CN114868354B

CN114868354B - Time synchronization method and equipment

Info

Publication number: CN114868354B
Application number: CN202080088865.1A
Authority: CN
Inventors: 刘永志; 李永祥; 张科
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2024-06-04
Anticipated expiration: 2040-01-22
Also published as: CN114868354A; WO2021147042A1

Abstract

The application discloses a time synchronization method and equipment, wherein in the method, first equipment and second equipment can realize time synchronization of 1588 protocol through cell interaction. Thus, the method can achieve accurate time synchronization between communication devices supporting cell transmission.

Description

Time synchronization method and equipment

Technical Field

The application relates to the technical field of communication, in particular to a time synchronization method and equipment.

Background

In digital communication systems, the 1588 protocol, also known as precision time protocol (precision time protocol, PTP), generally requires time synchronization between communication devices via ethernet, i.e. messages for time synchronization need to be transmitted between communication devices via ethernet messages. In some scenarios, however, it is also desirable to transmit traffic data between communication devices in the form of cells, such as in the case of frame cell (cell) systems and product multi-frame clusters, with accurate time synchronization. Then additional ethernet ports need to be added between the communication devices to send ethernet messages if still implemented in these scenarios in accordance with conventional time synchronization methods, which increases the cost of the communication devices.

Disclosure of Invention

The application provides a time synchronization method and equipment, which are used for supporting accurate time synchronization between communication equipment for cell transmission.

In a first aspect, an embodiment of the present application provides a time synchronization method, where the method may be applied to two communication devices that perform service transmission in a cell manner, and for convenience of explanation, a delay requester is hereinafter referred to as a first device, and a delay responder is referred to as a second device. Wherein the method comprises the following steps:

The method comprises the steps that first equipment sends a first cell to second equipment and determines first time, wherein the first cell contains a first reference bit, and the first time is the time when the first equipment sends the first reference bit in the first cell; the first device receives a second cell from the second device, wherein the second cell comprises a first time bit field and a second reference bit, and the first time bit field is used for indicating a second moment when the second device receives the first reference bit in the first cell; the first device determining a third time instant, the third time instant being a time instant when the second reference bit in the second cell is received by the first device; the first device receives a third cell from the second device, wherein the third cell comprises a second time bit field, and the second time bit field is used for indicating a fourth moment when the second device sends the second reference bit in the second cell; finally, 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.

By the method, the first device and the second device can realize time synchronization of 1588 protocol through cell interaction. Thus, the method can achieve accurate time synchronization between communication devices supporting cell transmission. In addition, any communication system supporting cell transmission can realize time synchronization of 1588 protocol based on cell mode by the method, thereby being capable of replacing the traditional method of carrying 1588 protocol based on Ethernet mode, being convenient for deployment of 1588 system.

In one possible design, the first reference bit and the second reference bit may be set by:

Mode one: 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;

Mode two: the first reference bit is an nth bit in the first cell, and the second reference bit is an nth bit in the second cell, where N is an integer greater than or equal to 1 and less than or equal to N, N is less than or equal to a total amount of bits contained in the first cell, and less than or equal to a total amount of bits contained in the second cell;

mode three: 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 design can improve the flexibility of setting the reference bits in the time synchronization related cells.

In one possible design, the first device stores a time corresponding to each clock cycle during the process of receiving the second cell; after receiving the second cell, the first device determines a target clock period in which the second reference bit in the second cell is received, and determines a time corresponding to the target clock period as the third time.

Since the first device cannot determine the type of the cell during the process of receiving the second cell, and cannot directly determine the time of receiving the second reference bit in the second cell, by this design, the first device can determine by determining the target clock cycle in which the second reference bit is received after the second cell is received.

In one possible design, the first time is a time when the first device physically encodes the first reference bit; the third time is a time when the first device performs physical decoding on the second reference bit.

In one possible design, the first cell is a delayed request cell, the second cell is a delayed response cell, and the third cell is a follow-up cell.

In a second aspect, an embodiment of the present application provides a time synchronization method, where the method may be applied to two communication devices that perform service transmission by using a cell manner, and for convenience of explanation, a delay requester is hereinafter referred to as a first device, and a delay responder is referred to as a second device. Wherein the method comprises the following steps:

The second device receives a first cell from the first device and determines a second time, wherein the first cell comprises a first reference bit, and the second time is the time when the second device receives the first reference bit in the first cell; the second device sends a second cell to the first device, and determines a fourth time, wherein the second cell comprises a first time bit field and a second reference bit, the first time bit field is used for indicating the second time, and the fourth time is the time when the second device sends the second reference bit in the second cell; the second device sends a third cell to the first device, wherein the third cell includes a second time bit field, and the second time bit field is used for indicating the fourth time.

