JP5235716B2 - Synchronous transfer device and synchronous control system - Google Patents

Description

  The present invention relates to a synchronous transfer device and a synchronous control system.

Patent Document 1 describes a network synchronization system that extracts a network synchronization clock signal from line data output from an electronic exchange and supplies the extracted network synchronization clock signal to a transmission apparatus.
JP 2003-318871 A

  However, in the above technique, when the transmission device that receives data is a network relay device that transmits data using an internal clock, the relay destination device processes the data at the timing of the internal clock of the network relay device. Processing cannot be performed synchronously with the exchange. As described above, in the related art, when a network relay device is provided on a data communication path, devices using the communication path cannot perform processing synchronously.

  In order to solve the above-mentioned problem, in the first embodiment of the present invention, a synchronous transfer device for controlling the synchronization of a network relay device of an asynchronous communication network, which extracts a clock from data input to the network relay device A clock extraction unit; a synchronization control unit that synchronizes data output from the network relay device with a clock timing extracted by the clock extraction unit; and a data transmission unit that transmits data synchronized by the synchronization control unit.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows an example of the configuration of an asynchronous communication network 10 according to the embodiment. The asynchronous communication network 10 is a communication network such as an IP network, and interconnects a plurality of base stations 12. The asynchronous communication network 10 includes a plurality of network relay devices 14. The network relay device 14 is a device such as a gateway, a router, or a hub that relays data in the asynchronous communication network 10.

  The network relay device 14 operates at the timing of the clock of data received from another device. The network relay device 14 has a built-in clock oscillator, and transmits data to other devices in synchronization with the timing of the clock generated by the clock oscillator.

  In the asynchronous communication network 10, even if a plurality of network relay devices 14 are not synchronized, an asynchronous application that does not place importance on synchronization accuracy can process data normally. On the other hand, when processing a synchronization application that places importance on synchronization accuracy, such as an application that synchronizes the time between the plurality of base stations 12, it is necessary to synchronize the plurality of network relay devices 14 with high accuracy. However, since the network relay device 14 used in the asynchronous communication network 10 has a low accuracy of the built-in clock oscillator, it is not easy to synchronize a plurality of network relay devices 14.

For example, in FIG. 1, base station 12A, the clock outputs data _{f 0.} Network relay device 14A is a clock to input data of f _0, and outputs the data using the clock f ₁ the internal clock oscillator is generated. Similarly, the network relay device 14B-D, and outputs data using the clock f ₂ -f ₄ the internal clock oscillator is generated. Thus, since the clocks of the data output from the plurality of network relay devices 14 are different from each other, it is not easy to synchronize the plurality of network relay devices 14.

  Therefore, the asynchronous communication network 10 of the present embodiment further includes a synchronization control system that controls the synchronization of the plurality of network relay devices 14. The synchronous control system includes a plurality of synchronous transfer devices 100. Specifically, in the asynchronous communication network 10, one synchronous transfer device 100 is provided for each of the plurality of network relay devices 14.

  The synchronous transfer device 100 controls the synchronization of the network relay device 14. Specifically, the synchronous transfer device 100 synchronizes the clock timing of the data output from the network relay device 14 with the clock timing of the data input to the network relay device 14. In the synchronous control system, each of the plurality of synchronous transfer devices 100 controls the clock timing of the data output from the network relay device 14, so that the clock timing of the plurality of data output from the plurality of network relay devices 14 is set. Synchronize. As a result, the synchronization control system synchronizes the plurality of network relay devices 14.

For example, as shown in FIG. 1, the synchronous transfer device 100A uses the data with the clock f ₁ output from the network relay device 14A and the timing of the clock f ₀ as the clock of the data input to the network relay device 14A. Synchronize with. Similarly, synchronous transfer device 100B-D may, to synchronize the data output from the network relay device 14B-D to the timing of the clock _{f 0.} Thereby, a synchronous control system synchronizes network relay apparatus 14A-D.

  As described above, according to the synchronization control system of the present embodiment, even when the accuracy of the clock oscillator of the network relay device 14 is low, the clock timings of the plurality of data output from the plurality of network relay devices 14 are synchronized. By doing so, the plurality of network relay devices 14 can be synchronized with high accuracy. In addition, since a synchronization control system can be constructed simply by connecting the synchronous transfer apparatus 100 to an existing network relay device 14, a synchronization control system for synchronizing a plurality of network relay devices 14 can be realized in a short period of time and at a low cost. Can be built with.

