Statistical value calculation device, propagation delay measurement system, statistical value calculation method, and statistical value calculation program

Abstract

The statistical value calculation device (100) includes a variation calculation unit (110). Assuming a model indicating that the variation in propagation delay, which is a delay occurring in a measurement target (400) that relays data in a wired network, is composed of a variation in variable delay, which is a delay that varies when the measurement target (400) is in continuous operation, and a variation in fixed delay, which is a delay that varies each time the measurement target (400) is started, and the measurement target (400) is started up multiple times and multiple propagation delays in the measurement target (400) in continuous operation are measured each time the measurement target (400) is started up, the variation calculation unit (110) measures the fixed delay based on the multiple propagation delays measured in the measurement target (400) in continuous operation for each start of the measurement target (400), and calculates the variation of the fixed delay based on the multiple measured fixed delays.

Description

[Technical field]

[0001] The present disclosure relates to a statistical value calculation device, Propagation Delay Measurement System, The present invention relates to a statistical value calculation method and a statistical value calculation program. [Background technology]

[0002] In FA (Factory Automation) networks, it is necessary to guarantee the time synchronization error throughout the network. One of the main causes of time synchronization error is the variation in propagation delay of communication stations and communication paths. The variation in propagation delay is the difference between the maximum value of the propagation delay and the minimum value of the propagation delay. Therefore, it is required to predict the variation in propagation delay in FA networks. Patent Document 1 discloses a technique for measuring the propagation delay of a measurement target that is in continuous operation multiple times and estimating the variation of the propagation delay from the variance of the multiple measured propagation delays. Note that, in conventional techniques including Patent Document 1, the propagation delay of a measurement target that is in continuous operation is generally measured. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-022918 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an FA network, the variation in propagation delay in the measurement target is considered to be composed of the variation in fixed delay and the variation in variable delay. Here, the fixed delay is a delay whose value varies every time the measurement target is started. The variable delay is a delay whose value varies within a certain range regardless of the timing of the measurement target's start-up. Here, the conventional technology has a problem in that the variation in the fixed delay is not taken into consideration when evaluating the variation in the propagation delay. An object of the present disclosure is to take into account the variation in fixed delay when evaluating the variation in propagation delay in a measurement target in an FA network. [Means for solving the problem]

[0005] The statistical value calculation device according to the present disclosure includes: Assuming a propagation delay model showing the variation in propagation delay, which is a delay that occurs in a measurement object that relays data in a wired network, and a model showing that the variation in the propagation delay is composed of a variable delay variation, which is a delay that varies when the measurement object is in continuous operation, and a fixed delay variation, which is a delay that varies each time the measurement object is started, and when the measurement object is started multiple times and multiple propagation delays are measured in the measurement object that is in continuous operation each time the measurement object is started, measuring a target fixed delay based on a plurality of propagation delays measured in the target during continuous operation, for each start of the target, A variation calculation unit that calculates the variation of the fixed delay based on a plurality of measured target fixed delays. Equipped with. Effect of the Invention

[0006] According to the present disclosure, the variation calculation unit measures a fixed delay based on a plurality of propagation delays measured in a measurement target that is in continuous operation, and calculates the variation of the fixed delay based on the plurality of measured fixed delays. Here, the measurement target may be a device that constitutes an FA network. Furthermore, when evaluating the variation of the propagation delay, the variation of the calculated fixed delay may be taken into consideration. Therefore, according to the present disclosure, when evaluating the variation of the propagation delay in the measurement target in the FA network, the variation of the fixed delay can be taken into consideration. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the configuration of a propagation delay measurement system 90 according to a first embodiment. [Diagram 2] FIG. 4 is a diagram for explaining a propagation delay according to the first embodiment. [Diagram 3] 1 is a diagram showing an example of a hardware configuration of a statistical value calculation device 100 according to a first embodiment. [Figure 4] 4 is a flowchart showing the operation of the propagation delay measurement system 90 according to the first embodiment. [Diagram 5] FIG. 13 is a diagram showing an example of a hardware configuration of a statistical value calculation device 100 according to a modification of the first embodiment. [Figure 6] 10 is a flowchart showing the operation of a propagation delay measurement system 90 according to the second embodiment. [Figure 7] 10 is a flowchart showing the operation of a propagation delay measurement system 90 according to a modification of the second embodiment. [Figure 8] 10 is a flowchart showing the operation of a propagation delay measurement system 90 according to the third embodiment. [Figure 9] 10 is a flowchart showing the operation of a propagation delay measurement system 90 according to the fourth embodiment. [Figure 10] FIG. 13 is a diagram showing an example of the configuration of a propagation delay measurement system 90 according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the description of the embodiments and the drawings, the same elements and corresponding elements are given the same reference numerals. Descriptions of elements given the same reference numerals are omitted or simplified as appropriate. Arrows in the drawings primarily indicate data flow or processing flow. In addition, "part" may be read as "circuit," "step," "procedure," "processing," or "circuitry" as appropriate.

[0009] Embodiment 1 Hereinafter, the present embodiment will be described in detail with reference to the drawings.

[0010] ***Configuration Description*** Fig. 1 shows an example of the configuration of a propagation delay measurement system 90 according to this embodiment. As shown in Fig. 1, the propagation delay measurement system 90 includes a statistical value calculation device 100, a delay measurement device 200, a frame transmitter 300, a measurement target 400, and a frame receiver 500. The statistical value calculation device 100 and the delay measurement device 200 may be configured integrally. The frame transmitter 300, the measurement target 400, and the frame receiver 500 may be components of a Factory Automation (FA) network. The frame transmitter 300 and the object to be measured 400, and the object to be measured 400 and the frame receiver 500 are connected by a wired network. A specific example of the wired network is a network that complies with the Ethernet (registered trademark) standard.

