Communication method and apparatus

Abstract

The present application belongs to the technical field of communications. Provided are a communication method and apparatus. In the method, in the case of a clock synchronization service provided for a group, only by means of determining a time difference between an access network device (e.g., a first access network device) and a member (e.g., a first terminal) in the group, can clock synchronization between terminals other than the first terminal in the group and the first terminal be realized, that is, clock synchronization of the group is realized.

Description

Communication method and device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on August 17, 2023, with application number 202311045122.8 and application name “Communication Method and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a communication method and device. Background Art

[0003] The fifth-generation (5G) mobile communication system (5GS) synchronizes two externally clocked user equipment (UE) using the general precise time protocol (gPTP). For example, a UE carries time-sensitive network (TSN) clock information in a gPTP message. This information is then transmitted to another UE's device-side TSN translator (DS-TT) via functions integrated into the user plane function (UPF) network element, such as the network TSN translator (NW-TT). The UE then calculates the offset between the 5G clock and the TSN clock based on the timestamp information in the gPTP message, ultimately obtaining accurate TSN clock information and achieving clock synchronization between the two terminal devices.

[0004] However, this approach may not be able to meet future clock synchronization needs.

[0005] Summary of the Invention

[0006] Embodiments of the present application provide a communication method and apparatus to achieve clock synchronization of a group.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a communication method is provided, comprising: a first access network device receiving a first message and obtaining a first time difference based on the first message. The first message indicates that the first access network device requires a clock synchronization service for a group. The first time difference is the time difference between a first terminal and the first access network device. The first terminal is a member of a group, and the first time difference is used to synchronize the clocks of other terminals in the group with the first terminal.

[0009] In the above scheme, when the clock synchronization service is provided for the group, by determining the time difference between the access network device (such as the first access network device) and the members of the group (such as the first terminal), it is possible to synchronize the clocks of other terminals in the group except the first terminal with the clocks of the first terminal, that is, to achieve clock synchronization of the group.

[0010] It is understood that the first message can be an interface message between the first access network device and the core network, such as an N2 message, or any other possible message, without limitation. In addition, the first time difference can also be understood as the difference between the time indicated by the reference time information of the first terminal and the time indicated by the reference time information of the first access network device.

[0011] It can be understood that the group may include a second terminal, and the first access network device may further use the first time difference to synchronize the clock of the second terminal with that of the first terminal, as follows.

[0012] In one possible design, the method described in the first aspect may further include: the first access network device sending a second message to the second terminal, wherein the second message carries the first time difference, or the first access network device broadcasting a third message, wherein the third message carries the first time difference. In other words, if the first access network device and the second terminal have already achieved clock synchronization, the first access network device can achieve clock synchronization between the first and second terminals by simply providing the first time difference, thereby reducing communication overhead.

[0013] The second message may be a unicast message, such as a radio resource control (RRC) message, a downlink control information (DCI) message, a media access control element (MAC_CE), etc., without limitation. The third message may be a broadcast message, such as a system message, without limitation.

[0014] Optionally, the first time difference is encrypted ciphertext. For example, if the first time difference is sent via a broadcast message, it can be encrypted ciphertext to prevent information theft and ensure communication security for clock synchronization. The second terminal can decrypt the ciphertext, for example, by pre-configuring a key required for decryption to the second terminal, or the key can be predetermined by the protocol.

[0015] Optionally, the method described in the first aspect may further include: synchronizing the clocks of the first access network device and the second terminal, such as by the first access network device sending reference time information of the first access network device to the second terminal via unicast or broadcast. To achieve higher clock accuracy, clock synchronization may also be achieved using propagation delay compensation (PDC), such as a TA-based, RTT-based, or other method, although this solution does not impose any restrictions on this.

[0016] In one possible design scheme, the first access network device sends the first time difference and the reference time information of the first access network device to the second terminal; or, the first access network device broadcasts the first time difference and the reference time information of the first access network device, so that the second terminal can achieve clock synchronization with the first terminal by adding the first time difference and the time of the reference time information of the first access network device.

[0017] Optionally, the first time difference and / or the reference time information of the first access network device may be encrypted ciphertext. For example, if the first time difference and / or the reference time information of the first access network device is transmitted via a broadcast message, it may be encrypted ciphertext to prevent information theft. Similarly, the second terminal can also decrypt the ciphertext.

[0018] Optionally, the first time difference and the reference time information of the first access network device can be carried in separate messages. For example, the first access network device sends the first time difference via a unicast message and sends the reference time information of the first access network device via a broadcast message. In another example, the first access network device sends the first time difference via a broadcast message and sends the reference time information of the first access network device via a unicast message. In another example, the first access network device sends the first time difference and the reference time information of the first access network device via separate unicast / broadcast messages. This decouples transmission and provides more flexible information transfer. Of course, the first time difference and the reference time information of the first access network device can also be carried in the same message, which is not a limitation. Optionally, the time indicated by the reference time information of the first access network device is the time when the first access network device sends the reference time information of the first access network device. In other words, regardless of whether propagation delay compensation (PDC) is performed between the first access network device and the second terminal, if the PDC is relatively small, the second terminal can obtain a relatively accurate time of the first terminal by adding the time when the reference time information of the first access network device is sent to the first time difference, thereby achieving clock synchronization with the first terminal.

[0019] Optionally, the method described in the first aspect may further include: the first access network device sending, to the second terminal, a PDC value of the first access network device and the second terminal. That is, group clock synchronization may further consider propagation delay compensation between the access network device and the terminal, thereby achieving more accurate clock synchronization. In this case, the PDC value may be carried in the aforementioned second message or the new message, without limitation.

[0020] It can be understood that the above-mentioned first time difference, reference time information of the first access network device and PDC value can be carried in the same message, or can be carried in different messages respectively. For example, the reference time information of the first access network device can be sent through one message first, and then the first time difference and PDC values ​​can be sent respectively through another two messages. There can also be other implementation methods, which are not limited to this.

[0021] In one possible design, the first access network device sends a second message to the second terminal based on the first time difference, where the second message carries the first terminal's reference time information. Alternatively, the first access network device broadcasts a third message based on the first time difference, where the third message carries the first terminal's reference time information. In other words, the first access network device can send the first terminal's time to the second terminal based on the first time difference, eliminating the need for the second terminal to determine its own time. This reduces the second terminal's overhead and improves energy efficiency.

[0022] As described above, the second message may also be a unicast message, and the third message may also be a broadcast message. For specific implementation, please refer to the above related introduction, which will not be repeated here.

[0023] Optionally, the first terminal's reference time information can be encrypted. For example, if the first terminal's reference time information is sent via a broadcast message, it can be encrypted to prevent information theft and ensure secure clock synchronization. Similarly, the second terminal can also decrypt the encrypted information.

[0024] Optionally, the reference time information of the first terminal is determined by the first access network device based on the first time difference and the reference time information of the first access network device. For example, the time indicated by the reference time information of the first access network device may be the time when the first access network device sends the reference time information of the first terminal. Without considering the value of the propagation delay compensation (PDC) between the first access network device and the second terminal, if the value of the propagation delay compensation (PDC) is relatively small, by adding the time when the reference time information of the first terminal is sent to the first time difference, a relatively accurate time of the first terminal can be obtained, thereby achieving clock synchronization with the first terminal.

[0025] Optionally, the method described in the first aspect may further include: the first access network device sending a value of the PDC of the first access network device and the second terminal to the second terminal.

[0026] The second message also carries the value of the propagation delay compensation PDC between the first access network device and the second terminal to achieve more accurate clock synchronization. Similarly, the value of the PDC can also be carried in the above-mentioned second message or new message, and this is not limited.

[0027] Optionally, the second terminal is a member of the group, or the second terminal is a new member of the group, that is, no matter it is an initial member of the group or a new member of the group, the first access network device can provide the second terminal with a group clock synchronization service.

[0028] In one possible design scheme, the first message includes at least one of the following: an identifier of the group, an identifier of the first terminal, or identifiers of other terminals in the group except the first terminal, to indicate each member of the group, thereby avoiding the situation where clock synchronization service is not provided to certain members of the group due to failure to indicate the members.

[0029] Optionally, the information included in the first message can also be used to indicate that other terminals in the group, excluding the first terminal, need to synchronize their clocks with the first terminal. For example, group members can be divided into two categories: master clock members and non-master clock members. The master clock member's clock serves as a reference, and the non-master clock members synchronize their clocks with the master clock member. In this case, the indication information included in the first message can be an identifier of a clock member, indicating that the first terminal is a master clock member, thereby implicitly indicating that other terminals in the group, excluding the first terminal, need to synchronize their clocks with the first terminal.

[0030] In one possible design scheme, the method described in the first aspect may also include: the first access network device sends a first time difference to the second access network device, so that the second access network device can provide clock synchronization services to other group members in the group that are connected to the second access network device.

[0031] In a possible design scheme, the method described in the first aspect may also include: the first access network device sends the first time difference to the policy control network element and / or the data management network element to save the first time difference to the network so that it does not need to be re-determined for subsequent use.

[0032] In one possible design scheme, the group may include a second terminal. When the second terminal switches to a second access network device, the first access network device sends the timing context of the second terminal to the second access network device, wherein the timing context of the second terminal is used to indicate the first time difference. And / or, the timing context of the second terminal is also used to indicate that the second terminal is a non-master clock member in the group. For example, the timing context of the second terminal includes the identifier of the second terminal and does not include the identifier of the master clock member, indicating that the second terminal is a non-master clock member in the group. It can be understood that the non-master clock member can also refer to the relevant introduction above, which will not be repeated here.

[0033] In one possible design, when the first terminal switches to a third access network device, the first access network device sends the timing context of the first terminal to the third access network device and receives the second time difference returned by the third access network device. The second time difference is the time difference between the first terminal and the third access network device. The timing context of the first terminal is used to indicate that the first terminal is a master clock member in the group. For example, the timing context of the first terminal includes the identifier of the first terminal and the identifier of the master clock member, indicating that the first terminal is a master clock member in the group. It can be understood that the master clock member can also refer to the relevant introduction above, which will not be repeated here.

[0034] It is understandable that the group may include a second terminal. When the first terminal switches to a third access network device, the first access network device may also use a second time difference to synchronize the second terminal with the first terminal clock, as follows.

[0035] In one possible design scheme, the first access network device sends a fourth message to the second terminal, wherein the fourth message carries the second time difference; or, the first access network device broadcasts a fifth message, wherein the fifth message carries the second time difference.

[0036] Optionally, the second time difference may be an encrypted ciphertext. Similarly, the second terminal can also decrypt the ciphertext.

[0037] Optionally, the method described in the first aspect may further include: the first access network device and the second terminal completing clock synchronization.

[0038] In one possible design scheme, the first access network device sends the second time difference and the reference time information of the first access network device to the second terminal; or, the first access network device broadcasts the second time difference and the reference time information of the first access network device.

[0039] Optionally, the second time difference and / or the reference time information of the first access network device is an encrypted ciphertext, and the second terminal can decrypt the ciphertext.

[0040] Optionally, the second time difference and the reference time information of the first access network device are carried in different messages, or may be carried in the same message, which is not limited.

[0041] Optionally, the time indicated by the reference time information of the first access network device is the time when the first access network device sends the reference time information of the first access network device.

[0042] Optionally, the method described in the first aspect may further include: the first access network device sending a value of the PDC of the first access network device and the second terminal to the second terminal.

[0043] It is understood that the second time difference, the reference time information of the first access network device, and the PDC value can be carried in the same message, or can be carried in different messages. For example, the reference time information of the first access network device can be sent in one message first, and the second time difference and the PDC value can be sent in two other messages respectively. Other implementation methods are also possible and are not limited to this.

[0044] In one possible design, the method described in the first aspect may further include: the first access network device sending a fourth message to the second terminal based on the second time difference, wherein the fourth message carries reference time information of the first terminal. Alternatively, the first access network device broadcasts a fifth message based on the second time difference, wherein the fifth message carries the reference time information of the first terminal.

[0045] Optionally, the reference time information of the first terminal may be an encrypted ciphertext. Similarly, the second terminal can also decrypt the ciphertext to ensure the communication security of clock synchronization.

[0046] Optionally, the reference time information of the first terminal is determined by the first access network device based on the second time difference and the reference time information of the first access network device. For example, the time indicated by the reference time information of the first access network device may be the time when the first access network device sends the reference time information of the first terminal.

[0047] Optionally, the method described in the first aspect may further include: the first access network device sending a value of the PDC of the first access network device and the second terminal to the second terminal.

[0048] It can be understood that the implementation principle of the above-mentioned first access network device using the second time difference to synchronize the second terminal clock with the first terminal is similar to the implementation principle of the first access network device using the first time difference to synchronize the second terminal clock with the first terminal. You can refer to it for understanding and will not repeat it here.

[0049] In a possible design scheme, the method described in the first aspect may further include: the first access network device sends a first time difference to a clock synchronization network element, such as a time-sensitive communication and time synchronization function TSCTSF network element. The clock synchronization network element determines the policy control network element corresponding to the members in the group, such as a PCF network element, or a PCF network element serving the members in the group, and the policy control network element determines the access and mobility management network element corresponding to the non-master clock members of the group, such as an AMF network element, or an AMF network element serving the non-master clock members of the group, and sends the first time difference to the access and mobility management network element, and the access and mobility management network element sends the first time difference to the non-master clock members to achieve clock synchronization between the non-master clock members and the master clock members.

[0050] A second aspect provides a communication method, comprising: an access and mobility management network element receiving a first time difference from a first access network device, wherein the group first time difference is the time difference between a first terminal and the first access network device, and the first terminal is a member of a group. The access and mobility management network element then sends the first time difference to access network devices where other terminals in the group other than the first terminal are located, such as a second access network device. For details, please refer to the description of the second access network device in the first aspect above and will not be repeated here.

[0051] In a possible design scheme, the method described in the second aspect may also include: the access and mobility management network element receives a first time difference from the policy control network element. The specific principles can be referred to the relevant introduction of the first aspect above and will not be repeated here.

[0052] In one possible design, the method described in the second aspect may further include: the access and mobility management network element sending the first time difference to other terminals in the group other than the first terminal. Optionally, the access and mobility management network element determines the access network device where the other terminals are located, and sends the first time difference to the other terminals via the access network device.

[0053] That is, when managed by the access and mobility management network element, such as when determining the members of the group, the clock synchronization between the non-master clock member and the master clock member can still adopt the method described in the first aspect above. Alternatively, the access network device where the non-master clock member is located can perform clock synchronization with the non-master clock member. For example, the non-master clock member completes clock synchronization with the access network device by receiving the reference time information of the access network device where it is located. At this time, the access and mobility management network element can directly send the first time difference to the non-master clock member (that is, the access network device where the non-master clock member is located can be transparently transmitted) so that the non-master clock member can synchronize its own clock with the master clock member. In addition, in the case of access and mobility management network element management, if the access and mobility management network element determines that a non-master clock member has switched, such as switching from a source access network device to a target access network device, the access and mobility management network element can also actively send the first time difference to the target access network device, so that the target access network device immediately sends the first time difference to the non-master clock member, so that the non-master clock member and the master clock member are synchronized.

[0054] In a third aspect, a communication method is provided, comprising: an application function sending group information to a network, wherein the group information is used to request a group clock synchronization service, wherein the group clock synchronization service requires non-master clock members in the group to synchronize their clocks with the master clock member in the group; and the application function receiving a response from the network, wherein the response indicates that the network accepts the request for the group clock synchronization service. In other words, the clock synchronization service for the group can be triggered by the application function, such as when the group is created or updated, without limitation.

