Search

JP-2026075337-A - Delay measurement method and communication system

JP2026075337AJP 2026075337 AJP2026075337 AJP 2026075337AJP-2026075337-A

Abstract

[Challenge] To perform high-precision delay measurement. [Solution] Communication device 1 inserts a DM identifier into the first frame signal and starts measuring the delay time. It extracts the DM identifier and the measurement result of the processing time from the second frame signal received from communication device 2. It calculates the delay time of the communication path between communication devices 1 and 2 by subtracting the measurement result of the processing time from the measurement result of the delay time from the insertion of the DM identifier to the detection of the DM identifier contained in the second frame signal. Communication device 2 starts measuring the processing time at the same time as detecting the DM identifier contained in the received first frame signal. It inserts the extracted DM identifier into the second frame signal to be transmitted to communication device 1, and also inserts a value indicating the measurement result of the processing time from the detection of the DM identifier contained in the first frame signal to the insertion of the DM identifier into the second frame signal. [Selection Diagram] Figure 1

Inventors

  • 畑 隆弘
  • 武井 和人

Assignees

  • ＮＴＴイノベーティブデバイス株式会社

Dates

Publication Date
20260508
Application Date
20241022

Claims (11)

  1. The first step is for the first communication device to insert a DM identifier into a first frame signal to be transmitted to a second communication device connected to it via a network, The first communication device starts measuring the delay time simultaneously with the insertion of the DM identifier in a second step, A third step in which the first communication device transmits the first frame signal to the second communication device, The second communication device receives the first frame signal in a fourth step, The second communication device performs a fifth step of extracting a DM identifier from the first frame signal, The second communication device starts measuring the processing time simultaneously with detecting the DM identifier included in the first frame signal, A seventh step in which the second communication device inserts the DM identifier extracted in the fifth step into the second frame signal to be transmitted to the first communication device, and also inserts a value indicating the measurement result of the processing time from the detection of the DM identifier contained in the first frame signal to the insertion of the DM identifier into the second frame signal, The eighth step is for the second communication device to transmit the second frame signal to the first communication device, The first communication device receives the second frame signal in a ninth step, A tenth step of extracting a DM identifier and the measurement result of the processing time of the second communication device from the second frame signal, A delay measurement method characterized by including an eleventh step of calculating a value obtained by subtracting the measurement result of the processing time from the measurement result of the delay time from the insertion of a DM identifier into the first frame signal to the detection of a DM identifier contained in the second frame signal, as the delay time of the communication path between the first communication device and the second communication device.
  2. In the delay measurement method according to claim 1, The first communication device, in delay amount notification mode, sets a value to be added to the median value of the first FIFO buffer inserted on the path of the first frame signal within the device, A thirteenth step in which the first communication device adjusts the delay amount of the first FIFO buffer based on a value to be added to the median value when in delay amount notification mode, The second communication device further includes a 14th step in which, in delay amount notification mode, the second communication device adjusts the delay amount of the second FIFO buffer inserted into the path of the second frame signal within its own device based on a value to be added to the median value notified by the first communication device, The first step includes inserting the DM identifier into the first frame signal when in DM mode, and inserting a value to be added to the median value into the first frame signal when in delay amount notification mode. The fifth step is a delay measurement method characterized by including the step of extracting the DM identifier from the first frame signal when in DM mode, and extracting a value to be added to the median value from the first frame signal when in delay amount notification mode.
  3. A delay measurement method characterized by including the step of measuring the delay time of a second signal transmitted from a first communication device to a second communication device on the opposite side, in a parallel signal path formed in parallel with the path of a first signal transmitted and received between the first communication device and the opposing second communication device, from the starting end of the parallel signal path, which is located parallel to the starting end of the first signal path, to the end of the parallel signal path, which is located parallel to the end of the first signal path, as the delay time of the first signal path.
  4. In the delay measurement method according to claim 3, The steps include setting a value to be added to the median value of the FIFO buffers inserted on the path of the first signal and on the parallel signal path, respectively, A delay measurement method further comprising the step of adjusting the delay amount of the FIFO buffer based on a value to be added to the median value.
