WO2021082674A1

WO2021082674A1 - Time synchronization method, communication device, and system

Info

Publication number: WO2021082674A1
Application number: PCT/CN2020/111117
Authority: WO
Inventors: 罗俊; 蒋志平; 孟凡顺; 李江; 孙春
Original assignee: 华为技术有限公司
Priority date: 2019-10-31
Filing date: 2020-08-25
Publication date: 2021-05-06
Also published as: CN112751639B; CN112751639A

Abstract

The present application relates to a time synchronization method, a communication device, and a system. A second device receives a first optical signal having a first wavelength that is sent by a first device over a first optical fiber, the moment for sending the first optical signal being t1, and the moment for receiving the first optical signal being t2, and the second devices sends a second optical signal having a second wavelength to the first device over the first optical fiber, the moment for sending the second optical signal being t3, and the moment for receiving the second optical signal being t4; the second device receives a third optical signal having the second wavelength that is sent by the first device over a second optical fiber, the moment for sending the third optical signal being t5, and the moment for receiving the third optical signal being t6, and the second devices sends a fourth optical signal having the first wavelength to the first device over the second optical fiber, the moment for sending the fourth optical signal being t7, and the moment for receiving the fourth optical signal being t8; the second device performs time synchronization with the first device according to t1, t2, t3, t4, t5, t6, t7, and t8.

Description

Time synchronization method, communication equipment and system

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China, the application number is 201911053055.8, and the invention title is "time synchronization method, communication equipment and system" on October 31, 2019, the entire content of which is incorporated by reference In this application.

Technical field

This application relates to the field of communications, and in particular to a method, communication device and system for time synchronization.

Background technique

In communication networks, the normal operation of services sometimes requires network time synchronization, that is, the time difference between network devices is kept within a reasonable error level. The 1588V2 protocol is a precise time synchronization protocol, referred to as the precision time protocol (PTP), which can realize the time synchronization of multiple network devices.

The 1588V2 protocol can synchronize the time of the receiving end device with the time of the sending end device through the combination of software and hardware. The stamping point can be defined in the protocol stack. In the receiving device that needs to be synchronized, when the PTP message passes the stamping point, a timestamp is generated, and the timestamp is carried in the message, and calculated by the message exchange with the sending device The time offset is compensated to realize the time synchronization between the receiving end device and the sending end device.

The time delay measurement methods in the prior art include one-way measurement and two-way measurement. If one-way measurement is performed between node A and node B, the one-way delay from node A to node B can be measured, and the one-way delay from node B to node A can also be measured. If a two-way service strategy is implemented for node A and node B, the time delay from node A to node B and then to node A can be measured, or the time delay from node B to node A and then to node B can be measured.

Time synchronization is based on the equal delay of the transceiver link between node A and node B. If the two-way delay is completely symmetrical, that is, the delay from node A to node B and the delay from node B to node A are the same, there will be no Introduce synchronization error; if the delay of the transceiver link between node A and node B is asymmetric, that is, the delays from node A to node B and node B to node A are not the same, synchronization error will be introduced. Since the physical links and wavelengths of two-way time stamp transmission may be different, it is difficult to achieve two-way delay symmetry. The time synchronization error introduced by the two-way delay asymmetry is generally on the order of tens of nanoseconds. In the future, the requirements for time synchronization accuracy of base stations are getting higher and higher. In order to achieve high-precision time synchronization, a time synchronization method, communication equipment and system are urgently needed to eliminate or reduce the error caused by the unequal delay of the transceiver link. .

Summary of the invention

In view of this, the embodiments of the present application provide a time synchronization method, communication device, and system, which are used to improve the accuracy of time synchronization in a communication network.

In the first aspect, this application discloses a time synchronization method, including:

The second communication device receives the first optical signal of the first wavelength sent by the first communication device on the first optical fiber, the first optical signal carries a first time stamp, and the first time stamp instructs the first communication device to send the first light The time of the signal is the first time t1; the second communication device generates a second time stamp, and the second time stamp indicates that the time when the second communication device receives the first optical signal is the second time t2; the second communication device communicates with the first The device sends the second optical signal with the second wavelength on the first optical fiber, the second communication device generates a third time stamp, and the third time stamp indicates that the time when the second communication device sends the second optical signal is the third time t3; The second communication device receives the fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates that the time when the first communication device receives the second optical signal is the fourth time t4;

The second communication device receives a third optical signal with a wavelength of the second wavelength sent by the first communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp instructs the first communication device to send the third light The time of the signal is the fifth time t5; the second communication device generates a sixth time stamp, and the sixth time stamp indicates that the time when the second communication device receives the third optical signal is the sixth time t6; the second communication device communicates with the first The device sends a fourth optical signal with a wavelength of the first wavelength on the second optical fiber, the second communication device generates a seventh time stamp, and the seventh time stamp indicates that the time when the second communication device sends the fourth optical signal is the seventh time t7; The second communication device receives the eighth time stamp sent by the first communication device on the second optical fiber, where the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8;

The second communication device communicates with the first communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8. Time synchronization.

In a possible implementation manner, the above-mentioned second communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the first time t1. The time synchronization with the first communication device at eight time t8 includes:

The second communication device determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4;

The second communication device determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8;

The second communication device determines the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation; the second communication device performs time synchronization with the first communication device according to the time deviation N.

In a possible implementation manner, the above-mentioned second communication device determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4, including: the first deviation N1 satisfies the calculation formula: N1 =[(t2-t1)-(t4-t3)]/2;

The above-mentioned second communication device determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8, including: the first deviation N2 satisfies the calculation formula: N2=[(t6-t5)- (t8-t7)]/2;

The above-mentioned second communication device determines the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation, including: the time deviation N satisfies the calculation formula: N=(N1+N2)/2.

In a possible implementation manner, the above-mentioned time synchronization method further includes: the second communication device determines the approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, and the approximate synchronization error S1 is the first deviation The difference between N1 and the time deviation N.

In a possible implementation manner, the above-mentioned time synchronization method further includes: the second communication device determines the approximate synchronization error S2 of the two-way delay on the second optical fiber according to the time deviation N and the second deviation N2, and the approximate synchronization error S2 is the second deviation The difference between N2 and the time deviation N.

In a possible implementation manner, the above-mentioned time synchronization method further includes: the second communication device performs time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1; and the second communication device is in the second The first optical pulse signal with the second wavelength is received on the optical fiber for detection, and the second communication device sends the second optical pulse signal with the first wavelength on the second optical fiber for detection.

In a possible implementation manner, the above-mentioned time synchronization method further includes: the second communication device performs time synchronization with the first communication device on the second optical fiber according to the second deviation N2 and the approximate synchronization error S2; The optical fiber receives the third optical pulse signal with the first wavelength for detection, and the second communication device sends the fourth optical pulse signal with the second wavelength on the first optical fiber for detection.

In the second aspect, this application discloses a time synchronization method, including:

The first communication device sends a first optical signal with a first wavelength on the first optical fiber to the second communication device, the first optical signal carries a first time stamp, and the first time stamp instructs the first communication device to send the first optical signal Is the first time t1, and the second communication device receives the first optical signal at the second time t2; the first communication device receives the second communication device sent by the second communication device on the first optical fiber with a second wavelength of the second wavelength Optical signal, the second communication device sends the second optical signal at the third time t3; the first communication device sends a fourth time stamp on the first optical fiber to the second communication device, and the fourth time stamp indicates that the first communication device receives The time when the second optical signal is reached is the fourth time t4;

The first communication device sends a third optical signal with a second wavelength on the second optical fiber to the second communication device, the third optical signal carries a fifth time stamp, and the fifth time stamp instructs the first communication device to send the third optical signal The time at is the fifth time t5, and the time at which the second communication device receives the third optical signal is the sixth time t6; the first communication device receives the fourth optical signal sent by the second communication device on the second optical fiber, and the second communication device The time when the device sends the fourth optical signal is the seventh time t7;

The first communication device sends the eighth time stamp on the second optical fiber to the second communication device, so that the second communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, and the fifth time Time t5, sixth time t6, seventh time t7, and eighth time t8 are time synchronized with the first communication device, and the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8.

In a third aspect, this application discloses a time-synchronized communication device, including a processor and a channel medium conversion module, and the processor and the channel medium conversion module establish a communication connection;

The channel medium conversion module is configured to receive a first optical signal with a wavelength of the first wavelength sent by the first communication device on the first optical fiber, the first optical signal carries a first time stamp, and the first time stamp instructs the first communication device to send The time of the first optical signal is the first time t1, and the time when the channel medium conversion module receives the first optical signal is the second time t2;

The channel medium conversion module is further configured to send a second optical signal with a second wavelength on the first optical fiber to the first communication device, and the time when the channel medium conversion module sends the second optical signal is the third time t3;

The channel medium conversion module is further configured to receive a fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates that the time when the first communication device receives the second optical signal is the fourth time t4;

The channel medium conversion module is also used to receive a third optical signal with a second wavelength sent by the first communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp indicates the first communication device The time when the third optical signal is sent is the fifth time t5, and the time when the channel medium conversion module receives the third optical signal is the sixth time t6;

The channel medium conversion module is further configured to send the fourth optical signal with the first wavelength on the second optical fiber to the first communication device, and the time when the channel medium conversion module sends the fourth optical signal is the seventh time t7;

The channel medium conversion module is further configured to receive an eighth time stamp sent by the first communication device on the second optical fiber, where the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8;

The processor is configured to communicate with the first communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 Perform time synchronization.

