CN113472467A

CN113472467A - Clock synchronization method, device and system

Info

Publication number: CN113472467A
Application number: CN202010237466.9A
Authority: CN
Inventors: 刘涛; 陈健; 周毅
Original assignee: China Telecom Corp Ltd
Current assignee: China Telecom Corp Ltd
Priority date: 2020-03-30
Filing date: 2020-03-30
Publication date: 2021-10-01

Abstract

The disclosure relates to a clock synchronization method, a clock synchronization device, a clock synchronization system and a computer-readable storage medium, and relates to the technical field of networks. The clock synchronization method comprises the following steps: responding to the fact that the terminal of the Internet of things exits the power saving mode to prepare for executing the periodic service, and obtaining the duration of the terminal of the Internet of things in the power saving mode; and sending a message for clock synchronization of the Internet of things terminal to the Internet of things terminal under the condition that the duration is greater than a preset threshold value. According to the method and the device, the clock synchronization of the terminal of the Internet of things is realized, and meanwhile, the equipment cost and the energy consumption cost of the terminal of the Internet of things are reduced.

Description

Clock synchronization method, device and system

Technical Field

The present disclosure relates to the field of network technologies, and in particular, to a clock synchronization method, apparatus, and system, and a computer-readable storage medium.

Background

NB-IoT (Narrow Band Internet of Things) is one of the Internet of Things wireless communication standards established by 3GPP (3rd Generation Partnership Project). The clock synchronization is applied to numerous applications of NB-IOT, and particularly, the terminal equipment of the Internet of things executing periodic service has certain requirements on time precision. When the periodic service is executed each time, the local time of the terminal side of the internet of things needs to be consistent with the current network time, so that the next periodic service can be normally executed in the expected time.

However, because the terminal of the internet of things is limited by volume and cost, the crystal clock with low precision is generally adopted, so that the clock and the network time are not synchronous after the terminal runs for a long time, and the time precision of the terminal of the internet of things executing the periodic service cannot be guaranteed. For example, a single day of operation may produce several minutes of error.

The error may cause that the terminal of the internet of things cannot execute the periodic service on time, so that the application platform cannot accurately count the communication behavior of the terminal of the internet of things. The error can also cause confusion of the originally realized service discrete mechanism of the terminal of the internet of things, thereby causing network congestion.

In the related art, a terminal side of the internet of things is modified, for example, a more accurate crystal clock is adopted.

Disclosure of Invention

The inventor thinks that: in the correlation technology, the terminal side of the Internet of things is improved, and the equipment cost and the energy consumption of the terminal of the Internet of things are high.

In view of the above technical problems, the present disclosure provides a solution, which reduces the equipment cost and the energy consumption cost of the terminal of the internet of things while realizing the clock synchronization of the terminal of the internet of things.

According to a first aspect of the present disclosure, there is provided a clock synchronization method, including: responding to the fact that the terminal of the Internet of things exits the power saving mode to prepare for executing the periodic service, and obtaining the duration of the terminal of the Internet of things in the power saving mode; and sending a message for clock synchronization of the Internet of things terminal to the Internet of things terminal under the condition that the duration is greater than a preset threshold value.

In some embodiments, the obtaining the duration that the terminal of the internet of things is in the power saving mode includes: in response to receiving an attachment request signaling from an internet of things terminal, inquiring whether the attachment receiving signaling comprises a specific parameter, wherein the specific parameter is used for identifying that the internet of things terminal supports a power saving mode; starting a timer in response to receiving a terminal context release request signaling from a base station in case that the attach accept signaling includes a specific parameter; the method comprises the steps of responding to a specific request signaling received from an Internet of things terminal, obtaining the value of a timer as the duration of the Internet of things terminal in a power saving mode, wherein the specific request signaling is a specific signaling sent when the Internet of things terminal exits the power saving mode and prepares to execute periodic service when exiting the power saving mode.