  5. The system comprises a first communication device and a second communication device connected to the first communication device via a network. The first communication device is A first insertion unit configured to insert a DM identifier into a first frame signal to be transmitted to the second communication device, A first transmitting unit configured to transmit the first frame signal to the second communication device, A first counter configured to start measuring the delay time simultaneously with the insertion of the DM identifier, A first receiving unit configured to receive a second frame signal transmitted from the second communication device, A first extraction unit configured to extract a DM identifier and the measurement result of the processing time of the second communication device from the second frame signal, The system includes a delay time calculation unit configured to calculate the delay time between the first communication device and the second communication device by subtracting the measurement result of the processing time from the measurement result of the delay time from the insertion of the DM identifier into the first frame signal to the detection of the DM identifier contained in the second frame signal, The second communication device is A second receiving unit configured to receive the first frame signal, A second extraction unit configured to extract a DM identifier from the first frame signal, A second counter configured to start measuring the processing time simultaneously with the detection of the DM identifier included in the first frame signal, A second insertion unit is configured to insert the DM identifier extracted by the second extraction unit into the second frame signal to be transmitted to the first communication device, and to insert a value indicating the measurement result of the processing time from the detection of the DM identifier contained in the first frame signal to the insertion of the DM identifier into the second frame signal, A communication system characterized by comprising a second transmitting unit configured to transmit the second frame signal to the first communication device.
  6. In the communication system described in claim 5, The first communication device is A first FIFO buffer inserted on the path of the first frame signal, A delay setting unit configured to set a value to be added to the median value of the first FIFO buffer when in delay amount notification mode, The system further comprises a first delay adjustment unit configured to adjust the delay amount of the first FIFO buffer based on a value to be added to the median value when in delay amount notification mode, The first insertion unit of the first communication device inserts the DM identifier into the first frame signal when in DM mode, and inserts a value to be added to the median value into the first frame signal when in delay amount notification mode. The second extraction unit of the second communication device extracts the DM identifier from the first frame signal in DM mode, and extracts a value to be added to the median value from the first frame signal in delay amount notification mode. The second communication device is A second FIFO buffer inserted on the path of the second frame signal, A communication system further comprising a second delay adjustment unit configured to adjust the delay amount of the second FIFO buffer based on a value to be added to the median value extracted by the second extraction unit when in delay amount notification mode.
  7. In the communication system according to claim 6, The first and second FIFO buffers are asynchronous FIFO buffers with different write and read clocks. A communication system characterized in that the first and second delay adjustment units adjust the frequency of the Read clock by PLL control so that the processing delay amount of the first and second frame signals remains constant, based on the usage amount of the first and second FIFO buffers and the value to be added to the median value.
  8. In the communication system according to claim 6, The first and second FIFO buffers are synchronous FIFO buffers that share a write clock and a read clock. A communication system characterized in that the first and second delay adjustment units adjust the Read pointers of the first and second FIFO buffers so that the processing delay amount of the first and second frame signals remains constant, based on the Write pointers of the first and second FIFO buffers and the value to be added to the median value.
  9. In the communication system according to claim 6, The first and second FIFO buffers are asynchronous FIFO buffers with different write and read clocks. A communication system characterized in that the first and second delay adjustment units use a basic read clock with a frequency higher than the design value of the read clock frequency of the first and second FIFO buffers, and output the result of masking the high period of the basic read clock as the read clock of the first and second FIFO buffers, based on the usage amount of the first and second FIFO buffers and the value to be added to the median, so that the processing delay amount of the first and second frame signals becomes constant.
  10. A parallel signal path formed in parallel with the path of the first signal transmitted and received between the opposing communication device and the other party, A communication device comprising: a delay time measuring unit that measures the delay time of a second signal transmitted from the starting end of the parallel signal path, which is located parallel to the starting end of the first signal path, to the end of the parallel signal path, which is located parallel to the end of the first signal path, as the delay time of the first signal path.
  11. In the communication device according to claim 10, A first FIFO buffer inserted on the path of the first signal, A second FIFO buffer inserted on the aforementioned parallel signal path, A delay setting unit configured to set a value to be added to the median value of the first and second FIFO buffers, A communication device further comprising a delay adjustment unit configured to adjust the delay amounts of the first and second FIFO buffers based on a value to be added to the median value.