In one possible design, the second device stores a time corresponding to each clock cycle during the process of receiving the first cell; and after receiving the first cell, the second device determines a target clock period in which the first reference bit in the first cell is received, and determines a time corresponding to the target clock period as the second time.

Since the second device cannot determine the type of the cell during the process of receiving the first cell, and cannot directly determine the time of receiving the first reference bit in the first cell, by the design, the second device can determine by determining the target clock cycle in which the first reference bit is received after the end of receiving the first cell.

In one possible design, the second time is a time when the second device physically decodes the first reference bit; the fourth time is a time when the second device performs physical encoding on the second reference bit.

In a third aspect, embodiments of the present application provide a communication apparatus comprising means for performing the steps of the above first or second aspects.

In a fourth aspect, embodiments of the present application provide a communications device comprising at least one processing element and at least one storage element, wherein the at least one storage element is for storing a program and data, and the at least one processing element is for performing the method provided in the above first or second aspect of the present application.

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

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

In a seventh aspect, an embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored, which when executed by a computer, causes the computer to perform the method provided in the first aspect or the second aspect.

In an eighth aspect, an embodiment of the present application further provides a chip, where the chip is configured to read a computer program stored in a memory, and perform the method provided in the first aspect or the second aspect.

In a thirteenth aspect, an embodiment of the present application further provides a chip system, where the chip system includes a processor, configured to support a computer device to implement the method provided in the first aspect or the second aspect. In one possible design, the chip system further includes a memory for storing programs and data necessary for the computer device. The chip system may be formed of a chip or may include a chip and other discrete devices.

Drawings

Fig. 1 is a schematic diagram of a time synchronization flow based on 1588 protocol provided in the prior art;

Fig. 2 is a block diagram of a communication system according to an embodiment of the present application;

FIG. 3 is a flowchart of a time synchronization method according to an embodiment of the present application;

Fig. 4 is a schematic diagram of a logic function structure of a communication device according to an embodiment of the present application;

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

fig. 6 is a block diagram of a communication device according to an embodiment of the present application;

fig. 7 is a block diagram of a communication device according to an embodiment of the present application.

Detailed Description

The application provides a time synchronization method and equipment, which are used for supporting accurate time synchronization between the equipment for cell transmission. The method and the device are based on the same technical conception, and because the principle of solving the problems by the method and the device is similar, the implementation of the device and the method can be mutually referred to, and the repetition is not repeated.

In the following, some terms used in the present application are explained for easy understanding by those skilled in the art.

1) The communication device is a device for transmitting service data in a cell manner, and may also be called a communication node or a node. The communication device may be, for example, a frame cell system or a communication device in a product multi-frame cluster.

2) Cell mode (Cell Model) is a technique for transmitting information or data in units of cells. Cell mode is a fast grouping technique that can cut information or data into cells through an adaptation layer of a communication device. Wherein the length of the cells may be fixed, and in some implementations, the length of the cells may be non-fixed.

Typically, a cell is mainly composed of two parts, namely a cell header and a cell payload. Contained in the cell header are address and control information, and the cell payload contains data. The cells may include both control cells and traffic cells according to a functional division. Wherein the control cells are used for transmitting control management related data and the service cells are used for transmitting service data.

3) "And/or" describes an association relationship of an associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.

The term "plurality" as used herein means two or more. At least one, meaning one or more.

In addition, it should be understood that in the description of the present application, the words "first," "second," and the like are used merely for distinguishing between the descriptions and not for indicating or implying any relative importance or order.

Referring now to fig. 1, a time synchronization principle of a conventional peer-to-peer delay (peerdelay) mechanism based on 1588 protocol will be described by taking a device a and a device B as examples.

The delay requester device A sends a delay Request message (Pdelay_request) to the device B at the time T1; the equipment B receives the delay request message at the moment T2, and then sends a delay Response message (Pdelay_response) to the equipment A at the moment T3, wherein the delay Response message comprises the moment T2 when the equipment B receives the delay request message; after the device B sends the delay Response message, sending a following message (pdelay_response_follow_up) of the delay Response message to the device a, where the following message includes a time T3 when the device B sends the delay Response message; the device a receives the delay response message at the time T4, then receives the following message, obtains T2 from the delay response message, obtains T3 from the following message, and finally, the device a can determine the average path delay between the device a and the device B through the following formula:

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

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

In order to realize time synchronization between the device A and the device B, the interactive message types are Ethernet messages, namely a delay response message, a delay response message and a following message of the delay response message are Ethernet messages. This requires that device a and device B have ethernet ports to be able to send ethernet messages.

