WO2023142939A1

WO2023142939A1 - Consistency test method and related apparatus

Info

Publication number: WO2023142939A1
Application number: PCT/CN2023/070628
Authority: WO
Inventors: 林友熙; 郑建宇; 陈健; 张乐伟
Original assignee: 华为技术有限公司
Priority date: 2022-01-27
Filing date: 2023-01-05
Publication date: 2023-08-03
Also published as: CN116566481A

Abstract

Disclosed in the present application are a consistency test method and a related apparatus, which are used for a consistency test of an optical transmitter and an optical receiver in a high-signal-rate scenario. The method of the present application comprises: collecting a signal sequence of optical signals, which are received by an optical receiver, wherein the optical signals are generated by means of an optical transmitter modulating a test sequence by using 4-level pulse amplitude modulation; acquiring the test sequence; performing equalization compensation on the signal sequence according to the test sequence; synthesizing a test eye diagram according to an equalization coefficient of the signal sequence that is obtained by means of the equalization compensation; calculating the value of a test parameter according to the test eye diagram and a noise enhancement coefficient corresponding to the equalization compensation; and if the value of the test parameter is less than or equal to a first threshold value, then determining that a consistency test of the optical signals is passed. By means of the method, an acceptable additional noise margin in a system can be increased, the numerical precision of a test TDECQ can be improved, and the test performance can be optimized.

Description

Conformance testing method and related device

This application claims the priority of the Chinese patent application with the application number 202210101984.7 and the title of the invention "Consistency Test Method and Related Devices" filed with the China Patent Office on January 27, 2022, the entire contents of which are hereby incorporated by reference in this application .

technical field

The embodiments of the present application relate to communication technologies, and in particular, to a conformance testing method and related devices.

Background technique

Physical layer devices in a data center network (DCN) include components such as transmitters, optical fibers, and receivers. In order to ensure that various devices provided by different manufacturers are compatible and interoperable, it is usually necessary to define the conformance test parameters and methods of the above devices in the standard, so as to maximize the integration of industry chain resources. At present, the optical port rate required by the data center is increasing rapidly, and has evolved from 25 gigabit (G) non-return-to-zero (NRZ) to 100G/lane four-level pulse amplitude modulation (4-level pulse amplitude modulation, PAM4), and will continue to evolve to 200G/lane in the future.

Currently, the IEEE 802.3 Ethernet standard uses transmitter and dispersion eye closure quaternary (TDECQ) as a conformance test parameter for 50G/lane optical ports and 100G/lane optical ports, and uses a feedforward equalizer (feed-forward equalizer, FFE) is a reference equalizer for conformance testing, where the value of TDECQ is calculated based on the acceptable additional noise in the system.

However, as the transmission rate continues to increase, in high signal rate scenarios, the signal-to-noise ratio decreases, and the acceptable additional noise margin in the system decreases. The value of TDECQ calculated according to the original conformance test scheme increases, and the test accuracy is greatly reduced. , test performance degrades. Therefore, how to determine whether the optical signal emitted by the transmitter can meet the use requirements of the receiver in the high signal rate scenario (hereinafter referred to as the conformance test of the optical transmitter) is an urgent problem to be solved.

Contents of the invention

The present application provides a conformance testing method and related devices, which are used to solve the problem of how to determine whether the optical signal transmitted by the transmitter can meet the use requirements of the receiver in a high signal rate scenario.

The first aspect of the present application provides a conformance testing method, which is characterized in that the method includes: collecting the signal sequence of the optical signal received by the optical receiver, and the optical signal is transmitted by the optical transmitter using a four-level pulse amplitude The modulation mode modulation test sequence is generated; the test sequence is obtained; the signal sequence is equalized and compensated according to the test sequence; the equalization coefficient of the signal sequence obtained according to the equalization compensation is used to synthesize the test eye diagram; according to the test The eye diagram and the noise enhancement coefficient corresponding to the equalization compensation calculate the value of the test parameter; if the value of the test parameter is less than or equal to the first threshold, it is determined that the conformance test of the optical signal is passed.

The consistency test method provided by this application uses a known test sequence to perform equalization compensation on the collected signal sequence, synthesizes a test eye diagram based on the equalization coefficient of the equalization compensation, and updates the noise enhancement coefficient based on the test eye diagram and the equalization compensation The value of the test parameter is calculated, and it is judged whether the consistency test of the optical signal passes according to whether the value of the test parameter is less than or equal to the threshold. Using a known test sequence to perform equalization compensation on the collected signal sequence can improve the equalization compensation effect, increase the acceptable additional noise margin of the system, improve the numerical accuracy of the TDECQ test, optimize the test performance, and meet the needs of optical transmitters in high signal rate scenarios. conformance testing requirements.

In a possible implementation manner of the first aspect, if the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, the optical signal consistency test passes indicating the consistency of the optical transmitter The test passes.

In the conformance test method provided by the present application, if the optical signal is transmitted by the optical transmitter when the relative intensity noise is the largest, it can be determined that the optical receiver uses In this equalization method, whether the conformance test of the optical transmitter adopting the PAM4 mode passes.

In a possible implementation manner of the first aspect, the method further includes: calculating the number of consecutive bit errors according to the test eye diagram and the signal sequence; if the value of the test parameter is less than or equal to The first threshold, then determining that the conformance test of the optical signal has passed includes: if the value of the test parameter is less than or equal to the first threshold, and the number of consecutive bit errors is less than or equal to the second threshold, then determining the The consistency test of the optical signal is passed.

The consistency test method provided by this application can also judge the number of consecutive bit errors in the system in order to accurately evaluate whether the consistency test of the optical signal is passed. When the number of consecutive bit errors is less than or equal to the second threshold, the It is judged whether the value of the test parameter is less than or equal to the first threshold, and if the two conditions are met, it is judged that the consistency test of the optical signal has passed, which further improves the accuracy of the implementation of the scheme.