In a possible implementation manner, the above-mentioned processor is based on the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time. Time synchronization between t8 and the first communication device includes: the processor determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4;

The processor determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8;

The processor determines the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation; the processor performs time synchronization with the first communication device according to the time deviation N.

In a possible implementation manner, the foregoing processor determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4, including: the first deviation N1 satisfies the calculation formula: N1=[ (t2-t1)-(t4-t3)]/2;

The foregoing processor determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8, including: the first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8 -t7)]/2;

The above-mentioned processor determines the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation, including: the time deviation N satisfies the calculation formula: N=(N1+N2)/2.

In a possible implementation manner, the above-mentioned processor is further configured to determine the approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, where the approximate synchronization error S1 is the first deviation N1 and the time deviation N The difference.

In a possible implementation manner, the foregoing processor is further configured to perform time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1;

In a possible implementation manner, the above-mentioned channel medium conversion module is further configured to receive the first optical pulse signal with the second wavelength on the second optical fiber for detection, and send the second optical pulse signal with the first wavelength on the second optical fiber. Light pulse signal for detection.

In a possible implementation manner, the second communication device further includes a stamping module. When the channel medium conversion module receives the first optical signal, the stamping module generates the first time stamp; when the channel medium conversion module sends the second optical signal, The stamping module generates a second time stamp; when the channel medium conversion module receives the third optical signal, the stamping module generates a fifth time stamp; when the channel medium conversion module sends the fourth optical signal, the stamping module generates an eighth time stamp.

In a possible implementation manner, the channel medium conversion module includes an optical transmitting and receiving module.

In a fourth aspect, this application also discloses a time-synchronized communication device, including a processor and a channel medium conversion module, and the processor and the channel medium conversion module establish a communication connection;

The channel medium conversion module is used to send the first optical signal with the first wavelength on the first optical fiber to the second communication device, the first optical signal carries a first time stamp, and the first time stamp instructs the channel medium conversion module to send the first optical signal. The time of an optical signal is the first time t1, and the time when the second communication device receives the first optical signal is the second time t2;

The channel medium conversion module is further configured to receive a second optical signal with a second wavelength sent by the second communication device on the first optical fiber, and the time when the second communication device sends the second optical signal is the third time t3;

The channel medium conversion module is further configured to send a fourth time stamp on the first optical fiber to the second communication device, where the fourth time stamp indicates that the time when the channel medium conversion module receives the second optical signal is the fourth time t4;

The channel medium conversion module is also used to send a third optical signal with a wavelength of the second wavelength to the second communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp instructs the channel medium conversion module to send The time of the third optical signal is the fifth time t5, and the time of the second communication device receiving the third optical signal is the sixth time t6;

The channel medium conversion module is further configured to receive the fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7;

The channel medium conversion module is also used to send an eighth time stamp on the second optical fiber to the second communication device, so that the second communication device can be based on the first time t1, the second time t2, the third time t3, and the fourth time Time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8 are time synchronized with the first communication device. The eighth time stamp indicates that the time when the channel medium conversion module receives the fourth optical signal is the eighth time. Time t8;

The processor is used to communicate with the channel medium conversion module.

In a fifth aspect, this application discloses a time-synchronized communication device, including a processing unit and a communication unit, and the processing unit and the communication unit establish a communication connection;

The communication unit is configured to receive a first optical signal with a wavelength of a first wavelength sent by the first communication device on the first optical fiber, the first optical signal carries a first time stamp, and the first time stamp instructs the first communication device to send the first The time of the optical signal is the first time t1, and the time when the channel medium conversion module receives the first optical signal is the second time t2;

The communication unit is further configured to send a second optical signal with a wavelength of the second wavelength to the first communication device on the first optical fiber, and the time when the channel medium conversion module sends the second optical signal is the third time t3;

The communication unit is further configured to receive a fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates that the time when the first communication device receives the second optical signal is the fourth time t4;

The communication unit is further configured to receive a third optical signal with a wavelength of the second wavelength sent by the first communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp instructs the first communication device to send the second wavelength The time of the three optical signals is the fifth time t5, and the time when the channel medium conversion module receives the third optical signal is the sixth time t6;

The communication unit is further configured to send a fourth optical signal with a wavelength of the first wavelength to the first communication device on the second optical fiber, and the time when the channel medium conversion module sends the fourth optical signal is the seventh time t7;

The communication unit is further configured to receive an eighth time stamp sent by the first communication device on the second optical fiber, where the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8;

The processing unit is configured to communicate with the first communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 Perform time synchronization.

In a sixth aspect, this application also discloses a time-synchronized communication device, including a processing unit and a communication unit, and the processing unit and the communication unit establish a communication connection;

The communication unit is configured to send a first optical signal with a wavelength of a first wavelength to the second communication device on the first optical fiber, the first optical signal carries a first time stamp, and the first time stamp instructs the channel medium conversion module to send the first light The time of the signal is the first time t1, and the time when the second communication device receives the first optical signal is the second time t2;

The communication unit is further configured to receive a second optical signal with a wavelength of the second wavelength sent by the second communication device on the first optical fiber, and the time when the second communication device sends the second optical signal is the third time t3;

The communication unit is further configured to send a fourth time stamp on the first optical fiber to the second communication device, where the fourth time stamp indicates that the time when the channel medium conversion module receives the second optical signal is the fourth time t4;

The communication unit is further configured to send a third optical signal with a wavelength of the second wavelength to the second communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp instructs the channel medium conversion module to send the third optical signal. The time of the optical signal is the fifth time t5, and the time of the second communication device receiving the third optical signal is the sixth time t6;

The communication unit is further configured to receive the fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7;

The communication unit is further configured to send an eighth time stamp on the second optical fiber to the second communication device, so that the second communication device can according to the first time t1, the second time t2, the third time t3, and the fourth time t4, The fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 are time synchronized with the first communication device, and the eighth time stamp indicates that the time when the channel medium conversion module receives the fourth optical signal is the eighth time t8 ；

The processing unit is used to communicate with the communication unit.

In a seventh aspect, the present application discloses a communication system. The communication system includes any communication device described in the third aspect and any communication device described in the fourth aspect, or the communication system includes Any communication device described in the above fifth aspect and any communication device described in the above sixth aspect.

In a possible implementation manner, the communication system may further include a first optical fiber and a second optical fiber.

The time synchronization method, communication equipment and system disclosed in the present application can realize a more accurate estimation of the clock time deviation value between communication equipment, improve the time synchronization accuracy in the communication network, without dispersion compensation, and support high-precision clock synchronization and OTDR technology is combined and applied.

Description of the drawings

In order to explain the embodiments of the present application or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings used when describing the background technology and the embodiments. Obviously, the following drawings describe only a part of the embodiments of the present application. For those of ordinary skill in the art, without creative work, other drawings or descriptions can be obtained based on these drawings and descriptions. Embodiments, and this application intends to cover all these derivative drawings or embodiments.

FIG. 1 is a schematic diagram of the principle of time synchronization performed by the 1588V2 protocol provided by an embodiment of the present application;

Figure 2a is a time synchronization system disclosed in an embodiment of the present application;

Figure 2b is a time synchronization method disclosed in an embodiment of the present application;

Figure 3a is another time synchronization system disclosed in an embodiment of the present application;

Figure 3b is another time synchronization method disclosed in an embodiment of the present application;

Fig. 4a is a schematic structural diagram of a second communication device disclosed in an embodiment of the present application;

4b is a schematic structural diagram of another second communication device disclosed in an embodiment of the present application;

Fig. 5a is a schematic structural diagram of a first communication device disclosed in an embodiment of the present application;

Fig. 5b is a schematic structural diagram of another first communication device disclosed in an embodiment of the present application.

Detailed ways

The embodiments of the present application provide a time synchronization method, communication equipment and system, which are used to improve the accuracy of time synchronization. Detailed descriptions are given below.

In the embodiments of the present application, "multiple" can be understood as "at least two"; "multiple" can be understood as "at least two"; "the difference between A and B" refers to AB, that is, A minus B , Or, refers to BA, that is, B minus A.

