Communication device and communication control method

Abstract

In one aspect of the present invention, a first communication device and a second communication device are connected to each other via a transmission path. The first communication device comprises a measurement unit that uses a second clock different from a first clock used for processing a signal to be transmitted to measure a first measurement value representing a time required for a delay measurement signal transmitted from the first communication device to be transferred in a second communication device and return to the first communication device. The second communication device comprises a measurement unit that uses the second clock to measure a second measurement value representing a time required to transfer the delay measurement signal from a received signal to a signal to be transmitted in the second communication device.

Description

Communication device and communication control method

[0001] The present invention relates to the technology of a communication device and a communication control method.

[0002] In a communication network, high-precision management of the transmission delay of a communication line is required. Use cases via a communication line include, for example, use cases with interaction between people, use cases with interaction between a person and a computer, and use cases with interaction between computers. Examples of use cases with interaction between people include remote e-sports battles, online meetings, remote chorus, remote ensemble, remote manzai, remote dance, remote concerts, remote sports events, and the like. Examples of use cases with interaction between a person and a computer include, for example, remote high-performance computing, remote game play, and the like. Examples of use cases with interaction between computers include, for example, high-frequency financial transactions using computers, computer clustering using computers at multiple locations, and the like. In such use cases, first, it is required to measure the delay of the communication line and adjust it as necessary. Also, when the delay varies over time, it is necessary to measure the temporal delay variation and adjust it as necessary.

[0003] An example of measuring the delay in a communication line between a first transmission device and a second transmission device will be described. Figure 20 shows an example of the configuration of a conventional communication system. The conventional communication system 900 has a first transmission device 910 and a second transmission device 930. The first transmission device 910 and the second transmission device 930 are connected to each other via a transmission line 950. The first transmission device 910 has a CL (client) signal receiving unit 911, a main signal processing unit 912, an NW (network) signal transmitting unit 913, an NW (network) signal receiving unit 914, a main signal processing unit 915, a CL signal transmitting unit 916, a clock unit 917, an insertion unit 918, a detection unit 919, and a counting unit 920. The second transmission device 930 includes an NW signal receiving unit 931, a main signal processing unit 932, a CL signal transmitting unit 933, a CL signal receiving unit 934, a main signal processing unit 935, an NW signal transmitting unit 936, a detection unit 937, a clock unit 938, and an insertion unit 939.

[0004] In response to a trigger from an operator or operating system, the first transmission device 910 inserts a delay measurement signal into the main signal via the main signal processing unit 912 on the transmitting side, in accordance with an insertion instruction from the insertion unit 918. At the same time, the insertion unit 918 notifies the counting unit 920 that the delay measurement signal has been inserted. The delay measurement signal inserted by the main signal processing unit 912 of the first transmission device 910 is passed to the NW signal transmission unit 913 and sent to the transmission line 950.

[0005] The NW signal receiving unit 931 of the second transmission device 930 receives the NW signal sent by the first transmission device 910 and outputs the received NW signal to the receiving-side main signal processing unit 932. The main signal processing unit 932 detects a delay measurement signal from the main signal and notifies the detection unit 937 of the detection. Furthermore, the detection unit 937 notifies the insertion unit 939 for the signal in the opposite direction of the bidirectional communication. In response to the insertion instruction from the insertion unit 939, the transmitting-side main signal processing unit 935 inserts the delay measurement signal into the main signal. The delay measurement signal inserted by the main signal processing unit 935 of the second transmission device 930 is passed to the NW signal transmitting unit 936 and sent to the transmission line 950.

[0006] Subsequently, the NW signal receiving unit 914 of the first transmission device 910 receives the NW signal sent by the second transmission device 930 and outputs the received NW signal to the receiving-side main signal processing unit 915. The main signal processing unit 915 detects a delay measurement signal from the main signal and notifies the detection unit 919. The detection unit 919 notifies the counting unit 920 when it receives the notification. The counting unit 920 counts the time difference between the timing when the first transmission device 910 first inserted the delay measurement signal and the timing when the delay measurement signal propagated through the transmission line 950, looped back, and returned to be detected. At that time, the counting unit 920 counts the time difference based on the frame pulse from the main signal processing unit 912. A frame pulse is a signal synchronized with the boundary of a frame. For example, when using the OTU4 signal in an OTN defined by ITU-T, one period of the frame pulse is approximately 1.17 u. The location where the delay measurement signal is inserted relative to the main signal is, for example, the ODU PM delay measurement (DMp) subfield described in section 15.8.2.1.6 of Non-Patent Document 1.

[0007] ITU-T G.709 / Y.1331 (2020) Cor. 2 (11 / 2022)”, ITU-T “Interfaces for the optical transport network”, International Telecommunication Union, 2022

[0008] However, in the conventional technology, the second transmission device 930 is configured to loop back the delay measurement signal, but generally, there is uncertainty in the timing at which the delay measurement signal can be inserted into the signal in the opposite direction of bidirectional communication. For this reason, in the conventional technology, insertion may take a short time or a long time. This leads to a deterioration in the accuracy of delay measurement. In addition, the counting unit 920 counts the delay difference based on the frame period received from the main signal processing unit 912 of the first transmission device 910. Thus, in the conventional technology, since the accuracy of delay measurement is based on a signal that depends on the main signal, the accuracy of delay measurement is limited to that signal. In this way, the conventional technology has the problem that there is uncertainty when looping back the delay measurement signal, and the accuracy of delay measurement is limited to that signal. In view of the above circumstances, the present invention aims to provide a technology that can measure the transmission delay of a communication line with high accuracy in a communication network.

[0009] One aspect of the present invention is a communication device in which a first communication device and a second communication device are connected to each other via a transmission line, the first communication device includes a measurement unit that measures a first measurement value representing the time required for a delay measurement signal transmitted from the first communication device to be re-transmitted by the second communication device and returned to the first communication device, using a second clock different from a first clock used for processing the transmitted signal, and the second communication device includes a measurement unit that measures a second measurement value representing the time required for the second communication device to re-transmit the delay measurement signal from a received signal to a transmitted signal, using the second clock.

[0010] One aspect of the present invention is a communication control method for a first communication device and a second communication device connected to each other via a transmission line, wherein a measurement unit measures a first measurement value, which represents the time required for a delay measurement signal transmitted from the first communication device to be re-transmitted by the second communication device and returned to the first communication device, using a second clock different from a first clock used for processing the transmitted signal; and the measurement unit measures a second measurement value, which represents the time required for the second communication device to re-transmit the delay measurement signal from the received signal to the transmitted signal, using the second clock.

[0011] This invention makes it possible to measure the transmission delay of communication lines in a communication network with high accuracy.

[0012] This is a diagram showing an example of the system configuration of the communication system of the first embodiment. This is an example of the configuration of the first communication device of the first embodiment. This is an example of the configuration of the second communication device of the first embodiment. This is a flowchart of the processing performed by the first communication device and the second communication device of the first embodiment. This is a diagram showing an example of the configuration of a communication system in which the first communication device is equipped with a delay control device. This is a diagram showing an example of the configuration of the communication system of the second embodiment. This is an example of the configuration of the first communication device of the second embodiment. This is an example of the configuration of the second communication device of the second embodiment. This is a flowchart of the processing of the communication system of the second embodiment. This is a diagram showing an example of the configuration of the communication system of the third embodiment. This is an example of the configuration of the first communication device of the third embodiment. This is an example of the configuration of the second communication device of the third embodiment. This is a diagram showing a first example of the configuration of the clock group generation unit and the measurement unit. This is a diagram showing a first example of the configuration of the clock group generation unit and the measurement unit. This is a diagram showing an example of the notification signal from the insertion unit and the notification signal from the detection unit and the distributed third clock. This is a diagram showing the delay adjustment unit on the transmitting side and the delay adjustment unit on the receiving side. This is a diagram showing an example of the adjustment configuration of the FIFO. This is a diagram showing an example of adjustment when increasing the delay and an example of adjustment when decreasing the delay. This figure shows a schematic of an example hardware configuration of an information processing device applied to the embodiment. This figure shows an example configuration of a conventional communication system.