[0011] Delay measurement device 200 notifies statistical value calculation device 100 of the difference between the reception time at frame receiver 500 and the transmission time at frame transmitter 300 as the propagation delay. Delay measurement device 200 measures the propagation delay based on the difference between the time when frame transmitter 300 transmits a target frame and the time when frame receiver 500 receives the target frame. A frame transmitter 300 repeatedly transmits frames addressed to a frame receiver 500 in a wired network, and also notifies a delay measurement device 200 of the frame transmission time. The object under test 400 corresponds to a repeater that repeats data in a wired network, and repeats frames between a frame transmitter 300 and a frame receiver 500. A propagation delay occurs in the object under test 400. Frame receiver 500 receives frames transmitted by frame transmitter 300 in a wired network, and notifies delay measurement device 200 of the frame reception time.

[0012] Propagation delay is a delay that occurs in communication via a wired network. As a specific example, propagation delay is used to correct time synchronization errors in an FA network. In the propagation delay measurement system 90 shown in FIG. 1, the propagation delay is the difference between the time when the frame transmitter 300 transmits a target frame and the time when the frame receiver 500 receives the target frame. As a specific example, the propagation delay is measured by using delay measurement device 200 to calculate the difference between the time when the frame transmitter 300 transmits a target frame and the time when the frame receiver 500 receives the target frame that has passed through measurement target 400. Note that the term "propagation delay" can also refer to data indicating the propagation delay. Here, in the conventional technology, the propagation delay when the continuously operating measurement target 400 repeatedly transfers frames is measured, and the value of the propagation delay variation is predicted by estimating the distribution of the propagation delay based on the measurement results. Therefore, the conventional technology cannot measure a fixed delay. In this embodiment, a propagation delay model is assumed as a model showing the variation in propagation delay. The propagation delay model is a model showing that the variation in propagation delay is composed of the variation in variable delay and the variation in fixed delay. The variable delay is a delay that varies when the measurement target 400 is continuously operating. The fixed delay is a delay that varies every time the measurement target 400 is started up.

[0013] As shown in FIG. 1, the statistical value calculation device 100 includes a variation calculation section 110 and a communication section 120.

[0014] When the measurement target 400 is started up multiple times and multiple propagation delays in the measurement target 400 in continuous operation are measured each time the measurement target 400 is started up, the variation calculation unit 110 measures the fixed delay based on the multiple propagation delays measured in the measurement target 400 in continuous operation as the target fixed delay each time the measurement target 400 is started up. Thereafter, the variation calculation unit 110 calculates the variation of the fixed delay based on the multiple measured target fixed delays. As a process of measuring the fixed delay, the variation calculation unit 110 may execute a process of calculating an average value of all the multiple propagation delays measured in the measurement target 400 in continuous operation. In addition, the variation calculation unit 110 measures the variable delay based on the multiple propagation delays measured in the measurement target 400 in continuous operation, and calculates the variation of the variable delay based on the measurement result of the variable delay. The variation calculation unit 110 calculates the variation of the propagation delay based on the calculated variation of the fixed delay and the calculated variation of the variable delay. The process executed by the variation calculation unit 110 will be specifically described below. When the measurement target 400 is continuously operating, the variation calculation unit 110 receives a plurality of propagation delays from the delay measurement device 200 via the communication unit 120, and executes a delay measurement process based on the received plurality of propagation delays. The delay measurement process includes a process of measuring the distribution of propagation delays as a distribution of variable delays based on the plurality of propagation delays, and a process of calculating the average value of all the plurality of propagation delays as a fixed delay. The average value may be a value calculated based on any definition. Note that the variation calculation unit 110 may execute a process of calculating each of the maximum and minimum values ​​of the variable delay as a process of measuring the distribution of the variable delay. In this case, as a specific example, the variation calculation unit 110 updates the maximum value of the variable delay when the maximum value of the variable delay calculated from the received plurality of propagation delays is larger than the maximum value of the variable delay at the time of execution of the delay measurement process, and updates the minimum value of the variable delay when the minimum value of the variable delay calculated from the received plurality of propagation delays is smaller than the minimum value of the variable delay at the time of execution of the delay measurement process. Note that the variable delay may take a negative value. Furthermore, the variation calculating section 110 may execute the delay measurement process using a propagation delay stored in a database or the like in which the propagation delay measured by the delay measuring device 200 is stored. Furthermore, in order to measure the distribution of the fixed delay, the measurement target 400 is restarted multiple times. The variation calculating section 110 executes the delay measurement process every time the measurement target 400 is restarted. When restarting the measurement target 400, in addition to the measurement target 400, at least one of the delay measurement device 200, the frame transmitter 300, the measurement target 400, and the frame receiver 500 may be restarted. Then, the variation calculation unit 110 measures the distribution of the fixed delay based on the multiple fixed delays calculated by executing the delay measurement process multiple times.The variation calculation unit 110 then determines the sum of the variation obtained from the distribution of the variable delay and the variation obtained from the distribution of the fixed delay as the variation of the propagation delay.Note that, as a process of measuring the distribution of the fixed delay, the variation calculation unit 110 may execute a process of calculating each of the maximum and minimum values ​​of the fixed delay, similar to the process of measuring the distribution of the variable delay. Here, the propagation delay variance is expressed by [Formula 1]. In [Formula 1], "variance of variable delay" refers to the variance obtained from the distribution of variable delay. "variance of fixed delay" refers to the variance obtained from the distribution of fixed delay. As a specific example, the "variation of the variable delay" is the maximum value of the range of the variable delay or a value estimated as the maximum value of the range of the variable delay. The range of the variable delay is the difference between the minimum value of the variable delay and the maximum value of the variable delay. The "variation of the fixed delay" is, for example, a range of the observed fixed delay or a value estimated as the range of the fixed delay. The range of the fixed delay is the difference between the minimum value of the fixed delay and the maximum value of the fixed delay. In addition, each of the minimum value of the variable delay, the maximum value of the variable delay, the minimum value of the fixed delay, and the maximum value of the fixed delay may be an actually observed value, may be a value estimated from an actually observed value, or may be a value theoretically calculated based on the properties or specifications of the object to be measured 400.

