Communication method and apparatus

Abstract

The application provides a communication method and device, and relates to the field of communication, and aims to improve the availability and reliability of time service. The method comprises the following steps: acquiring a first time starting point used by a terminal, and sending indication information to a user plane network element serving the terminal. The indication information indicates the first time starting point, and the first time starting point is used for synchronizing time between the user plane network element and the terminal.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly to a communication method and apparatus. Background Technology

[0002] The 5th generation (5G) mobile communication system (5GS) can act as a bridge to transmit time-sensitive network (TSN) time information to the end station (ES) and provide time synchronization for the ES.

[0003] When TSN time information is transmitted from the 5G system, the 5G system needs to compensate for the transmission delay of the TSN time information within the 5G system, i.e., the residence time, to ensure the accuracy of the TSN time information transmission. When a message used for time synchronization by the TSN network (such as a gPTP message) arrives at the network TSN translator (NW-TT), the NW-TT determines the arrival time of the message as TSi, i.e., the ingress timestamp, and sends TSi along with the time information to the device-side TSN translator (DS-TT). After receiving the time synchronization message, the DS-TT determines the arrival time of the message as TSe, i.e., the egress timestamp, and calculates the residence time of the time information within the 5G network as TSe-TSi.

[0004] However, in practice, this timing method often fails, preventing subsequent business operations from being established normally. Summary of the Invention

[0005] This application provides a communication method and apparatus to improve the availability and reliability of time synchronization.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] Firstly, a communication method is provided, applied to a session management network element, comprising: obtaining a first time start point used by a terminal, and sending indication information to a user plane network element serving the terminal. The indication information indicates the first time start point, which is used by the user plane network element to synchronize time with the terminal.

[0008] Therefore, when the starting point of time used by the terminal and the user plane network element may be different, the session management network element can obtain the starting point of time used by the terminal, such as the first starting point of time, and notify the user plane network element. In this way, the user plane network element can correct the entry timestamp based on the deviation between the starting point of time used by the terminal and the starting point of time used by the user plane network element, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0009] In one possible design, obtaining the first time start point used by the terminal includes: receiving first information from the terminal, the first information indicating one or more time start points used by the terminal, wherein the one or more time start points include the first time start point. In other words, the time start point used by the terminal can be actively reported by the terminal, which reduces signaling interaction and improves communication efficiency compared to instructing the terminal to report it.

[0010] Optionally, receiving first information from the terminal includes: receiving a session request message from the terminal, the session request message requesting the establishment or modification of a session of the terminal, the session request message including the first information, that is, the terminal can reuse the session establishment or modification process to report the starting time of the time used by the terminal, which can reduce process complexity and improve communication efficiency compared to designing a separate reporting process.

[0011] In one possible design, obtaining the first time point used by the terminal includes: obtaining second information from the data storage network element, the second information indicating one or more time points used by the terminal, the one or more time points including the first time point. That is, for terminals without enhancements, the terminal may not actively report its own time point. Therefore, the session management network element can also actively obtain the time point used by the terminal from the data storage network element to achieve backward compatibility.

[0012] Optionally, obtaining the second information from the data storage network element includes: receiving a session request message from the terminal, the session request message being used to request the establishment or modification of a session of the terminal; and obtaining the terminal's subscription from the data storage network element based on the fact that the session request message does not contain information indicating the start time of use of the terminal, the terminal's subscription including the second information. In other words, the session management network element can also reuse the session establishment or modification process to obtain the start time of use of the terminal, which reduces process complexity and improves communication efficiency compared to designing a separate acquisition process.

[0013] In one possible design, the method further includes determining a first time starting point from multiple time starting points.

[0014] Optionally, the method further includes: indicating a first time start point to the terminal.

[0015] It can be seen that if the terminal supports multiple time start points, the session management network element can notify the terminal of the selected time start point so that both the terminal and the user plane network element can use the same time start point for time synchronization, thereby improving the availability and reliability of time synchronization.

[0016] Optionally, instructing the terminal to indicate the first time start point includes sending a session response to the terminal, the response including information indicating the first time start point. In other words, the session management network element can reuse the session flow to notify the terminal of its selected time start point, which reduces process complexity and improves communication efficiency compared to designing a separate notification flow.

[0017] In one possible design, sending instruction information to the user plane network element serving the terminal includes sending the configuration of the terminal's session to the user plane network element. The session configuration includes the instruction information. Similarly, the session management network element can reuse the session process to notify the user plane network element of the start time of the terminal's use. Compared to designing a separate notification process, this reduces process complexity and improves communication efficiency.

[0018] In one possible design, the first time starting point is the time starting point used by the user-side time-sensitive network converter DS-TT of the terminal, or the first time starting point is the time starting point used by the access network node serving the terminal.

[0019] Secondly, a communication method is provided for use in a session management network element, comprising: obtaining a second time start point used by a user plane network element serving a terminal; sending an indication message to the terminal, wherein the indication message indicates the second time start point, and the second time start point is used for synchronizing the time between the terminal and the user plane network element.

[0020] Therefore, when the starting point of time used by the terminal and the user plane network element may be different, the session management network element can obtain the starting point of time used by the user plane network element, such as the second starting point, and notify the terminal. In this way, the terminal can correct the egress timestamp based on the deviation between the starting point of time used by the user plane network element and the starting point of time used by the terminal, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0021] In one possible design, obtaining the second time start point used by the user plane network element serving the terminal includes: obtaining information about the terminal's session, which includes third information indicating the second time start point.

[0022] Optionally, obtaining information about the terminal's session includes: obtaining session information in response to a terminal request to establish or modify a terminal's session.

[0023] Optionally, the session information includes policy and charging control (PCC) rules.

[0024] Optionally, the user plane element is the user plane element selected for the session.

[0025] It should be understood that since the time synchronization process usually reuses sessions to transmit TSN time information, i.e., session-level time synchronization, the session management network element needs to obtain the time start point used by the user plane network element selected for the session from the information of the session and notify the terminal, rather than notifying other user plane network elements of the time start point used, in order to improve the availability and reliability of time synchronization.

[0026] In one possible design, sending indication information to the terminal includes sending a response to the terminal's session, the response including the indication information. In other words, the session management network element can reuse the terminal's session flow to notify the terminal of the start time of the user plane network element's use. Compared to designing a separate notification flow, this reduces process complexity and improves communication efficiency.

[0027] In one possible design, the second time starting point is the time starting point used by the network-side time-sensitive network converter NW-TT of the user plane network element.

[0028] Thirdly, a communication method is provided, applied to a terminal-side device, comprising: receiving indication information and storing a second time start point. The indication information indicates the second time start point used by a user plane network element, the user plane network element serving the terminal, and the time start point used by the terminal being a first time start point, the first time start point being different from the second time start point.

[0029] In one possible design, receiving instruction information includes: receiving instruction information from a session management network element, which serves the terminal.

[0030] Optionally, receiving indication information from the session management network element includes: receiving a response from the session management network element regarding the session when the terminal requests to establish or modify the terminal's session, the response including indication information.

[0031] In one possible design, the method further includes: receiving time information from a user plane network element, and determining the dwell time of the time information based on a time offset, a first timestamp, and a second timestamp. The time information includes a first timestamp indicating the time when the time information arrives at the user plane network element, a time offset being the offset of a first time start point relative to a second time start point, or the offset of the second time start point relative to the first time start point, and a second timestamp indicating the time when the time information arrives at the terminal.

[0032] Optionally, the first timestamp specifically indicates the offset of the time when the time information arrives at the user plane network element relative to the second time starting point.

[0033] Optionally, the second timestamp specifically indicates the offset of the time when the time information arrives at the terminal relative to the first time starting point.

[0034] Optionally, the time offset is ΔT, the first timestamp is TSi, the second timestamp is TSe, and the dwell time is RT; when the offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: RT=TSe-TSi+ΔT; when the offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: RT=TSe-TSi-ΔT.

[0035] Optionally, the time information also includes indication information, which can be indicated to the terminal by user plane network elements through user plane communication.

[0036] It should be understood that the relevant technical effects of the method described in the third aspect can also refer to the relevant introduction of the method described in the second aspect above, and will not be repeated here.

[0037] Fourthly, a communication method is provided, applied to a user plane network element, comprising: receiving indication information and determining a time offset. The indication information indicates a first time starting point used by the terminal, the user plane network element serves the terminal, the time starting point used by the user plane network element is a second time starting point, the first time starting point and the second time starting point are different, and the time offset is the offset of the first time starting point relative to the second time starting point, or the offset of the second time starting point relative to the first time starting point.

[0038] In one possible design, receiving instruction information includes: receiving instruction information from a session management network element, which serves the terminal.

[0039] Optionally, receiving instruction information from the session management network element includes: receiving session configuration sent by the session management network element when the terminal requests to establish or modify the terminal's session, the configuration including instruction information.

[0040] In one possible design, the method further includes: receiving time information from a data network; determining a timestamp based on a time offset and the offset of the time when the time information arrives at the user plane network element relative to a second time starting point; and sending time information containing the timestamp to the terminal. The timestamp indicates the offset of the time when the time information arrives at the user plane network element relative to a first time starting point, where the time offset is either the offset of the first time starting point relative to the second time starting point or the offset of the second time starting point relative to the first time starting point.

[0041] Optionally, the time offset is ΔT, the offset of the time when the time information arrives at the user plane network element relative to the second time starting point is TSi1, and the offset of the time when the time information arrives at the user plane network element relative to the first time starting point is TSi2. When the time offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1+ΔT; when the time offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1-ΔT.

[0042] It should be understood that the relevant technical effects of the method described in the fourth aspect can also refer to the relevant introduction of the method described in the first aspect above, and will not be repeated here.

[0043] Fifthly, a communication method is provided, applied to a session management network element, comprising: obtaining a first time start point used by a terminal, and obtaining a second time start point used by a user plane network element serving the terminal, sending indication information to the terminal and / or to the user plane network element, the indication information indicating a time offset, the time offset being the offset of the first time start point relative to the second time start point, or the offset of the second time start point relative to the first time start point.

[0044] Therefore, when the starting points of time used by the terminal and the user plane network element may differ, the session management network element can obtain the starting points of time used by the terminal and the user plane network element respectively, determine the time offset between the two, and notify the user plane network element and / or the terminal. In this way, the user plane network element can correct the entry timestamp based on the time offset, or the terminal can also correct the exit timestamp based on the time offset, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0045] In one possible design, obtaining the first time starting point used by the terminal includes: receiving first information from the terminal, the first information indicating one or more time starting points used by the terminal, the one or more time starting points including the first time starting point.

[0046] Optionally, receiving first information from the terminal includes: receiving a session request message from the terminal, the session request message requesting the establishment or modification of a session of the terminal, the session request message including the first information.

[0047] In one possible design scheme, obtaining the first time point of terminal usage includes:

[0048] The second information is obtained from the data storage network element. The second information indicates one or more time points used by the terminal, and the one or more time points include the first time point.

[0049] Optionally, obtaining the second information from the data storage network element includes: receiving a session request message from the terminal, and obtaining the terminal's subscription from the data storage network element based on the fact that the session request message does not contain information indicating the start time of use by the terminal. The session request message is used to request the establishment or modification of the terminal's session; the terminal's subscription includes the second information.

[0050] In one possible design, the method further includes determining a first time starting point from multiple time starting points.

[0051] In one possible design, obtaining the second time start point used by the user plane network element serving the terminal includes: obtaining information about the terminal's session, the session information including third information, the third information indicating the second time start point.