In a possible implementation manner of the first aspect, the equalizing and compensating the signal sequence according to the test sequence includes: performing feedforward adaptive equalization on the signal sequence to obtain a first equalized signal sequence and a first an equalization coefficient; performing feed-forward adaptive equalization on the first equalized signal sequence according to the test sequence to obtain a second equalization coefficient.

In the consistency test method provided by this application, the equalization compensation includes feedforward adaptive equalization, and the newly added equalization compensation for the first equalized signal sequence obtained by the feedforward adaptive equalization according to the test sequence, the first equalization coefficient and the second equalization coefficient The two equalization coefficients are used to synthesize test eye diagrams. This equalization compensation step improves the equalization compensation effect, thereby improving the acceptable additional noise margin of the system, improving the accuracy of test parameters, and optimizing test performance.

In a possible implementation manner of the first aspect, an equalization coefficient of the signal sequence is determined according to the first equalization coefficient and the second equalization coefficient; and the test eye diagram is synthesized according to the equalization coefficient of the signal sequence.

The consistency testing method provided by the present application obtains the equalization system of the signal sequence based on the first equalization coefficient and the second equalization coefficient, and is used for synthesizing the eye pattern, thereby improving the equalization effect.

In a possible implementation manner of the first aspect, calculating the value of the test parameter according to the test eye diagram and the noise enhancement coefficient corresponding to the equalization compensation includes: according to the test eye diagram and the noise enhancement coefficient, determining the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate; according to the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate, Determine the value of the test parameter.

The consistency test method provided by this application, when calculating the value of the test parameter, can first determine the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached, and then further determine the value of the test parameter, A specific implementation method for obtaining test parameter values is provided, which enhances the realizability of the scheme.

In a possible implementation manner of the first aspect, according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached, determining the value of the test parameter includes:

Calculate the test parameter T according to the following formula:

in,

OMA is the optical modulation amplitude of the test eye pattern, Qt is the Q value of the test sequence waveform, σ _G is the standard deviation of the maximum additive noise, σ _s is the standard deviation of the optical receiver noise, Ceq Be the noise enhancement coefficient, N (f) is a noise density function, Heq (f) is the frequency response function of the first equalization coefficient, G (f) is the frequency response function of the second equalization coefficient, satisfying Heq (0)=G(0)=1.

The consistency test method provided by this application provides specific calculation formulas for test parameters. It is worth noting that, compared with the calculation formulas of the existing consistency test, the calculation formula of the noise enhancement coefficient in this scheme takes into account the change of the equalization unit There are also adaptive improvements, which make the overall calculation process of this scheme self-consistent and easy to implement.

In a possible implementation manner of the first aspect, the length of the signal sequence is greater than or equal to the length of the test sequence; performing equalization compensation on the signal sequence according to the test sequence includes: according to the test sequence , performing sequence alignment on the signal sequence, and performing the equalization compensation on the sequence-aligned signal sequence.

In the consistency test method provided by this application, before synthesizing the test eye diagram, it is necessary to perform sequence alignment on the signal sequence, and perform equalization compensation on the sequence-aligned signal sequence according to the test sequence, which enhances the feasibility of the solution.

The second aspect of the present application provides a conformance test device, including: a collection unit, used to collect the signal sequence of the optical signal received by the optical receiver, the optical signal is modulated by the optical transmitter using four-level pulse amplitude PAM4 Mode modulation test sequence generation; acquisition unit, used to obtain the test sequence; processing unit, used to perform equalization compensation on the signal sequence according to the test sequence, and obtain the equalization of the signal sequence according to the equalization compensation The coefficient synthesis test eye diagram; the calculation unit is used to calculate the value of the test parameter according to the noise enhancement coefficient corresponding to the test eye diagram and the equalization compensation; the determination unit is used for when the value of the test parameter is less than or When it is equal to the first threshold, it is determined that the consistency test of the optical signal passes.

In a possible implementation manner of the second aspect, if the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, the optical signal consistency test passes indicating the consistency of the optical transmitter The test passes.

In a possible implementation manner of the second aspect, the calculation unit is further configured to: calculate the number of consecutive bit errors according to the test eye diagram and the signal sequence; the determination unit is specifically configured to: in the When the value of the test parameter is less than or equal to the first threshold and the number of consecutive bit errors is less than or equal to the second threshold, it is determined that the consistency test of the optical signal is passed.

In a possible implementation manner of the second aspect, the processing unit is specifically configured to: perform feedforward adaptive equalization on the signal sequence to obtain a first equalized signal sequence and a first equalization coefficient; The first equalized signal sequence is subjected to feedforward adaptive equalization to obtain second equalization coefficients.

In a possible implementation manner of the second aspect, the processing unit is specifically configured to: determine the equalization coefficient of the signal sequence according to the first equalization coefficient and the second equalization coefficient; coefficients to synthesize the test eye diagram.

In a possible implementation manner of the second aspect, the calculation unit is specifically configured to: determine the maximum BER that the optical transmitter can support when reaching the target bit error rate according to the test eye diagram and the noise enhancement coefficient. The standard deviation of additive noise; according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached, the value of the test parameter is determined.

In a possible implementation manner of the second aspect, the calculation unit is specifically configured to: calculate the test parameter T according to the following formula:

in,

OMA is the optical modulation amplitude of the test eye diagram, Qt is the Q value of the test sequence waveform, σ _G is the standard deviation of the maximum additive noise, σ _S is the standard deviation of the optical receiver noise, Ceq Be the noise enhancement coefficient, N (f) is a noise density function, Heq (f) is the frequency response function of the first equalization coefficient, G (f) is the frequency response function of the second equalization coefficient, satisfying Heq (0)=G(0)=1.

In a possible implementation manner of the second aspect, the length of the signal sequence is greater than or equal to the length of the test sequence; the processing unit is specifically configured to perform sequence alignment on the signal sequence according to the test sequence , performing the equalization compensation on the signal sequence after sequence alignment.