[0015] [Formula 1] (Propagation Delay Variation) = (Variable Delay Variation) + (Fixed Delay Variation)

[0016] FIG. 2 is a table explaining the variation in propagation delay using a specific example of the measurement result of the propagation delay. This example shows the measurement result when the measurement target 400 is started six times. In the table shown in FIG. 2, the "Maximum value [ns]" column indicates the maximum value of the propagation delay in ns units when the measurement target 400 is continuously operating, and the "Minimum value [ns]" column indicates the minimum value of the propagation delay in ns units when the measurement target 400 is continuously operating. In addition, the "Average value [ns]" column indicates the average value of the entire observed propagation delay (i.e., fixed delay) in ns units, and the "Maximum value - Minimum value [ns]" column indicates the difference between the value in the "Maximum value [ns]" column and the value in the "Minimum value [ns]" column (i.e., the range of variable delay) in ns units. In this example, the maximum value of the fixed delay is 640 ns, and the minimum value of the fixed delay is 620 ns, so the variation of the fixed delay is 20 ns. Also, the maximum value of the width of the variable delay is 35 ns, so the variation of the variable delay is 35 ns. Therefore, in this example, the variation calculation unit 110 calculates 55 ns (= 35 ns + 20 ns) as the variation of the propagation delay using [Formula 1]. In this example, the maximum propagation delay is 655 ns shown in (A), and the minimum propagation delay is 605 ns shown in (B). Therefore, since the actually observed propagation delay variation is 50 ns (=655 ns-605 ns), it is considered that the variation calculation unit 110 can calculate a reasonable propagation delay variation using [Formula 1].

[0017] The communication section 120 communicates with the delay measurement device 200 .

[0018] 3 shows an example of a hardware configuration of the statistical value calculation device 100 according to this embodiment. The statistical value calculation device 100 is made up of a computer. The statistical value calculation device 100 may be made up of multiple computers.

[0019] As shown in the figure, the statistical value calculation device 100 is a computer including hardware such as a processor 11, a memory 12, an auxiliary storage device 13, an input / output IF (Interface) 14, and a communication device 15. These pieces of hardware are appropriately connected via signal lines 19.

[0020] The processor 11 is an integrated circuit (IC) that performs arithmetic processing and controls the hardware of the computer. Specific examples of the processor 11 include a central processing unit (CPU), a digital signal processor (DSP), and a graphics processing unit (GPU). The statistical value calculation device 100 may include a plurality of processors that replace the processor 11. The plurality of processors share the role of the processor 11.

[0021] The memory 12 is typically a volatile storage device, and a specific example is a RAM (Random Access Memory). The memory 12 is also called a primary storage device or a main memory. Data stored in the memory 12 is saved in the secondary storage device 13 as necessary.

[0022] The auxiliary storage device 13 is typically a non-volatile storage device, and specific examples thereof include a ROM (Read Only Memory), an HDD (Hard Disk Drive), or a flash memory. Data stored in the auxiliary storage device 13 is loaded into the memory 12 as necessary. The memory 12 and the auxiliary storage device 13 may be integrated into one unit.

[0023] The input / output IF 14 is a port to which an input device and an output device are connected. A specific example of the input / output IF 14 is a Universal Serial Bus (USB) terminal. Specific examples of the input device are a keyboard and a mouse. A specific example of the output device is a display.

[0024] The communication device 15 is a receiver and a transmitter, and is, for example, a communication chip or a network interface card (NIC).

[0025] Each unit of the statistical value calculation device 100 may use the input / output IF 14 and the communication device 15 as appropriate when communicating with other devices.

[0026] The auxiliary storage device 13 stores a statistical value calculation program. The statistical value calculation program is a program that causes a computer to realize the functions of each unit included in the statistical value calculation device 100. The statistical value calculation program is loaded into the memory 12 and executed by the processor 11. The functions of each unit included in the statistical value calculation device 100 are realized by software.

[0027] Data used when executing the statistical value calculation program and data obtained by executing the statistical value calculation program are appropriately stored in the storage device. Each unit of the statistical value calculation device 100 appropriately uses the storage device. As a specific example, the storage device is composed of at least one of the memory 12, the auxiliary storage device 13, the register in the processor 11, and the cache memory in the processor 11. The storage device may be independent of the computer. The functions of the memory 12 and the auxiliary storage device 13 may be realized by other storage devices.

[0028] The statistical value calculation program may be recorded in a computer-readable non-volatile recording medium. Specific examples of the non-volatile recording medium include an optical disk and a flash memory. The statistical value calculation program may be provided as a program product.

[0029] ***Explanation of Operation*** The operation procedure of the statistical value calculation device 100 corresponds to a statistical value calculation method. Also, a program that realizes the operation of the statistical value calculation device 100 corresponds to a statistical value calculation program.

[0030] 4 is a flowchart showing an example of the operation of the propagation delay measurement system 90. The operation of the propagation delay measurement system 90 will be described with reference to FIG.

[0031] (Step S101) The variation calculation section 110 measures the distribution of propagation delays in the continuously operating target object 400 as a distribution of variable delays, and calculates an average value M1 as a fixed delay. The average value M1 is the average value of all propagation delays in the continuously operating target object 400, and corresponds to the fixed delay.

[0032] (Step S102) If the number of average values ​​M1 calculated in step S101 is sufficient to obtain a distribution of fixed delays, step S104 is performed, otherwise step S103 is performed.

[0033] (Step S103) The measurement target 400 is restarted.

[0034] (Step S104) The variation calculation unit 110 calculates the variation of the propagation delay by [Formula 1]. That is, the variation calculation unit 110 determines the sum of the variation of the variable delay obtained from the distribution of the measured variable delay and the variation of the fixed delay obtained from the distribution of the obtained fixed delay as the variation of the propagation delay.

[0035] ***Explanation of the Effects of the First Embodiment*** As described above, according to this embodiment, the variation in propagation delay is calculated based on the variation in variable delay and the variation in fixed delay, so that the variation in propagation delay that may occur in the object to be measured 400 can be calculated more accurately.

[0036] ***Other configurations*** <Variation 1> FIG. 5 shows an example of the hardware configuration of the statistical value calculation device 100 according to this modification. The statistical value calculation device 100 includes a processing circuit 18 in place of the processor 11 , the processor 11 and memory 12 , the processor 11 and auxiliary storage device 13 , or the processor 11 , memory 12 , and auxiliary storage device 13 . The processing circuit 18 is hardware that realizes at least a part of each unit included in the statistical value calculation device 100. The processing circuitry 18 may be dedicated hardware, or may be a processor that executes programs stored in the memory 12 .

