Method and apparatus for avoiding saturation in optical wireless point-to-point systems - Patents.com

Abstract

An apparatus 200 in a point-to-point optical wireless communication system, the apparatus including an optical receiver 210 configured to receive a signal, a power detector 202 configured to detect a signal strength of the received signal, a digital baseband module 203 configured to demodulate the received signal and measure a data rate of the received signal, and a controller 204 configured to derive gain setting adjustments in response to changes in the measured data rate when the detected signal strength is above a threshold.

Description

[Technical field]

[0001] The present invention relates to the field of optical wireless communications. In particular, various methods, apparatus, systems, and computer-readable media are disclosed herein relating to gain control in a point-to-point optical wireless communication system. [Background technology]

[0002] In recent years, a wide range of technological advances, including data collection, analytics, machine learning, and augmented reality, have spurred the rise of smart, automated factories. Industry 4.0 is the current trend of automation and data exchange in manufacturing technologies. It includes cyber-physical systems, the Internet of things, and cloud computing. Yet, connectivity remains a critical barrier to realizing the full potential of Industry 4.0. Even today's state-of-the-art factories rely heavily on existing radio frequency (RF)-based technologies, such as Wi-Fi. However, RF-based communication technologies have certain limitations in industrial environments where RF is either not tolerant or does not work well due to multipath arising from metal surfaces.

[0003] The emergence of advanced connectivity technologies could provide manufacturers with a reliable alternative. Optical wireless communication, especially Li-Fi point-to-point communication, is emerging as a reliable and high-speed alternative to RF communication in harsh industrial environments. This could enable critical communications such as wireless control of machines and manufacturing robots, unlocking the full potential of Industry 4.0. Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors recognize that for production line and automated machine use cases, one of the practical problems to be solved is that the distance between two devices that need to be interfaced may constantly change following the machine movements. Although the communication link itself may tolerate a certain level of pathloss variation, drastic changes may lead to deep saturation or breaking of the link. [Means for solving the problem]

[0005] In view of the above, the present disclosure relates to a method, apparatus, system, computer program, and computer readable medium for an advanced automatic gain control scheme in a point-to-point optical wireless communication system, where gain control decisions are not only based on received signal strength, but are also determined in correlation with changes in the actual data rate on the link. This is particularly useful when optimal receiver performance is achieved in the receiver saturation region. In contrast, conventional gain control approaches that rely purely on received signal strength can only achieve suboptimal receiver performance.

[0006] Among others, the object of the invention is achieved by an apparatus according to claim 1, a point-to-point optical wireless communication system according to claims 9 and 10, a method according to claim 11 and a computer program according to claim 12.

[0007] According to a first aspect of the present invention, there is provided an apparatus in a point-to-point optical wireless communication system, the apparatus including: an optical receiver configured to receive a signal, a power detector configured to detect a signal strength of the received signal, a digital baseband module configured to demodulate the received signal and to measure a data rate of the received signal, and a controller configured to derive a gain setting adjustment in response to a change in the measured data rate when the detected signal strength is above a threshold.

[0008] Point-to-point Optical Wireless Communications (OWC) supports high-speed communication between two remote devices, typically over a direct and unobstructed path, or line-of-sight path. OWC is a good alternative to wired communications in industrial environments and also reduces multipath effects compared to RF-based wireless communications. OWC systems may operate in the visible, infrared (IR), or ultraviolet (UV) spectrum.

[0009] The optical receiver is configured to receive and convert the optical signal into an electrical signal, and the power detector is used to detect the signal strength. The power detector may be called an energy detector. The received signal is demodulated and digitally decoded in the digital baseband module, which monitors the real-time data rate of the signal. If the received signal is deemed to exceed a certain threshold or enter a saturation region, the controller is configured to derive a gain setting adjustment based on a change in the measured data rate of the received signal. The threshold may be predefined by a user depending on the application scenario or hardware characteristics.

[0010] Beneficially, the controller is configured to derive a gain setting adjustment for gain reduction when the detected signal strength exceeds a certain threshold and the measured data rate decreases.