[0013] Embodiments of the present invention will be described in detail with reference to the drawings.

[0014] <First Embodiment> Figure 1 is a diagram showing an example of the system configuration of the communication system of this embodiment. As shown in Figure 1, the communication system 1 includes, for example, a first communication device 2 (first communication device), a second communication device 3 (second communication device), and a delay control device 4. The delay control device 4 includes, for example, a correction unit 41 and a delay control unit 42. The first communication device 2 and the second communication device 3 are connected to each other via a transmission line 5. The first communication device 2 and the delay control device 4 are connected to each other via a wired line or a wireless line. The second communication device 3 and the delay control device 4 are connected to each other via a wired line or a wireless line.

[0015] Figure 2 shows an example of the configuration of the first communication device of this embodiment. As shown in Figure 2, the first communication device 2 includes, for example, a CL signal receiving unit 201, a main signal processing unit 202 on the transmitting side, a delay adjustment unit 203 on the transmitting side, an NW signal transmitting unit 204, an NW signal receiving unit 205, a delay adjustment unit 206 on the receiving side, a main signal processing unit 207 on the receiving side, a CL signal transmitting unit 208, a first clock unit 209, an insertion unit 210, a detection unit 211, a second clock unit 212, and a measurement unit 213.

[0016] Figure 3 shows an example of the configuration of the second communication device of this embodiment. As shown in Figure 3, the second communication device 3 includes, for example, an NW signal receiving unit 301, a receiving-side delay adjustment unit 302, a receiving-side main signal processing unit 303, a CL signal transmitting unit 304, a CL signal receiving unit 305, a transmitting-side main signal processing unit 306, a transmitting-side delay adjustment unit 307, an NW signal transmitting unit 308, a detection unit 309, a first clock unit 310, an insertion unit 311, a second clock unit 312, and a measurement unit 313.

[0017] In other words, as shown in Figures 2 and 3, the first communication device 2 and the second communication device 3 each include a CL signal receiving unit (201, 305), a main signal processing unit on the transmitting side (202, 306), a delay adjustment unit on the transmitting side (203, 307), an NW signal transmitting unit (204, 308), an NW signal receiving unit (205, 301), a delay adjustment unit on the receiving side (206, 302), a main signal processing unit on the receiving side (207, 303), a CL signal transmitting unit (208, 304), a first clock unit (209, 310), an insertion unit (210, 311), a detection unit (211, 309), a second clock unit (212, 312), and a measurement unit (213, 313).

[0018] As shown in Figure 1, the communication system 1 consists of a first communication device 2 and a second communication device 3 facing each other, with a communication path established between them. In Figures 2 and 3, the dashed line g1 shows a schematic representation of the signal flow for delay measurement between the first communication device 2 and the second communication device 3.

[0019] Next, the measurement and adjustment processes for the delay amount in communication system 1 will be explained using Figures 1 to 3. In the first communication device 2, the first clock generated by the first clock unit 209 is input to the main signal processing unit 202, and the second clock generated by the second clock unit 212 is input to the measurement unit 213. In the second communication device 3, the first clock generated by the first clock unit 310 is input to the main signal processing unit 306, and the second clock generated by the second clock unit 312 is input to the measurement unit 313. The frequency of the first clock is, for example, 350 MHz, and the frequency of the second clock is a different frequency from the first clock and higher than the frequency of the first clock, for example, 750 MHz. In the first communication device 2, the first clock unit 209 may use a clock regenerated in, for example, the CL signal receiving unit 201 or the NW signal receiving unit 204. Furthermore, in the second communication device 3, the first clock unit 310 may use, for example, a clock regenerated in the CL signal receiving unit 305 or the NW signal receiving unit 301.

[0020] (Insertion process of delay measurement signal on the first communication device side) The CL signal receiving unit 201 receives, for example, a client signal from a client device (not shown). The insertion unit 210 sends an instruction to the main signal processing unit 202 to insert a delay measurement signal, for example, triggered by an operator or operation system. The main signal processing unit 202 inserts a delay measurement signal into the main signal based on the insertion instruction from the insertion unit 210. The main signal processing unit 202 notifies the insertion unit 210 that the insertion of the delay measurement signal is complete when the insertion is finished. The insertion unit 210 notifies the measurement unit 213 of the timing of the delay measurement signal insertion. The signal with the inserted delay measurement signal is sent from the NW signal transmission unit 204 via the delay adjustment unit 203.

[0021] (Insertion process of delay measurement signal and delay amount measurement process on the second communication device side) The signal into which the delay measurement signal has been inserted in the first communication device 2 reaches the second communication device 3 via the transmission line 5. The NW signal receiving unit 301 receives the NW signal sent by the first communication device 2 and outputs the received NW signal to the delay adjustment unit 302. The delay adjustment unit 302 outputs the input NW signal to the main signal processing unit 303. The main signal processing unit 303 detects the delay measurement signal and notifies the detection unit 309 at the time of detection. The detection unit 309 notifies the insertion unit 311 and the measurement unit 313 that the delay measurement signal has been detected. The insertion unit 311 sends an instruction to the main signal processing unit 306 to insert the delay measurement signal. The main signal processing unit 306 inserts the delay measurement signal into the main signal and notifies the insertion unit 311 that the insertion is complete at the time of insertion. The insertion unit 311 notifies the measurement unit 313 at the timing of completion notification from the main signal processing unit 306. The measurement unit 313 counts the time difference between the detection timing from the detection unit 309 and the insertion timing from the insertion unit 311, based on the second clock generated by the second clock unit 312. The time counted by the measurement unit 313 is the time required to transfer (loop back) the delay measurement signal from the NW signal received by the second communication device 3 to the NW signal to be transmitted. In this embodiment, this time is called Loopback-Extra-Delay (LED) (second measurement value). The measurement unit 313 notifies the correction unit 41 of the delay control device 4 of the LED. The signal with the inserted delay measurement signal is sent from the NW signal transmission unit 308 via the delay adjustment unit 307.

[0022] (Delay measurement processing on the first communication device side) The signal into which the delay measurement signal has been inserted in the second communication device 3 reaches the first communication device 2 via the transmission line 5. The NW signal receiving unit 205 receives the NW signal sent by the second communication device 3 and outputs the received NW signal to the delay adjustment unit 206. The delay adjustment unit 206 outputs the input NW signal to the main signal processing unit 207. The main signal processing unit 207 detects the delay measurement signal and notifies the detection unit 211 at the timing of detection. The detection unit 211 notifies the measurement unit 213 that it has detected the delay measurement signal. The measurement unit 213 counts the time difference between the insertion timing from the insertion unit 210 and the detection timing from the detection unit 211 based on the second clock generated by the second clock unit 211. The time counted by the measurement unit 213 is the time required for the delay measurement signal transmitted from the first communication device 2 to be looped back by the second communication device 3 and return to the first communication device 2. Because this loopback time is uncertain, in this embodiment it is called Raw-Roundtrip-Delay (RRD) (first measured value). The measurement unit 213 notifies the correction unit 41 of the delay control device 4 of the RRD.

