WO2021147042A1

WO2021147042A1 - Time synchronization method and device

Info

Publication number: WO2021147042A1
Application number: PCT/CN2020/073915
Authority: WO
Inventors: 刘永志; 李永祥; 张科
Original assignee: 华为技术有限公司
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2021-07-29
Also published as: CN114868354A

Abstract

Disclosed in the present application are a time synchronization method and device. In the method, a first device and a second device can achieve time synchronization of a 1588 protocol by means of cell switch. Thus, the method can achieve accurate time synchronization among communication devices supporting cell transmission.

Description

Time synchronization method and equipment

Technical field

This application relates to the field of communication technology, in particular to design a time synchronization method and device.

Background technique

In digital communication systems, the 1588 protocol (also known as the precision time protocol (PTP)) usually needs to implement time synchronization between communication devices via Ethernet, that is, messages used for time synchronization need to pass Ethernet messages The way to transmit between communication devices. However, in some scenarios, communication devices that also need to perform accurate time synchronization transmit service data in the form of cells, such as in the scenario of a cell system and a multi-frame cluster of products. Then, if the traditional time synchronization method is still implemented in these scenarios, additional Ethernet ports need to be added between the communication devices to send Ethernet packets, which increases the cost of the communication devices.

Summary of the invention

This application provides a time synchronization method and device to support precise time synchronization between communication devices for cell transmission.

In the first aspect, the embodiments of the present application provide a time synchronization method, which can be applied to two communication devices that perform service transmission in the cell mode. For ease of description, the delay requester is referred to as the first device below. , The delayed responder is called the second device. Among them, the method includes the following steps:

The first device sends the first information element to the second device, and determines the first moment, where the first information element contains the first reference bit, and the first moment is for the first device to send the first The moment of the first reference bit in the cell; the first device receives a second cell from the second device, wherein the second cell contains a first time bit field and a second reference bit , The first time bit field is used to indicate the second moment when the second device receives the first reference bit in the first cell; the first device determines the third moment, the first Time three is the time when the first device receives the second reference bit in the second information element; the first device receives the third information element from the second device, where the third information element The element includes a second time bit field, and the second time bit field is used to indicate the fourth moment when the second device sends the second reference bit in the second cell; finally, the first The device performs time synchronization with the second device according to the first time, the second time, the third time, and the fourth time.

Through this method, the first device and the second device can interact with information elements to realize the time synchronization of the 1588 protocol. Therefore, this method can achieve precise time synchronization between communication devices that support cell transmission. In addition, any communication system that supports cell transmission can realize time synchronization based on the 1588 protocol in cell mode through this method, which can replace the traditional method of carrying the 1588 protocol based on the Ethernet mode, which is convenient for the deployment of the 1588 system. Further, Since the communication device supporting cell transmission can realize the time synchronization of the 1588 protocol without adding an additional Ethernet port, this method can also save the overhead caused by the hardware port.

In a possible design, the first reference bit and the second reference bit may be set in the following manner:

Manner 1: The first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell;

Manner 2: The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1. An integer less than or equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell;

Manner 3: The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.

This design can improve the flexibility of setting the reference bit in the time synchronization related cell.

In a possible design, the first device saves the time corresponding to each clock cycle during the process of receiving the second cell; after receiving the second cell, the first device determines to receive Determining the target clock cycle where the second reference bit in the second cell is located, and determining that the time corresponding to the target clock cycle is the third time.

In the process of receiving the second cell, the first device cannot determine the type of the cell, nor can it directly determine the moment of receiving the second reference bit in the second cell. By design, the first device may determine by determining the target clock cycle in which the second reference bit is received after receiving the second cell.

In a possible design, the first time is the time when the first device physically encodes the first reference bit; the third time is the first device to the second reference bit The moment of physical decoding.

In a possible design, the first cell is a delay request cell, the second cell is a delay response cell, and the third cell is a follow cell.

In the second aspect, the embodiments of the present application provide a time synchronization method, which can be applied to two communication devices that perform service transmission in a cell manner. For ease of description, the delay requester is hereinafter referred to as the first device , The delayed responder is called the second device. Among them, the method includes the following steps:

The second device receives the first information element from the first device, and determines a second time, the first information element includes a first reference bit, and the second time is when the second device receives the first information element The first reference bit time in the second device; the second device sends a second information element to the first device, and determines the fourth time, and the second information element contains the first time bit field and the second time bit field. Reference bit, the first time bit field is used to indicate the second moment, and the fourth moment is the moment when the second device sends the second reference bit in the second cell; the The second device sends a third information element to the first device, where the third information element includes a second time bit field, and the second time bit field is used to indicate the fourth time.

Manner 2: The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1. , And an integer less than or equal to N, where N is less than or equal to the total number of bits contained in the first cell, and less than or equal to the total number of bits contained in the second cell;

In a possible design, the second device saves the time corresponding to each clock cycle during the process of receiving the first cell; after receiving the first cell, the second device determines to receive Determining the target clock cycle where the first reference bit in the first cell is located, and determining that the time corresponding to the target clock cycle is the second time.

In the process of receiving the first cell, the second device cannot determine the type of the cell, nor can it directly determine the moment of receiving the first reference bit in the first cell. By design, the second device may determine the target clock cycle in which the first reference bit is received after receiving the first cell.

In a possible design, the second moment is the moment when the second device physically decodes the first reference bit; the fourth moment is when the second device performs physical decoding on the second reference bit. The moment of physical encoding.

