CN117015024A

CN117015024A - Time synchronization method, network equipment and communication system

Info

Publication number: CN117015024A
Application number: CN202210468563.8A
Authority: CN
Inventors: 宋毅; 万华春; 梅杰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-04-29
Filing date: 2022-04-29
Publication date: 2023-11-07

Abstract

The embodiment of the application discloses a time synchronization method which is used for high-precision multi-domain time synchronization in a 5G scene. The method of the embodiment of the application comprises the following steps: the method comprises the steps that first network equipment sends a first time synchronization message to second network equipment, wherein the first time synchronization message carries first time synchronization information and is used for determining second time synchronization information; the first network device receives a second time synchronization message sent by the second network device, wherein the second time synchronization message is used for determining third time synchronization information and fourth time synchronization information; the first network device sends a third time synchronization message to the second network device, carries the fourth time synchronization information, and based on the three time synchronization messages, can realize time synchronization between the first time domain of the second network device and the first time domain of the first network device, so that network bandwidth occupation can be reduced, and synchronization success rate can be improved.

Description

Time synchronization method, network equipment and communication system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a time synchronization method, a network device, and a communications system.

Background

The fifth generation mobile communication technology (5th generation mobile communication technology,5G) network is a new generation broadband mobile communication technology with high rate, low latency and large connectivity features. The precision clock synchronization protocol standard (1588 protocol for short) of the network measurement and control system defines a precision time synchronization protocol (precision time protocol, PTP) to meet the high-precision multi-domain time synchronization requirement of 5G.

And a master-slave synchronization system in 1588 protocol adopts four time synchronization messages (Sync message, follow_Up message, delay_Req message and delay_Resp message) to acquire time stamps of t1, t2, t3 and t4 to realize time synchronization.

In the existing time synchronization method, when a Sync message is sent, a media access control (medium access control, MAC) layer of a master node stamps a timestamp, and the timestamp is transmitted back to a PTP protocol layer, and then a Follow_Up message sends the recorded timestamp of t1 to a slave node. Because there is a delay for the t1 timestamp to be transmitted back to the PTP layer by the master node MAC layer, if the delay is long, the time synchronization will fail probabilistically.

Disclosure of Invention

In view of this, the present application provides a time synchronization method for performing multi-domain time synchronization, which can reduce network bandwidth occupation and improve synchronization success rate.

In a first aspect, the present application provides a time synchronization method, including: a first network device sends a first time synchronization message to a second network device, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates a sending time of the first time synchronization message under a first time domain of the first network device, a receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device; the first network device receives a second time synchronization message sent by the second network device, wherein the sending moment of the second time synchronization message under the first time domain of the second network device is used for determining third time synchronization information, and the receiving moment of the second time synchronization message under the first time domain of the first network device is used for determining fourth time synchronization information; the first network device sends a third time synchronization message to the second network device, wherein the third time synchronization message carries the fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information are used for time synchronization between a first time domain of the second network device and a first time domain of the first network device.

According to the scheme provided by the application, the first time synchronization message is carried in the first time synchronization message sent to the second network device, so that the first time synchronization message is not required to be transmitted to the second network device through one time synchronization message, time synchronization between the first time domain of the second network device and the first time domain of the first network device can be realized based on three time synchronization messages, and the network bandwidth occupation can be reduced due to the reduction of transmission of one time synchronization message.

In a possible implementation manner of the first aspect, the first time synchronization information includes a first timestamp, and the method further includes: the first network device determines the first timestamp, wherein the first timestamp is a sending time of the first time synchronization message under a first time domain of the first network device.

According to the scheme provided by the application, the first time stamp can be determined by the first network device, and then the first time stamp is carried by the first time synchronization message, so that the second network device can acquire the first time stamp and the second time stamp based on one time synchronization message, one time synchronization message can be reduced, and network bandwidth occupation is reduced.

In a possible implementation manner of the first aspect, the determining, by the first network device, the first timestamp includes: the first network device determines the first timestamp according to a first deviation and a first time, wherein the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time is a sending time of the first time synchronization message under the local time domain of the first network device.

The scheme provided by the application can be used for obtaining the first timestamp by the first network equipment specifically based on the first deviation and the first time, and the first time synchronization message sent by the PTP module of the first network equipment to the MAC module can carry the first deviation, wherein the first time is the sending time of the first time synchronization message under the local time domain of the first network equipment, and the MAC module is used for stamping and obtaining after the PTP module of the first network equipment sends the first time synchronization message to the MAC module to indicate the sending time of the first time synchronization message under the local time domain of the first network equipment.

In a possible implementation manner of the first aspect, the first timestamp is carried in an originTimestamp field and a correctionField field of the first time synchronization packet; or, the first time synchronization message includes an extended field, and the first timestamp is carried in the extended field.

The scheme provided by the application provides two specific implementation modes for sending the first time stamp, wherein the first implementation mode carries the first time stamp through the conventional origintime stamp field and the correlation field of the first time synchronization message, and the first time stamp cannot be carried independently because of the limited length of a single field, so that the first time stamp can be carried through the two fields. In a second implementation manner, the first time synchronization packet includes an extended field, where the extended field may specifically be a TLV field specified by a protocol, and the TLV field may carry information of a complete first timestamp.

In a possible implementation manner of the first aspect, the first time synchronization information includes a first deviation and a first time instant, the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time instant is a sending time instant of the first time synchronization message under the local time domain of the first network device.

According to the scheme provided by the application, the first time synchronization information comprises the first deviation and the first moment, the first time synchronization message carries the first deviation and the first moment, and the second network device can calculate and obtain the first timestamp based on the first deviation and the first moment. This approach may reduce the computational burden on the first network device, which is a viable implementation.