The third aspect of the present application provides a conformance testing device, which is characterized in that it includes: one or more processors and memory; wherein, computer-readable instructions are stored in the memory; the one or more processors Reading the computer-readable instructions enables the conformance testing device to execute the method described in any one of the above-mentioned first aspect and various possible implementation manners.

The fourth aspect of the present application provides a computer program product containing instructions, which is characterized in that, when it is run on a computer, the computer executes the program described in any one of the above-mentioned first aspect and various possible implementation manners. described method.

The fifth aspect of the present application provides a computer-readable storage medium, including instructions, which is characterized in that, when the instructions are run on the computer, the computer executes any one of the above-mentioned first aspect and various possible implementation manners. method described in the item.

The sixth aspect of the present application provides a chip, including a processor. The processor is used to read and execute the computer program stored in the memory, so as to execute the method in any possible implementation manner of any aspect above. Optionally, the chip includes a memory, and the memory and the processor are connected to the memory through a circuit or wires. Further optionally, the chip further includes a communication interface, and the processor is connected to the communication interface. The communication interface is used to receive data and/or information to be processed, and the processor obtains the data and/or information from the communication interface, processes the data and/or information, and outputs the processing result through the communication interface. The communication interface may be an input-output interface.

Wherein, the technical effect brought by any one of the second, third, fourth, fifth, or sixth aspects can refer to the technical effect brought by the corresponding implementation in the first aspect, here I won't repeat them here.

The present application provides a conformance testing method, device and storage medium, which are used to solve the problem of how to determine whether the optical signal transmitted by the transmitter can meet the use requirements of the receiver in a high signal rate scenario. The method performs equalization compensation on the collected signal sequence through the test sequence, which can improve the equalization compensation effect, increase the acceptable additional noise margin of the system, improve the numerical accuracy of the test TDECQ, and optimize the test performance.

Description of drawings

Fig. 1 is a schematic diagram of a conformance testing system;

Fig. 2 is a schematic diagram of a test eye diagram;

Fig. 3 is a structural schematic diagram of a reference equalizer;

FIG. 4 is a schematic diagram of the system architecture of the conformance testing system in the embodiment of the present application;

FIG. 5 is another schematic diagram of the system architecture of the conformance testing system in the embodiment of the present application;

FIG. 6 is a schematic flow chart of a consistency testing method provided in an embodiment of the present application;

FIG. 7 is a schematic diagram of a reference equalizer provided in an embodiment of the present application;

FIG. 8 is a schematic flowchart of another consistency testing method provided in the embodiment of the present application;

FIG. 9 is a schematic diagram of an embodiment of a consistency testing method provided in an embodiment of the present application;

FIG. 10 is a schematic diagram of a system architecture of a receiving end in an embodiment of the present application;

FIG. 11 is a schematic diagram of a calculation process of a receiving end in an embodiment of the present application;

FIG. 12 is a schematic structural diagram of a conformance testing device provided in an embodiment of the present application;

FIG. 13 is a schematic structural diagram of another conformance testing device provided in an embodiment of the present application.

Detailed ways

Embodiments of the present application provide a conformance testing method and a related device, which are used to solve the problem of how to determine whether the optical signal transmitted by the transmitter can meet the use requirements of the receiver in a high signal rate scenario.

For ease of understanding, the following briefly introduces some technical terms involved in the embodiments of this application:

1. Transmitter and dispersion eye closure (TDEC)

It is a measure of the loss of signal power margin after an optical transmitter passes through a typical optical channel. After the optical signal is transmitted over a certain distance, the transmission delay of different wavelength components in the signal will change due to the dispersion effect. These signals with different transmission delays are superimposed at the optical receiver, which will cause degradation of signal quality and decrease the sensitivity of the optical receiver.

In the 10G Ethernet IEEE 802.3ae standard, this indicator is defined as transmitter dispersion penalty (transmitter and dispersion penalty, TDP); in the 100G Ethernet IEEE 802.3bm standard, this indicator is defined as TDEC; and for 200G/400G Ethernet In the IEEE 802.3bs standard, the indicator is TDECQ.

2. TDECQ

Used to characterize the predicted system performance of a PAM4 transmitter. It calculates the bit error rate of the transmitted waveform after passing through the worst-case channel and equalizing with a standard reference receiver. It is used to indicate at the transmitter, how much noise can be superimposed compared to the ideal signal, and at the same time meet the target bit error rate, the unit is dB.

3. Feedforward equalizer (FFE)

FFE is a commonly used linear equalizer that corrects voltage levels by removing the effects of intersymbol interference. In the conformance test, due to the complexity of the PAM4 signal itself, it is necessary to use an equalizer at the signal receiving end to open the eye diagram. In the test of TDECQ, a reference equalizer (reference equalizer) is required. The reference equalizer specified in the existing standard It is a FFE equalizer with 5 taps (tap)/T interval (spaced). In order to adapt to single sampling, T is defined as the reciprocal of the signal baud rate, that is, 1/fs, fs is the baud rate of the signal/waveform, equalized The specific equalization coefficients of the filter need to be determined according to the input signal by an adaptive algorithm.

4. Conformance test

Also known as interoperability testing, in order to ensure that various devices provided by different manufacturers are compatible and interoperable, it is usually necessary to define device conformance test parameters and methods in standards, so as to maximize the integration of industry chain resources. The consistency test method in this application is a method for testing an optical transmitter based on a standard reference receiver.

Embodiments of the present application are described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Those of ordinary skill in the art know that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

The terms "first", "second" and the like in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or modules is not necessarily limited to the expressly listed Instead, other steps or modules not explicitly listed or inherent to the process, method, product or apparatus may be included. The naming or numbering of the steps in this application does not mean that the steps in the method flow must be executed in the time/logic sequence indicated by the naming or numbering. The execution order of the technical purpose is changed, as long as the same or similar technical effect can be achieved.

