF 630 may transmit an Nsmf_PDUSion_CreateSMContext request message to the SMF 640. The AMF 630 may include the PDU session modification request message received from the UE 610 in the nsmf_pduse_createsmcontext request. The AMF 630 may determine the RAT type of the UE 610 by identifying the RAT type transmitted by the base station 620. The AMF 630 may include the RAT type of the UE 610 in the nsmf_pduse_createsmcontext request message and may transmit it.

The SMF 640 may identify a RAT type received from the AMF 630, a RAT type included in the PDU session modification request message received from the UE 610, or a RAT type in the PCO and may determine whether to apply a CIoT-related function (e.g., a small data rate control function) to the corresponding UE 610.

As another example, if the RAT type of the UE 610 is changed, the AMF 630 may configure an nsmf_pduse_createsmcontext request message and may send it to the SMF 640. The AMF 630 may determine the RAT type indicating the RAT to which the UE 610 has access by identifying the tracking area code transmitted from the base station 620 and the RAT type associated therewith. The AMF 630 may include a RAT type indicating a RAT to which the UE 610 accesses in the nsmf_pduse_createsmcontext request message and may transmit it.

As another example, if the RAT type of the UE 610 is changed, the AMF 630 may send an event notification associated with the change in RAT type to the SMF 640. The SMF 640 receiving it may know that the RAT type of the UE 610 is changed and may determine whether to apply a CIoT-related function (e.g., a small data rate control function) to the corresponding RAT type. If it is determined to change the application of the small data rate control function, the SMF 640 may perform operation S609. Even if the operation S601 is not performed, S609 is operable.

Operation S605 is performed when PCF 650 reports the updated policy information to SMF 640.

Operation S607: the SMF 640 may receive an update regarding a change in subscription information from the UDM 660, or may give the UDM an update regarding current RAT type information of the UE 610, and may receive an update regarding subscription information associated therewith.

Operation S609: the SMF 640, which determines that the RAT type of the UE 610 is changed, may determine whether to apply CIoT-related functions (e.g., small data rate control) based on the changed RAT type.

In this example, SMF 640 may identify subscription information received from UDM 660 and if an indicator indicating whether CIoT-related functions (e.g., small data rate control) are applied is included in the corresponding subscription information, SMF 540 may also reference it. For example, if the UE 610 is accessed via an NB-IoT RAT, the SMF 640 may determine to apply the small data rate control function. As another example, if the UE 610 accesses via WB-etura RAT, the SMF 640 may identify whether the DNN used by the UE 610 is a DNN for CIoT, and if the DNN is identified as a DNN for CIoT, may determine to apply a small data rate control function. As another example, if the UE 610 accesses via WB-etura RAT, the SMF 640 may identify information included in subscription information of the UE 610 received from the UDM and indicating whether to apply the small data rate control function, and may determine to apply the small data rate control function. As another example, if the UE 610 accesses via an NR RAT, the SMF 640 may determine not to apply a small data rate control function to the UE. As another example, if the SMF determines that the UE 610 accesses via the NR RAT and recognizes information indicating whether to apply a small data rate control function and included in subscription information of the UE 610 or determines that the DNN requested by the UE 610 is a DNN for CIoT, the SMF may determine to apply small data rate control to the UE 610 accessed via the NR RAT. As another example, if UE 610 is accessed via an NR-IoT RAT, SMF 540 may determine to apply a small data rate control function to UE 610. As another example, if the RAT type of the RAT indicating the UE 610 access is LTE-M, the SMF 640 may determine to apply a small data rate control function to the UE 610.

The SMF 640 determining this may configure information associated with whether to apply the small data rate control or a value for applying the small data rate control in the PCO, and may transmit the PCO to the UE 610. In this case, the PDU session modification command as the SM NAS message may be used. The message may be transmitted to the AMF 630 via operation S609, and the AMF 630 may transmit the message to the UE 610 in operations S611 and S613.

Operation S613: the base station may receive the message of operation S611 and may perform an RRC signaling procedure for establishing a data radio bearer with the UE 610 according to the QoS information included in the N2 SM message. In addition, the base station 620 may transmit the received NAS message to the UE 610. The UE 610 may identify the N1 SM NAS message received from the SMF 640 and may identify the PCO included in the message. The UE 610 may identify small data rate control information included in the PCO and may determine whether to apply the small data rate control. If the small data rate control information is not included in the PCO, the UE 610 may determine not to apply the small data rate control. Alternatively, if a value set in the PCO for applying the small data rate control is set to null (null) or 0, the UE 610 may determine not to apply the small data rate control. The UE 610 may configure a PDU session modification complete message indicating completion of the PDU session modification procedure as an N1 SM NAS message and may transmit it to the SMF 640.

Operation S615: the base station 620 transmits a response in response to operation S613. The message includes an N2 SM message. The N1 SM NAS message may also be included if the UE 610 configures the PDU session modification complete message as an N1 SM NAS message.