[0052] Optionally, obtaining information about the terminal's session includes: obtaining session information in response to a terminal request to establish or modify a terminal's session.

[0053] Optionally, the session information includes policy and charging control (PCC) rules.

[0054] Optionally, the user plane element is the user plane element selected for the session.

[0055] In one possible design, sending indication information to the terminal and / or user plane network element includes: determining whether a first time start point and a second time start point are the same; and if the first time start point and the second time start point are different, sending indication information to the terminal and / or user plane network element. In other words, if the first time start point and the second time start point are the same, the session management network element does not need to send indication information, thereby reducing redundancy and improving communication efficiency.

[0056] In one possible design, sending indication information to the terminal includes sending a response to the terminal's session, the response including the indication information.

[0057] Optionally, the response may also include information indicating the first time start point.

[0058] In one possible design, sending instruction information to the user plane network element includes: sending the user plane network element a session configuration for the terminal, the configuration including the instruction information.

[0059] In one possible design, the first time starting point is the time starting point used by the user-side time-sensitive network converter DS-TT of the terminal, or the first time starting point is the time starting point used by the access network equipment serving the terminal.

[0060] In one possible design, the second time starting point is the time starting point used by the network-side time-sensitive network converter NW-TT of the user plane network element.

[0061] It should be understood that the technical effects of the method described in the fifth aspect can also be referred to the relevant descriptions of the methods described in the first and second aspects above, and will not be repeated here.

[0062] Sixthly, a communication method is provided for an apparatus applied to a terminal side, comprising: receiving indication information and storing a time offset. The indication information indicates the time offset, which is the offset of a first time starting point used by the terminal relative to a second time starting point used by a user plane network element, or the offset of the second time starting point relative to the first time starting point, wherein the user plane network element serves the terminal.

[0063] In one possible design, the method further includes: receiving time information from a user plane network element; determining the dwell time of the time information based on a time offset, a first timestamp, and a second timestamp; the second timestamp indicating the time the time information arrives at the terminal. The time information includes a first timestamp, which indicates the time the time information arrives at the user plane network element.

[0064] Optionally, the first timestamp specifically indicates the offset of the time when the time information arrives at the user plane network element relative to the second time starting point.

[0065] Optionally, the second timestamp specifically indicates the offset of the time when the time information arrives at the terminal relative to the first time starting point.

[0066] Optionally, the time offset is ΔT, the first timestamp is TSi, the second timestamp is TSe, and the dwell time is RT; when the offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: RT=TSe-TSi+ΔT; when the offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: RT=TSe-TSi-ΔT.

[0067] In one possible design, the first time starting point is the time starting point used by the user-side time-sensitive network converter DS-TT of the terminal, or the first time starting point is the time starting point used by the access network node serving the terminal.

[0068] In one possible design, the second time starting point is the time starting point used by the network-side time-sensitive network converter NW-TT of the user plane network element.

[0069] It should be understood that the technical effects of the method described in the sixth aspect can also be referred to the relevant introduction of the method described in the fifth aspect above, and will not be repeated here.

[0070] A seventh aspect provides a communication method applied to a user plane network element, comprising: receiving indication information and storing a time offset. The indication information indicates the time offset, which is the offset of a first time starting point used by the terminal relative to a second time starting point used by the user plane network element, or the offset of the second time starting point relative to the first time starting point, wherein the user plane network element serves the terminal.

[0071] In one possible design, the method further includes: receiving time information from a data network; determining a timestamp based on a time offset and the offset of the time the time information arrives at the user plane network element relative to a second time starting point; and sending time information containing the timestamp to the terminal. The timestamp indicates the offset of the time the time information arrives at the user plane network element relative to a first time starting point.

[0072] Optionally, the time offset is ΔT, the offset of the time when the time information arrives at the user plane network element relative to the second time starting point is TSi1, and the offset of the time when the time information arrives at the user plane network element relative to the first time starting point is TSi2. When the time offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1+ΔT; when the time offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1-ΔT.

[0073] It should be understood that the technical effects of the method described in the seventh aspect can also be referred to the relevant introduction of the method described in the fifth aspect above, and will not be repeated here.

[0074] Eighthly, a communication method is provided, applied to a user plane network element, comprising: obtaining a second time start point and sending indication information to a terminal. The second time start point is the time start point used by the user plane network element, the indication information indicates the second time start point, the user plane network element serves the terminal, and the second time start point is used for time synchronization between the terminal and the user plane network element.

[0075] Therefore, when the starting point of time used by the terminal and the user plane network element may be different, the user plane network element can transmit its own starting point of time to the terminal through the user plane. In this way, the terminal can correct the exit timestamp based on the deviation between the starting point of time used by the user plane network element and the starting point of time used by the terminal, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0076] In one possible design, sending indication information to the terminal includes: receiving time information from the data network, sending time information carrying a timestamp and indication information to the terminal, wherein the timestamp indicates the offset of the time when the time information arrives at the user plane network element relative to the second time starting point.

[0077] Ninthly, a communication apparatus is provided. This communication apparatus is used to execute the communication method described in any implementation of any one of the first to eighth aspects.

[0078] In this application, the communication device described in the ninth aspect can be a terminal device or a network device, or a chip (system) or other component or assembly, or a device containing the terminal device or network device. The aforementioned chip (system) or other component or assembly can all be disposed within the terminal device or network device.

[0079] It should be understood that the communication apparatus described in the ninth aspect includes modules, units, or means that implement the communication method described in any one of the first to eighth aspects. These modules, units, or means can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units for performing the functions involved in the aforementioned communication method.

[0080] A tenth aspect provides a communication device. The communication device includes a processor configured to execute the communication method described in any possible implementation of any of the first to eighth aspects.

[0081] In one possible design, the communication device described in the tenth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the tenth aspect and other communication devices.

[0082] In one possible design, the communication device described in the tenth aspect may further include a memory. This memory may be integrated with the processor or disposed separately. The memory may be used to store computer programs and / or data relating to the communication method described in any of the first to eighth aspects.

[0083] In this application, the communication device described in the tenth aspect can be a terminal device or a network device, or a chip (system) or other component or assembly, or a device containing the terminal device or network device. The aforementioned chip (system) or other component or assembly can all be disposed within the terminal device or network device. For example, when the communication device performs the method described in the first or second aspect, the communication device can be a network device; when the communication device performs the method described in the third aspect, the communication device can be a terminal device.

[0084] Eleventhly, a communication device is provided. The communication device includes: a processor coupled to a memory, the processor being configured to execute a computer program stored in the memory, such that the communication device performs the communication method described in any possible implementation of any of the first to eighth aspects.

[0085] In one possible design, the communication device described in the eleventh aspect may further include a transceiver. This transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the eleventh aspect and other communication devices.

[0086] In this application, the communication device described in the eleventh aspect can be a terminal device or a network device, or a chip (system) or other component or assembly, or a device containing the terminal device or network device. The aforementioned chip (system) or other component or assembly can all be disposed within the terminal device or network device. For example, when the communication device performs the method described in the first or second aspect, the communication device can be a network device; when the communication device performs the method described in the third aspect, the communication device can be a terminal device.

[0087] In a twelfth aspect, a communication device is provided, comprising: a processor and a memory; the memory being used to store a computer program, which, when executed by the processor, causes the communication device to perform the communication method described in any implementation of any one of the first to eighth aspects.

[0088] In one possible design, the communication device described in the twelfth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the twelfth aspect and other communication devices.

[0089] In this application, the communication device described in the twelfth aspect can be a terminal device or a network device, or a chip (system) or other component or assembly, or a device containing the terminal device or network device. The aforementioned chip (system) or other component or assembly can all be disposed within the terminal device or network device. For example, when the communication device performs the method described in the first or second aspect, the communication device can be a network device; when the communication device performs the method described in the third aspect, the communication device can be a terminal device.

[0090] In a thirteenth aspect, a communication device is provided, comprising: a processor; the processor being configured to be coupled to a memory, and after reading a computer program from the memory, to execute a communication method as described in any implementation of any one of the first to eighth aspects.

[0091] In one possible design, the communication device described in aspect thirteen may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in aspect thirteen and other communication devices.

[0092] In this application, the communication device described in aspect thirteen can be a terminal device or a network device, or a chip (system) or other component or assembly, or a device containing the terminal device or network device. The aforementioned chip (system) or other component or assembly can all be disposed within the terminal device or network device. For example, when the communication device performs the method described in aspect one or two above, the communication device can be a network device; when the communication device performs the method described in aspect three above, the communication device can be a terminal device.

[0093] In a fourteenth aspect, a processor is provided. The processor is configured to execute the communication method described in any possible implementation of any of the first to eighth aspects.

[0094] In a fifteenth aspect, a communication system is provided. The communication system includes at least one of the following: a session management network element for performing the method described in the first or second aspect, a terminal-side device for performing the method described in the third aspect, or a user plane network element for performing the method described in the fourth aspect. Alternatively, the communication system includes at least one of the following: a session management network element for performing the method described in the fifth aspect, a terminal-side device for performing the method described in the sixth aspect, or a user plane network element for performing the method described in the seventh aspect. Alternatively, the communication system includes a user plane network element for performing the method described in the eighth aspect.

[0095] In a sixteenth aspect, a computer-readable storage medium is provided, comprising a computer program or instructions that, when executed, cause a communication method as described in any possible implementation of any of the first to eighth aspects above to be performed.

[0096] In a seventeenth aspect, a computer program product is provided, comprising: a computer program or instructions that, when executed, cause the communication method described in any possible implementation of any of the first to eighth aspects above to be performed.

[0097] Furthermore, the technical effects of the aforementioned communication devices and systems can be referenced from the technical effects of the aforementioned communication methods, and will not be elaborated further. Attached Figure Description

[0098] Figure 1 This is a schematic diagram of the 5GS architecture;

[0099] Figure 2 This is a schematic diagram of the TNS architecture;

[0100] Figure 3 This is a schematic diagram illustrating an application scenario for time synchronization.

[0101] Figure 4 This application provides a schematic diagram of the architecture of a communication system.

[0102] Figures 5-12 A flowchart illustrating a communication method provided in an embodiment of this application;

[0103] Figure 13 A schematic diagram of the structure of a communication device provided in this application embodiment. Figure 1 ;

[0104] Figure 14 A schematic diagram of the structure of a communication device provided in this application embodiment. Figure 2 . Detailed Implementation

[0105] The technical solutions of this application embodiment can be applied to various communication systems, such as Wi-Fi wireless network systems, vehicle-to-everything (V2X) communication systems, device-to-device (D2D) communication systems, vehicle-to-everything (V2X) communication systems, fourth-generation (4G) mobile communication systems, such as long-term evolution (LTE) systems, worldwide interoperability for microwave access (WiMAX) communication systems, fifth-generation (5G) mobile communication systems, such as new radio (NR) systems, and future communication systems.

[0106] The technical terms and related technical solutions in this application will be described below with reference to the accompanying drawings.

[0107] 1. Fifth generation (5G) mobile communication system (5G system, 5GS):

[0108] Figure 1 This is a schematic diagram of the 5GS. (For example...) Figure 1 As shown, 5GS includes: access network (AN) and core network (CN), and may also include: terminals.

