A large bandwidth air interface wire calibration method and system

Abstract

This application discloses a large-bandwidth air interface cable calibration method and system, solving the problem of degraded isolation performance at frequencies outside the SSB frequency domain in existing technologies. The large-bandwidth air interface cable calibration method involves the output of a signal transmitting device reaching the device antenna via a channel simulator. The method includes the following steps: acquiring the phase values ​​of the spatial transmission matrix corresponding to different frequency points within the system bandwidth; determining the phase difference matrix of different frequency points; determining the discrete points of the phase difference for each air interface transmission link at each frequency point; calculating the slope of the discrete points of the phase difference belonging to the same air interface transmission link using a linear fitting method; and converting the slope into delay compensation for the transmission link in the channel simulator. The large-bandwidth air interface cable calibration method proposed in this application is adaptable to spatial transmission matrices outside the SSB frequency domain, exhibiting good isolation performance at other frequency points and significantly reducing interference caused by isolation degradation in the test system.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a method and system for calibrating high-bandwidth air interface wires. Background Technology

[0002] 5G introduces two key technologies: Massive MIMO and millimeter wave. Due to the introduction of these two technologies, current testing systems are gradually transitioning from conduction-based methods to over-the-air (OTA) communication.

[0003] There are various types of over-the-air (OTA) terminal performance testing methods based on wireless technology. Among them, the Radiated Two-Stage (RTS) method is relatively low in cost and easy to implement.

[0004] Currently, there are phase-free measurement and calibration methods and systems available on the market for real base stations and commercial terminals. By changing the amplitude and phase value configuration of the channel simulator output port and recording the RSRP (Reference Signal Receiving Power) value of the SSB (Synchronization Signal / PBCH) reported by the terminal under test in different states, the spatial transmission matrix for the SSB frequency domain location is calculated, and the inverse of the spatial transmission matrix is ​​inserted into the channel simulator to realize the air interface wire connection.

[0005] Although phase-free measurement calibration methods are efficient and fast, the spatial transmission matrix targeting only the SSB frequency domain cannot characterize the characteristics of frequencies outside the SSB domain due to the different transmission characteristics (such as amplitude, delay, and phase) at different frequencies. This leads to a deterioration in the isolation effect at other frequencies. This is equivalent to introducing additional interference into the test system, causing deviations in the test results of the terminal under test. Summary of the Invention This application provides a method and system for calibrating large-bandwidth over-the-air (OTI) conductors, which solves the problem of deteriorated isolation performance at frequencies outside the SSB frequency domain in existing technologies.

[0006] This application provides a method for calibrating a high-bandwidth over-the-air (OTA) cable, wherein the output of a signal transmitting device reaches the device antenna via a channel simulator, and includes the following steps: Obtain the phase values ​​of the spatial transmission matrix corresponding to different frequency points within the system bandwidth, and determine the phase difference matrix of different frequency points; Determine the discrete points of phase difference for each air interface transmission link at each frequency, and calculate the slope of the discrete points of phase difference belonging to the same air interface transmission link by using a straight line fitting method; The slope is converted into delay compensation and applied to the air interface transmission link of the channel simulator.

[0007] Preferably, before determining the spatial transfer matrix, the method further includes the following steps: Determine the transmission path delay from the first input of the channel simulator through all its outputs to the calibration antenna; The time delay difference is compensated to the output of the channel simulator.

[0008] In one embodiment, the center frequency point of the SSB is configured to be offset to a different frequency point within the system bandwidth.

[0009] In one embodiment, the center frequency of the entire broadband signal is changed so that the center frequency position of the SSB can traverse different frequency points.

[0010] In one embodiment, the slope compensation to the channel simulator specifically includes the following steps: Calculate the ratio of the slope to 2π to determine the difference between the first delay and the second delay; the first delay is the delay of probe k reaching device antenna n, and the second delay is the delay of probe 1 reaching device antenna n. The difference compensation value channel simulator A n To B k On the transmission link.

[0011] In one embodiment, obtaining the phase value of the spatial transfer matrix includes the steps of: Turn on only probe 1 and k, and configure the output phase offset value of probe 1. for Simultaneously adjust the output phase offset value of probe k. Determine the received power of antenna n of the device under test. Maximum The value, and The phase value of the spatial transmission matrix H is equal to the phase difference between the two transmission links from probe k to antenna n and from probe 1 to antenna n.