In order to facilitate the understanding of the embodiments of the present application, the current test system is described and introduced below. FIG. 1 is a schematic diagram of a conformance testing system. As shown in Figure 1, the test system can include:

Optical transmitter, optical fiber, O/E converter, clock recovery unit (CRU), oscilloscope, and reference equalizer. Wherein, the optical transmitter is located at the sending end, and the receiving end is a standard reference receiver, including: a photoelectric converter, a clock recovery unit and an oscilloscope. The test system is used to implement the TDECQ calculation method including the reference equalizer.

The optical transmitter transmits an optical signal, and the optical signal is transmitted to the receiving end through an optical fiber. Optionally, the optical signal sent by the transmitter can also be transmitted to the receiving end through the polarization rotator through the optical fiber. Therefore, through this test system, the consistency of the optical signal sent by the optical transmitter under different relative intensity noises can be tested .

The optical-to-electrical converter, the clock recovery unit and the reference equalizer are used to simulate the behavior of an optical receiver (that is, an optical receiver that receives optical signals in an equalized manner). Among them, the photoelectric converter is used to convert the received optical signal into an electrical signal. The clock recovery unit is used to extract the clock of the optical signal. The oscilloscope is used to collect the waveform of the electrical signal processed by the photoelectric converter in the form of sequence according to the clock extracted by the clock recovery unit. A reference equalizer, including an analysis software module, for equalizing the acquired sequence. Through the collected electrical signal sequence or the compensated electrical signal sequence, optical parameters such as optical modulation amplitude (optical modulation amplitude, OMA) and average optical power of the optical signal emitted by the optical transmitter can be calculated.

It should be noted that the above-mentioned photoelectric converter, clock recovery unit and reference equalizer may exist independently of the oscilloscope, or may be integrated in the oscilloscope. The photoelectric converter, clock recovery unit and reference equalizer in the test system shown in Figure 1 all exist independently of the oscilloscope.

When determining whether the optical signal emitted by the optical transmitter satisfies the use requirements of the optical receiver, the optical signal emitted by the optical transmitter can be collected by the above test system first. Specifically: the tester turns on the optical transmitter, and loads a test signal sequence (that is, a test sequence) of a preset waveform into the optical transmitter. The test sequence mentioned here may be a sequence with a fixed length. The sequence is random enough to simulate the data transmitted in a real transmission scenario.

The optical transmitter uses PAM4 to modulate the test sequence to generate an optical signal, and sends the optical signal to the optical link. Testers can rotate the polarization rotator to change the polarization direction of the optical signal according to the test requirements. Then, the oscilloscope at the receiving end can collect the signal sequence in the received optical signal. Since the length of the test sequence is fixed, according to the length of the test sequence, the complete waveform (ie, the signal sequence) of the test sequence can be collected from the optical signal by an oscilloscope. After the signal sequence in the optical signal is collected by the oscilloscope, the signal sequence can be processed and analyzed to determine whether the optical signal emitted by the optical transmitter to be tested can meet the requirements of the standard reference receiver, thereby judging the optical emission. Whether the conformance test of the machine passes.

The completely collected signal sequence is processed by the reference equalizer to synthesize the test eye diagram, as shown in Figure 2, the test eye diagram includes eight sampling windows, and the histogram probability distribution statistics are performed according to the data in the sampling window. As shown in FIG. 3, FIG. 3 is a schematic structural diagram of a reference equalizer, and the reference equalizer is a 5 tap/T spaced FFE equalizer. The test eye diagram is used to obtain the value of OMA, calculate the noise enhancement coefficient, and further calculate the value of TDECQ to judge the performance of the optical transmitter.

With the continuous improvement of the transmission rate, in the high signal rate scenario, the signal-to-noise ratio decreases, and the acceptable additional noise margin in the system decreases. The value of TDECQ calculated according to the original conformance test scheme increases, and the test accuracy is greatly reduced. Performance degradation. How to determine whether the optical signal emitted by the transmitter can meet the needs of the receiver in the high signal rate scenario is an urgent problem to be solved.

Considering the above problems, the embodiment of the present application provides a conformance testing method, which can test the optical signal transmitted by the transmitter in a high signal rate scenario, so as to determine whether the optical signal can meet the use requirements of the receiver.

In the system architecture of the conformance testing method provided by the embodiment of the present application, compared with the existing testing architecture, the reference equalizer is mainly improved, and the reference equalizer can use a known test sequence to equalize and compensate the collected signal sequence. Since sequence equalization is adopted in this method, that is, the receiving end knows the test sequence modulated by the optical transmitter using PAM4 mode, and performs equalization processing according to the known test sequence. Please refer to Figure 4 and Figure 5, which are system architecture diagrams of the consistency testing system in the embodiment of the present application. Compared with the system shown in Figure 1, the consistency testing system of the present application adds a sequence storage unit at the receiving end, the The sequence storage unit is used to store known test sequences, and send the test sequences to the oscilloscope for sequence alignment and equalization. Optionally, the sequence storage unit receives the test sequence sent by the sending end (as shown in FIG. 4 ), or, the sequence storage unit sends the test sequence to the sending end (as shown in FIG. 5 ).

Based on the system architecture of the conformance testing system shown in FIG. 4 and FIG. 5 , an embodiment of the present application provides a conformance testing method, and the execution subject of the method is a conformance testing device. The conformance testing device may specifically be a processing device with a processing function, for example, a computer, a server, etc. independent of the test system, or an oscilloscope in the test system. When the conformance test device is a processing device independent of the test system, the above-mentioned reference equalizer may exist independently in the test system, or may be integrated in an oscilloscope of the test system, or may be integrated in the processing device.

It should be noted that, when the above-mentioned reference equalizer is integrated in a processing device (for example, a processing device independent of the test system, or an oscilloscope in the test system), the above-mentioned reference equalizer can be implemented by means of hardware and/or software accomplish. For example, the above-mentioned reference equalizer can be realized by constructing a reference equalizer model in a processing device. Specifically, there is no limitation here.