  Note that the synchronization control system of the present embodiment further includes a connection control device 110 that controls connections between the plurality of network relay devices 14. The connection control device 110 performs various control processes according to the synchronization state of the plurality of synchronous transfer devices 100. For example, the connection control device 110 controls the data communication path according to the synchronization state of the plurality of synchronous transfer devices 100. The connection control apparatus 110 may control the data communication path so as to use a communication path in which the plurality of synchronous transfer apparatuses 100 are synchronized. Further, the connection control device 110 may control the data communication path so as to use a communication path with higher synchronization accuracy of the plurality of synchronous transfer apparatuses 100.

  As described above, according to the synchronization control system of the present embodiment, it is possible to easily grasp the synchronization state of the network relay device 14 by further including the connection control device 110. In addition, since communication paths and the like in the asynchronous communication network 10 can be automatically controlled according to the synchronization state of the plurality of synchronous transfer devices 100, applications using the asynchronous communication network 10 continue to have higher synchronization accuracy. Can be obtained.

  FIG. 2 shows the concept of data processing timing in the asynchronous communication network 10. Here, an example in which data is transmitted from the base station 12A to the base station 12B via the network relay device 14 will be described.

  The base station 12A transmits the data 202 and the data 204 in synchronization with the internal clock 206 of the base station 12A. The network relay device 14 transmits the data 202 and data 204 received from the base station 12 </ b> A in synchronization with the internal clock 210 of the network relay device 14.

  When the base station 12B directly receives the data 202 and data 204 output from the network relay device 14, the data differs in timing from the internal clock 210 of the network relay device 14, which has a frequency different from that of the internal clock 206 of the base station 12A. 202 and data 204 are processed. That is, the base station 12B cannot perform processing with a clock having the same frequency as the base station 12A, and cannot perform processing in synchronization with the base station 12A.

  Therefore, the base station 12B receives the data 202 and the data 204 from the network relay device 14 via the synchronous transfer device 100 that controls the synchronization of the network relay device 14. The synchronous transfer device 100 receives the data 202 and the data 204 from the network relay device 14. Then, the synchronous transfer apparatus 100 transmits the data 202 and the data 204 with the timing synchronized with the internal clock 206 of the base station 12A.

  The base station 12B receives the data 202 and the data 204 output from the synchronous transfer device 100, and processes the data 202 and the data 204 at the timing of the internal clock 206 of the base station 12A. That is, since the base station 12B can perform processing with a clock having the same frequency as the base station 12A, it can perform processing in synchronization with the base station 12A.

  Here, in the base station 12B, the arrival time of data due to the intermediate network and the relay device varies with respect to the base station 12A. However, since the clock used for the processing of the base station 12B is synchronized with the clock used for the processing of the base station 12A, the data timing can be easily reproduced on the basis of this. For example, in the example shown in FIG. 2, the base station 12A adds the additional information at timings T1 and T2 with T0 as a reference, and transmits data 202 and data 204. The base station 12B receives and processes the data 202 and the data 204 at the timings T1 ′ and T2 ′ delayed by the sum of the network transmission delay and the network repeater delay. Although the interval between these timings is different from that at the time of transmission, the base station 12B determines the frame 220 in FIG. 2 based on the clock synchronized with the base station 12A and the additional information added to the received data 202 and data 204. The timings T0, T1, and T2 are reproduced as shown in the figure, and the data and output timing of the transmission source can be easily reproduced using the reproduced timings T0, T1, and T2.

  FIG. 3 shows an example of functional configurations of the base station 12, the network relay device 14, and the synchronous transfer device 100.

  The base station 12 includes a buffer 300, an internal clock generation unit 302, and a data transmission unit 304. The buffer 300 stores data to be transmitted. The internal clock generator 302 generates an internal clock using a clock oscillator. The data transmission unit 304 transmits the data stored in the buffer 300 in synchronization with the timing of the internal clock generated by the internal clock generation unit 302.

  The network relay device 14 includes a data input unit 310, a PLL circuit unit 312, a buffer 314, an internal clock generation unit 316, and a data output unit 318. The data input unit 310 inputs data transmitted from the base station 12 and transmitted by the synchronous transfer device 100. The PLL circuit unit 312 synchronizes the data input by the data input unit 310 with the clock timing extracted from the data by the PLL circuit. The buffer 314 stores the data input by the data input unit 310. The internal clock generator 316 generates an internal clock using a clock oscillator. The data output unit 318 outputs the data stored in the buffer 314 to the synchronous transfer device 100 in synchronization with the timing of the internal clock generated by the internal clock generation unit 316.