[0011] Compared to traditional gain control approaches, the gain adjustment does not purely rely on the detected signal strength, but also takes into account the change in data rate. This can be extremely beneficial in cases where the receiver can tolerate a certain level of saturation, in which the maximum data rate is achieved. Furthermore, in systems composed of discrete components, the linearity of individual components along different stages of the receiver chain may not be optimized at the system level. In some cases, it may be very complicated, or even impossible, to measure these parameters separately.

[0012] Thus, it is advantageous to determine such an optimal operating point by observing changes in the measured data rate. When the signal is strong, such as above a certain threshold, the achieved data rate is likely to experience a maximum that indicates the optimal operating point. The controller is therefore configured to derive a negative gain setting adjustment to condition an over-saturated received signal, which may result, for example, from two communication devices moving towards each other.

[0013] Advantageously, the optical receiver includes a photodiode and a transimpedance amplifier (TIA) configured to amplify an output of the photodiode, and the controller is configured to apply a gain setting adjustment to the TIA.

[0014] A photodiode is a semiconductor device that converts light into a current or voltage based on the device's mode of operation. Sometimes photodiodes are also called photo detectors, light detectors, or photo sensors. Photodiodes may vary in structure, may include optical filters, built-in lenses, and may have large or small surface areas. Photodiodes typically have slower response times as the surface area increases. Depending on the structure of the device, photodiodes can be categorized into different types, such as PN photodiodes, Schottky photodiodes, PIN photodiodes, and avalanche photodiodes. Although different types of photodiodes may function differently, the basic operation of these diodes remains the same.

[0015] A TIA is a type of current-to-voltage converter and is often used for sensors with a more linear current response than a voltage response. Because the output electrical signal from a photodiode is typically small, it is beneficial to amplify the signal from the photodiode to a signal with a larger swing and / or amplitude for further processing. Therefore, TIAs are very often used as first stage amplifiers to condition the received signal of the photodiode.

[0016] In a preferred setup, gain setting adjustments derived by the controller are applied to the TIA, so that the received signal can be conditioned to a suitable range for further digital processing.

[0017] Advantageously, the power detector has a larger dynamic range than the TIA.

[0018] Dynamic range, typically expressed in decibels (dB), is the ratio of the highest signal level that a circuit, component, or system can handle to the lowest signal level that it can handle. The lowest signal level is usually determined by the noise floor of the circuit, component, or system and the minimum required signal-to-noise ratio (SNR). The highest signal level is usually determined by the linearity of the circuit, component, or system so that the signal does not distort or saturate.

[0019] Considering commercially available products, the dynamic range of a TIA is typically quite limited. If two communication devices are too close to each other, the received signal will increase and the TIA at the receiver may enter the saturation region and cause clipping. In contrast, as a separate component, a dedicated power detector can usually tolerate a much stronger input signal compared to a TIA. Therefore, it is beneficial to use a power detector to accurately measure the signal strength.

[0020] In another example, the controller is configured to provide gain setting adjustments to an optical transmitter coupled to the device.

[0021] Instead of or in addition to applying a gain adjustment to a receiver chain, such as a TIA, it may be beneficial to apply a gain adjustment to a transmitter chain, such as an optical transmitter locally connected to the device. Thus, the local communication device is an optical transceiver that supports bidirectional optical communication, including both the device and the optical transmitter in the same housing. Such a gain adjustment mechanism assumes that the bidirectional optical link is symmetrical, and two remote devices may use the same or similar output power levels. In practice, this is a very common scenario, especially for point-to-point optical wireless communication. Therefore, once a gain setting adjustment is derived based on a first signal received by the device from a remote device, the controller may apply a gain adjustment to a co-located transmitter to transmit a second signal to the remote device.

[0022] Beneficially, the optical transmitter may include an optical front end including a light source and an amplifier. The amplifier is controlled to apply different gain settings to amplify the electrical signal driving the light source accordingly. The light source may be either a light emitting diode (LED), a laser diode, a vertical cavity surface emitting laser (VCSEL), or a hybrid front end including both an LED and a VCSEL. In this option, the controller of the device is configured to apply the gain setting adjustments directly to the amplifier of the optical transmitter.

[0023] In one example, the peak-to-average power ratio (PAPR) of the signal is at least 3 dB.

