Radio system and communication control method

Abstract

In the present invention, an AMF transmits, to a radio access network to which a user terminal device is connected, an NAS establishment request for establishing an NAS in order for the user terminal device to transfer application layer data, and prioritizes and establishes, according to a prescribed priority setting condition and between the radio access network and the user terminal device, an SRB for transmitting an NAS message in the NAS.

Description

Wireless system and communication control method

[0001] This application claims priority to Japanese Patent Application No. 2023-167541, filed on September 28, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, a fifth-generation mobile communication system (5G system) standardized by the "3rd Generation Partnership Project" is known (see, for example, Non-Patent Documents 1-4). FIG. 9 is a diagram showing a schematic architecture of a 5G system. In FIG. 9, the 5G system is composed of a UE (User Equipment), a RAN (Radio Access Network), a CN (Core Network), etc.

[0003] The CN is composed of NFs (Network Functions) of the control plane (C-plane), such as AMF (Access and Mobility Management Function), UDM (Unified Data Management), and NWDAF (Network Data Analytics Function). In a 5G system, the NWDAF collects and analyzes data from NFs of the 5G Core Network (5GC). For example, network analysis is performed by collecting App-D (Application Layer Data) of the UE (User Equipment).

[0004] Non-Patent Document 3 describes an App-D collection method using a C-plane as a method for collecting UE App-D. Non-Patent Document 2 describes an App-D collection method using a user plane (U-plane) as a method for collecting UE App-D.

[0005] Non-Patent Document 4 also describes how to handle NAS (Non-Access-Stratum) messages, App-MR (Application Layer Measurement Report), and the like in the RRC (Radio Resource Control) layer. For example, it describes how to use different types of SRBs (Signaling Radio Bearers).

[0006] 3GPP (registered trademark), TS 23.501, V18.2.2, 2023-07 3GPP (registered trademark), TS 23.288, V18.2.0, 2023-06 3GPP (registered trademark), TS 28.405, V18.3.0, 2023-06 3GPP (registered trademark), TS 38.331, V17.5.0, 2023-06

[0007] However, the App-D collection method using the C-plane described in Non-Patent Document 3 is inefficient because messages that do not require interpretation in the RAN must be interpreted and converted in the RAN. Also, the App-D collection method using the U-plane described in Non-Patent Document 2 collects App-D using a route that passes through a Data Network (DN) that exists outside the operator-managed domain, making it impossible to control end-to-end Quality of Service (QoS).

[0008] Furthermore, the method of selectively using a plurality of types of SRBs described in Non-Patent Document 4 was sometimes insufficient in prioritizing NAS messages and the like.

[0009] The present disclosure has been made in consideration of these circumstances, and an example of a purpose thereof is to provide appropriate prioritization for NAS messages.

[0010] One aspect of the present disclosure is a wireless system in which an AMF (Access and Mobility Management Function) transmits a NAS establishment request to a wireless access network to which the user terminal device is connected, the NAS establishment request establishing a NAS (Non-Access-Stratum) for a user terminal device to transfer application layer data, and establishes an SRB (Signaling Radio Bearer) between the wireless access network and the user terminal device, prioritizing the SRB according to predetermined priority setting conditions, for transmitting a NAS message in the NAS. One aspect of the present disclosure is a wireless system in which an AMF (Access and Mobility Management Function) transmits to a user terminal device a NAS establishment request for establishing a NAS (Non-Access-Stratum) for the user terminal device to transfer application layer data, and the user terminal device transmits to a radio access network to which the user terminal device connects an SRB establishment request for establishing an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS, and the SRB is prioritized and established between the radio access network and the user terminal device according to a predetermined priority setting condition. Another aspect of the present disclosure is the wireless system, in which the priority setting condition is a priority indicated by the AMF. Another aspect of the present disclosure is the wireless system, in which the priority setting condition is a lower priority than an SRB essential for communication already established for the user terminal device.