  The synchronous transfer device 100 includes a data receiving unit 320, a clock extracting unit 322, a data transmitting unit 324, a data input unit 326, a PLL circuit unit 328, a buffer 330, a synchronization control unit 332, and a data transmitting unit 334.

  The data receiving unit 320 receives data input to the network relay device 14. The clock extraction unit 322 extracts a clock from data input to the network relay device 14. Specifically, the clock extraction unit extracts a clock from the data received by the data reception unit 320. The data transmission unit 324 inputs the data received by the data reception unit to the network relay device 14.

  The data input unit 326 inputs data output from the data output unit 318 of the network relay device 14. The PLL circuit unit 328 uses the PLL circuit to synchronize the data input by the data input unit 326 with the clock timing extracted from the data. The buffer 330 stores the data input by the data input unit 326.

  The synchronization control unit 332 uses the PLL circuit to synchronize the data output from the network relay device 14, that is, the data stored in the buffer 330, with the clock timing extracted by the clock extraction unit 322. The data transmission unit 334 transmits the data synchronized by the synchronization control unit 332. Specifically, the data transmission unit 334 transmits the data to a subsequent device that the network relay device 14 should originally transmit.

  The synchronous transfer device 100 further includes a high-accuracy clock generation unit 340, a high-accuracy clock acquisition unit 342, a synchronization state determination unit 344, a synchronization state information addition unit 346, and a synchronization state information notification unit 348.

  The high-accuracy clock generation unit 340 generates a high-accuracy clock with higher accuracy than the internal clock of the network relay device 14 with a high-accuracy clock oscillator such as OCXO (Oven Controlled Xtal Oscillator) as necessary. For example, in a mobile communication network of 3G or later, it is preferable to use a high-accuracy clock oscillator having a clock error of 0.05 ppm (parts per million) or less.

  The high-accuracy clock acquisition unit 342 acquires a high-accuracy clock that is more accurate than the internal clock of the network relay device 14. For example, the high accuracy clock acquisition unit 342 acquires the high accuracy clock generated by the high accuracy clock generation unit 340. The high-accuracy clock acquisition unit 342 may acquire a high-accuracy clock from an external device such as the base station 12 that includes a high-accuracy clock oscillator.

  The synchronization state determination unit 344 determines the synchronization state of the synchronous transfer device 100 by evaluating the clock extracted by the clock extraction unit 322 using the high-accuracy clock acquired by the high-accuracy clock acquisition unit 342. For example, the synchronization state determination unit 344 periodically observes the accuracy of the clock extracted by the clock extraction unit 322 using a high-precision clock, and the synchronous transfer device 100 synchronizes based on the observed clock error. Determine whether or not.

  In this case, when the observed clock error is larger than a predetermined reference value, the synchronization state determination unit 344 determines that the synchronous transfer device 100 is not synchronized, and determines a predetermined reference value. If smaller than that, it may be determined that the synchronous transfer device 100 is synchronized. For example, the synchronization state determination unit 344 may determine that the synchronous transfer device 100 is not synchronized when the observed clock error is greater than a predetermined reference value of 0.1 ppm.

  The synchronization state determination unit 344 may determine the synchronization level of the synchronous transfer device 100 based on the observed clock error. The synchronization level may be stepwise such as high / medium / low, or may be numerical such as a clock error expressed in ppm.

  The synchronization state information adding unit 346 adds synchronization state information indicating the synchronization state of the synchronous transfer device 100 to the data output from the network relay device 14, that is, the data stored in the buffer 330. For example, the synchronization state information giving unit 346 gives the simultaneous state information to the empty area of the data packet stored in the buffer 330. In this case, it is preferable that the synchronization state information providing unit 346 provides the synchronization state information to a free area that does not affect communication.

  The synchronization status information notification unit 348 notifies the connection control device 110 of synchronization status information indicating the synchronization status of the synchronous transfer device 100. For example, the synchronization status information notification unit 348 periodically notifies the connection control device 110 of the synchronization status information. The synchronization state information provided by the synchronization state information adding unit 346 and the synchronization state information notified by the synchronization state information notification unit 348 may indicate whether or not the synchronization processing by the synchronization control unit 332 has been successful. It may indicate the determination result by the state determination unit 344, or may simply indicate that the synchronous transfer device 100 is operating.