[0012] In one embodiment, the signal is compensated for via the slope in the transmission link to the channel simulator, causing the signal to travel from A... n Arrival at device antenna y n All paths traversed in between have the same time delay.

[0013] Secondly, embodiments of this application also provide a high-bandwidth air interface cable calibration system for implementing the high-bandwidth air interface cable calibration method described in any embodiment of the first aspect, comprising: a channel simulator for supporting MIMO transmission connections at the input and output ends; for controlling the amplitude, phase, and delay on each link; and for simulating wireless channel characteristic parameters. A power amplifier for compensating for signal attenuation, eliminating loop self-oscillation, and achieving uplink and downlink reciprocity. A spatial matrix selection module, further comprising a turntable and multiple dual-polarized probes. The turntable is used to control the attitude traversal of the device under test at a set azimuth and pitch angle. The dual-polarized probes are fixed on the inner wall of the anechoic chamber and aligned with the center position of the device under test.

[0014] Thirdly, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in any embodiment of the first aspect.

[0015] Fourthly, embodiments of this application also provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method as described in any embodiment of the first aspect.

[0016] The above-described technical solutions adopted in the embodiments of this application can achieve the following beneficial effects: The large-bandwidth over-the-air (OTA) cable calibration method proposed in this application effectively improves antenna isolation while achieving the same signal transmission characteristics as conducted cables. This method is adaptable to spatial transmission matrices outside the SSB frequency domain, ensuring good isolation at other frequencies and significantly reducing interference caused by isolation degradation in the test system. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a block diagram of a two-step radio frequency method for existing technology; Figure 2 This is a schematic diagram of the SSB frequency domain location in existing technology; Figure 3 A flowchart of a high-bandwidth over-the-air (OTA) cable calibration method provided in this application embodiment; Figure 4 This is a schematic diagram of a MIMO air interface wire testing scheme provided in an embodiment of this application; Figure 5 This is a schematic diagram of the SSB center frequency offset provided in the embodiments of this application; Figure 6A schematic diagram of a system-level latency calibration scheme provided in an embodiment of this application; Figure 7 This is a structural diagram of the high-bandwidth over-the-air (OTA) cable calibration system provided in an embodiment of this application; Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0020] Figure 1 This is a block diagram of the existing RTS radio frequency two-step method system.

[0021] like Figure 1 As shown, the first step of RTS is to measure the antenna pattern of the terminal under test (DUT), and the second step is to combine the terminal antenna pattern with the channel model under test and input it into the channel simulator. To ensure that each probe antenna is connected only to the corresponding antenna port of the DUT in the case of a wireless RF cable, and to achieve an over-the-air (OTA) wire connection, it is necessary to measure the amplitude and phase information on the antenna port of the terminal, complete the acquisition of the spatial transmission matrix between the output of the channel simulator and the antenna port of the DUT, and then input the inverse of the spatial transmission matrix into the channel simulator to achieve the OTA wire connection in the second step.

[0022] Although the phase-free measurement calibration method is efficient and fast, the SSB only occupies 240 subcarrier widths in the frequency domain. That is, when the subcarrier width is 15kHz, the SSB frequency domain width is 3.6MHz; when the subcarrier width is 30kHz, the SSB frequency domain width is 7.2MHz. Figure 2 As shown. Because the transmission characteristics of different frequency points are different, namely amplitude, delay and phase, the spatial transmission matrix for the SSB frequency domain location alone cannot characterize the spatial transmission matrix outside the SSB frequency domain. This leads to a deterioration of the isolation effect at other frequency points, which is equivalent to introducing additional interference into the test system, causing deviations in the test results of the terminal under test. In view of this, the purpose of this application is to provide a high-bandwidth air interface cable calibration method. Based on a conventional air interface cable hardware platform, it realizes the air interface cable connection between the signal transmitting equipment and the multi-antenna test equipment, ensuring that the inter-antenna isolation within the entire bandwidth can meet the index requirements, so as to support high-bandwidth system-level functional and performance tests, especially 5G millimeter wave terminals, satellite terminals and satellite communications with bandwidth of 100MHz and above.