[0011] One aspect of the present disclosure is a communication control method executed by a wireless system, the communication control method including: a NAS establishment request sending step in which an AMF (Access and Mobility Management Function) sends a NAS establishment request to a wireless access network to which the user terminal device is connected, the NAS establishment request establishing a NAS (Non-Access-Stratum) for a user terminal device to transfer application layer data; and an SRB establishment step in which an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS is established between the wireless access network and the user terminal device by prioritizing the SRB according to a predetermined priority setting condition. One aspect of the present disclosure is a communication control method executed by a wireless system, the communication control method including: a NAS establishment request sending step in which an AMF (Access and Mobility Management Function) sends to a user terminal device a NAS establishment request to establish a NAS (Non-Access-Stratum) for the user terminal device to transfer application layer data; an SRB establishment request sending step in which the user terminal device sends to a wireless access network to which the user terminal device is connected an SRB establishment request to establish an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS; and an SRB establishment step in which the SRB is prioritized and established between the wireless access network and the user terminal device according to predetermined priority setting conditions.

[0012] According to the present disclosure, as one example, an effect can be obtained in which appropriate prioritization can be achieved for NAS messages.

[0013] FIG. 1 is a diagram showing a schematic architecture of a wireless system according to an embodiment. FIG. 2 is a block diagram showing a schematic configuration example of a network device according to an embodiment. FIG. 3 is a block diagram showing a schematic configuration example of a network device according to an embodiment. FIG. 4 is a sequence diagram showing an example of the procedure of a data collection method according to an embodiment. FIG. 5 is a sequence diagram showing an example of the procedure of a communication control method according to an embodiment. FIG. 6 is a sequence diagram showing an example of the procedure of a communication control method according to an embodiment. FIG. 7 is a sequence diagram showing an example of the procedure of a communication control method according to an embodiment. FIG. 8 is a diagram showing a schematic architecture of a conventional 5G system.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a diagram showing a schematic architecture of a wireless system according to one embodiment. The wireless system 1 shown in Fig. 1 further includes an NWDAF-APP as an NF of the C-plane of the CN in the 5G system shown in Fig. 9. Note that the NWDAF-APP may be included in the NWDAF as a part of the NWDAF.

[0015] Fig. 2 is a block diagram showing an example of a schematic configuration of a network device 100 according to this embodiment. The network device 100 shown in Fig. 2 is a device that supports NWDAF-APP. In Fig. 2, the network device 100 includes an App-D request receiving unit 101, a NAS message transmission request transmitting unit 102, an App-D receiving unit 103, and an App-D transferring unit 104.

[0016] Each function of the network device 100 is realized by the network device 100 including computer hardware such as a CPU (Central Processing Unit) and memory, and the CPU executing a computer program stored in the memory. The network device 100 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device. For example, the network device 100 may be configured using a server computer connected to a communication network such as the Internet. Each function of the network device 100 may be realized by cloud computing. The network device 100 may be realized by a single computer, or may be realized by distributing the functions of the network device 100 across multiple computers.

[0017] The App-D request receiving unit 101 receives a request (application layer data request (App-D request)) to obtain application layer data (App-D) from a user terminal device (UE) related to network data analysis requested by the NWDAF (network data analysis function).

[0018] The NAS message transmission request transmission unit 102 transmits a NAS message (first NAS message) instructing the AMF to transfer App-D (Application Layer Data Transfer (App-DT)) to a UE related to the network data analysis. A request (NAS message transmission request) is transmitted.

[0019] The App-D receiving unit 103 receives the App-D transferred from the UE in response to the first NAS message from the AMF. The App-D transferring unit 104 transfers the App-D received from the AMF to the NWDAF. Note that if the NWDAF-APP is included in the NWDAF as part of the NWDAF, the App-D transferring unit 104 is not required.

[0020] 3 is a block diagram showing a schematic configuration example of a network device 200 according to this embodiment. The network device 200 shown in FIG. 3 is a device corresponding to the AMF in a conventional 5G system. In this embodiment, changes are made to the AMF in the conventional 5G system. FIG. 3 shows additions and changes from the AMF in the conventional 5G system.

