KR101313273B1 - Time stamping apparatus and method for network timing synchronization - Google Patents

Time stamping apparatus and method for network timing synchronization Download PDF

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Publication number
KR101313273B1
KR101313273B1 KR1020100036620A KR20100036620A KR101313273B1 KR 101313273 B1 KR101313273 B1 KR 101313273B1 KR 1020100036620 A KR1020100036620 A KR 1020100036620A KR 20100036620 A KR20100036620 A KR 20100036620A KR 101313273 B1 KR101313273 B1 KR 101313273B1
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South Korea
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time
synchronization
pulse signal
data
sync
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KR1020100036620A
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Korean (ko)
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KR20110007028A (en
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이승우
이범철
김승환
최우영
유태환
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한국전자통신연구원
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0685—Clock or time synchronisation in a node; Intranode synchronisation
    • H04J3/0697—Synchronisation in a packet node
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0644—External master-clock

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Electric Clocks (AREA)

Abstract

The present invention relates to a time stamping apparatus and method for network time synchronization. By generating a synchronization pulse signal synchronized with the local clock of the transmitter, the timing of the reception of the received data is measured to achieve precise network time synchronization.

Description

Time stamping apparatus and method for network timing synchronization

TECHNICAL FIELD The present invention relates to network time synchronization techniques, and more particularly to time stamping techniques for network time synchronization.

The present invention is derived from a study conducted as part of a general project of the Ministry of Knowledge Economy [Task Management No .: 2008-S-043-01, Task Name: Development of Scalable Microflow Processing Technology].

When the transmitting device that transmits data measures the time when data is transmitted using its local clock, and the receiving device that receives the data performs the time synchronization by measuring the time when the data is received using its local clock. Since the local clocks of the transmitter and the receiver are different from each other, an error occurs between the accurate reception time and the measured reception time.

If a measurement error occurs at the time of transmission or reception of data, an error occurs in the time offset and the propagation delay time, and as a result, the accuracy for network time synchronization is lowered. Therefore, the present inventors have studied a technique capable of precise network time synchronization by accurately measuring the transmission time and the reception time of data.

An object of the present invention is to precisely measure the time point at which data is transmitted and the time point at which data is received to achieve precise network time synchronization.

According to an aspect of the present invention for achieving the above object, a transmitting device records a time point at which data is transmitted using its local clock, and the receiving device synchronizes with a local clock of the transmitting device transmitting data from the received data. And generating and synchronizing the received synchronization data with the synchronization pulse signal synchronized with the local clock of the transmitter.

According to the present invention, the local clock of each of the transmitter and the receiver can accurately measure the transmission time and the reception time of the data, thereby achieving a useful network time synchronization.

1 is a schematic diagram of a time stamping apparatus for network time synchronization according to the present invention.
2 is a diagram illustrating an example of a network time synchronization process.
3 is a block diagram illustrating an embodiment of a time stamping apparatus for network time synchronization according to the present invention.
4 is a flowchart illustrating an embodiment of a time stamping method for network time synchronization according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The terms used throughout the specification of the present invention have been defined in consideration of the functions of the embodiments of the present invention and can be sufficiently modified according to the intentions and customs of the user or operator. It should be based on the contents of.

1 is a schematic diagram of a time stamping apparatus for network time synchronization according to the present invention. As shown in FIG. 1, the time stamping apparatus 100 for network time synchronization according to the present invention is mounted on each of the transmitter 10 and the receiver 20 and uses a local clock of each of the transmitter and the receiver. Accurate network time synchronization is achieved between the transmitting device 10 and the receiving device 20 by accurately measuring the transmission time and the reception time of the data.

2 is a diagram illustrating an example of a network time synchronization process. Referring to FIG. 2, a process of synchronizing network time between a transmitter and a receiver is described. The transmitter 10 periodically uses the local clock thereof to periodically generate a time stamp value t1 at the time of transmitting a sync message SYNC. It accurately measures 210 and periodically transmits the synchronization message SYNC including the time stamp value t1 at the time of transmission of the measured synchronization message SYNC.

Receiving device 20 that requires network time synchronization receives synchronization message SYNC including time stamp value t1 at the time of transmission of synchronization message SYNC periodically transmitted from transmitter 10, and The time stamp value t2 at the time of receiving the synchronization message SYNC is accurately measured using the clock multiplied by the local clock, and the time stamp value t1 at the time of transmission of the synchronization message SYNC and the time at the reception of the synchronization message SYNC. The stamp value t2 is stored.