[0023] In this application, "air interface cable" refers to the connection between the probe and the device antenna port, replacing wired signal transmission with one-to-one wireless signal transmission between the RF probe and the terminal antenna in the test system.

[0024] Figure 3 The flowchart of a large bandwidth air interface conductor calibration method provided in this application embodiment includes steps 110-130.

[0025] First, this application proposes a method for calibrating a high-bandwidth air interface wire, wherein the output of the signal transmitting device reaches the device antenna via a channel simulator.

[0026] Including the following steps: Step 110: Obtain the phase values ​​of the spatial transmission matrix corresponding to different frequency points within the system bandwidth, and determine the phase difference matrix of different frequency points.

[0027] Air interface wire calibration: Taking a K×N MIMO over-the-air cable test scheme as an example, where K is the number of probes and N is the number of antennas of the device under test, and K and N are equal, and it is assumed that the center frequency of the SSB is located at this time. .like Figure 4 As shown.

[0028] The overall spatial transfer matrix H can then be expressed by the following formula: Formula 1 in For probe With device antenna The channel response between the amplitude values and phase value Two decisions. For ease of calibration, only opening is required. One signal, simultaneously calibrating the matrix Configured as an all-1 matrix.

[0029] The measurement process mainly consists of three steps: Step 1: Measure the amplitude value

[0030] By controlling the attenuation value on each transmission path from port A1 to ports B1...BK of the CE, the probe path can be switched on or off, opening and closing them respectively. Each probe channel records the data of the device under test. RSRP value of road antenna For example, turn on the probe. Record the device under test The RSRP values ​​of the road antennas are respectively … The amplitude value of the global spatial transfer matrix H can be expressed by the following formula, where It is a constant.

[0031] Formula 2 Step 2: Measure the phase difference

[0032] In one embodiment, it includes: Turn on only probe 1 and k, and configure the output phase offset value of probe 1. for Simultaneously adjust the output phase offset value of probe k. Determine the received power of antenna n of the device under test. Maximum The value, and The phase value of the spatial transmission matrix H is equal to the phase difference between the two transmission links from probe k to antenna n and from probe 1 to antenna n.

[0033] For example, equal and The phase difference, here used express.

[0034] By repeating the above steps, all phase difference information can be obtained. … … While adjusting the probe's output phase offset value, the antenna of the device under test can be observed. … Received power The phase value of the global spatial transfer matrix H can be obtained by calculating the phase difference of the matrix H. The phase value of the matrix H can be expressed by the following formula: Formula 3 Using the obtained SSB center frequency point The amplitude of the spatial transfer matrix H and phase Determine the phase difference matrix. As shown in the formula below.

[0035] Formula 4 In one embodiment, the center frequency is shifted to a different frequency within the system bandwidth by configuring the SSB frequency point position.

[0036] For example, by configuring the SSB frequency position of the base station or integrated testing instrument, the center frequency can be shifted to a different frequency within the system bandwidth. .

[0037] In one embodiment, the center frequency of the entire broadband signal is changed so that the center frequency position of the SSB can traverse different frequency points.

[0038] Change the center frequency of the entire broadband signal (e.g., 100MHz) so that the center frequency position of the SSB can traverse different frequency points. .

[0039] SSB center frequency offset as Figure 5 As shown.

[0040] Complete the phase difference measurement in Step 2 again to obtain the phase difference matrix. ,in As shown in the formula below.

[0041] Formula 5 Step 120: Determine the discrete points of phase difference for each air interface transmission link at each frequency, and calculate the slope of the discrete points of phase difference belonging to the same air interface transmission link by using the linear fitting method.

[0042] Discrete points can be obtained using linear fitting methods, such as least squares method and gradient descent method. slope The probe is calculated using the following formula. Reaching the antenna of the terminal under test The time delay and the arrival time of probe 1 at the antenna of the terminal under test The difference in latency .

[0043] Formula 6 In one embodiment, the slope compensation to the channel simulator specifically includes the following steps: Calculate the ratio of the slope to 2π to determine the difference between the first delay and the second delay; the first delay is the delay of probe k reaching device antenna n, and the second delay is the delay of probe 1 reaching device antenna n.