[0037] When processing circuitry 18 is dedicated hardware, processing circuitry 18 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The statistical value calculation device 100 may include a plurality of processing circuits that replace the processing circuit 18. The plurality of processing circuits share the role of the processing circuit 18.

[0038] In the statistical value calculation device 100, some of the functions may be realized by dedicated hardware, and the remaining functions may be realized by software or firmware.

[0039] Processing circuitry 18 is illustratively implemented in hardware, software, firmware, or a combination thereof. The processor 11, memory 12, auxiliary storage device 13, and processing circuit 18 are collectively referred to as the “processing circuitry.” In other words, the functions of the functional components of the statistical value calculation device 100 are realized by the processing circuitry. The statistical value calculation devices 100 according to other embodiments may also have the same configuration as this modified example.

[0040] Embodiment 2 The following mainly describes the differences from the above-described embodiment with reference to the drawings. In this embodiment, the variation in variable delay and the variation in fixed delay are calculated from the maximum and minimum values ​​obtained by measuring the propagation delay a predetermined number of times.

[0041] ***Configuration Description*** The configuration of the propagation delay measurement system 90 according to this embodiment is similar to the configuration of the propagation delay measurement system 90 according to the first embodiment. The variation calculation section 110 according to this embodiment calculates the maximum and minimum values ​​of the fixed delay based on the measurement result of the fixed delay, and calculates the variation of the fixed delay based on the calculated maximum and minimum values ​​of the fixed delay. Also, the variation calculation section 110 calculates the maximum and minimum values ​​of the variable delay based on the measurement result of the variable delay, and calculates the variation of the variable delay based on the calculated maximum and minimum values ​​of the variable delay. The target of measurement 400 according to this embodiment is restarted a first measurement number of times. In addition, the propagation delay of the target of measurement 400 in continuous operation is measured a second measurement number of times.

[0042] Specifically, when the measurement target 400 is continuously operating, and the propagation delay is notified N1 times (N1 is a natural number), the variation calculation unit 110 records the average value M1 of the entire notified propagation delay, and the maximum value MAX1 and minimum value MIN1 calculated from the notified propagation delay. Then, the measurement target 400 is restarted. After this cycle is repeated N2 times (N2 is a natural number), the variation calculation unit 110 records the maximum value MAX2 and minimum value MIN2 of the sample, using the recorded average value M1 as a sample. Using these results, the variation of the propagation delay is calculated by [Formula 2]. Here, each of N1 and N2 indicates the number of measurements, and may be determined in any way. The value of N1 corresponds to the first number of measurements. The value of N2 corresponds to the second number of measurements. The value of N1 and the value of N2 may be different from each other. The average value M1 indicates the average value of the entire propagation delay observed in the measurement target 400 that is continuously operating. The maximum value MAX1 indicates the maximum value in the entire variable delay observed in the continuously operating test object 400. The minimum value MIN1 indicates the minimum value in the entire variable delay observed in the continuously operating test object 400. The maximum value MAX2 indicates the maximum value in the entire calculated average value M1. The minimum value MIN2 indicates the minimum value in the entire calculated average value M1. (Maximum value MAX2 - minimum value MIN2) indicates the variation in fixed delay. (Maximum value MAX1 - minimum value MIN1) indicates the variation in variable delay.

[0043] [Formula 2] (Propagation delay variation) = Maximum value MAX2 - Minimum value MIN2 + Maximum value MAX1 - Minimum value MIN1

[0044] ***Explanation of Operation*** 6 is a flowchart showing an example of the operation of the propagation delay measurement system 90. The operation of the propagation delay measurement system 90 will be described with reference to FIG.

[0045] (Step S111) Step S112 is executed if the variation calculator 110 has received N1 propagation delays after starting up the system under test 400. Otherwise, step S111 is repeatedly executed.

[0046] (Step S112) The variation calculation section 110 calculates an average value M1, a maximum value MAX1, and a minimum value MIN1 from the received N1 propagation delays, and records the calculated average value M1, maximum value MAX1, and minimum value MIN1.

[0047] (Step S113) If the variation calculation section 110 has recorded the N2 average values ​​M1, step S114 is executed, otherwise step S103 is executed.

[0048] (Step S114) The variation calculation section 110 calculates a maximum value MAX2 and a minimum value MIN2 based on the recorded N2 average values ​​M1, and records the calculated maximum value MAX2 and minimum value MIN2. Thereafter, the variation calculation section 110 calculates the variation in the propagation delay according to [Formula 2] using the recorded maximum value MAX2, minimum value MIN2, maximum value MAX1, and minimum value MIN1.

[0049] ***Explanation of the Effects of the Second Embodiment*** As described above, according to this embodiment, even a simple statistical value calculation device 100 that cannot calculate a standard deviation can calculate the variation in propagation delay in the object to be measured 400. Furthermore, by restarting only the measurement target 400, the fixed delay of the measurement error becomes constant, that is, the fixed delay of the measurement error contained in the maximum value MAX2 and the minimum value MIN2 coincide. Therefore, by taking the difference between the maximum value MAX2 and the minimum value MIN2, the fixed delay of the measurement error can be offset, making it possible to more accurately estimate the variation in the propagation delay. The measurement error is an error contained in the propagation delay, and is an error caused by the measurement equipment. The measurement equipment is equipment for measuring the propagation delay, and is specifically composed of delay measurement equipment 200, frame transmitter 300, and frame receiver 500.

[0050] ***Other configurations*** <Variation 2> In this modification, the first measurement count and the second measurement count are each determined according to a target measurement error of the propagation delay variation. For N1 and N2, when N measurement values ​​are measured, the standard deviation of a sample consisting of the measured measurement values ​​is ((N-1) / N)^0.5 times the standard deviation in the population, and the difference between the maximum and minimum values ​​is also expected to be ((N-1) / N)^0.5 times the difference in the population. Here, the standard deviation in the population corresponds to a theoretical value. Therefore, in this modification, when the target error of the propagation delay variation is ±M% (where M≧0), the values ​​of N1 and N2 are each set to a value of N that satisfies [Formula 3]. Note that when i significant digits (i is a natural number) are required, the values ​​of N1 and N2 are each set to a value of N that satisfies [Formula 4].