Operation S617: the AMF 630 receiving the message of operation S615 may transmit the N2 SM message and the N1 SM NAS message included in the message of S615 to the SMF 640.

Operation S619: the SMF 640 may recognize the N2 SM message received in operation S617 and may perform an N4 session modification procedure together with the UPF. In this example, the SMF 640 may communicate base station side N3 tunnel information received from the base station 620 to the UPF and may also communicate packet forwarding rules associated therewith. In operation S621, the SMF 640 transmits a response to the AMF 630 in response to operation S617.

Fig. 7 is a diagram illustrating a structure of a User Equipment (UE) according to an embodiment of the present disclosure.

The UE of fig. 7 is the user equipment shown in fig. 1 to 6. Referring to fig. 7, the ue may include a transceiver 710, a controller 720, and a memory 730. In this disclosure, a controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The transceiver 710 may perform transmission or reception of signals with another network entity.

The controller 720 may control overall operations of the UE according to the embodiment. For example, the controller 720 may control the signal flow such that operations are performed according to the flowcharts of fig. 1 to 6.

The memory 730 may store at least one piece of information among information transmitted or received via the transceiver 710 and information generated by the controller 720.

Fig. 8 is a diagram illustrating a structure of a network entity according to an embodiment of the present disclosure. The network entity of fig. 8 may be each of the plurality of network entities of fig. 1-6. For example, the network entity of fig. 8 may be AMF, SMF, UPF, UDM, NEF or AS/AF.

Referring to fig. 8, a network entity may include a transceiver 810, a controller 820, and a memory 830. In this disclosure, a controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The transceiver 810 may perform transmission or reception of signals with another network entity. For example, the transceiver 810 may transmit system information to the UE and may transmit a synchronization signal or a reference signal.

The controller 820 may control the overall operation of the network entity according to an embodiment. For example, the controller 820 may control the signal flow such that operations are performed according to the flowcharts of fig. 1 to 6.

The memory 830 may store at least one piece of information among information transmitted or received via the transceiver 810 and information generated by the controller 820.

Claims

1. A method performed by a session management function, SMF, in a wireless communication system, the method comprising:

receiving a first message from an access management function, AMF, wherein the first message comprises a radio access technology, RAT, type of a user equipment, UE;

determining whether to apply a small data rate control function to the UE based on the RAT type; and

and sending a second message to the AMF, wherein the second message comprises a small data rate control parameter.

2. The method of claim 1, wherein the small data rate control parameter comprises a number of packets per time unit.

3. The method of claim 2, wherein the small data rate control parameter is included in a protocol configuration option PCO.

4. The method of claim 1, wherein the RAT type is determined by long term evolution, machine type, communication, LTE-M, or new radio, NR.

5. A method performed by an access management function, AMF, in a wireless communication system, the method comprising:

transmitting a first message to a session management function, SMF, wherein the first message comprises a radio access technology, RAT, type of a user equipment, UE; and

Receiving a second message from the SMF, wherein the second message includes a small data rate control parameter,

wherein whether to apply a small data rate control function to the UE is determined by the SMF based on the RAT type.

6. The method of claim 5, wherein the small data rate control parameter comprises a number of packets per time unit.

7. The method of claim 6, wherein the small data rate control parameter is included in a protocol configuration option PCO.

8. The method of claim 5, wherein the RAT type is determined by long term evolution machine type communication, LTE-M, or new radio, NR.

9. A session management function, SMF, in a wireless communication system, the SMF comprising:

a transceiver; and

a controller configured to:

the method comprises receiving a first message from an access management function, AMF, via the transceiver, wherein the first message comprises a radio access technology, RAT, type of a user equipment, UE, determining whether to apply a small data rate control function to the UE based on the RAT type, and sending a second message to the AMF via the transceiver, wherein the second message comprises a small data rate control parameter.

10. The SMF of claim 9, wherein the small data rate control parameter comprises a number of packets per time unit.

11. The SMF of claim 10, wherein the small data rate control parameter is included in a protocol configuration option PCO.

12. The SMF of claim 9, wherein the RAT type is determined by long term evolution machine type communication, LTE-M, or new radio, NR.

13. An access management function, AMF, in a wireless communication system, the AMF comprising:

a transceiver; and

a controller configured to:

transmitting a first message to a session management function, SMF, via the transceiver, wherein the first message comprises a radio access technology, RAT, type of a user equipment, UE, and receiving a second message from the SMF, wherein the second message comprises small data rate control parameters, and wherein whether to apply a small data rate control function to the UE is determined by the SMF based on the RAT type.

14. The AMF of claim 13, wherein the small data rate control parameter comprises a number of packets per time unit, and wherein the small data rate control parameter is included in a protocol configuration option PCO.

15. The AMF of claim 13, wherein the RAT type is determined by long term evolution machine type communication, LTE-M, or new radio, NR.