The technical solutions of the embodiments of this application can also be applied to various communication systems, such as: Global System of Mobile Communication (GSM) system, Code Division Multiple Access (CDMA) system, and broadband code division multiple Address (Wideband Code Division Multiple Access, WCDMA) system, communication system based on orthogonal frequency division multiplexing (OFDM) technology, General Packet Radio Service (GPRS), Long Term Evolution (Long Term) Evolution, LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD), Universal Mobile Telecommunication System (UMTS), Wireless Fidelity (Wireless) Fidelity (WiFi) system, Worldwide Interoperability for Microwave Access (WiMAX) communication system, Wireless Local Area Networks (WLAN) system, Public Land Mobile Network (PLMN) network, car To everything (Vehicle to everything, V2X) system, fifth generation (5th Generation, 5G) system, future sixth generation (6th Generation, 6G) system or New Radio (NR), optical transmission network, wavelength division Network, etc.

It should be understood that the communication method in the embodiments of the present application can be used in application scenarios that are sensitive to time synchronization or delay, such as automatic or assisted driving, augmented reality (AR), virtual reality (Virtual Reality, VR), and tactile Internet , Industrial control, smart grid (smart grid), real-time games, process automation (Process automation), industrial automation (Factory automation) and other scenarios, which are not limited in the embodiment of the present application.

For example, in an industrial control scenario, it is necessary to maintain time synchronization between the controller and the actuator. The controller sends control signaling to the actuator to instruct the actuator to execute the command at a certain time. If the actuator and the controller have different perceptions of time, that is, the time is not synchronized, the actuator will execute the command at the wrong time and cause the task execution to fail. For example, the controller tells the actuator (such as a mechanical arm) to start rotating to the left at a constant speed at 3 o'clock, the angular velocity is w, and the rotation time is t=5s. But in fact, because the time of the actuator and the controller are not synchronized, the 3 o'clock considered by the actuator is 3 o'clock and 1 second in the eyes of the controller. Therefore, the actuator starts to rotate at 3 o'clock and 1 s, and rotates for 5 s, and continues to 3 o'clock and 6 s. This lag of 1s may cause the actuator to conflict with other actuators and affect the smooth operation of industrial control. Therefore, time synchronization in industrial control is particularly important.

For example, in a smart grid, phase measurement modules (such as Data Terminal Unit (DTU)) need time synchronization. DTU is deployed in the ring network cabinet as a UE to sense voltage and current changes. The distribution network can use DTU to realize the differential protection of the distribution network. Adjacent DTUs learn their respective sampling values of currents through periodic interaction. The sampling time of each DTU to the current is fixed and the same (pre-configured). Each DTU compares the current values sampled by itself and its neighbor DTU at the same time. If the difference between the two exceeds a current threshold, it is considered that the circuit between the two is faulty, and each DTU will open the switch to perform current isolation protection. In this scenario, the time of adjacent DTUs must be synchronized in pairs. Otherwise, the asynchronous DTU will sample the current at different times, which will cause deviations in the current value normally sampled. The greater the time synchronization error, the greater the current deviation value may appear. Once the current threshold is exceeded, a false alarm will be generated. In user power consumption, false alarms will be reflected in the power failure of the entire community or area, resulting in poor user experience; in industrial power use, false alarms will be reflected in the power failure of the factory or workshop, causing unnecessary economic losses. Therefore, the importance of time synchronization in the smart grid is particularly prominent.

In order to better understand the embodiments of the present application, an application scenario used in the embodiments of the present application will be described below. In the communication network, the time synchronization of different base stations is required, and the time synchronization accuracy is within the required accuracy. The 1588V2 protocol is used to solve the time synchronization problem between the base stations. Please refer to FIG. 1, which is a schematic diagram of the principle of time synchronization performed by the 1588V2 protocol provided by an embodiment of the present application. As shown in Figure 1, the receiving end device and the sending end device interact through a message carrying a timestamp, and the receiving end device performs time synchronization with the sending end device according to the timestamp. Specifically, the sending end device sends a synchronization message at time t1, and carries the t1 timestamp indicating time t1 in the synchronization message; the receiving end device receives the synchronization message at time t2, and locally generates t2 indicating time t2 on the receiving end device. Timestamp, and extract the t1 timestamp from the synchronization message; the receiving device sends a delay request message at t3, and locally generates a t3 timestamp indicating t3 on the receiving device; the sending device receives the delay request message at t4 , And locally generate a t4 timestamp indicating t4 on the sending end device; the sending end device carries the t4 timestamp in the delayed response message and sends it to the receiving end device; the receiving end device extracts the t4 timestamp from the delayed response message; The receiving end device can calculate the time deviation between the receiving end device and the sending end device according to the obtained timestamps t1, t2, t3, and t4, and adjust the time of the receiving end device itself to achieve time synchronization with the sending end device.

Assuming that the path delay from the sender device to the receiver device is Delay1, the path delay from the receiver device to the sender device is Delay2, the time offset between the receiver device and the sender device is N, and the calculation of the time offset is specifically:

Then it can be obtained that the time deviation N=[(t2-t1)-(t4-t3)-(Delay1-Delay2)]/2.

When calculating the time deviation of the existing 1588V2 time synchronization, suppose Delay1=Delay2, the path delay from the sender device to the receiver device and the path delay from the receiver device to the sender device are equal, that is, the transceiver link delay is equal; then the time deviation calculation is The formula is further expressed as: N=[(t2-t1)-(t4-t3)]/2.

Since the physical link and wavelength of the time stamp transmission of the transceiver link are often different, it is difficult to achieve the same delay of the transceiver link Delay1=Delay2. If the path delay from the sender device to the receiver device and the path delay from the receiver device to the sender device are not equal, that is, the delay of the transceiver link is not equal, Delay1≠Delay2, will bring synchronization error to the size of the time deviation, synchronization error M =(Delay1-Delay2)/2. In order to achieve high-precision time synchronization, it is necessary to eliminate or reduce the error caused by the unequal delay of the transceiver link.

The above-mentioned time stamp is the information indicating the time at which its own clock is located when the sending end device or the receiving end device stamps. The time stamp is, for example, a character string or encoded information. The sending end device and the receiving end device may be ports, modules, network devices, etc. that need to be time synchronized. Synchronization messages, delayed request messages, and delayed response messages may be delivered in the form of messages.

1588V2 messages are divided into two categories: event messages (EVENT Message) and general messages (General Message). Event messages are time-concept messages and need to be stamped with accurate time stamps when entering and leaving the device port, while general messages are non-time concept messages, and no time stamp is generated when entering and leaving the device. Event messages include 4: Sync, Delay_Req, Pdelay_Req and Pdelay_Resp; general messages include 6: Announce, Follow_Up, Delay_Resp, Pdelay_Resp_Follow_Up, Management and Signalling.

Figures 2a and 2b show a time synchronization system and method disclosed in an embodiment of the present application. Optionally, the first communication device and the second communication device in the embodiment of the present application may be a wavelength division device in an optical network, an OTN device, or a node unit in another wavelength division network; the first communication device in the embodiment of the present application The communication device can also be a wireless access network device or node (such as a base station (Base Station, BS), a base station gNB in a 5G mobile communication system, an evolved base station eNodeB, a centralized unit (CU), and a distributed unit (Distributed Unit). Unit, DU)), the second communication device may also be a terminal device, user equipment (User Equipment, UE), D2D (Device to Device, D2D) equipment, BS, gNB, eNB, CU, DU; the first communication device may It is the above-mentioned sending-end device, and the second communication device may be the above-mentioned receiving-end device.

As shown in Figure 2a, a time synchronization system includes a first communication device 20 and a second communication device 21. The first communication device 20 and the second communication device 21 are connected by a single-fiber bidirectional optical fiber, and the second communication device 21 needs to adjust its own clock to achieve synchronization with the time of the first communication device 20. The signals sent by the first communication device 20 are all signals of the first wavelength, and the signals sent by the second communication device 21 are all signals of the second wavelength. For example, the first wavelength signal may be an optical signal with a wavelength of 1490 nm based on the 1588 protocol. The second wavelength signal may be an optical signal with a wavelength of 1510nm based on the 1588 protocol; or the first wavelength signal may also be an optical signal with a wavelength of 1506nm, and the second wavelength signal may also be an optical signal with a wavelength of 1514nm. This application lists The optical signal of is a commonly used optical signal, but it is not limited to this.

As shown in Figure 2b, a time synchronization method includes:

Step S201: The first communication device sends a first optical signal to the second communication device, and at the same time, when the first communication device sends the first optical signal, it places a first time stamp locally on the first communication device, and the first optical signal carries the first optical signal. A first time stamp, where the first time stamp indicates that the time when the first communication device sends the first optical signal is the first time t1, and the second communication device extracts the first time t1 from the first time stamp;

Step S202: When the second communication device receives the first optical signal, it puts a second time stamp locally on the second communication device, and the second time stamp indicates that the time when the second communication device receives the first optical signal is The second moment t2;

Step S203: The second communication device sends a second optical signal to the first communication device, and at the same time, when the second communication device sends the second optical signal, a third time stamp is printed locally on the second communication device, and the third time stamp indicates The time when the second communication device sends the second optical signal is the third time t3;

Step S204: When the first communication device receives the second optical signal, it places a fourth time stamp locally on the first communication device, and the fourth time stamp indicates that the time when the first communication device receives the second optical signal is the fourth time. Time t4;

Step S205: The first communication device sends the fourth time stamp to the second communication device, and the second communication device extracts the fourth time t4 from the fourth time stamp.