In some embodiments, the specific parameter is a T3324 parameter, and the specific request signaling is control plane service request signaling.

In some embodiments, the timer is a software timer.

In some embodiments, the obtaining the duration that the terminal of the internet of things is in the power saving mode further includes: in response to receiving an attachment request signaling from the terminal of the internet of things, sending the attachment accepting signaling to the terminal of the internet of things; and before receiving a terminal context release request signaling from a base station, responding to an attachment completion signaling received from the Internet of things terminal, and sending a message for the Internet of things terminal to perform clock synchronization to the Internet of things terminal.

In some embodiments, the preset threshold is 20 hours.

In some embodiments, the clock synchronization method is performed by a mobility management entity, MME.

In some embodiments, the message for clock synchronization of the terminal of the internet of things is an evolved packet system mobility management EMM message.

According to a second aspect of the present disclosure, there is provided a clock synchronization apparatus including: the system comprises an acquisition module, a processing module and a processing module, wherein the acquisition module is configured to respond to the fact that the terminal of the Internet of things exits a power saving mode to prepare for executing periodic services, and acquire the duration of the terminal of the Internet of things in the power saving mode; the sending module is configured to send a message for clock synchronization of the terminal of the internet of things to the terminal of the internet of things under the condition that the duration is greater than a preset threshold.

In some embodiments, the clock synchronization means is a mobility management entity MME.

According to a third aspect of the present disclosure, there is provided a clock synchronization apparatus comprising: a memory; and a processor coupled to the memory, the processor configured to perform the clock synchronization method of any of the above embodiments based on instructions stored in the memory.

According to a fourth aspect of the present disclosure, there is provided a clock synchronization system including the clock synchronization apparatus of any of the above embodiments.

In some embodiments, the clock synchronization system further comprises: and the Internet of things terminal is configured to receive the message for the Internet of things terminal to perform clock synchronization from the clock synchronization device and perform clock synchronization by using the message for the Internet of things terminal to perform clock synchronization.

In some embodiments, the clock synchronization using the message for clock synchronization of the terminal of the internet of things includes: calculating local time by using the message for the Internet of things terminal to perform clock synchronization; and performing clock synchronization according to the local time.

In some embodiments, wherein the internet of things terminal is further configured to: sending an attach request signaling to the clock synchronization apparatus; receiving an attach accept signaling from the clock synchronization apparatus; after the attachment is finished, sending an attachment finishing signal to the clock synchronization device; after the data service is completed, sending a Radio Resource Control (RRC) release signaling to a base station; responding to the terminal of the internet of things exiting the power saving mode to prepare for executing the periodic service, and sending a specific request signaling to the clock synchronization device, wherein the specific request signaling is a specific signaling sent when the terminal of the internet of things exits the power saving mode and prepares for executing the periodic service, and the data service comprises the periodic service.

In some embodiments, wherein the internet of things terminal is further configured to: after the clock synchronization is finished, the periodic service is interactively executed with the clock synchronization device; and after the periodic service is completed, sending an RRC release signaling to the base station.

In some embodiments, the clock synchronization system further comprises: a base station configured to transmit a terminal context release request to the clock synchronization apparatus according to the RRC release signaling.

According to a fifth aspect of the present disclosure, there is provided a computer-storable medium having stored thereon computer program instructions which, when executed by a processor, implement the clock synchronization method of any of the above embodiments.

In the embodiment, the clock synchronization of the terminal of the internet of things is realized, and the equipment cost and the energy consumption cost of the terminal of the internet of things are reduced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

The present disclosure may be more clearly understood from the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 illustrates a flow diagram of a clock synchronization method according to some embodiments of the present disclosure;

fig. 2 illustrates a signaling diagram of a clock synchronization method according to some embodiments of the present disclosure;

FIG. 3 illustrates a block diagram of a clock synchronization apparatus in accordance with some embodiments of the present disclosure;

FIG. 4 shows a block diagram of a clock synchronization apparatus according to further embodiments of the present disclosure;

FIG. 5 illustrates a block diagram of a clock synchronization system in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates a block diagram of a computer system for implementing some embodiments of the present disclosure.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise.

Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

Fig. 1 illustrates a flow diagram of a clock synchronization method according to some embodiments of the present disclosure.

As shown in fig. 1, the clock synchronization method includes step S110 and step S120. The clock synchronization method is performed, for example, by an MME (Mobility Management Entity).

In step S110, in response to the internet of things terminal exiting the Power Saving Mode to prepare for executing the periodic service, a duration that the internet of things terminal is in the Power Saving Mode (PSM) is obtained. For example, the internet of things terminal is an NB-IoT terminal.

In step S120, when the duration is greater than the preset threshold, a message for performing clock synchronization on the terminal of the internet of things is sent to the terminal of the internet of things. In some embodiments, the message used for the terminal of the internet of things to perform clock synchronization is an EMM message (Evolved Packet System Mobility Management). EMM messages include, for example, local time zone, world coordination time, and daylight saving time. In some embodiments, the preset threshold is 20 hours. Generally, the clock error of the terminal of the internet of things is small within 20 hours.

In some embodiments, when the duration is less than or equal to the preset threshold, a message for performing clock synchronization by the terminal of the internet of things does not need to be sent to the terminal of the internet of things. Under the condition, the terminal of the Internet of things basically has no time error, and does not need to carry out clock synchronization.

In the above embodiment, when the terminal of the internet of things exits the power saving mode to prepare for executing the periodic service, the time length that the terminal of the internet of things is in the power saving mode is acquired, and under the condition that the time length is greater than the preset threshold value, a message for the terminal of the internet of things to perform clock synchronization is sent to the terminal of the internet of things, so that the clock synchronization of the terminal of the internet of things is realized, the side of the terminal of the internet of things is not required to be transformed, the equipment cost of the terminal of the internet of things is reduced, a more accurate crystal clock is not required to be adopted, and the energy consumption cost of the terminal of the internet of things is reduced. In addition, the clock synchronization method disclosed by the invention is suitable for the on-line applicable Internet of things terminal due to no need of modifying the terminal, and has strong universality.

In addition, the clock synchronization of the terminal of the internet of things is triggered only when the terminal of the internet of things exits the power saving mode to prepare for executing the periodic service, so that the signaling overhead of the network side is reduced.

For example, the method for acquiring the duration of the terminal of the internet of things in the power saving mode in response to the terminal of the internet of things exiting the power saving mode in step S110 of fig. 1 to prepare to execute the periodic service is implemented as follows.

First, in response to receiving an Attach Request (Attach Request) signaling from an internet of things terminal, it is queried whether an Attach Accept (Attach Accept) signaling includes a specific parameter. The specific parameters are used for identifying that the terminal of the Internet of things supports a power saving mode. For example, the specific parameter is a T3324 parameter. Whether the received attachment signaling comprises the specific parameters or not is inquired, and whether the terminal of the Internet of things supports the power saving mode or not can be judged more accurately compared with the inquiry of the attachment request signaling.

In some embodiments, the obtaining the duration that the terminal of the internet of things is in the power saving mode further includes: and sending an attachment accepting signaling to the terminal of the Internet of things in response to receiving the attachment request signaling from the terminal of the Internet of things. For example, whether the attach receiving signaling includes the specific parameter may be queried before the attach receiving signaling is sent to the terminal of the internet of things, whether the attach receiving signaling includes the specific parameter may be queried after the attach receiving signaling is sent to the terminal of the internet of things, and whether the attach receiving signaling includes the specific parameter may be simultaneously performed.

Then, in case that the attach accept signaling includes a specific parameter, a timer is started in response to receiving a terminal Context Release request (UE Context Release request) signaling from the base station. For example, the timer is a software timer. The hardware cost of the network side can be reduced by adopting a software timer mode.

