Access method and device of low earth orbit satellite communication system

Abstract

The invention discloses an access method and device of a low-orbit satellite communication system, and belongs to the field of satellite communication. The method comprises the following steps: if an auxiliary information timer of a current satellite cell is overtime and random access fails, determining whether an adjacent cell of which the beam signal strength reaches access threshold strength exists at present; if it is determined that the neighbor cell with the beam signal strength reaching the access threshold strength exists currently, determining an optimal satellite cell of random access according to the current satellite cell and the remaining service time of the neighbor cell to the ground terminal; the remaining service time is the remaining time when the satellite cell beam signal covers the ground terminal. According to the invention, the access can be accelerated, the access time delay can be reduced, and the risks of switching, signaling resource waste and switching failure increase caused by fast switching after access can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to an access method and device for a low-orbit satellite communication system. Background Art

[0002] When a ground terminal accesses a non-ground network system, it performs random access within the effective duration obtained based on the auxiliary information. Due to the fast movement speed of low-orbit satellites, the ground terminal stays in a satellite cell beam for a short time. If the access fails during random access in the current satellite cell, after the next attempt to access is successful, it may be necessary to switch to the next satellite cell beam soon, resulting in a large delay in random access of the terminal and a high access failure rate. Summary of the invention

[0003] The present invention provides a method and device for accessing a low-orbit satellite communication system, which can solve the problems of large delay and high failure rate in related technologies. The technical solution is as follows:

[0004] On the one hand, a method for accessing a low-orbit satellite communication system is provided, which is applied to a ground terminal, and the method includes:

[0005] If the auxiliary information timer of the current satellite cell times out and random access fails, determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength;

[0006] If it is determined that there is a neighboring cell whose beam signal strength reaches the access threshold strength, the optimal satellite cell for random access is determined based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

[0007] On the other hand, an access device for a low-orbit satellite communication system is provided, which is applied to a ground terminal, and the device includes:

[0008] A first determination unit is used to determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength if the auxiliary information timer of the current satellite cell times out and the random access fails;

[0009] The second determination unit is used to determine the optimal satellite cell for random access based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal if it is determined that there is currently a neighboring cell whose beam signal strength reaches the access threshold strength; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

[0010] On the other hand, a computer device is provided, which includes a memory and a processor, the memory is used to store computer programs, and the processor is used to execute the computer programs stored in the memory to implement the steps of the above-mentioned low-orbit satellite communication system access method.

[0011] On the other hand, a computer-readable storage medium is provided, wherein a computer program is stored in the storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned method for accessing the low-orbit satellite communication system are implemented.

[0012] On the other hand, a computer program product is provided, including a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for accessing the low-orbit satellite communication system.

[0013] The technical solution provided by the present invention can at least bring the following beneficial effects:

[0014] The ground terminal initiates random access to the current satellite cell within the validity period of the auxiliary information. If the auxiliary information timer times out and the random access fails, it is necessary to select the optimal cell for access. The optimal cell can be the current satellite cell or a neighboring cell whose beam signal strength reaches the access threshold strength. When selecting the optimal cell, the remaining time that the beam signal covers the ground terminal is introduced as the remaining service time of the satellite cell to the ground terminal. Selecting the optimal cell based on the remaining service time can not only speed up access and reduce access delay, but also avoid switching soon after access, waste of signaling resources and increase the risk of switching failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is a flow chart of a method for accessing a low-orbit satellite communication system provided by one embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the effective duration of a SIB19 system message provided by an embodiment of the present invention;

[0018] Figure 3 It is a structural diagram of an access device for a low-orbit satellite communication system provided by one embodiment of the present invention;

[0019] Figure 4It is a hardware architecture diagram of a computer device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] When a ground terminal accesses a non-terrestrial network system (NTN), it first synchronizes with the satellite cell, then receives the auxiliary information sent by the satellite cell, uses the auxiliary information to determine its effective duration, and initiates random access to the satellite cell within the effective duration. If the effective duration ends but the random access fails, it will continue to initiate random access to the satellite cell until it detects that the beam signal of the satellite cell is weakened and the beam signal strength of the neighboring cell reaches the access threshold strength, then it switches to the neighboring cell for random access.