However, it is known that in some communication scenarios, traffic data is transmitted in the form of cells between communication devices that also need to be precisely time synchronized, such as in the case of frame cell systems and product multi-frame clusters. Then additional ethernet ports need to be added between the communication devices to send ethernet messages if still implemented in these scenarios in accordance with conventional time synchronization methods, which increases the cost of the communication devices.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Fig. 2 shows a possible architecture of a communication system to which the time synchronization method provided by the embodiment of the present application is applicable, where communication between communication devices does not use an ethernet port, and traffic is transmitted between the communication devices by means of cells. As shown in the figure, in the communication system, a plurality of communication apparatuses (a communication apparatus a, b, and c shown in the figure) are included, each of which can communicate with other communication apparatuses.

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, the service data transmitted from the sender and the receiver have a certain time delay due to various factors such as the physical location between the sender and the receiver performing the service transmission, the communication device or cable through which the service data is transmitted, and the communication condition between the communication interfaces.

Further, the sender and the receiver of each service transmission are different, and thus, the service transmission delay between the sender and the receiver of each service transmission is also different. For example, the service transmission delay of the communication device a as the sender at the time of service transmission with the communication device b is 0.6ms; for another example, the service transmission delay of the communication device a as the sender when performing service transmission with the communication device c is 0.4ms; for another example, the service transmission delay of the communication device b as the sender at the time of service transmission with the communication device c is 0.5ms.

The accuracy of time synchronization is known to determine the traffic efficiency of both the transmitter and receiver. Therefore, in order to ensure the efficiency of service transmission, the sender and the receiver in the communication system need to perform a precise time synchronization process.

In order to achieve accurate time synchronization between communication devices supporting cell transmission, the embodiment of the application provides a time synchronization method. The method can be applied to the communication system supporting cell-wise transmission shown in fig. 2. The time synchronization method is implemented by a time synchronization principle of 1588 protocol similar to that of fig. 1. The method provided by the embodiment of the present application is described in detail below with reference to the flowchart shown in fig. 3. In the embodiment of the present application, for convenience of distinction and description, a latency requester in a communication system is referred to as a "first device", and a latency responder on the other side is referred to as a "second device".

S301: the method comprises the steps that a first device sends a first cell to a second device and determines a first time T1, wherein the first cell contains a first reference bit, and the first time T1 is the time when the first device sends the first reference bit in the first cell. Alternatively, the first cell may be referred to as a delayed request cell.

S302: the second device receives the first cell from the first device and determines a second time T2, the second time T2 being the time at which the second device receives the first reference bit in the first cell.

S303: the second device sends a second cell to the first device, and determines a third time T3, where 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 T2, and the third time T3 is a time when the second device sends the second reference bit in the second cell. Alternatively, the second cell may be referred to as a delayed response cell.

S304: the first device receives the second cell from the second device and determines a fourth time T4, wherein the fourth time T4 is a time when the second reference bit in the second cell is received by the first device.

S305: the second device sends a third cell to the first device, where the third cell 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 cell from the second device. The third cell may be referred to as a following cell of the delayed response cell, or a following 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 1588 protocol, which is not described herein.

In the present application, since the first device and the second device typically encode the cells when transmitting the corresponding cells, the cells are physically encoded, for example, by a physical encoding sublayer (physical coding sublayer, PCS). The first device and the second device can therefore take as the moment of transmitting the reference bit, i.e. the moment of transmitting the cell, the moment of encoding the reference bit in the cell that it needs to transmit.

However, when the first device and the second device receive the corresponding cells, the first device and the second device actually receive the encoded cells, so that the first device and the second device cannot determine the specific position of the reference bit in the encoded cells, and thus cannot determine the moment of receiving the reference bit. In the embodiment of the present application, in the process of receiving the encoded cell, the first device and the second device may record corresponding time for each clock cycle, after receiving and decoding the cell, determine the clock cycle in which the reference bit in the cell is located, and finally may use the recorded time corresponding to the clock cycle as the time of receiving the cell.

Based on the above description, in step S302 of the present embodiment, the second device may determine the second time T2 by:

the second device stores the corresponding time of each clock period in the process of receiving the first cell;

after receiving the first cell, the second device determines a target clock period in which the first reference bit in the first cell is received, and then determines a time corresponding to the target clock period as the second time T2.

Also, in step S304 of the present embodiment, the first device may determine the fourth time T4 by:

the first device stores the corresponding time of each clock period in the process of receiving the second cell;

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

In addition, it should be further noted that, in the embodiment of the present application, in order to ensure the accuracy of the first device when performing time synchronization, the first device and the second device need to negotiate in advance or specify, by a protocol, a selection rule of a reference bit in a cell used for time synchronization, that is, the first reference bit in the first cell and the second reference bit in the second cell are determined by using the same rule, and may have the same location or the same function in the cell in which each of the first device and the second device is located.