In a possible implementation manner of the first aspect, the first time synchronization packet includes an extended field, where the extended field carries the first offset and the first time instant; or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

In a second aspect, the present application provides a time synchronization method, which is characterized in that the method includes: the method comprises the steps that a second network device receives a first time synchronization message, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network device, the receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device; the second network device sends a second time synchronization message to the first network device, wherein the second time synchronization message is used for determining third time synchronization information at the sending moment of a first time domain of the second network device, and the second time synchronization message is used for determining fourth time synchronization information at the receiving moment of the first time domain of the first network device; the second network device receives a third time synchronization message sent by the first network device, wherein the third time synchronization message carries the fourth time synchronization information; the second network device realizes time synchronization between the first time domain of the second network device and the first time domain of the first network device according to the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information.

According to the scheme provided by the application, the first time synchronization message sent by the first network equipment carries the first time synchronization information, and the second network equipment does not need to acquire the first time synchronization information through one time synchronization message, so that the time synchronization between the first time domain of the second network equipment and the first time domain of the first network equipment can be realized based on three time synchronization messages.

In a possible implementation manner of the second aspect, the first time synchronization information includes a first timestamp, where the first timestamp is a transmission time of the first time synchronization packet in a first time domain of the first network device.

According to the scheme provided by the application, the first time synchronization message can directly carry the first time stamp, and the second network equipment directly obtains the first time synchronization message, so that the subsequent calculation process is consistent with the prior art, and the scheme is easy to realize in a floor mode.

In a possible implementation manner of the second aspect, the originTimestamp field and the corlectionfield field of the first time synchronization packet carry the first timestamp; or, the first time synchronization message includes an extended field, where the extended field carries the first timestamp.

In a possible implementation manner of the second aspect, the first time synchronization information includes a first deviation and a first time instant, the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time instant is a sending time instant of the first time synchronization message under the local time domain of the first network device.

According to the scheme provided by the application, the first time synchronization message can carry the first deviation and the first moment, the second network equipment can acquire the first time stamp through simple calculation, and the subsequent time synchronization process is consistent with the existing calculation method, so that the method is simple and easy to realize.

In a possible implementation manner of the second aspect, the first time synchronization packet includes an extended field, where the extended field carries the first offset and the first time instant; or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

In a possible implementation manner of the second aspect, the method further includes: and the second network equipment determines a first time stamp according to the first deviation and the first time, wherein the first time stamp is the sending time of the first time synchronization message under the first time domain of the first network equipment.

According to the scheme provided by the application, if the second network equipment acquires the first deviation and the first time, the first time stamp is also needed to be calculated, and the subsequent time synchronization process is consistent with the existing calculation method, so that the method is simple and easy to realize.

In a third aspect, the present application provides a network device, the device comprising: the receiving and transmitting module is used for sending a first time synchronization message to the second network equipment, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network equipment, the receiving time of the first time synchronization message under the first time domain of the second network equipment is used for determining second time synchronization information, and the first network equipment is upstream time synchronization equipment of the second network equipment; the transceiver module is further configured to receive a second time synchronization packet sent by the second network device, where a sending time of the second time synchronization packet in a first time domain of the second network device is used to determine third time synchronization information, and a receiving time of the second time synchronization packet in a first time domain of the first network device is used to determine fourth time synchronization information; the transceiver module is further configured to send a third time synchronization packet to the second network device, where the third time synchronization packet carries the fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information, and the fourth time synchronization information are used for time synchronization between the first time domain of the second network device and the first time domain of the first network device.

In a possible implementation manner of the third aspect, the first time synchronization information includes a first timestamp, and the apparatus further includes: and the determining module is used for determining the first timestamp, wherein the first timestamp is the sending moment of the first time synchronization message under the first time domain of the first network equipment.

In a possible implementation manner of the third aspect, the determining module is specifically configured to: and determining the first timestamp according to a first deviation and a first moment, wherein the first deviation is the deviation between a first time domain of the first network equipment and a local time domain of the first network equipment, and the first moment is the sending moment of the first time synchronization message under the local time domain of the first network equipment.

In a possible implementation manner of the third aspect, the first timestamp is carried in an originTimestamp field and a correctionField field of the first time synchronization packet; or, the first time synchronization message includes an extended field, and the first timestamp is carried in the extended field.

In a possible implementation manner of the third aspect, the first time synchronization information includes a first deviation and a first time instant, the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time instant is a sending time instant of the first time synchronization message under the local time domain of the first network device.

In a possible implementation manner of the third aspect, the first time synchronization packet includes an extended field, where the extended field carries the first offset and the first time instant; or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

In a fourth aspect, the present application provides a time synchronization apparatus, the apparatus comprising: the receiving and transmitting module is used for receiving a first time synchronization message, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network device, the receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device; the transceiver module is further configured to send a second time synchronization packet to the first network device, where the second time synchronization packet is used to determine third time synchronization information at a sending time of a first time domain of the second network device, and the second time synchronization packet is used to determine fourth time synchronization information at a receiving time of the first time domain of the first network device; the transceiver module is further configured to receive a third time synchronization packet sent by the first network device, where the third time synchronization packet carries the fourth time synchronization information; and the synchronization module is used for realizing time synchronization between the first time domain of the second network equipment and the first time domain of the first network equipment according to the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information.

In a possible implementation manner of the fourth aspect, the first time synchronization information includes a first timestamp, where the first timestamp is a transmission time of the first time synchronization packet in a first time domain of the first network device.

In a possible implementation manner of the fourth aspect, the originTimestamp field and the corlectionfield field of the first time synchronization packet carry the first timestamp; or, the first time synchronization message includes an extended field, where the extended field carries the first timestamp.

In a possible implementation manner of the fourth aspect, the first time synchronization information includes a first deviation and a first moment, where the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first moment is a sending moment of the first time synchronization message under the local time domain of the first network device.