  FIG. 4 shows an example of a functional configuration of the connection control device 110. The connection control device 110 includes a synchronization state information acquisition unit 402, a synchronization state information storage unit 404, and a path control unit 406.

  The synchronization state information acquisition unit 402 acquires synchronization state information indicating the synchronization state of the synchronous transfer device 100 from each of the multiple synchronous transfer devices 100. The synchronization state information storage unit 404 stores the synchronization state information acquired by the synchronization state information acquisition unit 402. For example, the synchronization state information storage unit 404 uses the acquired synchronization state information every time the synchronization state information acquisition unit 402 acquires the synchronization state information periodically notified from each of the plurality of synchronous transfer devices 100. The synchronization status information stored in the synchronization status information storage unit 404 is periodically updated.

  The synchronization state information storage unit 404 stores, for example, information indicating whether or not the synchronous transfer device 100 is synchronized as synchronization state information. The synchronization state information storage unit 404 may store information indicating the synchronization level of the synchronous transfer device 100 as synchronization state information. In addition, the synchronization state information storage unit 404 may store information indicating a synchronization relationship with another synchronized transfer apparatus 100 as synchronization state information. Further, the synchronization state information storage unit 404 may store information indicating whether or not the synchronous transfer device 100 is operating as synchronization state information.

  The path control unit 406 controls the connection between the plurality of network relay devices 14 based on the synchronization state information of the plurality of synchronous transfer devices 100 stored in the synchronization state information storage unit 404, thereby performing asynchronous communication. A data communication path in the network 10 is controlled. For example, the path control unit 406 may synchronize the plurality of synchronous transfer apparatuses 100 when there are communication paths in which the plurality of synchronous transfer apparatuses 100 are synchronized and communication paths in which the plurality of synchronous transfer apparatuses 100 are not synchronized. The data communication path in the asynchronous communication network 10 is controlled so as to use the communication path.

  The path control unit 406 does not include the synchronous transfer apparatus 100 that is not operating when there is a communication path including the synchronous transfer apparatus 100 that is not operating and a communication path that does not include the synchronous transfer apparatus 100 that is not operating. The communication path of data in the asynchronous communication network 10 may be controlled so as to use the communication path. When there are a plurality of communication paths with which the plurality of synchronous transfer apparatuses 100 are synchronized, the path control unit 406 performs asynchronous communication so that the plurality of synchronous transfer apparatuses 100 use a communication path synchronized with higher accuracy. The data communication path in the network 10 may be controlled.

  FIG. 5 shows an example of the synchronization state information stored in the synchronization state information storage unit 404. In the synchronization status information storage unit 404, synchronization status information is stored in association with each of the plurality of synchronous transfer device IDs. The synchronization status information includes an item “operation status”, an item “synchronization status”, and an item “synchronization accuracy”.

  In the item “operation state”, “operation” indicating that the synchronous transfer device 100 is operating, or “non-operation” indicating that the synchronous transfer device 100 is not operating is set. The synchronization state information storage unit 404 may not store synchronization state information for the synchronous transfer device 100 that is not operating. In other words, the fact that the synchronization status information is stored may indicate that the synchronous transfer device 100 is operating.

  In the item “synchronized state”, “synchronous” indicating that the synchronous transfer device 100 is synchronized with the other synchronous transfer devices 100, or that the synchronous transfer device 100 is not synchronized with the other synchronous transfer devices 100. “Asynchronous” is set. In the item “synchronization accuracy”, the synchronization level of the synchronous transfer device 100 is set. In the example shown in FIG. 5, in the item “synchronization accuracy”, a clock error in ppm is set as the synchronization level.

  When the synchronization state information shown in FIG. 5 is stored in the synchronization state information storage unit 404, the path control unit 406 is the synchronized transfer device ID “1”, “2”, In addition, the data communication path may be controlled so that the communication path provided with the synchronous transfer device 100 of “3” is used preferentially. Further, the path control unit 406 gives higher priority to the communication path in which the synchronous transfer apparatuses 100 having the synchronous transfer apparatuses ID “1” and “2”, which are the synchronous transfer apparatuses 100 in synchronization, are provided. In addition, the data communication path may be controlled. Further, the path control unit 406 performs data transfer so that the communication path provided with the synchronous transfer apparatus 100 having the synchronous transfer apparatus ID “1”, which is the synchronous transfer apparatus 100 with higher synchronization accuracy, is used with higher priority. The communication path may be controlled.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 shows an example of the configuration of an asynchronous communication network 10 according to an embodiment. A concept of data processing timing in the asynchronous communication network 10 will be described. An example of a functional configuration of the base station 12, the network relay device 14, and the synchronous transfer device 100 is shown. An example of a functional structure of the connection control apparatus 110 is shown. An example of the synchronization status information stored in the synchronization status information storage unit 404 is shown.