Illustratively, the first reference bit and the second reference bit may be, but are not limited to, the following:

Form one: the first reference bit is a most significant bit (most significant bit, MSB) in the first cell and the second reference bit is an MSB in the second cell.

Form two: the first reference bit is a least significant bit (LEAST SIGNIFICANT bits, LSB) in the first cell and the second reference bit is a LSB in the second cell.

Form three: the first reference bit is an nth bit in the first cell, and the second reference bit is an nth bit in the second cell, where N is an integer greater than or equal to 1 and less than or equal to N, where N is less than or equal to a total amount of bits contained in the first cell and less than or equal to a total amount of bits contained in the second cell.

Form four: 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 timing of executing the above-described time synchronization procedure is not limited in the embodiments of the present application. Optionally, the first device may initiate the time synchronization procedure when performing service transmission with the second device for the first time, or the first device may periodically perform the time synchronization procedure, or the first device may perform the time synchronization procedure after receiving a time synchronization instruction, or the first device may perform the time synchronization procedure at regular time. In addition, the embodiment of the present application also does not limit the type of the related cells in the time synchronization process, and the first cell, the second cell, and the third cell may be control cells.

The embodiment of the application provides a time synchronization method, in which the first equipment and the second equipment can realize the time synchronization of 1588 protocol through cell interaction. Thus, the method can achieve accurate time synchronization between communication devices supporting cell transmission. In addition, any communication system supporting cell transmission can realize time synchronization of 1588 protocol based on cell mode by the method, thereby being capable of replacing the traditional method of carrying 1588 protocol based on Ethernet mode, being convenient for deployment of 1588 system.

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, the embodiment of the application further provides a communication device. The individual units/modules in the communication device are divided in terms of implementing the logical functions 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 processing unit (cell processor), a PCS, and a physical interface. The functions of the respective modules are described in detail below.

The time processing unit is used for recording and storing the time stamp of the communication equipment and performing time synchronization according to the stored time stamp information.

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

When the communication device is a delay requester, the time processing unit may record a time T1 when the communication device transmits a reference bit in a delay request cell to a delay responder, a time T4 when the communication device receives a reference bit in a delay response cell, a time T2 when the cell processing unit receives a reference bit in a delay request cell from a delay responder acquired from a delay response cell, and a time T3 when the cell processing unit transmits a reference bit in a delay response cell from a delay responder acquired from a follow-up cell of the delay response cell. The cell processing unit may perform time synchronization according to the stored 4 times and in a manner in the time synchronization principle of the 1588 protocol.

The cell processing unit is configured to process related cells for service transmission of the communication device, and may also process cells related to time synchronization. As shown in fig. 4, the cell processing unit may be divided into a transmission (Tx) unit and a reception (Rx) unit according to different functions of a transmission (Tx) direction and a reception (Rx) direction. The sending unit is mainly used for generating cells, sending the cells to the PCS for coding, and finally sending the cells out through a physical interface. The sending unit is mainly used for receiving the cell obtained by PCS decoding and executing related operation according to the type of the cell and the data in the cell.

The PCS is used for carrying out physical coding and physical decoding processing on the cells. As shown in fig. 4, the cell processing unit may be divided into an encoding unit and a decoding unit according to different functions of Tx direction and Rx. The coding unit is configured to perform physical coding processing on a cell to be sent, and send the cell after physical coding to other communication devices through a physical interface. The decoding unit is used for performing physical decoding processing on the cells after the physical coding received by the physical interface to obtain cells, and sending the cells after the physical decoding to the cell processing unit for further processing.

The physical interface may be connected to other communication devices by a cable for communication interaction with other communication devices by receiving and transmitting cells. Alternatively, the physical interface may be a serial interface (serdes). As shown in fig. 4, the physical interfaces may be divided into Tx physical interfaces and Rx physical interfaces according to different functions of Tx direction and Rx. The Tx physical interface is configured to send the physically encoded information element to other communication devices. The Rx physical interface is configured to receive the physically encoded cells from the other communication device.

Based on the time synchronization method shown in fig. 3 and the logic function structure of the communication device shown in fig. 4, the embodiment of the application further provides a time synchronization example. Among them, for convenience of distinction and description, the present example refers to a delayed requester as "communication device a" and a delayed responder as "communication device B". Since the communication device a and the communication device B have the same units/modules, in order to distinguish the units/modules, the present example adds a after the names of the respective units/modules attributed to the communication device a, and adds B after the names of the respective units/modules attributed to the communication device B. The flow of this time synchronization example is described below with reference to fig. 5:

(1): in the communication apparatus a, the transmitting unit a generates a delay request cell (Prequest-cell) (abbreviated as Preq-cell in the figure). The transmitting unit a then transmits the delay request cell to the encoding unit a in the PCS a.

