Communication method and system for restraining signaling of ran and core system when terminal transmits user data
By enabling IoT devices to transmit user data with the terminal context to a second base station, which creates tunnels with the core system's user plane function, the communication method reduces signaling and power consumption in 5G networks, addressing the challenges of high signaling activity and power consumption in IoT devices.
Patent Information
- Application Number
- JP2023211656
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-12-15
- Publication Date
- 2025-06-26
AI Technical Summary
In 5G mobile networks, IoT devices experience increased power consumption and communication processing load due to high signaling activity in the RAN and core systems, especially during handovers and data transmissions.
A communication method where a terminal establishes a connection with the control plane function of the core system via a first base station, receives the terminal context, disconnects from the first base station, connects to a second base station, and transmits user data along with the terminal context. The second base station then uses this context to create tunnels with the user plane function for efficient data transfer.
This method suppresses signaling in the RAN and core system, reducing congestion delay and power consumption for IoT devices, while maintaining efficient communication resource utilization.
Smart Images
Figure 2025095569000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the signaling technology of the RAN (Radio Access Network) and the core system when a terminal transmits user data.
Background Art
[0002] FIG. 1 is a configuration diagram of a mobile communication system.
[0003] According to FIG. 1, an example of a mobile communication system based on the 5GS (5th Generation System) standard is shown. This system is composed of a plurality of base stations 1 serving as the RAN, a movable terminal 2, and a core system 3.
[0004] [Base Station 1] Base station 1 functions as one RAN 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. According to FIG. 1, a first base station 11 and a second base station 12 that connect a wireless link according to the position of the terminal 2 are shown.
[0005] [Terminal 2] Terminal 2 connects a wireless link with base station 1 and is accommodated in core system 3 via that base station 1. The terminal is generally called a "UE (User Equipment)". As terminal 2, an IoT (Internet of things) device is assumed. Examples of IoT devices include EHealth (wearable devices) that can be worn by people and always measure physical conditions, and Smart manufacturing that efficiently controls production logistics.
[0006] IoT devices generally have limited power supply such as batteries, and it is important to reduce power consumption. In particular, power consumption in communication processing is high. As the amount of data transmitted and received between the IoT device and the base station 1 increases, the protocol processing of the wireless link (such as adding and deleting IP headers) also increases, and as a result, the power consumption also increases.
[0007] [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 2 and is responsible for routing and forwarding processing of user data. Note that the control plane function 31 and the user plane function 32 are composed of multiple devices, but are represented as one function according to Figure 1 for simplicity.
[0008] The destination device 4 with which the terminal 2 communicates may be, for example, a MEC (Multi-Access Edge Computing) server. When the destination of the user data is the MEC server 4, the user plane function 32 physically or logically adjacent to the terminal 2 and the base station 1 is selected.
[0009] Figure 2 is a sequence diagram of a communication method in the prior art.
[0010] According to Figure 2, when the terminal 2 (5G Stand Alone) transmits user data, a signaling sequence occurs in the RAN (the first base station 11 and the second base station 12) and the core system 3. In the 5G mobile network, in order to suppress the large amount of signaling in the control plane based on the service request from the terminal 2, UP (User Plane)-CIoT 5GS Optimization and RRC-Inactive state are adopted. According to Figure 2, it represents the data transfer sequence of UP-CIoT 5GS Optimization (see, for example, Non-Patent Document 1).
[0011] (S01) Assume that the terminal 2 has transitioned from the CM (Connection Management)-IDLE state in which the radio link is released to the CM-CONNECTED state in which the radio link is connected to the first base station 11.
[0012] The terminal 2 transmits a PDU session establishment request (Protocol Data Unit session establishment request) to the first base station 11 in order to establish a session with the control plane function 31 of the core system 3. The first base station 11 transfers the PDU session establishment request to the control plane function 31 of the core system 3. Thereby, a signaling sequence for session establishment is executed within the RAN and the core system 3.