In the 1588V2 synchronization protocol, the delayed response message is the Delay_Resp message. Each Delay_Resp message generated is used to carry the fourth timestamp generated this time, and the originTimestamp field of the Delay_Resp message can be used to carry the fourth timestamp. .

Step S206: The second communication device performs time synchronization with the first communication device according to the aforementioned first time t1, second time t2, third time t3, and fourth time t4. Specifically, the second communication device determines the time deviation N according to the following calculation formula:

N=[(t2-t1)-(t4-t3)]/2

The second communication device performs time synchronization with the first communication device according to the calculated time deviation.

The message transmission of the time synchronization method and system provided in this embodiment adopts a single-fiber bidirectional transmission configuration. Since the message transmission is carried out on the same optical fiber, the time synchronization method or system eliminates or avoids the transmission and reception link optical fiber The difference in the length of the transceiver link causes the error of the delay of the transceiver link. The difference in the fiber length of the transceiver link refers to the length of the fiber where the link sent by the first communication device to the second communication device is and the length of the fiber sent by the second communication device to the first communication device The fiber length of the link is different.

However, because the wavelengths of the messages sent by the first communication device to the second communication device and the messages sent by the second communication device to the first communication device are generally different, the difference in fiber dispersion results in different wavelengths of the same fiber. The transmission delay is different, so it will still bring synchronization error to the two-way delay of the transceiver link. The transceiver link mentioned in the embodiment of the present application refers to the link from the first communication device to the second communication device and the link from the second communication device to the first communication device.

Theoretically, under the condition that the actual length of the fiber, the fiber dispersion curve, and the wavelength of the message transmission in the two directions on the transceiver link are known, the calculation method of the dispersion delay can be used to calculate the two-way delay caused by the fiber dispersion. Asymmetry is compensated, but at the same time, the actual length of the fiber, the fiber dispersion curve, and the wavelength of the message transmission in the two directions on the transceiver link need to be input. The deployment complexity is greatly increased, and there is a risk of error. Even for the same fiber type, the fiber dispersion curve still has a certain difference, and the actual dispersion curve of the fiber has no better measurement method. If the standard dispersion curve of the corresponding fiber type is substituted for compensation, the dispersion delay difference still cannot be eliminated. The error caused by the two-way delay of the transceiver link.

Assuming that the path delay from the first communication device to the second communication device is Delay1, and the path delay from the second communication device to the first communication device is Delay2, according to the above embodiment, it can be known that the synchronization error M=(Delay1-Delay2)/2.

Assuming that the first wavelength of the message transfer from the first communication device to the second communication device is wavelength λ1, the second wavelength of the message transfer from the second communication device to the first communication device is wavelength λ2, and the refractive indices corresponding to the wavelengths are n1, respectively n2, the length of the optical fiber is L, and the speed of light is c, the synchronization error M0 of the two-way delay of the transceiver link is:

M0=(Delay1-Delay2)/2=L*(n1-n2)/2c

It can be seen that the synchronization error of the two-way delay of the transceiver link is positively correlated with the length of the optical fiber link. The longer the optical link length, the greater the synchronization error of the two-way delay of the transceiver link.

The terms "first" and "second" in this application are used to distinguish similar objects, but not necessarily used to describe a specific sequence or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that The described embodiments can be implemented in a sequence not described in this application. "And/or" is used to describe the association relationship of associated objects, indicating that there can be three types of relationships. For example, A and/or B can mean that: A alone exists, A and B exist at the same time, and B exists alone. The specific operation method in the method embodiment can also be applied to the device embodiment. In addition, in order to more clearly reflect the relationship between the components in the different embodiments, the present application uses the same drawing numbers to represent components with the same or similar functions in the different embodiments.

It should also be noted that, unless otherwise specified, the specific description of some technical features in one embodiment can also be used to explain the corresponding technical features in other embodiments.

Figures 3a and 3b show yet another time synchronization system and method disclosed in an embodiment of the present application. A time synchronization system, as shown in Figure 3a, includes a first communication device 20 and a second communication device 21. The first communication device 20 and the second communication device 21 are connected by a first optical fiber 22 and a second optical fiber 23 Wherein, the fiber lengths of the first optical fiber 22 and the second optical fiber 23 are kept the same as far as possible, and a certain error may be allowed in practice. The second communication device 21 needs to adjust its own clock to achieve time synchronization with the first communication device 20.

The signals sent by the first communication device 20 on the first optical fiber 22 are all signals of the first wavelength, and the signals sent by the second communication device 21 on the first optical fiber 22 are all signals of the second wavelength, for example, signals of the first wavelength. It may be an optical signal with a wavelength of 1490nm based on the 1588 protocol, and the second wavelength signal may be an optical signal with a wavelength of 1510nm based on the 1588 protocol; or the first wavelength signal may also be an optical signal with a wavelength of 1506nm, and the second wavelength signal may also It can be an optical signal with a wavelength of 1514 nm. The signals sent by the first communication device 20 on the second optical fiber 23 are all signals of the second wavelength, and the signals sent by the second communication device 21 on the second optical fiber 23 are all signals of the first wavelength.

A method of time synchronization, as shown in Figure 3b, includes:

Step S301: the first communication device 20 and the second communication device 21 perform message transfer on the first optical fiber 22 and the second optical fiber 23;

Wherein, on the first optical fiber 22, the message transfer process between the first communication device 20 and the second communication device 21 is as follows:

The first communication device 20 sends a first optical signal with a wavelength of the first wavelength to the second communication device 21 on the first optical fiber 22, and the first communication device 20 sends the first optical signal while marking the first time stamp. An optical signal carries a first time stamp, and the first time stamp indicates that the time at which the first communication device 20 sends the first optical signal is the first time t1;

When the second communication device 21 receives the first optical signal, a second time stamp is printed, and the second time stamp indicates that the time when the second communication device 21 receives the first optical signal is the second time t2;

The second communication device 21 sends a second optical signal with a second wavelength on the first optical fiber 22 to the first communication device 20, and the second communication device 21 stamps a third time stamp, which indicates the second communication device 21 The time when the above-mentioned second optical signal is sent is the third time t3;

The second communication device 21 receives the fourth time stamp sent by the first communication device 20 on the first optical fiber 22, and the fourth time stamp indicates that the time when the first communication device 20 receives the second optical signal is the fourth time t4.

On the second optical fiber 23, the message transfer process between the first communication device 20 and the second communication device 21 is as follows:

The second communication device 21 receives a third optical signal with a wavelength of the above-mentioned second wavelength sent by the first communication device 20 on the second optical fiber 23, and the third optical signal carries a fifth time stamp, and the fifth time stamp indicates the first The time when the communication device 20 sends the third optical signal is the fifth time t5, and the time when the second communication device 21 receives the third optical signal is the sixth time t6;

The second communication device 21 sends the fourth optical signal with the wavelength of the first wavelength to the first communication device 20 on the second optical fiber 23, and the time when the second communication device 21 sends the fourth optical signal is the seventh time t7;

The first communication device 20 sends an eighth time stamp on the second optical fiber 23 to the second communication device 21, and the eighth time stamp indicates that the time when the first communication device 20 receives the fourth optical signal is the eighth time t8.

For the message transfer process performed by the first communication device 20 and the second communication device 21 on the first optical fiber 22 and the second optical fiber 23, refer to FIG. 2b and related descriptions for details. For the sake of brevity, the details are not repeated here.

Preferably, the first communication device 20 and the second communication device 21 perform message transmission on the first optical fiber 22 and the second optical fiber 23 at the same time. For example, the first communication device 20 transmits the first optical signal on the first optical fiber 22 at the same time. The third optical signal is sent on the second optical fiber 23, and an error within a certain range is allowed in practice.

Step S302: the second communication device 21 performs time synchronization with the first communication device 20, and the second communication device 21 adjusts its own time to be synchronized with the first communication device 20;

Specifically, the second communication device 21 is based on the first time t1, the second time t2, the third time t3, and the fourth time generated during the message transmission between the first communication device 20 and the second communication device 21 on the first optical fiber 22. t4 determines the first deviation N1, where the calculation formula of N1 is: N1=[(t2-t1)-(t4-t3)]/2;

The second communication device 21 determines the first communication device 20 and the second communication device 21 at the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 during the message transmission on the second optical fiber 23 described above. Two deviations N2, where the calculation formula of N2 is: N2=[(t6-t5)-(t8-t7)]/2;

The second communication device 21 determines the time deviation N of the second communication device 21 relative to the first communication device 20 according to the first deviation N1 and the second deviation N2, where the calculation formula of N is: N=(N1+N2 )/2;

The second communication device 21 performs time synchronization with the first communication device 20 according to the calculated time deviation N.