[0023] (Processing in the delay control device) The correction unit 41 obtains the RRD from the first communication device 2 and the LED from the second communication device 3. In order to eliminate uncertainty in the loopback time, the correction unit 41 subtracts the LED from the RRD to obtain a highly accurate measurement result of the transmission delay time. The correction unit 41 notifies the delay control unit 42 of the obtained transmission delay time. The delay control unit 42 calculates the amount of delay to be set, for example, based on instructions from an operator (not shown) or an operation system (not shown), or by a predetermined algorithm, as needed, and notifies at least one of the delay adjustment unit 203 of the first communication device 2, the delay adjustment unit 206 of the first communication device 2, the delay adjustment unit 307 of the second communication device 3, and the delay adjustment unit 302 of the second communication device 3 of the amount of delay to be added.

[0024] At least one of the delay adjustment units (delay adjustment unit 203 of the first communication device 2, delay adjustment unit 206 of the first communication device 2, delay adjustment unit 307 of the second communication device 3, and delay adjustment unit 302 of the second communication device 3) that receives a notification from the delay control device 4 adjusts to the notified delay amount. The delay adjustment may be a continuous delay adjustment that changes the delay without interrupting the main signal, or a momentary delay adjustment that interrupts the main signal. An example of a continuous delay adjustment method will be described later.

[0025] (Uncertainty of Loopback Time) Next, we will explain the uncertainty of loopback time in the second communication device 3 using a specific example. Here, we will explain an example using the OTU4 signal of OTN as defined in ITU-T. The OTU4 signal is bidirectional and consists of an OTU4 signal from the first communication device 2 to the second communication device 3 and an OTU4 signal from the second communication device 3 to the first communication device 2, as shown in Figures 2 and 3. Both signals are generally asynchronous because they are generated using separate clock sources. The frame period of the OTU4 signal is approximately 1.17 (us), and when the insertion unit 311 in the opposite direction inserts the delay measurement signal into the main signal after the detection unit 309 in the second communication device 3 detects the delay measurement signal, there are cases where the delay measurement signal can be loaded in the shortest possible time and cases where it has to wait up to one frame, resulting in uncertainty of one frame, or approximately 1.17 (us). The LED measurement described above measures the time it takes for this delay measurement signal to loop back. Therefore, in this embodiment, by subtracting the LED from the RRD, it becomes possible to measure the transmission delay time with high accuracy.

[0026] The second clock of the first communication device 2 and the second clock of the second communication device 3 may be synchronized by means of wired or wireless connection. Alternatively, the first communication device 2 and the second communication device 3 may each use a second clock based on a high-precision clock such as an atomic clock. Synchronizing both clocks in this way enables more accurate measurements. Although the configuration described uses the first communication device 2 as the starting point for delay measurement and the second communication device 3 as a loopback, this is not the only configuration. The second communication device 3 may be the starting point for delay measurement and the first communication device 2 as a loopback.

[0027] (Example of Processing Procedure) Next, an example of a processing procedure performed by the first communication device 2 and the second communication device 3 will be described. Figure 4 is a flowchart of the processing performed by the first communication device and the second communication device in this embodiment. Note that the processing example in Figure 4 is an example in which the first communication device 2 is the starting point for delay measurement and the second communication device 3 performs a loopback.

[0028] (Step S1) The insertion unit 210 of the first communication device 2 outputs an instruction to insert a delay measurement signal to the main signal processing unit 202.

[0029] (Step S2) The main signal processing unit 202 of the first communication device 2 inserts a delay measurement signal into the main signal based on the insertion instruction from the insertion unit 210. Furthermore, when the insertion of the delay measurement signal is completed, the main signal processing unit 202 notifies the insertion unit 210 that the insertion is complete. Furthermore, the insertion unit 210 notifies the measurement unit 213 of the timing of the delay measurement signal insertion.

[0030] (Step S3) The NW signal transmission unit 204 of the first communication device 2 sends the NW signal with the delay measurement signal inserted to the second communication device 3 via the transmission line 5.

[0031] (Step S4) The NW signal receiving unit 301 of the second communication device 3 receives the NW signal transmitted by the first communication device 2.

[0032] (Step S5) The main signal processing unit 303 of the second communication device 3 detects the delay measurement signal and notifies the detection unit 309 at the time of detection. Furthermore, the detection unit 309 notifies the insertion unit 311 and the measurement unit 313 that the delay measurement signal has been detected.

[0033] (Step S6) The insertion unit 311 of the second communication device 3 outputs an instruction to the main signal processing unit 306 to insert a delay measurement signal.

[0034] (Step S7) The main signal processing unit 306 of the second communication device 3 inserts a delay measurement signal into the main signal and notifies the insertion unit 311 that the insertion is complete at the time of insertion. Furthermore, the insertion unit 311 notifies the measurement unit 313 at the time of the completion notification from the main signal processing unit 306.

[0035] (Step S8) The measurement unit 313 of the second communication device 3 counts the time difference between the detection timing from the detection unit 309 and the insertion timing from the insertion unit 311, based on the second clock generated by the second clock unit 312. Furthermore, the measurement unit 313 notifies the correction unit 41 of the delay control device 4 of the LED.

[0036] (Step S9) The NW signal transmission unit 308 of the second communication device 3 sends the NW signal with the delay measurement signal inserted to the first communication device 2 via the transmission line 5.

[0037] (Step S10) The NW signal receiving unit 205 of the first communication device 2 receives the NW signal transmitted by the second communication device 3.

[0038] (Step S11) The main signal processing unit 207 of the first communication device 2 detects the delay measurement signal and notifies the detection unit 211 at the time of detection. Furthermore, the detection unit 211 notifies the measurement unit 213 that it has detected the delay measurement signal.

[0039] (Step S12) The measurement unit 213 of the first communication device 2 counts the time difference between the insertion timing from the insertion unit 210 and the detection timing from the detection unit 211, based on the second clock generated by the second clock unit 211. Furthermore, the measurement unit 213 notifies the correction unit 41 of the delay control device 4 of the RRD.

[0040] (Step S13) The correction unit 41 of the delay control device 4 acquires the RRD from the first communication device 2 and the LED from the second communication device 3. Subsequently, the correction unit 41 subtracts the LED from the RRD to calculate the measurement result of the transmission delay time. Subsequently, the delay control unit 42 calculates the amount of delay to be set, for example, based on instructions from an operator (not shown) or an operation system (not shown), or according to a predetermined algorithm, as needed.

[0041] (Step S14) The delay control unit 42 of the delay control device 4 notifies at least one of the following of the calculated delay amount: the delay adjustment unit 203 of the first communication device 2, the delay adjustment unit 206 of the first communication device 2, the delay adjustment unit 307 of the second communication device 3, and the delay adjustment unit 302 of the second communication device 3.

[0042] (Step S15) At least one of the delay adjustment units (the delay adjustment unit 203 of the first communication device 2, the delay adjustment unit 206 of the first communication device 2, the delay adjustment unit 307 on the transmission side of the second communication device 3, the delay adjustment unit 302 of the second communication device 3) that has received a notification from the delay control device 4 adjusts to the notified delay amount.

[0043] Note that the above-described processing contents and processing procedures are merely examples and are not limited thereto. For example, some processes may be performed simultaneously or in parallel.