[0109] A terminal can be a terminal with transceiver capabilities, or it can be a chip or chip system installed in the terminal. This terminal can also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station (MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user apparatus. The terminals in the embodiments of this application may be mobile phones, cellular phones, smartphones, tablets, wireless data cards, personal digital assistants (PDAs), wireless modems, handsets, laptop computers, machine-type communication (MTC) terminals, computers with wireless transceiver capabilities, virtual reality (VR) terminals, augmented reality (AR) terminals, smart home devices (e.g., refrigerators, televisions, air conditioners, electricity meters, etc.), intelligent robots, robotic arms, workshop equipment, wireless terminals in autonomous driving, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, vehicle-mounted terminals, and roadside units with terminal functions. The terminal in this application can also be an onboard module, onboard unit, onboard component, onboard chip, or onboard unit that is built into a vehicle as one or more components or units. The terminal device can also be other devices with terminal functions; for example, it can be a device that functions as a terminal in D2D communication.

[0110] The embodiments of this application do not limit the device form of the terminal. The device used to implement the functions of the terminal device can be the terminal device itself; it can also be a device that supports the terminal device in implementing the functions, such as a chip system. The device can be installed in the terminal device or used in conjunction with the terminal device. In the embodiments of this application, the chip system can be composed of chips or can include chips and other discrete components.

[0111] The aforementioned AN is used to implement access-related functions, providing network access capabilities for authorized users and determining transmission links of different quality levels to transmit user data based on user level, service requirements, etc. The AN forwards control signals and user data between the terminal and the CN. The AN may include access network equipment, also known as radio access network (RAN) equipment.

[0112] The CN (Network Access Provider) is primarily responsible for maintaining the subscription data of the mobile network and providing terminals with functions such as session management, mobility management, policy management, and security authentication. The CN mainly includes all or some of the following functions: UPF (User Member Function), authentication server function (AUSF), access and mobility management function (AMF), session management function (SMF), network slice selection function (NSSF), network exposure function (NEF), network repository function (NRF), policy control function (PCF), unified data management (UDM), unified data repository (UDR), introduction of time-sensitive communication and time synchronization function (TSCTSF), and application function (AF).

[0113] like Figure 1As shown, the UE accesses the 5G network through the RAN device. The UE communicates with the AMF through the N1 interface (N1 for short); the RAN communicates with the AMF through the N2 interface (N2 for short); the RAN communicates with the UPF through the N3 interface (N3 for short); the SMF communicates with the UPF through the N4 interface (N4 for short); and the UPF accesses the data network (DN) through the N6 interface (N6 for short). Furthermore, Figure 1 The control plane functions shown, such as AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR, or AF, interact using service-oriented interfaces. For example, the service-oriented interface provided by AUSF is Nausf; AMF is Namf; SMF is Nsmf; NSSF is Nnssf; NEF is Nnef; NRF is Nnrf; PCF is Npcf; UDM is Nudm; UDR is Nudr; TSCTSF is Ntsctsf; and AF is Naf.

[0114] An access network device can be a device with wireless transceiver capabilities, or it can be a chip or chip system located in the access network (AN) of a communication system to provide access services to terminals. For example, an access network device can be called a radio access network (RAN) device, specifically a future mobile communication system, such as a future access network device, such as a future base station. In future mobile communication systems, access network devices may also have other naming conventions, all of which are covered within the protection scope of the embodiments of this application, and this application does not impose any limitations on them. Alternatively, the access network device may also include 5G, such as a gNB in ​​a new radio (NR) system, or one or a group of antenna panels (including multiple antenna panels) of a 5G base station, or it may be a network node constituting a gNB, a transmission and reception point (TRP) or transmission point (TP), or a transmission measurement function (TMF), such as a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), an RSU with base station functionality, or a wired access gateway, or a 5G core network element, etc. Alternatively, the access network device may also include: an access point (AP) in a wireless fidelity (WiFi) system, a wireless relay node, a wireless backhaul node, various forms of macro base stations, micro base stations (also known as small cells), relay stations, access points, wearable devices, vehicle-mounted equipment, etc.

[0115] In this network, CU and DU can be configured separately or included in the same network element, such as a baseband unit (BBU). RU can be included in radio frequency equipment or radio frequency units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs). It is understood that network equipment can be CU nodes, DU nodes, or a combination of CU and DU nodes. Furthermore, CUs can be classified as network equipment in the access network (RAN) or in the core network (CN); there are no restrictions on this classification.

[0116] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0117] In this embodiment, the form of the network device is not limited. The device used to implement the function of the network device can be the network device itself, or it can be a device that supports the network device in implementing the function, such as a chip system. The device can be installed in the network device or used in conjunction with the network device.

[0118] The User-Defined Processing (UPP) is primarily responsible for user data processing (forwarding, receiving, billing, etc.). For example, a UPF can receive user data from a data network (DN) and forward it to the terminal through access network equipment. Alternatively, a UPF can receive user data from the terminal through access network equipment and forward it to the DN. A DN refers to the operator's network that provides data transmission services to users. Examples include Internet Protocol (IP) multimedia services (IMS) and the Internet. A DN can be an external network of the operator or a network controlled by the operator, used to provide services to terminals. In a Protocol Data Unit (PDU) session, the UPF directly connected to the DN via N6 is also called the Protocol Data Unit Session Anchor (PSA).

[0119] AUSF is primarily used to perform security authentication for terminals.

[0120] AMF is primarily used for mobility management in mobile networks. Examples include user location updates, user network registration, and user handover.

[0121] SMF is primarily used for session management in mobile networks. This includes session establishment, modification, and release. Specific functions include assigning Internet Protocol (IP) addresses to users and selecting a UPF (User-Defined Provider) to handle packet forwarding.

[0122] The PCF primarily supports providing a unified policy framework to control network behavior, delivering policy rules to control-layer network functions, and acquiring user subscription information related to policy decisions. The PCF can provide policies to the AMF and SMF, such as Quality of Service (QoS) policies and slice selection policies.

[0123] NSSF is primarily used to select network slices for terminals.

[0124] NEF is primarily used to support the opening of capabilities and events.

[0125] UDM is primarily used to store user data, such as contract data and authentication / authorization data.

[0126] UDR is primarily used to store structured data, including contract data, policy data, externally exposed structured data, and application-related data.

[0127] The main functions of TSCTSF are to associate time synchronization service requests from NF consumers with AF sessions of PCF; and to detect the availability of 5GS bridge information for Ethernet and IP type PDU sessions reported by PCF.

[0128] AF primarily supports interaction with CN to provide services, such as influencing data routing decisions, policy control functions, or providing third-party services to the network side.

[0129] It is understood that the functions mentioned in the embodiments of this application can also refer to functional network elements or functional entities. For example, UPF can be referred to as UPF network element, AMF can be referred to as AMF network element, SMF can be referred to as SMF network element, PCF can be referred to as PCF network element, and so on, without limitation.

[0130] 2. Clock synchronization:

[0131] The clock synchronization capability of 5G networks is a network function that can be opened to external systems, such as serving as the master clock for the entire system to synchronize the clocks of other devices. Section 5.27.1.8 of Release 17 defines that the clock synchronization capability of 5G networks can be activated and deactivated by the AF (Active Controller).

[0132] Figure 2 This is a schematic diagram of the architecture of a time-sensitive network (TSN), as shown below. Figure 2 As shown, the 5G system acts as a TSN bridge within a TSN network. The time-sensitive network grandmaster (TSN GM) serves as the clock source within the TSN network. The network TSN translator (NW-TT) is the interface on the UPF (Upper Filter Function) side and also the bridge's input interface, responsible for introducing TSN data into the 5G network. Because it receives time synchronization messages from the TSN network, it acts as a slave interface. The NW-TT needs to perform latency and frequency deviation measurements with the TSN bridge. The NW-TT adds an interface timestamp (Tse) to the synchronization messages.

[0133] The device-side TSN translator (DS-TT) is the UE-side interface, i.e., the bridge's outgoing interface, responsible for inputting TSN data into the TSN network. Because it needs to send time synchronization messages to the TSN network, it is the master interface. The DS-TT needs to work with the end station to perform latency and frequency offset measurements. The DS-TT adds an egress timestamp (Tsi) to the synchronization messages received from the UE and then calculates the internal forwarding latency.

[0134] The TSN architecture supports two time synchronization technologies: 5G accessstratum-based time distribution (APT), also known as air interface time synchronization, and gPTP-based time distribution. The 5G network host (5G GM) serves as the NR clock source, typically provided by the Global Positioning System (GPS). The main process of air interface time synchronization involves the base station broadcasting System Information Block (SIB) 9 timing signaling. SIB9 can include information elements such as time information and time information type. The time information indicates a relative time to a specific starting point, and the time information type indicates that starting point. When SIB9 does not include a time information type, the default starting point is the GPS epoch, specifically 1980-01-06 00:00 Coordinated Universal Time (UTC).

[0135] Specific application scenarios for time information transmission in 5G systems include: UEs using air interface time synchronization to synchronize with the 5G master clock. Based on this, the 5G system can act as a bridge to transmit TSN time information to the end station (ES). When TSN time information is transmitted from the 5G system, the 5G system needs to compensate for the transmission delay of the TSN time information within the 5G system, i.e., the residence time, to ensure the accuracy of TSN time information transmission. Specifically, as follows... Figure 3 As shown, when a time synchronization message (e.g., a gPTP message) arrives at the 5G UPF / NW-TT, the NW-TT determines the arrival time of the message as TSi, i.e., the ingress timestamp, and sends TSi along with the time information to the UE / DS-TT. After receiving the time synchronization message, the DS-TT determines the arrival time of the message as TSe, i.e., the egress timestamp, and calculates the dwell time of the time information within the 5G network as TSe-TSi.

[0136] However, the applicant's research revealed that for the two timestamps used to calculate dwell time, such as TSi and TSe, since both DS-TT and NW-TT use the PTP protocol to process gPTP messages, these two timestamps, according to the Institute of Electrical and Electronics Engineers (IEEE) 1588v2 standard, are relative times relative to a certain epoch. The epoch used by the TSN's master clock is typically the PTP epoch, specifically 1970-01-01 00:00 UTC, meaning that TSi in the gPTP message is a relative time relative to the PTP epoch. The UE's time comes from over-the-air time synchronization; in this case, the time indicated by the time information in SIB9 is by default relative to the GPS epoch. Typically, DS-TT and UE are co-located, i.e., in the same device; therefore, the timestamp TSe obtained by DS-TT is usually also obtained from the UE's hardware clock, i.e., also a relative time relative to the GPS epoch. Because the GPS origin and PTP origin differ greatly, such as 1980-01-06 and 1970-01-01, the calculation of dwell time will also produce this difference, that is, an error of more than 10 years. This leads to errors in the calculation of dwell time, incorrect transmission of time information, and subsequent services cannot be established correctly.

[0137] To address the aforementioned technical problems, this application proposes the following technical solutions. The technical solutions in this application will now be described in conjunction with the accompanying drawings.

[0138] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches are also possible.

[0139] Furthermore, in the embodiments of this application, words such as "exemplarily" and "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as an "example" in this application should not be construed as being better or more advantageous than other embodiments or designs. Rather, the use of the word "example" is intended to present the concept in a specific manner.

[0140] First, in this application, "for indicating" can include both direct and indirect indication. When describing "information" for indicating A, it can include whether the information directly indicates A or indirectly indicates A, but does not necessarily mean that the information carries A.

[0141] The information indicated by a given piece of information is called the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as, but not limited to, directly indicating the information to be indicated, such as the information to be indicated itself or its index. It can also be indirectly indicated by indicating other information, where there is a relationship between the other information and the information to be indicated. It can also indicate only a part of the information to be indicated, while the other parts are known or pre-agreed upon. For example, the indication of specific information can be achieved by using a pre-agreed (e.g., protocol-defined) arrangement of various pieces of information, thereby reducing the indication overhead to some extent. At the same time, common parts of various pieces of information can be identified and indicated uniformly to reduce the indication overhead caused by individually indicating the same information.