[0055] In one possible design, the group information further indicates that the master clock member is the first terminal, and that the non-master clock members in the group include the second terminal. Of course, the non-master clock members in the group may also include other terminals besides the second terminal, such as a third terminal or a fourth terminal, without limitation. This application uses the second terminal as an example for description.

[0056] Optionally, the group information is carried in the group clock synchronization creation request message, that is, the existing message is reused to trigger the clock synchronization service, or a newly defined message can be used to achieve decoupling from the existing message and more flexible clock synchronization.

[0057] In one possible design, the group information further indicates that the master clock member has been changed to the first terminal. At this point, the original master clock member may have left the group. Alternatively, the group information further indicates that newly added non-master clock members in the group include the second terminal. Similarly, newly added non-master clock members in the group may also include other terminals in addition to the second terminal, without limitation.

[0058] Optionally, group information is carried in a group update request message, that is, when a group is updated, the clock synchronization service can be triggered by reusing existing messages, or a newly defined message can be used to achieve decoupling from existing messages, making clock synchronization more flexible.

[0059] It can be understood that the relevant technical effects of the method described in the third aspect can also refer to the relevant introduction of the first aspect, which will not be repeated here.

[0060] In a fourth aspect, a communication method is provided, comprising: a clock synchronization network element receiving group information, wherein the group information is used to request a clock synchronization service for the group; and the clock synchronization network element initiating the group clock synchronization service for the group based on the group information.

[0061] In one possible design scheme, the clock synchronization network element receives group information, including: the clock synchronization network element receives a group clock synchronization creation request message from an application function, wherein the group clock synchronization creation request message carries group information, and the group information is also used to indicate that the master clock member is the first terminal, and the non-master clock members in the group include the second terminal.

[0062] In a possible design scheme, the clock synchronization network element receives group information, including: the clock synchronization network element receives group information from the data management network element, and the group information can also be used to indicate that the master clock member is changed to the first terminal, and / or the group information is also used to indicate that the newly added non-master clock members in the group include the second terminal. That is, by subscribing to the service of the data management network element, the update of the group can be learned and the clock synchronization service of the group can be triggered. For example, the clock synchronization network element can subscribe to the group information change notification (which carries the group identifier) ​​from the data management network element; in the case of a group information change, the clock synchronization network element receives the group information from the data management network element, that is, the data management network element sends the changed group information to the clock synchronization network element by way of a subscription notification. When the clock synchronization network element obtains the updated group information, the clock synchronization network element will initiate an update of the clock synchronization service of the group.

[0063] In one possible implementation, the method described in the fourth aspect may also include: the clock synchronization network element receives the first time difference from the first access network device, and sends the first time difference to the policy control network element corresponding to the members in the group. Optionally, the clock synchronization network element can determine the policy control network element based on the first time difference, and then send the first time difference to the policy control network element. The specific principles can be referred to the relevant introduction of the first aspect above, and will not be repeated here.

[0064] It can be understood that the relevant technical effects of the method described in the fourth aspect can also refer to the relevant introduction of the first aspect, which will not be repeated here.

[0065] In a fifth aspect, a communication device is provided. The communication device includes: a module for executing the method described in any one of aspects 1 to 4, such as a transceiver module and a processing module. For example, the transceiver module is configured to indicate the transceiver function of the communication device, and the processing module is configured to perform functions of the communication device other than the transceiver function.

[0066] Optionally, the transceiver module may include a sending module and a receiving module, wherein the sending module is used to implement the sending function of the communication device described in the fifth aspect, and the receiving module is used to implement the receiving function of the communication device described in the fifth aspect.

[0067] Optionally, the communication device described in the fifth aspect may further include a storage module, wherein the storage module stores a program or instruction. When the processing module executes the program or instruction, the communication device can execute the method described in any one of the first to fourth aspects.

[0068] It can be understood that the communication device described in the fifth aspect can be a network device, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device. This application does not limit this.

[0069] In addition, the technical effects of the communication device described in the fifth aspect can refer to the technical effects of the other aspects mentioned above and will not be repeated here.

[0070] In a sixth aspect, a communication device is provided, comprising: a processor configured to execute the method described in any one of the first to fourth aspects.

[0071] In one possible design solution, the communication device described in the sixth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the sixth aspect to communicate with other communication devices.

[0072] In one possible design, the communication device described in aspect 6 may further include a memory. The memory may be integrated with the processor or provided separately. The memory may be used to store the computer program and / or data involved in the method described in any one of aspects 1 to 4.

[0073] In an embodiment of the present application, the communication device described in the sixth aspect can be the network device described in any one of the first to fourth aspects, or a chip (system) or other parts or components that can be set in the network device, or a device that includes the network device.

[0074] In addition, the technical effects of the communication device described in the sixth aspect can refer to the technical effects of the methods described in any one of the first to fourth aspects, and will not be repeated here.

[0075] In a seventh aspect, a communication device is provided, comprising: a processor coupled to a memory, the processor configured to execute a computer program stored in the memory, so that the communication device performs the method described in any one of the first to fourth aspects.

[0076] In one possible design solution, the communication device described in the seventh aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the seventh aspect to communicate with other communication devices.

[0077] In an embodiment of the present application, the communication device described in the seventh aspect can be the network device described in any one of the first to fourth aspects, or a chip (system) or other parts or components that can be set in the network device, or a device that includes the network device.

[0078] In addition, the technical effects of the communication device described in the seventh aspect can refer to the technical effects of the methods described in any one of the first to fourth aspects, and will not be repeated here.

[0079] In an eighth aspect, a communication device is provided, comprising: a processor and a memory; the memory is used to store a computer program, and when the processor executes the computer program, the communication device executes the method described in any one of the first to fourth aspects.

[0080] In one possible design solution, the communication device described in the eighth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the eighth aspect to communicate with other communication devices.

[0081] In an embodiment of the present application, the communication device described in aspect 8 may be the network device described in any one of aspects 1 to 4, or a chip (system) or other parts or components that may be set in the network device, or a device that includes the network device.

[0082] In addition, the technical effects of the communication device described in the eighth aspect can refer to the technical effects of the methods described in any one of the first to fourth aspects, and will not be repeated here.

[0083] In a ninth aspect, a communication system is provided, comprising: the device / network element in the method described in at least two of the first to fourth aspects.

[0084] In a tenth aspect, a computer-readable storage medium is provided, comprising: a computer program or instructions; when the computer program or instructions are run on a computer, the computer is caused to execute the method described in any one of the first to fourth aspects.

[0085] In the eleventh aspect, a computer program product is provided, comprising a computer program or instructions, which, when executed on a computer, causes the computer to execute the method described in any one of the first to fourth aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 is a schematic diagram of the 5GS architecture;

[0087] Figure 2 is a schematic diagram of the TSN architecture;

[0088] Figure 3 is a schematic diagram of the TA-based process;

[0089] Figure 4 is a schematic diagram of the RTT-based process;

[0090] FIG5 is a schematic diagram of the architecture of a communication system provided in an embodiment of the present application;

[0091] FIG6 is a flow chart of a communication method according to an embodiment of the present application;

[0092] FIG7 is a second flow chart of the communication method provided in an embodiment of the present application;

[0093] FIG8 is a third flow chart of the communication method provided in an embodiment of the present application;

[0094] FIG9 is a fourth flow chart of a communication method according to an embodiment of the present application;

[0095] FIG10 is a first structural diagram of a communication device provided in an embodiment of the present application;

[0096] FIG11 is a second structural diagram of the communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0097] For ease of understanding, the technical terms involved in the embodiments of this application are first introduced below.

[0098] 1. Fifth generation (5G) mobile communication system (abbreviated as 5G system (5G system, 5GS)):

[0099] Figure 1 is a schematic diagram of the 5GS architecture. As shown in Figure 1, the 5GS includes an access network (AN) and a core network (CN), and may also include terminals.

[0100] A terminal may be a terminal with transceiver functions, or may be a chip or chip system provided in the terminal. The terminal may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station (MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal in the embodiments of the present application can be a mobile phone, a cellular phone, a smart phone, a tablet computer, a wireless data card, a personal digital assistant (PDA), a wireless modem, a handset, a laptop computer, a machine type communication (MTC) terminal, a computer with wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a smart home device (for example, a refrigerator, a television, an air conditioner, an electric meter, etc.), an intelligent robot, a robotic arm, a workshop equipment, a wireless terminal in unmanned driving, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical care, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a vehicle-mounted terminal, a roadside unit with terminal function, or a wireless terminal in a smart city. The terminal device of the present application may also be an onboard module, onboard module, onboard component, onboard chip or onboard unit built into a vehicle as one or more components or units. The terminal device may also be other devices with terminal functions, for example, the terminal device may also be a device that functions as a terminal in D2D communication.

[0101] The embodiments of this application do not limit the device form factor of the terminal. The device used to implement the functions of the terminal device can be the terminal device; it can also be a device that supports the terminal device to implement 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 include chips and other discrete devices.

[0102] The AN implements access-related functions, providing network access for authorized users and determining transmission links of varying quality for user data based on user level and service requirements. The AN forwards control signals and user data between terminals and the CN. The AN may include access network equipment, also known as radio access network (RAN) equipment.

[0103] The CN is mainly responsible for maintaining the subscription data of the mobile network and providing terminal functions such as session management, mobility management, policy management, and security authentication. The CN mainly includes all or part of the following functions: UPF, 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), the introduction of the time sensitive communication and time synchronization function (TSCTSF), and application function (AF).

[0104] As shown in Figure 1, the UE accesses the 5G network through the RAN equipment. The UE communicates with the AMF through the N1 interface (referred to as N1); the RAN communicates with the AMF through the N2 interface (referred to as N2); the RAN communicates with the UPF through the N3 interface (referred to as N3); the SMF communicates with the UPF through the N4 interface (referred to as N4), and the UPF accesses the data network (DN) through the N6 interface (referred to as N6). In addition, the control plane functions such as AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR or AF shown in Figure 1 interact using service-based interfaces. For example, the service interface provided by AUSF to the outside world is Nausf; the service interface provided by AMF to the outside world is Namf; the service interface provided by SMF to the outside world is Nsmf; the service interface provided by NSSF to the outside world is Nnssf; the service interface provided by NEF to the outside world is Nnef; the service interface provided by NRF to the outside world is Nnrf; the service interface provided by PCF to the outside world is Npcf; the service interface provided by UDM to the outside world is Nudm; the service interface provided by UDR to the outside world is Nudr; the service interface provided by TSCTSF to the outside world is Ntsctsf; and the service interface provided by AF to the outside world is Naf.

[0105] The access network device may be a device with wireless transceiver functions, or may be a chip or chip system provided in the device, located in the access network (AN) of the communication system, and used to provide access services to the terminal. For example, the access network device may be referred to as a radio access network device (RAN), and may specifically be an access network device of the next generation mobile communication system, such as 6G, such as a 6G base station. Alternatively, in the next generation mobile communication system, the access network device may also have other naming methods, all of which are covered within the scope of protection of the embodiments of this application, and this application does not impose any limitation on this. Alternatively, the access network device may 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 base station in 5G, or a network node constituting a gNB, a transmission and reception point (TRP or 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), a radio unit (RU), an RSU with base station functions, a wired access gateway, or a 5G core network element. Alternatively, the access network device may include an access point (AP) in a wireless fidelity (WiFi) system, a wireless relay node, a wireless backhaul node, various types of macro base stations, micro base stations (also known as small cells), relay stations, access points, wearable devices, vehicle-mounted devices, and the like.

[0106] Among them, the CU and DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU) or a remote radio head (RRH). It can be understood that the network device can be a CU node, a DU node, or a device including a CU node and a DU node. In addition, the CU can be divided into a network device in the access network RAN, or the CU can be divided into a network device in the core network CN, and there is no limitation here.

[0107] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (Open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, this application uses CU, CU-CP, CU-UP, DU and RU as examples for description. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0108] In the embodiments of the present application, the form of the network device is not limited. The device used to implement the function of the network device can be a network device; it can also be a device that can support the network device to implement the function, such as a chip system. The device can be installed in the network device or used in conjunction with the network device.

[0109] UPF is mainly responsible for user data processing (forwarding, receiving, billing, etc.). For example, UPF can receive user data from the data network (DN) and forward the user data to the terminal through the access network equipment. UPF can also receive user data from the terminal through the access network equipment and forward the user data to the DN. DN refers to the operator network that provides data transmission services to users. For example, the Internet Protocol (IP) Multimedia Service (IMS), the Internet, etc. DN can be an operator's external network or a network controlled by the operator, used to provide business services to the terminal. In the protocol data unit (PDU) session, the UPF directly connected to the DN through N6 is also called the protocol data unit session anchor (PSA).

[0110] AUSF is mainly used to perform terminal security authentication.

[0111] AMF is mainly used for mobility management in mobile networks, such as user location update, user network registration, and user handover.

[0112] The SMF is primarily used for session management in mobile networks, such as session establishment, modification, and release. Specific functions include allocating Internet Protocol (IP) addresses to users and selecting the UPF that provides packet forwarding capabilities.

[0113] PCF primarily supports providing a unified policy framework to control network behavior, providing policy rules to the control layer network functions, and is responsible for obtaining user subscription information related to policy decisions. PCF can provide policies to AMF and SMF, such as quality of service (QoS) policies and slice selection policies.

[0114] NSSF is mainly used to select network slices for terminals.

[0115] NEF is mainly used to support the opening of capabilities and events.

[0116] UDM is mainly used to store user data, such as contract data, authentication / authorization data, etc.

[0117] UDR is mainly used to store structured data, including contract data and policy data, externally exposed structured data, and application-related data.

[0118] The main functions of TSCTSF are to associate the time synchronization service request of NF consumers with the AF session of PCF; detect the availability of 5GS bridge information of Ethernet and IP type PDU sessions reported by PCF, etc.

[0119] AF mainly supports interaction with CN to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side.

[0120] It can be understood that the functions mentioned in the embodiments of the present application can also be expressed as functional network elements or functional entities. For example, UPF can be expressed as UPF network element, AMF can be expressed as AMF network element, SMF can be expressed as SMF network element, PCF can be expressed as PCF network element, and so on, without limitation.

[0121] 2. Clock synchronization:

[0122] The clock synchronization capability of a 5G network is a network function that can be exposed to external devices. For example, it can serve as the master clock for the entire system and synchronize the clocks of other devices. Section 5.27.1.8 of Release 17 defines that the clock synchronization exposure capability of a 5G network can be activated and deactivated by the AF.

[0123] Figure 2 is a schematic diagram of the TSN architecture. As shown in Figure 2, the 5G system serves as a TSN bridge in TSN, where:

[0124] The time sensitive network grandmaster (TSN GM) is the clock source in the TSN network.

[0125] The NW-TT is the interface on the UPF network element side and the inbound interface of the bridge. It is responsible for importing TSN data into the 5G network. Because it receives time synchronization messages from the TSN network, it serves as a slave interface. The NW-TT needs to measure latency and frequency deviation with the TSN bridge. The NW-TT adds an inbound timestamp (Tse) to the synchronization (sync) messages.

[0126] DS-TT is the UE-side interface, also known as the bridge's outbound interface. It is responsible for inputting TSN data into the TSN network. Because it needs to send time synchronization messages to the TSN network, it serves as the master interface. DS-TT collaborates with the end station to measure latency and frequency deviation. DS-TT adds an egress timestamp (Tsi) to the synchronization messages received from the UE and then calculates the internal forwarding delay.