[0022] When the ground terminal performs random access in the current satellite cell, it will not consider switching to the neighboring cell until the beam signal weakens. If the ground terminal successfully accesses the current satellite cell when the signal weakens, it will need to switch to the neighboring cell soon. Since the satellite is far away from the ground terminal, the terminal random access delay is large and the failure rate is high.

[0023] Based on this, the inventive concept of the present invention is to introduce the remaining time of the satellite cell beam signal covering the ground terminal as the remaining service time of the satellite cell to the ground terminal, and use the remaining service time to select the optimal cell for quick access whenever random access fails. The optimal cell can be the current satellite cell or a neighboring cell whose beam signal strength reaches the access threshold strength. This can reduce the access delay and improve the access success rate.

[0024] The specific implementation of the above concept is described below.

[0025] Please refer to Figure 1 , an access method for a low-orbit satellite communication system provided by an embodiment of the present invention is applied to a ground terminal, and the method includes:

[0026] Step 100: If the auxiliary information timer of the current satellite cell times out and random access fails, determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength;

[0027] Step 102: If it is determined that there is a neighboring cell whose beam signal strength reaches the access threshold strength, the optimal satellite cell for random access is determined based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

[0028] In an embodiment of the present invention, the ground terminal initiates random access to the current satellite cell within the validity period of the auxiliary information. If the auxiliary information timer times out and the random access fails, it is necessary to select the optimal cell for access. The optimal cell can be the current satellite cell or a neighboring cell whose beam signal strength reaches the access threshold strength. When selecting the optimal cell, the remaining time that the beam signal covers the ground terminal is introduced as the remaining service time of the satellite cell to the ground terminal. Selecting the optimal cell based on the remaining service time can not only speed up access and reduce access delay, but also avoid switching soon after access, waste signaling resources and increase the risk of switching failure.

[0029] Described below Figure 1 How the various steps are performed.

[0030] First, with respect to step 100, if the auxiliary information timer of the current satellite cell times out and random access fails, it is determined whether there is currently a neighboring cell whose beam signal strength reaches the access threshold strength.

[0031] Before accessing a non-ground network, a ground terminal first detects the beam signal of the non-ground network. There may be one or more detected beam signals. If there is only one, the satellite cell corresponding to the beam signal is directly used as the current satellite cell for synchronization and random access is initiated. If there are multiple ones, the satellite cell with the strongest beam signal can be selected as the current satellite cell for synchronization and random access is initiated.

[0032] After the ground terminal is synchronized with the current satellite cell, it receives the auxiliary information sent by the current satellite cell, where the auxiliary information can be a SIB19 system message. Based on the auxiliary information, the effective time (EpochTime, the start time of T430) and the effective duration (UlSyncValidityDuration, the end time of T430) of the auxiliary information can be obtained. Please refer to Figure 2 The ground terminal initiates random access to the current satellite cell according to the effective time and effective duration.

[0033] It can be understood that the auxiliary information timer is used to time the effective duration. The ground terminal initiates random access from the start time T430. If the auxiliary information timer times out, it indicates that the end time T430 has been reached. At this time, the auxiliary information is invalid. If the random access fails at this time, it is necessary to determine whether there is a neighboring area whose beam signal strength reaches the access threshold strength to determine whether it is necessary to switch to the neighboring area.

[0034] In one embodiment of the present invention, if it is determined that there is no neighboring cell whose beam signal strength reaches the access threshold strength, random access to the current satellite cell continues.

[0035] Then, for step 102, if it is determined that there is a neighboring cell whose beam signal strength reaches the access threshold strength, the optimal satellite cell for random access is determined based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

[0036] Since low-orbit satellites are closer to ground terminals and have faster speeds, their beam signals cover ground terminals for a shorter period of time. In order to ensure that ground terminals can have a longer service time after randomly accessing a satellite cell, rather than having to switch to other satellite cells soon after successful access. In an embodiment of the present invention, the remaining service time and the service threshold time are introduced, and whether the remaining service time exceeds the service threshold time is used to determine whether the satellite cell needs to be accessed. Among them, the remaining service time can be calculated through auxiliary information. The service threshold time can be set according to the maximum service time that the satellite cell can serve the ground terminal, for example, the service threshold time is 1 / 2 of the maximum service time.