In addition, the receiving device 20 transmits the time information request message REQ to the transmitting device 10, and accurately measures the time stamp value t3 at the time of transmitting the time information request message REQ using its local clock. Save it.

The transmitter 10 that has received the time information request message REQ transmitted from the receiver 20 is a clock multiplied by a local clock of the receiver 20 and is a time stamp value at the time of receiving the time information request message REQ. (t4) is accurately measured, and the time information response message (RESP) including the time stamp value t4 at the time point at which the measured time information request message (REQ) is received is transmitted.

The receiving device 20 that has received the time information response message RESP including the time stamp value t4 at the time of receiving the time information request message REQ from the transmitting device 10 is included in the time information response message RESP. A time stamp value t4 at the time point at which the received time information request message REQ is received.

As a result, the receiving device 20 receives the time stamp value t1 at the time of transmitting the sync message SYNC, the time stamp value t2 at the time of receiving the sync message SYNC, and the time stamp at the time of transmitting the time information request message REQ. Value (t3) and time stamp value (t4) at the time of receiving the time information request message (REQ) can be accurately known, and the time offset and propagation delay time can be accurately used to achieve accurate and accurate network time synchronization. have.

The propagation delay time is an index indicating the propagation delay amount on the network, and D = ((t2-t1) + (t4-t3)) / 2, and the time offset is a value for correcting the time deviation. )-(t4-t3)) / 2 When the time offset value is reflected in the time of the receiver 20, the time of the transmitter 10 is synchronized with the time of the network.

3 is a block diagram illustrating an embodiment of a time stamping apparatus for network time synchronization according to the present invention. As shown in FIG. 3, the time stamping apparatus 100 for network time synchronization according to the present embodiment includes a synchronization pulse signal generator 110 and a reception time measurement unit 120.

The synchronizing pulse signal generating unit 110 generates a synchronizing pulse signal synchronized with the local clock of the transmitting apparatus which transmitted the data from the received data. The received data includes a time stamp value at the time of data transmission measured using the local clock of the transmitter.

At this time, the sync pulse signal generator 110 may recognize a certain pattern of the received data and generate a sync pulse signal synchronized with the local clock of the transmitter. For example, the sync pulse signal generator 110 may include a clock restorer 111 and a sync pulse restorer 112.

The clock recovery unit 111 recovers a clock having the same clock frequency as that of the local clock of the transmitter from the received data. The sync pulse recovery unit 112 recognizes a predetermined pattern of the received data and generates a sync pulse signal synchronized with the clock restored by the clock restore unit 111.

The reception time measurement unit 120 measures a time stamp value at the time when the reception data is received using the synchronization pulse signal generated by the synchronization pulse signal generation unit 110. The sync pulse signal generated by the sync pulse signal generator 110 is a signal synchronized with the local clock of the restored transmitter, and has the same clock frequency as the local clock of the transmitter.

In other words, the receiver receives a time stamp value at the time of data transmission measured using the local clock of the transmitter included in the received data, and a time stamp value at the time of data reception measured using a clock multiplied by the local clock of the restored transmitter. Therefore, the measurement error caused when the time stamp value at the time of data transmission and the time stamp value at the time of data reception are measured using the local clocks of the transmitter and the receiver, respectively.

Accordingly, since the time stamp value at the time of data transmission and the time stamp value at the time of data reception can be measured using the local clock of the transmitter, precise network time synchronization at the time of network time synchronization is possible through the process of FIG.

Meanwhile, according to an additional aspect of the present invention, the sync pulse signal generator 110 may be implemented in the physical layer of the receiver, and the reception time measurement unit 120 may be implemented in the upper layer of the physical layer of the receiver.

For example, the physical layer of Ethernet consists of a PCS block, a PMA block, and a PMD block, and in the case of 10G Ethernet, the PCS block includes a 64bit / 66bit or 8bit / 10bit encoder and decoder. The PCS block is a block operating in the local clock region of the recovered transmission apparatus. In the case of a 64-bit / 66-bit encoder, 64-bit block data is coded into a 66-bit block.