[0044] Here, the advantages of using the second clock will be described. In the prior art, the measurement unit measures the time difference between two notifications using the clock for generating the main signal or a clock dependent on that clock. For example, the case of using an OTU4 signal in OTN will be described. In ITU-T G.709, the delay measurement DM counts the time difference with a frame pulse indicating the boundary of the OTU4 frame. The frame period is about 1.17 (μs). This value will limit the accuracy of the delay measurement. Alternatively, it is also assumed to use the clock for generating OTU4. In this case, an example of the frequency is about 350 (MHz). When counting the time difference using this clock, the time difference is counted in units of about 2.86 (ns), which is one cycle of 350 (MHz), and this value will limit the accuracy.

[0045] In contrast, in this embodiment, high accuracy is achieved by providing a second clock unit (212, 312) separately from the first clock unit (209, 310) related to the main signal. Note that the clock output from the second clock unit (212, 312) may or may not be synchronized with the clock output from the first clock unit (209, 310). When both clocks are synchronized, the components can be simplified. When both clocks are not synchronized, the degree of freedom in selecting the clock frequency of the second clock unit (212, 312) is improved.

[0046] Here, consider using a clock in which the second clock section (212, 312) is asynchronous with the first clock section (209, 310) and the frequency of the second clock is higher than that of the first clock. A higher clock frequency means that one cycle of the clock becomes shorter, which means that the time difference measurement in the measurement section is made more accurate. For example, in the case of an OTU4 signal, the case where the first clock is about 350 (MHz) will be described. At this time, if a 1 (GHz) clock is used as the second clock, the measurement section will measure the time difference in units of 1.00 (ns). Therefore, it can be made more accurate than 2.86 (ns) when using a 350 (MHz) clock or 1.17 (us) when using an OTU4 frame pulse.

[0047] In addition, since adjustment is possible if there is one delay adjustment section on the communication path, it is also possible to adopt a configuration in which only a specific device is provided with the delay adjustment section. Alternatively, when adjusting a large delay amount and the delay amount that can be adjusted by a single delay adjustment section is exceeded, a combination of a plurality of delay adjustment sections and a plurality of transmission devices may be used.

[0048] Also, the delay adjustment can be used to compensate for delay fluctuations. For example, it is known that the delay of an optical fiber transmission line changes according to temperature. Therefore, in the present embodiment, the transmission delay of the optically transmitted signal is measured at any time, and based on that value, the delay adjustment is periodically performed, so that the delay fluctuation can be compensated and the same delay can always be maintained.

[0049] (Modified Example) In the above-described example, an example in which the delay control device 4 is outside the first communication device 2 and the second communication device 3 has been described, but the present invention is not limited to this. The delay control device 4 may be provided in at least one of the first communication device 2 and the second communication device 3.

[0050] Figure 5 shows an example of a communication system configuration in which the first communication device is equipped with a delay control device. As shown in Figure 5, in communication system 1A, the first communication device 2A (first communication device) is equipped with a delay control device 4. The first communication device 2A and the second communication device 3 (second communication device) communicate with each other via a transmission line 5. In this configuration, the delay control device 4 equipped in the first communication device 2A collects LEDs and RRDs and performs correction processing and notification processing. Alternatively, the first communication device 2A or the second communication device 3 may be equipped with a correction unit 41 of the functions of the delay control device 4, and the delay control device 4 may be equipped with a delay control unit 42.

[0051] <Second Embodiment> This embodiment describes an example of measuring and adjusting the amount of delay in multiplexed communication. Figure 6 is a diagram showing an example of the configuration of the communication system of this embodiment. As shown in Figure 6, the communication system 1B includes, for example, a first communication device 2B (first communication device), a second communication device 3B (second communication device), and a delay control device 4B. The delay control device 4B includes, for example, a correction unit 41, a delay control unit 42, a correction unit 43, and a delay control unit 44. The first communication device 2B and the second communication device 3B are connected to each other via a transmission line 5. The first communication device 2B and the delay control device 4B are connected to each other via a wired line or a wireless line. The second communication device 3B and the delay control device 4B are connected to each other via a wired line or a wireless line.

[0052] Figure 7 shows an example of the configuration of the first communication device of this embodiment. As shown in Figure 7, the first communication device 2B includes, for example, a CL signal receiving unit 201, a main signal processing unit 202 on the transmitting side, a delay adjustment unit 203B on the transmitting side, an NW signal transmitting unit 204B, an NW signal receiving unit 205B, a delay adjustment unit 206B on the receiving side, a main signal processing unit 207 on the receiving side, a CL signal transmitting unit 208, a first clock unit 209B, an insertion unit 210, a detection unit 211, a second clock unit 212B, a measurement unit 213, a multiplexing unit 221, a main signal processing unit 222 on the transmitting side, a delay adjustment unit 223 on the transmitting side, a delay adjustment unit 224 on the receiving side, a main signal processing unit 225 on the receiving side, a separation unit 226, an insertion unit 227, a detection unit 228, and a measurement unit 229.

[0053] Figure 8 shows an example of the configuration of the second communication device of this embodiment. As shown in Figure 8, the second communication device 3B includes, for example, an NW signal receiving unit 301B, a receiving-side delay adjustment unit 302, a receiving-side main signal processing unit 303B, a CL signal transmitting unit 304B, a CL signal receiving unit 305B, a transmitting-side main signal processing unit 306B, a transmitting-side delay adjustment unit 307, an NW signal transmitting unit 308B, a detection unit 309, a first clock unit 310B, an insertion unit 311, a second clock unit 312B, a measurement unit 313, a separation unit 321, a receiving-side delay adjustment unit 322, a receiving-side main signal processing unit 323, a transmitting-side main signal processing unit 324, a transmitting-side delay adjustment unit 325, a multiplexing unit 326, a detection unit 327, an insertion unit 328, and a measurement unit 329.

[0054] In other words, the first communication device 2B and the second communication device 3B each include two sets of delay adjustment units on the transmitting side, two sets of delay adjustment units on the receiving side, two sets of main signal processing units on the transmitting side, two sets of main signal processing units on the receiving side, two sets of insertion units, two sets of detection units, two sets of measurement units, and further a multiplexing unit and a separation unit. In the first communication device 2B, the first clock unit 209B may use a clock regenerated in, for example, the CL signal receiving unit 201 or the NW signal receiving unit 204B. In the second communication device 3B, the first clock unit 310B may use a clock regenerated in, for example, the CL signal receiving unit 305B or the NW signal receiving unit 301B. Furthermore, the second clock of the first communication device 2B and the second clock of the second communication device 3B may be synchronized by means such as wired or wireless. Alternatively, the first communication device 2B and the second communication device 3B may each use a second clock based on a high-precision clock such as an atomic clock. Synchronizing the two clocks in this way enables more precise measurements.

[0055] Next, the measurement and adjustment processes for the delay amount in communication system 1B will be explained using Figures 6 to 9. In the first communication device 2B, the first clock generated by the first clock unit 209B is input to the main signal processing unit 202 and the main signal processing unit 222, and the second clock generated by the second clock unit 212B is input to the measurement unit 213 and the measurement unit 229. In the second communication device 3B, the first clock generated by the first clock unit 310B is input to the main signal processing unit 306 and the main signal processing unit 324, and the second clock generated by the second clock unit 312B is input to the measurement unit 313 and the measurement unit 329.

[0056] Figure 9 is a flowchart of the processing of the communication system in this embodiment. The processing example in Figure 9 is an example in which the first communication device 2B is used as the starting point for delay measurement, and the second communication device 3B performs a loopback.

[0057] (Step S101) The insertion unit 210 of the first communication device 2B outputs an instruction to insert a delay measurement signal to the main signal processing unit 202.