(2): The coding unit A performs physical coding on the received delay request cell and sends the delay request cell after physical coding to the Tx physical interface A. And in the process of physically encoding the delay request cell by the encoding unit A, when the encoding unit A performs physical encoding on the MSB in the delay request cell, acquiring the current time T1 (the time when the communication equipment A transmits the delay request cell) and transmitting the current time to the time processing unit A of the communication equipment A. The time processing unit a saves this time T1.

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

(4): The Rx physical interface B in the communication device B sends the coded delay request cell to the decoding unit B in the PCS B after receiving it.

(5): And the decoding unit B records the corresponding moment of each clock period in the process of receiving the coded delay request cell. And the decoding unit B performs physical decoding on the received coded delay request cell to obtain the delay request cell, and then sends the delay request cell obtained by decoding at the corresponding time of a plurality of clock cycles recorded in the process of receiving the coded delay request cell 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, may be determined by an indication in the delay request cell, or may be determined according to a cell identifier, or may be determined according to a cell type), then identifies the MSB in the delay request cell, determines a target clock period in which the MSB is received, and finally determines a time T2 corresponding to the target clock period, and uses the time as a time when the communication device B receives the delay request cell. The receiving unit B sends the time T2 to the transmitting unit B, and notifies the transmitting unit B to perform a delay response.

(7): After receiving the notification from the receiving unit B, the transmitting unit B generates a delayed response cell (Presponse-cell) (abbreviated as Prsp-cell in the figure) including the received time T2. The transmitting unit B then transmits the delayed response cell to the coding unit B in the PCS B.

(8): The coding unit B performs physical coding on the received delayed response cell, and sends the delayed response cell after physical coding to the Tx physical interface B. And in the process of physically encoding the delay response cell by the encoding unit B, when the encoding unit B performs physical encoding on the MSB in the delay response cell, the current time T3 (the time when the communication equipment B transmits the delay response cell) is acquired and transmitted back to the transmitting unit B.

(9): The sending unit B generates a following cell (Presponse-low-up-cell) (abbreviated as Prfu-cell in the figure) containing the time T3 delayed response cell when receiving the time T3 returned by the encoding unit B. The transmitting unit B then transmits the following cell to the coding unit B in the PCS B.

(10): The coding unit B performs physical coding on the received following cell, and sends the coded following cell to the Tx physical interface B.

(11): The Tx physical interface B transmits the encoded delayed response cells and the encoded following cells, respectively, to the communication device a.

(12): The Rx physical interface a in the communication device a sends the coded delay response cell and the coded follow-up cell to the decoding unit a in the PCS a after receiving the coded delay response cell and the coded follow-up cell, respectively.

(13): And the decoding unit A records the corresponding moment of each clock period in the process of receiving the coded delay response information element. And the decoding unit A performs physical decoding on the received coded delay response cell to obtain the delay response cell, and then sends the delay response cell obtained by decoding at the corresponding time of a plurality of clock cycles recorded in the process of receiving the coded delay response cell to the receiving unit A in the cell processing unit A.

The decoding unit A receives the encoded following cell and then physically decodes the encoded following cell to obtain the following cell. The decoding unit a then transmits the decoded following cell to the receiving unit a.

(14): After receiving the time corresponding to the multiple clock cycles recorded by the decoding unit a and the time obtained by decoding, the receiving unit a determines that the received cell is a time delay response cell (for example, the time delay response cell can be determined by an indication in the time delay response cell or determined according to a cell identifier or a cell type), identifies the MSB in the time delay response cell, determines a target clock cycle in which the MSB is received, and finally determines a time T4 corresponding to the target clock cycle, and uses the time as a time when the communication device a receives the time delay 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 this time T4.

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

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

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

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

A time synchronization sequence number (sequence ID), a link number of a physical interface, an identification of the communication device a, an identification of the communication device B.

Similarly, the time processing unit a in the communication device a also stores the time group according to the flow identifier. I.e. all moments in the same set of moments are saved for the same flow identity.

Thus, after receiving the delay response cell and the following cell, the receiving unit a in the communication device a performs pairing verification, i.e. verifies whether the flow identifier in the received delay response cell and the following cell is the same as the flow identifier in the transmitted delay request cell. If not, the receiving unit A discards the delay response cell and the following cell; if the received signal is the same, the receiving unit A performs subsequent operations according to the delayed response cell and the following cell.