[0013] The control plane function 31 of the core system 3 returns the PDU session establishment response to the first base station 11. The PDU session establishment response includes a UE Context (terminal context). The terminal context also includes the TEID (Tunnel Endpoint Identifier) and IP address of the user plane function 32, as well as other information such as forwarding rules and charging IDs. Then, the first base station 11 returns the PDU session establishment response to the terminal 2.
[0014] Here, by holding the terminal context, the first base station 11 can recognize which N3 session to use to transfer the user data received from the terminal 2 to the user plane function 32 of the core system 3. Conversely, it can recognize to which terminal 2 the user data received from the user plane function 32 of the core system 3 via the N3 session should be transferred.
[0015] After that, the terminal 2 transmits user data to the first base station 11. The first base station 11 transfers the user data to the user plane function 32 based on the terminal context. The user plane function 32 of the core system 3 transfers the user data to the destination device (server) 4.
[0016] (S02) Assume that the terminal 2 releases the radio link with the first base station 11, for example, by moving. At this time, according to the conventional general technology, the first base station 11 of the RAN releases the radio link of the terminal that has not communicated for a certain period of time for effective utilization of radio resources and discards the target terminal context. In contrast, according to UP-CIoT 5GS Optimization, the first base station 11 holds the terminal context without discarding it.
[0017] Next, assume that the terminal 2 transitions from the CM-IDLE state in which the radio link is released to the CM-CONNECTED state in which the radio link is connected to the second base station 12.
[0018] At this time, under the control within the RAN, the second base station 12 that becomes the handover destination requests the terminal context for the terminal 2 from the first base station 11 that becomes the handover source. In response, the first base station 11 transfers the held terminal context to the second base station. As a result, the second base station 12 can hold the terminal context for the terminal 2. Then, the second base station 12 can execute a signaling sequence for session establishment with the core system 3. By holding the terminal context, the second base station 12 can know the user plane function 32 of the core system 3 to which the user data received from the terminal 2 should be transferred.
[0019] Thereafter, the terminal 2 transmits (uploads) the user data to the second base station 12 on the RRC (Radio Resource Control) between the terminal and the base station. The second base station 12 transfers the user data received from the terminal 2 to the user plane function 32 based on the terminal context. The user plane function 32 transfers the user data to the destination device 4 using the Point-to-Point Protocol. Of course, not limited to the uplink user data, the downlink user data is also transferred through the same path.
[0020] That is, according to the UP-CIoT 5GS Optimization in FIG. 2, there is no need to execute a control plane sequence (e.g., a sequence based on handover) for generating a terminal context between the second base station 12 and the control plane function 31 of the core system 3. The terminal 2 only needs to transmit user data to the second base station 12 in RRC packets. This contributes to reducing the power consumption of communication processing in the terminal 2.
[0021] In addition, according to 3GPP (3rd Generation Partnership Project) (registered trademark), a technology of Small Data Transmission in RRC Inactive that reduces the sequence through the control plane has been defined for IoT devices that sporadically upload a small amount of data. Also, for the RRC-Inactive state, a technology that reduces the load of the radio link sequence for the terminal to resume communication of user data has been defined. However, the reduction of signaling overhead (efficiency improvement of message transfer) in Small Data Transmission in RRC Inactive is related to the radio link between the terminal and the RAN, not the section between the RAN and 5GC (5GS: 5th Generation Core System). On the other hand, in the 6G network, a technology is defined for connecting a large number of movable IoT devices to sporadically upload a small amount of data.
Prior Art Documents
Non-Patent Documents
[0022]
Non-Patent Document 1
Non-Patent Document 2
Non-Patent Document 3
Summary of the Invention
Problems to be Solved by the Invention
[0023] According to 5GC, before a terminal connects a radio link to a target base station for handover and transmits user data from the CM-IDLE state, a large amount of signaling (Service Request / AN Release) occurs in the RAN and core systems. When the terminal is an IoT device, due to its communication characteristic of generating sporadic data, the number of connections tends to increase. As a result, the signaling in the RAN and core systems also increases, and congestion delay may occur in some cases. In addition, not only in the RAN and core systems, but also for terminals of IoT devices, battery consumption may occur due to an increase in power consumption and communication processing load.