Referring to FIG. 6, a consistency testing method provided in the embodiment of the present application will be introduced below. The method includes steps 601-606.

601. Collect a signal sequence of an optical signal received by an optical receiver.

The optical signal is an optical signal generated by modulating the test sequence by the optical transmitter in a PAM4 manner, and the optical signal is transmitted to the receiving end through an optical link.

602. Acquire a test sequence.

The consistency testing device acquires the test sequence and stores it in the sequence storage unit. It should be noted that the sequence storage unit may be an independent device or a part of the consistency testing device, which is not limited here. Optionally, the consistency testing device receives the test sequence sent by the sending end; or, the receiving end sends the test sequence stored in the sequence storage unit to the sending end, which is not limited here.

The test sequence is used for the optical transmitter to modulate the test sequence in a PAM4 manner to generate an optical signal, and transmit the optical signal to the receiving end through an optical link.

Optionally, after acquiring the test sequence and the collected signal sequence, the consistency testing device may perform sequence alignment on the signal sequence according to the test sequence, and the sequence-aligned signal sequence is used for subsequent equalization compensation.

603. Perform equalization compensation on the signal sequence according to the test sequence.

The consistency testing device performs equalization compensation on the signal sequence through a reference equalizer, specifically, performs equalization compensation through a known test sequence.

In a possible implementation method, the conformance testing device performs feedforward adaptive equalization on the signal sequence to obtain the first equalized signal sequence and the first equalization coefficient; performs feedforward on the first equalized signal sequence according to the test sequence Adaptive equalization to obtain a second equalization coefficient. Then, the consistency testing device determines the equalization coefficient of the signal sequence according to the first equalization coefficient and the second equalization coefficient.

Specifically, as shown in FIG. 7 , the reference equalizer includes two parts (part A and part B), wherein part A is a feed-forward equalizer FFE. Part B is the feed-forward adaptive equalizer that uses the test sequence and the first equalized signal sequence output by FFE as input. Its structure is the same as that of FFE. The difference is that the test sequence and the first equalized signal sequence are input. Known test sequences can be used for data judgment, and a function similar to decision feedback equalizer (DFE) can be realized.

It should be noted that compared with the existing DFE, part B of the reference equalization provided by this application removes the feedback branch, avoids the complicated decision process and the error caused by the decision algorithm, and can retain the noise of the original transmitter , effectively retaining the noise characteristics of the equalized receiver.

In the application method, the output sequence Y(n) equalized by the reference equalizer can be expressed as:

Y(n)＝∑c _i ×x_in_syn(i)+∑d _i ×Pattern(i)

x_in_syn(i) is the feedforward adaptive equalization signal sequence (i.e. the first equalization signal sequence), Pattern(i) is a known test sequence, and c _i and d _i are coefficients determined by the convergence of the adaptive algorithm, which can make Signal sequence Y(n) has the highest signal-to-noise ratio. It can be obtained from the above formula that Y(n) can be described by a specific linear formula on the premise of retaining the noise.

604. Synthesize a test eye diagram according to the equalization coefficients of the signal sequence obtained through equalization compensation.

Specifically, reference may be made to the prior art for the process of synthesizing the test eye diagram by the conformance testing device according to the equalization coefficients, which will not be repeated here.

605. Calculate the value of the test parameter according to the test eye diagram and the noise enhancement coefficient corresponding to the equalization compensation.

In one embodiment, the conformance testing device determines the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate according to the test eye diagram and the noise enhancement coefficient corresponding to the equalization compensation in step 603;

According to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached, the values of the test parameters are determined. The calculation formula of the test parameter T is as follows:

in,

OMA is the optical modulation amplitude of the test eye diagram, Qt is the Q value of the test sequence waveform, σ _G is the standard deviation of the maximum additive noise, σ _S is the standard deviation of the optical receiver noise, Ceq is the noise enhancement coefficient, N(f ) is the noise density function, Heq(f) is the frequency response function of the first equalization coefficient, G(f) is the frequency response function of the second equalization coefficient, satisfying Heq(0)=G(0)=1.

It should be noted that the difference between the test parameter T in this application and the existing TDECQ calculation method is that, considering the improvement of the reference equalizer part, the calculation method of the noise enhancement coefficient Ceq in this application has been adapted Adjustment, since the test parameters have the same effect, the test parameter T in this application can also be called TDECQ.

If the tap coefficients (1, di, ..., dn) of part B of the equalizer are regarded as an independent filter, and the equivalent filter generated by it is defined as G(f), then the parameters of Ceq can be expressed as:

Compared with the existing Ceq noise factor, increasing the noise suppression effect of the equalizer B part can ensure the self-consistency of the scheme.

606. If the value of the test parameter is less than or equal to the first threshold, determine that the consistency test of the optical signal passes.

If the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, passing the optical signal consistency test indicates that the optical transmitter has passed the consistency test. It should be noted that the first threshold can be set according to actual application requirements, and the specific value is not limited here.

In a possible implementation, the conformance testing device calculates the number of consecutive bit errors according to the test eye diagram and the signal sequence, if the value of the test parameter is less than or equal to the first threshold, and the number of consecutive bit errors is less than or equal to the first threshold two thresholds, the consistency testing device determines that the consistency test of the optical signal passes. The second threshold can be set according to actual application requirements, and the specific value is not limited here.

The consistency test method provided by this application performs equalization compensation on the collected signal sequence through the test sequence, which can improve the equalization compensation effect, increase the acceptable additional noise margin of the system, improve the numerical accuracy of the test TDECQ, and optimize the test performance.

The following is an introduction to a specific implementation of the consistency testing method provided in the embodiment of the present application. Please refer to FIG. 8 , which is a schematic diagram of another embodiment of the consistency testing method provided in the embodiment of the application. The method includes steps 801-805 .