As can be seen from the transmission time of the following cells, the communication device a should finally determine the time T3, so the order of the time instants at which the communication device a maintains time synchronization is: T1-T2/T4-T3. Thus when the communication device a determines that any one of the time groups held for the same flow identification is invalid, the time group is discarded.

In addition, as can be seen from the detailed flow description of the above example, the example uses a mechanism of time stamping by a physical medium connection layer (physical medium attachment, PMA) in a communication device, and this mechanism can avoid time jitter caused by time stamping by a conventional PCS layer and a forward error correction (forward error correction, FEC) layer, so that the accuracy of time synchronization can be further improved.

Based on the same technical concept, the embodiment of the present application also provides a communication device, where the structure of the device is shown in fig. 6, and the device includes a communication unit 601 and a processing unit 602. The communication apparatus 600 may be applied to a communication device of the communication system shown in fig. 2, and may implement the time synchronization method provided in the above embodiment or example. In the embodiment of the present application, the communication apparatus 600 may be applied to a latency requestor (abbreviated as a first device) in a communication system or a latency responder (abbreviated as a second device) in a communication system.

The functions of the various units in the device 600 are described below.

The communication unit 601 is configured to receive and transmit cells. The communication unit 601 may implement the above-mentioned transceiving function through a physical interface (for example, serdes) and a PCS.

In one embodiment, when the communication apparatus 600 is applied to the first device, the functions of the respective units are as follows:

The processing unit 602 is configured to send a first cell to a second device through the communication unit 601, and determine a first time, where the first cell includes a first reference bit, and the first time is a time when the communication unit 601 sends the first reference bit in the first cell; receiving, by the communication unit 601, a second cell from the second device, where the second cell includes a first time bit field and a second reference bit, where the first time bit field is used to indicate a second time when the second device receives the first reference bit in the first cell; determining a third time instant, which is a time instant when the communication unit 601 receives a second reference bit in the second cell; receiving, by the communication unit 601, a third cell from the second device, where the third cell includes a second time bit field, and the second time bit field is used to instruct the second device to send the second reference bit in the second cell; and performing time synchronization with the second device according to the first time, the second time, the third time and the fourth time;

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

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 alternatively

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

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 is specifically configured to, when receiving, by the communication unit 601, the second cell from the second device and determining the third time point:

storing a time corresponding to each clock cycle in the process of receiving the second cell by the communication unit 601;

after the communication unit 601 receives the second cell, it determines a target clock period in which the second reference bit in the second cell is received, and determines a time corresponding to the target clock period as the third time.

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

In another embodiment, when the communication apparatus 600 is applied to the second device, the functions of the respective units are as follows:

A processing unit 602, configured to receive, by using the communication unit 601, a first cell from a first device, and determine a second time, where the first cell includes a first reference bit, and the second time is a time when the communication unit 601 receives the first reference bit in the first cell; transmitting, by the communication unit 601, a second cell to the first device, and determining a fourth time, where 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, and the fourth time is a time when the communication unit 601 transmits the second reference bit in the second cell; and transmitting a third cell to the first device through the communication unit 601, where the third cell includes a second time bit field, and the second time bit field is used to indicate the fourth time;

A communication unit 601 for receiving the first cell and transmitting the second cell and the third cell.

Optionally, the processing unit 602 is specifically configured to, when receiving, by the communication unit 601, the first cell from the first device and determining the second time instant:

storing a time corresponding to each clock cycle in the process of receiving the first cell by the communication unit 601;

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

It should be noted that, in the above embodiments of the present application, the division of the modules is merely schematic, and there may be another division manner in actual implementation, and in addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or may exist separately and physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

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

Based on the same technical concept, the embodiment of the present application also provides a communication device, which can be applied to the communication system shown in fig. 2, can implement the time synchronization method provided in the above embodiment or example, and has the function of the communication apparatus 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 interconnected.

Optionally, the communication interface 701, the processor 702 and the memory 703 are connected to each other via a bus 704. The bus 704 may be a peripheral component interconnect standard (PERIPHERAL COMPONENT INTERCONNECT, PCI) bus, or an extended industry standard architecture (extended industry standard architecture, EISA) bus, or the like. The buses may be classified as address buses, data buses, control buses, etc. For ease of illustration, only one thick line is shown in fig. 7, but not only one bus or one type of bus.

The communication interface 701 is configured to receive and send a cell, and implement communication interaction with other communication devices.

The processor 702 is configured to process cells, including generating, parsing, physical encoding, physical decoding, and time synchronizing.