The following describes the accuracy of the time deviation N obtained above:

Assuming that the first wavelength is wavelength λ1 and the second wavelength is wavelength λ2, the refractive indices corresponding to the wavelengths are n1 and n2, respectively, the length of the first optical fiber 22 is L1, the length of the second optical fiber 23 is L2, and the speed of light is c, According to the above embodiment, it can be seen that:

The synchronization error of the two-way delay of the transceiver link between the second communication device 21 and the first communication device 20 on the first optical fiber 22 is M1=L1*(n1-n2)/2c;

The synchronization error of the two-way delay of the transceiver link between the second communication device 21 and the second communication device 21 and the first communication device 20 on the second optical fiber 23 is M2=L2*(n2-n1)/2c

Assuming that the real time deviation between the second communication device 21 and the first communication device 20 is N0, then

N1=N0-M1, N2=N0-M2, then N=(N1+N2)/2=N0-(M1+M2)/2;

At this time, the synchronization error M relative to the real time deviation N0 under the above-mentioned N=(N1+N2)/2 calculation method is:

M=(M1+M2)/2=(L1-L2)*(n1-n2)/4c

According to the related description of Fig. 2b, the synchronization error of the time synchronization system shown in Fig. 2a is M0=(Delay1-Delay2)/2=L*(n1-n2)/2c;

Then the ratio of M to M0: M/M0=(L1-L2)/2L;

It can be seen that when (L1-L2) is much smaller than 2*L, that is, when the length difference between fiber 1 and fiber 2 is much less than twice the length of a single fiber, M/M0 approaches 0; The fiber lengths of the optical fiber 22 and the second optical fiber 23 should be kept the same as far as possible. In practice, a certain error is allowed, that is, (L1-L2) is much smaller than 2*L, that is to say, the first calculated based on the embodiment of Figure 3a and Figure 3b The synchronization error corresponding to the time deviation value between the second communication device and the first communication device is much smaller than the synchronization error of the time synchronization system in FIGS. 2a and 2b, so the time deviation N is infinitely close to the real time deviation N0. Therefore, the time synchronization method and system provided in this embodiment can achieve high-precision time synchronization without the need to perform fiber dispersion delay difference compensation, and without additional input of fiber length and fiber dispersion curve.

Step S303-Step 306 are optional steps, which are possible extended implementations of the above solution.

Step S303: The second communication device 21 determines the approximate synchronization error of the two-way time delay between the first communication device 20 and the second communication device 21 on the first optical fiber 22;

The second communication device 21 determines the approximate synchronization error S1 of the two-way time delay between the first communication device 20 and the second communication device 21 on the first optical fiber 22 according to the above-mentioned time deviation N and the above-mentioned first deviation N1, the approximate synchronization error S1 is the difference between the first deviation N1 and the time deviation N, that is, S1=N1-N.

According to the above steps, the time deviation N is infinitely close to the real time deviation N0, so here, the value of (N1-N) is taken as the approximate synchronization error S1, and the approximate synchronization error S1 is used for clock compensation. The following is the approximate synchronization error S2 similar.

Step S304: the second communication device 21 performs time synchronization on the first optical fiber 22, and performs a pulse test on the second optical fiber 23;

The second communication device 21 performs time synchronization with the first communication device 20 on the first optical fiber 22 according to the first deviation N1 and the approximate synchronization error S1, and the second communication device further compensates the approximate synchronization error S1 calculated above to the first optical fiber. The time of the second communication device 21 on 22 is synchronized with the time of the first communication device 20. At this time, time synchronization can be achieved only through message transmission on the first optical fiber 22;

The first communication device 20 sends the first optical pulse signal with the above-mentioned second wavelength on the second optical fiber 23 to the second communication device 21 for detection, and the second communication device 21 sends the wavelength to the first communication device 20 on the second optical fiber. Detect the second optical pulse signal of the first wavelength mentioned above.

Step S305: The second communication device 21 determines the synchronization error of the two-way time delay between the first communication device 20 and the second communication device 21 on the second optical fiber 23;

The second communication device 21 determines the approximate synchronization error S2 of the two-way time delay between the first communication device 20 and the second communication device 21 on the second optical fiber 23 according to the above-mentioned time deviation N and the second deviation N2, and the approximate synchronization error S2 is The difference between the second deviation N2 and the time deviation N is S2=N2-N.

Step S306: the second communication device performs time synchronization on the second optical fiber, and performs a pulse test on the first optical fiber;

The second communication device 21 performs time synchronization with the first communication device 20 on the second optical fiber 23 according to the second deviation N2 and the approximate synchronization error S2. The second communication device further compensates the approximate synchronization error S2 obtained by the calculation to the first communication device 20. The time of the second communication device 21 and the first communication device 20 on the second optical fiber 23 is synchronized. At this time, time synchronization can be realized only through message transmission on the second optical fiber 23;

The first communication device 20 sends a third optical pulse signal with a wavelength of the above-mentioned first wavelength to the second communication device 21 on the first optical fiber 22 for detection, and the second communication device 21 sends to the first communication device 20 on the first optical fiber 22 The fourth optical pulse signal whose wavelength is the above-mentioned second wavelength is detected.

The foregoing optical pulse signal may be an OTDR (Optical Time Domain Reflectometer, Optical Time Domain Reflectometer) pulse signal or an OFDR (Optical Frequency Domain Reflectometer, Optical Frequency Domain Reflectometer) pulse signal.

In this embodiment, step 303-step 306 is to first perform a pulse test on the second optical fiber 23, and then perform a pulse test on the first optical fiber 22, or perform a pulse test on the first optical fiber 22 first, and then perform a pulse test on the first optical fiber 22. The pulse test is performed on the second optical fiber 23, that is, step 305 to step 306 are performed first, and then step 303 to step 304 are performed.

The time synchronization method and system disclosed in this embodiment implements accurate estimation of clock time deviation values between communication devices, improves time synchronization accuracy in communication networks, does not require dispersion compensation, and supports the combined application of high-precision clock synchronization and OTDR technology.

For the method based on the foregoing embodiment, please refer to FIG. 4a. FIG. 4a is a schematic structural diagram of a second communication device 21 disclosed in an embodiment of the present application. As shown in Fig. 4a, the second communication device 21 includes a communication unit 401 and a processing unit 402, wherein:

The communication unit 401 is configured to receive a first optical signal with a wavelength of a first wavelength sent by the first communication device 20 on a first optical fiber, the first optical signal carries a first time stamp, and the first time stamp indicates the first The time when the communication device sends the first optical signal is the first time t1, and the time when the communication unit 401 receives the first optical signal is the second time t2;

The communication unit 401 is further configured to send a second optical signal with a second wavelength on the first optical fiber to the first communication device, and the time when the communication unit 401 sends the second optical signal is the third time t3;

The communication unit 401 is further configured to receive a fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates that the time when the first communication device receives the second optical signal is the fourth time t4;

The communication unit 401 is further configured to receive a third optical signal with a wavelength of the second wavelength sent by the first communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp indicates the first optical signal. The time when a communication device sends the third optical signal is the fifth time t5, and the time when the communication unit 401 receives the third optical signal is the sixth time t6;

The communication unit 401 is further configured to send a fourth optical signal with a wavelength of the first wavelength to the first communication device on the second optical fiber, and the time when the communication unit 401 sends the fourth optical signal is the seventh time t7;

The communication unit 401 is further configured to receive an eighth time stamp sent by the first communication device on the second optical fiber, where the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8;

The processing unit 402 is configured to compare the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8 with the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8. A communication device performs time synchronization.

Specifically, the processing unit 402 compares the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8 with the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8. A communication device performs time synchronization, including:

The processing unit 402 determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4. The first deviation N1 satisfies the calculation formula: N1=[(t2-t1)-(t4-t3 )]/2;

The processing unit 402 determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8. The first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8-t7 )]/2;

The processing unit 402 determines the time deviation N of the second communication device 21 relative to the first communication device 20 according to the first deviation and the second deviation, and the time deviation N satisfies the calculation formula: N=(N1+N2)/2;

The processing unit 402 performs time synchronization with the first communication device 20 according to the time deviation N.

Optionally, the processing unit 402 is further configured to determine the approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, where the approximate synchronization error S1 is the difference between the first deviation N1 and the time deviation N .

Further, the processing unit 402 is also configured to perform time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1; the communication unit 401 is also configured to receive the second optical fiber with a wavelength of the above-mentioned second optical fiber. The first optical pulse signal with the wavelength is detected, and the second optical pulse signal with the wavelength of the first wavelength is sent on the second optical fiber for detection.

Optionally, the processing unit 402 is further configured to determine the approximate synchronization error S2 of the two-way delay on the second optical fiber according to the time deviation N and the second deviation N2, where the approximate synchronization error S2 is the difference between the first deviation N2 and the time deviation N .

