Post FEC (Forward Error Correction) Padding processing method and device for WIFI (Wireless Fidelity) system

Abstract

The invention provides a Post FEC (Forward Error Correction) Padding processing method and device for a WIFI (Wireless Fidelity) system, which is used for processing Post FEC Padding data of each user and comprises the following steps: performing grouping processing on the Post FEC Padding data of each user to obtain a plurality of groups of data; according to the method and the system, each group of data and Cover codes are subjected to logical operation, and each user uses different Cover codes so as to ensure that Post FEC Padding data of each user are different. Or scrambling processing is carried out on the Post FEC Padding data of each user through a scrambler, and each user uses different non-zero scrambling initial values so as to ensure that the Post FEC Padding data of each user are different. According to the method and the device, the coverage code processing or the scrambling processing is performed on the Post FEC Padding data of the users in the WIFI communication system, so that the Post FEC Padding data of each user are different, the situation that corresponding subcarriers generate the same phase when the data of multiple users are transmitted in an overlapped manner is avoided, further, the data distortion saturation is avoided, the decoding error rate is reduced, and the decoding efficiency is improved. And the system performance of WIFI communication is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a Post FEC Padding processing method and apparatus for a WIFI system. Background Art

[0002] WIFI is a wireless local area network technology based on the IEEE 802.11 standard. It allows electronic devices to access the internet at high speed over short distances via radio waves. It has undergone multiple evolutions from WIFI1 to WIFI7, and its theoretical transmission rate has increased from 2Mbps to 46Gbps. WIFI2 began using Orthogonal Frequency Division Multiplexing (OFDM) technology, a multi-carrier modulation scheme that divides the channel into several orthogonal sub-channels, converting high-speed data signals into parallel low-speed sub-data streams, which are modulated for transmission on each sub-channel. Users are distinguished by time. In each time period, a user occupies all sub-carriers within the bandwidth and sends a complete data packet. WIFI5 introduced Multi-User Multiple Input Multiple Output (MUMIMO) technology, which allows the use of multiple antennas to transmit data to multiple devices simultaneously, greatly improving spectrum utilization. Wi-Fi 6 introduces a more efficient data transmission mode, Orthogonal Frequency Division Multiple Access (OFDMA). This mode multiplexes channel resources among multiple users by allocating subcarriers to different users and adding multiple access within the OFDM system. The smallest subchannel is called a Resource Unit (RU), and each RU contains at least 26 subcarriers. Compared to OFDM, OFDMA achieves finer channel resource allocation, making it better suited for indoor Wi-Fi data transmission scenarios.

[0003] In Wi-Fi systems, physical layer padding is a critical step in ensuring that data packet lengths meet specific requirements. This includes pre-FEC padding and post-FEC padding before forward error correction (FEC) coding. Pre-FEC padding ensures that the data input to the encoder meets the coding requirements, while post-FEC padding ensures that the encoded data length can fill a full OFDM symbol. According to the IEEE 802.11ax protocol, when multiple users transmit using OFDMA, if each user's post-FEC padding consists of consecutive "0s" or "1s," or some other identical random data, the overlapping transmission of multiple user data will cause the corresponding subcarriers to have the same phase, resulting in higher instantaneous power and, consequently, a higher peak-to-average power ratio (PAPR). Because the linear operating range of power amplifiers is limited, a higher PAPR can easily cause the signal to enter the nonlinear region, leading to distortion saturation. Especially when packet lengths are short, this nonlinear distortion saturation can lead to extremely high decoding error rates, degrading system performance. Summary of the Invention

[0004] In view of this, embodiments of the present disclosure provide a Post FEC Padding processing method and apparatus for a Wi-Fi system, which can significantly improve the system performance of Wi-Fi communications.

[0005] The embodiments of this specification provide the following technical solutions:

[0006] In a first aspect, embodiments of this specification provide a Post FEC Padding processing method for a Wi-Fi system, which is used to process Post FEC Padding data of each user, including the following steps:

[0007] The Post FEC Padding data of each user is grouped and processed to obtain multiple groups of data;

[0008] Perform a logical operation on each set of data and Cover codes to obtain corresponding Post FEC Padding data. Each user uses different Cover codes to ensure that the Post FEC Padding data of each user is different.