[0024] According to FIG. 2 described above, the first base station 11 serving as the handover source needs to hold the terminal context of the terminal 2 after the radio link with the terminal 2 is released. Also, after the terminal 2 connects a radio link to the second base station 12, a sequence for transferring the terminal context from the first base station 11 to the second base station 12 will be executed. Furthermore, the second base station 12 also needs to generate signaling with the core system 3 using the received terminal context. Thus, every time the terminal 2 hands over from the first base station 11 to the second base station 12, a large amount of signaling occurs in the RAN and the core system 3.
[0025] Therefore, an object of the present invention is to provide a communication method and system capable of suppressing signaling in a RAN and a core system when a terminal transmits user data.
Means for Solving the Problem
[0026] According to the present invention, there is provided a communication method in which a terminal communicates with a core system via a first base station or a second base station, when the terminal establishes a connection with the control plane function of the core system via the first base station, a first step of receiving the terminal context of the user plane function from the control plane function of the core system; after the terminal disconnects the radio link with the first base station, a second step of connecting the radio link with the second base station and transmitting user data and the terminal context; a third step in which the second base station transmits user data to the user plane function of the core system using the terminal context; and a fourth step in which the user plane function of the core system transfers the user data to the destination device characterized by comprising.
[0027] According to another embodiment of the communication method of the present invention, the terminal context is the TEID (Tunnel Endpoint Identifier) and IP address of the user plane function, Regarding the second step, it is also preferable that the first base station does not hold the terminal context This is also preferable.
[0028] According to another embodiment of the communication method of the present invention, Regarding the third step, the second base station creates an uplink tunnel with the user plane function of the core system using the terminal context, and transmits the user data to the user plane function of the core system through the uplink tunnel is also preferable.
[0029] According to another embodiment of the communication method of the present invention, Regarding the third step, the second base station creates a downlink tunnel with the user plane function of the core system using the terminal context. Regarding the fourth step, the user plane function of the core system creates a downlink tunnel with the second base station using the source IP address of the user data. It is also preferable to further include a fifth step of transmitting the user data received from the destination device to the second base station through the downlink tunnel. is also preferable.
[0030] According to another embodiment of the communication method of the present invention, When the terminal performs a location registration sequence executed with the control plane function of the core system via the first base station, the terminal notifies the control plane function of the core system of a flag indicating whether to perform the transfer of user data based on the first to fourth steps. Regarding the first step, The terminal transmits a session establishment request to the control plane function of the core system via the first base station. When the flag is true, the control plane function of the core system returns a session establishment response including the terminal context to the terminal. is also preferable.
[0031] According to another embodiment of the communication method of the present invention, Regarding the second step, the terminal includes the user data in a packet of the terminal-base station inter-functional layer based on RRC (Radio Resource Control) instead of a packet of the terminal-core system inter-functional layer. is also preferable.
[0032] According to another embodiment of the communication method of the present invention, The terminal is a mobile station, and the first base station and the second base station are fixed stations, or the terminal is a terrestrial station, and the first base station and the second base station are satellite stations which is also preferable.
[0033] According to the present invention, there is provided a communication system in which a terminal communicates with a core system via a first base station or a second base station, the terminal when establishing a connection with the control plane function of the core system via the first base station, has a first function of receiving the terminal context of the user plane function from the control plane function of the core system, and after disconnecting the radio link with the first base station, connects a radio link with the second base station and has a second function of transmitting user data and the terminal context and the second base station transmits the user data to the user plane function of the core system using the terminal context, and the user plane function of the core system transfers the user data to the destination device which is characterized in that.
Advantages of the Invention
[0034] According to the communication method and system of the present invention, signaling of the RAN and the core system can be suppressed when the terminal transmits user data.
Brief Description of the Drawings
[0035]
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0037] FIG. 3 is a sequence diagram of the communication method in the present invention.