[0037] Then, in the embodiment of the present invention, the method of determining the optimal satellite cell for random access may be: determining whether the auxiliary information sent by the current satellite cell can be obtained;

[0038] If the auxiliary information sent by the current satellite cell can be obtained, the auxiliary information is used to calculate the remaining service time of the current satellite cell to the ground terminal, and it is determined whether the remaining service time exceeds the set threshold time. If the remaining service time of the current satellite cell exceeds the set threshold time, the current satellite cell is randomly accessed as the optimal satellite cell; if the remaining service time of the current satellite cell does not exceed the set threshold time, the neighboring cell with a remaining service time exceeding the set threshold time and the strongest beam signal is randomly accessed as the optimal satellite cell.

[0039] In the embodiment of the present invention, if the auxiliary information sent by the current satellite cell can be obtained, it indicates that the beam signal strength of the current satellite cell is acceptable, communication with the current satellite cell can be achieved, and the success rate of random access is high. Therefore, the current satellite cell can also be used as a candidate cell for the optimal satellite cell.

[0040] In addition, if the remaining service time of the current satellite cell exceeds the set threshold time, it means that you can continue to try to access the current satellite cell, and at this time, you have already synchronized with the current satellite cell, and you only need to continue to initiate random access to the current satellite cell according to the auxiliary information. If the remaining service time of the current satellite cell does not exceed the set threshold time, it means that even if you try to access the current satellite cell again and the access is successful, you will need to switch to other satellite cells in a short time after the access is successful. At this time, you can directly select the best satellite cell in the neighboring area.

[0041] In an embodiment of the present invention, when selecting the optimal satellite cell in a neighboring cell, it is necessary to select a neighboring cell whose remaining service time exceeds a set threshold time and whose beam signal is the strongest. Then, the method for determining the neighboring cell whose remaining service time exceeds the set threshold time and whose beam signal is the strongest may include:

[0042] Sort the neighboring cells according to the beam signal strength, and select the neighboring cell with the strongest beam signal as the target neighboring cell;

[0043] Perform downlink synchronization with the target neighboring cell and obtain auxiliary information sent by the target neighboring cell; use the auxiliary information to calculate the remaining service time of the target neighboring cell to the ground terminal, and determine whether the remaining service time of the target neighboring cell exceeds the set threshold time. If the remaining service time of the target neighboring cell exceeds the set threshold time, the target neighboring cell is used as the optimal satellite cell and randomly accessed; if the remaining service time of the target neighboring cell does not exceed the set threshold time, the neighboring cell with the strongest beam signal among the remaining neighboring cells is selected as the target neighboring cell, and continue to execute this step.

[0044] That is to say, although the beam signal strength of the neighboring cell has reached the access threshold strength, the remaining service time of the neighboring cell beam signal may be short and it cannot be used as the optimal satellite cell. By selecting the neighboring cell with the remaining service time exceeding the set threshold time and the strongest beam signal, the problem of switching within a short time after random access and wasting signaling resources can be avoided.

[0045] Furthermore, if the remaining service time of the target neighboring cell does not exceed the set threshold duration, before selecting the neighboring cell with the strongest beam signal as the target neighboring cell from the remaining neighboring cells, it may also include: determining whether there are other neighboring cells whose beam signal strength reaches the access threshold strength, and if so, adding the other neighboring cells to the remaining neighboring cells for sorting, and using the new sorting to perform the selection of the neighboring cell with the strongest beam signal as the target neighboring cell from the remaining neighboring cells. In this way, when selecting the optimal satellite cell from the remaining neighboring cells, the candidate cells can be kept updated at all times, further improving the success rate of random access.

[0046] It should be noted that if there is currently one neighboring cell whose beam signal strength reaches the access threshold strength, then this one neighboring cell can be directly used as the optimal satellite cell; if there are multiple neighboring cells, they can be selected in the above manner.

[0047] In another case, if it is determined that the auxiliary information sent by the current satellite cell cannot be obtained, it means that the beam signal strength of the current satellite cell is poor, communication with the current satellite cell is difficult, and the success rate of random access is also low. In other words, if the auxiliary information sent by the current satellite cell cannot be obtained, the best satellite cell is selected from the neighboring cells for random access. In this way, the current satellite cell is no longer a candidate satellite cell for the best satellite cell, and only the best satellite cell is selected from the neighboring cells.