[0142] Furthermore, the specific indication method can also be any existing indication method, such as, but not limited to, the above-mentioned indication methods and their various combinations. Specific details of various indication methods can be found in existing technologies, and will not be repeated here. As described above, for example, when multiple pieces of information of the same type need to be indicated, the indication methods for different pieces of information may differ. In the specific implementation process, the required indication method can be selected according to specific needs. This application embodiment does not limit the selected indication method; therefore, the indication methods involved in this application embodiment should be understood to cover various methods that enable the party to be indicated to obtain the information to be indicated.

[0143] Second, in the embodiments shown below, the first, second, and various numerical designations are merely distinctions for descriptive convenience and are not intended to limit the scope of the embodiments of this application. For example, to distinguish different indication information.

[0144] Third, "pre-set," "predefined," or "pre-configured" can be achieved by pre-saving corresponding codes, tables, or other means of indicating relevant information in the device (e.g., including terminal devices and network devices), or by pre-defining them in a protocol. This application does not limit the specific implementation method. "Saving" can refer to saving in one or more memories. These memories can be separate installations or integrated into the encoder, decoder, processor, or communication device. Alternatively, some memories can be separately installed, while others are integrated into the decoder, processor, or communication device. The type of memory can be any form of storage medium, and this application does not specifically limit this.

[0145] Fourth, the “protocol” involved in the embodiments of this application may refer to standard protocols in the field of communication, such as 3GPP’s LTE protocols (such as technical specification (TS) 36, i.e., the TS36 series of technical specifications), NR protocols (such as the TS38 series of technical specifications), and related protocols applied to future communication systems. This application does not limit this.

[0146] The network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0147] To facilitate understanding of the embodiments of this application, let's first take... Figure 4 The communication system illustrated herein is used as an example to illustrate a communication system applicable to embodiments of this application. For example, Figure 4 This is a schematic diagram of the architecture of a communication system to which the method provided in the embodiments of this application applies.

[0148] Figure 4 A schematic diagram of the communication system architecture, such as Figure 4 As shown, the communication system mainly includes at least one of the following: a terminal, a session management network element, or a user plane network element.

[0149] The form factor of the terminal can be referred to in the relevant introduction of 5GS above. The terminal can be co-located with DS-TT, that is, the terminal can include DS-TT, and the functions involved in the terminal in this embodiment can also be understood as being implemented by DS-TT. In addition, DS-TT can also be referred to in the relevant introduction of TSN architecture above, and will not be repeated here.

[0150] Session management network elements can serve terminals, such as selecting network elements for terminal sessions. The session management network element can be the aforementioned SMF (Session Management Element), as detailed in the 5GS introduction above. Alternatively, in future communication systems, the SMF can be replaced with any network element capable of session management without specific limitations.

[0151] User plane network elements can serve terminals, such as network elements selected for terminal sessions. User plane network elements can be the aforementioned UPF (User Plane Function), as detailed in the 5GS description above. Alternatively, in future communication systems, the UPF can be replaced with any network element capable of implementing user plane functions, without specific limitations. User plane network elements can be co-located with NW-TT (Network-to-Wireless Telephony), meaning a user plane network element can include an NW-TT. The functions involved in the user plane network elements in this embodiment can also be understood as being implemented by the NW-TT. Furthermore, the NW-TT can also be referenced in the TSN architecture description above, which will not be repeated here.

[0152] In this communication system, the time starting points used by the terminal and the user plane network element may differ. For example, the terminal might use the GPS starting point, while the user plane network element might use the PTP starting point. Therefore, in one possible approach, the session management network element can obtain the time starting point used by the terminal and notify the user plane network element, or it can obtain the time starting point used by the user plane network element and notify the terminal. This allows either the user plane network element or the terminal to determine the deviation between the other party's time starting point and its own, i.e., the time offset. This time offset can then be used to correct the timestamp used for calculating dwell time in the context of time synchronization, thereby improving the availability and reliability of time synchronization. Alternatively, in another possible approach, the session management network element can obtain both the time starting point used by the terminal and the time starting point used by the user plane network element to determine the time offset between them. The session management network element can then notify the terminal and / or the user plane network element of the time offset. In this way, the user plane network element or the terminal can use the time offset to correct the timestamp used for calculating dwell time in the context of time synchronization, also improving the availability and reliability of time synchronization. Alternatively, in another possible approach, the user plane network element can also transmit its own time start point to the terminal through the user plane, so that the terminal can determine the time offset between the time start point used by the user plane network element and its own time start point. In the case of time synchronization, the time offset can be used to correct the timestamp used to calculate the dwell time, thereby improving the availability and reliability of time synchronization.

[0153] It should also be understood that Figure 4 This is a simplified diagram for ease of understanding only. Other network elements / devices / terminals may also be included in this communication system. Figure 4The details are not shown in the diagram. Furthermore, the solutions described in this application can also be applied to other communication systems, and the corresponding names can be replaced with the names of the corresponding functions in other communication systems, without specific limitations.

[0154] The following will combine Figures 5-12 The interaction process between network elements in the above-mentioned communication system is specifically described through method embodiments. This communication method can be applied to the interaction between various network elements / devices in the above-mentioned communication system, which will be described in detail below.

[0155] Figure 5 This is a flowchart illustrating the communication method. Figure 1 This communication method mainly involves the interaction between the session management network element and the user plane network element in the above communication system, and mainly involves the session management network element notifying the user plane network element of the start time of terminal use.

[0156] like Figure 5 As shown, the flow of this communication method is as follows:

[0157] S501, the session management network element obtains the first time point of terminal usage.

[0158] The first time starting point can be one of one or more time starting points used by the terminal. At least some of these time starting points can be different. For example, multiple time starting points can include the 5G GM starting point (5G GM epoch), GPS starting point, PTP starting point, DN starting point, or a newly defined time starting point in the future, without specific restrictions. Among them, the 5G GM starting point and the GPS starting point can be the same or different, such as the 5G GM starting point being a PTP starting point. The DN starting point and the PTP starting point are usually the same.

[0159] It should be understood that since the terminal and DS-TT are co-located, one or more time starting points used by the terminal can also be understood as one or more time starting points used by the terminal's DS-TT; that is, the first time starting point can also be the time starting point used by the terminal's DS-TT. Alternatively, since the terminal is usually time-synchronized by the access network node (such as RAN) serving the terminal, the time starting points used by the terminal and that access network node may also be the same. Therefore, one or more time starting points used by the terminal can also be understood as one or more time starting points used by that access network node; that is, the first time starting point can also be the time starting point used by that access network node.

[0160] The session management network element can obtain the first time starting point from the terminal or the network side. The following describes two scenarios.

[0161] Scenario 1:

[0162] The session management network element can receive the first information from the terminal.

[0163] The first information may indicate one or more time points used by the terminal, including the first time point.

[0164] For example, the first information can indicate the type of one or more time starting points, such as GPS starting point / 5G GM starting point, which means that the time starting point used by the terminal is GPS starting point / 5G GM starting point, or PTP starting point / DN starting point, which means that the time starting point used by the terminal is PTP starting point / DN starting point, or PTP starting point / DN starting point + GPS starting point / 5G GM starting point, which means that the time starting point used by the terminal can be either GPS starting point / 5G GM starting point or PTP starting point / DN starting point. For example, the first piece of information can also include the specific time of the starting point, such as 1980-01-06 00:00UTC, which indicates that the starting point of the time used by the terminal is the GPS starting point / 5G GM starting point, or 1970-01-01 00:00UTC, which indicates that the starting point of the time used by the terminal is the PTP starting point / DN starting point, or 1970-01-01 00:00UTC+1980-01-06 00:00UTC, which indicates that the starting point of the time used by the terminal can be either the GPS starting point / 5G GM starting point or the PTP starting point / DN starting point.

[0165] In one possible implementation, the session management network element receives a session request message from the terminal.

[0166] The session request message requests the establishment or modification of a terminal's session. Specifically, it can be a session establishment / modification request message, or a message to be defined in the future; no specific restrictions apply. The session request message includes the first piece of information mentioned above, namely that the terminal can reuse the session establishment or modification process to report the starting point of the time used by the terminal. Compared to designing a separate reporting process, this reduces process complexity and improves communication efficiency.

[0167] For example, when a terminal has latency-sensitive service requirements, these requirements may need to be synchronized to ensure latency accuracy. If the terminal's non-access stratum (NAS) receives port management information container (PMIC) information from the DS-TT network, indicating that the DS-TT has a service requirement with a specific DN (such as a TSN DN), the terminal, when requesting to establish a session for that service, includes the first piece of information in the session request message and then sends the session request message to the network to proactively report one or more time points used by the terminal. Furthermore, the session request message can also include service information, such as information indicating latency-sensitive service requirements. This session request message can be sent directly by the terminal to the session management network element through the access network equipment, or forwarded to the session management network element by an intermediate network element, without specific restrictions.

[0168] Therefore, the session management network element can obtain the first information from the session request message. For example, the session management network element can, by default, detect whether the session request message carries information indicating the start time of terminal use, thereby obtaining the first information. Alternatively, the session management network element can also trigger the detection of whether the session request message carries information indicating the start time of terminal use based on the service information in the session request message indicating latency-sensitive service requirements, thereby obtaining the first information. In other words, for other service requirements, the session management network element may not need to detect the information indicating the start time of terminal use, thus reducing the overhead of the session management network element.

[0169] It should be understood that the above example is based on latency-sensitive business requirements, but is not intended as a limitation. For example, the terminal may also carry the first information in the session request message by default.

[0170] As can be seen, in scenario 1, the starting point of the time used by the terminal can be actively reported by the terminal. Compared to instructing the terminal to report, this reduces signaling interaction and improves communication efficiency. Of course, the session management network element can also instruct the terminal to report one or more starting points of the time used by the terminal; the specific implementation is not limited.

[0171] Scenario 2:

[0172] Session management network elements can obtain secondary information from data storage network elements.

[0173] The second information can indicate one or more time starting points used by the terminal, including the first time starting point. The specific implementation is similar to the first information mentioned above, and can be understood by referring to it. It will not be repeated here.

[0174] In one possible implementation, the session management network element can receive a session request message from a terminal, which requests the establishment or modification of the terminal's session. Unlike case 1, since the terminal is not enhanced—that is, when the terminal needs to establish a session due to latency-sensitive service requirements—the terminal may not know that it needs to include information indicating the start time of use in the corresponding session request message; that is, the session request message does not carry information indicating the start time of use. Therefore, the session management network element can obtain the terminal's subscription from the data storage network element based on the absence of information indicating the start time of use in the session request message. The data storage network element can be a UDM or a newly defined network element in the future, without specific limitations. The terminal's subscription may include second information. For example, the session management network element can send a subscription data request message to the data storage network element, which requests the acquisition of the terminal's subscription, such as including the terminal's identifier. Thus, the data storage network element can obtain the terminal's subscription based on the terminal's identifier and return a subscription data response message to the session management network element, which contains the terminal's subscription. In this way, the session management network element can obtain the second information from the terminal's subscription.

[0175] It should be understood that the above-mentioned provision of terminal subscription by the data storage network element to the session management network element is only an example and is not intended to be a limitation. For example, the subscription data request message may also include an indication of the request start time. The data storage network element can obtain the second information from the terminal's subscription according to the indication and then send the second information directly to the session management network element.