[0058] (Step S102) The main signal processing unit 202 of the first communication device 2B inserts a delay measurement signal into the main signal based on an insertion instruction from the insertion unit 210, and outputs the main signal with the inserted delay measurement signal to the multiplexing unit 221 via the delay adjustment unit 203B. Furthermore, when the insertion of the delay measurement signal is completed, the main signal processing unit 202 notifies the insertion unit 210 that the insertion is complete. Furthermore, the insertion unit 210 notifies the measurement unit 213 of the timing of the delay measurement signal insertion.

[0059] (Step S103) The multiplexing unit 221 of the first communication device 2B multiplexes the signal into which the delay measurement signal has been inserted by the main signal processing unit 202 with other signals and outputs it to the main signal processing unit 222.

[0060] (Step S104) The insertion unit 227 of the first communication device 2B outputs an instruction to insert a delay measurement signal to the main signal processing unit 222.

[0061] (Step S105) The main signal processing unit 222 of the first communication device 2B inserts a delay measurement signal into the main signal based on the insertion instruction from the insertion unit 227, and outputs the main signal with the inserted delay measurement signal to the NW signal transmission unit 204B via the delay adjustment unit 223. Furthermore, when the insertion of the delay measurement signal is completed, the main signal processing unit 222 notifies the insertion unit 227 that the insertion is complete. Furthermore, the insertion unit 227 notifies the measurement unit 229 of the timing of the delay measurement signal insertion.

[0062] (Step S106) The NW signal transmission unit 204B of the first communication device 2B sends the NW signal, which has a delay measurement signal inserted and is multiplexed, to the second communication device 3B via the transmission line 5.

[0063] (Step S107) The NW signal receiving unit 301B of the second communication device 3B receives the NW signal sent by the first communication device 2B and outputs the received NW signal to the main signal processing unit 303B via the delay adjustment unit 302.

[0064] (Step S108) The main signal processing unit 303B of the second communication device 3B detects the delay measurement signal and notifies the detection unit 309 at the time of detection. Furthermore, the detection unit 309 notifies the insertion unit 311 and the measurement unit 313 that the delay measurement signal has been detected. Furthermore, the main signal processing unit 303B outputs the input multiplexed signal to the separation unit 321.

[0065] (Step S109) The separation unit 321 of the second communication device 3B separates the multiplexed signals and outputs the separated main signals to the main signal processing unit 323 via the delay adjustment unit 322.

[0066] (Step S109) The main signal processing unit 323 of the second communication device 3B detects the delay measurement signal and notifies the detection unit 327 at the time of detection. Furthermore, the detection unit 327 notifies the insertion unit 328 and the measurement unit 329 that the delay measurement signal has been detected. Furthermore, the main signal processing unit 323 outputs the input main signal to the CL signal transmission unit 304B.

[0067] (Step S110) The CL signal transmission unit 304B of the second communication device 3B sends a CL signal to another communication device. The CL signal receiving unit 305B receives a CL signal from the other communication device and outputs the received signal to the main signal processing unit 324.

[0068] (Step S111) The insertion unit 328 of the second communication device 3B outputs an instruction to the main signal processing unit 324 to insert a delay measurement signal.

[0069] (Step S112) The main signal processing unit 324 of the second communication device 3B inserts a delay measurement signal into the main signal based on the insertion instruction from the insertion unit 328, and outputs the main signal with the inserted delay measurement signal to the multiplexing unit 326 via the delay adjustment unit 325. Furthermore, when the insertion of the delay measurement signal is completed, the main signal processing unit 324 notifies the insertion unit 328 that the insertion is complete. Subsequently, the insertion unit 328 notifies the measurement unit 329 at the same time as the completion notification from the main signal processing unit 324.

[0070] (Step S113) The multiplexing unit 326 of the second communication device 3B multiplexes the signal into which the delay measurement signal has been inserted by the main signal processing unit 324 with other signals and outputs it to the main signal processing unit 306B.

[0071] (Step S114) The insertion unit 311 of the second communication device 3B outputs an instruction to insert a delay measurement signal to the main signal processing unit 306B.

[0072] (Step S115) The main signal processing unit 306B of the second communication device 3B inserts a delay measurement signal into the main signal based on the insertion instruction from the insertion unit 311, and outputs the main signal with the inserted delay measurement signal to the NW signal transmission unit 308B via the delay adjustment unit 307. Furthermore, when the insertion of the delay measurement signal is completed, the main signal processing unit 306B notifies the insertion unit 311 that the insertion is complete. Subsequently, the insertion unit 311 notifies the measurement unit 313 at the same time as the completion notification from the main signal processing unit 306B.

[0073] (Step S116) The measurement unit 329 of the second communication device 3B counts the time difference between the detection timing from the detection unit 327 and the insertion timing from the insertion unit 328 based on the second clock generated by the second clock unit 312B. Furthermore, the measurement unit 329 notifies the correction unit 41 of the delay control device 4B of the counted LEDs. Furthermore, the measurement unit 313 of the second communication device 3B counts the time difference between the detection timing from the detection unit 309 and the insertion timing from the insertion unit 311 based on the second clock generated by the second clock unit 312. Furthermore, the measurement unit 313 notifies the correction unit 43 of the delay control device 4B of the counted LEDs.

[0074] (Step S117) The NW signal transmission unit 308B of the second communication device 3 sends the NW signal, which has a delay measurement signal inserted and is multiplexed, to the first communication device 2B via the transmission line 5.

[0075] (Step S118) The NW signal receiving unit 205B of the first communication device 2B receives the multiplexed NW signal sent by the second communication device 3B and outputs the received NW signal to the main signal processing unit 225 via the delay adjustment unit 224.

[0076] (Step S119) The main signal processing unit 225 of the first communication device 2B detects the delay measurement signal and notifies the detection unit 228 at the time of detection. Furthermore, the detection unit 228 notifies the measurement unit 229 that it has detected the delay measurement signal. Furthermore, the main signal processing unit 225 outputs the input signal to the separation unit 226.

[0077] (Step S120) The separation unit 226 of the first communication device 2B separates the multiplexed signals and outputs the separated main signals to the main signal processing unit 207 via the delay adjustment unit 206B.

[0078] (Step S121) The main signal processing unit 207 of the first communication device 2B detects the delay measurement signal and notifies the detection unit 211 at the time of detection. Furthermore, the detection unit 211 notifies the measurement unit 213 that it has detected the delay measurement signal. Furthermore, the main signal processing unit 207 outputs the input signal to the CL signal transmission unit 208.

[0079] (Step S122) The measurement unit 229 of the first communication device 2B counts the time difference between the detection timing from the detection unit 327 and the insertion timing from the insertion unit 328 based on the second clock generated by the second clock unit 212B. Furthermore, the measurement unit 229 notifies the correction unit 43 of the delay control device 4B of the counted RRD. Furthermore, the measurement unit 213 of the first communication device 2B counts the time difference between the detection timing from the detection unit 211 and the insertion timing from the insertion unit 210 based on the second clock generated by the second clock unit 212B. Furthermore, the measurement unit 313 notifies the correction unit 41 of the delay control device 4B of the counted RRD.

[0080] (Step S123) The correction unit 41 of the delay control device 4B acquires the RRD from the first communication device 2B and the LED from the second communication device 3B. Furthermore, the correction unit 43 of the delay control device 4B acquires the RRD from the first communication device 2B and the LED from the second communication device 3B. Subsequently, the correction unit 41 subtracts the LED from the RRD to calculate the measurement result of the transmission delay time. Subsequently, the correction unit 43 subtracts the LED from the RRD to calculate the measurement result of the transmission delay time. Subsequently, the delay control unit 42 calculates the amount of delay to be set, for example, based on instructions from an operator (not shown) or an operation system (not shown), or according to a predetermined algorithm, as needed. Furthermore, the delay control unit 44 calculates the amount of delay to be set, for example, based on instructions from an operator (not shown) or an operation system (not shown), or according to a predetermined algorithm, as needed.