In some embodiments, after receiving the attach accept signaling, the terminal of the internet of things sends an RRC (Radio Resource Control) Release (RRC Release) signaling to the base station, and the base station sends a terminal context Release request signaling in response to receiving the RRC Release signaling from the terminal of the internet of things.

For example, after receiving the attach accept signaling, the terminal of the internet of things executes an attach procedure. And after the terminal of the Internet of things finishes the attachment process, sending an attachment Complete (Attach Complete) signaling. In some embodiments, the obtaining the duration that the terminal of the internet of things is in the power saving mode further includes: and before receiving a terminal context release request signaling from the base station, responding to an attachment completion signaling received from the Internet of things terminal, and sending a message for performing clock synchronization on the Internet of things terminal to the Internet of things terminal. For example, after the terminal of the internet of things completes attachment, clock synchronization is performed according to a message for performing clock synchronization on the terminal of the internet of things, so as to perform a data service. Data traffic includes, but is not limited to, periodic traffic. And after the terminal of the Internet of things completes the data service, the RRC release signaling is sent to the base station, and the base station responds to the RRC release signaling from the terminal of the Internet of things and sends a terminal context release request signaling.

And finally, responding to a specific request signaling received from the terminal of the Internet of things, and acquiring the value of the timer as the duration of the terminal of the Internet of things in the power saving mode. The specific request signaling is specific signaling sent by the terminal of the internet of things to exit the power saving mode and prepare to execute periodic service when the terminal of the internet of things exits the power saving mode. For example, the specific Request signaling is Control Plane Service Request (Control Plane Service Request) signaling.

Fig. 2 illustrates a signaling diagram of a clock synchronization method according to some embodiments of the present disclosure.

As shown in fig. 2, the clock synchronization method includes steps S201 to S222.

In step S201, the terminal of the internet of things and the base station interactively establish an RRC connection.

In step S202, after establishing RRC connection with the base station, the terminal of the internet of things sends an attach request signaling to the base station.

In step S203, the base station forwards an attach request signaling from the terminal of the internet of things to the MME.

In step S204, the MME transmits an attach accept signaling to the base station in accordance with the attach request signaling from the base station.

In step S205, the MME inquires whether the T3324 parameter is included in the attach accept signaling. In case the T3324 parameter is included in the attach accept signaling, step S206-step S214 are performed. In the case where the T3324 parameter is not included in the acceptance of the attachment signaling, step S206 to step S213 are performed. For example, step S205 may be performed before step S204, step S205 may be performed after step S204, and step S205 may be performed simultaneously with step S204.

In step S206, the base station forwards the attach accept signaling from the MME to the internet of things terminal.

In step S207, after completing the attachment process according to the attachment receiving signaling from the base station, the terminal of the internet of things sends an attachment completion signaling to the base station.

In step S208, the base station forwards an attach complete signaling from the terminal of the internet of things to the MME.

In step S209, in response to receiving the attach complete signaling from the base station, the MME sends an EMM message to the internet of things terminal.

In step S210, the terminal of the internet of things performs clock synchronization according to the EMM message.

In step S211, the terminal of the internet of things and the MME interact to perform a data service. For example, the data traffic includes periodic traffic, communication traffic, and the like.

In step S212, the terminal of the internet of things sends an RRC release signaling to the base station when the data service is completed.

In step S213, the base station sends a terminal context release request signaling to the MME in response to receiving the RRC release signaling from the terminal of the internet of things.

In step S214, the MME starts a timer in response to receiving the terminal context release request signaling from the base station. At this time, the terminal of the internet of things may enter a power saving mode. After the timer is started, the timer starts to count time.

In response to the internet of things terminal exiting the power saving mode to prepare for performing the periodic service, the internet of things terminal performs step S215. In step S215, the terminal of the internet of things and the base station interactively establish an RRC connection.