[0024] PAPR represents the square of the ratio of the peak amplitude to the root mean square (RMS) value of the signal. PAPR characterizes the signal in terms of its waveform and is thus sensitive to nonlinear and / or amplitude distortions. Advantageously, the signal received by the device has a PAPR of 3 dB or more, as is common for certain modulation formats such as 8PSK, OQPSK, 64QAM, OFDM, etc. The area of ​​the PAPR is also an indication of the modulation scheme applied to the signal. Higher order amplitude modulation typically results in a larger PAPR.

[0025] The disclosed scheme is extremely beneficial for signals with large PAPR. In a conventional gain control scheme based purely on received signal strength, the system will reduce the amplifier gain as long as the receiver detects saturation of the received signal, which is usually determined by the peak power of the signal. However, in a practical system, even if the peak power may saturate some components in the receiver chain, there is still some margin that allows the receiver to correctly demodulate and decode the signal. This operating region may contribute to the maximum throughput being achieved. In this way, performance may be improved.

[0026] Preferably the signal is by spread spectrum modulation.

[0027] Multi-carrier spread spectrum technology has the advantages of improved channel capacity and robustness against multi-user interference. The channel capacity can be further increased by adaptive bit loading, such as applying different orders of modulation to different subcarriers depending on the communication channel profile. Thus, it is the preferred modulation to be used in point-to-point optical wireless communication systems.

[0028] Advantageously, the signal is an orthogonal frequency-division multiplexing (OFDM) signal.

[0029] OFDM has a great advantage of being robust against harsh channel conditions, such as narrowband interference or frequency selective fading, and is therefore widely used as a digital multi-carrier modulation method in many communication systems. Also, by dividing the full band into multiple subcarriers, the system has the flexibility to apply different modulation and coding schemes to individual subcarriers, which can be used to maximize the capacity of the channel. In optical wireless communication, unipolar OFDM modulation techniques are typically adopted, such as ACO-OFDM, DCO-OFDM, ADO-OFDM and / or Flip OFDM.

[0030] In a preferred setup, the point-to-point optical wireless communication system is an OFDM-based multi-carrier system.

[0031] According to a second aspect of the present invention, there is provided a point-to-point optical wireless communication system, comprising an optical transmitting device configured to transmit a signal to a remote optical receiving device, the remote optical receiving device including an apparatus according to the present invention.

[0032] In a first possible setup, the disclosed gain control scheme is applied at a remote optical receiving device: Gain setting adjustments are derived by the device's controller based on the currently received signal, and the gain setting adjustments are then applied directly to the TIA in the receiver chain, thus applying real-time gain adjustments to the received signal.

[0033] In another setup, a point-to-point optical wireless communication system includes a first optical transceiver device including a first apparatus according to the present invention and a first optical transmitter connected thereto, and a second optical transceiver device including a second apparatus according to the present invention and a second optical transmitter connected thereto, the first optical transceiver device configured to transmit a first signal to the second optical transceiver device, the second optical transceiver device configured to receive the first signal and apply a gain setting adjustment derived from the first signal to the second optical transmitter to transmit another signal to the first optical transceiver device.

[0034] In this second possible setup, the disclosed gain control scheme is applied at the second optical transceiver device to transmit a new packet to the first optical transceiver. The gain setting adjustment is derived by the second optical transceiver device based on the first signal received earlier from the first optical transceiver. The underlying premise is that the first optical transceiver and the second optical transceiver have a bidirectional point-to-point link, and the bidirectional link is symmetric. Therefore, by applying the gain setting adjustment at the second optical transmitter to transmit another signal to the first optical transceiver device, the situation where the other signal saturates at the first optical transceiver device is avoided. Then, the same gain setting adjustment may also be applied to the TIA in the receive chain of the second optical transceiver device for receiving the first signal or any upcoming signal from the first optical transceiver device.

[0035] According to a third aspect of the present invention, there is provided an apparatus method in a point-to-point optical wireless communication system, the method including the apparatus receiving a signal, detecting a signal strength of the received signal, demodulating and measuring a data rate of the received signal, and deriving a gain setting adjustment in response to a change in the measured data rate if the detected signal strength is above a threshold.

[0036] The method further includes the device deriving a gain setting adjustment for gain reduction if the detected signal strength exceeds a threshold and the measured data rate decreases.