In one embodiment, when the communication device 700 is applied to a latency requester (where the latency requester is abbreviated as a first device and the latency responder is abbreviated as a second device) of two communication devices that need time synchronization, the processor 702 is specifically configured to:

transmitting a first cell to a second device through the communication interface 701, and determining a first time, where the first cell includes a first reference bit, and the first time is a time when the first device transmits the first reference bit in the first cell; receiving a second cell from the second device through the communication interface 701, wherein the second cell includes a first time bit field and a second reference bit, and the first time bit field is used for indicating a second time point when the second device receives the first reference bit in the first cell; determining a third time instant, wherein the third time instant is a time instant when the first device receives a second reference bit in the second cell; receiving a third cell from the second device through the communication interface 701, wherein the third cell includes a second time bit field, and the second time bit field is used to instruct the second device to send the second reference bit in the second cell; and performing time synchronization with the second device according to the first time, the second time, the third time and the fourth time.

Optionally, the processor 702 is specifically configured to:

Storing the corresponding time of each clock period in the process of physically decoding the second cell;

After the second cell is physically decoded, determining a target clock period in which the second reference bit in the second cell is received, and determining a time corresponding to the target clock period as the third time.

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

Receiving a first cell from a first device through the communication interface 701, and determining a second time instant, wherein the first cell includes a first reference bit, and the second time instant is a time instant when a second device receives the first reference bit in the first cell; transmitting a second cell to the first device through the communication interface 701, and determining a fourth time, where 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, and the fourth time is a time when the second device transmits the second reference bit in the second cell; and transmitting a third cell to the first device through the communication interface 701, where the third cell 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:

storing a 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, determining a target clock period in which the first reference bit in the first cell is received, and determining a time corresponding to the target clock period as the second time.

It should be noted that, the functions of the processor 702 may be described in the time synchronization method provided in the above embodiments and examples, and the specific functional description of the communication device 600 in the embodiment shown in fig. 6 is not repeated here.

The memory 703 is used for storing program instructions, data, and the like. In particular, the program instructions may comprise program code comprising computer-operating instructions. The memory 703 may include random access memory (random access memory, RAM) and may also include 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 functions described above, thereby implementing the time synchronization method provided in the above embodiment.

It will be appreciated that the memory 703 in FIG. 7 of the present application can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. The nonvolatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable EPROM (EEPROM), or a flash Memory. The volatile memory may be random access memory (Random Access Memory, RAM) which acts as external cache memory. By way of example, and not limitation, 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 (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 memory bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

Based on the above embodiments, the present application also provides a computer program, which when run on a computer, causes the computer to perform the time synchronization method provided in the above embodiments.

Based on the above embodiments, the present application also provides a computer-readable storage medium having stored therein a computer program which, when executed by a computer, causes the computer to execute the time synchronization method provided in the above embodiments.

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

Based on the above embodiments, the embodiments of the present application further provide a chip, where the chip is configured to read a computer program stored in a memory, to implement the time synchronization method provided in the above embodiments.

Based on the above embodiments, the embodiments of the present application provide a chip system, which includes a processor for supporting a computer apparatus to implement the functions involved in the communication device in the above embodiments. In one possible design, the chip system further includes a memory for storing programs and data necessary for the computer device. The chip system can be composed of chips, and can also comprise chips and other discrete devices.

In summary, the embodiment of the application provides a time synchronization method and a device. In this scheme, the first device and the second device may implement time synchronization of the 1588 protocol through cell interaction. Thus, the method can achieve accurate time synchronization between communication devices supporting cell transmission. In addition, any communication system supporting cell transmission can realize time synchronization of 1588 protocol based on cell mode by the method, thereby being capable of replacing the traditional method of carrying 1588 protocol based on Ethernet mode, being convenient for deployment of 1588 system.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

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

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A method of time synchronization, comprising:

The method comprises the steps that first equipment sends a first cell to second equipment and determines first time, wherein the first cell contains a first reference bit, and the first time is the time when the first equipment sends the first reference bit in the first cell;

the first device receives a second cell from the second device, wherein the second cell comprises a first time bit field and a second reference bit, and the first time bit field is used for indicating a second moment when the second device receives the first reference bit in the first cell;

The first device determining a third time instant, the third time instant being a time instant when the second reference bit in the second cell is received by the first device;

The first device receives a third cell from the second device, wherein the third cell comprises a second time bit field, and the second time bit field is used for indicating a fourth moment when the second device sends 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.

2. The method of claim 1, wherein the first reference bit is a most significant bit MSB in the first cell and the second reference bit is an MSB in the second cell; or alternatively

3. The method of claim 1, wherein the first device receiving the second cell from the second device comprises:

the first device determining the third time, comprising:

After receiving the second cell, the first device determines a target clock period in which the second reference bit in the second cell is received, and determines a time corresponding to the target clock period as the third time.