In step S216, after establishing RRC connection with the base station, the terminal of the internet of things sends a control panel service request signaling to the MME. At this time, the terminal of the internet of things exits the power saving mode and prepares to execute the periodic service when exiting the power saving mode.

In the case where the T3324 parameter is included in the attach accept signaling, the execution proceeds to step S217. In step S217, a value of the timer is obtained as a duration of the terminal of the internet of things being in the power saving mode. For example, after the value of the timer is obtained, a zero clearing operation is performed on the timer for subsequent re-timing.

In case the value of the timer is greater than the preset threshold, the steps S218 to S222 are performed.

In step S218, the MME sends an EMM message to the internet of things terminal.

In step S219, the terminal of the internet of things performs clock synchronization according to the EMM message.

In step S220, the terminal of the internet of things and the MME interactively execute a periodic service.

In step S221, after the terminal of the internet of things completes the periodic service, an RRC release signaling is sent to the base station.

In step S222, the base station sends a terminal context release request signaling to the MME in response to receiving the RRC release signaling from the terminal of the internet of things.

In the case where the value of the timer is less than or equal to the preset threshold value, the steps S220 to S222 are directly performed without performing the steps S218 and S219.

For example, the clock synchronization method further includes step S223. Step S223 is executed after step S222. In case the MME receives the terminal context release request signaling from the base station, step S223 is performed. In step S223, the MME starts a timer. The MME counts again after starting the timer, and then circularly executes the steps similar to the steps S215-S222, thereby realizing the continuous clock synchronization of the terminal of the Internet of things and ensuring that the local time is synchronized with the network time when the terminal of the Internet of things executes periodic services each time.

Fig. 3 illustrates a block diagram of a clock synchronization apparatus according to some embodiments of the present disclosure.

As shown in fig. 3, the clock synchronization apparatus 31 includes an acquisition module 311 and a transmission module 312. For example, the clock synchronization apparatus is an MME.

The obtaining module 311 is configured to, in response to the internet of things terminal exiting the power saving mode to prepare to execute the periodic service, obtain a duration that the internet of things terminal is in the power saving mode, for example, execute step S110 shown in fig. 1.

The sending module 312 is configured to send a message for clock synchronization of the terminal of the internet of things to the terminal of the internet of things if the duration is greater than the preset threshold, for example, to execute step S120 shown in fig. 1.

FIG. 4 illustrates a block diagram of a clock synchronization apparatus according to further embodiments of the present disclosure.

As shown in fig. 4, the clock synchronizing means 41 includes a memory 411; and a processor 412 coupled to the memory 411. The memory 411 is used for storing instructions for executing the corresponding embodiments of the clock synchronization method. The processor 412 is configured to perform a clock synchronization method in any of the embodiments of the present disclosure based on instructions stored in the memory 411.

Fig. 5 illustrates a block diagram of a clock synchronization system according to some embodiments of the present disclosure.

As shown in fig. 5, the clock synchronization system 5 includes a clock synchronization apparatus 51 in any of the embodiments of the present disclosure.

In some embodiments, the clock synchronization system 5 further includes an internet of things terminal 52. The terminal 52 of the internet of things is configured to receive the message for clock synchronization of the terminal of the internet of things from the clock synchronization device and perform clock synchronization using the message for clock synchronization of the terminal of the internet of things. For example, the local time is calculated by using a message for performing clock synchronization by the terminal of the internet of things, and then clock synchronization is performed according to the local time.

In some embodiments, the internet of things terminal 52 is further configured to: sending an attach request signaling to the clock synchronization means 51; receiving an attach accept signaling from the clock synchronization means 51; after the attachment is completed, an attachment completion signal is sent to the clock synchronization device 51; after the data service is completed, sending an RRC release signaling to the base station 53; in response to the internet of things terminal 52 exiting the power saving mode in preparation for performing the periodic service, a specific request signaling is sent to the clock synchronization device 51. The specific request signaling is specific signaling sent by the terminal of the internet of things to exit the power saving mode and prepare to execute periodic service when the terminal of the internet of things exits the power saving mode. Data traffic includes, but is not limited to, periodic traffic.