[0048] When selecting the optimal satellite cell among neighboring cells, in one implementation method, the neighboring cell with the strongest beam signal can be selected as the optimal satellite cell, so that the satellite cell can be accessed quickly and the access delay can be reduced. In another implementation method, the neighboring cell with the remaining service time exceeding the set threshold time and the strongest beam signal can be selected as the optimal satellite cell. In this way, not only can the satellite cell be accessed quickly, but also it can be ensured that after the satellite cell is accessed, it can be maintained for a long time without switching.

[0049] Please refer to Figure 3 The embodiment of the present invention provides an access device for a low-orbit satellite communication system, which is applied to a ground terminal, and the device includes:

[0050] The first determination unit 300 is used to determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength if the auxiliary information timer of the current satellite cell times out and the random access fails;

[0051] The second determination unit 302 is used to determine the optimal satellite cell for random access based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal if it is determined that there is currently a neighboring cell whose beam signal strength reaches the access threshold strength; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

[0052] In one embodiment of the present invention, the apparatus may further include: a third determination unit, configured to continue to randomly access the current satellite cell if it is determined that there is no neighboring cell whose beam signal strength reaches the access threshold strength.

[0053] In one embodiment of the present invention, when the second determination unit determines the optimal satellite cell for random access according to the remaining service time of the current satellite cell and the neighboring cells to the ground terminal, the method specifically includes:

[0054] Determine whether the auxiliary information sent by the current satellite cell can be obtained;

[0055] If the auxiliary information sent by the current satellite cell can be obtained, the auxiliary information is used to calculate the remaining service time of the current satellite cell to the ground terminal, and it is determined whether the remaining service time exceeds the set threshold time. If the remaining service time of the current satellite cell exceeds the set threshold time, the current satellite cell is randomly accessed as the optimal satellite cell; if the remaining service time of the current satellite cell does not exceed the set threshold time, the neighboring cell with a remaining service time exceeding the set threshold time and the strongest beam signal is randomly accessed as the optimal satellite cell.

[0056] In one embodiment of the present invention, when the second determination unit determines the optimal satellite cell for random access based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal, if the auxiliary information sent by the current satellite cell cannot be obtained, the optimal satellite cell is selected in the neighboring cell for random access.

[0057] In one embodiment of the present invention, the method for determining the neighboring cell whose remaining service time exceeds the set threshold time and whose beam signal is the strongest includes:

[0058] Sort the neighboring cells according to the beam signal strength, and select the neighboring cell with the strongest beam signal as the target neighboring cell;

[0059] Perform downlink synchronization with the target neighboring cell and obtain auxiliary information sent by the target neighboring cell; use the auxiliary information to calculate the remaining service time of the target neighboring cell to the ground terminal, and determine whether the remaining service time of the target neighboring cell exceeds the set threshold time. If the remaining service time of the target neighboring cell exceeds the set threshold time, the target neighboring cell is used as the optimal satellite cell and randomly accessed; if the remaining service time of the target neighboring cell does not exceed the set threshold time, the neighboring cell with the strongest beam signal among the remaining neighboring cells is selected as the target neighboring cell, and continue to execute this step.

[0060] In one embodiment of the present invention, if the remaining service time of the target neighboring area does not exceed the set threshold duration, then before selecting the neighboring area with the strongest beam signal among the remaining neighboring areas as the target neighboring area, the second determination unit can also be used to: determine whether there are other neighboring areas whose beam signal strength reaches the access threshold strength; if so, add the other neighboring areas to the remaining neighboring areas for sorting, and use the new sorting to execute the selection of the neighboring area with the strongest beam signal among the remaining neighboring areas as the target neighboring area.

[0061] It should be noted that the access device of the low-orbit satellite communication system provided in the above embodiment is only illustrated by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the access device of the low-orbit satellite communication system provided in the above embodiment and the access method embodiment of the low-orbit satellite communication system belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0062] The embodiment of the present application also provides a computer device, please refer to Figure 4 The computer device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor to implement the access method of the low-orbit satellite communication system provided by the above-mentioned method embodiments.