[0176] As can be seen, in scenario 2, the session management network element can also reuse the session flow to obtain the starting point of the time used by the terminal. Compared with designing a separate acquisition flow, this can reduce the complexity of the flow and improve communication efficiency. In addition, for terminals without enhancements, the terminal may not actively report its own starting point of time. In this case, the session management network element can actively obtain the starting point of time used by the terminal from the data storage network element to achieve backward compatibility.

[0177] It should also be understood that the above scenarios 1-2 are examples of the session process, but are not intended as limitations. For example, the terminal can also report the starting point of the time used by the terminal to the access and mobility management network element, such as AMF, or a newly defined network element in the future, such as the NAS management function (NM) in the distributed subnet. These network elements will then provide the starting point of the time used by the terminal to the session management network element.

[0178] If the terminal uses one or more time points, i.e., the first time point, the session management network element can directly determine this time point as the first time point. Alternatively, if the terminal uses one or more time points, the session management network element can determine the first time point from the multiple time points, such as by randomly selecting a time point or selecting the time point closest to the current time, i.e., the first time point.

[0179] In S502, the session management network element sends an instruction message to the user plane network element. Correspondingly, the user plane network element receives the instruction message.

[0180] For S502, the indication information can be denoted as indication information #1. Indication information #1 can be used to indicate the first time start point for the user plane network element and the terminal to synchronize time. For example, indication information #1 can indicate the type of the first time start point, such as GPS start point / 5G GM start point, or it can also include the specific time of the first time start point, such as 1980-01-06 00:00UTC.

[0181] The session management network element can send session configurations for a terminal to the user plane network element. Correspondingly, when a terminal requests to establish or modify a session, the user plane network element can receive the session configuration sent by the session management network element. This session configuration may include indication information #1. For example, the session management network element can select a user plane network element suitable for the terminal's session, such as a user plane network element co-located with NW-TT, or a user plane network element that supports NW-TT. Thus, when establishing an N4 session with this user plane network element, the session management network element can send indication information #1 to the user plane network element through the N4 session, encapsulating this indication information #1 into the session configuration. The N4 session is then sent to the user plane network element, and the user plane network element can obtain the indication information #1 through the N4 session.

[0182] As can be seen, in S502, the session management network element can also reuse the session flow to notify the user plane network element of the starting time of terminal usage. Compared with designing a separate notification flow, this reduces process complexity and improves communication efficiency. Of course, the session management network element can also send the indication information #1 separately to the user plane network element to achieve decoupling from the existing session flow, making information transmission more flexible.

[0183] S503, User plane network element determines time offset.

[0184] The time offset can be the offset of the first time starting point relative to the second time starting point, i.e., the second time starting point minus the first time starting point, or the offset of the second time starting point relative to the first time starting point, i.e., the first time starting point minus the second time starting point. The second time starting point is the time starting point used by the user plane network element. For example, the second time starting point can be the PTP starting point, or the DN starting point, or it could be a newly defined time starting point in the future. Since the user plane network element is co-located with the NW-TT, the second time starting point can also be called the time starting point used by the user plane network element's NW-TT.

[0185] Typically, the first time starting point and the second time starting point are different.

[0186] User plane network elements can also receive time information from DN, denoted as time information #1.

[0187] The DN can be a TSN DN or any other possible type of DN, without specific restrictions. Time information #1 can be TSN time information and can be carried in the gPTP message, meaning the TSN DN provides time synchronization for the ES through the TSN time information. In this case, the user plane network element can correct the arrival time of time information #1 according to the time offset to achieve time synchronization with the terminal.

[0188] For example, a user plane network element can determine the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point. Then, the user plane network element can determine a timestamp (or entry timestamp) based on the time offset and the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point. The entry timestamp can indicate the time when time information #1 arrives at the user plane network element, specifically indicating the offset of the time when time information #1 arrives at the user plane network element relative to the first time starting point. For example, if the time offset is ΔT, the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point is TSi1, and the offset of the time when time information #1 arrives at the user plane network element relative to the first time starting point is TSi2; when the time offset is the offset of the first time starting point relative to the second time starting point, the entry timestamp satisfies the following relationship: TSi2 = TSi1 + ΔT; when the time offset is the offset of the second time starting point relative to the second time starting point, the entry timestamp satisfies the following relationship: TSi2 = TSi1 - ΔT.

[0189] It should be understood that user plane network elements do not need to determine the time offset separately, but can determine the overall entry timestamp upon receiving time information #1. For example, if the first time start point is denoted as T1 and the second time start point is denoted as T2, the entry timestamp satisfies the following relationship: TSi2 = TSi1 + T1 - T2.

[0190] The user plane network element can also send time information #1, which includes the aforementioned entry timestamp, to the terminal.

[0191] For example, the user plane network element can reuse the session established or modified by the aforementioned session management network element for the terminal, encapsulate the time information #1 into the user plane information / message, and then transmit the information / message to the terminal through the session, so that the terminal can obtain the time information #1 and calculate the dwell time, thereby enabling accurate time synchronization for ES in the future.

[0192] It should be understood that the user plane network element can send time information #1 containing the above-mentioned entry timestamp to the terminal. This can be understood as the user plane network element sending a correction field to the terminal. That is, time information #1 can be replaced by a correction field, or any other possible name. The correction field is used by the terminal to calculate the dwell time. For example, the correction field can include TSi2, or the correction field can also include TSi1 and ΔT.

[0193] It should also be understood that user plane network elements can determine the time offset by default, or user plane network elements can determine the time offset if the first time start point and the second time start point are different. If the first time start point and the second time start point are the same, then user plane network elements can not determine the time offset and can perform time synchronization using existing technology, so as to reduce the processing overhead of user plane network elements.

[0194] In summary, when the starting points of time used by the terminal and the user plane network element may differ, the session management network element can obtain the starting point of time used by the terminal, such as the first starting point of time, and notify the user plane network element. In this way, the user plane network element can correct the entry timestamp based on the deviation between the starting point of time used by the terminal and the starting point of time used by the user plane network element, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0195] Optionally, in conjunction with the above S501-S503, the method further includes:

[0196] S504, the session management network element indicates the first time start point to the terminal.

[0197] When a terminal uses multiple time points, the session management network element can notify the terminal of the time point selected from these multiple time points, so that both the terminal and the user plane network element can use the same time point for time synchronization, thereby improving the availability and reliability of time synchronization.

[0198] For example, the session management network element can send a response to the terminal regarding the session. This response could be a session response message, such as a session establishment response message or a session modification response message, to indicate whether the session establishment / modification of the terminal was successful or failed. The response can include indication information, such as indication information #2. Indication information #2 can indicate the type of the first time start point, or it can also contain the specific time of the first time start point. In other words, the session management network element can still reuse the session flow to notify the terminal of its selected time start point. Compared to designing a separate notification flow, this reduces process complexity and improves communication efficiency. Of course, the session management network element can also send indication information #2 to the terminal separately to decouple it from the session flow, allowing for more flexible information transmission.

[0199] The above combination Figure 5 The overall process of this communication method has been introduced. The following section will combine... Figure 6 This section describes the specific process of this communication method in some example application scenarios.

[0200] Figure 6 Flowchart of the communication method provided in the embodiments of this application Figure 2 . Figure 6 The process shown mainly involves the interaction between UE / DS-TT (as the terminal mentioned above), SMF (as the session management network element mentioned above), UDM (as the data storage network element mentioned above), and UPF / NW-TT (as the user plane network element mentioned above).

[0201] Specifically, such as Figure 6 As shown, the flow of this communication method is as follows:

[0202] S600, the UE receives the PMIC information from DS-TT.

[0203] S601, the UE sends a session establishment request message to the SMF.

[0204] The Session Establishment Request message can be used to request the establishment of a session for the UE.

[0205] The session establishment request message may include first information, namely, one or more time start points indicating the UE's usage. For details, please refer to the relevant description of Case 1 above, which will not be repeated here. Furthermore, in S600-S601, the UE can determine from the PMIC information that the DS-TT has a communication requirement with the TSN DN, and therefore can trigger session establishment, i.e., execute S601. For details, please refer to the relevant description of S501 above, which will not be repeated here.

[0206] S602, SMF obtains the UE's contract from UDM.

[0207] The UE's subscription may include a second piece of information, namely one or more time start points indicating the UE's use.

[0208] It should be understood that S602 is optional. If the session establishment request message of S601 does not carry the first information, SMF can execute S602. For details, please refer to the relevant introduction of situation 2 above, which will not be repeated here.

[0209] S603, SMF selects the first time starting point.

[0210] SMF can select the first time start point from one or more time start points used by the UE.

[0211] S604, SMF sends N4 message to UPF / NW-TT.

[0212] The N4 message may contain indication information #1 to indicate the first time start.

[0213] It should be understood that the specific details of S603-S604 can also be found in the relevant introduction of S502 above, and will not be repeated here.

[0214] S605, SMF sends N1 SM (N1 Session management) message to UE.

[0215] The N1 SM message can be understood as a response to the session, such as indicating whether the UE's session establishment was successful or failed.

[0216] Optionally, if the UE uses multiple time start points, the N1 SM message may also include indication information #2. For details, please refer to the relevant introduction of S504 above, which will not be repeated here.

[0217] S606, UPF / NW-TT receives gTPT messages from TSN DN.

[0218] gTPT messages can include time information #1.

[0219] S607, UPF / NW-TT determines the entry timestamp.

[0220] The entry timestamp can be denoted as TSi2, satisfying TSi2=TSi1+ΔT, or TSi2=TSi1-ΔT. TSi1 is the offset of the time when time information #1 arrives at UPF / NW-TT relative to the second time starting point used by UPF / NW-TT, and ΔT is the time offset between the first time starting point and the second time starting point. For details, please refer to the relevant introduction in S503 above, which will not be repeated here.

[0221] S608, UPF / NW-TT sends downlink data to UE / DS-TT.

[0222] The downlink data carries time information #1, which includes the aforementioned entry timestamp.

[0223] Downlink data can be carried in the UE's session, that is, UPF / NW-TT can transmit time information #1 to UE / DS-TT through the session established / modified for the UE as described above.

[0224] S609, UE / DS-TT determines the dwell time.

[0225] The length of stay is TSe-TSi2.

[0226] TSe is the offset of the time when time information #1 arrives at UE / DS-TT relative to the first time starting point.

[0227] Figure 7 This is a flowchart illustrating the communication method. Figure 3 This communication method mainly involves the interaction between the session management network element and the terminal in the above-mentioned communication system, and mainly involves the session management network element notifying the terminal of the start time of use of the user plane network element.

[0228] like Figure 7 As shown, the flow of this communication method is as follows:

[0229] S701, the session management network element obtains the second time starting point for the use of the user plane network element.

[0230] The second time starting point can be referred to in the relevant introduction in S503 above, and will not be repeated here.

[0231] The session management network element can obtain information about the terminal's session, which may include third-party information.

[0232] The third information can be used to indicate the second time start point. For example, the third information can indicate the type of the second time start point, such as PTP start point / DN start point, or the third information can also include the specific time of the second time start point, such as 1970-01-01 00:00UTC.

[0233] The session information can be policy and charging control (PCC) rules, or any other possible session information, without specific limitations. For example, in response to a terminal requesting to establish or modify a terminal's session, the session management network element can obtain session information. Taking PCC rules as an example, the session management network element can receive a session establishment request message or a session modification request message from a terminal, indicating that the terminal requests to establish or modify its session. In response, the session management network element can obtain the PCC rules from the policy control network element (such as the PCF or any other possible network element).