801. Sequence alignment.

Since this solution uses known waveforms (ie, test sequences) to participate in the calculation, the data to be processed, that is, the signal sequence, is aligned with the known test sequences before equalization. Before this step, steps 601 and 602 need to be performed.

802. Equilibrium compensation.

Please refer to step 603 for the specific implementation process.

803. Synthesize an eye diagram for testing.

Step 803 includes obtaining the test eye diagram and calculating the value of the test parameter T, for details, please refer to

steps

604 and 605 .

804. Determine whether the number of consecutive bit errors is less than or equal to a second threshold.

In an implementation of step 804, the conformance testing device calculates the number of consecutive bit errors according to the test eye diagram and the signal sequence, and judges whether the number of consecutive bit errors is less than or equal to the second threshold, and if so, executes step 805; if If not, the conformance testing device judges that the conformance test of the optical transmitter fails.

805. Determine whether the value of the test parameter is less than or equal to the first threshold.

If yes, the conformance testing device judges that the conformance test of the optical transmitter is passed. If not, the conformance testing device judges that the conformance test of the optical transmitter fails.

For content not described in detail in FIG. 8 , reference may be made to the description of relevant parts in FIG. 6 .

The following briefly introduces the data processing flow in the consistency testing method provided by the embodiment of the present application, please refer to FIG. 9 .

The input signal X_in is a signal collected by the standard receiver O/E, and its data collection length needs to be greater than the length of the test sequence stored in the sequence storage unit. First, X_in is down-sampled to single-fold sampling to obtain data X_in_ds. That is, the physical time interval between data is T=1/fs, where fs is the baud rate of the signal. Since this scheme uses known test sequences (patterns) to participate in the calculation, it is necessary to perform cross-correlation between the data to be processed (X_in_ds) and the known test sequences before equalization. The sequence alignment function X_in_ds cross-correlates with the pattern to get the length of X_in_ds that needs to be translated, and then enters the equalization process after outputting the alignment signal X_in_syn. As shown in Figure 9, part A of the frame line is the FFE equalization process, and part B is the sequence feedback equalization process. The specific implementation is: the nth X_in_syn sequence enters FFE equalization, T is the delay operation, that is, the signal at the sampling moment before the nth signal of x_in_syn is selected, that is, the n-1th x_in_syn signal, and so on, and then T operation is performed again, Then take out the n-2th x_in_syn signal. The length of the participating signal is determined by the number of FFE equalization coefficients. {x_in_syn(n), x_in_syn(n-1), x_in_syn(n-2),…} signals are multiplied with the first equalization coefficients {c_n, c_n-1, c_n-2,…} in turn to get {x_in_syn (n)*c_n, x_in_syn(n-1)*c_n-1,...}, and then do the addition operation. The FFE equalization process can be implemented through memory, multiplication gates and addition circuits. The first equalization coefficient {Ci} is obtained by an adaptive algorithm, for example, it may be the signal-to-noise ratio of the feed-forward equalization output sequence. For part B sequence feedback equalization, for the nth output signal Y, the test sequence Pattern(n) first passes the T delay operation, selects the n-1th signal, and so on selects n-2, n-3 signals, The length of the participating operation is determined by the length of the feedback equalization coefficient. {Pattern(n-1), Pattern(n-2),...} sequence is multiplied by {d(n-1), d(n-2), d(n-3),...}, the second equalization The coefficient {di} is obtained by an adaptive algorithm. It can be obtained that the output signal Y(n) can be expressed as:

Y(n)＝∑c _i *x_in_syn(i)+∑d _i *pattern(i)

The adaptive equalization method between the output sequence Y(n) and the original pattern, as well as {Ci} and {di} are determined by the adaptive algorithm, and will not be discussed in detail here.

A possible data processing flow is introduced below from the perspective of the system architecture of the receiving end, as shown in FIG. 10 .

The sequence storage unit stores the test sequence, which is used for sequence alignment in the down-sampling step, and is also used for sending the test sequence to the sequence feedback equalization device for further equalization processing. The receiving end performs down-sampling on the collected input signal X to obtain data X_in, and inputs X_in into the feedforward equalization device for equalization. The first equalization coefficient of the feedforward equalization device is {ci}, and the output is the first equalization sequence Y_FFE, and continues through the sequence The feedback equalization device performs equalization, the second equalization coefficient is {di}, and the output second equalization sequence is Y_out.

After the equalization coefficient {ci}{di} is obtained, the value of TDECQ can be further calculated. Refer to FIG. 11 , which is a schematic diagram of a calculation process of a receiving end in an embodiment of the present application.

After obtaining the equalization coefficient, based on the opened eye diagram, by generating a histogram, obtain OMA, the standard deviation σ _G of the maximum additive noise, and Ceq, where σ _G is the standard of the maximum noise margin that the system can increase after equalization variance value.

Based on the above parameters, the value of the test parameter TDECQ can be obtained through formula calculation, and then the conformance test performance of the transmitter can be judged.

The consistency test method provided by the embodiment of the present application, considering that in the high signal rate scenario, the existing consistency test scheme test has too high requirements on the performance of the equipment, and the test accuracy is reduced, and the reference equalizer is improved, based on the known test sequence Perform equalization compensation on the collected signal sequence, synthesize the test eye diagram based on the equalization coefficient of the equalization compensation, calculate the value of the test parameter TDECQ according to the test eye diagram and the noise enhancement coefficient updated based on the equalization compensation, and use it to judge the optical signal transmitter This method can improve the acceptable additional noise margin of the system, improve the numerical accuracy of the test TDECQ, and optimize the test performance.

The consistency test method provided by this application is introduced above, and the consistency test device for implementing the consistency test method is introduced below. Please refer to FIG. 12, which is a schematic structural diagram of a consistency test device provided by the embodiment of this application .

