Communication method, base station, and program for a terminal to transmit and receive user data via a control plane

Abstract

To provide a communication method or the like that realizes low delay of user data within a core system when a terminal transmits and receives user data via a control plane.SOLUTION: In a communication method in which a terminal transmits and receives user data between a base station and a core system via a control plane, the base station transmits and receives user data to and from the terminal via the control plane, and to and from a user plane function of the core system. The base station also transmits and receives control data that is transmitted and received from the terminal via the control plane to and from the control plane function of the core system. According to the 5GS standard mobile communication system, a terminal includes user data in a terminal-base station functional layer (RRC) packet rather than a terminal-core system functional layer (NAS) packet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a technique in which a terminal transmits user data to a base station and a core system via a control plane.

Background Art

[0002] FIG. 1 is a configuration diagram of a mobile communication system.

[0003] According to FIG. 1, for example, a mobile communication system based on the 5GS (5GS: 5th Generation System) standard is shown. This system is composed of a plurality of base stations 1, a movable terminal 2, and a core system 3. Also, it is assumed that the edge server 4 is physically or logically arranged under a neighboring base station 1.

[0004] [Base Station 1] The base station 1 functions as a single RAN (Radio Access Network) composed of a plurality of antenna stations and a control station. According to 5G, the base station is called a "gNB" and communicates wirelessly with a plurality of terminals 2.

[0005] [Terminal 2] The terminal 2 communicates wirelessly with the base station 1 and is accommodated in the core system 3 via the base station 1. The terminal is generally called a "UE (User Equipment)". The terminal 2 is assumed to be, for example, an IoT (Internet of things) device. IoT devices often have poor power supply, and it is important to reduce power consumption. Among them, communication processing requires the main power consumption in IoT devices. In particular, the increase in user data leads to an increase in protocol processing (such as addition and deletion of IP headers) in the wireless section, increasing power consumption.

[0006] [Core System 3] The core system 3 is composed of a control plane function (device) 31 and a user plane function (device) 32. The Control-Plane function 31 is a group of network devices that transmit and receive control signals such as communication establishment, and has the following group of network devices. AMF (Access and Mobility Management Function) SMF (Session Management Function) The AMF is responsible for unified registration management, connection management, and mobility management for the terminal. The SMF is responsible for assigning IP (Internet Protocol) addresses to the terminal and session management for the UPF. The User-Plane function 32 has a group of UPF (User Plane Function) devices for transmitting and receiving user data. The UPF establishes a session with the terminal and is responsible for routing and transfer processing of user data.

[0007] [Edge Server 4] Edge Server 4 is assumed to be, for example, an MEC (Multi-access Edge Computing) server. The MEC server here functions as edge computing considering access from IoT devices as Terminal 2.

[0008] Figure 2 is a sequence diagram in the prior art.

[0009] According to Figure 2, it represents the sequence of data transfer of Control Plane CIoT 5GS Optimization (see, for example, Non-Patent Document 1). This transfers user data on the control plane (control signal) for terminals such as 5G Stand Alone (SA) IoT devices. As a result, the wireless establishment of the user plane (session for user data) and the processing of adding and deleting headers such as IP are eliminated, contributing to reducing the communication power consumption at the terminal.

[0010] According to FIG. 2, a user plane session is not established between the radio section between the terminal 2 and the base station 1 and the section between the base station 1 and the UPF 32. Furthermore, a user plane (N4-u Session) is established in the section between the control plane function 31 (SMF) and the user plane function 32 (UPF) of the core system 3.

[0011] The terminal 2 stores user data in NAS (Non-Access Stratum), which is the control plane protocol between the terminal and the AMF. The NAS packet is transmitted to the base station 1 over RRC (Radio Resource Control), which is the control plane protocol between the terminal and the base station. The base station 1 transfers the NAS packet (user data) received from the terminal 2 to the AMF of the control plane function 31. The AMF transfers the user data to the SMF. The SMF of the control plane function 31 transfers the received user data to the UPF of the user plane function 32 via the N4-u Session.