In a possible implementation manner of the fourth aspect, the first time synchronization packet includes an extended field, where the extended field carries the first offset and the first time instant; or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

In a possible implementation manner of the fourth aspect, the apparatus further includes: and the determining module is used for determining a first time stamp according to the first deviation and the first time, wherein the first time stamp is the sending time of the first time synchronization message under the first time domain of the first network equipment.

In a fifth aspect, the present application provides a network device comprising: a memory having computer readable instructions stored therein;

a processor coupled to the memory, the computer readable instructions, when executed by the processor, cause the network device to perform the method of the first aspect and any of the various possible implementations.

In a sixth aspect, the present application provides a network device, comprising: a memory having computer readable instructions stored therein; a processor coupled to the memory, the computer readable instructions, when executed by the processor, cause the network device to perform the method of the second aspect and any of the various possible implementations.

In a seventh aspect, the present application provides a computer program product comprising instructions, comprising computer readable instructions, which when run on a processor, cause the processor to perform the method according to any of the first aspect, the second aspect and any of the various possible implementations described above.

In an eighth aspect, the present application provides a computer readable storage medium having instructions stored therein which, when run on a processor, cause the processor to perform the method of the first aspect, the second aspect and any of a variety of possible implementations.

In a ninth aspect, the present application provides a chip comprising a processor. The processor is configured to read and execute a computer program stored in the memory to perform the method in any of the possible implementations of any of the aspects described above. Optionally, the chip includes a memory, and the memory and the processor are connected to the memory through a circuit or a wire. Further optionally, the chip further comprises a communication interface, and the processor is connected to the communication interface. The communication interface is used for receiving data and/or information to be processed, and the processor acquires the data and/or information from the communication interface, processes the data and/or information and outputs a processing result through the communication interface. The communication interface may be an input-output interface.

In a tenth aspect, the present application provides a communication system comprising a first network device for performing the method as in the first aspect and any of the various possible implementations, and a second network device for performing the method as in the second aspect and any of the various possible implementations.

The technical effects of any implementation manner of the third aspect, the fourth aspect, the fifth aspect, the sixth aspect, the seventh aspect, the eighth aspect, the ninth aspect and the tenth aspect may refer to the technical effects of the corresponding implementation manner of the first aspect or the second aspect, and are not described herein.

Compared with the prior art that the time synchronization is carried out through four time synchronization messages, the time synchronization method provided by the application can reduce the occupation of network bandwidth. In addition, because the first time synchronization information and the second time synchronization information are acquired through the first time synchronization message, the probability synchronization failure problem caused when the first time synchronization information is transmitted through another time synchronization message after being returned by the first network equipment is avoided.

Drawings

Fig. 1 is an application scenario architecture diagram of a time synchronization method according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a time synchronization method;

FIG. 3 is a flow chart of a process for transmitting a t1 time stamp;

FIG. 4 is a schematic diagram of an embodiment of a time synchronization method according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an embodiment of acquiring t1 and t2 according to an embodiment of the present application;

FIG. 6 is a schematic diagram of another embodiment of acquiring t1 and t2 according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a message structure of a Sync message in the time synchronization method according to the embodiment of the present application;

FIG. 8 is a schematic diagram of a time synchronization scheme according to an embodiment of the present application;

FIG. 9 is a schematic diagram of an embodiment of a network device according to an embodiment of the present application;

FIG. 10 is a schematic diagram of another embodiment of a network device according to an embodiment of the present application;

fig. 11 is a schematic diagram of another embodiment of a network device according to an embodiment of the present application.

Detailed Description

The application provides a time synchronization method which is used for performing multi-domain time synchronization, can reduce network bandwidth occupation and improves synchronization success rate.

Embodiments of the present application will now be described with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the present application. As one of ordinary skill in the art can know, with the development of technology and the appearance of new scenes, the technical scheme provided by the embodiment of the application is also applicable to similar technical problems.

The terms first, second and the like in the description and in the claims and in the above-described figures, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be implemented in other sequences than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules that are expressly listed or inherent to such process, method, article, or apparatus. The naming or numbering of the steps in the present application does not mean that the steps in the method flow must be executed according to the time/logic sequence indicated by the naming or numbering, and the execution sequence of the steps in the flow that are named or numbered may be changed according to the technical purpose to be achieved, so long as the same or similar technical effects can be achieved.

Embodiments of the present application are described below with reference to the accompanying drawings. As one of ordinary skill in the art can know, with the development of technology and the appearance of new scenes, the technical scheme provided by the embodiment of the application is also applicable to similar technical problems.

The following describes an application scenario architecture of a time synchronization method in an embodiment of the present application, and please refer to fig. 1 and fig. 2, which are an application scenario architecture diagram of a time synchronization method in an embodiment of the present application.

As shown in fig. 1, an application scenario of the time synchronization method provided by the embodiment of the present application includes:

the first network device 100 and the second network device 200 are connected through a 5G network, may be a direct connection or a relay connection through other network devices, and it should be noted that, in order to achieve high-precision synchronization, the first network device 100 needs to be directly connected to the second network device 200. In the case where the first network device 100 is an upstream time synchronization device of the second network device 200, in implementing time synchronization of the communication system, the second network device 200 needs to implement time synchronization with the first network device 100, specifically, in the 5G communication network system, high-precision multi-domain time synchronization is required, that is, the first network device 100 maintains a plurality of client time domains, similarly, the second network device 200 also maintains a plurality of client time domains, each of the plurality of client time domains of the second network device 200 corresponds to one of the plurality of client time domains of the first network device 100, and time synchronization is required between the corresponding time domains. Specifically, the first network device 100 may be a network device such as a base station or a router, and the specific device type is not limited herein. The second network device 200 may also be a network device such as a base station or a router, and the specific device type is not limited herein.

In a 5G communication network system, high accuracy multi-domain time synchronization is required, and a detailed analysis is performed with reference to fig. 1 and 2.