[0021] 3, the network device 200 includes a NAS message transmission request receiving unit 201 , a NAS message transmitting unit 202 , a NAS message receiving unit 203 , an App-D transmitting unit 204 , and an NGAP message transmitting unit 205 .

[0022] Each function of the network device 200 is realized by the network device 200 including computer hardware such as a CPU (Central Processing Unit) and memory, and the CPU executing a computer program stored in the memory. The network device 200 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device. For example, the network device 200 may be configured using a server computer connected to a communication network such as the Internet. Each function of the network device 200 may be realized by cloud computing. The network device 200 may be realized by a single computer, or may be realized by distributing the functions of the network device 200 across multiple computers.

[0023] The NAS message transmission request receiving unit 201 receives a NAS message transmission request from the network device 100 .

[0024] The NAS message transmitting unit 202 transmits a NAS message (first NAS message) instructing the UE to transfer App-D. The NAS message receiving unit 203 receives a NAS message (second NAS message) transmitted from the UE and including App-D transferred from the UE in response to the first NAS message. The App-D transmitting unit 204 transmits the App-D transferred from the UE to the network device 100.

[0025] The NGAP message sending unit 205 sends an NGAP (Next Generation Application Protocol) message to a RAN (Radio Access Network).

[0026] Next, a data collection method executed by the wireless system 1 according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a sequence diagram showing an example of the procedure of the data collection method according to this embodiment.

[0027] (Step S1) An NFc, which is an arbitrary NF, requests the NWDAF for network data analysis. This request for network data analysis requires information to determine target UEs, which are UEs or UEs related to the network data analysis, and may include, for example, an identifier of the target UE (e.g., SUPI, etc.). In response to the request for network data analysis, the NWDAF determines whether or not it is necessary to collect App-D for the target UE. If the result of this determination indicates that it is necessary to collect App-D for the target UE, the NWDAF executes the subsequent steps. On the other hand, if it indicates that it is not necessary to collect App-D for the target UE, it terminates the processing of FIG. 4.

[0028] (Steps S2 and S3) The NWDAF requests the UDM for information on the AMF in which the target UE is located, and obtains the information on the AMF from the UDM.

[0029] (Step S4) The NWDAF sends a request (App-D request) to acquire App-D from the target UE to the NWDAF-APP (network device 100). The NWDAF-APP (App-D request receiver 101) receives the App-D request from the NWDAF. The App-D request includes the identifier of the target UE and information about the AMF in which the target UE is located. The App-D request corresponds to a request for App-DT.

[0030] (Steps S5-S8) The NWDAF-APP communicates with the UDM according to a predetermined procedure to confirm the UE consent information regarding the App-DT of the target UE. If the confirmation result shows that the UE consent information is not obtained or the App-DT is rejected, the process of Fig. 4 is terminated. Otherwise, the process of Fig. 4 is continued.

[0031] The NWDAF-APP determines whether to execute the following steps based on the analysis request time and requested quality regarding the App-D request from the NWDAF, and the consent status of the target UE in the UE consent information. If the result of this determination is that the following steps are not to be executed, the processing of FIG. 4 is terminated, whereas if not, the following steps are executed.

[0032] (Step S9) The NWDAF-APP (NAS message transmission request transmitter 102) transmits a NAS message transmission request to the AMF (network device 200) in which the target UE resides. This NAS message transmission request is a request to issue an App-DT instruction to the target UE using a NAS message in the downlink (downlink (DL)) link (direction from the AMF to the UE). In addition, the signaling related to the NAS message transmission request may include an identifier indicating the QoS of the NAS signaling in the App-DT instruction from the AMF to the target UE, or an identifier indicating the QoS of the NAS signaling in the App-DT from the target UE to the AMF.

[0033] The AMF (NAS message transmission request receiving unit 201) receives a NAS message transmission request from the NWDAF-APP.