[0234] It should be understood that since the session information is usually provided by the application function to the policy control network element, and the application function usually belongs to a third party, such as the DN, the second time start indicated by the third information contained in the session information is usually the second time start used by the third party, such as the time start used by the DN. Since the time start used by the user plane network element is usually the same as the time start used by the DN, the second time start indicated by the third information can also be understood as the time start used by the user plane network element.

[0235] Therefore, the session management network element can obtain the second time starting point from the session information.

[0236] It should also be understood that in S701, since the time synchronization process usually uses sessions to transmit TSN time information, i.e., session-level time synchronization, the session management network element needs to obtain the time start point used by the user plane network element selected for the session from the information of the session and notify the terminal, rather than notifying other user plane network elements of the time start point used, in order to improve the availability and reliability of time synchronization.

[0237] In S702, the session management network element sends an instruction message to the terminal. The terminal then receives the instruction message.

[0238] For S702, the indication information can be denoted as indication information #3. This indication information #3 can be used to indicate the second time start point for the terminal to synchronize its time with the user plane network element. For example, indication information #3 can indicate the type of the second time start point, or it can also include the specific time of the second time start point. For details, please refer to the relevant introduction above, which will not be repeated here.

[0239] During the process of establishing / modifying a terminal's session, the session management network element can send a response to the terminal regarding the session. This response can be a session response message, such as a session establishment response message or a session modification response message, to indicate whether the session establishment / modification was successful or failed. This response may include indication information #3. Correspondingly, the terminal can receive indication information #3 from the session management network element, such as when the terminal requests to establish or modify its session, in which case the terminal receives the aforementioned response returned by the session management network element. In other words, the session management network element can reuse the terminal's session flow to notify the terminal of the start time of use of the user plane network element, reducing process complexity and improving communication efficiency compared to designing a separate notification process. Of course, the session management network element can also send indication information #3 to the terminal separately to decouple it from the session flow, allowing for more flexible information transmission.

[0240] S703, the terminal saves the second time start point.

[0241] The terminal can also determine the time offset.

[0242] The time offset can be the offset of the first time starting point relative to the second time starting point, or the offset of the second time starting point relative to the first time starting point. The terminal uses the first time starting point, as detailed in the S501 description above, which will not be repeated here. Typically, the first and second time starting points are different.

[0243] It should be understood that the terminal can determine the time offset by default, or the terminal can determine the time offset if the first time start point and the second time start point are different. If the first time start point and the second time start point are the same, the terminal can not determine the time offset and can use the existing technology to perform time synchronization, so as to reduce the processing overhead of the terminal.

[0244] The terminal can also receive time information from user plane network elements, such as time information #2.

[0245] Time information #2 may include a first timestamp, which can be understood as an entry timestamp. The first timestamp indicates the time when time information #2 arrives at the user plane network element, specifically indicating the offset of the time when time information #2 arrives at the user plane network element relative to the second time starting point. In other words, when the user plane network element receives time information #2 from the DN, it can determine the first timestamp and encapsulate it into time information #2, and then send time information #2 to the terminal via the user plane.

[0246] The terminal can determine the dwell time of time information #2 based on the time offset, the first timestamp, and the second timestamp.

[0247] The second timestamp can be understood as the exit timestamp. It indicates the time when time information #2 arrives at the terminal, specifically the offset of its arrival time relative to the first time starting point. Based on this, the time offset is ΔT, the first timestamp is TSi, the second timestamp is TSe, and the dwell time is RT. When the offset is the offset of the first time starting point relative to the second time starting point, the dwell time satisfies the following relationship: RT = TSe - TSi + ΔT. When the offset is the offset of the second time starting point relative to the third time starting point, the dwell time satisfies the following relationship: RT = TSe - TSi - ΔT. Therefore, the terminal can use the dwell time to further synchronize the ES time.

[0248] It should be understood that the terminal may also determine the exit timestamp as a whole without separately determining the time offset, upon receiving time information #2. For example, the first time start point is denoted as T1, the second time start point is denoted as T2, and the dwell time satisfies the following relationship: RT = TSe - TSi + T1 - T2.

[0249] In summary, when the starting points of time used by the terminal and the user plane network element may differ, the session management network element can obtain the starting point of time used by the user plane network element, such as a second starting point, and notify the terminal. In this way, the terminal can correct the egress timestamp based on the deviation between the starting point of time used by the user plane network element and the starting point of time used by the terminal, thereby achieving time synchronization between the user plane network element and the terminal, which can improve the availability and reliability of time synchronization.

[0250] The above combination Figure 7 The overall process of this communication method has been introduced. The following section will combine... Figure 8 This section describes the specific process of this communication method in some example application scenarios.

[0251] Figure 8 Flowchart of the communication method provided in the embodiments of this application Figure 4 . Figure 8 The process shown mainly involves the interaction between UE / DS-TT (as the terminal mentioned above), SMF (as the session management network element mentioned above), PCF (as the policy control network element mentioned above), and UPF / NW-TT (as the user plane network element mentioned above).

[0252] Specifically, such as Figure 8 As shown, the flow of this communication method is as follows:

[0253] S800, the UE receives the PMIC information from DS-TT.

[0254] S801, the UE sends a session establishment request message to the SMF.

[0255] The Session Establishment Request message can be used to request the establishment of a session for the UE.

[0256] In S800-S801, the UE can determine that the DS-TT has a communication requirement with the TSN DN based on the PMIC information, and thus can trigger the establishment of a session, i.e., execute S801.

[0257] S802, SMF obtains the PCC rules for the session from PCF.

[0258] PCC rules can include third information, namely, the time starting point indicating the DN's use, i.e., the second time starting point.

[0259] It should be understood that the relevant introduction of S701 can also be referred to for S800-S802, and will not be repeated here.

[0260] S803, SMF sends N1 SM message to UE.

[0261] The N1 SM message can be understood as a response to the session, such as indicating whether the UE's session establishment was successful or failed.

[0262] The N1 SM message also includes indication information #3 to indicate the second time start point. For details, please refer to the relevant introductions of S702-S703 above, which will not be repeated here.

[0263] S804, UPF / NW-TT receives gTPT messages from TSN DN.

[0264] gTPT messages can include time information #2.

[0265] S805, UPF / NW-TT determines the first timestamp.

[0266] For the first timestamp, please refer to the relevant introduction in S703 above, which will not be repeated here.

[0267] UPF / NW-TT can encapsulate the first timestamp into time information #2.

[0268] S806, UPF / NW-TT sends downlink data to UE / DS-TT.

[0269] The downlink data carries time information #2, which includes the aforementioned first timestamp.

[0270] Downlink data can be carried in the UE's session, that is, UPF / NW-TT can transmit time information #2 to UE / DS-TT through the session established / modified for the UE as described above.

[0271] S807, UE / DS-TT determines dwell time.

[0272] The dwell time is TSe-TSi+ΔT or TSe-TSi-ΔT. For details, please refer to the relevant introduction in S703 above, which will not be repeated here.

[0273] It should be understood that the above Figures 5-8 The methods shown are merely examples and are not intended to be limiting. For instance, the session management network element can pre-configure or pre-define other time starting points, such as a third time point. This third time point differs from the first and second time points and could be a newly defined time starting point in the future. The session management network element can send the third time point to both the terminal and the user plane network element. In this way, the user plane network element can determine the entry timestamp based on the offset between the third time point and the second time point. Similarly, the terminal can determine the exit timestamp based on the offset between the third time point and the first time point, and further determine the dwell time, thereby completing time synchronization.

[0274] Figure 9This is a flowchart illustrating the communication method. Figure 5 The communication method mainly involves the interaction between the session management network element, the terminal, and the user plane network element in the above-mentioned communication system. It mainly involves the session management network element determining the time offset between the time start point used by the user plane network element and the time start point used by the terminal, and notifying the terminal and / or the user plane network element of the time offset.

[0275] like Figure 9 As shown, the flow of this communication method is as follows:

[0276] S901, the session management network element obtains the first time starting point for terminal use, and the second time starting point for user plane network element use.

[0277] The session management network element can receive first information from the terminal, which may indicate one or more time start points used by the terminal, including the first time start point. Specifically, the session management network element can receive a session request message from the terminal, requesting the establishment or modification of the terminal's session. The session request message may include the first information, as detailed in the relevant description of situation 1 above, and will not be repeated here. Alternatively, the session management network element can obtain second information from the data storage network element, which indicates one or more time start points used by the terminal. Specifically, the session management network element can receive a session request message from the terminal, and if the session request message does not contain information indicating the time start point used by the terminal, it can obtain the terminal's subscription from the data storage network element. The terminal's subscription may include the second information, as detailed in the relevant description of situation 2 above, and will not be repeated here.

[0278] The session management network element can determine the first time starting point from multiple time starting points. For details, please refer to S502 above, which will not be repeated here.

[0279] The session management network element obtains session information of the terminal. The session information can be PCC rules and includes third-party information, which can indicate a second time start point. For example, the session management network element can respond to a terminal request to establish or modify a terminal's session and obtain session information. For details, please refer to the relevant introduction of S701 above, which will not be repeated here.

[0280] S902, the session management network element sends indication information to the terminal and / or to the user plane network element. Correspondingly, the terminal and / or the user plane network element receives the indication information.

[0281] For S902, the indication information can be denoted as indication information #4. Indication information #4 can be used to indicate the time offset, such as including the value of this time offset. This time offset is the offset of the first time start point relative to the second time start point, such as the second time start point minus the first time start point, or the offset of the second time start point relative to the first time start point, such as the first time start point minus the second time start point. Specifically, it is determined by the session management network element based on the first and second time start points obtained in S901.

[0282] 1) Sending instruction information #4 from the session management network element to the user plane network element:

[0283] The session management network element can send the session configuration for the terminal to the user plane network element. Correspondingly, when the terminal requests to establish or modify the terminal's session, the user plane network element can receive the session configuration sent by the session management network element. The session configuration may include indication information #4. For details, please refer to the relevant introduction of S502 above, which will not be repeated here.

[0284] 2) Send instruction information #4 to the terminal from the session management network element:

[0285] During the process of establishing / modifying a terminal's session, the session management network element can send a response to the terminal regarding the session. This response can be a session response message, indicating whether the session establishment / modification was successful or failed. The response may include indication information #4. Correspondingly, the terminal can receive indication information #4 from the session management network element. For example, if the terminal requests to establish or modify its session, the terminal receives the aforementioned response from the session management network element. For details, please refer to the relevant description in S702 above; further elaboration is unnecessary.

[0286] Optionally, the response may also include information indicating the first time start point, such as the indication information #2 mentioned above. For details, please refer to the relevant introduction of S504 above, which will not be repeated here.

[0287] For S902, the session management network element can determine whether the first time start point and the second time start point are the same. If the first time start point and the second time start point are different, it sends indication information #4 to the terminal and / or user plane network element. In other words, if the first time start point and the second time start point are the same, the session management network element does not need to send indication information #4 to reduce redundancy and improve communication efficiency. Of course, the session management network element can also send indication information #4 to the terminal and / or user plane network element by default.

[0288] S903, Terminal and / or user plane network element save time offset.

[0289] For S903, under time synchronization, user plane network elements can use the saved time offset to correct the entry timestamp, or the terminal can use the saved time offset to correct the exit timestamp. The following describes the different cases.

[0290] Scenario A: The user plane network element uses the saved time offset to correct the entry timestamp.