Based on the application scenario shown in fig. 1, a specific process of obtaining time stamps of t1, t2, t3 and t4 to achieve time synchronization by using four time synchronization messages (Sync message, follow_up message, delay_req message and delay_resp message) in the existing standard is described below. Referring to fig. 2, a master node corresponds to the first network device 100 in fig. 1, and a slave node corresponds to the second network device 200 in fig. 1.

1) The master node sends a Sync message (short for Sync message) to the slave node, and the sending time of the Sync message is marked as a first time stamp (timestamp 1, t 1), and it should be noted that the time when the t1 indicates that the Sync message exits from the port of the master node device is obtained by adding a compensation value to the stamping time, and the specific implementation process is not described herein. The moment when the Sync message is received from the node is marked as a second timestamp (timestamp 2, t 2), and similarly, t2 indicates the moment when the Sync message enters the slave node device port;

2) The master node sends a Follow_Up message (called Follow_Up message for short) to the slave node, wherein the Follow_Up message carries recorded t1;

3) The slave node sends a delay_req message to the master node, the time of the slave node sending the delay_req message is a third timestamp (timestamp 3, t 3), and the time of the master node receiving the delay_req message is recorded as a fourth timestamp (timestamp 4, t 4);

4) The master node sends a delay_resp message (abbreviated as delay_resp message) to the slave node, wherein the delay_resp message carries recorded t4.

Since in the 5G communication network system, the node needs to maintain multiple time domains, the multiple time domains of the master and slave nodes need to be synchronized respectively. Illustratively, the 4 client time domains of the master node are RTC0, RTC1, RTC2 and RTC3, respectively, the Common time domain of the master node is rtc_common, which is configured by the system CPU for providing a bias reference for the plurality of client time domains, wherein RTC0, RTC1, RTC2 and RTC3 are maintained in the form of a bias from rtc_common (delta_rtc), delta_rtci=rtci=rtci_rtc, i=0 to 3), representing the difference between the i-th time domain and the local time domain of the node. i is Domain value information (Domain Number) corresponding to multiple domains, and RTCi represents an ith time Domain.

In the following description, taking the calculation process of the time synchronization in the first time domain (RTC 0) as an example, t1, t2, t3 and t4 are respectively:

t1＝t1_Common+Delta_RTC_m

t2＝t2_Common+Delta_RTC_s

t3＝t3_Common+Delta_RTC_s

t4＝t4_Common+Delta_RTC_m

wherein, t1_Common and t4_Common are from the local time domain of the master node, t2_Common and t3_Common are from the local time domain of the slave node, delta_RTC_m is the difference between RTC0 of the master node and RTC_Common of the master node, and Delta_RTC_s is the difference between RTC0 of the slave node and RTC_Common of the slave node.

According to t1, t2, t3 and t4, the offset between the slave node RTC0 and the master node RTC0 is calculated as:

offset＝(t2-t1)-delay

wherein delay= [ (t 2-t 1) + (t 4-t 3) ]/2

The slave node can realize time synchronization with the master node at RTC0 based on the value of offset.

Referring to fig. 3, a specific flow of transmitting a t1 time stamp to a slave node by a master node in a Two-step mode in the prior art will be described. The Master node comprises a 1588 message and a protocol stack module (Master_PTP) for processing the time stamp, and a high-precision time stamp generating module (Master_MAC), wherein a Sync message sent by the Master_PTP reaches the Master_MAC to generate a t1_Common time stamp, the t1_Common is transmitted back to the Master_PTP, the Master_PTP determines a corresponding Delta_RTCi according to the value of the DomainNumber, the Delta_RTCi is added by the t1_Common to obtain a final t1 time stamp, and the t1 time stamp is carried to the Slave network element through the Follow_UP message.

Since the Two-step mode generation of the T1 and T2 time stamps is completed in cooperation with the Sync message and the Follow_Up message, the Two messages increase the bandwidth used, and in addition, the Two-step mode has a requirement on the time stamp return path delay of the T1_common. For example: if master_mac generates a highly accurate t1_common timestamp in 8+24 format (8 bit fraction ns+24bit integer NS), then the latency of the backhaul path is required to be less than 10.144256ms. If the delay of the backhaul path is greater than 10.144256ms, a probabilistic failure of the time synchronization will result.

In view of the above, the embodiments of the present application provide a time synchronization method and a network device, which are used for reducing bandwidth waste in a time synchronization process and avoiding synchronization failure caused by backhaul delay.

Referring to fig. 4, an embodiment of the present application proposes a time synchronization method 400. The method 400 may be applied in the scenario shown in fig. 1, where in the application scenario shown in fig. 1, the first network device corresponds to the first network device 100 shown in fig. 1, and the second network device corresponds to the second network device 200 shown in fig. 1. The method 400 comprises steps S401-S403.

S401, a first network device sends a first time synchronization message to a second network device;

the first network device is an upstream time synchronization device of the second network device, the first time domain of the second network device corresponds to the first time domain of the first network device, and the first time domain of the second network device needs to be time synchronized with the first time domain of the first network device.

The first network device sends a first time synchronization message to the second network device. Illustratively, the first time synchronization message is a sync message. The first time synchronization message carries first time synchronization information, and the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network device. The time of receipt of the first time synchronization message in the first time domain of the second network device is used to determine second time synchronization information.

As a specific implementation manner, the first network device uses the first time synchronization message Wen Fasong to implement the first time synchronization information.