[0034] (Step S10) The AMF (NAS message transmitter 202) transmits a NAS message (first NAS message) indicating App-DT to the target UE. At this time, the AMF may perform a NAS signaling process so that the RAN to which the target UE is connected distinguishes between the first NAS message and other NAS messages and sets an appropriate QoS. Specifically, the AMF adds an identifier indicating the QoS (QoS identifier) ​​to the IE (Information Element) of the NGAP header of the "DL NAS TRANSFER message" in the NGAP layer. The RAN applies the QoS indicated by the QoS identifier in the IE of the NGAP header of the "DL NAS TRANSFER message" to the first NAS message. The QoS identifier may be included in a NAS message transmission request and notified to the AMF.

[0035] The target UE receives a first NAS message from the AMF via the RAN to which it connects.

[0036] (Step S11) The target UE stores the App-D indicated in the first NAS message in a NAS message (second NAS message) and transmits the second NAS message to the AMF. At this time, the target UE may assign appropriate priority to the second NAS message in the RRC (Radio Resource Control) layer.

[0037] The AMF (NAS message receiving unit 203) receives a second NAS message from the target UE.

[0038] (Step S12) The AMF (App-D transmitter 204) transmits the App-D stored in the second NAS message received from the target UE to the NWDAF-APP. The NWDAF-APP (App-D receiver 103) receives the App-D.

[0039] (Step S13) The NWDAF-APP (App-D transfer unit 104) transfers the App-D received from the AMF to the NWDAF.

[0040] (Step S14) The NWDAF performs the network data analysis requested by the NFc based on the App-D of the target UE received from the NWDAF-APP, and transmits the analysis result to the NFc.

[0041] According to this embodiment, the App-D of the UE can be collected using a NAS message. The NAS message is a message exchanged in the NAS between the UE and the AMF. Therefore, the RAN does not need to interpret the payload of the NAS message. Furthermore, the NAS message is a message between the UE and the AMF, that is, a C-plane message. Therefore, QoS control in the C-plane can be applied to the NAS message. As a result, according to this embodiment, it is possible to obtain the effect of improving the efficiency of collecting the App-D of the UE and QoS control.

[0042] Next, a method for dynamically prioritizing NAS signaling according to this embodiment will be described.

[0043] Non-Patent Document 4 describes how NAS messages are handled in the RRC layer. This point will be explained. When NAS messages are communicated between the RAN and the UE, SRBs (signaling radio bearers) are used in the RRC layer. Two types of SRBs (referred to as SRB1 and SRB2, respectively) that can be used by NAS messages are defined. A maximum of one SRB each of SRB1 and SRB2 is assigned to one UE. For example, one SRB of SRB1 and one SRB of SRB2 can be assigned to a certain UE, but two or more SRBs of either SRB1 or SRB2 cannot be assigned to a certain UE.

[0044] SRB1 and SRB2 are used differently depending on whether "AS (Access Stratum) security" is enabled between the UE and the network. Specifically, SRB1 is used before "AS security" is enabled (e.g., at the time of initial access), and SRB2 is used after "AS security" is enabled. Based on this differentiation, different priorities can be assigned to SRB1 and SRB2. Specifically, it is recommended to assign the highest priority to SRB1 and a medium priority to SRB2. That is, in Non-Patent Document 4, the priority of NAS messages in the RRC layer is determined only by whether "AS security" is enabled, and cannot be flexibly changed by operators depending on the content of the NAS messages.

[0045] Furthermore, Non-Patent Document 4 describes how APP-MR is handled in the RRC layer. This point will be explained. RRC messages for collecting App-D of a UE have been standardized, and among them, the message used when actually transmitting App-D from the UE to the network is called APP-MR. SRB4 is used in the RRC layer for APP-MR, while SRB0, SRB1, SRB2, and SRB3 are used for other RRC messages. The priority of SRB4 can be differentiated compared to the other SRBs (i.e., SRB0, SRB1, SRB2, and SRB3).