Further, the processing unit 402 is further configured to perform time synchronization with the first communication device on the second optical fiber according to the second deviation N2 and the approximate synchronization error S2; the communication unit 401 is also configured to receive the first optical fiber with a wavelength of the above-mentioned first optical fiber. The third optical pulse signal with the wavelength is detected, and the fourth optical pulse signal with the wavelength of the second wavelength is sent on the first optical fiber for detection.

As a possible implementation, when the communication unit 401 receives the above-mentioned first optical signal, the stamping module in the second communication device 21 generates the first time stamp; when the communication unit 401 sends the above-mentioned second optical signal, the second communication The stamping module in the device 21 generates the second time stamp; in the same way, the sixth time stamp and the seventh time stamp are also generated by the above stamping module.

As a possible implementation manner, after the stamping module in the second communication device 21 generates the second, third, sixth, sixth, or seventh time stamps, the second time stamp is , The third time stamp, the sixth time stamp, the sixth time stamp, or the seventh time stamp are sent to the processor in the second communication device 21, and a certain time stamp indicates the time corresponding to the time stamp, for example, the first time stamp indicates At the aforementioned first time, the processor may store the second time stamp, the third time stamp, the sixth time stamp, or the seventh time stamp in the memory of the second communication device 21.

The processing unit 402 may be used to implement the functions of the processor and the stamping module in the second communication device 21 described above.

In particular, the communication unit 401 may include at least two sub-units, for example, a first communication unit and a second communication unit. The first communication unit is used to process communications on the first optical fiber, and the second communication unit is used for the second communication. Communication on optical fiber.

It should be noted that the implementation of each unit may also correspond to the corresponding description of the time synchronization method embodiment shown in FIG. 3b.

For the method based on the foregoing embodiment, please refer to FIG. 4b. FIG. 4b is a schematic structural diagram of another second communication device 21 disclosed in an embodiment of the present application. As shown in FIG. 4b, the second communication device 21 may include a processor 411 and a channel medium conversion module 413, where the processor 411 and the channel medium conversion module 413 establish a communication connection, where:

The channel medium conversion module 413 is configured to receive a first optical signal with a wavelength of a first wavelength sent by the first communication device 20 on the first optical fiber, the first optical signal carries a first time stamp, and the first time stamp indicates the foregoing The time when the first communication device 20 sends the first optical signal is the first time t1, and the time when the channel medium conversion module 413 receives the first optical signal is the second time t2;

The channel medium conversion module 413 is further configured to send a second optical signal with a second wavelength on the first optical fiber to the first communication device 20, and the time when the channel medium conversion module 413 sends the second optical signal is the third time t3 ；

The channel medium conversion module 413 is further configured to receive a fourth time stamp sent by the first communication device 20 on the first optical fiber, and the fourth time stamp indicates that the time when the first communication device 20 receives the second optical signal is the fourth Time t4;

The channel medium conversion module 413 is configured to receive a third optical signal with a wavelength of the second wavelength sent by the first communication device 20 on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp indicates The time when the first communication device sends the third optical signal is the fifth time t5, and the time when the channel medium conversion module 413 receives the third optical signal is the sixth time t6;

The channel medium conversion module 413 is further configured to send the fourth optical signal with the wavelength of the first wavelength to the first communication device on the second optical fiber, and the time when the channel medium conversion module 413 sends the fourth optical signal is the seventh Time t7;

The channel medium conversion module 413 is further configured to receive the eighth time stamp sent by the first communication device 20 on the second optical fiber, and the eighth time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time. Time t8;

The processor 411 is configured to compare the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 with the aforementioned first time t1, second time t2, third time t3, fourth time t4, A communication device 20 performs time synchronization.

Specifically, the processor 411 compares the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8 with the aforementioned first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, seventh time t7, and eighth time t8. A communication device performs time synchronization, including:

The processor 411 determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8. The first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8-t7 )]/2;

The processor 411 determines the time deviation N of the second communication device 21 relative to the first communication device 20 according to the first deviation and the second deviation, and the time deviation N satisfies the calculation formula: N=(N1+N2)/2;

The processor 411 performs time synchronization with the first communication device 20 according to the time deviation N.

Optionally, the processor 411 is further configured to determine an approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, where the approximate synchronization error S1 is the difference between the first deviation N1 and the time deviation N .

Further, the processor 411 is further configured to perform time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1; the channel medium conversion module 413 is also configured to receive the wavelength on the second optical fiber as described above The first optical pulse signal with the second wavelength is detected, and the second optical pulse signal with the wavelength of the first wavelength is sent on the second optical fiber for detection.

As a possible implementation, the second communication device 21 further includes a stamping module 412. When the channel medium conversion module 413 receives the first optical signal, the stamping module 412 generates a first time stamp; the channel medium conversion module 413 sends When the second optical signal is used, the stamping module 412 generates a second time stamp; when the channel medium conversion module 413 receives the third optical signal, the stamping module 412 generates a fifth time stamp; the channel medium conversion module 413 sends the first In the case of four optical signals, the stamping module 412 generates an eighth time stamp. The stamping module 412 sends the second, third, sixth, and seventh timestamps to the processor 411, and the processor 411 may send the second, third, sixth, or The seventh time stamp is stored in the memory of the second communication device 21.

Optionally, the channel media conversion module 413 includes a fiber optic transceiver or an optical module; the channel media conversion module 413 may include two fiber optic transceivers, or two optical modules, or one fiber transceiver and one optical module, one of which is a fiber transceiver. The optical transceiver or optical module is used to process the communication on the above-mentioned first optical fiber, and the other optical transceiver or optical module is used to process the communication on the above-mentioned second optical fiber.

Optionally, the channel medium conversion module 413 may be an optical transmitting and receiving module for sending or receiving optical signals or optical pulse signals. The channel medium conversion module 413 may also include a receiver and a transmitter, and the receiver and the transmitter may be integrated on a chip.

Optionally, the stamping module 412 may also include two sub-modules. One of the stamping sub-modules is used to process the communication on the above-mentioned first optical fiber, and the other stamping sub-module is used to process the communication on the above-mentioned second optical fiber.

The stamping module 412 may be implemented by a field programmable gate array, for example.

Among them, the implementation of each module may correspond to the corresponding description of the time synchronization method embodiment shown in FIG. 3b.

The processor involved in the embodiment of the present application may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP. The processor may also be a hardware chip, which may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The above-mentioned PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL) or any combination thereof.

For the method based on the foregoing embodiment, please refer to FIG. 5a. FIG. 5a is a schematic structural diagram of a first communication device 20 disclosed in an embodiment of the present application. As shown in Fig. 5a, the first communication device 20 includes a communication unit 501 and a processing unit 502, wherein:

The communication unit 501 is configured to send a first optical signal with a first wavelength on the first optical fiber to the second communication device 21, the first optical signal carries a first time stamp, and the first time stamp instructs the communication unit 501 to send the first optical signal The time of an optical signal is the first time t1, and the time when the second communication device 21 receives the first optical signal is the second time t2;

The communication unit 501 is further configured to receive a second optical signal with a second wavelength sent by the second communication device 21 on the above-mentioned first optical fiber, and the time when the second communication device 21 sends the second optical signal is the third time t3;

The communication unit 501 is further configured to send a fourth time stamp on the first optical fiber to the second communication device 21, where the fourth time stamp indicates that the time when the communication unit 501 receives the second optical signal is the fourth time t4;

The communication unit 501 is further configured to send a third optical signal with a wavelength of the second wavelength on the second optical fiber to the second communication device 21, the third optical signal carries a fifth time stamp, and the fifth time stamp indicates the communication unit 501 The time when the third optical signal is sent is the fifth time t5, and the time when the second communication device receives the third optical signal is the sixth time t6;

The communication unit 501 is further configured to receive the fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7;

The communication unit 501 is further configured to send an eighth time stamp on the second optical fiber to the second communication device 21, so that the second communication device 21 can be based on the first time t1, the second time t2, and the third time t3. , The fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 are time synchronized with the first communication device 20, and the eighth time stamp indicates that the first communication device 20 receives the fourth The time of the optical signal is the eighth time t8;

The processing unit 502 is configured to communicate with the communication unit 501.

Specifically, the second communication device 21 compares the relationship between the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 according to the foregoing first time t1, second time t2, third time t3, fourth time t4, fifth time t5, sixth time t6, and The above-mentioned first communication device performing time synchronization includes:

The second communication device 21 determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4. The first deviation N1 satisfies the calculation formula: N1=[(t2-t1)-(t4 -t3)]/2;

The second communication device 21 determines the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8. The first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8 -t7)]/2;

The second communication device 21 determines the time deviation N of the second communication device 21 relative to the first communication device 20 according to the first deviation N1 and the second deviation N2, and the time deviation N satisfies the calculation formula: N=(N1+N2)/2 ；

The second communication device 21 performs time synchronization with the first communication device 20 according to the time deviation N.

Optionally, the second communication device 21 is further configured to determine the approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, and the approximate synchronization error S1 is the difference between the first deviation N1 and the time deviation N Difference.