[0051] [Formula 3] ((N-1) / N)^0.5≧1-M / 100 [Formula 4] ((N-1) / N)^0.5>1-0.5*10^(1-i)

[0052] 7 is a flowchart showing an example of the operation of the propagation delay measurement system 90 according to this modified example. The operation of the propagation delay measurement system 90 will be described with reference to FIG.

[0053] (Step S121) When M % is input as the target error of the variation in the propagation delay, the variation calculation section 110 sets each of the values ​​of N1 and N2 to a value of N that satisfies [Formula 3].

[0054] According to this modification, it is expected that the variation in propagation delay that satisfies the target error of M % can be calculated.

[0055] Embodiment 3 The following mainly describes the differences from the above-described embodiment with reference to the drawings. This embodiment corresponds to an application example of the second embodiment.

[0056] ***Configuration Description*** The configuration of the propagation delay measurement system 90 according to this embodiment is similar to the configuration of the propagation delay measurement system 90 according to the first embodiment. The variation calculating section 110 according to this embodiment calculates the standard deviation as a first standard deviation based on the measurement result of the variable delay when the target for measurement 400 is continuously operating. When the first standard deviation converges with the first precision, the target for measurement 400 is restarted. Furthermore, the variation calculating section 110 calculates the standard deviation as a second standard deviation based on the measurement result of the fixed delay, and calculates the variation of the fixed delay when the calculated second standard deviation converges with the second precision. Each of the first precision and the second precision may be determined in any manner. Specifically, the variation calculation unit 110 measures the standard deviation S1 each time the variable delay is measured, and measures the standard deviation S2 each time the fixed delay is measured. The standard deviation S1 corresponds to the variation of the variable delay and corresponds to the first standard deviation. The standard deviation S2 corresponds to the variation of the fixed delay and corresponds to the second standard deviation. When the standard deviation S1 and the standard deviation S2 each converge with the required accuracy, the variation calculation unit 110 determines that the error of each of the standard deviations S1 and S2 with respect to the standard deviation in the population may be ignored, and ends the measurement regardless of the values ​​of N1 and N2. Here, the standard deviation S1 is the standard deviation of the variable delay. The standard deviation S2 is the standard deviation of the fixed delay. The required accuracy may be determined in any way. The required accuracy corresponding to the standard deviation S1 and the required accuracy corresponding to the standard deviation S2 may be different from each other.

[0057] ***Explanation of Operation*** 8 is a flowchart showing an example of the operation of the propagation delay measurement system 90 according to this embodiment. The operation of the propagation delay measurement system 90 will be described with reference to FIG.

[0058] (Step S131) The variation calculation section 110 calculates the standard deviation S1 using all the propagation delays received after the system under test 400 is started up.

[0059] (Step S132) If the standard deviation S1 has converged with the required accuracy, step S112 is executed, otherwise step S131 is executed.

[0060] (Step S133) The variation calculation section 110 calculates the standard deviation S2 using all the recorded average values ​​M1.

[0061] (Step S134) If the standard deviation S2 has converged with the required accuracy, step S114 is executed, otherwise step S103 is executed.

[0062] ***Explanation of the Effects of the Third Embodiment*** According to this embodiment, it is expected that the variation in propagation delay that satisfies a predetermined target accuracy can be calculated.

[0063] Embodiment 4 The following mainly describes the differences from the above-described embodiment with reference to the drawings. This embodiment is an example in which the variation in propagation delay is calculated based on a theoretical standard deviation in the case where the distribution of the propagation delay can be predicted.

[0064] ***Configuration Description*** The configuration of the propagation delay measurement system 90 according to this embodiment is similar to the configuration of the propagation delay measurement system 90 according to the first embodiment. The variation calculation section 110 according to the present embodiment calculates the standard deviation as the third standard deviation based on the measurement result of the variable delay, calculates the standard deviation as the fourth standard deviation based on the measurement result of the fixed delay, and calculates the variation of the propagation delay based on the calculated third standard deviation and the calculated fourth standard deviation. At this time, as a specific example, the variation calculation section 110 calculates the variation of the propagation delay based on the third standard deviation and a distribution that the variable delay is considered to follow. Also, the variation calculation section 110 calculates the variation of the propagation delay based on the fourth standard deviation and a distribution that the fixed delay is considered to follow. As a specific example, the distribution that each of the variable delay and the fixed delay is considered to follow is a uniform distribution or a normal distribution. The standard deviation S1 according to the present embodiment corresponds to the third standard deviation. The standard deviation S2 according to the present embodiment corresponds to the fourth standard deviation. Specifically, when the distribution of the propagation delay can be predicted, the variation calculation unit 110 may calculate the variation of the propagation delay using the measured standard deviations S1 and S2. As a specific example, in a synchronous circuit using a general clock, most of the variation of the propagation delay is caused by clock transfer. Therefore, the distribution of the propagation delay is expected to be a uniform distribution or a superposition of uniform distributions. Here, the standard deviation of the uniform distribution is as shown in [Formula 5]. In addition, when each of the standard deviations S1 and S2 converges with the required accuracy, each of the standard deviations S1 and S2 is considered to be sufficiently close to the theoretical value. If each of the standard deviations S1 and S2 is sufficiently close to the theoretical value, then from [Formula 5], each of the variation of the variable delay and the variation of the fixed delay in the population is as shown in [Formula 6]. In addition, considering that the distribution spreads symmetrically on both sides of the average value in the uniform distribution, each of the maximum value of the propagation delay and the minimum value of the propagation delay is as shown in [Formula 7]. Therefore, when each of the distribution of the variable delay and the distribution of the fixed delay is a uniform distribution, the variation of the propagation delay is as shown in [Formula 8]. Here, the average value M2 indicates the average value in the distribution of the propagation delay. The variation calculating section 110 may calculate each of the maximum and minimum propagation delay values ​​by [Formula 9], where Max(...) indicates the maximum value in the brackets, and Min(...) indicates the minimum value in the brackets.