[0081] (Step S124) The delay control unit 42 of the delay control device 4B notifies at least one of the delay adjustment units (203B, 206B, 322, 325) of the calculated delay amount. Furthermore, the delay control unit 44 of the delay control device 4B notifies at least one of the delay adjustment units (223, 224, 302, 307) of the calculated delay amount.

[0082] (Step S125) At least one of the delay adjustment units (203B, 223, 224, 206B, 302, 322, 325, 307) that has received notification from the delay control device 4B adjusts to the notified delay amount.

[0083] The processing content and procedures described above are merely examples and are not limited to them. For example, some processes may be performed simultaneously or in parallel.

[0084] Here, we will explain in detail using the case of OTN as an example. The communication path ODU defined in OTN is multiplexable. For example, an ODU2 signal of approximately 10 Gbps can be multiplexed into an ODU4 signal of approximately 100 Gbps. Figures 6 to 8 show a configuration that enables delay measurement and adjustment for both the ODU2 path and the ODU4 path. Each functional block before the main signal multiplexing unit or after the main signal separation unit is a block for the low-speed ODU path (Lower-Order ODU or LO-ODU), and each functional block after the main signal multiplexing unit or before the main signal separation unit is a block for the high-speed ODU path (Higher-Order ODU or HO-ODU). By adopting such a configuration, it becomes possible to measure and adjust the delay of both the LO-ODU and HO-ODU. Furthermore, in the conventional ITU-T OTN standard, the delay measurement accuracy differs depending on the type of ODU. For example, if ODU4 is used as the HO-ODU and ODU2 as the LO-ODU, the frame period of ODU4 is 1.168 (us) and the frame period of ODU2 is 12.191 (us), so the delay measurement accuracy of each is different.

[0085] As described above, with the configuration and processing of this implementation, even with multiplexed communication, accurate measurement and adjustment of the delay amount can be performed by using a second clock with a frequency different from and higher than the frequency of the first clock. With the configuration and processing of this implementation, since a common second clock is used for both the HO-ODU and LO-ODU, the same accuracy can be achieved.

[0086] In Figure 6, an example is shown in which the delay control device 4B is connected to the outside of the first communication device 2B and the second communication device 3B. However, the delay control device 4B may be provided in at least one of the first communication device 2B and the second communication device 3B. Also, in Figure 6, an example is shown in which the delay control device 4B includes two sets of correction units (41, 43) and two sets of delay control units (42, 44). However, it is not limited to this. For example, the first delay control device may include a correction unit 41 and a delay control unit 42, and the second delay control device may include a correction unit 43 and a delay control unit 44. Alternatively, for example, the correction unit 41 may have the functions of both the correction unit 41 and the correction unit 43, and for example, the delay control unit 42 may have the functions of both the delay control unit 42 and the delay control unit 44. Furthermore, the first communication device 2B or the second communication device 3B may have the correction unit 41 and the correction unit 43 among the functions of the delay control device 4B, and the delay control unit 42 and the delay control unit 44 may be provided by the delay control device 4B.

[0087] <Third Embodiment> In this embodiment, an example in which a group of clocks is used as the second clock will be described. Figure 10 is a diagram showing an example of the configuration of the communication system of this embodiment. As shown in Figure 10, the communication system 1C includes, for example, a first communication device 2C (first communication device), a second communication device 3C (second communication device), and a delay control device 4. The delay control device 4 includes, for example, a correction unit 41 and a delay control unit 42. The first communication device 2C and the second communication device 3C are connected to each other via a transmission line 5. The first communication device 2C and the delay control device 4 are connected to each other via a wired line or a wireless line. The second communication device 3C and the delay control device 4 are connected to each other via a wired line or a wireless line.

[0088] Figure 11 shows an example configuration of the first communication device of this embodiment. As shown in Figure 11, the first communication device 2C includes, for example, a CL signal receiving unit 201, a main signal processing unit 202 on the transmitting side, a delay adjustment unit 203 on the transmitting side, an NW signal transmitting unit 204, an NW signal receiving unit 205, a delay adjustment unit 206 on the receiving side, a main signal processing unit 207 on the receiving side, a CL signal transmitting unit 208, a first clock unit 209, an insertion unit 210, a detection unit 211, a measurement unit 213, and a clock group generation unit 231 (second clock unit).

[0089] Figure 12 shows an example configuration of the second communication device of this embodiment. As shown in Figure 12, the second communication device 3C includes, for example, an NW signal receiving unit 301, a receiving-side delay adjustment unit 302, a receiving-side main signal processing unit 303, a CL signal transmitting unit 304, a CL signal receiving unit 305, a transmitting-side main signal processing unit 306, a transmitting-side delay adjustment unit 307, an NW signal transmitting unit 308, a detection unit 309, a first clock unit 310, an insertion unit 311, a measurement unit 313, and a clock group generation unit 331 (second clock unit).

[0090] In other words, as shown in Figures 11 and 12, the first communication device 2C and the second communication device 3C each include a CL signal receiving unit 201 (305), a main signal processing unit 202 (303) on the transmitting side, a delay adjustment unit 203 (307) on the transmitting side, an NW signal transmitting unit 204 (308), an NW signal receiving unit 205 (301), a delay adjustment unit 206 (302) on the receiving side, a main signal processing unit 207 (303) on the receiving side, a CL signal transmitting unit 208 (304), a first clock unit 209 (310), an insertion unit 210 (311), a detection unit 211 (309), a clock group generation unit 231 (331) which is the second clock unit, and a measurement unit 213 (313). In the following description, symbols without parentheses are symbols for functional units of the first communication device 2C, and symbols within parentheses are symbols for functional units of the second communication device 3C. In the first communication device 2C, the first clock unit 209 may use a clock regenerated in, for example, the CL signal receiving unit 201 or the NW signal receiving unit 204. In the second communication device 3C, the first clock unit 310 may use a clock regenerated in, for example, the CL signal receiving unit 305 or the NW signal receiving unit 301.

[0091] Next, an example configuration of the clock group generation unit and the measurement unit will be described. The clock group generation unit 231 (331) generates multiple clocks and inputs them to the measurement unit 213 (313). The measurement unit 213 (313) then uses the multiple clocks to count the time difference and improve accuracy.

[0092] Figure 13 shows a first example configuration of the clock group generation unit and the measurement unit. In the first example, the measurement unit 213 (313) generates the clock １ Clock from 2311-1 (3311-1) Ｎ The configuration uses N clocks, from 2311-N (3311-N) where N is an integer greater than or equal to 2. In the first example, each of the N time difference counting units 2131-1 to 2131-N (3131-1 to 3131-N) counts the time difference using clocks 1 to N. Each time difference counting unit 2131-1 to 2131-N (3131-1 to 3131-N) receives a signal (e.g., a trigger signal) from the detection unit 211 (309) indicating the timing of the detection of the delay measurement signal. Each time difference counting unit also receives a signal (e.g., a trigger signal) from the insertion unit 210 (311) indicating the timing of the insertion of the delay measurement signal. Furthermore, the measurement unit 213 (313) achieves high-precision time difference counting by, for example, averaging the obtained N measurement results.