[0127] The 5G network host (5G GM) is the NR clock source, which is generally provided by the global positioning system (GPS).

[0128] 5G time domain: Because the 5GS is a precision time protocol (PTP) node, the 5G clock domain must operate within the same clock domain. The internal forwarding delay (residence time, Tse-Tsi) calculation between the NW-TT and DS-TT must be in the same clock domain and have the same frequency.

[0129] TSN working domain: This clock domain can be a factory-defined clock source and does not necessarily have to be consistent with GPS or coordinated universal time (UTC).

[0130] As shown in Figure 2, the basic idea of ​​the clock synchronization solution is:

[0131] 5G system devices, such as UEs and UPFs, first synchronize to the 5G system clock. For example, the gNB broadcasts the synchronization to the UE via air interface frame alignment, enabling the UE to calculate accurate local 5G clock information. The UPF uses the 5G clock information provided by the gNB or the transport network to accurately calculate the local 5G clock information.

[0132] Afterwards, the TSN clock information is carried in the gPTP message and passed to the DS-TT (which can be a function integrated in the UE) via the NW-TT (a function of the UPF network element). The UE calculates the deviation between the 5G clock and the TSN clock based on the timestamp information in the gPTP message, and ultimately obtains accurate TSN clock information. For example, the TSN GM sends a clock synchronization message to each TSN node, such as a TSN bridge or end node. Because the 5G system is also a TSN bridge, it will also receive clock synchronization messages. For example, the NW-TT is the first module in the 5G system to receive the TSN clock information (carried in the gPTP message). The NW-TT will add the timestamp of receipt of the message to the gPTP message and encapsulate the gPTP message in the general packet radio service (GPRS) tunneling protocol (GTP) message of the 5G user plane. The UPF network element co-located with the NW-TT sends the encapsulated message to the UE as a regular user plane message, and further sends it to the DS-TT. In this way, the TSN clock information in the gPTP message can be restored and the local TSN clock information can be calculated.

[0133] Currently, base stations (or RAN equipment) can provide reference time information to UEs via broadcast or unicast. There are two methods for base station propagation delay compensation (PDC): a timing advance (TA)-based UE clock synchronization solution and a round trip time (RTT)-based UE clock synchronization solution. These two methods are described below.

[0134] TA-based:

[0135] As shown in Figure 3, the RAN device synchronizes its clock with the UE through TA-based synchronization as follows:

[0136] S301 , the RAN device broadcasts a system information block (SIB) 9 .

[0137] SIB9 may include the time of the RAN device, which may be the time the RAN device obtains from the network, or the time when the RAN device broadcasts SIB9. Accordingly, the UE may receive SIB9 broadcast by the RAN device in a non-connected state (e.g., inactive or idle state).

[0138] S302: The UE sends an uplink message to the RAN device. The RAN device receives the uplink message from the UE.

[0139] The UE can respond to SIB9 by switching from a non-connected state to a connected state to send an uplink message to the RAN device. The RAN device can determine the air interface delay (TA) between the RAN device and the UE by analyzing the uplink message, such as the preamble in the uplink message.

[0140] S303: The RAN device sends a downlink message to the UE. The UE receives the downlink message from the RAN device.

[0141] The downlink message may carry the TA determined in S302. In this way, the UE achieves time synchronization with the RAN device based on the TA and the time of the RAN device. Alternatively, the RAN device may determine the exact time at which the UE receives the downlink message based on the time at which the RAN device will send the downlink message and the TA, and carry the exact time at which the UE receives the downlink message in the downlink message, thereby achieving time synchronization between the UE and the RAN device.

[0142] It can be seen that TA-based requires the UE to perform correction in the RAN clock domain, that is, the same source is required.

[0143] RTT-based:

[0144] As shown in Figure 4, the process of RAN equipment synchronizing with the UE clock through RTT-based synchronization can refer to the steps in 802.1AS, where the RAN is the initiator and the UE is the responder. The details are as follows:

[0145] S401: An initiator sends a request to a responder, and the responder receives the request from the initiator.

[0146] The request in S401 carries the time when the initiating entity sends the request, which is recorded as t1. Correspondingly, the responding entity can determine the time when the request in S401 is received, which is recorded as t2.

[0147] S402: The responding entity sends a response to the initiating entity, and the initiating entity receives the response from the responding entity.

[0148] Among them, the response of S402 is used to respond to the request of S401. The response carries the time when the responding entity sent the response, recorded as t3. Accordingly, the requesting entity can determine the time when the response was received, recorded as t4. In this way, the requesting entity can determine the air interface transmission delay between the initiating entity and the responding entity, such as the air interface transmission delay is [(t2-t1)+(t4-t3)] / 2. And / or, the requesting entity can determine the time difference (offset) between the initiating entity and the responding entity, such as the time difference is [(t2-t1)-(t4-t3)] / 2.

[0149] S403: The initiating entity sends the time difference to the responding entity.

[0150] As can be seen, the time difference calculated based on RTT is the clock deviation between the two clock sources. For example, if the time of the initiating entity is 5:00 and the time of the responding entity is 5:05, then the time difference is 5 minutes, and the same source is not required.

[0151] In addition to the two methods mentioned above, the delay or clock deviation between the access network device and the terminal can also be calculated by other methods, which are not limited in the embodiments of the present application.

[0152] As shown above, 5GS synchronizes two external clock UEs via gPTP clock synchronization. In industrial scenarios, this means that each industrial device must be equipped with a DS-TT module, which is relatively costly. In dual-end wireless scenarios, the clock synchronization accuracy requirements from the UPF network element to the DS-TT are even more stringent, resulting in limited practical applications and high application costs. Furthermore, current clock synchronization solutions lack a solution for group synchronization.

[0153] In response to the above technical problems, the embodiments of the present application propose the following technical solutions.

[0154] The technical solution in this application will be described below with reference to the accompanying drawings.

[0155] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as wireless network (Wi-Fi) systems, vehicle to everything (V2X) communication systems, device-to-device (D2D) communication systems, Internet of Vehicles communication systems, fourth-generation (4G) mobile communication systems, such as long-term evolution (LTE) systems, world-wide interoperability for microwave access (WiMAX) communication systems, fifth-generation (5G) systems, such as new radio (NR) systems, and future communication systems.

[0156] In the embodiment of the present application, "indication" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a certain information (such as the first indication information, the second indication information, or the third indication information below) is called 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, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein the other information and the information to be indicated have an association relationship. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, the indication of specific information can be achieved by means of the arrangement order of each information agreed in advance (such as specified in the protocol), thereby reducing the indication overhead to a certain extent. At the same time, the common parts of each information can be identified and indicated uniformly to reduce the indication overhead caused by indicating the same information separately.

[0157] In addition, the specific indication method can also be various existing indication methods, such as but not limited to the above-mentioned indication methods and various combinations thereof. The specific details of the various indication methods can be referred to the prior art and will not be repeated herein. As can be seen from the above, for example, when it is necessary to indicate multiple information of the same type, there may be a situation where the indication methods for different information are different. In the specific implementation process, the required indication method can be selected according to specific needs. The embodiment of the present application does not limit the selected indication method. In this way, the indication method involved in the embodiment of the present application should be understood to cover various methods that can enable the party to be indicated to obtain the information to be indicated.

[0158] It should be understood that the information to be indicated can be sent as a whole or divided into multiple sub-information and sent separately, and the sending period and / or sending time of these sub-information can be the same or different. The specific sending method is not limited in the embodiments of this application. The sending period and / or sending time of these sub-information can be predefined, for example, predefined according to a protocol, or can be configured by the transmitting device by sending configuration information to the receiving device.

[0159] "Pre-definition" or "pre-configuration" can be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in the device, and the embodiments of the present application do not limit the specific implementation method. Among them, "saving" can mean saving in one or more memories. The one or more memories can be set separately or integrated in an encoder or decoder, a processor, or a communication device. The one or more memories can also be partially set separately and partially integrated in a decoder, a processor, or a communication device. The type of memory can be any form of storage medium, and the embodiments of the present application do not limit this.

[0160] The "protocol" involved in the embodiments of the present application may refer to a protocol family in the communication field, a standard protocol with a similar protocol family frame structure, or a related protocol used in future communication systems. The embodiments of the present application do not make specific limitations on this.

[0161] In the embodiments of the present application, descriptions such as "when...", "in the case of...", "if" and "if" all mean that the device will perform corresponding processing under certain objective circumstances. It does not limit the time, nor does it require the device to perform judgment actions when implemented, nor does it mean that there are other limitations.

[0162] In the description of the embodiments of the present application, unless otherwise specified, " / " indicates that the objects associated with each other are in an "or" relationship. For example, A / B can represent A or B. "And / or" in the embodiments of the present application is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, in the description of the embodiments of the present application, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish between identical or similar items with basically the same functions and effects. Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit differences. At the same time, in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or design. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0163] The network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Ordinary technicians in this field will know that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0164] For ease of understanding, the relevant concepts involved in the embodiments of this application are first introduced.

[0165] 1) Group: A group can be a combination of members with the same attributes. For example, it can be a combination of members that can enjoy the consistent services provided by the application network element, or it can be a combination of all terminal devices located in a specified area. The group can be a 5G local area network (5G LAN), also known as a 5G virtual network (5G VN), or other types of groups, such as temporary groups or dynamic groups (groups that require dynamic management of group members), without specific limitation.

[0166] 2) Group identification: The group identification can be the internal group identification of the group (or internal group ID), or it can also be the identification of the group (or external group ID). Among them, the internal group ID can refer to the core network (such as 5GC) or the network element inside the operator network (such as SMF network element, AMF network element, UDM network element, PCF network element, NEF network element, etc.) that can be identified and uniquely represents the group. The internal group ID can be DNN, S-NSSAI, or a combination of DNN and S-NSSAI, or represented by other information. The external group ID can refer to an identifier that is identified and uniquely represents the group outside the core network or operator network, for example, within the AF range. The external group ID can be a string, a random number, etc., or represented by other information. It can be understood that the network element inside the core network or operator network may not be able to recognize the external group ID. The external group ID and the internal group ID can have a mapping relationship.

[0167] 3) Group members: The members of a group can be a master clock member and other members other than the master clock member, also known as non-master clock members. For example, a group includes three members: UE#1, UE#2, and UE#3. UE#1 is the master clock member, or master clock UE, and UE#2 and UE#3 are other members of the group other than the master clock member, also known as non-master clock UEs. The time of the master clock member can be used as a reference, and the non-master clock members need to synchronize with the master clock member time. That is, UE#2 and UE#3 need to synchronize with UE#1 time. For example, if UE#1's local time is currently 9:01 and UE#2 and UE#3's local time is currently 9:03, then UE#2 and UE#3 need to adjust their local time from 9:03 to 9:01 to achieve time synchronization with UE#1. This process is also called group timing, or group clock synchronization. For details, please refer to the relevant introduction below and will not be repeated here.

[0168] 4) Identification of each member in the group: The identification of each member in the group may be the internal identification (or internal ID) of the member, or it may be the external identification (or external ID) of the member. Among them, the internal ID of each member may refer to an identification that can be identified by the network element inside the core network or the operator network, and uniquely represents the member in the group. The internal ID of each member may be a user permanent identifier (SUPI). The external ID of each member may refer to an identification that can be identified and uniquely represents a group member in the group outside the core network or the operator network, for example, within the AF range. The internal ID of each member may be an IP address, a generic public subscription identifier (GPSI), etc. It can be understood that the network element inside the core network or the operator network may not be able to recognize the external ID of the member. The external ID of each member may have a corresponding relationship with the internal ID of the member.

[0169] It can be understood that the group identifier and the identifier of each member in the group can have a mapping relationship or an inclusion relationship, which is used to indicate which UEs are members of the group, such as the group identifier {UE#1 identifier, UE#2 identifier, UE#3 identifier}, indicating that UE#1, UE#2 and UE#3 are members of the group.

[0170] 5) Identification of the master clock member: The identification of the master clock member can be used to indicate which member of all members of the group is the master clock member. The identification of the master clock member can be an explicit indication element, such as a newly defined element, which contains the identification of which member, indicating that the member is the master clock member, such as the master clock member {UE#1}. Alternatively, the identification of the master clock member can also be an implicit indication element, such as the default that the xth member (such as the first member) in the above mapping relationship is the master clock member, that is, UE#1. Alternatively, the identification of the master clock member can also be implemented in other ways, which are not limited. It can be understood that the embodiment of the present application does not limit which member in the group serves as the master clock member.

[0171] 6) Time synchronization error budget: The time synchronization error budget can be used to indicate the error requirement that the RAN device must meet when providing group timing (or providing group clock synchronization services). That is, the clock synchronization error of the RAN device when providing group clock synchronization services must be within the error limit of the clock synchronization error budget.

[0172] To facilitate understanding of the embodiments of the present application, a communication system applicable to the embodiments of the present application is first described in detail using the communication system shown in Figure 5 as an example. For example, Figure 5 is a schematic diagram of the architecture of a communication system applicable to the communication method provided in the embodiments of the present application.

[0173] As shown in Figure 5, this communication system can be applied to the aforementioned 5GS and primarily includes: application functions (e.g., AF), time synchronization network elements (e.g., TSCTSF network elements), and access network equipment (e.g., RAN equipment). The application functions can send group information to the network, such as the time synchronization network element. Based on the group information, the time synchronization network element can trigger the access network equipment to provide clock synchronization services for the group, synchronizing the clocks of group members. For example, all group members, excluding the master clock member, synchronize their clocks with the master clock member.

[0174] The following will be combined with Figures 6 to 9 to specifically describe the interaction process between each network element / device in the above communication system through a method embodiment. The communication method provided in the embodiment of the present application can be applied to the above communication system and specifically applied to various scenarios mentioned in the above communication system, which will be described in detail below.

[0175] Scenario 1:

[0176] Figure 6 is a flow chart of the communication method provided in an embodiment of the present application. The communication method is applicable to the above-mentioned communication system, and mainly involves the interaction between UE, RAN equipment, AMF network element, PCF network element, TSCTSF network element, AF, etc.

[0177] In Scenario 1, the AF can initiate a group clock synchronization creation request message to the TSCTSF network element. The TSCTSF network element can respond to the AF's request, triggering the PCF network element to create an AM policy and provide it to the AMF network element. The AMF network element, based on the AM policy, enables the RAN equipment to provide clock synchronization services for the group. For example, the RAN equipment can determine the time difference between itself and the master clock member in the group and use this time difference to complete the timing of non-master clock members in the group, enabling non-master clock members to synchronize with the master clock member.

[0178] As shown in Figure 6, the process of the communication method is as follows:

[0179] S601: The AF sends a parameter provisioning creation request (Nnef_ParameterProvision_Create Request) message #1 to the NEF network element. The NEF network element receives the parameter provisioning creation request message #1 from the AF.

[0180] The parameter configuration creation request message #1 is used to provide one or more parameters (such as a group) to be created to the NEF network element. For example, the parameter configuration creation request message #1 may include group information, which may include at least one of the following: clock synchronization error, group identifier, identifier of each member in the group, and identifier of the master clock member.

[0181] After receiving the parameter configuration creation request message #1 from the AF, the NEF network element can determine whether the AF is authorized to provide parameters, such as whether the AF has the authority to create a group. If the AF has the authority to create a group, the NEF network element executes S602. Otherwise, the process fails.

[0182] It can be understood that the parameter configuration creation request message #1 is an example, and it can also be replaced by a parameter configuration update / deletion request message, without limitation.