[0065] [Formula 5] (Standard deviation of uniform distribution) = ((maximum value) - (minimum value)) / 2√3 [Formula 6] (Maximum value of delay variation)-(Minimum value of delay variation)=Standard deviation S1*2√3 (Maximum fixed delay)-(Minimum fixed delay)=Standard deviation S2*2√3 [Formula 7] (Maximum propagation delay) = Mean value M2 + Standard deviation S1*√3 + Standard deviation S2*√3 (Minimum propagation delay) = Mean value M2 - Standard deviation S1*√3 - Standard deviation S2*√3 [Formula 8] (Propagation delay variation) = (maximum propagation delay) - (minimum propagation delay) =(Standard deviation S1+Standard deviation S2)×2√3 [Formula 9] (Maximum value of propagation delay) = Average value M2 + Max (Maximum value MAX1 - Average value M1) + Max (Maximum value MAX2 - Average value M2) = Maximum value MAX2 + Max (Maximum value MAX1 - Average value M1) (Minimum value of propagation delay) = Average value M2 + Min (Minimum value MIN1 - Average value M1) + Min (Minimum value MIN2 - Average value M2) =Minimum value MIN2 + Min (Minimum value MIN1 - Average value M1)

[0066] ***Explanation of Operation*** 9 is a flowchart showing an example of the operation of the propagation delay measurement system 90 according to this embodiment. The operation of the propagation delay measurement system 90 will be described with reference to FIG.

[0067] (Step S141) The variation calculation section 110 records the calculated standard deviation S1.

[0068] (Step S142) The variation calculation section 110 uses the calculated standard deviations S1 and S2 to calculate the variation in the propagation delay according to [Formula 8].

[0069] ***Explanation of the effect of the fourth embodiment*** According to this embodiment, it is expected that the variation in propagation delay can be calculated with higher accuracy than when the variation in propagation delay is calculated using maximum and minimum values ​​based on the measurement results.

[0070] ***Other configurations*** <Variation 3> In the fourth embodiment, it may be assumed that only the fixed delay or only the variable delay follows a uniform distribution. When it is assumed that only the fixed delay follows a uniform distribution, the maximum value of the propagation delay and the minimum value of the propagation delay are as shown in [Formula 10]. When it is assumed that only the variable delay follows a uniform distribution, the maximum value of the propagation delay and the minimum value of the propagation delay are as shown in [Formula 11]. The variation calculating section 110 according to this modification calculates the variation in propagation delay based on [Formula 10] or [Formula 11].

[0071] [Formula 10] (Maximum value of propagation delay) = Average value M2 + Max (Maximum value MAX1 - Average value M1) + Standard deviation S2 * √3 (Minimum value of propagation delay) = Mean value M2 + Min (Minimum value MIN1 - Mean value M1) - Standard deviation S2 * √3 [Formula 11] (Maximum value of propagation delay) = Average value M2 + Standard deviation S1 * √3 + Max (Maximum value MAX2 - Average value M2) = Maximum value MAX2 + Standard deviation S1*√3 (Minimum value of propagation delay) = Mean value M2 - Standard deviation S1 * √3 + Min (Minimum value MIN2 - Mean value M2) = Minimum value MIN2 - Standard deviation S1*√3

[0072] Embodiment 5. The following mainly describes the differences from the above-described embodiment. This embodiment is an example in which the variation in propagation delay is calculated based on a theoretical standard deviation when the distribution of the propagation delay cannot be predicted.

[0073] ***Configuration Description*** The configuration of the propagation delay measurement system 90 according to this embodiment is similar to the configuration of the propagation delay measurement system 90 according to the first embodiment. The variation calculation unit 110 according to this embodiment assumes that the distribution that the fixed delay is expected to follow is a normal distribution, and that the distribution that the variable delay is expected to follow is a normal distribution. Specifically, when the distribution of the propagation delay cannot be predicted, the variation calculation unit 110 assumes a normal distribution as the distribution of the propagation delay as a specific example, and calculates the variation of the propagation delay using a standard normal distribution table. Here, it is necessary to be in a state where there is a high possibility that a variable delay equal to or less than the minimum value MIN1 and a variable delay equal to or more than the maximum value MAX1 will not occur in the communication performed by the measurement target 400 in its lifetime. That is, as shown in [Formula 12-1], the sum of the probability that a variable delay equal to or less than the minimum value MIN1 will occur in one communication and the probability that a variable delay equal to or more than the maximum value MAX1 will occur in one communication, multiplied by the number of communications performed by the measurement target 400 in its lifetime, must be 0.5 times or less. Here, due to the symmetry of the normal distribution, (the probability that a variable delay equal to or more than the maximum value MAX1 will occur) is the same as (the probability that a variable delay equal to or less than the minimum value MIN1 will occur). Therefore, [Formula 12-1] is substantially the same as [Formula 12-2]. Moreover, [Formula 12-2] is transformed to [Formula 13]. The variation calculation unit 110 calculates the minimum value MIN1 by substituting the average value M1 and the standard deviation S1 into the cumulative distribution function that satisfies [Formula 13] and solving it. Thereafter, the variation calculation section 110 calculates the maximum value MAX1 by [Formula 17]. [Formula 16] holds when the variable delay and the fixed delay each follow a normal distribution. [Formula 16] can be transformed to [Formula 17]. As with the variable delay, the fixed delay must be in a state in which there is a high probability that a fixed delay equal to or less than the minimum value MIN2 and a fixed delay equal to or more than the maximum value MAX2 will not occur. For this reason, [Formula 14] must be satisfied. [Formula 14] can be transformed to [Formula 15]. The variance calculation unit 110 calculates the minimum value MIN2 by substituting the mean value M3 and the standard deviation S2 into a cumulative distribution function that satisfies [Formula 15] and solving the result. Thereafter, the variance calculation unit 110 calculates the maximum value MAX2 using [Formula 17]. Here, the mean value M3 indicates the mean value of the entire fixed delay. The values ​​substituted into the cumulative distribution function may be calculated in any manner.