4. A method as claimed in any one of claims 1 to 3, wherein said first cell is a delayed request cell, said second cell is a delayed response cell and said third cell is a following cell.

5. A method of time synchronization, comprising:

The second device receives a first cell from the first device and determines a second time, wherein the first cell comprises a first reference bit, and the second time is the time when the second device receives the first reference bit in the first cell;

The second device sends a second cell to the first device, and determines a fourth time, wherein the second cell comprises a first time bit field and a second reference bit, the first time bit field is used for indicating the second time, and the fourth time is the time when the second device sends the second reference bit in the second cell;

the second device sends a third cell to the first device, wherein the third cell includes a second time bit field, and the second time bit field is used for indicating the fourth time.

6. The method of claim 5, wherein the first reference bit is a most significant bit MSB in the first cell and the second reference bit is an MSB in the second cell; or alternatively

7. The method of claim 5, wherein the second device receiving the first cell from the first device comprises:

the second device determining the second time, comprising:

And after receiving the first cell, the second device determines a target clock period in which the first reference bit in the first cell is received, and determines a time corresponding to the target clock period as the second time.

8. A method according to any of claims 5-7, wherein the first cell is a delayed request cell, the second cell is a delayed response cell, and the third cell is a following cell.

9. A communication apparatus, the apparatus being applied to a first device, the apparatus comprising:

A communication unit for receiving and transmitting cells;

A processing unit, configured to send a first cell to a second device through the communication unit, and determine a first time, where the first cell includes a first reference bit, and the first time is a time when the communication unit sends the first reference bit in the first cell; receiving, by the communication unit, a second cell from the second device, the second cell including a first time bit field and a second reference bit, the first time bit field being used to indicate a second time instant when the second device receives the first reference bit in the first cell; determining a third time instant, wherein the third time instant is the time instant when the communication unit receives the second reference bit in the second cell; receiving, by the communication unit, a third cell from the second device, where the third cell includes a second time bit field, where the second time bit field is used to instruct the second device to send a fourth time instant of the second reference bit in the second cell; and performing time synchronization with the second device according to the first time, the second time, the third time and the fourth time.

10. The apparatus of claim 9, wherein the first reference bit is a most significant bit MSB in the first cell and the second reference bit is an MSB in the second cell; or alternatively

11. The apparatus according to claim 9, wherein the processing unit is configured to:

Storing a time corresponding to each clock cycle in the process of receiving the second cell by the communication unit;

After the communication unit receives the second cell, determining a target clock period in which the second reference bit in the second cell is received, and determining a time corresponding to the target clock period as the third time.

12. The apparatus according to any of claims 9-11, wherein the first cell is a delayed request cell, the second cell is a delayed response cell, and the third cell is a follow-up cell.

13. A communication apparatus, the apparatus being applied to a second device, the apparatus comprising:

A communication unit for receiving and transmitting cells;

A processing unit, configured to receive, by the communication unit, a first cell from a first device, and determine a second time, where the first cell includes a first reference bit, and the second time is a time when the communication unit receives the first reference bit in the first cell; transmitting a second cell to the first device through the communication unit, and determining a fourth time, wherein the second cell comprises a first time bit field and a second reference bit, the first time bit field is used for indicating the second time, and the fourth time is the time when the communication unit transmits the second reference bit in the second cell; and transmitting a third cell to the first device through the communication unit, wherein the third cell includes a second time bit field, and the second time bit field is used for indicating the fourth time.

14. The apparatus of claim 13, wherein the first reference bit is a most significant bit MSB in the first cell and the second reference bit is an MSB in the second cell; or alternatively

15. The apparatus according to claim 13, wherein the processing unit is specifically configured to:

Storing a time corresponding to each clock cycle in the process of receiving the first cell by the communication unit;

After the communication unit receives the first cell, determining a target clock period in which the first reference bit in the first cell is received, and determining a time corresponding to the target clock period as the second time.

16. The apparatus according to any of claims 13-15, wherein the first cell is a delayed request cell, the second cell is a delayed response cell, and the third cell is a follow-up cell.

17. A communication device, comprising:

a communication interface for receiving and transmitting cells;

A memory for storing program instructions and data;

A processor for invoking said program instructions and data stored in said memory and for performing the method of any of claims 1-8 via said communication interface.

18. A computer program which, when run on a computer, causes the computer to perform the method of any of claims 1-8.

19. A computer readable storage medium, characterized in that the computer readable storage medium has stored therein a computer program which, when executed by a computer, causes the computer to perform the method according to any of claims 1-8.

20. A chip for reading a computer program stored in a memory, performing the method of any of claims 1-8.