[0063] An embodiment of the present application also provides a computer-readable storage medium, on which is stored at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the access method of the low-orbit satellite communication system provided by the above-mentioned method embodiments.

[0064] An embodiment of the present application also provides a computer program product, which includes a computer program. A processor of a computer device reads the computer program from a computer-readable storage medium, and the processor executes the computer program, so that the computer device executes the access method of the low-orbit satellite communication system described in any of the above embodiments.

[0065] For the convenience of description, the above system or device is described by dividing it into various modules or units according to its functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0066] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly contributed to the prior art in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0067] Finally, it should be noted that, in this article, relational terms such as first, second, third and fourth are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0068] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for accessing a low-orbit satellite communication system, characterized in that: Applied to a ground terminal, the method comprises: If the auxiliary information timer of the current satellite cell times out and random access fails, determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength; If it is determined that there is a neighboring cell whose beam signal strength reaches the access threshold strength, the optimal satellite cell for random access is determined based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

2. The method according to claim 1, characterized in that If it is determined that there is no neighboring cell whose beam signal strength reaches the access threshold strength, continue to randomly access the current satellite cell.

3. The method according to claim 1, characterized in that The step of determining the optimal satellite cell for random access according to the remaining service time of the current satellite cell and the neighboring cells to the ground terminal comprises: Determine whether the auxiliary information sent by the current satellite cell can be obtained; If the auxiliary information sent by the current satellite cell can be obtained, the auxiliary information is used to calculate the remaining service time of the current satellite cell to the ground terminal, and it is determined whether the remaining service time exceeds the set threshold time. If the remaining service time of the current satellite cell exceeds the set threshold time, the current satellite cell is randomly accessed as the optimal satellite cell; if the remaining service time of the current satellite cell does not exceed the set threshold time, the neighboring cell with a remaining service time exceeding the set threshold time and the strongest beam signal is randomly accessed as the optimal satellite cell.

4. The method according to claim 3, characterized in that If the auxiliary information sent by the current satellite cell cannot be obtained, the best satellite cell is selected in the neighboring cell for random access.

5. The method according to claim 3, characterized in that: The method for determining the neighboring cell whose remaining service time exceeds the set threshold time and whose beam signal is the strongest includes: Sort the neighboring cells according to the beam signal strength, and select the neighboring cell with the strongest beam signal as the target neighboring cell; Perform downlink synchronization with the target neighboring cell and obtain auxiliary information sent by the target neighboring cell; use the auxiliary information to calculate the remaining service time of the target neighboring cell to the ground terminal, and determine whether the remaining service time of the target neighboring cell exceeds the set threshold time. If the remaining service time of the target neighboring cell exceeds the set threshold time, the target neighboring cell is used as the optimal satellite cell and randomly accessed; if the remaining service time of the target neighboring cell does not exceed the set threshold time, the neighboring cell with the strongest beam signal among the remaining neighboring cells is selected as the target neighboring cell, and continue to execute this step.

6. The method according to claim 5, characterized in that If the remaining service time of the target neighboring cell does not exceed the set threshold duration, before selecting the neighboring cell with the strongest beam signal from the remaining neighboring cells as the target neighboring cell, the method further includes: Determine whether there are other neighboring areas whose beam signal strength reaches the access threshold strength. If so, add the other neighboring areas to the remaining neighboring areas for sorting, and use the new sorting to select the neighboring area with the strongest beam signal among the remaining neighboring areas as the target neighboring area.

7. An access device for a low-orbit satellite communication system, characterized in that: Applied to a ground terminal, the device comprises: A first determination unit is used to determine whether there is a neighboring cell whose beam signal strength reaches the access threshold strength if the auxiliary information timer of the current satellite cell times out and the random access fails; The second determination unit is used to determine the optimal satellite cell for random access based on the remaining service time of the current satellite cell and the neighboring cell to the ground terminal if it is determined that there is currently a neighboring cell whose beam signal strength reaches the access threshold strength; the remaining service time is the remaining time that the satellite cell beam signal covers the ground terminal.

8. A computer device, characterized in that: The computer device includes a memory and a processor, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of any one of the methods described in claims 1-6.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 6 are implemented.

10. A computer program product, characterized in that The method comprises a computer program, wherein when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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