[0183] S602: The NEF network element sends a Nudm_Parameter Provision_Create Request message #2 to the UDM network element. The UDM network element receives the Nudm_Parameter Provision_Create Request message #2 from the NEF network element.

[0184] Parameter configuration creation request message #2 carries the parameters in parameter configuration creation request message #1. Parameter configuration creation request message #2 and parameter configuration creation request message #1 can be the same message, or different messages, and there is no limitation on this. After the UDM network element receives the parameter configuration creation request message #2 from the NEF network element, the UDM network element can optionally determine whether the UDM network element accepts the group parameters provided by the AF. If the UDM network element accepts the parameters of the AF group, the UDM network element configures the corresponding parameters. For example, the UDM network element creates a group based on the parameter configuration creation request message #2, such as saving the group information in the parameter configuration creation request message #2 as the contract information of the group, or saving it to the contract information of the group, otherwise, the process fails.

[0185] Optionally, if the group identifier is an external group ID, the UDM network element may also map the external group ID to an internal group ID. Similarly, if the identifier of a member in the group is an external ID, the UDM network element may also map the external ID to an internal ID.

[0186] It can be understood that the parameter configuration creation request message #2 is an example and can also be replaced by a parameter configuration update / deletion request message, without limitation.

[0187] S603: The UDM network element sends a Nudm_Parameter Provision_Create Response message #2 to the NEF network element. The NEF network element receives the Nudm_Parameter Provision_Create Response message #2 from the UDM network element.

[0188] Parameter Configuration Create Response Message #2 is used to respond to Parameter Configuration Create Request Message #1. If the process fails, the reason value in Parameter Configuration Create Response Message #2 indicates the failure reason, such as the UDM network element does not accept the AF creation group.

[0189] It can be understood that the parameter configuration creation response message #2 is an example, which can also be replaced by a parameter configuration update / deletion response message, without limitation.

[0190] S604: The NEF network element sends a Nudm_ParameterProvision_Create Response message #1 to the AF. The AF receives the Nudm_ParameterProvision_Create Response message #1 from the NEF network element.

[0191] Parameter Configuration Create Response Message #1 is used to respond to Parameter Configuration Create Request Message #1. If the process fails, the reason value in Parameter Configuration Create Response Message #1 indicates the failure reason, such as the AF is not granted the permission to create a group.

[0192] It can be understood that the parameter configuration creation response message #1 is an example, which can also be replaced by a parameter configuration update / deletion response message, without limitation.

[0193] If the AF is a trusted third-party application service, the AF may directly initiate a group parameter configuration creation request to the UDM network element. After receiving the request, the UDM network element performs the same operation as S602 and initiates a response to the AF accordingly.

[0194] S605: The AF sends a group access stratum time synchronization creation request (Nnef_ASTI_Create Request) message #1 to the NEF network element. The NEF network element receives the group access stratum time synchronization creation request message #1 from the AF.

[0195] The group access stratum clock synchronization creation request message #1, i.e., initiating the access stratum time synchronization service, may include the aforementioned group information to request the group's clock synchronization service.

[0196] It is understood that if S601-S604 have been executed in advance, the group information in the group access layer clock synchronization creation request message #1 may also include only the group identifier. In addition, the group access layer clock synchronization creation request message #1 is an example and can be replaced by any other possible message without limitation.

[0197] In an embodiment of the present application, optionally, after the NEF network element receives the group access layer clock synchronization creation request message #1 from the AF, the NEF network element may authenticate the AF, such as determining whether the AF is authorized to request the group clock synchronization service. If the AF is authorized to request the group clock synchronization service, the NEF network element executes S606; otherwise, the process fails.

[0198] S606: The NEF network element sends a group access layer clock synchronization creation request (Ntsctsf_ASTI_Create Request) message #2 to the TSCTSF network element. The TSCTSF network element receives the group access layer clock synchronization creation request message #2 from the NEF network element.

[0199] Group Access Layer Clock Synchronization Creation Request Message #2 may carry the same group information as Group Access Layer Clock Synchronization Creation Request Message #1. That is, the NEF network element may encapsulate the group information in Group Access Layer Clock Synchronization Creation Request Message #1 into Group Access Layer Clock Synchronization Creation Request Message #2 and then send Group Access Layer Clock Synchronization Creation Request Message #2 to the TSCTSF network element. Alternatively, Group Access Layer Clock Synchronization Creation Request Message #2 and Group Access Layer Clock Synchronization Creation Request Message #1 may be the same message. That is, the NEF network element forwards Group Access Layer Clock Synchronization Creation Request Message #1 to the TSCTSF network element.

[0200] It is understood that if the group identifier in the group information is an external group ID, the NEF network element may map the external group ID to an internal group ID. Similarly, if the member identifier in the group information is an external ID, the NEF network element may map the external ID to an internal ID. Furthermore, Group Access Layer Clock Synchronization Creation Request Message #2 is an example and may also be replaced by a Timing Update / Delete Request message, without limitation.

[0201] S607: Optionally, the TSCTSF network element obtains the subscription data of the group from the UDM network element.

[0202] S607 is an optional step. If S601-S604 have been executed in advance, the TSCTSF network element can subscribe to the group data from the UDM network element based on the group identifier in the Group Access Layer Clock Synchronization Creation Request Message #2, to obtain the group information in the group's subscription data, namely, at least one of the following items: clock synchronization error, group identifier, identifier of each group member, and identifier of the master clock member, and then execute S608. Of course, if S601-S604 have not been executed, the TSCTSF network element can directly execute S608 after receiving the Group Access Layer Clock Synchronization Creation Request Message #2.

[0203] S608: The TSCTSF network element sends a PCF access and mobility (AM) policy authorization creation request (Npcf_AM_Policy Authorization_Create Request) message to the PCF network element. The PCF network element receives the PCF AM policy authorization creation request message from the TSCTSF network element.

[0204] The PCF AM Policy Authorization Create Request message can be used to request the PCF network element to create an AM policy. In addition, the PCF AM Policy Authorization Create Request message can also carry group information to indicate that the parameters required to create the AM policy may include the group information.

[0205] S609: The PCF network element creates an AM policy.

[0206] The AM policy may include the aforementioned group information. The PCF network element can authorize the creation of an AM policy based on the PCF AM policy creation request message, for example by encapsulating the group information as part of the AM policy. The PCF network element can also provide the created AM policy to the AMF network element, which then issues the corresponding configuration to the RAN device based on the AM policy, thereby providing group clock synchronization services.

[0207] S610: The PCF network element sends a PCF AM policy authorization creation response (Npcf_AM_Policy Authorization_Create Response) message to the TSCTSF network element. The TSCTSF network element receives the PCF AM policy authorization creation response message from the PCF network element.

[0208] The PCF AM policy authorization creation response message can be used to respond to the above-mentioned PCF AM policy authorization creation request message, indicating that the AM policy was successfully created.

[0209] S611, the TSCTSF network element sends a group access layer clock synchronization response (Ntsctsf_ASTI_Create_Response) message #2 to the NEF network element. The NEF network element receives the group access layer clock synchronization creation response message #2 from the TSCTSF network element.

[0210] S612: The NEF network element sends a group access layer clock synchronization response (Nnef_ASTI_Create_Response) message #1 to the AF. The AF receives the group access layer clock synchronization creation response message #1 from the NEF network element.

[0211] Among them, the group access layer clock synchronization creation response message #2 can be used to respond to the above-mentioned group access layer clock synchronization creation request message #2, and the group access layer clock synchronization creation response message #1 can be used to respond to the above-mentioned group access layer clock synchronization creation request message #1, indicating that the network accepts the group's request for clock synchronization service.

[0212] S613: The AMF network element sends an N2 message to the RAN device.

[0213] There may be one or more RAN devices, such as RAN device #1 and RAN device #2. The N2 message may include the aforementioned group information. For example, the AMF network element may determine, through mobility management, that group members reside on one or more RAN devices, such as UE #1 and UE #2 residing on RAN device #1, and UE #3 residing on RAN device #2. The AMF network element sends N2 messages carrying the group information to RAN #1 and RAN #2, respectively.

[0214] It is understood that if the AMF network element is enhanced, such as being able to identify group information, it can pre-process the group information. For example, the AMF network element can include information required by RAN device #1 in the group information, such as the group identifier {UE#1's identifier, UE#2's identifier}, the master clock member {UE#1}, and the clock synchronization error, in the N2 message sent to RAN device #1. Similarly, the AMF network element can also include information required by RAN device #2 in the group information, such as the group identifier {UE#3's identifier} and the clock synchronization error, in the N2 message sent to RAN device #2. This avoids transmission redundancy.

[0215] It can also be understood that the execution order between S613 and S610 - S612 is not limited.

[0216] S614, RAN device #1 obtains time difference #1.

[0217] Time difference #1 can be the time difference between UE#1 and RAN device #1. In response to receiving the N2 message (such as the first message), RAN device #1 can determine that UE#1 is a member of the master clock. In this way, RAN device #1 can obtain time difference #1. Further, time difference #1 can be obtained based on the clock synchronization error. Optionally, an RTT-based process with UE#1 can be executed to obtain time difference #1. Among them, the specific implementation of RTT-based can refer to the relevant introduction of Figure 4 above, which will not be repeated here. If the current time of RAN device #1 is 9:05 and the current time of UE#1 is 9:04, then the time difference #1 between UE#1 and RAN device #1 is -1 minute, then RAN device #1 can determine that the current time of UE#1 is accelerated by 1 minute based on its own current time.

[0218] Optionally, RAN device #1 may also create a timing context for UE #1, such as one containing at least one of the following: a group identifier, a member identifier (e.g., UE #1's identifier), or a master clock member identifier, to indicate that UE #1 is the master clock member of the group. Optionally, the timing context for UE #1 may also include clock synchronization error and time difference #1.

[0219] S615 , RAN device #1 synchronizes the clocks of UE #2 and UE #1.

[0220] There are multiple ways to synchronize the clocks of UE#2 and UE#1, which are introduced below.

[0221] 1) RAN device #1 completes clock synchronization by sending time difference #1:

[0222] In one possible implementation, when RAN device #1 and UE #2 have completed clock synchronization, RAN device #1 sends a unicast message (e.g., a second message), such as an RRC message, a DCI message, or a MAC_CE message, to UE #2. The unicast message may carry time difference #1. That is, when clock synchronization has been completed (e.g., UE #2 receives reference time information from RAN device #1 via unicast or broadcast, or optionally further completes PDC clock synchronization via TA-based, RTT-based, or other methods), RAN device #1 only needs to provide time difference #1 to achieve clock synchronization between UE #2 and UE #1, with relatively low communication overhead. For example, if RAN device #1 sends the unicast message at 9:07, UE #2 is synchronized with RAN device #1, i.e., UE #2 is also at 9:07. Time difference #1 is -1 minute. After receiving the unicast message, UE #2 adjusts its own time forward by 1 minute to achieve clock synchronization with UE #1.

[0223] In another possible implementation, when RAN device #1 and UE #2 have completed clock synchronization, RAN device #1 sends a broadcast message (e.g., the third message) containing time difference #1, which is used to synchronize the clocks of UE #2 and UE #1. Optionally, time difference #1 in the broadcast message can be encrypted ciphertext, and UE #2 can decrypt the ciphertext to ensure communication security for clock synchronization. For example, RAN device #1 sends a unicast message carrying a key to UE #2, and UE #2 can use the key to decrypt the ciphertext to obtain time difference #1.

[0224] 2) RAN device #1 completes clock synchronization by sending time difference #1 and RAN device #1's reference time information:

[0225] RAN device #1 sends time difference #1 and its reference time information to UE #2, and / or RAN device #1 broadcasts time difference #1 and its reference time information. The time indicated by RAN device #1's reference time information is the time at which RAN device #1 sent its reference time information. For example, if RAN device #1 sent its reference time information at 9:07, then the time indicated by RAN device #1's reference time information is 9:07. Accordingly, UE #2 synchronizes its clock with UE #1 by adding time difference #1 to the time indicated by its reference time information. For example, if time difference #1 is -1 minute, the sum is 9:06. If UE #2's own time is 9:10, UE #2 adjusts its own time to UE #1's time, i.e., 9:06, thereby achieving clock synchronization with UE #1.

[0226] It is understandable that time difference #1 and the reference time information of RAN device #1 can be carried in the same message, such as the same unicast or broadcast message, or can be carried in different messages. For example, time difference #1 and the reference time information of RAN device #1 are carried in different unicast or broadcast messages. In this case, the unicast or broadcast message containing time difference #1 and the unicast or broadcast message containing the reference time information of RAN device #1 can be sent at different times. For example, RAN device #1 first sends a unicast message carrying time difference #1 and then sends a unicast message carrying the reference time information of RAN device #1. For example, RAN device #1 sends a broadcast message carrying time difference #1 at a first period and sends a broadcast message carrying the reference time information of RAN device #1 at a first period, and the first period is different from the second period. For another example, time difference #1 is carried in a unicast message and the reference time information of RAN device #1 is carried in a broadcast message, or vice versa.

[0227] Optionally, without considering the propagation delay between RAN device #1 and UE #2, the time when RAN device #1 sends the reference time information of RAN device #1 can be understood as the time when UE #2 receives the reference time information of RAN device #1. If the propagation delay between RAN device #1 and UE #2 is considered, RAN device #1 can also send the value of PDC to UE #2. Accordingly, UE #2 can achieve clock synchronization with UE #1 by adding time difference #1, the time when RAN device #1 sends the reference time information of RAN device #1, and the value of PDC. For example, the time when RAN device #1 sends the reference time information of RAN device #1 is 9:06, the time difference #1 is -1 minute, and the value of PDC is 1 minute. The sum of the three is 9:06, thereby achieving clock synchronization with UE #1.

[0228] Optionally, if time difference #1 and / or the reference time information of RAN device #1 are included in a broadcast message, the time difference #1 and / or the reference time information of RAN device #1 may be encrypted ciphertext, and UE #2 may be able to decrypt the ciphertext to ensure communication security for clock synchronization. For example, RAN device #1 may send a unicast message carrying a key to UE #2, and UE #2 may use the key to decrypt the ciphertext and obtain the time difference #1 and / or the reference time information of RAN device #1.

[0229] It can also be understood that, when sending the PDC value, the PDC value and the above-mentioned time difference #1 and the reference time information of the RAN device #1 are carried in the same message, or they can be carried in different messages respectively. For example, the reference time information of the RAN device #1 can be sent through one message (unicast / broadcast) first, and then the time difference #1 and / or PDC value can be sent through another message. There can also be other implementation methods, which are not limited to this.

[0230] 3) RAN device #1 completes clock synchronization by sending UE #1's reference time information:

[0231] In one possible implementation, RAN device #1 sends a unicast message (e.g., a second message) to UE #2. The unicast message may carry UE #1's reference time information. UE #1's reference time information may be determined by RAN device #1 based on time difference #1 and RAN device #1's reference time information, so that the time indicated by RAN device #1's reference time information may be the time synchronized with UE #1. For example, the time indicated by RAN device #1's reference time information may be the time when RAN device #1 sent UE #1's reference time information. RAN device #1 can determine the time synchronized with UE #1 by adding the time difference #1 to the time when RAN device #1 sent UE #1's reference time information. In other words, RAN device #1 can independently determine the time synchronized with UE #1 and send it to UE #2, eliminating the need for UE #2 to determine the time independently. This reduces UE #2's overhead and improves energy efficiency. For example, if RAN device #1 sends UE #1's reference time information at 9:07 and time difference #1 is 1 minute, RAN device #1 determines the time synchronized with UE #1 as 9:08 by adding the time difference #1. RAN device #1 sends 9:08 to UE #2. UE #2 then adjusts its own time to the time information carried in the message sent by RAN device #1, achieving clock synchronization with UE #1.