[0074] [Formula 12-1] {(Probability of occurrence of a variable delay equal to or less than the minimum value MIN1) + (Probability of occurrence of a variable delay equal to or more than the maximum value MAX1)} * (Number of communications performed by the measurement target 400 in its lifetime) ≦ 0.5 [Formula 12-2] (Probability of occurrence of a variable delay that is equal to or less than the minimum value MIN1) * (Number of communications performed by the measurement target 400 in its lifetime) * 2 ≦ 0.5 [Formula 13] (Probability of occurrence of a variable delay less than or equal to the minimum value MIN1) ≦ 0.5 / (number of communications performed by the measurement target 400 in its lifetime) / 2 [Formula 14] (Probability of occurrence of a fixed delay equal to or less than the minimum value MIN2) * (Number of times the measurement target 400 starts up in its lifetime) * 2 ≦ 0.5 [Formula 15] (Probability of occurrence of a fixed delay less than or equal to the minimum value MIN2) ≦ 0.5 / (Number of times that the measurement target 400 starts up in its lifetime) / 2 [Formula 16] Average value M1 = (maximum value MAX1 + minimum value MIN1) / 2 Average value M3 = (maximum value MAX2 + minimum value MIN2) / 2 [Formula 17] Maximum value MAX1 = 2 * average value M1 - minimum value MIN1 Maximum value MAX2 = 2 * average value M3 - minimum value MIN2

[0075] The variation calculation section 110 calculates the maximum and minimum values ​​corresponding to the variable delay and the maximum and minimum values ​​corresponding to the fixed delay as described above, and then calculates the variation in the propagation delay using [Equation 18].

[0076] [Formula 18] (Propagation delay variation) = (difference between maximum and minimum values ​​corresponding to variable delay) + (difference between maximum and minimum values ​​corresponding to fixed delay)

[0077] ***Explanation of Operation*** The operation of the propagation delay measurement system 90 according to this embodiment is similar to the operation of the propagation delay measurement system 90 according to embodiment 4. The differences between this embodiment and embodiment 4 will be described below.

[0078] (Step S142) The variation calculation unit 110 calculates the variation in the propagation delay using [Formula 18].

[0079] ***Explanation of the effect of the fifth embodiment*** According to this embodiment, it is expected that the variation in propagation delay can be calculated with higher accuracy than when the variation in propagation delay is calculated using maximum and minimum values ​​based on the measurement results.

[0080] Embodiment 6 The following mainly describes the differences from the above-described embodiment with reference to the drawings.

[0081] ***Configuration Description*** In this embodiment, as the propagation delay measurement system, a propagation delay measurement system 90 according to the first embodiment and a propagation delay measurement system 91 are used. The term “propagation delay measurement system” is a general term for the propagation delay measurement system 90 and the propagation delay measurement system 91. As shown in FIG. 10, the propagation delay measurement system 91 includes a statistical value calculation device 100, a delay measurement device 200, a frame transmitter 300, and a frame receiver 500. Propagation delay measurement system 90 is also referred to as a first system, and propagation delay measurement system 91 is also referred to as a second system. As a propagation delay model showing the variation in propagation delay in the first system, a model showing that the variation in propagation delay in the first system is composed of a variation in a first variable delay and a variation in a first fixed delay is assumed. The first variable delay is a delay that varies when all the components of the first system are continuously operating. The first fixed delay is a delay that varies every time all the components of the first system are started up. As a propagation delay model showing the variation in propagation delay in the second system, a model showing that the variation in propagation delay in the second system is composed of the variation in the second variable delay and the variation in the second fixed delay is assumed. The second variable delay is a delay that varies when all the components of the second system are operating continuously. The second fixed delay is a delay that varies every time all the components of the second system are started up.

[0082] In the case where the start-up of all the components of the first system is executed multiple times and multiple propagation delays in the first system in continuous operation are measured each time the start-up of all the components of the first system is executed, the variation calculation section 110 according to this embodiment measures a first fixed delay based on the multiple propagation delays measured in the first system for each start-up of all the components of the first system. Also, the variation calculation section 110 measures a first variable delay based on the multiple propagation delays measured in the first system in continuous operation. After that, the variation calculation section 110 calculates a first fixed standard deviation, which is a standard deviation, based on the measurement result of the first fixed delay, and calculates a first variable standard deviation, which is a standard deviation, based on the measurement result of the first variable delay. Furthermore, when the start-up of all the components of the second system is executed multiple times and multiple propagation delays in the second system in continuous operation are measured each time the start-up of all the components of the second system is executed, the variation calculation unit 110 measures the second fixed delay based on the multiple propagation delays measured in the second system for each start-up of all the components of the second system. Furthermore, the variation calculation unit 110 measures the second variable delay based on the multiple propagation delays measured in the second system in continuous operation. Thereafter, the variation calculation unit 110 calculates a second fixed standard deviation that is a standard deviation based on the measurement result of the second fixed delay, and calculates a second variable standard deviation that is a standard deviation based on the measurement result of the second variable delay. Then, the variation calculating section 110 calculates a third standard deviation based on the first varying standard deviation and the second varying standard deviation, and calculates a fourth standard deviation based on the first fixed standard deviation and the second fixed standard deviation.

[0083] In this embodiment, the entire components of the propagation delay measurement system are restarted to measure the fixed delay. In this embodiment, in order to remove the measurement error of the measurement equipment and calculate the variation in the propagation delay in the object of measurement 400, the standard deviation is measured in each of the propagation delay measurement system 90 and the propagation delay measurement system 91, and then the additivity of the variance is used to calculate the variation in the propagation delay in the object of measurement 400. Specifically, the variation calculation section 110 calculates the standard deviation using [Formula 19], and calculates the variation in the propagation delay in the object of measurement 400 using the calculated standard deviation. Here, the "configuration with the object of measurement 400" corresponds to the propagation delay measurement system 90, and the "configuration without the object of measurement 400" corresponds to the propagation delay measurement system 91. It should be noted that variation calculating section 110 may calculate an average value of the delay according to [Formula 20], and calculate the variation in the propagation delay in object to be measured 400 using the calculated average value.