[0012] According to FIG. 2, user data is transferred to different UPFs of the user plane function 32 according to its destination. According to FIG. 2(a), the UPF of the user plane function 32 transfers user data to the target server using the Point-to-Point Protocol. Also, according to FIG. 2(b), the UPF of the user plane function 32 transfers user data to the MEC server 4 using the Point-to-Point Protocol. In this case, the terminal 2, the base station 1, and the MEC server 4 are transferred to a UPF that is physically or logically adjacent.

[0013] Note that FIG. 2 describes the user data in the uplink direction, but the downlink user data is also transferred through the same path.

Prior Art Documents

Non-Patent Documents

[0014] [Non-Patent Document 1] 3GPP TS 23.501, [online], [searched on August 17, 2022], Internet <URL:https: / / www.3gpp.org / ftp / Specs / archive / 23_series / 23.501 / > [Non-Patent Document 2] 3GPP TS 23.502, [online], [searched on August 17, 2022], Internet <URL: https: / / www.3gpp.org / ftp / Specs / archive / 23_series / 23.502 / > [Summary of the Invention] [Problems to be Solved by the Invention]

[0015] According to the above-described prior art, since the terminal can transmit and receive user data via the control plane session without establishing a user plane session, it contributes to reducing the communication power consumption in the terminal. On the other hand, as a low-power IoT device, wearable devices such as body monitoring are assumed. Even for such IoT devices, in addition to reducing power consumption, communication with low latency has also been required.

[0016] However, according to the above-described sequence, although the reduction of latency in the section between the terminal and the base station (edge equipment) is considered, the reduction of latency in the section within the core system is not considered.

[0017] As the sequence within the core system 3 in FIG. 2(b) described above, the control plane function 31 is selected to pass through the user plane function 32 that becomes a local station with respect to the MEC server 4 that transmits and receives user data to and from the terminal 2. Nevertheless, the user data will pass through the control plane function 31 located at the central office. As a result, the propagation delay within the core system 3 increases, resulting in a problem that communication with low latency cannot be achieved. Of course, in order to achieve low latency of user data by using the Control Plane CIoT 5GS Optimization function, it is also conceivable to place the control plane functions 31 (AMF and SMF) closer to the edge near the local station. However, this leads to an increase in introduction costs and complexity in cooperation with other communication facilities such as other control plane functions 31.

[0018] Therefore, an object of the present invention is to provide a communication method, a base station, and a program that realize low latency of user data within a core system when a terminal transmits and receives user data via a control plane.

Means for Solving the Problem

[0019] According to the present invention, in a communication method in which a terminal transmits and receives user data to and from a base station and a core system via a control plane, When the base station receives a session establishment request to transmit and receive user data from the terminal via a control session, it transfers the session establishment request to the control plane function of the core system. The user plane function of the core system establishes a user plane session with the base station according to an instruction from the control plane function of the core system, without assigning an IP address to the terminal. the base station transmits and receives user data transmitted and received via the control plane to and from the user plane function of the core system. This is the feature.

[0020] According to another embodiment of the communication method of the present invention, it is also preferable that the base station transmits and receives control data transmitted and received via the control plane to and from the control plane function of the core system. This is also preferable.

[0021] According to another embodiment of the communication method of the present invention, The terminal includes user data in packets of the terminal-base station inter-functional layer instead of packets of the terminal-core system inter-functional layer. This is also preferable.

[0022] According to another embodiment of the communication method of the present invention, According to a mobile communication system of the 5GS (5th Generation System) standard, The terminal-core system inter-functional layer is based on NAS (Non-Access Stratum), The terminal-base station inter-functional layer is based on RRC (Radio Resource Control). This is also preferable.

[0025] According to another embodiment of the communication method of the present invention, The base station does not establish a user plane session with the terminal. This is also preferable.

[0026] According to another embodiment of the communication method of the present invention, During a location registration sequence executed between the terminal and the control plane function of the core system via the base station, the terminal notifies the base station and the control plane function of the core system of a flag indicating whether to transmit user data via the control plane. This is also preferable.