In a third aspect, an embodiment of the present application provides a communication device, which includes a unit for executing each step in the first aspect or the second aspect above.

In a fourth aspect, an embodiment of the present application provides a communication device, including at least one processing element and at least one storage element, wherein the at least one storage element is used to store programs and data, and the at least one processing element is used to execute the above The method provided by the first or second aspect.

In a fifth aspect, an embodiment of the present application provides a communication system, including a first device and a second device, wherein the first device has the function of executing the method provided in the first aspect of the present application, and the second device has The function of the method provided in the second aspect of this application.

In a sixth aspect, the embodiments of the present application also provide a computer program, which when the computer program runs on a computer, causes the computer to execute the method provided in the first aspect or the second aspect.

In a seventh aspect, the embodiments of the present application also provide a computer-readable storage medium in which a computer program is stored. When the computer program is executed by a computer, the computer is caused to execute the first The method provided by the aspect or the second aspect.

In an eighth aspect, an embodiment of the present application also provides a chip, which is used to read a computer program stored in a memory and execute the method provided in the first aspect or the second aspect.

In a thirteenth aspect, an embodiment of the present application also provides a chip system, which includes a processor, and is configured to support a computer device to implement the method provided in the first aspect or the second aspect. In a possible design, the chip system further includes a memory, and the memory is used to store necessary programs and data of the computer device. The chip system can be composed of chips, or it can include chips and other discrete devices.

Description of the drawings

FIG. 1 is a schematic diagram of a time synchronization process based on the 1588 protocol provided by the prior art;

FIG. 2 is a structural diagram of a communication system provided by an embodiment of this application;

FIG. 3 is a flowchart of a time synchronization method provided by an embodiment of this application;

FIG. 4 is a schematic diagram of a logical function structure of a communication device provided by an embodiment of this application;

FIG. 5 is a flowchart of a time synchronization example provided by an embodiment of the application;

FIG. 6 is a structural diagram of a communication device provided by an embodiment of this application;

FIG. 7 is a structural diagram of a communication device provided by an embodiment of this application.

Detailed ways

This application provides a time synchronization method and device to support accurate time synchronization between devices for cell transmission. Among them, the method and the device are based on the same technical idea. Since the principles of the method and the device to solve the problem are similar, the implementation of the device and the method can be referred to each other, and the repetition will not be repeated.

Hereinafter, some terms in this application will be explained to facilitate the understanding of those skilled in the art.

1) A communication device is a device that transmits service data in a cell mode, and can also be referred to as a communication node or node. Exemplarily, the communication device may be a communication device in a frame cell system or a product multi-frame cluster.

2) Cell Model is a technology that transmits information or data in units of cells. As a fast grouping technology, the cell method can cut information or data into multiple cells through the adaptation layer of the communication device. Among them, the length of the cell may be fixed. In addition, in some implementation schemes, the length of the cell may also be variable.

Usually, the cell is mainly composed of two parts, namely the cell header and the cell payload. The cell header contains address and control information, and the cell payload contains data. According to the function division, the cell can include two types: control cell and service cell. The control cell is used to transmit control and management related data, and the business cell is used to transmit business data.

3), "and/or", describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and/or B, which can mean: A alone exists, A and B exist at the same time, and B alone exists. condition. The character "/" generally indicates that the associated objects are in an "or" relationship.

It should be noted that the multiple involved in this application refers to two or more. At least one refers to one or more.

In addition, it should be understood that in the description of this application, words such as “first” and “second” are only used for the purpose of distinguishing description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating Or imply the order.

Referring to FIG. 1 below, taking device A and device B as an example, the time synchronization principle of the traditional peer delay mechanism based on the 1588 protocol will be described.

The delay requester device A sends a delay request message (Pdelay_Request) to device B at time T1; device B receives the delay request message at time T2, and then sends a delay response message to device A at time T3 ( Pdelay_Response), wherein the delay response message includes the time T2 when the device B receives the delay request message; the device B sends the delay response message to the device A sends a follow-up message (Pdelay_Response_Follow_Up) of a delayed response message, where the follow-up message includes the time T3 when the device B sends the delayed response message; the device A receives the delay response message at time T4 Delay response message, and then receive the follow-up message, obtain T2 from the delayed response message, and obtain T3 from the follow-up message. Finally, the device A can use the following formula to determine all The average path delay between the device A and the device B:

meanPathDelay=[(T2-T1)+(T4-T3)]/2=[(T2-T3)+(T4-T1)]/2.

Finally, the device A can perform time synchronization with the device B according to the calculated average path delay.

Among them, in order to achieve time synchronization between device A and device B, the types of messages exchanged are Ethernet messages, that is, delayed response messages, delayed response messages, and follow-up messages of delayed response messages. Ethernet message. This requires device A and device B to have Ethernet ports and be able to send Ethernet packets.

However, we know that in some communication scenarios, communication devices that also need to perform accurate time synchronization transmit service data in the form of cells, such as in the scenario of a box cell system and a product multi-chassis cluster. Then, if the traditional time synchronization method is still implemented in these scenarios, additional Ethernet ports need to be added between communication devices to send Ethernet packets, which increases the cost of communication devices.

The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

FIG. 2 shows the architecture of a possible communication system to which the time synchronization method provided by the embodiment of the present application is applicable. In the communication system, the communication between the communication devices does not use the Ethernet port, and the communication device The service transmission is carried out in the cell mode between each other. As shown in the figure, the communication system includes multiple communication devices (communication device a, communication device b, and communication device c as shown in the figure), and each communication device can communicate with other communication devices.