Further, the second communication device 21 is also used to perform time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1; the communication unit 501 is also used to transmit on the second optical fiber with a wavelength of the above The first optical pulse signal with the second wavelength is detected and the second optical pulse signal with the wavelength of the first wavelength is received on the second optical fiber for detection.

As a possible implementation, when the communication unit 501 sends the above-mentioned first optical signal, the stamping module in the first communication device 20 generates a first time stamp, and when the communication unit 501 receives the above-mentioned second optical signal, the first communication The stamping module in the device 20 generates the fourth time stamp; in the same way, the fifth and eighth time stamps are also generated by the stamping module in the first communication device 20. The above-mentioned stamping module sends the first time stamp, the fourth time stamp, the fifth time stamp or the eighth time stamp to the processor in the first communication device 20, and the processor can send the first time stamp, the fourth time stamp, the The fifth time stamp or the eighth time stamp is stored in the memory of the first communication device 20.

As a possible implementation manner, the communication unit 501 sends the first time stamp to the second communication device 21, including:

After receiving the first time stamp sent by the stamping module, the processing unit 502 sends a synchronization message to the second communication device 21 via the channel medium conversion module in the first communication device 20. The synchronization message carries the first time stamp. It may be the above-mentioned first optical signal.

As a possible implementation manner, the first communication device 20 sending the fourth time stamp to the second communication device 21 includes: after the processor in the first communication device 20 receives the fourth time stamp sent by the stamping module, The delay response message is sent to the second communication device 21 via the channel medium conversion module in the first communication device 20, and the delay response message carries the fourth time stamp.

The communication unit 501 may be used to implement the function of the channel media conversion module in the first communication device 20, and the processing unit 502 may be used to implement the functions of the processor and the stamping module in the first communication device 20.

Based on the foregoing method and system embodiments, please refer to FIG. 5b. FIG. 5b is a schematic structural diagram of another first communication device 20 disclosed in an embodiment of the present application. As shown in FIG. 5b, the first communication device 20 may include a processor 511 and the channel media conversion module 513, wherein: the processor 511 and the channel media conversion module 513 establish a communication connection, wherein:

The channel medium conversion module 513 is configured to send a first optical signal with a first wavelength on the first optical fiber to the second communication device 21, the first optical signal carries a first time stamp, and the first time stamp indicates the communication unit 501 The time when the first optical signal is sent is the first time t1, and the time when the second communication device 21 receives the first optical signal is the second time t2;

The channel medium conversion module 513 is also used to receive the second optical signal with the second wavelength sent by the second communication device 21 on the first optical fiber, and the time when the second communication device 21 sends the second optical signal is the third time t3;

The channel medium conversion module 513 is further configured to send a fourth time stamp on the first optical fiber to the second communication device 21, where the fourth time stamp indicates that the time when the communication unit 501 receives the second optical signal is the fourth time t4;

The channel medium conversion module 513 is further configured to send a third optical signal with a wavelength of the second wavelength to the second communication device 21 on the second optical fiber. The third optical signal carries a fifth time stamp, and the fifth time stamp indicates The time when the communication unit 501 sends the third optical signal is the fifth time t5, and the time when the second communication device receives the third optical signal is the sixth time t6;

The channel medium conversion module 513 is further configured to receive the fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7;

The channel media conversion module 513 is further configured to send an eighth time stamp on the second optical fiber to the second communication device 21, so that the second communication device can perform according to the first time t1, the second time t2, and the third time. t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 are time synchronized with the first communication device 20. The eighth time stamp indicates that the first communication device 20 receives the first communication device 20. The time of the four-light signal is the eighth time t8;

The processor 511 is configured to communicate with the channel medium conversion module 513.

As a possible implementation, the first communication device 20 further includes a stamping module 512. When the channel medium conversion module 513 sends the above-mentioned first optical signal, the stamping module 512 generates the first time stamp, and the channel medium conversion module 513 receives For the above-mentioned second optical signal, the stamping module 512 generates a fourth time stamp; similarly, the fifth time stamp and the eighth time stamp are also generated by the stamping module 512. The stamping module 512 sends the first, fourth, fifth, or eighth timestamp to the processor 511, and the processor 511 may send the first, fourth, fifth, or The eighth time stamp is stored in the memory of the first communication device 20.

Optionally, the channel media conversion module 513 includes a fiber optic transceiver or an optical module; the channel media conversion module 513 may include two fiber optic transceivers, or two optical modules, or one fiber transceiver and one optical module, one of which is a fiber transceiver. The optical transceiver or optical module is used to process the communication on the above-mentioned first optical fiber, and the other optical transceiver or optical module is used to process the communication on the above-mentioned second optical fiber.

Optionally, the channel medium conversion module 513 may be an optical transmitting and receiving module for sending or receiving optical signals or optical pulse signals. The channel medium conversion module 413 may also include a receiver and a transmitter, and the receiver and the transmitter may be integrated on a chip.

Optionally, the stamping module 512 may also include two sub-modules. One of the stamping sub-modules is used to process the communication on the above-mentioned first optical fiber, and the other stamping sub-module is used to process the communication on the above-mentioned second optical fiber.

The stamping module 512 may be implemented by a field programmable gate array, for example.

Based on the above-mentioned embodiment, the embodiment of the present application further discloses a communication system. As shown in FIG. 3a, the communication system includes a first communication device 20 and a second communication device 21. The first communication device 20 is shown in FIG. 5a or FIG. 5b. The first communication device 20 disclosed in the described embodiment, and the second communication device 21 is the second communication device 21 disclosed in the embodiment described in FIG. 4a or FIG. 4b. The communication system may also include a first optical fiber and a second optical fiber. optical fiber.

The same and similar parts in the various embodiments of the present application can be referred to each other. In particular, for the embodiment of FIG. 4a-FIG. 5b, since it is based on the embodiment corresponding to FIG. 1 to FIG. 3b, the description is relatively simple and relevant. For details, please refer to the part of the description of the corresponding embodiment in Figs.

The embodiment of the present application provides a computer-readable storage medium, including computer-readable instructions. When the computer reads and executes the computer-readable instructions, the computer executes the method executed by the above-mentioned processor.

The embodiment of the present application also provides a computer program product containing instructions, which when the computer program product runs on a computer, causes the computer to execute the method executed by the above-mentioned processor.

Obviously, those skilled in the art should understand that the above-mentioned modules or steps of this application can be implemented by a general computing device, and they can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. Optionally, they can be implemented with program codes executable by the computing device, so that they can be stored in a storage medium (ROM/RAM, magnetic disk, optical disk) and executed by the computing device, and in some cases The steps shown or described can be executed in a different order from here, or they can be made into individual integrated circuit modules, or multiple modules or steps of them can be made into a single integrated circuit module to achieve. Therefore, this application is not limited to any specific combination of hardware and software.

Finally, it should be noted that the above are only specific implementations of this application, and the scope of protection of this application is not limited to this. Any person skilled in the art can easily think of changes within the technical scope disclosed in this application. Or replacement should be covered within the scope of protection of this application.

Claims

A method for time synchronization, characterized in that the method includes:

The second communication device receives the first optical signal with the first wavelength sent by the first communication device on the first optical fiber, where the first optical signal carries a first time stamp, and the first time stamp indicates the first optical signal. The time when the communication device sends the first optical signal is the first time t1;

Generating a second time stamp by the second communication device, where the second time stamp indicates that the time when the second communication device receives the first optical signal is a second time t2;

The second communication device sends a second optical signal with a second wavelength on the first optical fiber to the first communication device, the second communication device generates a third time stamp, and the third time stamp Instruct the second communication device to send the second optical signal at the third time t3;

The second communication device receives a fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates the moment when the first communication device receives the second optical signal Is the fourth time t4;

The second communication device receives a third optical signal with a wavelength of the second wavelength sent by the first communication device on the second optical fiber, the third optical signal carries a fifth time stamp, and the fifth time stamp indicates The time when the first communication device sends the third optical signal is the fifth time t5;

Generating a sixth time stamp by the second communication device, where the sixth time stamp indicates that the time when the second communication device receives the third optical signal is the sixth time t6;

The second communication device sends a fourth optical signal with a wavelength of the first wavelength to the first communication device on the second optical fiber, the second communication device generates a seventh time stamp, and the seventh The time stamp indicates that the time when the second communication device sends the fourth optical signal is the seventh time t7;

The second communication device receives an eighth timestamp sent by the first communication device on the second optical fiber, where the eighth timestamp indicates the moment when the first communication device receives the fourth optical signal Is the eighth time t8;

The second communication device according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, and the The seventh time t7 and the eighth time t8 are time synchronized with the first communication device.
The method according to claim 1, wherein the second communication device is based on the first time t1, the second time t2, the third time t3, the fourth time t4, and the Performing time synchronization with the first communication device at the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 includes:

The second communication device determines the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4;

The second communication device determines a second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8;