[0232] In another possible implementation, RAN device #1 sends a broadcast message (such as the third message) that carries UE #1's reference time information. Optionally, the reference time information of UE #1 in the broadcast message can be encrypted ciphertext, and UE #2 can decrypt the ciphertext to ensure communication security for clock synchronization. For example, RAN device #1 sends a unicast message carrying a key to UE #2. UE #2 can use the key to decrypt the ciphertext and obtain UE #1's reference time information.

[0233] It will be appreciated that, similar to the above, if the PDC values ​​of RAN device #1 and UE #2 are considered, RAN device #1 can also send the PDC value to UE #2. Alternatively, RAN device #1 can take the PDC value into account when determining UE #1's reference time information. For example, RAN device #1 calculates UE #1's reference time information by adding the time when RAN device #1 sends UE #1's reference time information, time difference #1, and the PDC value.

[0234] Optionally, RAN device #1 may also create a timing context for UE #2, such as one that includes at least one of the following: a group identifier or a member identifier, such as UE #2's identifier, to indicate that UE #2 is a non-master clock member of the group. Optionally, the timing context for UE #2 may also include clock synchronization error, time difference #1, and the like.

[0235] S616, optionally, RAN device #1 saves the time difference #1 to the TSC TSF network element, the UDM network element, or the PCF network element.

[0236] RAN device #1 can send time difference #1 to the TSCTSF network element, UDM network element, or PCF network element. Optionally, it can also send the group identifier to the TSCTSF network element, UDM network element, or PCF network element. The TSCTSF network element, UDM network element, or PCF network element can save time difference #1 or, alternatively, store time difference #1 as group-associated information based on the group identifier for subsequent use. For example, the UDM network element can save time difference #1 in the group's subscription information. Alternatively, the TSCTSF network element or PCF network element can locally associate time difference #1 with the aforementioned group information and store it.

[0237] It is understandable that, considering the real-time nature, the network side may not save the time difference #1.

[0238] S617, optionally, RAN device #1 sends time difference #1 to RAN device #2.

[0239] If an Xn interface exists between RAN device #1 and RAN device #2, RAN device #1 can send time difference #1 directly to RAN device #2 without forwarding it through the AMF network element. Otherwise, RAN device #1 can first send time difference #1 to the AMF network element, which then forwards it to RAN device #2. In this case, time difference #1 can be carried in any possible message or information, such as existing information or newly defined information or information, without limitation.

[0240] It can be understood that both RAN device #2 and RAN device #1 are synchronized with the 5GS time. In other words, the time of RAN device #2 and RAN device #1 can be synchronized.

[0241] S618, optionally, RAN device #2 synchronizes the clocks of UE #3 and UE #1.

[0242] The principle of RAN device #2 synchronizing the clocks of UE #3 and UE #1 is similar to the principle of RAN device #1 synchronizing the clocks of UE #2 and UE #1. Please refer to S615 above for understanding, and will not be repeated here.

[0243] Optionally, RAN device #2 may further create a timing context for UE #3, such as one containing at least one of the following: a group identifier or a member identifier, such as UE #3's identifier, to indicate that UE #3 is a non-master clock member of the group. Optionally, the timing context for UE #3 may further include clock synchronization error, time difference #1, and the like.

[0244] At this point, the network side completes the clock synchronization of the group.

[0245] S619, optionally, if UE#2 is switched to RAN device #3, RAN device #1 sends the timing context of UE#2 to RAN device #3.

[0246] The manner in which RAN device #1 sends the timing context of UE #2 is similar to the above-mentioned S617, which can be understood by reference and will not be described in detail here.

[0247] RAN device #3 can determine, based on UE#2's timing context, that UE#2 is a non-master clock member in the group, facilitating group maintenance and updates by RAN device #3. For example, in a scenario where RAN device #3 and UE#2 are performing a PDC, RAN device #3 can send the PDC value and time difference #1 in UE#2's timing context to UE#2 to ensure that UE#2 continues to synchronize with UE#1. The specific principles are similar to those in S615 above and can be understood with reference thereto. Further description is omitted. For another example, after obtaining the latest time difference, RAN device #3 can resynchronize UE#2's clock with UE#1 based on the latest time difference. For another example, in the event of a group update, such as when UE#2 leaves the group, RAN device #3 can simultaneously remove UE#2 from the group. In the scenario where RAN device #3 obtains time difference #1, the method for RAN device #3 to synchronize UE#2 with UE#1 is similar to the method in S615 used by RAN device #1 to synchronize UE#2 with UE#1, and further description is omitted.

[0248] It can be understood that both RAN device #3 and RAN device #1 are synchronized with the 5GS time, that is, the time of RAN device #3 and RAN device #1 can be synchronized.

[0249] It can also be understood that S619 is an optional step, and UE#2 may not be switched.

[0250] S620, optionally, if UE#1 is switched to RAN device #4, RAN device #1 sends the timing context of UE#1 to RAN device #4.

[0251] The manner in which RAN device #1 sends the timing context of UE #1 is similar to that in S617 above, which can be understood by reference and will not be described again here.

[0252] S621, optionally, RAN device #4 obtains time difference #2.

[0253] Time difference #2 can be the time difference between UE#1 and RAN device #4. In response to receiving the timing context from UE#1, RAN device #4 can determine that UE#1 is a member of the master clock. RAN device #4 can then obtain time difference #2 based on the clock synchronization error. Optionally, it can perform an RTT-based process with UE#1 to obtain time difference #2. The specific implementation of the RTT-based process can be found in the description of Figure 4 above and will not be further elaborated here.

[0254] S622, optionally, RAN device #4 sends time difference #2 to RAN device #1.

[0255] S623, optionally, RAN device #4 sends time difference #2 to RAN device #2.

[0256] For S622-S623, the manner in which RAN device #4 sends time difference #2 is similar to that of S617 above, which can be referred to for understanding and will not be described in detail.

[0257] S624, optionally, RAN device #1 synchronizes the clocks of UE #2 and UE #1.

[0258] It can be understood that the specific implementation principle of S624 is similar to that of the above-mentioned S615, which can be referred to for understanding and will not be repeated here.

[0259] S625 , optionally, RAN device # 2 synchronizes the clocks of UE # 3 and UE # 1 .

[0260] Among them, the implementation principle of S625 is similar to that of the above-mentioned S615, which can be understood by reference and will not be repeated here.

[0261] Optionally, RAN device #2 may also update the timing context of UE #3, such as updating time difference #1 to time difference #2.

[0262] It can be understood that S620-S625 are optional steps, and UE#1 may not be switched.

[0263] It can also be understood that the execution of S619 and S620 - S625 may be in an “or” relationship.

[0264] S626, optionally, if UE#3 is switched to RAN device #5, RAN device #2 sends the timing context of UE#3 to RAN device #5.

[0265] The implementation principle of S626 is similar to that of S617 described above and can be referenced for further understanding. Furthermore, RAN device #5 can determine, based on UE #3's timing context, that UE #3 is a non-master clock member of the group, facilitating RAN device #5's maintenance and updates of the group. The implementation principle of S626 is similar to that of S619 described above and can be referenced for further understanding. Further explanation is omitted.

[0266] It can be understood that S626 is an optional step, and UE#1 may not be switched.

[0267] It can also be understood that the execution of S626 and S620 - S625 may be in an "and / or" relationship.

[0268] It should be understood that the scheme shown in S601-S626 above is only an example, as a limitation. For example, the time difference between the master clock UE and the RAN device where the master clock UE is located, such as the time difference #1 mentioned above, can also be directly managed by the AMF network element. For example, RAN#1 obtains time difference #1 and sends it to the AMF network element. If, in addition to the members residing in the RAN#1 device, there are other members in the group residing in other RAN devices, the AMF network element determines in which RAN devices, such as RAN device #2, other members (such as UE#3) in the group reside except for the members residing in the RAN#1 device, so as to send the time difference #1 to RAN device #2. In the case of AMF network element management, the clock synchronization between the non-master clock UE and the master clock UE can still adopt the three methods described in S615 above. Alternatively, the RAN device where the non-master clock UE is located can synchronize its clock with the non-master clock UE. The non-master clock UE completes clock synchronization with the RAN device where it is located by receiving the reference time of the RAN device where it is located. At this time, the time difference #1 provided by the AMF network element to the non-master clock UE is used for the non-master clock UE to synchronize its clock with the master clock UE. In addition, in the case of AMF network element management, if the AMF network element determines that a non-master clock UE has undergone a handover, such as switching from a source RAN device to a target RAN device, the AMF network element can also actively send time difference #1 to the target RAN device. The target RAN device then sends time difference #1 to the non-master clock UE for clock synchronization between the non-master clock UE and the master clock UE.

[0269] It should also be understood that the process illustrated in FIG6 is based on an example of a group consisting of three UEs and two RAN devices. In practice, a group may include more or fewer UEs and more or fewer RAN devices. The implementation principles remain similar to the process illustrated in FIG6 and can be readily understood by reference. Further explanation is omitted.

[0270] Scenario 2:

[0271] Figure 7 is a flow chart of the communication method provided in an embodiment of the present application. The communication method is applicable to the above-mentioned communication system, and mainly involves the interaction between UE, RAN equipment, AMF network element, PCF network element, TSCTSF network element, AF, etc.

[0272] Scenario 2 can be implemented based on Scenario 1. For example, when the clock synchronization of the group has been completed in Scenario 1, the AF can initiate a group update request message (such as the update of the master clock member in the group) to the TSCTSF network element. The TSCTSF network element can respond to the AF's request, trigger the PCF network element to update the AM policy, and provide it to the AMF network element. The AMF network element will trigger the RAN device to synchronize the group's clock again based on the latest AM policy. For example, the RAN device can determine the time difference between itself and the latest master clock member in the group, and complete the timing of the non-master clock members in the group accordingly, so that the non-master clock members can be synchronized with the master clock members. Alternatively, the RAN device can determine the time difference between itself and the latest master clock member in the group and send it to the AMF network element. The AMF network element will send the time difference to the non-master clock members in the group accordingly, so that the non-master clock members can be synchronized with the master clock members.

[0273] As shown in Figure 7, the process of the communication method is as follows:

[0274] S701: The AF sends a parameter configuration update request (Nnef_ParameterProvision_Update Request) message #1 to the NEF network element. The NEF network element receives the parameter configuration update request message #1 from the AF.

[0275] The parameter configuration creation request message #1 is used to provide one or more parameters (such as a group) to be updated to the NEF network element. For example, the parameter configuration creation request message #1 may include group information to request a clock synchronization service for the group, such as a clock synchronization service when a master clock member in the group is updated. For example, the group information may include at least one of the following: a clock synchronization error, a group identifier, an identifier of a member in the group, or an identifier of the latest master clock member. For example, if the latest master clock member is UE#2, that is, the master clock member has changed from the original UE#1 to UE#2, at which point UE#1 may have left the group. In other words, the group members at this point may include UE#2 and UE#3.

[0276] After receiving the parameter configuration update request message #1 from the AF, the NEF network element can determine whether the AF is authorized to update parameters, such as whether the AF is authorized to update the group. If the AF is authorized to update the group, the NEF network element executes S702; otherwise, the process fails.

[0277] It is understandable that the parameter configuration update request message #1 may also be replaced by any other possible message, such as a group update request message.

[0278] S702: The NEF network element sends a Nudm_Parameter Provision_Update Request message #2 to the UDM network element. The UDM network element receives the Nudm_Parameter Provision_Update Request message #2 from the NEF network element.

[0279] Parameter configuration update request message #2 carries the parameters in NEF parameter configuration update request message #1. Parameter configuration creation request message #2 and parameter configuration creation request message #1 can be the same message, or different messages, and there is no limitation on this. Optionally, after the UDM network element receives the UDM parameter configuration update request message #1 from the network element, the UDM network element can determine whether the UDM network element has accepted the AF update group. If the UDM network element accepts the AF update group, the UDM network element configures the corresponding parameters. For example, the UDM network element updates the group according to the parameter configuration update request message #2, such as saving the group update information in the parameter configuration creation request message #2 to the contract information of the group to update the master clock member in the contract information of the group, otherwise, the process fails.

[0280] Optionally, if the group identifier is an external group ID, the UDM network element may also map the external group ID to an internal group ID. Similarly, if the identifier of a member in the group is an external ID, the UDM network element may also map the external ID to an internal ID.

[0281] It is understandable that the parameter configuration update request message #2 may also be replaced by any other possible message, such as a group update request message.

[0282] S703: The UDM network element sends a Nudm_Parameter Provision_Update Response message #2 to the NEF network element. The NEF network element receives the Nudm_Parameter Provision_Update Response message #2 from the UDM network element.

[0283] Parameter Configuration Update Response Message #2 is used in response to Parameter Configuration Update Request Message #2. If the process fails, the reason value in Parameter Configuration Update Response Message #2 indicates the failure reason, such as the UDM network element not accepting the AF update group. It is understood that Parameter Configuration Update Response Message #2 can also be replaced by any other possible message, such as a Group Update Response Message.

[0284] S704: The NEF network element sends a Nudm_ParameterProvision_Update Response message #1 to the AF. The AF receives the Nudm_ParameterProvision_Update Response message #1 from the NEF network element.

[0285] Parameter Configuration Update Response Message #1 is used in response to Parameter Configuration Update Request Message #1. If the process fails, the reason value in Parameter Configuration Update Response Message #1 may indicate the reason for the failure, such as the AF not being authorized to update the group. It is understood that Parameter Configuration Update Response Message #1 can also be replaced by any other possible message, such as a Group Update Response Message.

[0286] It is understandable that if the AF is a trusted third-party application service, the AF can directly initiate a group parameter configuration update request message to the UDM network element. After receiving the request, the UDM network element performs the same operation as S702 and initiates a response to the AF accordingly.

[0287] S705: The UDM network element sends group information to the TSCTSF network element.

[0288] According to the process shown in Figure 6 above, the TSCTSF network element can subscribe to the group data from the UDM network element when creating a group. Therefore, when the group changes, the UDM network element can respond to the subscription of the TSCTSF network element and send the changed group information to the TSCTSF network element.

[0289] It is understood that the implementation of S705 is a possible example and is not intended to be limiting. For example, group information (such as lightweight information) may also be stored in the TSCTSF network element, and the TSCTSF network element may update the group information locally or in accordance with the AF group update request to obtain the changed group information. For another example, the AF may also send a request for group update to the TSCTSF network element, and the TSCTSF network element may obtain the group information from the UDM network element based on the request, and then update the group information to obtain the changed group information.

[0290] It can be understood that, unlike the group information in the process of FIG. 6 , the group information in the process of FIG. 7 refers to the changed group information unless otherwise specified.

[0291] It can be understood that the execution order between S703 - S704 and S705 is not limited.

[0292] S706: The AF sends a group access layer clock synchronization update request message (Nnef_ASTI_Update Request) message #1 to the NEF network element. The NEF network element receives the group access layer clock synchronization update request message #1 from the AF.

[0293] The group access layer clock synchronization update request message #1 may include group information to request the group's clock synchronization service, such as the clock synchronization service when the master clock member in the group is updated, thereby triggering the network to provide the group's clock synchronization service again.