[0038] According to FIG. 3, similar to FIG. 2 described above, it represents a communication method in which the terminal 2 communicates with the core system 3 via a plurality of base stations 1 (the first base station 11 and the second base station 12). Specifically, as a communication method, it represents the steps of the interaction between the terminal 2, the plurality of base stations 1, and the core system 3. Of course, it can also be understood as a communication system with the terminal 2, the plurality of base stations 1, and the core system 3 as their respective functions.
[0039] In addition, according to FIG. 3, similar to FIG. 1 described above, the terminal 2, the plurality of base stations 1, and the core system 3 are all represented as terrestrial ground stations. Also, the terminal 2 is represented as a mobile station, and the first base station 11 and the second base station 12 are represented as fixed stations.
[0040] (S1) When the terminal 2 establishes a connection with the control plane function 31 of the core system 3 via the first base station 11, the terminal context (UE Context) of the user plane function 32 in the terminal 2 is received from the control plane function 31 of the core system 3. Here, S1 in FIG. 3 is basically the same as S01 in FIG. 2, but the difference is that the first base station 11 includes the terminal context (N2 SM information) in the PDU session establishment response (protocol N11) and returns it to the terminal 2. As a result, the terminal 2 can receive the terminal context of the user plane function 32.
[0041] Here, the terminal context includes the TEID (Tunnel Endpoint Identifier) and IP address of the user plane function 32. <User plane function 32 of the core system 3> TEID: XXXX IP address: YYYY In addition, the terminal context also includes other information such as transfer rules and charging IDs. Note that the TEID should not overlap with other sessions established on the same RAN. Therefore, it is also preferable to set the value of the TEID of the user plane function 32 to a value based on the IP address assigned to the terminal 2 at the time of PDU session establishment.
[0042] (S2) Assume that the terminal 2 releases the radio link with the first base station 11 (RRC Release). At this time, the first base station 11, which is the handover source, discards the terminal context. The discard of the terminal context may occur after a certain period of time has elapsed after the release of the radio link. Or it may occur when the terminal 2 receives Small Data Transmission assistance information.
[0043] Thereafter, the terminal 2 connects the radio link with the second base station 12, which is the handover destination. Then, the terminal 2 transmits (uploads) the terminal context together with the user data to the second base station 12, which is the handover destination.
[0044] Here, there are the following two important features of the present invention. <1> The first base station 11, which is the handover source, discards and does not hold the terminal context (N2 SM information) after releasing the radio link with the terminal 2. <2> The second base station 12, which is the handover destination, receives the terminal context together with the user data after connecting the radio link with the terminal 2.
[0045] (S3) The second base station 12 creates an uplink tunnel with the user plane function 32 of the core system 3 by using the terminal context received from the terminal 2. Specifically, the second base station 12 temporarily establishes a GTP (GPRS (General Packet Radio System) Tunneling Protocol) tunnel (N3 session) for uplink user data transfer with the user plane function 32 based on the TEID (XXXX) and IP address (YYYY) of the user plane function 32 described in the terminal context.
[0046] Also, the second base station 12 may create a downlink tunnel with the user plane function 32 of the core system 3 by using the terminal context received from the terminal 2. Specifically, the second base station 12 temporarily establishes a GTP tunnel for downlink user data transfer based on the TEID (XXXX) of the user plane function 32 described in the terminal context and its own IP address (ZZZZ).
[0047] At this time, within the second base station 12 and the core system 3, there is no signaling to establish a user plane session in which the user plane function 32 assigns an IP address to the terminal 2. Also, according to S3 in FIG. 3, compared with S03 in FIG. 2, there is no need to execute a sequence to transfer the terminal context within the RAN (between the first base station 11 and the second base station 12). As a result, signaling generation is suppressed within the RAN and the core system 3, enabling efficient use of communication resources and reduction of congestion delay. Also, the terminal 2 has a reduced communication processing load, achieving a reduction in battery power consumption.
[0048] Then, the second base station 12 transfers the user data received from the terminal 2 to the user plane function 32 of the core system 3 through the uplink GTP tunnel. Specifically, only the uplink GTP header is added to the user data.