10 asynchronous communication network, 12 base station, 14 network relay device, 100 synchronous transfer device, 110 connection control device, 202 data, 204 data, 206 internal clock, 210 internal clock, 300 buffer, 302 internal clock generator, 304 data transmission Unit, 310 data input unit, 312 PLL circuit unit, 314 buffer, 316 internal clock generation unit, 318 data output unit, 320 data reception unit, 322 clock extraction unit, 324 data transmission unit, 326 data input unit, 328 PLL circuit unit , 330 buffer, 332 synchronization control unit, 334 data transmission unit, 340 high accuracy clock generation unit, 342 high accuracy clock acquisition unit, 344 synchronization state determination unit, 346 synchronization state information addition unit, 348 synchronization state information notification unit, 402 synchronization Status information acquisition unit, 404 synchronization state information storage unit, 406 routing control unit

Claims (6)

A synchronous transfer device for controlling the synchronization of a network relay device of an asynchronous communication network,
A clock extraction unit that extracts a clock from data input to the network relay device;
A synchronization controller that synchronizes the data output from the network relay device with the timing of the clock;
A data transmission unit for transmitting data synchronized by the synchronization control unit ;
A synchronous transfer apparatus comprising: a synchronization state information adding unit that adds synchronization state information indicating a synchronization state of the synchronous transfer apparatus to data output from the network relay device.   A synchronous transfer device for controlling the synchronization of a network relay device of an asynchronous communication network,
  A clock extraction unit that extracts a clock from data input to the network relay device;
  A synchronization controller that synchronizes the data output from the network relay device with the timing of the clock;
  A data transmission unit for transmitting data synchronized by the synchronization control unit;
  A synchronization state information notifying unit for notifying a synchronization state information indicating a synchronization state of the synchronous transfer device to a connection control device that controls connection between the plurality of network relay devices;
A synchronous transfer device.   A synchronous transfer device for controlling the synchronization of a network relay device of an asynchronous communication network,
  A clock extraction unit that extracts a clock from data input to the network relay device;
  A synchronization controller that synchronizes the data output from the network relay device with the timing of the clock;
  A data transmission unit for transmitting data synchronized by the synchronization control unit;
  A high-accuracy clock acquisition unit that acquires a high-accuracy clock that is higher than the internal clock of the network relay device;
  A synchronization state determination unit that determines the synchronization state of the synchronous transfer device by evaluating the clock extracted by the clock extraction unit using the high-accuracy clock;
A synchronous transfer device. A data receiving unit for receiving data input to the network relay device;
A data transmission unit for inputting the data received by the data receiving unit to the network relay device;
The synchronous transfer device according to any one of claims 1 to 3, wherein the clock extraction unit extracts the clock from data received by the data reception unit. A synchronous transfer device according to any one of claims 1 to 4 ;
A connection control device for controlling connection between the plurality of network relay devices,
The connection control device includes:
A synchronization state information acquisition unit for acquiring synchronization state information indicating a synchronization state of the synchronous transfer device from each of the plurality of synchronous transfer devices;
A path control unit that controls a communication path of data in the asynchronous communication network by controlling connection between the plurality of network relay devices based on the synchronization state information of each of the plurality of synchronous transfer apparatuses. Synchronous control system.   A synchronous transfer device for controlling the synchronization of the network relay device of the asynchronous communication network;
  A connection control device for controlling connection between the plurality of network relay devices;
A synchronous control system comprising:
  The synchronous transfer device includes:
  A clock extraction unit that extracts a clock from data input to the network relay device;
  A synchronization controller that synchronizes the data output from the network relay device with the timing of the clock;
  A data transmission unit for transmitting data synchronized by the synchronization control unit;
Have
  The connection control device includes:
  A synchronization state information acquisition unit for acquiring synchronization state information indicating a synchronization state of the synchronous transfer device from each of the plurality of synchronous transfer devices;
  A path control unit that controls a communication path of data in the asynchronous communication network by controlling connection between the plurality of network relay devices based on the synchronization state information of each of the plurality of synchronous transfer apparatuses;
Having a synchronous control system.

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