[0084] [Formula 19] (Standard deviation) = {(Standard deviation in a configuration with 400 measurement targets)^2 -(Standard deviation in a configuration without 400 measurement targets)^2}^0.5 [Formula 20] (Average value) = (average value in a configuration with the measurement target 400) - (average value in a configuration without the measurement target 400)

[0085] ***Explanation of Operation*** The operation of the propagation delay measurement system 90 according to this embodiment is similar to the operation of the propagation delay measurement system 90 according to embodiment 4. The differences between this embodiment and embodiment 4 will be described below.

[0086] (Step S103) All components of the propagation delay measurement system are restarted.

[0087] (Step S142) This step is executed when the standard deviations S1 and S2 in the propagation delay measurement system 90 have converged with the required accuracy, and when the standard deviations S1 and S2 in the propagation delay measurement system 91 have converged with the required accuracy. The variation calculating section 110 calculates the standard deviations S1 and S2 corresponding to the object of measurement 400 according to [Formula 19] using the standard deviations S1 and S2 in the propagation delay measurement system 90 and the standard deviations S1 and S2 in the propagation delay measurement system 91. Thereafter, the variation calculating section 110 calculates the variation in the propagation delay in the object of measurement 400 according to the method shown in the fourth or fifth embodiment, using the calculated standard deviations S1 and S2 corresponding to the object of measurement 400.

[0088] ***Explanation of the effect of the sixth embodiment*** According to this embodiment, it is expected that the variation in propagation delay can be calculated with higher accuracy than when the variation in propagation delay is calculated using maximum and minimum values ​​based on the measurement results.

[0089] ***Other embodiments*** The above-described embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted. Moreover, the embodiments are not limited to those shown in the first to sixth embodiments, and various modifications are possible as necessary. The procedures explained using the flowcharts and the like may be modified as appropriate. [Explanation of symbols]

[0090] 11 processor, 12 memory, 13 auxiliary storage device, 14 input / output IF, 15 communication device, 18 processing circuit, 19 signal line, 90, 91 propagation delay measurement system, 100 statistical value calculation device, 110 variation calculation unit, 120 communication unit, 200 delay measurement device, 300 frame transmitter, 400 measurement target, 500 frame receiver.

Claims

1. A statistical value calculation device for calculating a variance in propagation delay occurring in a measurement target that relays data, comprising: Calculating a fixed delay that varies each time the measurement target is activated based on a plurality of measured propagation delays each time the measurement target is activated; A variation calculation unit that calculates a variation in the fixed delay based on a plurality of fixed delays calculated at a plurality of startups. A statistical value calculation device comprising:

2. The statistical value calculation device according to claim 1 , wherein the variation calculation section determines, as the fixed delay, an average value of a plurality of propagation delays measured during continuous operation of the measurement target.

3. 3. The statistical value calculation device according to claim 1 or 2, wherein the variation calculation unit calculates a variable delay that varies when the object to be measured is operating continuously and a variation of the variable delay based on a plurality of propagation delays measured during continuous operation of the object to be measured, and calculates the variation of the propagation delay based on the variation of the fixed delay and the variation of the variable delay.

4. 4. The statistical value calculation device according to claim 3, wherein the variation calculation unit calculates maximum and minimum values ​​of the fixed delay based on a calculation result of the fixed delay, calculates the variation of the fixed delay based on the calculated maximum and minimum values ​​of the fixed delay, calculates maximum and minimum values ​​of the variable delay based on the calculation result of the variable delay, and calculates the variation of the variable delay based on the calculated maximum and minimum values ​​of the variable delay.

5. 3. The statistical value calculation device according to claim 1, wherein the measurement target is restarted a first measurement number of times, and a propagation delay is measured in the measurement target during continuous operation a second measurement number of times.

6. 6. The statistical value calculation device according to claim 5, wherein each of the first measurement count and the second measurement count is determined according to a target measurement error of the variation in the propagation delay.

7. The variation calculation unit calculates a standard deviation as a first standard deviation based on a calculation result of the variation delay when the measurement target is continuously operating, When the first standard deviation has converged with a first accuracy, the measurement object is restarted; 4. The statistical value calculation device according to claim 3, wherein the variation calculation unit calculates a standard deviation as a second standard deviation based on a calculation result of the fixed delay, and when the calculated second standard deviation converges with a second precision, calculates the variation of the propagation delay using the maximum and minimum values ​​of the fixed delay and the variable delay.

8. 8. The statistical value calculation device according to claim 7, wherein the variation calculation unit calculates a standard deviation as a third standard deviation based on a calculation result of the variable delay, calculates a standard deviation as a fourth standard deviation based on a calculation result of the fixed delay, and calculates the variation of the propagation delay based on the calculated third standard deviation and the calculated fourth standard deviation.

9. The variation calculation unit is calculating a variation in the propagation delay based on the third standard deviation and a distribution that the variable delay is expected to follow; 9. The statistical value calculation device according to claim 8, further comprising: a calculation unit for calculating the variation in the propagation delay based on the fourth standard deviation and a distribution that the fixed delay is considered to follow.

10. The statistical value calculation device according to claim 9 , wherein the variance calculation section determines a distribution which the fixed delay is likely to follow as a normal distribution, and determines a distribution which the variable delay is likely to follow as a normal distribution.

11. A propagation delay measurement system comprising two statistical value calculation devices according to claim 8, A propagation delay measurement system in which the variation calculation unit calculates the third standard deviation based on the two first standard deviations calculated by the two statistical value calculation devices, and calculates the fourth standard deviation based on the two second standard deviations calculated by the two statistical value calculation devices.

12. A method for calculating a statistical value of a propagation delay variance occurring in a measurement target that relays data, comprising: The computer calculates a fixed delay that varies each time the measurement target is activated based on the measured propagation delays each time the measurement target is activated; The computer calculates a variance in the fixed delay based on a plurality of fixed delays calculated during a plurality of startups.

13. A statistical value calculation program for calculating a variation in propagation delay occurring in a measurement target that relays data, comprising: Calculating a fixed delay that varies each time the measurement target is activated based on a plurality of measured propagation delays each time the measurement target is activated; A variation calculation process for calculating a variation in the fixed delay based on a plurality of fixed delays calculated at a plurality of startups. A statistical value calculation program that causes a statistical value calculation device, which is a computer, to execute the above.

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