[0044] The difference compensation value channel simulator A n To B k On the transmission link.

[0045] Step 130: Convert the slope into delay compensation and apply it to the air interface transmission link of the channel simulator.

[0046] Delay difference It's at the link level, so when performing calibration compensation, this value needs to be compensated to the channel simulator. arrive On the transmission link, not at the input / output end.

[0047] Preferably, before determining the spatial transfer matrix, the method further includes the following steps: Step 210: Determine the transmission path delay from the first input to all outputs of the channel simulator; For example, such as Figure 6 The system-level latency calibration scheme is shown, in which the device antenna is placed in the center of the anechoic chamber, which is also the location of the center of the terminal under test.

[0048] The first delay difference is 0. The difference between the delay from the first input terminal to the first output terminal and the delay from the first input terminal to any subsequent output terminal is determined as the subsequent delay difference. VNA uses the S21 measurement method, with CE as the standard. The ports serve as signal input terminals, respectively completing the CE output. Transmission path delay to the calibration antenna The time delay difference is calculated as follows: .

[0049] The S21 measurement method represents the forward transmission coefficient from port 1 to port 2, including amplitude and phase information.

[0050] The VNA transmits a signal to port A1 of the CE. The signal is transmitted to the device antenna via the output terminals B1...BK of the CE. The VNA measures the amplitude and phase response of the transmission path from port A1 to the calibration antenna.

[0051] Formula 7 Step 220: Compensate the time delay difference to the output of the channel simulator.

[0052] The time delay difference will be compensated to the CE output. This ensures that the latency is the same for each transmission path.

[0053] In one embodiment, the slope compensation is used to ensure that the signal travels from A to the air interface transmission link of the channel simulator. n Arrival at device antenna y n All paths traversed in between have the same time delay.

[0054] The ultimate goal of multi-antenna delay calibration is to ensure that the signal from An Arrive at y n All paths traversed in between have the same time delay, for example , ... ... The transmission path delay is the same.

[0055] Figure 7 A structural diagram of a high-bandwidth over-the-air (OTA) cable calibration system provided in this application embodiment is used to implement the high-bandwidth OTA cable calibration method described in any embodiment of the first aspect, including: Channel simulator 11 is used to support input and output MIMO transmission connections; it is also used to control the amplitude, phase and delay on each link; and it is also used to simulate wireless channel characteristic parameters.

[0056] For example, the channel simulator not only supports MIMO transmission connections at the input and output ends, but also enables independent control of amplitude, phase and delay on each link. It also supports simulating wireless channel characteristic parameters. Therefore, after system calibration, performance tests of the device under test can be performed directly under the wireless channel.

[0057] Power amplifier 12 is used to compensate for signal attenuation, eliminate loop self-oscillation, and achieve uplink and downlink reciprocity.

[0058] For example, the power amplifier mainly includes key components such as a time-controlled single-pole double-throw switch, a power amplifier, and an adjustable attenuator. Its main functions are threefold: first, to compensate for signal attenuation in an anechoic chamber, ensuring good power coverage for the device under test; second, to ensure uplink and downlink reciprocity by adjusting the adjustable attenuator, and to support performance tests such as those conducted at long distances; and third, to effectively prevent signal self-oscillation by utilizing the high isolation characteristics of the single-pole double-throw switch.

[0059] The spatial matrix selection module 13 further includes a turntable 131 and multiple dual-polarization probes 132.

[0060] The turntable is used to control the attitude of the device under test to traverse the set azimuth and pitch angles. The dual-polarized probe is fixed to the inner wall of the darkroom and aligned with the center of the device under test.

[0061] For example, the antenna patterns of the device under test (DUT) antenna and the dual-polarized probe, as well as their spatial relative positions, determine the characteristics of the spatial transmission matrix. By adjusting the DUT's various orientations in space using a turntable and simultaneously placing multiple dual-polarized probes, diverse spatial transmission matrices can be constructed. The final DUT orientation and probe combination can be optimally selected based on the matrix condition number and the final isolation.

[0062] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0063] Therefore, this application also proposes a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the methods described in any embodiment of this application.

[0064] Furthermore, this application also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in any embodiment of this application.