[0294] S707: The NEF network element sends a group access layer clock synchronization update request (Ntsctsf_ASTI_Update Request) message #2 to the TSCTSF network element. The TSCTSF network element receives the group access layer clock synchronization update request message #2 from the NEF network element.

[0295] Group access layer clock synchronization update request message #2 may carry the same group information as group access layer clock synchronization update request message #1. That is, the NEF network element may encapsulate the group information in group access layer clock synchronization update request message #1 into group access layer clock synchronization update request message #2 and send group access layer clock synchronization update request message #2 to the TSCTSF network element. Alternatively, group access layer clock synchronization update request message #2 and group access layer clock synchronization update request message #1 may be the same message.

[0296] It can be understood that the execution of S706-S707 and S701-S705 can be in an "and / or" relationship, that is, the AF can trigger the clock synchronization of the group by requesting the UDM network element to update the group, and / or, the AF can also trigger the clock synchronization of the group by directly requesting the TSCTSF.

[0297] S708: The TSCTSF network element sends a PCF AM policy authorization update request (Npcf_AM_Policy Authorization_Update Request) message to the PCF network element. The PCF network element receives the PCF AM policy authorization update request message from the TSCTSF network element.

[0298] The PCF AM policy authorization update request message can be used to request the PCF network element to update the AM policy. For example, the PCF AM policy authorization update request message can carry group information to indicate that the group information should be updated in the AM policy.

[0299] S709: The PCF network element updates the AM policy and obtains the updated AM policy.

[0300] The updated AM policy may include the aforementioned group information. That is, the PCF network element may update the AM policy based on the PCF AM policy authorization update request message, such as by updating the group information into the existing AM policy to replace the original group information in the AM policy (such as the group information involved in the process of Figure 6 ), thereby obtaining an updated AM policy. The PCF network element may also provide the updated AM policy to the AMF network element, so that the AMF network element can issue the corresponding configuration to the RAN device based on the updated AM policy, thereby achieving group clock synchronization.

[0301] S710: The PCF network element sends a PCF AM policy authorization update response (Npcf_AM_Policy Authorization_Update Response) message to the TSCTSF network element. The TSCTSF network element receives the PCF AM policy authorization update response message from the PCF network element.

[0302] The PCF AM policy authorization update response message can be used to respond to the above-mentioned PCF AM policy authorization update request message, indicating that the AM policy update is successful.

[0303] S711, the TSCTSF network element sends a group access layer clock synchronization update response (Ntsctsf_ASTI_Update Response) message #2 to the NEF network element. The NEF network element receives the group access layer clock synchronization update response message #2 from the TSCTSF network element.

[0304] S712: The NEF network element sends a group access layer clock synchronization update response (Nnef_ASTI_Create Response) message #1 to the AF. The AF receives the group access layer clock synchronization update response message #1 from the NEF network element.

[0305] Among them, the group access layer clock synchronization update response message #2 can be used to respond to the above-mentioned group access layer clock synchronization update request message #2, and the group access layer clock synchronization update response message #1 can be used to respond to the above-mentioned group access layer clock synchronization update request message #1, indicating that the network accepts the group's request for clock synchronization service.

[0306] S713, the AMF network element sends an N2 message to the RAN device.

[0307] Among them, the principle of S713 is similar to that of the above-mentioned S613, which can be understood by reference and will not be repeated here.

[0308] S714, RAN device #1 obtains time difference #3.

[0309] Time difference #3 can be the time difference between UE#2 and RAN device #1. For example, in response to receiving the N2 message, RAN device #1 can determine that UE#2 is the latest master clock member. In this way, RAN device #1 can obtain time difference #3 based on the clock synchronization error. Optionally, it can perform an RTT-based process with UE#2 to obtain time difference #3. The specific implementation of the RTT-based process can be found in the description of Figure 4 above and will not be repeated here.

[0310] Optionally, RAN device #1 may also update the timing context of UE #2, such as updating UE #2 as a master clock member into the timing context of UE #2.

[0311] S715 , RAN device # 1 saves the time difference # 3 to the TSC TSF network element, the UDM network element, or the PCF network element.

[0312] Among them, S715 is used to update the previously saved time difference, such as updating time difference #1 / time difference #2 to time difference #3. Its principle is similar to that of the above-mentioned S616, which can be understood by reference and will not be repeated here.

[0313] S716 , RAN device # 1 sends time difference # 3 to RAN device # 2 .

[0314] Among them, the principle of S716 is similar to that of the above-mentioned S617, which can be understood by reference and will not be repeated here.

[0315] S717 , RAN device #2 synchronizes the clocks of UE #3 and UE #2.

[0316] Among them, the implementation principle of S717 is similar to that of the above-mentioned S615, which can be referred to for understanding and will not be repeated here.

[0317] At this point, the network completes the clock synchronization of the group under the condition that the master clock member changes. Afterwards, if the members in the group switch, the principle is similar to the above S619-S626, which can be understood by reference and will not be repeated here.

[0318] It is understandable that the above scenario 2 takes the change of the master clock member as an example, but is not intended to be limiting. For example, when the clock synchronization error changes, the network side may also need to re-complete the group's clock synchronization.

[0319] It can also be understood that, similar to that shown in FIG6 above, the time difference between the master clock UE and the RAN device where the master clock UE is located, such as the time difference #1 mentioned above, can also be directly managed by the AMF network element. You can refer to it for understanding and will not go into details.

[0320] Scenario 3:

[0321] Figure 8 is a flow chart of the communication method provided in the embodiment of the present application. The communication method is applicable to the above-mentioned communication system, mainly involving the interaction between UE, RAN equipment, AMF network element, PCF network element, TSCTSF network element, AF, etc.

[0322] Scenario 3 can be implemented based on Scenario 1. For example, when the clock synchronization of the group has been completed in Scenario 1, the AF can initiate a group update request message to the TSCTSF network element (such as the group has new non-master clock members). The TSCTSF network element can respond to the AF's request, trigger the PCF network element to update the AM policy, and provide it to the AMF network element. The AMF network element triggers the RAN device to synchronize the time of the newly added non-master clock members in the group according to the latest AM policy, so that the newly added non-master clock members can be synchronized with the master clock members.

[0323] As shown in Figure 8, the process of the communication method is as follows:

[0324] S801: The AF sends a parameter configuration update request message #1 to the NEF network element. The NEF network element receives the parameter configuration update request message #1 from the AF.

[0325] The parameter configuration update request message # is used to provide one or more parameters (such as a group) to be updated to the NEF network element. For example, the parameter configuration update request message # may include group information, such as group information, to request clock synchronization services for the group, such as clock synchronization services when a new non-master clock member is added to the group. For example, the group information may include at least one of the following: a clock synchronization error, a group identifier, and an identifier of a new member (non-master clock member) in the group, such as a new UE#4 added to the group, or an identifier of a master clock member.

[0326] After receiving the parameter configuration update request message #1 from the AF, the NEF network element can determine whether the AF is granted the authority to update the group. If the AF is granted the authority to update the group, the NEF network element executes S802, otherwise, the process fails.

[0327] It is understandable that the parameter configuration update request message #1 may also be replaced by any other possible message, such as a group update request message.

[0328] S802: The NEF network element sends a parameter configuration update request message #2 to the UDM network element. The UDM network element receives the parameter configuration update request message #2 from the NEF network element.

[0329] Parameter configuration update request message #2 carries the parameters in parameter configuration update request message #1. Optionally, after the UDM network element receives parameter configuration update request message #2 from the NEF network element, the UDM network element can determine whether the UDM network element accepts the authority of the AF update group. If the UDM network element accepts the authority of the AF update group, the UDM network element configures the corresponding parameters. For example, the UDM network element can update the group according to parameter configuration update request message #2, such as saving the group update information in the UDM parameter configuration creation request message to the contract information of the group to update the non-master clock members in the contract information of the group, otherwise, the process fails.

[0330] Optionally, if the group identifier is an external group ID, the UDM network element may also map the external group ID to an internal group ID. Similarly, if the identifier of a member in the group is an external ID, the UDM network element may also map the external ID to an internal ID.

[0331] It is understandable that the parameter configuration update request message #2 may also be replaced by any other possible message, such as a group update request message.

[0332] S803: The UDM network element sends a parameter configuration update response message #2 to the NEF network element. The NEF network element receives the parameter configuration update response message #2 from the UDM network element.

[0333] Parameter Configuration Update Response Message #2 is used in response to Parameter Configuration Update Request Message #2. If the process fails, the reason value in Parameter Configuration Update Response Message #2 indicates the failure reason, such as the UDM network element not accepting the AF update group's permission. It is understood that Parameter Configuration Update Response Message #2 can also be replaced by any other possible message, such as a Group Update Response Message.

[0334] S804: The NEF network element sends a parameter configuration update response message #1 to the AF. The AF receives the parameter configuration update response message #1 from the NEF network element.

[0335] Parameter Configuration Update Response Message #1 is used in response to Parameter Configuration Update Request Message #1. If the process fails, the reason value in Parameter Configuration Update Response Message #1 indicates the failure reason, such as the AF not being authorized to update the group. It is understood that Parameter Configuration Update Response Message #1 can also be replaced by any other possible message, such as a Group Update Response Message.

[0336] It is understandable that if the AF is a trusted third-party application service, the AF can directly initiate a group parameter configuration update request message to the UDM network element. After receiving the request, the UDM network element performs the same operation as S802 and initiates a response to the AF accordingly.

[0337] S805: The UDM network element sends group information to the TSCTSF network element.

[0338] According to the process shown in Figure 6 above, the TSCTSF network element can subscribe to the group data from the UDM network element when creating a group. Therefore, when the group changes, the UDM network element can respond to the subscription of the TSCTSF network element and send the updated group information to the TSCTSF network element.

[0339] It can be understood that, unlike the group information in the process of FIG. 6 , the group information in the process of FIG. 8 refers to the changed group information unless otherwise specified.

[0340] It can be understood that the execution order between S803 - S804 and S805 is not limited.

[0341] S806: The AF sends a group access layer clock synchronization update request message #1 to the NEF network element. The NEF network element receives the group access layer clock synchronization update request message #1 from the AF.

[0342] The group access layer clock synchronization update request message #1 may include group information to request the group's clock synchronization service, such as the clock synchronization service when there are new non-master clock members in the group, thereby triggering the network to provide the group's clock synchronization service again, such as synchronizing the new non-master clock members with the master clock members.

[0343] S807: The NEF network element sends a group access layer clock synchronization update request message #2 to the TSCTSF network element. The TSCTSF network element receives the group access layer clock synchronization update request message #2 from the NEF network element.

[0344] The group access layer clock synchronization update request message #2 may carry the same group information as the group access layer clock synchronization update request message #1, that is, the NEF network element may encapsulate the group information in the group access layer clock synchronization update request message #1 into the group access layer clock synchronization update request message #2, and send the group access layer clock synchronization update request message #2 to the TSCTSF network element.

[0345] It can be understood that the execution of S806-S807 and S801-S805 can be in an "and / or" relationship, that is, the AF can trigger the timing of the newly added non-master clock members by requesting the UDM network element to update the group, and / or, the AF can also trigger the timing of the newly added non-master clock members by directly requesting the TSCTSF.

[0346] S808: The TSCTSF network element sends a PCF AM policy authorization update request (Npcf_AM_Policy Authorization_Update Request) message to the PCF network element. The PCF network element receives the PCF AM policy authorization update request message from the TSCTSF network element.

[0347] The PCF AM policy authorization update request message can be used to request the PCF network element to update the AM policy. For example, the PCF AM policy authorization update request message can carry group information to indicate that the group information should be updated in the AM policy.

[0348] S809: The PCF network element updates the AM policy and obtains the updated AM policy.

[0349] The updated AM policy may include the aforementioned group information. That is, the PCF network element may update the AM policy based on the PCF AM policy authorization update request message, such as by updating the group information into the existing AM policy to replace the original group information in the AM policy, thereby obtaining an updated AM policy. The PCF network element may also provide the updated AM policy to the AMF network element, which then issues the corresponding configuration to the RAN device based on the updated AM policy, thereby enabling timing for the newly added non-master clock member.

[0350] S810: The PCF network element sends a PCF AM policy authorization update response message to the TSCTSF network element. The TSCTSF network element receives the PCF AM policy authorization update response message from the PCF network element.

[0351] The PCF AM policy authorization update response message can be used to respond to the above-mentioned PCF AM policy authorization update request message, indicating that the AM policy update is successful.

[0352] S811, the TSCTSF network element sends a TSCTSF group clock synchronization update response message #2 to the NEF network element. The NEF network element receives the TSCTSF group clock synchronization update response message #2 from the TSCTSF network element.

[0353] S812: The NEF network element sends an NEF group clock synchronization update response message #1 to the AF. The AF receives the NEF group clock synchronization update response message #1 from the NEF network element.

[0354] Among them, the group access layer clock synchronization update response message #2 can be used to respond to the above-mentioned group access layer clock synchronization update request message #2, and the NEF group clock synchronization update response message can be used to respond to the above-mentioned group access layer clock synchronization update request message #1, both of which can indicate that the network has responded to the AF's request.

[0355] S813, the AMF network element sends an N2 message to RAN device #1.

[0356] The AMF network element can determine that UE#4 resides on RAN device #1 through mobility management of UE#4, and thus send the N2 message to RAN device #1. In addition, the principle of S813 is similar to that of S613 above, and can be understood by reference, and will not be repeated here.

[0357] It is understandable that UE#4 residing on RAN device #1 is only an example, and it may also be other RAN devices, such as RAN device #2, RAN device #3, etc., without limitation.

[0358] S814, RAN device #1 synchronizes the clocks of UE #4 and UE #1.

[0359] Since UE#1, i.e., the master clock UE, resides on RAN device #1, RAN device #1 can locally obtain the time difference between UE#1 and RAN device #1, such as time difference #1 described above. Alternatively, since time difference #1 can also be stored on the network side, such as a UDM network element, a PCF network element, or a TSCTSF network element, RAN device #1 can also obtain time difference #1 from the UDM network element, the PCF network element, or the TSCTSF network element. Alternatively, if UE#1 is not residing on RAN device #1, RAN device #1 can also obtain the time difference between UE#1 and the RAN device on which UE#1 resides. For example, RAN device #1 can obtain the time difference via the Xn interface between itself and the RAN device on which UE#1 resides. Alternatively, RAN device #1 can request the time difference from the AMF network element. Based on the request from RAN device #1, the AMF network element obtains the time difference from the RAN device on which UE#1 resides and sends it to RAN device #1.

[0360] In this way, RAN device #1 can synchronize the clocks of UE #4 and UE #1 based on the time difference between UE #1 and the RAN device where UE #1 resides. The implementation principle of clock synchronization is similar to that of S615 above, which can be understood by reference and will not be repeated here.

[0361] At this point, if there is a new non-master clock member in the group, the network completes the clock synchronization of the new non-master clock member. Afterwards, if a member in the group switches, the principle is similar to that of S619-S626 above, which can be understood by reference and will not be repeated here.

[0362] It can also be understood that, similar to that shown in FIG6 above, the time difference between the master clock UE and the RAN device where the master clock UE is located, such as the time difference #1 mentioned above, can also be directly managed by the AMF network element. You can refer to it for understanding and will not go into details.