Mode 1: the first time synchronization information is a first timestamp (i.e. t 1), and t1 is a sending time of the first time synchronization message in a first time domain of the first network device. The first network device carries a first timestamp in a first time synchronization message. Optionally, an originTimestamp field and a correctionField field of the first time synchronization packet carry a first timestamp; alternatively, the first timestamp is carried in a field of the first time synchronization packet extension, for example, a TLV (type-length-value) field. It should be noted that, due to the two available fields existing in the first time synchronization packet: an origninistamp field and a correctionField field can be used to carry a first timestamp, and since the number of bytes the orignnistamp field can carry is 10 bytes, the number of bytes the correctionField can carry is 8 bytes, the first timestamp is 96 bits (bits), i.e. 12 bytes, where 48 bits high is second information (unit: seconds), 32 bits middle is integer Nanosecond (NS) information (unit: nanoseconds), and 16 bits low is fractional NS information (unit: 1/(16 th) nanoseconds). The single field cannot carry the complete first timestamp information, so the two fields of originTimestamp and correctionField respectively carry part of the contents of the first timestamp information.

Mode 2: the first time synchronization information is a first deviation (delta_rtc0) and a first time (t1_common), the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time is a sending time of the first time synchronization message under the local time domain of the first network device. The first network device carries a first offset and a first time in the first time synchronization message, optionally, a field of the first time synchronization message extension, for example, a TLV field carries the first offset and the first time; alternatively, the originTimestamp field and the corectionfield field of the first time synchronization message carry the first time, and the fields of the first time synchronization message extension, for example, the TLV field, carry the first offset. The second network device may calculate t1 according to the difference between the first time and the first deviation.

S402, the first network equipment receives a second time synchronization message sent by the second network equipment;

the first network equipment receives a second time synchronization message sent by the second network equipment, wherein the time information of the second time synchronization message sent by the second network equipment is third time synchronization information, and the time information of the second time synchronization message received by the first network equipment is fourth time synchronization information;

S403, the first network device sends a third time synchronization message to the second network device.

The first network device sends a third time synchronization message to the second network device, wherein the third time synchronization message carries the fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information are used for realizing time synchronization between the second network device and the first network device.

In one possible implementation manner, the first time synchronization information is t1, the second time synchronization information is t2, the third time synchronization information is t3, the fourth time synchronization information is t4, and the time synchronization between the first time domain of the second network device and the first time domain of the first network device is implemented according to t1, t2, t3 and t4, and the specific calculation method may refer to the existing calculation flow and is not described herein again.

It should be noted that, the time synchronization between each client time domain in the second network device and the corresponding time domain in the first network device may be implemented through the methods of S401-S403, which are not described herein.

It should be noted that, in practical application, when the second network device performs frequency synchronization through t1 and t2, the first time synchronization message provided in the embodiment of the present application may also be applied to obtain t1 and t2 simultaneously. The subsequent calculation process after t1 and t2 are obtained may refer to the existing calculation method, and will not be described herein.

The time synchronization method provided by the application realizes high-precision multi-domain time synchronization in the 5G network equipment through three time synchronization messages, and can reduce network bandwidth occupation compared with the time synchronization carried out through four time synchronization messages in the prior art. In addition, because the first time synchronization information and the second time synchronization information are acquired through the first time synchronization message, the probability synchronization failure problem caused when the first time synchronization information is transmitted through another time synchronization message after being returned by the first network equipment is avoided.

From the above description, in the time synchronization method provided by the embodiment of the present application, the first time synchronization information and the second time synchronization information can be obtained only through the first time synchronization message.

The two modes of sending the first time synchronization information by the master node are described below with reference to fig. 5 to fig. 6, and two specific modes of obtaining the t1 time stamp and the t2 time stamp in the time synchronization method provided by the embodiment of the application are described.

Mode one: t1 is carried directly by the sync message. Referring to fig. 5, a master node (master) corresponds to the first network device 100 shown in fig. 1, and a slave node (slave) corresponds to the second network device 200 shown in fig. 1. The process of acquiring t1 and t2 in the time synchronization procedure between the first time domain RTC0 of the second network device 200 and the first time domain RTC0 of the first network device 100 is described below, and the process includes steps S501-S504.

S501, a Master_PTP module sends a Sync message.

The master_ptp module sends out a Sync message, and the Sync message carries the delta_rtci value, or sends the delta_rtci value to the master_mac module of the Master media access control (medium access control, MAC) layer through other signaling.

Optionally, a TLV field is added at the end of the message according to the protocol extension, where the TLV field stores the delta_rtci value (delta_rtci is the difference of RTCi minus rtc_common, i=0 to 3). Reference may be made to the schematic diagram of the Sync message corresponding to step S501.

S502, the Sync message reaches a Master_MAC module.

When the Sync message arrives at the master_mac module, the stamping will generate t1_command.

And the Master_MAC module calculates t1 of the client domain according to the Delta_RTCi and the t1_Common carried by the Sync message.

There are several ways to send t 1:

in one possible implementation, t1 is carried in the originTimestamp field and the correctionField field of the Sync message and sent to the slave network element. In this implementation, the Sync message may retain the TLV field, or the extended TLV field may be stripped, which may refer to the schematic diagram of the Sync message corresponding to step S502.

In another possible implementation manner, the TLV field extended by the Sync message carries t1 and sends it to the slave network element.

S503, the Sync message reaches the slave_MAC module.

And (3) stamping the Sync message arrival time to obtain t2_common, and sending the t2_common to the slave_PTP module.

S504, the Sync message reaches the slave_PTP module.

The Sync message reaches the slave_ptp module, and the slave_ptp module obtains t1, and in addition, the flow of obtaining t2 is consistent with the prior art, which is not described herein.

Mode two: the first time and the first offset are carried by the sync message. Referring to fig. 6, a master node (master) corresponds to the first network device 100 shown in fig. 1, and a slave node (slave) corresponds to the second network device 200 shown in fig. 1. The following describes a procedure for acquiring t1 and t2 in the time synchronization procedure between the first time domain RTC1 of the second network device 200 and the first time domain RTC1 of the first network device 100, including steps S601-S604.

S601, a Master_PTP module sends a Sync message.