[0291] The user plane network element can receive time information #1 from the DN and determine the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point. Then, the user plane network element can determine a timestamp (or entry timestamp) based on the time offset and the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point. The entry timestamp indicates the time when time information #1 arrives at the user plane network element, specifically indicating the offset of the time when time information #1 arrives at the user plane network element relative to the first time starting point. For example, if the time offset is ΔT, the offset of the time when time information #1 arrives at the user plane network element relative to the second time starting point is TSi1, and the offset of the time when time information #1 arrives at the user plane network element relative to the first time starting point is TSi2; when the time offset is the offset of the first time starting point relative to the second time starting point, the entry timestamp satisfies the following relationship: TSi2 = TSi1 + ΔT; when the time offset is the offset of the second time starting point relative to the second time starting point, the entry timestamp satisfies the following relationship: TSi2 = TSi1 - ΔT.

[0292] The user plane network element can also send time information #1, which includes the aforementioned entry timestamp, to the terminal.

[0293] It should be understood that situation A can also refer to the relevant introduction of S503 above, and will not be repeated here.

[0294] Scenario B: The terminal uses the saved time offset to correct the exit timestamp.

[0295] The terminal can also receive time information #2 from user plane network elements.

[0296] Time information #2 may include a first timestamp, which can be understood as an entry timestamp. The first timestamp can indicate the time when time information #2 arrives at the user plane network element, such as specifically indicating the offset of the time when time information #2 arrives at the user plane network element relative to the second time starting point.

[0297] The terminal can determine the dwell time of time information #2 based on the time offset, the first timestamp, and the second timestamp.

[0298] The second timestamp can be understood as the exit timestamp. It indicates the time when time information #2 arrives at the terminal, specifically the offset of its arrival time relative to the first time starting point. Based on this, the time offset is ΔT, the first timestamp is TSi, the second timestamp is TSe, and the dwell time is RT. When the offset is the offset of the first time starting point relative to the second time starting point, the dwell time satisfies the following relationship: RT = TSe - TSi + ΔT. When the offset is the offset of the second time starting point relative to the third time starting point, the dwell time satisfies the following relationship: RT = TSe - TSi - ΔT. Therefore, the terminal can use the dwell time to further synchronize the ES time.

[0299] It should be understood that situation B can also refer to the relevant introduction of S703 above, and will not be repeated here.

[0300] In summary, when the starting points of time used by the terminal and the user plane network element may differ, the session management network element can obtain the starting points of time used by the terminal and the user plane network element respectively, determine the time offset between the two, and notify the user plane network element and / or the terminal. In this way, the user plane network element can correct the entry timestamp based on the time offset, or the terminal can also correct the exit timestamp based on the time offset, so as to realize the synchronization of time between the user plane network element and the terminal, thereby improving the availability and reliability of time synchronization.

[0301] The above combination Figure 9 The overall process of this communication method has been introduced. The following section will combine... Figures 10-11 This section describes the specific process of this communication method in some example application scenarios.

[0302] Figure 10 Flowchart of the communication method provided in the embodiments of this application Figure 6 . Figure 10 The process shown mainly involves the interaction between UE / DS-TT (as the terminal mentioned above), SMF (as the session management network element mentioned above), UDM (as the data storage network element mentioned above), and UPF / NW-TT (as the user plane network element mentioned above).

[0303] Specifically, such as Figure 10 As shown, the flow of this communication method is as follows:

[0304] S1000, the UE receives the PMIC information from DS-TT.

[0305] S1001, the UE sends a session establishment request message to the SMF.

[0306] S1002, SMF obtains the UE's contract from UDM.

[0307] S1003, SMF selects the first time starting point.

[0308] It should be understood that S1000-S1003 can be referred to the relevant introduction of S600-S603 above, and will not be repeated here.

[0309] S1004, SMF determines the time offset.

[0310] S1005, SMF sends N4 message to UPF / NW-TT.

[0311] The N4 message can contain indication information #4 to indicate the time offset.

[0312] It should be understood that the details of S1004-S1005 can also be found in the relevant introduction of S902 above, and will not be repeated here.

[0313] S1006, SMF sends N1 SM message to UE.

[0314] The N1 SM message can be understood as a response to the session, such as indicating whether the UE's session establishment was successful or failed.

[0315] Optionally, if the UE uses multiple time start points, the N1 SM message may also include indication information #2. For details, please refer to the relevant introduction of S504 above, which will not be repeated here.

[0316] S1007, UPF / NW-TT receives gTPT messages from TSN DN.

[0317] gTPT messages can include time information #1.

[0318] S1008, UPF / NW-TT determines the entry timestamp.

[0319] The entry timestamp can be denoted as TSi2, satisfying TSi2=TSi1+ΔT, or TSi2=TSi1-ΔT, where TSi1 is the offset of the time when time information #1 arrives at UPF / NW-TT relative to the second time starting point used by UPF / NW-TT, and ΔT is the time offset.

[0320] S1009, UPF / NW-TT sends downlink data to UE / DS-TT.

[0321] The downlink data carries time information #1, which includes the aforementioned entry timestamp.

[0322] S1010, UE / DS-TT determines the dwell time.

[0323] The length of stay is TSe-TSi2.

[0324] TSe is the offset of the time when time information #1 arrives at UE / DS-TT relative to the first time starting point.

[0325] It should be understood that S1007-S1010 can also refer to the relevant introductions of S606-S609, and will not be repeated here.

[0326] Figure 11 Flowchart of the communication method provided in the embodiments of this application Figure 7 . Figure 11 The process shown mainly involves the interaction between UE / DS-TT (as the terminal mentioned above), SMF (as the session management network element mentioned above), PCF (as the policy control network element mentioned above), and UPF / NW-TT (as the user plane network element mentioned above).

[0327] Specifically, such as Figure 11 As shown, the flow of this communication method is as follows:

[0328] S1100, the UE receives the PMIC information from DS-TT.

[0329] S1101, the UE sends a session establishment request message to the SMF.

[0330] The Session Establishment Request message can be used to request the establishment of a session for the UE.

[0331] In S1100-S1101, the UE can determine from the PMIC information that the DS-TT has a communication requirement with the TSN DN, and thus can trigger the establishment of a session, i.e., execute S1101.

[0332] S1102, SMF obtains the PCC rules for the session from PCF.

[0333] PCC rules can include third information, namely, the time starting point indicating the DN's use, i.e., the second time starting point.

[0334] It should be understood that S1100-S1102 can also refer to the relevant introduction of S901 above, and will not be repeated here.

[0335] S1103, SMF determines the time offset.

[0336] S1104, SMF sends N1 SM message to UE.

[0337] The N1 SM message can be understood as a response to the session, such as indicating whether the UE's session establishment was successful or failed.

[0338] The N1 SM message also includes indication information #4 to indicate the time offset, which can be found in the relevant introduction of S902 above, and will not be repeated here.

[0339] S1105, UPF / NW-TT receives gTPT messages from TSN DN.

[0340] gTPT messages can include time information #2.

[0341] S1106, UPF / NW-TT determines the first timestamp.

[0342] For the first timestamp, please refer to the relevant introduction in S903 above, which will not be repeated here.

[0343] UPF / NW-TT can encapsulate the first timestamp into time information #2.

[0344] S1107, UPF / NW-TT sends downlink data to UE / DS-TT.

[0345] The downlink data carries time information #2, which includes the aforementioned first timestamp.

[0346] S1108, UE / DS-TT determines the dwell time.

[0347] The dwell time is TSe-TSi+ΔT or TSe-TSi-ΔT. For details, please refer to the relevant introduction of S903 above, which will not be repeated here.

[0348] It should be understood that the above Figures 9-11 The methods shown are merely examples and are not intended to be limiting. For instance, the session management network element can pre-configure or predefine other time starting points, such as a third time point, which differs from the first and second time points and could be a newly defined time starting point in the future. The session management network element can determine the time offset #1 between the first and third time points and send it to the terminal. It can also determine the time offset #2 between the second and third time points and send it to the user plane network element. Thus, the user plane network element can determine the entry timestamp based on the time offset #2, and correspondingly, the terminal can determine the exit timestamp based on the time offset #1 and further determine the dwell time, thereby completing time synchronization.

[0349] Figure 12 This is a flowchart illustrating the communication method. Figure 8 This communication method mainly involves the interaction between the terminal and the user plane network element in the above communication system, and mainly involves the user plane network element notifying the terminal of the start time of the user plane network element's use.

[0350] like Figure 12 As shown, the flow of this communication method is as follows:

[0351] S1201, User plane network element obtains the second time starting point.

[0352] The second time starting point is the time starting point for the use of user plane network elements. For details, please refer to the relevant introduction above, which will not be repeated here.

[0353] User plane network elements can obtain a pre-configured or protocol-predefined second time starting point locally, or they can obtain a second time starting point from the DN, without specific restrictions.

[0354] S1202, the user plane network element sends an instruction message to the terminal.

[0355] For S1202, the indication information can be denoted as indication information #5. Indication information #5 can be used to indicate the second time start point for time synchronization between the terminal and the user plane network element. For example, indication information #5 can indicate the type of the second time start point, or it can also contain the specific time of the second time start point. For details, please refer to the relevant introduction above, which will not be repeated here.

[0356] Specifically, in the case of time synchronization, the user plane network element can receive time information from the DN, such as time information #3. The user plane network element can determine a timestamp, such as the first timestamp mentioned above, which indicates the offset of the time when time information #3 arrives at the user plane network element relative to the second time starting point. Then, the user plane network element can send time information #3 carrying the timestamp and indication information #5 to the terminal. Time information #3 also includes indication information #5. Accordingly, the terminal can determine the dwell time based on the received time information #3. The specific implementation principle is similar to that in case B above, and will not be repeated here.

[0357] It should be understood that the above example is based on the user plane network element indicating the second time start point to the terminal through the user plane, but it is not a limitation. For example, the user plane network element can also indicate the second time start point to the terminal through the control plane.

[0358] In summary, when the starting point of time used by the terminal and the user plane network element may differ, the user plane network element can transmit its own starting point of time to the terminal through the user plane. In this way, the terminal can correct its egress timestamp based on the deviation between the starting point of time used by the user plane network element and the starting point of time used by the terminal, thereby achieving time synchronization between the user plane network element and the terminal and improving the availability and reliability of time synchronization.

[0359] It should be understood that the above Figure 12 The processes shown are merely examples and are not intended to be limiting. For instance, the terminal may also report the first time start point to the user plane network element so that the user plane network element can correct the entry timestamp.

[0360] It should also be understood that the above is based on user plane network elements as an example. In the case of NW-TT and access network equipment being co-located, the above user plane network elements can also be replaced by the access network equipment, that is, the access network equipment accessed by the terminal.

[0361] The above combination Figures 5-12 The communication method provided in the embodiments of this application is described in detail below. Figure 13 and Figure 14 This document describes in detail the communication apparatus used to perform the communication method provided in the embodiments of this application.

[0362] For example, Figure 13 This is a schematic diagram of the structure of the communication device provided in the embodiments of this application. Figure 1 .like Figure 13 As shown, the communication device 1300 includes a processing module 1301 and a transceiver module 1302. For ease of explanation, Figure 13 Only the main components of the communication device are shown.

[0363] In some embodiments, the communication device 1300 may be adapted to Figure 4 In the communication system shown, the execution Figures 5-12 The function of the session management network element in the communication method shown.

[0364] The transceiver module 1302 is used to perform the transceiver functions of the session management network element.

[0365] The processing module 1301 is used to perform functions of the session management network element other than the sending and receiving functions.