In the communication system, each communication device maintains a local device time, and each communication device transmits and receives service data according to the locally maintained device time. However, due to various factors such as the physical location between the sender and the receiver of the service transmission, the communication equipment or cables through which the service data is transmitted, and the communication conditions between the communication interfaces, the transmission between the sender and the receiver Business data has a certain time delay.

In another step, the sender and receiver of each service transmission are also different. Therefore, the service transmission delay between the sender and receiver of each service transmission is not the same. For example, the service transmission delay of communication device a as the sender when performing service transmission with communication device b is 0.6 ms; for another example, the service transmission delay of communication device a as the sender when performing service transmission with communication device c is 0.4ms; for another example, the service transmission delay of the communication device b as the sender when performing service transmission with the communication device c is 0.5ms.

We know that the accuracy of time synchronization can determine the business transmission efficiency of the sender and receiver. Therefore, in order to ensure the efficiency of service transmission, the sender and receiver in the communication system need to perform a precise time synchronization process.

In order to achieve precise time synchronization between communication devices that support cell transmission, an embodiment of the present application provides a time synchronization method. This method can be applied to the communication system supporting cell transmission as shown in FIG. 2. Among them, the time synchronization method is implemented through the time synchronization principle of the 1588 protocol similar to FIG. 1. The method provided in the embodiment of the present application will be described in detail below with reference to the flowchart shown in FIG. 3. In the embodiments of the present application, in order to facilitate distinction and description, the delay requester in the communication system is referred to as the "first device", and the delay responder on the other side is referred to as the "second device".

S301: The first device sends a first information element to the second device, and determines a first time T1, where the first information element contains a first reference bit, and the first time T1 is sent by the first device The time of the first reference bit in the first cell. Optionally, the first information element may be referred to as a delay request information element.

S302: The second device receives the first information element from the first device, and determines a second time T2. The second time T2 is when the second device receives all of the first information elements. The moment of the first reference bit.

S303: The second device sends a second information element to the first device, and determines a third time T3, where the second information element includes a first time bit field and a second reference bit, and the second information element includes a first time bit field and a second reference bit. A time bit field is used to indicate the second time T2, and the third time T3 is the time when the second device sends the second reference bit in the second cell. Optionally, the second cell may be referred to as a delayed response cell.

S304: The first device receives the second information element from the second device, and determines a fourth time T4, where the fourth time T4 is when the first device receives the second information element The moment of the second reference bit.

S305: The second device sends a third information element to the first device, where the third information element includes a second time bit field, and the second time bit field is used to indicate the third time T3. The first device receives the third information element from the second device. The third cell may be referred to as a follow cell of the delayed response cell, or a follow cell.

S306: The first device performs time synchronization with the second device according to the first time T1, the second time T2, the third time T3, and the fourth time T4.

The first device may perform time synchronization in the manner described in the time synchronization principle based on the 1588 protocol above, which will not be repeated here.

In this application, when the first device and the second device send corresponding information elements, they usually encode information elements, for example, physical encoding is performed through a physical coding sublayer (PCS). Therefore, the first device and the second device may use the time at which the reference bit in the cell to be sent is encoded as the time at which the reference bit is sent, that is, the time at which the cell is sent.

However, when the first device and the second device receive the corresponding cells, they actually receive the encoded cells. Therefore, the first device and the second device cannot determine the encoded cells. The specific position of the reference bit in the middle, so that the moment of receiving the reference bit cannot be determined. In the embodiment of the present application, the first device and the second device may record the corresponding time for each clock cycle in the process of receiving the encoded cell, the reception is completed and the cell is decoded After that, the clock cycle of the reference bit in the cell is determined, and finally the recorded time corresponding to the clock cycle can be used as the time of receiving the cell.

Based on the above description, in step S302 of this embodiment, the second device may determine the second time T2 in the following manner:

The second device saves the time corresponding to each clock cycle during the process of receiving the first cell;

After receiving the first cell, the second device determines the target clock cycle in which the first reference bit in the first cell is received, and then determines that the time corresponding to the target clock cycle is the second Time T2.

Similarly, in step S304 of this embodiment, the first device may determine the fourth time T4 in the following manner:

The first device saves the time corresponding to each clock cycle during the process of receiving the second cell;

After receiving the second cell, the first device determines the target clock cycle in which the second reference bit in the second cell is received, and then determines that the time corresponding to the target clock cycle is the fourth Time T4.

In addition, it should be noted that, in the embodiment of the present application, in order to ensure the accuracy of the first device's final time synchronization, the first device and the second device need to be negotiated in advance or stipulated by agreement. The selection rule of the reference bit in the cell used for time synchronization, that is, the first reference bit in the first cell and the second reference bit in the second cell use the same As determined by the rules, the two may have the same position or the same function in the cell where they are located.

Exemplarily, the first reference bit and the second reference bit may be, but not limited to, the following forms:

Form 1: The first reference bit is the most significant bit (MSB) in the first cell, and the second reference bit is the MSB in the second cell.

Form 2: The first reference bit is the least significant bit (LSB) in the first cell, and the second reference bit is the LSB in the second cell.

Form 3: The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or An integer equal to 1 and less than or equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell.

Form 4: The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.