Description

This invention relates to a delay measurement method, a communication system, and a communication device. The standard ODU (Optical Channel Data Unit) DM (Delay Measurement) function, as defined in ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) G. 709, is a function that measures the amount of delay in the communication path on a frame-by-frame basis (see Non-Patent Documents 1, 2, and 3). Figure 19 illustrates a conventional DM (Direct Debit) function. The communication device 1000 inserts a DM identifier into Row 2 and Col 3 of the control overhead (hereinafter referred to as OH) of the ODU frame 2000, and increments a delay measurement counter every frame. The insertion of the DM identifier is performed by bit-inverting any of the seven bits in Row 2 and Col 3 of the OH. Communication device 1001 extracts the DM identifier from the OH of the ODU frame 2000 transmitted from communication device 1000. Communication device 1001 inserts the extracted DM identifier into Row 2 and Col 3 of the OH of the ODU frame 2001 sent to communication device 1000. The extraction and insertion of the DM identifier is performed by extracting Row 2 and Col 3 of the OH of the ODU frame 2000 and inserting them into Row 2 and Col 3 of the OH of the ODU frame 2001. Communication device 1000 extracts Row2 and Col3 of the OH field of ODU frame 2001 transmitted from communication device 1001. Communication device 1000 terminates DM when it receives the same values for Row2 and Col3 inserted into the OH field of ODU frame 2000 for three consecutive frames. Communication device 1000 obtains the measurement result of the number of frames from the insertion of the DM identifier to the termination of DM from a counter, and subtracts the protection time (3 frames) from the measurement result to determine the delay amount of the communication path between communication device 1000 and 1001. Conventional DM (Direct Delay) functions had the problem of using frames as the unit of delay measurement, resulting in a coarse granularity of delay measurement (for example, 1.2 μs for ODU4). Furthermore, at the communication device 1001, which is the loopback point of the DM signal, a delay occurs due to the loopback processing, separate from the delay amount of the communication path, leading to errors in the delay measurement results. Additionally, because the DM function is not defined as a standard for the FlexO (Flexible OTN) frame format, delay measurement could not be performed in applications where ODU OH (OIF 400ZR/800ZR, etc.) does not exist. Furthermore, conventional DM (Direct Demand) functions had the drawback of not being able to measure the delay time for both the frame transmission process and the frame reception process within the device. "JT-G709 Interfaces for the Optical Transport Network (OTN)", Information and Communications Technology Committee, March 1, 2011, <https://www.ttc.or.jp/application/files/4615/5425/1895/JT-G709v2.1.pdf>“Characteristics of optical transport network hierarchy equipment functional blocks”, ITU-T Recommendation G.798, 2010“Flexible OTN common elements”, ITU-T Recommendation G.709.1, 2024 Figure 1 is a block diagram showing the configuration of a communication system according to a first embodiment of the present invention.Figure 2 is a flowchart illustrating the operation of the transmitting communication device during DM according to the first embodiment of the present invention.Figure 3 is a flowchart illustrating the operation of the loopback-side communication device during DM according to the first embodiment of the present invention.Figure 4 is a timing chart illustrating the operation of the transmitting communication device during DM according to the first embodiment of the present invention.Figure 5 is a timing chart illustrating the operation of the loopback-side communication device during DM according to the first embodiment of the present invention.Figure 6 is a block diagram showing the configuration of a communication system according to a second embodiment of the present invention.Figure 7 is a flowchart illustrating the operation of the transmitting communication device during DM according to a second embodiment of the present invention.Figure 8 is a flowchart illustrating the operation of the loopback-side communication device during DM according to a second embodiment of the present invention.Figure 9 is a block diagram showing the configuration of the FIFO buffer and delay adjustment unit according to a second embodiment of the present invention.Figure 10 is a block diagram showing the configuration of a FIFO buffer and a delay adjustment unit according to a third embodiment of the present invention.Figure 11 is a block diagram showing the configuration of a FIFO buffer and a delay adjustment unit according to a fourth embodiment of the present invention.Figure 12 is a waveform diagram showing an example of mask control by a mask control uni