The Master_PTP module sends out a Sync message, and the Sync message carries a Delta_RTCi value, or sends the Delta_RTCi value to the Master_MAC module through other signaling.

Optionally, a TLV field is added at the end of the message according to the protocol extension, where the TLV field stores the delta_rtci value (delta_rtci is the difference of RTCi minus rtc_common, i=0 to 3). Reference may be made to the schematic diagram of the Sync message corresponding to step S601.

S602, the Sync message reaches a Master_MAC module.

There are several ways in which the master_mac module sends the first time synchronization information to the slave:

the master sends a first time (t1_common) and a first deviation (delta_RTCi) to the slave, and the slave node can calculate t1 based on the obtained t1_common and delta_RTCi.

There are several ways to send t1_common and Delta_RTCi:

in one possible implementation, t1_Common is placed in the originTimestamp field and the correctionField field; and adding a TLV field according to protocol extension at the tail part of the Sync message, and storing a Delta_RTCi value in the TLV field. Reference may be made to the schematic diagram of the Sync message corresponding to step S602.

In another possible implementation, a TLV field is added at the end of the Sync message by protocol extension, and t1_common and delta_rtci are stored in the TLV field.

S603, the Sync message reaches the slave_MAC module.

S604, the Sync message reaches the slave_PTP module.

The Sync message reaches the slave_ptp module, and the slave_ptp module calculates t1 through delta_rtci and t1_common, and the flow of obtaining t2 is consistent with the prior art, which is not described herein.

Referring to fig. 7, a schematic diagram of a message structure of a Sync message in the time synchronization method according to the embodiment of the present application is shown, where a format requirement of the message may refer to an existing standard, and a Sync message field possibly related to the time synchronization method according to the embodiment of the present application includes a correction field 701 and an originimestamp field 702, and further may extend a TLV field 703 according to a standard specification.

To clearly show the difference of the inventive scheme from the specific procedure of the prior art of fig. 2 for obtaining the four time stamps t1, t2, t3 and t4. Fig. 8 is a schematic diagram of a time synchronization scheme according to an embodiment of the application.

1) The time of the Sync message sent by the master node to the slave node is recorded as t1, and the time synchronization information indicating t1 is carried in the Sync message in the form of t1 or t1_Common+Delta_RTCi. The moment when the Sync message is received by the slave node is marked as t2, and t1 and t2 can be obtained by receiving the Sync message by the slave node;

2) The slave node sends a delay_req message to the master node, the time when the slave node sends the delay_req message is t3, and the time when the master node receives the delay_req message is recorded as t4;

3) The master node sends a delay_resp message to the slave node, wherein the delay_resp message carries recorded t4.

Thus, the slave node can acquire t1, t2, t3 and t4 based on the Sync message, the delay_Req message and the delay_Resp message. The subsequent calculation process is consistent with the existing calculation mode, and will not be described here again.

The time synchronization method provided by the present application is described above, and the time synchronization device for implementing the time synchronization method is described below, referring to fig. 9, which is a schematic diagram of an embodiment of the time synchronization device in an embodiment of the present application.

The network device includes:

the transceiver module 901 is configured to send a first time synchronization packet to a second network device, where the first time synchronization packet carries first time synchronization information, where the first time synchronization information indicates a sending time of the first time synchronization packet in a first time domain of the first network device, and a receiving time of the first time synchronization packet in the first time domain of the second network device is used to determine the second time synchronization information, where the first network device is an upstream time synchronization device of the second network device;

the transceiver module 901 is further configured to receive a second time synchronization packet sent by the second network device, where a sending time of the second time synchronization packet in a first time domain of the second network device is used to determine third time synchronization information, and a receiving time of the second time synchronization packet in the first time domain of the first network device is used to determine fourth time synchronization information;

The transceiver module 901 is further configured to send a third time synchronization packet to the second network device, where the third time synchronization packet carries fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information, and the fourth time synchronization information are used for time synchronization between the first time domain of the second network device and the first time domain of the first network device.

In one possible implementation, the first time synchronization information includes a first timestamp, and the apparatus further includes: a determining module 902, configured to determine the first timestamp, where the first timestamp is a sending time of the first time synchronization message in a first time domain of the first network device.

In one possible implementation, the determining module 902 is specifically configured to: and determining the first timestamp according to a first deviation and a first moment, wherein the first deviation is the deviation between a first time domain of the first network equipment and a local time domain of the first network equipment, and the first moment is the sending moment of the first time synchronization message under the local time domain of the first network equipment.

In one possible implementation manner, the first timestamp is carried in an originTimestamp field and a correctionField field of the first time synchronization message; or, the first time synchronization message includes an extended field, and the first timestamp is carried in the extended field.

In one possible implementation manner, the first time synchronization information includes a first deviation and a first time, where the first deviation is a deviation between a first time domain of the first network device and a local time domain of the first network device, and the first time is a sending time of the first time synchronization message under the local time domain of the first network device.

In one possible implementation manner, the first time synchronization packet includes an extended field, where the extended field carries the first offset and the first time instant; or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

The network device provided in the embodiment of the present application is used to implement the time synchronization method described in the foregoing embodiment, and specific implementation processes and beneficial effects are not described herein. It should be understood that the above division of the units of the network is merely a division of a logic function, and may be fully or partially integrated into a physical entity or may be physically separated when actually implemented. And these units may all be implemented in the form of software calls through the processing element; or can be realized in hardware; it is also possible that part of the units are implemented in the form of software, which is called by the processing element, and part of the units are implemented in the form of hardware.

For example, the above units may be one or more integrated circuits configured to implement the above methods, such as: one or more specific integrated circuits (application specific integrated circuit, ASIC), or one or more microprocessors (digital singnal processor, DSP), or one or more field programmable gate arrays (field programmable gate array, FPGA), or the like. For another example, when a unit above is implemented in the form of a processing element scheduler, the processing element may be a general purpose processor, such as a central processing unit (central processing unit, CPU) or other processor that may invoke the program. For another example, the units may be integrated together and implemented in the form of a system-on-a-chip (SOC).