Finally, it should be noted that the embodiment of the present application does not limit the timing of executing the above-mentioned time synchronization process. Optionally, the first device may initiate the time synchronization process when performing service transmission with the second device for the first time, or the first device may periodically perform the time synchronization process, or the first device The time synchronization process may be executed after receiving the time synchronization instruction, or the first device may periodically execute the time synchronization process. In addition, the embodiment of the present application does not limit the types of related cells in the execution of the above-mentioned time synchronization process. The above-mentioned first cell, second cell, and third cell may be control cells.

The embodiment of the present application provides a time synchronization method. In this method, the first device and the second device can exchange information elements to achieve time synchronization of the 1588 protocol. Therefore, this method can achieve precise time synchronization between communication devices that support cell transmission. In addition, any communication system that supports cell transmission can realize time synchronization based on the 1588 protocol in cell mode through this method, which can replace the traditional method of carrying the 1588 protocol based on the Ethernet mode, which is convenient for the deployment of the 1588 system. Further, Since the communication device supporting cell transmission can realize the time synchronization of the 1588 protocol without adding an additional Ethernet port, this method can also save the overhead caused by the hardware port.

Based on the function of each communication device in the communication system shown in FIG. 2 and the time synchronization method shown in FIG. 3, an embodiment of the present application also provides a communication device. Each unit/module in the communication device is divided according to the logic function of the communication device in the embodiment shown in FIG. 3. Referring to FIG. 4, the communication device includes: a time processing unit, a cell processor, a PCS, and a physical interface. The function of each module is described in detail below.

The time processing unit is used to record and save the time stamp of the communication device, and perform time synchronization according to the saved time stamp information.

For example, when the communication device is the delayed responder, the time processing unit may record the time T2 when the reference bit in the delayed request cell is received, and send the delayed response cell to the delayed requester. Reference bit time T3.

When the communication device is the delay requester, the time processing unit may record the time T1 at which the communication device sends the reference bit in the delay request cell to the delay responder, and the communication device receives the delay response The time T4 of the reference bit in the cell, the time T2 when the delay responder obtained from the delay response cell receives the reference bit in the delay request cell, and the cell processing unit The time T3 at which the delayed responder, obtained from the following cell of the delayed response cell, sends the reference bit in the delayed response cell. In addition, the cell processing unit may also perform time synchronization in accordance with the method in the time synchronization principle of the 1588 protocol according to the above-mentioned four saved times.

The cell processing unit is configured to process related cells for service transmission performed by the communication device, and may also process cells related to time synchronization. As shown in FIG. 4, according to different functions in the transmit (Tx) direction and the receive (Rx) direction, the cell processing unit can be divided into a transmit (Tx) unit and a receive (Rx) unit. Wherein, the sending unit is mainly used to generate a cell, send the cell to the PCS for encoding, and finally send it out through a physical interface. The sending unit is mainly used to receive the cell decoded by the PCS, and perform related operations according to the type of the cell and the data in the cell.

The PCS is used to perform physical encoding and physical decoding processing on cells. As shown in FIG. 4, according to the different functions of the Tx direction and the Rx, the cell processing unit can be divided into an encoding unit and a decoding unit. Wherein, the encoding unit is used to perform physical encoding processing on the information element to be sent, and send the physically encoded information element to other communication devices through the physical interface. The decoding unit is configured to perform physical decoding processing on the physically encoded cells received by the physical interface to obtain the cells, and send the cells obtained after physical decoding to the cell processing unit for further processing.

The physical interface can be connected to other communication devices through cables, and is used to communicate and interact with other communication devices by receiving and sending cells. Optionally, the physical interface may be a serial interface (serdes). As shown in Figure 4, according to the Tx direction and the different functions of the Rx, the physical interfaces can be divided into Tx physical interfaces and Rx physical interfaces. Wherein, the Tx physical interface is used to send physically encoded cells to other communication devices. The Rx physical interface is used to receive physically encoded cells from other communication devices.

Based on the time synchronization method shown in FIG. 3 and the logical function structure of the communication device shown in FIG. 4, the embodiment of the present application also provides a time synchronization example. Among them, in order to facilitate the distinction and description, this example refers to the delay requester as "communication device A", and the delay responder as "communication device B". Since the communication equipment A and the communication equipment B have the same unit/module, in order to distinguish the units/modules, this example adds A after the names of the units/modules belonging to the communication equipment A, and will belong to the units/modules of the communication equipment B /Add B after the name of the module. Refer to Figure 5 below to describe the process of this time synchronization instance:

(1): The sending unit A in the communication device A generates a delay request cell (Prequest-cell) (abbreviated as Preq-cell in the figure). Then the sending unit A sends the delay request information element to the coding unit A in the PCS A.

(2): The encoding unit A physically encodes the received delay request information element, and sends the physically encoded delay request information element to the Tx physical interface A. Wherein, when the encoding unit A physically encodes the delay request cell, when the encoding unit A physically encodes the MSB in the delay request cell, collect the current time T1 (communication The time when the device A sends the delay request cell), and sends it to the time processing unit A of the communication device A. The time processing unit A saves the time T1.

(3): The Tx physical interface A sends the encoded delay request cell to the communication device B.

(4): After receiving the encoded delay request cell, the Rx physical interface B in the communication device B sends it to the decoding unit B in the PCS B.

(5): The decoding unit B records the time corresponding to each clock cycle during the process of receiving the encoded delay request information element. The decoding unit B physically decodes the received encoded delay request cell, and after obtaining the delay request cell, it records multiple clocks in the process of receiving the encoded delay request cell The time corresponding to the cycle and the delay request cell obtained by decoding are sent to the receiving unit B in the cell processing unit B.