[0366] Optionally, the communication device 1300 may also include a storage module. Figure 13 (Not shown in the image), this storage module stores programs or instructions. When the processing module 1301 executes the program or instructions, it enables the communication device 1300 to perform operations. Figures 5-12 The communication method shown illustrates the function of the session management network element. It should be understood that the processing module 1301 involved in the communication device 1300 can be implemented by a processor or processor-related circuit components, and can be a processor or processing unit; the transceiver module 1302 can be implemented by a transceiver or transceiver-related circuit components, and can be a transceiver or transceiver unit.

[0367] Furthermore, the communication device 1300 can be a network device, a chip (system) or other component or assembly disposed within a network device, or a device containing the network device; this application embodiment does not limit this. The technical effects of the communication device 1300 can be referred to separately. Figures 5-12 The technical effects of any of the communication methods shown will not be elaborated here.

[0368] In other embodiments, the communication device 1300 may be adapted to Figure 4 In the communication system shown, the execution Figures 5-12 The function of the user plane network element in the communication method shown.

[0369] The transceiver module 1302 is used to perform the transceiver functions of the user plane network element.

[0370] The processing module 1301 is used to perform functions of the user plane network element other than the transmit and receive functions.

[0371] Optionally, the communication device 1300 may also include a storage module. Figure 13 (Not shown in the image), this storage module stores programs or instructions. When the processing module 1301 executes the program or instructions, it enables the communication device 1300 to perform operations. Figures 5-12 The communication method shown illustrates the function of the user plane network element. It should be understood that the processing module 1301 involved in the communication device 1300 can be implemented by a processor or processor-related circuit components, and can be a processor or processing unit; the transceiver module 1302 can be implemented by a transceiver or transceiver-related circuit components, and can be a transceiver or transceiver unit.

[0372] Furthermore, the communication device 1300 can be a network device, a chip (system) or other component or assembly disposed within a network device, or a device containing the network device; this application embodiment does not limit this. The technical effects of the communication device 1300 can be referred to separately. Figures 5-12 The technical effects of any of the communication methods shown in the examples are not elaborated here.

[0373] In some other embodiments, the communication device 1300 may be adapted to Figure 4 In the communication system shown, the execution Figures 5-12 The terminal function in the communication method shown.

[0374] The transceiver module 1302 is used to perform the terminal's transceiver functions.

[0375] The processing module 1301 is used to perform functions of the terminal other than sending and receiving functions.

[0376] Optionally, the communication device 1300 may also include a storage module. Figure 13 (Not shown in the image), this storage module stores programs or instructions. When the processing module 1301 executes the program or instructions, it enables the communication device 1300 to perform operations. Figures 7-11 The terminal function in the communication method shown. It should be understood that the processing module 1301 involved in the communication device 1300 can be implemented by a processor or processor-related circuit components, and can be a processor or processing unit; the transceiver module 1302 can be implemented by a transceiver or transceiver-related circuit components, and can be a transceiver or transceiver unit.

[0377] Furthermore, the communication device 1300 can be a terminal, a chip (system) or other component or assembly disposed in a terminal, or a device containing the terminal; this application embodiment does not limit this. The technical effects of the communication device 1300 can be referred to separately. Figures 5-12 The technical effects of any of the communication methods shown in the figure will not be elaborated here.

[0378] Figure 14 Schematic diagram of the communication device provided in the embodiments of this application Figure 2 For example, the communication device can be a terminal, or a chip (system) or other component or assembly that can be set in the terminal. Figure 14 As shown, the communication device 1400 may include a processor 1401. Optionally, the communication device 1400 may also include a memory 1402 and / or a transceiver 1403. The processor 1401 is coupled to the memory 1402 and the transceiver 1403, for example, they may be connected via a communication bus.

[0379] The following is combined Figure 14 A detailed description of each component of the communication device 1400 is provided below:

[0380] The processor 1401 is the control center of the communication device 1400. It can be a single processor or a collective term for multiple processing elements. For example, the processor 1401 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement the embodiments of this application, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0381] Optionally, the processor 1401 can perform various functions of the communication device 1400, such as the functions described above, by running or executing software programs stored in the memory 1402 and calling data stored in the memory 1402. Figures 5-12 The communication method shown.

[0382] In a specific implementation, as one example, the processor 1401 may include one or more CPUs, for example... Figure 14 CPU0 and CPU1 are shown in the diagram.

[0383] In a specific implementation, as one example, the communication device 1400 may also include multiple processors, for example... Figure 14 The processors 1401 and 1404 are shown. Each of these processors can be a single-core processor or a multi-core processor. A processor here can refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0384] The memory 1402 is used to store the software program that executes the solution of this application, and is controlled by the processor 1401 to execute it. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0385] Optionally, the memory 1402 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 1402 may be integrated with the processor 1401 or may exist independently, and may be connected via the interface circuit of the communication device 1400. Figure 14 (Not shown in the image) is coupled to processor 1401, and this embodiment of the application does not specifically limit this.

[0386] Transceiver 1403 is used for communication with other communication devices. For example, if communication device 1400 is a terminal, transceiver 1403 can be used to communicate with a network device or with another terminal device. As another example, if communication device 1400 is a network device, transceiver 1403 can be used to communicate with a terminal or with another network device.

[0387] Alternatively, transceiver 1403 may include a receiver and a transmitter. Figure 14 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the sending function.

[0388] Alternatively, the transceiver 1403 can be integrated with the processor 1401, or it can exist independently and be connected via the interface circuit of the communication device 1400. Figure 14 (Not shown in the image) is coupled to processor 1401, and this embodiment of the application does not specifically limit this.

[0389] Understandable Figure 14 The structure of the communication device 1400 shown does not constitute a limitation on the communication device. Actual communication devices may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0390] Furthermore, the technical effects of the communication device 1400 can be referred to the technical effects of the method described in the above method embodiments, and will not be repeated here.

[0391] It should be understood that the processor in the embodiments of this application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0392] It should also be understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0393] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0394] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0395] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0396] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0397] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0398] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0399] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0400] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0401] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0402] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0403] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method characterized by comprising: Applied to session management network elements, including: Obtain the first point in time when the terminal is in use; An instruction message is sent to the user plane network element serving the terminal, the instruction message indicating the first time start point, the first time start point being used for the user plane network element to synchronize time with the terminal.

2. The method of claim 1, wherein, The first time starting point used by the acquisition terminal includes: The terminal receives first information indicating one or more time start points used by the terminal, the one or more time start points including the first time start point.

3. The method of claim 2, wherein, The receipt of the first information from the terminal includes: A session request message is received from the terminal, the session request message requesting the establishment or modification of a session on the terminal, the session request message including the first information.

4. The method according to any one of claims 1-3, characterized in that, Sending indication information to the user plane network element serving the terminal includes: Send the configuration of the session for the terminal to the user plane network element, the configuration including the indication information.

5. The method according to any one of claims 1 to 4, characterized in that, The first time start point is the time start point used by the user-side time-sensitive network converter DS-TT of the terminal, or the first time start point is the time start point used by the access network node serving the terminal.

6. A communication method characterized by comprising: Applied to session management network elements, including: Obtain the second time starting point for the user plane network element used by the terminal; The terminal is sent an instruction message indicating the second time start point, which is used for the terminal to synchronize its time with the user plane network element.

7. The method of claim 6, wherein, The process of obtaining the second time starting point used by the user plane network element serving the terminal includes: The terminal's session information is obtained, and the session information includes third information, which indicates the second time start point.

8. The method of claim 7, wherein, Obtaining session information for the terminal includes: In response to a terminal request to establish or modify a session of the terminal, information about the session is obtained.

9. The method according to claim 7 or 8, characterized in that, The information in the session is the policy and charging control (PCC) rules.

10. The method according to any one of claims 6-9, characterized in that, The user plane network element is the user plane network element selected for the session.

11. The method according to any one of claims 6-10, characterized in that, Sending instruction information to the terminal includes: Send a response to the terminal for the session of the terminal, the response including the indication information.

12. The method according to any one of claims 6-11, characterized in that, The second time starting point is the time starting point used by the network-side time-sensitive network converter NW-TT of the user plane network element.

13. A method of communication, comprising: Devices applied on the terminal side include: Receive instruction information, the instruction information indicating a second time start point used by the user plane network element, the user plane network element serving the terminal, the time start point used by the terminal is a first time start point, the first time start point is different from the second time start point; Save the second time starting point.

14. The method of claim 13, wherein, The receiving indication information includes: The terminal receives the instruction information from a session management network element, which serves the terminal.

15. The method according to claim 14, characterized in that, The receipt of the indication information from the session management network element includes: When the terminal requests to establish or modify a session for the terminal, the system receives a response from the session management network element for the session, the response including the indication information.

16. The method according to any one of claims 13-15, characterized in that, The method further includes: Receive time information from the user plane network element, the time information including a first timestamp, the first timestamp indicating the time when the time information arrives at the user plane network element; The residence time of the time information is determined based on the time offset, the first timestamp, and the second timestamp. The time offset is the offset of the first time start point relative to the second time start point, or the offset of the second time start point relative to the first time start point. The second timestamp indicates the time when the time information arrives at the terminal.

17. The method of claim 16, wherein, The time offset is ΔT, the first timestamp is TSi, the second timestamp is TSe, and the dwell time is RT. When the offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: RT = TSe - TSi + ΔT. When the offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: RT = TSe - TSi - ΔT.

18. The method of claim 16 or 17, wherein, The time information also includes the indication information.

19. A method of communication, comprising: Applied to user plane network elements, including: The terminal receives an instruction message, which indicates a first time starting point used by the terminal. The user plane network element serves the terminal. The time starting point used by the user plane network element is a second time starting point. The first time starting point is different from the second time starting point. Determine the time offset, which is the offset of the first time starting point relative to the second time starting point, or the offset of the second time starting point relative to the first time starting point.

20. The method of claim 19, wherein, The receiving indication information includes: The terminal receives the instruction information from a session management network element, which serves the terminal.

21. The method of claim 20, wherein, The receipt of the indication information from the session management network element includes: When the terminal requests to establish or modify a session, the system receives the session configuration sent by the session management network element, the configuration including the indication information.

22. The method according to any one of claims 19-21, characterized by, The method further includes: Receive time information from the data network; A timestamp is determined based on the time offset and the offset of the time when the time information arrives at the user plane network element relative to the second time starting point. The timestamp indicates the offset of the time when the time information arrives at the user plane network element relative to the first time starting point. The time information, including the timestamp, is sent to the terminal.

23. The method of claim 22, wherein, The time offset is ΔT, the time offset of the time when the time information arrives at the user plane network element relative to the second time starting point is TSi1, and the time offset of the time when the time information arrives at the user plane network element relative to the first time starting point is TSi2; when the time offset is the offset of the first time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1+ΔT; when the time offset is the offset of the second time starting point relative to the second time starting point, the following relationship is satisfied: TSi2=TSi1-ΔT.

24. A communications device, characterized by The communication device includes a model for performing the method as described in any one of claims 1-23.

25. A communication device, characterized in that, include: Processor and memory; The memory is used to store computer instructions that, when executed by the processor, cause the communication device to perform the method as described in any one of claims 1-23.

26. The communication apparatus according to claim 25, wherein, The communication device is a chip.

27. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a computer program or instructions that, when executed, cause the method as described in any one of claims 1-23 to be performed.

28. A computer program product, characterised in that, The computer program product includes: a computer program or instructions that, when run, cause the method described in any one of claims 1-23 to be performed.

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