[0009] In conjunction with the first aspect, in one possible implementation, the step of grouping the Post FEC Padding data to obtain multiple groups of data includes:

[0010] Assuming the length of Post FEC Padding is K bits and grouped by M bits, there are a total of Group data, where M <K。

[0011] In combination with the first aspect, in a possible implementation, the logical operation is any one of an AND operation, an OR operation, a NOT operation, an XOR operation, an XNOR operation, a NAND operation, and a NOR operation; and / or,

[0012] The Cover codes may be Hadamard codes or any other random codes.

[0013] In conjunction with the first aspect, in a possible implementation, the method further includes the following steps:

[0014] The Post FEC Padding data obtained after the logical operation is further scrambled by the scrambler to ensure that the Post FEC Padding data of each user is different.

[0015] In a second aspect, an embodiment of this specification provides a Post FEC Padding processing method for a Wi-Fi system, which is used to process Post FEC Padding data of each user, including the following steps:

[0016] The Post FEC Padding data of each user is scrambled by a scrambler to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

[0017] In combination with the second aspect, in a possible implementation, a 7th-order or 11th-order scrambler is used for scrambling based on the same data domain, or,

[0018] The polynomial of the scrambler may be any one of an m-sequence or a Gold sequence of other orders.

[0019] With reference to the second aspect, in a possible implementation, the scrambling code generating polynomial of the scrambler is:

[0020] S(x)=x 7 +x 4 +1 or

[0021] S(x)=x 11 +x 9 +1

[0022] Where x represents the bit involved in the operation in the scrambler, for example, x 4 Indicates that the value of the fourth shift register needs to participate in the operation, and S(x) represents the scrambler output.

[0023] In conjunction with the second aspect, in a possible implementation, the method further includes the following steps:

[0024] The Post FEC Padding data obtained after scrambling for each user is grouped to obtain multiple groups of data;

[0025] Perform logical operations on each set of data and Cover codes to ensure that the Post FECPadding data of each user is different.

[0026] In a third aspect, an embodiment of this specification provides a Post FEC Padding processing device for a Wi-Fi system, configured to process Post FEC Padding data of each user, including:

[0027] The grouping module is used to group the Post FEC Padding data of each user to obtain multiple groups of data;

[0028] The Cover codes processing module is used to perform a logical operation on each set of data and the Cover codes to obtain corresponding Post FEC Padding data. Each user uses a different Cover codes to ensure that the Post FEC Padding data of each user is different.

[0029] In a fourth aspect, an embodiment of this specification provides a Post FEC Padding processing device for a Wi-Fi system, configured to process Post FEC Padding data of each user, including:

[0030] The scrambler is used to scramble the Post FEC Padding data of each user to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

[0031] In a fifth aspect, an embodiment of this specification provides a communication system, including an AP device, a soft AP device and a terminal device; the AP device, the soft AP device or the terminal device is used to execute the method described in any of the above solutions.

[0032] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0033] This application performs cover code processing or scrambling on the Post FEC Padding data of each user in a Wi-Fi communication system, making the Post FEC Padding data of each user different. This prevents the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of Wi-Fi communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 This is a schematic diagram of the HEMU PPDU sending process in the prior art;

[0036] Figure 2 This is a schematic diagram of the multi-user Post FEC Padding process in the prior art;

[0037] Figure 3 Cover codes processing flow chart of the Post FEC Padding processing method provided by this application;

[0038] Figure 4 This is a schematic diagram of the Cover codes process of the Post FEC Padding processing method provided by this application;

[0039] Figure 5 This is a scrambling process flow chart of the Post FEC Padding processing method provided by this application;

[0040] Figure 6 This is a schematic diagram of the multi-user scrambling process of the Post FEC Padding processing method provided by this application;

[0041] Figure 7 Flowchart of Cover codes processing and scrambling processing of the Post FEC Padding processing method provided by this application;

[0042] Figure 8This is a flowchart of the scrambling and cover codes processing of the Post FEC Padding processing method provided by this application;

[0043] Figure 9 This is a schematic diagram of the simulation results of the Post FEC Padding processing method provided in this application. DETAILED DESCRIPTION

[0044] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0045] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0046] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0047] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0048] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples, however, one skilled in the art will appreciate that the examples can be practiced without these specific details.