[0049] (S4) The user plane function 32 of the core system 3 transfers the user data received through the uplink GTP tunnel to the destination device 4. At this time, the user plane function 32 of the core system 3 temporarily establishes a downlink GTP tunnel (N3 session) with the second base station 12 using the source IP address (ZZZZ) of the user data. Specifically, the TEID of the GTP header of the packet of the user data received from the second base station 12 and the source IP address of the second base station 12 are used as the downlink GTP tunnel to update the terminal context of the user plane function 32.
[0050] (S5) Also, the user data transmitted from the destination device 4 to the terminal 2 is also transferred to the terminal 2 in the reverse direction of S4. The user plane function 32 of the core system 3 transfers the user data received from the destination device 4 to the second base station 12 through the downlink GTP tunnel. Then, the second base station 12 transfers the user data received from the user plane function 32 of the core system 3 to the terminal 2.
[0051] Finally, the second base station 12 and the user plane function 32 of the core system 3 discard the GTP tunnel information after a certain period of time or upon receiving the Small Data Transmission assistance information from the terminal 2. Then, the second base station 12 releases the radio link with the terminal 2.
[0052] Figure 4 is a sequence diagram showing the protocol configuration in the communication method of the present invention.
[0053] [Terminal 2] According to the 5GS standard mobile communication system, the protocol configuration in the control plane is as follows. Terminal <-------------NAS--------------> Control plane function of the core system NAS (Non-Access Stratum) Terminal <---RRC---> Base station <---NGAP----> Control plane function of the core system RRC (Radio Resource Control) NGAP (NG Application Protocol) Terminal <---RRC---> Base station <----GTP----> User plane function of the core system GTP (GPRS (General Packet Radio System) Tunneling Protocol)
[0054] (S1) Terminal 2 receives a PDU session establishment response including terminal content by means of an NAS packet from the control plane function 31 of the core system 3 via the first base station 11 of the handover source. (S2) Then, Terminal 2 transmits user data and terminal content to the second base station 12 of the handover destination by means of an RRC packet. For example, a flag such as "User Data Transfer" is attached to the RRC packet. When the second base station 12 receives the RRC packet with this flag attached, it recognizes that the terminal context is added. Then, the second base station 12 creates a downlink GTP tunnel using the terminal context and transfers the user data to the user plane function 32 of the core system 3 through that GTP tunnel.
[0055] Figure 5 is a sequence diagram for requesting permission to use the method of the present invention from the terminal to the core system.
[0056] (Assume that the terminal 2 has connected a radio link with the first base station 11.) First, the terminal 2 transmits a location registration request to the control plane function 31 of the core system 3 via the first base station 11. Here, the terminal 2 attaches an inquiry flag indicating whether the inventive method (transfer of user data based on the first to fourth steps) can be used to the location registration request in the NAS packet. Then, a location registration sequence is executed within the RAN and the core system 3.
[0057] (S1b) In response, if the control plane function 31 of the core system 3 can use the inventive method, it returns a location registration response with a permission flag attached to the terminal 2 via the first base station 11. Thereby, the terminal 2 recognizes that the use of the inventive method is permitted.
[0058] (S1c) Next, the terminal 2 transmits a PDU session establishment request to the control plane function 31 of the core system 3 via the first base station 11. Here, the terminal 2 attaches a usage flag requesting the use of the inventive method to the PDU session establishment request in the NAS packet. Then, a session establishment sequence is executed within the RAN and the core system 3.
[0059] (S1d) In response, the control plane function 31 of the core system 3 returns a PDU session establishment response with a terminal context attached to the terminal 2 via the first base station 11. Thereby, the terminal 2 can receive and hold the terminal context.
[0060] (S2) Thereafter, when the terminal 2 releases the radio link with the first base station 11, the first base station 11 discards the target terminal context for effective utilization of radio resources.
[0061] Figure 6 is a configuration diagram of a satellite communication system.