(6): After receiving the above content, the receiving unit B determines that the received cell is a delay request cell (for example, it can be determined by the indication in the delay request cell, or determined according to the cell identifier, or After determining according to the type of the cell), identify the MSB in the delay request cell, determine the target clock cycle where the MSB is received, and finally determine the time T2 corresponding to the target clock cycle, and use this time as the communication The time when the device B receives the delay request cell. The receiving unit B sends the time T2 to the sending unit B, and notifies the sending unit B to make a delayed response.

(7): After receiving the notification from the receiving unit B, the sending unit B generates a delayed response cell (Presponse-cell) (abbreviated as Prsp-cell in the figure) containing the received time T2. Then, the sending unit B sends the delayed response information element to the coding unit B in the PCS B.

(8): The encoding unit B physically encodes the received delay response information element, and sends the physically encoded delay response information element to the Tx physical interface B. Wherein, when the encoding unit B physically encodes the delay response cell, when the encoding unit B physically encodes the MSB in the delay response cell, collect the current time T3 (communication The time when the device B sends the delayed response cell), and sends it back to the sending unit B.

(9): The sending unit B generates a follow-up cell (Presponse-follow-up-cell) containing the delayed response cell at the time T3 when receiving the time T3 returned by the coding unit B (Figure Chinese abbreviated as Prfu-cell). Then, the sending unit B sends the following information element to the coding unit B in the PCS B.

(10): The encoding unit B physically encodes the received follow-up cell, and sends the encoded follow-up cell to the Tx physical interface B.

(11): The Tx physical interface B sends the encoded delayed response cell and the encoded follow cell to the communication device A respectively.

(12): After the Rx physical interface A in the communication device A receives the encoded delayed response cell and the encoded follow-up cell, respectively, it sends them to the decoding unit A in the PCS A.

(13): The decoding unit A records the time corresponding to each clock cycle during the process of receiving the encoded delayed response cell. The decoding unit A physically decodes the received encoded delayed response cell, and after obtaining the delayed response cell, it records multiple clocks during the process of receiving the encoded delayed response cell The time corresponding to the cycle and the delayed response cell obtained by decoding are sent to the receiving unit A in the cell processing unit A.

After receiving the encoded follower cell, the decoding unit A physically decodes the encoded follower cell to obtain the follower cell. Then the decoding unit A sends the following information element obtained by decoding to the receiving unit A.

(14): The receiving unit A determines that the received information element is a delayed response signal after receiving the time corresponding to the multiple clock cycles recorded by the decoding unit A and the delayed response cell obtained by decoding. After the element (for example, it can be determined by the indication in the delayed response cell, or determined according to the cell identifier, or determined according to the type of the cell), the MSB in the delayed response cell is identified, and the MSB is determined to be received Where the target clock cycle is located, the time T4 corresponding to the target clock cycle is finally determined, and this time is used as the time at which the communication device A receives the delayed response cell. The receiving unit A sends the time T4 to the time processing unit A of the communication device A. The time processing unit A saves the time T4.

The receiving unit A obtains the time T2 contained in the delayed response cell, and sends the time T2 to the time processing unit A. The time processing unit A saves the time T2.

After receiving the decoded follower cell, the receiving unit A obtains the time T3 contained in the follower cell from the follower cell, and sends the time T3 to the time processing unit A. The time processing unit A saves the time T3.

(15): The time processing unit A performs time synchronization with the communication device B according to the four saved moments.

It should be noted that, in an example, the communication device A may initiate the above time synchronization process to multiple other communication devices at the same time, and the communication device A may also initiate the above time synchronization process to the same communication device multiple times. In order to ensure the accuracy of time synchronization, the two communication devices of time synchronization can recognize that clock synchronization related cells (delay request cell, delay response cell, and follow cell of delay response cell) belong to the same time synchronization For the process, in this example, the process identifier can be added to the above-mentioned relevant information element. Optionally, the process identifier can be any one or a combination of the following:

Time synchronization sequence number (sequence ID), link number of the physical interface, identification of the communication device A, and identification of the communication device B.

Similarly, the time processing unit A in the communication device A is also grouped with the saved time according to the process identifier. That is, all the moments in the same moment group are saved for the same process ID.

In this way, the receiving unit A in the communication device A can first perform pairing verification after receiving the delayed response cell and the follow cell, that is, verify whether the received delayed response cell and the process identifier in the follow cell are the same as the sender The process ID in the delay request cell is the same. If they are not the same, the receiving unit A discards the delayed response cell and the following cell; if they are the same, the receiving unit A performs subsequent operations according to the delayed response cell and the following cell.

According to the sending time of the following cell, it can be known that the communication device A should finally determine the time T3. Therefore, the order of the time when the communication device A saves time synchronization is: T1-T2/T4-T3. Therefore, when the communication device A determines that any one of the time groups saved for the same process identifier is invalid, the time group is discarded.

In addition, from the specific process description of the above example, it can be seen that this example uses the physical medium attachment (PMA) mechanism of the communication device to time stamp. This mechanism can avoid the traditional PCS layer and forward error correction. The time jitter caused by the time stamping of the forward error correction (FEC) layer can further improve the accuracy of time synchronization.

Based on the same technical concept, an embodiment of the present application also provides a communication device. The structure of the device is shown in FIG. 6 and includes a communication unit 601 and a processing unit 602. The communication device 600 can be applied to the communication device of the communication system shown in FIG. 2 and can implement the time synchronization method provided in the above embodiments or examples. In the embodiment of the present application, the communication device 600 can be applied to both the delay requester in the communication system (referred to as the first device for short) and the delay responder in the communication system (referred to as the second device for short). ).