The first two bits of the 66 bits indicate whether it is a data block or a control block, and the remaining 64 bits (or 8 bytes) are called a payload. The start character transmitted through XGMII, the interface standard between the physical layer and the MAC layer (L2 layer) of 10G Ethernet, is included in the control block and transmitted, and is located in the first or fifth byte of the transmitted eight bytes. The sync pulse signal generator 110 may recognize a start character to generate a start point of the frame, that is, a sync pulse signal in the PCS block.

In other words, in this embodiment, the synchronous pulse signal generating unit 110 for generating a synchronous pulse signal synchronized with the local clock of the transmitting apparatus that has transmitted the data from the received data is implemented in the physical layer of the receiving apparatus, The reception time measurement unit 120 measuring a time stamp value at the time of receiving the received data is implemented in an upper layer of the physical layer to achieve more accurate network time synchronization.

Meanwhile, according to an additional aspect of the present invention, the time stamping apparatus 100 for network time synchronization may further include a synchronization message detector 130 and a time stamp selector 140.

The synchronization message detector 130 detects whether the received data is a synchronization message. At this time, the sync message detector 130 may analyze the header of the received data or the specific format of the received data to detect whether the received data is a sync message or general data.

For example, in the case of the IEEE 1588 standard, a UDP port number is identified as a synchronous message or general data such as 319 or 320 in the UDP header field. It can be detected whether or not it is normal data.

That is, the general apparatus receives not only the synchronization message but also general data, and only the synchronization message is required for network time synchronization, and thus the synchronization device detects the synchronization message through the synchronization message detector 130.

The time stamp selector 140 selects a time stamp value corresponding to the sync message detected by the sync message detector 130 among the time stamp values measured by the reception time measurement unit 120.

The reception apparatus stores the time stamp value at the time of continuous data reception through the reception time measurement unit 120 whenever a general data frame as well as a synchronization message is received.

Since only the time stamp value at the time of reception of the synchronization message is needed for network time synchronization, the synchronization message detection unit 130 is detected among the time stamp values measured by the reception time measurement unit 120 through the time stamp selection unit 140. Select the time stamp value corresponding to the sync message.

Meanwhile, the time stamp selector 140 transmits the time stamp value corresponding to the synchronization message to the upper layer to perform precise network time synchronization through the process shown in FIG. 2 in the upper layer.

Referring to FIG. 4, a process of measuring a time stamp value at the time of data reception for network time synchronization of the time stamping apparatus for network time synchronization as described above will be described. 4 is a flowchart illustrating an embodiment of a time stamping method for network time synchronization according to the present invention.

When the transmitting apparatus measures the time stamp value at the time of transmitting data using its local clock for network time synchronization, and transmits the time stamp value at the time of transmitting the data in the transmission data, the data receiving step 410 ), The receiver receives the data.

Next, in the synchronizing pulse signal generating step 420, the receiving apparatus generates a synchronizing pulse signal synchronized with the local clock of the transmitting apparatus which transmitted the data from the data received by the data receiving step 410. At this time, in the sync pulse signal generation step 420, the receiver may recognize a certain pattern of the received data to generate a sync pulse signal synchronized with the local clock of the transmitter.

For example, the synchronous pulse signal generation step 420 may include a clock recovery step 421 and a synchronous pulse recovery step 422. In the clock recovery step 421, a clock having the same clock frequency as the local clock of the transmitting device is recovered from the received data. In the synchronous pulse recovery step 422, a predetermined pattern of the received data is recognized and the clock recovery step 421 is performed. Generate a sync pulse signal synchronized with the recovered clock.

Next, in the reception time measurement step 430, the reception apparatus measures the time stamp value at the time when the corresponding reception data is received using the synchronization pulse signal generated by the synchronization pulse signal generation step 420.

In this way, the time stamp value at the time of data transmission and the time stamp value at the time of data reception can be measured using the local clock of the transmission apparatus, thereby enabling accurate network time synchronization at the time of network time synchronization.

According to an additional aspect, the time stamping method for network time synchronization may further include a synchronization message detection step 440 and a time stamp selection step 450.

In the sync message detecting step 440, the receiving apparatus detects whether the received data whose time stamp value is measured by the receiving time measurement step 430 is a sync message, and in the time stamp selection step 450, the sync message. When the reception data is detected as the synchronization message by the detection step 440, the reception apparatus selects a time stamp value corresponding to the detected synchronization message from among the time stamp values measured by the reception time measurement step 430. .