Determining, by the second communication device, a time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation;

The second communication device performs time synchronization with the first communication device according to the time deviation N.
The method of claim 2, wherein:

The second communication device determining the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4 includes:

The first deviation N1 satisfies the calculation formula: N1=[(t2-t1)-(t4-t3)]/2;

The second communication device determining the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 includes:

The first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8-t7)]/2;

The second communication device determining the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation includes:

The time deviation N satisfies the calculation formula: N=(N1+N2)/2.
The method according to any one of claims 2 or 3, wherein the method further comprises:

The second communication device determines the approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, and the approximate synchronization error S1 is the difference between the first deviation N1 and the total time delay. The difference of the time deviation N.
The method according to any one of claims 2 or 3, wherein the method further comprises:

The second communication device determines the approximate synchronization error S2 of the two-way delay on the second optical fiber according to the time deviation N and the second deviation N2, where the approximate synchronization error S2 is the difference between the second deviation N2 and the second deviation N2. The difference of the time deviation N.
The method of claim 4, wherein the method further comprises:

The second communication device performs time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1;

The second communication device receives a first optical pulse signal with a wavelength of the second wavelength on the second optical fiber for detection, and the second communication device transmits on the second optical fiber a wavelength of the first optical pulse signal. The second optical pulse signal of the wavelength is detected.
The method of claim 5, wherein the method further comprises:

The second communication device performs time synchronization with the first communication device on the second optical fiber according to the second deviation N2 and the approximate synchronization error S2;

The second communication device receives a third optical pulse signal with a wavelength of the first wavelength on the first optical fiber for detection, and the second communication device transmits a third optical pulse signal with a wavelength of the second wavelength on the first optical fiber. The wavelength of the fourth optical pulse signal is detected.
A time synchronization method, characterized in that it includes:

The first communication device sends a first optical signal with a wavelength of a first wavelength on a first optical fiber to a second communication device, the first optical signal carries a first time stamp, and the first time stamp indicates the first communication The time when the device sends the first optical signal is the first time t1, and the time when the second communication device receives the first optical signal is the second time t2;

The first communication device receives the second optical signal with the second wavelength sent by the second communication device on the first optical fiber, and the time when the second communication device sends the second optical signal is the first Three time t3;

The first communication device sends a fourth time stamp on the first optical fiber to the second communication device, where the fourth time stamp indicates that the time when the first communication device receives the second optical signal is fourth Time t4;

The first communication device sends a third optical signal with a wavelength of the second wavelength on a second optical fiber to the second communication device, the third optical signal carries a fifth time stamp, and the fifth time stamp Instruct the first communication device to send the third optical signal at the fifth time t5, and the second communication device to receive the third optical signal at the sixth time t6;

The first communication device receives the fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7, the eighth The time stamp indicates that the time when the first communication device receives the fourth optical signal is the eighth time t8;

The first communication device sends the eighth time stamp on the second optical fiber to the second communication device, so that the second communication device sends the eighth time stamp according to the first time t1, the second time t2, and the second time t2. The third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 are time synchronized with the first communication device .
A time-synchronized communication device, characterized by comprising a processor and a channel medium conversion module, the processor and the channel medium conversion module establish a communication connection,

The channel medium conversion module is configured to receive a first optical signal with a wavelength of a first wavelength sent by the first communication device on a first optical fiber, the first optical signal carries a first time stamp, and the first optical signal The time stamp indicates that the time when the first communication device sends the first optical signal is the first time t1, and the time when the channel medium conversion module receives the first optical signal is the second time t2;

The channel medium conversion module is further configured to send a second optical signal with a second wavelength on the first optical fiber to the first communication device, and the channel medium conversion module sends the second optical signal to the first optical fiber. Time is the third time t3;

The channel medium conversion module is further configured to receive a fourth time stamp sent by the first communication device on the first optical fiber, where the fourth time stamp indicates that the first communication device receives the second The time of the optical signal is the fourth time t4;

The channel medium conversion module is further configured to receive a third optical signal with a wavelength of the second wavelength sent by the first communication device on a second optical fiber, and the third optical signal carries a fifth time stamp, so The fifth time stamp indicates that the time when the first communication device sends the third optical signal is the fifth time t5, and the time when the channel medium conversion module receives the third optical signal is the sixth time t6;

The channel medium conversion module is further configured to send a fourth optical signal with a wavelength of the first wavelength to the first communication device on the second optical fiber, and the channel medium conversion module sends the fourth optical signal. The time of the optical signal is the seventh time t7;

The channel medium conversion module is further configured to receive an eighth time stamp sent by the first communication device on the second optical fiber, and the eighth time stamp indicates that the first communication device received the fourth light The time of the signal is the eighth time t8;

The processor is configured to, according to the first time t1, the second time t2, the third time t3, the fourth time t4, the fifth time t5, and the sixth time t6, The seventh time t7 and the eighth time t8 are time synchronized with the first communication device.
The communication device according to claim 9, wherein the processor is based on the first time t1, the second time t2, the third time t3, the fourth time t4, and the first time t2. The fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 to synchronize time with the first communication device include:

Determining, by the processor, a first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4;

Determining, by the processor, a second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8;

Determining, by the processor, a time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation;

The processor performs time synchronization with the first communication device according to the time deviation N.
The communication device according to claim 10, wherein:

The processor determining the first deviation N1 according to the first time t1, the second time t2, the third time t3, and the fourth time t4 includes:

The first deviation N1 satisfies the calculation formula: N1=[(t2-t1)-(t4-t3)]/2;

The processor determining the second deviation N2 according to the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 includes:

The first deviation N2 satisfies the calculation formula: N2=[(t6-t5)-(t8-t7)]/2;

The processor determining the time deviation N of the second communication device relative to the first communication device according to the first deviation and the second deviation includes:

The time deviation N satisfies the calculation formula: N=(N1+N2)/2.
The communication device according to any one of claims 10 or 11, wherein:

The processor is further configured to determine an approximate synchronization error S1 of the two-way delay on the first optical fiber according to the time deviation N and the first deviation N1, where the approximate synchronization error S1 is the first deviation N1 and the first deviation N1. The difference of the time deviation N.
The communication device according to claim 12, wherein:

The processor is further configured to perform time synchronization with the first communication device on the first optical fiber according to the first deviation N1 and the approximate synchronization error S1;

The channel medium conversion module is further configured to receive a first optical pulse signal with a wavelength of the second wavelength on the second optical fiber for detection, and send a first optical pulse signal with a wavelength of the first wavelength on the second optical fiber Two light pulse signals are detected.
The communication device according to claim 9, wherein the second communication device further comprises a stamping module, and when the channel medium conversion module receives the first optical signal, the stamping module generates a first Time stamp; when the channel medium conversion module sends the second optical signal, the stamping module generates a second time stamp; when the channel medium conversion module receives the third optical signal, the stamping module A fifth time stamp is generated; when the channel medium conversion module sends the fourth optical signal, the stamping module generates an eighth time stamp.
The communication device according to any one of claims 10 to 13, wherein the channel medium conversion module includes an optical transmitting and receiving module.
A time-synchronized communication device, characterized by comprising a processor and a channel medium conversion module, the processor and the channel medium conversion module establish a communication connection,

The channel medium conversion module is configured to send a first optical signal with a wavelength of a first wavelength to a second communication device on a first optical fiber, the first optical signal carries a first time stamp, and the first time stamp indicates The time when the channel medium conversion module sends the first optical signal is the first time t1, and the time when the second communication device receives the first optical signal is the second time t2;

The channel medium conversion module is further configured to receive a second optical signal with a second wavelength sent by the second communication device on the first optical fiber, and the second communication device sends the second optical signal Is the third time t3;

The channel medium conversion module is further configured to send a fourth time stamp on the first optical fiber to the second communication device, the fourth time stamp indicating that the channel medium conversion module receives the second optical signal Time is the fourth time t4;

The channel medium conversion module is further configured to send a third optical signal with a wavelength of the second wavelength to the second communication device on a second optical fiber, the third optical signal carries a fifth time stamp, and the The fifth time stamp indicates that the time when the channel medium conversion module sends the third optical signal is the fifth time t5, and the time when the second communication device receives the third optical signal is the sixth time t6;

The channel medium conversion module is further configured to receive a fourth optical signal sent by the second communication device on the second optical fiber, and the time when the second communication device sends the fourth optical signal is the seventh time t7;

The channel medium conversion module is further configured to send an eighth time stamp on the second optical fiber to the second communication device, so that the second communication device can be based on the first time t1 and the second time t2, the third time t3, the fourth time t4, the fifth time t5, the sixth time t6, the seventh time t7, and the eighth time t8 and the first communication device Synchronously, the eighth time stamp indicates that the time when the channel medium conversion module receives the fourth optical signal is the eighth time t8;

The processor is configured to communicate with the channel medium conversion module.
A time synchronization system, characterized in that the system comprises the communication device according to any one of claims 9-15 and the communication device according to claim 16.