[0065] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0066] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0067] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0068] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory. Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0069] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device 600 shown is merely an example and should not impose any limitations on the function and scope of use of the embodiments of this application. It includes: one or more processors 620; and a storage device 610 for storing one or more programs, which, when run by the one or more processors 620, cause the one or more processors 620 to implement the methods in steps 110-130 and 210-220.

[0070] The electronic device 600 also includes an input device 630 and an output device 640; the processor 620, storage device 610, input device 630 and output device 640 in the electronic device can be connected by a bus or other means, as shown in the figure, which is connected by a bus 650.

[0071] Storage device 610, as a computer-readable storage medium, can be used to store software programs, computer-executable programs, and module units, such as program instructions corresponding to the methods in the embodiments of this application. Storage device 610 may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function; the data storage area may store data created based on terminal usage. Furthermore, storage device 610 may include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some instances, storage device 610 may further include memory remotely located relative to processor 620, and these remote memories can be connected via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0072] Input device 630 can be used to receive input digital, character, or voice information, and to generate key signal inputs related to user settings and function control of the electronic device. Output device 640 may include electronic devices such as a display screen and a speaker.

[0073] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0074] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for calibrating a high-bandwidth over-the-air (OTA) cable, wherein the output of a signal transmitting device reaches the device antenna via a channel simulator, characterized in that... Including the following steps: Obtain the phase values ​​of the spatial transmission matrix corresponding to different frequency points within the system bandwidth, and determine the phase difference matrix of different frequency points; Determine the discrete points of phase difference for each air interface transmission link at each frequency, and calculate the slope of the discrete points of phase difference belonging to the same air interface transmission link by using a straight line fitting method; The slope is converted into delay compensation and applied to the transmission link of the channel simulator.

2. The large-bandwidth over-the-air (OTA) cable calibration method according to claim 1, characterized in that, Before determining the spatial transfer matrix, the following steps are included: Determine the transmission path delay from the first input of the channel simulator through all its outputs to the calibration antenna; The time delay difference is compensated to the output of the channel simulator.

3. The large-bandwidth over-the-air (OTA) cable calibration method according to claim 1, characterized in that, By configuring the SSB frequency point position, the center frequency point can be shifted to different frequency points within the system bandwidth.

4. The large bandwidth over-the-air cable calibration method according to claim 1, characterized in that, By changing the center frequency of the entire broadband signal, the position of the SSB center frequency can traverse different frequency points.

5. The method for calibrating large-bandwidth over-the-air cables according to claim 1, characterized in that, The slope compensation to the channel simulator specifically includes the following steps: Calculate the ratio of the slope to 2π to determine the difference between the first delay and the second delay; the first delay is the delay of probe k reaching device antenna n, and the second delay is the delay of probe 1 reaching device antenna n. The difference compensation value channel simulator A n To B k On the transmission link.

6. The large-bandwidth over-the-air (OTA) cable calibration method according to claim 1, characterized in that, Obtaining the phase value of the spatial transfer matrix includes the following steps: Turn on only probe 1 and k, and configure the output phase offset value of probe 1. for Simultaneously adjust the output phase offset value of probe k. Determine the received power of antenna n of the device under test. Maximum The value, and It is equal to the phase difference between probe k and antenna n.

7. The large-bandwidth over-the-air cable calibration method according to claim 1, characterized in that, The slope compensation is applied to the air interface transmission link of the channel simulator, causing the signal to travel from A... n Arrival at device antenna y n All paths traversed in between have the same time delay.

8. A high-bandwidth over-the-air (OTA) cable calibration system, used to implement the high-bandwidth OTA cable calibration method according to any one of claims 1 to 7, characterized in that, include: Channel simulator, used to support MIMO transmission connections at both input and output ends; It is also used to control the amplitude, phase, and delay on each link; and to simulate wireless channel characteristic parameters. Power amplifiers are used to compensate for signal attenuation, eliminate loop self-oscillation, and achieve uplink and downlink reciprocity. The spatial matrix selection module further includes a turntable and multiple dual-polarization probes; The turntable is used to control the attitude of the device under test to traverse the set azimuth and pitch angles. The dual-polarization probe is fixed on the inner wall of the dark room and aligned with the center of the device under test.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-7.

10. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-7.

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