[0049] The professional and technical explanations in the embodiments of this specification are as follows:

[0050] like Figure 1 As shown in the figure, the sending process of HEMU PPDU (High Efficiency Multi User Physical Layer Protocol Data Unit) is illustrated. Since the sending end of the downlink HEMU PPDU is the access point (AP), the AP is aware of the data and resource allocation information of all users, including MCS (Modulation and Coding Scheme), the number of spatial streams, etc. This information is included in HE-SIG-B (High Efficiency Signal B). The transmitted data of each user is first filled with Pre FEC Padding, then sent to the encoder for channel coding, and then filled with Post FEC Padding. After spatial stream parsing, interleaving or tone mapping (LDPC Tone Map), the data of each user is mapped to the corresponding RU through constellation modulation. Specifically, Figure 1 The functions of each module are explained as follows:

[0051] Payload: Payload; Scrambler: Scrambler; BCC Encoder: BCC (Binary Convolutional Code) encoder; LDPC Encoder: (Low-Density Parity-Check Code) encoder; Stream Parser: Stream Parser; BCC Interleaver: BCC interleaver; Constellation mapper: Constellation mapper; CSD per STS: Cyclic shift diversity (CSD) per Space-Time Streams (Cyclic shift diversity per space-time stream); LDPC Tone Mapper: LDPC tone mapper; Spatial and Frequency Mapping: Spatial and Frequency Mapping.

[0052] Another example Figure 2Figure 2 illustrates the Post FEC Padding process. Because each user's data packets vary in length, the Post FEC Padding length varies. Ultimately, all user data is aligned to OFDM symbol boundaries. To facilitate hardware implementation, this padding is typically set to "0" or "1," or all users use the same initial scrambling code value for 7-order scrambling.

[0053] However, when multiple users transmit using OFDMA, if each user's Post FEC Padding uses continuous "0"s or "1"s, or some other identical random data, the superimposed transmission of multiple users' data will cause the corresponding subcarriers to have the same phase, resulting in higher instantaneous power and, in turn, a higher Peak to Average Power Ratio (PAPR). Since the linear operating region of the power amplifier is limited, a higher PAPR can easily cause the signal to enter the nonlinear region, leading to distortion saturation. Especially when the packet length is short, the data decoding bit error rate caused by nonlinear distortion saturation is extremely high, which reduces system performance.

[0054] Based on this, the embodiments of this specification propose a new Post FEC Padding processing solution.

[0055] The following describes the technical solutions provided by various embodiments of the present application in conjunction with the accompanying drawings.

[0056] <Example 1>

[0057] like Figure 3 and Figure 4 As shown, Example 1 of this specification provides a Post FEC Padding processing method for a WIFI system, which is used to process the Post FEC Padding data of each user, including S101-S102. Specifically,

[0058] Step S101: Grouping the Post FEC Padding data of each user to obtain multiple groups of data.

[0059] Specifically, assuming the length of Post FEC Padding is K bits and grouped by M bits, there are a total of Group data, where M <K。

[0060] Step S102: Perform a logical operation on each set of data and Cover codes (ie, cover codes) to obtain corresponding Post FEC Padding data. Each user uses different Cover codes to ensure that each user's Post FEC Padding data is different.

[0061] In this step, the specific logical operation can be any of the following: AND, OR, NOT, XOR, XNOR, NAND, and NOR. Furthermore, the Cover Codes here can be Hadamard codes or any other random codes. By having each user use a different Cover Code, each user's Post FEC Padding data can be unique.

[0062] In one embodiment, the logic operation is set to an exclusive OR operation. Figure 4 As shown, assuming Cover codes = [1, 0, 1, 0], the multiple groups of data obtained after grouping are processed as follows: the first group of M data are inverted, the second group of M data symbols remain unchanged, the third group of M data are inverted, and the fourth group of M data symbols remain unchanged.

[0063] Based on the same processing process, by performing logical processing operations, as long as the Covercodes used by each user are different, the Post FEC Padding data of each user can be ensured to be different. Here, it should be noted that Figure 4 In the example, Concatenation means connection.

[0064] In combination with the above-mentioned embodiment 1, in the Wi-Fi communication system, the Post FEC Padding data of each user is processed by a cover code, so that the Post FEC Padding data of each user is different. This prevents the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of Wi-Fi communication.