[0046] In the method for collecting UE App-D according to the present embodiment, the UE App-D is collected using NAS messages, but it is preferable to appropriately prioritize each NAS message by flexibly differentiating the priority of the NAS messages used for collecting UE App-D (the first NAS message and the second NAS message) from the priority of NAS messages used for purposes other than collecting UE App-D. For example, it is preferable to assign a higher priority to NAS messages essential for communication between the UE and the CN (e.g., PDU session activation) than to NAS messages used for collecting UE App-D (the first NAS message and the second NAS message).

[0047] The communication control method according to this embodiment will be described below.

[0048] [RAN-initiated Method] FIGS. 5 and 6 are sequence diagrams showing an example of the procedure of a communication control method based on the RAN-initiated method.

[0049] The procedure for activating the SRB will be described with reference to Figure 5. In advance, normal NAS messages (i.e., NAS messages used for purposes other than collecting the UE's App-D) can be communicated between the UE and the CN's NF (e.g., AMF).

[0050] (Step S101) The AMF (NGAP message sending unit 205) identifies the RAN in which the target UE is located (served RAN) and sends a NAS establishment request (NGAP message) to the served RAN to establish a NAS (NAS_X) for the target UE to transfer App-D.

[0051] Step S101 performed by the AMF may be initiated by the AMF itself, by signaling from another NF, or by NAS signaling from the target UE.

[0052] (Step S102) In response to the NAS establishment request, the serving RAN transmits "RRC Reconfiguration" signaling to the target UE. The "RRC Reconfiguration" signaling requests the target UE to establish an SRB (SRB_X) for transmitting NAS messages (the first NAS message and the second NAS message) in NAS_X, with the SRB prioritized according to a predetermined priority setting condition.

[0053] In addition, step S102 performed by the RAN may be initiated by the serving RAN without signaling from the AMF. Specifically, the serving RAN may perform step S102 when receiving a NAS message (first NAS message) corresponding to SRB_X from the AMF. In this case, the first NAS message corresponds to a NAS establishment request.

[0054] (Step S103) The target UE transmits "RRC Reconfiguration Complete" signaling to the serving RAN. The "RRC Reconfiguration Complete" signaling notifies the serving RAN that the SRB_X has been prioritized and established according to a predetermined priority setting condition.

[0055] The procedure for invalidating an SRB will be described with reference to FIG.

[0056] (Step S111) The AMF (NGAP message sending unit 205) identifies the RAN in which the target UE is located (served RAN) and sends a NAS discard request (NGAP message) to the served RAN to discard the NAS (NAS_X) for the target UE to transfer App-D.

[0057] Step S111 executed by the AMF may be initiated by the AMF itself, by signaling from another NF, or by NAS signaling from the target UE.

[0058] (Step S112) In response to the NAS discard request, the serving RAN transmits "RRC Reconfiguration" signaling to the target UE. The "RRC Reconfiguration" signaling requests the target UE to discard the SRB (SRB_X) for transmitting the NAS messages (the first NAS message and the second NAS message) in NAS_X.

[0059] In addition, step S112 performed by the RAN may be initiated by the serving RAN without signaling from the AMF. Specifically, the serving RAN may perform step S112 when a NAS message (first NAS message) corresponding to SRB_X is not received from the AMF for a certain period of time.

[0060] (Step S113) The target UE transmits "RRC Reconfiguration Complete" signaling to the serving RAN. The "RRC Reconfiguration Complete" signaling notifies the serving RAN that the SRB_X has been discarded.

[0061] [UE-initiated Method] FIGS. 7 and 8 are sequence diagrams showing an example of the procedure of a communication control method based on the UE-initiated method.

[0062] The procedure for activating the SRB will be described with reference to Figure 7. In advance, normal NAS messages (i.e., NAS messages used for purposes other than collecting the UE's App-D) can be communicated between the UE and the CN's NF (e.g., AMF).

[0063] (Step S201) The AMF (NAS message sending unit 202) sends a NAS establishment request (NAS message) to the target UE to establish a NAS (NAS_X) for the target UE to transfer App-D.