The functions of each unit in the device 600 are introduced below.

The communication unit 601 is used to receive and send information elements. Wherein, the communication unit 601 can implement the above-mentioned transceiver function through a physical interface (for example, serdes) and a PCS.

In an implementation manner, when the communication device 600 is applied to the first device, the functions of each unit are as follows:

The processing unit 602 is configured to send a first information element to the second device through the communication unit 601 and determine a first moment, where the first information element includes a first reference bit, and the first moment Is the time when the communication unit 601 sends the first reference bit in the first cell; the second cell is received from the second device through the communication unit 601, and the second cell contains A first time bit field and a second reference bit, where the first time bit field is used to indicate the second moment when the second device receives the first reference bit in the first cell; determining the third Time, the third time is the time when the communication unit 601 receives the second reference bit in the second information element; the third information element is received from the second device through the communication unit 601, where The third information element includes a second time bit field, and the second time bit field is used to indicate the moment when the second device sends the second reference bit in the second information element; and according to the Perform time synchronization with the second device at the first time, the second time, the third time, and the fourth time;

The communication unit 601 is configured to send the first information element, and receive the second information element and the third information element.

Optionally, the first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell; or

The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1, and less than Or an integer equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell; or

The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.

Optionally, the processing unit 602, when receiving the second information element from the second device through the communication unit 601 and determining the third time, is specifically configured to:

Save the time corresponding to each clock cycle during the process of receiving the second cell by the communication unit 601;

After the communication unit 601 receives the second cell, it determines the target clock cycle in which the second reference bit in the second cell is received, and determines that the time corresponding to the target clock cycle is the first Three moments.

Optionally, the first cell is a delay request cell, the second cell is a delay response cell, and the third cell is a follow cell.

In another implementation manner, when the communication device 600 is applied to a second device, the functions of each unit are as follows:

The processing unit 602 is configured to receive a first information element from a first device through the communication unit 601, and determine a second time, where the first information element includes a first reference bit, and the second time is the communication The unit 601 receives the moment of the first reference bit in the first cell; sends a second cell to the first device through the communication unit 601, and determines the fourth moment, the second cell Contains a first time bit field and a second reference bit, the first time bit field is used to indicate the second time, and the fourth time is all the information in the second cell sent by the communication unit 601 The time of the second reference bit; and sending a third information element to the first device through the communication unit 601, wherein the third information element includes a second time bit field, and the second time bit field Used to indicate the fourth moment;

The communication unit 601 is configured to receive the first information element, and send the second information element and the third information element.

Optionally, the processing unit 602, when receiving the first information element from the first device through the communication unit 601 and determining the second time, is specifically configured to:

Save the time corresponding to each clock cycle during the process of receiving the first cell by the communication unit 601;

After the communication unit 601 receives the first cell, it determines the target clock period in which the first reference bit in the first cell is received, and determines that the time corresponding to the target clock period is the The second moment.

It should be noted that the division of modules in the above embodiments of the present application is illustrative, and is only a logical function division. In actual implementation, there may be other division methods. In addition, each function in each embodiment of the present application The unit can be integrated into one processing unit, or it can exist alone physically, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.

If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including a number of instructions to enable a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program code .

Based on the same technical concept, the embodiments of the present application also provide a communication device, which can be applied to the communication system as shown in FIG. 2 and can implement the time synchronization method provided by the above embodiments or examples, and has The function of the communication device shown in FIG. 6. Referring to FIG. 7, the communication device 700 includes: a communication interface 701, a processor 702, and a memory 703. Wherein, the communication interface 701, the processor 702, and the memory 703 are connected to each other.

Optionally, the communication interface 701, the processor 702, and the memory 703 are connected to each other through a bus 704. The bus 704 may be a peripheral component interconnect standard (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, and so on. For ease of representation, only one thick line is used in FIG. 7, but it does not mean that there is only one bus or one type of bus.

The communication interface 701 is used to receive and send information elements to realize communication interaction with other communication devices.

The processor 702 is configured to process information elements, including processing such as generation, analysis, physical encoding and physical decoding, and time synchronization.

In one embodiment, when the communication device 700 is applied to the delay requester of two communication devices that require time synchronization (wherein, the delay requester is referred to as the first device, and the delay responder is referred to as the first In the case of two devices), the processor 702 is specifically configured to:

The first information element is sent to the second device through the communication interface 701, and the first time is determined, where the first information element includes the first reference bit, and the first time is the first device sending the first time. The moment of the first reference bit in a cell; a second cell is received from the second device through the communication interface 701, and the second cell includes a first time bit field and a second reference bit , The first time bit field is used to indicate the second time at which the second device receives the first reference bit in the first cell; the third time is determined, and the third time is the The moment when the first device receives the second reference bit in the second cell; the third cell is received from the second device through the communication interface 701, where the third cell contains the second time Bit field, the second time bit field is used to indicate the time when the second device sends the second reference bit in the second cell; and according to the first time, the second time, The third time and the fourth time are synchronized with the second device.

Optionally, the processor 702 is specifically configured to:

Saving the time corresponding to each clock cycle in the process of physically decoding the second cell;

After the physical decoding of the second cell is completed, determine the target clock cycle in which the second reference bit in the second cell is received, and determine that the time corresponding to the target clock cycle is the third time .