[0065] <Example 2>

[0066] like Figure 5 and Figure 6 As shown, Example 2 of this specification also provides a Post FEC Padding processing method for a WIFI system, which is used to process the Post FEC Padding data of each user, including step S201. Specifically,

[0067] Step S201: Scramble the Post FEC Padding data of each user using a scrambler to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

[0068] In practical applications, to reuse hardware resources, a 7th-order or 11th-order scrambler can be used for scrambling based on the same data domain. Of course, other-order scramblers, such as a 15th-order or 23rd-order scrambler, can also be used. Furthermore, the scrambler polynomial of this embodiment can also be any other-order m-sequence (longest linear feedback shift register sequence) or Gold sequence (pseudo-random sequence), as long as the scrambling process ensures that each user's Post FEC Padding data is unique.

[0069] In one embodiment, Figure 6 The figure shows the scrambling process of the scrambler. STA (Station) represents the terminal device; Init value represents the initial value of the scrambler; and iuser represents the user number. Figure 6 Only the terminal device STA is used for illustration. In practice, it can also be an AP device or a Soft AP device, as long as it has communication functions.

[0070] The specific scrambling code generating polynomial of the scrambler can be as follows:

[0071] S(x)=x 7 +x 4 +1 or

[0072] S(x)=x 11 +x 9 +1

[0073] Where x represents the bit involved in the operation in the scrambler, for example, x 4 Indicates that the value of the fourth shift register needs to participate in the operation, and S(x) represents the scrambler output.

[0074] In combination with the above-mentioned embodiment 2, in the Wi-Fi communication system, the Post FEC Padding data of each user is scrambled, so that the Post FEC Padding data of each user is different. This prevents the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of Wi-Fi communication.

[0075] <Example 3>

[0076] Based on the above embodiment 1, Figure 7 As shown, the method of this embodiment 3 may further include step S103 after steps S101 and S102. Specifically,

[0077] Step S103: The Post FEC Padding data obtained after the logical operation is further scrambled by a scrambler to ensure that the Post FEC Padding data of each user is different.

[0078] In this step, the scrambling process is the same as that in the above-mentioned embodiment 2, and will not be described in detail here.

[0079] In conjunction with this embodiment 3, in a Wi-Fi communication system, the Post FEC Padding data of each user is subjected to a cover code process and further scrambled, so that the Post FEC Padding data of each user is different. This prevents the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of Wi-Fi communication.

[0080] <Example 4>

[0081] Based on the above embodiment 2, Figure 8 As shown, the method of this embodiment 4 may further include steps S202 and S203 after step S201. Specifically,

[0082] Step S202: Group the Post FEC Padding data obtained after the scrambling process for each user to obtain multiple groups of data.

[0083] Step S203: Perform a logical operation on each set of data and Cover codes to ensure that the PostFEC Padding data of each user is different.

[0084] In this step, the process of data grouping and Cover codes processing is the same as that of the above embodiment 1, and will not be repeated here.

[0085] In conjunction with this embodiment 3, in a Wi-Fi communication system, the Post FEC Padding data of each user is scrambled and further covered with a code, so that the Post FEC Padding data of each user is different. This prevents the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of Wi-Fi communication.

[0086] Based on the method of the above embodiment 1, this embodiment of the specification provides a Post FEC Padding processing device for a Wi-Fi system, which is used to process the Post FEC Padding data of each user, including:

[0087] The grouping module is used to group the Post FEC Padding data of each user to obtain multiple groups of data.

[0088] The Cover codes processing module is used to perform a logical operation on each set of data and the Cover codes to obtain corresponding Post FEC Padding data. Each user uses a different Cover codes to ensure that the Post FEC Padding data of each user is different.

[0089] Based on the method of the above embodiment 2, this embodiment of the present specification provides a Post FEC Padding processing device for a Wi-Fi system, which is used to process the Post FEC Padding data of each user, including:

[0090] The scrambler is used to scramble the Post FEC Padding data of each user to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

[0091] In summary of all the above embodiments, the present application performs cover code processing or scrambling processing or both processing on the Post FECPadding data of each user in the WIFI communication system, so that the Post FECPadding data of each user is different, thereby avoiding the corresponding subcarriers from having the same phase when the data of multiple users are superimposed and sent, thereby avoiding data distortion and saturation, reducing the decoding bit error rate, and effectively improving the system performance of WIFI communication. It is particularly suitable for multi-user short packet OFDMA transmission scenarios, which can ensure that the Post FEC Padding data of each user is different, and can significantly improve the performance of the WIFI communication system. Of course, this method is also applicable to single-user transmission scenarios or data packet transmission scenarios of arbitrary length specified by the protocol. For single-user transmission, the data processing of this method can ensure the randomness of the Post FECPadding data. Similarly, this method is also applicable to non-OFDMA transmission scenarios, and can effectively improve the performance of the WIFI communication system.