[0363] It can be understood that the above-mentioned process of scenario 2-scenario 3 is only an example, and in practice, there may be other implementation methods. For example, based on scenario 1, the AMF network element may send a group information subscription message carrying the identifier of the above-mentioned group to the UDM network element / TSCTSF network element, so as to implement the subscription of group information change notification to the UDM network element / TSCTSF network element with group as the granularity. When the UDM network element or TSCTSF network element learns about the group information change through the UDM network element (such as S701-S707, S801-S807 above), the UDM network element / TSCTSF network element may send a group information subscription notification message carrying the changed group information to the AMF network element, so that the AMF network element can then provide the group information to the RAN device to trigger the group's clock synchronization service.

[0364] In summary, according to the above scenarios 1-3, since the clock synchronization of the group can be achieved through the RAN device, for example, the RAN device first determines the time difference between itself and the master clock member, and then synchronizes the clocks of the non-master clock members in the group with the master clock member based on this time difference, that is, achieving the clock synchronization of the group. In addition, as mentioned in the method of scenario 1, the clock synchronization of the group can also be achieved through the AMF. For example, the RAN device first determines the time difference between itself and the master clock member, that is, the time difference between the 5GS time and the master clock member of the group, and sends this time difference to the AMF, which then sends it to the non-master clock members in the group, achieving the clock synchronization of the non-master clock members in the group with the master clock members. In addition, since clock synchronization does not require gPTP, members in the group do not need to configure the DS-TT module, and there is no need to ensure the clock synchronization accuracy from the UPF network element to the DS-TT, which can also reduce the implementation cost.

[0365] The above describes the process of the communication method in a specific scenario in conjunction with Figures 6 to 8. The following describes the overall process of the communication method in conjunction with Figure 9.

[0366] Figure 9 is a fourth flow chart of a communication method provided in an embodiment of the present application. This communication method is applicable to the above-mentioned communication system, and mainly involves the interaction between application functions (such as AF), time synchronization network elements (such as TSCTSF network elements) and access network devices (such as RAN devices).

[0367] As shown in Figure 9, the specific process is as follows:

[0368] S901, the application function sends group information to the network.

[0369] Group information can be used to request group clock synchronization services. Group clock synchronization services require non-master clock members in the group to synchronize their clocks with the master clock member. In other words, group clock synchronization services can be triggered by application functions, such as when a group is created or updated, without restriction.

[0370] Optionally, the group information can also be used to indicate that the master clock member is the first terminal, and the non-master clock members in the group include the second terminal. In this case, the group information can be carried in the group clock synchronization creation request message (such as the above-mentioned group access network clock synchronization creation request message), that is, the existing message is reused to trigger the clock synchronization service, or a newly defined message can be used to achieve decoupling from the existing message, making the clock synchronization more flexible. For details, please refer to the relevant introduction in S601 above, which will not be repeated here. Of course, the non-master clock members in the group can also include other terminals besides the second terminal, such as the third terminal / fourth terminal, etc., and there is no limitation on this. This application takes the second terminal as an example for introduction.

[0371] Alternatively, optionally, the group information can also be used to indicate that the master clock member is changed to the first terminal. At this time, the original master clock member may have left the group, and / or the group information is also used to indicate that the newly added non-master clock members in the group include the second terminal. Similarly, the newly added non-master clock members in the group may also include other terminals in addition to the second terminal, and there is no restriction on this. In this case, the group information is carried in the group update request message (such as the above-mentioned group access network clock synchronization update request message), that is, when the group is updated, the clock synchronization service can be triggered by reusing the existing message, or a newly defined message can be used to achieve decoupling from the existing message, so that the clock synchronization is more flexible. For details, please refer to the relevant introduction in S701 and / or S801 above, which will not be repeated here.

[0372] That is, the second terminal can be an initial member when the group is created or a member that joins the group later. That is, whether it is an initial member or a later member, the network (such as the access network device described below) can provide it with a group clock synchronization service.

[0373] The network may include a data management network element (such as a UDM network element) or a clock synchronization network element (such as a TSCTSF network element). The application function may send group information to the data management network element, and the data management network element may send the group information to the clock synchronization network element through the subscription service, and the clock synchronization network element may send the group information to the access and mobility management network element (such as an AMF network element) through the policy control network element (such as a PCF network element). For details, please refer to the above-mentioned S601-S604, S701-S705, S801-S805 related introductions, which will not be repeated here. Alternatively, the application function may send group information directly to the clock synchronization network element, and the clock synchronization network element may trigger or create a clock synchronization service for the group. Alternatively, after receiving the group information, the data management network element may also forward the group information to the access and mobility management network element. The application function can send group information directly to the clock synchronization network element, and the clock synchronization network element sends the group information to the access and mobility management network element through the policy control network element. For details, please refer to the relevant introduction of S605-S607, S706-S707, S806-S807 above, which will not be repeated here.

[0374] For ease of understanding, the following example uses the clock synchronization network element sending group information to the access and mobility management network element through the policy control network element.

[0375] S902: The clock synchronization network element receives group information.

[0376] As described in S901, the clock synchronization network element can receive a group clock synchronization creation request message from the application function. The group clock synchronization creation request message carries the above-mentioned group information. Alternatively, the clock synchronization network element can receive group information from the data management network element, that is, it can obtain group updates by subscribing to the services of the data management network element and trigger the group's clock synchronization service. For example, the clock synchronization network element can subscribe to group information change notifications (which carry the group's identifier) ​​from the data management network element; in the case of group information changes, the clock synchronization network element receives group information from the data management network element, that is, the data management network element sends the changed group information to the clock synchronization network element by way of subscription notifications. When the clock synchronization network element obtains the updated group information, the clock synchronization network element will initiate an update of the group's clock synchronization service.

[0377] S903: The clock synchronization network element initiates a group clock synchronization service for the group according to the group information.

[0378] S904: The application function receives a response from the network.

[0379] The clock synchronization network element can send group information to the access and mobility management network element through the policy control network element, which triggers the access network device to initiate the group clock synchronization service (e.g., through a first message). During this process, the clock synchronization network element can also apply a function to return a response to indicate that the network accepts the group clock synchronization service request. It is understood that the specific implementation of S903-S904 can also refer to the relevant descriptions of S608-S612, S708-S712, and S808-S812 above, and will not be repeated here.

[0380] S905: The first access network device receives the first message.

[0381] The first message may be an interface message between the first access network device and the core network, such as an N2 message, or any other possible message, without limitation. The first message may be used to indicate that the first access network device needs to provide clock synchronization services for the group. For example, the first message may include group information, such as at least one of the following: an identifier of the group, an identifier of the first terminal, or identifiers of other terminals in the group other than the first terminal, to indicate each member of the group, thereby avoiding failure to provide clock synchronization services to certain members of the group due to failure to indicate the information.

[0382] Optionally, the information included in the first message can also be used to indicate that other terminals in the group, excluding the first terminal, need to synchronize their clocks with the first terminal. For example, group members can be divided into two categories: master clock members and non-master clock members. The master clock member's clock serves as a reference, and the non-master clock members synchronize their clocks with the master clock member. In this case, the indication information included in the first message can be an identifier of a clock member, indicating that the first terminal is a master clock member, thereby implicitly indicating that other terminals in the group, excluding the first terminal, need to synchronize their clocks with the first terminal.

[0383] In addition, the specific implementation of S905 can also refer to the relevant introduction of S613, S713, and S813 above, which will not be repeated here.

[0384] S906: The first access network device obtains a first time difference according to the first message.

[0385] The first time difference is the time difference between the first terminal and the first access network device. The first time difference can also be understood as the difference between the time indicated by the reference time information of the first terminal and the time indicated by the reference time information of the first access network device. The first time difference is used to synchronize the clocks of other terminals in the group, excluding the first terminal, with the first terminal. For specific implementation, please refer to the description of S614, S714, and S814 above and will not be repeated here.

[0386] In summary, in the case of clock synchronization service provided for the group, only by determining the time difference between the access network device (such as the first access network device) and the members of the group (such as the first terminal), it is possible to synchronize the clock of other terminals in the group except the first terminal with the clock of the first terminal, that is, to achieve clock synchronization of the group.

[0387] It can be understood that the group may include a second terminal, and the first access network device may further use the first time difference to synchronize the clock of the second terminal with that of the first terminal, as follows.

[0388] In a first possible design scheme, in combination with S901 to S906 above, the method may further include: the first access network device synchronizing the second terminal clock with the first terminal clock according to the first time difference.

[0389] Method 1: The first access network device sends a second message to the second terminal, or the first access network device broadcasts a third message. Both the second message and the third message may carry the first time difference. The first access network device and the second terminal are clock-synchronized. For example, the first access network device may send its reference time information to the second terminal via unicast or broadcast. To achieve higher clock accuracy, clock synchronization may also be achieved through propagation delay compensation (PDC), such as through a TA-based, RTT-based, or other method, though this solution does not limit this. In other words, if the first access network device and the second terminal have already achieved clock synchronization, the first access network device can achieve clock synchronization between the first and second terminals by simply providing the first time difference, resulting in relatively low communication overhead. Optionally, the first time difference may be encrypted ciphertext. For example, if the first time difference is sent via a broadcast message, it may be encrypted ciphertext to prevent information theft and ensure communication security for clock synchronization. The second terminal can decrypt the ciphertext, for example by pre-configuring the decryption key with the second terminal, or by pre-determining the key in the protocol to ensure communication security for clock synchronization.

[0390] It is understood that the second message may be a unicast message, such as an RRC message, a DCI message, a MAC_CE, etc., which is not limited thereto. The third message may be a broadcast message, such as a system message, which is also not limited thereto.

[0391] Method 2: The first access network device sends the first time difference and the reference time information of the first access network device to the second terminal; or, the first access network device broadcasts the first time difference and the reference time information of the first access network device, so that the second terminal can achieve clock synchronization with the first terminal by adding the first time difference and the time of the reference time information of the first access network device.

[0392] Optionally, the time indicated by the reference time information of the first access network device may be the time when the first access network device transmits the reference time information of the first access network device. That is, regardless of whether propagation delay compensation (PDC) is performed between the first access network device and the second terminal, if the PDC value is relatively small, the second terminal can obtain a relatively accurate time of the first terminal by adding the first time difference to the time when the reference time information of the first access network device was transmitted, thereby achieving clock synchronization with the first terminal.

[0393] Optionally, the first time difference and / or the reference time information of the first access network device are encrypted. For example, if the first time difference and / or the reference time information of the first access network device are sent via a broadcast message, they can be encrypted to prevent information theft. Similarly, the second terminal can also decrypt the ciphertext to ensure communication security for clock synchronization.

[0394] Optionally, the first time difference and the reference time information of the first access network device can be carried in different messages. For example, the first access network device sends the first time difference via a unicast message and sends the reference time information of the first access network device via a broadcast message. For another example, the first access network device sends the first time difference via a broadcast message and sends the reference time information of the first access network device via a unicast message. For another example, the first access network device sends the first time difference and the reference time information of the first access network device respectively via different unicast / broadcast messages. In this way, decoupling of transmission can be achieved, and information transmission can be more flexible. Of course, the first time difference and the reference time information of the first access network device can also be carried in the same message, and this is not limited to this.

[0395] Optionally, this design scheme may also consider the PDCs of the first access network device and the second terminal. Specifically, the first access network device may send the PDC values ​​of the first access network device and the second terminal to the second terminal, thereby further improving clock synchronization. In this case, the PDC value may be carried in the second message or the new message, without limitation.

[0396] It can be understood that the above-mentioned first time difference, reference time information of the first access network device and PDC value can be carried in the same message, or can be carried in different messages respectively. For example, the reference time information of the first access network device can be sent through one message first, and then the first time difference and PDC values ​​can be sent respectively through another two messages. There can also be other implementation methods, which are not limited to this.

[0397] It can be understood that the specific implementation of this design solution can also refer to the relevant introduction of S615 above, which will not be repeated here.

[0398] Mode 3: The first access network device sends a second message to the second terminal based on the first time difference, or the first access network device broadcasts a third message based on the first time difference. Both the second message and the third message may carry the reference time information of the first terminal.

[0399] The reference time information of the first terminal is determined by the first access network device based on the first time difference and the reference time information of the first access network device. For example, the time indicated by the reference time information of the first access network device can be the time when the first access network device sends the reference time information of the first terminal. Without considering whether PDC is performed between the first access network device and the second terminal, if the value of PDC is relatively small, by adding the time when the reference time information of the first terminal is sent to the first time difference, a relatively accurate time of the first terminal can be obtained, thereby achieving clock synchronization with the first terminal. In other words, the first access network device can send the time of the first terminal to the second terminal based on the first time difference, without the second terminal having to determine it on its own, thereby reducing the overhead of the second terminal and being more energy-efficient.

[0400] Furthermore, as described above, the second message can also be a unicast message, and the third message can also be a broadcast message. For detailed implementation, please refer to the above description and will not be further elaborated here. Optionally, the first terminal's reference time information can also be encrypted ciphertext. For example, if the first terminal's reference time information is sent via a broadcast message, it can be encrypted ciphertext to prevent information theft. Similarly, the second terminal can also decrypt the ciphertext to ensure secure clock synchronization communications.

[0401] Optionally, the second message also carries the PDC values ​​of the first access network device and the second terminal to achieve more accurate clock synchronization. Similarly, the PDC value can also be carried in the above-mentioned second message or new message, and this is not limited.

[0402] It can be understood that the specific implementation of this design solution can also refer to the relevant introduction of S615 above, which will not be repeated here.

[0403] In the second possible design scheme, combined with the above S901-S906, the method may also include: the first access network device sends the first time difference to the policy control network element and / or the data management network element to save the first time difference to the network so that it does not need to be re-determined for subsequent use. For specific implementation, please refer to the relevant introduction of the above S616 and will not be repeated here.

[0404] In the third possible design scheme, combined with the above S901-S906, the method may also include: the first access network device sends a first time difference to other access network devices (such as the second access network device), so that the second access network device can provide clock synchronization services to other group members in the group who are connected to the second access network device. For specific implementation, please refer to the relevant introduction of the above S617-S618, which will not be repeated here.

[0405] In a fourth possible design scheme, in combination with S901-S906 above, the method may further include: when the second terminal switches to the second access network device, the first access network device sends the timing context of the second terminal to the second access network device. For example, the timing context of the second terminal is used to indicate the first time difference and / or that the second terminal is a non-master clock member in the group. For example, the timing context of the second terminal includes the identifier of the second terminal and does not include the identifier of the master clock member, that is, it indicates that the second terminal is a non-master clock member in the group. The non-master clock members in the group need to be synchronized with the clock of the master clock members in the group. The first terminal is a master clock member, so that the second terminal can still maintain clock synchronization with the first terminal in the second access network device.

[0406] It can be understood that the specific implementation of this design solution can also refer to the relevant introduction of S619 above, which will not be repeated here.

[0407] In the fifth possible design scheme, in combination with the above S901-S906, the method may also include: when the first terminal switches to the third access network device, the first access network device sends the timing context of the first terminal to the third access network device, and receives the second time difference returned by the third access network device. The second time difference is the time difference between the first terminal and the third access network device, which is used to continue to achieve clock synchronization of the group. For example, the timing context of the first terminal is used to indicate that the first terminal is the master clock member in the group, and the non-master clock members in the group need to be synchronized with the master clock member. That is, when the master clock member moves, it is still possible to achieve clock synchronization between the non-master clock members in the group and the master clock member.

[0408] In this case, the first access network device may further synchronize the clocks of the second terminal with those of the first terminal according to the second time difference.

[0409] Method A: The first access network device sends a fourth message to the second terminal, or the first access network device broadcasts a fifth message. Both the fourth and fifth messages carry the second time difference. The first access network device and the second terminal are clock-synchronized. For example, the first access network device can send its reference time information to the second terminal via unicast or broadcast. To achieve higher clock accuracy, clock synchronization can also be achieved using PDC. Optionally, the second time difference can be encrypted ciphertext, which can be decrypted by the second terminal.