[0027] According to another embodiment of the communication method of the present invention, Among a plurality of user plane functions of the core system, a user plane function capable of communicating with an edge server physically or logically adjacent to the base station communicating with the terminal is selected. User data is transmitted and received between the terminal and the edge server. This is also preferable.

[0028] According to the present invention, in a base station interposed between a terminal and a core system and transmitting and receiving user data via a control plane, When the base station receives a session establishment request to transmit and receive user data from the terminal via a control session, it transfers the session establishment request to the control plane function of the core system. According to the instruction from the control plane function of the core system to the user plane function of the core system, it establishes a user plane session with the user plane function of the core system, without assigning an IP address to the terminal. Terminal Transmit and receive user data transmitted and received via the control plane between the end and the core system to and from the user plane function of the core system characterized by.

[0029] According to the present invention, in a program that causes a computer mounted on a base station that is interposed between a terminal and a core system and transmits and receives user data via a control plane to function, When the base station receives a session establishment request to transmit and receive user data from the terminal via a control session, it transfers the session establishment request to the control plane function of the core system. According to the instruction from the control plane function of the core system to the user plane function of the core system, it establishes a user plane session with the user plane function of the core system, without assigning an IP address to the terminal. Terminal Transmit and receive user data transmitted and received via the control plane between the end and the core system to and from the user plane function of the core system characterized by causing the computer to function as follows.

Effect of the Invention

[0030] According to the communication method, base station, and program of the present invention, when a terminal transmits and receives user data via a control plane, it is possible to reduce the latency of user data in the core system.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0033] Figure 3 is a sequence diagram in the present invention.

[0034] According to FIG. 3, similar to FIG. 2 described above, it represents a communication method in which the terminal 2 transmits and receives user data between the base station 1 and the core system 3 via the control plane.

[0035] [Terminal 2] According to the 5GS standard mobile communication system, the protocol configuration in the control plane is as follows. Terminal Base Station Core System (AMF) <----------------NAS-----------------> <-----RRC---->(Base Station)<----NGAP----> According to FIG. 3, compared with FIG. 2, the terminal 2 includes user data in packets of the terminal-base station inter-functional layer instead of packets of the terminal-core system inter-functional layer. Terminal-Core System Inter-Functional Layer: NAS (Non-Access Stratum) Terminal-Base Station Inter-Functional Layer: RRC (Radio Resource Control) Base Station-Core System Inter-Functional Layer: NGAP (NG Application Protocol)

[0036] That is, the terminal 2 includes user data in RRC packets in the control plane. For example, a flag such as "User Data Transfer" is added to the RRC packets. By storing user data in RRC packets without storing it in NAS packets, the base station 1 can acquire the user data.

[0037] Although not shown in FIG. 3, for "control data", the terminal 2 includes it in NAS packets of the control plane and transmits it to the AMF via the base station 1 in the same manner as in the prior art.

[0038] [Base Station 1] According to FIG. 3, compared with FIG. 2, Base Station 1 relays and controls between Terminal 2 and Core System 3 as follows. (1) Base Station 1 transmits and receives the "user data" transmitted and received via the control plane between Base Station 1 and Terminal 2 to and from the user plane function (UPF) 32 of Core System 3. (2) Base Station 1 transmits and receives the "control data" transmitted and received via the control plane between Base Station 1 and Terminal 2 to and from the control plane function (AMF) 31 of the core system.

[0039] Base Station 1 establishes a user plane N3 session with the UPF. At this time, the UPF does not assign an IP address to Terminal 2. That is, similar to FIG. 2, Base Station 1 does not establish a user plane session with Terminal 2. In addition, Base Station 1 maintains a "UE Context" that associates the user plane N3 session between the Base Station 1 and the UPF with Terminal 2.

[0040] According to FIG. 3, since the user data via the control plane between Terminal 2 and Base Station 1 does not pass through the control plane function 31 of Core System 3, low latency can be achieved. Also, when the destination of the user data is the MEC server 4, the user plane function 32 physically or logically adjacent to Terminal 2 and Base Station 1 is selected.