[0092] In addition, the Post FEC Padding data of each user involved in this method may also use any random data, and it is only necessary to ensure that the Post FEC Padding data of each user is different.

[0093] Specifically, the simulation is performed using the scenarios of HEMU PPDU, AWGN (Additive White Gaussian Noise) channel, MCS11, 160M bandwidth, LDPC coding, multi-user OFDMA, and Pre FEC factor equal to 3. Figure 9 As shown, after the Cover codes processing or scrambling processing of this embodiment, the WIFI communication system obtains a gain of nearly 6 dB.

[0094] <Example 5>

[0095] Embodiment 5 of this specification also provides a communication system including an AP device, a soft AP device, and a terminal device, wherein any two of the AP devices, soft AP devices, and terminal devices can communicate with each other. During any communication process, any of the AP devices, soft AP devices, and terminal devices can execute the Post FEC Padding processing method of Embodiment 1 or Embodiment 2 to ensure that the user's Post FEC Padding data is random or unique, thereby improving the performance of the Wi-Fi communication system.

[0096] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A Post FEC Padding processing method for a WIFI system, characterized in that: The process for processing the Post FEC Padding data of each user includes the following steps: The Post FEC Padding data of each user is grouped and processed to obtain multiple groups of data; Perform a logical operation on each set of data and Cover codes to obtain corresponding Post FEC Padding data. Each user uses different Cover codes to ensure that the Post FEC Padding data of each user is different.

2. The method according to claim 1, characterized in that The step of grouping the Post FEC Padding data to obtain multiple groups of data includes: Assuming the length of Post FEC Padding is K bits and grouped by M bits, there are a total of Group data, where M <K。 3. The method according to claim 1, characterized in that The logic operation is any one of an AND operation, an OR operation, a NOT operation, an XOR operation, an XNOR operation, a NAND operation, and a NOR operation; and / or, The Cover codes may be Hadamard codes or any other random codes.

4. The method according to claim 1, wherein The following steps are also included: The Post FEC Padding data obtained after the logical operation is further scrambled by the scrambler to ensure that the Post FEC Padding data of each user is different.

5. A Post FEC Padding processing method for a WIFI system, characterized in that: The process for processing the Post FEC Padding data of each user includes the following steps: The Post FEC Padding data of each user is scrambled by a scrambler to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

6. The method according to claim 5, characterized in that Scrambling is performed using a 7th or 11th order scrambler based on the same data field, or, The polynomial of the scrambler may be any one of an m-sequence or a Gold sequence of other orders.

7. The method according to claim 5, characterized in that The scrambling code generating polynomial of the scrambler is: S(x)=x 7 +x 4 +1 or S(x)=x 11 +x 9 +1 Where x represents the bit involved in the operation in the scrambler, for example, x 4 Indicates that the value of the fourth shift register needs to participate in the operation, and S(x) represents the scrambler output.

8. The method according to claim 5, characterized in that The following steps are also included: The Post FEC Padding data obtained after scrambling for each user is grouped to obtain multiple groups of data; Perform logical operations on each set of data and Cover codes to ensure that the Post FEC Padding data of each user is different.

9. A Post FEC Padding processing device for a WIFI system, characterized in that: Used to process each user's Post FEC Padding data, including: The grouping module is used to group the Post FEC Padding data of each user to obtain multiple groups of data; The Cover codes processing module is used to perform a logical operation on each set of data and the Cover codes to obtain corresponding Post FEC Padding data. Each user uses a different Cover codes to ensure that the Post FEC Padding data of each user is different.

10. A Post FEC Padding processing device for a WIFI system, characterized in that: Used to process each user's Post FEC Padding data, including: The scrambler is used to scramble the Post FEC Padding data of each user to obtain corresponding Post FEC Padding data. Each user uses a different non-zero scrambling code initial value to ensure that the Post FEC Padding data of each user is different.

11. A communication system, characterized in that: It comprises an AP device, a soft AP device and a terminal device; the AP device, the soft AP device or the terminal device is used to execute the method according to any one of claims 1 to 8.

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