[0037] The present invention may further be embodied in a computer program comprising code means for causing the processing means to perform the apparatus methods disclosed in the present invention when said program is executed by an apparatus comprising processing means. [Brief description of the drawings]

[0038] In the drawings, like reference characters generally refer to the same parts throughout the different views and the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [Figure 1] 1 illustrates a bidirectional point-to-point communication link. [Diagram 2] This shows the change in throughput depending on the distance between two communicating devices. [Diagram 3] 1 shows a schematic of the basic components of the device. [Figure 4] 1 shows a schematic diagram of an example of the basic components of the device. [Diagram 5] 1 shows an example of a control loop for the device. [Figure 6] 4 shows another example of a control loop for the device. [Figure 7] 1 illustrates an example of a point-to-point communication system. [Figure 8]1 illustrates an example of a point-to-point communication system. [Figure 9] 1 shows a flow chart of a method of the apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The embodiments described below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and recognize applications of these concepts not specifically addressed herein. It should be understood that these concepts and applications are within the scope of the present disclosure.

[0040] The communication system is a point-to-point optical wireless communication system operating in optical bands such as visible, ultraviolet (UV), infrared (IR), etc. Figure 1 shows a simplified version of a Li-Fi or free-space-optical (FSO) point-to-point communication system consisting of two transceivers TRX1 and TRX2. Each transceiver includes a baseband module BB, which may be an ITU g.hn / g.vlc or IEEE compliant baseband, an optical receiver RX, an optical transmitter TX, and a connection to an external device such as an Ethernet connection ETH. Both transceiver units are aligned and separated by a distance d to establish a free-space optical or Li-Fi connection. One of the transceivers may be connected to a machine or device via a connection port such as an Ethernet port ETH, and the other transceiver may be located in another part of the same machine or device, or in a different machine or device that interfaces to an external network via a corresponding Ethernet port ETH.

[0041] If the distance d between the two transceivers is too small, such as on the order of cm, the received signal may enter a saturation region where the throughput drops rapidly, following the behavior depicted in Figure 2. As can be seen, as the distance decreases and the saturation region is entered, the throughput drops, but the signal strength does not drop and remains at a high level. Also, a particular throughput can correspond either to a distance within the saturation region or to a distance outside the saturation region where the throughput drops with distance (hence no adjustment is required). In the figure, points "a" and "b" show equal throughput or the same data rate, but in the case of point "a", the gain of the receiver or the opposing transmitter needs to be reduced to increase the throughput.

[0042] Therefore, to detect when a transceiver is at saturation distance, there are two possible approaches: A time-of-flight (ToF) sensor placed on one side of the device detects the actual distance. Although this solution is possible, it can be problematic if the devices are not perfectly aligned, as the ToF sensor may report incorrect measurements. Correlate the actual throughput or data rate with the received signal strength: if the signal strength is high or above a certain threshold but the throughput falls off, the distance between the transceivers is in the saturation zone and thus the gain needs to be reduced.

[0043] Therefore, the present invention addresses the problem of receiver saturation in point-to-point Li-Fi or FSO communication systems when two devices are too close and the received power is too high, for example applicable in an industrial setup where two segments of an automated machine need to be connected by a fast and reliable connection, and the variation of the path loss between these two devices is very large, and at a certain point, the distance between the devices is too short, causing the data rate to drop due to saturation.

[0044] On the other hand, it is also desirable to approach the optimum operating point where the data rate is maximized, such as near the reflection point of the curve as shown in Figure 2. Considering that the receiver can tolerate a certain level of saturation of the received signal and the optimum operating point is located in the saturation zone, it is advantageous for the device disclosed in this invention to determine the gain adjustment by correlating the received signal strength with the change in the actual throughput or data rate.

[0045] 3 shows a schematic of the basic components of the device 200. The device 200 includes at least an optical receiver 210, a power detector 202, a digital baseband module 203, and a controller 204. The controller 204 may be a low-power processor or controller, such as a microcontroller (MCU). The optical receiver 210 is configured to receive a signal and provides the signal to the digital baseband module 203. The digital baseband module 203 is configured to demodulate the received signal and measure the data rate of the received signal. Meanwhile, the power detector 202 is configured to detect the signal strength. Using information about the signal strength and the measured data rate, the controller 204 is configured to derive a gain setting adjustment in response to a change in the measured data rate when the detected signal strength is above a certain threshold.