[0064] Step S201 performed by the AMF may be initiated by the AMF itself, by signaling from another NF, or by NAS signaling from the target UE.

[0065] (Step S202) In response to the NAS establishment request, the target UE transmits, by RRC signaling, an SRB establishment request to establish an SRB (SRB_X) for transmitting a NAS message in NAS_X to the RAN to which the target UE is connected (served RAN).

[0066] Note that step S202 executed by the target UE may be initiated by the target UE without signaling from the AMF. For example, the target UE may initiate step S202 when it becomes necessary to notify the CN of App (Application Layer) information in the target UE. Specifically, this may be when the remaining battery capacity of the target UE becomes sufficient to be above a certain level due to charging, making it possible to notify information.

[0067] (Step S203) In response to the SRB establishment request, the serving RAN transmits "RRC Reconfiguration" signaling to the target UE. The "RRC Reconfiguration" signaling requests the target UE to establish an SRB (SRB_X) for transmitting NAS messages (the first NAS message and the second NAS message) in NAS_X, with the SRB prioritized according to a predetermined priority setting condition.

[0068] (Step S204) The target UE transmits "RRC Reconfiguration Complete" signaling to the serving RAN. The "RRC Reconfiguration Complete" signaling notifies the serving RAN that the SRB_X has been prioritized and established according to a predetermined priority setting condition.

[0069] The procedure for invalidating an SRB will be described with reference to FIG.

[0070] (Step S211) The AMF (NAS message sending unit 202) sends a NAS discard request (NAS message) to the target UE to discard the NAS (NAS_X) for the target UE to transfer App-D.

[0071] Step S211 executed by the AMF may be initiated by the AMF itself, by signaling from another NF, or by NAS signaling from the target UE.

[0072] (Step S212) In response to the NAS discard request, the target UE transmits, by RRC signaling, an SRB discard request to discard the SRB (SRB_X) for transmitting the NAS message in NAS_X to the RAN to which the target UE is connected (served RAN).

[0073] Note that step S212 executed by the target UE may be initiated by the target UE without signaling from the AMF. For example, the target UE may initiate step S212 when it becomes necessary to terminate notifying the CN of App information in the target UE. Specifically, this may be when the remaining battery power of the target UE becomes less than a certain level.

[0074] (Step S213) In response to the SRB discard request, the serving RAN transmits "RRC Reconfiguration" signaling to the target UE. The "RRC Reconfiguration" signaling requests the target UE to discard the SRB (SRB_X) for transmitting the NAS messages (the first NAS message and the second NAS message) in NAS_X.

[0075] (Step S214) The target UE transmits "RRC Reconfiguration Complete" signaling to the serving RAN. The "RRC Reconfiguration Complete" signaling notifies the serving RAN that SRB_X has been discarded.

[0076] Next, an example of a priority setting condition for prioritizing an SRB (SRB_X) for transmitting NAS messages (first NAS message and second NAS message) in NAS_X is shown below.

[0077] (Example 1 of Priority Setting Condition) Example 1 of priority setting condition is a priority instructed by the AMF.

[0078] (Example 2 of Priority Setting Condition) Example 2 of priority setting condition is a condition that has a lower priority than an SRB that is essential for communication already established with the target UE. The SRB that is essential for communication already established with the target UE is, for example, SRB2. A specific example is shown below.

[0079] (Example 1) The priority is the same as that of SRB4 already established for the target UE. SRB4 has a lower priority than SRB2.

[0080] (Example 2) The priority is the same as the "default priority" of any SRB that has not yet been established for the target UE. The priority that is the same as the "default priority" of an SRB has a lower priority than SRB2.

[0081] (Example 3) The priority is the same as that of SRB4, which has not yet been established for the target UE. SRB4 has a lower priority than SRB2.

[0082] (Example 4) The priority is the same as that of one of the DRBs (Data Radio Bearers) already established in the target UE. The priority of a DRB (Data Radio Bearer) is lower than that of an SRB2.