In some embodiments, the internet of things terminal 52 is further configured to: after the clock synchronization is completed, the periodic service is executed interactively with the clock synchronization device 51; after the periodic service is completed, an RRC release signaling is sent to the base station 53.

In some embodiments, the clock synchronization system 5 further comprises a base station 53. The base station 53 is configured to send a terminal context release request to the clock synchronization means 51 according to RRC release signalling.

As shown in FIG. 6, computer system 60 may take the form of a general purpose computing device. Computer system 60 includes a memory 610, a processor 620, and a bus 600 that connects the various system components.

The memory 610 may include, for example, system memory, non-volatile storage media, and the like. The system memory stores, for example, an operating system, an application program, a Boot Loader (Boot Loader), and other programs. The system memory may include volatile storage media such as Random Access Memory (RAM) and/or cache memory. The non-volatile storage medium stores, for instance, instructions to perform corresponding embodiments of at least one of the clock synchronization methods. Non-volatile storage media include, but are not limited to, magnetic disk storage, optical storage, flash memory, and the like.

The processor 620 may be implemented as discrete hardware components, such as a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gates or transistors, or the like. Accordingly, each of the modules, such as the judging module and the determining module, may be implemented by a Central Processing Unit (CPU) executing instructions in a memory for performing the corresponding step, or may be implemented by a dedicated circuit for performing the corresponding step.

Bus 600 may use any of a variety of bus architectures. For example, bus structures include, but are not limited to, Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, and Peripheral Component Interconnect (PCI) bus.

Computer system 60 may also include input-output interface 630, network interface 640, storage interface 650, and the like. These

interfaces

630, 640, 650 and the memory 610 and the processor 620 may be connected by a bus 600. The input/output interface 630 may provide a connection interface for input/output devices such as a display, a mouse, and a keyboard. The network interface 640 provides a connection interface for various networking devices. The storage interface 650 provides a connection interface for external storage devices such as a floppy disk, a usb disk, and an SD card.

Various aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable apparatus to produce a machine, such that the execution of the instructions by the processor results in an apparatus that implements the functions specified in the flowchart and/or block diagram block or blocks.

These computer-readable program instructions may also be stored in a computer-readable memory that can direct a computer to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and/or block diagram block or blocks.

The present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects.

By the clock synchronization method, the clock synchronization device, the clock synchronization system and the computer storage medium in the embodiments, the clock synchronization of the terminal of the internet of things is realized, and the equipment cost and the energy consumption cost of the terminal of the internet of things are reduced.

Thus far, clock synchronization methods, apparatuses and systems, computer-readable storage media according to the present disclosure have been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. It will be fully apparent to those skilled in the art from the foregoing description how to practice the presently disclosed embodiments.

Claims

1. A method of clock synchronization, comprising:

responding to the fact that the terminal of the Internet of things exits the power saving mode to prepare for executing the periodic service, and obtaining the duration of the terminal of the Internet of things in the power saving mode;

and sending a message for clock synchronization of the Internet of things terminal to the Internet of things terminal under the condition that the duration is greater than a preset threshold value.

2. The clock synchronization method according to claim 1, wherein the obtaining of the duration that the internet of things terminal is in the power saving mode comprises:

in response to receiving an attachment request signaling from an internet of things terminal, inquiring whether the attachment receiving signaling comprises a specific parameter, wherein the specific parameter is used for identifying that the internet of things terminal supports a power saving mode;

starting a timer in response to receiving a terminal context release request signaling from a base station in case that the attach accept signaling includes a specific parameter;

the method comprises the steps of responding to a specific request signaling received from an Internet of things terminal, obtaining the value of a timer as the duration of the Internet of things terminal in a power saving mode, wherein the specific request signaling is a specific signaling sent when the Internet of things terminal exits the power saving mode and prepares to execute periodic service when exiting the power saving mode.