[0046] Another example of the basic components of the device 200 is shown in FIG. 4, where the optical receiver 210 includes a photodiode (PD) 211 and a transimpedance amplifier (TIA) 212. In some cases, the photodiode 211 is also called a photodetector, a light detector, or a photosensor. The photodiode may include an optical filter and a built-in lens. Depending on the structure of the device, the photodiode can be classified into different types, such as PN photodiodes, Schottky photodiodes, PIN photodiodes, and avalanche photodiodes. The TIA 212 is configured to amplify the electrical output of the photodiode or photodetector 211. In this example, the controller 204 is further configured to apply a gain setting adjustment to the TIA 212. Thus, the gain of the receiver chain is adjusted accordingly.

[0047] FIG. 5 shows a more detailed example of the control loop of the device 200. The photodiode 211 receives the optical signal, which is amplified by the subsequent TIA 212 before reaching the digital baseband module BB 203. The power detector 202 detects the signal strength, and the value is read by the controller 204 using an internal or external analog-to-digital converter (ADC) (not shown). The digital baseband module BB 203 measures the data rate or throughput of the PHY layer and sends it to the controller 204. The connection between the digital baseband module 203 and the controller may be via a wired communication protocol (e.g., UART) or simple GPIO value coding. The controller 204 then judges depending on the signal strength and the value of the measured PHY data rate to determine whether the system is in the saturation zone. If so, the controller 204 applies a gain setting adjustment or correction to the gain of the TIA 212 to avoid deep saturation. As a result, the throughput or data rate remains near the maximum point of the curve as shown in FIG. 2, or near the maximum level. Thus, the system performance is optimized, which solves a common problem in optical receiver chains where the TIA 212 saturates before the data rate reaches its highest level, given that the photodiode 211 has a much higher dynamic range than the TIA.

[0048] FIG. 6 shows another example of the control loop of the apparatus 200. In this example, it is assumed that the link between two remote devices is symmetrical when the optical beams are aligned. When saturation of the received signal is detected, instead of applying a gain adjustment to the TIA, the controller 204 is configured to apply a gain adjustment to an optical transmitter connected to the apparatus 200. Thus, less power is received at the remote device, leading to avoiding saturation there. The optical transmitter includes at least an amplifier AMP and a light source. The light source may be either a light emitting diode (LED), a laser diode, a vertical cavity surface emitting laser (VCSEL), or a hybrid front end including both LED and VCSEL. Thus, a gain setting adjustment may be applied to the amplifier connected to the light source of the optical transmitter.

[0049] In a further example not shown, the controller 204 may be configured to apply gain setting adjustments simultaneously to both the TIA in the receiver chain and the amplifier in the transmitter chain, such as a combination of the examples shown in Figures 5 and 6. The advantage is that not only is the current reception performance improved at the local device, but also the reception performance of the remote peer device.

[0050] Fig. 7 shows an example of a point-to-point optical wireless communication system 100. The point-to-point optical wireless communication system 100 includes an optical transmitting device 110 configured to transmit a signal to a remote optical receiving device 120, which includes an apparatus 200 according to the invention. Gain setting adjustments derived from the received signal are applied directly to the receiving chain. Although only a unidirectional link is shown in the figure, this should not be understood as a limitation. The disclosed scheme may also be applied to bidirectional links.

[0051] Another example of a point-to-point communication system 100 is shown in Fig. 8. The point-to-point optical wireless communication system 100 comprises two identical communication devices, a first optical transceiver device 150 and a second optical transceiver device 160. Both devices 150, 160 comprise an apparatus 200 according to the invention and an optical transmitter 151, 161 connected thereto. In this example, a symmetric bidirectional link is assumed. As mentioned above, in this setup, the gain setting adjustments derived by the apparatus may be applied to the receiver chain, the transmitter chain, or both.