[0041] According to FIG. 3, Base Station 1 receives an RRC packet including user data from Terminal 2 via the control plane. Then, Base Station 1 transfers the user data stored in the RRC packet to the UPF via the user plane session. The UPF transfers the user data to the MEC server 4 via the user plane session. Terminal <---RRC---> (Base Station) <---GTP---> Core System (UPF) GTP: GPRS (General Packet Radio System) Tunneling Protocol

[0042] Also, according to FIG. 3, the user data transmitted from the MEC server 4 is also transferred to the terminal 2 in the reverse direction of FIG. 3. The UPF transfers the user data received from the MEC server 4 to the base station 1 via the user plane session. The base station 1 stores the user data in the RRC packet and transfers it to the terminal 2 via the control plane.

[0043] The essential feature of the present invention lies in the "base station". The base station is interposed between the terminal and the core system, transmits and receives user data to and from the terminal via the control plane, and transmits and receives the user data to and from the user plane function via the user plane session. The present invention is realized with only the "base station" as the simplest configuration. It is also realized as a program that functions the computer mounted on the base station.

[0044] FIG. 4 is a sequence diagram for establishing the session of the present invention.

[0045] (S1) The terminal 2 transmits a "location registration request" to the base station 1. Thereby, the terminal 2 starts a location registration sequence with the control plane function 31 of the core system 3 via the base station 1. The NAS packet of the location registration request in the control plane is attached with a "flag indicating whether to transmit user data via the control plane" (a flag indicating the execution of the present invention). 「C-Plane user data low-latency forwarding」 The terminal 2 attaches the flag and notifies the base station 1 and the control plane function 31 of the core system 3.

[0046] The base station 1 transfers its location registration request to the AMF (control plane function 31 of the core system 3). Here, the AMF recognizes the flag included in the location registration request. The AMF responds with "permitted" or "not permitted" in the execution of the present invention by attaching the same flag to the location registration response. The location registration response is sent back from the AMF via the base station 1 to the terminal 2.

[0047] (S2) Next, the terminal 2 sends a "PDF session establishment request" to the base station 1. Thereby, the terminal 2 attempts to establish a user plane session with the user plane function 32 of the core system 3 via the base station 1. When the base station 1 receives a session establishment request from the terminal 2, it transfers the session establishment request to the control plane function 31 of the core system 3.

[0048] Regarding the control plane function 31, the AMF instructs the SMF to establish a session with the terminal 2. At this time, a flag representing the execution of the present invention as follows is attached to the protocol N11. 「C-Plane user data low-latency forwarding」

[0049] Next, the SMF sends a user plane establishment instruction to the UPF in response to the instruction from the AMF. At this time, among the multiple UPFs of the core system 3, a UPF that can communicate with the edge server 4 physically or logically adjacent to the base station 1 that communicates with the terminal 2 is selected.

[0050] The UPF that receives the user plane establishment instruction establishes a user plane N3 session with the base station 1. At this time, the UPF only establishes a GTP tunnel for the N3 session with the base station 1 without assigning an IP address to the terminal 2.

[0051] The SMF of the core system 3 notifies the AMF of the completion of the session establishment at the UPF.

[0052] Then, the AMF of the core system 3 returns a "PDU session establishment response" to the terminal 2 via the base station 1. A flag representing the execution of the present invention is added to the protocol N11 in the PDU session establishment response as follows. "C-Plane user data low-latency forwarding" In addition, the PDU session establishment response also includes the N2 SM information (UE Context) and is transmitted to the base station 1. When the base station 1 recognizes that "the present invention is executed", it holds the N2 SM information (UE Context). When the base station 1 receives user data from the terminal 2 via the control plane, it recognizes, based on the N2 SM information, which N3 session should be used to transfer the user data to the UPF. Conversely, when receiving user data from the UPF via the N3 session, it recognizes which control plane should be used to transfer the user data to the terminal 2.

[0053] (S3) After executing the PDU session establishment sequence of S2, the base station 1 holds the "UE Context" that associates the user plane N3 session with the terminal 2. Thereby, as shown in FIG. 3 described above, the base station 1 transmits and receives user data between the terminal 2 and the MEC server 4.