In another embodiment, when the communication device 700 is applied to the delayed responder of two communication devices that need time synchronization (wherein, the delayed responder is referred to as the second device for short, and the delayed requester is referred to as When it is the first device), the processor 702 is specifically configured to:

The first information element is received from the first device through the communication interface 701, and the second time is determined. The first information element includes the first reference bit, and the second time is when the second device receives the first information. The time of the first reference bit in the element; send a second information element to the first device through the communication interface 701, and determine the fourth time, the second information element contains the first time bit field and A second reference bit, where the first time bit field is used to indicate the second moment, and the fourth moment is the moment when the second device sends the second reference bit in the second cell; And sending a third information element to the first device through the communication interface 701, where the third information element includes a second time bit field, and the second time bit field is used to indicate the fourth time .

Optionally, the processor 702 is specifically configured to:

Saving the time corresponding to each clock cycle in the process of physically decoding the first cell;

After the physical decoding of the first cell is completed, determine the target clock cycle where the first reference bit in the first cell is received, and determine that the time corresponding to the target clock cycle is the second time .

It should be noted that the function of the processor 702 may refer to the description in the time synchronization method provided in the above embodiments and examples, and the specific function description of the communication device 600 in the embodiment shown in FIG. Go into details again.

The memory 703 is used to store program instructions and data. Specifically, the program instructions may include program code, and the program code includes computer operation instructions. The memory 703 may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory. The processor 702 executes the program instructions stored in the memory 703, and uses the data stored in the memory 703 to implement the above-mentioned functions, thereby realizing the time synchronization method provided in the above-mentioned embodiment.

It can be understood that the memory 703 in FIG. 7 of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory. Among them, the non-volatile memory can be read-only memory (Read-Only Memory, ROM), programmable read-only memory (Programmable ROM, PROM), erasable programmable read-only memory (Erasable PROM, EPROM), and electrically available Erase programmable read-only memory (Electrically EPROM, EEPROM) or flash memory. The volatile memory may be a random access memory (Random Access Memory, RAM), which is used as an external cache. By way of exemplary but not restrictive description, many forms of RAM are available, such as static random access memory (Static RAM, SRAM), dynamic random access memory (Dynamic RAM, DRAM), synchronous dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (Double Data Rate SDRAM, DDR SDRAM), Enhanced Synchronous Dynamic Random Access Memory (Enhanced SDRAM, ESDRAM), Synchronous Link Dynamic Random Access Memory (Synchlink DRAM, SLDRAM) ) And Direct Rambus RAM (DR RAM). It should be noted that the memories of the systems and methods described herein are intended to include, but are not limited to, these and any other suitable types of memories.

Based on the above embodiments, the embodiments of the present application also provide a computer program, which when the computer program runs on a computer, causes the computer to execute the time synchronization method provided in the above embodiments.

Based on the above embodiments, the embodiments of the present application also provide a computer-readable storage medium in which a computer program is stored. When the computer program is executed by a computer, the computer can execute the time provided in the above embodiment. Synchronization method.

The storage medium may be any available medium that can be accessed by a computer. Take this as an example but not limited to: computer readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or can be used to carry or store instructions or data in the form of structure The desired program code and any other medium that can be accessed by the computer.

Based on the above embodiments, an embodiment of the present application also provides a chip, which is used to read a computer program stored in a memory to implement the time synchronization method provided in the above embodiment.

Based on the above embodiments, the embodiments of the present application provide a chip system including a processor, which is used to support a computer device to implement the functions related to the communication device in the above embodiment. In a possible design, the chip system further includes a memory, and the memory is used to store necessary programs and data of the computer device. The chip system can be composed of chips, or include chips and other discrete devices.

In summary, the embodiments of the present application provide a time synchronization method and device. In this solution, the first device and the second device can exchange information elements to realize the time synchronization of the 1588 protocol. Therefore, this method can achieve precise time synchronization between communication devices that support cell transmission. In addition, any communication system that supports cell transmission can realize time synchronization based on the 1588 protocol in cell mode through this method, which can replace the traditional method of carrying the 1588 protocol based on the Ethernet mode to facilitate the deployment of the 1588 system. Further, Since the communication device supporting cell transmission can realize the time synchronization of the 1588 protocol without adding an additional Ethernet port, this method can also save the overhead caused by the hardware port.

Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

This application is described with reference to flowcharts and/or block diagrams of methods, equipment (systems), and computer program products according to this application. It should be understood that each process and/or block in the flowchart and/or block diagram, and the combination of processes and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing equipment are generated It is a device that realizes the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device. The device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment. The instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

Obviously, those skilled in the art can make various changes and modifications to this application without departing from the protection scope of this application. In this way, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, then this application is also intended to include these modifications and variations.