[0052] Thus, when the first optical transceiver device 150 transmits a first signal to the second optical transceiver device 160, the second optical transceiver device 160 receives the first signal and makes a gain setting adjustment derived from the first signal, to a second optical transmitter 161 for transmitting another signal to the first optical transceiver device 150, or to an optical receiver included in the second optical transceiver device 160 for further conditioning the received first signal or any incoming signal from the first optical transceiver device 150, or A combination of the previous two options by applying gain setting adjustments to both the second optical transmitter 161 and the optical receiver included in the second optical transceiver device 160; It is configured to apply.

[0053] If two remote communication devices with a bidirectional link implement the same scheme as disclosed, it may be necessary to coordinate between them to avoid instability that may be caused by both transceivers adjusting their transmit gain (instead of the TIA gain) at the same time when they react to a received signal.

[0054] 9 shows a flowchart of a method 500 of the apparatus 200 in the point-to-point optical wireless communication system 100. The method 500 includes the apparatus 200 receiving a signal in step S501, detecting a signal strength of the received signal in step S502, demodulating the received signal and measuring a data rate of the received signal in step S503, and deriving a gain setting adjustment in response to a change in the measured data rate if the detected signal strength is above a certain threshold in step S504.

[0055] The method according to the invention may be implemented in a computer as a computer implemented method, or in dedicated hardware, or in a combination of both.

[0056] The executable code for the method according to the invention may be stored on a computer / machine readable storage means. Examples of computer / machine readable storage means include non-volatile memory devices, optical storage media / devices, solid state media, integrated circuits, servers etc. Preferably, the computer program product comprises non-transitory program code means stored on a computer readable medium for performing the method according to the invention when said program product is run on a computer.

[0057] Methods, systems and computer readable media (transitory and non-transitory) may be provided for implementing selected aspects of the above-described embodiments.

[0058] The terms "program" or "computer program" are used herein in a general sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program one or more processors or controllers.

Claims

1. 1. An apparatus in a point-to-point optical wireless communication system, the apparatus comprising: an optical receiver configured to receive a signal; a power detector configured to detect a signal strength of a received signal; a digital baseband module configured to demodulate the received signal and to measure a data rate of the received signal; a controller configured to derive a gain setting adjustment for gain reduction when the detected signal strength exceeds a threshold indicating the detected signal strength enters a saturation region and the measured data rate decreases; 13. An apparatus comprising:

2. 2. The apparatus of claim 1, wherein the optical receiver includes a photodiode and a transimpedance amplifier (TIA) configured to amplify an output of the photodiode, and the controller is configured to apply the gain setting adjustment to the TIA.

3. The apparatus of claim 2 , wherein the power detector has a larger dynamic range than the TIA.

4. 4. The apparatus of claim 1, wherein the controller is configured to provide the gain setting adjustment to an optical transmitter connected to the apparatus.

5. 5. The apparatus of claim 1, wherein the peak-to-average power ratio (PAPR) of the signal is at least 3 dB.

6. 6. Apparatus according to any one of claims 1 to 5, wherein the signal is spread spectrum modulated.

7. 7. Apparatus according to any one of claims 1 to 6, wherein the signal is an Orthogonal Frequency Division Multiplexing (OFDM) signal.

8. an optical transmitting device configured to transmit a signal to a remote optical receiving device; The remote optical receiving device includes the apparatus of claim 1; A point-to-point optical wireless communication system comprising:

9. A first optical transceiver device including a first apparatus according to claim 4 and a first optical transmitter connected thereto; a second optical transceiver device including a second apparatus according to claim 4 and a second optical transmitter connected thereto; A point-to-point optical wireless communication system comprising: The first optical transceiver device is configured to transmit a first signal to the second optical transceiver device, the second optical transceiver device being receiving the first signal; and applying a gain setting adjustment derived from the first signal to the second optical transmitter to transmit another signal to the first optical transceiver device. A point-to-point optical wireless communication system configured as follows.

10. 1. A method for an apparatus in a point-to-point optical wireless communication system, the method comprising: Receiving a signal; and Detecting a signal strength of a received signal; demodulating the received signal and measuring a data rate of the received signal; deriving a gain setting adjustment for gain reduction when the detected signal strength exceeds a threshold indicating the detected signal strength enters a saturation region and the measured data rate decreases; and A method comprising:

11. A computing program comprising code means which, when said program is executed by an apparatus according to any one of claims 1 to 7, causes said apparatus to carry out the steps of the method according to claim 10.

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