The conformance test set includes:

The acquisition unit 1201 is used to acquire the signal sequence of the optical signal received by the optical receiver, the optical signal is generated by the optical transmitter using the four-level pulse amplitude modulation PAM4 mode modulation test sequence;

An acquisition unit 1202, configured to acquire the test sequence;

The processing unit 1203 is configured to perform equalization compensation on the signal sequence according to the test sequence, and synthesize a test eye diagram according to the equalization coefficient of the signal sequence obtained through the equalization compensation;

Calculation unit 1204, configured to calculate the value of the test parameter according to the test eye diagram and the noise enhancement coefficient corresponding to the equalization compensation;

The determination unit 1205 is configured to determine that the consistency test of the optical signal passes when the value of the test parameter is less than or equal to the first threshold.

Optionally, if the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, passing the optical signal consistency test indicates that the optical transmitter passes the consistency test.

Optionally, the calculating unit 1204 is also used for:

Calculate the number of consecutive bit errors according to the test eye diagram and the signal sequence;

The determining unit 1205 is specifically used for:

When the value of the test parameter is less than or equal to the first threshold and the number of consecutive bit errors is less than or equal to the second threshold, it is determined that the consistency test of the optical signal is passed.

Optionally, the processing unit 1203 is specifically configured to:

performing feedforward adaptive equalization on the signal sequence to obtain a first equalized signal sequence and a first equalization coefficient;

A feedforward adaptive equalization is performed on the first equalized signal sequence according to the test sequence to obtain a second equalization coefficient.

Optionally, the processing unit 1203 is specifically configured to:

determining an equalization coefficient of the signal sequence according to the first equalization coefficient and the second equalization coefficient;

The test eye diagram is synthesized according to the equalization coefficient of the signal sequence.

Optionally, the computing unit 1204 is specifically configured to:

According to the test eye diagram and the noise enhancement coefficient, determine the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate;

The value of the test parameter is determined according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached.

Optionally, the computing unit 1204 is specifically configured to:

Calculate the test parameter T according to the following formula:

in,

OMA is the optical modulation amplitude of the test eye diagram, Qt is the Q value of the test sequence waveform, σ _G is the standard deviation of the maximum additive noise, σ _S is the standard deviation of the optical receiver noise, and Ceq is the noise enhancement coefficient, N(f) is the noise density function, Heq(f) is the frequency response function of the first equalization coefficient, G(f) is the frequency response function of the second equalization coefficient, satisfying Heq(0)=G(0 )=1.

Optionally, the length of the signal sequence is greater than or equal to the length of the test sequence;

The processing unit 1203 is specifically used for:

Sequence alignment is performed on the signal sequence according to the test sequence, and the equalization compensation is performed on the sequence-aligned signal sequence.

The conformance test device provided by this application performs equalization compensation on the collected signal sequence based on the known test sequence, synthesizes the test eye diagram based on the equalization coefficient of the equalization compensation, and calculates according to the test eye diagram and the noise enhancement coefficient updated based on the equalization compensation The value of the test parameter TDECQ is used to judge whether the conformance test of the optical signal transmitter has passed, which can increase the acceptable additional noise margin of the system, improve the numerical accuracy of the test TDECQ, and optimize the test performance.

Please refer to FIG. 13 , which is a schematic structural diagram of another conformance testing device provided in the embodiment of the present application. The conformance test apparatus 1300 may specifically be a processing device with a processing function, for example, a computer, a server, etc. independent of the test system, or an oscilloscope in the test system. When the execution subject of the embodiment of the present application is a processing device independent of the test system, the above-mentioned reference equalizer may exist independently in the test system, or may be integrated in an oscilloscope of the test system, or may be integrated in the processing device. It should be noted that, when the above-mentioned reference equalizer is integrated in a processing device (for example, a processing device independent of the test system, or an oscilloscope in the test system), the above-mentioned reference equalizer can be implemented by means of hardware and/or software accomplish. For example, the above-mentioned reference equalizer can be realized by constructing a reference equalizer model in a processing device. Specifically, there is no limitation here. In the embodiment of the present application, the specific equipment form of the consistency testing device is not limited.

The conformance testing device 1300 may have relatively large differences due to different configurations or performances, and may include one or more processors 1301 and memory 1302, and programs or data are stored in the memory 1302. Optionally, the memory 1302 uses for storing test sequences.

Wherein, the storage 1302 may be a volatile storage or a non-volatile storage. Optionally, the processor 1301 is one or more central processing units (central processing unit, CPU), and the CPU may be a single-core CPU or a multi-core CPU. The processor 1301 can communicate with the memory 1302 , and execute a series of instructions in the memory 1302 on the conformance testing device 1300 .

The conformance testing device 1300 also includes one or more network interfaces 1303, such as Ethernet interfaces, optical fiber interfaces and the like.

Optionally, although not shown in FIG. 13 , the conformance testing device 1300 may also include one or more power supplies; one or more input and output interfaces, and the input and output interfaces may be used to connect a display, a mouse, a keyboard, a touch screen device or sensing equipment, etc.

For the process executed by the processor 1301 in the conformance testing apparatus 1300 in this embodiment, reference may be made to the method process described in the foregoing method embodiments, and details are not repeated here.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

If the integrated unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or part of the contribution to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (read-only memory, ROM), random access memory (random access memory, RAM), magnetic disk or optical disc and other media that can store program codes. .

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still understand the foregoing The technical solutions described in each embodiment are modified, or some of the technical features are equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the various embodiments of the application.