[0093] Figure 14 shows a second example configuration of the clock group generation unit and the measurement unit. In the second example, a single clock source is used and distributed to N units to generate multiple clocks, and then the phase adjustment unit 2314 (3314) adjusts the phase of each clock to generate a clock group. In the second example, the measurement unit 213 (313) uses the generated multiple clocks to count the time difference. In the second example, high-precision time difference counting is achieved, for example, by averaging the obtained N measurement results.

[0094] In the second example, the clock group generation unit 231 (331) includes, for example, a clock generation unit 2312 (3312), a distribution unit 2313 (3313), and a phase adjustment unit 2314 (3314). The measurement unit 213 (313) includes, for example, N time difference count units 2131-1 to 2131-N (3131-1 to 3131-N). Each time difference count unit 2131-1 to 2131-N (3131-1 to 3131-N) receives a signal (for example, a trigger signal) from the detection unit 211 (309) indicating the timing of the detection of the delay measurement signal. Each time difference count unit also receives a signal (for example, a trigger signal) from the insertion unit 210 (311) indicating the timing of the insertion of the delay measurement signal.

[0095] The clock generation unit 2312 (3312) generates a third clock. The frequency of the third clock may be higher, the same as, or lower than that of the first clock. The distribution unit 2313 (3313) distributes the third clock to, for example, N units, and outputs each of the distributed third clocks to the phase adjustment unit 2314 (3314). The phase adjustment unit 2314 (3314) shifts the phase of the N third clocks distributed by the distribution unit 2313 (3313) as shown in Figure 15, for example.

[0096] Figure 15 shows an example of a notification signal from the insertion unit, a notification signal from the detection unit, and a distributed third clock. In Figure 15, the horizontal axis represents time (s), and the vertical axis represents the level of each signal (H level or L level). Waveform g101 is the notification signal from the insertion unit, waveform g102 is the notification signal from the detection unit, and waveforms g103 to g110 are the clock group, which are examples of waveforms after phase adjustment of the signals distributed by the distribution unit.

[0097] In the example in Figure 15, the waveforms g103 to g110 after phase adjustment show an example where the frequencies of the eight clock systems are the same, but the phase difference differs by 2π / 8 each. The period T that the measurement unit 213 (313) counts is, for example, from when the notification signal from the insertion unit changes from L level to H level (between times t1 and t2) to when the notification signal from the detection unit changes from L level to H level (between times t13 and t14), and it counts the number of rising edges of each clock with a phase shift.

[0098] In the example shown in Figure 15, when the time difference of the object to be measured is measured using the clocks of each system, the number of rising edges of each waveform g103 to g110 during the counting period T is "1, 1, 2, 2, 2, 2, 1, 1". The measurement unit 213 (313) then averages these "1, 1, 2, 2, 2, 2, 1, 1" edges by 8 to obtain a count of 1.5. Thus, according to the configuration of the second example, by using a group of clocks, higher accuracy is possible compared to using a single clock.

[0099] Furthermore, in each of the embodiments and examples described above, the clock used for measuring the time difference may be dual-edge. In this case, accuracy can be improved by counting the time difference using not only the rising edge but also the falling edge of the clock. By measuring with such accuracy, for example, it becomes possible to make the delays of multiple communication lines the same, thereby enabling fair high-frequency financial transactions. Also, by measuring with such accuracy, for example, it becomes possible to achieve equal-length wiring by making the delays of multiple communication lines connecting multiple computers the same, thereby enabling efficient execution of real-time processing and other operations in cooperation with multiple computers.

[0100] <Examples of Delay Adjustment> Next, we will explain the embodiments and examples of delay adjustment in each of the above-described embodiments. Figure 16 is a diagram showing a first configuration example of the delay adjustment unit on the transmitting side and the delay adjustment unit on the receiving side. As shown in Figure 16, the delay adjustment unit includes a FIFO 601 and a phase adjustment unit 602. The FIFO (First in First out) 601 stores the input signals in the FIFO 601 and then outputs the signals that were input first. The delay adjustment unit can adjust the delay by changing the amount of signals stored in the FIFO 601. For example, the delay adjustment unit adjusts the delay by setting how many clock cycles of data to store in the FIFO 601 and operate it. Since the number of clock cycles is specified, the granularity of the delay adjustment in the FIFO 601 is one clock cycle of the clock that operates the FIFO 601.

[0101] For example, in the case of an OTU4 signal using a 350 MHz clock for the first clock, one clock cycle is 2.86 ns. When adjusting the delay, the delay can be adjusted without interrupting the signal by intentionally slightly shifting the frequency of the read clock to the FIFO 601 from the frequency of the write clock. If the read clock frequency is higher than the write clock frequency, the amount of signal stored in the FIFO 601 decreases, thus reducing the delay. Conversely, if the read clock frequency is lower than the write clock frequency, the amount of signal stored in the FIFO 601 increases, thus increasing the delay. The amount of frequency control is, for example, in the case of OTU4, the clock deviation is specified as ±20 ppm in the standard specification, so the frequency is changed within that range.

[0102] The phase adjustment unit 602 adjusts delays of less than one clock cycle. An example of the configuration of the phase adjustment unit 602 is the use of a phase shifter.

[0103] Here, using Figures 17 and 18, we will explain an example configuration and operation that allows delay adjustment without interrupting the signal. Figure 17 is a diagram showing an example of a FIFO adjustment configuration. As shown in Figure 17, the signal to be adjusted is input to the FIFO 601 as an input signal. In addition, a clock synchronized with the input signal is used as the write clock to the FIFO 601. The write clock is also input to the frequency adjustment unit 603. The frequency adjustment unit receives notification of the amount of delay from the delay control unit described above and performs the necessary frequency control.

[0104] Figure 18 shows examples of adjustments for increasing and decreasing the delay. Code g200 represents an example of adjustment for increasing the delay. Code g210 represents an example of adjustment for decreasing the delay. Graphs g201 and g211 show the change in the readout clock frequency with respect to time. The horizontal axis is time, and the vertical axis is frequency. Graphs g202 and g212 show the change in delay time ΔD (sec) with respect to time. The horizontal axis is time, and the vertical axis is delay time.

[0105] For example, to increase the delay, as shown in graphs g201 and g202, the read clock is reduced by -1 (ppm). This causes the amount of signal flowing into FIFO 601 to be greater than the amount flowing out of FIFO 601, thus increasing the amount of data stored in FIFO 601 and thus increasing the delay. Conversely, to decrease the delay, as shown in graphs g211 and g212, the read clock is increased by +1 (ppm). This causes the amount of signal flowing into FIFO 601 to be smaller than the amount flowing out of FIFO 601, thus decreasing the amount of data stored in FIFO 601 and thus decreasing the delay. Note that the clock frequency adjustment in the frequency adjustment unit 603 may be continuous or discontinuous.

[0106] As described above, by using the FIFO 601 which performs delay adjustment in units of one clock and the phase adjustment unit 602 which performs delay adjustment in units of less than one clock, it becomes possible to adjust the delay with an accuracy of less than one clock over a wide delay adjustment range that exceeds one clock.

[0107] Furthermore, the first communication device 2, the second communication device 3, and a portion of the delay control device 4 are configured using a processor such as a CPU (Central Processing Unit) and memory. The first communication device 2 and the second communication device 3 function, for example, as a main signal processing unit on the transmitting side, a delay adjustment unit on the transmitting side, a delay adjustment unit on the receiving side, a main signal processing unit on the receiving side, an insertion unit, a detection unit, and a measurement unit, when the processor executes a program. The delay control device 4 also functions, for example, as a correction unit and a delay control unit, when the processor executes a program. Furthermore, some of the functions of the first communication device 2, the second communication device 3, and the delay control device 4 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor memory devices (e.g., SSDs: Solid State Drives), as well as memory devices such as hard disks and semiconductor memory devices built into computer systems. The above program may be transmitted via a telecommunications line.