3. The clock synchronization method according to claim 2, wherein the specific parameter is a T3324 parameter and the specific request signaling is a control plane service request signaling.

4. The clock synchronization method of claim 2, wherein the timer is a software timer.

5. The clock synchronization method according to claim 2, wherein the obtaining of the duration of the terminal of the internet of things in the power saving mode further comprises:

in response to receiving an attachment request signaling from the terminal of the internet of things, sending the attachment accepting signaling to the terminal of the internet of things;

and before receiving a terminal context release request signaling from a base station, responding to an attachment completion signaling received from the Internet of things terminal, and sending a message for the Internet of things terminal to perform clock synchronization to the Internet of things terminal.

6. The clock synchronization method according to claim 1, wherein the preset threshold is 20 hours.

7. The clock synchronization method according to any of claims 1 to 6, wherein said clock synchronization method is performed by a mobility management entity, MME.

8. The clock synchronization method according to any one of claims 1 to 6, wherein the message for clock synchronization of the terminal of the Internet of things is an evolved packet System mobility management (EMM) message.

9. A clock synchronization apparatus, comprising:

the system comprises an acquisition module, a processing module and a processing module, wherein the acquisition module is configured to respond to the fact that the terminal of the Internet of things exits a power saving mode to prepare for executing periodic services, and acquire the duration of the terminal of the Internet of things in the power saving mode;

the sending module is configured to send a message for clock synchronization of the terminal of the internet of things to the terminal of the internet of things under the condition that the duration is greater than a preset threshold.

10. The clock synchronization apparatus of claim 9, wherein the clock synchronization apparatus is a Mobility Management Entity (MME).

11. A clock synchronization apparatus, comprising:

a memory; and

a processor coupled to the memory, the processor configured to perform the clock synchronization method of any of claims 1 to 8 based on instructions stored in the memory.

12. A clock synchronization system comprising:

a clock synchronization device as claimed in any one of claims 9 to 11.

13. The clock synchronization system of claim 12, further comprising:

and the Internet of things terminal is configured to receive the message for the Internet of things terminal to perform clock synchronization from the clock synchronization device and perform clock synchronization by using the message for the Internet of things terminal to perform clock synchronization.

14. The clock synchronization system of claim 13, wherein clock synchronization with the message for clock synchronization with the internet of things terminal comprises:

calculating local time by using the message for the Internet of things terminal to perform clock synchronization;

and performing clock synchronization according to the local time.

15. The clock synchronization system of claim 13, wherein the internet of things terminal is further configured to:

sending an attach request signaling to the clock synchronization apparatus;

receiving an attach accept signaling from the clock synchronization apparatus;

after the attachment is finished, sending an attachment finishing signal to the clock synchronization device;

after the data service is completed, sending a Radio Resource Control (RRC) release signaling to a base station;

responding to the terminal of the internet of things exiting the power saving mode to prepare for executing the periodic service, and sending a specific request signaling to the clock synchronization device, wherein the specific request signaling is a specific signaling sent when the terminal of the internet of things exits the power saving mode and prepares for executing the periodic service, and the data service comprises the periodic service.

16. The clock synchronization system of claim 13, wherein the internet of things terminal is further configured to:

after the clock synchronization is finished, the periodic service is interactively executed with the clock synchronization device;

and after the periodic service is completed, sending an RRC release signaling to the base station.

17. The clock synchronization system of claim 15 or 16, further comprising:

a base station configured to transmit a terminal context release request to the clock synchronization apparatus according to the RRC release signaling.

18. A computer-storable medium having stored thereon computer program instructions which, when executed by a processor, implement the clock synchronization method of any one of claims 1 to 8.