Claims

A consistency testing method, characterized in that the method comprises:

Collecting the signal sequence of the optical signal received by the optical receiver, the optical signal is generated by the optical transmitter using a four-level pulse amplitude modulation modulation test sequence;

obtaining the test sequence;

performing equalization compensation on the signal sequence according to the test sequence;

Synthesizing test eye diagrams according to the equalization coefficients of the signal sequence obtained by the equalization compensation;

Calculate the value of the test parameter according to the noise enhancement coefficient corresponding to the test eye diagram and the equalization compensation;

If the value of the test parameter is less than or equal to the first threshold, it is determined that the consistency test of the optical signal is passed.
The method according to claim 1, wherein if the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, the optical signal consistency test passes indicating that the optical transmitter is consistent sex test passed.
The method according to claim 1 or 2, characterized in that the method further comprises:

Calculate the number of consecutive bit errors according to the test eye diagram and the signal sequence;

If the value of the test parameter is less than or equal to the first threshold, determining that the consistency test of the optical signal passes includes:

If the value of the test parameter is less than or equal to the first threshold, and the number of consecutive bit errors is less than or equal to the second threshold, it is determined that the consistency test of the optical signal is passed.
The method according to any one of claims 1 to 3, wherein said equalizing and compensating said signal sequence according to said test sequence comprises:

performing feedforward adaptive equalization on the signal sequence to obtain a first equalized signal sequence and a first equalization coefficient;

Perform feedforward adaptive equalization on the first equalized signal sequence according to the test sequence to obtain a second equalization coefficient.
The method according to claim 4, wherein said synthesizing an eye pattern of an equalization coefficient of said signal sequence obtained according to said equalization compensation comprises:

determining an equalization coefficient of the signal sequence according to the first equalization coefficient and the second equalization coefficient;

The test eye diagram is synthesized according to the equalization coefficient of the signal sequence.
The method according to claim 4 or 5, wherein the calculation of the value of the test parameter according to the noise enhancement coefficient corresponding to the test eye diagram and the equalization compensation comprises:

According to the test eye diagram and the noise enhancement coefficient, determine the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate;

The value of the test parameter is determined according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached.
The method according to claim 6, wherein, according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached, determining the value of the test parameter includes :

Calculate the test parameter T according to the following formula:

in,

OMA is the optical modulation amplitude of the test eye diagram, Qt is the Q value of the test sequence waveform, σ G is the standard deviation of the maximum additive noise, σ S is the standard deviation of the optical receiver noise, Ceq Be the noise enhancement coefficient, N (f) is a noise density function, Heq (f) is the frequency response function of the first equalization coefficient, G (f) is the frequency response function of the second equalization coefficient, satisfying Heq (0)=G(0)=1.
The method according to any one of claims 1 to 7, wherein the length of the signal sequence is greater than or equal to the length of the test sequence;

The equalizing and compensating the signal sequence according to the test sequence includes:

Perform sequence alignment on the signal sequence according to the test sequence, and perform the equalization compensation on the sequence-aligned signal sequence.
A consistency testing device, characterized in that it comprises:

The acquisition unit is used to collect the signal sequence of the optical signal received by the optical receiver, and the optical signal is generated by the optical transmitter using a four-level pulse amplitude modulation PAM4 mode modulation test sequence;

an acquisition unit, configured to acquire the test sequence;

A processing unit, configured to perform equalization compensation on the signal sequence according to the test sequence, and synthesize a test eye diagram according to the equalization coefficient of the signal sequence obtained by the equalization compensation;

A calculation unit, configured to calculate the value of the test parameter according to the noise enhancement coefficient corresponding to the test eye diagram and the equalization compensation;

The determination unit is configured to determine that the consistency test of the optical signal passes when the value of the test parameter is less than or equal to a first threshold.
The device according to claim 9, wherein if the optical signal is transmitted by the optical transmitter when the relative intensity noise is maximum, the optical signal consistency test passes indicating that the optical transmitter is consistent sex test passed.
The device according to claim 9 or 10, wherein the computing unit is further used for:

Calculate the number of consecutive bit errors according to the test eye diagram and the signal sequence;

The determining unit is specifically used for:

When the value of the test parameter is less than or equal to a first threshold and the number of consecutive bit errors is less than or equal to a second threshold, it is determined that the consistency test of the optical signal is passed.
The device according to any one of claims 9 to 11, wherein the processing unit is specifically configured to:

performing feedforward adaptive equalization on the signal sequence to obtain a first equalized signal sequence and a first equalization coefficient;

Perform feedforward adaptive equalization on the first equalized signal sequence according to the test sequence to obtain a second equalization coefficient.
The device according to claim 12, wherein the processing unit is specifically used for:

determining an equalization coefficient of the signal sequence according to the first equalization coefficient and the second equalization coefficient;

The test eye diagram is synthesized according to the equalization coefficient of the signal sequence.
The device according to claim 12 or 13, wherein the calculation unit is specifically used for:

According to the test eye diagram and the noise enhancement coefficient, determine the standard deviation of the maximum additive noise that the optical transmitter can support when reaching the target bit error rate;

The value of the test parameter is determined according to the standard deviation of the maximum additive noise that the optical transmitter can support when the target bit error rate is reached.
The device according to claim 14, wherein the calculation unit is used to calculate the test parameter T according to the following formula:

in,

OMA is the optical modulation amplitude of the test eye diagram, Qt is the Q value of the test sequence waveform, σ G is the standard deviation of the maximum additive noise, σ S is the standard deviation of the optical receiver noise, Ceq Be the noise enhancement coefficient, N (f) is a noise density function, Heq (f) is the frequency response function of the first equalization coefficient, G (f) is the frequency response function of the second equalization coefficient, satisfying Heq (0)=G(0)=1.
The device according to any one of claims 9 to 15, wherein the length of the signal sequence is greater than or equal to the length of the test sequence;

The processing unit is specifically used for:

Perform sequence alignment on the signal sequence according to the test sequence, and perform the equalization compensation on the sequence-aligned signal sequence.
A conformance testing device is characterized in that it includes: one or more processors and memory; wherein,

computer readable instructions are stored in the memory;

The one or more processors read the computer readable instructions to cause the conformance testing device to implement the method of any one of claims 1-8.
A computer program product, characterized by comprising computer-readable instructions, which, when the computer-readable instructions are run on a computer, cause the computer to execute the method according to any one of claims 1 to 8.
A computer-readable storage medium, characterized in that instructions are stored therein, and when the instructions are run on a computer, the computer is made to execute the method according to any one of claims 1 to 8.