[0062] According to FIG. 6, compared with FIG. 1, it represents the case where the base station 1 is a satellite station. Assume that the terminal 2 and the core system 3 are terrestrial ground stations. According to FIG. 6, even if the terminal 2 is a fixed station, over time, the base station 1 connecting the wireless link will transition. Even in that case, the sequences of FIGS. 3 to 5 of the present invention described above can be executed.
[0063] As described in detail above, the communication method and system of the present invention can suppress the signaling of the RAN and the core system when the terminal transmits user data. Thereby, it is possible to reduce the congestion delay caused by the increase in signaling in the RAN and the core system. Also, for terminals such as IoT devices, the power consumption and the communication processing load can be reduced, and the battery consumption can be suppressed. In addition, in order to implement the present invention, it is not necessary to separately install equipment devices in the RAN or the core system, and it is not necessary to reduce the introduction cost or perform special cooperation control in the core system.
[0064] In addition, thereby, for example, "when the terminal hands over to a different base station and transmits user data, suppress the signaling generated in the RAN and the core system, and realize the reduction of the congestion delay of the entire system and the power consumption of the terminal", it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization, and foster innovation".
[0065] 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 only limited to the scope of the claims and their equivalents.
Description of Reference Numerals
[0066] 1 Base station 11 First base station, first satellite station 12 Second base station, second satellite station 2 Terminal, IoT device 3 Core system 31 Control plane function 32 User plane function 4 Destination device, MEC server
Claims
1. A communication method in which a terminal communicates with a core system via a first base station or a second base station, comprising: A first step in which, when the terminal establishes a connection with the control plane function of the core system via the first base station, the terminal receives the terminal context of the user plane function from the control plane function of the core system; A second step in which, after the terminal disconnects the radio link with the first base station, the terminal connects the radio link with the second base station and transmits user data and the terminal context; A third step in which the second base station uses the terminal context to transmit the user data to the user plane function of the core system; A fourth step in which the user plane function of the core system transfers the user data to the destination device The communication method is characterized by comprising the above steps.
2. The terminal context is the TEID (Tunnel Endpoint Identifier) and IP address of the user plane function, For the second step, the first base station does not hold the terminal context The communication method according to claim 1, characterized by the above.
3. For the third step, the second base station uses the terminal context to create an uplink tunnel with the user plane function of the core system, and transmits the user data to the user plane function of the core system through the uplink tunnel The communication method according to claim 1, characterized by the above.
4. For the third step, the second base station uses the terminal context to create a downlink tunnel with the user plane function of the core system, For the fourth step, the user plane function of the core system uses the source IP address of the user data to create a downlink tunnel with the second base station, And a fifth step of transmitting the user data received from the destination device to the second base station through the downlink tunnel The communication method according to claim 1, further characterized by comprising the above steps.
5. During the location registration sequence executed between the terminal and the control plane function of the core system via the first base station, the terminal notifies the control plane function of the core system of a flag indicating whether to execute the transfer of user data based on the first step to the fourth step, For the first step, The terminal transmits a session establishment request to the control plane function of the core system via the first base station, and when the flag is true, the control plane function of the core system returns a session establishment response including the terminal context to the terminal. The communication method according to claim 1, characterized in that.
6. Regarding the second step, the terminal includes the user data in a packet of the terminal-base station inter-functional layer based on RRC (Radio Resource Control), rather than in a packet of the terminal-core system inter-functional layer. The communication method according to claim 1, characterized in that.
7. The terminal is a mobile station, and the first base station and the second base station are fixed stations, or the terminal is a terrestrial station, and the first base station and the second base station are satellite stations. The communication method according to claim 1, characterized in that.
8. A communication system in which a terminal communicates with a core system via a first base station or a second base station, wherein the terminal has a first function of receiving the terminal context of the user plane function from the control plane function of the core system when establishing a connection with the control plane function of the core system via the first base station, and has a second function of disconnecting the radio link with the first base station and then connecting the radio link with the second base station and transmitting user data and the terminal context. The second base station transmits the user data to the user plane function of the core system using the terminal context, and the user plane function of the core system transfers the user data to the destination device. A communication system, characterized in that.