[0083] (Example 5) The priority is the same as the "default priority" of any DRB that has not yet been established for the target UE. The priority that is the same as the "default priority" of the DRB has a lower priority than SRB2.

[0084] According to this embodiment, it is possible to flexibly differentiate the priority of NAS messages (first NAS message and second NAS message) used to collect UE App-D from the priority of NAS messages used for purposes other than collecting UE App-D, and to appropriately prioritize each NAS message. For example, a NAS message essential for communication between the UE and the CN (e.g., PDU session activation, etc.) can be assigned a higher priority than the NAS messages (first NAS message and second NAS message) used to collect UE App-D.

[0085] This will enable, for example, improvements to the overall quality of services in wireless networks, which will contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0086] The above has described in detail an embodiment of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0087] Furthermore, a computer program for implementing the functions of each of the above-described devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. Note that the term "computer system" may also include hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disc), or a storage device such as a hard disk built into a computer system.

[0088] Furthermore, the term "computer-readable recording medium" also includes a storage medium that stores a program for a certain period of time, such as a volatile memory (e.g., a dynamic random access memory (DRAM)) within a computer system that serves as a server or client when the program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may also be transmitted from a computer system that stores the program in a storage device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may also be a program that realizes part of the aforementioned functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the aforementioned functions in combination with a program already stored in the computer system.

[0089] According to the present disclosure, as one example, an effect can be obtained in which appropriate prioritization can be achieved for NAS messages.

[0090] 1...wireless system, 100...network device (NWDAF-APP), 101...App-D request receiving unit, 102...NAS message transmission request transmitting unit, 103...App-D receiving unit, 104...App-D forwarding unit, 200...network device (AMF), 201...NAS message transmission request receiving unit, 202...NAS message transmitting unit, 203...NAS message receiving unit, 204...App-D transmitting unit, 205...NGAP message transmitting unit

Claims

1. A wireless system in which an AMF (Access and Mobility Management Function) sends a NAS establishment request to a wireless access network to which the user terminal device is connected, to establish a NAS (Non-Access-Stratum) for a user terminal device to transfer application layer data, and establishes an SRB (Signaling Radio Bearer) between the wireless access network and the user terminal device, by prioritizing the SRB according to predetermined priority setting conditions, to transmit a NAS message in the NAS.

2. A wireless system in which an AMF (Access and Mobility Management Function) sends a NAS establishment request to a user terminal device to establish a NAS (Non-Access-Stratum) for the user terminal device to transfer application layer data, and the user terminal device sends an SRB establishment request to a wireless access network to which the user terminal device is connected to establish an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS, and the SRB is established between the wireless access network and the user terminal device by prioritizing it according to predetermined priority setting conditions.

3. The wireless system according to claim 1, wherein the priority setting condition is a priority instructed by the AMF.

4. The wireless system according to claim 1, wherein the priority setting condition is a lower priority than an SRB essential for communication already established with the user terminal device.

5. A communication control method executed by a wireless system, comprising: a NAS establishment request sending step in which an AMF (Access and Mobility Management Function) sends a NAS establishment request to a wireless access network to which the user terminal device is connected, the NAS establishment request establishing a NAS (Non-Access-Stratum) for a user terminal device to transfer application layer data; and an SRB establishment step in which an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS is established between the wireless access network and the user terminal device, by prioritizing the SRB according to a predetermined priority setting condition.

6. A communication control method executed by a wireless system, comprising: a NAS establishment request sending step in which an AMF (Access and Mobility Management Function) sends to a user terminal device a NAS establishment request to establish a NAS (Non-Access-Stratum) for the user terminal device to transfer application layer data; an SRB establishment request sending step in which the user terminal device sends to a wireless access network to which the user terminal device is connected an SRB establishment request to establish an SRB (Signaling Radio Bearer) for transmitting a NAS message in the NAS; and an SRB establishment step in which the SRB is prioritized and established between the wireless access network and the user terminal device according to a predetermined priority setting condition.

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