[0108] Figure 19 is a schematic diagram of an example hardware configuration of an information processing device applied to an embodiment. For example, some of the first communication devices (2, 2A, 2B, 2C), the second communication devices (3, 3B, 3C), and delay control devices (4, 4B) may be implemented by the information processing device 7, as shown in Figure 19, executing a program. The information processing device 7 includes, for example, a processor 701, a main memory 702, a communication interface 703, an auxiliary storage device 704, an input / output interface 705, and an internal bus 706. The processor 701, the main memory 702, the communication interface 703, the auxiliary storage device 704, and the input / output interface 705 are connected to each other so as to be able to communicate via the internal bus 706. The information processing device 7 may be applied to, for example, some of the first communication device 2, the second communication device 3, and the delay control device 4. In this case, for example, the CL signal receiving units (201, 201B, 305, 305B), CL signal transmitting units (208, 208B, 304, 304B), NW signal transmitting units (204, 204B, 308, 308B), and NW signal receiving units (205, 205B, 301, 301B) may be configured using a communication interface 703 or an input / output interface 705. Also, the delay adjustment units (203, 203B, 206, 206B, 223, 224, 302, 307, 322, 325) and measurement units (213, 229, 313, 329) of the first communication device (2, 2A, 2B, 2C) and the second communication device (3, 3B, 3C) may be configured using a processor 701, a main memory 702, and an auxiliary memory 704. Furthermore, the correction units (41, 43) and delay control units (42, 44) of the delay control device 4 may be configured using a processor 701, a main memory 702, and an auxiliary storage device 704.

[0109] As described above, in each embodiment, the measurement unit (213, 229) of the first communication device (2, 2A, 2B, 2C) measures a first measurement value, which represents the time required for the delay measurement signal transmitted from the first communication device (2, 2A, 2B, 2C) to be re-transferred by the second communication device (3, 3B, 3C) and returned to the first communication device (2, 2A, 2B, 2C), using a second clock different from the first clock used for processing the transmitted signal. Furthermore, in each embodiment, the measurement unit (313, 329) of the second communication device (3, 3B, 3C) measures a second measurement value, which represents the time required for the delay measurement signal to be re-transferred from the received signal to the transmitted signal in the second communication device (3, 3B, 3C), using a second clock. In each embodiment, the second clock is one of a group of clocks that have a higher frequency than the first clock, or the same frequency but different phases.

[0110] In the communication devices configured in this way (first communication device (2, 2A, 2B, 2C), second communication device (3, 3B, 3C)), the LED and RRD are measured using a second clock independent of the main signal, making it possible to measure the transmission delay of communication lines in service in a communication network with high accuracy. As a result, each embodiment and example allows for accurate measurement, which enables, for example, equalizing the delay of multiple communication lines to enable fair high-frequency financial transactions. Furthermore, each embodiment and example allows for accurate measurement, which enables, for example, equal-length wiring to be achieved by equalizing the delay of multiple communication lines connecting multiple computers, enabling efficient execution of real-time processing and other operations in cooperation with multiple computers.

[0111] Furthermore, in each embodiment, in addition to measurement, the delay adjustment unit (203, 203B, 206, 206B, 223, 224, 302, 307, 322, 224) adjusts the delay based on the measured delay amount. In the conventional technology, only delay measurement is possible, and there is no mechanism to adjust that delay. Therefore, in the conventional technology, it was not possible to freely control the delay.

[0112] In the communication devices configured in this way (first communication device (2, 2A, 2B, 2C), second communication device (3, 3B, 3C)), the delay can be freely controlled by using them in combination with a delay adjustment mechanism.

[0113] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention.

[0114] <Notes> (1) A communication device comprising a first clock unit, a second clock unit, an insertion unit, a detection unit, a measurement unit, a main signal processing unit (transmitter side), a main signal processing unit (receiver side), a CL signal receiving unit, a CL signal transmitting unit, an NW signal transmitting unit, and an NW signal receiving unit, wherein the first communication device measures Raw-Roundtrip-Delay (RRD) and the second communication device measures Loopback-Extra-Delay (LED). (2) A communication device in the manner of (1) above, further comprising a first clock unit and a second clock unit. (3) A communication device in the manner of (2) above, wherein the second clock unit uses multiple clocks (a group of clocks). (4) A communication device in the manner of (3) above, wherein when the second clock unit handles a group of clocks, it uses multiple clocks of the same frequency but different phases. (5) A communication device in the manner of (4) above, wherein when the second clock unit generates a group of clocks, it is equipped with a single clock source, a distributor, and a phase adjustment unit. (6) A communication device comprising a delay adjustment unit and a phase adjustment unit in any one of the embodiments of (1) to (5) above. (7) A communication device that dynamically adjusts the delay according to the delay measurement result in the embodiment of (6) above.

[0115] The present invention is applicable to transmitting devices that transmit transmission signals, receiving devices that receive transmission signals, transmission devices, transmission systems, and the like.

[0116] 1, 1A, 1B, 1C... Communication system, 2, 2A, 2B, 2C... First communication device, 3, 3B, 3C... Second communication device, 4, 4B... Delay control device, 41, 43... Correction unit, 42, 44... Delay control unit, 201, 305, 305B... CL signal receiving unit, 202, 207, 303, 306... Main signal processing unit, 203, 203B, 206, 206B, 223, 224, 302, 307, 322, 224... Delay adjustment unit, 204, 204B, 308, 308B... NW signal transmission unit, 20 5, 205B, 301, 301B...NW signal receiving unit, 208, 304, 304B...CL signal transmitting unit, 209, 209B, 310, 310B...First clock unit, 210, 311...Insertion unit, 211, 309...Detection unit, 212, 212B, 312, 312B...Second clock unit, 213, 313...Measurement unit, 221, 326...Multiplexing unit, 226, 321...Separation unit, 231, 331...Clock group generation unit, 2311-1 to 2311-N, 3311-1 to 3311-N...Clock １～Ｎ ,2131-1 to 2131-N, 3131-1 to 3131-N...time difference counting unit, 2312, 3312...clock generation unit, 2313, 3313...distribution unit, 2314, 3314...phase adjustment unit

Claims

1. A first communication device and a second communication device are connected to each other via a transmission line, the first communication device includes a measurement unit that measures a first measurement value representing the time required for a delay measurement signal transmitted from the first communication device to be re-transmitted by the second communication device and returned to the first communication device, using a second clock different from the first clock used for processing the transmitted signal, and the second communication device includes a measurement unit that measures a second measurement value representing the time required for the second communication device to re-transmit the delay measurement signal from the received signal to the transmitted signal, using the second clock, the communication device.

2. The communication device according to claim 1, wherein the second clock is one of a group of clocks comprising a plurality of clocks having a higher frequency than the frequency of the first clock, or having the same frequency but different phases.

3. The communication device according to claim 1 or claim 2, further comprising a delay adjustment unit that adjusts the amount of delay based on the result of subtracting the second measurement value from the first measurement value.

4. A communication control method for a first communication device and a second communication device connected to each other via a transmission line, wherein a measurement unit measures a first measurement value, which represents the time required for a delay measurement signal transmitted from the first communication device to be re-transmitted by the second communication device and returned to the first communication device, using a second clock different from a first clock used for processing the transmitted signal; and the measurement unit measures a second measurement value, which represents the time required for the second communication device to re-transmit the delay measurement signal from the received signal to the transmitted signal, using the second clock.

Images