[0410] Method B: The first access network device sends the second time difference and the reference time information of the first access network device to the second terminal; or, the first access network device broadcasts the second time difference and the reference time information of the first access network device, so that the second terminal can achieve clock synchronization with the first terminal by adding the second time difference and the time indicated by the reference time information of the first access network device.

[0411] Optionally, the time indicated by the reference time information of the first access network device may be the time when the first access network device sends the reference time information of the first access network device.

[0412] Optionally, the second time difference and / or the reference time information of the first access network device are encrypted ciphertext, and the second terminal can also decrypt the ciphertext. Optionally, the second time difference and the reference time information of the first access network device can also be carried in different messages, or can also be carried in the same message, without limitation.

[0413] Optionally, this design scheme can also consider the PDCs of the first access network device and the second terminal. That is, the first access network device can also send the PDC values ​​of the first access network device and the second terminal to the second terminal to achieve more accurate clock synchronization. In this case, the second time difference, the reference time information of the first access network device, and the PDC value can be carried in the same message or in different messages, without limitation.

[0414] It can be understood that the specific implementation of this design solution can also refer to the relevant introduction of S615 above, which will not be repeated here.

[0415] Mode C: The first access network device sends a fourth message to the second terminal based on the second time difference, or the first access network device broadcasts a fifth message based on the second time difference. Both the fourth message and the fifth message may carry the reference time information of the first terminal.

[0416] The reference time information of the first terminal is determined by the first access network device based on the second time difference and the reference time information of the first access network device. For example, the time indicated by the reference time information of the first access network device may be the time when the first access network device sends the reference time information of the first terminal.

[0417] Optionally, the reference time information of the first terminal may also be encrypted ciphertext, and the second terminal can also decrypt the ciphertext. Optionally, the fourth message also carries the PDC values ​​of the first access network device and the second terminal to achieve more accurate clock synchronization.

[0418] It can be understood that the specific implementation of this design solution can also refer to the relevant introduction of S615 or S625 above, which will not be repeated here.

[0419] It can also be understood that the implementation of the above method is some examples and is not limiting, and the method can also have other implementations.

[0420] Specifically, the first access network device may further send the first time difference to a clock synchronization network element, such as a time-sensitive communication and time synchronization function (TSCTSF) network element. Based on this, the clock synchronization network element determines a policy control network element, such as a PCF network element, corresponding to a member of the group, or a PCF network element serving the group. For example, the clock synchronization network element receives the first time difference from the first access network device and sends the first time difference to a policy control network element corresponding to a member of the group. Optionally, the clock synchronization network element may determine the policy control network element based on the first time difference and then send the first time difference to the policy control network element.

[0421] The policy control network element may determine the access and mobility management network element corresponding to the non-master clock member of the group, such as the AMF network element, or the AMF network element serving the non-master clock member of the group, and send the first time difference to the access and mobility management network element. For example, the policy control network element receives the first time difference from the clock synchronization network element, and sends the first time difference to the access and mobility management network element corresponding to the non-master clock member of the group. Optionally, the policy control network element may determine the access and mobility management network element based on the first time difference, and then send the first time difference to the access and mobility management network element.

[0422] The access and mobility management network element can send a first time difference to other terminals in the group except the first terminal. Optionally, the access and mobility management network element determines the access network device where the other terminal is located, and sends the first time difference to the other terminal through the access network device. That is, when managed by the access and mobility management network element, such as when the members of the group are determined, the clock synchronization between the non-master clock members and the master clock members can still adopt the method described in the first aspect above. Alternatively, the access network device where the non-master clock member is located can perform clock synchronization with the non-master clock member. For example, the non-master clock member completes clock synchronization with the access network device by receiving the reference time information of the access network device where it is located. At this time, the access and mobility management network element can directly send the first time difference to the non-master clock member (that is, the access network device where the non-master clock member is located can be transparently transmitted) for the non-master clock member to synchronize its own clock with the master clock member. In addition, under the management of the access and mobility management network element, if the access and mobility management network element determines that a non-master clock member has switched, such as switching from a source access network device to a target access network device, the access and mobility management network element can also actively send a first time difference to the target access network device, so that the target access network device can immediately send the first time difference to the non-master clock member, so that the non-master clock member is synchronized with the master clock member.

[0423] The communication method provided in the embodiment of the present application is described in detail above in conjunction with Figures 6 to 9. The communication device for executing the communication method provided in the embodiment of the present application is described in detail below in conjunction with Figures 10 and 11.

[0424] Figure 10 is a structural diagram of a communication device according to an embodiment of the present application. As shown in Figure 10 , the communication device 1000 includes a transceiver module 1001 and a processing module 1002. For ease of description, Figure 10 shows the main components of the communication device.

[0425] The transceiver module 1001 is used to perform the transceiver function of the method shown in FIG. 6 to FIG. 9 , and the processing module 1002 is used to perform other functions of the method shown in FIG. 6 to FIG. 9 except the transceiver function.

[0426] Optionally, the transceiver module 1001 may include a sending module (not shown in FIG10 ) and a receiving module (not shown in FIG10 ). The sending module is used to implement the sending function of the communication device 1000 , and the receiving module is used to implement the receiving function of the communication device 1000 .

[0427] Optionally, the communication device 1000 may further include a storage module (not shown in FIG. 10 ) storing a program or instruction. When the processing module 1002 executes the program or instruction, the communication device 1000 may perform the functions of the network device in the methods shown in FIG. 6 to FIG. 9 in the above method.

[0428] It can be understood that the communication device 1000 can be a network device, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device, which is not limited in this application.

[0429] In addition, the technical effects of the communication device 1000 can refer to the technical effects of the communication method shown in Figures 6 to 9, and will not be repeated here.

[0430] Figure 11 is a second structural diagram of a communication device provided in an embodiment of the present application. Exemplarily, the communication device may be a network device, or a chip (system) or other component or assembly that can be provided in a network device. As shown in Figure 11, the communication device 1100 may include a processor 1101. Optionally, the communication device 1100 may further include a memory 1102 and / or a transceiver 1103. The processor 1101 is coupled to the memory 1102 and the transceiver 1103, such as by a communication bus.

[0431] The following is a detailed introduction to the various components of the communication device 1100 with reference to FIG11 :

[0432] The processor 1101 is the control center of the communication device 1100 and can be a single processor or a collective term for multiple processing elements. For example, the processor 1101 can be one or more central processing units (CPUs), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application, such as one or more digital signal processors (DSPs) or one or more field programmable gate arrays (FPGAs).

[0433] Optionally, the processor 1101 can execute various functions of the communication device 1100 by running or executing software programs stored in the memory 1102 and calling data stored in the memory 1102, such as executing the communication methods shown in Figures 6 to 9 above.

[0434] In a specific implementation, as an embodiment, the processor 1101 may include one or more CPUs, such as CPU0 and CPU1 shown in FIG11 .

[0435] In a specific implementation, as an embodiment, the communication device 1100 may also include multiple processors, such as the processor 1101 and the processor 1104 shown in FIG11 . Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0436] Among them, the memory 1102 is used to store the software program for executing the solution of this application, and the execution is controlled by the processor 1101. The specific implementation method can refer to the above method embodiment and will not be repeated here.

[0437] Alternatively, the memory 1102 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including a compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 1102 may be integrated with the processor 1101 or exist independently and be coupled to the processor 1101 via an interface circuit (not shown in FIG. 11 ) of the communication device 1100, which is not specifically limited in this embodiment of the present application.

[0438] Transceiver 1103 is used for communication with other communication devices. For example, if communication device 1100 is a terminal, transceiver 1103 can be used to communicate with a network device or another terminal device. For another example, if communication device 1100 is a network device, transceiver 1103 can be used to communicate with a terminal or another network device.

[0439] Optionally, the transceiver 1103 may include a receiver and a transmitter (not shown separately in FIG11 ), wherein the receiver is used to implement a receiving function, and the transmitter is used to implement a transmitting function.

[0440] Optionally, the transceiver 1103 may be integrated with the processor 1101 or exist independently and be coupled to the processor 1101 through an interface circuit (not shown in FIG. 11 ) of the communication device 1100 . This embodiment of the present application does not specifically limit this.

[0441] It is understandable that the structure of the communication device 1100 shown in FIG11 does not constitute a limitation on the communication device, and an actual communication device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0442] In addition, the technical effects of the communication device 1100 can refer to the technical effects of the methods described in the above method embodiments, and will not be repeated here.

[0443] It should be understood that the processor in the embodiments of the present application may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0444] It should also be understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0445] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. 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 program are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. 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 computer-readable storage medium. 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 a wired (such as infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0446] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. A and B can be singular or plural. Furthermore, the character " / " as used herein generally indicates an "or" relationship between the associated objects, but it may also indicate an "and / or" relationship. For specific understanding, please refer to the context.

[0447] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural 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 plural.

[0448] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean 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 the present application.

[0449] Those skilled in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel 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.

[0450] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0451] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0452] The units described as separate components may or may not be physically separate, and 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 these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0453] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0454] If the functions are implemented in the form of 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 the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0455] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: include: The first access network device receives a first message, wherein the first message is used to indicate a clock synchronization service provided by the first access network device for a group; The first access network device obtains a first time difference based on the first message; wherein the first time difference is the time difference between a first terminal and the first access network device, the first terminal is a member of the group, and the first time difference is used for clock synchronization between other terminals in the group except the first terminal and the first terminal.

2. The method according to claim 1, characterized in that The group includes a second terminal, and the method further includes: The first access network device sends a second message to the second terminal, wherein the second message carries the first time difference, or the first access network device broadcasts a third message, wherein the third message carries the first time difference.

3. The method according to claim 2, characterized in that The first time difference is an encrypted ciphertext, and the second terminal can decrypt the ciphertext.

4. The method according to claim 2 or 3, characterized in that: The method further comprises: The first access network device is synchronized with the second terminal clock.

5. The method according to claim 1, characterized in that The group includes a second terminal, and the method further includes: The first access network device sends the first time difference and reference time information of the first access network device to the second terminal; Alternatively, the first access network device broadcasts the first time difference and reference time information of the first access network device.

6. The method according to claim 5, characterized in that The first time difference and / or the reference time information of the first access network device is encrypted ciphertext, and the second terminal can decrypt the ciphertext.

7. The method according to claim 5 or 6, characterized in that: The first time difference and the reference time information of the first access network device are carried in different messages.

8. The method according to any one of claims 5 to 7, characterized in that: The time indicated by the reference time information of the first access network device is the time when the first access network device sends the reference time information of the first access network device.

9. The method according to any one of claims 5 to 8, characterized in that: The method further comprises: The first access network device sends a value of a propagation delay compensation PDC between the first access network device and the second terminal to the second terminal.

10. The method according to claim 1, characterized in that The group includes a second terminal, and the method further includes: The first access network device sends a second message to the second terminal according to the first time difference, wherein the second message carries reference time information of the first terminal; or The first access network device broadcasts a third message according to the first time difference, wherein the third message carries reference time information of the first terminal.

11. The method according to claim 10, characterized in that The reference time information of the first terminal is encrypted ciphertext, and the second terminal can decrypt the ciphertext.

12. The method according to claim 10 or 11, characterized in that: The reference time information of the first terminal is determined by the first access network device according to the first time difference and the reference time information of the first access network device.

13. The method according to any one of claims 10 to 12, characterized in that: The method further comprises: The first access network device sends a value of a PDC of the first access network device and the second terminal to the second terminal.

14. The method according to any one of claims 2 to 13, characterized in that The second terminal is a member of the group, or the second terminal is a member that newly joins the group.

15. The method according to any one of claims 1 to 14, characterized in that The first message includes at least one of the following: an identifier of the group, an identifier of the first terminal, or identifiers of other terminals in the group except the first terminal.

16. The method according to claim 15, characterized in that The information included in the first message is also used to indicate that other terminals in the group except the first terminal need to be synchronized with the clock of the first terminal.

17. The method according to any one of claims 1 to 16, characterized in that The method further comprises: The first access network device sends the first time difference to the second access network device.

18. The method according to any one of claims 1 to 17, characterized in that The method further comprises: The first access network device sends the first time difference to a policy control network element and / or a data management network element.

19. The method according to any one of claims 1 to 18, characterized in that The group includes a second terminal, and the method further includes: When the second terminal switches to the second access network device, the first access network device sends the timing context of the second terminal to the second access network device.

20. The method according to claim 19, characterized in that The timing context of the second terminal is used to indicate the first time difference and / or that the second terminal is a non-master clock member in the group.

21. The method according to any one of claims 1 to 20, characterized in that The method further comprises: When the first terminal switches to a third access network device, the first access network device sends the timing context of the first terminal to the third access network device; The first access network device receives the second time difference returned by the third access network device, wherein the second time difference is the time difference between the first terminal and the third access network device.

22. The method according to claim 21, characterized in that The timing context of the first terminal is used to indicate that the first terminal is a master clock member in the group.

23. A communication method, characterized in that: include: The application function sends group information to the network, wherein the group information is used to request a clock synchronization service of the group, and the clock synchronization service of the group means that a non-master clock member in the group needs to synchronize the clock with the master clock member in the group; The application function receives a response from the network, wherein the response is used to indicate that the network accepts the request for the clock synchronization service of the group.

24. The method according to claim 23, characterized in that The group information is also used to indicate that the master clock member is a first terminal, and the non-master clock members in the group include at least one second terminal.

25. The method according to claim 23 or 24, characterized in that The group information is carried in the group clock synchronization creation request message.

26. The method according to any one of claims 23 to 25, characterized in that The group information is further used to indicate that the master clock member is changed to the first terminal, and / or the group information is further used to indicate that newly added non-master clock members in the group include the second terminal.

27. The method according to any one of claims 23 to 26, characterized in that The group information is carried in the group update request message.

28. A communication method, characterized in that: include: The clock synchronization network element receives group information, wherein the group information is used to request a clock synchronization service of the group, The clock synchronization network element initiates, creates, or updates a clock synchronization service for the group according to the group information.

29. The method according to claim 28, characterized in that The clock synchronization network element receives group information, including: The clock synchronization network element receives a group clock synchronization creation request message from an application function, wherein the group clock synchronization creation request message carries the group information, and the group information is also used to indicate that the master clock member is the first terminal, and / or the non-master clock members in the group include the second terminal.

30. The method according to claim 28, characterized in that The clock synchronization network element receives group information, including: The clock synchronization network element receives the group information from the data management network element, and the group information is also used to indicate that the master clock member is changed to the first terminal, and / or the group information is also used to indicate that the newly added non-master clock members in the group include the second terminal.

31. The method according to any one of claims 27 to 30, characterized in that The clock synchronization network element receives the group information from the data management network element, including: The clock synchronization network element subscribes to the group information change notification from the data management network element; The clock synchronization network element receives the group change information from the data management network element.

32. A communication device, characterized in that: The apparatus comprises: a module for executing the method as claimed in any one of claims 1-31.

33. A communication device, characterized in that: The communication device comprises: a processor and a memory; the memory is used to store computer instructions, and when the processor executes the instructions, the communication device executes the method according to any one of claims 1-31.

34. A computer-readable storage medium, characterized in that: The computer-readable storage medium comprises a computer program or instructions, and when the computer program or instructions are executed on a computer, the computer is caused to perform the method according to any one of claims 1 to 31.

Images