Referring to fig. 10, another embodiment of a time synchronization apparatus according to an embodiment of the application is shown.

The network device includes:

the transceiver module 1001 is configured to receive a first time synchronization packet, where the first time synchronization packet carries first time synchronization information, the first time synchronization information indicates a sending time of the first time synchronization packet in a first time domain of a first network device, and a receiving time of the first time synchronization packet in the first time domain of a second network device is used to determine second time synchronization information, where the first network device is an upstream time synchronization device of the second network device;

The transceiver module 1001 is further configured to send a second time synchronization packet to the first network device, where the second time synchronization packet is used to determine third time synchronization information at a sending time of a first time domain of the second network device, and the second time synchronization packet is used to determine fourth time synchronization information at a receiving time of the first time domain of the first network device;

the transceiver module 1001 is further configured to receive a third time synchronization packet sent by the first network device, where the third time synchronization packet carries fourth time synchronization information;

the synchronization module 1002 is configured to implement time synchronization between the first time domain of the second network device and the first time domain of the first network device according to the first time synchronization information, the second time synchronization information, the third time synchronization information, and the fourth time synchronization information.

In one possible implementation, the first time synchronization information includes a first timestamp, where the first timestamp is a transmission time of the first time synchronization message in a first time domain of the first network device.

In one possible implementation manner, the originTimestamp field and the correctionField field of the first time synchronization packet carry the first timestamp; or, the first time synchronization message includes an extended field, where the extended field carries the first timestamp.

In one possible implementation, the apparatus further includes: a determining module 1003, configured to determine a first timestamp according to the first deviation and the first time, where the first timestamp is a sending time of the first time synchronization packet in a first time domain of the first network device.

Referring to fig. 11, another embodiment of a network device according to an embodiment of the present application is shown;

the network device provided in this embodiment may be an electronic device such as a base station or a router, and the specific device configuration is not limited in the embodiment of the present application.

The network device 1100 may vary widely in configuration or performance and may include one or more processors 1101 and memory 1102, with programs or data stored in the memory 1102.

The memory 1102 may be volatile or nonvolatile storage, among other things. The processor 1101 is optionally one or more central processing units (central processing unit, CPU), which may be a single core CPU or a multi-core CPU. The processor 1101 may be in communication with the memory 1102, executing a series of instructions in the memory 1102 on the network device 1100.

The network device 1100 also includes one or more wired or wireless network interfaces 1103, such as an ethernet interface.

Optionally, although not shown in fig. 11, the network device 1100 may also include one or more power sources; the input/output interface may be used to connect a display, a mouse, a keyboard, a touch screen device, a sensing device, or the like, and the input/output interface may be an optional component, may or may not be present, and is not limited herein.

The flow executed by the processor 1101 in the network device 1100 in this embodiment may refer to the method flow described in the foregoing method embodiment, and will not be described herein.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.

The embodiment of the application also provides a chip which comprises a processor. The processor is configured to read and execute the computer program stored in the memory to perform the method in any of the possible implementations described above. Optionally, the chip includes a memory, and the memory and the processor are connected to the memory through a circuit or a wire. Further optionally, the chip further comprises a communication interface, and the processor is connected to the communication interface. The communication interface is used for receiving data and/or information to be processed, and the processor acquires the data and/or information from the communication interface, processes the data and/or information and outputs a processing result through the communication interface. The communication interface may be an input-output interface.

The embodiment of the application also provides a communication system, which comprises a first network device and a second network device, wherein the first network device is used for executing any one of the possible implementation modes, and the second network device is used for executing any one of the possible implementation modes.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of time synchronization, the method comprising:

a first network device sends a first time synchronization message to a second network device, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates a sending time of the first time synchronization message under a first time domain of the first network device, a receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device;

the first network device receives a second time synchronization message sent by the second network device, wherein the sending moment of the second time synchronization message under the first time domain of the second network device is used for determining third time synchronization information, and the receiving moment of the second time synchronization message under the first time domain of the first network device is used for determining fourth time synchronization information;

the first network device sends a third time synchronization message to the second network device, wherein the third time synchronization message carries the fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information are used for time synchronization between a first time domain of the second network device and a first time domain of the first network device.

2. The method of claim 1, wherein the first time synchronization information comprises a first timestamp, the method further comprising:

the first network device determines the first timestamp, wherein the first timestamp is a sending time of the first time synchronization message under a first time domain of the first network device.

3. The method of claim 2, wherein the first network device determining the first timestamp comprises:

the first network device determines the first timestamp according to a first deviation and a first time, wherein the first deviation is the deviation between a first time domain of the first network device and a public time domain of the first network device, and the first time is the sending time of the first time synchronization message under the local time domain of the first network device.

4. The method of claim 2 or 3, wherein the first timestamp is carried in an originTimestamp field and a corectionfield field of the first time synchronization message;

or, the first time synchronization message includes an extended field, and the first timestamp is carried in the extended field.

5. The method of claim 1, wherein the first time synchronization information comprises a first offset between a first time domain of the first network device and a local time domain of the first network device and a first time instant at which the first time synchronization message is sent under the local time domain of the first network device.

6. The method of claim 5, wherein the first time synchronization message includes an extended field carrying the first offset and the first time instant;

or, the originTimestamp field and the corectionfield field of the first time synchronization packet carry the first time, and the first time synchronization packet includes an extended field, where the extended field carries the first offset.