[0054] As described in detail above, according to the communication method, base station, and program of the present invention, when the terminal transmits and receives user data via the control plane, the user data does not pass through the control plane function of the core system, so that low latency of user data in the core system can be realized. The transmission and reception of user data via the control plane are effective for low-power terminals such as IoT devices. In addition, within the core system, in order for the user plane function physically or logically adjacent to the terminal and the base station to be selected, low latency can be achieved when the destination of user data is the MEC server. Furthermore, in order to achieve low latency of user data via the control plane in the terminal, there is no need to separately install equipment in the core system, and it is not necessary to reduce the introduction cost or perform special cooperation control with other control plane functions.

[0055] Furthermore, thereby, for example, "when a low-power terminal such as an IoT device transmits and receives user data via the control plane, low latency of user data within the core system is achieved", which can contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization, and foster innovation".

[0056] Regarding the various embodiments of the present invention described above, various changes, modifications, and omissions within the scope of the technical idea and perspective of the present invention can be easily made by those skilled in the art. The above description is merely an example and is not intended to impose any restrictions. The present invention is limited only by the claims and their equivalents.

Explanation of Reference Numerals

[0057] 1 Base station 2 Terminal, IoT device 3 Core system 31 Control plane function 32 User plane function 4 MEC server, Edge server

Claims

1. In a communication method in which a terminal transmits and receives user data to and from a base station and a core system via a control plane, when the base station receives a session establishment request for transmitting and receiving user data via a control session from the terminal, the base station transfers the session establishment request to the control plane function of the core system. The user plane function of the core system establishes a user plane session with the base station according to an instruction from the control plane function of the core system, and without assigning an IP address to the terminal. The base station transmits and receives user data transmitted and received via the control plane between the terminal and the user plane function of the core system. A communication method characterized by the above.

2. The base station transmits and receives control data transmitted and received via the control plane between the terminal and the control plane function of the core system. The communication method according to claim 1, characterized by the above.

3. The terminal includes user data in a packet of a terminal-base station inter-functional layer instead of a packet of a terminal-core system inter-functional layer. The communication method according to claim 1 or 2, characterized by the above.

4. According to a mobile communication system of 5GS (5th Generation System) standard, the terminal-core system inter-functional layer is based on NAS (Non-Access Stratum), and the terminal-base station inter-functional layer is based on RRC (Radio Resource Control). The communication method according to claim 3, characterized by the above.

5. The base station does not establish a user plane session with the terminal. The communication method according to claim 1 or 2, characterized by the above.

6. When performing a location registration sequence executed between the terminal and the control plane function of the core system via the base station, the terminal notifies the base station and the control plane function of the core system of a flag indicating whether to transmit user data via the control plane. The communication method according to claim 1 or 2, characterized by the above.

7. Among a plurality of user plane functions of the core system, a user plane function capable of communicating with an edge server physically or logically adjacent to the base station communicating with the terminal is selected. User data is transmitted and received between the terminal and the edge server. The communication method according to claim 1 or 2, characterized in that.

8. In a base station that is interposed between a terminal and a core system and transmits and receives user data via a control plane, When receiving a session establishment request for transmitting and receiving user data via a control session from a terminal, transferring the session establishment request to the control plane function of the core system, Establishing a user plane session with the user plane function of the core system according to an instruction from the control plane function of the core system to the user plane function of the core system, and without assigning an IP address to the terminal, Transmitting and receiving user data transmitted and received via the control plane between the terminal and the user plane function of the core system. A base station characterized by the above.

9. In a program that functions a computer installed in a base station that is interposed between a terminal and a core system and transmits and receives user data via a control plane, When receiving a session establishment request for transmitting and receiving user data via a control session from a terminal, transferring the session establishment request to the control plane function of the core system, Establishing a user plane session with the user plane function of the core system according to an instruction from the control plane function of the core system to the user plane function of the core system, and without assigning an IP address to the terminal, Transmitting and receiving user data transmitted and received via the control plane between the terminal and the user plane function of the core system. A program characterized by functioning the computer as described above.

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