Claims

A time synchronization method, characterized in that it comprises:

The first device sends the first information element to the second device, and determines the first moment, where the first information element contains the first reference bit, and the first moment is for the first device to send the first The time of the first reference bit in the cell;

The first device receives a second information element from the second device, where the second information element includes a first time bit field and a second reference bit, and the first time bit field is used to indicate the The second device receives the second moment of the first reference bit in the first cell; the first device determines the third moment, and the third moment is the first device receiving the second moment The time of the second reference bit in the cell;

The first device receives a third information element from the second device, where the third information element includes a second time bit field, and the second time bit field is used to instruct the second device to send The fourth moment of the second reference bit in the second cell;

The first device performs time synchronization with the second device according to the first time, the second time, the third time, and the fourth time.
The method according to claim 1, wherein the first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell; or

The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1, and An integer less than or equal to N, where N is less than or equal to the total number of bits contained in the first cell, and less than or equal to the total number of bits contained in the second cell; or

The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.
The method according to claim 1 or 2, wherein the first device receiving the second information element from the second device comprises:

The first device saves the time corresponding to each clock cycle during the process of receiving the second cell;

The determining, by the first device, the third moment includes:

After receiving the second cell, the first device determines the target clock cycle in which the second reference bit in the second cell is received, and determines that the time corresponding to the target clock cycle is the first Three moments.
The method according to any one of claims 1-3, wherein the first cell is a delay request cell, the second cell is a delay response cell, and the third cell To follow the cell.
A time synchronization method, characterized in that it comprises:

The second device receives the first information element from the first device, and determines a second time, the first information element includes a first reference bit, and the second time is when the second device receives the first information element The time of the first reference bit in;

The second device sends a second information element to the first device and determines a fourth time. The second information element includes a first time bit field and a second reference bit, and the first time bit field uses When indicating the second moment, the fourth moment is the moment when the second device sends the second reference bit in the second cell;

The second device sends a third information element to the first device, where the third information element includes a second time bit field, and the second time bit field is used to indicate the fourth time.
The method according to claim 5, wherein the first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell; or

The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1, and less than Or an integer equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell; or

The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.
The method according to claim 5 or 6, wherein the second device receiving the first information element from the first device comprises:

The second device saves the time corresponding to each clock cycle during the process of receiving the first cell;

The determining of the second moment by the second device includes:

After receiving the first cell, the second device determines the target clock cycle where the first reference bit in the first cell is received, and determines that the time corresponding to the target clock cycle is the first cell. Two moments.
7. The method according to any one of claims 5-7, wherein the first cell is a delay request cell, the second cell is a delay response cell, and the third cell To follow the cell.
A communication device applied to a first device, characterized in that the device includes:

The communication unit is used to receive and send cells;

The processing unit is configured to send a first information element to the second device through the communication unit and determine a first moment, wherein the first information element includes a first reference bit, and the first moment is the communication The moment when the unit sends the first reference bit in the first cell; receives a second cell from the second device through the communication unit, and the second cell contains the first time bit field and The second reference bit, the first time bit field is used to indicate the second moment when the second device receives the first reference bit in the first cell; to determine the third moment, the third The time is the time when the communication unit receives the second reference bit in the second information element; the third information element is received from the second device through the communication unit, wherein the third information element contains the second reference bit A two-time bit field, where the second time bit field is used to indicate the moment when the second device sends the second reference bit in the second cell; and according to the first moment, the second Time, the third time, and the fourth time are synchronized with the second device.
9. The apparatus of claim 9, wherein the first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell; or

The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1, and less than Or an integer equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell; or

The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.
The device according to claim 9 or 10, wherein the processing unit is specifically configured to:

Saving the time corresponding to each clock cycle during the process of receiving the second cell by the communication unit;

After the communication unit receives the second cell, it determines the target clock cycle where the second reference bit in the second cell is received, and determines that the time corresponding to the target clock cycle is the third time.
The device according to any one of claims 9-11, wherein the first cell is a delay request cell, the second cell is a delay response cell, and the third cell is To follow the cell.
A communication device applied to a second device, characterized in that the device includes:

The communication unit is used to receive and send cells;

A processing unit, configured to receive a first information element from a first device through the communication unit, and determine a second time, the first information element includes a first reference bit, and the second time is received by the communication unit The time of the first reference bit in the first cell; the second cell is sent to the first device through the communication unit, and the fourth time is determined, and the second cell contains the first A time bit field and a second reference bit, the first time bit field is used to indicate the second moment, and the fourth moment is the second reference bit in the second cell sent by the communication unit And sending a third information element to the first device through the communication unit, wherein the third information element includes a second time bit field, and the second time bit field is used to indicate the first Four moments.
The apparatus according to claim 13, wherein the first reference bit is the most significant bit MSB in the first cell, and the second reference bit is the MSB in the second cell; or

The first reference bit is the nth bit in the first cell, the second reference bit is the nth bit in the second cell, where n is greater than or equal to 1, and less than Or an integer equal to N, where N is less than or equal to the total number of bits contained in the first cell and less than or equal to the total number of bits contained in the second cell; or

The first reference bit is the last bit in the first cell, and the second reference bit is the last bit in the second cell.
The device according to claim 13 or 14, wherein the processing unit is specifically configured to:

Saving the time corresponding to each clock cycle during the process of receiving the first cell by the communication unit;

After the communication unit receives the first cell, it determines the target clock cycle where the first reference bit in the first cell is received, and determines that the time corresponding to the target clock cycle is the second time.
The apparatus according to any one of claims 13-15, wherein the first cell is a delay request cell, the second cell is a delay response cell, and the third cell To follow the cell.
A communication device, characterized in that it comprises:

Communication interface for receiving and sending cells;

Memory, used to store program instructions and data;

The processor is configured to call the program instructions and data stored in the memory, and execute the method according to any one of claims 1-8 through the communication interface.
A computer program, characterized in that, when the computer program runs on a computer, the computer is caused to execute the method according to any one of claims 1-8.
A computer-readable storage medium, characterized in that a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a computer, the computer is caused to execute any one of claims 1-8. The method described.
A chip, characterized in that the chip is used to read a computer program stored in a memory and execute the method according to any one of claims 1-8.