7. A method of time synchronization, the method comprising:

the method comprises the steps that a second network device receives a first time synchronization message, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network device, the receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device;

The second network device sends a second time synchronization message to the first network device, wherein the second time synchronization message is used for determining third time synchronization information at the sending moment of a first time domain of the second network device, and the second time synchronization message is used for determining fourth time synchronization information at the receiving moment of the first time domain of the first network device;

the second network device receives a third time synchronization message sent by the first network device, wherein the third time synchronization message carries the fourth time synchronization information;

the second network device realizes time synchronization between the first time domain of the second network device and the first time domain of the first network device according to the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information.

8. The method of claim 7, wherein the first time synchronization information comprises a first timestamp, and wherein the second network device receiving the first time synchronization message comprises:

the second network device receives a first time synchronization message carrying the first time stamp, wherein the first time stamp is the sending time of the first time synchronization message in a first time domain of the first network device.

9. The method of claim 8, wherein the step of determining the position of the first electrode is performed,

the originTimestamp field and the correctionField field of the first time synchronization message carry the first timestamp;

or, the first time synchronization message includes an extended field, where the extended field carries the first timestamp.

10. The method of claim 7, wherein the first time synchronization information comprises a first offset between a first time domain of the first network device and a local time domain of the first network device and a first time instant at which the first time synchronization message is sent under the local time domain of the first network device.

11. The method of claim 10, wherein the first time synchronization message includes an extended field carrying the first offset and the first time instant;

12. The method according to claim 10 or 11, characterized in that the method further comprises:

and the second network equipment determines a first time stamp according to the first deviation and the first time, wherein the first time stamp is the sending time of the first time synchronization message under the first time domain of the first network equipment.

13. A network device, the network device comprising:

the receiving and transmitting module is used for sending a first time synchronization message to the second network equipment, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network equipment, the receiving time of the first time synchronization message under the first time domain of the second network equipment is used for determining second time synchronization information, and the first network equipment is upstream time synchronization equipment of the second network equipment;

the transceiver module is further configured to receive a second time synchronization packet sent by the second network device, where a sending time of the second time synchronization packet in a first time domain of the second network device is used to determine third time synchronization information, and a receiving time of the second time synchronization packet in a first time domain of the first network device is used to determine fourth time synchronization information;

The transceiver module is further configured to send a third time synchronization packet to the second network device, where the third time synchronization packet carries the fourth time synchronization information, and the first time synchronization information, the second time synchronization information, the third time synchronization information, and the fourth time synchronization information are used for time synchronization between the first time domain of the second network device and the first time domain of the first network device.

14. The network device of claim 13, wherein the first time synchronization information comprises a first timestamp, the network device further comprising:

and the determining module is used for determining the first timestamp, wherein the first timestamp is the sending moment of the first time synchronization message under the first time domain of the first network equipment.

15. The network device of claim 14, wherein the determining module is specifically configured to:

and determining the first timestamp according to a first deviation and a first moment, wherein the first deviation is the deviation between a first time domain of the first network equipment and a local time domain of the first network equipment, and the first moment is the sending moment of the first time synchronization message under the local time domain of the first network equipment.

16. The network device according to claim 14 or 15, wherein the first timestamp is carried in an originTimestamp field and a corectionfield field of the first time synchronization message;

17. The network device of claim 13, wherein the first time synchronization information comprises a first offset between a first time domain of the first network device and a local time domain of the first network device and a first time instant at which the first time synchronization message is sent under the local time domain of the first network device.

18. The network device of claim 17, wherein the first time synchronization message comprises an extended field carrying the first offset and the first time instant;

19. A network device, the network device comprising:

the receiving and transmitting module is used for receiving a first time synchronization message, wherein the first time synchronization message carries first time synchronization information, the first time synchronization information indicates the sending time of the first time synchronization message under the first time domain of the first network device, the receiving time of the first time synchronization message under the first time domain of the second network device is used for determining second time synchronization information, and the first network device is upstream time synchronization equipment of the second network device;

the transceiver module is further configured to send a second time synchronization packet to the first network device, where the second time synchronization packet is used to determine third time synchronization information at a sending time of a first time domain of the second network device, and the second time synchronization packet is used to determine fourth time synchronization information at a receiving time of the first time domain of the first network device;

the transceiver module is further configured to receive a third time synchronization packet sent by the first network device, where the third time synchronization packet carries the fourth time synchronization information;

And the synchronization module is used for realizing time synchronization between the first time domain of the second network equipment and the first time domain of the first network equipment according to the first time synchronization information, the second time synchronization information, the third time synchronization information and the fourth time synchronization information.

20. The network device of claim 19, wherein the first time synchronization information comprises a first timestamp, the first timestamp being a time of transmission of the first time synchronization message in a first time domain of the first network device.

21. The network device of claim 20, wherein an originTimestamp field and a correctionField field of the first time synchronization message carry the first timestamp;

22. The network device of claim 19, wherein the first time synchronization information comprises a first offset between a first time domain of the first network device and a local time domain of the first network device and a first time instant at which the first time synchronization message is sent under the local time domain of the first network device.

23. The network device of claim 22, wherein the first time synchronization message comprises an extended field carrying the first offset and the first time instant;

24. The network device according to claim 22 or 23, characterized in that the network device further comprises:

and the determining module is used for determining a first time stamp according to the first deviation and the first time, wherein the first time stamp is the sending time of the first time synchronization message under the first time domain of the first network equipment.

25. A network device, comprising:

a memory having computer readable instructions stored therein;

a processor coupled to the memory, the computer readable instructions, when executed by the processor, cause the network device to implement the method of any one of claims 1 to 12.

26. A computer program product comprising computer readable instructions which, when run on a processor, cause the processor to perform the method of any of claims 1 to 12.

27. A computer readable storage medium having instructions stored therein which, when executed on a processor, cause the processor to perform the method of any one of claims 1 to 12.

28. A communication system comprising a first network device for performing the method of any of claims 1 to 6 and a second network device for performing the method of any of claims 7 to 12.