In this case, the synchronization message detection step 440 may be implemented to detect whether the received data is a synchronization message or general data by analyzing the header of the received data or a specific format of the received data.

That is, the general apparatus receives not only the synchronization message but also general data, and only the synchronization message is required for network time synchronization, and thus, the synchronization message is detected in the synchronization message detection step 440.

In the time stamp selection step 450, a time stamp value corresponding to the synchronization message detected by the synchronization message detection step 440 is selected from the time stamp values measured by the reception time measurement step 430.

The reception apparatus stores the time stamp value at the time of continuous data reception through the reception time measurement step 430 whenever receiving the general data frame as well as the synchronization message.

Since only the time stamp value at the time of reception of the synchronization message is required for network time synchronization, the synchronization message detection step 440 of the time stamp values measured by the reception time measurement step 430 in the time stamp selection step 450 is detected. Select the time stamp value corresponding to the sync message.

When the time stamp value corresponding to the synchronization message is selected by the time stamp selection step 450, the reception apparatus selects a time stamp value and a time stamp value at the time of data transmission measured using the local clock of the transmission apparatus included in the received data. Precise network time synchronization is performed through the procedure described with reference to FIGS. 2 and 3 using the time stamp value at the time of receiving the synchronization message selected by step 450.

As described above, the present invention can accurately measure the transmission time and the reception time of data using local clocks of the transmitter and the receiver, so that accurate network time synchronization can be achieved. Can be achieved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. .

The present invention is industrially available in the network time synchronization art and its application art.

10: transmitting device 20: receiving device
100: time stamping device 110: sync pulse signal generation unit
111: clock recovery unit 112: synchronous pulse recovery unit
120: reception time measurement unit 130: synchronization message detection unit
140: time stamp selector

Claims (13)

In the time stamping apparatus for network time synchronization implemented in the receiving apparatus,
A synchronizing pulse signal generating unit for generating from the received data a synchronizing pulse signal synchronized with the local clock of the transmitting apparatus which has transmitted the data;
A reception time measurement unit for measuring a time stamp value at the time when the reception data is received using the synchronization pulse signal generated by the synchronization pulse signal generation unit;
Time stamping apparatus for network time synchronization comprising a. The method of claim 1,
The sync pulse signal generation unit:
Time stamping device for network time synchronization, characterized in that implemented in the physical layer of the receiving device. The method of claim 1,
The reception time measurement unit:
Time stamping device for network time synchronization, characterized in that implemented in the upper layer of the physical layer of the receiving device. The method of claim 1,
The sync pulse signal generation unit:
A time stamping device for network time synchronization, characterized by generating a sync pulse signal synchronized with a local clock of a transmitter by recognizing a predetermined pattern of received data. 5. The method of claim 4,
The sync pulse signal generation unit:
A clock recovery unit for recovering a clock having the same clock frequency as that of the local clock of the transmitter from the received data;
A synchronization pulse recovery unit for recognizing a predetermined pattern of received data and generating a synchronization pulse synchronized with a clock restored by the clock recovery unit;
And a time stamping device for network time synchronization. The method of claim 1,
The time stamping device for network time synchronization:
A sync message detector for detecting whether the received data is a sync message;
A time stamp selector which selects a time stamp value corresponding to a sync message detected by the sync message detector among time stamp values measured by the reception time measurer;
A time stamping device for network time synchronization, further comprising. The method according to claim 6,
The sync message detection unit:
And analyzing the header of the received data or a specific format of the received data to detect whether the received data is a synchronous message or general data. The method according to claim 6,
The time stamp selector includes:
And a time stamp value corresponding to the synchronization message to a higher layer. delete delete delete delete delete
KR1020100036620A 2009-07-15 2010-04-20 Time stamping apparatus and method for network timing synchronization KR101313273B1 (en)

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KR20090064565 2009-07-15

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070172236A1 (en) * 2005-12-20 2007-07-26 Takumi Nomura Optical switching device, optical access network, optical switching method, program, and recording medium
US20110274141A1 (en) * 2007-10-25 2011-11-10 Nokia Corporation Method of and apparatus for synchronization

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070172236A1 (en) * 2005-12-20 2007-07-26 Takumi Nomura Optical switching device, optical access network, optical switching method, program, and recording medium
US20110274141A1 (en) * 2007-10-25 2011-11-10 Nokia Corporation Method of and apparatus for synchronization

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